JP2012047771A - Magnetic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner excellent in release property and in developing property after being left to stand for a long period of time in a high temperature environment, and excellent in developing stability in long-term use in high temperature and high humidity environment.SOLUTION: The toner is a magnetic toner comprising: magnetic toner particles containing at least a magnetic material, a binder resin and a release agent; and an inorganic fine powder. The magnetic toner particles are produced by a suspension polymerization method. The magnetic material is surface treated with a silane compound having a 3C or 4C hydrocarbon group having a branched structure. The binder resin contains, as a main component, a resin prepared by polymerization of an organic peroxide having a 3C or 4C hydrocarbon group having a branched structure. The organic peroxide is selected from peroxy dicarbonate and diacylperoxide.

Description

  The present invention relates to a magnetic toner used in a recording method using electrophotography or the like.

  Many methods are known as electrophotographic methods. Generally, an electrostatic latent image is formed on an electrostatic charge image carrier (hereinafter also referred to as a “photosensitive member”) by using a photoconductive substance by various means. Form. Next, the latent image is developed with toner to form a visible image, and if necessary, the toner image is transferred to a recording medium such as paper, and then the toner image is fixed on the recording medium by heat or pressure, etc. Is what you get.

  Examples of such an image forming apparatus include a copying machine and a printer. These image forming apparatuses are excellent in reproducibility of latent images and high resolution, and at the same time, there is a strong demand for higher speed and higher stability. For this purpose, various image forming methods have been proposed. One of them is magnetic toner, and a rotating sleeve having a magnetic pole at the center is used to fly between the photosensitive member and the sleeve by an electric field. A so-called jumping method is known. The jumping method is a developing method having high stability and is an effective method for meeting the above needs.

  However, if the speed of the apparatus is increased in the jumping method using such magnetic toner, the image density and image quality tend to become unstable. This is because factors such as an increase in the process speed of the apparatus makes it easy to raise the temperature inside the apparatus and a lack of heat application capability of the fixing device. For this reason, magnetic toner has stable development performance for a long period of time in a high temperature environment, and also exhibits excellent releasability from a fixing member such as a fixing roller or film even when the heat application ability of the fixing device is reduced. Is required.

  In addition, high performance is required for the storage stability of the magnetic toner. With the diversification of the usage environment and purpose of printers and copiers, the storage environment for cartridges is also diversifying. Under such circumstances, there is a case where after being used for a long time, it is left without being output for a while and is used again. Even in such a situation, it is required to exhibit stable performance.

  In order to improve the chargeability in an environment where temperature rise is assumed and the developability in long-term use, studies have been made on controlling the magnetic toner material and its dispersion state. Among them, a technique for reducing the environmental difference in the charge amount of the magnetic toner is disclosed by paying attention to the structure of the polymerization initiator used when the resin component of the magnetic toner is produced by polymerization (Patent Document 1). reference). In addition, a technique for controlling the molecular weight distribution by using two kinds of polymerization initiators and improving the durability performance of the magnetic toner is also disclosed (see Patent Document 2). However, these technologies still have room for improvement in terms of performance after being used for a long time.

  Further, with respect to the above-described problems, studies have been made focusing on the method and material for the hydrophobic treatment of the magnetic material surface.

  There are two typical hydrophobization treatment methods: wet treatment in water and dry treatment in the gas phase. The former is easy to cover the surface of the magnetic material uniformly, and the latter is very easy to treat. Because of its ease, dry processing has been studied conventionally, and techniques for various processing agents have been disclosed (see Patent Document 3). Moreover, the technique which vaporizes fluoroalkylsilane and / or alkoxysilane, processes, and controls water vapor | steam adsorption amount is also disclosed (refer patent document 4). However, even if such a magnetic material is used, a material satisfying the development stability that is assumed to be left after long-term use has not been obtained.

  Also disclosed is a technique for improving developability after being left in a harsh environment by controlling the circularity and magnetic force of the magnetic toner and the dispersibility of the magnetic substance in a solvent (see Patent Document 5). However, there remains room for improvement in terms of fog characteristics when left after long-term use.

JP 2006-343372 A JP 2007-086457 A JP 2004-294480 A JP 2000-327948 A JP 2001-343783 A

  The object of the present invention has been made in view of the above problems of the prior art. That is, it is an object of the present invention to provide a toner that is excellent in development stability in long-term use in a high-temperature and high-humidity environment and excellent in developability when left after long-term use.

In a magnetic toner having a magnetic material, a binder resin, a magnetic toner particle containing at least a release agent, and an inorganic fine powder,
The magnetic toner particles are produced by a suspension polymerization method,
The magnetic material has a surface treated with a silane compound containing a compound having a structure represented by formula (1) as a main component,
The binder resin contains, as a main component, a resin polymerized using an organic peroxide having a hydrocarbon group having a branched structure having 3 or 4 carbon atoms as a polymerization initiator,
The organic peroxide relates to a magnetic toner, wherein the organic peroxide is selected from peroxydicarbonate and diacyl peroxide.
Formula (1) R ₂ O — [— SiR ₁ (OR ₂ ) —O—] _m —R ₂ , 1 ≦ m ≦ 10
R ₁ : A hydrocarbon group having a branched structure having 3 or 4 carbon atoms.
R ₂ : a functional group represented by H or C _n H _{2n + 1} [1 ≦ n ≦ 4].

  It is possible to provide a toner having excellent development stability in long-term use in a high-temperature and high-humidity environment, and excellent developability when left after long-term use.

FIG. 2 is a schematic cross-sectional view illustrating an example of an image forming apparatus that can suitably use the toner of the present invention. ¹ is a schematic ¹ H-NMR chart of a silane compound. A schematic GPC chart of a silane compound.

A feature of the present invention is a magnetic toner having a magnetic toner, a binder resin, a magnetic toner particle containing at least a release agent, and an inorganic fine powder.
The magnetic toner particles are produced by a suspension polymerization method,
The magnetic material has a surface treated with a silane compound containing a compound having a structure represented by formula (1) as a main component,
The binder resin contains, as a main component, a resin polymerized using an organic peroxide having a hydrocarbon group having a branched structure having 3 or 4 carbon atoms as a polymerization initiator,
The organic peroxide is selected from peroxydicarbonate and diacyl peroxide.
Formula (1) R ₂ O — [— SiR ₁ (OR ₂ ) —O—] _m —R ₂ , 1 ≦ m ≦ 10
R ₁ : A hydrocarbon group having a branched structure having 3 or 4 carbon atoms.
R ₂ : a functional group represented by H or C _n H _{2n + 1} [1 ≦ n ≦ 4].

  According to the diligent study of the present inventors, it has been found that the above problem can be solved when the combination of the structure and type of the initiator used for the polymerization of the surface treatment agent of the magnetic substance and the binder resin is as described above. The invention has been completed.

  Below, the effect obtained by this invention is demonstrated in detail.

  The present inventors believe that the reason why the durable developability is increased by the above configuration is that the adhesion between the resin and the magnetic material is increased. As an index of adhesion, the present inventors used the moisture adsorption amount of the toner particles. In the case of a toner containing a magnetic material as in the present invention, water adsorption due to the magnetic material occurs, so that the degree of incorporation of the magnetic material into the resin can be estimated from the water adsorption amount of the toner. The combination of the magnetic substance and the polymerization initiator reduces the amount of moisture adsorbed, and the adhesion between the magnetic substance and the binder resin is increased, which is considered to have improved the durable developability.

  Further, the reason why the adhesiveness is increased is considered as follows. First, suspension polymerization is performed by dispersing a magnetic substance or other material in a polymerizable monomer such as styrene or butyl acrylate as described later, and then introducing a polymerization initiator to polymerize the monomer. In this method, toner particles are obtained using a binder resin. By incorporating hydrocarbon groups with 3 or 4 carbon atoms on the surface of the magnetic material and the polymerization initiator, the affinity of each other increases, and the starting point of the polymerization reaction becomes close to the magnetic material by becoming familiar with each other during suspension polymerization. This is presumed to be because the magnetic material was firmly incorporated into the resin.

  Here, according to the study by the present inventors, the adhesion tends to be remarkably increased when the hydrocarbon group has a branched structure. This is thought to be because the structural bulk of the surface of the magnetic material and the initiator is reduced by branching, and the magnetic material and the initiator are brought closer to each other, thereby improving the adhesion to the resin.

  The inventors of the present invention speculate that the reason why the development characteristics when left to stand after a long period of use due to the above configuration is increased is the dispersibility of the magnetic substance in the toner particles. It is expected that the magnetic substance and the initiator have a hydrocarbon group having 3 or 4 carbon atoms, so that they have high affinity and are adapted to suspension polymerization. Therefore, it is considered that the reaction starts near the magnetic surface. In ordinary suspension polymerization, the polymerization reaction proceeds randomly in the droplets formed from the polymerizable monomer, so that the viscosity in the droplets becomes non-uniform and secondary aggregation or segregation of the magnetic material occurs. Likely to happen.

  However, in the case of the system of the present invention, since the resin is formed around the magnetic material, the magnetic materials are unlikely to agglomerate and segregate, and the finely dispersed state is maintained in the toner. For this reason, it is presumed that good fog characteristics are exhibited even in a harsh environment from the viewpoint of chargeability and fluidity that are left after long-term use.

  The magnetic substance contained in the magnetic toner of the present invention is treated with a silane compound having a hydrocarbon group having a branched structure having 3 or 4 carbon atoms. From the viewpoint of adhesion, it is considered advantageous that both the magnetic substance and the polymerization initiator have a smaller number of carbon atoms. However, when applying a magnetic material to suspension polymerization, it is necessary to make the surface sufficiently hydrophobic in order to keep the magnetic material in a droplet formed of a polymerizable monomer. If the hydrophobicity is insufficient, it will migrate to the water outside the droplet. When the number of carbon atoms of the hydrocarbon group contained in the silane compound described above is 2 or less, the hydrophobicity is remarkably lowered, so that it is difficult to disperse in the polymerizable monomer, and the dispersion of the magnetic substance tends to be non-uniform. On the other hand, in the case of a straight chain structure having 5 or more carbon atoms or no branching, the durability developability is greatly lowered because the adhesion between the magnetic substance and the resin is lowered.

The magnetic toner of the present invention is produced using peroxydicarbonate or diacyl peroxide having a hydrocarbon group having a branched structure having 3 or 4 carbon atoms as a polymerization initiator. Peroxydicarbonate and diacyl peroxide have a structure in which hydrocarbon groups are present at both ends, so all the generated radical species have high affinity with magnetic substances, and the adhesion between magnetic substances and binder resin is improved. Increase. When a substance other than peroxydicarbonate or diacyl peroxide is used, the affinity may decrease due to the generation of multiple types of active terminals, or the binder resin composition itself may become non-uniform due to insufficient reactivity of the polymerization initiator. Therefore, the adhesiveness tends to decrease. Therefore, the performance is remarkably deteriorated from the viewpoint of durable developability. Further, when the number of carbon atoms is 2 or less, it is necessary to increase the affinity by setting the number of carbon atoms on the surface of the magnetic material to 2 or less. As a result, the magnetic material dispersibility is greatly disturbed due to insufficient hydrophobicity of the magnetic material. In addition, when only the hydrocarbon of the polymerization initiator has a carbon number of 2 or less and the magnetic material has a sufficient number of carbon atoms, the affinity is low and the adhesion is lowered, and the durable developability is low. descend. On the other hand, when the number of carbon atoms is 5 or more, the polymerization initiator becomes structurally bulky, so that adhesion is lowered and durability developability is lowered.

  Both the silane compound treated on the surface of the magnetic material used in the magnetic toner of the present invention and the hydrocarbon group of the polymerization initiator used have 3 or 4 carbon atoms and have a branched structure. This is to increase the affinity between the magnetic substance and the polymerization initiator. If one of the two has a different structure, the affinity is not exhibited and the effect of the present invention cannot be obtained. When the hydrocarbon groups are the same, it is preferable because the affinity is maximized, so that aggregation and segregation of the magnetic substance that occurs during suspension polymerization can be suppressed, and developability when left after long-term use is greatly improved.

  Regarding the adhesion between the magnetic material and the binder resin in the magnetic toner particles of the present invention, the water adsorption amount of the magnetic toner particles serves as an index as described above. If the amount of moisture adsorption is small, the magnetic substance is firmly taken into the binder resin and shows a high adhesion state. Specifically, it is preferable that the moisture adsorption amount per unit surface area of the magnetic toner particles is 1.40 or less because durability developability is excellent.

  The materials that can be used in the magnetic toner of the present invention are described below.

  The binder resin contained in the magnetic toner of the present invention contains, as a main component, a resin polymerized using an organic peroxide having a hydrocarbon group having a branched structure having 3 or 4 carbon atoms. The main component here refers to a component that occupies 80% or more of the binder resin.

  Examples of the binder resin used in the magnetic toner of the present invention include styrene such as polystyrene and polyvinyltoluene, and a homopolymer of a substituted product thereof, a styrene-propylene copolymer, a styrene-vinyltoluene copolymer, and a styrene-vinylnaphthalene copolymer. Polymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, Styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl Ethyl ether copolymer, steel Styrene-based copolymers such as styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, polymethyl methacrylate , Polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, and the like can be used, and these can be used alone or in combination. Among these, a styrene-acrylic resin made of a copolymer of styrene and an acrylic monomer is particularly preferable in terms of development characteristics.

  In the present invention, the physical properties of the binder resin in the magnetic toner have a great influence on the obtained effect. The preferred ranges for the physical properties of the binder resin are described below.

  According to the examination results of the present inventors, the peak molecular weight measured by gel permeation chromatography of the component extracted with tetrahydrofuran of the magnetic toner of the present invention is preferably 8000 to 18,000. Within this range, branching of the binder resin contained in the toner particles obtained by suspension polymerization is relatively small, so that the adhesion between the magnetic substance and the binder resin can be maintained high. Therefore, the tendency which is excellent in durable developability is seen.

  In addition, in the magnetic toner of the present invention, when an appropriate amount of a high molecular weight component in the binder resin, particularly a component that has been high molecular weight or cross-linked to a region insoluble in a solvent (hereinafter, gel content) is contained, There is a tendency that the durability developability tends to increase by increasing. Specifically, it is preferable that the insoluble content derived from the component of the binder resin when the Soxhlet extraction is performed using tetrahydrofuran of the magnetic toner is 15.0% by mass or more and 50.0% by mass or less. When the amount is 15.0% by mass or more, the development performance after long-term storage in a high temperature environment tends to be improved. Moreover, if the gel content is too much, segregation of the magnetic material is promoted and the dispersion state is disturbed, but if it is 50.0% by mass or less, the effect is exerted without any harmful effect, and there is a tendency to improve the development performance when left after long-term use It can be seen.

  On the other hand, the component having an extremely low molecular weight is preferably reduced as much as possible because the portion is weak against mechanical shock and becomes brittle. A preferred range is that the ratio of the molecular weight of 500 or less to the molecular weight of 1000000 or less in the chart of molecular weight distribution measured by gel permeation chromatography of the tetrahydrofuran-soluble content of the binder resin is 2.50% or less. Within this range, the peeling of the magnetic material caused by the partial brittleness of the resin was suppressed, and the durability developability tends to be excellent.

  In the present invention, the composition, production method, and physical properties of the magnetic material greatly affect the performance of the magnetic toner. Preferred ranges for the magnetic material that can be used in the present invention are described below.

  The magnetic toner of the present invention contains a magnetic material. The magnetic body is obtained by surface-treating an untreated magnetic body (hereinafter referred to as an untreated magnetic body), and the magnetic body that can be used in the present invention will be described below.

  The magnetic substance is mainly composed of magnetic iron oxide such as triiron tetroxide and γ-iron oxide, and may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. The shape of the magnetic body includes a polyhedron, an octahedron, a hexahedron, a sphere, a needle, and a scale. Preferred above.

  An unprocessed magnetic body can be manufactured by the following method, for example. An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equivalent to or greater than the iron component to the ferrous salt aqueous solution. Air was blown in while maintaining the pH of the prepared aqueous solution at 7.0 or higher, and ferrous hydroxide was oxidized while heating the aqueous solution to 70 ° C. or higher, and seed crystals serving as the core of the magnetic iron oxide particles were formed. First generate. Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. The pH of the liquid is maintained at 5.0 or higher and 10.0 or lower, and the reaction of ferrous hydroxide proceeds while blowing air, and magnetic iron oxide particles are grown with the seed crystal as a core. At this time, it is possible to control the shape and magnetic characteristics of the magnetic material by selecting an arbitrary pH, reaction temperature, and stirring conditions. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 5.0. An untreated magnetic material can be obtained by filtering, washing, and drying the magnetic material thus obtained by a conventional method.

In order to obtain the magnetic material of the present invention, it is necessary to perform a surface treatment with a silane compound mainly composed of a compound represented by the following formula (1). In addition, the main component said here refers to a component with the highest ratio among all the components.
Formula (1) R ₂ O — [— SiR ₁ (OR ₂ ) —O—] _m —R ₂ , 1 ≦ m ≦ 10
R ₁ : A hydrocarbon group having a branched structure having 3 or 4 carbon atoms.
R ₂ : a functional group represented by H or C _n H _{2n + 1} [1 ≦ n ≦ 4].

As shown in the above formula, R ₁ includes an isobutyl group, a tert-butyl group, a sec-butyl group, and an isopropyl group.

Examples of R ₂ include hydrogen, methyl group, ethyl group, propyl group, butyl group, etc. If hydrogen, methyl group, or ethyl group is used, the reactivity with the magnetic substance is high, and uniform treatment should be performed. Is preferable. Here, when m = 1, for example, there are three R _{2 s} , all of which need not be the same functional group, and there is no problem in carrying out the present invention as long as they are within the prescribed range of R ₂ .

  m is an integer of 1 or more and 10 or less, but preferably 5 or less from the viewpoint of processing uniformity and reactivity of the processing agent.

  Further, when n ≧ 1, the silane compound undergoes a condensation reaction with the surface of the magnetic substance through a hydrolysis step, but when n increases, the hydrolysis rate of the silane compound tends to decrease. For this reason, n is preferably 2 or less because reactivity tends to decrease. That is, preferred structures for R2 are hydrogen, methyl group, and ethyl group.

  The surface treatment of the magnetic material referred to in the present invention refers to a treatment performed for the purpose of imparting characteristics such as hydrophobicity to the magnetic material surface by reacting the magnetic material surface with a treating agent to give a chemical bond. Therefore, this is different from the treatment in which the treatment agent is simply sprayed or mixed on the magnetic material.

  There are two types of methods for surface treatment of magnetic materials, dry and wet. When the surface treatment is performed by a dry method, the silane compound is added to the washed, filtered and dried magnetic material, and the surface treatment is performed in the gas phase. When wet surface treatment is performed, after the oxidation reaction is completed, the dried product is redispersed, or after completion of the oxidation reaction, the iron oxide body obtained by washing and filtering is not dried but in another aqueous medium. And re-disperse to surface treatment. As a method for obtaining the magnetic material of the present invention, it is preferable to use a dry treatment method. This is considered as follows. In the dry method, since only a small amount of water is present in the reaction system, it is difficult to form a hydrogen bond between the hydrophilic group contained in the silane compound and water. When the hydrogen bond is formed, the reaction between the magnetic surface and the silane compound is hindered, so that an untreated portion or a portion with insufficient reaction is likely to be generated on the magnetic surface. Further, when the hydrophilic group of the treatment agent forms a hydrogen bond with water and adsorbs and reacts with the surface of the magnetic material while trapping water, the hydrophilic group remains on the surface of the magnetic material without being reacted. Since hydrophilic groups easily absorb water, the amount of moisture adsorbed by the magnetic material increases. Since the dry processing method can prevent such problems due to hydrogen bonding, it is easy to satisfy the performance required for the magnetic material of the present invention, and is a preferable method.

  When surface-treating a magnetic material by a dry method, it is preferable to use a hydrolyzate of alkoxysilane as described above because the uniformity of the treatment is greatly improved.

  Hydrolysis of the alkoxysilane can be performed, for example, by the following method.

  The alkoxysilane is gradually added to the aqueous solution whose pH is adjusted to 4 or more and 6 or less, and is stirred and dispersed uniformly using a disper blade, for example, and the dispersion time is adjusted so as to obtain a desired hydrolysis rate. Disassemble. When a dispersion apparatus capable of imparting high shear is used, the alkoxysilane forms an emulsion, so that the contact area between the alkoxysilane and water increases dramatically, and the hydrolysis can be performed stably. At this time, it is also important to adjust the pH during hydrolysis. When the pH is too high or too low, the condensation reaction between the silane compounds proceeds, or the hydrolysis hardly proceeds. In this way, an aqueous solution obtained by hydrolyzing the alkoxysilane is obtained.

  Next, a specific method of the dry process will be exemplified. Dry processing methods include a method of volatilizing a processing agent, a method of spraying using a device such as a spray dryer, and a method of stirring while applying a share using a device such as a Henschel mixer. Among them, the method of processing using a stirring device such as a Henschel mixer is preferable because it is simple and can be easily controlled to the physical properties of the magnetic material required by the present invention. When such a treatment method is used, a magnetic material in which a hydrolyzate of a silane compound is adsorbed on the surface can be obtained by adding the aqueous solution dropwise while dispersing an untreated magnetic material. Thereafter, the condensation reaction is allowed to proceed by heating, whereby a hydrophobized magnetic material is obtained.

  When the silane compound is used, it can be treated alone or in combination of a plurality of types. When using several types together, you may process separately with each silane compound, and may process simultaneously.

  When the alkoxysilane is used after being subjected to hydrolysis treatment, the affinity for the polymerization initiator is particularly increased when the hydrolysis rate is 80% or more, so that the surface treatment of the magnetic material can be made more uniform, and the durable developability. Is preferable. The method for obtaining and defining the hydrolysis rate of alkoxysilane will be described later.

  Moreover, it is preferable that the ratio (henceforth siloxane ratio) which exists as a siloxane among the hydrolyzed alkoxysilane in the said silane compound is 35% or less, More preferably, it is 30% or less. Here, siloxane refers to a compound having a silicon-oxygen-silicon bond. The method for obtaining and defining the siloxane ratio will be described later.

  Since siloxane is produced by a condensation reaction between hydrolyzed alkoxysilanes, it is bulkier than the hydrolyzed alkoxysilane alone. Therefore, it is important to keep the siloxane ratio low in order to uniformly treat the surface of the magnetic material and reduce the amount of moisture adsorbed and the amount of styrene eluted from the treated magnetic material. A siloxane ratio of 35% or less is preferable because the surface of the magnetic material is uniformly treated, the affinity with the polymerization initiator is increased, the adhesion is increased, and the durability developability is improved.

  In addition, the said siloxane rate can achieve the value within said range by adjusting the hydrolysis conditions of alkoxysilane suitably.

  It is important for the magnetic material used in the magnetic toner of the present invention to precisely control the polarity and composition of the surface, and it is preferable that the magnetic material is sufficiently covered with a silane compound. As an indicator of the coating state, solubility in hydrochloric acid can be mentioned. Specifically, the absorbance at a wavelength of 338 nm of the supernatant when dispersed in 2.7 (mol / L) hydrochloric acid and allowed to stand at 25 ° C. for 1 hour is preferably 6.00 or less. This condition of dissolving in hydrochloric acid for 1 hour is suitable for monitoring the treatment agent coating state on the surface of the magnetic material, and the above-described method is adopted in the present invention. When the absorbance at a wavelength of 338 nm of the supernatant when left at 25 ° C. for 1 hour is 6.00 or less, the affinity with the polymerization initiator is particularly increased, and segregation and aggregation of the magnetic substance during suspension polymerization are suppressed. In view of this, the development characteristics when left standing after long-term use tend to be improved, which is preferable.

In addition, since the surface of the magnetic material is a portion that is compatible with the polymerization initiator, it is necessary to reduce the number of unreacted treatment agents and treatment agent-free portions as much as possible. In either case, polar groups such as OH groups tend to increase on the surface of the magnetic material. As a technique for knowing them qualitatively, there is a method of measuring the amount of moisture adsorbed on a magnetic material. Specifically, when the amount of moisture adsorption per unit area of the magnetic material is 0.190 mg / m ² or less, the adhesion with the affinity between the magnetic material and the polymerization initiator increases, and the durability developability tends to increase. preferable.

  In the present invention, other colorants may be used in addition to the magnetic substance. Examples of the colorant that can be used in combination include magnetic or nonmagnetic inorganic compounds in addition to the above-described known dyes and pigments. Specifically, ferromagnetic metal particles such as cobalt and nickel, or alloys obtained by adding chromium, manganese, copper, zinc, aluminum, rare earth elements and the like to these. Examples thereof include particles such as hematite, titanium black, nigrosine dye / pigment, carbon black, and phthalocyanine. These are also preferably used by treating the surface.

  Examples of the release agent that can be used in the toner of the present invention include aliphatic hydrocarbon waxes and ester waxes. In the present invention, the ester wax only needs to have at least one ester bond in one molecule, and either natural wax or synthetic wax may be used.

Below, the wax which can be used is illustrated.
-Aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, and paraffin wax.
-Oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof.
-Waxes based on fatty acid esters such as carnauba wax, sazol wax, and montanic acid ester wax.
・ Deoxidized part or all of fatty acid esters such as deoxidized carnauba wax.
・ Saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid.
・ Unsaturated fatty acids such as brassic acid, eleostearic acid and valinalic acid, stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, seryl alcohol, melyl alcohol and other saturated alcohols, and polyhydric alcohols such as sorbitol .
-Fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide.
-Saturated fatty acid bisamides such as methylene bis stearamide, ethylene biscapric amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide.
Unsaturated fatty acid amides such as ethylene bis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide.
-Aromatic bisamides such as m-xylenebisstearic acid amide and N, N'-distearylisophthalic acid amide.
-Aliphatic metal salts such as calcium stearate, calcium laurate, zinc stearate, magnesium stearate (generally referred to as metal soap).
-Waxes grafted to aliphatic hydrocarbon waxes using vinyl monomers such as styrene and acrylic acid.
-A methyl ester compound having a hydroxyl group, obtained by partial esterification of a fatty acid and a polyhydric alcohol, such as behenic acid monoglyceride, hydrogenation of vegetable oils and the like.
-Long chain alkyl alcohol or long chain alkyl carboxylic acid having 12 or more carbon atoms.

  In the present invention, it is also one of preferred modes to use an ester wax and a hydrocarbon wax together if necessary.

  In the magnetic toner of the present invention, a charge control agent is preferably blended as necessary to improve charging characteristics. As the charge control agent, a known one can be used, but a charge control agent that has a high charging speed and can stably maintain a constant charge amount is particularly preferable. Among the charge control agents, specific examples of negative charge control agents include metal compounds of aromatic carboxylic acids such as salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, dicarboxylic acid, azo dyes or metal salts of azo pigments or Examples thereof include a metal complex, a polymer or copolymer having a sulfonic acid group, a sulfonic acid group, or a sulfonic acid ester group, a boron compound, a urea compound, a silicon compound, and a calixarene. Examples of the positive charge control agent include a quaternary ammonium salt, a polymer compound having the quaternary ammonium salt in the side chain, a guanidine compound, a nigrosine compound, and an imidazole compound.

  As a method for incorporating a charge control agent in the magnetic toner, a method of adding the toner inside the magnetic toner particles, or a magnetic toner by suspension polymerization, the polymer monomer composition is prepared before granulation. A method of adding a charge control agent is common. In addition, during the polymerization by forming oil droplets in water, or after polymerization, seed polymerization is performed by adding a polymerizable monomer in which the charge control agent is dissolved and suspended, thereby uniformizing the magnetic toner surface. It is also possible to cover it. In the case where an organometallic compound is used as the charge control agent, it is also possible to introduce these compounds by adding these compounds to the magnetic toner particles, mixing and stirring them with shearing.

  The magnetic toner of the present invention preferably has a core-shell structure in order to further improve the durability developability under high temperature and high humidity. This is because by having the shell layer, the surface property of the toner becomes uniform, the charging property becomes uniform, and the stress resistance increases. For this reason, it is preferable to use an amorphous high molecular weight body for the shell layer.

  The method for producing the magnetic toner of the present invention will be described below.

  The magnetic toner of the present invention is produced by a suspension polymerization method.

  The suspension polymerization method is a polymerizable monomer in which a polymerizable monomer and a colorant (in addition, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives as necessary) are uniformly dissolved or dispersed. A method for producing toner particles for obtaining a composition. Thereafter, the polymerizable monomer composition is dispersed in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer using an appropriate stirrer, and simultaneously subjected to a polymerization reaction, thereby obtaining a magnetic toner having a desired particle size. Particles are obtained. Since the magnetic toner particles obtained by this suspension polymerization method have an almost spherical shape for each magnetic toner particle, the distribution of charge amount is relatively uniform, so that it is possible to expect an improvement in durable developability.

  In the production of the magnetic toner particles according to the present invention, examples of the polymerizable monomer constituting the polymerizable monomer composition include the following.

  Examples of the polymerizable monomer include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-ethylstyrene, methyl acrylate, ethyl acrylate, Acrylate esters such as n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate , Methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, Methacrylic acid dimethyl aminoethyl, methacrylic acid esters such as diethylaminoethyl methacrylate and other acrylonitrile, methacrylonitrile, and the like monomers acrylamide. These monomers can be used alone or in combination. Among the above-mentioned monomers, styrene or a styrene derivative is preferably used alone or mixed with other monomers from the viewpoint of the development characteristics and durability of the magnetic toner.

  The binder resin contained in the magnetic toner of the present invention is polymerized using peroxydicarbonate or diacyl peroxide having a hydrocarbon group (such as sec-butyl group) having a branched structure having 3 or 4 carbon atoms. It is a thing.

  Specific examples of the polymerization initiator include diisopropyl peroxydicarbonate, disec-butyl peroxydicarbonate, isobutyryl peroxide and the like.

  In particular, when disec-butyl peroxydicarbonate is used, the affinity with the magnetic surface is maximized, so that the dispersion state of the magnetic material at the time of suspension polymerization is stabilized, and the development characteristics when left after long-term use are enhanced. Because there is a tendency, it is preferable.

  The addition amount of the polymerization initiator is preferably 0.5 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer.

  In the production of the magnetic toner particles of the present invention, a crosslinking agent can be added as necessary. A preferable addition amount is 0.01 parts by mass or more and 10.00 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer.

  Here, as the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, such as ethylene glycol diacrylate and ethylene glycol diacrylate. Carboxylic acid ester having two double bonds, such as methacrylate, 1,3-butanediol dimethacrylate, divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, divinyl sulfone, and three or more vinyl groups A compound is used alone or as a mixture of two or more.

  When the magnetic toner particles of the present invention are produced, a polymerizable monomer composition which is uniformly dissolved or dispersed by a dispersing machine such as a homogenizer, a ball mill, or an ultrasonic dispersing machine by appropriately adding the above-described toner composition or the like. The product is suspended in an aqueous medium containing a dispersion stabilizer. At this time, the particle size of the obtained toner particles becomes sharper by using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser to obtain a desired toner particle size at a stretch. The polymerization initiator may be added at the same time when other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Moreover, a polymerizable monomer or a polymerization initiator can be added immediately after granulation and before starting the polymerization reaction.

  After granulation, stirring may be performed using a normal stirrer to such an extent that the particle state is maintained and particle floating and sedimentation are prevented.

  When the magnetic toner particles of the present invention are produced, known surfactants, organic dispersants, and inorganic dispersants can be used as the dispersion stabilizer. In particular, inorganic dispersants are less likely to produce harmful ultrafine powders, and because of their steric hindrance, dispersion stability is obtained, so even if the reaction temperature is changed, stability is not easily lost, and washing is easy and does not adversely affect the toner. Therefore, it can be preferably used. Examples of such inorganic dispersants include tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, phosphate polyvalent metal salts such as hydroxyapatite, carbonates such as calcium carbonate and magnesium carbonate, calcium metasuccinate, calcium sulfate, Examples thereof include inorganic salts such as barium sulfate and inorganic compounds such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide.

  These inorganic dispersants are preferably used in an amount of 0.20 parts by mass or more and 20.00 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer. Moreover, the said dispersion stabilizer may be used independently and may use multiple types together. Further, a surfactant may be used in combination.

  When these inorganic dispersants are used, they may be used as they are, but in order to obtain finer particles, the inorganic dispersant particles can be generated and used in an aqueous medium. For example, in the case of tricalcium phosphate, a sodium phosphate aqueous solution and a calcium chloride aqueous solution can be mixed under high-speed stirring to produce water-insoluble calcium phosphate, which enables more uniform and fine dispersion. At the same time, water-soluble sodium chloride salt is produced as a by-product. However, if water-soluble salt is present in the aqueous medium, dissolution of the polymerizable monomer in water is suppressed, and ultrafine toner is generated by emulsion polymerization. This is more convenient.

  In the step of polymerizing the polymerizable monomer, the polymerization temperature is set to 40 ° C or higher, and generally 50 ° C to 90 ° C. As described above, in the present invention, it is desirable to control the molecular weight distribution of the binder resin formed by polymerizing the polymerizable monomer to be low and sharp. The polymerization temperature and the rate of temperature rise until reaching the polymerization temperature greatly contribute to the molecular weight distribution, and it is important to adjust these production conditions in order to control the molecular weight distribution.

  After completion of the above steps, the obtained polymer particles are filtered, washed and dried by a known method to obtain magnetic toner particles. The magnetic toner of the present invention can be obtained by mixing the magnetic toner particles with inorganic fine powder as will be described later, if necessary, and adhering them to the surface of the magnetic toner particles. It is also possible to insert a classification step in the manufacturing process (before mixing the inorganic fine powder) to cut coarse powder and fine powder contained in the magnetic toner particles.

The magnetic toner of the present invention has an inorganic fine powder. Silica, titanium oxide, alumina, etc. can be used as the inorganic fine powder used in the present invention. As the fine silica powder, for example, both a so-called dry method produced by vapor phase oxidation of silicon halide or dry silica called fumed silica, and so-called wet silica produced from water glass or the like can be used. is there. However, dry silica having fewer silanol groups on the surface and in the silica fine powder and less production residue such as Na ₂ O and SO ₃ ²⁻ is more preferable. In dry silica, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride and titanium chloride together with silicon halogen compounds in the production process, They are also included.

  In the present invention, it is preferable that the inorganic fine powder is a hydrophobized product because the environmental stability of the magnetic toner can be improved.

  The magnetic toner used in the present invention may further contain other additives, for example, a lubricant powder such as a polyfluorinated ethylene powder, a zinc stearate powder, a polyvinylidene fluoride powder, or a cerium oxide powder within a range that does not have a substantial adverse effect. Abrasives such as silicon carbide powder and strontium titanate powder, or fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder, anti-caking agents, and organic fine particles having opposite polarity and inorganic fine particles as developability improvers A small amount can be used. These additives can also be used after hydrophobizing the surface.

  The magnetic toner of the present invention can be used as a one-component developer by further mixing with other external additives (for example, a charge control agent) if necessary, and can be used as a two-component developer in combination with a carrier. be able to. As the carrier for use in the two-component development method, all conventionally known carriers can be used. Specifically, surface oxidized or unoxidized iron, nickel, cobalt, manganese, chromium, rare earth, etc. Particles having an average particle size of 20 μm or more and 300 μm or less, such as metals and their alloys or oxides, are preferably used.

  Next, an example of an image forming apparatus that can suitably use the magnetic toner of the present invention will be described in detail with reference to FIG. In FIG. 1, reference numeral 100 denotes an electrostatic latent image carrier (hereinafter also referred to as a photoconductor), which includes a charging roller 117, a developing device 140 having a toner carrier 102, a transfer charging roller 114, a cleaner 116, and a register roller. 124 etc. are provided. The electrostatic latent image carrier 100 is charged to, for example, −600 V by the charging roller 117 (applied voltages are, for example, an AC voltage of 1.85 kVpp and a DC voltage of −620 Vdc). Then, exposure is performed by irradiating the electrostatic latent image carrier 100 with the laser beam 123 by the laser generator 121, and an electrostatic latent image corresponding to the target image is formed. The electrostatic latent image on the electrostatic latent image carrier 100 is developed with a one-component toner by the developing device 140 to obtain a toner image, and the toner image is transferred in contact with the electrostatic latent image carrier via a transfer material. The image is transferred onto the transfer material by the roller 114. The transfer material on which the toner image is placed is conveyed to the fixing device 126 by the conveying belt 125 or the like and fixed on the transfer material. In addition, the toner remaining on the electrostatic latent image carrier is partially cleaned by the cleaner 116.

  Next, a method for measuring each physical property related to the magnetic toner of the present invention will be described.

(1) Method for Measuring Moisture Adsorption Amount per Unit Area of Magnetic Material and Magnetic Toner Particles The amount of water adsorption per unit area of the magnetic material and magnetic toner particles in the present invention is the BET specific surface area and the amount of water adsorption of the magnetic material used. Measure and calculate using those values. Specifically, the water adsorption amount per unit weight obtained in [2] is divided by the BET specific surface area obtained in [1] to calculate.

[1] BET measurement of magnetic substance and magnetic toner particles The BET specific surface area was measured using a degassing device Bacuprep 061 (manufactured by Micromesotic) and a BET measuring device Gemini 2375 (manufactured by Micromesotic). . The BET specific surface area in the present invention is a value of a multipoint BET specific surface area. Specifically, the procedure is as follows.

  After measuring the mass of the empty sample cell, 2.0 g of the magnetic material and 1.0 g of the magnetic toner particles are weighed and filled. Furthermore, the sample cell filled with the sample is set in the degassing apparatus, and degassing is performed at room temperature for 12 hours. After completion of degassing, the mass of the entire sample cell is measured, and the accurate mass of the sample is calculated from the difference from the empty sample cell. Next, empty sample cells are set in the balance port and analysis port of the BET measuring apparatus. A dewar bottle containing liquid nitrogen is set at a predetermined position, and P0 is measured by a saturated vapor pressure (P0) measurement command. After the P0 measurement is completed, the sample cell prepared for degassing is set in the analysis port, and after inputting the sample mass and P0, the measurement is started by the BET measurement command. After that, the BET specific surface area is automatically calculated.

[2] Measurement of moisture adsorption amount of magnetic substance and magnetic toner particles In the measurement of moisture adsorption amount, first, the measurement sample was left in an environment of 30 ° C. and 80% humidity for 72 hours, and then measured by the following measuring device.

  The moisture adsorption amount was measured using a moisture measuring device manufactured by Hiranuma Sangyo Co., Ltd. Specifically, the moisture content in the magnetic substance and magnetic toner particles is measured by Karl Fischer coulometric titration using a trace moisture analyzer AQ-2100, automatic heating precious moisture measurement system AQS-2320, and automatic moisture vaporizer SE320. Was measured.

  The measurement conditions are described below. As a measurement method, a waiting time (INTERVAL) control method was adopted. The setting time was 40 seconds, the heating temperature was 120 ° C., the amount charged when measuring the magnetic material was 2.0 g, and 1.0 g for the magnetic toner particles. In addition, the moisture adsorption amount per unit weight is obtained by this measurement.

(2) Method for Measuring THF-Insoluble Content About 1.5 g of magnetic toner is weighed (W1 g) and placed in a pre-weighed cylindrical filter paper (for example, product name No. 86R (size 28 × 100 mm), manufactured by Advantech Toyo). Set in a Soxhlet extractor. Extraction is performed for 20 hours using 200 ml of tetrahydrofuran (THF) as a solvent, and extraction is performed at a reflux rate so that the extraction cycle of the solvent is about once every 5 minutes.

  After the extraction is completed, the cylindrical filter paper is taken out and air-dried, and then vacuum-dried at 40 ° C. for 8 hours. The mass of the cylindrical filter paper including the extraction residue is weighed, and the mass of the extraction residue ( W2g) is calculated.

Next, content (W3g) of components other than a resin component is calculated | required in the following procedures. About 2 g of toner is weighed (Wag) into a 30 ml magnetic crucible weighed in advance. Put the crucible in an electric furnace, heat at about 900 ° C for about 3 hours, let cool in the electric furnace, let it cool in a desiccator at room temperature for more than 1 hour, weigh the mass of the crucible containing the incineration residual ash, and crucible The incineration residual ash content (Wbg) is calculated by subtracting the mass of. And the mass (W3g) of the incineration residual ash content in the material W1g is calculated by the following formula (A).
W3 = W1 × (Wb / Wa) (A)

In this case, the THF-insoluble matter is determined by the following formula (B).
THF insoluble matter (mass%) = {(W2-W3) / (W1-W3)} × 100 (B)

(3) Measurement of molecular weight of magnetic toner The molecular weight distribution of the THF soluble part of the magnetic toner is measured by gel permeation chromatography (GPC) as follows.

First, a sample is dissolved in tetrahydrofuran (THF) at room temperature over 24 hours. The obtained solution is filtered through a solvent-resistant membrane filter “Maescho Disc” (manufactured by Tosoh Corporation) having a pore diameter of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of the component soluble in THF is about 1.0% by mass. Using this sample solution, measurement is performed under the following conditions.
Apparatus: HLC8120 GPC (detector: RI) (manufactured by Tosoh Corporation)
Column: Seven series of Shodex KF-801, 802, 803, 804, 805, 806, 807 (manufactured by Showa Denko KK)
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 ml / min
Oven temperature: 40.0 ° C
Sample injection volume: 0.10 ml

  In calculating the molecular weight of the sample, standard polystyrene resin (for example, trade name “TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F— 10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500 ", manufactured by Tosoh Corporation) are used. In the obtained molecular weight distribution chart, the peak top molecular weight at which the intensity of the distribution derived from the binder resin component is the maximum was defined as the “peak molecular weight” of the present invention. Further, in a region having a molecular weight of 1,000,000 or less, the chart was divided at a point corresponding to a molecular weight of 500, and the area ratio of the portion of 500 or less to the total area value of the molecular weight distribution was calculated to obtain a ratio of the molecular weight of 500 or less.

(4) Absorbance measurement of magnetic substance with hydrochloric acid eluate The elution of magnetic substance with hydrochloric acid was measured as follows.

In a glass vial, 8 g of hydrochloric acid having a concentration of 2.7 mol / L (“Contaminone N” as a dispersing agent (neutral detergent for cleaning a precision measuring instrument having a pH of 7 consisting of a nonionic surfactant, an anionic surfactant and an organic builder, 1 g of magnetic material was added to 0.16 g (made by Wako Pure Chemical Industries, Ltd.). Then, dispersion is performed for 5 minutes using an ultrasonic disperser. In addition, as an ultrasonic disperser, two oscillators having an oscillation frequency of 50 kHz are incorporated in a state where the phase is shifted by 180 degrees, and an ultrasonic disperser “Ultrasonic Dispensing System Tetora 150” having an electrical output of 120 W (manufactured by Nikka Bios) Use water with ion-exchanged water in the tank.
After ultrasonic dispersion, the mixture was allowed to stand at 25 ° C. for 1 hour, and then the supernatant other than the magnetic substance was extracted and diluted 4-fold with 2.7 mol / L hydrochloric acid.

  The quartz cell containing the diluted solution is set in a spectrophotometer “MPS2000” (manufactured by Shimadzu Corporation), and the state is maintained for 10 minutes, and the change in transmittance is awaited. After 10 minutes, the absorbance at a measurement wavelength of 338 nm is measured.

(5) Average particle size and particle size distribution of magnetic toner The weight average particle size (D4) of the magnetic toner of the present invention is a precision particle size distribution measuring apparatus “Coulter Counter Multisizer equipped with a pore electric resistance method having an aperture tube of 100 μm. 3 ”(registered trademark, manufactured by Beckman Coulter) and attached dedicated software“ Beckman Coulter Multisizer 3 Version 3.51 ”(manufactured by Beckman Coulter, Inc.) for measurement condition setting and measurement data analysis, Measurement was performed with 25,000 effective measurement channels, and the measurement data was analyzed and calculated.

  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, dedicated software was set up as follows.

  In the “Standard Measurement Method (SOM) Change Screen” of the dedicated software, set the total count in the control mode to 50000 particles, set the number of measurements once, and set the Kd value to “standard particles 10.0 μm” (Beckman Coulter, Inc.) Set the value obtained using The threshold and noise level are automatically set by pressing the threshold / noise level measurement button. Also, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II, and the aperture tube flash 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 placed 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 rpm. Then, dirt and bubbles in the aperture tube are removed by the “aperture flush” function of the analysis software.
[2] About 30 ml of the electrolytic aqueous solution was placed in a glass 100 ml flat bottom beaker, and “Contaminone N” (nonionic surfactant, anionic surfactant, organic builder consisting of an organic builder as a dispersant was precisely measured. About 0.3 ml of a diluted solution obtained by diluting a 10% by weight aqueous solution of a neutral detergent for washing a vessel (made by Wako Pure Chemical Industries, Ltd.) 3 times with ion exchange water is added.
[3] Two oscillators with an oscillation frequency of 50 kHz are incorporated in a state where the phase is shifted by 180 degrees, and placed in a water tank of an ultrasonic disperser “Ultrasonic Dissipation System Tetora 150” (manufactured by Nikki Bios) with an electrical output of 120 W. A fixed amount of ion-exchanged water is added, and about 2 ml of the above-mentioned Contaminone N is added to this 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] The electrolyte solution of [5] in which the toner is dispersed is dropped using a pipette into the round bottom beaker of [1] installed in the sample stand, 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. Note that the analysis / volume statistics (arithmetic value when graph / volume% is set with the dedicated software) The “average diameter” on the (average) screen is the weight average particle diameter (D4).

(6) Method for Measuring Hydrolysis Rate of Silane Compound The hydrolysis rate of the silane compound is described. When the alkoxysilane is subjected to a hydrolysis treatment, a mixture composed of a hydrolyzate, an unhydrolyzed product, and a condensate is obtained. Described below is the ratio of hydrolyzate in the resulting mixture. This mixture corresponds to the silane compound described above.

First, the alkoxysilane hydrolysis reaction will be described by taking methoxysilane as an example. When methoxysilane is hydrolyzed, the methoxy group becomes a hydroxyl group and methanol is produced. Therefore, the progress of hydrolysis can be known from the quantitative ratio of methoxy group and methanol. In the present invention, the quantitative ratio was measured by ¹ H-NMR (nuclear magnetic resonance) to determine the hydrolysis rate. A schematic diagram is shown in FIG. Taking methoxysilane as an example, specific measurement and calculation methods are shown below.

First, ¹ H-NMR (nuclear magnetic resonance) of methoxysilane before being subjected to hydrolysis treatment was measured using deuterated chloroform, and the peak position derived from the methoxy group was confirmed. Thereafter, hydrolysis treatment was performed on methoxysilane to obtain a silane compound, and the hydrolysis reaction was stopped by setting the silane compound aqueous solution just before being added to the untreated magnetic substance to pH 7.0 and a temperature of 10 ° C. . Water in the obtained aqueous solution was removed to obtain a dried silane compound. A small amount of deuterated chloroform was added to the dried product, and 1H-NMR was measured. The peak derived from the methoxy group in the obtained spectrum was determined based on the peak position confirmed in advance. The peak area derived from the methoxy group was defined as A, and the peak area derived from the methyl group of methanol was defined as B, and the hydrolysis rate was determined by the following equation.
Hydrolysis rate (%) = B / (A + B) × 100

The measurement conditions for ¹ H-NMR were set as follows.
Measuring apparatus: FT NMR apparatus JNM-EX400 (manufactured by JEOL Ltd.)
Measurement frequency: 400MHz
Pulse condition: 5.0μs
Frequency range: 10500Hz
Integration count: 1024 times Measurement temperature: 40 ° C

(7) Method for measuring abundance ratio of siloxane in hydrolyzed alkoxysilane The ratio (siloxane ratio) present as siloxane in alkoxysilane is the ratio of the condensate in the silane compound. When this condensate ratio is high, as described above, uniform treatment is hindered when the magnetic material is surface-treated.

  The amount of the compound in the silane compound is measured by gel permeation chromatography (GPC) as follows. In advance, the GPC of the alkoxysilane that has not been subjected to hydrolysis treatment is measured and the retention time is confirmed.

Using acetic acid, triethylamine and ion-exchanged water, 70% by volume of an aqueous solution adjusted to the same pH as the silane compound to be measured and 30% by volume of acetonitrile were mixed to prepare an eluent. At this time, when measuring the alkoxysilane which has not hydrolyzed, it adjusted by adjusting pH to 7-8. Next, the silane compound to be measured was sufficiently dissolved in the eluent so as to be 10% by volume, and GPC was measured as a measurement sample.
Apparatus: HLC8120 GPC (detector: RI) (manufactured by Tosoh Corporation)
Column: GF-310-HQ (made by Showa Denko KK)
Flow rate: 1.0 ml / min
Oven temperature: 40.0 ° C
Sample injection volume: 25 μL

  Subsequently, a method for calculating β and γ from the GPC result of the silane compound will be described below.

  When the silane compound is measured by GPC, a chart schematically shown in FIG. 3 is obtained. FIG. 3 shows a chart before (upper) and after (lower) the hydrolysis treatment, and the upper schematic diagram shows a GPC chart obtained by measuring alkoxysilane before the hydrolysis treatment. The lower schematic diagram shows a GPC chart in which alkoxysilane is hydrolyzed and alkoxysilane, hydrolyzate, and siloxane are present. Peak assignments are also shown on the schematic diagram.

In the obtained chart, the total area of the peak derived from the silane compound was β, and the area of the peak corresponding to siloxane which is a hydrolyzed alkoxysilane condensate was γ. Using these β and γ, the siloxane ratio was defined as follows.
Siloxane ratio (%) = 100 × γ / β

(8) Measurement of Glass Transition Point of Amorphous Polyester The glass transition point (Tg) of amorphous polyester is measured according to ASTM D3418-82 using a differential scanning calorimetric analyzer “Q1000” (manufactured by TA Instruments). .

  The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium.

  Specifically, about 5 mg of amorphous polyester is precisely weighed and placed in an aluminum pan, and an empty aluminum pan is used as a reference. Measurement is performed at ° C / min. In this temperature rising process, a specific heat change is obtained in the temperature range of 40 to 100 ° C. At this time, the glass transition temperature Tg is defined as the intersection of the intermediate point line of the baseline before and after the specific heat change and the differential heat curve.

(9) Molecular weight measurement of amorphous polyester The molecular weight distribution of the THF-soluble matter of the amorphous polyester and the release agent is measured in the same manner as the molecular weight measurement of the binder resin using gel permeation chromatography (GPC). . The number average molecular weight (Mn) obtained by the measurement was taken as the molecular weight of the amorphous polyester.

(10) Measurement of acid value of amorphous polyester The acid value is the number of mg of potassium hydroxide necessary to neutralize the acid contained in 1 g of the sample. The acid value of the binder resin is measured according to JIS K 0070-1966. Specifically, it is measured according to the following procedure.

[1] Preparation of Reagent 1.0 g of phenolphthalein is dissolved in 90 ml of ethyl alcohol (95 vol%), and ion exchange water is added to make 100 ml to obtain a “phenolphthalein solution”.

  7 g of special grade potassium hydroxide is dissolved in 5 ml of water, and ethyl alcohol (95 vol%) is added to make 1 l. In order to avoid contact with carbon dioxide, etc., it is placed in an alkali-resistant container and allowed to stand for 3 days, followed by filtration to obtain a “potassium hydroxide solution”. The obtained potassium hydroxide solution is stored in an alkali-resistant container. The orientation is performed according to JIS K 0070-1996.

[2] Operation (A) Main test 2.0 g of the pulverized amorphous polyester sample is precisely weighed in a 200 ml Erlenmeyer flask, and 100 ml of a mixed solution of toluene / ethanol (2: 1) is added and dissolved over 5 hours. To do. Subsequently, several drops of the phenolphthalein solution is added as an indicator, and titration is performed using the potassium hydroxide solution. The end point of titration is when the light red color of the indicator lasts for about 30 seconds.
(B) Blank test Titration is performed in the same manner as above except that no sample is used (that is, only a mixed solution of toluene / ethanol (2: 1) is used).

[3] The acid value is calculated by substituting the obtained result into the following equation.
A = [(BC) × f × 5.61] / S
Here, A: acid value (mgKOH / g), B: addition amount (ml) of a potassium hydroxide solution in a blank test, C: addition amount (ml) of a potassium hydroxide solution in this test, f: potassium hydroxide Solution factor, S: sample (g).

(11) Measurement of Maximum Endothermic Peak Temperature of Release Agent The peak temperature of the maximum endothermic peak of the release agent is measured according to ASTM D3418-82 using a differential scanning calorimeter “Q1000” (manufactured by TA Instruments). .

  The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium.

  Specifically, about 5 mg of the mold release agent is precisely weighed, put in an aluminum pan, an empty aluminum pan is used as a reference, and a temperature rising rate is 10 ° C. between a measuring range of 30 to 200 ° C. Measure at / min. In the measurement, the temperature is once raised to 200 ° C., subsequently lowered to 30 ° C., and then the temperature is raised again. The maximum endothermic peak temperature of the DSC curve in the temperature range of 30 to 200 ° C. in the second temperature raising process was defined as the maximum endothermic peak temperature.

  Hereinafter, the present invention will be described more specifically with reference to production examples and examples. In addition, all the parts in the following mixing | blending show a mass part.

<Manufacture of untreated magnetic material>
In a ferrous sulfate aqueous solution, 1.0 equivalent or more and 1.1 equivalent or less of caustic soda solution with respect to iron element, and 1.5 mass% sodium silicate in terms of silicon element with respect to iron element are mixed, and water An aqueous solution containing ferrous oxide was prepared.

  While maintaining the aqueous solution at pH 9.0, air was blown in, and an oxidation reaction was performed at 80 ° C. or higher and 90 ° C. or lower to prepare a slurry liquid for generating seed crystals.

  Subsequently, the ferrous sulfate aqueous solution was added to this slurry liquid so that it might become 1.0 equivalent with respect to the original alkali amount (sodium component of caustic soda). Thereafter, the slurry liquid was maintained at pH 8.0, and an oxidation reaction was promoted while air was blown to obtain a slurry liquid containing magnetic iron oxide. The slurry was filtered and washed, and then filtered again. Thereafter, crushing and drying were performed to obtain an untreated magnetic material.

<Preparation of Silane Compound 1>
20 parts of isobutyltrimethoxysilane was added dropwise with stirring to 80 parts of ion exchange water. Thereafter, this aqueous solution is maintained at pH 5.5 and a temperature of 40 ° C., and dispersed by using a disper blade at 0.46 m / s for 2 hours for hydrolysis, and silane compound 1 which is an aqueous solution containing a hydrolyzate is obtained. Obtained. The physical properties of the obtained silane compound 1 are shown in Table 1.

<Preparation of Silane Compounds 2 to 11>
In the production of silane compound 1, using the alkylalkoxysilane described in Table 1, the hydrolysis rate and siloxane ratio described in Table 1 were adjusted by adjusting the hydrolysis time and the pH of the aqueous solution. Silane compounds 2 to 11 were obtained. The physical properties of the obtained silane compounds 2 to 11 are shown in Table 1.

<Preparation of Silane Compounds 12 to 14>
The alkoxysilanes not subjected to the hydrolysis treatment described in Table 1 were designated as silane compounds 12 to 14. Table 1 shows the physical properties of the silane compounds 12 to 14.

<Preparation of Silane Compounds 15 to 20>
In the production of silane compound 1, using the alkylalkoxysilane described in Table 1, the hydrolysis rate and siloxane ratio described in Table 1 were adjusted by adjusting the hydrolysis time and the pH of the aqueous solution. Silane compounds 15 to 20 were obtained. The physical properties of the obtained silane compounds 15 to 20 are shown in Table 1. When the main components of the silane compounds 17, 18, and 19 are analyzed from the GPC measurement results in the siloxane ratio measurement, the pentamer [m = 5 in the formula (1)] and the 10-mer [m = in the formula (1), respectively, 10] and 11-mer [m = 11 in the formula (1)].

<Manufacture of magnetic body 1>
While the untreated magnetic material was put into a Henschel mixer (Mitsui Miike Chemical Co., Ltd., FM-10C) and the peripheral speed of the stirring blade was adjusted to 34.5 m / s and dispersed, silane compound 1 was 3.8. Added by partial spraying. After dispersing as it was for 20 minutes, the magnetic material adsorbed with the silane compound 1 was taken out and the Henschel mixer was cleaned. Thereafter, the magnetic material on which the silane compound 1 was adsorbed was again put into a Henschel mixer, and stirred and dispersed at 40.5 m / s for 10 minutes. Thereafter, the magnetic body was dried at 160 ° C. for 2 hours and the condensation reaction of the silane compound was allowed to proceed. Then, it obtained as the magnetic body 1 which passed the sieve with an opening of 100 micrometers. Table 2 shows the physical properties of the obtained magnetic body 1.

<Manufacture of magnetic bodies 2 to 11>
In the production of the magnetic body 1, the magnetic bodies 2 to 11 were obtained in the same manner as in the production of the magnetic body 1 except that the silane compound was changed as described in Table 2. Table 2 shows the physical properties of the obtained magnetic bodies 2 to 11.

<Manufacture of magnetic body 12>
An aqueous solution containing ferrous hydroxide was prepared by mixing 1.0 to 1.1 equivalents of a caustic soda solution with respect to iron ions in an aqueous ferrous sulfate solution. While maintaining the aqueous solution at pH 9, air was blown in, and an oxidation reaction was performed at 80 to 90 ° C. to prepare a slurry liquid for generating seed crystals.

Subsequently, after adding ferrous sulfate aqueous solution to this slurry liquid so that it may become 0.9 to 1.2 equivalent with respect to the original alkali amount (sodium component of caustic soda), the slurry liquid is maintained at pH 8 and air is supplied. The oxidation reaction was advanced while blowing, and the pH was adjusted to about 6 at the end of the oxidation reaction. Thereafter, 0.6 part of silane coupling agent [n-C ₆ H ₁₃ Si (OCH ₃ ) ₃ ] was added to 100 parts of iron oxide and sufficiently stirred. The produced hydrophobic iron oxide particles were washed, filtered and dried by a conventional method, and then the agglomerated particles were crushed to obtain a magnetic body 12. Table 2 shows the physical properties of the obtained magnetic body 12.

<Manufacture of magnetic body 13>
In aqueous ferrous sulfate solution, 1.0 to 1.1 equivalents of caustic soda solution with respect to iron element, 1.0 mass% sodium hexametaphosphate in terms of phosphorus element with respect to iron element, silicon element with respect to iron element Then, 1.0 mass% sodium silicate was mixed to prepare an aqueous solution containing ferrous hydroxide.

  While maintaining the pH of the aqueous solution at around 13, air was blown and an oxidation reaction was performed at 80 to 90 ° C. to obtain a slurry solution of magnetic particles. After washing and filtering, this hydrous slurry liquid was once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Next, this water-containing sample was redispersed in another aqueous medium without drying, and then the pH of the redispersed liquid was adjusted to about 6. Thereafter, 2.3 parts of n-hexyltrimethoxysilane and 0.98 part of γ-methacryloxypropyltrimethoxysilane were added to 100 parts of magnetic iron oxide with sufficient stirring, and a coupling treatment was performed. The produced hydrophobic magnetic particles were washed, filtered and dried by a conventional method, and the resulting particles were sufficiently crushed to obtain a magnetic body 13. Table 2 shows the physical properties of the magnetic body 13 obtained.

<Manufacture of magnetic body 14>
An aqueous solution containing ferrous hydroxide was prepared by mixing 1.0 to 1.1 equivalents of a caustic soda solution with respect to iron ions in an aqueous ferrous sulfate solution.

While maintaining the pH of the aqueous solution at around 9, air was blown and an oxidation reaction was performed at 80 to 90 ° C. to obtain a slurry solution of magnetic particles. After washing and filtering, this hydrous slurry liquid was once taken out. At this time, a small amount of water-containing sample was collected and the water content was measured. Next, this water-containing sample was re-dispersed in another aqueous medium without drying, and then the pH of the re-dispersed liquid was adjusted to about 6, and the silane coupling agent (n-C ₁₀ H _{21 was} thoroughly stirred. 0.2 part of Si (OCH ₃ ) ₃ ) was added to the magnetic iron oxide (the amount of magnetic particles was calculated as a value obtained by subtracting the water content from the water-containing sample), and a coupling treatment was performed. The produced hydrophobic magnetic material was washed, filtered and dried by a conventional method, and the resulting particles were sufficiently crushed. Next, the obtained hydrophobic magnetic material is again subjected to a hydrophobic treatment with 0.3 part of a silane coupling agent (n-C ₁₀ H ₂₁ Si (OCH ₃ ) ₃ ) by a dry method, whereby the magnetic material 14 is obtained. It was. Table 2 shows the physical properties of the magnetic body 14 obtained.

<Manufacture of magnetic bodies 15 to 20>
In the production of the magnetic body 1, magnetic bodies 15 to 20 were obtained in the same manner as in the production of the magnetic body 1 except that the silane compound was changed as described in Table 2. Table 2 shows the physical properties of the magnetic bodies 15 to 20 obtained.

<Manufacture of magnetic toner 1>
450 parts of 0.1M Na ₃ PO ₄ aqueous solution is added to 720 parts of ion-exchanged water and heated to 60 ° C., and then 67.7 parts of 1.0M CaCl ₂ aqueous solution is added to contain a dispersion stabilizer. An aqueous medium was obtained.

・ Styrene 80.00 parts ・ N-butyl acrylate 20.00 parts ・ Divinylbenzene 0.65 parts ・ Iron complex of monoazo dye (T-77: manufactured by Hodogaya Chemical Co., Ltd.) 1.00 parts ・ Magnetic substance 1 90.00 parts -Amorphous polyester 3.00 parts (saturated polyester resin Mn = 5000 obtained by condensation reaction of EO adduct of bisphenol A and terephthalic acid, acid value = 12 mgKOH / g, Tg = 68 ° C.)
The above ingredients were uniformly dispersed and mixed using an attritor (Mitsui Miike Chemical Co., Ltd.) and then heated to 60 ° C., and then behenyl behenate (maximum endothermic peak temperature: 70.0 ° C.) as a release agent. 15.0 parts were mixed and dissolved. Thereafter, 4.50 parts of initiator 1 (see Table 3) was added and mixed to obtain a monomer composition.

The monomer composition was put into the aqueous medium, and stirred at 18.8 m / s for 10 minutes with a TK homomixer (Special Machine Industries Co., Ltd.) at 60 ° C. in an N ₂ atmosphere. Grained. Thereafter, the temperature was raised to 70 ° C. at a rate of 0.5 ° C./min while stirring with a paddle stirring blade, and the reaction was allowed to proceed for 6 hours while maintaining the temperature at 70 ° C. Thereafter, the temperature was raised to 90 ° C., held for 2 hours, and then gradually cooled to 30 ° C. at a rate of 0.5 ° C./min. After cooling, hydrochloric acid was added for washing, followed by filtration and drying to obtain magnetic toner particles 1.

  100 parts of this magnetic toner particle 1 and 1.0 part of hydrophobic silica fine powder having a number average primary particle size of 12 nm were mixed with a Henschel mixer (Mitsui Miike Chemical Co., Ltd.), and the weight average particle size (D4) was A 7.0 μm magnetic toner 1 was obtained. When the obtained magnetic toner was analyzed, it contained 100 parts of a binder resin. Table 4 shows the physical properties of the magnetic toner 1.

<Manufacture of magnetic toners 2 to 9>
Magnetic toners 2 to 9 were obtained in the same manner as in the production of the magnetic toner 1 except that the magnetic material, initiator type, and initiator addition amount were changed as shown in Tables 3 and 4 in the production of the magnetic toner 1. When these magnetic toners were analyzed, all of them contained 100 parts of a binder resin.

<Manufacture of magnetic toner 10>
In the production of the magnetic toner 1, the production of the magnetic toner 1, except that the magnetic substance, the initiator type and the initiator addition amount were changed as shown in Tables 3 and 4 and the reaction temperature was 70 ° C. In the same manner, magnetic toner 10 was obtained. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 11>
In the production of the magnetic toner 10, the magnetic toner 11 was obtained in the same manner as in the production of the magnetic toner 10 except that the heating rate up to 76 ° C. was 1.0 ° C./min. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 12>
In the production of the magnetic toner 11, the magnetic toner 12 was obtained in the same manner as in the production of the magnetic toner 11 except that the amount of divinylbenzene added was 0.55 parts. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 13>
In the production of the magnetic toner 11, a magnetic toner 13 was obtained in the same manner as in the production of the magnetic toner 11 except that the amount of divinylbenzene added was 0.80 part. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 14>
In the production of the magnetic toner 11, the magnetic toner 14 was obtained in the same manner as in the production of the magnetic toner 11 except that the addition amount of divinylbenzene was 0.50 part and the reaction temperature which was 76 ° C. was 80 ° C. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 15>
In the production of the magnetic toner 11, the magnetic toner 15 was obtained in the same manner as in the production of the magnetic toner 11 except that the addition amount of divinylbenzene was 0.90 parts and the reaction temperature which was 76 ° C. was 68 ° C. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 16>
In the production of the magnetic toner 14, the magnetic toner 16 was obtained in the same manner as in the production of the magnetic toner 14 except that the reaction temperature, which was 80 ° C., was 85 ° C. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 17>
In the production of the magnetic toner 15, the magnetic toner 17 was obtained in the same manner as the production of the magnetic toner 15 except that the reaction temperature, which was 68 ° C., was changed to 63 ° C. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toners 18 to 21>
Magnetic toners 18 to 21 were obtained in the same manner as the magnetic toner 17 except that the magnetic material was changed as shown in Table 4 in the production of the magnetic toner 17. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 1 for comparison>
In the production of the magnetic toner 15, a comparative magnetic toner 1 was obtained in the same manner as in the production of the magnetic toner 15 except that the initiator type and the addition amount were changed as shown in Tables 3 and 4. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toners 2 and 3 for comparison>
In the production of the magnetic toner 14, comparative magnetic toners 2 to 3 were obtained in the same manner as in the production of the magnetic toner 14 except that the initiator type and addition amount were changed as shown in Tables 3 and 4. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of Comparative Magnetic Toner 4>
Comparative magnetic toner 4 was obtained in the same manner as comparative magnetic toner 2 except that the magnetic material was changed as shown in Tables 3 and 4 in the production of comparative magnetic toner 2. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of Comparative Magnetic Toners 5 to 8>
Comparative magnetic toners 5 to 8 were obtained in the same manner as in the production of the magnetic toner 17 except that the magnetic material was changed as shown in Tables 3 and 4 in the production of the magnetic toner 17. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of magnetic toner 9 for comparison>
-Production of binder resin A-70.0 parts of styrene-30.0 parts of n-butyl acrylate-4.5 parts of initiator 1-0.5 parts of divinylbenzene After heating 200 parts of xylene to 85 ° C The above-mentioned formulation components were dropped into xylene over 4 hours, and further maintained for 6 hours under reflux of xylene. After the polymerization was completed, the solvent was distilled off under reduced pressure. The resin thus obtained is referred to as a binder resin A. The peak molecular weight of the binder resin A was 7800.

Production of magnetic toner 9 for comparison / Binder resin A 100 parts / HNP-10 (manufactured by Nippon Seiwa Co., Ltd., melting point 75 [deg.] C.) 4 parts / 95 parts of magnetic substance 1 / monoazo iron complex (T-77: 2 parts After premixing the above mixture with a Henschel mixer, the mixture was melt kneaded with a biaxial extruder heated to 110 ° C., and the cooled kneaded material was coarsely pulverized with a hammer mill to obtain a magnetic toner coarsely pulverized product. Obtained. The resulting coarsely pulverized product was finely pulverized by adjusting the air temperature at the inlet and outlet using a mechanical pulverizer turbo mill (manufactured by Turbo Kogyo Co., Ltd.). The finely pulverized product obtained was classified and removed at the same time by a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect. The magnetic toner particles thus obtained had a weight average particle diameter (D ₄ ) measured by a Coulter counter method of 7.3 μm.

  A magnetic toner 9 for comparison was prepared by mixing 100 parts of the magnetic toner particles and 1.35 parts of hydrophobic silica fine powder treated with hexamethyldisilazane and then treated with dimethyl silicone oil using a Henschel mixer. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Production of Comparative Magnetic Toner 10>
○ Synthesis of charge control resin The following components were added to a pressurizable reaction vessel equipped with a reflux tube, a stirrer, a thermometer, a nitrogen introduction tube, a dropping device and a decompression device, and heated to the reflux temperature while stirring the solvent. . A solution prepared by diluting 1 part of 2,2-azobis (2-methylbutyronitrile) as a polymerization initiator with 20 parts of 2-butanone was added dropwise over 30 minutes, and stirring was continued for 5 hours. Further, a solution obtained by diluting 2 parts of 4,4′-azobis (4-cyanopentanoic acid) with 20 parts of 2-butanone was added dropwise over 40 minutes, and the mixture was further stirred for 7 hours to complete the polymerization reaction. The polymer obtained after the polymerization solvent was distilled off under reduced pressure was roughly pulverized to 100 μm or less using a cutter mill equipped with a 150 mesh screen to obtain a charge control resin.
200 parts methanol, 150 parts 2-butanone, 50 parts water, 100 parts 2-propanol, 79 parts styrene, 14 parts n-butyl acrylate, 7 parts 2-acrylamido-2-methylpropanesulfonic acid

Production of Comparative Magnetic Toner 10 460 parts of 0.1M Na ₃ PO ₄ aqueous solution was added to 780 parts of ion-exchanged water and 16 parts of 1N hydrochloric acid was added and heated to 60 ° C., followed by 1.0M CaCl ₂ aqueous solution 67. 7 parts were added to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

On the other hand, as dispersoid,
・ Styrene 80 parts ・ N-butyl acrylate 20 parts ・ Polyester resin 2 parts (peak molecular weight = 7300, hydroxyl value = 16 mgKOH / g)
・ Magnetic material 13 90 parts ・ Charge control resin 1 part Stearyl stearate 10 parts (Maximum endothermic peak temperature 60 ° C.)
The above formulation was heated to 60 ° C., and uniformly dispersed and dissolved at 12,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). 7 parts of a polymerization initiator disec-butyl peroxydicarbonate was added and dissolved therein to prepare a polymerizable monomer system.

The above polymerizable monomer system is put into the above-mentioned aqueous medium, and stirred at 10,000 rpm for 15 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) at 60 ° C. in an N ₂ atmosphere, and granulated. did. Then, while stirring with a paddle stirring blade, the mixture was reacted at 60 ° C. for 7 hours, then heated to 80 ° C., and further reacted for 3 hours. After completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve the dispersant at a pH of 2 or lower, filtered, washed with water, and dried to obtain magnetic toner particles having a weight average particle diameter (D ₄ ) of 7.3 μm.

With respect to 100 parts of the magnetic toner particles obtained by the above method, silica having a primary particle diameter of 12 nm was treated with hexamethyldisilazane and then treated with silicone oil, and the BET value after the treatment was 120 m ² / g. 1.0 part of hydrophobic silica fine powder was added. Then, the magnetic toner 10 for a comparison was prepared by mixing using a Henschel mixer (Mitsui Miike Chemical Co., Ltd.). When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Manufacture of Comparative Magnetic Toner 11>
After adding 451 g of 0.1 M Na ₃ PO ₄ aqueous solution to 709 g of ion exchange water and heating to 60 ° C., 67.7 g of 1.0 M CaCl ₂ aqueous solution was gradually added, and hydrochloric acid was added to adjust the pH of the solution. Was adjusted to about 8.5 to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

・ Styrene 80 parts ・ N-butyl acrylate 20 parts ・ Unsaturated polyester resin 5 parts ・ Monoazo dye iron complex (T-77: manufactured by Hodogaya Chemical Co., Ltd.) 1 part ・ Magnetic substance 14 90 parts Atlite (Mitsui Mitsui) Koka Koki Co., Ltd.) was uniformly dispersed and mixed. This monomer composition was heated to 60 ° C., and 20 parts of ester wax (maximum endothermic peak temperature: 70 ° C.) mainly composed of behenyl behenate was added and mixed therewith, and polymerization initiators 2, 2 ′ were added thereto. -4.5 masses of azobis (2,4-dimethylvaleronitrile) were dissolved.

The polymerizable monomer system was put into the aqueous medium, and the mixture was granulated by stirring at 10,000 rpm for 15 minutes with a TK homomixer (Special Machine Industries Co., Ltd.) in an N ₂ atmosphere at 60 ° C. . Thereafter, the mixture was reacted at 60 ° C. for 7 hours while stirring with a paddle stirring blade. Thereafter, the liquid temperature was raised to 80 ° C., and stirring was further continued for 3 hours. After the completion of the reaction, the suspension was cooled, hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ , filtered, washed with water, and dried to obtain magnetic toner particles having a weight average particle diameter of 6.6 μm.

To 100 parts of magnetic toner particles, silica having a number average primary particle size of 12 nm is treated with hexamethyldisilazane and then treated with silicone oil, and 1 part of hydrophobic silica fine powder having a BET value of 140 m ² / g after treatment is obtained. Added. Thereafter, the magnetic toner 11 for comparison was prepared by mixing with a Henschel mixer (Mitsui Miike Chemical Co., Ltd.). When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Production of Comparative Magnetic Toners 12 and 13>
Comparative magnetic toners 18 to 21 were obtained in the same manner as the magnetic toner 17 except that the magnetic material was changed as shown in Tables 3 and 4 in the production of the magnetic toner 17. When this magnetic toner was analyzed, it contained 100 parts of a binder resin.

<Example 1>
1. Durability developability test As an image forming apparatus for the durability developability test, an LBP3100 (manufactured by Canon) was modified to increase the process speed to 200 mm / sec. Using this modified magnetic toner 1, a horizontal line with a printing rate of 4% is obtained in a normal temperature and humidity environment (23 ° C., 60% RH) and a high temperature and high humidity environment (32.5 ° C., 80% RH). A 2000-sheet image output test was performed in the second intermittent mode. As the recording medium, A4 75 g / m ² paper was used. Before and after passing the paper, a chart with a solid image formed on the entire surface of the printing paper is output one by one, and this solid image is measured with a Macbeth densitometer (manufactured by Macbeth) using an SPI filter with a reflection densitometer. Went. The original used a chart with an image ratio of 5%, and the evaluation was performed with the image density output at the end of the durability. At this time, those having a reflection density of less than 1.35 were judged to be unpreferable for practical use.

Moreover, in the developability evaluation test, a white image was output before and after the endurance of paper passing, and the reflectance was measured using a REFECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku. On the other hand, the reflectance of the transfer paper (standard paper) before white image formation was measured in the same manner. The filter used was a green filter, and fog was calculated according to the following formula.
Fog (reflectance) (%) = reflectance of standard paper (%)-reflectance of white image sample (%)

  As for the fog, the maximum fog value obtained was 0.5% or less as a good level, and 3.0% or more as a practically undesirable level.

2. Developability evaluation test when left after long-term use After leaving the main body after the developability evaluation test in a high temperature and high humidity environment for 3 days in a low temperature and low humidity environment (15 ° C, 10% RH), 5 solid white images are output. The fog was measured and evaluated in the same manner as in the durability development test. As for the fog, the maximum fog value obtained was 0.5% or less as a good level, and 3.0% or more as a practically undesirable level.

<Examples 2 to 17>
An image formation test was performed in the same manner as in Example 1 except that the magnetic toners 2 to 17 were used. As a result, all the toners were at a level where there was no practical problem in the above two tests. The evaluation results are shown in Table 5.

<Comparative Examples 1 to 11>
An image output test was performed in the same manner as in Example 1 except that the comparative toners 1 to 11 were used. According to the results, practically unfavorable results were obtained in either the durable developing property or the cleaning property. The evaluation results are shown in Table 5.

  DESCRIPTION OF SYMBOLS 100 Electrostatic latent image carrier (photoreceptor), 102 Toner carrier, 114 Transfer member (transfer roller), 116 Cleaner, 117 Contact charging member (charge roller), 121 Laser generator (latent image forming means, exposure device) , 123 laser, 124 register roller, 125 conveying belt, 126 fixing device, 140 developing device, 141 stirring member, A peak derived from the alkyl portion of the alkoxy group, B peak derived from the alkyl portion of the alkyl alcohol, alkyl group of the C alkylalkoxysilane Origin peak, area of peak derived from non-hydrolyzed product of α silane compound, total peak area of β silane compound, area of peak derived from hydrolyzate present as monomer of γ silane compound

Claims (7)

In a magnetic toner having a magnetic material, a binder resin, a magnetic toner particle containing at least a release agent, and an inorganic fine powder,
The magnetic toner particles are produced by a suspension polymerization method,
The magnetic material has a surface treated with a silane compound containing a compound having a structure represented by formula (1) as a main component,
The binder resin contains, as a main component, a resin polymerized using an organic peroxide having a hydrocarbon group having a branched structure having 3 or 4 carbon atoms as a polymerization initiator,
A magnetic toner, wherein the organic peroxide is selected from peroxydicarbonate and diacyl peroxide.
Formula (1) R ₂ O — [— SiR ₁ (OR ₂ ) —O—] _m —R ₂ , 1 ≦ m ≦ 10
R ₁ : A hydrocarbon group having a branched structure having 3 or 4 carbon atoms.
R ₂ : a functional group represented by H or C _n H _{2n + 1} [1 ≦ n ≦ 4].   2. The magnetic toner according to claim 1, wherein a peak molecular weight measured by gel permeation chromatography of a component extracted with tetrahydrofuran of the magnetic toner is 8000 or more and 18000 or less.   The insoluble matter derived from the binder resin component when the Soxhlet extraction is performed using tetrahydrofuran of the magnetic toner is 15.0% by mass or more and 50.0% by mass or less. Magnetic toner.   The ratio of the molecular weight of 500 or less to the molecular weight of 1000000 or less in the chart of molecular weight distribution measured by gel permeation chromatography of the component extracted with tetrahydrofuran of the magnetic toner is 2.50% or less. The magnetic toner according to any one of 1 to 3.   The magnetic substance is dispersed in 2.7 (mol / L) hydrochloric acid, and the absorbance at a wavelength of 338 nm of the supernatant when left at 25 ° C. for 1 hour is 6.00 or less. The magnetic toner according to any one of 1 to 4. 6. The magnetic toner according to claim 1, wherein the magnetic substance has a moisture adsorption amount per unit area of 0.190 mg / m ² or less.   The magnetic toner according to claim 1, wherein the organic peroxide is a peroxydicarbonate having a sec-butyl group.

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