JP2015227929A - Magnetic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic toner having stable transfer characteristics before and after long-term use.SOLUTION: The magnetic toner comprises magnetic toner particles produced by granulating a magnetic toner composition comprising a resin including a polyester resin (A), a hydrophobicized magnetic material, and a polymerizable monomer in an aqueous medium, and polymerizing the polymerizable monomer. The polyester resin (A) contains an isosorbide unit represented by formula (1) below by 0.1 mol% or more and 30.0 mol% or less; and the polyester resin (A) is included by 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the resin and included by 2.0 parts by mass or more and 15.0 parts by mass or less with respect to 100.0 parts by mass of the hydrophobicized magnetic material. When a transmittance of a solution prepared by mixing the hydrophobicized magnetic material and a methanol/water mixture solvent reaches 50%, the methanol concentration in the mixture solvent is 50 vol% or more and 80 vol% or less.

Description

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

  In recent years, image forming apparatuses such as copying machines and printers have been required to have higher speed, higher image quality, and higher stability as the purpose of use and environment of use have diversified. For example, printers that have been mainly used in the office in the past have come to be used in harsh environments such as high temperatures and high humidity, and are placed in such harsh environments. It is important to provide a stable image quality even in the case of a problem.

  By the way, in copying machines and printers, downsizing and energy saving of the apparatus are progressing, and a magnetic one-component developing system using magnetic toner which is advantageous in these respects is preferably used.

  In the magnetic one-component developing method, a magnetic toner layer regulating member (hereinafter referred to as a developing blade) is used, and a magnetic carrier is provided on a toner carrier (hereinafter referred to as a developing sleeve) provided with a magnetic field generating means such as a magnet roll. A toner layer is formed. Then, the magnetic toner layer is conveyed to the development area by the developing sleeve and developed.

  At this time, when the electric charge is applied to the magnetic toner, the developing blade and the developing sleeve are brought into contact with each other at a contact portion between the developing blade and the developing sleeve (hereinafter referred to as a blade nip portion). The magnetic toner is charged by friction generated during the contact.

  From the standpoint of speeding up the apparatus, rapid and uniform charge rising of the toner on the back of the sleeve is required. For this purpose, it is necessary to sharpen the distribution of the charging ability of the magnetic toner, and higher internal uniformity is required for the internal material dispersibility.

  Considering that the usage environment is diversified, it is also assumed that the magnetic toner is left for a long time in, for example, a high temperature and high humidity environment. In that case, it is conceivable that the resin component of the magnetic toner or the magnetic material absorbs moisture. If the image is printed in this state, the charge distribution becomes broad, and there is a problem that it is not stable from the viewpoint of transferability.

  In particular, in magnetic toners, the dispersibility of the magnetic material has a greater effect on the chargeability than non-magnetic toners that do not contain a magnetic material, and various image defects occur when the charge distribution of the magnetic toner is broad. Prone to occur. Among the image defects, the present inventors paid attention to the problem of transfer failure due to a change in the transfer process from the latent image carrier to the medium. By the way, in an environment where transfer defects are likely to occur, for example, there is a difference in image uniformity between the initial use and after long-term use. This is due to uneven transferability as a magnetic toner and exposure to the environment. This is because the magnetic toner changes depending on the case.

  In order to deal with such problems, many methods have been proposed from the viewpoint of reducing the change in toner with respect to the environment.

  For example, in Patent Document 1, an attempt is made to improve the storage stability of the toner by devising the monomer composition of the resin. Also in Patent Document 2, an attempt is made to improve developability by devising a monomer component of a resin.

  Patent Document 3 discloses a toner having improved developability by limiting the production method of polyester.

JP 2010-285555 A JP 2012-073305 A JP 2012-145600 A

  The proposals in Patent Documents 1 and 2 certainly have a certain effect under certain specific conditions. However, especially in a system having a magnetic material, the dispersibility of the magnetic material greatly affects the transferability. In particular, a high degree of dispersibility where the content of the magnetic material is large is not sufficiently mentioned, and there is still room for improvement in terms of transferability.

  Patent Document 3 does not mention particularly the case where a considerable amount of a magnetic material is contained as a colorant or the transferability after long-term use, which is insufficient to obtain the effects of the present invention. .

  As described above, there is still room for improvement in order to stably obtain a high-quality image with a magnetic toner having stable transfer characteristics before and after long-term use.

  An object of the present invention is to provide a magnetic toner capable of solving the above problems, that is, a magnetic toner having stable transfer characteristics before and after long-term use.

The magnetic toner of the present invention is a magnetic toner containing magnetic toner particles containing a resin and a hydrophobized magnetic material,
The magnetic toner particles are obtained by granulating a magnetic toner composition containing the resin containing polyester resin A, a hydrophobized magnetic material, and a polymerizable monomer in an aqueous medium, Produced by polymerizing the body,
The polyester resin A is represented by the following formula (1)

Containing 0.1 mol% or more and 30.0 mol% or less of an isosorbide unit represented by
The polyester resin A is contained in an amount of 1.0 to 20.0 parts by mass with respect to 100.0 parts by mass of the resin, and with respect to 100.0 parts by mass of the hydrophobized magnetic material. 2.0 parts by weight or more and 15.0 parts by weight or less,
The methanol concentration in the mixed solvent when the permeability of the solution obtained by mixing the hydrophobized magnetic substance and the methanol / water mixed solvent reaches 50% is 50% by volume or more and 80% by volume or less. Features.

  According to the present invention, it is possible to provide a magnetic toner having stable transfer characteristics before and after long-term use.

1 is a diagram illustrating an example of an image forming apparatus in which a magnetic toner of the present invention is used. It is a figure which shows the example of a methanol dripping transmittance | permeability curve. It is a figure which shows the < ¹ > H-NMR chart of the methoxysilane by which the hydrolysis process was made | formed. It is a figure which shows the GPC chart before and behind hydrolyzing alkoxysilane.

  Hereinafter, the present invention will be described in detail.

  The present invention relates to a magnetic toner containing magnetic toner particles including a resin and a hydrophobized magnetic material. In the present invention, the magnetic toner particles are obtained by granulating a magnetic toner composition containing a resin containing polyester resin A, a hydrophobized magnetic substance, and a polymerizable monomer in an aqueous medium, It is produced by polymerizing monomers. In the present invention, the polyester resin A has the following formula (1):

Is contained in an amount of 0.1 mol% to 30.0 mol%. In the present invention, the polyester resin A is contained in an amount of 1.0 to 20.0 parts by mass with respect to 100.0 parts by mass of the resin, and 100.0 parts by mass of the hydrophobized magnetic material. On the other hand, it is contained in an amount of 2.0 to 15.0 parts by mass. In the present invention, the methanol concentration in the mixed solvent when the transmittance of the solution obtained by mixing the hydrophobized magnetic substance and the methanol / water mixed solvent reaches 50% is 50% by volume to 80% by volume. is there.

  As a result of investigations by the present inventors, by using the magnetic toner as described above, it is possible to obtain a toner that can maintain excellent transferability even during long-term use and can provide a stable image. Here, the inventors presume the reason why the above-mentioned performance can be imparted by adjusting the combination of a specific polyester resin and a magnetic substance having a specific hydrophobic property and adjusting the quantitative ratio of these components as follows. ing.

  First, considering the transferability, in the transfer process, the magnetic toner on the latent image carrier is transferred onto paper under a transfer bias. When the transfer bias is applied, if the original magnetic toner has a broad charge distribution or is easily charged up, the amount of components that are not transferred onto the paper increases due to high adhesion to the latent image carrier. In particular, in the magnetic toner, when the dispersion state of the magnetic material is not uniform, the transferability is reduced due to the above phenomenon. Furthermore, when used for a long period of time in a harsh environment such as a high temperature and humidity environment, the magnetic toner with insufficient dispersibility of the magnetic material tends to have poor developability, and after long use, the magnetic toner with poor transferability tends to remain. . The present inventors have found that transferability can be improved by highly uniformly dispersing a magnetic material by the above means, and have completed the present invention. Hereinafter, the present invention will be described in detail.

  First, the magnetic toner of the present invention includes a polyester resin A containing a predetermined amount of an isosorbide unit represented by the following formula (1).

  The polyester resin A having the isosorbide unit of the formula (1) has high affinity with the hydrophobized magnetic substance, and is considered to have the effect of the present invention. The isosorbide unit of the formula (1) has a structure that tends to form a hydrogen bond because the oxygen atom faces outward as compared with a conventionally used alcohol monomer (for example, BPA PO adduct, EO adduct). it is conceivable that. Specifically, when the unit of the formula (1) is contained in the polyester resin A in an amount of 0.1 mol% or more and 30.0 mol% or less, the above-described hydrogen bonding effect tends to be exhibited. On the other hand, the polyester resin in which the content of the isosorbide unit of the formula (1) is less than 0.1 mol% is difficult to exert the above-described effect due to hydrogen bonding. Further, when the amount of the unit of the formula (1) is too large, the moisture adsorption amount tends to be increased. That is, when the content of the isosorbide unit of the formula (1) exceeds 30.0 mol%, the developability under high temperature and high humidity tends to decrease, which is not preferable.

  Here, the effect of increasing the affinity based on the hydrogen bond described above is notable for the first time when the degree of hydrophobicity of the hydrophobized magnetic material is within a specific range. Specifically, the methanol concentration in the mixed solvent when the transmittance of the solution obtained by mixing the hydrophobized magnetic substance and the methanol / water mixed solvent reaches 50% is 50% by volume or more and 80% by volume or less. It is. Here, the methanol concentration at which the transmittance of the solution reaches 50% is referred to as “hydrophobicity” in the following description.

  In considering the affinity between the polyester resin A and the hydrophobized magnetic material, first, the method for producing the magnetic toner of the present invention will be considered. The magnetic toner particles of the present invention are obtained by granulating a magnetic toner composition containing a polyester resin A, a hydrophobized magnetic substance, and a polymerizable monomer in an aqueous medium. Manufactured by polymerization. Therefore, there is a step of mixing and dissolving the polyester resin A, the hydrophobized magnetic substance and the polymerizable monomer. However, the resin or polymerizable monomer and the magnetic substance are likely to be non-uniform even if the dissolution strength is increased due to differences in hydrophobicity and specific gravity. The present inventors believe that the isosorbide unit contained in the polyester resin A and the hydrophobized magnetic substance can be highly uniformized in the solution by interacting during the dissolution process. Therefore, even in the granulation step in an aqueous medium, which is a step following the dissolution of the above three components, a uniformly dispersed state can be maintained, so that magnetic toner particles in which each particle is uniformly dispersed can be obtained.

  Here, the case where the degree of hydrophobicity is less than 50% by volume will be described. The magnetic toner particles according to the present invention are obtained by granulating a magnetic toner composition containing polyester resin A, a hydrophobized magnetic substance and a polymerizable monomer in an aqueous medium, and polymerizing the polymerizable monomer. Manufactured by. Therefore, the hydrophobized magnetic material needs to be hydrophobic to be separated from the aqueous medium and stably dispersed in the polymerizable monomer. At this time, if the degree of hydrophobicity is less than 50% by volume, the phase separation from the aqueous medium is insufficient, so that the dispersibility of the magnetic material itself is disturbed and the charge distribution tends to become non-uniform.

  On the other hand, if the degree of hydrophobicity exceeds 80.0% by volume, the effect of hydrogen bonding described above is weakened, and in the production in an aqueous medium, the hydrophobized magnetic substance tends to be unevenly distributed inside the polymerizable monomer, There is a tendency to obtain a magnetic toner that is easily charged up.

  It is also important to adjust the quantity ratio between the polyester resin A and the hydrophobized magnetic material. Specifically, the content of the polyester resin A contained in the magnetic toner is 2.0 parts by mass or more and 15.0 parts by mass or less with respect to 100.0 parts by mass of the hydrophobized magnetic material. When the amount of the polyester resin A is less than 2.0 parts by mass, the effect of stabilizing the dispersion of the polyester resin A is insufficient, so that the dispersibility of the hydrophobized magnetic material is significantly deteriorated. On the other hand, when the amount of the polyester resin A exceeds 15.0 parts by mass, the amount is excessive with respect to the magnetic material, and the magnetic material dispersibility tends to be deteriorated.

  Furthermore, it is also important that the content of the polyester resin A is 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the resin contained in the magnetic toner. The effect of the present invention cannot be obtained without a certain amount. Specifically, when the amount is less than 1.0 part by mass, the dispersibility of the magnetic material is significantly deteriorated. On the other hand, when the amount exceeds 20.0 parts by mass, the viscosity and interfacial tension of the polymerizable monomer are affected, and the granulation property tends to be disturbed, whereby the magnetic material dispersibility tends to deteriorate.

  In the present invention, the polyester resin A containing the isosorbide unit of the formula (1) as a constituent component condenses the divalent carboxylic acid or its anhydride with the isosorbide and divalent alcohol represented by the following formula (2). It is prepared by. Specifically, it can be prepared by a dehydration condensation method at a reaction temperature of 180 to 260 ° C. in a nitrogen atmosphere at a composition ratio in which carboxyl groups remain. Moreover, you may use together monohydric or bivalent or more alcohol other than isosorbide other than following formula (2) as needed. Further, a monovalent, trivalent or higher carboxylic acid component or an anhydride thereof may be used.

  Examples of the divalent alcohol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, Aliphatic diols such as 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polypropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethyl glycol; 2 -Ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenol represented by the following formula (A) and derivatives thereof; diols represented by the following formula (B), and the like.

(In the formula (A), R is an ethylene or propylene group. X and y are each an integer of 0 or more, provided that the average value of x + y is 0 to 10. The propylene group is 1, (This is a functional group derived from 2-propanediol.)

(In the formula (B), R ′ is any one of the above (B1) to (B3). X ′ and y ′ are integers of 0 or more, provided that the average value of x ′ + y ′ is 0. 10)

  In the present invention, the dihydric alcohol is preferably a bisphenol of the formula (A) and a derivative thereof from the viewpoint of reactivity, and more preferably, the average value of x + y among the bisphenol of the formula (A) and the derivative thereof is 1 to 4 is a compound.

  Examples of trihydric or higher alcohols that can be used in the preparation of the polyester resin A include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like can be mentioned.

  Examples of the divalent carboxylic acid that can be used in the preparation of the polyester resin A include benzene dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride, or anhydrides thereof, lower alkyl esters; succinic acid, adipic acid Alkyl dicarboxylic acids such as sebacic acid and azelaic acid or anhydrides thereof, lower alkyl esters; alkenyl succinic acids or alkyl succinic acids such as n-dodecenyl succinic acid and n-dodecyl succinic acid, or anhydrides, lower alkyl esters thereof; Examples thereof include unsaturated dicarboxylic acids such as acid, maleic acid, citraconic acid and itaconic acid, or anhydrides thereof, lower alkyl esters; and derivatives thereof. In the present invention, benzenedicarboxylic acids such as terephthalic acid and isophthalic acid are preferably used from the viewpoints of handling properties and reactivity.

  Examples of the trivalent or higher polyvalent carboxylic acid component that can be used in the preparation of the polyester resin A include trimellitic acid, pyromellitic acid, 1,2,4-benzenetricarboxylic acid, and 1,2,5-benzenetricarboxylic acid. 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2- Methyl-2-methylenecarboxypropane, tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, empole trimer acid, and their anhydrides, lower alkyl esters;

(In the formula (C), X represents an alkylene group or an alkenylene group, where X is a substituent having 5 to 30 carbon atoms having one or more side chains having 3 or more carbon atoms.)
And polycarboxylic acids such as anhydrides and lower alkyl esters thereof and derivatives thereof. In the present invention, trimellitic acid is suitably used from the viewpoint of easy adjustment of reactivity and resin acid value.

  In the present invention, the acid value of the polyester resin A is preferably 25.0 or less, and the hydroxyl value of the polyester resin A is preferably 30.0 or less. When the acid value of the polyester resin A is 25.0 or less and the hydroxyl value of the polyester resin A is 30.0 or less, terminal carboxyl groups and OH groups that can interact with the hydrophobized magnetic substance are sufficiently reduced. Therefore, it is easy to achieve the effect of increasing the dispersibility of the magnetic material. That is, the dispersibility of the magnetic material is likely to increase. The acid value of the polyester resin A is preferably 20.0 or less, and more preferably 10.0 or less.

  The magnetic substance contained in the magnetic toner of the present invention is preferably magnetic iron oxide surface-treated with a silane compound. This is because it is necessary to hydrophobize the magnetic material when the magnetic toner is produced by the suspension polymerization method preferably used for controlling the dispersibility of the magnetic material. As a result of intensive studies on the dispersibility of the magnetic material by the present inventors, it has been found that it is preferable to treat with a silane compound. Specifically, in the suspension polymerization method, a monomer composition containing a magnetic substance is dispersed in an aqueous medium, granulated, and a polymerizable monomer contained in the granulated particles is polymerized. Therefore, the surface of the magnetic material to be used needs to be hydrophobized so as not to be exposed to the aqueous medium. The reason why the surface treatment (hydrophobic treatment) of the magnetic iron oxide is performed in this way is that the untreated magnetic iron oxide is highly hydrophilic because functional groups such as hydroxyl groups are present on the surface.

  Here, silane compounds, titanate compounds, aluminate compounds, and the like are generally known as surface treatment agents, but these surface treatment agents all hydrolyze and exist on the surface of magnetic iron oxide. It has a strong chemical bond by condensation reaction with a hydroxyl group and exhibits hydrophobicity. However, it is known that these compounds may undergo self-condensation during hydrolysis and are likely to form polymers and oligomers. As a result of intensive studies by the present inventors, it has been found that titanate compounds and aluminate compounds are susceptible to self-condensation after hydrolysis and it is difficult to uniformly treat the surface of magnetic iron oxide (hydrophobic treatment). This is considered to be because the activity of titanium and aluminum contained in the titanate compound and the aluminate compound is high. On the other hand, since the silane compound can suppress the self-condensation while increasing the hydrolysis rate by controlling the hydrolysis conditions, the surface of the magnetic iron oxide can be uniformly treated. The present inventors consider that this is because the silicon activity of the silane compound is not as high as that of titanium or aluminum. For this reason, it is preferable to use a silane compound. Moreover, since it is the process for making the surface of a magnetic body hydrophobic, a silane compound needs to have a hydrophobic group, and it is preferable to have a hydrocarbon group specifically.

  The amount of the silane compound present on the surface of the magnetic material can be determined by measuring the amount of carbon contained in the magnetic material after the hydrophobic treatment. Although a measuring method is mentioned later, it is preferable that the carbon amount derived from a silane compound is 0.42 mass% or more and 0.80 mass% or less on the basis of magnetic iron oxide. If it is within this range, it can be used without affecting the production stability of the magnetic toner even if it is used for the treatment of the surface of the magnetic material.

  Further, in order to control the surface state of the magnetic material, it is necessary to control the toner manufacturing process manufactured according to the present invention.

  That is, for example, it is necessary to maintain the amount of the silane compound present on the surface of the magnetic material even in a polymerizable monomer such as styrene. As a result of intensive studies by the present inventors, the amount of residual carbon derived from the silane compound after washing with styrene is preferably 0.40% by mass or more and 0.70% by mass or less based on magnetic iron oxide. . By washing with styrene, the amount (attachment amount) of the silane compound present on the surface of the magnetic material used when producing the magnetic toner by the production method of the present invention can be estimated by the amount of residual carbon. This is because the hydrocarbon group is generally important for the silane compound to exhibit hydrophobicity, and it is effective to estimate the amount of carbon constituting the hydrocarbon group when estimating the hydrophobic capacity of the magnetic substance. The present inventors believe that this is because. In addition, a magnetic material that satisfies the above requirements has sufficient hydrophobic capacity that can be applied to the manufacturing method of the present invention, and, for example, good magnetic material dispersibility can be obtained without affecting manufacturing stability such as granulation. Cheap.

  Further, the silane compound obtained by treating the surface of the magnetic material used in the method for producing a magnetic toner of the present invention is obtained by subjecting alkoxysilane to hydrolysis treatment, and the hydrolysis rate of alkoxysilane is 50% or more. It is preferable. In general, a silane compound is used without being hydrolyzed and is often treated as it is, but this cannot form a chemical bond with a hydroxyl group or the like existing on the surface of magnetic iron oxide, and the degree of physical adhesion It has only strength. In this state, the silane compound is likely to be detached due to the share received during toner formation.

  For the above reason, in the present invention, the silane compound is preferably a product obtained by subjecting alkoxysilane to hydrolysis treatment. By performing the hydrolysis treatment, the silane compound is adsorbed via a hydrogen bond with a hydroxyl group or the like on the surface of the magnetic iron oxide, and a strong chemical bond can be formed by heating and dehydrating it. Further, by forming a hydrogen bond, volatilization of the silane compound can be suppressed during heating.

  For these reasons, in the present invention, the hydrolysis rate of the silane compound is preferably 50% or more, and more preferably 90% or more. When the hydrolysis rate of the silane compound is 50% or more, the surface of the magnetic iron oxide can be treated using a large number of treatment agents for the reasons described above. Furthermore, the uniformity of the surface treatment is improved, and the dispersibility of the magnetic material is further improved.

  Next, when performing a surface treatment with a silane compound on the magnetic material used in the present invention, the surface treatment is preferably performed in a gas phase.

  There are two types of methods for surface treatment of the magnetic material, dry and wet. When the surface treatment is performed by a dry method, a silane compound is added to the dried magnetic material, and the surface treatment is performed in a gas phase.

  When surface treatment is performed by a wet method, the dried product is redispersed in an aqueous medium, or the iron oxide obtained after completion of the oxidation reaction is redispersed in another aqueous medium without drying, and a silane compound Surface treatment by On the other hand, the magnetic material used in the present invention is a magnetic material that has been surface-treated (hereinafter also referred to as a dry method) in a gas phase with a silane compound. It is preferable because improvement in properties can be achieved. About this reason, the present inventors consider 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. Therefore, compared to a wet process in which water is present, the rate of hydrogen bond formation with the surface of the magnetic material is increased, and a more uniform and efficient hydrophobic treatment with a silane compound can be performed. In addition, when the reaction occurs while the hydrophilic group of the treatment agent forms a hydrogen bond with water and is trapped on the surface of the magnetic material, the hydrophilic group contained in the silane compound remains unreacted. Remains on the surface. At this time, since the hydrophilic group is easily compatible with water, if there are many hydrophilic groups on the surface of the magnetic material, uneven distribution of the magnetic material at the time of toner production tends to occur. Since the dry processing method can prevent problems due to hydrogen bonding when performing the wet processing method, the uniform coverage of the magnetic material used in the toner produced by the present invention with the silane compound is improved.

  Next, a method for producing a magnetic material used for the toner produced by the production method of the present invention will be described in detail.

  Hydrolysis of the alkoxysilane used for surface treatment of the magnetic material used in the present invention is preferably carried out as follows. Specifically, alkoxysilane is gradually added to an aqueous solution or a mixed solution of alcohol and water whose pH is adjusted to 3.0 or more and 6.5 or less, and uniformly dispersed using, for example, a disper blade. At this time, it is preferable that the temperature of the dispersion is 35 ° C. or more and 60 ° C. or less. Generally, the lower the pH and the higher the liquid temperature, the easier the alkoxysilane is hydrolyzed. As a result of diligent investigations by the present inventors, using a dispersing device capable of imparting high shear, such as a disperse blade, even under difficult hydrolysis conditions, the contact area between the alkoxysilane and water increases, and it is efficient. It was found that hydrolysis can be promoted. It was also found that this makes it possible to suppress self-condensation while increasing the hydrolysis rate. If the hydrolysis and stirring conditions are not appropriate, the silane compound is self-condensed to become siloxane and the reactivity with the surface of the magnetic material is reduced. According to the study by the present inventors, the amount of siloxane needs to be suppressed to 50% or less. In the present invention, it is preferable to treat the surface of magnetic iron oxide with a silane compound in the gas phase. As described above, the magnetic substance contained in the magnetic toner of the present invention can have a strong chemical bond by adsorbing a silane compound on the surface of magnetic iron oxide by a hydrogen bond and dehydrating it. . However, since the hydrogen bond generated between the silane compound and the surface of magnetic iron oxide is a reversible reaction, it is possible to treat more silane compounds on the surface of magnetic iron oxide when there is less water in the reaction system. It is. This greatly increases the hydrophobicity of the magnetic material and increases the dispersibility of the magnetic material.

  A known stirrer can be used as an apparatus used for the surface treatment of magnetic iron oxide. Specifically, a Henschel mixer (Mitsui Miike Chemical), a high speed mixer (Fukae Powtech), a hybridizer (Nara Machinery Co., Ltd.), etc. are preferable.

Magnetic iron oxide is mainly composed of triiron tetroxide or γ-iron oxide, but may contain elements other than iron such as phosphorus, cobalt, nickel, copper, magnesium, manganese, and aluminum. Magnetic material, it is preferable that a BET specific surface area is less than 2.0 m ² / g or more 20.0 m ² / g by a nitrogen adsorption method, not more than 3.0 m ² / g or more 10.0 m ² / g More preferred. The shape of the magnetic body includes a polyhedron, an octahedron, a hexahedron, a sphere, a needle, and a scale, but a polyhedron, an octahedron, a hexahedron, a sphere, and the like having a low anisotropy increase the image density. Preferred above. The magnetic material preferably has a volume average particle diameter (Dv) of 0.10 μm or more and 0.40 μm or less from the viewpoint of uniform dispersibility and color in the toner. The volume average particle diameter (Dv) of the magnetic material can be measured using a transmission electron microscope. Specifically, after sufficiently dispersing the toner particles to be observed in the epoxy resin, the cured product is obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days. Particle size of 100 magnetic bodies that can be seen in the field of view or in a photograph when the obtained cured product is made into a flaky sample with a microtome and then magnified 10,000 to 40,000 times with a transmission electron microscope (TEM) Measure. Then, the volume average particle diameter (Dv) is calculated based on the equivalent diameter of a circle equal to the projected area of the magnetic material. It is also possible to measure the particle size with an image analyzer.

  The magnetic material used in the magnetic toner produced according to the present invention can be produced, for example, by the following method. Specifically, 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. Next, air is blown in while maintaining the pH of the prepared aqueous solution at 7.0 or higher, and ferrous hydroxide is oxidized while the aqueous solution is heated to 70 ° C. or higher to become the core of magnetic iron oxide particles. First, seed crystals are formed. 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. Next, the pH of the aqueous solution is maintained at 5.0 or higher and 10.0 or lower, and the reaction of ferrous hydroxide proceeds while blowing air, thereby growing magnetic iron oxide particles with the seed crystal as a core. At this time, it is possible to control the shape and magnetic properties of the magnetic iron oxide by appropriately selecting pH, reaction temperature, stirring conditions and the like. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the aqueous solution is preferably not less than 5.0. After completion of the oxidation reaction, a silicon source such as sodium silicate is added to adjust the pH of the solution to 5.0 or more and 8.0 or less. By doing in this way, the coating layer containing silicon is formed on the surface of the magnetic iron oxide particles. Magnetic iron oxide particles can be obtained by filtering, washing, and drying the magnetic iron oxide particles obtained as above.

  The amount of silicon element present on the surface of magnetic iron oxide can be controlled by adjusting the amount of silicon source such as sodium silicate added after the oxidation reaction.

  Next, surface treatment with a silane compound is performed. Specifically, the liquid temperature is adjusted so that the aqueous solution whose pH is adjusted to 3.0 or more and 6.5 or less is 35 ° C. or more and 50 ° C. or less. Then, alkoxysilane is gradually added to this aqueous solution, and the alkoxysilane is hydrolyzed by, for example, uniformly stirring and dispersing using a disper blade or the like. The hydrolyzate thus obtained is added to magnetic iron oxide and mixed uniformly with a stirrer / mixer such as a high speed mixer or a Henschel mixer. Thereafter, by drying and crushing at a temperature of 80 ° C. or higher and 160 ° C. or lower, a magnetic material that has been surface-treated with silane can be obtained.

  When wet surface treatment is performed, after the oxidation reaction of iron hydroxide is completed, the dried reaction product (oxide) is redispersed, or after the oxidation reaction is completed, it is obtained by washing and filtering. The oxide (iron oxide) is redispersed in another aqueous medium without drying, and then the surface treatment is performed. Specifically, by adding alkoxysilane while sufficiently stirring the re-dispersion and increasing the temperature after hydrolysis, or adjusting the pH of the dispersion to an alkaline region after hydrolysis. Surface treatment is performed.

  Examples of silane compounds that can be used for the surface treatment of magnetic iron oxide include compounds represented by the following general formula (1).

R _m SiY _n (1)
(In Formula (1), R represents an alkoxy group or a hydroxyl group, m represents an integer of 1 to 3, Y represents an alkyl group or a vinyl group, and the alkyl group represented by Y is: It may further have a substituent such as an amino group, a hydroxyl group, an epoxy group, an acrylic group, a methacryl group, etc. n represents an integer of 1 to 3, provided that m + n = 4.

  Examples of the silane compound represented by the general formula (1) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4 epoxy cyclohexyl) ethyltrimethoxysilane, γ- Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltri Acetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiet Sisilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, trimethylmethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, hydroxypropyltrimethoxy Examples thereof include silane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, and hydrolysates thereof.

  When performing the silanization process using the said silane compound, you may process by using one type independently, and you may process combining several types. When a plurality of types of silane compounds are used in combination, each silane compound may be treated individually or simultaneously. In this invention, it is preferable that a silane compound has a hydrocarbon group as mentioned above, More preferably, carbon number contained in a hydrocarbon group is 2-6.

  In the present invention, the content of the magnetic substance is preferably 20 parts by mass or more and 150 parts by mass or less, and more preferably 50 parts by mass or more and less than 100 parts by mass with respect to 100 parts by mass of the binder resin.

  The content of the magnetic substance contained in the magnetic toner can be measured using a thermal analysis device manufactured by PerkinElmer, TGA7. The measuring method is as follows. The toner is heated from room temperature to 900 ° C. at a temperature rising rate of 25 ° C./min in a nitrogen atmosphere. The weight loss mass% between 100 ° C. and 750 ° C. is defined as the binder resin amount, and the remaining mass is approximately defined as the magnetic material amount.

  Examples of the binder resin contained in the magnetic toner of the present invention include a styrene resin, a polyester resin, an epoxy resin, and a polyurethane resin. However, the binder resin is not particularly limited, and a conventionally known resin may be used. it can. Among these, from the viewpoint of dispersibility of a magnetic material or a release agent, it is preferable that a styrene resin is a main component. In the present invention, the main component of the binder resin is defined as a component occupying at least 50% by mass or more in the binder resin.

  Specific examples of styrenic resins preferably used include styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-methyl acrylate copolymers, and 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, styrene-vinyl methyl ketone copolymer, styrene- Butadiene copolymer, steel Down - isoprene copolymer, styrene - maleic acid copolymer, styrene - like maleic acid ester copolymer. One of these resins may be used alone, or a plurality of these resins may be used in combination.

  The glass transition temperature (Tg) of the magnetic toner of the present invention is preferably 47 ° C. or more and 57 ° C. or less. This is because when the glass transition temperature is 47 ° C. or higher and 57 ° C. or lower, storage stability and durability developability can be improved while maintaining good fixability.

  The glass transition temperature of the resin or magnetic toner can be measured according to ASTM D3418-82 using a differential scanning calorimeter, for example, DSC-7 manufactured by PerkinElmer or DSC2920 manufactured by TA Instruments Japan. .

  The magnetic toner of the present invention contains an ester compound as a release agent from the viewpoint of low-temperature fixability, and the magnetic toner has a maximum endothermic peak at 50 ° C. or more and 80 ° C. or less as measured by a differential scanning calorimeter (DSC). It is preferable.

  Examples of the ester compound used as a release agent include saturated fatty acid monoesters such as behenyl behenate, palmitic acid palmitate, stearyl stearate, lignoceryl lignocerate, glycerin tribehenate, and carnauba wax.

  In addition to the monofunctional ester compound described above, a bifunctional ester compound such as a tetrafunctional or hexafunctional polyfunctional ester compound can also be used as the ester compound. Specifically, diesterified products of saturated aliphatic dicarboxylic acids and saturated aliphatic alcohols such as dibehenyl sebacate, distearyl dodecanedioate and distearyl octadecanedioate; nonanediol dibehenate, dodecanediol distearate and the like Diesterified products of saturated aliphatic diols and saturated fatty acids; Trialcohols such as glycerol tribehenate and glycerol tristearate and saturated fatty acids; Trialcohols such as glycerol monobehenate and glycerol dibehenate And a partially esterified product with a saturated fatty acid.

  In addition to the above ester compounds, the release agents that can be used in the present invention include, specifically, petroleum waxes such as paraffin wax, microcrystalline wax, and petrolactam and derivatives thereof; montan wax and derivatives thereof; Hydrocarbon waxes and their derivatives by the Tropsch method; polyolefin waxes and their derivatives represented by polyethylene and polypropylene; natural waxes and their derivatives such as carnauba wax and candelilla wax; and ester waxes. Here, the derivative is a concept including an oxide, a block copolymer with a vinyl monomer, and a graft-modified product.

  One of these release agents may be used alone, or two or more thereof may be used in combination.

  The maximum endothermic peak temperature of the release agent is preferably 50 ° C or higher and 80 ° C or lower.

  In the present invention, the peak top temperature of the maximum endothermic peak 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.

  As a specific measuring method, about 2 mg of the mold release agent is precisely weighed, put in an aluminum pan, and an empty aluminum pan is used as a reference. The measurement is performed at a temperature rising rate of 10 ° C./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 peak top temperature of the maximum endothermic peak of the release agent is determined from the DSC curve in the temperature range of 30 to 200 ° C. in the second temperature raising process.

  In the magnetic toner of the present invention, it is preferable to further add a charge control agent. In the present invention, since the binder resin itself has high negative chargeability, it is preferable to add a charge control agent for negative chargeability.

  As the charge control agent for negative charging, for example, organometallic complex compounds and chelate compounds are effective. Examples of these include monoazo metal complex compounds; acetylacetone metal complex compounds; metal complexes of aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids.

  As a charge control agent for negative charging, for example, Spiron Black TRH, T-77, T-95 (Hodogaya Chemical Co., Ltd.), BONTRON (registered trademark) S-34, S-44, S-54, E-84, E-88, E-89 (Orient Chemical).

  One of these charge control agents may be used alone, or two or more thereof may be used in combination. The amount of these charge control agents used is preferably 0.1 to 10.0 parts by mass, more preferably 0.1 parts by mass per 100 parts by mass of the binder resin from the viewpoint of the amount of charge of the magnetic toner of the present invention. Part to 5.0 parts by mass.

  Various inorganic fine particles can be added to the magnetic toner of the present invention, and organic fine particles may be used in place of the inorganic fine particles or together with the inorganic fine particles. Examples of inorganic fine particles that can be used in the present invention include lubricants such as silica fine particles, fluororesin particles, zinc stearate particles, and polyvinylidene fluoride particles; cerium oxide particles, silicon carbide particles, and alkaline earth metal titanates. Specific examples include abrasives such as strontium titanate fine particles, barium titanate fine particles, and calcium titanate fine particles. Further, a small amount of spacer particles such as silica can be used so as not to affect the effect of the present invention. Among these, silica fine particles are preferable because they significantly improve the fluidity of the magnetic toner and easily achieve the effects of the present invention.

When silica fine particles are used in the present invention, the specific surface area (BET specific surface area) measured by the BET method by nitrogen adsorption is 20 m ² / g or more and 350 m ² / g or less in order to give good fluidity to the magnetic toner. Is preferred. More preferably not more than 25 m ² / g or more 300m ² / g.

  The specific surface area (BET specific surface area) measured by the BET method by nitrogen adsorption is measured according to JIS Z8830 (2001). As the measuring device, an “automatic specific surface area / pore distribution measuring device TriStar 3000 (manufactured by Shimadzu Corporation)” which employs a gas adsorption method based on a constant volume method as a measuring method can be used.

  Silica fine particles and other inorganic fine particles are preferably those subjected to a hydrophobization treatment, and have been subjected to a hydrophobization treatment so that the degree of hydrophobicity measured by a methanol titration test is 40% or more, more preferably 50% or more. Those are particularly preferred.

  Examples of the hydrophobizing treatment include treatment with an organosilicon compound, silicone oil, long chain fatty acid and the like.

  Examples of the organosilicon compound include hexamethyldisilazane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, hexa And methyldisiloxane. One kind of these organosilicon compounds may be used, or a mixture of two or more kinds may be used.

  Examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, α-methylstyrene modified silicone oil, chlorophenyl silicone oil, and fluorine modified silicone oil.

  As the long chain fatty acid, a fatty acid having 10 to 22 carbon atoms can be suitably used, but it may be a linear fatty acid or a branched fatty acid. Further, either saturated fatty acid or unsaturated fatty acid can be used.

  Among these, a linear saturated fatty acid having 10 to 22 carbon atoms is very preferable because it can easily treat the surface of the inorganic fine particles uniformly.

  Examples of linear saturated fatty acids include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid.

  Among the inorganic fine particles used in the present invention, the silica fine particles are preferably treated with silicone oil, and more preferably, the silica fine particles treated with a silicon compound and silicone oil can suitably control the degree of hydrophobicity. ,preferable.

  As a method of treating silica fine particles with silicone oil, for example, a method of directly mixing inorganic fine particles treated with a silicon compound and silicone oil using a mixer such as a Henschel mixer, or spraying silicone oil onto inorganic fine particles A method is mentioned. Alternatively, after dissolving or dispersing silicone oil in a suitable solvent, inorganic fine particles may be added and mixed to remove the solvent.

  In order to obtain good hydrophobicity, the treatment amount of the silicone oil is preferably 1 part by mass or more and 40 parts by mass or less, and preferably 3 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of silica fine particles. More preferred.

  The magnetic toner of the present invention preferably has a weight average particle diameter (D4) of 7.0 μm or more and 12.0 μm or less from the viewpoint of balance between developability and fixability. More preferably, they are 7.5 micrometers or more and 11.0 micrometers or less, More preferably, they are 7.5 micrometers or more and 10.0 micrometers or less.

  In addition, the magnetic toner of the present invention has an average circularity of preferably 0.955 or more, more preferably 0.957 or more.

  Hereinafter, the method for producing the magnetic toner of the present invention will be exemplified, but the present invention is not limited thereto.

  The toner of the present invention can be produced using a conventionally known production method such as a suspension polymerization method, a dissolution suspension method, or an emulsion aggregation method. Among the above production methods, the suspension polymerization method can easily control the presence state of the styrene acrylic resin and the polyester resin A in the vicinity of the toner surface by utilizing the balance of polarity between water and the toner material. Therefore, the suspension polymerization method is a more preferable form from the viewpoint of improving the chargeability of the toner. Details of the toner production method using the suspension polymerization method will be described below.

  The method for producing a magnetic toner of the present invention comprises granulating a polymerizable monomer composition containing polyester resin A, a colorant, and a polymerizable monomer in an aqueous medium, and polymerizing the polymerizable monomer. This is a method for producing a magnetic toner.

  The polymerizable monomer composition is added to an aqueous medium having a dispersant for dispersing the polymerizable monomer composition and granulated. Thereafter, the polymerizable monomer in the polymerizable monomer composition is polymerized to form particles, and the obtained particles can be filtered, washed, and dried to obtain toner particles.

  As a method for adjusting the content of the styrene acrylic resin in the toner when using the suspension polymerization method, a styrene monomer and an acrylic monomer may be used as the polymerizable monomer. It may be adjusted by adding a styrene-acrylic resin in advance.

  The polymerization initiator used when the magnetic toner of the present invention is produced by the suspension polymerization method may be added at the same time when other additives are added to the polymerizable monomer, or may be polymerizable in the aqueous medium. You may mix immediately before granulating a monomer composition. Further, immediately after granulation, a polymerization initiator dissolved in a polymerizable monomer or solvent may be added before starting the polymerization reaction.

  The following are mentioned as a polymerization initiator used when manufacturing a toner using a suspension polymerization method.

  2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis Azo or diazo polymerization initiators such as -4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl Peroxide-based polymerization initiators such as peroxide, lauroyl peroxide, tert-butyl-peroxypivalate.

  The amount of these polymerization initiators to be used varies depending on the desired degree of polymerization, but is generally 3 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer. preferable. The type of the polymerization initiator is slightly different depending on the polymerization method, but is selected with reference to the 10-hour half-life temperature, and is used in a mode in which one type is used alone or a mode in which two or more types are used in combination.

  As the dispersant for dispersing the polymerizable monomer composition in the aqueous medium, known inorganic and organic dispersants can be used.

  Examples of the inorganic dispersant include the following.

  Tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, magnesium carbonate, calcium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina .

  On the other hand, examples of the organic dispersant include the following.

  Polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, carboxymethyl cellulose sodium salt, starch.

  Also, commercially available nonionic, anionic and cationic surfactants can be used as a dispersant for dispersing the polymerizable monomer composition in an aqueous medium. Examples of such surfactants include the following.

  Sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate.

  In the present invention, among the dispersants used when the polymerizable monomer composition is dispersed in an aqueous medium, a poorly water-soluble inorganic dispersant is preferable, and the poorly water-soluble is soluble in an acid. It is more preferable to use an inorganic dispersant.

  The amount of the dispersant used for dispersing these polymerizable monomer compositions in the aqueous medium is 0.2 parts by mass or more and 2.0 parts by mass with respect to 100 parts by mass of the polymerizable monomer. The following is preferable. Further, in the aqueous dispersion medium in which the polymerizable monomer composition is granulated in the aqueous medium, 300 parts by mass or more and 3,000 parts by mass or less of water are added to 100 parts by mass of the polymerizable monomer composition. It is preferable to use it to prepare an aqueous dispersion medium.

  In the present invention, when preparing an aqueous dispersion medium in which the poorly water-soluble inorganic dispersant is dispersed, a commercially available dispersant may be used as it is. In addition, in order to obtain particles of a dispersant having a fine and uniform particle size, an aqueous dispersion medium is prepared after forming the above slightly water-soluble inorganic dispersant in a liquid medium such as water under high-speed stirring. May be. For example, when tricalcium phosphate is used as a dispersant, fine particles of tricalcium phosphate can be formed by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution with high-speed stirring.

  Next, an image forming apparatus that can suitably use the magnetic toner of the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic view showing an example of an image forming apparatus using the magnetic toner of the present invention. In the image forming apparatus of FIG. 1, reference numeral 100 denotes an electrostatic latent image carrier (hereinafter also referred to as a photoconductor). A charging roller 117, a developing device 140 having a developing sleeve 102, a transfer charging roller 114, a cleaner container 116, a fixing device 126, a pickup roller 124, and the like are provided around the charging roller 117. The electrostatic latent image carrier 100 is charged by the charging roller 117. Then, exposure is performed by irradiating the electrostatic latent image carrier 100 with laser light from 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 and fixed on the transfer material. Further, the magnetic toner partially left on the electrostatic latent image carrier is scraped off by the cleaning blade and stored in the cleaner container 116.

  Next, a method for measuring physical properties that determines the characteristics of the magnetic toner of the present invention will be described.

(1) Method for Measuring Acid Value of Polyester Resin A The acid value of polyester resin A contained in the magnetic toner of the present invention is determined by the following operation. In basic operation, the acid value of a polar resin belonging to JIS K0070 can be measured by the following method.

  The acid value is the number of mg of potassium hydroxide necessary for neutralizing the acid contained in 1 g of the sample. The acid value of the polar resin was measured according to JIS K 0070-1992. Specifically, it measured according to the following procedures.

(1-1) Preparation of reagent Phenolphthalein solution was obtained by dissolving 1.0 g of phenolphthalein in 90 ml of ethyl alcohol (95 vol%) and adding ion-exchanged water to bring the liquid volume to 100 ml.

  7 g of special grade potassium hydroxide was dissolved in 5 ml of water, and ethyl alcohol (95 vol%) was added to make the volume 1 l. Next, this solution was placed in an alkali-resistant container so as not to come into contact with carbon dioxide gas, etc., and allowed to stand for 3 days, followed by filtration to obtain a potassium hydroxide solution. The obtained potassium hydroxide solution was stored in an alkali-resistant container. The factor of the potassium hydroxide solution is that when 25 ml of 0.1 mol / l hydrochloric acid is placed in an Erlenmeyer flask, a few drops of the phenolphthalein solution is added and titrated with the potassium hydroxide solution. It calculated | required from the quantity of the said potassium hydroxide solution required. The 0.1 mol / l hydrochloric acid used at this time was prepared according to JIS K 8001-1998.

(1-2) Operation (A) Main test 2.0 g of the pulverized polar resin and binder resin sample are precisely weighed into a 200 ml Erlenmeyer flask, and 100 ml of a mixed solution of toluene: ethanol (2: 1) is added. Dissolve over time. 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 described above, except that no sample is used (that is, only a mixed solution of toluene: ethanol (2: 1) is used).

(1-3)
The acid value is calculated by substituting the obtained result into the following formula (*).
A = [(C−B) × f × 5.61] / S (*)

  In the formula (*), A represents the acid value (mgKOH / g), B represents the addition amount (ml) of the potassium hydroxide solution in the blank test, and C represents the addition of the potassium hydroxide solution in the present test. Represents volume (ml). f represents the factor of the potassium hydroxide solution, and S represents the amount (g) of the sample.

(2) Method for measuring methanol concentration at which the permeability reaches 50% in the methanol / water mixed solvent of the hydrophobized magnetic substance Methanol concentration at which the permeability reaches 50% in the methanol / water mixed solvent of the hydrophobized magnetic substance Is obtained by measuring a methanol dropping transmittance curve using a powder wettability tester WET-101P manufactured by Reska Co., Ltd. Specific operations will be described below.

  First, 40% by volume of methanol and 60% by volume of water were mixed to prepare a methanol / water mixed solvent, and then 70 ml of the mixed solvent was placed in a container, and ultra-high to remove bubbles and the like in the measurement sample. Disperse for 5 minutes with a sonic disperser. Next, 1.0 g of a hydrophobized magnetic substance as a specimen is precisely weighed and added to the container. At this time, the hydrophobized magnetic material is previously passed through 70 mesh (opening diameter: 212 μm) to remove large aggregates.

Next, while stirring the sample solution for measurement at a speed of 6.67 s ⁻¹ , methanol was added at 1.3 ml / min. Are continuously added at a dropping speed of 5. At the same time, the transmittance is measured with light having a wavelength of 780 nm, and for example, a methanol dropping transmittance curve shown in FIG. 2 is prepared. The container used in the measurement is a cylindrical beaker with a bottom diameter of 5 cm and a glass beaker with a thickness of 1.75 mm. The magnetic stirrer has a spindle shape of 25 mm in length and a maximum of 8 mm in total, and fluorine. The one coated with resin was used. From the obtained transmittance curve (for example, FIG. 2), a methanol concentration (volume%) at which the transmittance reaches 50% is obtained.

(3) Measuring method of carbon amount derived from silane compound of hydrophobized magnetic material For hydrophobized magnetic material, the carbon amount per unit weight is measured using HORIBA carbon / sulfur analyzer (EMIA-320V). . In the measurement, for example, the amount of sample charged at the time of measuring EMIA-320V is 0.20 g, and a mixture of tungsten and tin can be used as a combustion aid.

(4) Residual carbon content measurement method after washing the hydrophobized magnetic material with styrene 20 g of styrene and 1.0 g of the hydrophobized magnetic material were charged into a 50 ml glass vial, and the glass vial was made by Iwaki Sangyo Co., Ltd. Set to “KM Shaker” (model: V.SX). Next, the processing agent contained in the magnetic material that has been surface-treated by shaking for 1 hour with speed set to 50 is eluted in styrene. Thereafter, the hydrophobized magnetic material and styrene are separated, and the magnetic material is sufficiently dried with a vacuum dryer.

  About the dried hydrophobic treatment magnetic body, it operates similarly to the measuring method of the carbon amount originating in the silane compound contained in a hydrophobic treatment magnetic body, and measures the carbon amount per unit weight.

(5) Method for Measuring Hydrolysis Rate of Silane Compound When hydrolysis treatment is performed on alkoxysilane, a mixture composed of a hydrolyzate, an unhydrolyzed product, and a condensate is obtained. Described below is the ratio of the hydrolyzate in the resulting mixture, which corresponds to the hydrolysis rate of the silane compound. Moreover, the said mixture corresponds to the silane compound mentioned above.

Here, the hydrolysis reaction of alkoxysilane will be described by taking methoxysilane as an example. When methoxysilane is hydrolyzed, oxygen atoms contained in methoxy groups become hydroxyl groups and methanol is generated. Therefore, the progress of hydrolysis can be known from the quantitative ratio between the methoxy group and methanol. In the present invention, the quantitative ratio is measured by ¹ H-NMR (nuclear magnetic resonance) to determine the hydrolysis rate. Hereinafter, specific measurement and calculation methods will be described below using methoxysilane as an example.

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 is performed on methoxysilane to obtain a silane compound, and the pH of the aqueous silane compound solution just before being added to the untreated magnetic material is 7.0, and the temperature is set to 10 ° C. Was stopped. Next, a dried product of the silane compound is obtained by removing moisture from the obtained aqueous solution. A small amount of deuterated chloroform is added to the dried product, and ¹ H-NMR is measured. The peak derived from the methoxy group in the obtained spectrum is determined based on the peak position confirmed in advance. FIG. 3 is a diagram showing a ¹ H-NMR chart of methoxysilane subjected to hydrolysis treatment. In FIG. 3, the peak area derived from the methoxy group is A, the peak area derived from the methyl group of methanol is B, and the hydrolysis rate is determined using the following formula (**).
Hydrolysis rate (%) = {B / (A + B)} × 100 (**)

In addition, the measurement conditions of ¹ H-NMR are set as follows, for example.
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

(6) Method for Measuring the Abundance Ratio of Siloxane in Silane Compound Among the hydrolyzate contained in the treated product when the alkoxysilane is hydrolyzed, the ratio (siloxane ratio) present as siloxane is unhydrolyzed among the silane compounds. It is calculated | required as a ratio of the condensate with respect to the sum total of the component except a thing. That is, the quantity ratio of the components that have been hydrolyzed and have become condensates is shown. However, when the condensate ratio is high, the uniform treatment is hindered as described above when the magnetic material is surface-treated.

  When quantifying the compound in the silane compound, it is measured by gel permeation chromatography (GPC) as follows.

In advance, GPC measurement is performed on the alkoxysilane that has not been subjected to hydrolysis treatment, and the retention time is confirmed. Then, the hydrolysis reaction is stopped by adjusting the pH of the aqueous silane compound solution immediately before use to the untreated magnetic material to 7.0 and a temperature of 10 ° C. In addition, when adjusting pH, an acetic acid, a triethylamine, and ion-exchange water are used. Thereafter, acetonitrile is added and mixed so that the concentration of the silane compound is 10% by volume, and GPC measurement is performed using the obtained solution as a measurement sample. Here, GPC measurement conditions are shown below.
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 the siloxane ratio from the result of GPC measurement of alkoxysilane will be described below. When alkoxysilane is measured by GPC, for example, a chart as shown in FIG. 4 is obtained. Here, the upper part of FIG. 4 shows a GPC chart before hydrolysis of alkoxysilane, and the lower part of FIG. 4 shows a chart after hydrolysis of alkoxysilane. In the lower chart of FIG. 4, there are peaks derived from alkoxysilane, a hydrolyzate of alkoxysilane, and siloxane, and the attribution of the peaks is as described in FIG. In the chart after hydrolysis of alkoxysilane, β represents the total area of peaks derived from alkoxysilane, the hydrolyzate of alkoxysilane and siloxane, and γ represents the area of the peak derived from siloxane. Using these β and γ, the siloxane ratio can be defined as in the following formula (***).
Siloxane ratio (%) = γ / β × 100 (***)

(7) Measuring method of weight average particle diameter (D4) of magnetic toner The weight average particle diameter (D4) of the magnetic toner is calculated as follows. As a measuring device, a precise particle size distribution measuring device “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter, Inc.) using a pore electrical resistance method equipped with an aperture tube of 100 μm is used. For setting the measurement conditions and analyzing the measurement data, the attached dedicated software “Beckman Coulter Multisizer 3 Version 3.51” (manufactured by Beckman Coulter, Inc.) is used. The measurement is performed with 25,000 effective measurement channels.

  As the electrolytic aqueous solution used for the measurement, special grade sodium chloride is dissolved in ion-exchanged water so as to have a concentration of about 1% by mass, for example, “ISOTON II” (manufactured by Beckman Coulter, Inc.) can be used.

  Prior to measurement and analysis, the dedicated software is set as follows.

  On the “Change Standard Measurement Method (SOM)” screen of the dedicated software, set the total count in the control mode to 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 By pressing the “Threshold / Noise Level Measurement Button”, the threshold and noise level are automatically set. In addition, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II, and the “aperture tube flush after measurement” is checked.

  In the “Pulse to particle size conversion setting” screen of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bin, and the particle size range is set to 2 μm to 60 μm.

  Here, the specific measuring method of D4 is as follows.

  (7-1) About 200 ml of the electrolytic 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 dedicated software.

  (7-2) About 30 ml of the electrolytic aqueous solution is put into a glass 100 ml flat bottom beaker. In this, "Contaminone N" (nonionic surfactant, anionic surfactant, 10% by weight aqueous solution of neutral detergent for pH7 precision measuring instrument cleaning, made by organic builder, manufactured by Wako Pure Chemical Industries, Ltd. About 0.3 ml of a diluted solution obtained by diluting 3) with ion-exchanged water.

  (7-3) Two oscillators with an oscillation frequency of 50 kHz are incorporated with the phase shifted by 180 degrees, and an ultrasonic disperser “Ultrasonic Dispersion System Tetora150” (manufactured by Nikka Ki Bios) with an electrical output of 120 W is prepared. To do. About 3.3 l of ion-exchanged water is placed in the water tank of the ultrasonic disperser, and about 2 ml of Contaminone N is added to the water tank.

  (7-4) The beaker of (7-2) 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.

  (7-5) In a state where the electrolytic aqueous solution in the beaker of (7-4) is irradiated with ultrasonic waves, about 10 mg of magnetic 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 ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted so as to be 10 ° C. or higher and 40 ° C. or lower.

  (7-6) The electrolytic solution (7-5) in which the toner is dispersed with a pipette is dropped into the round bottom beaker (7-1) installed in the sample stand, and the measured concentration is about 5%. Adjust so that Measurement is performed until the number of measured particles reaches 50,000.

  (7-7) The measurement data is analyzed with the dedicated software attached to the apparatus, and the weight average particle diameter (D4) is calculated. The “average diameter” on the “analysis / volume statistic (arithmetic average)” screen when the graph / volume% is set with the dedicated software is the weight average particle diameter (D4).

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, these Examples do not limit this invention at all. In addition, all the parts in the following mixing | blending are a mass part.

[Method for producing polyester resin A]
(Production of Resin A-1)
100 parts by mass of a mixture obtained by mixing raw material monomers other than trimellitic anhydride in the amounts shown in Table 1 below, and 0.52 parts by mass of di (2-ethylhexanoic acid) tin as a catalyst were introduced into nitrogen. The polymerization tank equipped with the line, the dehydration line, and the stirrer was put. Next, after the inside of the No. 10 tank was put into a nitrogen atmosphere, a polycondensation reaction was carried out over 6 hours while heating at 200 ° C. Furthermore, after raising the temperature to 210 ° C., trimellitic anhydride was added, and after the pressure in the polymerization tank was reduced to 40 kPa, a condensation reaction was further performed. The acid value, hydroxyl value, and molecular weight of the obtained resin are as shown in Table 1. This resin is designated as resin A-1.

  In addition, isosorbide in the table is a compound having the structure of the general formula (1).

(Production of resins A-2 to A-13)
Resins A-2 to A-13 were produced in the same manner as Resin A-1 with the raw material monomer charge shown in Table 1 below. At that time, sampling and measurement were sequentially performed, and when the desired acid value was reached, the polymerization reaction was stopped and taken out from the polymerization tank. The physical properties of the obtained resin are shown in Table 1 below.

[Method for producing untreated magnetic material]
In a ferrous sulfate aqueous solution, 1.1 molar equivalent of caustic soda solution with respect to iron element, SiO _{2 in} an amount of 0.60% by mass in terms of silicon element with respect to iron element, and with respect to iron element An amount of sodium phosphate of 0.15% by mass in terms of phosphorus element was mixed. In this way, an aqueous solution containing ferrous hydroxide was prepared. Next, the pH of the aqueous solution was set to 8.0, and an oxidation reaction was performed at 85 ° C. while blowing air to prepare a slurry liquid having seed crystals.

  Next, after adding an aqueous ferrous sulfate solution to this slurry liquid so as to be 1.0 equivalent to the initial alkali amount (sodium component of caustic soda), the pH of the slurry liquid is maintained at 7.5, and air is supplied. The slurry liquid containing magnetic iron oxide was obtained by proceeding the oxidation reaction while blowing. This slurry was filtered, washed, dried and crushed to obtain an untreated magnetic material having a number average primary particle size (D1) of 0.21 μm.

[Preparation of Silane Compound]
(Preparation of Silane Compound 1)
An aqueous solution was prepared by adding 20 parts by mass of isobutyltrimethoxysilane dropwise with stirring to 80 parts by mass of ion-exchanged water. Thereafter, the aqueous solution containing the hydrolyzate is prepared by dispersing the aqueous solution at a pH of 5.5 and dispersing it at 0.46 m / s for 2 hours using a disper blade while maintaining the temperature at 40 ° C. A certain silane compound 1 was obtained. Table 2 shows the physical properties of the obtained silane compound.

(Preparation of silane compounds 2-9)
Except that the alkoxysilane described in Table 2 was used and the hydrolysis time and the pH of the aqueous solution were appropriately adjusted so that the hydrolysis rate and the siloxane rate would be the desired values, the same as the method for producing the silane compound 1 Silane compounds 2 to 9 were obtained by the method. Table 2 shows the physical properties of the obtained silane compound. However, the silane compound 8 was not subjected to hydrolysis treatment.

[Method for producing hydrophobized magnetic material]
(Manufacture of hydrophobized magnetic material 1)
After the untreated magnetic material is put into a Henschel mixer (Mitsui Miike Chemical Co., Ltd.), the untreated magnetic material is dispersed at a rotational speed of 34.5 m / s, and silane compound 1 (3.8 parts by mass) Was added while spraying. Next, after dispersing for 10 minutes, the magnetic material adsorbed with the silane compound 1 was taken out, and after treatment, the magnetic material was dried in a state of being gently placed at 160 ° C. for 2 hours, and the condensation reaction of the silane compound was allowed to proceed. . Thereafter, a magnetic material that passed through a sieve having an opening of 100 μm was obtained as a hydrophobized magnetic material 1. The amount of carbon derived from the silane compound was 0.53% by mass, the amount of carbon remaining after washing with styrene was 0.48% by mass, and the methanol concentration at a transmittance of 50% was 61% by volume. Table 3 shows the physical properties of the hydrophobized magnetic material.

(Production of hydrophobized magnetic materials 2 to 8 and 10 to 11)
In the manufacturing method of the hydrophobized magnetic body 1, the type of the silane compound was appropriately changed as described in Table 3, and the spray amount of the silane compound was appropriately changed. Thereby, the hydrophobized magnetic bodies 2 to 8 and 10 to 11 in which the desired “carbon amount derived from the silane compound” was adjusted were obtained. The spray amount and the length of the hydrocarbon group of the silane compound correlate with the carbon amount. The physical properties of the obtained hydrophobized magnetic material are shown in Table 3 below.

(Manufacture of hydrophobized magnetic material 9)
In the production of the untreated magnetic material, it was redispersed in another aqueous medium without drying after filtration and washing. Thereafter, the pH of the redispersed liquid was adjusted to about 6 and the temperature was adjusted to about 50 ° C., and n-decyltrimethoxysilane was added to 5.0 parts by mass (the amount of magnetic iron oxide) with respect to 100 parts by mass of magnetic iron oxide while sufficiently stirring Measured the water content of the water-containing sample and added it). The coupling process was continued for 24 hours under the above conditions. The obtained hydrophobized magnetic material was washed, filtered, dried and crushed by a conventional method, and a magnetic material passed through a sieve having an opening of 100 μm was obtained as hydrophobized magnetic material 9. The physical properties of the obtained hydrophobized magnetic material are shown in Table 3 below.

[Production of Magnetic Toner 1]
850 parts by mass of 0.1 mol / L-Na ₃ PO ₄ aqueous solution was added to a container equipped with a high-speed stirring device Claremix (M Technique Co., Ltd.) and stirred at a rotating peripheral speed of 33 m / s to 60 ° C. Warmed up. To this, 68 parts by mass of a 1.0 mol / L-CaCl ₂ aqueous solution was added to prepare an aqueous medium containing a minute hardly water-soluble dispersant Ca ₃ (PO ₄ ) ₂ .

Moreover, the following materials were mixed and dissolved using a propeller type stirring device to prepare a solution. In addition, when mixing the following material, the rotational speed of the stirrer was 100 r / min.
-Styrene 75.0 parts by mass-n-butyl acrylate 25.0 parts by mass-Resin A-1 10.0 parts by mass-Hydrophobized magnetic substance 1 100.0 parts by mass-Monoazo dye iron complex (T-77: 1.0 parts by mass / hydrocarbon wax HNP-51 (manufactured by Nippon Seiwa Co., Ltd.) 15.0 parts by mass Thereafter, the mixture was heated to a temperature of 60 ° C., and then a TK homomixer (special machine) Made by Kagaku Kogyo Co., Ltd., and the stirring speed was set to 9000 r / min, and the solid content was dissolved and dispersed.

  A polymerizable monomer composition was prepared by charging 10.0 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile), which is a polymerization initiator, and dissolving it in the mixed solution. . Next, the polymerizable monomer composition was put into the aqueous medium, heated to a temperature of 60 ° C., and granulated for 15 minutes while rotating the CLEARMIX at a rotational peripheral speed of 33 m / s.

  Thereafter, the mixture was transferred to a propeller type stirring device and reacted at a temperature of 70 ° C. for 5 hours while stirring at 100 rpm, and then heated to a temperature of 85 ° C. and further reacted for 4 hours to produce magnetic toner particles. . After completion of the polymerization reaction, the residual monomer was removed under reduced pressure by heating, and then, after cooling, hydrochloric acid was added to lower the pH to 2.0 or less, thereby dissolving the inorganic fine particles. Further, after washing with water several times, drying was performed at 40 ° C. for 72 hours using a dryer, and then classification was performed using a multi-division classifier utilizing the Coanda effect, whereby magnetic toner particles 1 were obtained. .

With respect to the obtained magnetic toner particles 1 (100 parts by mass), 1.0 part of hydrophobic silica having a specific surface area by the BET method of 200 m ² / g was added using a Henschel mixer (Mitsui Miike Chemical Co., Ltd.). By performing external addition, magnetic toner 1 having a weight average particle diameter (D4) of 8.1 μm was obtained. The physical properties of the magnetic toner 1 are shown in Table 4 below. In addition, the quantity with respect to 100 mass parts of resin of the polyester resin A in a table | surface is obtained by a following formula.
Amount based on 100 parts by mass of resin = (addition amount of polyester resin A / total amount of resin other than wax) × 100

On the other hand, the amount with respect to 100 parts by mass of the hydrophobized magnetic material is obtained by the following formula.
Amount based on 100 parts by mass of hydrophobized magnetic material = (addition amount of polyester resin A / added amount of hydrophobized magnetic material) × 100

The amount of the hydrophobized magnetic material is obtained by the following formula.
Amount of hydrophobized magnetic material = (addition amount of hydrophobized magnetic material / total amount of resin other than wax) × 100

[Methods for producing magnetic toners 2 to 14 and comparative magnetic toners 1 to 6]
In the production of the magnetic toner 1, except that the types and amounts of the polyester resin A and the hydrophobized magnetic material were changed as shown in Table 4 above, the magnetic toners 2 to 14 and Comparative magnetic toners 1 to 6 were obtained. All the toners had a weight average diameter (D4) in the range of 7.6 μm to 8.5 μm. The physical properties of the produced magnetic toners are as shown in Table 4 above.

[Method for Producing Magnetic Toner 7 for Comparison]
The raw materials shown below were premixed with a Henschel mixer FM10C (Mitsui Miike Chemical Co., Ltd.).
-Resin A-11 90.0 parts by mass-Hydrophobized magnetic substance 9 100.0 parts by mass-Iron complex of monoazo dye (T-77: manufactured by Hodogaya Chemical Co., Ltd.) 1.0 part by mass-Hydrocarbon wax HNP-51 (Nippon Seiwa Co., Ltd.) 2.0 parts by mass Thereafter, the direct temperature in the vicinity of the outlet of the kneaded product was 150 ° C. with a biaxial kneading extruder (PCM-30: Ikegai Iron Works Co., Ltd.) set at a rotation speed of 200 rpm The set temperature was adjusted so as to be kneaded.

  The obtained melt-kneaded product was cooled, and the cooled melt-kneaded product was coarsely pulverized with a cutter mill. Then, the obtained coarsely pulverized product was finely pulverized using a turbo mill T-250 (manufactured by Turbo Kogyo Co., Ltd.) with a feed amount of 20 kg / hr and an air temperature adjusted to 40 ° C. Thereafter, classification was performed using a multi-division classifier utilizing the Coanda effect, thereby obtaining comparative magnetic toner particles 7 having a weight average particle diameter (D4) of 7.6 μm.

1.0 part of hydrophobic silica having a specific surface area of 200 m ² / g according to the BET method is added to the Henschel mixer (Mitsui Miike Chemical Co., Ltd.) with respect to the obtained comparative magnetic toner particles 7 (100 parts by mass). Then, a magnetic toner 7 for comparison was obtained. Table 4 shows the physical properties of the comparative magnetic toner 7 obtained.

[Method for Producing Magnetic Toner 8 for Comparison]
In the production of the comparative magnetic toner 7, the same operation was performed except that the resin A-11 was changed to the resin A-12, and a comparative magnetic toner 8 having a weight average diameter (D4) of 7.8 μm was obtained.

[Method for Producing Magnetic Toner 9 for Comparison]
According to the following procedure, comparative magnetic toner particles 9 were produced by an emulsion aggregation method.

(Preparation of resin particle dispersion A)
The following components were put into a round bottom flask and stirred.
-Resin A-13 100.0 parts by mass-Ethyl acetate 60.0 parts by mass-Isopropyl alcohol 15.0 parts by mass After confirming that resin A-13 was sufficiently mixed, 10% aqueous ammonia 3.0 Part by weight was added. Then, 1000 mass parts of ion-exchange water was dripped, and the resin emulsion was obtained by carrying out phase inversion emulsification. Next, a resin particle dispersion A was obtained by removing an organic solvent (ethyl acetate, isopropyl alcohol) under reduced pressure using an evaporator. When the size of the resin particles in the dispersion A was measured using a particle size measuring device (Horiba, Ltd., LA-700), the average particle size was 0.15 μm.

(Preparation of resin particle dispersion B)
Resin particle dispersion B was obtained in the same manner as in the preparation of resin particle dispersion A except that resin A-13 was changed to resin A-9. When the size of the resin particles in the dispersion B was measured using a particle size measuring device (Horiba, Ltd., LA-700), the average particle size was 0.18 μm.

(Preparation of wax dispersion)
The following components were charged into a predetermined container.
-Hydrocarbon wax (HNP-51, Nippon Seiwa Co., Ltd.) 100.0 parts by mass-Anionic surfactant (Neogen RK, Daiichi Kogyo Seiyaku) 10.0 parts by mass-Ion-exchanged water 390.0 parts by mass Next In addition, the charge is dispersed using a homogenizer (made by IKA: Ultra Turrax T50) while being heated to 95 ° C., and then dispersed by a pressure discharge type homogenizer to disperse a wax component. A liquid was prepared. When measured using a particle size measuring apparatus (LA-700, manufactured by Horiba, Ltd.), the average particle size was 0.30 μm.

(Preparation of magnetic dispersion)
The following components were dispersed for 30 minutes using a homogenizer (manufactured by IKA: Ultra Tarrax T50) to obtain a magnetic dispersion.
-Hydrophobized magnetic material 9 100.0 parts by mass-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) 10.0 parts by mass-Ion-exchanged water 1200.0 parts by mass

(Preparation of comparative magnetic toner particles 9)
The following components and ion exchange water in an amount of 15% solid content were charged into a separable flask equipped with a stirrer, a condenser and a thermometer.
-Resin particle dispersion A 75.0 parts by weight as a solid content-17.0 parts by weight as a wax dispersion liquid-100.0 parts by weight as a solid dispersion liquid Next, a homogenizer (manufactured by IKA: Ultrata) The contents of the flask were mixed thoroughly using Lux T50). Thereafter, 0.36 part of polyaluminum chloride was gradually added as a flocculant, and then dispersion with a homogenizer was continued for 30 minutes. After 30 minutes, the content was heated to 50 ° C., and 25.0 parts by mass of resin particle dispersion B was gradually added as a solid content. Thereafter, an appropriate amount of an aqueous sodium hydroxide solution was added to adjust the pH in the system to 6.9, and the mixture was heated to 85 ° C. with stirring and held for 3 hours. After cooling, the solid content was sufficiently washed with filtration and ion-exchanged water, and then the solid content was dried and classified using a multi-division classifier utilizing the Coanda effect, thereby obtaining comparative magnetic toner particles 9. .

(Adjustment of comparative magnetic toner 9)
For the obtained comparative magnetic toner particles 9 (100 parts by mass), 1.2 parts of hydrophobic silica having a specific surface area by the BET method of 200 m ² / g was supplied to a Henschel mixer (Mitsui Miike Chemical Co., Ltd.). And made an external addition. As a result, a comparative magnetic toner 9 having a weight average particle diameter (D4) of 7.1 μm was obtained.

[Example 1]
(Measurement method of empty lumps)
The empty dust of the magnetic toner 1 was evaluated as follows. As described above, the empty dust is an index of the dispersibility of the magnetic material contained in the magnetic toner. If there is a lot of empty dust, the dispersion of the magnetic material becomes non-uniform and the charge distribution becomes broad, resulting in poor transferability. It is a trend. In the present invention, not only actual transferability but also measurement of empty dams was performed, and evaluation was made as “excellent in performance” when both transferability and empty damping were good. In addition, a dry product or a pulverized product before air classification was used as a sample used for empty dama measurement.

1. Preparation before measurement (i) 50 g of an electrolytic aqueous solution used in the above-described method for measuring the weight average particle diameter (D4) of magnetic toner, and 0.4 g of Contaminone N (manufactured by Wako Pure Chemical Industries, Ltd.) as a surfactant In a 100 cc glass beaker, the dispersion was prepared by mixing well.

  (Ii) Here, Contaminone N (manufactured by Wako Pure Chemical Industries, Ltd.) is 10 mass of a neutral detergent for washing a precision measuring machine with a pH of 7 comprising a nonionic surfactant, an anionic surfactant and an organic builder. % Aqueous solution. After adding 1.0 g of the pre-classification sample of magnetic toner particles 1 to the beaker containing the dispersion liquid (i), the sample was allowed to stand for 12 hours or more, and it was confirmed that the magnetic toner had settled.

  (Iii) “Method for measuring weight average particle diameter (D4) of magnetic toner” (7-1), (7-3) The ultrasonic disperser was prepared and adjusted in the same procedure. However, 150 g of the electrolyte solution was put in a round bottom beaker.

  (Iv) A beaker was set in the same manner as in “Method for measuring weight average particle diameter (D4) of magnetic toner” (7-4), and ultrasonic dispersion treatment was continued for 30 seconds. Thereafter, the beaker was taken out and a measurement sample dispersed in the aqueous solution was attracted by applying a neodymium magnet to the bottom of the beaker. At this time, it was confirmed whether or not bubbles were biting the sample, and if the bubbles were floating, the ultrasonic dispersion treatment was repeated many times with the upper limit being 5 times until the bubbles were removed.

2. Measurement (i) After sufficiently removing bubbles, ultrasonic treatment was further continued for 60 seconds, and after completion of the ultrasonic treatment, a beaker was left on the neodymium magnet for 30 seconds.

  (Ii) After standing, 5.0 ml is sampled from the center of the aqueous solution layer in the beaker. All the sampled samples (5.0 ml) were dropped into the round bottom beaker prepared in (iii). At this time, the solution was dropped while taking care not to generate bubbles.

  (Iii) “Measurement of weight average particle diameter (D4) of magnetic toner” (7-6) In the same manner as in (7-6), measurement was performed using Coulter counter Multisizer 3 until the number of measured particles reached 50000. Here, the measurement time (seconds) until it reaches 50000 pieces is set as a numerical value of empty lumps. It means that the shorter the measurement time, the more empty lumps in the measured aqueous solution, that is, the measurement sample contains more empty lumps.

(Transferability and image density)
Transferability and image speed were evaluated using an image forming apparatus (LBP-3100, manufactured by Canon Inc.). In the evaluation, the printing speed was reset (modified) from 16 sheets / minute to 40 sheets / minute. This is because the durability can be strictly evaluated by changing the printing speed to 40 sheets / minute.

  Using this modified image forming apparatus, five solid images were output continuously in a high temperature and high humidity environment (32.5 ° C./80% RH) using magnetic toner 1, and these output images Were used for evaluation of transferability according to the following criteria. Thereafter, a test was performed in which 10,000 horizontal lines with a printing rate of 1% were printed in a single intermittent mode.

  After the test of printing 10,000 sheets, the image forming apparatus was left in a high-temperature and high-humidity environment for one day, and five solid images were printed. The transferability was evaluated according to the following criteria. Further, the image density of the output image was measured with a Macbeth reflection densitometer (manufactured by Macbeth).

(1) Criteria for judging transferability Uniform solid image with no density unevenness.
B. If it is transmitted through strong light, it will not bother you with some uneven density.
C. Some density unevenness can be seen even if it is not transparent to light.
D. Some of the density unevenness can be seen even if it is not transparent to light, but if it is transparent to light, the density unevenness is seen over a wide range.
E. Density unevenness can be seen over a wide range that can be seen without being transparent to light.

  The evaluation results of the magnetic toner 1 are shown in Table 5.

<Examples 2 to 14 and Comparative Examples 1 to 9>
Evaluation was performed in the same manner and conditions as in Example 1 except that any of magnetic toners 2 to 14 and comparative magnetic toners 1 to 9 was used instead of magnetic toner 1. The evaluation results are shown in Table 5.

  100: electrostatic latent image carrier (photoconductor), 102: developing sleeve, 114: transfer member (transfer roller), 116: cleaner, 117: charging member (charging roller), 121: laser generator (latent image forming means) , Exposure device), 123: laser, 124: register roller, 125: transport belt, 126: fixing device, 140: developing device, 141: stirring member

Claims (6)

A magnetic toner containing magnetic toner particles containing a resin and a hydrophobically treated magnetic material,
The magnetic toner particles are obtained by granulating a magnetic toner composition containing the resin containing polyester resin A, a hydrophobized magnetic material, and a polymerizable monomer in an aqueous medium, Produced by polymerizing the body,
The polyester resin A is represented by the following formula (1)

Containing 0.1 mol% or more and 30.0 mol% or less of an isosorbide unit represented by
The polyester resin A is contained in an amount of 1.0 to 20.0 parts by mass with respect to 100.0 parts by mass of the resin, and with respect to 100.0 parts by mass of the hydrophobized magnetic material. 2.0 parts by weight or more and 15.0 parts by weight or less,
The methanol concentration in the mixed solvent when the permeability of the solution obtained by mixing the hydrophobized magnetic substance and the methanol / water mixed solvent reaches 50% is 50% by volume or more and 80% by volume or less. Characteristic magnetic toner.   The magnetic toner according to claim 1, wherein the acid value of the polyester resin A is 25.0 (mgKOH / g) or less.   3. The magnetic toner according to claim 1, wherein the hydrophobized magnetic material is magnetic iron oxide surface-treated with a silane compound having a hydrocarbon group having 2 to 6 carbon atoms.   The carbon content of the hydrophobized magnetic material and derived from the silane compound is 0.42% by mass or more and 0.80% by mass or less based on the magnetic iron oxide. The magnetic toner described in 1.   After washing the hydrophobized magnetic material with styrene, the amount of carbon derived from the silane compound remaining in the hydrophobized magnetic material is 0.40% by mass or more and 0.70% based on the magnetic iron oxide. 5. The magnetic toner according to claim 3, wherein the magnetic toner is not more than mass%. The silane compound is obtained by subjecting alkoxysilane to hydrolysis.
The magnetic toner according to claim 1, wherein the alkoxysilane has a hydrolysis rate of 50% or more.

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