JP2016224251A - Magnetic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic toner that has excellent fixability and excellent transferability over a long-term use.SOLUTION: There is provided a magnetic toner that has a melting point (Tm) of 55°C or more and 90°C or less, and contains a crystalline polyester having a polyester part and a vinyl polymer part and a magnetic substance having a silane compound having a specific partial structure immobilized on the surface.SELECTED DRAWING: None

Description

  The present invention relates to a toner used in an image forming method such as an electrophotographic method, an electrostatic recording method, and a toner jet method.

  Many methods are known as electrophotographic methods. In general, an electrostatic latent image is formed on an electrostatic charge image carrier (hereinafter also referred to as “photoconductor”) by using a photoconductive substance by various means. Next, the latent image is developed with toner to form a visible image, and if necessary, the toner image is transferred to a recording medium such as paper, and then the toner image is fixed on the recording medium by heat or pressure, etc. Is what you get. Examples of such an image forming apparatus using electrophotography include a copying machine and a printer.

  These printers and copiers are moving from analog to digital, and have excellent reproducibility of latent images and high resolution, and at the same time, stable image quality is required even when used for a long period of time. Furthermore, a toner having a good fixing property is required as an energy saving measure, and a binder resin and a wax are improved to improve the fixing property.

  Focusing on the wax here, it is generally known that the use of a large amount of wax reduces the viscosity at the time of melting and improves the fixability. On the other hand, when a large amount of wax is used, durability and storage stability tend to be inferior, and conventionally, a combination of fixing means, durability, and storage stability has been achieved by combining with means such as external addition.

  However, such a toner having improved fixability is liable to have a problem that developability and transferability are deteriorated as a result of coalescence or deforming after long-term use. In particular, the present inventors considered transferability as an issue and focused their attention.

  A number of techniques for improving development by using crystalline polyester as a technique for improving the fixability have been disclosed (for example, Patent Document 1 and Patent Document 2). However, even these proposed crystalline polyester-containing toners are insufficient to maintain the transferability deterioration with long-term use, and improvements are demanded.

JP 2014-35506 A Japanese Patent No. 4571975

  An object of the present invention is to provide a magnetic toner that is excellent in fixability and excellent in transferability in long-term use.

  The aforementioned problems are solved by the present invention described below.

The toner of the present invention is a magnetic toner having magnetic toner particles containing a binder resin, a crystalline polyester, and a magnetic material,
The binder resin contains 70% by mass or more of a styrene acrylic resin based on the mass of the binder resin.
The crystalline polyester is
i) Melting point (Tm) is 55 ° C. or higher and 90 ° C. or lower,
ii) having a polyester moiety and a vinyl polymer moiety;
ii-1) The polyester portion has a unit represented by the following formula (1),
ii-2) The weight average molecular weight (Mw) of the vinyl polymer moiety is from 3000 to 40000,
A silane compound having a partial structure represented by the following formula (2) is immobilized on the surface of the magnetic material,
The difference between the solubility parameter of the unit represented by the following formula (1) and the solubility parameter of the partial structure represented by the following formula (2) is 0.80 or more and 1.20 or less. .

  (In the formula, m represents an integer of 4 to 14, and n represents an integer of 6 to 16.)

  (In the formula, R represents a hydrocarbon group having 3 or more carbon atoms.)

  According to the present invention, it is possible to provide a magnetic toner having excellent fixability and excellent transferability in long-term use.

FIG. 2 is a schematic cross-sectional view illustrating an example of an image forming apparatus that can suitably use the toner of the present invention.

  First, consider the transfer process in electrophotography. In the transfer process, a transfer bias is applied to a transfer roller or the like, and the toner image on the latent image carrier is electrostatically attached to a medium such as paper. According to the study by the present inventors, when magnetic materials are present in an uneven manner in the magnetic toner particles (hereinafter referred to as unevenly distributed particles) or a large number of irregularly shaped particles and coalesced particles are present, the transferability tends to be inferior. It was.

  Particles with uneven magnetic dispersion such as unevenly distributed particles often have not only transferability but also developability. Therefore, for example, when used for a long time in a laser beam printer without replenishment, unevenly distributed particles, irregularly shaped particles, and coalesced particles accumulate in the developing device, so that the transferability tends to be lower than the initial value.

  On the other hand, there is a demand for improvement in fixing properties. Conventionally, a method of adding a low melting point wax or crystalline polyester has been used for fixing improvement. However, these materials often exude to the surface as they melt upon receiving heat. When used for a long time, for example, in a system in which a magnetic toner carrier or a developing device is equipped with agitation, the magnetic toner receives heat locally by rubbing against these members. At this time, the coalescence particles may be generated or the particles may be deformed due to the low melting point material oozing out. In this case, as described above, the transferability is lowered.

  As a result of intensive studies on the combination of the structure of crystalline polyester and the combination of magnetic materials with respect to the problem of transferability deterioration when such a magnetic toner is used for a long period of time, the above problems can be solved in a specific combination. The headline and the invention were completed. The toner of the present invention will be described below.

The toner of the present invention is a magnetic toner having magnetic toner particles containing a binder resin, a crystalline polyester, and a magnetic material,
The binder resin contains 70% by mass or more of a styrene acrylic resin based on the mass of the binder resin.
The crystalline polyester is
i) Melting point (Tm) is 55 ° C. or higher and 90 ° C. or lower,
ii) having a polyester moiety and a vinyl polymer moiety;
ii-1) The polyester portion has a unit represented by the following formula (1),
ii-2) The weight average molecular weight (Mw) of the vinyl polymer moiety is from 3000 to 40000,
A silane compound having a partial structure represented by the following formula (2) is immobilized on the surface of the magnetic material,
The difference between the solubility parameter of the unit represented by the following formula (1) and the solubility parameter of the partial structure represented by the following formula (2) is 0.80 or more and 1.20 or less. Is.

  (In the formula, m represents an integer of 4 to 14, and n represents an integer of 6 to 16.)

  (In the formula, R represents a hydrocarbon group having 3 or more carbon atoms.)

[Crystalline polyester]
In the present invention, the resin having “crystallinity” means that the resin has an endothermic peak observed in differential scanning calorimetry (DSC).

The crystalline polyester used in the present invention is
i) Melting point is 55-90 ° C.
ii) having a polyester moiety and a vinyl polymer moiety;

  The melting point is preferably within the above range from the viewpoints of developability, fixability, and toner production stability.

  Next, the vinyl polymer portion of the crystalline polyester will be described. The magnetic toner of the present invention contains a styrene acrylic resin because it is excellent in terms of material dispersibility, ease of application to various toner production methods, development and transferability. According to the study by the present inventors, the polyester and the styrene acrylic resin have low affinity and are hardly compatible, but the compatibility can be greatly improved by introducing a vinyl polymer site into the crystalline polyester.

  Focusing on the polyester part, the polyester has many ester bonds with high polarity. On the other hand, since the silane compound having the partial structure represented by the formula (2) is immobilized on the surface of the magnetic substance, a large number of siloxane bonds exist on the surface, but the siloxane bond is also highly polar. . For this reason, polyesters having close polarities and the magnetic material of the present invention tended to fit together.

  That is, since the crystalline polyester having the vinyl polymer portion is compatible with both the styrene acrylic resin and the magnetic material of the present invention, it functions as a dispersion aid for the magnetic material, so that the uneven distribution of the magnetic material as described above is achieved. I think I was able to suppress it.

  However, the effect on the dispersion of the magnetic material was observed only in the combination of the crystalline polyester and the magnetic material satisfying specific conditions. The above conditions were first the relationship between the solubility parameter of the magnetic substance and the crystalline polyester, the structure of the magnetic substance surface, the molecular weight of the vinyl polymer part of the crystalline polyester, and the structure of the polyester part.

  First, the relationship between the solubility parameters of the magnetic substance and the crystalline polyester will be described. Specifically, the difference between the solubility parameter of the unit represented by the formula (1) and the solubility parameter of the partial structure represented by the formula (2) is 0.80 or more and 1.20 or less. The unit represented by formula (1) refers to the structure of the polyester moiety. Further, the solubility parameter referred to here is obtained from the Fedors equation described later. Generally, the solubility parameter is more easily compatible as the difference between the numerical values is smaller. However, according to the study by the present inventors, it was found that the numerical values of the crystalline polyester and the magnetic material should be close, but they should be separated to some extent. This is because the crystalline polyester of the present invention is compatible with both styrene acrylic resin and magnetic material, and if the polyester part and magnetic material are excessively compatible, the interaction between the vinyl polymer and styrene acrylic is inhibited. Yes.

  Second, the surface structure of the magnetic material will be described. The magnetic body needs to have a silane compound having a partial structure represented by the formula (2) immobilized on the surface. Immobilization of the silane compound on the surface of the magnetic material is aimed at enhancing the dispersibility of the resin by imparting hydrophobicity. When the carbon number of R is 3 or less, sufficient hydrophobicity can be obtained, and it becomes easy to encapsulate in the toner particles even during production in an aqueous medium.

  Third, the molecular weight of the vinyl polymer portion of the crystalline polyester will be described. The vinyl polymer portion needs to have a certain length in order to exert a dispersion effect on the styrene acrylic resin, but if it is too short, it has no effect. Specifically, the weight average molecular weight (Mw) was required to be 3000 to 40000. This is a range in which the crystalline polyester not only has a sufficiently high affinity for the styrene acrylic resin but also has excellent fixability. Furthermore, since the viscosity at the time of melting of the crystalline polyester is slightly increased by bonding the vinyl polymer portion, it also tends to suppress exudation when receiving local heat. The molecular weight of the vinyl polymer portion is more preferably 4000 to 15000 from the viewpoint of fixability.

  Fourth, the polyester part of the crystalline polyester of the present invention will be described. The polyester portion has a unit represented by the formula (1). This indicates that the repeating unit has a structure in which a dicarboxylic acid having 4 to 14 methylene groups (m = 4 to 14) and a diol having 6 to 16 methylene groups (n = 6 to 16) are condensed. ing. In addition, it is preferable that the crystalline polyester of this invention has 90 mass% or more of the structure derived from the said repeating unit in all the polyester parts of crystalline polyester. When the number of methylene groups in the formula (1) is within the specified range, appropriate hydrophobicity is obtained, and compatibility with the styrene acrylic resin is appropriate.

  Moreover, m + n is preferably 10 to 22 from the viewpoint of transferability and developability. By appropriately adjusting m and n within this range, the melting point of the crystalline polyester and the solubility parameter of the polyester part can be controlled.

  Further, the difference between the average value of m and n in the formula (1) and the carbon number of R in the formula (2) is preferably 2 to 6 from the viewpoint of transferability and developability.

The presence or absence of the styrene acrylic resin and the structure and content of the crystalline polyester can be confirmed by the following method. First, tetrahydrofuran is added to the magnetic toner to dissolve most of the resin components. Here, things other than resin, such as a magnetic substance and an external additive, are removed by centrifugation using a specific gravity difference. Thereafter, structural analysis of the tetrahydrofuran-soluble component such as nuclear magnetic resonance spectroscopy ( ¹ H-NMR) can be performed to determine whether a styrene acrylic resin is contained. Since the resin component remaining undissolved is a mixture composed mainly of crystalline polyester and a release agent, the crystalline polyester is isolated by preparative LC and then subjected to nuclear magnetic resonance spectroscopy ( ¹ H-NMR) or the like. By analyzing the structure, the structure can be specified.

  In addition, regarding the content of crystalline polyester in the magnetic toner, the magnetic toner itself and the crystalline polyester after separation are compared with each other by comparing the nuclear magnetic resonance spectroscopic analysis results to obtain the peak area ratio specific to the crystalline polyester. can get. From the structure of the crystalline polyester thus obtained, the solubility parameter is obtained by the calculation method described later.

  Furthermore, by separately preparing a calibration curve for the amount of vinyl polymer and peak area in nuclear magnetic resonance spectroscopy, the content of vinyl polymer in the crystalline polyester can be known from the result of nuclear magnetic resonance spectroscopy. By taking these mass ratios, a mass-based ratio of the polyester portion and the vinyl polymer portion of the crystalline polyester can be obtained.

  The solubility parameter can be controlled by the type and amount of monomer added. In order to increase the solubility parameter, a monomer having a large solubility parameter (a monomer having a short carbon chain) may be added. To reduce the solubility parameter, a monomer having a low solubility parameter (a monomer having a long carbon chain) May be added.

  The unit represented by the above formula (1) can be obtained by condensation of a dicarboxylic acid and a diol.

  As the dicarboxylic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid and the like can be used.

  Examples of the diol include 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14- Tetradecanediol, 1,16-hexadecanediol and the like can be used.

  Further, a known vinyl monomer such as styrene, methyl methacrylate or n-butyl acrylate can be used for the vinyl polymer portion of the crystalline polyester of the present invention. Particularly preferably, when styrene is used, it effectively works as a compatible site for the styrene acrylic resin and exhibits more plasticity at the time of melting.

  In the crystalline polyester, the ratio based on the mass of the polyester part and the vinyl polymer part (polyester part / vinyl polymer part) is preferably 40/60 to 95/5, more preferably 40/60 to 80/20. . Within this range, sufficient low-temperature fixability can be obtained by the sharp melt property that is a characteristic of the polyester part, and the transferability is excellent.

  The crystalline polyester in the present invention is preferably a block polymer having a polyester moiety and a vinyl polymer moiety.

  The polyester portion having crystallinity facilitates a design that achieves compatibility with styrene acrylic resin and maintaining crystallinity when a toner is added. Further, by having an amorphous vinyl polymer portion, it is possible to finely disperse the crystalline polyester in the styrene acrylic resin, and the low-temperature fixability is further improved. In addition, since the block polymer is in a form in which the crystalline part and the amorphous part are connected by the main chain, since it does not take a three-dimensional structure, the dispersion state with respect to the styrene acrylic resin is uniform. Is also excellent in transferability.

  The definition of block polymer includes a polymer composed of a plurality of linearly linked blocks (a glossary of basic terms in polymer science by the Polymer Society International Pure Chemical Union) The present invention follows that definition.

  The content of the crystalline polyester is preferably 2.0 to 40.0 parts by mass, more preferably 2.0 to 30.0 parts by mass, per 100 parts by mass of the binder resin. When the crystalline polyester is 2.0 parts by mass or more, the effect of the present invention on the fixing property and magnetic substance dispersion is improved. When the crystalline polyester is 40.0 parts by mass or less, the surface oozing amount of the crystalline polyester is suppressed, and the transferability is excellent.

  It is preferable that the weight average molecular weight of crystalline polyester is 12000-45000. Within this range, the dispersion of the magnetic substance in the magnetic toner particles is exhibited and the compatibility with the styrene acrylic resin is excellent.

  The method for producing the crystalline polyester of the present invention is not particularly limited, but since it contains a polyester site and a vinyl polymer site, it is necessary to select a production method for obtaining a structure in which both are chemically bonded. A preferable production method is illustrated below.

  (1) Polyester is obtained by condensation polymerization of dicarboxylic acid and diol. At this time, a known esterification catalyst such as a tin compound such as dibutyltin oxide, tin dioctylate, titanium (IV) isopropoxide, or a titanium compound may be used as the esterification catalyst. Next, polymerization is advanced by adding a monomer having an unsaturated group and a functional group capable of transesterification such as a carboxyl group or an ester group, and a vinyl monomer such as styrene or (meth) acrylic acid. Thus, the desired polymer is obtained. When prepared by such a manufacturing method, a reaction for cross-linking the polyester sites occurs at the time of vinyl polymer production, so a part of the graft structure is taken. For this reason, the inventors refer to such crystalline polyesters as graft polymers.

  (2) A vinyl polymer having a carboxylic acid or a carboxylic acid ester at one or both ends is produced, and a diol and a dicarboxylic acid are appropriately added to the vinyl polymer, followed by a condensation polymerization reaction to obtain a target polymer. For the polycondensation reaction, a known esterification catalyst can be used as in (1). Regarding the production of a vinyl polymer having one or both ends of a carboxylic acid or a carboxylic acid ester, a method using a functional group-containing initiator and a method using a functional group-containing chain transfer agent are known methods. As a method using a functional group-containing initiator, for example, Koji Ishizu, “Journal of Polymer Science Part A: Polymer Chemistry” (USA), John Wiley & Sons, 1990, pp. 28, 1887. As a method using a functional group-containing chain transfer agent, for example, Toshiro Uchida, et al., “Journal of Polymer Science Part A: Polymer Chemistry” (USA), John Wiley & Sons, Vol. -3058. ]. What was produced with such a manufacturing method takes the form of the block polymer as mentioned above.

  (3) A polyester is obtained in the same manner as (1). Thereafter, a polyester site and vinyl polymer site block copolymer is obtained according to the ATRP method. By using so-called precision radical polymerization, a polymer in which one block of polyester and vinyl polymer exists in one molecule can be prepared. What was produced with such a manufacturing method takes the form of the block polymer as mentioned above.

  The monomer which has an unsaturated group and has a functional group which can perform transesterification is illustrated. Acrylic acid, fumaric acid, methacrylic acid, citraconic acid, maleic acid, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, and anhydrides of these carboxylic acids, alkyl (C1-C2) esters And the like. Among these, acrylic acid, methacrylic acid, fumaric acid, maleic acid and derivatives of these carboxylic acids are preferable from the viewpoint of reactivity.

  The following can be illustrated as a vinyl monomer. Styrene, α-methylstyrene, α-ethylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p -Ethyl styrene, 2,4-dimethyl styrene, pn-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn- Decyl styrene, pn-dodecyl styrene, ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone, vinyl Naphthalene, acryloni Examples include tolyl, methacrylonitrile, and acrylamide.

  As a polymerization initiator used for polymerizing the above-described vinyl polymer in producing a crystalline polyester, an oil-soluble initiator and a polymerization initiator other than those used in the present invention are within the range not inhibiting the effects of the present invention. A water-soluble initiator can be used as appropriate. For example, oil-soluble initiators include azo compounds such as 2,2′-azobisisobutyronitrile; t-butylperoxyneodecanoate, t-hexylperoxypivalate, lauroyl peroxide, t- Examples thereof include peroxides such as butyl peroxy 2-ethylhexanoate, t-butyl peroxyisobutyrate, di-t-butyl peroxyisophthalate, and di-t-butyl peroxide.

  Water-soluble initiators include ammonium persulfate, potassium persulfate, 2,2′-azobis (N, N′-dimethyleneisobutyroamidine) hydrochloride, 2,2′-azobis (2-aminodinopropane) hydrochloric acid Salt, azobis (isobutylamidine) hydrochloride, sodium 2,2′-azobisisobutyronitrile sulfonate, 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2 -Hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}, hydrochloride ferrous sulfate or hydrogen peroxide.

[Magnetic material]
The form of the magnetic material that can be used in the present invention will be described below.

  The magnetic body of the present invention has a silane compound having a partial structure represented by the formula (2) immobilized on the surface thereof. This is because, as described above, in addition to the purpose of improving the dispersibility inside the toner by the interaction with the crystalline polyester of the present invention, it is very preferable when the toner is produced in an aqueous medium.

In order to obtain a magnetic material in which a silane compound having a partial structure represented by the formula (2) is immobilized, for example, there is a technique of treating the surface of the magnetic material using a silane coupling agent, a titanium coupling agent, or the like. Can be mentioned. More preferably used is a silane coupling agent, which is represented by the general formula (I).
R _m SiY _n (I)
[Wherein, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a functional group such as an alkyl group, a vinyl group, an epoxy group, or a (meth) acryl group, and n represents 1 to 3] Indicates an integer. However, m + n = 4. ]

  Examples of the silane coupling agent represented by the general formula (I) include n-propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, n- Examples include octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane. In the present invention, those in which Y in the general formula (I) is an alkyl group having 3 or more carbon atoms can be preferably used. Among these, an alkyl group having 3 to 10 carbon atoms is preferable, and an alkyl group having 3 to 6 carbon atoms is particularly preferable.

  When using the said silane coupling agent, it is possible to process independently or to process in combination of several types. When using several types together, you may process separately with each coupling agent, and may process simultaneously.

  When the surface treatment is performed by a dry method, the coupling agent treatment is performed on the magnetic powder that has been washed, filtered, and dried. When wet surface treatment is performed, after the oxidation reaction is completed, the dried product is redispersed, or after completion of the oxidation reaction, the iron oxide body obtained by washing and filtering is not dried but in another aqueous medium. The dispersion is redispersed and a coupling treatment is performed. In the present invention, either a dry method or a wet method can be selected as appropriate.

  It is preferable that the surface of the magnetic material is fixed to the surface of the magnetic powder to some extent. Specifically, it is preferable from the viewpoint of developability that the amount of carbon derived from the silane compound fixed on the surface of the magnetic material is 0.35 to 0.60% by mass based on the magnetic material.

The magnetic body of the present invention is obtained by subjecting a magnetic powder not subjected to surface treatment to surface treatment. The magnetic substance is mainly composed of magnetic iron oxide such as triiron tetroxide and γ-iron oxide, and may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon. These magnetic powders is preferably a BET specific surface area by nitrogen adsorption method is 2~30m ² / g, more preferably 3~28m ² / g. Further, those having a Mohs hardness of 5 to 7 are preferred. The shape of the magnetic powder includes polyhedron, octahedron, hexahedron, spherical shape, needle shape, scale shape, etc., but those having low anisotropy such as polyhedron, octahedron, hexahedron, spherical shape, etc. It is preferable in terms of enhancement.

  The magnetic material preferably has a number average particle diameter of 0.10 to 0.40 μm. In general, the smaller the particle size of the magnetic material, the higher the coloring power, but the magnetic material tends to aggregate, and the uniform dispersibility of the magnetic material in the toner is inferior.

  The number average particle diameter 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, a cured product obtained by curing in an atmosphere at a temperature of 40 ° C. for 2 days is obtained. The obtained cured product is used as a flaky sample by a microtome, and the particle diameters of 100 magnetic bodies in the field of view are measured with a transmission electron microscope (TEM) with a photograph with a magnification of 10,000 to 40,000 times. Then, the number average particle diameter 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 toner of the present invention can be produced, for example, by the following method. An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equivalent to or greater than the iron component to the ferrous salt aqueous solution. Air was blown in while maintaining the pH of the prepared aqueous solution at pH 7 or higher, and ferrous hydroxide was oxidized while heating the aqueous solution to 70 ° C. or higher. First, seed crystals serving as the core of the magnetic iron oxide powder were formed. Generate.

  Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. While maintaining the pH of the solution at 5 to 10, the reaction of ferrous hydroxide proceeds while blowing air to grow magnetic iron oxide powder with the seed crystal as the core. At this time, it is possible to control the shape and magnetic characteristics of the magnetic material by selecting an arbitrary pH, reaction temperature, and stirring conditions. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not less than 5. A magnetic material can be obtained by filtering, washing, and drying the magnetic material thus obtained by a conventional method.

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

  The magnetic toner particles of the present invention preferably contain 30.0 to 80.0 parts by mass of a magnetic material per 100 parts by mass of the binder resin because of excellent transferability and developability.

  The content of the magnetic substance in the magnetic toner can be measured using a thermal analysis apparatus manufactured by Perkin Elmer, 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.

  The structure of the silane compound can be confirmed as follows, for example.

First, the magnetic material is dispersed and stirred in styrene, and the silane compound not immobilized on the surface is washed away. After the washed magnetic material is dried, the magnetite is dissolved by leaving it in hydrochloric acid for several days. By analyzing the structure of the remaining silane compound such as nuclear magnetic resonance spectroscopy ( ¹ H-NMR, 29Si-NMR), the structure of the silane compound can be specified, and R in Formula (2) can be specified and dissolved. Parameter values can be calculated.

  In the magnetic toner of the present invention, in order to control the interaction between the crystalline polyester and the magnetic material, it is also preferable to adjust the content ratio of both. Specifically, it is preferable in terms of developability and transferability that the content of the magnetic substance and the crystalline polyester is magnetic substance / crystalline polyester = 95/5 to 75/25 on the basis of mass.

  As described above, the content of the magnetic substance can be measured using a thermal analyzer, TGA7, manufactured by PerkinElmer. Further, the content of the crystalline polyester can also be obtained by combining isolation by preparative LC and nuclear magnetic resonance spectroscopy as described above. Using these numerical values, a mass-based ratio is obtained.

[Binder resin]
The binder resin used in the toner of the present invention contains 70% by mass or more of styrene acrylic resin with respect to the total amount of the binder resin. More preferably, it is 80 mass% or more.

  The styrene acrylic resin is a copolymer of styrene and an acrylic monomer (acrylic acid, acrylic ester, methacrylic acid, methacrylic ester), for example, styrene-methyl acrylate copolymer, styrene-acrylic acid. Ethyl copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer Examples thereof include styrene-butyl methacrylate copolymer and styrene-dimethylaminoethyl methacrylate copolymer.

  The binder resin can also be used in combination with other known resins. Other resins include homopolymers of styrene such as polystyrene and polyvinyltoluene and substituted products thereof; styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-vinylmethyl ether. Copolymer, Styrene-vinyl ethyl ether copolymer, Styrene-vinyl methyl ketone copolymer, Styrene-butadiene copolymer, Styrene-isoprene copolymer, Styrene-maleic acid copolymer, Styrene-maleic acid ester copolymer Styrene copolymers such as polymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic acid resin And the like.

  The following can be illustrated as a polymerizable monomer which forms the said styrene acrylic resin. Examples of the styrene polymerizable monomer include styrene; styrene polymerizable monomers such as α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, and p-methoxy styrene. Acrylic polymerizable monomers include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate And acrylic polymerizable monomers such as n-octyl acrylate and cyclohexyl acrylate. Methacrylic polymerizable monomers include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate. And methacrylic polymerizable monomers such as n-octyl methacrylate.

  In addition, the manufacturing method of a styrene acrylic resin is not specifically limited, A well-known method can be used.

  The toner produced according to the present invention preferably has a weight average particle diameter (D4) of 3.0 to 12.0 μm, more preferably 4.0 to 10.0 μm. Within the above range, good fluidity can be obtained and development can be performed faithfully to the latent image.

  The toner of the present invention can be produced by any known method. First, when manufacturing by a pulverization method, for example, a binder resin, a colorant, an ester wax, a low melting point material, a charge control agent and other necessary components and other additives are mixed in a Henschel mixer, a ball mill, etc. Mix thoroughly with a vessel. Thereafter, the toner material is dispersed or dissolved by using a heat kneader such as a heating roll, a kneader, or an extruder to disperse or dissolve the toner material, and after cooling and solidification, pulverization, and surface treatment as necessary to obtain toner particles. be able to. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.

  The pulverization step can be performed by a method using a known pulverizer such as a mechanical impact type or a jet type. Further, it is preferable to further pulverize by applying heat or to add a mechanical impact to the auxiliary. Further, a hot water bath method in which finely pulverized (classified as necessary) toner particles are dispersed in hot water, a method of passing in a hot air stream, or the like may be used.

  Examples of means for applying a mechanical impact force include a method using a mechanical impact pulverizer such as a kryptron system manufactured by Kawasaki Heavy Industries, Ltd. or a turbo mill manufactured by Turbo Industry. Also, like devices such as Hosokawa Micron's Mechano-Fusion System and Nara Machinery's Hybridization System, the toner is pressed against the inside of the casing by centrifugal force with high-speed rotating blades, and the force of compression force, friction force, etc. There is a method of applying a mechanical impact force to the toner.

  The toner particles according to the present invention can be produced by a pulverization method as described above. However, the toner particles can be produced in an aqueous medium such as a suspension polymerization method, a dissolution suspension method, or an emulsion aggregation method. A production method for obtaining toner particles by granulating the coalescent composition is more suitable.

  The toner particle production method will be described below using the most suitable suspension polymerization method among the toner particle production methods that can be used in the present invention.

  The above-mentioned polymerizable monomer, crystalline resin, wax, and other additives such as a colorant and a release agent are added to the above-mentioned styrene acrylic resin, homogenizer, ball mill, colloid mill, ultrasonic disperser. It is dissolved or dispersed uniformly by a dispersing machine such as A polymerization initiator is dissolved in this, and a polymerizable monomer composition is prepared. Next, the polymerizable monomer composition is put into an aqueous medium containing a dispersion stabilizer to granulate the polymerizable monomer composition droplets, and then polymerized to produce toner particles. .

  The polymerization initiator may be added at the same time when other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Also, a polymerization initiator can be added during or immediately after granulation and before starting the polymerization reaction.

  In the case of a polymerization method using an aqueous medium such as a suspension polymerization method, it is preferable to add a polar resin to the polymerizable monomer composition. By adding a polar resin, inclusion of a crystalline resin or wax is promoted.

  When a polar resin is present in the polymerizable monomer composition droplets suspended in the aqueous medium, the polar resin is not at the interface between the aqueous medium and the polymerizable monomer composition droplets due to the difference in affinity for water. Since it tends to move to the vicinity, polar resin is unevenly distributed on the surface of the toner particles. As a result, the toner particles form a core-shell structure.

  As the polar resin, a polyester resin or a carboxyl-containing styrene resin is preferable. When these polar resins are unevenly distributed on the surface of the toner particles to form a shell, the lubricity of the polar resin itself can be expected.

  As the polyester-based resin, a resin obtained by condensation polymerization of an acid component monomer and an alcohol component monomer described below can be used.

  Acid monomers include terephthalic acid, isophthalic acid, phthalic acid, fumaric acid, maleic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, camphor Examples include acids, cyclohexanedicarboxylic acid, and trimellitic acid.

  Examples of alcohol component monomers include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, and 1,4-bis (hydroxymethyl). ) Cycloalkylene glycols and polyalkylene glycols, bisphenol A, hydrogenated bisphenol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, glycerin, trimethylolpropane, and pentaerythritol.

  As the carboxyl group-containing styrene resin, styrene acrylic acid copolymer, styrene methacrylic acid copolymer, styrene maleic acid copolymer, etc. are preferable, and styrene-acrylic acid ester-acrylic acid copolymer is particularly preferable. It is preferable because the charge amount can be easily controlled.

  The carboxyl group-containing styrenic resin more preferably contains a monomer having a primary or secondary hydroxyl group. Specific polymer compositions include styrene-2-hydroxyethyl methacrylate-methacrylic acid-methyl methacrylate copolymer, styrene-n-butyl acrylate-2-hydroxyethyl methacrylate-methacrylic acid-methyl methacrylate copolymer. And styrene-α-methylstyrene-2-hydroxyethyl methacrylate-methacrylic acid-methyl methacrylate copolymer. A resin containing a monomer having a primary or secondary hydroxyl group has a large polarity and has a better long-term storage stability.

  1.0-20.0 mass parts is preferable with respect to 100.0 mass parts of binder resin, and, as for content of polar resin, 2.0-10.0 mass parts is more preferable.

  In the present invention, a known wax may be used. Specifically, paraffin wax, microcrystalline wax, petroleum wax such as petrolatum and derivatives thereof, montan wax and derivatives thereof, hydrocarbon wax and derivatives thereof by Fischer-Tropsch method, polyolefin wax and derivatives thereof typified by polyethylene, Examples thereof include natural waxes such as carnauba wax and candelilla wax, and derivatives thereof. Derivatives include oxides, block copolymers with vinyl monomers, and graft modified products. Further, alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid or compounds thereof; acid amides, esters, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes, and animal waxes. These can be used alone or in combination.

  Among these, when a polyolefin wax, a hydrocarbon wax by the Fischer-Tropsch method, or a petroleum wax is used, the effect of improving developability and transferability is further enhanced. These wax components may be added with an antioxidant within a range that does not affect the chargeability of the toner. Further, these wax components are preferably used in an amount of 1.0 to 30.0 parts by mass with respect to 100.0 parts by mass of the binder resin.

  The melting point of the wax component used in the present invention is preferably in the range of 30 to 120 ° C, more preferably in the range of 60 to 100 ° C.

  By using the wax component exhibiting the thermal characteristics as described above, the releasing effect is efficiently expressed and a sufficient fixing region is secured.

  When obtaining toner particles using the suspension polymerization method, it is preferable to use a colorant that has been subjected to a hydrophobic treatment with a substance that does not inhibit polymerization in consideration of the polymerization inhibitory property and water phase transferability of the colorant. .

  Moreover, a charge control agent can also be used as needed. As the charge control agent, known ones can be used, but a charge control agent that has a high tribocharging speed and can stably maintain a constant triboelectric charge amount is preferable. Further, when the toner particles are produced by a suspension polymerization method, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous medium is required.

  As the charge control agent, there are one that controls the toner to negative charge and one that controls the toner to positive charge. Examples of controlling the toner to be negatively charged include the following. Monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic acid and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, Examples include anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarenes, and charge control resins.

  Examples of the charge control agent that controls the toner to be positively charged include the following. Guanidine compounds; imidazole compounds; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts that are analogs thereof And these lake pigments; triphenylmethane dyes and lake pigments (including phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, and Ferrocyanide); metal salt of higher fatty acid; charge control resin.

  Said charge control agent can be used individually or in combination of 2 or more types.

  Among these charge control agents, metal-containing salicylic acid compounds are preferable, and those in which the metal is aluminum or zirconium are particularly preferable.

  The addition amount of the charge control agent is preferably 0.01 to 20.0 parts by mass, more preferably 0.5 to 10.0 parts by mass with respect to 100.0 parts by mass of the binder resin.

  As the charge control resin, it is preferable to use a polymer or copolymer having a sulfonic acid group, a sulfonic acid group, or a sulfonic acid ester group. The polymer having a sulfonic acid group, a sulfonic acid group or a sulfonic acid ester group preferably contains a sulfonic acid group-containing acrylamide monomer or a sulfonic acid group-containing methacrylamide monomer in a copolymerization ratio of 2% by mass or more. . More preferably, it is 5% by mass or more in terms of copolymerization ratio. The charge control resin preferably has a glass transition temperature (Tg) of 35 to 90 ° C., a peak molecular weight (Mp) of 10,000 to 30,000, and a weight average molecular weight (Mn) of 25,000 to 50,000. . When this charge control resin is used, preferable triboelectric charging characteristics can be imparted without affecting the thermal characteristics required of the toner particles. Furthermore, since the charge control resin contains a sulfonic acid group, the dispersibility of the charge control resin itself in the dispersion of the colorant, and the dispersibility of the colorant are improved, and the coloring power, transparency, and The triboelectric charging characteristics can be further improved.

  In order to polymerize the polymerizable monomer, a polymerization initiator may be used. Examples of the polymerization initiator that can be used in the present invention include organic peroxide initiators and azo polymerization initiators. The following are mentioned as an organic peroxide type | system | group initiator. Benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, bis (4-t-butylcyclohexyl) peroxydicarbonate, 1, 1-bis (t-butylperoxy) cyclododecane, t-butylperoxymaleic acid, bis (t-butylperoxy) isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropyl Peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, tert-butyl-peroxypivalate, and the like.

  As the azo polymerization initiator, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile) ), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobismethylbutyronitrile, and the like.

  A redox initiator in which an oxidizing substance and a reducing substance are combined can also be used as the polymerization initiator. Examples of the oxidizing substance include hydrogen peroxide, inorganic peroxides of persulfate (sodium salt, potassium salt, and ammonium salt), and oxidizing metal salt of tetravalent cerium salt. Reducing substances include reducing metal salts (divalent iron salts, monovalent copper salts, and trivalent chromium salts), ammonia, lower amines (methylamine and ethylamine such as ethylamine having 1 to 6 carbon atoms). Amine), amino compounds such as hydroxylamine, sodium thiosulfate, sodium hydrosulfite, sodium bisulfite, sodium sulfite, and reducing sulfur compounds of sodium formaldehyde sulfoxylate, lower alcohols (1-6 carbon atoms) ), Ascorbic acid or a salt thereof, and a lower aldehyde (having 1 to 6 carbon atoms).

  The polymerization initiator is selected with reference to the 10-hour half-life temperature, and is used alone or in combination. Although the addition amount of the said polymerization initiator changes with the target degree of polymerization, generally 0.5-20.0 mass parts is added with respect to 100.0 mass parts of polymerizable monomers.

  Further, a known chain transfer agent or polymerization inhibitor may be further added and used to control the degree of polymerization.

  Various crosslinking agents can also be used when polymerizing a polymerizable monomer. Cross-linking agents include divinylbenzene, 4,4′-divinylbiphenyl, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, glycidyl acrylate, glycidyl methacrylate, trimethylolpropane triacrylate, trimethylolpropane triacrylate. A polyfunctional compound such as methacrylate may be mentioned.

  As the dispersion stabilizer used when preparing the aqueous medium, known dispersion stabilizers of inorganic compounds and organic compound dispersion stabilizers can be used. As dispersion stabilizers for inorganic compounds, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate , Barium sulfate, bentonite, silica, and alumina. On the other hand, examples of the organic compound dispersion stabilizer include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid and salts thereof, and starch. The amount of the dispersion stabilizer used is preferably 0.2 to 20.0 parts by mass with respect to 100.0 parts by mass of the polymerizable monomer.

  When an inorganic compound dispersion stabilizer is used, a commercially available one may be used as it is, but the inorganic compound may be produced in an aqueous medium in order to obtain a finer particle size dispersion stabilizer. For example, tricalcium phosphate can be obtained by mixing an aqueous sodium phosphate solution and an aqueous calcium chloride solution with high stirring.

  An external additive may be externally added to the toner particles in order to impart various properties to the toner. Examples of the external additive for improving the fluidity of the toner include inorganic fine particles such as silica fine particles, titanium oxide fine particles, and double oxide fine particles thereof. Of the inorganic fine particles, silica fine particles and titanium oxide fine particles are preferable. For example, the toner of the present invention can be obtained by adding inorganic fine particles to toner particles and adhering them to the surface of the toner particles. The external addition of the inorganic fine particles can be performed by a known method, for example, a method of performing a mixing treatment using an FM mixer (Nippon Coke Kogyo Co., Ltd.).

Examples of the silica fine particles include dry silica or fumed silica produced by vapor phase oxidation of silicon halide, and wet silica produced from water glass. As the inorganic fine particles, dry silica having less silanol groups on the surface and inside the silica fine particles and less Na ₂ O, (SO ₃ ) ₂ — is preferable. Further, it may be a composite fine particle of silica and another metal oxide produced by using a metal halogen compound such as aluminum chloride, titanium chloride or the like together with a silicon halogen compound in the production process of dry silica.

  The inorganic fine particles whose surface is hydrophobized can achieve adjustment of the triboelectric charge amount of the toner, improvement of environmental stability, and improvement of fluidity under high temperature and high humidity. Therefore, it is preferable. When the inorganic fine particles added to the toner absorb moisture, the triboelectric charge amount and fluidity of the toner are lowered, and the developability and transferability are likely to be lowered.

  Treatment agents for hydrophobizing inorganic fine particles include unmodified silicone varnishes, various modified silicone varnishes, unmodified silicone oils, various modified silicone oils, silane compounds, silane coupling agents, other organosilicon compounds, and An organic titanium compound is mentioned. Among these, silicone oil is preferable. These treatment agents may be used alone or in combination.

  The total amount of inorganic fine particles added is preferably 1.0 to 5.0 parts by mass, more preferably 1.0 to 2.5 parts by mass with respect to 100.0 parts by mass of toner particles. The external additive preferably has a particle size of 1/10 or less of the average particle size of the toner particles from the viewpoint of durability when added to the toner.

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

  Although an image forming apparatus for magnetic one-component jumping development is shown here, it may be used for any method of jumping development or contact development.

  Hereinafter, the measurement method of various physical properties according to the present invention will be described.

<Calculation method of solubility parameter (SP value)>
The SP value in the present invention was determined using the following Fedors equation (4). The values of Δei and Δvi here refer to the evaporation energy and molar volume (25 ° C.) of atoms and atomic groups according to Table 3-9 of “Basic Science of Coating”, pages 54 to 57, 1986 (Tsubaki Shoten). I made it.
δi = [Ev / V] ^1/2 = [Δei / Δvi] ^1/2 formula (4)
Ev: Evaporation energy V: Molar volume Δei: Evaporation energy of atom or atomic group of component i Δvi: Molar volume of atom or atomic group of component i For example, hexanediol is atomic group (—OH) × 2 + (— CH ₂ ) × 6, and the calculated SP value is obtained by the following equation.
δi = [Δei / Δvi] ^1/2 = [{(5220) × 2 + (1180) × 6} / {(13) × 2 + (16.1) × 6}] ^1/2
As a result, the SP value (δi) is 11.95.

<Measurement method of molecular weight>
The weight average molecular weight (Mw) of the crystalline polyester is measured by gel permeation chromatography (GPC) as follows.

First, crystalline polyester is dissolved in tetrahydrofuran (THF) at room temperature. The obtained solution is filtered through a solvent-resistant membrane filter “Mysholy disk” (manufactured by Tosoh Corporation) having a pore diameter of 0.2 μm to obtain a sample solution. A sample solution is adjusted so that the density | concentration of the component soluble in THF may be 0.8 mass%. Using this sample solution, measurement is performed under the following conditions.
Device: High-speed GPC device "HLC-8220GPC" (manufactured by Tosoh Corporation)
Column: LF-604 double eluent: THF
Flow rate: 0.6 ml / min
Oven temperature: 40 ° C
Sample injection amount: 0.020 ml
In calculating the molecular weight of the sample, a standard polystyrene resin (for example, trade names “TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F— 10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500 ", manufactured by Tosoh Corporation) are used.

  The molecular weight of the vinyl polymer portion of the crystalline polyester is measured by hydrolyzing the polyester portion of the crystalline polyester.

  Specifically, 5 ml of dioxane and 1 ml of a 10% by mass potassium hydroxide aqueous solution are added to 30 mg of crystalline polyester, and the polyester part is hydrolyzed by shaking at a temperature of 70 ° C. for 6 hours. Thereafter, the solution is dried to prepare a sample for measuring the molecular weight of the vinyl polymer site. The subsequent operation is performed in the same manner as the measurement of the molecular weight of the crystalline polyester.

<Measuring method of melting point of crystalline polyester>
The melting point of the crystalline polyester is measured in accordance with ASTM D3418-82 using a differential scanning calorimeter “Q1000” (manufactured by TA Instruments).

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

  Specifically, 5 mg of crystalline polyester is precisely weighed, placed in an aluminum pan, an empty aluminum pan is used as a reference, and the temperature rising rate is within a measuring temperature range of 30 to 200 ° C. Measurement is performed at 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 maximum endothermic peak of the DSC curve in the temperature range of 30 to 200 ° C. in the second temperature raising process is taken as the melting point in the DSC measurement of the crystalline polyester of the present invention.

<Method for measuring the amount of carbon derived from a silane compound immobilized on the surface of a magnetic material>
The magnetic material used in the magnetic toner of the present invention is surface-treated with a silane compound having a hydrocarbon group. Among the treated silane compounds, components not immobilized on the surface can be removed by washing with a solvent. Therefore, the amount of silane compound immobilized on the surface of the magnetic material can be known by accurately measuring the amount of carbon contained in the magnetic material after the cleaning treatment.

  First, the magnetic material is washed with styrene. A glass vial with a capacity of 50 ml is charged with 20 g of styrene and 1.0 g of a magnetic material, and the glass vial is set in “KM Shaker” (model: V.SX) manufactured by Iwaki Sangyo Co., Ltd. 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 magnetic material and styrene are separated, and the magnetic material is sufficiently dried with a vacuum dryer.

  About the dried magnetic body, the amount of carbon per unit weight is measured for the magnetic body using a carbon / sulfur analyzer (EMIA-320V) manufactured by HORIBA. 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.

  In the present invention, the amount of carbon after washing is defined as the amount of carbon derived from the silane compound immobilized on the surface of the magnetic material.

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

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

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

  On the “Change Standard Measurement Method (SOM)” screen of the dedicated software, set the total count in the control mode to 50,000 particles, set the number of measurements once, and set the Kd value to “standard particles 10.0 μm” (Beckman Coulter Set the value obtained using By pressing the “Threshold / Noise Level Measurement Button”, the threshold and noise level are automatically set. In addition, the current is set to 1600 μA, the gain is set to 2, the electrolyte is set to ISOTON II, and the “aperture tube flush after measurement” is checked.

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

  The specific measurement method is as follows.

  (1) In a glass 250 ml round bottom beaker for exclusive use of Multisizer 3, 200 ml of the electrolytic aqueous solution is placed and set on a sample stand, and the stirrer rod is stirred counterclockwise at 24 rpm. Then, the dirt and bubbles in the aperture tube are removed by the “aperture flush” function of the dedicated software.

  (2) Put 30 ml of the aqueous electrolytic solution 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. 0.3 ml of a diluted solution obtained by diluting 3) with ion-exchanged water.

  (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 Tetora 150” (manufactured by Nikka Ki Bios) having an electrical output of 120 W is prepared. Into the water tank of the ultrasonic disperser, 3.3 l of ion-exchanged water is added, and 2 ml of Contaminone N is added to the water tank.

  (4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. And the height position of a beaker is adjusted so that the resonance state of the liquid level of the electrolyte solution in a beaker may become the maximum.

  (5) In a state where the electrolytic aqueous solution in the beaker of (4) is irradiated with ultrasonic waves, 10 mg of toner is added to the electrolytic aqueous solution little by little and dispersed. Then, the ultrasonic dispersion process is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water tank is appropriately adjusted so as to be 10 ° C. or higher and 40 ° C. or lower.

  (6) To the round bottom beaker (1) installed in the sample stand, the electrolyte aqueous solution (5) in which the toner is dispersed is dropped using a pipette, and the measurement concentration is adjusted to 5%. Measurement is performed until the number of measured particles reaches 50,000.

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

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited by the following examples. In the examples and comparative examples, all parts and% are based on mass unless otherwise specified.

<Manufacture of vinyl polymer 1>
In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen introduction tube, and a decompression device, 100.0 parts by mass of xylene was heated while being purged with nitrogen, and refluxed at a liquid temperature of 140 ° C. To this solution, 100.0 parts by mass of styrene and 10.0 parts by mass of dimethyl-2,2′-azobis (2-methylpropionate) were added dropwise over 3 hours, and after completion of the addition, the solution was stirred for 3 hours. . Thereafter, xylene and residual styrene were distilled off at 160 ° C. and 1 kPa to obtain vinyl polymer 1. Mw of vinyl polymer 1 was 6000.

<Manufacture of vinyl polymers 2-5>
Vinyl polymers 2 to 5 were obtained in the same manner as in the production of vinyl polymer 1 except that the production conditions were changed as shown in Table 1. Table 1 shows the physical properties of the obtained vinyl polymers 2 to 5.

<Production of crystalline polyester 1>
The following was put into a reaction vessel equipped with a stirrer, thermometer, nitrogen introduction tube, dehydration tube, and decompression device, and reacted at 160 ° C. for 5 hours in a nitrogen atmosphere.
-Vinyl polymer 1 159.1 parts by mass-Xylene 127.3 parts by mass-1,10-decanediol 105.3 parts by mass-Titanium (IV) isopropoxide 0.56 parts by mass Thereafter, 100.0 parts by mass of sebacic acid And reacted at 160 ° C. for 5 hours and at 180 ° C. for 4 hours. Furthermore, it was made to react until it became desired Mw at 180 degreeC and 1 kPa, and the crystalline polyester 1 which is a block polymer was obtained. Table 2 shows the physical properties of the obtained crystalline polyester 1.

<Production of crystalline polyester 2>
In a reaction vessel equipped with a stirrer, a thermometer, and a nitrogen introduction tube, 100.0 parts by mass of crystalline polyester 1 and 440.0 parts by mass of dehydrated chloroform were added and completely dissolved. Thereafter, 5.0 parts by mass of triethylamine was added, and 15.0 parts by mass of 2-bromoisobutyryl bromide was gradually added while cooling with ice. Thereafter, the mixture was stirred at room temperature (25 ° C.) for a whole day and night.

  The resin solution was gradually dropped into a container containing 550.0 parts by mass of methanol to reprecipitate the resin component, followed by filtration, purification, and drying to obtain purified polyester 1.

Subsequently, the following was put into a reaction vessel equipped with a stirrer, a thermometer, and a nitrogen introduction tube, and a polymerization reaction was performed at a temperature of 110 ° C. while stirring.
-Refined polyester 1 100.0 parts by mass-Styrene 300.0 parts by mass-Copper (I) bromide 3.5 parts by mass-Pentamethyldiethylenetriamine 8.5 parts by mass The reaction was stopped when the desired molecular weight was reached, Reprecipitation was performed with 250.0 parts by mass of methanol, filtration and purification to remove unreacted styrene and catalyst. Then, it dried with the vacuum dryer set to 50 degreeC, and obtained the crystalline polyester 2 which is a block polymer. Table 2 shows the physical properties of the obtained crystalline polyester 2.

<Production of crystalline polyesters 3-9, 15-19, 21>
Crystalline polyesters 2-9, 15-19, and 21 were obtained in the same manner as in the production of crystalline polyester 1 except that the raw materials and production conditions were changed as shown in Table 2. Table 2 shows the physical properties of the obtained crystalline polyesters 2 to 9, 15 to 19, and 21.

<Production of crystalline polyester 10>
Add 100.0 parts by mass of sebacic acid and 106.5 parts by mass of 1,12-dodecanediol to a reaction vessel equipped with a stirrer, thermometer, nitrogen introduction tube, dehydration tube, and decompression device, and stir. While heating to 130 ° C. After adding 0.7 part by mass of titanium (IV) isopropoxide, the temperature is raised to 160 ° C. and polycondensation is performed over 5 hours. 15.0 parts by mass of acrylic acid and 140.0 parts by mass of styrene were added dropwise over 1 hour. Stirring was continued for 1 hour while maintaining the temperature at 160 ° C., and then the monomer of the styrene resin component was removed at 8.3 kPa for 1 hour. Thereafter, the temperature was raised to 210 ° C., and the reaction was carried out until the desired molecular weight was reached, thereby obtaining crystalline polyester 10 as a graft polymer. Table 3 shows the physical properties of the obtained crystalline polyester 10.

<Production of crystalline polyesters 11-14, 22>
Crystalline polyesters 11 to 14 and 22 were obtained in the same manner as the production of the crystalline polyester 10 except that the raw materials and production conditions were changed as shown in Table 3. Table 3 shows the physical properties of the obtained crystalline polyesters 11 to 14 and 22.

<Production of crystalline polyester 20>
Add 100.0 parts by mass of octanedioic acid and 82.9 parts by mass of 1,6-hexanediol to a reaction vessel equipped with a stirrer, thermometer, nitrogen introduction tube, dehydration tube, and decompression device and stir. While heating to 140 ° C. After adding 0.7 parts by mass of titanium (IV) isopropoxide as an esterification catalyst, the temperature is raised to 160 ° C. and polycondensation is performed over 7 hours. Thereafter, the temperature was raised to 180 ° C., and the mixture was reacted until the desired molecular weight was reached while reducing the pressure to obtain polyester 20. The crystalline polyester 20 had a weight average molecular weight (Mw) of 20,100, a melting point of 56 ° C., and a solubility parameter of 9.97.

<Manufacture of magnetic iron oxide>
50 liters of iron sulfate aqueous solution containing 2.0 mol / L of Fe ²⁺ is mixed and stirred with 55 liters of 4.0 mol / L sodium hydroxide aqueous solution, and a ferrous salt aqueous solution containing ferrous hydroxide colloid is mixed. Obtained. This aqueous solution was kept at 85 ° C., and an oxidation reaction was performed while blowing air at 20 L / min to obtain a slurry containing core particles.

  The obtained slurry was filtered and washed with a filter press, and then the core particles were dispersed again in water and reslurried. To this reslurry liquid, sodium silicate that is 0.20% by mass in terms of silicon per 100 parts of the core particles is added, the pH of the slurry liquid is adjusted to 6.0, and the magnetic oxidation having a silicon-rich surface is performed by stirring. Iron particles were obtained. The obtained slurry was filtered and washed with a filter press, and further reslurried with ion-exchanged water. To this reslurry liquid (solid content 50 g / L), 500 g (10% by mass with respect to magnetic iron oxide) of ion exchange resin SK110 (manufactured by Mitsubishi Chemical) was added, and ion exchange was performed by stirring for 2 hours. Thereafter, the ion exchange resin was removed by filtration through a mesh, filtered and washed with a filter press, dried and crushed to obtain magnetic iron oxide having a number average diameter of 0.23 μm.

<Production of Silane Compound 1>
30 parts of iso-butyltrimethoxysilane was added dropwise to 70 parts of ion exchange water with stirring. Then, this aqueous solution was kept at pH 5.5 and a temperature of 40 ° C., and hydrolyzed by dispersing for 120 minutes at a peripheral speed of 0.46 m / s using a disper blade. Thereafter, the pH of the aqueous solution was adjusted to 7.0 and cooled to 10 ° C. to stop the hydrolysis reaction. Thus, an aqueous solution containing the silane compound 1 was obtained.

<Production of Silane Compound 2>
30 parts of iso-propyltrimethoxysilane was added dropwise to 70 parts of ion exchange water with stirring. Thereafter, this aqueous solution was maintained at pH 4.2 and a temperature of 25 ° C., and hydrolyzed by dispersing for 60 minutes at a peripheral speed of 0.46 m / s using a disper blade. Thereafter, the pH of the aqueous solution was adjusted to 7.0 and cooled to 10 ° C. to stop the hydrolysis reaction. Thus, an aqueous solution containing the silane compound 2 was obtained.

<Production of Silane Compound 3>
30 parts of n-decyltrimethoxysilane was added dropwise to 70 parts of ion-exchanged water while stirring. Then, this aqueous solution was maintained at pH 6.1 and a temperature of 53 ° C., and hydrolyzed by dispersing for 360 minutes at a peripheral speed of 0.46 m / s using a disper blade. Thereafter, the pH of the aqueous solution was adjusted to 7.0 and cooled to 10 ° C. to stop the hydrolysis reaction. Thus, an aqueous solution containing the silane compound 3 was obtained.

<Production of Silane Compound 4>
30 parts of n-hexyltrimethoxysilane was added dropwise to 70 parts of ion-exchanged water with stirring. Then, this aqueous solution was maintained at pH 5.7 and temperature 45 ° C., and hydrolyzed by dispersing for 180 minutes at a peripheral speed of 0.46 m / s using a disper blade. Thereafter, the pH of the aqueous solution was adjusted to 7.0 and cooled to 10 ° C. to stop the hydrolysis reaction. Thus, an aqueous solution containing the silane compound 4 was obtained.

<Production of Silane Compound 5>
30 parts of ethyltrimethoxysilane was added dropwise to 70 parts of ion-exchanged water while stirring. Thereafter, this aqueous solution was kept at pH 3.3 and a temperature of 10 ° C., and hydrolyzed by dispersing it at a peripheral speed of 0.46 m / s for 30 minutes using a disper blade. Thereafter, the hydrolysis reaction was stopped by setting the pH of the aqueous solution to 7.0. Thus, an aqueous solution containing the silane compound 5 was obtained.

<Manufacture of magnetic body 1>
100 parts of the above magnetic iron oxide was put into a high speed mixer (LFS-2 type manufactured by Fukae Pautech Co., Ltd.), and silane compound 1 (8.0 parts) was added dropwise over 2 minutes while stirring at a rotational speed of 2000 rpm. Thereafter, the mixture was mixed and stirred for 5 minutes. Next, in order to enhance the fixing property of the silane compound, after drying at 40 ° C. for 1 hour to reduce moisture, the mixture was dried at 110 ° C. for 3 hours to proceed the condensation reaction of the silane compound. Then, it pulverized and obtained the magnetic body 1 through the sieve with an opening of 100 micrometers. Table 4 shows the physical properties of the magnetic body 1.

<Manufacture of magnetic body 2>
In the production of the magnetic body 1, magnetic bodies 2 to 6 were obtained in the same manner except that the silane compound used was changed as shown in Table 4. Table 4 shows the physical properties of the magnetic bodies 2 to 6.

<Manufacture of magnetic toner particles 1>
After adding 450 parts of 0.1 mol / L-Na ₃ PO ₄ aqueous solution to 720 parts of ion-exchanged water and heating to 60 ° C., 67.7 parts of 1.0 mol / L-CaCl ₂ aqueous solution was added. An aqueous medium containing a dispersion stabilizer was obtained.
・ Styrene 79.0 parts ・ N-Butyl acrylate 21.0 parts ・ Divinylbenzene 0.6 parts ・ Monoazo dye iron complex (T-77: Hodogaya Chemical Co., Ltd.) 1.5 parts ・ Magnetic substance 1 90.0 parts Amorphous saturated polyester resin 5.0 parts (Amorphous saturated polyester resin obtained by condensation reaction of bisphenol A ethylene oxide and propylene oxide adducts with terephthalic acid; Mw = 9500, acid value = 2.2 mgKOH / g, glass transition temperature = 68 ° C.)
The above formulation was uniformly dispersed and mixed using an attritor (manufactured by Mitsui Miike Chemical Co., Ltd.) to obtain a monomer composition. This monomer composition was heated to 63 ° C., and 10 parts by mass of the crystalline polyester 1 described in Table 2 and 15 parts by mass of paraffin wax (HNP-9 manufactured by Nippon Seiwa Co., Ltd.) were added and mixed. Dissolved.

During the aqueous medium, a monomer composition obtained by dissolving the crystalline polyester 1 and paraffin wax were charged, 60 ° C., T. under N ₂ atmosphere K. The mixture was stirred at 12000 rpm for 10 minutes with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) and granulated. Thereafter, 6.0 parts by mass of a polymerization initiator t-butyl peroxypivalate was added while stirring with a paddle stirring blade, and the temperature was raised to 70 ° C. and reacted for 4 hours. After completion of the reaction, the suspension was heated to 100 ° C. and held for 2 hours. Thereafter, as a cooling step, ice was added to the suspension, and the suspension was cooled from 100 ° C. to 50 ° C. at a rate of 40 ° C./min, and then allowed to cool to room temperature. Thereafter, hydrochloric acid was added to the suspension and thoroughly washed to dissolve the dispersion stabilizer, followed by filtration and drying to obtain magnetic toner particles 1. The manufacturing method and prescription are shown in Table 5.

<Production of magnetic toner particles 2 to 28>
As shown in Table 5, the magnetic toner particles 1 were changed except that the materials used and the number of added parts were changed and the amount of the dispersion stabilizer was adjusted so that the weight average particle diameter (D4) was 6.0 to 9.0 μm. Magnetic toner particles 2 to 28 were obtained in the same manner as in the production. Table 5 shows the physical properties of the magnetic toner particles obtained.

<Manufacture of magnetic toner particles 29>
The following materials were mixed in advance, melt-kneaded with a biaxial extruder, the cooled kneaded product was roughly pulverized with a hammer mill, and the resulting finely pulverized product was classified to obtain magnetic toner particles 29.
-Crystalline polyester 1 100.0 parts by mass-Magnetic substance 1 100.0 parts by mass-Iron complex of monoazo dye (T-77: manufactured by Hodogaya Chemical Co., Ltd.) 1.5 parts by mass-Paraffin wax (manufactured by Nippon Seiwa Co., Ltd.) HNP-9) 5.0 parts by mass The physical properties of the magnetic toner particles 29 are shown in Table 5.

<Manufacture of Magnetic Toner 1-19 and Comparative Magnetic Toner 1-10>
100 parts by mass of magnetic toner particles 1 and 0.8 parts by mass of hydrophobic silica fine powder obtained by subjecting dry silica fine particles having a BET specific surface area of 300 m ² / g (primary particle size 8 nm) to hexamethyldisilazane treatment, Magnetic toner 1 was obtained by mixing using a Henschel mixer (Mitsui Miike Chemical Co., Ltd.).

  Further, magnetic toners 2 to 19 and comparative magnetic toners 1 to 10 were obtained in the same manner except that the magnetic toner particles 1 were changed to magnetic toner particles 2 to 29. Each of the obtained magnetic toners had a weight average particle diameter (D4) of 6.0 to 9.0 μm, and an endothermic peak derived from the crystalline polyester was observed in DSC measurement.

<Examples 1 to 19 and Comparative Examples 1 to 10>
The following evaluations were performed using the obtained toners 1 to 19 and comparative magnetic toners 1 to 10. The evaluation results are shown in Table 6.

[Initial developability]
As the image forming apparatus, an LBP 3410 (monochrome laser beam printer, manufactured by Canon Inc.) equipped with a cartridge for LP3410 filled with toner was used. In the evaluation of initial developability, an image forming apparatus was used that was left in a normal temperature and humidity environment (temperature 23 ° C., humidity 60%) for one day. As recording paper, A4 color laser copy paper (Canon, 80 g / m ² ) was used.

  Five solid images were continuously output under normal temperature and humidity conditions, and the image density of the five solid images obtained was measured using a Macbeth reflection densitometer (manufactured by Macbeth). These worst values were defined as solid density, and the higher the solid density, the better the developability. The evaluation results are shown in Table 6.

[Fixability]
As the image forming apparatus, an LBP 3410 equipped with a cartridge for LP3410 filled with toner was used. In addition, modification was made so that development bias adjustment was possible. In the evaluation of the fixability, an image forming apparatus was used that was left in a low temperature and low humidity environment (temperature 15 ° C., humidity 10%) for one day. The low-temperature and low-humidity environment is a more severe environment for fixing because the toner is in a cold state. As the recording paper, FOX RIVER BOND paper (110 g / m ² ) left for one day in a low temperature and low humidity environment was used. This recording paper is a thick paper having relatively large surface irregularities, and is a severe paper in evaluating the rubbing of the printed image. The evaluation procedure is shown below.

First, a solid image was printed in a low-temperature and low-humidity environment using an image forming apparatus left in a low-temperature and low-humidity environment. The image density of the obtained solid image was measured using a Macbeth reflection densitometer (manufactured by Macbeth Co.), and then the developing bias was adjusted so that the image density was 1.4 or more and 1.45 or less. Further, after being left for 1 hour in a low temperature and low humidity environment, one solid image was output with the adjusted bias setting. The obtained solid image was rubbed twice by applying a load of 55 g / cm ^{2 to} the Sylbon paper. The solid image after rubbing and the Sylbon paper used for rubbing were visually observed and evaluated according to the following criteria.
A: Image density uniformity is maintained even after rubbing.
B: Image density uniformity is maintained even after rubbing, but the Sylbon paper is slightly soiled.
C: Image density uniformity is maintained even after rubbing, but clear stains are present on the Sylbon paper.
D: The solid image after rubbing has a thin portion (non-uniform portion) whose density is low enough to be recognized when it is held over light.
E: The solid image after the rubbing has a clearly low density portion.

[Transferability evaluation]
As the image forming apparatus, an LBP 3410 equipped with a cartridge for LP3410 filled with toner was used. In the evaluation of transferability, an image forming apparatus that was left in a high temperature and high humidity environment (temperature 32.5 ° C., humidity 82.5%) for one day was used. The high-temperature and high-humidity environment is a harsher environment for the transfer because the paper contains a large amount of moisture, so that a transfer bias is not easily applied and a transfer failure is likely to occur. As recording paper, A4 color laser copy paper (manufactured by Canon, 80 g / m ² ) left for one day in a high humidity and high temperature environment was used.

  Five solid black images are output by the above image forming apparatus, visually ranked according to the following evaluation criteria, and the density of the non-generated part and the generated part is determined by the Macbeth reflection densitometer for the part where the thin density due to the transfer failure occurs. The difference was compared.

After that, 15000 horizontal line images with a printing rate of 1% were output in the intermittent mode, and the transferability was evaluated again. When the durability of the magnetic toner is evaluated, the toner consumed during development is biased because there is a difference between the particles regarding the dispersion state of the magnetic material. According to the study by the present inventors, after the endurance, the dispersion of the magnetic substance is likely to remain non-uniform in the toner particles (coagulation in the particles is observed). Thus, the dispersion state of the magnetic material as described above can be strictly evaluated.
A: A uniform solid image was obtained for all five sheets, and no transfer failure was observed.
B: A slight transfer omission (density difference of 0.1 or less) is observed at one place among five sheets.
C: Slight transfer omission (density difference of 0.1 or less) is observed at 2 to 5 locations in 5 sheets, but no transfer omission exceeding density difference of 0.1 occurs.
D: Slight transfer omission (density difference of 0.1 or less) is observed at 6 or more positions in 5 sheets, but transfer omission exceeding density difference of 0.1 does not occur.
E: Transfer missing exceeding a density difference of 0.1 occurs.

Claims (7)

A magnetic toner having magnetic toner particles containing a binder resin, a crystalline polyester and a magnetic material,
The binder resin contains 70% by mass or more of a styrene acrylic resin based on the mass of the binder resin.
The crystalline polyester is
i) Melting point (Tm) is 55 ° C. or higher and 90 ° C. or lower,
ii) having a polyester moiety and a vinyl polymer moiety;
ii-1) The polyester portion has a unit represented by the following formula (1),
ii-2) The weight average molecular weight (Mw) of the vinyl polymer moiety is from 3000 to 40000,
A silane compound having a partial structure represented by the following formula (2) is immobilized on the surface of the magnetic material,
The difference between the solubility parameter of the unit represented by the following formula (1) and the solubility parameter of the partial structure represented by the following formula (2) is 0.80 or more and 1.20 or less. Magnetic toner.

(In the formula, m represents an integer of 4 to 14, and n represents an integer of 6 to 16.)

(In the formula, R represents a hydrocarbon group having 3 or more carbon atoms.)   The magnetic toner according to claim 1, wherein a ratio (polyester part / vinyl polymer part) based on a mass of the polyester part and the vinyl polymer part is 40/60 to 95/5.   3. The magnetic toner according to claim 1, wherein the amount of carbon derived from the silane compound immobilized on the surface of the magnetic material is 0.35 to 0.60 mass% based on the magnetic material.   The magnetic toner according to claim 1, wherein the content of the magnetic material is 30.0 to 80.0 parts by mass per 100 parts by mass of the binder resin. The content of the magnetic material and the crystalline polyester is based on mass,
Magnetic material / Crystalline polyester = 95/5 to 75/25
The magnetic toner according to claim 1, wherein   The magnetic toner according to claim 1, wherein the crystalline polyester is a block polymer.   The magnetic toner according to claim 1, wherein the content of the crystalline polyester is 2.0 to 40.0 parts by mass per 100 parts by mass of the binder resin.

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