JP6439708B2 - Magnetic toner - Google Patents

Description

  The present invention relates to a magnetic toner.

  Magnetic toners used in image forming apparatuses tend to require a certain level of magnetic retention. This is because the magnetic toner is transported to the developing region of the developing sleeve and the thin layer (toner thin film) is formed by the magnetic toner on the developing sleeve. The strength of magnetism is determined, for example, by the amount of magnetic powder added to the magnetic toner. If the amount of magnetic powder added is increased, the fixability of the magnetic toner to the recording medium may be reduced. Moreover, since magnetic powder has electrical conductivity, the amount of magnetic powder added tends to affect the charge amount of the magnetic toner. Therefore, the amount of magnetic powder added to the magnetic toner particles tends to be limited. Therefore, it is desired to improve the image quality while keeping the amount of magnetic powder added constant.

  For example, Patent Document 1 describes a toner containing at least a binder resin containing an amorphous resin and a crystalline resin, and a release agent. In this toner, the absolute value of the difference between the melting temperature of the crystalline resin and the melting temperature of the release agent is 5 ° C. or less. Further, when the solubility parameter SP values of the amorphous resin, the crystalline resin, and the release agent are SP (a), SP (c), and SP (w), respectively, SP (a)> SP (c)> SP (W), and the difference between SP (a) and SP (c) is 0.75 to 1.44.

JP 2014-44366 A

  However, although the toner described in Patent Document 1 has thermal characteristics (for example, reduction of image difference such as gloss and melting unevenness), the charging stability of the toner is insufficient. For this reason, it is difficult for the toner described in Patent Document 1 to have both low-temperature fixability, heat-resistant storage stability, and charging stability.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a magnetic toner that can combine low-temperature fixability, heat-resistant storage stability, and charging stability.

The magnetic toner of the present invention contains a plurality of toner particles. The toner particles include a binder resin, magnetic powder, and a charge control agent. The charge control agent is a resin having a chargeable functional group. The binder resin includes an amorphous polyester resin and a crystalline polyester resin. The content of the magnetic powder is 40 parts by mass or more with respect to 100 parts by mass of the binder resin. The solubility parameter SPa of the non-crystalline polyester resin, the solubility parameter SPc of the crystalline polyester resin, and the solubility parameter SPq of the charge control agent satisfy Formula (1), Formula (2), and Formula (3). .
SPa-SPq ≧ + 0.50 (1)
SPc−SPq ≧ + 0.50 (2)
0.20 ≦ | SPa−SPc | ≦ 0.70 (3)

  According to the present invention, it is possible to provide a magnetic toner capable of combining low-temperature fixability, heat-resistant storage stability, and charging stability.

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

<First Embodiment: Magnetic Toner>
The magnetic toner according to the first embodiment (hereinafter sometimes simply referred to as “toner”) is an electrostatic latent image developing toner. The toner according to the first embodiment is a powder composed of a large number of toner particles. The toner according to the first embodiment can be used in, for example, an electrophotographic apparatus (image forming apparatus).

  In an electrophotographic apparatus, an electrostatic latent image is developed using a developer containing toner. In the developing step, a charged toner is attached to the electrostatic latent image formed on the photoconductor to form a toner image. In the subsequent transfer process, the toner image on the photoconductor is transferred to a recording medium (for example, paper). Thereafter, the toner image is heated and pressurized to fix the toner image on the recording medium.

The toner according to the first embodiment has the following configuration (A).
Configuration (A): The charge control agent is a resin having a chargeable functional group. The solubility parameter SPa of the amorphous polyester resin, the solubility parameter SPc of the crystalline polyester resin, and the solubility parameter SPq of the charge control agent satisfy Expressions (1), (2), and (3).
SPa-SPq ≧ + 0.50 (1)
SPc−SPq ≧ + 0.50 (2)
0.20 ≦ | SPa−SPc | ≦ 0.70 (3)

  “Crystallinity” as shown in the “crystalline polyester resin” defined in the present invention indicates that there is a clear endothermic peak, not a stepwise endothermic change, in differential scanning calorimetry (DSC). Specifically, “crystallinity” means that the half-value width of the endothermic peak when measured at a heating rate of 10 ° C./min is 15 ° C. or less. On the other hand, a polyester resin in which the half-value width of the endothermic peak exceeds 15 ° C. or a polyester resin in which no clear endothermic peak is observed means non-crystalline (amorphous).

The solubility parameter δ (hereinafter sometimes referred to as an SP value) defined in the present invention is an SP value proposed by Fedors, and is represented by Formula (I).
δ = (ΣE _coh / ΣV) ^1/2 (I)
In Equation (I), E _coh represents the cohesive energy of the molecular structure, and V represents the volume of the molecule.

  Hereinafter, a factor for adjusting the SP value will be described by taking a crystalline polyester resin as an example. The SP value of the crystalline polyester resin can be adjusted by introducing a substituent into the crystalline polyester resin. More specifically, introduction of substituents into the crystalline polyester resin can be adjusted by, for example, the type of substituents or the number of substituents introduced.

  In general, the smaller the SP value, the stronger the hydrophobicity of the crystalline polyester resin, and the larger the SP value, the stronger the hydrophilicity of the crystalline polyester resin. In order to reduce the SP value of the crystalline polyester resin, for example, it can be adjusted by introducing a hydrophobic substituent. Examples of the hydrophobic substituent include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group. In order to increase the SP value of the crystalline polyester resin, for example, it can be adjusted by introducing a hydrophilic substituent. Examples of the hydrophilic substituent include a hydroxyl group, a carboxyl group, a cyano group, a nitro group, and an amino group. Similarly, the SP values of the amorphous polyester resin and the charge control agent can be controlled.

  The configuration (A) is useful for paralleling the low-temperature fixability, heat-resistant storage stability, and charge stability of the toner. In the toner having the configuration (A), SPa, SPc, and SPq satisfy Expressions (1), (2), and (3). For this reason, there exists a tendency for an amorphous polyester resin, a crystalline polyester resin, and a charge control agent to disperse | distribute. That is, in the non-crystalline polyester resin, the crystalline polyester resin and the charge control agent are easily easily dispersed as domains. Therefore, the toner having the configuration (A) suppresses the charge releasing property by the crystalline polyester resin and the magnetic powder, and maintains the charge retaining property and the charge releasing property in a well-balanced manner, so that the charge amount is appropriately maintained. be able to. Therefore, the toner having the configuration (A) is excellent in charging stability. In the toner having the configuration (A), the crystalline polyester resin becomes a melting start portion of the binder resin in a state of being well dispersed in the amorphous polyester resin. Therefore, the toner having the configuration (A) suppresses a decrease in low-temperature fixability due to the magnetic powder, and has a good balance between heat resistance and meltability. Therefore, the toner having the configuration (A) is excellent in low-temperature fixability and heat-resistant storage stability. From the above, the toner having the configuration (A) can have both low-temperature fixability, heat-resistant storage stability, and charging stability.

In order to further improve the low-temperature fixability, heat-resistant storage stability or charging stability of the toner, the toner has the following configurations (B), (C) and (D) in addition to the configuration (A). Is preferred.
Configuration (B): The temperature Ta of the amorphous polyester resin, the temperature Tc of the crystalline polyester resin, and the temperature Tq of the charge control agent are measured at a melt viscosity of 10,000 Pa · s measured with a Koka flow tester. , Expression (4) and Expression (5) are satisfied.
Tc <Tq <Ta (4)
Ta-Tc <+ 40 ° C. (5)
Configuration (C): The dispersion diameter of the crystalline polyester resin obtained by observing the cross section of the toner particles with a transmission electron microscope is 0.1 μm or less.
Configuration (D): The dispersion diameter of the charge control agent obtained by observing the cross section of the toner particles with a transmission electron microscope is 0.1 μm or more.

  The temperatures Ta, Tc, and Tq can be read from a semi-logarithmic graph measured by a Koka type flow tester (for example, “CFT-500D” manufactured by Shimadzu Corporation). Specifically, the measurement sample is set in the Koka flow tester, and the sample is melted and discharged under predetermined conditions. Thereby, melt viscosity data at a plurality of temperatures is obtained. A semi-logarithmic graph is obtained from the obtained data by plotting the horizontal axis as temperature and the vertical axis as logarithm of melt viscosity. A linear regression line is created from the obtained semilogarithmic graph, and the temperature at the intersection of the linear regression line and the melt viscosity of 10,000 Pa · s is obtained. In addition, the measuring method of temperature Ta, Tc, and Tq is demonstrated in detail in an Example.

  The configuration (B) is useful for improving the low-temperature fixability and charging stability of the toner. In the toner having the configuration (B), Ta, Tc, and Tq satisfy Expressions (4) and (5). When Ta and Tc satisfy Expression (4), the difference in melt viscosity between the crystalline polyester resin and the amorphous polyester resin does not become excessively large. Further, the crystalline polyester resin is easily dispersed in the binder resin. When Ta, Tc, and Tq satisfy Expression (5), the charge control agent is easily dispersed in the binder resin. Therefore, the toner having the configuration (B) can easily improve the low-temperature fixability and the charging stability.

  The dispersion diameter of the crystalline polytel resin is measured from an image obtained by photographing a cross section of the toner particles with a transmission electron microscope (TEM) (for example, “JSM-6700F” manufactured by JEOL Ltd.). The dispersion diameter of the crystalline polyester resin is an average value of the longest diameters measured from the image. The method for measuring the dispersion diameter of the crystalline polyester resin will be described in detail in Examples. Similarly, the dispersion diameter of the charge control agent is also measured. The dispersion diameter of the charge control agent is an average value of dispersion diameters measured from images.

  The configuration (C) is useful for improving the low-temperature fixability of the toner. In the toner having the configuration (C), the dispersion diameter of the crystalline polyester resin is 0.10 μm or less, and preferably 0.01 μm or more and 0.10 μm or less. When the dispersion diameter of the crystalline polyester resin is 0.10 μm or less, the crystalline polyester resin is favorably dispersed in the binder resin and tends to exhibit a low-temperature fixing function. Therefore, the toner having the configuration (C) can easily improve the low-temperature fixability. Further, when the dispersion diameter of the crystalline polyester resin is 0.01 μm or more, the crystalline polyester resin tends to exist as a domain in the binder resin.

  The configuration (D) is useful for improving the charging stability of the toner. In the toner having the configuration (D), the dispersion diameter of the charge control agent is 0.10 μm or more. When the dispersion diameter of the charge control agent is 0.10 μm or more, the charge control agent exists as a domain in the binder resin, and thus tends to exhibit a charge control function. Therefore, the toner having the configuration (D) can easily improve the charging stability. Further, the dispersion diameter of the charge control agent is preferably 2.00 μm or less, and more preferably 1.00 μm or less. When the dispersion diameter of the charge control agent is 2.00 μm or less, the magnetic toner can easily hold the charge control agent. As a result, adhesion to members in the image forming apparatus due to the charge control agent detached from the magnetic toner can be easily suppressed.

  The content of the magnetic powder is 40 parts by mass or more and 100 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the toner particles. When the content of the magnetic powder is 60 mass parts or less with respect to 100 mass parts of the toner particles, the image density of the formed image is hardly lowered.

  Hereinafter, the toner particles will be described. Further, a toner manufacturing method will be described. Acrylic and methacrylic are sometimes collectively referred to as “(meth) acrylic”. In addition, a compound and a derivative thereof may be generically named by adding “system” after the compound name. When the name of a polymer is expressed by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

<1. Toner particles>
As already described, the toner particles include a binder resin, magnetic powder, and a charge control agent. The toner particles may further contain an internal additive. Hereinafter, the binder resin, the magnetic powder, the charge control agent, and the internal additive will be described.

<1-1. Binder resin>
The binder resin includes a crystalline polyester resin and an amorphous polyester resin. Hereinafter, the crystalline polyester resin and the amorphous polyester resin will be described.

<1-1-1. Crystalline polyester resin>
The crystalline polyester resin is obtained, for example, by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component. A divalent or trivalent or higher alcohol can be used as the alcohol component. Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, di1,2-propanediol, polyethylene glycol, poly1,2-propanediol or polytetramethylene glycol; Bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylene bisphenol A or polyoxypropylene bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol Dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butane Examples thereof include trivalent or higher alcohols such as triol, trimethylolethane, trimethylolpropane, or 1,3,5-trihydroxymethylbenzene.

  Among these alcohol components, since crystallization of the polyester resin is easily promoted, aliphatic diols having 2 to 8 carbon atoms are preferable, and α, ω-alkanediols having 2 to 8 carbon atoms are preferable. More preferred is 1,4-butanediol or 1,6-hexanediol.

  In order to obtain a crystalline polyester resin, the proportion of the aliphatic diol having 2 to 10 carbon atoms in the alcohol component is preferably 80 mol% or more, more preferably 90 mol% or more. Similarly, the content of the component (single compound) contained in the largest amount in the alcohol component is preferably 70 mol% or more, more preferably 90 mol% or more, and 100 mol%. Most preferred.

  As the carboxylic acid component, a divalent or trivalent or higher carboxylic acid can be used. Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, alkyl succinic acid or alkenyl succinic acid (e.g. n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, divalent carboxylic acids such as n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid or isododecenyl succinic acid); 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5, 7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1, , 4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) methane , 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or trivalent or higher carboxylic acid such as empole trimer acid. These divalent or trivalent or higher carboxylic acid components may be used by being transformed into ester-forming derivatives such as carboxylic acid halides, carboxylic acid anhydrides or lower alkyl esters. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  Among these carboxylic acid components, an aliphatic dicarboxylic acid having 2 to 16 carbon atoms is preferable because α-ω has 2 to 16 carbon atoms. Alkanedicarboxylic acid is more preferred. The carboxylic acid component may further contain a monovalent carboxylic acid. Examples of the monovalent carboxylic acid include stearic acid.

  In order to obtain a crystalline polyester resin, the aliphatic dicarboxylic acid having 2 to 16 carbon atoms in the carboxylic acid component is preferably 70 mol% or more, and more preferably 90 mol% or more. Similarly, the content of the component (single compound) contained in the largest amount in the carboxylic acid component is preferably 70 mol% or more, more preferably 90 mol% or more, and 100 mol%. Is most preferred.

  The content of the crystalline polyester resin is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 3 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the toner particles. When the content of the crystalline polyester resin is 1 part by mass or more and 15 parts by mass or less, the low-temperature fixability of the toner is improved and the toner is difficult to be negatively charged.

  In order to improve the low-temperature fixability of the toner and effectively suppress the occurrence of offset when fixing at a high temperature, the crystallinity index of the crystalline polyester resin is 0.98 or more and 1.05 or less. preferable.

<1-1-2. Amorphous polyester resin>
When preparing an amorphous polyester resin, it is necessary to suppress crystallization of the obtained polyester resin. The method for suppressing crystallization of the polyester resin is not particularly limited, and examples of general crystallization suppressing methods include the following methods (A) to (C).

  Method (a): A method in which only a small amount of alcohol and carboxylic acid that promotes crystallization of the crystalline polyester resin are used or not.

  Method (b): A method of using two or more compounds as alcohol and carboxylic acid.

  Method (c): A method of suppressing crystallization by using an alcohol such as an alkylene oxide adduct of bisphenol A or a carboxylic acid such as an alkyl-substituted succinic acid.

  Among these methods for inhibiting crystallization, the method (c) is more preferable because the number of types of monomers is small and the preparation of an amorphous polyester resin is easy. In the method (c), crystallization is more easily suppressed as the amounts of alcohol (for example, an alkylene oxide adduct of bisphenol A) and carboxylic acid (for example, alkyl-substituted succinic acid) are increased. However, the amount of these monomers used is preferably adjusted as appropriate in consideration of the crystallinity index of the resulting polyester and other physical properties. In addition, an amorphous polyester resin may be used independently and may be used in combination of 2 or more type.

  The content of the amorphous polyester resin is preferably 30 parts by weight or more and 90 parts by weight or less, and more preferably 35 parts by weight or more and 85 parts by weight or less with respect to 100 parts by weight of the toner particles.

  The binder resin may include a resin other than the crystalline polyester resin and the amorphous polyester resin. Examples of such resins include acrylic acid resins, styrene-acrylic acid resins, polyamide resins, urethane resins, and vinyl alcohol resins.

<1-2. Magnetic powder>
Examples of magnetic powders include ferromagnetic metals, alloys of multiple types of ferromagnetic metals, magnetic powders composed mainly of ferromagnetic metals, magnetic powders doped with cobalt oxide or nickel in iron oxide, and no ferromagnetic metal elements. An alloy or chromium dioxide which becomes ferromagnetic by heat treatment. Examples of the ferromagnetic metal include iron, cobalt, and nickel. Iron may be used in the form of iron oxide (eg, magnetite or ferrite). As the magnetic powder, one of these magnetic powders may be used alone, or two or more thereof may be used in combination. Magnetite is preferred as the magnetic powder because the charge amount of the toner particles can be easily adjusted.

  The magnetic powder may be subjected to a surface treatment in order to improve the dispersibility of the magnetic powder in the binder resin and the durability of the magnetic powder. When surface-treating magnetic powder, examples of surface treatment agents include cationic surfactants, anionic surfactants, amphoteric surfactants, silane coupling agents, titanium coupling agents, aluminum coupling agents, phenolic resins, An epoxy resin, a cyanate resin, or a urethane resin can be used. You may use a surface treating agent individually by 1 type or in combination of 2 or more types.

<1-3. Charge control agent>
The charge control agent is a resin having a chargeable functional group (for example, a cationic copolymer). Examples of the chargeable functional group include a quaternary ammonium salt, a carboxylate salt, and a carboxyl group. Examples of the resin having a chargeable functional group include a resin having a chargeable functional group in a repeating unit of the resin. Examples of such a resin include a styrene resin having a quaternary ammonium salt, an acrylic acid resin having a quaternary ammonium salt, a styrene-acrylic acid resin having a quaternary ammonium salt, and a polyester having a quaternary ammonium salt. Resin, styrene resin having carboxylate, acrylic resin having carboxylate, styrene-acrylic acid resin having carboxylate, polyester resin having carboxylate, styrene resin having carboxyl group, carboxyl Examples thereof include an acrylic acid resin having a group, a styrene acrylic acid resin having a carboxyl group, and a polyester resin having a carboxyl group. Of these resins having a chargeable functional group, a styrene-acrylic acid resin having a quaternary ammonium salt or an acrylic acid resin having a quaternary ammonium salt is preferable. These resins may be oligomers or polymers. These resins may be used alone or in combination of two or more.

  Furthermore, the resin having a chargeable functional group may be combined with another resin. For example, a styrene-acrylic acid resin having a quaternary ammonium salt or an acrylic acid resin having a quaternary ammonium salt may be combined with a styrene resin by melt mixing or dissolution mixing.

  Hereinafter, a styrene-acrylic acid-based resin having a quaternary ammonium salt or an acrylic acid-based resin having a quaternary ammonium salt (hereinafter may be referred to as a cationic copolymer (A)) will be described. The cationic copolymer (A) comprises a styrene monomer (M1) and / or a (meth) acrylic acid alkyl ester monomer (M2) and a quaternary ammonium of a (meth) acrylic acid dialkylaminoalkyl monomer. Obtained by copolymerization with salt (M3).

  Examples of the styrene monomer (M1) include styrene, α-methylstyrene, p-methylstyrene, and p-chlorostyrene. Of these, styrene is preferred. Examples of the (meth) acrylic acid alkyl ester monomer (M2) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic. Examples include acid amyl, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, or stearyl (meth) acrylate. Of these, butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate is preferred.

  Since the quaternary ammonium salt (M3) of the (meth) acrylic acid dialkylaminoalkyl monomer can sufficiently impart positive chargeability, a compound represented by the general formula (II) is preferable.

In general formula (II), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group, and R ³ , R ⁴ and R ⁵ each independently represents an alkyl group. Examples of the alkylene group represented by R ² include a methylene group, an ethylene group, a propylene group, and a butylene group. Of these, an ethylene group is preferred. Examples of the alkyl group represented by R ³ , R ⁴ and R ⁵ include a methyl group, an ethyl group, a propyl group, an n-butyl group and a t-butyl group. Of these, a methyl group is preferred.

  Examples of the (meth) acrylate dialkylaminoalkyl include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate or dibutylaminoethyl (meth) acrylate. It is done. Of these, dimethylaminoethyl (meth) acrylate is preferred because it is inexpensive.

  As a manufacturing method of a cationic copolymer (A), the following method is mentioned, for example. The methacrylic acid dialkylaminoalkyl is quaternized with para-toluenesulfonic acid alkyl ester according to a conventional method to obtain a quaternary ammonium salt (M3) of (meth) acrylic acid dialkylaminoalkyl. Thereafter, the quaternary ammonium salt (M3), the styrene monomer (M1) and / or the (meth) acrylic acid alkyl ester monomer (M2) are mixed and copolymerized in the presence of a polymerization initiator.

  Examples of the paratoluenesulfonic acid alkyl ester include methyl paratoluenesulfonate, ethyl paratoluenesulfonate, and propyl paratoluenesulfonate. Of these, methyl paratoluenesulfonate is preferred because it can be easily quaternized. When the paratoluenesulfonic acid alkyl ester is reacted with the dialkylaminoalkyl (meth) acrylate, the amount of the paratoluenesulfonic acid alkyl ester used is 0.8 per mole of the dialkylaminoalkyl (meth) acrylate. It is preferable that it is 1 mol or more and 1.5 mol or less, and it is more preferable that it is 1.0 mol or more and 1.2 mol or less.

  Examples of the copolymerization method include solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization. Of these, melt polymerization is preferred. The reason why melt polymerization is preferable is, for example, that the control of the mass average molecular weight of the obtained copolymer is relatively easy and the reaction operation is easy. Examples of the solvent used in the solution polymerization include ketone solvents (more specifically, methyl ethyl ketone or methyl isobutyl ketone), alcohol solvents (more specifically, normal butanol or isobutanol), ester solvents, and the like. (More specifically, ethyl acetate or isobutyl acetate) or an aromatic hydrocarbon solvent (more specifically, toluene or xylene). Among these, a ketone solvent or an alcohol solvent is preferable from the viewpoint of the solubility of the copolymer.

  Examples of the polymerization initiator include peroxide-based initiators (more specifically, t-butylperoxy 2-ethylhexanoate, t-amylperoxy 2-ethylhexanoate, 1,1-di- (T-butylperoxy) cyclohexane, dibenzoyl peroxide, etc.) or azo initiators (more specifically, 2,2′-azobis (2-methylbutyronitrile) etc.) are used. The polymerization initiator is preferably 0.5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the total mass of the monomers.

  In the cationic copolymer (A), a styrene monomer (M1) unit, a (meth) acrylic acid alkyl ester monomer (M2), and a (meth) acrylic acid dialkylaminoalkyl quaternary ammonium salt (M3). When the total mass of the unit is 100 parts by mass, the content of the quaternary ammonium salt (M3) unit of dialkylaminoalkyl (meth) acrylate is preferably 0.5 parts by mass or more and 35 parts by mass or less. It is more preferable that the amount is not less than 30 parts by mass. If the content of the quaternary ammonium salt (M3) unit of (meth) acrylic acid dialkylaminoalkyl is 0.5 parts by mass or more, sufficient chargeability of the toner can be secured, and if it is 35 parts by mass or less, the result is The compatibility with the resin is improved, and the moisture resistance of the toner is also improved.

  The cationic copolymer (A) preferably has a mass average molecular weight of 1,500 or more and 100,000 or less, and more preferably 3,000 or more and 50,000 or less. When the weight average molecular weight of the cationic copolymer (A) is in such a range, the chargeability is hardly lowered even in a high humidity environment, and the toner adheres and remains on the surface of the fixing roll during fixing. Offset is unlikely to occur. In addition, the compatibility with the binder resin and the dispersibility when used as a toner are good, and even when the toner is used together with a carrier, the spent state in which the toner particles are crushed is difficult to proceed.

  The styrene resin (B) is a homopolymer of a styrene monomer. As the styrene monomer, the same styrene monomer (M1) that forms the cationic copolymer (A) is used. The mass average molecular weight of the styrene resin (B) is preferably 1,000 to 10,000, and more preferably 2,000 or more and 8,000 or less. If the mass average molecular weight of the styrene resin (B) is 1,000 or more, the styrene resin (B) can be easily produced, and if it is 10,000 or less, cold offset of the toner hardly occurs.

  As a method of melt-mixing the cationic copolymer (A) and the styrene resin (B) (hereinafter, this method may be referred to as a melt-mixing method), the cationic copolymer (A) and Examples thereof include a method of thermally kneading the styrene resin (B). Examples of the heat kneader include a plast mill, a heating roll, a kneader, and an extruder. The heating temperature during melt mixing is preferably 90 ° C. or higher and 170 ° C. or lower. If heating temperature is 90 degreeC or more, it will be easy to melt-mix a cationic copolymer (A) and a styrene resin (B) fully. If heating temperature is 170 degrees C or less, a cationic copolymer (A) or a styrene resin (B) will not deteriorate easily.

  More specifically, the method of dissolving and mixing the cationic copolymer (A) and the styrene resin (B) (hereinafter, this method may be referred to as a dissolution and mixing method) In this method, the solvent is removed after the coalescence (A) and the styrene resin (B) are dissolved in the solvent. Examples of such a solvent include methyl ethyl ketone, methyl isobutyl ketone, normal butanol, isobutanol, ethyl acetate, isobutyl acetate, toluene or xylene. At the time of dissolution, it is preferable to heat to 80 ° C. or higher and 140 ° C. or lower in order to promote dissolution. When removing the solvent, it is preferable to reduce the pressure in order to promote the removal.

  In the cationic copolymer (A), the content of the styrene resin (B) is 10 parts by mass or more and 90 parts by mass with respect to 100 parts by mass of the total mass of the cationic copolymer (A) and the styrene resin (B). Part or less, more preferably 20 parts by weight or more and 80 parts by weight or less. When the styrene resin (B) is 10% by mass or more, it is easy to prevent a decrease in chargeability after a long time, and when it is 90% by mass or less, sufficient chargeability is easily secured.

  The charge control agent may contain a known quaternary ammonium salt, a nigrosine compound, or the like, if necessary.

The volume resistivity of the charge control agent is preferably 4 × 10 ¹⁰ Ω · cm or more and 40 × 10 ¹⁰ Ω · cm or less. If the volume resistivity of the charge control agent is 4 × 10 ¹⁰ Ω · cm or more, sufficient chargeability is easily exerted, and if it is 40 × 10 ¹⁰ Ω · cm or less, the chargeability is unlikely to be excessive. The volume resistivity is a value measured by the following method. The powder of the charge control agent is pressure-molded into a cylindrical pellet having a diameter of 20 mm and a thickness of 3 mm. Next, using this pellet as a measurement sample, conductance G (1 / Ω) is measured at a measurement frequency of 1 kHz. From this conductance G, the volume resistivity ρ (Ω · cm) is obtained by using Equation (III).
ρ = (1 / G) × (S / L) (III)
In formula (III), S represents the cross-sectional area (cm ² ) of the pellet, and L represents the length (cm) of the pellet.

  The use amount of the positively chargeable charge control agent is preferably 0.5 parts by mass or more and 20.0 parts by mass or less, and 1.0 part by mass or more and 15.0 parts by mass when the total amount of toner is 100 parts by mass. It is more preferable that the amount is not more than part by mass.

<1-4. Internal additive>
Examples of the toner internal additive include a release agent. Hereinafter, the release agent will be described. The toner may contain a release agent. The release agent is used, for example, for the purpose of improving the fixing property or offset resistance of the toner. In order to increase the anionicity of the toner core, it is preferable to produce the toner core using an anionic wax. In order to improve the fixing property or offset resistance of the toner, the amount of the release agent used is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferably, it is 20 parts by mass or less.

  As the release agent, for example, wax is preferable. Examples of the wax include ester wax, polyethylene wax, polypropylene wax, fluororesin wax, Fischer-Tropsch wax, paraffin wax, and montan wax. Examples of the ester wax include synthetic ester wax or natural ester wax (specifically, carnauba wax or rice wax). These release agents can be used in combination of two or more. Of these release agents, ester waxes are more preferred, and synthetic ester waxes are even more preferred.

  The method for producing the synthetic ester wax is not particularly limited as long as it is a chemical synthesis method. For example, a synthetic ester wax can be synthesized using a known method such as a reaction between an alcohol and a carboxylic acid in the presence of an acid catalyst, or a reaction between a carboxylic acid halide and an alcohol. In addition, the raw material of synthetic ester wax may be derived from natural products such as long chain fatty acids produced from natural fats and oils. Moreover, as a synthetic ester wax, you may use what is marketed as a synthetic product.

  In order to improve the low-temperature fixability of the toner and suppress the occurrence of high-temperature offset, the release agent preferably has a melting point of 50 ° C. or higher and 100 ° C. or lower. The melting point of the release agent can be measured in the same manner as the melting point of the crystalline polyester resin described above.

<2. Toner Production Method>
Next, a toner manufacturing method will be described. The method for producing the toner is not particularly limited, but a preferred method for producing the toner according to the present embodiment will be described. The toner manufacturing method includes, for example, a preparation step and a toner particle preparation step.

<2-1. Preparation process>
As already described above, in the preparation step, for example, a binder resin is prepared. A crystalline polyester resin and an amorphous polyester resin are prepared and prepared as a binder resin.

  Specific examples of the preparation of the crystalline polyester resin are described below. Alcohol and carboxylic acid are mixed at a predetermined ratio to obtain a monomer mixture. Next, while stirring the monomer mixture, the temperature is raised to 190 ° C. or higher and 250 ° C. or lower in a nitrogen atmosphere. A crystalline polyester resin can be obtained by maintaining the elevated temperature and allowing the monomer to undergo a polymerization reaction.

  Specific examples of the preparation of the amorphous polyester resin are described below. Alcohol and carboxylic acid are mixed at a predetermined ratio to obtain a monomer mixture. Next, while stirring the monomer mixture, the temperature is raised to 180 ° C. or higher and 220 ° C. or lower in a nitrogen atmosphere. An amorphous polyester resin can be obtained by maintaining the temperature at a raised temperature and allowing the monomer to undergo a polymerization reaction.

<2-2. Toner particle preparation process>
The toner particle preparation step is a step of preparing toner particles containing a binder resin, magnetic powder, and a charge control agent. The toner particle preparation step is not particularly limited as long as the crystalline polyester resin, the magnetic powder, and the charge control agent can be satisfactorily dispersed in the amorphous polyester resin, and a known method can be appropriately employed. Known methods include, for example, a melt-kneading method or an agglomeration method. In the toner particle preparation step, an arbitrary component (for example, a release agent) may be dispersed in the toner particles.

  The toner particle preparation step by the melt kneading method includes, for example, a mixing step and a kneading step. The mixing step is a step of obtaining a mixture by mixing a binder resin, magnetic powder, a charge control agent, and an optional component (for example, a release agent). A kneading | mixing process is a process of melt-kneading the obtained mixture and obtaining a kneaded material. The toner particle preparation step by the melt kneading method may further include a pulverization step and a classification step. The pulverization step is a step of pulverizing the obtained kneaded product. In the classification step, the pulverized kneaded product is classified to obtain toner particles having a desired particle size. From the viewpoint of toner particle productivity or colorant dispersibility, a melt-kneading method is preferred.

  The toner particle production process by the aggregation method includes, for example, an aggregation process and a coalescence process. The aggregating step is a step of aggregating fine particles containing components constituting the toner particles in an aqueous medium to form aggregated particles. The coalescence process is a process in which the components contained in the aggregated particles are coalesced in an aqueous medium to form toner particles. When the aggregation method is used as a method for preparing toner particles, it is easy to obtain toner particles having a uniform shape and a uniform particle diameter.

  The toner particle preparation step may further include a washing step and a drying step. The cleaning step is a step of cleaning the toner particles using an aqueous medium. As a suitable cleaning method, toner particles are dispersed in an aqueous medium to prepare an aqueous dispersion containing toner particles. From the prepared aqueous dispersion, toner particles are recovered as a wet cake by solid-liquid separation, and the resulting wet cake is washed with an aqueous medium or the toner particles in the aqueous dispersion containing the toner particles are precipitated. And a method of replacing the supernatant liquid with an aqueous medium and redispersing the toner particles in the aqueous medium after the replacement.

  The drying process is a process of drying the toner particles. A suitable method for drying the toner particles includes a method using a dryer (for example, a spray dryer, a fluidized bed dryer, a vacuum freeze dryer, or a vacuum dryer). Among these methods, a method using a spray dryer is preferable in order to suppress aggregation of toner particles during drying. In the case of using a spray dryer, the external additive can be attached to the surface of the toner particles by spraying a dispersion of the external additive such as silica together with the dispersion of the toner particles.

  The toner according to this embodiment has been described above. The toner according to the exemplary embodiment is excellent in low-temperature fixability and charging stability. For this reason, the toner according to the exemplary embodiment can be suitably used in various image forming apparatuses.

  Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the scope of the examples.

[1. Preparation of crystalline polyester resin]
[1-1. Crystalline polyester resin C1]
A four-necked flask was used as a reaction vessel. This four-necked flask is a reaction vessel having a capacity of 2 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. 1,10-decanediol as an alcohol monomer and sebacic acid as an acid monomer in an amount (molar ratio) shown in Table 1 were charged into a reaction vessel. Further, tin dioctylate as a catalyst was charged into a 1 part by mass reaction vessel with respect to 100 parts by mass of the total amount of monomers. The reaction vessel was placed on a mantle heater, and nitrogen gas was introduced into the reaction vessel through a nitrogen introduction tube to make the inside of the reaction vessel a nitrogen atmosphere. Next, the internal temperature of the reaction vessel was raised to 140 ° C. while stirring the monomer mixture under normal pressure, and the polymerization reaction was performed for 6 hours while continuing stirring at the same temperature to distill off water. Subsequently, it was made to react, raising the internal temperature in reaction container to 200 degreeC with the temperature increase rate of 10 degreeC / hour. Next, the reaction was carried out for 2 hours after the internal temperature in the reaction vessel reached 200 ° C. Thereafter, the inside of the reaction vessel was decompressed to 5 kPa or less and reacted at 200 ° C. for 3 hours. The contents in the reaction vessel were taken out into a vat and cooled to room temperature (25 ° C.) to obtain a polyester resin C1. Table 1 summarizes the raw materials used in the preparation of the crystalline polyester resin and the composition ratios. Table 2 summarizes various physical properties of the crystalline polyester resin.

[1-2. Crystalline polyester resin C2 to C9]
Crystalline polyester resins C2 to C9 were prepared in the same manner as the method for preparing crystalline polyester resin C1, except that the types of alcohol monomers and acid monomers listed in Table 1 and the blending composition were changed.

[2. Preparation of amorphous polyester resin]
[2-1. Amorphous polyester resin A1]
A four-necked flask was used as a reaction vessel. This four-necked flask is a reaction vessel with a capacity of 2 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. , BPA-EO) and bisphenol A-propylene oxide 2-mole adduct (hereinafter sometimes referred to as BPA-PO), and terephthalic acid, alkenyl succinic acid and trimellitic acid as acid monomers. The reaction vessel was charged. Further, dibutyltin as a catalyst was charged into a 1.5 parts by mass reaction vessel with respect to 100 parts by mass of the total amount of monomers. The reaction vessel was placed on a mantle heater, and nitrogen gas was introduced into the reaction vessel through a nitrogen introduction tube to make the inside of the reaction vessel a nitrogen atmosphere. Next, the internal temperature of the reaction vessel was quickly raised to 180 ° C. while stirring the monomer mixture under normal pressure. Next, the internal temperature of the reaction vessel was increased from 180 ° C. to 210 ° C. at a rate of 10 ° C./hour, and a polymerization reaction was carried out while distilling off water. Next, after the internal temperature in the reaction vessel reached 210 ° C., the pressure in the reaction vessel was reduced to 5 kPa. The polycondensation reaction was performed at a temperature of 210 ° C. and a pressure of 5 kPa in the reaction vessel. As a result, an amorphous polyester resin A1 was obtained. Table 3 shows the raw materials used for the preparation of the amorphous polyester resin and the composition ratios. Table 4 shows various physical properties of the amorphous polyester resin.

[2-2. Amorphous polyester resins A2 to A5]
Amorphous polyester resins A2 to A5 were prepared in the same manner as the method for preparing amorphous polyester resin A1, except that the types of alcohol monomers and acid monomers listed in Table 3 and the blending composition were changed.

[3. Preparation of charge control agent]
[3-1. Charge control agent Q1]
[3-1-1. Preparation of cationic copolymer (A-1)]
A four-necked flask was used as a reaction vessel. This four-necked flask is a reaction vessel having a capacity of 2 L equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. As a solvent, 180 g of isobutanol was charged into the reaction vessel. Further, 18 g of diethylaminoethyl methacrylate and 18 g of methyl paratoluenesulfonate were charged into the reaction vessel. The reaction vessel was placed on a mantle heater, nitrogen gas was introduced into the reaction vessel through a nitrogen introduction tube, the inside of the reaction vessel was made into a nitrogen atmosphere, and the temperature in the reaction vessel was raised to 80 ° C. The temperature in the reaction vessel was maintained at 80 ° C., and the quaternization reaction was performed for 1 hour while stirring the mixture in the reaction vessel. Next, while introducing nitrogen into the reaction vessel, 210 g of styrene, 72 g of butyl acrylate, and 12 g of t-butylperoxy 2-ethylhexanoate (manufactured by Arkema Yoshitomi Co., Ltd.) as a peroxide initiator were added to the reaction vessel. Added to. The temperature in the reaction vessel was raised to 95 ° C., and the content in the reaction vessel was stirred for 3 hours while maintaining 95 ° C. (polymerization temperature). As a result, a polymer solution was obtained. The obtained polymer solution was heated and dried under conditions of a temperature of 140 ° C. and a reduced pressure (10 kPa or less) in the reaction vessel. As a result, a resin from which the solvent was removed was obtained. The resin was crushed to obtain a cationic copolymer (A-1). A quaternary ammonium salt (M3) of a styrene monomer (M1), a (meth) acrylic acid ester monomer (M2), and a (meth) acrylic acid dialkylaminoalkyl monomer in the obtained cationic copolymer. ) Was (M1 + M2): M3 = 88.7: 11.3.

[3-1-2. Preparation of styrene resin (B-1)]
An autoclave was used as the reaction vessel. This reaction vessel is a 1 L capacity reaction vessel equipped with a nitrogen introduction tube, a stirrer and a thermometer. In a reaction vessel, 0.2 g of partially saponified polyvinyl alcohol (“GOHSENOL (registered trademark) GH-20” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was charged. Furthermore, a mixture containing 100 g of a styrene monomer and 15 g of a ring oxide benzoyl peroxide (“NIPER BW” manufactured by NOF Corporation) was charged into the reaction vessel. While stirring the contents in the reaction vessel, the temperature in the reaction vessel was raised to 130 ° C., and suspension polymerization was carried out for 1 hour. After suspension polymerization, the contents in the reaction vessel were filtered, washed, dehydrated and dried. As a result, a styrene resin (B-1) was obtained. The obtained styrene resin (B-1) had a mass average molecular weight of 8,000.

[3-1-3. Preparation of charge control agent Q1]
A flask was used as a reaction vessel. This flask is a 5 L reaction vessel equipped with a stirrer and a thermometer. 300 g of cationic copolymer (A-1), 700 g of styrene resin (B-1) (“SX-100” manufactured by Yasuhara Chemical Co., Ltd., weight average molecular weight 2,500), and 1000 g of methyl ethyl ketone as a solvent in a reaction vessel. Prepared. The reaction vessel was placed on a mantle heater, and the temperature of the reaction vessel was raised while stirring. When the solvent in the reaction vessel began to reflux, the temperature in the reaction vessel was further raised while discharging the solvent from the reaction vessel. When the temperature in the reaction vessel reached 140 ° C., the pressure in the reaction vessel was reduced until the pressure in the reaction vessel became 10 KPa or less, the solvent was removed, and a molten resin component was obtained. The obtained resin component was taken out, the resin component was cooled and further pulverized. As a result, a charge control agent Q1 was obtained. Table 5 shows the raw materials used for the preparation of the charge control agent and the blending composition ratio thereof. Table 6 shows various physical properties of the charge control agent.

[3-2. Charge control agent Q2-4]
The charge control agents Q2 to Q4 consist of an addition amount of styrene monomer of 100 g, an addition amount of cationic copolymer of 300 g, and an addition amount of styrene resin of 700 g, respectively. The charge control agents Q2 to Q4 were adjusted in the same manner as the preparation of the charge control agent Q1, except that the addition amount of styrene resin and the addition amount of styrene resin were changed.

[4. Preparation of toner]
[4-1. Toner 1]
5% by mass of crystalline polyester resin C1, 42% by mass of non-crystalline polyester resin A1, 5% by mass of charge control agent Q1, 45% by mass of magnetic powder (“Magnetite” manufactured by Toda Kogyo Co., Ltd.) and wax (day) “Nissan Electol (registered trademark) WEP-3” manufactured by Oil Co., Ltd.) was mixed at a blending ratio of 3 mass% using an FM mixer (“FM-20 Model” manufactured by Nippon Coke Industries, Ltd.). Next, the mixture was kneaded at a temperature of 100 ° C. using a biaxial kneader (“PCM-30” manufactured by Ikekai Tekko Co., Ltd.). The obtained kneaded material was primarily pulverized using a coarse pulverizer (“Rohtoplex (registered trademark)” manufactured by Hosokawa Micron Corporation). Next, the obtained primary pulverized product was subjected to secondary pulverization using a fine pulverizer ("T-250" manufactured by Freund Turbo Inc.) at a rotational speed of 9,500 rpm. The obtained secondary pulverized product was classified using an elbow jet classifier utilizing the Counder effect to obtain toner base particles. Using an FM mixer (“FM-20 type” manufactured by Nippon Coke Co., Ltd.), positively charged hydrophobic silica (primary particle diameter of 20 nm) and hydrophobic titanium oxide (primary particle diameter of 300 nm) were added to the obtained toner base particles. Addition and surface-treated toner 1 was obtained. The hydrophobic silica and the hydrophobic titanium oxide were added to the toner base particles so that the content with respect to the toner 1 was 1% by mass, respectively. The number average particle diameter of the magnetite used for preparing the toner was 0.25 μm. The magnetic properties of the magnetite used in the toner preparation were as follows: the coercive force when 796 kA / m was applied was 4.5 kA / m, the saturation magnetization was 82 Am ² / kg, and the residual magnetization was 4.5 Am ² / kg. It was. The magnetic properties of the magnetite were measured using a vibrating sample magnetometer (“VSM-P7-15” manufactured by Toei Kogyo Co., Ltd.).

[4-2. Toner 2 to 9 and Toner B1 to B6]
Toners 2 to 9 and toners B1 to B6 are the non-crystalline polyester resin A1, the crystalline polyester resin C1, and the charge control agent Q1, respectively. The non-crystalline polyester resin, the crystalline polyester resin, and the charge control agent described in Table 7 are used. Toners 2 to 9 and toners B1 to B6 were prepared in the same manner as the preparation method of the toner 1 except that

[5. Measuring method]
[5-1. Dispersion diameter of crystalline polyester resin and charge control agent]
First, an evaluation sample was prepared. A sample (toner) and a resin (room temperature curable epoxy resin) were mixed to prepare a mixture in which the toner was sufficiently dispersed. The resulting mixture was allowed to cure for 2 days at a temperature of 40 ° C. with the toner sufficiently dispersed. Thus, a cured product in which the sample was embedded in the resin was obtained. The cured product was dyed with osmium tetroxide. Using a micronome (“EMUC6” manufactured by Leica Co., Ltd.), a flaky sample was prepared from the dyed cured product. The obtained flaky sample was used as an evaluation sample. Using a transmission electron microscope (“JSM-6700F” manufactured by JEOL Ltd.), the evaluation sample was photographed at a magnification of 10,000 to obtain an image of a cross section of the toner particles. The longest diameter of the crystalline polyester resin in the obtained image was measured. An average value was obtained from the plurality of longest diameters obtained (number of measurements n = 100). The average value obtained was taken as the dispersion diameter of the crystalline polyester resin. Similarly, a dispersion diameter of the charge control agent was obtained.

[5-2. Measurement of Temperature Tc of Crystalline Polyester Resin, Temperature Ta of Amorphous Polyester Resin, and Temperature Tq of Charge Control Agent]
A crystalline polyester resin (1.8 g) was pressure-molded at a pressure of 10 MPa to prepare a cylindrical molded sample (volume: 1 cm ³ ) having a diameter of 1 cm. The produced molded sample was used as a measurement sample. A molding sample was set in a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation). The measurement sample was melted and flowed out under the following conditions. Thus, the melt viscosity at a plurality of temperatures was measured. A semi-log plot (horizontal axis: temperature, vertical axis: logarithm of melt viscosity) was created from the measured melt viscosity. The measurement was performed at a temperature of 23 ° C. and a humidity of 50% RH.
Plunger load: 20 kg / cm ²
Die pore diameter: 1mm
Die length: 1mm
Temperature increase rate 4.0 ° C / min Preheating temperature: 40 ° C
Preheating time: 300 seconds (5 minutes)
Based on the obtained log-log plot, the temperature Tc of the crystalline polyester resin was determined based on the above-described reading method. Similarly, the temperature Ta of the amorphous polyester resin and the temperature Tq of the charge control agent were determined.

[5-3. Measurement of mass average molecular weight of crystalline polyester resin and non-crystalline polyester resin]
The mass average molecular weight (Mw) was measured using gel filtration chromatography (GPC) (“HLC-8220GPC” manufactured by Tosoh Corporation). A sample (crystalline polyester resin) was put in tetrahydrofuran (THF), allowed to stand for about 1 hour and dissolved. Then, the sample pretreatment filter (Kurabo Chromatodisc 25N non-aqueous pore size 0.45 μm) was passed through. The obtained THF-soluble component was used as a sample for GPC measurement. The sample concentration was adjusted so that the resin component was 3 mg / mL. The column was stabilized in a heat chamber, and THF was flowed at a flow rate of 1 mL / min as a developing solvent. About 50 to 200 μL of the obtained measurement sample was injected into such a column and measured. An RI (refractive index) detector was used as the detector. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse styrene resin standard samples and the count number (retention time). Examples of standard styrene resin samples for preparing a calibration curve include molecular weights of 3.84 × 10 ⁶ , 1.09 × 10 ⁶ , 3.55 × 10 ⁵ , 1.02 × 10 ⁵ , and 4 manufactured by Tosoh Corporation. Standard styrene resin samples of 39 × 10 ⁴ , 9.10 × 10 ³ and 2.98 × 10 ³ were used. As the column, in order to accurately measure the molecular weight region of 10 ^{3 to} 2 × 10 ^6, a plurality of commercially available styrene resin gel columns were used in combination.

[6. Evaluation method]
[6-1. Measurement of low temperature fixing temperature of toner (evaluation of low temperature fixing property)]
A printer (“FS-1370DN” manufactured by Kyocera Document Solutions Inc.) was used as an evaluation machine. This evaluation machine is a printer in which the fixing device is remodeled into a Roller-Roller type heat and pressure type. Using an evaluation machine, on a 90 g / m ² paper (A4 size evaluation paper) under the conditions of a linear speed of 200 mm / second, a nip passage time of 40 milliseconds, a nip width of 8 mm, and a toner loading of 1.0 mg / cm ^2. A solid image having a size of 25 mm × 25 mm and a printing rate of 100% was formed. Subsequently, the paper on which the image was formed was passed through a fixing device to form an image. The obtained image after fixing was folded and reciprocated 5 times with a 1 kg weight, and it was confirmed whether the width of the crease peeled was less than 1 mm. An image in which the width of the crease peeled off was less than 1 mm was evaluated as an image in which no cold offset occurred. The setting range of the fixing temperature was 100 ° C. or higher and 200 ° C. or lower. Specifically, the fixing temperature of the fixing device is gradually increased from 100 ° C., and the lowest temperature (minimum fixing temperature) at which the toner (solid image) can be fixed on the paper without causing a cold offset is determined. From the obtained minimum fixing temperature, the low-temperature fixing property of the toner was evaluated based on the following criteria.
○ (Good): The minimum fixing temperature was 145 ° C. or lower.
X (Poor): The minimum fixing temperature was higher than 145 ° C.

[6-2. Measurement of aggregation degree of toner (evaluation of heat-resistant storage stability)]
3 g of a sample (toner) was weighed into a 20 mL capacity plastic container and allowed to stand in a thermostatic chamber set at 60 ° C. for 3 hours to obtain a sample for heat resistant storage stability evaluation. Then, the sample for heat resistant storage stability evaluation was sieved using a 200 mesh (mesh opening 75 μm) sieve under the conditions of rheostat scale 2 and time 30 seconds according to the manual of a powder tester (manufactured by Hosokawa Micron Corporation). . After sieving, the mass of the sample remaining on the sieve was measured. From the mass of the sample before sieving and the mass of the sample remaining on the sieving after sieving, the degree of aggregation (% by mass) of the toner was calculated according to the following formula (IV).
Aggregation degree (mass%) = (mass of sample remaining on sieve / mass of specimen before sieving) × 100 (IV)
From the calculated degree of aggregation, the heat resistant storage stability of the toner was evaluated according to the following criteria.
○ (Good): The degree of aggregation was 10% by mass or less.
X (Poor): The degree of aggregation was more than 10% by mass.

[6-3. Measurement of change rate of charge decay constant of toner (Evaluation of charging stability)]
The charge decay was measured using an electrostatic charge diffusion method defined in Japanese Industrial Standard JIS 61340-2-1. The charge decay was measured using an electrostatic diffusivity measuring device (“NS-D100 type” manufactured by Nano Seeds Co., Ltd.). The measurement apparatus and the sample (toner) were left in normal temperature and normal humidity (NN, temperature 23 ° C., humidity 50% RH) for 12 hours. The obtained sample was used as a sample for evaluation. Next, the evaluation sample was set in a measuring apparatus. The sample for evaluation was charged with 7 KV, and the charge retention state after 2 seconds was measured. The measurement was performed in a normal temperature and humidity environment. From the measurement of the charge retention state on the toner surface, the charge decay constant α was determined using the following formula (V).
V = V ₀ exp (−α√t) (V)
In Formula (V), V ₀ represents the initial surface potential (V) of the toner, V represents the surface potential (V) of the toner, α represents a charge decay constant, and t represents time (seconds). The obtained charge decay constant was defined as α (NN). The measurement method and calculation of α (NN), except that the sample preparation environment and measurement environment were changed from a normal temperature and normal humidity (NN) environment to a high temperature and high humidity (HH, temperature 32.5 ° C, humidity 80% RH) environment. In the same manner as the method, the charge decay constant α in a high temperature and high humidity environment was determined. The obtained charge decay constant was defined as α (HH). From the obtained α (NN) and α (HH), the rate of change of the charge decay constant was determined using the following formula (VI).
Rate of change (%) = (α (HH) / α (NN)) × 100 (VI)
From the obtained rate of change, the charging stability of the toner was evaluated according to the following criteria.
○ (Good): The rate of change was 20% or less.
X (Poor): The rate of change was more than 20%.

  Table 10 shows the evaluation results of the low-temperature fixability, heat-resistant storage stability and charging stability of each sample (toners 1 to 9 of Examples 1 to 9 and toners B1 to B6 of Comparative Examples 1 to 6). In Table 9, “not confirmed” indicates that the domain was not observed.

  As shown in Table 8, in toners 1 to 9, SPa-SPq is +0.54 or more, SPc-SPq is +0.57 or more, and | SPc-SPa | is 0.20 or more and 0.70 or less. there were. As shown in Table 10, with toners 1 to 9, the evaluation results of low-temperature fixability, heat-resistant storage stability, and charging stability were all “good”.

  As shown in Tables 8 and 10, in toners B1 and B5, | SPc-SPa | was less than 0.20, and the evaluation result of heat resistant storage stability was x (poor). For toners B2, B3, and B6, | SPc−SPa | was greater than 0.70, and the evaluation result of low-temperature fixability was x (poor). In toners B4 and B5, SPc-SPq and SPc-SPq were both less than +0.50, and the evaluation result of charging stability was x (poor).

  It was shown that the toners 1 to 9 have low-temperature fixability, heat-resistant storage stability, and charging stability as compared with the toners B1 to B6.

  The magnetic toner according to the present invention can be used for forming an image in an image forming apparatus (for example, a copying machine or a printer).

Claims (3)

A magnetic toner containing a plurality of toner particles,
The toner particles include a binder resin, magnetic powder, and a charge control agent,
The charge control agent is a resin having a chargeable functional group,
The binder resin includes an amorphous polyester resin and a crystalline polyester resin,
The content of the magnetic powder is 40 parts by mass or more with respect to 100 parts by mass of the binder resin,
The solubility parameter SPa of the non-crystalline polyester resin, the solubility parameter SPc of the crystalline polyester resin, and the solubility parameter SPq of the charge control agent satisfy Equations (1), (2), and (3). And
At a melt viscosity of 10,000 Pa · s measured with a Koka flow tester, the temperature Ta of the amorphous polyester resin, the temperature Tc of the crystalline polyester resin, and the temperature Tq of the charge control agent A magnetic toner satisfying (4) and formula (5) .
SPa-SPq ≧ + 0.50 (1)
SPc−SPq ≧ + 0.50 (2)
0.20 ≦ | SPa−SPc | ≦ 0.70 (3)
Tc <Tq <Ta (4)
Ta-Tc <+ 40 ° C. (5) A magnetic toner containing a plurality of toner particles,
The toner particles include a binder resin, magnetic powder, and a charge control agent,
The charge control agent is a resin having a chargeable functional group,
The binder resin includes an amorphous polyester resin and a crystalline polyester resin,
The content of the magnetic powder is 40 parts by mass or more with respect to 100 parts by mass of the binder resin,
The solubility parameter SPa of the non-crystalline polyester resin, the solubility parameter SPc of the crystalline polyester resin, and the solubility parameter SPq of the charge control agent satisfy Equations (1), (2), and (3). ,
Der dispersion diameter is 0.10μm or less of the crystalline polyester resin obtained by cross-sectional observation of the toner particles with a transmission electron microscope is,
A magnetic toner in which a dispersion diameter of the charge control agent obtained by observing a cross section of the toner particles with a transmission electron microscope is 0.10 μm or more .
SPa-SPq ≧ + 0.50 (1)
SPc−SPq ≧ + 0.50 (2)
0.20 ≦ | SPa−SPc | ≦ 0.70 (3) A magnetic toner containing a plurality of toner particles,
The toner particles include a binder resin, magnetic powder, and a charge control agent,
The charge control agent is a resin having a chargeable functional group,
The binder resin includes an amorphous polyester resin and a crystalline polyester resin,
The content of the magnetic powder is 40 parts by mass or more with respect to 100 parts by mass of the binder resin,
The solubility parameter SPa of the non-crystalline polyester resin, the solubility parameter SPc of the crystalline polyester resin, and the solubility parameter SPq of the charge control agent satisfy Equations (1), (2), and (3). ,
The binder resin does not have a quaternary ammonium group,
The charge controlling agent having a quaternary ammonium group as the functional group of the chargeability, magnetic toner.
SPa-SPq ≧ + 0.50 (1)
SPc−SPq ≧ + 0.50 (2)
0.20 ≦ | SPa−SPc | ≦ 0.70 (3)