Toner, developer, toner storage unit, image forming apparatus, and image forming method

Abstract

To provide a toner that achieves both low temperature fixability and heat-resistant storage properties and has good cleaning properties.SOLUTION: A toner has a toner base particles that contains at least a binder resin, resin fine particles that cover the toner base particle, and zinc stearate particles as an external additive. The resin fine particles cover the toner base particle at a coverage of 30% or more and 70% or less. The zinc stearate particles have a volume average particle diameter of 3 μm or more and 20 μm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to toner, developer, toner storage unit, image forming apparatus, and image forming method. [Background technology]

[0002] In recent years, toners have been required to have small particle sizes and high-temperature offset resistance for high-quality output images, low-temperature fixing properties for energy saving, and heat-resistant storage properties to withstand high temperatures and humidity during storage and transportation after manufacturing. In particular, since power consumption during fixing accounts for a large portion of the power consumption in the image formation process, improving low-temperature fixing properties is extremely important.

[0003] To improve the low-temperature fixing properties of toner, it is necessary to use materials with a low melting point in the toner. However, toner manufactured using materials with a low melting point has the problem of poor heat resistance during storage. Therefore, there is a trade-off between low-temperature fixing properties and heat resistance during storage.

[0004] Therefore, in order to achieve both low-temperature fixability and heat-resistant storage, a method for producing composite resin particles has been proposed that includes a removal step to remove some or all of the resin from the resin microparticles after forming composite resin particles in which resin microparticles containing two types of resin as constituent components within the same particle are attached to the surface of toner matrix particles (see, for example, Patent Documents 1 to 3). Furthermore, it has been proposed to place resin microparticles on the surface of toner matrix particles (see, for example, Patent Document 4). [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a toner that achieves both low-temperature fixability and heat-resistant storage, while also possessing good cleaning properties. [Means for solving the problem]

[0006] The toner of the present invention, as a means for solving the above problems, A toner comprising toner matrix particles containing at least a binder resin, resin fine particles coating the toner matrix particles, and zinc stearate particles as an external additive, The coating rate of the toner matrix particles by the resin fine particles is 30% or more and 70% or less. The volume-average particle diameter of the zinc stearate particles is 3 μm or more and 20 μm or less. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a toner that achieves both low-temperature fixability and heat-resistant storage, as well as good cleaning properties. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an example of the image forming apparatus of the present invention. [Figure 2] Figure 2 is a schematic diagram showing another example of the image forming apparatus of the present invention. [Figure 3] Figure 3 is a partially enlarged view of the image forming apparatus shown in Figure 2. [Figure 4] Figure 4 is a schematic diagram showing an example of a process cartridge. [Modes for carrying out the invention]

[0009] (toner) The toner of the present invention comprises toner matrix particles, resin fine particles coating the toner matrix particles, and zinc stearate particles as an external additive, and further comprises other components as necessary.

[0010] The toners described in Patent Documents 1 to 4 aim to achieve both low-temperature fixing property and heat-resistant storage property, but there is a problem that good cleaning property for a photoreceptor (electrostatic latent image carrier) cannot be obtained. For cleaning the photoreceptor, there are a blade method using a cleaning blade and a roller method using a roller. However, there is a problem that friction occurs between the photoreceptor and the cleaning blade or the roller, and image defects due to poor cleaning are likely to occur. In order to prevent the poor cleaning, by containing zinc stearate particles in addition to silica as an external additive, the surface of the photoreceptor can be coated and the friction between the photoreceptor and the cleaning blade or the like can be reduced. However, since the zinc stearate particles are likely to be buried in the surface of the toner mother particles, they are less likely to be released from the toner mother particles in the system (image forming apparatus), and there is a problem that a sufficient coating effect cannot be obtained.

[0011] Therefore, as a result of intensive studies by the present inventors, it has been found that by coating the toner mother particles with the resin fine particles so that the coating rate is 30% or more and 70% or less, it is possible to suppress the zinc stearate particles from being buried in the toner mother particles. Further, by coating the toner mother particles with the resin fine particles, the toner mother particles can be hardened while ensuring the low-temperature fixing property of the toner, so that both the low-temperature fixing property and the heat-resistant storage property can be achieved. In addition, when the volume average particle diameter of the zinc stearate particles is 3 μm or more and 20 μm or less, it is possible to prevent the zinc stearate particles from being buried in the toner mother particles and to prevent the zinc stearate particles from being captured by the cleaning blade or the like, and thus it has been found that excellent cleaning property can be obtained.

[0012] The toner of the present invention has a coating rate of the toner base particles by the resin fine particles of 30% or more and 70% or less, preferably 40% or more and 60% or less. When the coating rate is 30% or more, the heat-resistant storage stability of the toner is improved, and since the zinc stearate particles as an external additive can be suppressed from being buried in the toner base particles, excellent cleaning performance can be obtained. When the coating rate is 70% or less, the zinc stearate particles are likely to be externally added to the surface of the toner base particles, so excellent cleaning performance can be obtained, and since heat is easily transferred when the toner is fixed to the recording medium, excellent low-temperature fixing performance is achieved. Furthermore, when the coating rate is 30% or more and 70% or less, the zinc stearate particles as an external additive adhere moderately to the surface of the toner base particles, and a certain amount of the zinc stearate particles is released from the toner base during cleaning. As a result, the zinc stearate particles are deposited on the contact surface between the cleaning blade and the photoreceptor, and good cleaning performance can be obtained, and the occurrence of filming can be suppressed.

[0013] The method for measuring the coating rate is not particularly limited and can be appropriately selected according to the purpose. For example, the resin fine particles on the surface of the toner base particles are observed and photographed with a scanning electron microscope (SEM), and the area ratio of the resin fine particles to the area of the toner base particles is calculated using image processing software to measure it.

[0014] The specific method for measuring the coating rate will be described below. As a method for measuring the coating rate, after performing a release treatment of the external additive to remove the external additive as much as possible by ultrasonic waves, the resin fine particles covering the toner base particles are observed using a scanning electron microscope (SEM).

[0015] As the release treatment of the external additive, the external additive is released from the toner base particles according to the following [1] to [2] and [ultrasonic conditions]. [1] Mix 50 ml of a 5% by mass surfactant solution (product name: Neugen ET-165, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a dispersion solution with 3 g of toner in a 100 ml screw tube, gently move it up and down and left and right, and then stir with a ball mill for 30 minutes so that the toner is well absorbed into the dispersion solution. [2] Subsequently, ultrasonic energy is applied using an ultrasonic homogenizer (product name: homogenizer, model VCX750, CV33, manufactured by SONICS&MATERIALS Co., Ltd.) under the following [ultrasonic conditions].

[0016] [Ultrasound conditions] • Vibration time: 60 minutes continuous ·Amplitude: 40W ·Vibration start temperature: 23±1.5℃ ·Temperature during vibration: 23±1.5℃

[0017] [3](1) The dispersion is filtered by suction using filter paper (product name: Qualitative filter paper (No. 2, 110 mm), manufactured by Advantec Toyo Co., Ltd.), washed twice again with deionized water and filtered to remove the freed additives, and then the toner is dried. (2) Scanning electron microscope (SEM) images are taken of the toner obtained in (1) using a scanning electron microscope (SEM). When taking images, an SEM image is taken from a direction perpendicular to the direction of the image taken, and a total of 20 or more SEM images are taken. First, Si-containing additives and fillers are detected by observing the backscattered electron image. (3) The image from (1) is binarized using image processing software (ImageJ) to remove the external additive and filler.

[0018] Next, observe the secondary electron image at the same position as in (1). Since resin nanoparticles are not observed in the backscattered electron image but only in the secondary electron image, compare it with the image obtained in (3) and observe the nanoparticles present in the parts other than the remaining external additive and filler (the parts other than those excluded in (3)) as resin nanoparticles.

[0019] [Shooting conditions] • Scanning electron microscope: SU-8230 (manufactured by Hitachi High-Technologies Corporation) • Magnification: 35,000x • Image type: SE(L): Secondary electrons, BSE(backscattered electrons) • Acceleration voltage: 2.0kV ·Acceleration current: 1.0μA • Probe current: Normal • Focus mode: UHR WD: 8.0mm

[0020] The toner of the present invention has a volume-average particle diameter of zinc stearate particles as an external additive that is 3 μm or more and 20 μm or less, preferably 5 μm or more and 15 μm or less. When the volume-average particle diameter is 3 μm or more, the zinc stearate particles are prevented from becoming embedded in the toner matrix particles, so that the zinc stearate particles are released from the toner matrix particles, improving the coating effect on the photoreceptor and resulting in excellent cleaning performance. When the volume-average particle diameter is 20 μm or less, the zinc stearate particles are prevented from being captured by the cleaning blade, resulting in excellent cleaning performance.

[0021] There are no particular restrictions on the method for measuring the volume-average particle diameter of the zinc stearate particles, and a suitable method can be selected depending on the purpose. For example, the zinc stearate particles may be observed and photographed using a scanning electron microscope (SEM), and the longest length of randomly selected zinc stearate particles may be measured using the image analysis software ImageJ on the captured SEM images (number of particles measured: 100 to 200), and the volume-average particle diameter may be calculated.

[0022] <Resin fine particles> The resin fine particles coat the toner matrix particles. The toner matrix particles coated with the aforementioned resin microparticles have improved durability and excellent heat resistance for storage, and the zinc stearate particles are prevented from becoming embedded in the toner matrix particles. The resin fine particles preferably have a core resin (core portion) and a shell resin (outer shell portion) that covers at least a part of the surface of the core resin, and more preferably contain a vinyl-based unit consisting of the core resin and the shell resin.

[0023] <<Shell resin>> As the shell resin, a polymer obtained by homopolymerizing or copolymerizing vinyl monomers is preferred. Examples of the aforementioned vinyl monomers include (1) to (10) listed below.

[0024] (1) Vinyl hydrocarbons Examples of the vinyl hydrocarbons include (1-1) aliphatic vinyl hydrocarbons, (1-2) alicyclic vinyl hydrocarbons, and (1-3) aromatic vinyl hydrocarbons.

[0025] (1-1) Aliphatic vinyl hydrocarbons Examples of the aliphatic vinyl hydrocarbons include alkenes and alkadienes. Specific examples of the aforementioned alkenes include ethylene, propylene, and α-olefins. Specific examples of the aforementioned alkadienes include butadiene, isoprene, 1,4-pentadiene, 1,6-hexadiene, and 1,7-octadiene.

[0026] (1-2) Alicyclic vinyl hydrocarbons Examples of the alicyclic vinyl hydrocarbons include monocycloalkenes, dicycloalkenes, and dicycloalkadienes, with specific examples including (di)cyclopentadiene and terpenes.

[0027] (1-3) Aromatic vinyl hydrocarbons Examples of the aromatic vinyl hydrocarbon include styrene and hydrocarbyl derivatives of styrene (e.g., alkyl, cycloalkyl, aralkyl, alkenyl, etc.). Specific examples of hydrocarbyl-substituted styrenes include α-methylstyrene, 2,4-dimethylstyrene, and vinylnaphthalene.

[0028] (2) Carboxyl group-containing vinyl monomers and salts thereof Examples of the carboxyl group-containing vinyl monomers and their salts include unsaturated monocarboxylic acids (salts) having 3 to 30 carbon atoms, unsaturated dicarboxylic acids (salts), their anhydrides (salts), and their monoalkyl (1 to 24 carbon atoms) esters. Specific examples of the carboxyl group-containing vinyl monomers include (meth)acrylic acid, (anhydride) maleic acid, maleic acid monoalkyl esters, fumaric acid, fumaric acid monoalkyl esters, crotonic acid, itaconic acid, itaconic acid monoalkyl esters, itaconic acid glycol monoether, citraconic acid, citraconic acid monoalkyl esters, cinnamic acid, and other carboxyl group-containing vinyl monomers, as well as metal salts thereof.

[0029] In this invention, "(salt)" means an acid or a salt thereof. For example, "unsaturated monocarboxylic acid (salt) having 3 to 30 carbon atoms" means an unsaturated monocarboxylic acid or a salt thereof. Examples of the aforementioned salts include alkali metal salts (sodium salts, potassium salts, etc.), alkaline earth metal salts (calcium salts, magnesium salts, etc.), ammonium salts, amine salts, and quaternary ammonium salts. In this invention, "(meth)acrylic" means methacrylic acid or acrylic acid. In this invention, "(meth)acryloyl" means methacryloyl or acryloyl. In this invention, "(meth)acrylate" means methacrylate or acrylate.

[0030] (3) Sulfonic acid group-containing vinyl monomers, vinyl sulfate monoesters, and salts thereof Examples of the sulfonic acid group-containing vinyl monomers, vinyl sulfate monoesters, and salts thereof include C2-C14 alkene sulfonic acid (salt), C2-C24 alkyl sulfonic acid (salt), sulfo(hydroxy)alkyl-(meth)acrylate (salt), (meth)acrylamide (salt), and alkylallyl sulfosuccinate (salt). Examples of the alkene sulfonic acid having 2 to 14 carbon atoms include vinyl sulfonic acid (salt). Examples of the alkyl sulfonic acid (salt) having 2 to 24 carbon atoms include α-methylstyrene sulfonic acid (salt). Examples of the sulfo(hydroxy)alkyl-(meth)acrylate (salt) include sulfopropyl (meth)acrylate (salt), sulfate ester (salt), or sulfonic acid group-containing vinyl monomer (salt).

[0031] (4) Phosphate group-containing vinyl monomers and their salts Examples of the phosphate group-containing vinyl monomer and its salts include (meth)acryloyloxyalkyl (1-24 carbon atoms) phosphate monoester (salt) and (meth)acryloyloxyalkyl (1-24 carbon atoms) phosphonic acid (salt). Examples of the (meth)acryloyloxyalkyl (1-24 carbon atoms) phosphate monoester (salt) mentioned above include 2-hydroxyethyl (meth)acryloyl phosphate (salt) and phenyl-2-acryloyloxyethyl phosphate (salt). Examples of the (meth)acryloyloxyalkyl (1-24 carbon atoms) phosphonic acid (salt) mentioned above include 2-acryloyloxyethylphosphonic acid (salt).

[0032] (5) Hydroxyl group-containing vinyl monomer Examples of the hydroxyl group-containing vinyl monomers include hydroxystyrene, N-methylol(meth)acrylamide, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, polyethylene glycol mono(meth)acrylate, (meth)allyl alcohol, clotyl alcohol, isoclotyl alcohol, 1-buten-3-ol, 2-buten-1-ol, 2-buten-1,4-diol, propargyl alcohol, 2-hydroxyethylpropenyl ether, and sucrose allyl ether.

[0033] (6) Nitrogen-containing vinyl monomer Examples of the nitrogen-containing vinyl monomers include (6-1) amino group-containing vinyl monomers, (6-2) amide group-containing vinyl monomers, (6-3) nitrile group-containing vinyl monomers, (6-4) quaternary ammonium cation group-containing vinyl monomers, and (6-5) nitro group-containing vinyl monomers.

[0034] (6-1) Examples of amino group-containing vinyl monomers include aminoethyl (meth)acrylate.

[0035] (6-2) Examples of amide group-containing vinyl monomers include (meth)acrylamide and N-methyl(meth)acrylamide.

[0036] (6-3) Examples of nitrile group-containing vinyl monomers include (meth)acrylonitrile, cyanostyrene, and cyanoacrylate.

[0037] (6-4) Examples of vinyl monomers containing quaternary ammonium cation groups include dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, and quaternized vinyl monomers containing tertiary amine groups such as diallylamine (quaternized using quaternizing agents such as methyl chloride, dimethyl sulfate, benzyl chloride, and dimethyl carbonate).

[0038] (6-5) Examples of nitro group-containing vinyl monomers include nitrostyrene.

[0039] (7) Epoxy group-containing vinyl monomer Examples of the epoxy group-containing vinyl monomers include glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and p-vinylphenylphenyl oxide.

[0040] (8) Halogen-containing vinyl monomers Examples of the halogen-containing vinyl monomers include vinyl chloride, vinyl bromide, vinylidene chloride, allyl chloride, chlorostyrene, bromostyrene, dichlorostyrene, chloromethylstyrene, tetrafluorostyrene, and chloroprene.

[0041] (9) Vinyl esters, vinyl (thio) ethers, vinyl ketones Examples of the vinyl esters include vinyl acetate, vinyl butyrate, vinyl propionate, vinyl butyrate, diallyl phthalate, diallyl adipate, isopropenyl acetate, vinyl methacrylate, methyl 4-vinyl benzoate, cyclohexyl methacrylate, benzyl methacrylate, phenyl (meth)acrylate, vinyl methoxyacetate, vinyl benzoate, ethyl α-ethoxyacrylate, alkyl (meth)acrylate having an alkyl group with 1 to 50 carbon atoms [methyl ( (Meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, eicosyl (meth)acrylate, behenyl (meth)acrylate, etc.), dialkyl fumarate (the two alkyl groups are linear, branched, or alicyclic groups with 2 to 8 carbon atoms), diary Lumaleates (the two alkyl groups are linear, branched, or alicyclic groups with 2 to 8 carbon atoms), poly(meth)allyloxyalkanes [diallyloxyethane, triallyloxyethane, tetraallyloxyethane, tetraallyloxypropane, tetraallyloxybutane, tetramethallyloxyethane, etc.], vinyl monomers having polyalkylene glycol chains [polyethylene glycol (molecular weight 300) mono(meth)acrylate, polypropylene glycol (molecular weight 500) monoacrylate, methyl Examples include [10-mol ethylene oxide adduct (meth)acrylate, 30-mol lauryl alcohol ethylene oxide adduct (meth)acrylate, etc.], and poly(meth)acrylates [poly(meth)acrylates of polyhydric alcohols: ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, polyethylene glycol di(meth)acrylate, etc.]. Examples of vinyl (thio) ethers include vinyl methyl ether. Examples of vinyl ketones include vinyl methyl ketone.

[0042] (10) Other vinyl monomers Other vinyl monomers include, for example, tetrafluoroethylene, fluoroacrylate, isocyanatoethyl (meth)acrylate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate.

[0043] For the synthesis of the shell resin, one of the vinyl monomers (1) to (10) above may be used alone, or two or more may be used in combination. As the shell resin, styrene-(meth)acrylic acid ester copolymer and (meth)acrylic acid ester copolymer are preferred from the viewpoint of low-temperature fixation, and styrene-(meth)acrylic acid ester copolymer is more preferred.

[0044] The loss modulus G'' of the viscoelastic properties of the shell resin at a frequency of 1 Hz and 100°C is not particularly limited and can be appropriately selected depending on the purpose, but 1.5 MPa to 100 MPa is preferred, 1.7 MPa to 30 MPa is more preferred, and 2.0 MPa to 10 MPa is particularly preferred.

[0045] The loss modulus of elasticity G'' of the viscoelastic properties of the shell resin and the core resin described later at a frequency of 1 Hz and 100°C can be adjusted by changing the type and ratio of constituent monomers, or by changing the polymerization conditions (type and amount of initiator and chain transfer agent, and reaction temperature, etc.).

[0046] There are no particular restrictions on the acid value of the shell resin, and it can be appropriately selected depending on the purpose, but 75 mg KOH / g to 400 mg KOH / g is preferred, and 150 mg KOH / g to 300 mg KOH / g is more preferred. When the acid value of the shell resin is 75 mg KOH / g to 400 mg KOH / g, resin fine particles containing vinyl-based units that include the shell resin and core resin as constituent components within the same particle are more likely to form toner that adheres to the surface of the toner matrix particles. The acid value mentioned above is a theoretical acid value calculated from the molar amount of acidic groups contained in the constituent monomers and the total weight of the constituent monomers.

[0047] The shell resin preferably contains methacrylic acid and / or acrylic acid. There are no particular restrictions on the content of the methacrylic acid and / or acrylic acid, and it can be appropriately selected depending on the purpose, but it is preferably 10% to 60% by mass relative to the shell resin, and more preferably 30% to 50% by mass. This makes it possible to set the acid value of the shell resin to 75 mg KOH / g to 400 mg KOH / g.

[0048] There are no particular restrictions on the glass transition temperature (Tg) of the shell resin, and it can be appropriately selected depending on the purpose, but it is preferably 0°C to 150°C, and more preferably 50°C to 100°C. If the Tg is 0°C or higher, it has excellent heat resistance for storage. If the Tg is 150°C or lower, it has excellent low-temperature fixing properties.

[0049] The glass transition temperature (Tg) of the shell resin is preferably higher than the glass temperature (Tg) of the core resin, which will be described later. This results in a toner with excellent heat resistance for storage. To make the glass transition temperature (Tg) of the shell resin higher than the glass temperature (Tg) of the core resin described later, one example is to adjust the monomers used when synthesizing the shell resin, the ratio of the monomers, etc.

[0050] There are no particular restrictions on the measurement of the glass transition temperature (Tg) of the shell resin, and it can be appropriately selected depending on the purpose. For example, it can be measured using the method (DSC) specified in ASTM D3418-82 with a DSC60-A (manufactured by Shimadzu Corporation). Specifically, the melting point and glass transition temperature of the target sample can be measured using the following procedure. First, put about 5.0 mg of the target sample into a sample container made of aluminum, place the sample container on the holder unit, and set it in an electric furnace. Then, under a nitrogen atmosphere, heat it from 0 °C to 150 °C at a heating rate of 1 *0 °C / min. After that, cool it from 150 °C to 0 °C at a cooling rate of 1 *0 °C / min, and then heat it from 0 °C to 150 °C at a heating rate of 1 *0 °C / min, and measure the DSC curve using a differential scanning calorimeter (「DSC-60」, manufactured by Shimadzu Corporation). From the obtained DSC curve, using the analysis program 『Endothermic Shoulder Temperature』 in the DSC-60 system, select the DSC curve during the first heating, and the glass transition temperature of the target sample during the first heating can be obtained. Also, using 『Endothermic Shoulder Temperature』, select the DSC curve during the second heating, and the glass transition temperature of the target sample during the second heating can be obtained. Also, from the obtained DSC curve, using the analysis program 『Endothermic Peak Temperature』 in the DSC-60 system, select the DSC curve during the first heating, and the melting point of the target sample during the first heating can be obtained. Also, using 『Endothermic Peak Temperature』, select the DSC curve during the second heating, and the melting point of the target sample during the second heating can be obtained.

[0051] The solubility parameter of the shell resin (hereinafter sometimes referred to as the SP value) is preferably 9 (cal / cm 3 ) 1 / 2 to 13 (cal / cm 3 ) 1 / 2 hereinafter, more preferably 9.5 (cal / cm 3)1 / 2 ) to 12.5 (cal / cm 3 ) 1 / 2 hereinafter, even more preferably 10.5 (cal / cm 3 ) to 11.5 (cal / cm 1 / 2 ) 3 hereinafter. 1 / 2 Even more preferably. The SP value of the shell resin can be adjusted by changing the types of monomers constituting it and their composition ratios. The aforementioned SP value can be calculated using the Fedors method [Polym.Eng.Sci.14(2)152,(1974)].

[0052] There are no particular restrictions on the number-average molecular weight (Mn) of the shell resin, and it can be appropriately selected depending on the purpose, but 2,000 to 2,000,000 is preferred, and 20,000 to 200,000 is more preferred. When the number-average molecular weight is 2,000 or more, the heat-resistant storage properties are improved. When the number-average molecular weight is 2,000,000 or less, the low-temperature fixation properties are improved.

[0053] There are no particular restrictions on the weight-average molecular weight (Mw) of the shell resin, and it can be appropriately selected depending on the purpose. However, it is preferable that it is greater than the weight-average molecular weight of the core resin, more preferably 1.5 times or more than the weight-average molecular weight of the core resin, and particularly preferable 2.0 times or more. This makes it easier to form the toner and improves low-temperature fixation. Furthermore, the weight-average molecular weight (Mw) of the shell resin is preferably 20,000 to 20,000,000, and more preferably 200,000 to 2,000,000. When the weight-average molecular weight is 20,000 or more, the heat-resistant storage properties are improved. When the weight-average molecular weight is 20,000,000 or less, there is less inhibition of low-temperature fixation properties.

[0054] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) can be measured, for example, using gel permeation chromatography (GPC) under the following measurement conditions. [Measurement conditions] • Device (example): "HLC-8120" [Manufactured by Tosoh Corporation] • Column (example): "TSK GEL GMH6" [manufactured by Tosoh Corporation] 2 pieces ·Measurement temperature: 40℃ • Sample solution: 0.25% by weight tetrahydrofuran solution (insoluble matter filtered out using a glass filter) ·Solution injection volume: 100μl • Detection device: Refractive index detector • Reference material: Standard polystyrene (TSKstandard POLYSTYRENE) 12 samples (molecular weight: 500, 1,050, 2,800, 5,970, 9,100, 18,100, 37,900, 96,400, 190,000, 355,000, 1,090,000, 2,890,000) [Manufactured by Tosoh Corporation]

[0055] <<Core resin>> As the core resin, a polymer obtained by homopolymerizing or copolymerizing vinyl monomers is preferred. Examples of vinyl monomers used in the core resin include those similar to those used in the shell resin. From the viewpoint of low-temperature fixation properties, styrene-(meth)acrylic acid ester copolymer and (meth)acrylic acid ester copolymer are preferred as the core resin, and styrene-(meth)acrylic acid ester copolymer is more preferred.

[0056] The loss modulus G'' of the viscoelastic properties of the core resin at a frequency of 1 Hz and 100°C is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.01 MPa to 1.0 MPa, more preferably 0.02 MPa to 0.5 MPa, and even more preferably 0.05 MPa to 0.3 MPa. When the loss modulus G'' of the viscoelastic properties is 0.01 MPa to 1.0 MPa, the resin fine particles containing the shell resin and the core resin as constituent components within the same particle are likely to form toner that adheres to the surface of the toner matrix particles.

[0057] There are no particular restrictions on the acid value of the core resin, and it can be appropriately selected depending on the purpose, but it is preferably 0 mg KOH / g or more and 50 mg KOH / g or less, more preferably 0 mg KOH / g or more and 20 mg KOH / g or less, and particularly preferably 0 mg KOH / g.

[0058] There are no particular restrictions on the glass transition temperature (Tg) of the core resin, and it can be appropriately selected depending on the purpose, but -30°C to 100°C is preferred, 0°C to 80°C is more preferred, and 30°C to 60°C is particularly preferred. If the Tg is -30°C or higher, it has excellent heat resistance for storage. If the Tg is 100°C or lower, it has excellent low-temperature fixing properties.

[0059] The solubility parameter of the core resin (hereinafter sometimes referred to as the SP value) is set to 8.5 (cal / cm³) from the viewpoint of ease of toner formation. 3 ) 1 / 2 More than 12.5(cal / cm 3 ) 1 / 2 The following is preferable: 9 (cal / cm³) 3 ) 1 / 2 More than 12(cal / cm 3 ) 1 / 2 The following is more preferable: 10 (cal / cm³) 3 ) 1 / 2 More than 11(cal / cm 3 ) 1 / 2 The following are particularly preferable. The SP value of the core resin can be adjusted by changing the types of monomers that make up the resin and their respective composition ratios.

[0060] There are no particular restrictions on the number-average molecular weight (Mn) of the core resin, and it can be appropriately selected depending on the purpose, but 1,000 to 1,000,000 is preferred, and 10,000 to 100,000 is more preferred. When the number-average molecular weight is 1,000 or more, the heat-resistant storage properties are improved. When the number-average molecular weight is 1,000,000 or less, the low-temperature fixation properties are improved.

[0061] There are no particular restrictions on the weight-average molecular weight (Mw) of the core resin, and it can be appropriately selected depending on the purpose, but 10,000 to 10,000,000 is preferred, and 100,000 to 1,000,000 is more preferred. If the weight-average molecular weight is 10,000 or more, the heat resistance of the toner is improved. If the weight-average molecular weight is 10,000,000 or less, the low-temperature fixation is improved.

[0062] There are no particular restrictions on the volume-average particle size of the resin fine particles, and they can be appropriately selected depending on the purpose, but a size of 0.01 μm or more and 0.06 μm or less is preferred, and a size of 0.01 μm or more and 0.04 μm or less is more preferred. When the volume-average particle size is 0.01 μm or more, good cleaning performance can be obtained while ensuring low-temperature fixation.

[0063] As a method for measuring the volume-average particle diameter, for example, a scanning electron microscope (SEM) can be used to observe and capture SEM images, and the measurement can be taken from the captured SEM images.

[0064] There are no particular restrictions on the glass transition temperature (Tg) of the resin fine particles, and it can be appropriately selected depending on the purpose, but it is preferably 40°C to 70°C. When the glass transition temperature (Tg) is 40°C to 70°C, high heat resistance for storage can be ensured without hindering the fixing of the toner. To achieve the glass transition temperature Tg of 40°C to 70°C, for example, one can appropriately adjust the glass transition temperatures of the shell resin and the core resin.

[0065] One method for measuring the glass transition temperature Tg of the resin fine particles is to physically remove the resin fine particles from the toner surface or separate them using an organic solvent before measuring the temperature.

[0066] There are no particular restrictions on the mass ratio of the shell resin to the core resin in the resin fine particles, and it can be appropriately selected depending on the purpose, but 5 / 95 to 95 / 5 is preferred, 25 / 75 to 75 / 25 is more preferred, and 40 / 60 to 60 / 40 is particularly preferred. When the mass ratio is 5 / 95 or higher, the toner has excellent heat resistance for storage. When the mass ratio is 95 / 5 or lower, the resin fine particles tend to adhere to the surface of the toner matrix particles, forming toner.

[0067] Examples of methods for producing the aforementioned resin fine particles include known manufacturing methods, such as the following manufacturing methods (I) to (V). (I) A method of seed polymerization of constituent monomers of a core resin using fine particles of a shell resin in an aqueous dispersion as seeds. (II) A method for seed polymerization of constituent monomers of a shell resin using fine particles of a core resin in an aqueous dispersion as seeds. (III) A method for obtaining an aqueous dispersion of resin fine particles by emulsifying a mixture of shell resin and core resin in an aqueous medium. (IV) A method for obtaining an aqueous dispersion of resin fine particles by emulsifying a mixture of shell resin and core resin constituent monomers in an aqueous medium, and then polymerizing the core resin constituent monomers. (V) A method of obtaining an aqueous dispersion of resin fine particles by emulsifying a mixture of core resin and shell resin constituent monomers in an aqueous medium, and then polymerizing the shell resin constituent monomers.

[0068] The fact that the resin microparticles contain the shell resin and the core resin as constituent components within the same particle can be confirmed by observing elemental mapping images of the cross-section of the resin microparticles using a known surface elemental analyzer (such as TOF-SIMSEDX-SEM), and by observing electron microscope images of the cross-section of the resin microparticles stained with a dye corresponding to the functional groups contained in the shell resin and core resin. Furthermore, the resin fine particles obtained by this method may be a mixture containing resin fine particles that have both shell resin and core resin as constituent components within the same particle, as well as resin fine particles that have only shell resin as a constituent resin component and resin fine particles that have only core resin as a constituent resin component. In the compounding process described later, the mixture may be used as is, or the resin fine particles may be isolated and used separately.

[0069] Specific examples of (I) above include a method in which a constituent monomer of a shell resin is polymerized dropwise to produce an aqueous dispersion of resin fine particles containing the shell resin, and then the constituent monomer of the core resin is polymerized using this as a seed, and a method in which a shell resin previously produced by solution polymerization or the like is emulsified and dispersed in water, and then the constituent monomer of the core resin is polymerized using this as a seed.

[0070] Specific examples of (II) above include a method in which constituent monomers of a core resin are polymerized dropwise to produce an aqueous dispersion of resin fine particles containing the core resin, and then the constituent monomers of the shell resin are polymerized using this as a seed, and a method in which a core resin previously produced by solution polymerization or the like is emulsified and dispersed in water, and then the constituent monomers of the shell resin are polymerized using this as a seed.

[0071] Specific examples of (III) above include a method in which a solution or melt of a shell resin and a core resin, which have been manufactured in advance by solution polymerization or the like, are mixed, and then the mixture is emulsified and dispersed in an aqueous medium.

[0072] Specific examples of (IV) above include a method in which a shell resin produced in advance by solution polymerization or the like is mixed with constituent monomers of a core resin, the mixture is emulsified and dispersed in an aqueous medium, and then the constituent monomers of the core resin are polymerized; and a method in which a shell resin is produced in constituent monomers of a core resin, the mixture is emulsified and dispersed in an aqueous medium, and then the constituent monomers of the core resin are polymerized.

[0073] Specific examples of (V) above include a method in which a core resin produced in advance by solution polymerization or the like is mixed with constituent monomers of a shell resin, the mixture is emulsified and dispersed in an aqueous medium, and then the constituent monomers of the shell resin are polymerized; and a method in which the shell resin is produced in constituent monomers, the mixture is emulsified and dispersed in an aqueous medium, and then the constituent monomers of the shell resin are polymerized.

[0074] <Zinc stearate particles> The zinc stearate particles are used as an external additive. The volume-average particle diameter of the zinc stearate particles is 3 μm or more and 20 μm or less, preferably 5 μm or more and 15 μm or less. When the volume-average particle diameter is 3 μm or more, the zinc stearate particles are prevented from becoming embedded in the toner matrix particles, allowing the zinc stearate particles to be released from the toner matrix particles, improving the coating effect on the photoreceptor and resulting in excellent cleaning performance. When the volume-average particle diameter is 20 μm or less, the zinc stearate particles are prevented from being captured by the cleaning blade, resulting in excellent cleaning performance.

[0075] There are no particular restrictions on the method for measuring the volume-average particle diameter of the zinc stearate particles, and a suitable method can be selected depending on the purpose. For example, the zinc stearate particles may be observed and photographed using a scanning electron microscope (SEM), and the longest length of randomly selected zinc stearate particles may be measured using the image analysis software ImageJ on the captured SEM images (number of particles measured: 100 to 200), and the average particle diameter may be calculated.

[0076] The zinc stearate particles can be manufactured industrially by methods such as a wet process or a dry process. In the aforementioned wet method, stearic acid can be saponified with caustic soda or caustic potash to form an alkaline soap, which is then reacted with zinc to obtain zinc stearate particles. As a dry method, zinc stearate particles can be obtained by reacting stearic acid with zinc oxide or hydroxide. Methods for micronizing the zinc stearate particles include dry grinding of dried zinc stearate particles using high-pressure air, and wet grinding of the particles by dispersing them in silicone oil or the like using a bead mill.

[0077] Commercially available zinc stearate particles may be used as the aforementioned zinc stearate particles. Examples of the aforementioned commercially available products include the SZ-2000 (manufactured by Sakai Chemical Industry Co., Ltd.).

[0078] There are no particular restrictions on the content of the zinc stearate particles, and it can be appropriately selected depending on the purpose, but it is preferably 0.05% by mass or more and 0.20% by mass or less, and more preferably 0.08% by mass or more and 0.16% by mass or less, relative to the toner matrix particles.

[0079] There are no particular restrictions on the amount of zinc released from the toner in the zinc stearate particles, and it can be appropriately selected depending on the purpose, but it is preferably 0.005% by mass or more, and more preferably 0.01% by mass or more and 0.06% by mass or less. When the amount of released zinc is 0.005% by mass or more, the photoreceptor is coated with the zinc stearate particles released from the toner, improving cleaning performance.

[0080] <Toner matrix particles> The toner matrix particles preferably contain at least a binder resin, a colorant, a release agent, and an inorganic filler, and may further contain other components as needed.

[0081] <<Binding resin>> The binder resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyester resin, styrene-acrylic resin, polyol resin, vinyl resin, polyurethane resin, epoxy resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, and polycarbonate resin. These may be used individually or in combination of two or more. Among these, polyester resin is preferred because it can impart flexibility to the toner.

[0082] <<<Polyester resin>>> There are no particular restrictions on the polyester resin, and it can be appropriately selected depending on the purpose. Examples include crystalline polyester resins, amorphous polyester resins, modified polyester resins, amorphous hybrid resins, etc. These may be used individually or in combination of two or more.

[0083] -Amorphous polyester resin- The amorphous polyester resin (hereinafter sometimes referred to as "amorphous polyester," "amorphous polyester," "amorphous polyester resin," "unmodified polyester resin," and "polyester resin component A") is not particularly limited and can be appropriately selected depending on the purpose. Examples include amorphous polyester resins obtained by reacting a polyol with a polycarboxylic acid. In this invention, amorphous polyester resin refers to a resin obtained by reacting a polyol with a polycarboxylic acid. Modified polyester resins, such as the prepolymers described later, and modified polyester resins obtained by crosslinking and / or stretching the prepolymers, are treated as modified polyester resins, not amorphous polyester resins. The amorphous polyester is a polyester resin component soluble in tetrahydrofuran (THF). As the amorphous polyester, linear polyester resin is preferred.

[0084] Examples of the aforementioned polyols include diols. Examples of the aforementioned diols include alkylene (2-3 carbon atoms) oxide (average number of added moles 1-10) adducts of bisphenol A such as polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene (2,2)-2,2-bis(4-hydroxyphenyl)propane; ethylene glycol; propylene glycol; hydrogenated bisphenol A; and alkylene (2-3 carbon atoms) oxide (average number of added moles 1-10) adducts of hydrogenated bisphenol A. These may be used individually or in combination of two or more types. Among these, it is preferable that the polyol contains 40 mol% or more of alkylene glycol.

[0085] Examples of the polycarboxylic acid include dicarboxylic acids. Examples of the dicarboxylic acid include succinic acids such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, dodecenyl succinic acid, and octyl succinic acid. These may be used individually or in combination of two or more. Among these, terephthalic acid is preferred.

[0086] The amorphous polyester resin may contain trivalent or higher carboxylic acids, trivalent or higher alcohols, trivalent or higher epoxy compounds, etc., at the ends of its resin chains in order to adjust the acid value and hydroxyl value. Among these, trivalent or higher alcohols are preferred from the viewpoint of being less prone to unevenness and obtaining sufficient gloss and image density. Examples of the carboxylic acids with a valency of 3 or higher include trimellitic acid, pyromellitic acid, or their acid anhydrides. Examples of trivalent or higher alcohols include glycerin, pentaerythritol, and trimethylolpropane.

[0087] Furthermore, it is preferable that the amorphous polyester resin component contains a crosslinking component. While trivalent or higher carboxylic acids and epoxy compounds can be used as crosslinking components for amorphous polyester resin components, it is more preferable to include trivalent or higher aliphatic alcohols as crosslinking components from the viewpoint of preventing unevenness and obtaining sufficient gloss and image density. The crosslinking component preferably contains a trivalent or higher aliphatic alcohol, and more preferably contains a trivalent or tetravalent aliphatic alcohol from the viewpoint of gloss and image density of the fixed image. The trivalent or tetravalent aliphatic alcohol is preferably a trivalent or tetravalent aliphatic polyhydric alcohol component having 3 to 10 carbon atoms. The crosslinking component may consist only of the trivalent or higher aliphatic alcohol. The aforementioned trivalent or higher aliphatic alcohols can be appropriately selected depending on the purpose, and examples include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, and dipentaerythritol. These trivalent or higher aliphatic alcohols may be used individually or in combination of two or more.

[0088] The molecular weight of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably within the following range. The weight-average molecular weight (Mw) of the amorphous polyester resin is preferably 3,000 to 10,000, and more preferably 4,000 to 7,000. The number-average molecular weight (Mn) of the amorphous polyester resin is preferably 1,000 to 4,000, and more preferably 1,500 to 3,000. The molecular weight ratio (Mw / Mn) of the amorphous polyester resin is preferably 1.0 to 4.0, and more preferably 1.0 to 3.5. The aforementioned molecular weight can be measured by GPC (gel permeation chromatography). The reason why the molecular weight is preferably within the above range is that if the molecular weight is too low, the toner may have poor heat resistance for storage and durability against stress such as agitation in the developing machine. If the molecular weight is too high, the viscoelasticity of the toner when melted may increase, resulting in poor low-temperature fixing properties. Also, if there is too much of a component with a molecular weight of 600 or less, the toner may have poor heat resistance for storage and durability against stress such as agitation in the developing machine. If there is too little of a component with a molecular weight of 600 or less, the low-temperature fixing properties may be poor.

[0089] The THF-soluble components with a molecular weight of 600 or less are preferably present in an amount of 2% to 10% by mass. One method for adjusting the content of this component is to extract amorphous polyester resin with methanol, remove components with a molecular weight of 600 or less, and then purify it.

[0090] There are no particular restrictions on the acid value of the amorphous polyester resin, and it can be appropriately selected depending on the purpose, but 1 mg KOH / g to 50 mg KOH / g is preferred, and 5 mg KOH / g to 30 mg KOH / g is more preferred. When the acid value is 1 mg KOH / g or higher, the toner tends to become negatively charged, and furthermore, the affinity between the paper and the toner improves when fixing to paper, and low-temperature fixing performance can be improved. On the other hand, when the acid value is 50 mg KOH / g or lower, it is possible to prevent problems such as a decrease in charge stability, especially charge stability against environmental fluctuations.

[0091] There are no particular restrictions on the hydroxyl value of the amorphous polyester resin, and it can be appropriately selected depending on the purpose, but 5 mg KOH / g or higher is preferred.

[0092] There are no particular restrictions on the glass transition temperature (Tg) of the amorphous polyester resin, and it can be appropriately selected depending on the purpose, but it is preferably 40°C to 65°C, more preferably 45°C to 65°C, and even more preferably 50°C to 60°C. When the Tg is 40°C or higher, the heat resistance of the toner during storage and its durability against stress such as agitation in the developing machine are improved, and its filming resistance is also improved. When the Tg is 65°C or lower, deformation due to heating and pressurization during toner fixing is improved, and low-temperature fixing performance is improved.

[0093] There are no particular restrictions on the content of the amorphous polyester resin, and it can be appropriately selected depending on the purpose, but it is preferably 80 parts by mass or more and 90 parts by mass or less per 100 parts by mass of toner.

[0094] -Crystalline polyester resin- The crystalline polyester resin (hereinafter also referred to as "crystalline polyester" or "polyester resin component D") is not particularly limited and can be appropriately selected depending on the purpose. For example, a crystalline polyester resin obtained by reacting a polyol with a polycarboxylic acid can be used.

[0095] The aforementioned crystalline polyester resin exhibits thermal melting properties, showing a rapid decrease in viscosity near the fixing start temperature, due to its high crystallinity. By using the crystalline polyester resin having these characteristics together with the amorphous polyester resin, the toner exhibits high heat resistance and storage properties due to its crystallinity until just before the melting temperature. Upon reaching the melting temperature, the crystalline polyester resin undergoes a rapid decrease in viscosity (sharp melt), causing it to become compatible with the amorphous polyester resin. As a result, both materials rapidly decrease in viscosity and fix together. This yields a toner that combines excellent heat resistance and low-temperature fixing properties. Furthermore, the release width (the difference between the fixing lower limit temperature and the high-temperature offset occurrence temperature) also shows favorable results.

[0096] The crystalline polyester resin is obtained using a polyhydric alcohol (polyol) and a polyhydric carboxylic acid or its derivative, such as a polyhydric carboxylic acid, polyhydric carboxylic acid anhydride, or polyhydric carboxylic acid ester. In this invention, crystalline polyester resin refers to a resin obtained by reacting a polyol with a polycarboxylic acid. Modified polyester resins, such as the prepolymers described later, and modified polyester resins obtained by crosslinking and / or stretching the prepolymers, are treated as modified polyester resins, not amorphous polyester resins.

[0097] --Polyhydric alcohols (polyols)-- There are no particular restrictions on the polyhydric alcohol (polyol) mentioned above, and it can be appropriately selected depending on the purpose. Examples include diols and polyols with a valency of three or higher.

[0098] Examples of the aforementioned diols include saturated aliphatic diols. Examples of the saturated aliphatic diols include linear saturated aliphatic diols and branched saturated aliphatic diols. These may be used individually or in combination of two or more. Among these, linear saturated aliphatic diols are preferred because they improve crystallinity and prevent a decrease in the melting point, and linear saturated aliphatic diols with 2 to 12 carbon atoms are more preferred. If the saturated aliphatic diol is branched, the crystallinity of the crystalline polyester resin may decrease, and the melting point may be lowered. Furthermore, if the number of carbon atoms in the saturated aliphatic diol exceeds 12, it may become difficult to obtain practical materials. It is more preferable that the number of carbon atoms be 12 or less.

[0099] Examples of the saturated aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanediol. Among these, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred because they exhibit high crystallinity and excellent sharp-melt properties in the crystalline polyester resin.

[0100] Examples of trivalent or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0101] --Polycarboxylic acids-- There are no particular restrictions on the polycarboxylic acid (polycarboxylic acid) and it can be appropriately selected depending on the purpose. Examples include divalent carboxylic acids and trivalent or higher carboxylic acids.

[0102] Examples of the aforementioned divalent carboxylic acids include saturated aliphatic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, superiric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, and mesaconic acid; and further, their anhydrides and lower (1-3 carbon atoms) alkyl esters.

[0103] Examples of the carboxylic acids with a valency of 3 or higher include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, their anhydrides, and their lower (1-3 carbon atoms) alkyl esters.

[0104] In addition to the saturated aliphatic dicarboxylic acids and aromatic dicarboxylic acids, the polycarboxylic acid may also include a dicarboxylic acid having a sulfonic acid group. Furthermore, in addition to the saturated aliphatic dicarboxylic acids and aromatic dicarboxylic acids, it may also include a dicarboxylic acid having a double bond. These can be used individually or in combination of two or more types.

[0105] The crystalline polyester resin is preferably composed of a linear saturated aliphatic dicarboxylic acid having 4 to 12 carbon atoms and a linear saturated aliphatic diol having 2 to 12 carbon atoms. That is, the crystalline polyester resin preferably has constituent units derived from a saturated aliphatic dicarboxylic acid having 4 to 12 carbon atoms and constituent units derived from a saturated aliphatic diol having 2 to 12 carbon atoms. This is preferable because it exhibits high crystallinity and excellent sharp melt properties, thus providing excellent low-temperature fixability.

[0106] The presence or absence of crystallinity in the aforementioned crystalline polyester resin can be confirmed using a crystallographic X-ray diffractometer (e.g., X'Pert Pro MRD, Philips). The measurement method is described below. First, the target sample is ground in a mortar to create a sample powder, and the resulting sample powder is uniformly applied to the sample holder. Then, the sample holder is set in the diffractometer, and measurements are taken to obtain the diffraction spectrum. Crystallinity is determined to exist if the peak with the highest peak intensity among the obtained diffraction peaks in the range of 20° < 2θ < 25° has a peak width at half maximum of 2.0 or less. In this invention, a polyester resin that does not exhibit the above-mentioned state, as opposed to a crystalline polyester resin, is referred to as an amorphous polyester resin. The measurement conditions for X-ray diffraction are described below. [Measurement conditions] Tension kV: 45kV Current: 40mA MPSS Upper Gonio Scanmode: continuos Starting angle: 3° End angle: 35° Angle Step: 0.02° Lucident beam optics Divergence slit: Div slit 1 / 2 Difflection beam optics Anti scatter slit: As fixed 1 / 2 Receiving slit: Prog rec slit

[0107] There are no particular restrictions on the melting point of the crystalline polyester resin, and it can be appropriately selected depending on the purpose, but a melting point of 60°C or higher and 80°C or lower is preferred. If the melting point is 60°C or higher, the crystalline polyester resin melts easily at low temperatures, and excellent heat resistance for storage is obtained. If the melting point is 80°C or lower, the crystalline polyester resin does not melt sufficiently due to heating during fixing, and excellent low-temperature fixing properties are obtained.

[0108] There are no particular restrictions on the molecular weight of the crystalline polyester resin, and it can be appropriately selected depending on the purpose. The soluble orthodichlorobenzene content of the crystalline polyester resin is preferably such that, in GPC measurement, the weight-average molecular weight (Mw) is 3,000 to 30,000, and more preferably 5,000 to 15,000. The soluble orthodichlorobenzene content of the crystalline polyester resin is preferably such that the number average molecular weight (Mn) is 1,000 to 10,000, and more preferably 2,000 to 10,000, as measured by GPC. The molecular weight ratio Mw / Mn of the crystalline polyester resin is preferably 1.0 to 10, and more preferably 1.0 to 5.0. This is because substances with a sharp molecular weight distribution and low molecular weight exhibit excellent low-temperature fixation properties, while a high proportion of low molecular weight components reduces heat resistance during storage.

[0109] There are no particular restrictions on the acid value of the crystalline polyester resin, and it can be appropriately selected depending on the purpose, but it is preferably 5 mg KOH / g or more and 45 mg KOH / g or less, and more preferably 10 mg KOH / g or more and 45 mg KOH / g or less. When the acid value is 5 mg KOH / g or more, excellent low-temperature fixation properties are obtained. When the acid value is 45 mg KOH / g or less, excellent high-temperature offset resistance is obtained.

[0110] There are no particular restrictions on the hydroxyl value of the crystalline polyester resin, and it can be appropriately selected depending on the purpose. However, a value of 0 mg KOH / g or more and 50 mg KOH / g or less is preferred, and a value of 5 mg KOH / g or more and 50 mg KOH / g or less is more preferred, in order to obtain excellent low-temperature fixing properties and electrostatic properties.

[0111] The molecular structure of the crystalline polyester resin can be confirmed by NMR measurements in solution or solid state, as well as by X-ray diffraction, GC / MS, LC / MS, IR measurements, etc. A simpler method is infrared absorption spectroscopy, which can be used to determine the structure at 965±10 cm⁻¹. -1 or 990±10cm -1 One method involves detecting crystalline polyester resins that exhibit absorption based on δCH (out-of-plane bending vibration) of olefins.

[0112] There are no particular restrictions on the content of the crystalline polyester resin, and it can be appropriately selected depending on the purpose, but it is preferably 3 parts by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of toner. When the content is 3 parts by mass or more, sufficient sharp melting of the crystalline polyester resin occurs and the low-temperature fixing performance is excellent. When the content is 20 parts by mass or less, the heat resistance for storage is excellent and the occurrence of image fogging can be prevented.

[0113] There are no particular restrictions on the polyhydric alcohol component, and it can be appropriately selected depending on the purpose. Examples include alkylene (2-3 carbon atoms) oxide (average number of added moles 1-10) adducts of bisphenol A such as polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene (2,2)-2,2-bis(4-hydroxyphenyl)propane, ethylene glycol, propylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, hydrogenated bisphenol A, sorbitol, and their alkylene (2-3 carbon atoms) oxide (average number of added moles 1-10) adducts. These may be used individually or in combination of two or more.

[0114] The polycarboxylic acid component is not particularly limited and can be appropriately selected depending on the purpose. Examples include dicarboxylic acids such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, and maleic acid; succinic acid substituted with C1-C20 alkyl groups or C2-C20 alkenyl groups such as dodecenyl succinic acid and octyl succinic acid; trimellitic acid and pyromellitic acid; anhydrides of these acids; and alkyl (C1-C8) esters of these acids. These may be used individually or in combination of two or more.

[0115] The amorphous polyester resin is preferably at least partially compatible with a prepolymer (described later) and a resin obtained by crosslinking and / or stretching the prepolymer, thereby improving low-temperature fixability and high-temperature offset resistance.

[0116] The weight-average molecular weight (Mw) of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but 2,500 to 10,000 is preferred. The number-average molecular weight (Mn) of the amorphous polyester resin is not particularly limited and can be appropriately selected depending on the purpose, but 1,000 to 4,000 is preferred. There are no particular restrictions on the aforementioned Mw / Mn, and it can be appropriately selected according to the purpose, but it is preferably between 1.0 and 4.0. There are no particular restrictions on the method for measuring the weight-average molecular weight (Mw) and number-average molecular weight (Mn), and they can be appropriately selected depending on the purpose. For example, they can be measured by gel permeation chromatography (GPC).

[0117] There are no particular restrictions on the acid value of the amorphous polyester resin, and it can be appropriately selected depending on the purpose, but it is preferably 1 mg KOH / g or more and 50 mg KOH / g or less, and more preferably 5 mg KOH / g or more and 30 mg KOH / g or less. When the acid value is 1 mg KOH / g or more, the toner tends to become negatively charged, the affinity of the toner to recording media such as paper improves, and the low-temperature fixing performance improves. When the acid value is 50 mg KOH / g or less, good electrostatic stability against environmental fluctuations can be maintained.

[0118] There are no particular restrictions on the hydroxyl value of the amorphous polyester resin, and it can be appropriately selected depending on the purpose, but 5 mg KOH / g or higher is preferred.

[0119] There are no particular restrictions on the glass transition temperature (Tg) of the amorphous polyester resin, and it can be appropriately selected depending on the purpose. However, if the Tg is too low, the heat resistance of the toner during storage and its durability against stress such as agitation in the developer may be poor, and if the Tg is too high, the viscoelasticity of the toner during melting may be high, resulting in poor low-temperature fixing properties. Therefore, 40°C to 70°C is preferred, and 45°C to 60°C is more preferred.

[0120] There are no particular restrictions on the content of the amorphous polyester resin, and it can be appropriately selected depending on the purpose, but it is preferably 50% to 95% by mass relative to the toner, and more preferably 60% to 90% by mass. When the content is 50% by mass or more, the toner components such as pigments and release agents are uniformly dispersed, and high-quality images can be obtained. When the content is 95% by mass or less, excellent low-temperature fixing properties are obtained.

[0121] The molecular structure of the amorphous polyester resin can be confirmed by NMR, X-ray diffraction, GC / MS, LC / MS, and IR measurements in solution or solid state. A simple method is to use infrared absorption spectroscopy, which can determine the structure at 965±10 cm⁻¹. -1 and 990±10cm -1One method for detecting amorphous polyester resins is one in which those that do not exhibit absorption based on δCH (out-of-plane angular bending vibration) of olefins are identified.

[0122] <<Release agent>> There are no particular restrictions on the release agent, and it can be appropriately selected from known ones. Examples of release agents for waxes and waxes include natural waxes such as: plant-based waxes such as carnauba wax, cotton wax, wood wax, and rice wax; animal-based waxes such as beeswax and lanolin; mineral waxes such as ozokerite and cerucine; and petroleum waxes such as paraffin, microcrystalline, and petrolatum.

[0123] There are no particular restrictions on the melting point of the release agent, and it can be appropriately selected depending on the purpose, but a melting point of 60°C or higher and less than 95°C is preferred.

[0124] The release agent is more preferably a hydrocarbon wax with a melting point of 60°C or higher and less than 95°C. Since such a release agent can act effectively as a release agent between the fixing roller and the toner interface, it is possible to improve high-temperature offset resistance without applying a release agent such as oil to the fixing roller. In particular, hydrocarbon waxes are preferable because they have almost no compatibility with the polyester resin A and can function independently of each other, thus not impairing the softening effect as a binder resin for crystalline polyester resin or the offsetting effect of the mold release agent. If the melting point of the release agent is below 60°C, the release agent may melt easily at low temperatures, resulting in poor heat resistance for the toner. If the melting point of the release agent is 95°C or higher, the release agent may not melt sufficiently due to heating during fixing, resulting in insufficient offset.

[0125] There are no particular restrictions on the content of the release agent, and it can be appropriately selected depending on the purpose, but it is preferably 2 to 10 parts by mass, and more preferably 3 to 8 parts by mass, per 100 parts by mass of toner. If the content is less than 2 parts by mass, the high-temperature offset resistance and low-temperature fixing performance during fixing may be poor, and if it exceeds 10 parts by mass, the heat-resistant storage performance may deteriorate, and image fogging may occur easily. If the content is within the more preferable range described above, it is advantageous in terms of improving image quality and fixing stability.

[0126] <<Coloring agent>> There are no particular restrictions on the aforementioned colorants, and they can be appropriately selected according to the purpose. For example, carbon black, nigrosine dyes, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, anthrazane yellow B GL, Isoindolinone Yellow, Bengara, Red Lead, Red Lead, Cadmium Red, Cadmium Mercury Red, Antimony Red, Permanent Red 4R, Para Red, Faise Red, Parachlor-Orthonitroaniline Red, Risol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Risol Rubin GX, Permanent Red F5R, Bri Liantcarmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinon Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine, Navy Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chromium Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake,Examples include malachite green lake, phthalocyanine green, anthraquinone green, titanium dioxide, zinc oxide, and lithobone. There are no particular restrictions on the content of the coloring agent, and it can be appropriately selected depending on the purpose, but it is preferably 1 to 15 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of toner.

[0127] The coloring agent can also be used as a masterbatch compounded with the resin. Examples of resins used in the production of the masterbatch or mixed with the masterbatch include, in addition to the hybrid resin, polymers of styrene or its substituted derivatives such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, and styrene-α-chloromethacrylate copolymer. Examples include styrene copolymers such as styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, and paraffin wax. These may be used individually or in combination of two or more.

[0128] The aforementioned masterbatch can be obtained by mixing and kneading a resin for the masterbatch and a colorant under high shear force. In this process, an organic solvent can be used to enhance the interaction between the colorant and the resin. Alternatively, a method called the flushing method, in which an aqueous paste containing water from the colorant is mixed and kneaded with the resin and organic solvent to transfer the colorant to the resin side and remove the water and organic solvent components, is also preferably used because it allows the wet cake of the colorant to be used as is, eliminating the need for drying. A high-shear dispersion device such as a three-roll mill is preferably used for mixing and kneading.

[0129] <<Inorganic filler>> The toner matrix particles may contain the inorganic filler. The inorganic filler is not particularly limited and can be appropriately selected depending on the purpose. Examples include calcium carbonate, kaolin clay, talc, barium sulfate, and layered inorganic minerals. These may be used individually or in combination of two or more. The inorganic filler may be surface-treated with a silane coupling agent, surfactant, metal soap, etc., and may also be adjusted to a desired particle size distribution by classification or the like.

[0130] The layered inorganic mineral is an inorganic mineral made up of layers several nanometers thick stacked on top of each other, and modification with organic ions means introducing organic ions into the ions present between the layers. As the layered inorganic mineral, a modified layered inorganic mineral modified with organic ions is preferred. Due to its modified layered structure, the modified layered inorganic mineral has high hydrophilicity, and during toner manufacturing, it is miniaturized and deformed, and is abundant on the surface of the toner matrix particles, thus performing a charge regulation function and exhibiting excellent low-temperature fixing.

[0131] Examples of the aforementioned layered inorganic minerals include smectites such as montmorillonite and saponite, kaolins such as kaolinite, magadhiite, and kanemite. In this case, the content of modified layered inorganic minerals in the toner material is preferably 0.2% to 1.5% by mass.

[0132] <<Other ingredients>> The other components contained in the toner matrix particles are not particularly limited and can be appropriately selected depending on the purpose. Examples include prepolymers, active hydrogen group-containing compounds, charge control agents, flow improvers, and magnetic materials.

[0133] The aforementioned prepolymer is a polymer having a site that can react with an active hydrogen group-containing compound, and is not particularly limited; it can be appropriately selected depending on the purpose. Examples include polyol resins, polyacrylic resins, polyester resins, epoxy resins, and derivatives thereof. These may be used individually or in combination of two or more. Among these, polyester resins are preferred in terms of high fluidity and transparency during melting.

[0134] The reactable sites of the prepolymer with the active hydrogen group-containing compound include isocyanate groups, epoxy groups, carboxyl groups, and functional groups represented by -COCl. These may be used individually or in combination of two or more. Among these, isocyanate groups are preferred.

[0135] There are no particular restrictions on the prepolymer, and it can be appropriately selected depending on the purpose. However, polyester resins having isocyanate groups or the like that can generate urea bonds are preferred because they allow for easy adjustment of the molecular weight of the polymer component and ensure good oil-free low-temperature fixing characteristics in dry toners, particularly in the absence of a release oil application mechanism to the fixing heating medium.

[0136] The active hydrogen group-containing compound acts as an elongating agent, crosslinking agent, etc., when the prepolymer undergoes elongation or crosslinking reactions in an aqueous medium.

[0137] The active hydrogen group is not particularly limited and can be appropriately selected depending on the purpose. Examples include hydroxyl groups such as alcoholic hydroxyl groups and phenolic hydroxyl groups, amino groups, carboxyl groups, and mercapto groups. These may be used individually or in combination of two or more.

[0138] There are no particular restrictions on the active hydrogen group-containing compound, and it can be appropriately selected depending on the purpose. However, if the prepolymer is a polyester resin containing an isocyanate group, amines are preferred. The aforementioned amines are not particularly limited and can be appropriately selected depending on the purpose. Examples include diamines, trivalent or higher amines, amino alcohols, amino mercaptans, amino acids, and those in which the amino group has been blocked. These may be used individually or in combination of two or more. Among these, diamines and trivalent or higher amines are preferred.

[0139] The diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples include aromatic diamines, alicyclic diamines, and aliphatic diamines. The aromatic diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples include phenylenediamine, diethyltoluenediamine, and 4,4'-diaminodiphenylmethane. The alicyclic diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples include 4,4'-diamino-3,3'-dimethyldicyclohexylmethane, diaminocyclohexane, and isophorone diamine. The aliphatic diamine is not particularly limited and can be appropriately selected depending on the purpose. Examples include ethylenediamine, tetramethylenediamine, and hexamethylenediamine.

[0140] There are no particular restrictions on the amines with a valency of three or higher, and they can be appropriately selected depending on the purpose. Examples include diethylenetriamine and triethylenetetramine.

[0141] The amino alcohol is not particularly limited and can be appropriately selected depending on the purpose. Examples include ethanolamine and hydroxyethylaniline. The amino mercaptan is not particularly limited and can be appropriately selected depending on the purpose. Examples include aminoethyl mercaptan and aminopropyl mercaptan.

[0142] There are no particular restrictions on the amino acids mentioned above, and they can be appropriately selected depending on the purpose. Examples include aminopropionic acid and aminocaproic acid. There are no particular limitations on the amino group that is blocked, and it can be appropriately selected depending on the purpose. Examples include ketimine compounds and oxazolidine compounds obtained by blocking the amino group with ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[0143] There are no particular limitations on the polyester resin containing the isocyanate group (hereinafter sometimes referred to as "polyester prepolymer having an isocyanate group"), and it can be appropriately selected depending on the purpose. Examples include reaction products of a polyester resin having an active hydrogen group obtained by polycondensation of a polyol and a polycarboxylic acid with a polyisocyanate.

[0144] The polyol is not particularly limited and can be appropriately selected depending on the purpose. Examples include diols, trivalent or higher alcohols, and mixtures of diols and trivalent or higher alcohols. These may be used individually or in combination of two or more. Among these, diols and mixtures of diols with small amounts of trivalent or higher alcohols are preferred.

[0145] The aforementioned diol is not particularly limited and can be appropriately selected depending on the purpose. Examples include alkylene glycols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol; diols having an oxyalkylene group such as diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; alicyclic diols such as 1,4-cyclohexanedimethanol and hydrogenated bisphenol A; alicyclic diols to which alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide have been added; bisphenols such as bisphenol A, bisphenol F, and bisphenol S; and alkylene oxide adducts of bisphenols to which alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide have been added. The number of carbon atoms in the alkylene glycol is not particularly limited and can be appropriately selected depending on the purpose, but 2 to 12 is preferred. Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferred, and a mixture of alkylene oxide adducts of bisphenols, alkylene oxide adducts of bisphenols, and alkylene glycols having 2 to 12 carbon atoms is more preferred.

[0146] There are no particular restrictions on the alcohols with a valency of three or higher, and they can be appropriately selected depending on the purpose. Examples include aliphatic alcohols with a valency of three or higher, polyphenols with a valency of three or higher, and alkylene oxide adducts of polyphenols with a valency of three or higher. There are no particular restrictions on the aliphatic alcohols with a valency of three or higher, and they can be appropriately selected depending on the purpose. Examples include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol. There are no particular restrictions on the polyphenols with a valency of three or higher, and they can be appropriately selected depending on the purpose. Examples include trisphenol PA, phenol novolac, and cresol novolac. Examples of alkylene oxide adducts of polyphenols with a valency of three or higher include those obtained by adding alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to polyphenols with a valency of three or higher. When the diol and the trivalent or higher alcohol are used in a mixture, there are no particular restrictions on the mass ratio of the trivalent or higher alcohol to the diol, and it can be appropriately selected depending on the purpose, but 0.01% to 10% by mass is preferred, and 0.01% to 1% by mass is more preferred.

[0147] The polycarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples include dicarboxylic acids, trivalent or higher carboxylic acids, and mixtures of dicarboxylic acids and trivalent or higher carboxylic acids. These may be used individually or in combination of two or more. Among these, dicarboxylic acids and mixtures of dicarboxylic acids with small amounts of trivalent or higher polycarboxylic acids are preferred.

[0148] The dicarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples include divalent alkanic acid, divalent alkeneic acid, and aromatic dicarboxylic acid. There are no particular restrictions on the divalent alkanoic acid, and it can be appropriately selected depending on the purpose. Examples include succinic acid, adipic acid, and sebacic acid. The divalent alkenoic acid is not particularly limited and can be appropriately selected depending on the purpose, but a divalent alkenoic acid having 4 to 20 carbon atoms is preferred. The divalent alkenoic acid having 4 to 20 carbon atoms is not particularly limited and can be appropriately selected depending on the purpose, and examples include maleic acid and fumaric acid. The aromatic dicarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose, but aromatic dicarboxylic acids having 8 to 20 carbon atoms are preferred. The aromatic dicarboxylic acid having 8 to 20 carbon atoms is not particularly limited and can be appropriately selected depending on the purpose, and examples include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc.

[0149] There are no particular restrictions on the carboxylic acid with a valency of three or more, and it can be appropriately selected depending on the purpose. For example, aromatic carboxylic acids with a valency of three or more are examples. There are no particular restrictions on the trivalent or higher aromatic carboxylic acid, and it can be appropriately selected depending on the purpose, but trivalent or higher aromatic carboxylic acids having 9 to 20 carbon atoms are preferred. There are no particular restrictions on the trivalent or higher aromatic carboxylic acid having 9 to 20 carbon atoms, and it can be appropriately selected depending on the purpose, and examples include trimellitic acid and pyromellitic acid.

[0150] As the polycarboxylic acid, an acid anhydride or lower alkyl ester of any of the following may be used: a dicarboxylic acid, a trivalent or higher carboxylic acid, or a mixture of a dicarboxylic acid and a trivalent or higher carboxylic acid. The aforementioned lower alkyl ester is not particularly limited and can be appropriately selected depending on the purpose. Examples include methyl esters, ethyl esters, and isopropyl esters. When the dicarboxylic acid and the trivalent or higher carboxylic acid are used in a mixture, there are no particular restrictions on the mass ratio of the trivalent or higher carboxylic acid to the dicarboxylic acid, and it can be appropriately selected depending on the purpose, but 0.01% to 10% by mass is preferred, and 0.01% to 1% by mass is more preferred.

[0151] When polycondensing the polyol and the polycarboxylic acid, there are no particular restrictions on the equivalent ratio of the hydroxyl groups of the polyol to the carboxyl groups of the polycarboxylic acid, and it can be appropriately selected depending on the purpose, but 1 to 2 is preferred, 1 to 1.5 is more preferred, and 1.02 to 1.3 is particularly preferred.

[0152] There are no particular restrictions on the content of polyol-derived structural units in the polyester prepolymer having isocyanate groups, and it can be appropriately selected depending on the purpose, but 0.5% to 40% by mass is preferred, 1% to 30% by mass is more preferred, and 2% to 20% by mass is particularly preferred. If the aforementioned content is less than 0.5% by mass, the high-temperature offset resistance decreases, making it difficult to achieve both heat resistance for storage and low-temperature fixing properties for the toner. If it exceeds 40% by mass, the low-temperature fixing properties may decrease.

[0153] There are no particular restrictions on the polyisocyanate, and it can be appropriately selected depending on the purpose. Examples include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aromatic aliphatic diisocyanates, isocyanurates, and those obtained by blocking these with phenol derivatives, oximes, caprolactams, etc.

[0154] There are no particular restrictions on the aliphatic diisocyanate, and it can be appropriately selected depending on the purpose. Examples include tetramethylene diisocyanate, hexamethylene diisocyanate, methyl 2,6-diisocyanatocaproate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, trimethylhexane diisocyanate, and tetramethylhexane diisocyanate.

[0155] There are no particular restrictions on the alicyclic diisocyanate, and it can be appropriately selected depending on the purpose. Examples include isophorone diisocyanate and cyclohexylmethane diisocyanate.

[0156] The aromatic diisocyanate is not particularly limited and can be appropriately selected depending on the purpose. Examples include tolylene diisocyanate, diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4'-diisocyanatodiphenyl, 4,4'-diisocyanato-3,3'-dimethyldiphenyl, 4,4'-diisocyanato-3-methyldiphenylmethane, and 4,4'-diisocyanato-diphenyl ether.

[0157] The aforementioned aromatic aliphatic diisocyanate is not particularly limited and can be appropriately selected depending on the purpose. Examples include α,α,α',α'-tetramethylxylylene diisocyanate. There are no particular restrictions on the isocyanurates mentioned above, and they can be appropriately selected depending on the purpose. Examples include tris(isocyanatoalkyl)isocyanurate and tris(isocyanatocycloalkyl)isocyanurate. These may be used individually or in combination of two or more.

[0158] When reacting the polyisocyanate with a polyester resin having hydroxyl groups, there are no particular restrictions on the equivalent ratio of the isocyanate groups of the polyisocyanate to the hydroxyl groups of the polyester resin, and it can be appropriately selected depending on the purpose, but 1 to 5 is preferred, 1.2 to 4 is more preferred, and 1.5 to 3 is particularly preferred. If the equivalent ratio is less than 1, the offset resistance may decrease, and if it exceeds 5, the low-temperature fixability may decrease.

[0159] There are no particular restrictions on the content of polyisocyanate-derived structural units in the polyester prepolymer having isocyanate groups, and it can be appropriately selected depending on the purpose, but 0.5% to 40% by mass is preferred, 1% to 30% by mass is more preferred, and 2% to 20% by mass is particularly preferred. If the content is less than 0.5% by mass, the high-temperature offset resistance may decrease, and if it exceeds 40% by mass, the low-temperature fixability may decrease.

[0160] There are no particular restrictions on the average number of isocyanate groups per molecule of the polyester prepolymer having isocyanate groups, and it can be appropriately selected depending on the purpose, but it is preferably 1 or more, more preferably 1.2 to 5, and particularly preferably 1.5 to 4. If the average number is less than 1, the molecular weight of the urea-modified polyester resin will be low, and the high-temperature offset resistance may decrease.

[0161] The polyhydric alcohol component contains 50 mol% or more of a propylene oxide adduct of bisphenols, and the mass ratio of the polyester prepolymer having isocyanate groups to the polyester resin having a specific hydroxyl value and acid value is not particularly limited and can be appropriately selected depending on the purpose, but a ratio of less than 5 / greater than 95 to greater than 25 / less than 75 is preferred, and 10 / 90 to 25 / 75 is more preferred. If the mass ratio is less than 5 / 95, the high-temperature offset resistance may decrease, and if it exceeds 25 / 75, the low-temperature fixability and image gloss may decrease.

[0162] The aforementioned charge control agent is not particularly limited and can be appropriately selected depending on the purpose. Examples include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, elemental or compound phosphorus, elemental or compound tungsten, fluorine-based surfactants, metal salicylic acid salts, and metal salts of salicylic acid derivatives. Specifically, examples include the nigrosine-based dye Bontron 03, the quaternary ammonium salt Bontron P-51, the metal-containing azo dye Bontron S-34, the oxynaphthoic acid-based metal complex E-82, the salicylic acid-based metal complex E-84, the phenolic condensate E-89 (all manufactured by Orient Chemical Industry Co., Ltd.), the quaternary ammonium salt molybdenum complexes TP-302 and TP-415 (both manufactured by Hodogaya Chemical Co., Ltd.), LRA-901, the boron complex LR-147 (manufactured by Nippon Carlit Co., Ltd.), copper phthalocyanine, perylene, quinacridone, azo pigments, and other polymer compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts.

[0163] There are no particular restrictions on the content of the charge control agent, and it can be appropriately selected depending on the purpose, but preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, per 100 parts by mass of toner. If the content exceeds 10 parts by mass, the toner becomes too electrostatically charged, reducing the effect of the charge control agent, increasing the electrostatic attraction force with the developing roller, which may lead to a decrease in the fluidity of the developer and a decrease in image density. These charge control agents can be dissolved and dispersed after melting and kneading with the masterbatch and resin, or they can be added when directly dissolving and dispersing in an organic solvent, or they can be fixed to the toner surface after toner production.

[0164] <Other ingredients> Other components included in the toner are not particularly limited and can be appropriately selected depending on the purpose. Examples include other external additives other than the zinc stearate particles.

[0165] <<Other external additives>> Examples of the aforementioned other external additives include fatty acid metal salts such as calcium stearate and aluminum stearate, titanium dioxide, alumina microparticles, polymethyl methacrylate microparticles, and polymer microparticles produced by soap-free emulsion polymerization, such as polystyrene microparticles. Commercially available titania fine particles can be used, for example, P-25 and other products from Nippon Aerosil Co., Ltd., STT-30, STT-65C-S and other products from Titanium Industry Co., Ltd., TAF-140 and other products from Fuji Titanium Industry Co., Ltd., and MT-150W, MT-500B, MT-600B, MT-150A and other products from Teika Co., Ltd.

[0166] Examples of hydrophobized titanium oxide nanoparticles include T-805 (manufactured by Nippon Aerosil Co., Ltd.), STT-30A, STT-65S-S (all manufactured by Titanium Industry Co., Ltd.), TAF-500T, TAF-1500T (both manufactured by Fuji Titanium Industry Co., Ltd.), MT-100S, MT-100T (both manufactured by Teika Co., Ltd.), and IT-S (manufactured by Ishihara Sangyo Co., Ltd.).

[0167] Hydrophobized oxide nanoparticles, hydrophobized silica nanoparticles, hydrophobized titania nanoparticles, and hydrophobized alumina nanoparticles can be obtained by treating hydrophilic nanoparticles with silane coupling agents such as methyltrimethoxysilane, methyltriethoxysilane, and octyltrimethoxysilane. Silicone oil-treated oxide nanoparticles and inorganic nanoparticles, obtained by treating silicone oil with heat if necessary to convert it into inorganic nanoparticles, are also suitable.

[0168] Examples of the silicone oils mentioned above include dimethyl silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, methyl hydrogen silicone oil, alkyl-modified silicone oil, fluorine-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, epoxy-polyether-modified silicone oil, phenol-modified silicone oil, carboxyl-modified silicone oil, mercapto-modified silicone oil, acrylic-methacrylic-modified silicone oil, and α-methylstyrene-modified silicone oil. Examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, iron oxide, copper oxide, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride. Among these, silica and titanium dioxide are preferred.

[0169] There are no particular restrictions on the content of the other external additives mentioned above, and they can be appropriately selected depending on the purpose, but it is preferably 0.1% by mass or more and 5% by mass or less relative to the toner, and more preferably 0.3% by mass or more and 3% by mass or less.

[0170] <Toner manufacturing method> There are no particular limitations on the method for producing the toner, and it can be appropriately selected depending on the purpose, but it is preferable that the toner is granulated by dispersing an oil phase containing at least the amorphous polyester resin, the crystalline polyester resin, the mold release agent, and the coloring agent in an aqueous medium. One example of a method for producing the aforementioned toner is a known dissolution and suspension method. Furthermore, as another example of the toner manufacturing method, a method for forming toner matrix particles while generating a material (hereinafter sometimes referred to as "adhesive substrate") produced by an extension reaction and / or crosslinking reaction between the active hydrogen group-containing compound and a polymer having a site that can react with the active hydrogen group-containing compound is shown below. In such a method, an aqueous medium is prepared, an oil phase containing the toner material is prepared, the toner material is emulsified or dispersed, and organic solvents are removed.

[0171] -Preparation of aqueous media (aqueous phase)- The aqueous medium can be prepared, for example, by dispersing resin fine particles in the aqueous medium. The amount of resin fine particles added to the aqueous medium is not particularly limited and can be appropriately selected depending on the purpose, but 0.5% to 10% by mass is preferred. The resin particles are not particularly limited and can be appropriately selected depending on the purpose, and examples include surfactants, poorly water-soluble inorganic compound dispersants, and polymer protective colloids. These may be used individually or in combination of two or more, and among these, surfactants are preferred.

[0172] The aqueous medium is not particularly limited and can be appropriately selected depending on the purpose. Examples include water, a solvent miscible with water, and mixtures thereof. These may be used individually or in combination of two or more. Among these, water is preferred. There are no particular restrictions on the solvent that can be miscible with water, and it can be appropriately selected depending on the purpose. Examples include alcohols, dimethylformamide, tetrahydrofuran, cellosolves, and lower ketones. There are no particular restrictions on the alcohol, and it can be appropriately selected depending on the purpose. Examples include methanol, isopropanol, and ethylene glycol. The aforementioned lower ketones are not particularly limited and can be appropriately selected depending on the purpose. Examples include acetone and methyl ethyl ketone.

[0173] - Preparation of the oil phase - The oil phase containing the toner material can be prepared by dissolving or dispersing the toner material, which includes the active hydrogen group-containing compound, a polymer having a site that can react with the active hydrogen group-containing compound, the crystalline polyester resin, the amorphous polyester resin, the mold release agent, the hybrid resin, and the colorant, in an organic solvent.

[0174] There are no particular restrictions on the organic solvent, and it can be appropriately selected depending on the purpose, but an organic solvent with a boiling point of less than 150°C is preferred because it is easy to remove. The organic solvent with a boiling point below 150°C is not particularly limited and can be appropriately selected depending on the purpose. Examples include toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, and methyl isobutyl ketone. These may be used individually or in combination of two or more. Among these, ethyl acetate, toluene, xylene, benzene, methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferred, with ethyl acetate being more preferred.

[0175] -Emulsification or dispersion- The emulsification or dispersion of the toner material can be carried out by dispersing the oil phase containing the toner material in the aqueous medium. When emulsifying or dispersing the toner material, an adhesive substrate is generated by causing an extension reaction and / or crosslinking reaction between an active hydrogen group-containing compound and a polymer having a site that can react with the active hydrogen group-containing compound.

[0176] The adhesive substrate may be produced by emulsifying or dispersing an oil phase containing a polymer that is reactive to active hydrogen groups, such as a polyester prepolymer having isocyanate groups, together with a compound containing active hydrogen groups, such as amines, in an aqueous medium, and then causing an extension reaction and / or crosslinking reaction between the two in the aqueous medium; or by emulsifying or dispersing an oil phase containing toner material in an aqueous medium to which a compound containing active hydrogen groups has been previously added, and then causing an extension reaction and / or crosslinking reaction between the two in the aqueous medium; or by emulsifying or dispersing an oil phase containing toner material in an aqueous medium, then adding a compound containing active hydrogen groups, and then causing an extension reaction and / or crosslinking reaction between the two from the particle interface in the aqueous medium. When the extension reaction and / or crosslinking reaction is carried out between the two from the particle interface, a urea-modified polyester resin may be preferentially formed on the surface of the toner produced, and a concentration gradient of urea-modified polyester resin can be provided in the toner.

[0177] There are no particular restrictions on the reaction conditions (reaction time, reaction temperature) for producing the adhesive substrate, and they can be appropriately selected depending on the combination of the active hydrogen group-containing compound and the polymer having a site that can react with the active hydrogen group-containing compound. There are no particular restrictions on the reaction time, and it can be appropriately selected depending on the purpose, but 10 minutes to 40 hours is preferred, and 2 hours to 24 hours is more preferred. The reaction temperature is not particularly limited and can be appropriately selected depending on the purpose, but 0°C to 150°C is preferred, and 40°C to 98°C is more preferred.

[0178] There are no particular limitations on the method for stably forming a dispersion in the aqueous medium containing a polymer having a site that can react with an active hydrogen group-containing compound, such as a polyester prepolymer having an isocyanate group. A suitable method can be selected depending on the purpose. For example, one method involves adding an oil phase prepared by dissolving or dispersing toner material in a solvent to the aqueous medium and dispersing it by shear force.

[0179] There are no particular restrictions on the disperser used for the aforementioned dispersion, and it can be appropriately selected according to the purpose. Examples include low-speed shear dispersers, high-speed shear dispersers, friction dispersers, high-pressure jet dispersers, and ultrasonic dispersers. Among these, a high-speed shear disperser is preferred because it can control the particle size of the dispersion (oil droplets) to between 2 μm and 20 μm. When using the aforementioned high-speed shear type disperser, conditions such as rotation speed, dispersion time, and dispersion temperature can be appropriately selected according to the purpose. There are no particular restrictions on the rotational speed, and it can be appropriately selected according to the purpose, but 1,000 rpm to 30,000 rpm is preferred, and 5,000 rpm to 20,000 rpm is more preferred. There are no particular restrictions on the aforementioned distribution time, and it can be selected as appropriate depending on the purpose, but in the case of a batch method, 0.1 minutes to 5 minutes is preferable. There are no particular restrictions on the dispersion temperature, and it can be appropriately selected depending on the purpose, but under pressure, 0°C to 150°C is preferred, and 40°C to 98°C is more preferred. Generally, dispersion is easier at higher dispersion temperatures.

[0180] There are no particular restrictions on the amount of aqueous medium used when emulsifying or dispersing the toner material, and it can be appropriately selected according to the purpose, but 50 to 2,000 parts by mass, and more preferably 100 to 1,000 parts by mass, per 100 parts by mass of toner material. If the amount of the aqueous medium used is less than 50 parts by mass, the dispersion state of the toner material may deteriorate, and toner matrix particles of a predetermined particle size may not be obtained. If it exceeds 2,000 parts by mass, production costs may increase.

[0181] When emulsifying or dispersing the oil phase containing the toner material, it is preferable to use a dispersant from the viewpoint of stabilizing the dispersion, such as oil droplets, to achieve the desired shape and sharpen the particle size distribution. The aforementioned dispersant is not particularly limited and can be appropriately selected depending on the purpose. Examples include surfactants, poorly water-soluble inorganic compound dispersants, and polymeric protective colloids. These may be used individually or in combination of two or more. Among these, surfactants are preferred.

[0182] There are no particular restrictions on the surfactant, and it can be appropriately selected depending on the purpose. For example, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc., can be used. The anionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples include alkylbenzene sulfonates, α-olefin sulfonates, and phosphate esters. Among these, those having a fluoroalkyl group are preferred.

[0183] A catalyst can be used in the extension reaction and / or crosslinking reaction when producing the aforementioned adhesive substrate. The catalyst is not particularly limited and can be appropriately selected depending on the purpose. Examples include dibutylsulfurate and dioctylsulfurate.

[0184] -Removal of organic solvents- There are no particular limitations on the method for removing the organic solvent from the dispersion liquid such as the emulsified slurry, and a suitable method can be selected depending on the purpose. Examples include gradually raising the temperature of the entire reaction system to evaporate the organic solvent in the oil droplets, or spraying the dispersion liquid into a dry atmosphere to remove the organic solvent in the oil droplets. Once the organic solvent is removed, toner matrix particles are formed. These toner matrix particles can be washed, dried, and further classified. The classification may be performed by removing the fine particles in the liquid using a cyclone, decanter, centrifugation, etc., or the classification operation may be performed after drying.

[0185] The obtained toner matrix particles may be mixed with particles such as the external additive and the charge control agent. In this case, applying a mechanical impact force can suppress the detachment of particles such as the external additive from the surface of the toner matrix particles. There are no particular limitations on the method of applying the aforementioned mechanical impact force, and it can be appropriately selected depending on the purpose. Examples include a method of applying impact force to a mixture using a blade that rotates at high speed, or a method of introducing a mixture into a high-speed airflow and accelerating it to cause particles to collide with each other or with a suitable impact plate. There are no particular restrictions on the equipment used in the above method, and can be appropriately selected depending on the purpose. Examples include an Ongmill (manufactured by Hosokawa Micron Corporation), a modified I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) with reduced grinding air pressure, a hybridization system (manufactured by Nara Machine Works), a cryptron system (manufactured by Kawasaki Heavy Industries), and an automatic mortar and pestle.

[0186] <Developer> The developer of the present invention comprises at least the toner, and optionally other components such as a carrier, as appropriate. Therefore, it has excellent transferability and electrostatic properties, and can stably form high-quality images. The developer may be a one-component developer or a two-component developer, but when used in high-speed printers that can handle the recent increase in information processing speed, a two-component developer is preferred because it extends the lifespan. When the aforementioned developer is used as a single-component developer, even when toner is balanced, there is little variation in the toner particle size, resulting in less toner filming onto the developing roller and less toner fusion onto components such as blades that thin the toner layer. This allows for good and stable development and image quality even during long-term agitation in the developing apparatus. When the aforementioned developer is used as a two-component developer, even with long-term toner balance, there is little variation in toner particle size, and good and stable developability and images can be obtained even with long-term agitation in the developing device. When the toner is used in a two-component developer, it may be used in combination with the carrier. There are no particular restrictions on the amount of the carrier in the two-component developer, and it can be appropriately selected depending on the purpose, but 90% to 98% by mass is preferred, and 93% to 97% by mass is more preferred.

[0187] <Career> There are no particular restrictions on the carrier, and it can be appropriately selected according to the purpose, but one having a core material and a resin layer covering the core material is preferred.

[0188] -Core material- There are no particular restrictions on the material of the core material, and it can be appropriately selected according to the purpose. Examples include manganese-strontium materials and manganese-magnesium materials with a magnetization of 50 emu / g to 90 emu / g. Furthermore, in order to ensure image density, it is preferable to use highly magnetized materials such as iron powder of 100 emu / g or more, or magnetite with a magnetization of 75 emu / g to 120 emu / g. In addition, it is preferable to use low magnetized materials such as copper-zinc materials with a magnetization of 30 emu / g to 80 emu / g, as this can mitigate the impact of the developer in a condensed state on the photoreceptor and is advantageous for improving image quality. These can be used individually or in combination of two or more.

[0189] There are no particular restrictions on the volume-average particle size of the core material, and it can be appropriately selected depending on the purpose, but 10 μm to 150 μm is preferred, and 40 μm to 100 μm is more preferred. If the volume-average particle diameter is less than 10 μm, there will be a large amount of fine powder in the carrier, which can reduce the magnetization per particle and cause carrier scattering. If it exceeds 150 μm, the specific surface area will decrease, which can cause toner scattering, and in full-color printing with many solid areas, the reproduction of solid areas may be particularly poor.

[0190] -Resin layer- There are no particular restrictions on the material of the resin layer, and it can be appropriately selected from known resins according to the purpose. Examples include amino resins, polyvinyl resins, polystyrene resins, polyhalogenated olefins, polyester resins, polycarbonate resins, polyethylene, polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polyhexafluoropropylene, copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, fluoropolymers such as copolymers of tetrafluoroethylene, vinylidene fluoride and monomers without fluorogroups, and silicone resins. These can be used individually or in combination of two or more.

[0191] There are no particular restrictions on the amino-based resin, and it can be appropriately selected depending on the purpose. Examples include urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. There are no particular restrictions on the polyvinyl resin, and it can be appropriately selected depending on the purpose. Examples include acrylic resin, polymethyl methacrylate, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, and polyvinyl butyral. The polystyrene-based resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include polystyrene and styrene-acrylic copolymers. The polyhalogenated olefin is not particularly limited and can be appropriately selected depending on the purpose; for example, polyvinyl chloride is one such example. There are no particular restrictions on the polyester resin, and it can be appropriately selected depending on the purpose. Examples include polyethylene terephthalate and polybutylene terephthalate.

[0192] The resin layer may contain conductive powder or the like as needed. There are no particular restrictions on the conductive powder, and it can be appropriately selected depending on the purpose. Examples include metal powder, carbon black, titanium dioxide, tin oxide, and zinc oxide. The average particle size of the conductive powder is preferably 1 μm or less. If the average particle size exceeds 1 μm, it may become difficult to control the electrical resistance.

[0193] The aforementioned resin layer can be formed by dissolving a silicone resin or the like in a solvent to prepare a coating solution, then applying the coating solution to the surface of the core material using a known coating method, drying it, and then baking it. There are no particular restrictions on the coating method, and it can be appropriately selected depending on the purpose. For example, immersion coating, spray coating, brush coating, etc., can be used. The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, and butyl cellosolve acetate. The aforementioned baking process may be carried out using an external heating method or an internal heating method, and examples include methods using a fixed electric furnace, a fluidized bed electric furnace, a rotary electric furnace, a burner furnace, etc., or methods using microwaves.

[0194] There are no particular restrictions on the resin layer content in the carrier, and it can be appropriately selected depending on the purpose, but 0.01% by mass to 5.0% by mass is preferred. If the content is less than 0.01% by mass, it may not be possible to form a uniform resin layer on the surface of the core material, and if it exceeds 5.0% by mass, the resin layer is too thick, causing fusion between carriers and reducing the uniformity of the carriers.

[0195] (Toner storage unit) In this invention, a toner storage unit refers to a unit having the function of storing toner, in which toner is stored. Examples of the toner storage unit include a toner storage container, a developer, and a process cartridge. A toner container refers to a container that holds toner. A developing unit refers to a device that has the means to store toner and develop it.

[0196] <Processing Cartridge> The process cartridge according to the present invention is formed to be detachably attached to various image forming apparatuses and comprises at least a photoreceptor that carries an electrostatic latent image and a developing means that develops the electrostatic latent image carried on the photoreceptor with the developer of the present invention to form a toner image. The process cartridge of the present invention may further comprise other means as needed. The developing means includes at least a developer storage section for containing the developer of the present invention, and a developer carrier for carrying and transporting the developer contained in the developer storage section. The developing means may further include a regulating member or the like to regulate the thickness of the carried developer.

[0197] By mounting the toner storage unit in an image forming apparatus and performing image formation, the characteristics of the toner, which are excellent in offset resistance, charge stability, stress resistance, and background stain resistance, can be utilized to provide high-definition, high-quality images over a long period of time, thereby enabling the formation of high-quality, high-definition images with long-term image stability.

[0198] (Image forming apparatus and image forming method) The image forming apparatus of the present invention comprises at least an electrostatic latent image carrier, an electrostatic latent image forming means, and a developing means, and further comprises other means as necessary. The image forming method according to the present invention includes at least an electrostatic latent image formation step and a development step, and further includes other steps as necessary. The above image forming method can be preferably performed by the above image forming apparatus. The electrostatic latent image forming step can be preferably performed by the electrostatic latent image forming means. The developing step can be preferably performed by the developing means. The other steps can be preferably performed by the other means.

[0199] The image forming apparatus of the present invention more preferably includes an electrostatic latent image carrier, an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, a developing means including toner for developing the electrostatic latent image formed on the electrostatic latent image carrier with the toner to form a toner image, a transfer means for transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and a fixing means for fixing the toner image transferred to the surface of the recording medium. The image forming method of the present invention more preferably includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier, a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier with toner to form a toner image, a transfer step of transferring the toner image formed on the electrostatic latent image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0200] In the above developing means, the toner is used. Preferably, a developer containing the toner and further containing other components such as a carrier as required may be used to form the toner image.

[0201] <Electrostatic latent image carrier> The material, structure, and size of the electrostatic latent image carrier (hereinafter also referred to as "photoconductor") are not particularly limited and can be appropriately selected from known ones. Examples of the material include inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors such as polysilane and phthalopolymethine.

[0202] <Electrostatic latent image forming means> As the electrostatic latent image forming means, there is no particular limitation as long as it is means for forming an electrostatic latent image on the electrostatic latent image carrier, and it can be appropriately selected according to the purpose. For example, there are means having at least a charging member for charging the surface of the electrostatic latent image carrier and an exposure member for imagewise exposing the surface of the electrostatic latent image carrier.

[0203] <Developing means> As the developing means, there is no particular limitation as long as it is developing means including toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a visible image, and it can be appropriately selected according to the purpose.

[0204] <Cleaning means> In the image forming apparatus of the present invention, it is preferable to have cleaning means. As described above, the toner of the present invention is excellent in cleaning property. Therefore, by applying the toner to the image forming apparatus having cleaning means, the cleaning property is improved in the following points. · By improving the spacer effect of the toner matrix, the fluidity of the toner is maintained even under stress, and the cleaning property is improved. · The amount of externally added agent (silica) released (% by mass) forms a deposited layer (dam layer) of the externally added agent in the cleaning blade nip portion by sufficiently releasing the externally added agent from the toner on the photoreceptor, thereby achieving high cleaning property.

[0205] As the cleaning means, there is no particular limitation as long as it is means for removing the toner remaining on the photoreceptor, and it can be appropriately selected according to the purpose. For example, there are magnetic brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

[0206] <Other means> As the other means, for example, there are transfer means, fixing means, charge removal means, recycling means, control means, and the like.

[0207] Next, one embodiment of a method for forming an image using the image forming apparatus of the present invention will be described with reference to Figure 1.

[0208] Figure 1 shows an example of the image forming apparatus of the present invention. The color image forming apparatus 100A shown in Figure 1 comprises a photoreceptor drum 10 (hereinafter sometimes referred to as "photoreceptor 10") as the electrostatic latent image carrier, a charging roller 20 as the charging means, an exposure device 30 as the exposure means, a developer 40 as the developing means, an intermediate transfer body 50, a cleaning device 60 as the cleaning means having a cleaning blade, and a static elimination lamp 70 as the static elimination means.

[0209] The intermediate transfer body 50 is an endless belt and is designed to be movable in the direction of the arrow by three rollers 51 positioned inside it and tensioning it. Part of the three rollers 51 also function as transfer bias rollers capable of applying a predetermined transfer bias (primary transfer bias) to the intermediate transfer body 50. A cleaning device 90 having a cleaning blade is positioned near the intermediate transfer body 50. Also positioned near the intermediate transfer body 50, facing the intermediate transfer body 50, is a transfer roller 80, which serves as the transfer means capable of applying a transfer bias for transferring a developed image (toner image) to the transfer paper P, which is a recording medium (secondary transfer). Around the intermediate transfer body 50, a corona charger 52 for imparting charge to the toner image on the intermediate transfer body 50 is positioned between the contact area between the photoreceptor 10 and the intermediate transfer body 50 and the contact area between the intermediate transfer body 50 and the transfer paper P in the rotational direction of the intermediate transfer body 50.

[0210] The black developing unit 45K, yellow developing unit 45Y, magenta developing unit 45M, and cyan developing unit 45C are arranged directly opposite each other around the photosensitive drum 10. The black developing unit 45K includes a developer container 42K, a developer supply roller 43K, and a developing roller 44K. The yellow developing unit 45Y includes a developer container 42Y, a developer supply roller 43Y, and a developing roller 44Y. The magenta developing unit 45M includes a developer container 42M, a developer supply roller 43M, and a developing roller 44M. The cyan developing unit 45C includes a developer container 42C, a developer supply roller 43C, and a developing roller 44C. The developing belt 41 is an endless belt, rotatably stretched over multiple belt rollers, with a portion of it in contact with the electrostatic latent image carrier 10.

[0211] In the color image forming apparatus 100A shown in Figure 1, for example, a charging roller 20 uniformly charges the photoreceptor drum 10. An exposure device 30 exposes the photoreceptor drum 10 in an image-like manner, forming an electrostatic latent image. The electrostatic latent image formed on the photoreceptor drum 10 is developed by supplying toner from the developer 40 to form a toner image. This toner image is transferred (primary transfer) onto an intermediate transfer body 50 by a voltage applied from a roller 51, and then transferred (secondary transfer) onto transfer paper P. As a result, a transferred image is formed on the transfer paper P. Residual toner on the photoreceptor 10 is removed by a cleaning device 60, and the charge on the photoreceptor 10 is temporarily removed by an anti-static lamp 70.

[0212] Figure 2 shows another example of the image forming apparatus of the present invention. The image forming apparatus 100B shown in Figure 1 comprises a copy device body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400. The main body 150 of the copying device has an endless belt-shaped intermediate transfer body 50 in its center. The intermediate transfer body 50 is stretched over support rollers 14, 15, and 16 and is rotatable clockwise in Figure 2. Near the support roller 15, an intermediate transfer body cleaning device 17 is positioned to remove residual toner from the intermediate transfer body 50. A tandem-type developer 120, in which four image forming means 120 for yellow, cyan, magenta, and black are arranged opposite each other along the transport direction of the intermediate transfer body 50 stretched over by the support rollers 14 and 15, is positioned. Near the tandem-type developer 120, an exposure device 21, which is the exposure member, is positioned. On the side of the intermediate transfer body 50 opposite to the side where the tandem-type developer 120 is positioned, a secondary transfer device 22 is positioned. In the secondary transfer device 22, an endless belt, the secondary transfer belt 24, is stretched over a pair of rollers 23, and the transfer paper and the intermediate transfer body 50 conveyed on the secondary transfer belt 24 can come into contact with each other. A fixing device 25, which is the fixing means, is located near the secondary transfer device 22. The fixing device 25 comprises a fixing belt 26, which is an endless belt, and a pressure roller 27 that is positioned under pressure from the fixing belt. In the tandem image forming apparatus, a sheet reversing device 28 is located near the secondary transfer device 22 and the fixing device 25 to reverse the transfer paper in order to form an image on both sides of the transfer paper.

[0213] Next, the formation of a full-color image (color copy) using the tandem-type developing unit 120 will be described. Specifically, first, the original document is placed on the document glass 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened and the original document is placed on the contact glass 32 of the scanner 300, and then the automatic document feeder 400 is closed.

[0214] When the start switch (not shown) is pressed, if a document is placed in the automatic document transporter 400, the document is transported and moved onto the contact glass 32 before the scanner 300 is activated. If a document is placed on the contact glass 32, the scanner 300 is activated immediately. The first travel body 33 and the second travel body 34 then move. At this time, the first travel body 33 illuminates the document with light from the light source, and the mirror on the second travel body 34 reflects the reflected light from the document surface. This light is then received by the reading sensor 36 through the imaging lens 35, and the color document (color image) is read and converted into black, yellow, magenta, and cyan image information.

[0215] The image information for black, yellow, magenta, and cyan is then transmitted to each image forming means 120 (image forming means for black, image forming means for yellow, image forming means for magenta, and image forming means for cyan) in the tandem developer 120. Then, the toner images for black, yellow, magenta, and cyan are formed in each image forming means. That is, as shown in Figure 3, each image forming means 120 (image forming means for black, image forming means for yellow, image forming means for magenta, and image forming means for cyan) in the tandem developer 120 consists of an electrostatic latent image carrier 10 (electrostatic latent image carrier 10K for black, electrostatic latent image carrier 10Y for yellow, electrostatic latent image carrier 10M for magenta, and electrostatic latent image carrier 10C for cyan), a charging device 20 which is the charging means for uniformly charging the electrostatic latent image carrier 10, and each color image information The system includes an exposure apparatus that exposes the electrostatic latent image carrier to each color image (L in Figure 3) and forms an electrostatic latent image on the electrostatic latent image carrier corresponding to each color image; a developing apparatus 61 which is the developing means that develops the electrostatic latent image using each color toner (black toner, yellow toner, magenta toner, and cyan toner) to form a toner image using each color toner; a transfer charger 62 for transferring the toner image onto an intermediate transfer body 50; a cleaning apparatus 63; and a static eliminator 64. Each image forming means 120 is capable of forming each monochrome image (black image, yellow image, magenta image, and cyan image) based on the image information of each color. The black image, yellow image, magenta image, and cyan image thus formed are sequentially transferred (primary transfer) onto an intermediate transfer body 50 that is rotated by support rollers 14, 15, and 16. The black image formed on the black electrostatic latent image carrier 10K, the yellow image formed on the yellow electrostatic latent image carrier 10Y, the magenta image formed on the magenta electrostatic latent image carrier 10M, and the cyan image formed on the cyan electrostatic latent image carrier 10C are then superimposed on the intermediate transfer body 50 to form a composite color image (color transfer image).

[0216] Meanwhile, in the paper feed table 200, one of the paper feed rollers 142 is selectively rotated to feed a sheet (recording paper) from one of the multi-stage paper feed cassettes 144 in the paper bank 143. The sheets are separated one by one by the separation roller 145 and sent to the paper feed path 146, transported by the transport roller 147 and guided to the paper feed path 148 in the copier body 150, where they are stopped by the registration roller 49. Alternatively, the paper feed roller 142 is rotated to feed a sheet (recording paper) from the manual feed tray 54, separate it one by one by the separation roller 52 and put it into the manual feed path 53, where it is stopped by the registration roller 49. The registration roller 49 is generally used in a grounded state, but it may also be used with a bias applied to remove paper dust from the sheets. Then, the register roller 49 is rotated in time with the composite color image (color transfer image) synthesized on the intermediate transfer body 50, and a sheet (recording paper) is fed between the intermediate transfer body 50 and the secondary transfer device 22, and the secondary transfer device 22 transfers the composite color image (color transfer image) onto the sheet (recording paper) (secondary transfer). In this way, a color image is transferred and formed on the sheet (recording paper). After image transfer, any residual toner on the intermediate transfer body 50 is cleaned by the intermediate transfer body cleaning device 17.

[0217] The sheet (recording paper) on which the color image has been transferred and formed is transported by the secondary transfer device 22 and sent to the fixing device 25, where the composite color image (color transfer image) is fixed onto the sheet (recording paper) by heat and pressure. After that, the sheet (recording paper) is switched by the switching claw 55 and discharged by the discharge roller 56 and stacked on the paper output tray 57. Alternatively, the sheet is switched by the switching claw 55 and inverted by the sheet inversion device 28 and guided back to the transfer position, where an image is recorded on the back side as well, before being discharged by the discharge roller 56 and stacked on the paper output tray 57.

[0218] FIG. 4 shows an example of a process cartridge according to the present invention. The process cartridge 110 includes a photoreceptor drum 10, a corona charger 52, a developing device 40, a transfer roller 80, and a cleaning device 90.

Example

[0219] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples. In the following description, "parts" and "%" represent "parts by mass" and "%", respectively.

[0220] <Production Example 1 of Resin Fine Particle Dispersion Liquid> Into a reaction vessel equipped with a stirrer, a heating and cooling device, and a thermometer, 3,710 parts by mass of water and 200 parts by mass of polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ammonium (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Aqualon KH-1025) were charged and stirred at 200 revolutions per minute for homogenization. Then, after heating to a temperature of 75°C in the system, 90 parts by mass of a 10 mass% aqueous ammonium persulfate solution was added, and a mixed solution consisting of 450 parts by mass of styrene, 250 parts by mass of butyl acrylate, and 300 parts by mass of methacrylic acid was dropped over 4 hours. After the dropping, aging at 75°C for 4 hours gave a dispersion liquid 1 of resin fine particles (A1) composed of a core resin (a1) in which the styrene, the butyl acrylate, the methacrylic acid, and the polyoxyethylene-1-(allyloxymethyl) alkyl ether sulfate ammonium were copolymerized. When the volume average particle diameter of the resin fine particles A1 in the [dispersion liquid 1] was measured by the dynamic light scattering method (light scattering electrophoresis apparatus: manufactured by Otsuka Electronics Co., Ltd., ELS-8000), it was 15 nm. Also, a part of [dispersion liquid 1] was dried to isolate the core resin (a1), and when the glass transition temperature (Tg) was measured, it was 75°C, and when the acid value was measured, it was 195 mgKOH / g.

[0221] <Production Example 2 of Resin Fine Particle Dispersion Liquid> In a reaction vessel equipped with a stirrer, a heating and cooling device, and a thermometer, 667 parts by mass of the [dispersion 1], 248 parts by mass of water, and 0.267 parts by mass of tert-butyl hydroperoxide (manufactured by NOF Corporation, Perbutyl H) were added and heated until the system temperature reached 70°C. Then, a mixture consisting of 43.3 parts by mass of styrene, 23.3 parts by mass of butyl acrylate, and 18.0 parts by mass of a 1% by mass aqueous solution of ascorbic acid was added dropwise over 2 hours. Subsequently, by aging at 70°C for 4 hours, a dispersion 2 of resin fine particles (A2) was obtained in which the core resin (a1) and the shell resin (a2), which is a polymer copolymerized of the tertiary butyl hydroperoxide, the styrene, and the butyl acrylate, were contained as constituent components within the same particle. The volume-average particle size of the resin fine particles (A2) in the [dispersion 2] was measured in the same manner as for the resin fine particles (A1) and was found to be 17.3 nm. Furthermore, the [dispersion 2] was neutralized with a 10% by mass aqueous ammonia solution to a pH of 9.0, and the precipitate obtained by centrifugation was allowed to dry to isolate the shell resin (a2). The glass transition temperature (Tg) was measured in the same manner as for the core resin (a1) and was found to be 61°C. Furthermore, it was confirmed that the resin fine particles (A2) in the aforementioned [dispersion 2] contain both the core resin (a1) and the shell resin (a2) as constituent components within the same particle, as described below. Specifically, a gel was prepared by adding 2 parts by mass of gelatin (Cook Gelatin, manufactured by Morinaga Milk Industry Co., Ltd.) to 15 parts by mass of water at 95°C to 100°C, air-cooling to 40°C to obtain an aqueous gelatin solution, mixing the aforementioned [dispersion 2] in a 1:1 mass ratio, and then cooling at 10°C for 1 hour. The aforementioned gel was prepared into 80 nm thick sections using an ultramicrotome (Ultramicrotome UC7, FC7, Leica Microsystems) while maintaining a temperature of -80°C. After vapor-phase staining with a 2% by mass ruthenium tetroxide aqueous solution for 5 minutes, the sections were observed with a transmission electron microscope (Hitachi Technologies, Ltd., H-7100) to confirm that they were core-shell structured resin nanoparticles.

[0222] <Example 3 of manufacturing resin particle dispersion> In a reaction vessel equipped with a stirrer, a heating and cooling device, and a thermometer, 3,810 parts by mass of water and 100 parts by mass of polyoxyethylene-1-(allyloxymethyl)alkyl ether sulfate ammonium (Aqualon KH-1025, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were charged and stirred at 200 rpm until homogenized. After heating to a system temperature of 75°C, 90 parts by mass of a 10% by mass aqueous solution of ammonium persulfate was added, and a mixture consisting of 400 parts by mass of styrene, 300 parts by mass of butyl acrylate, and 300 parts by mass of methacrylic acid was added dropwise over 4 hours. After dropwise addition, the mixture was aged at 75°C for 4 hours to obtain a dispersion 3 of resin fine particles (B1) consisting of a core resin (b1) which is a polymer copolymerized of styrene, butyl acrylate, methacrylic acid, and polyoxyethylene-1-(allyloxymethyl)alkyl ether sulfate ammonium. The volume-average particle size of the resin fine particles (B1) in the [dispersion 3] was measured using dynamic light scattering (light scattering electrophoresis apparatus: Otsuka Electronics Co., Ltd., ELS-8000) and found to be 45 nm. Furthermore, a portion of the [dispersion 3] was dried to isolate the core resin (b1), and its glass transition temperature (Tg) was measured to be 65°C, and its acid value was measured to be 195 mg KOH / g.

[0223] <Example 4 of manufacturing resin particle dispersion> In a reaction vessel equipped with a stirrer, a heating and cooling device, and a thermometer, 667 parts by mass of the [dispersion 3], 248 parts by mass of water, and 0.267 parts by mass of tert-butyl hydroperoxide (manufactured by NOF Corporation, Perbutyl H) were added, and the mixture was heated until the system temperature reached 70°C. Then, a mixture consisting of 43.3 parts by mass of styrene, 23.3 parts by mass of butyl acrylate, and 18.0 parts by mass of a 1% by mass aqueous solution of ascorbic acid was added dropwise over 2 hours. Subsequently, by aging at 70°C for 4 hours, a dispersion 4 of resin fine particles (B2) was obtained in which the core resin (b1) and the shell resin (b2), which is a polymer copolymerized of tertiary butyl hydroperoxide, styrene, and butyl acrylate, were contained as constituent components within the same particle. The volume-average particle size of the resin fine particles (B2) in the [dispersion 4] was measured in the same manner as for the resin fine particles (B1) and was found to be 51.5 nm. Furthermore, the [dispersion 4] was neutralized with a 10% by mass aqueous ammonia solution to a pH of 9.0, and the precipitate obtained by centrifugation was allowed to dry to isolate the shell resin (b2). The glass transition temperature (Tg) was measured in the same manner as for the core resin (b1) and was found to be 55°C. Furthermore, when the structure of the resin microparticles (B2) in [Dispersion 4] was examined using the same method as for [Dispersion 2], it was confirmed that they were resin microparticles with a core-shell structure.

[0224] <Synthesis of amorphous polyester resin> In a reaction vessel equipped with a condenser, stirrer, heating / cooling device, thermometer, and nitrogen inlet tube, 425 parts by mass of bisphenol A·PO2 molar adduct, 100 parts by mass of propylene glycol, 634 parts by mass of terephthalic acid·propylene glycol 2 molar adduct, and 0.5 parts by mass of titanium diisopropoxybistriethanolaminate as a condensation catalyst were added and the mixture was reacted at 230°C for 12 hours. Next, the mixture was reacted under reduced pressure of 10-15 mmHg and cooled to 180°C. Then, 30 parts by mass of trimellitic anhydride were added and the mixture was reacted at 180°C for 1 hour, after which it was cooled to room temperature to obtain an amorphous polyester resin. The glass transition temperature (Tg) of the aforementioned amorphous polyester resin was 42°C, the number-average molecular weight (Mn) was 2,400, the weight-average molecular weight (Mw) was 5,400, the hydroxyl value was 32 mgKOH / g, and the acid value was 18 mgKOH / g.

[0225] <Example of manufacturing a colorant dispersion> In a reaction vessel equipped with a condenser, stirrer, heating and cooling device, thermometer, and nitrogen inlet tube, 557 parts by mass of propylene glycol, 569 parts by mass of dimethyl terephthalate, 184 parts by mass of adipic acid, and 3 parts by mass of tetrabutoxytinate as a condensation catalyst were added, and the mixture was reacted at 180°C under a nitrogen stream for 8 hours while distilling off the methanol produced. Next, the temperature was gradually increased to 230°C, and the reaction was carried out for 4 hours under a nitrogen atmosphere while distilling off the generated propylene glycol and water. After that, the reaction was carried out for 1 hour under reduced pressure of 0.007 MPa to 0.026 MPa. Next, the mixture was cooled to 180°C, 121 parts by mass of trimellitic anhydride were added, and the mixture was reacted under atmospheric pressure and in a sealed state for 2 hours. After that, the mixture was reacted at 220°C under atmospheric pressure until the softening point reached 180°C to obtain a polyester resin (number average molecular weight (Mn) = 8,500). 20 parts by mass of copper phthalocyanine, 4 parts by mass of dispersant (Solspers 28000, manufactured by Abyssia), 20 parts by mass of the aforementioned [polyester resin], and 56 parts by mass of ethyl acetate were added to a beaker and stirred. Then, the copper phthalocyanine was finely dispersed using a bead mill to obtain a [coloring agent dispersion]. The volume-average particle size of the obtained [coloring agent dispersion] was 0.2 μm.

[0226] <Example of manufacturing a mold release agent dispersion> In a pressure-resistant reaction vessel equipped with a stirrer, heating / cooling device, thermometer, and dropping cylinder, 454 parts by mass of xylene and 150 parts by mass of low molecular weight polyethylene (Sanyo Chemical Industries, Ltd., Sanwax LEL-400) were added. After purging with nitrogen, the temperature was raised to 170°C under stirring, and a mixed solution of 595 parts by mass of styrene, 255 parts by mass of methyl methacrylate, 34 parts by mass of di-t-butyl peroxyhexahydroterephthalate, and 119 parts by mass of xylene was added dropwise over 3 hours, and the mixture was held for a further 30 minutes. Next, xylene was removed under reduced pressure of 0.039 MPa to obtain [modified wax]. The SP value of the graft chain of the aforementioned [modified wax] is 10.35 (cal / cm²). 3 ) 1 / 2 The number-average molecular weight (Mn) was 1,900, the weight-average molecular weight (Mw) was 5,200, and the glass transition temperature (Tg) was 57°C. Next, 10 parts by mass of paraffin wax (HNP-9, manufactured by Nippon Seiro Co., Ltd.), 1 part by mass of the [modified wax], and 33 parts by mass of ethyl acetate were added to a reaction vessel equipped with a condenser, stirrer, heating and cooling device, and thermometer. The mixture was stirred at 78°C for 30 minutes, and then cooled to 30°C over 1 hour to crystallize the paraffin wax into fine particles. The mixture was then wet-milled using UltraViscomil (manufactured by AIMEX) to obtain a [release agent dispersion]. The volume-average particle size of the [release agent dispersion] was 0.25 μm.

[0227] <Examples of reactive prepolymer manufacturing> In a reaction vessel equipped with a condenser, a stirrer, and nitrogen inlet tube, 3-methyl-1,5-pentanediol, isophthalic acid, adipic acid, and trimellitic anhydride were added together with titanium tetraisopropoxide (1,000 ppm relative to the resin component) such that the molar ratio of hydroxyl groups to carboxyl groups (OH / COOH) was 1.5, the diol component consisted of 100 mol% 3-methyl-1,5-pentanediol, the dicarboxylic acid component consisted of 40 mol% isophthalic acid and 60 mol% adipic acid, and the amount of trimellitic anhydride in the total monomer was 1 mol%. The temperature was then raised to 200°C over approximately 4 hours, and then to 230°C over 2 hours, and the reaction continued until all the effluent was gone. Subsequently, the reaction was carried out under reduced pressure of 10 mmHg to 15 mmHg for 5 hours to obtain [intermediate polyester C-1]. Next, [intermediate polyester C-1] and isophorone diisocyanate (IPDI) were added to a reaction vessel equipped with a condenser, stirrer, and nitrogen inlet tube in a molar ratio (isocyanate groups of IPDI / hydroxyl groups of intermediate polyester) of 2.0. After diluting with ethyl acetate to a 50% ethyl acetate solution, the mixture was reacted at 100°C for 5 hours to obtain a [reactive prepolymer].

[0228] (Example 1) <Preparation of the aqueous phase> In a beaker, 165 parts by mass of deionized water, 10 parts by mass of [dispersion 1], 5 parts by mass of [dispersion 2], 1 part by mass of sodium carboxymethylcellulose, 26 parts by mass of sodium dodecyldiphenyl ether disulfonate (manufactured by Sanyo Chemical Industries, Ltd., Eleminor MON-7), and 15 parts by mass of ethyl acetate were added and mixed to obtain the [aqueous phase].

[0229] <Preparation of the oil phase> After adding and mixing 71 parts by mass of the aforementioned [amorphous polyester resin], 40 parts by mass of the [coloring agent dispersion], 39 parts by mass of the [mold release agent dispersion], and 54 parts by mass of ethyl acetate, 18 parts by mass of the aforementioned [reactive prepolymer] and 0.3 parts by mass of isophorone diamine as a curing agent were added and mixed to obtain the [oil phase].

[0230] <Composite process> The entire amount of the [aqueous phase] was added to the [oil phase] and stirred for 2 minutes in a TK autohomogenizer to obtain a mixture. The obtained mixture was transferred to a reaction vessel equipped with a stirrer and a thermometer, and a compounding process was carried out at 50°C until the concentration of ethyl acetate was 0.5% by mass or less to obtain an aqueous dispersion of composite particles. When the shape of the particles contained in the obtained aqueous dispersion of composite particles was observed using a scanning electron microscope: SU-8230 (manufactured by Hitachi High-Technologies Corporation), toner matrix particles coated with resin fine particles were observed. Next, sodium hydroxide was added to the aqueous dispersion of composite particles so that its pH became 12. Then, as a reslurrying step, the mixture was stirred for 1 hour using a three-one motor and centrifugal filtration was performed, followed by the addition of deionized water to form a reslurry. After repeating the reslurrying step several times, the mixture was filtered by suction using a membrane filter (hereinafter referred to as the "washing and filtration step"), dried at 40°C for 18 hours, and the volatile content was reduced to 0.5% by mass or less to obtain a toner precursor.

[0231] <External Additive Processing Process> To 100 parts by mass of the [toner precursor], 1.5 parts by mass of hydrophobic silica particles (volume average particle diameter: 50 nm), 1.0 part of hydrophobic titanium oxide (volume average particle diameter: 20 nm), and 0.12 parts by mass of zinc stearate particles were added as external additives and mixed using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) to obtain [toner 1]. The [coverage rate of toner matrix particles by resin fine particles] and the [amount of zinc released from zinc stearate particles] of the obtained [toner 1] were measured using the following method. The coverage rate was 70%, and the amount of zinc released was 0.010% by mass. Furthermore, the volume-average particle size of the zinc stearate particles was measured by the following method and found to be 10 μm.

[0232] <Measurement of the coating rate of toner matrix particles by resin microparticles> As a method for measuring the coating rate, after performing an additive removal treatment using ultrasound to remove as much of the additive as possible, the resin fine particles coating the toner matrix particles were observed using a scanning electron microscope (SEM). As part of the treatment to release the external additive, the external additive was released from the toner matrix particles by the following [1]~[2] and [ultrasonic conditions]. [1] 50 ml of a 5% by mass surfactant solution (product name: Neugen ET-165, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a dispersion solution and 3 g of toner were mixed in a 100 ml screw tube, and after being gently moved up and down and left and right, the mixture was stirred for 30 minutes using a ball mill to allow the toner to blend with the dispersion solution. [2] Subsequently, ultrasonic energy was applied using an ultrasonic homogenizer (product name: homogenizer, model VCX750, CV33, manufactured by SONICS&MATERIALS Co., Ltd.) under the following [ultrasonic conditions]. [Ultrasound conditions] • Vibration time: 60 minutes continuous ·Amplitude: 40W ·Vibration start temperature: 23±1.5℃ ·Temperature during vibration: 23±1.5℃ [3] (1) The dispersion is filtered by suction using filter paper (product name: Qualitative filter paper (No. 2, 110 mm), manufactured by Advantec Toyo Co., Ltd.), washed twice again with deionized water and filtered to remove the freed additives, and then the toner is dried. (2) Scanning electron microscope (SEM) images are taken of the toner obtained in (1) using a scanning electron microscope (SEM). When taking images, an SEM image is taken from a direction perpendicular to the direction of the image taken, and a total of 20 or more SEM images are taken. First, Si-containing additives and fillers are detected by observing the backscattered electron image. (3) The image from (1) is binarized using image processing software (ImageJ) to remove the external additive and filler. Next, a secondary electron image was observed at the same position as in (1). Since resin nanoparticles were not observed in the backscattered electron image but only in the secondary electron image, the image was compared with the image obtained in (3), and the nanoparticles present in the parts other than the residual additive and filler (the parts other than those excluded in (3)) were identified as resin nanoparticles and observed.

[0233] [Shooting conditions] • Scanning electron microscope: SU-8230 (manufactured by Hitachi High-Technologies Corporation) • Magnification: 35,000x • Image type: SE(L): Secondary electrons, BSE(backscattered electrons) • Acceleration voltage: 2.0kV ·Acceleration current: 1.0μA • Probe current: Normal • Focus mode: UHR WD: 8.0mm

[0234] <Measurement of the amount of zinc released from zinc stearate particles> 10 g of polyoxyalkylene alkyl ether (Neugen ET-165, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 300 mL of pure water were placed in a 500 mL beaker and dispersed by sonication for 1 hour to obtain [Dispersion A]. Then, [Dispersion A] was transferred to a 2 L volumetric flask, diluted to the final volume, and dissolved by sonication for 1 hour to obtain [Dispersion B] containing 0.5% polyoxyalkylene alkyl ether. 50 mL of the aforementioned [Dispersion B] was poured into a 110 mL screw-cap tube, and 3.75 g of the sample toner (referred to as [Sample Toner Before Processing]) was added. The mixture was stirred for 30 to 90 minutes, using the lowest possible rotation speed to avoid creating bubbles, until the screw-cap tube was thoroughly mixed with [Dispersion B] to obtain [Dispersion C]. Using an ultrasonic homogenizer (VCX750, manufactured by SONICS&Materials, Inc., 20kHz, 750 watts), the vibrating part was inserted 2.5 cm into the [dispersion C], and ultrasonic vibration was applied for 1 minute at 40% output energy to obtain [dispersion D].

[0235] The aforementioned [dispersion D] was placed in a 50 mL centrifuge tube and centrifuged at 2,000 rpm for 2 minutes to obtain the supernatant and precipitate. The obtained precipitate was washed with 60 mL of pure water and poured into a separator, and the washing water was removed by suction filtration. The filtered precipitate and 60 mL of pure water were placed in a cup, stirred slowly five times with the handle of a spatula, and then the washing water was removed by suction filtration. The toner remaining on the filter paper was collected and dried in a 40°C constant temperature bath for 8 hours. 3 g of the dried toner was pelletized to a diameter of 3 mm and a thickness of 2 mm using an automatic pressure molding machine (T-BRB-32, manufactured by Maekawa; load 6.0 t, pressurization time 60 seconds) to obtain the processed sample toner. Similarly, the toner was pelletized to a diameter of 3 mm and a thickness of 2 mm to obtain a sample toner before processing. Using an X-ray fluorescence spectrometer (ZSX-100e, manufactured by Rigaku Corporation), the zinc content (mass%) in the [processed sample toner] and the [unprocessed sample toner] was measured, and the amount of free zinc (mass%) was calculated based on the following formula 1. The calibration curve used was prepared in advance using sample toners with zinc content of 0.1 parts, 1 part, and 1.8 parts per 100 parts of toner. Free zinc amount (mass%) = (Zinc content of [sample toner before treatment] (mass%) - Zinc content of [sample toner after treatment] (mass%)) / Zinc content of [sample toner before treatment] (mass%) × 100 ... (Equation 1)

[0236] <Measurement of volume-average particle diameter of zinc stearate particles> A small amount of toner that had undergone the above external additive treatment was collected using a Henschel mixer, and a scanning electron microscope (SEM) image of the zinc stearate particles in the toner was taken under the following imaging conditions. [Shooting conditions] • Scanning electron microscope: SU-8230 (manufactured by Hitachi High-Technologies Corporation) • Magnification: 35,000x • Image type: SE(L): Secondary electrons, BSE(backscattered electrons) • Acceleration voltage: 2.0kV ·Acceleration current: 1.0μA • Probe current: Normal • Focus mode: UHR WD: 8.0mm Using the image analysis software ImageJ, the longest length of randomly selected zinc stearate particles was measured from the captured SEM images (number of particles measured: 100 to 200), and the volume-average particle diameter was calculated. For the calculation of the volume-average particle diameter, 5 lots of zinc stearate particles were measured, and if the measurement results for 80% or more of these lots were between 3 μm and 20 μm, the numerical range for the volume-average particle diameter of zinc stearate particles in this invention was considered to be satisfied.

[0237] (Example 2) In Example 1, toner was manufactured in the same manner as in Example 1, except that 10 parts by mass of [Dispersion 1] was changed to 7.5 parts by mass of [Dispersion 1] and 5 parts by mass of [Dispersion 2] was changed to 7.5 parts by mass of [Dispersion 2]. [Toner 2] was obtained. When the obtained [Toner 2] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of toner matrix particles by resin fine particles] and the [amount of zinc released from zinc stearate particles] were found to be 70% and 0.014% by mass, respectively.

[0238] (Example 3) In Example 1, toner was manufactured in the same manner as in Example 1, except that 10 parts by mass of [Dispersion 1] was changed to 5 parts by mass of [Dispersion 1] and 5 parts by mass of [Dispersion 2] was changed to 10 parts by mass of [Dispersion 2], and [Toner 3] was obtained. When the obtained [Toner 3] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of the toner matrix particles by resin fine particles] and the [amount of zinc released from the zinc stearate particles] were found to be 50% and 0.012% by mass, respectively.

[0239] (Example 4) In Example 3, the toner was manufactured in the same manner as in Example 3, except that zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 6 μm), and [Toner 4] was obtained. When the obtained [Toner 4] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of the toner matrix particles by resin fine particles] and the [amount of zinc released from the zinc stearate particles] were found to be 50% and 0.008% by mass, respectively.

[0240] (Example 5) In Example 3, the toner was manufactured in the same manner as in Example 3, except that zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 3 μm), and [Toner 5] was obtained. When the obtained [Toner 5] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of the toner matrix particles by resin fine particles] and the [amount of zinc released from the zinc stearate particles] were found to be 50% and 0.005% by mass, respectively.

[0241] (Example 6) In Example 3, the toner was manufactured in the same manner as in Example 3, except that zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 14 μm), and [Toner 6] was obtained. When the obtained [Toner 6] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of the toner matrix particles by resin fine particles] and the [amount of zinc released from the zinc stearate particles] were found to be 50% and 0.017% by mass, respectively.

[0242] (Example 7) In Example 3, the toner was manufactured in the same manner as in Example 3, except that zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 20 μm), and [Toner 7] was obtained. When the obtained [Toner 7] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of the toner matrix particles by resin fine particles] and the [amount of zinc released from the zinc stearate particles] were found to be 50% and 0.020% by mass, respectively.

[0243] (Comparative Example 1) In Example 1, toner was manufactured in the same manner as in Example 1, except that 10 parts by mass of [Dispersion 1] was replaced with 10 parts by mass of [Dispersion 3], 5 parts by mass of [Dispersion 2] was replaced with 5 parts by mass of [Dispersion 4], and zinc stearate particles (volume average particle size: 10 μm) as an external additive were replaced with zinc stearate particles (volume average particle size: 1.5 μm). [Toner 8] was obtained. When the obtained [Toner 8] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of the toner matrix particles by resin fine particles] and the [amount of zinc released from the zinc stearate particles] were found to be 80% and 0.004% by mass, respectively.

[0244] (Comparative Example 2) In Comparative Example 1, the toner was manufactured in the same manner as in Comparative Example 1, except that zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 25 μm), and [Toner 9] was obtained. When the obtained [toner 9] was measured in the same manner as for [toner 1] in Example 1, the [coverage rate of toner matrix particles by resin fine particles] and the [amount of zinc released from zinc stearate particles] were found to be 80% and 0.024% by mass, respectively.

[0245] (Comparative Example 3) In Example 1, toner was manufactured in the same manner as in Example 1, except that 10 parts by mass of [Dispersion 1] was changed to 3.75 parts by mass of [Dispersion 3], 5 parts by mass of [Dispersion 2] was changed to 11.25 parts by mass of [Dispersion 4], and zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 3 μm). [Toner 10] was obtained. When the obtained [Toner 10] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of toner matrix particles by resin fine particles] and the [amount of zinc released from zinc stearate particles] were found to be 20% and 0.003% by mass, respectively.

[0246] (Comparative Example 4) In Comparative Example 3, the toner was manufactured in the same manner as in Comparative Example 3, except that zinc stearate particles (volume average particle size: 3 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 20 μm), and [Toner 11] was obtained. When the obtained [toner 11] was measured in the same manner as for [toner 1] in Example 1, the [coverage rate of toner matrix particles by resin fine particles] and the [amount of zinc released in zinc stearate particles] were found to be 20% and 0.016% by mass, respectively.

[0247] (Comparative Example 5) In Comparative Example 3, the toner was manufactured in the same manner as in Comparative Example 3, except that the zinc stearate particles (volume average particle size: 3 μm) used as an external additive were changed to zinc stearate particles (volume average particle size: 25 μm), and [Toner 12] was obtained. When the obtained [Toner 12] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of the toner matrix particles by resin fine particles] and the [amount of zinc released from the zinc stearate particles] were found to be 20% and 0.022% by mass, respectively.

[0248] (Comparative Example 6) In Example 3, the toner was manufactured in the same manner as in Example 3, except that zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 1.5 μm), and [Toner 13] was obtained. When the obtained [Toner 13] was measured in the same manner as for [Toner 1] in Example 1, the [coverage rate of toner matrix particles by resin fine particles] and the [amount of zinc released from zinc stearate particles] were found to be 50% and 0.006% by mass, respectively.

[0249] (Comparative Example 7) In Example 3, the toner was manufactured in the same manner as in Example 3, except that zinc stearate particles (volume average particle size: 10 μm) as an external additive were changed to zinc stearate particles (volume average particle size: 25 μm), and [Toner 14] was obtained. When the obtained [toner 14] was measured in the same manner as for [toner 1] in Example 1, the [coverage rate of toner matrix particles by resin fine particles] and the [amount of zinc released from toner matrix particles into zinc stearate particles] were found to be 50% and 0.021% by mass, respectively.

[0250] The "heat resistance to storage" and "cleaning properties" of the [Toner 1] to [Toner 14] obtained in Examples 1 to 7 and Comparative Examples 1 to 7, or each developer containing them, were evaluated. The results are shown in Tables 1 and 2 below.

[0251] <Heat-resistant storage stability> Each 50 mL glass container was filled with 10 g of toner, and the container was tapped thoroughly until there was no change in the apparent density of the toner, and then the container was sealed. The toner was left in a 50°C constant temperature bath for 24 hours, then cooled to 24°C, and the penetration rate was measured by a penetration test (JIS K2235-1991), and the "heat resistance to storage" was evaluated based on the evaluation criteria below. Furthermore, a higher degree of penetration indicates better heat resistance and storage properties. In the evaluation criteria below, a rating of "△" or higher indicates a level that is practical for use. -Evaluation Criteria- ◎: Needle penetration depth of 25mm or more ○: Needle penetration depth of 20mm or more but less than 25mm △: Needle penetration depth is 15mm or more but less than 20mm ×: Needle penetration less than 15mm

[0252] <Cleaning properties> A developer containing each toner was loaded into a digital full-color multifunction printer (device name: Imagio MP C5000, manufactured by Ricoh Co., Ltd.), and the toner was deposited onto MyPaper (A4 size, manufactured by Ricoh Co., Ltd.) as a recording medium at a concentration of 1.0 mg / cm². 2 Multiple copies of a solid image were printed under the specified conditions. Initial prints were taken when 1,000 copies were made using the aforementioned digital full-color multifunction printer, and prints taken after 100,000 copies were taken over time. In each case, the toner remaining on the photoreceptor after the cleaning process was transferred to blank paper using Scotch tape (manufactured by Sumitomo 3M), and the reflectance density was measured using a reflectance densitometer (device name: RD514, manufactured by Gretag Macbeth). The "cleanability" was then evaluated based on the following evaluation criteria. -Evaluation Criteria- ◎: Difference in reflectance between initial and time-dependent periods is less than 0.01 ○: The difference in reflectance between the initial state and over time is 0.01 or more and less than 0.025. △: The difference in reflectance between the initial state and over time is between 0.025 and less than 0.05. ×: The difference in reflectance between the initial state and over time is 0.05 or more.

[0253] [Table 1]

[0254] [Table 2]

[0255] In Examples 1 to 7, the evaluation results for both heat resistance and cleanability were all good. In contrast, in Comparative Examples 1 and 6, the average particle size of the zinc stearate particles was less than 3 μm, which reduced the amount of zinc released from the zinc stearate particles, resulting in insufficient coating effect on the photoreceptor and poor cleaning performance. In Comparative Examples 2 and 7, the average particle size of the zinc stearate particles was greater than 20 μm, which increased the number of zinc stearate particles captured by the cleaning blade, resulting in insufficient coating effect on the photoreceptor and poor cleaning performance. In Comparative Examples 3 and 4, the coating rate of the toner matrix particles by resin microparticles was less than 30%, resulting in reduced strength of the toner matrix particles and poor heat resistance during storage. In Comparative Example 5, the coating rate of the toner matrix particles by resin microparticles was less than 30%, resulting in poor heat resistance and storage performance. Additionally, the average particle size of the zinc stearate particles was less than 3 μm, leading to a decrease in the amount of released zinc and a deterioration in cleaning performance.

[0256] Examples of embodiments of the present invention include the following: <1> A toner comprising toner matrix particles containing at least a binder resin, resin fine particles coating the toner matrix particles, and zinc stearate particles as an external additive, The coating rate of the toner matrix particles by the resin fine particles is 30% or more and 70% or less. The toner is characterized in that the volume-average particle diameter of the zinc stearate particles is 3 μm or more and 20 μm or less. <2> The volume-average particle diameter of the zinc stearate particles is 5 μm or more and 15 μm or less. <1> This is the toner described in [the document]. <3> The amount of zinc released from the toner in the zinc stearate particles is 0.005% by mass or more, <1> from <2> It is the toner described in one of the following lists. <4> The coating rate of the toner matrix particles by the resin fine particles is 40% or more and 60% or less. <1> from <3> It is the toner described in one of the following lists. <5> The aforementioned <1> from <4> This developer is characterized by containing the toner described in any of the following. <6> The aforementioned <1> from <4> This is a toner storage unit containing the toner described in one of the following. <7> Electrostatic latent image carrier, An electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, The aforementioned <1> from <4> Toner or the above <5> A developing means that uses the developer described above to develop the electrostatic latent image and form a visible image, A transfer means for transferring the visible image onto a recording medium, The image forming apparatus is characterized by having fixing means for fixing the transferred image transferred onto the recording medium. <8> An electrostatic latent image formation step in which an electrostatic latent image is formed on an electrostatic latent image carrier, The aforementioned <1> from <4> Toner or the above <5> A developing step in which the electrostatic latent image is developed using the developer described above to form a visible image, A transfer step of transferring the visible image onto a recording medium, The image forming method is characterized by comprising a fixing step of fixing the transferred image onto the recording medium.

[0257] The aforementioned <1> from <4> Toner or the above <5> The developer described above, <6> The toner storage unit described above, <7> The image forming apparatus described above, and the <8> The image forming method described above can solve the aforementioned problems of the conventional method and achieve the objectives of the present invention. [Prior art documents] [Patent Documents]

[0258] [Patent Document 1] Japanese Patent Publication No. 2002-284881 [Patent Document 2] Japanese Patent Publication No. 2019-099809 [Patent Document 3] Japanese Patent Publication No. 2019-143128 [Patent Document 4] Japanese Patent Publication No. 2007-233030

Claims

1. A toner comprising toner matrix particles containing at least a binder resin, resin fine particles coating the toner matrix particles, and zinc stearate particles as an external additive, The coating rate of the toner matrix particles by the resin fine particles is 30% or more and 70% or less. The volume-average particle diameter of the zinc stearate particles is 3 μm or more and 20 μm or less. The aforementioned binder resin contains polyester resin, The toner is characterized by containing a styrene-(meth)acrylic acid ester copolymer.

2. The toner according to claim 1, wherein the volume-average particle diameter of the zinc stearate particles is 5 μm or more and 15 μm or less.

3. The toner according to any one of claims 1 to 2, wherein the amount of zinc released from the toner in the zinc stearate particles is 0.005% by mass or more.

4. The toner according to any one of claims 1 to 3, wherein the coating rate of the toner matrix particles by the resin fine particles is 40% or more and 60% or less.

5. A developer characterized by containing the toner described in any one of claims 1 to 4.

6. A toner storage unit containing the toner described in any one of claims 1 to 4.

7. Electrostatic latent image carrier, An electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, A developing means for developing the electrostatic latent image to form a visible image using the toner described in any one of claims 1 to 4 or the developer described in claim 5, A transfer means for transferring the visible image onto a recording medium, An image forming apparatus characterized by having fixing means for fixing a transferred image onto the recording medium.

8. An electrostatic latent image formation step in which an electrostatic latent image is formed on an electrostatic latent image carrier, A developing step of developing the electrostatic latent image to form a visible image using the toner according to any one of claims 1 to 4 or the developer according to claim 5, A transfer step of transferring the visible image onto a recording medium, An image forming method characterized by comprising a fixing step of fixing the transferred image onto the recording medium.

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