Toner

Abstract

The present invention relates to a toner. There is provided a toner including: toner particles containing a binder resin, a release agent, and a colorant; and iron oxide particles present on the surface of the toner particles, wherein the iron oxide particles have a surface containing a compound having a specific structure.

Description

Technical Field

[0001] The present invention relates to a toner used in a recording method such as an electrophotographic method. Background Art

[0002] In recent years, image forming apparatuses such as copiers or printers have diversified in terms of usage purposes and usage environments, and improvements in high speed, high image quality, and high stability have been required. In addition, copiers or printers have been miniaturized or improved in energy saving at the same time. Therefore, it is preferable to use a magnetic one-component development system using a magnetic toner useful in these aspects.

[0003] The electrophotographic method includes a charging step of charging an electrostatic latent image bearing member (hereinafter referred to as a photosensitive member) by a charging unit, an exposure step of exposing the charged photosensitive member to form an electrostatic latent image, and a developing step of developing the electrostatic latent image with a toner to form a toner image. Next, the toner image is output as an image through a transfer step of transferring the toner image onto a recording material with or without an intermediate transfer member, and a fixing step of heating and pressing the toner image by passing the recording material bearing the toner image through a nip portion formed by a pressing member and a rotatable image heating member. In particular, in a magnetic one-component development system, development is performed by storing a magnetic toner using a toner carrier (hereinafter referred to as a sleeve) provided with a magnetic field generating unit such as a magnetic roll and transporting the magnetic toner to a development area.

[0004] In recent years, in order to cope with high image quality and energy saving, optimization of each step has become important. In order to improve image quality, it is generally important to optimize the developing step of developing the electrostatic latent image with a toner to form a toner image and the transfer step of transferring the toner image from the photosensitive member to the recording material. In addition, in order to improve energy saving, it is important to perform sufficient fixing at a low temperature.

[0005] Considering problems related to the transfer step, transfer defects can be instances where image defects occur when there are problems during transfer. In the transfer step, a transfer bias is applied to the toner on the photosensitive member and the toner is transferred onto the recording medium by electrostatic attraction. At this time, the toner may remain on the photosensitive member without being transferred, or may interfere with the toner layer during transfer, and thereby, defects or unevenness may occur on the image. This phenomenon is called a transfer defect.

[0006] So far, in order to improve the transferability, attempts have been made to measure by externally adding iron oxide particles during toner production while suppressing the decrease in the fluidity of the toner (Japanese Patent Application Laid-Open No. 2000-214625 and Japanese Patent Application Laid-Open No. 2005-37744).

[0007] However, in Japanese Patent Application Laid-Open No. 2000-214625 and Japanese Patent Application Laid-Open No. 2005-37744, there is still room for research on the compatibility between transferability and fixability.

[0008] Specifically, in the toners described in Japanese Patent Application Laid-Open No. 2000-214625 and Japanese Patent Application Laid-Open No. 2005-37744, sufficient release performance has not been obtained, and in the fixing step, member contamination may occur in a pressure member, an image heating member, etc., which may cause image defects.

[0009] In addition, for example, in a state where frictional pressure is applied to the fixed image such as when erasing written characters with an eraser, the toner of the fixed image will peel off from the paper. Summary of the Invention

[0010] The present invention is made in view of the above problems.

[0011] That is, an object of the present invention is to provide a toner that can improve the release performance in the fixing step and suppress member contamination, and the amount of toner peeled off from the image is small and it has excellent friction fixing property.

[0012] As a result of intensive research, the present inventors have found that the above problems can be solved by the following toner according to the present invention.

[0013] That is, the toner according to the present invention is a toner including: toner particles containing a binder resin, a release agent, and a colorant; and iron oxide particles present on the surface of the toner particles, wherein the iron oxide particles have a surface containing a compound having a structure represented by the following formula (1),

[0014] R-SiO 3 / 2 (1)

[0015] wherein, R represents a hydrocarbon group having 1 or more carbon atoms.

[0016] With reference to the accompanying drawings, further features of the present invention will become apparent from the following description of exemplary embodiments. Brief Description of the Drawings

[0017] Figure 1 is a diagram showing a capacitor model.

[0018] Figure 2 An example of an absorption spectrum of Si in near-edge X-ray absorption fine structure (NEXAFS) obtained by observing hydrophobized iron oxide particles is shown. Detailed Description of the Invention

[0019] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

[0021] The toner according to the present invention is a toner including: toner particles containing a binder resin, a release agent, and a colorant; and iron oxide particles present on the surface of the toner particles, wherein the iron oxide particles have a surface containing a compound having a structure represented by the following formula (1),

[0022] R-SiO 3 / 2 (1)

[0023] wherein R represents a hydrocarbon group having 1 or more carbon atoms.

[0024] In the transfer step, the toner is charged to a positive or negative polarity between the photosensitive member and the recording medium, and a reverse polarity bias is applied to the transfer material on the back surface of the recording medium. Since the charged toner particles are deposited in several layers, it is considered that surface discharge occurs along the surface of the toner particles during the transfer step.

[0025] In the case where strong surface discharge occurs, due to the disorder of charging, the toner tends to become a reverse component, which causes "re-transfer" in which the toner on the recording medium returns to the photosensitive member. For example, when re-transfer frequently occurs when outputting a solid black image, transfer defects become significant, and an uneven image is formed.

[0026] That is, in order to suppress transfer defects, it is necessary to suppress surface discharge along the toner surface.

[0027] Here, considering the discharge, the capacitor model shown in Figure 1 can be considered, where the photosensitive member and the transfer material on the back surface of the recording medium are used as electrode plates. Assuming that the dielectric 12 between the electrodes 11 is the toner and its capacitance is C, C is represented by the following equation.

[0028] C = εS / d

[0029] wherein S represents the area of one electrode plate, d represents the distance between the electrode plates, and ε represents the dielectric constant of the dielectric between the electrode plates.

[0030] When the electric field applied between the electrodes 11 is large and Figure 1 the capacitance C of the dielectric 12 is small, discharge occurs.

[0031] According to the above equation, the capacitance C is proportional to the dielectric constant ε of the toner as the dielectric. Therefore, a toner having a high dielectric constant ε is desired to have the effect of reducing the discharge frequency. Based on this idea, as a result of in-depth research from the viewpoint of substances having a high dielectric constant, the present inventors have found that a remarkable effect can be obtained when iron oxide particles are present on the surface of the toner. It is considered that the reason is that the presence of iron oxide particles having a high dielectric constant on the surface of the toner particles makes it difficult for creeping discharge to occur on the surface of the toner particles.

[0032] On the other hand, the present inventors have found that when iron oxide particles are present on the surface of the toner, component contamination occurs in a pressure member, an image heating member, etc. during the fixing step, which causes image defects. It is speculated that this is due to the following reasons.

[0033] In the case of externally adding iron oxide particles, the transferability is improved, but the surface of the iron oxide particles is hydrophilic, resulting in low affinity with the release agent in the toner, and during the fixing step, the release agent does not easily ooze out around the externally added iron oxide particles.

[0034] Generally, during the fixing step, a release agent having a high sharp melting property oozes out on the image surface. At this time, when iron oxide particles having a low affinity with the release agent are present on the surface of the toner, the release agent is repelled, resulting in the formation of a region where a part of the image surface is not covered with the release agent. Therefore, it is considered that the release effect is not sufficiently exerted during the fixing step, leading to component contamination.

[0035] Image defects caused by component contamination occur significantly in high-speed machines. It is speculated that the reason involves the heat applied to the toner layer. As the image formation speed is higher, the heat from the fixing device is more difficult to transfer to the toner, and a large amount of insufficiently melted toner tends to increase. That is, the proportion of toner in which the amount of the release agent oozing out from the inside of the toner is insufficient increases, and fixing defects are more likely to occur.

[0036] In addition, when forming a fixed image using a toner containing toner particles with iron oxide particles present on the surface, and rubbing the obtained fixed image with a wiper, the toner of the fixed image can be easily peeled off from the paper. It is speculated that this is because the release agent does not have affinity around the iron oxide particles having a hydrophilic surface, the slidability of the wiper deteriorates, and the toner of the fixed image is peeled off from the paper due to the friction between the wiper and the toner. In particular, at the concave portions of the paper between the paper fibers, the pressure applied to the toner during the fixing step is insufficient, only the surface of the toner is fixed in a molten state, and the release agent supplied from the inside of the toner is insufficient. Therefore, the slidability of the wiper deteriorates significantly, and the toner is easily peeled off from the paper.

[0037] In the present invention, the iron oxide particles present on the surface of the toner particles are hydrophobized to contain a compound having a structure represented by the formula (1). That is, the iron oxide particles present on the surface of the toner particles are hydrophobized by bonding a siloxane condensate having a hydrocarbon group with 1 or more carbon atoms to the surface of the iron oxide particles. Therefore, when using the toner according to the present invention, contamination of components due to fixing defects is suppressed, and the friction fixing property is improved.

[0038] According to the research conducted by the present inventors, it was found that by subjecting the iron oxide particles to a silane-based surface treatment, the chargeability is improved and excellent characteristics of the toner are exhibited. In the present invention, a similar effect of improving the chargeability can be obtained by subjecting the iron oxide particles to a surface treatment with a siloxane condensate.

[0039] On the other hand, when using an inorganic coupling agent condensate such as a titanate-based or aluminate-based coupling agent condensate other than Si, the chargeability is worse than when using a siloxane condensate. Therefore, when iron oxide particles surface-treated with an inorganic coupling agent condensate other than Si are present on the surface of the toner particles, the charging of the toner is suppressed, and surface discharge due to uneven charging is likely to occur. As a result, the transferability cannot be compatible with the fixing property.

[0040] In addition, when the iron oxide particles are surface-treated with an inorganic compound not having an R group, hydrophobicity is not exhibited, and thus, the effect of improving the release performance is not obtained, and the fixing property cannot be improved.

[0041] In addition, when the R group in the formula (1) is not a hydrocarbon group, hydrophobicity on the surface of the iron oxide particles is not obtained. Therefore, the effects of improving component contamination and friction fixing property are not obtained.

[0042] In addition, when silicone oil is used as the siloxane compound for hydrophobizing the surface of iron oxide particles, the effects of the present invention cannot be obtained. It is speculated that this is because the fixation rate of silicone oil to iron oxide particles is low, and silicone oil peels off from the iron oxide particles in the fixing step, and thereby exposes the hydrophilic iron oxide surface.

[0043] In formula (1), the number of carbon atoms of the R group is preferably from 1 to 20, more preferably from 2 to 10, and still more preferably from 4 to 6.

[0044] The smaller the number of carbon atoms of the R group in formula (1), the lower the affinity between the surface of the iron oxide particles and the release agent. Therefore, the effect of attracting the release agent near the iron oxide particles is low, and the effect of suppressing the contamination of the member due to fixing defects is also low.

[0045] On the other hand, as the number of carbon atoms of the R group in formula (1) increases, the affinity with the release agent increases, and the effect of attracting the release agent near the iron oxide particles increases. However, when the number of carbon atoms is too large, due to the steric hindrance of the R group, the surface of the iron oxide particles is not uniformly hydrophobized. Therefore, regions where hydrophobization treatment is not performed are generated on the surface of the iron oxide particles, and the hydrophilic surface is exposed. As a result, the effects of improving the contamination of the member due to fixing defects and tribofixing properties are reduced.

[0046] Preferably, the iron oxide particles are externally added to the surface of the toner in a sufficiently pulverized state. When the amount of secondary aggregates of iron oxide particles coated on the surface of the toner particles is large, the release agent exuded in the fixing step is restricted in the aggregated particles of the iron oxide particles, and the release effect around the iron oxide particles cannot be obtained sufficiently. The pulverized state of the iron oxide particles can be evaluated by measuring the diameter of the aggregated particles of the iron oxide particles on the toner surface with a scanning electron microscope. The diameter of the aggregated particles of the iron oxide particles is preferably 1.2 times or less of the primary particle diameter of the iron oxide particles.

[0047] The fixation rate of the iron oxide particles to the toner particles is preferably 50 to 80%. When the fixation rate of the iron oxide particles is 80% or less, the iron oxide particles are embedded in the surface of the toner, and it is difficult to suppress the exudation of the release agent. In addition, the effect of suppressing the surface discharge on the toner surface in the transfer step can be obtained sufficiently, and transfer defects can be suppressed effectively. In addition, when the fixation rate of the iron oxide particles is 50% or more, the iron oxide particles are less likely to be free, and thereby, the loss of the effect of suppressing transfer defects can be suppressed.

[0048] The fixation rate of the iron oxide particles to the toner particles is more preferably 60 to 78%.

[0049] The content ratio of the iron oxide particles present on the surface of the toner particles to the total amount of the toner is preferably 0.10 to 5.00% by mass. When the content ratio of the iron oxide particles present on the surface of the toner particles to the total amount of the toner is 0.10% by mass or more, the surface discharge along the surface of the toner layer is significantly suppressed, and the transferability is significantly improved, and thus, transfer defects can be effectively suppressed. In addition, since the release agent exuded in the fixing step can be attracted by the hydrophobized iron oxide particles, excellent release performance can be obtained. In addition, when the content ratio of the iron oxide particles present on the surface of the toner particles to the total amount of the toner is 5.00% by mass or less, the amount of the iron oxide particles is not excessive, and the appearance of white streaks caused by the wear of the members by the free iron oxide particles can be suppressed. Therefore, the reduction in the image density of the solid black image caused by the appearance of the white streaks can be suppressed. The content ratio of the iron oxide particles present on the surface of the toner particles to the total amount of the toner is more preferably 0.50 to 4.00% by mass, and still more preferably 1.00 to 2.50% by mass.

[0050] In the present invention, the difference between the SP value of the binder resin and the SP value of the release agent is preferably 1.50 or more, and the SP value is calculated by the Fedors method. In addition, the difference between the SP value of the release agent and the SP value of the compound having the structure represented by the formula (1) is preferably 1.20 or less, and the SP value is calculated by the Fedors method.

[0051] The SP value is a so-called solubility parameter and is a numerical value used as an index indicating the solubility or affinity of how much a substance dissolves in certain substances. When the SP value of one substance is close to the SP value of another substance, the solubility or affinity of the substance with the other substance is high, and when the SP value of one substance is far from the SP value of another substance, the solubility or affinity of the substance with the other substance is low. In the present invention, the SP value is a value calculated based on the commonly used Fedors method [Poly. Eng. Sci., 14(2) 147(1974)]. The unit of the SP value is (cal / cm 3 ) 1 / 2 。

[0052] In order for the toner heated and melted in the fixing step to exhibit a release effect, it is necessary to separate the release agent from the binder resin and exude it. In addition, the exuded release agent needs to be evenly spread around the iron oxide particles on the surface of the toner.

[0053] When the SP values of the binder resin, the release agent, and the compound having the structure represented by the formula (1) satisfy the above relationship, the release agent can exude from the inside of the toner during fixing to produce a state where the exuded release agent is spread around the iron oxide particles on the surface of the toner.

[0054] When the difference between the SP value of the binder resin and the SP value of the release agent is 1.50 or more, the release agent is likely to separate from the binder resin and exude to the surface of the toner, and thus the release effect is likely to be exhibited.

[0055] In addition, when the difference between the SP value of the release agent and the SP value of the compound having the structure represented by the formula (1) is 1.20 or less, the release agent has a high affinity for the compound having the structure represented by the formula (1) on the surface of the iron oxide particles. Therefore, the problem that the release agent exuding to the surface of the toner is difficult to exude around the iron oxide particles that have not been hydrophobized can be sufficiently solved. Therefore, a high release effect can be obtained, and image defects caused by member contamination can be suppressed.

[0056] The difference between the SP value of the binder resin and the SP value of the release agent is more preferably from 2.00 to 3.50, and still more preferably from 2.50 to 3.00. In addition, the difference between the SP value of the release agent and the SP value of the compound having the structure represented by the formula (1) is more preferably 1.10 or less, and still more preferably 1.00 or less.

[0057] In the present invention, in the endothermic curve obtained by measurement using a differential scanning calorimeter (DSC) with both the heating rate and the cooling rate being 100 °C / min, the half-value width of the endothermic peak in the second heating process is preferably from 4.0 to 8.0 °C.

[0058] The endothermic peak in the present invention refers to the endothermic peak derived from the release agent.

[0059] As a conventionally used DSC measurement method, for example, in the case of the method according to JIS K 7121 (the international standard is ASTM D3418-82), the heating rate is usually measured as 10 °C / min. Here, focusing on the printing speed of the printer, in order to prevent the toner from adhering to the fixing device, it is necessary, for example, for the toner to melt and the release agent to exude within a very short time of several milliseconds to several tens of milliseconds in order to exhibit the release effect. Therefore, as a result of intensively studying the ability of the release agent to separate from and exude from the binder resin, the present inventors found that it is effective to change the heating rate and the cooling rate in the DSC measurement from the usual 10 to 100 °C / min.

[0060] When the measured heating rate and cooling rate are each 10 °C / min, considering the movement of the release agent, the measurement rate is considered slow. That is, among the parameters that can be obtained under the measurement conditions where the measured heating rate and cooling rate are each 10 °C / min, assuming several milliseconds to several tens of milliseconds as the time during which the toner can directly receive heat from the fixing device, the release performance of the printer in the fixing step cannot be described.

[0061] Next, the case where the first heating and cooling and the second heating are all performed at 100 °C / min will be described.

[0062] In a combination where the release agent and the binder resin are easily compatible with each other, when the first heating and the cooling are performed at 100 °C / min, there is no time to sufficiently separate the release agent from the binder resin, and the cooling is completed while maintaining the molten plastic state after the heating. Then, when the temperature is raised again at 100 °C / min while maintaining the plastic state, the temperature is raised in a state where the binder resin and the release agent are partially plasticized, and an endothermic peak is obtained in a state where the binder resin and the release agent are mixed with each other, rather than an endothermic peak peculiar to the release agent. In this state, since the release agent and the binder resin are easily compatible with each other, the half-value width is wider.

[0063] In the present invention, the half-value width of the endothermic peak in the second heating process is preferably 4.0 to 8.0 °C, and it means that the half-value width of the endothermic peak in the second heating process is somewhat narrow.

[0064] The sharpness of the endothermic peak reflects the degree to which the melting of the release agent and the subsequent separation from the binder resin proceed during the heating process. That is, in the case where the release agent is melted and further separated from the binder resin by sufficiently following the rapid heating rate, the endothermic peak in the second heating process becomes narrow, and the half-value width becomes a small value.

[0065] In the present invention, in order to solve the above-mentioned member contamination in the fixing step, it is necessary to melt the toner and exude the release agent in a very short time of several milliseconds to several tens of milliseconds. Therefore, it is important to control the half-value width of the endothermic peak in the second heating process within a predetermined range.

[0066] In the present invention, when the half-value width of the endothermic peak in the second heating process is 4.0 °C or more, the phases of the binder resin and the release agent are separated in the developing step, and the release agent on the surface of the toner exudes, so that the deterioration of the developability can be suppressed. In addition, when the half-value width of the endothermic peak in the second heating process is 8.0 °C or less, the melting of the release agent or the separation of the binder resin can sufficiently follow the high-speed heating, and the member contamination in the fixing step can be suppressed.

[0067] In the endothermic curve obtained by measurement using DSC with both the heating rate and the cooling rate being 100 °C / min, the half-value width of the endothermic peak in the second heating process is more preferably 4.0 to 6.0 °C.

[0068] In the present invention, the wettability of the iron oxide particles present on the surface of the toner particles is preferably 40 to 80 vol%. The wettability of the iron oxide particles present on the surface of the toner particles is determined as follows. The iron oxide particles present on the surface of the toner particles are suspended in a 50 mL methanol / water mixed solvent in an amount of 0.1 g, and the transmittance of light with a wavelength of 780 nm is measured. Then, the value of the methanol concentration when the transmittance is 50% is taken as the wettability of the iron oxide particles present on the surface of the toner particles. The wettability of the iron oxide particles present on the surface of the toner particles is more preferably 55 to 60 vol%. When the wettability is within the above value range, the chargeability of the iron oxide particles is improved, and the affinity with the release agent is improved. Therefore, a sufficient release effect can be obtained around the iron oxide particles, and image defects caused by member contamination can be suppressed. The wettability can be controlled by changing the surface treatment state of the iron oxide particles. When the wettability is 40 vol% or more, a high degree of hydrophobic treatment of the surface of the iron oxide particles can be obtained, and a high release effect can be obtained in the fixing step. In addition, when the wettability is 80 vol% or less, the embedding of the iron oxide particles in the surface of the toner particles can be suppressed, and problems such as transfer defects or fogging caused by charge defects of the toner, for example, can be suppressed.

[0069] The water / methanol wettability test method will be described below.

[0070] In the present invention, the compound having the structure represented by the formula (1) present on the surface of the iron oxide particles is preferably a highly condensed compound having a high degree of condensation.

[0071] In the case where there is a high molecular weight body in a highly condensed state, compared with the case where there is a low molecular weight body in a low condensed state, the hydrophobizing agent tends to be more bulky. Therefore, the density of the hydrocarbon chains on the surface of the iron oxide particles is increased, and the affinity with the release agent exuded from the inside of the toner in the fixing step is easily improved. As a result, significant effects of improving member contamination or friction fixing property due to release defects can be obtained.

[0072] The index for evaluating the degree of condensation of the compound having the structure represented by the formula (1) contained in the surface of the iron oxide particles will be described below.

[0073] In the present invention, [Si - O - Si] / [Si - C] is preferably 1.4 to 1.7. Here, [Si - O - Si] / [Si - C] is defined as follows. An infrared absorption spectrum (Fourier transform infrared (FT - IR) spectrum) of the components extracted from the iron oxide particles present on the surface of the toner particles with toluene is obtained. In the obtained FT - IR spectrum, in the range of 990 to 1,040 cm -1The maximum absorption peak intensity within the range is defined as [Si-O-Si]. Additionally, in the range of 1,240 to 1,280 cm -1 the maximum absorption peak intensity is defined as [Si-C]. In this case, the ratio of [Si-O-Si] to [Si-C] is [Si-O-Si] / [Si-C].

[0074] In the hydrophobized iron oxide particles, there is a certain amount of condensate of the treating agent that is not bound to the iron oxide particles. The iron oxide particles are impregnated in 50 mL of toluene in an amount of 100 mg, and then left for 5 hours so that the condensate of the treating agent can be extracted into toluene. The condensation state of the hydrophobizing treating agent can be determined by measuring the FT-IR spectrum of the extract obtained by removing the iron oxide particles and then evaporating and drying the toluene.

[0075] The FT-IR spectrum is measured by the attenuated total reflection (ATR) method. The measurement is carried out under the conditions where Ge is used as the ATR crystal and the incident angle of the infrared light is 45° to obtain the FT-IR spectrum. In the obtained FT-IR spectrum, the maximum absorption peak intensity within the range of 990 to 1,040 cm -1 that is considered to be derived from Si-O-Si of the siloxane is defined as [Si-O-Si]. Additionally, in the obtained FT-IR spectrum, the maximum absorption peak intensity within the range of 1,240 to 1,280 cm -1 that is considered to be derived from Si-C of the siloxane is defined as [Si-C].

[0076] In the case of obtaining the FT-IR spectrum in the monomer units obtained by hydrolyzing the silane coupling treating agent, the peak intensity ratio [Si-O-Si] / [Si-C] is 1.3.

[0077] On the other hand, in the case of obtaining the FT-IR spectrum in the polymer obtained by fully condensing the hydrolysis product of the silane coupling treating agent, the peak intensity ratio [Si-O-Si] / [Si-C] is 1.7.

[0078] When the condensation rate of the silane coupling agent in the toluene extract of the iron oxide particles is low, since the proportion of monomer units in the extract is high, the peak intensity ratio [Si-O-Si] / [Si-C] is a value close to 1.3. On the other hand, when the condensation rate of the silane coupling agent in the toluene extract of the iron oxide particles is high, since the proportion of monomer units in the extract is low, the peak intensity ratio [Si-O-Si] / [Si-C] is a value close to 1.7.

[0079] When [Si-O-Si] / [Si-C] is 1.4 or more, the condensation rate of the silane coupling agent can be high, and the demolding effect in the fixing step can be improved.

[0080] The measurement of the FT-IR spectrum by the ATR method will be described later.

[0081] In addition, in the iron oxide particles present on the surface of the toner particles, when the near-edge X-ray absorption fine structure (hereinafter referred to as NEXAFS) is observed by measurement using the total electron yield (TEY) method with soft X-rays, the obtained absorption spectrum of Si has peak A in the range of 1,844.4 to 1,844.8 eV and peak B in the range of 1,846.1 to 1,846.6 eV, and IA / (IA + IB) / MSi is preferably 40 to 55 g / mol, where IA is the area of peak A, IB is the area of peak B, and MSi is the number of moles of Si derived from the silane compound contained in 1 g of the iron oxide particles.

[0082] By observing NEXAFS, information on the bonding state of the Si element of the silane compound bonded to the surface of the iron oxide particles can be obtained. NEXAFS is observed by the total electron yield (TEY) method in which the energy of electrons generated from the sample is not selected in the spectroscopic analysis using soft X-rays.

[0083] The soft X-rays penetrate to a depth of about 50 nm from the surface of the sample to be measured, but electrons detected by NEXAFS such as photoelectrons or Auger electrons that spill out from the sample surface are limited to a depth of about 5 nm. Therefore, the chemical bonding state of the silane compound on the surface of the iron oxide particles can be observed very significantly.

[0084] Figure 2 An example of the absorption spectrum of Si in NEXAFS obtained by measuring the hydrophobized iron oxide particles is shown. The absorption spectrum of Si has two peaks A and B in the range of 1,840 to 1,850 eV. Peak A appears on the low energy side, and peak B appears on the high energy side. Specifically, the peak position of peak A appears in the range of 1,844.4 to 1,844.8 eV, and the peak position of peak B appears in the range of 1,846.1 to 1,846.6 eV.

[0085] Here, it is known that when the bond between the Si atom and the O atom in the silane compound is represented by Si-O-X, the bond between the Si atom and the O atom corresponds to peak A when X is Si, and the bond between the Si atom and the O atom corresponds to peak B when X is Fe. That is, it can be determined that the amount of the silane compound bonded to the surface of the iron oxide particles is small because peak A in the absorption spectrum of Si is large, and the amount of the silane compound bonded to the surface of the iron oxide particles is large because peak B is large.

[0086] Since the proportion of the silane compound chemically bonded to the surface of the iron oxide particles is small, the silane coupling agents highly condense with each other, and the silane compound on the surface of the iron oxide particles becomes bulky. Since the silane compound on the surface of the iron oxide particles becomes bulky, the affinity with the mold release agent is high, and the mold release effect around the iron oxide particles is further improved.

[0087] That is, the absorption spectrum of Si in the above NEXAFS is measured so that the binding ratio information between the iron oxide particles and the silane coupling agent can be obtained. Therefore, the bulkiness of the silane compound on the surface of the iron oxide particles can be evaluated.

[0088] When IA / (IA + IB) / MSi is 55 g / mol or less, the binding between the silane compound and the iron oxide particles is strong, and the exposure of the hydrophilic iron oxide surface is suppressed. When IA / (IA + IB) / MSi is 40 g / mol or more, the degree of condensation of the silane compound can be high, and a high mold release effect can be obtained. IA / (IA + IB) / MSi is more preferably 43 to 48 g / mol.

[0089] The reason for dividing the value of IA / (IA + IB) by the value of MSi is for normalization. For example, a scanning X-ray fluorescence spectrometer ZSX PrimusII (manufactured by Rigaku Corporation) is used to measure MSi.

[0090] The toner according to the present invention contains iron oxide particles present on the surface of the toner particles, and the iron oxide particles are hydrophobized so as to contain a compound having a structure represented by formula (1). Here, the iron oxide particles can be contained on the surface of the toner particles by external addition to the toner particles.

[0091] Examples of the iron oxide particles include iron oxides such as magnetite, maghemite, or ferrite; and metals such as iron, cobalt, or nickel, or alloys of these metals and metals such as aluminum, copper, magnesium, tin, zinc, beryllium, calcium, manganese, selenium, titanium, tungsten, or vanadium, and mixtures thereof.

[0092] The shape of the iron oxide particles is an octahedron, hexahedron, sphere, needle shape, or scale shape, etc., and any shape can be used, but the shape of the iron oxide particles preferably has a polyhedral structure such as at least a tetrahedron, and more preferably a polyhedral structure such as at least an octahedron.

[0093] The number average particle diameter (D1) of the primary particles of the iron oxide particles is preferably 0.50 μm or less, and more preferably 0.05 to 0.30 μm.

[0094] When the number average particle diameter (D1) of the primary particles of the iron oxide particles is 0.05 to 0.30 μm, in the external addition step, the iron oxide particles are likely to uniformly adhere to the surface of the toner particles in the state of primary particles, and an effect of reducing fogging is obtained. The number average particle diameter (D1) of the primary particles of the iron oxide particles is more preferably 0.10 to 0.30 μm.

[0095] In addition, as the magnetic properties of the iron oxide particles when applying 79.6 kA / m, when the coercive force (Hc) is 1.6 to 25.0 kA / m, the developability tends to be improved, which is preferable. The coercive force (Hc) is more preferably 15.0 to 25.0 kA / m. In addition, the magnetization intensity (σs) is preferably 30 to 90 Am 2 / kg, and more preferably 40 to 80 Am 2 / kg. In addition, the residual magnetization (σr) is preferably 1.0 to 10.0 Am 2 / kg, and more preferably 1.5 to 8.0 Am 2 / kg.

[0096] The iron oxide particles can be produced by, for example, the following method.

[0097] An alkali such as sodium hydroxide equivalent to or more than equivalent to the iron compound is added to an aqueous solution of ferrous salt to prepare an aqueous solution containing ferrous hydroxide. While maintaining the pH of the prepared aqueous solution at a pH of 7 or more, air is blown into the prepared aqueous solution, and while heating the aqueous solution to 70 °C or more, an oxidation reaction of ferrous hydroxide is carried out so that first, seeds of the core of iron oxide powder are generated.

[0098] Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to a slurry solution containing seeds based on the amount of the alkali previously added. While maintaining the pH of the solution at 5 to 10 and blowing air, the reaction of ferrous hydroxide is carried out, whereby iron oxide powder is grown using the seeds as the core. At the same time, the shape and magnetic properties of the iron oxide particles can be controlled by selecting arbitrary pH, reaction temperature, and stirring conditions. As the oxidation reaction proceeds, the pH of the solution shifts to the acidic side, and preferably, the pH of the solution is not less than 5. The iron oxide particles can be obtained by filtering, washing, and drying the iron oxide particles obtained by the conventional method as described above.

[0099] In addition, in the case of surface treatment by a dry method, a coupling agent treatment is performed on the washed, filtered, and dried iron oxide particles. When surface treatment is performed by a wet method, after the oxidation reaction, the dried iron oxide particles are redispersed, or after the oxidation reaction, without drying, the iron oxide particles obtained by washing and filtering are redispersed in another aqueous medium, and then, a coupling agent treatment is performed. In the present invention, both the dry method and the wet method can be appropriately selected.

[0100] Examples of coupling agents that can be used in the surface treatment of iron oxide particles include silane coupling agents. A silane coupling agent having a structure represented by the general formula (2) is more preferably used.

[0101] R-SiX n Y m (2)

[0102] Wherein, X and Y each represent an alkoxy group, n and m each independently represent an integer from 0 to 3, n + m is 3, and R represents an alkyl group, a phenyl group, a vinyl group, an epoxy group, or a (meth)acryloyl group.

[0103] Examples of the silane coupling agent represented by the general formula (2) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, n-propyltrimethoxysilane, isopropyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, trimethylmethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, hydroxypropyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.

[0104] In the present invention, a silane coupling agent represented by the general formula (2) in which R is an alkyl group can be preferably used. Among them, R is preferably an alkyl group having 3 to 6 carbon atoms, and R is particularly preferably an alkyl group having 3 or 4 carbon atoms.

[0105] In the case of using a silane coupling agent, the silane coupling agent can be used alone for treatment, or a plurality of silane coupling agents can be combined for treatment. When a plurality of silane coupling agents are used in combination, each silane coupling agent can be used for treatment, or all the silane coupling agents can be used for treatment simultaneously.

[0106] The total amount of the coupling agent used for treatment is preferably 0.9 to 3.0 parts by mass with respect to 100 parts by mass of the iron oxide particles, and it is important to adjust the amount of the treatment agent according to the surface area of the iron oxide particles, the reactivity of the coupling agent, etc.

[0107] In the present invention, examples of the binder resin of the toner include, but are not limited to, vinyl resins and polyester resins, and resins known in the related art can be used.

[0108] Specifically, for example, styrene copolymers such as polystyrene, styrene-propylene copolymer, styrene-vinyltoluene 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, styrene-octyl methacrylate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer or styrene-maleate copolymer, polyacrylate, polymethacrylate, and polyvinyl acetate can be used, and these resins can be used alone or in combination of two or more thereof. Among them, styrene copolymers and polyester resins are particularly preferred in terms of developing properties and fixability.

[0109] The glass transition temperature (Tg) of the toner is preferably 40 to 70 °C. When the glass transition temperature of the toner is 40 to 70 °C, storage stability and durability can be improved while maintaining excellent fixability.

[0110] Preferably, a charge control agent is added to the toner according to the present invention. As a negative charge control agent, organometallic complexes and chelates are effective, and specific examples thereof include monoazo metal complexes; acetylacetone metal complexes; and metal complexes such as aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids. Specific examples of commercially available products of the negative charge control agent include Spilon Black TRH, T-77, and T-95 (manufactured by Hodogaya Chemical Co., Ltd.) and BONTRON (registered trademark) S-34, S-44, S-54, E-84, E-88, and E-89 (manufactured by Orient Chemical Industries Co., Ltd.).

[0111] In addition, examples of positive charge control agents include nigrosine and nigrosine products modified with fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthalenesulfonate or tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts and their lake pigments; triphenylmethane dyes and their lake pigments (as lake formers, for example, phosphotungstic acid, phosphomolybdic acid, phosphotungstomolybdic acid, tannic acid, lauric acid, gallic acid, ferrocyanic acid, or ferrocyanide, etc.); metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, or dicyclohexyltin oxide; and organotin borates such as dibutyltin borate, dioctyltin borate, or dicyclohexyltin borate. Specific examples of commercially available products of positive charge control agents include TP-302 and TP-415 (manufactured by Hodogaya Chemical Co., Ltd.), BONTRON (registered trademark) N-01, N-04, N-07, and P-51 (manufactured by Orient Chemical Industries Co., Ltd.), and Copy Blue PR (manufactured by Clariant AG).

[0112] These charge control agents can be used alone or in combination of two or more of them. From the viewpoint of the charge amount of the toner, the amount of the charge control agent used is preferably 0.1 to 10.0 parts by mass, and more preferably 0.1 to 5.0 parts by mass, relative to 100 parts by mass of the binder resin.

[0113] The toner particles contain a release agent. The toner particles contain a release agent so that the fixability is improved.

[0114] As the release agent, all known release agents can be used. Specific examples thereof include petroleum waxes such as paraffin wax, microcrystalline wax, or petrolatum and their derivatives, montan wax and its derivatives, hydrocarbon waxes obtained by the Fischer-Tropsch method and their derivatives, polyolefin waxes such as polyethylene or polypropylene and their derivatives, natural waxes such as carnauba wax or candelilla wax and their derivatives, and ester waxes. Here, derivatives include oxides, block copolymers with vinyl monomers, or graft-modified products. In addition, as the ester wax, monofunctional ester waxes, bifunctional ester waxes, or polyfunctional waxes such as tetrafunctional or hexafunctional ester waxes can be used.

[0115] The content ratio of the release agent in the toner particles is preferably 0.5 to 10 parts by mass relative to 100 parts by mass of the binder resin. When the content ratio of the release agent is within the above range, the fixability is improved and the storage stability of the toner is not impaired.

[0116] Alternatively, the release agent can be blended in the binder resin by a method in which the resin is dissolved in a solvent in the production of the binder resin, the temperature of the resin solution is increased, and addition and mixing are carried out while stirring, or by a method in which addition is carried out during melt-kneading in the production of the toner.

[0117] The peak temperature of the maximum endothermic peak measured by differential scanning calorimetry (DSC) of the release agent (hereinafter referred to as the melting point) is preferably 60 to 140°C, and more preferably 70 to 130°C. When the peak temperature of the maximum endothermic peak (melting point) is 60 to 140°C, the toner is easily plasticized during fixing, and the fixability is improved. In addition, when the toner is stored for a long time, leakage of the release agent is less likely to occur, which is preferable.

[0118] The peak temperature of the maximum endothermic peak of the release agent can be measured using a differential scanning calorimeter "Q 1000" (manufactured by TA Instruments) in accordance with ASTM D3418-82. In this case, the melting points of indium and zinc are used for temperature calibration of the detection unit of the apparatus, and the heat of fusion of indium is used for heat calibration.

[0119] Specifically, approximately 10 mg of the measurement sample is accurately weighed, the measurement sample is placed in an aluminum pan, and an empty aluminum pan is used as a reference. Measurement is carried out at a measurement temperature of 30 to 200°C and a heating rate of 10°C / minute. In the measurement, the temperature is raised to 200°C once, then cooled to 30°C at 10°C / minute, and then heated again at 10°C / minute. The peak temperature of the maximum endothermic peak of the release agent is determined from the DSC curve at a temperature of 30 to 200°C during the second heating process.

[0120] Examples of the colorant contained in the toner particles include, but are not particularly limited to, organic pigments, organic dyes, and inorganic pigments, and colorants known in the related art can be used.

[0121] Examples of cyan-based colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specifically, examples of cyan-based colorants include the following: C.I. Pigment Blue 1, C.I. Pigment Blue 7, C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 60, C.I. Pigment Blue 62, and C.I. Pigment Blue 66.

[0122] Examples of magenta-based colorants include the following: condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, examples of magenta-based colorants include the following: C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Violet 19, C.I. Pigment Red 23, C.I. Pigment Red 48:2, C.I. Pigment Red 48:3, C.I. Pigment Red 48:4, C.I. Pigment Red 57:1, C.I. Pigment Red 81:1, C.I. Pigment Red 122, C.I. Pigment Red 144, C.I. Pigment Red 146, C.I. Pigment Red 150, C.I. Pigment Red 166, C.I. Pigment Red 169, C.I. Pigment Red 177, C.I. Pigment Red 184, C.I. Pigment Red 185, C.I. Pigment Red 202, C.I. Pigment Red 206, C.I. Pigment Red 220, C.I. Pigment Red 221, and C.I. Pigment Red 254.

[0123] Examples of yellow-based colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complex compounds, methylene compounds, and allylamide compounds. Specifically, examples of yellow-based colorants include the following: C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 15, C.I. Pigment Yellow 17, C.I. Pigment Yellow 62, C.I. Pigment Yellow 74, C.I. Pigment Yellow 83, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 95, C.I. Pigment Yellow 97, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 111, C.I. Pigment Yellow 120, C.I. Pigment Yellow 127, C.I. Pigment Yellow 128, C.I. Pigment Yellow 129, C.I. Pigment Yellow 147, C.I. Pigment Yellow 151, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. Pigment Yellow 168, C.I. Pigment Yellow 174, C.I. Pigment Yellow 175, C.I. Pigment Yellow 176, C.I. Pigment Yellow 180, C.I. Pigment Yellow 181, C.I. Pigment Yellow 185, C.I. Pigment Yellow 191, and C.I. Pigment Yellow 194.

[0124] Examples of black-based colorants include carbon black and colorants provided by color mixing using the above yellow-based colorants, magenta-based colorants, and cyan-based colorants to obtain black.

[0125] These colorants can be used alone, as a mixture, or in a solid solution state. The colorants are selected from the viewpoints of hue angle, chroma, brightness, lightfastness, OHP transparency, and dispersibility in toner particles.

[0126] In the case where a magnetic material is used as a colorant, the magnetic material contains, for example, magnetic iron oxides such as magnetite or γ-iron oxide as a main component, and may contain elements such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, or silicon. The BET specific surface area of the magnetic material is preferably 2 to 30 m 2 / g, and more preferably 3 to 28 m 2 / g, and the BET specific surface area is obtained by the nitrogen adsorption method. In addition, the Mohs hardness of the magnetic material is preferably 5 to 7. The shape of the magnetic material is a polyhedron, octahedron, hexahedron, sphere, needle, or flake, etc., and a magnetic material with low anisotropy such as a polyhedron, octahedron, hexahedron, or sphere is preferred in terms of improving image density.

[0127] The content ratio of the colorant in the toner particles is preferably 1 to 20 parts by mass relative to 100 parts by mass of the binder resin or the polymerizable monomer constituting the binder resin. In the case where magnetic powder is used as a colorant, the content ratio of the magnetic powder in the toner particles is preferably 20 to 200 parts by mass relative to 100 parts by mass of the binder resin or the polymerizable monomer constituting the binder resin, and more preferably 40 to 150 parts by mass.

[0128] If necessary, iron oxide particles can be added to the toner according to the present invention, and external additives can be attached to the surface of the toner by mixing.

[0129] Examples of external additives include metal oxide fine particles (inorganic fine particles) such as silica fine particles, alumina fine particles, titanium dioxide fine particles, zinc oxide fine particles, strontium titanate fine particles, cerium oxide fine particles, and calcium titanate fine particles. In addition, composite oxide fine particles using two or more metals can be used, and two or more selected from these fine particles can be used in any combination.

[0130] In addition, resin fine particles or organic-inorganic composite fine particles of resin fine particles and inorganic fine particles can be used as external additives.

[0131] More preferably, the external additive includes at least one selected from the group consisting of silica fine particles and organic-inorganic composite fine particles.

[0132] Examples of silica fine particles include sol-gel silica fine particles produced by the sol-gel method, aqueous colloidal silica fine particles, alcoholic-silica fine particles, fumed silica fine particles obtained by the vapor phase method, and fused silica fine particles.

[0133] Examples of the resin fine particles include resin particles such as vinyl-based resins, polyester resins, and silicone resins.

[0134] Examples of the organic-inorganic composite fine particles include organic-inorganic composite fine particles composed of resin fine particles and inorganic fine particles.

[0135] In the case of the organic-inorganic composite fine particles, the excellent durability and chargeability exhibited by the inorganic fine particles are maintained, and during fixing, due to the component of the resin material having a low heat capacity, it is difficult to hinder the coalescence of toner particles and it is difficult to cause fixing hindrance. Therefore, it is easy to achieve both durability and fixability.

[0136] Preferably, the organic-inorganic composite fine particles are composite fine particles having convex portions formed by inorganic fine particles embedded in the surface of resin fine particles (preferably vinyl-based resin fine particles) as the resin component. More preferably, the organic-inorganic composite fine particles are composite fine particles having a structure in which the inorganic fine particles are exposed on the surface of the vinyl-based resin fine particles. Even more preferably, the organic-inorganic composite fine particles are composite fine particles having a structure in which the surface of the vinyl-based resin fine particles has convex portions derived from the inorganic fine particles.

[0137] Examples of the inorganic fine particles constituting the organic-inorganic composite fine particles include fine particles such as silica fine particles, alumina fine particles, titanium dioxide fine particles, zinc oxide fine particles, strontium titanate fine particles, cerium oxide fine particles, and calcium titanate fine particles.

[0138] The content ratio of the external additive in the toner is preferably 0.1 to 20.0 parts by mass with respect to 100 parts by mass of the toner particles.

[0139] The external additive can be hydrophobized with a hydrophobizing agent.

[0140] Examples of the hydrophobizing agent include chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tert-butyldimethylchlorosilane, and vinyltrichlorosilane;

[0141] For example, alkoxysilanes such as tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, and γ-(2-aminoethyl)aminopropylmethyldimethoxysilane;

[0142] For example, silazanes such as hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahyldisilazane, hexacyclohexyldisilazane, hexaphenyldisilazane, divinyltetramethyldisilazane, and dimethyltetravinyldisilazane;

[0143] For example, silicones such as dimethyl silicone oil, methylhydrogen silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil, chloroalkyl-modified silicone oil, chlorophenyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, methanol-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, and terminal-reactive silicone oil;

[0144] For example, siloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, and octamethyltrisiloxane; and

[0145] For example, long-chain fatty acids such as undecanoic acid, lauric acid, tridecanoic acid, dodecanoic acid, myristic acid, palmitic acid, pentadecanoic acid, stearic acid, heptadecanoic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, and arachidonic acid, and metal salts of these fatty acids with metals such as zinc, iron, magnesium, aluminum, calcium, sodium, or potassium.

[0146] Among them, in terms of easy hydrophobization treatment, alkoxysilanes, silazanes, and silicone oils are preferably used. These hydrophobization treatment agents can be used alone or in combinations of two or more of them.

[0147] In order to improve the fluidity or chargeability of the toner, the toner may contain a variety of external additives.

[0148] The number average particle diameter of the primary particles of the external additive is preferably from 0.030 to 0.30 μm.

[0149] In the toner according to the present invention, other external additives such as lubricant powders such as fluororesin powder, zinc stearate powder, or polyvinylidene fluoride powder can be used in small amounts; abrasives such as cerium oxide powder, silicon carbide powder, or strontium titanate powder; fluidity imparting agents such as titanium oxide powder or alumina powder; anti-caking agents; and anti-polar organic fine particles or inorganic fine particles as developability improvers, as long as they do not have a substantial adverse effect. In addition, the surface of the external additive can be hydrophobized.

[0150] The weight average particle diameter (D4) of the toner particles is preferably from 3.0 to 12.0 μm, and more preferably from 4.0 to 10.0 μm. When the weight average particle diameter (D4) of the toner particles is from 3.0 to 12.0 μm, excellent fluidity can be obtained, and the latent image can be developed sufficiently.

[0151] There is no particular limitation on the production method of the toner, and known production methods can be adopted. Examples of the production method of the toner include a pulverization method, a polymerization method, a dispersion polymerization method, an association aggregation method, a dissolution suspension method, a suspension polymerization method, and an emulsion aggregation method.

[0152] Hereinafter, the pulverization method for producing a toner by a melt-kneading step and a pulverization step will be specifically described, and the present invention is not limited thereto.

[0153] For example, a binder resin, a colorant, a release agent, and, if necessary, a charge control agent and an external additive are sufficiently mixed with each other by a mixer such as a Henschel mixer or a ball mill (mixing step). The obtained mixture is melt-kneaded by a heating kneader such as a twin-screw extruder, a heating roll, a kneader, or an extruder (melt-kneading step).

[0154] The obtained melt-kneaded product is cooled and solidified, pulverized by a pulverizer (pulverization step), and then classified by a classifier (classification step), thereby obtaining toner particles. In addition, if necessary, the toner particles and an external additive are mixed with each other by a mixer such as a Henschel mixer to obtain a toner.

[0155] Examples of mixers include the following: FM mixer (manufactured by NIPPON COKE&ENGINEERING CO.,LTD.); Super mixer (manufactured by KAWATA MFG.CO.,LTD.); Ribocone (manufactured by OKAWARA MFG.CO.,LTD.); Nauta mixer, Turbulizer, and Cyclomix (manufactured by Hosokawa Micron Corporation); Spiral Pin mixer (manufactured by Pacific Machinery&Engineering Co.,Ltd.); and Lodige mixer (manufactured by Matsubo Corporation).

[0156] Examples of heating and kneading machines include the following: KRC kneading machine (manufactured by Kurimoto,Ltd.); Buss co-kneading machine (manufactured by Buss Co.,Ltd.), TEM type extruder (manufactured by TOSHIBA MACHINE MACHINERY CO.,LTD.); TEX twin-screw kneading machine (manufactured by The Japan Steel Works,Ltd.); PCM kneading machine (manufactured by Ikegai Corp.); three-roll mill, mixing roll mill, and kneading machine (manufactured by INOUE MFG.,INC.); Kneadex (manufactured by Mitsui Mining&Smelting Co.,Ltd.); MS type pressure kneading machine and Kneader-Ruder (manufactured by Moriyama ManufacturingCo.,Ltd.); and Banbury mixer (manufactured by Kobe Steel,Ltd.).

[0157] Examples of the pulverizer include the following: Counter jet mill, Micron jet mill, and Inomizer (manufactured by Hosokawa Micron Corporation); IDS type mill and PJM jet mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); cross jet mill (manufactured by Kurimoto, Ltd.); Ulmax (manufactured by Nisso Engineering Co., Ltd.); SK Jet O mill (manufactured by Seishin Enterprise Co., Ltd.); Criptron (manufactured by Kawasaki Heavy Industries, Ltd.); turbo machine (manufactured by Turbo Kogyo Co., Ltd.); and super rotor (manufactured by Nisshin Engineering Inc.).

[0158] Examples of the classifier include the following: Classiel, Micron classifier, and Spedic classifier (manufactured by Seishin Enterprise Co., Ltd.); turbo classifier (manufactured by Nisshin Engineering Inc.); fine powder separator, Turboplex (ATP), and TSP separator (manufactured by Hosokawa Micron Corporation); elbow jet mill (manufactured by Nittetsu Mining Co., Ltd.); dispersion separator (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); and YM Microcut (manufactured by Yasukawa Shoji Co., Ltd.).

[0159] In addition, examples of the screening device for screening coarse particles include the following: Ultra Sonic (manufactured by Kouei-Sangyou Co., Ltd.); Rezona sieve and Gyro sieve (manufactured by Tokuju Corporation); Vibrasonic system (manufactured by Dalton Corporation); Sonicreen (manufactured by SINTOKOGIO, LTD.); turbo sieve (manufactured by Turbo Kogyo Co., Ltd.); ultrafine pulverizer (manufactured by Makino mfg.co., Ltd.); and circular vibrating screen.

[0160] From the viewpoint of the dispersibility of the external additive, it is preferable to adjust the mixing time in the external addition step to 0.5 to 10.0 minutes, and more preferably 1.0 to 5.0 minutes.

[0161] Next, the measurement methods of various physical properties will be described.

[0162] <Measurement method of number average particle diameter (D1) of primary particles of iron oxide particles>

[0163] First, observe the iron oxide particles with a transmission electron microscope. For observation, for example, a transmission electron microscope JEM2800 (manufactured by JEOL, Ltd.) can be used to calculate the particle diameter from the captured bright-field image. The image capture conditions of JEM2800 are as follows.

[0164] Disperse the iron oxide particles to be observed sufficiently in epoxy resin, and then cure them for 2 days in a temperature atmosphere of 40 °C to obtain a cured product. Use the obtained cured product as a flaky sample with an ultramicrotome (manufactured by Leica Microsystems GmbH).

[0165] Using JEM2800, obtain a transmission image under the conditions of an acceleration voltage of 200 kV, a magnification of 100,000 times, and a size of 1,024 × 1,024 pixels.

[0166] Use the image analysis software "Image-Pro Plus version 5.0" to binarize the obtained transmission image to measure the major axis diameters of 100 iron oxide particles, and use the arithmetic mean as the number average particle diameter of the primary particles.

[0167] <Measurement method of number average aggregated particle diameter of iron oxide particles on the toner surface>

[0168] Observe the surface of the toner with a scanning electron microscope to measure the number average aggregated particle diameter of the iron oxide particles. Therefore, the pulverized state of the iron oxide particles externally added to the toner surface can be observed.

[0169] For observation, use a scanning electron microscope S-4800 (manufactured by Hitachi High-Tech Corporation) to calculate the particle diameter from the captured backscattered electron image. The image capture conditions of S-4800 are as follows.

[0170] (1) S-4800 observation conditions

[0171] First, set the observation conditions of S-4800 as follows: acceleration voltage: 1.0 kV, emission current 20 μA, detection current: normal, focusing mode: UHR, and WD: 3.0 mm.

[0172] The detector (U + BSE mode) is selected and L.A.100 is selected, and observe the backscattered electron image in a field of view magnified 200,000 times.

[0173] Perform automatic brightness adjustment and save an image with a size of 1,280 × 960 pixels. Take multiple images to obtain an image in which at least 100 aggregated iron oxide particles can be analyzed.

[0174] (2) Image analysis

[0175] Use the image analysis software "Image-Pro Plus version 5.0" to binarize the transmission image to measure the major axis of 100 iron oxide particles (aggregated particles), and use the arithmetic mean as the number-average aggregated particle size of the iron oxide particles.

[0176] <Quantitative method for iron oxide particles present on the surface of toner particles>

[0177] Separate the external additive component including iron oxide particles from the toner particles, further separate the iron oxide particles, and recover them from the separated external additive component so that the iron oxide particles present on the surface of the toner particles can be quantified. Examples of specific methods include the following methods.

[0178] (1) Put 5 g of toner into a sample bottle and add 200 mL of methanol thereto. Further, add a few drops of "Contaminon N" (an aqueous solution of a 10 mass% precision measuring instrument cleaning neutral detergent containing a nonionic surfactant, an anionic surfactant, and an organic auxiliary agent and having a pH of 7, manufactured by Wako Pure Chemical Industries, Ltd.).

[0179] (2) Disperse the sample with an ultrasonic cleaner for 5 minutes to separate the external additive component.

[0180] (3) Separate the toner particles and the external additive through a suction filter (10 μm membrane filter).

[0181] (4) Perform the above steps (2) and (3) three times in total.

[0182] Through the above operations, the external additive component is separated from the toner particles. The iron oxide particles are separated and recovered by centrifuging the recovered solution with a centrifuge. Next, the solvent is removed and the obtained particles are sufficiently dried with a vacuum dryer to measure the mass of the obtained particles, thereby determining the content of iron oxide particles in 5 g of toner. Therefore, the content ratio of the iron oxide particles present on the surface of the toner particles in the toner can be determined.

[0183] <Method for measuring the fixing rate of iron oxide particles>

[0184] Weigh 20 g of “Contaminon N” (an aqueous solution of a 10% by mass neutral detergent for precision measuring instruments containing a nonionic surfactant, an anionic surfactant, and an organic auxiliary agent and having a pH of 7) into a 50 mL vial and mix it with 1 g of toner.

[0185] Place the vial in a “KM shaker” (model: V.SX, manufactured by IWAKI SANGYO CO., LTD.), set the speed to 50, and shake for 30 seconds. Thus, the unfixed iron oxide particles are transferred from the surface of the toner particles to the dispersion liquid.

[0186] Thereafter, centrifuge (trade name: H-9R, manufactured by Kokusan Co., Ltd.) for 16.67 s -1 Disperse the toner particles and the iron oxide particles transferred to the supernatant for 5 minutes. Vacuum-dry the separated toner (40 °C / 24 hours) to dry and solidify it, thereby obtaining a sample.

[0187] Granulate the toner using a press machine to use it as a sample. In the toner samples before and after the above treatment, the specific Fe element of the iron oxide particles to be analyzed is quantified by the following wavelength-dispersive X-ray fluorescence (XRF) analysis. Then, the amount of iron oxide particles remaining on the surface of the toner particles and not transferred to the supernatant through the above treatment is determined by the following formula (A), and the obtained value is defined as the fixing rate. As the value of the fixing rate, the arithmetic mean of the values obtained from 100 samples is adopted.

[0188] (i) Sample preparation

[0189] In the preparation of the sample, use a sample press machine MAEKAWA testing machine (manufactured by MFG Co., LTD.). Put 0.5 g of toner into an aluminum ring (model: 3481E1), set the load to 5.0 tons, and press the toner for 1 minute, thereby granulating the toner.

[0190] (ii) Examples of equipment used

[0191] X-ray fluorescence spectrometer 3080 (manufactured by Rigaku Corporation)

[0192] (iii) Measurement conditions

[0193] Measurement diameter: 10

[0194] Measurement potential and voltage: 50 kV, 50 to 70 mA

[0195] 2θ angle: 25.12°

[0196] Crystal plate: LiF

[0197] Measurement time: 60 seconds

[0198] (iv) Calculation method of the fixation rate of iron oxide particles

[0199] Fixation rate of iron oxide particles (%) = (Intensity of the element of iron oxide particles from the toner after treatment / Intensity of the element of iron oxide particles from the toner before treatment) × 100 (A)

[0200] <Calculation method of SP value>

[0201] The solubility parameter (SP value) is determined using the Fedors equation represented by the following equation (B).

[0202] δi = (Ev / V)1 / 2 = (Δei / Δvi)1 / 2 (B)

[0203] Ev: Evaporation energy

[0204] V: Molar volume

[0205] Δei: Evaporation energy of the atom or atomic group of component i

[0206] Δvi: Molar volume of the atom or atomic group of component i

[0207] The values of Δei and Δvi refer to the evaporation energy and molar volume (25 °C) of atoms and atomic groups described in Table 3-9 on pages 54 to 57 of "Basic Coating Science", 1986 (Maki Shoten K.K.).

[0208] In equation (B), "δi" is the SP value of the atom or atomic group of component i, and the SP value of the target substance is obtained as the sum of the SP values δi of the atoms or atomic groups of the target substance.

[0209] In the present invention, the SP value of the compound having the structure represented by formula (1) is the SP value calculated using formula (B) based on the structure of the hydrophobizing agent used to form the compound having the structure represented by formula (1) on the surface of the iron oxide particles.

[0210] In addition, the unit of the SP value is (cal / cm 3 ) 1 / 2 And it can be converted to the unit (J / m 3 ) 1 / 2 = 2.046 × 10 3 (J / m 3 ) 1 / 2 by 3 ) 1 / 2 .

[0211] <Method for Measuring Wettability of Iron Oxide Particles>

[0212] In the wettability test of iron oxide particles using a water / methanol mixed solvent, a methanol addition transmittance curve obtained by measurement using a powder wettability tester (trade name: WET-100P, manufactured by RHESCA CO., LTD.) under the following conditions and procedures is used.

[0213] First, 50 mL of water is placed in a flask, and the transmittance is measured. The transmittance at this time is set to 100%, and the transmittance in a state where no light passes through is set to 0%. Then, while continuously adding methanol to the water to increase the methanol concentration, the transmittance is measured. The concentration (mass %) of methanol when the intensity of the transmitted light during measurement is half of the intensity of the transmitted light when the light passes through water is defined as the wettability of the iron oxide particles.

[0214] Specifically, the transmittance is measured as follows.

[0215] A magnetic stirrer is placed in a beaker containing 50 mL of water. Then, 0.1 g of iron oxide particles sieved with a 100-μm opening mesh is accurately weighed and placed in the flask.

[0216] Next, stirring is started with a magnetic stirrer at a stirring speed of 300 rpm (5 revolutions per second), and methanol is continuously added to the sample solution for measurement at an addition rate of 1.3 mL / minute through a glass tube. Additionally, at this time, the transmittance of light with a wavelength of 780 nm is measured to create a methanol addition transmittance curve. The reason for using methanol as the titrant solvent at this time is that the influence of the elution of the hydrophobizing agent used for treating the surface of the iron oxide particles is small and the surface properties of the iron oxide particles can be evaluated more precisely.

[0217] In the measurement, for example, a glass beaker with a diameter of 5 cm can be used as the beaker, and a spindle-shaped beaker coated with Teflon (registered trademark) with a length of 25 mm and a maximum diameter of 8 mm can be used as the magnetic stirrer.

[0218] <Measurement of Weight-Average Particle Size (D4) and Number-Average Particle Size (D1) of Toner Particles>

[0219] The weight-average particle size (D4) and number-average particle size (D1) of toner particles are measured using the dedicated software, measurement condition setting, and measurement data analysis attached to the following equipment, with 25,000 effective measurement channels, and the measured data is analyzed and calculated.

[0220] · Equipment: A precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.) equipped with a 100-μm orifice tube and operating by the aperture resistance method

[0221] · Dedicated software: "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.)

[0222] The electrolyte aqueous solution used in the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass, and for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.) can be used.

[0223] Before performing the measurement and analysis, the dedicated software is set as follows.

[0224] In the "Change Standard Measurement Method (SOM) Screen" of the dedicated software, the total count of the control mode is set to 50,000 particles, the number of measurements is set to 1, and the value obtained by using "10.0-μm standard particles" (manufactured by Beckman Coulter, Inc.) is set as the Kd value. The threshold and noise level are automatically set by pressing the measurement button for the threshold / noise level. Additionally, the current is set to 1,600 μA, the gain is set to 2, the electrolyte solution is set to ISOTON II, and the orifice tube is ticked to be rinsed after the measurement.

[0225] In the "Pulse to Particle Size Conversion Setting Screen" of the dedicated software, the element interval is set to logarithmic particle size, the particle size element is set to 256 particle size elements, and the particle size range is set to 2 to 60 μm.

[0226] The specific measurement method is as follows.

[0227] (1) Put about 200 mL of the electrolyte aqueous solution into a 250-mL round-bottom glass beaker dedicated to Multisizer 3, set the beaker on the sample stage, and stir it counterclockwise with a stir bar at 24 revolutions per second. Then, remove the dirt and bubbles in the orifice tube through the "Orifice Tube Rinsing" function of the dedicated software.

[0228] (2) Place approximately 30 mL of an aqueous electrolyte solution into a 100 mL flat-bottom glass beaker. Add approximately 0.3 mL of a dilution obtained by diluting "Contaminon N" (an aqueous solution of a 10 mass% neutral detergent for precision measuring instruments containing a nonionic surfactant, an anionic surfactant, and an organic auxiliary agent and having a pH of 7, manufactured by Wako Pure Chemical Industries, Ltd.) 3-fold with ion-exchanged water as a dispersant to the aqueous electrolyte solution.

[0229] (3) Place a predetermined amount of ion-exchanged water into the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.) having two oscillators with an oscillation frequency of 50 kHz, a phase shift of 180°, and a power output of 120 W, and add approximately 2 mL of Contaminon N to the water tank.

[0230] (4) Set the beaker in (2) in the beaker fixing hole of the ultrasonic disperser and start the ultrasonic disperser. Then, adjust the height position of the beaker to maximize the resonance state of the liquid surface of the aqueous electrolyte solution in the beaker.

[0231] (5) While irradiating the aqueous electrolyte solution in the beaker in (4) with ultrasonic waves, gradually add and disperse approximately 10 mg of toner (particles) in the aqueous electrolyte solution. Then, continue the ultrasonic dispersion treatment for an additional 60 seconds. During the ultrasonic dispersion treatment, appropriately adjust the water temperature in the water tank so that the temperature is between 10°C and 40°C.

[0232] (6) Use a pipette to drop the aqueous electrolyte solution in (5) in which the toner particles are dispersed into the round-bottom beaker mounted on the sample stage in (1) to adjust the measurement concentration to approximately 5%. Then, perform the measurement until the number of measured particles reaches 50,000.

[0233] (7) Analyze the measurement data using the dedicated software attached to the device to calculate the weight-average particle diameter (D4). When setting the chart / volume% with the dedicated software, the "average diameter" on the analysis / volume statistical value (arithmetic mean) screen is the weight-average particle diameter (D4). Additionally, when setting the chart / number% with the dedicated software, the "average diameter" on the analysis / number statistical value (arithmetic mean) screen is the number-average particle diameter (D1).

[0234] <Method for Measuring the Half-Width of the Endothermic Peak of the Toner>

[0235] The half-value width of the endothermic peak of the toner was measured as follows using a differential scanning calorimeter "Q 1000" (manufactured by TA Instruments).

[0236] For the temperature calibration of the detection unit of the device, the melting points of indium and zinc were used, and for the heat calibration, the heat of fusion of indium was used.

[0237] As a measurement sample, 3.0 mg of the toner was accurately weighed and placed in an aluminum pan, and the empty aluminum pan was used as a reference.

[0238] After maintaining the temperature at 20 °C for 1 minute, during the first heating process, while heating from 30 °C to 200 °C at a rate of 100 °C / minute, the measurement sample was measured.

[0239] Next, after maintaining the temperature at 200 °C for 1 minute, while cooling from 200 °C to 30 °C at a rate of -100 °C / minute, the measurement was carried out.

[0240] Finally, after maintaining the temperature at 30 °C for 1 minute, while heating from 30 °C to 200 °C at a rate of 100 °C / minute, the measurement was carried out during the second heating process.

[0241] During the second heating process, the specific heat change was obtained in the temperature range of 40 to 200 °C, and the endothermic peak derived from the melting of the release agent was obtained. The melting point Tm (°C) of the release agent during the second heating process is the peak temperature of the maximum endothermic peak in the specific heat change curve, and the half-value width of the endothermic peak is the temperature width at the midpoint between the heat at the peak temperature of the maximum endothermic peak and the baseline.

[0242] <Method for Measuring IR and Calculating the [Si-O-Si] / [Si-C] Value>

[0243] The FT-IR spectrum was measured by the ATR method using the following equipment.

[0244] · Fourier transform infrared spectrophotometer (Spectrum One, manufactured by PerkinElmer Inc.) equipped with a Universal ATR Sampling Accessory

[0245] The specific measurement steps are as follows.

[0246] The incident angle of the infrared ray (λ = 5 μm) was set to 45°. A Ge ATR crystal (refractive index: 4.0) was used as the ATR crystal. Other conditions are as follows.

[0247] Range

[0248] Start: 4000 cm -1

[0249] End: 600 cm -1

[0250] Continuous

[0251] Number of scans: 16

[0252] Resolution: 4.00 cm -1

[0253] [Calculation method of hydrocarbon wax index (Ge)]

[0254] (1) Install the Ge ATR crystal in the device

[0255] (2) Weigh the toluene extract of 0.01 g of iron oxide particles on the ATR crystal

[0256] (3) Pressurize the sample with a pressure wall for measurement. (Dynamometer is 90)

[0257] (4) Perform baseline correction on the obtained FT-IR spectrum by automatic correction

[0258] (5) Calculate the ratio [Si-O-Si] / [Si-C] of the maximum absorption peak intensity [Si-O-Si] in the range of 990 to 1,040 cm -1 to the maximum absorption peak intensity [Si-C] in the range of 1,240 to 1,280 cm -1

[0259] According to the present invention, a toner can be provided that can improve the release performance in the fixing step, suppress member contamination, have a small amount of image peeling, and have excellent friction fixing properties

[0260] [Examples]

[0261] Hereinafter, the present invention will be described more specifically with reference to production examples and examples, and the present invention is not limited to these examples. All parts in the following formulations are by mass

[0262] [Production example of iron oxide particles C1]

[0263] In an aqueous solution of ferrous sulfate, a caustic soda solution, P 2 O 5 , and SiO 2 are mixed with each other in the amounts shown below to prepare an aqueous solution containing ferrous hydroxide

[0264] Caustic soda solution: 1.00 to 1.10 equivalents relative to iron element

[0265] P 2 O 5 ​: The amount equivalent to 0.15 mass % of phosphorus element relative to iron element

[0266] SiO 2 : The amount corresponding to 0.50 mass % of silicon element relative to iron element

[0267] The pH of the aqueous solution was set to 8.0, and an oxidation reaction was performed at 85° C. while blowing air, thereby preparing a slurry containing seed crystals.

[0268] Next, an aqueous solution of ferrous sulfate is added to the slurry so that its amount is 0.90 to 1.20 equivalents relative to the initial amount of alkali (sodium component of caustic soda). Thereafter, the pH of the slurry is maintained at 7.6, and an oxidation reaction is performed while blowing air, thereby obtaining a slurry containing iron oxide.

[0269] Filtration and washing were performed, and then the aqueous slurry was temporarily removed. At this time, a small amount of aqueous sample was collected, and the water content was measured.

[0270] Next, the aqueous sample was put into a separate aqueous medium without drying, and the slurry was redispersed with a centrifugal mill while centrifuging and stirring, thereby adjusting the pH of the redispersed liquid to about 9.0. Then, while stirring, an isobutyltrimethoxysilane coupling agent was added in an amount of 1.4 parts by mass relative to 100 parts by mass of the iron oxide particles (the amount of the iron oxide particles was calculated as a value obtained by subtracting the water content from the aqueous sample), and hydrolysis was performed at a liquid temperature of 45° C. Thereafter, stirring was performed sufficiently, and surface treatment was performed.

[0271] The iron oxide particles produced by the hydrophobization treatment were filtered by a filter press, the filtered particles were washed with a large amount of water, the washed particles were dried at 120° C. for 2 hours, and the obtained particles were pulverized, thereby obtaining iron oxide particles C1 having a number average particle size (D1) of 0.26 μm.

[0272] <Production Example of Iron Oxide Particles C2 to C8>

[0273] In the production example of iron oxide particles C1, the initial pH of the redispersion liquid of the slurry was set to pH (A) shown in Table 1, the hydrophobizing agent shown in Table 1 was added, hydrolysis was performed, the pH was changed to pH (B) shown in Table 1, and then, surface treatment was performed. Except for the above, iron oxide particles C2 to C8 were obtained by the same equipment and under the same conditions as in the production of iron oxide particles C1.

[0274] <Production Example of Iron Oxide Particles C9>

[0275] In the ferrous sulfate aqueous solution, caustic soda solution, P 2 O5 , and SiO 2 are mixed with each other to prepare an aqueous solution containing ferrous hydroxide.

[0276] Caustic soda solution: 1.00 to 1.10 equivalents relative to iron element

[0277] P 2 O 5 : an amount equivalent to 0.15% by mass of phosphorus element relative to iron element

[0278] SiO 2 : an amount equivalent to 0.50% by mass of silicon element relative to iron element

[0279] The pH of the aqueous solution is set to 8.0, and an oxidation reaction is carried out at 85 °C while blowing air, thereby preparing a slurry containing seeds.

[0280] Next, an aqueous solution of ferrous sulfate is added to the slurry such that its amount is 0.90 to 1.20 equivalents relative to the initial amount of base (sodium component of caustic soda). Thereafter, the pH of the slurry is maintained at 7.6, an oxidation reaction is carried out while blowing air, the pH is adjusted to 6 at the end of the oxidation reaction, and washing and drying are carried out. The obtained particles are pulverized to obtain iron oxide particles having a number average particle diameter (D1) of 0.23 μm.

[0281] As a hydrophobizing agent, 30 parts by mass of isobutyltrimethoxysilane is added dropwise to 70 parts by mass of ion-exchanged water while stirring. Thereafter, the aqueous solution is maintained at a pH of 5.5 and a temperature of 55 °C, and dispersed for 120 minutes at a circumferential speed of 0.46 m / s using a dispersion blade, and hydrolysis is carried out. Thereafter, the pH of the aqueous solution is set to 7.0, and the aqueous solution is cooled to 10 °C to stop the hydrolysis reaction. Thus, an aqueous solution containing a silane compound is obtained.

[0282] In a high-speed mixer (trade name: LFS-2 type, manufactured by Fukae Powtec Corporation), 100 parts by mass of iron oxide particles are placed, and while stirring at a rotational speed of 2,000 rpm, 8.0 parts by mass of the aqueous solution containing the silane compound is added dropwise within 2 minutes. Thereafter, mixing and stirring are carried out for 5 minutes. Next, in order to improve the fixing property of the silane compound, the mixture is dried at 40 °C for 1 hour to reduce the amount of moisture, the mixture is dried at 110 °C for 3 hours, and then, the condensation reaction of the silane compound is carried out. Thereafter, the condensate is pulverized and passed through a sieve with an opening of 100 μm, thereby obtaining iron oxide particles C9.

[0283] <Production examples of iron oxide particles C10 to C16>

[0284] In the production example of iron oxide particles C9, the type of hydrophobizing agent used was changed as shown in Table 1. Except as described above, iron oxide particles C10 to C16 were obtained using the same equipment and under the same conditions as in the production of iron oxide particles C9.

[0285] <Production example of iron oxide particles C17>

[0286] In an aqueous solution of ferrous sulfate, caustic soda solution, P 2 O 5 , and SiO 2 (in an amount equivalent to 0.50% by mass of silicon element based on iron element) were mixed with each other to prepare an aqueous solution containing ferrous hydroxide.

[0287] Caustic soda solution: 1.00 to 1.10 equivalents relative to iron element

[0288] P 2 O 5 : in an amount equivalent to 0.15% by mass of phosphorus element based on iron element

[0289] SiO 2 : in an amount equivalent to 0.50% by mass of silicon element based on iron element

[0290] The pH of the aqueous solution was set to 8.0, and an oxidation reaction was carried out at 85 °C while blowing air, thereby preparing a slurry containing seed crystals.

[0291] Next, an aqueous solution of ferrous sulfate was added to the slurry in an amount of 0.90 to 1.20 equivalents relative to the initial amount of base (sodium component of caustic soda). Thereafter, the pH of the slurry was maintained at 7.6, an oxidation reaction was carried out while blowing air, and the pH was adjusted to 6 at the end of the oxidation reaction. Thereafter, washing and drying were carried out, and the obtained particles were pulverized, thereby obtaining iron oxide particles having a number average particle diameter (D1) of 0.23 μm.

[0292] The iron oxide particles were placed in a Henschel mixer (manufactured by NIPPON COKE & ENGINEERING CO., LTD.), and while spraying in a state where the untreated iron oxide particles were dispersed at a rotational speed of 34.5 m / s, 3.8 parts by mass of dimethyl silicone oil was added, and the iron oxide particles were dispersed as they were for 10 minutes. Thereafter, iron oxide particles passing through a sieve with an opening of 100 μm were obtained as iron oxide particles C17.

[0293] <Production example of iron oxide particles C18>

[0294] Except in the production example of iron oxide particles C17, the type and amount of the hydrophobizing agent were changed to modified silicone oil KF-415 (manufactured by Shin-Etsu Silicone Co., Ltd.) and 3.8 parts by mass, respectively, and iron oxide particles C18 were obtained by the same equipment and under the same conditions as in the production example of iron oxide particles C17.

[0295] <Production Example of Iron Oxide Particles C19>

[0296] In an aqueous solution of ferrous sulfate, a caustic soda solution, P 2 O 5 、and SiO 2 were mixed with each other in the amounts shown below to prepare an aqueous solution containing ferrous hydroxide.

[0297] Caustic soda solution: 1.00 to 1.10 equivalents relative to iron element

[0298] P 2 O 5 : An amount equivalent to 0.15% by mass of phosphorus element relative to iron element

[0299] SiO 2 : An amount equivalent to 0.50% by mass of silicon element relative to iron element

[0300] The pH of the aqueous solution was set to 8.0, and an oxidation reaction was carried out at 85 °C while blowing air, thereby preparing a slurry containing seed crystals.

[0301] Next, an aqueous solution of ferrous sulfate was added to the slurry so that its amount was 0.90 to 1.20 equivalents relative to the initial amount of base (sodium component of caustic soda). Thereafter, the pH of the slurry was maintained at 7.6, and an oxidation reaction was carried out while blowing air. At the end of the oxidation reaction, the pH was adjusted to 6. Thereafter, washing and drying were carried out, and the obtained particles were pulverized, thereby obtaining iron oxide particles having a number average particle diameter (D1) of 0.23 μm.

[0302] As the hydrophobizing agent, 30 parts by mass of triisostearoyl titanate isopropyl ester was added dropwise to 70 parts by mass of ion-exchanged water while stirring. Thereafter, the aqueous solution was maintained at a pH of 5.5 and a temperature of 55 °C, and dispersed for 120 minutes at a circumferential speed of 0.46 m / s using a dispersion blade, and hydrolysis was carried out. Thereafter, the pH of the aqueous solution was set to 7.0, and the aqueous solution was cooled to 10 °C to stop the hydrolysis reaction. Thus, an aqueous solution containing a titanate compound was obtained.

[0303] In a high-speed mixer (trade name: LFS-2 type, manufactured by Fukae Powtec Corporation), 100 parts by mass of iron oxide particles are placed, and while stirring at a rotational speed of 2,000 rpm, an aqueous solution containing a titanate compound is dropped in over 2 minutes in an amount of 8.0 parts by mass. Thereafter, mixing and stirring are carried out for 5 minutes. Next, in order to improve the fixation of the titanate compound, the mixture is dried at 40°C for 1 hour to reduce the amount of moisture, the mixture is dried at 110°C for 3 hours, and then, a condensation reaction of the titanate compound is caused to proceed. Thereafter, the condensate is pulverized and passed through a sieve with an opening of 100 μm, whereby iron oxide particles C19 are obtained.

[0304] <Production Example of Iron Oxide Particles C20>

[0305] In an aqueous solution of ferrous sulfate, a caustic soda solution, P 2 O 5 、and SiO 2 are mixed with each other in the amounts shown below to prepare an aqueous solution containing ferrous hydroxide.

[0306] Caustic soda solution: 1.00 to 1.10 equivalents relative to iron element

[0307] P 2 O 5 : An amount equivalent to 0.15 mass% in terms of phosphorus element relative to iron element

[0308] SiO 2 : An amount equivalent to 0.50 mass% in terms of silicon element relative to iron element

[0309] The pH of the aqueous solution is set to 8.0, and an oxidation reaction is carried out at 85°C while blowing air, whereby a slurry containing seed crystals is prepared.

[0310] Next, an aqueous solution of ferrous sulfate is added to the slurry such that its amount is 0.90 to 1.20 equivalents relative to the initial amount of base (sodium component of caustic soda). Thereafter, the pH of the slurry is maintained at 7.6, an oxidation reaction is caused to proceed while blowing air, and the pH is adjusted to 6 at the end of the oxidation reaction. Thereafter, washing and drying are carried out, and the obtained particles are pulverized, whereby iron oxide particles having a number average particle diameter (D1) of 0.23 μm are obtained.

[0311] Next, iron oxide particles were added to a dilute sulfuric acid solution to adjust the pH to 4. Next, an aqueous solution of aluminum sulfate was gradually added dropwise and thoroughly mixed. While further continuing stirring, an aqueous solution of sodium hydroxide was gradually added dropwise to adjust the pH of the suspension to 6, and then, the suspension was aged. Thereafter, washing and drying were carried out, and the obtained particles were pulverized, whereby iron oxide particles C20 having a number average particle diameter (D1) of 0.23 μm were obtained.

[0312] <Production Example of Iron Oxide Particles C21>

[0313] In the production example of iron oxide particles C9, the type of the hydrophobizing agent was changed to tetramethoxysilane. Except as described above, iron oxide particles C21 were obtained by the same equipment and under the same conditions as in the production example of iron oxide particles C9.

[0314] <Production Example of Iron Oxide Particles C22>

[0315] In the production example of iron oxide particles C17, the type and the amount used of the hydrophobizing agent were changed to hexamethyldisilazane and 3.8 mass parts, respectively. Except as described above, iron oxide particles C22 were obtained by the same equipment and under the same conditions as in the production example of iron oxide particles C17.

[0316] <Production Example of Iron Oxide Particles C23>

[0317] In an aqueous solution of ferrous sulfate, a caustic soda solution, P 2 O 5 、and SiO 2 were mixed with each other in the amounts shown below to prepare an aqueous solution containing ferrous hydroxide.

[0318] Caustic soda solution: 1.00 to 1.10 equivalents relative to iron element

[0319] P 2 O 5 : An amount equivalent to 0.15 mass% in terms of phosphorus element relative to iron element

[0320] SiO 2 : An amount equivalent to 0.50 mass% in terms of silicon element relative to iron element

[0321] The pH of the aqueous solution was set to 8.0, and an oxidation reaction was carried out at 85 °C while blowing air, whereby a slurry containing seeds was prepared.

[0322] Next, an aqueous solution of ferrous sulfate is added to the slurry so that its amount is 0.90 to 1.20 equivalents relative to the initial alkali amount (sodium component of caustic soda). Thereafter, the pH of the slurry is maintained at 7.6, an oxidation reaction is carried out while blowing air, and the pH is adjusted to 6 at the end of the oxidation reaction. Thereafter, washing and drying are performed, and the obtained particles are pulverized to obtain iron oxide particles C23 having a number average particle diameter (D1) of 0.23 μm. The iron oxide particles C23 are iron oxide particles that have not been surface treated.

[0323] [Table 1]

[0324]

[0325] The physical property values ​​of the iron oxide particles C1 to C23 produced as described above are shown in Table 2, the physical property values ​​being determined by the above methods.

[0326] [Table 2]

[0327]

[0328] <Production Example of Magnetic Material (Colorant)>

[0329] To 92L Fe 2+ 88 L of 3.74 mol / L sodium hydroxide aqueous solution was added to the 1.79 mol / L ferrous sulfate aqueous solution, and mixed and stirred while blowing air at 20 L / min so as to maintain the temperature and pH at 89° C. and 9 to 12, respectively. After mixing and stirring for 30 minutes, the slurry was filtered, washed, and dried to obtain magnetic body particles.

[0330] <Production Example of Toner Particles A1>

[0331] Prepare the following ingredients.

[0332] · Amorphous polyester resin (PES) (amorphous polyester resin obtained by condensation reaction of ethylene oxide and propylene oxide adducts of bisphenol A with terephthalic acid, Mw=9,500, Tg=58° C.) 100 parts by mass

[0333] Magnetic material (colorant) 95 parts by mass

[0334] (Number average particle size (D1): 0.20 μm, magnetic properties (σs: 65.9 Am 2 / kg,σr:7.3Am 2 / kg), without surface treatment)

[0335] Release agent B1 (behenyl behenate, melting point: 75°C) 5.0 parts by mass

[0336] · 2.0 parts by mass of an iron complex of a monoazo dye (T-77, manufactured by Hodogaya Chemical Co., Ltd.)

[0337] These raw materials were premixed by a Henschel mixer FM10C (manufactured by Mitsui Miike Chemical Engineering Machinery Co., Ltd.). Thereafter, the raw materials were kneaded by a twin-screw kneader (trade name: PCM-30, manufactured by Ikegai Corp.) by setting the rotation speed to 250 rpm and adjusting the temperature so that the direct temperature near the outlet of the kneaded product was 145°C.

[0338] The obtained melt-kneaded product was cooled, and the cooled melt-kneaded product was coarsely pulverized by a chopper. Thus, the obtained coarsely pulverized product was finely pulverized by a Turbo T-250 (manufactured by Turbo Kogyo Co., Ltd.) at a feed rate of 25 kg / hr by adjusting the air temperature so that the exhaust temperature was 38°C, and classified using a multi-stage classifier utilizing the wall effect. As a result, toner particles A1 with a weight-average particle diameter (D4) of 8.4 μm were obtained.

[0339] <Production Examples of Toner Particles A2 to A4>

[0340] In the production example of toner particles A1, the type of release agent used was changed as shown in Table 3. Except for the above, toner particles A2 to A4 were obtained by the same equipment and under the same conditions as in the production example of toner particles A1.

[0341] <Production Example of Toner Particles A5>

[0342] Prepare the following raw materials.

[0343] · 100.0 parts by mass of styrene / butyl acrylate copolymer 1 (StAc) (styrene acrylic resin (mass ratio of styrene to butyl acrylate: 78:22), Mw = 8,500, Tg = 58°C)

[0344] · Magnetic material (number-average particle diameter (D1): 0.20 μm, magnetic properties (σs: 65.9 A·m 2 / kg, σr: 7.3 A·m 2 / kg), not surface-treated) 95.0 parts by mass

[0345] · 5.0 parts by mass of release agent B1 (behenyl behenate, melting point: 75°C)

[0346] ·Iron complex of monoazo dye (trade name: T-77, manufactured by Hodogaya Chemical Co., Ltd.) 2.0 parts by mass

[0347] These raw materials were processed using the same equipment and under the same conditions as in the production example of toner particles A1, whereby toner particles A5 were obtained.

[0348] <Production of toner particles A6 to A8>

[0349] In the production example of toner particles A5, the release agent used was changed as shown in Table 3. Except as described above, toner particles A6 to A8 were obtained using the same equipment and under the same conditions as in the production example of toner particles A5.

[0350] <Production example of toner particles A9>

[0351] Toner particles A9 were produced by the emulsion aggregation method according to the following steps.

[0352] Styrene, butyl acrylate, acrylic acid, and lauryl mercaptan were mixed and dissolved in amounts of 89.5 parts, 9.2 parts, 1.3 parts, and 3.2 parts, respectively. An aqueous solution was prepared by mixing 1.5 parts of Neogen RK (manufactured by DKS Co., Ltd.) with 150 parts of ion-exchanged water, and the mixture was added to the above-prepared mixed solution and dispersed therein.

[0353] An aqueous potassium persulfate solution was prepared by mixing 0.3 part of potassium persulfate with 10 parts of ion-exchanged water. The aqueous potassium persulfate solution was added while stirring slowly for 10 minutes.

[0354] After purging with nitrogen, emulsion polymerization was carried out at 70 °C for 6 hours. After completion of the polymerization, the reaction solution was cooled to room temperature and ion-exchanged water was added, whereby a dispersion of binder resin particles having a solid content concentration of 12.5 mass% and a volume-based median diameter of 0.2 μm was obtained.

[0355] A release agent (100 parts) (Fischer-Tropsch wax, melting point: 77 °C) and Neogen RK (15 parts) were mixed in 385 parts of ion-exchanged water, and the mixture was dispersed using a wet jet mill JN100 (manufactured by JOKOH CO., LTD.) for about 1 hour, whereby a release agent dispersion was obtained. The solid content concentration of the release agent dispersion was 20 mass%.

[0356] Magnetic iron oxide particles (100 parts) and Neogen SC (10.0 parts) were mixed in 890 parts of ion-exchanged water, and the mixture was dispersed using a wet jet mill JN100 for about 1 hour, whereby a magnetic iron oxide dispersion was obtained.

[0357] A binder resin particle dispersion (265 parts), a release agent dispersion (10 parts), and a magnetic iron oxide dispersion (65 parts) were placed in a container, and the mixture was dispersed using a homogenizer (trade name: Ultra Turrax T50, manufactured by IKA Works Inc.).

[0358] While stirring the mixture, the temperature in the container was adjusted to 30 °C, and 1 mol / L hydrochloric acid was added to adjust the pH to 5.0. After standing for 3 minutes, heating was started and the temperature was raised to 50 °C to produce aggregated particles. In this state, the particle size of the aggregated particles was measured by "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.). When the weight-average particle size of the aggregated particles was 6.2 μm, 1 mol / L aqueous sodium hydroxide solution was added and the pH was adjusted to 8.0 to stop particle growth.

[0359] Thereafter, the temperature was raised to 95 °C to melt and spheroidize the aggregated particles. When the average circularity reached 0.980, cooling was started and the temperature was lowered to 30 °C, thereby obtaining a toner particle dispersion.

[0360] Hydrochloric acid was added to the obtained toner particle dispersion to adjust the pH to 1.5 or less, and the mixture was stirred and allowed to stand for 1 hour, and then solid-liquid separation was performed using a pressure filter, thereby obtaining a toner filter cake.

[0361] The toner filter cake was repulped into a dispersion with ion-exchanged water, and the dispersion was subjected to solid-liquid separation using the above filter. Repulping and solid-liquid separation were repeated until the conductivity of the filtrate was 5.0 μS / cm or less, and then final solid-liquid separation was performed, thereby obtaining a toner filter cake.

[0362] The obtained toner filter cake was dried using a pneumatic dryer (pneumatic jet dryer, manufactured by Seishin Enterprise Co., Ltd.). Drying was performed under the condition that the blowing temperature was 90 °C. The outlet temperature of the dryer was 40 °C, and the supply rate of the toner filter cake was adjusted so that the outlet temperature did not deviate from 40 °C depending on the water content of the toner filter cake.

[0363] In addition, fine coarse powder was cut using a multi-stage classifier utilizing the wall effect to obtain toner particles A9. The weight-average particle size (D4) of the toner particles A9 was 8.4 μm, the average circularity of the toner particles A9 was 0.980, and the glass transition temperature (Tg) of the toner particles A9 was 57 °C.

[0364] <Production Examples of Toner Particles A10 to A12>

[0365] In the production example of toner particles A5, the type and amount of the release agent used were changed as shown in Table 3. Except as described above, toner particles A10 to A12 were obtained using the same equipment and under the same conditions as in the production example of toner particles A5.

[0366] <Production Example of Toner Particles A13>

[0367] In the production example of toner particles A4, the amount of the release agent used was changed as shown in Table 3. Except as described above, toner particles A13 were obtained using the same equipment and under the same conditions as in the production example of toner particles A4.

[0368] The types of release agents used for producing toner particles A1 to A13 and the respective physical properties determined by the above method are shown in Table 3. Regarding toner particles A1 to A13, the production conditions and the respective physical properties determined by the above method are shown in Table 4.

[0369] [Table 3]

[0370] Release agent Type Molecular weight Melting point (°C) <![CDATA[SP value ((cal / cm 3 ) 1 / 2 )]]> B1 Behenyl behenate 649 75 8.59 B2 Ethylene glycol dilaurate 426 55 8.97 B3 Ethylene glycol distearate 594 72 8.85 B4 Polyethylene 1194 94 8.45 B5 Fischer-Tropsch wax 283 77 8.11 B6 Carnauba wax 675 83 8.57 B7 Dipentaerythritol hexalaurate 1348 78 9.14

[0371] [Table 4]

[0372]

[0373] <Production Example of Toner 1>

[0374] Using an FM mixer (trade name: FM-10B, manufactured by NIPPON COKE & ENGINEERING CO., LTD.), 100 parts of toner particles A1 and 1 part of hydrophobic silica particles were mixed for 5 minutes under the condition of a rotational speed of 3,500 rpm. In the production of the hydrophobic silica particles, 3-aminopropyltriethoxysilane and dimethyl silicone oil were used as the hydrophobizing agents.

[0375] Next, 2.0 parts of iron oxide particles C1 were injected into the FM mixer and mixed for 5 minutes under the condition of a rotational speed of 3,000 rpm, thereby obtaining a toner mixture.

[0376] Thereafter, coarse particles were removed using a 300-mesh sieve (opening 48 μm) to obtain toner 1.

[0377] <Production Examples of Toners 2 to 16>

[0378] In the production example of toner 1, and as shown in Table 5, the type of iron oxide particles used was changed. Except as described above, toners 2 to 16 were obtained using the same equipment and under the same conditions as in the production example of toner 1.

[0379] <Production Examples of Toners 17 to 23>

[0380] In the production example of toner 1, the types of toner particles and iron oxide particles used were changed as shown in Table 5. Except for the above, toners 17 to 23 were obtained using the same equipment and under the same conditions as in the production example of toner 1.

[0381] <Production Examples of Toners 24 to 29>

[0382] In the production example of toner 1, the type of toner particles used was changed to toner particle A5, the type of iron oxide particles used was changed to iron oxide particle C13, and the amount of iron oxide particles used was changed as shown in Table 5. Except for the above, toners 24 to 29 were obtained using the same equipment and under the same conditions as in the production example of toner 1.

[0383] <Production Example of Toner 30>

[0384] Using an FM mixer (trade name: FM-10B, manufactured by NIPPON COKE&ENGINEERING CO., LTD.), 100 parts of toner particle A5 and 1 part of hydrophobic silica particles were mixed for 5 minutes under the condition of a rotation speed of 3,500 rpm. In the production of the hydrophobic silica particles, 3-aminopropyltriethoxysilane and dimethyl silicone oil were used as the hydrophobizing agents.

[0385] Next, 0.1 part of iron oxide particle C5 was injected into the FM mixer and mixed for 3 minutes under the condition of a rotation speed of 3,200 rpm to obtain a toner mixture.

[0386] Thereafter, coarse particles were removed using a 300-mesh sieve (opening 48 μm) to obtain toner 30.

[0387] <Production Examples of Toners 31 to 34>

[0388] In the production example of toner 30, the conditions for the external addition treatment of the iron oxide particles were changed as shown in Table 5. Except for the above, toners 31 to 34 were obtained using the same equipment and under the same conditions as in the production example of toner 30.

[0389] <Production Example of Toner 35>

[0390] In the production example of toner 34, the type of toner particles used was changed to toner particle A9. Except for the above, toner 35 was obtained using the same equipment and under the same conditions as in the production example of toner 34.

[0391] <Comparative Example>

[0392] <Production Examples of Toners 36 to 42>

[0393] In the production example of Toner 1, the types of toner particles and iron oxide particles used were changed as shown in Table 5. Except for the above, Toners 36 to 42 were obtained using the same equipment and under the same conditions as in the production example of Toner 1.

[0394] [Table 5]

[0395]

[0396] Regarding each toner produced as described above, the values of each physical property determined by the above method are shown in Table 6.

[0397] [Table 6]

[0398]

[0399] <Evaluation>

[0400] For the evaluation of the fixing property of high-speed machines, an HP LaserJet Enterprise M609dn with a processing speed modified to 500 mm / second was used. In addition, by connecting an external power supply for modification, the transfer bias was changed, and the fixing film contamination, friction fixing property, and transfer defects were evaluated as follows.

[0401] <Evaluation 1: Evaluation of Fixing Film Contamination>

[0402] The fixing film contamination was evaluated by continuously outputting 50 solid black images in a normal humidity and normal temperature environment and then immediately outputting 3 solid white images, and the contamination degree of the solid white images was determined.

[0403] When fixing high print rate images such as solid black images, a part of the toner that cannot be released from the fixing film adheres to the fixing film. When a solid white image is immediately printed, thereafter, the toner remaining on the fixing film is transferred to the paper and becomes apparent as a contaminant on the paper.

[0404] The solid white images obtained as described above were observed with an optical microscope and evaluated based on the following criteria. The evaluation results are shown in Table 6.

[0405] A: No contamination was observed.

[0406] B: Only contaminated spots were observed.

[0407] C: Two or more slightly contaminated spots were observed.

[0408] D: Contamination was observed, but slight contamination was observed over the entire surface, or clear contamination that was immediately visible was observed.

[0409] <Evaluation 2: Evaluation of Frictional Fixing Property>

[0410] The frictional fixing property was evaluated by outputting a solid black image in a normal humidity and normal temperature environment and measuring the density reduction rate before and after rubbing with a wiper.

[0411] The abrasion resistance of the fixed image was tested using a wiper (product name: MONO, manufactured by TOMBOW PENCIL CO., LTD.) with a load of 300 g. The density reduction rate before and after rubbing the solid image back and forth 10 times with the wiper was measured, and the frictional fixing property was evaluated based on the following criteria. The lower the reduction rate, the better the frictional fixing property. The evaluation results are shown in Table 6.

[0412] A: The density reduction rate was 0 to 3.0%.

[0413] B: The density reduction rate was 3.1 to 10.0%.

[0414] C: The density reduction rate was 10.1 to 15.0%.

[0415] D: The density reduction rate was 15.1% or more.

[0416] <Evaluation 3: Evaluation of Transfer Defects>

[0417] Generally, when the transfer bias is high, discharge is likely to occur, and transfer defects can be evaluated strictly.

[0418] In addition, generally, in the case of using thick paper placed in a high humidity environment, the transfer property is strict.

[0419] Thick paper (95 g / m 2 , manufactured by Canon Inc.) was used, and 1,500 image prints were made in an intermittent mode of a single horizontal line at a printing rate of 2% in a high temperature and high humidity environment (32.5 °C / 80% RH) under a normal transfer bias (0.5 kV). After printing 1,500 images, a solid black image was output. Thereafter, the transfer bias was set to 1.5 kV, and a solid black image was output.

[0420] By changing the transfer bias to 1.5 kV and visually observing the output solid black image, the transfer defects were evaluated based on the following criteria. The evaluation results are shown in Table 6.

[0421] A: No transfer defects were observed.

[0422] B: Density non-uniformity was partially observed.

[0423] C: Non-uniform concentration was observed over the entire surface.

[0424] D: White blank portions were observed on the solid black image.

[0425] [Table 7]

[0426]

[0427] While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be accorded the broadest interpretation so as to cover all such modifications as well as equivalent structures and functions.

Claims

1. A toner, characterized in that, it comprises: toner particles containing a binder resin, a release agent, and a colorant; and iron oxide particles present on the surface of the toner particles, wherein the iron oxide particles have a surface containing a compound having a structure represented by the following formula (1), R-SiO 3 / 2 (1) wherein, R represents a hydrocarbon group having 1 or more carbon atoms, the fixing rate of the iron oxide particles to the toner particles is 50 to 80%, and the content ratio of the iron oxide particles relative to the total amount of the toner is 0.50 to 4.00% by mass.

2. The toner according to claim 1, wherein the difference between the SP value of the binder resin and the SP value of the release agent is 1.50 or more, and the unit of the SP value is (cal / cm 3 ) 1 / 2 , and the SP value is calculated by the Fedors method.

3. The toner according to claim 1 or 2, wherein the difference between the SP value of the mold release agent and the SP value of the compound having the structure represented by the formula (1) is 1.20 or less, and the unit of the SP value is (cal / cm 3 ) 1 / 2 , and the SP value is calculated by the Fedors method.

4. The toner according to claim 1 or 2, wherein in the endothermic curve obtained by measuring using a differential scanning calorimeter DSC with both the heating rate and the cooling rate being 100 °C / minute, the half-value width of the endothermic peak in the second heating process is 4.0 to 8.0 °C.

5. The toner according to claim 1 or 2, wherein when 0.1 g of the iron oxide particles are suspended in 50 mL of a methanol / water mixed solvent, the transmittance of light with a measurement wavelength of 780 nm is measured, and when the value of the methanol concentration when the transmittance is 50% is defined as the wettability of the iron oxide particles, the wettability is 40 to 80 vol%.

6. The toner according to claim 1 or 2, wherein in the Fourier transform infrared (FT-IR) spectrum of the components extracted from the iron oxide particles with toluene, the ratio [Si-O-Si] / [Si-C] of the maximum absorption peak intensity [Si-O-Si] in the range of 990 to 1,040 cm -1 to the maximum absorption peak intensity [Si-C] in the range of 1,240 to 1,280 cm -1 is 1.4 to 1.

7.

7. The toner according to claim 1 or 2, wherein when observing the near-edge X-ray absorption fine structure NEXAFS of the iron oxide particles by measurement using soft X-ray through the total electron yield TEY method, the obtained absorption spectrum of Si has a peak A in the range of 1,844.4 to 1,844.8 eV and a peak B in the range of 1,846.1 to 1,846.6 eV, and IA / (IA + IB) / MSi is 40 to 55 g / mol, where IA is the area of the peak A, IB is the area of the peak B, and MSi is the number of moles of Si derived from the silane compound contained in 1 g of the iron oxide particles.

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