Non-magnetic one component toner, image forming apparatus, and method for producing toner

Abstract

To provide a nonmagnetic one component toner capable of forming an image with few white streaks and density unevenness.SOLUTION: The non-magnetic one component toner contains toner particles. The toner particles each include a toner mother particle and an external additive attached to a surface of the toner mother particle. The external additive includes silica particles, resin particles, and negatively chargeable lubricating particles. A detachment ratio DSi of the silica particles, a detachment ratio DR of the polymer particles, and a detachment ratio DN of the negatively chargeable lubricating particles, which are measured by subjecting the toner particles to an ultrasonic treatment at a frequency of 28kHz for 5 minutes, satisfy Formula (1) "DSi <DR <DN" is satisfied.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a non-magnetic single-component toner, an image forming apparatus, and a method for producing the toner. [Background technology]

[0002] Dry development methods include two-component development methods and one-component development methods. Two-component development methods use a two-component developer containing toner and carrier. One-component development methods use a one-component developer containing toner but not carrier. Because no carrier is used, one-component development methods have the advantage of not causing carrier deterioration or fluctuations in the mixture ratio of toner and carrier. One-component development methods also have the advantage of making image forming apparatuses easier to maintain and more compact. For this reason, various one-component developers for use in one-component development methods have been studied. For example, an external additive is added to the toner base particles of the positively charged toner for non-magnetic one-component development described in Patent Document 1. This external additive has an average particle diameter of 200 nm to 1000 nm and an electrical resistivity of 1×10 15 It contains negatively charged resin particles of Ω·cm or less, silica with an average particle size of 50nm to 300nm, silica with an average particle size of 5nm or more but less than 50nm, and polytetrafluoroethylene microparticles with an average particle size of 100nm to 1000nm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-180910 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the positively charged toner for non-magnetic one-component development described in Patent Document 1 is insufficient in terms of forming images with fewer white streaks and density unevenness.

[0005] The present invention has been made in view of the above-mentioned problems, and its object is to provide a non-magnetic single-component toner, an image forming apparatus, and a method for manufacturing the toner, which are capable of forming images with fewer white streaks and density unevenness. [Means for solving the problem]

[0006] The non-magnetic single-component toner according to the present invention includes toner particles. The toner particles include toner base particles and external additives attached to the surfaces of the toner base particles. The external additives include silica particles, resin particles, and negatively chargeable lubricating particles. The toner particles are subjected to ultrasonic treatment at a frequency of 28 kHz for 5 minutes, and the detachment rate DSi of the silica particles, the detachment rate DR of the resin particles, and the detachment rate DN of the negatively chargeable lubricating particles are measured and satisfy the following formula (1): DSi <DR<DN ···(1)

[0007] The image forming apparatus according to the present invention includes a toner, an image carrier, and a developing unit that supplies the toner to an electrostatic latent image formed on the surface of the image carrier. The developing unit includes a toner carrier that carries the toner in the form of a toner layer, and a regulating member that contacts the toner layer on the toner carrier and regulates the thickness of the toner layer. The toner is the non-magnetic single-component toner.

[0008] The toner manufacturing method according to the present invention includes an external addition step of attaching the external additive to the surface of the toner base particles to obtain a toner containing the toner particles. The toner is the non-magnetic one-component toner. [Effects of the Invention]

[0009] The non-magnetic one-component toner and image forming apparatus according to the present invention can form images with fewer white streaks and density unevenness. The toner produced by the production method according to the present invention can form images with fewer white streaks and density unevenness. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 10 is a diagram showing an image forming apparatus according to a third embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the image carrier and the developing unit shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described. First, the terms used in this specification will be described. A non-magnetic single-component toner is an aggregate (e.g., powder) of toner particles. An external additive is an aggregate (e.g., powder) of external additive particles. Unless otherwise specified, evaluation results (e.g., values ​​indicating shape and physical properties) of powders (e.g., powders of toner particles and powders of external additive particles) are the number averages of values ​​measured for each of a considerable number of particles selected from the powder. Unless otherwise specified, the softening point (Tm) is a value measured using a high-speed flow tester (Shimadzu Corporation, CFT-500D). In the S-shaped curve (horizontal axis: temperature, vertical axis: stroke) measured using the high-speed flow tester, the temperature at which "(baseline stroke value + maximum stroke value) / 2" is obtained corresponds to the softening point. Volume median diameter (D 50Unless otherwise specified, the mean diameter is the median diameter measured using a laser diffraction / scattering particle size analyzer (e.g., Beckman Coulter's "Multisizer 3"). Unless otherwise specified, the number-average primary particle diameter is the number average of the equivalent circle diameters of primary particles (Heywood diameter: the diameter of a circle with the same area as the projected area of ​​a primary particle) measured using a scanning electron microscope. Unless otherwise specified, the strength of chargeability is the ease of triboelectric charging relative to a standard carrier provided by the Imaging Society of Japan. For example, the test object is triboelectrically charged by stirring it with standard carriers provided by the Imaging Society of Japan (anionic: N-01, cationic: P-01). For example, a Q / m meter (Trek's "MODEL 212HS") is used to measure the amount of charge per unit mass of the test object before and after triboelectric charging. The greater the change in the amount of charge per unit mass before and after triboelectric charging, the stronger the chargeability of the test object. Unless otherwise specified, the "main component" of a material refers to the component that is contained in the largest amount in the material by mass. Unless otherwise specified, the relative humidity is a value measured in accordance with JIS (Japanese Industrial Standards) Z8806:2001. Hereinafter, the compound name may be followed by "based" to collectively refer to the compound and its derivatives. When the compound name is followed by "based" to refer to the name of a polymer, it means that the repeating unit of the polymer is derived from the compound or its derivative. Acrylic and methacrylic may be collectively referred to as "(meth)acrylic." Each component described in this specification may be used alone or in combination of two or more. The terms used in this specification have been explained above.

[0012] [First embodiment: non-magnetic single-component toner] The first embodiment of the present invention relates to a non-magnetic one-component toner. The non-magnetic one-component toner of the present invention contains toner particles. The toner particles include toner mother particles and an external additive attached to the surface of the toner mother particles. The external additive includes silica particles, resin particles, and negatively charged lubricating particles. The desorption rate DSi of the silica particles, the desorption rate DR of the resin particles, and the desorption rate DN of the negatively charged lubricating particles, measured by subjecting the toner particles to ultrasonic treatment at a frequency of 28 kHz for 5 minutes, satisfy the formula (1) "DSi < DR < DN".

[0013] Hereinafter, the "non-magnetic one-component toner" may be simply referred to as "toner". The act of "subjecting the toner particles to ultrasonic treatment at a frequency of 28 kHz for 5 minutes" may be referred to as "predetermined ultrasonic treatment".

[0014] By having the above configuration, the toner of the present invention can form an image with less white streaks and density unevenness. The reason is speculated as follows. Hereinafter, referring to FIGS. 1 and 2, the reason will be explained. FIG. 1 is a diagram showing an image forming apparatus 1 according to a third embodiment described later. FIG. 2 is a diagram showing an enlarged view of the image carrier 23 and the developing unit 22 shown in FIG. 1.

[0015] To facilitate understanding, we will first provide an overview of the developing unit 22, which employs a non-magnetic single-component development method. As shown in FIG. 1, the image forming apparatus 1 includes the developing unit 22 and an image carrier 23. As shown in FIG. 2, the developing unit 22 includes a storage frame 210, a supply roller 220, a toner carrier 230, and a restricting member 240. The storage frame 210 accommodates toner T therein. At a nip N1 between the supply roller 220 and the toner carrier 230, the supply roller 220 supplies the toner T accommodated in the storage frame 210 to the toner carrier 230. The toner carrier 230 retains the toner T supplied from the supply roller 220 on its surface (peripheral surface) 230a in the form of a toner layer (a so-called thin toner layer). If the toner layer is thick, only the area near the surface of the toner layer is charged, making it difficult to uniformly charge the entire toner layer. Therefore, in order to thin the toner layer, the regulating member 240 contacts the toner layer held on the surface 230a of the toner carrier 230 at a predetermined pressure in the nip N2 between the regulating member 240 and the toner carrier 230, thereby regulating the thickness of the toner layer. Regulating the thickness of the toner layer means adjusting the thickness of the toner layer to a predetermined uniform value. After the thickness is regulated, the toner T contained in the toner layer is supplied from the surface 230a of the toner carrier 230 to the electrostatic latent image formed on the surface (circumferential surface) 23a of the image carrier 23. The electrostatic latent image is then developed into a toner image. The above has described an overview of the developing unit 22 that employs a non-magnetic one-component development method.

[0016] Here, at nip N1, toner T on supply roller 220 comes into contact with toner carrier 230, causing toner T to be triboelectrically charged. At nip N2, toner T on toner carrier 230 comes into contact with regulating member 240, causing toner T to be further triboelectrically charged. However, if toner T is not charged to a desired level due to these triboelectric charges, density unevenness may occur in the formed image.

[0017] Also, in nip N2, when the regulating member 240 contacts the toner layer on the toner carrier 230, the toner T contained in the toner layer may adhere to and stick to the regulating member 240. If the thickness of the toner layer is regulated by the regulating member 240 to which the toner T has stuck, white streaks may occur in the formed image.

[0018] Therefore, in the toner T of the present embodiment, the desorption rate DSi of the silica particles, the desorption rate DR of the resin particles, and the desorption rate DN of the negatively charged lubricating particles satisfy the formula (1) "DSi < DR < DN". Among the desorption rates DSi, DR, and DN, the desorption rate DN of the negatively charged lubricating particles is the highest, so that the desorbed negatively charged lubricating particles remain in the developing unit 22. By being rubbed against the negatively charged lubricating particles remaining in the developing unit 22, the toner T is sufficiently charged to a positive polarity. Also, the torque required to drive the developing unit 22 is reduced by the desorbed negatively charged lubricating particles, and the temperature rise of the developing unit 22 is suppressed. As a result, the thermal stress on the toner T in the developing unit 22 is reduced, and the toner T is sufficiently charged without deteriorating. As a result of these, the toner T is charged to a desired value, and uneven density in the formed image can be suppressed from occurring.

[0019] Also, among the desorption rates DSi, DR, and DN, the desorption rate DN of the negatively charged lubricating particles is the highest, so that the desorbed negatively charged lubricating particles adhere to the regulating member 240, and the regulating member 240 is coated with the negatively charged lubricating particles. As a result, it is possible to suppress the toner T from adhering to and sticking to the regulating member 240, and it is possible to suppress the occurrence of white streaks in the formed image.

[0020] On the other hand, the silica particles tend to scrape off the negatively charged lubricating particles adhering to the regulating member 240. Therefore, among the desorption rates DSi, DR, and DN, the desorption rate DSi of the silica particles is made the lowest. By making the desorption rate DSi the lowest, the silica particles do not excessively scrape off the negatively charged lubricating particles adhering to the regulating member 240. Since a sufficient amount of negatively charged lubricating particles coat the regulating member 240, it is difficult for the toner T to adhere to the regulating member 240, and the occurrence of white streaks in the formed image can be suppressed.

[0021] Also, although the negative charge property of the resin particles is lower than that of the negatively charged lubricating particles, it tends to be higher than that of the silica particles. If the detachment rate DR of the resin particles is higher than the detachment rate DSi of the silica particles (that is, if "DSi < DR" is satisfied), the toner T is further charged to the positive polarity due to the friction with the detached resin particles. As a result, the toner T is charged to a desired value, and it is possible to suppress the occurrence of density unevenness in the formed image.

[0022] Also, the silica particles enhance the fluidity of the toner T and promote the triboelectric charging of the toner T. Further, the resin particles attached to the toner mother particles function as spacers and suppress the silica particles from being buried in the toner mother particles. If the detachment rate DR of the resin particles is lower than the detachment rate DN of the negatively charged lubricating particles (that is, if "DR < DN" is satisfied), the resin particles do not detach too much from the toner mother particles and are sufficiently attached to the toner mother particles. The resin particles attached to the toner mother particles can function sufficiently as spacers and suppress the silica particles from being buried in the toner mother particles. As a result, the triboelectric charging of the toner T is promoted, and it is possible to suppress the occurrence of density unevenness in the formed image.

[0023] In addition, if the detachment rate DR of the resin particles is lower than the detachment rate DN of the negatively charged lubricating particles (that is, if "DR < DN" is satisfied), and the resin particles attached to the toner mother particles function sufficiently as spacers, it is also possible to suppress the occurrence of fogging and density defects in the formed image.

[0024] As described above, with reference to FIGS. 1 and 2, the reason why the toner of the present invention can form an image with few white streaks and density unevenness has been explained.

[0025] The toner of the present invention is particularly suitable for use as a toner containing a release agent. The above-mentioned white streaks tend to occur particularly when an image is formed using a toner containing a release agent. To reduce the size and cost of the fixing unit of an image forming apparatus, a fixing unit that does not include a fixing oil application mechanism or that applies a reduced amount of fixing oil may be used. To suppress offset to such a fixing unit, a release agent may be incorporated into the toner. However, if a large amount of release agent is incorporated into the toner, the amount of release agent on the toner surface increases, making the toner more likely to adhere to the regulating member due to mechanical and thermal effects. For these reasons, when an image is formed using a toner containing a release agent, white streaks tend to occur particularly in the formed image. As already mentioned, the toner of the present invention can suppress the occurrence of white streaks in the formed image. Therefore, the toner of the present invention can be particularly suitable for use as a toner containing a release agent.

[0026] <Toner particles> The toner particles contained in the toner include toner base particles and an external additive. The external additive is attached to the surface of the toner base particles. The toner base particles are, for example, non-capsule toner particles that do not have a shell layer. However, the toner base particles may also be encapsulated toner particles that include a toner core and a shell layer that covers the toner core. The toner particles do not contain magnetic powder and are used as a toner without being mixed with a carrier (i.e., a non-magnetic one-component toner). The toner containing the toner particles is suitably used, for example, as a positively charged toner for developing electrostatic latent images.

[0027] <External additives> The external additive contains silica particles, resin particles, and negatively chargeable lubricating particles as external additive particles. The negative chargeability of the negatively chargeable lubricating particles is higher than the negative chargeability of the resin particles. The negative chargeability of the resin particles is higher than the negative chargeability of the silica particles. The silica particles are preferably positively chargeable.

[0028] As described above, the desorption rate DSi of silica particles, the desorption rate DR of resin particles, and the desorption rate DN of negatively charged lubricating particles satisfy the formula (1) "DSi < DR < DN". The desorption rate DSi of silica particles can be adjusted, for example, by changing one or both of the number-average primary particle diameter SSi of silica particles and the stirring time TSi between toner mother particles and silica particles in the external addition step. The desorption rate DR of resin particles can be adjusted, for example, by changing one or both of the number-average primary particle diameter SR of resin particles and the stirring time TR between toner mother particles and resin particles in the external addition step. The desorption rate DN of negatively charged lubricating particles can be adjusted, for example, by changing one or both of the number-average primary particle diameter SN of negatively charged lubricating particles and the stirring time TN between toner mother particles and negatively charged lubricating particles in the external addition step.

[0029] Hereinafter, the measurement methods for the desorption rate DSi of silica particles, the desorption rate DR of resin particles, and the desorption rate DN of negatively charged lubricating particles will be described. The desorption rate DSi of silica particles, the desorption rate DR of resin particles, and the desorption rate DN of negatively charged lubricating particles are measured by performing a predetermined ultrasonic treatment. The predetermined ultrasonic treatment is carried out by subjecting a dispersion obtained by dispersing 2 parts by mass of toner particles in 100 parts by mass of an aqueous solution of a nonionic surfactant with a concentration of 2% by mass to ultrasonic treatment at a frequency of 28 kHz for 5 minutes using an ultrasonic disperser. After the predetermined ultrasonic treatment, the toner particles after the predetermined ultrasonic treatment are taken out from the dispersion and used as the measurement target.

[0030] The desorption rate DR of resin particles is determined, for example, by the following method. That is, the peak area YA of the peak derived from the resin particles of the toner particles after the predetermined ultrasonic treatment is determined by gas chromatography-mass spectrometry (GC / MS analysis). The peak area YB of the peak derived from the resin particles of the toner particles before the predetermined ultrasonic treatment (initial toner particles) is determined by GC / MS analysis. Then, the desorption rate DR of resin particles is calculated according to the formula "desorption rate DR = 100 × (YB - YA) / YB".

[0031] The detachment rate DSi of silica particles can be determined, for example, by the following method. That is, by X-ray fluorescence analysis, the peak intensity XA of the peak derived from the measured element (Si) of the toner particles after the predetermined ultrasonic treatment is determined. By X-ray fluorescence analysis, the peak intensity XB of the peak derived from the measured element (Si) of the toner particles (initial toner particles) before the predetermined ultrasonic treatment is determined. Then, the detachment rate DSi of the silica particles is calculated according to the formula "detachment rate DSi = 100 × (XB - XA) / XB".

[0032] The detachment rate DN of negatively chargeable lubricating particles can be determined, for example, by the following method. That is, by fluorescent X-ray analysis, the peak intensity ZA of the peak derived from the measured element (e.g., an element characteristic of negatively chargeable lubricating particles) of the toner particles after the predetermined ultrasonic treatment is determined. By fluorescent X-ray analysis, the peak intensity ZB of the peak derived from the measured element (e.g., an element characteristic of negatively chargeable lubricating particles) of the toner particles (initial toner particles) before the predetermined ultrasonic treatment is determined. Then, the detachment rate DN of the negatively chargeable lubricating particles is calculated according to "detachment rate DN = 100 × (ZB - ZA) / ZB". Note that when the negatively chargeable lubricating particles are fluorine-containing resin particles, the measured element is, for example, fluorine (F).

[0033] The methods for measuring the detachment rate DSi of silica particles, the detachment rate DR of resin particles, and the detachment rate DN of negatively chargeable lubricating particles have been described above. Details of these measurement methods will be described later in the examples.

[0034] The resin particle content WR per 100.0 parts by mass of toner base particles may be equal to or greater than the silica particle content WSi per 100.0 parts by mass of toner base particles, but it is preferable that the resin particle content WR be less than the silica particle content WSi, since this makes it easier to adjust the silica particle detachment rate DSi and the resin particle detachment rate DR to values ​​within the desired ranges.

[0035] The content WN of negatively chargeable lubricating particles per 100.0 parts by mass of toner base particles may be the same as or greater than the content WSi of silica particles per 100.0 parts by mass of toner base particles, but it is preferable that the content WN of negatively chargeable lubricating particles be less than the content WSi of silica particles, since this makes it easier to adjust the detachment rate DSi of silica particles and the detachment rate DN of negatively chargeable lubricating particles to values ​​within the desired ranges.

[0036] The content WN of negatively chargeable lubricating particles per 100.0 parts by mass of toner base particles may be the same as or greater than the content WR of resin particles per 100.0 parts by mass of toner base particles. However, since it is easy to adjust the detachment rate DR of the resin particles and the detachment rate DN of the negatively chargeable lubricating particles to values ​​within the desired ranges, it is preferable that the content WN of negatively chargeable lubricating particles be less than the content WR of the resin particles.

[0037] Since the detachment rate DSi of silica particles, the detachment rate DR of resin particles, and the detachment rate DN of negatively chargeable lubricating particles can be easily adjusted to values ​​within the desired ranges, it is preferable that the silica particle content WSi, the resin particle content WR, and the negatively chargeable lubricating particle content WN per 100.0 parts by mass of toner base particles satisfy the formula (2) "WSi>WR>WN".

[0038] The number average primary particle diameter SR of the resin particles may be equal to or smaller than the number average primary particle diameter SSi of the silica particles, but is preferably larger than the number average primary particle diameter SSi of the silica particles, since this makes it easier to adjust the detachment rates DSi of the silica particles and DR of the resin particles to values ​​within the desired ranges.

[0039] The number average primary particle diameter SN of the negatively chargeable lubricating particles may be the same as or smaller than the number average primary particle diameter SSi of the silica particles, but it is preferable that the number average primary particle diameter SN of the negatively chargeable lubricating particles be larger than the number average primary particle diameter SSi of the silica particles, since this makes it easier to adjust the detachment rates DSi of the silica particles and DN of the negatively chargeable lubricating particles to values ​​within the desired ranges.

[0040] The number average primary particle diameter SN of the negatively charged lubricating particles may be the same as or smaller than the number average primary particle diameter SR of the resin particles. However, since it is easy to adjust the detachment rate DR of the resin particles and the detachment rate DN of the negatively charged lubricating particles to values within a desired range, the number average primary particle diameter SN of the negatively charged lubricating particles is preferably larger than the number average primary particle diameter SR of the resin particles.

[0041] Since it is easy to adjust the detachment rate DSi of the silica particles, the detachment rate DR of the resin particles, and the detachment rate DN of the negatively charged lubricating particles to values within a desired range, the number average primary particle diameter SSi of the silica particles, the number average primary particle diameter SR of the resin particles, and the number average primary particle diameter SN of the negatively charged lubricating particles preferably satisfy the formula (3) "SSi < SR < SN".

[0042] In addition to formula (1), the toner preferably satisfies both formula (2) and formula (3). As shown in formula (2), the content WN of the negatively charged lubricating particles is at least the smallest, and as shown in formula (3), the number average primary particle diameter SN of the negatively charged lubricating particles is the largest, so that the detachment rate DN of the negatively charged lubricating particles can be made the highest. As a result, the detached negatively charged lubricating particles adhere sufficiently to the regulating member 240, and the occurrence of white streaks in the formed image can be preferably suppressed. Also, as shown in formula (2), the content WSi of the positively charged silica particles is the largest, so that the fluidity of the toner is increased and the triboelectric charging of the toner is promoted. As a result, the occurrence of density unevenness in the formed image can be preferably suppressed. On the other hand, as shown in formula (3), the number average primary particle diameter SSi of the silica particles is the smallest, so that even if the content WSi of the silica particles is the largest, the detachment rate DSi of the silica particles can be made the lowest. As a result, it is difficult for the negatively charged lubricating particles attached to the regulating member by the silica particles to be scraped off, and the occurrence of white streaks in the formed image can be preferably suppressed.

[0043] In order to balance the amount of negatively chargeable lubricating particles adhering to the regulating blade and the amount of negatively chargeable lubricating particles scraped off by the silica particles, the ratio WSi / WN of the content WN of negatively chargeable lubricating particles per 100.0 parts by mass of toner base particles to the content WSi of silica particles per 100.0 parts by mass of toner base particles is preferably 2.5 or more and 5.0 or less, and more preferably 3.5 or more and 4.5 or less.

[0044] In order to form an image with minimal white streaks and density unevenness, the ratio WSi / WR of the resin particle content WR per 100.0 parts by mass of toner base particles to the silica particle content WSi per 100.0 parts by mass of toner base particles is preferably 1.5 or more and 3.5 or less, and more preferably 2.0 or more and 3.0 or less.

[0045] In order to form an image with fewer white streaks and density unevenness, the ratio WR / WN of the content WN of negatively charged lubricating particles per 100.0 parts by mass of toner base particles to the content WR of resin particles per 100.0 parts by mass of toner base particles is preferably 0.5 or more and 2.5 or less, and more preferably greater than 1.0 and 2.0 or less.

[0046] (silica particles) The silica particles impart fluidity to the toner particles, and are preferably silica particles that have been subjected to a surface treatment to impart either or both of positive chargeability and hydrophobicity.

[0047] In order to form an image with few white streaks and density unevenness, the detachment rate DSi of the silica particles is preferably 5% or more and 15% or less.

[0048] The number-average primary particle diameter SSi of the silica particles is preferably less than 40 nm, more preferably 30 nm or less, and even more preferably 20 nm or less. If the number-average primary particle diameter SSi of the silica particles is less than 40 nm, the silica particles are less likely to detach from the toner base particles, and the detachment rate DSi of the silica particles can be easily adjusted to a value within a desired range. On the other hand, the number-average primary particle diameter SSi of the silica particles is preferably 10 nm or more. If the number-average primary particle diameter SSi of the silica particles is 10 nm or more, the embedding of the silica particles in the toner base particles can be suppressed.

[0049] Since the detachment rate DSi of the silica particles can be easily adjusted to a value within the desired range, the content WSi of the silica particles is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, more preferably 0.5 parts by mass or more and 3.0 parts by mass or less, and even more preferably 1.5 parts by mass or more and 2.5 parts by mass or less, relative to 100.0 parts by mass of the toner base particles.

[0050] (resin particles) In order to form an image with fewer white streaks and density unevenness, the resin particle detachment rate DR is preferably 15% or more and 50% or less, more preferably 20% or more and 45% or less, even more preferably 25% or more and 40% or less, and even more preferably 30% or more and 35% or less.

[0051] The number-average primary particle diameter SR of the resin particles is preferably 40 nm or more and 130 nm or less. When the number-average primary particle diameter SR of the resin particles is 40 nm or more and 130 nm or less, the detachment rate DR of the resin particles can be easily adjusted to a value within a desired range. Furthermore, when the number-average primary particle diameter SR of the resin particles is 130 nm or less, the occurrence of density unevenness in the formed image can be further suppressed.

[0052] Since the detachment rate DR of the resin particles can be easily adjusted to a value within the desired range, the content WR of the resin particles is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, more preferably 0.5 parts by mass or more and 3.0 parts by mass or less, and even more preferably 0.7 parts by mass or more and 1.4 parts by mass or less, relative to 100.0 parts by mass of the toner base particles.

[0053] The resin particles contain a resin. The resin content in the resin particles is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass.

[0054] Examples of resins contained in the resin particles include styrene resins, acrylic resins (more specifically, acrylic acid ester polymers and methacrylic acid ester polymers, etc.), polyolefins (more specifically, polyethylene and polypropylene, etc.), vinyl chloride resins, polyvinyl alcohol, vinyl ether resins, N-vinyl resins, polyester resins, polyamide resins, and urethane resins. Copolymers of these resins, i.e., copolymers in which any repeating unit is introduced into the above resins (more specifically, styrene-acrylic resins, styrene-butadiene resins, etc.), may also be used.

[0055] The resin contained in the resin particles is preferably a thermoplastic resin. The thermoplastic resin is obtained by addition polymerization or condensation polymerization of one or more thermoplastic monomers. An example of a thermoplastic monomer is a monomer that becomes a thermoplastic resin by addition polymerization (e.g., an acrylic acid-based monomer or a styrene-based monomer). Another example of a thermoplastic monomer is a monomer that becomes a thermoplastic resin by condensation polymerization (e.g., a combination of a polyhydric alcohol and a polycarboxylic acid that becomes a polyester resin by condensation polymerization).

[0056] When the resin particles contain a thermoplastic resin, the thermoplastic resin is preferably a styrene-acrylic resin, which is a copolymer of one or more styrene-based monomers and one or more acrylic acid-based monomers.

[0057] When the resin particles contain a styrene-acrylic resin, the styrene-acrylic resin is preferably a cross-linked styrene-acrylic resin. The cross-linked styrene-acrylic resin is a styrene-acrylic resin having a cross-linked structure derived from a cross-linking agent. The cross-linked styrene-acrylic resin is a copolymer of one or more styrene-based monomers, one or more acrylic acid-based monomers, and a cross-linking agent.

[0058] Suitable examples of styrene-based monomers include styrene, alkylstyrene, and hydroxystyrene. Examples of alkylstyrenes include α-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, and 4-t-butylstyrene. Examples of hydroxystyrenes include p-hydroxystyrene and m-hydroxystyrene. Styrene is preferred as the styrene-based monomer. The content of repeating units derived from styrene-based monomers in a styrene-acrylic resin (e.g., a crosslinked styrene-acrylic resin) is preferably 5% by mass or more and 15% by mass or less.

[0059] Suitable examples of acrylic acid monomers include (meth)acrylic acid, (meth)acrylonitrile, (meth)acrylic acid alkyl esters, and (meth)acrylic acid hydroxyalkyl esters. Suitable examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate (more specifically, n-propyl (meth)acrylate and iso-propyl (meth)acrylate), butyl (meth)acrylate (more specifically, n-butyl (meth)acrylate and iso-butyl (meth)acrylate), and 2-ethylhexyl (meth)acrylate. Suitable examples of (meth)acrylic acid hydroxyalkyl esters include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. The acrylic acid monomer is preferably a (meth)acrylic acid alkyl ester, more preferably butyl (meth)acrylate, further preferably n-butyl (meth)acrylate, and particularly preferably n-butyl methacrylate. The content of repeating units derived from acrylic acid monomers in the styrene-acrylic resin (e.g., crosslinked styrene-acrylic resin) is preferably 50% by mass or more and 60% by mass or less.

[0060] The crosslinking agent has two or more unsaturated bonds (e.g., carbon-carbon double bonds). Suitable examples of the crosslinking agent include N,N'-methylenebisacrylamide, divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, 1,4-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate. Divinylbenzene is preferred as the crosslinking agent. The content of repeating units derived from the crosslinking agent having two or more unsaturated bonds in the crosslinked styrene-acrylic resin is preferably 30% by mass or more and 40% by mass or less.

[0061] The resin particles do not contain, for example, halogen atoms (such as fluorine atoms), and are, for example, halogen-free particles, more specifically, fluorine-free resin particles.

[0062] (Negatively charged lubricant particles) In order to form an image with fewer white streaks and density unevenness, the detachment rate DN of the negatively charged lubricating particles is preferably 35% or more and 80% or less, more preferably 50% or more and 80% or less, even more preferably 55% or more and 80% or less, and even more preferably 65% ​​or more and 80% or less.

[0063] The number average primary particle diameter SN of the negatively chargeable lubricating particles is preferably 60 nm or more. On the other hand, the number average primary particle diameter SN of the negatively chargeable lubricating particles is preferably 400 nm or less, more preferably 350 nm or less, even more preferably 300 nm or less, even more preferably 200 nm or less, even more preferably 100 nm or less, and particularly preferably 90 nm or less. If the number average primary particle diameter SN of the negatively chargeable lubricating particles is 60 nm or more and 400 nm or less, it is easy to adjust the detachment rate DN of the negatively chargeable lubricating particles to a value within the desired range. Furthermore, if the number average primary particle diameter SN of the negatively chargeable lubricating particles is 350 nm or less, the occurrence of density unevenness in the formed image can be suitably suppressed.

[0064] Since the detachment rate DN of the negatively chargeable lubricating particles can be easily adjusted to a value within the desired range, the content WN of the negatively chargeable lubricating particles is preferably 0.1 parts by mass or more and 5.0 parts by mass or less, more preferably 0.2 parts by mass or more and 3.0 parts by mass or less, and even more preferably 0.3 parts by mass or more and 0.6 parts by mass or less, relative to 100.0 parts by mass of the toner base particles.

[0065] The negatively chargeable lubricating particles have, for example, a halogen atom (for example, a fluorine atom), and examples of the negatively chargeable lubricating particles include fluorine-containing resin particles.

[0066] The fluorine-containing resin particles contain a fluorine-containing resin. The content of the fluorine-containing resin in the fluorine-containing resin particles is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass.

[0067] Examples of fluorine-containing resins include polytetrafluoroethylene (PTFE), perfluoroalkoxy fluorine-containing resins, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, tetrafluoroethylene-n-perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-ethylene copolymers, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymers, and tetrafluoroethylene-perfluoroalkoxyethylene copolymers. PTFE is preferred as the fluorine-containing resin. PTFE particles are also preferred as the fluorine-containing resin particles.

[0068] When the negatively chargeable lubricating particles are fluorine-containing resin particles, emulsion polymerization is a preferred method for preparing the fluorine-containing resin particles. The fluorine-containing resin particles obtained by emulsion polymerization are nearly spherical, making them suitable as external additives for toner. Commercially available fluorine-containing resin particles may also be used. Examples of such commercially available products include KTL-500F (Kitamura Corporation, number average primary particle diameter 300 nm), Lubron (registered trademark) L2 (Daikin Industries, Ltd., number average primary particle diameter 300 nm), Lubron (registered trademark) L5 (Daikin Industries, Ltd., number average primary particle diameter 200 nm), Fluon Lubricant L170J (Asahi ICI Fluoropolymers Corporation, number average primary particle diameter 100 nm), and Fluon Lube. Examples of such polymers include Lycant L172J (manufactured by Asahi ICI Fluoropolymers Co., Ltd., number average primary particle diameter 0.1 μm), MP-1100 (manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd., number average primary particle diameter 200 nm), MP-1200 (manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd., number average primary particle diameter 300 nm), and TLP-10F-1 (manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd., number average primary particle diameter 200 nm).

[0069] (Other external additive particles) The external additive may contain only silica particles, resin particles, and negatively chargeable lubricating particles as external additive particles, or may further contain particles other than these particles (hereinafter sometimes referred to as "other external additive particles"). The total content of the silica particles, resin particles, and negatively chargeable lubricating particles in the external additive is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass. Examples of other external additive particles include particles of metal oxides (specifically, magnesium oxide, zinc oxide, etc.) and particles of organic acid compounds such as fatty acid metal salts (specifically, zinc stearate, etc.).

[0070] <Toner base particles> The toner base particles contain, for example, a binder resin as a main component, and may further contain an internal additive (for example, at least one of a colorant, a release agent, a charge control agent, and other additives) as needed.

[0071] (binder resin) The content of the binder resin in the toner base particles is preferably 60% by mass or more and 95% by mass or less, and more preferably 75% by mass or more and 90% by mass or less. From the viewpoint of improving the low-temperature fixability of the toner, the softening point of the binder resin is preferably 100°C or more and 150°C or less.

[0072] From the viewpoint of improving the low-temperature fixability of the toner, the toner base particles preferably contain a thermoplastic resin as a binder resin, and more preferably contain the thermoplastic resin in a proportion of 85% by mass or more of the total binder resin. Examples of thermoplastic resins include styrene resins, acrylic resins, polyolefins (e.g., polyethylene and polypropylene), vinyl resins (e.g., vinyl chloride resins, polyvinyl alcohol, vinyl ether resins, and N-vinyl resins), polyesters, polyamides, and urethane resins. Copolymers of these resins, i.e., copolymers in which any repeating unit is introduced into the above resins (e.g., styrene-acrylic resins and styrene-butadiene resins), can also be used as binder resins.

[0073] From the viewpoint of improving the low-temperature fixability of the toner, polyester resins are preferred as binder resins. Polyester resins are obtained by polycondensation of one or more polyhydric alcohols and one or more polycarboxylic acids. Examples of alcohols used to synthesize polyester resins include dihydric alcohols (e.g., diol compounds and bisphenol compounds) and trivalent or higher alcohols. Examples of carboxylic acids used to synthesize polyester resins include divalent carboxylic acids and trivalent or higher carboxylic acids. Note that instead of polycarboxylic acids, polycarboxylic acid derivatives capable of forming ester bonds by polycondensation (e.g., polycarboxylic acid anhydrides and polycarboxylic acid halides) may be used.

[0074] Examples of diol compounds include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 2-butene-1,4-diol, 1,5-pentanediol, 2-pentene-1,5-diol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, 1,4-benzenediol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0075] Examples of bisphenol compounds include bisphenol A, hydrogenated bisphenol A, ethylene oxide adducts of bisphenol A (for example, polyoxyethylene (2,2)-2,2-bis(4-hydroxyphenyl)propane), and propylene oxide adducts of bisphenol A.

[0076] Examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

[0077] Examples of divalent carboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, succinic acid, alkylsuccinic acids (more specifically, n-butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid), and alkenylsuccinic acids (more specifically, n-butenylsuccinic acid, isobutenylsuccinic acid, n-octenylsuccinic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid).

[0078] Examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxylpropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid.

[0079] The polyester resin is preferably a condensation polymer of bisphenol A ethylene oxide adduct, terephthalic acid, and trimellitic anhydride, and more preferably a condensation polymer of polyoxyethylene(2,2)-2,2-bis(4-hydroxyphenyl)propane, terephthalic acid, and trimellitic anhydride.

[0080] (coloring agent) As the colorant, a known pigment or dye can be used in accordance with the color of the toner. From the viewpoint of forming a high-quality image using the toner, the content of the colorant is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin.

[0081] The toner base particles may contain a black colorant. Examples of black colorants include carbon black. The black colorant may also be a colorant toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

[0082] The toner base particles may contain color colorants, such as yellow colorants, magenta colorants, and cyan colorants.

[0083] The yellow colorant may be, for example, one or more compounds selected from the group consisting of condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds. Examples of the yellow colorant include CI Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 191, and 194), Naphthol Yellow S, Hansa Yellow G, and CI Vat Yellow.

[0084] Examples of magenta colorants that can be used include one or more compounds selected from the group consisting of condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Examples of magenta colorants include CI Pigment Red (2, 3, 5, 6, 7, 19, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, and 254).

[0085] The cyan colorant may be, for example, one or more compounds selected from the group consisting of copper phthalocyanine compounds, anthraquinone compounds, and basic dye lake compounds, including, for example, CI Pigment Blue (1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66), phthalocyanine blue, CI Vat Blue, and CI Acid Blue.

[0086] (mold release agent) The release agent is used, for example, for the purpose of imparting offset resistance to the toner. From the viewpoint of imparting sufficient offset resistance to the toner, the content of the release agent is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin.

[0087] Examples of release agents include aliphatic hydrocarbon waxes, oxidized aliphatic hydrocarbon waxes, vegetable waxes, animal waxes, mineral waxes, ester waxes primarily composed of fatty acid esters, and waxes in which fatty acid esters have been partially or completely deoxidized. Examples of aliphatic hydrocarbon waxes include low-molecular-weight polyethylene, low-molecular-weight polypropylene, polyolefin copolymers, polyolefin waxes, microcrystalline waxes, paraffin waxes, and Fischer-Tropsch waxes. Examples of oxidized aliphatic hydrocarbon waxes include oxidized polyethylene waxes and block copolymers of oxidized polyethylene waxes. Examples of vegetable waxes include candelilla wax, carnauba wax, Japan wax, jojoba wax, and rice wax. Examples of animal waxes include beeswax, lanolin, and spermaceti. Examples of mineral waxes include ozokerite, ceresin, and petrolatum. Examples of ester waxes primarily composed of fatty acid esters include Montan acid ester wax and castor wax. Examples of waxes in which fatty acid esters have been partially or completely deoxidized include deoxidized carnauba wax. As the release agent, carnauba wax is preferred.

[0088] (charge control agent) Charge control agents are used, for example, for the purpose of providing a toner having excellent charge stability or excellent charge rise characteristics. The charge rise characteristics of a toner are an index of whether the toner can be charged to a predetermined charge level in a short period of time. By incorporating a positively chargeable charge control agent into the toner base particles, the cationic nature of the toner base particles can be strengthened.

[0089] From the viewpoint of obtaining a toner having excellent charge stability, the content of the charge control agent is preferably 0.1 to 30 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the binder resin.

[0090] Examples of positively chargeable charge control agents include azine compounds, direct dyes, acid dyes, alkoxylated amines, alkylamides, quaternary ammonium salt compounds, and resins containing quaternary ammonium cation groups. Quaternary ammonium salt compounds are preferred as charge control agents.

[0091] [Second embodiment: Toner manufacturing method] The second embodiment of the present invention relates to a method for producing a toner. The toner produced by the production method of the second embodiment is the toner described in the first embodiment. Therefore, for the same reasons as those described in the first embodiment, the toner produced by the production method of the second embodiment can form images with fewer white streaks and density unevenness. The toner production method of the second embodiment includes, for example, a toner base particle preparation step and an external addition step.

[0092] (Toner base particle preparation process) In the toner base particle preparation step, the toner base particles are prepared by, for example, an aggregation method or a pulverization method.

[0093] The aggregation method includes, for example, an aggregation step and a coalescence step. In the aggregation step, fine particles containing components constituting the toner base particles are aggregated in an aqueous medium to form aggregated particles. In the coalescence step, components contained in the aggregated particles are coalesced in the aqueous medium to form toner base particles.

[0094] Next, the pulverization method will be described. The pulverization method allows toner base particles to be prepared relatively easily and also enables reduction in production costs. When toner base particles are prepared by the pulverization method, the preparation process of the toner base particles includes, for example, a kneading step and a pulverization step. The preparation process of the toner base particles may further include a mixing step before the kneading step. Furthermore, the preparation process of the toner base particles may further include at least one of a fine pulverization step and a classification step after the pulverization step.

[0095] In the mixing step, a binder resin and an internal additive, which is added as needed, are mixed to obtain a mixture. In the kneading step, the toner materials (for example, the mixture obtained in the mixing step) are melted and kneaded to obtain a kneaded product. In the pulverizing step, the obtained kneaded product is cooled, for example, to room temperature (25°C), and then pulverized to obtain a pulverized product. If it is necessary to reduce the diameter of the pulverized product obtained in the pulverizing step, a fine pulverizing step may be carried out to further pulverize the pulverized product. Furthermore, if the particle size of the pulverized product is to be uniform, a classification step may be carried out to classify the pulverized product. Through the above steps, toner base particles, which are the pulverized product, are obtained.

[0096] (External addition process) In the external addition step, an external additive (more specifically, an external additive containing silica particles, resin particles, and negatively charged lubricating particles) is attached to the surface of the toner base particles to obtain a toner containing toner particles. In the external addition step, the toner base particles and the external additive are stirred, for example, with a mixer, to cause the external additive to adhere to the surface of the toner base particles.

[0097] When an external additive is attached by stirring, the toner base particles and the external additive particles are physically fixed to each other, not chemically (i.e., without chemical reaction). The degree of fixation between the toner base particles and the external additive particles can be adjusted by the stirring conditions (more specifically, the stirring time, the stirring rotation speed, etc.) and the particle size of the external additive particles. Therefore, by changing the stirring conditions and the particle size of the external additive particles, the detachment rate DSi of the silica particles, the detachment rate DR of the resin particles, and the detachment rate DN of the negatively charged lubricating particles can be appropriately adjusted.

[0098] Silica particles, resin particles, and negatively chargeable lubricating particles may be added to the toner base particles simultaneously and stirred. However, it is preferable to add the silica particles, resin particles, and negatively chargeable lubricating particles to the toner base particles at different times and stir them. By adding them at different times, the degree of fixation of the silica particles, the degree of fixation of the resin particles, and the degree of fixation of the negatively chargeable lubricating particles to the toner base particles can be adjusted independently. As a result, the detachment rate DSi of the silica particles, the detachment rate DR of the resin particles, and the detachment rate DN of the negatively chargeable lubricating particles can be adjusted independently.

[0099] The longer the mixing time TSi between the toner base particles and the silica particles, the more sufficiently the silica particles are fixed to the surface of the toner base particles, and the lower the detachment rate DSi of the silica particles. The mixing time TSi between the toner base particles and the silica particles is preferably 13 minutes or more and 20 minutes or less.

[0100] The longer the stirring time TR of the toner base particles and resin particles, the more sufficiently the resin particles are fixed to the surface of the toner base particles, and the lower the detachment rate DR of the resin particles. The stirring time TR of the toner base particles and resin particles is preferably 8 minutes or more and 12 minutes or less.

[0101] The longer the stirring time TN of the toner base particles and the negatively chargeable lubricating particles, the more sufficiently the negatively chargeable lubricating particles are fixed to the surface of the toner base particles, and the lower the detachment rate DN of the negatively chargeable lubricating particles. The stirring time TN of the toner base particles and the negatively chargeable lubricating particles is preferably 3 minutes or more and 7 minutes or less.

[0102] In order to adjust the detachment rate DSi of the silica particles, the detachment rate DR of the resin particles, and the detachment rate DN of the negatively chargeable lubricating particles to values ​​within the desired ranges, it is preferable that the stirring time TSi of the toner base particles and silica particles, the stirring time TR of the toner base particles and resin particles, and the stirring time TN of the toner base particles and negatively chargeable lubricating particles satisfy the following formula (A): TSi>TR>TN (A)

[0103] In order to adjust the silica particle detachment rate DSi, resin particle detachment rate DR, and negatively chargeable lubricant particle detachment rate DN to values ​​within the desired ranges, the mixing time TN between the toner base particles and the negatively chargeable lubricant particles and the mixing time TR between the toner base particles and the resin particles preferably satisfy the formula "1.5≦TR / TN≦2.5". For the same reason, the mixing time TN between the toner base particles and the negatively chargeable lubricant particles and the mixing time TSi between the toner base particles and the silica particles preferably satisfy the formula "2.5≦TSi / TN≦3.5". For the same reason, the mixing time TSi between the toner base particles and the silica particles and the mixing time TR between the toner base particles and the resin particles preferably satisfy the formula "1.0≦TSi / TR≦2.0".

[0104] [Third embodiment: image forming apparatus] The third embodiment of the present invention relates to an image forming apparatus. Hereinafter, an image forming apparatus 1, which is one example of the image forming apparatus of the present invention, will be described with reference to FIGS. 1 and 2 again. Note that the same reference symbols in the drawings represent the same or corresponding parts. Dimensional relationships such as length, width, thickness, and depth have been changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

[0105] As shown in FIG. 1, the image forming apparatus 1 includes a paper feed section 10, a conveyance section 11, an image forming section 12, a fixing section 13, a discharge section 14, and a control section 15.

[0106] The paper feed unit 10 includes a paper feed cassette 30 and a paper feed roller group 31. The paper feed cassette 30 can accommodate multiple recording media P. The paper feed roller group 31 feeds the recording media P accommodated in the paper feed cassette 30 one by one to the conveyance unit 11. The recording media P are made of, for example, paper or synthetic resin.

[0107] The conveying section 11 extends from the paper feeding section 10 to the discharge section 14. The conveying section 11 conveys the recording medium P from the paper feeding section 10 to the discharge section 14, passing through the image forming section 12 and the fixing section 13.

[0108] The image forming unit 12 includes an exposure unit 20, a charging unit 21, a developing unit 22, toner T (see FIG. 2), an image carrier 23, a cleaning unit 24, and a transfer unit 25. The charging unit 21, the developing unit 22, the transfer unit 25, and the cleaning unit 24 are arranged along the circumferential surface of the image carrier 23 in the order listed from the upstream side in the rotation direction R of the image carrier 23 (clockwise direction in FIG. 1).

[0109] The charging unit 21 uniformly charges the image carrier 23 to a preset polarity.

[0110] The exposure unit 20 irradiates (exposes) light onto the surface 23a (see FIG. 2) of the charged image carrier 23. The exposure unit 20 exposes the surface 23a of the image carrier 23 based on image data input to the image forming apparatus 1. As a result, an electrostatic latent image is formed on the surface 23a of the image carrier 23.

[0111] The developing unit 22 contains toner T. The developing unit 22 supplies the toner T to the electrostatic latent image formed on the surface 23a of the image carrier 23, and develops the electrostatic latent image into a toner image. Details of the developing unit 22 will be described later.

[0112] Toner T is the toner described in the first embodiment. Therefore, the image forming apparatus 1 including toner T can form images with fewer white streaks and density unevenness for the same reasons as those described in the first embodiment.

[0113] The image carrier 23 carries a toner image on its surface 23a. The image carrier 23 is, for example, a photosensitive drum.

[0114] The transfer unit 25 is disposed opposite the image carrier 23 and transfers the toner image on the image carrier 23 onto the recording medium P.

[0115] The cleaning unit 24 collects the toner T remaining on the surface 23a of the image carrier 23 after transfer from the surface 23a of the image carrier 23.

[0116] The fixing unit 13 includes a heating unit 40 and a pressure unit 41. The heating unit 40 and the pressure unit 41 are arranged opposite each other. The pressure unit 41 presses the heating unit 40 to form a fixing nip. The recording medium P onto which the toner image has been transferred passes through the fixing nip and is heated and pressurized. As a result, the toner T is fixed to the recording medium P. The recording medium P is transported from the fixing unit 13 to the discharge unit 14 by the transport unit 11.

[0117] The discharge section 14 includes a discharge roller pair 60 and a discharge tray 61. The discharge roller pair 60 discharges the recording medium P onto the discharge tray 61.

[0118] The control unit 15 controls the operation of each unit included in the image forming apparatus 1. The control unit 15 is, for example, a processor such as a CPU (Central Processing Unit). The control unit 15 comprehensively controls the operation of the image forming apparatus 1 to realize various functions.

[0119] Next, the details of the developing unit 22 will be described with reference to Fig. 2. As already mentioned, the developing unit 22 includes a storage frame 210, a supply roller 220, a toner carrier 230, and a regulating member 240. The lengths of the supply roller 220 and the toner carrier 230 in the axial direction (the direction perpendicular to the paper surface of Fig. 2) are approximately the same as the length of the image carrier 23.

[0120] The storage frame 210 stores toner T therein. The storage frame 210 includes a supply roller 220, a toner carrier 230, and a regulating member 240 therein. The storage frame 210 has an opening 211, which is disposed opposite the image carrier 23. The opening 211 exposes a portion of the toner carrier 230 to the outside of the storage frame 210.

[0121] Supply roller 220 is supported so as to be rotatable in the direction of the arrow in FIG. 2 (counterclockwise). Supply roller 220 carries toner T contained inside storage frame 210 on its surface (circumferential surface). A nip N1 is provided between toner carrier 230 and supply roller 220. In nip N1, supply roller 220 supplies toner T carried on its surface to toner carrier 230. In addition, in nip N1, toner T on supply roller 220 comes into contact with toner carrier 230, thereby causing toner T to be frictionally charged.

[0122] The toner carrier 230 is supported so as to be rotatable in the direction of the arrow in FIG. 2 (counterclockwise). The toner carrier 230 is disposed opposite the supply roller 220. The toner carrier 230 is also disposed opposite the image carrier 23 through the opening 211 of the storage frame 210. The toner carrier 230 carries the toner T supplied from the supply roller 220 on its surface (circumferential surface) 230a in the form of a toner layer. The toner T is carried on the surface 230a of the toner carrier 230 due to the image force acting between the toner carrier 230 and the toner T. The toner carrier 230 is, for example, a development roller.

[0123] The toner carrier 230 includes a conductive support 231, an elastic layer 232, and a coating layer 233. The elastic layer 232 is provided on the conductive support 231 (specifically, on the outer peripheral surface of the conductive support 231). The elastic layer 232 is made of, for example, silicone rubber. The coating layer 233 is provided on the elastic layer 232 (specifically, on the outer peripheral surface of the elastic layer 232). The coating layer 233 is made of, for example, urethane.

[0124] The regulating member 240 is plate-shaped. One end 241 of the regulating member 240 is fixed to the storage frame 210, and the other end 242 is a free end. The regulating member 240 is bent toward the opposite side to the toner carrier 230 near the outer edge of the other end 242 (free end). The regulating member 240 is made of, for example, stainless steel (SUS). The regulating member 240 is, for example, a regulating blade.

[0125] The regulating member 240 is flexible and deformable so that the other end 242 approaches the toner carrier 230. The toner carrier 230 has one or more magnet portions (not shown) therein. The regulating member 240 is magnetic. The other end 242 of the magnetic regulating member 240 is urged toward the toner carrier 230 by the magnetic force generated by the magnet portion of the toner carrier 230. In this way, a nip N2 is formed between the regulating member 240 and the surface 230a of the toner carrier 230. In the nip N2, the regulating member 240 comes into contact with the toner layer on the toner carrier 230 (specifically, the toner layer formed on the surface 230a of the toner carrier 230) with a predetermined pressure to regulate the thickness of the toner layer. In order to regulate the thickness of the toner layer within a desired range, the pressure (regulation pressure) of regulation member 240 against surface 230a of toner carrier 230 is preferably 15 N / m or more and 40 N / m or less. Furthermore, at nip N2, toner T on toner carrier 230 comes into contact with regulation member 240, thereby further triboelectrically charging toner T.

[0126] When a development bias is applied to the toner carrier 230, the toner T contained in the toner layer is supplied from the toner carrier 230 to the electrostatic latent image formed on the surface 23a of the image carrier 23 through the opening 211. The details of the developing unit 22 have been described above with reference to FIG.

[0127] As described above, the image forming apparatus 1 shown in Fig. 1 has been described as an example of the image forming apparatus of the third embodiment. However, the image forming apparatus of the third embodiment is not limited to the image forming apparatus 1 described above, and can be modified in the following respects, for example.

[0128] For example, in the third embodiment, the image forming apparatus 1 is an apparatus that records an image using a single color toner, but this is not limiting. The image forming apparatus may be an apparatus that records a color image using multiple color toners.

[0129] For example, in the third embodiment, the regulating member 240 is plate-shaped, but this is not limiting. The regulating member 240 may be roller-shaped. When the regulating member 240 is roller-shaped, the peripheral surface of the roller-shaped regulating member 240 comes into contact with the toner layer on the toner carrier 230 (specifically, the toner layer formed on the surface 230a of the toner carrier 230) with a predetermined pressure, thereby regulating the thickness of the toner layer. [Example]

[0130] Examples of the present invention will be described below, but the present invention is not limited to the scope of the examples. First, methods for measuring physical property values ​​will be described.

[0131] [Number average primary particle size] The number-average primary particle diameter of the external additive particles (specifically, silica particles, resin particles, and negatively charged lubricant particles) was determined from particle projection images taken using a scanning electron microscope ("JSM-7600F" manufactured by JEOL Ltd.) Specifically, the external additive particles were observed using the scanning electron microscope, and the number-average primary particle diameter was determined as the number-average circle-equivalent diameter (Heywood diameter: diameter of a circle having the same area as the projected area of ​​a primary particle) of 100 external additive particles.

[0132] [Negatively charged lubricant particles] The negatively chargeable lubricating particles shown in Table 1 were prepared by the following method. All of the prepared negatively chargeable lubricating particles were PTFE particles. The preparation conditions for each negatively chargeable lubricating particle are shown in Table 1. The number average primary particle diameter of the negatively chargeable lubricating particles measured is also shown in Table 1. The "diameter" used in Table 1 refers to the number average primary particle diameter.

[0133] [Table 1]

[0134] <Preparation of negatively charged lubricant particles (NA)> An autoclave equipped with a stainless steel anchor-type stirring blade and a temperature-controlling jacket was used as the reaction vessel. 3580 mL of deionized water, 3.58 g of ammonium perfluorooctanoate, and 94.1 g of paraffin wax (Nippon Seiro Co., Ltd.'s "Paraffin Wax-130") were charged into the reaction vessel. After purging the atmosphere in the reaction vessel with nitrogen gas and tetrafluoroethylene (TFE), TFE was further pressure-fed into the reaction vessel. The contents of the reaction vessel were stirred at a stirring speed of 250 rpm (hereinafter referred to as the stirring speed X), while the reaction vessel was heated to a temperature of 80°C and maintained at this temperature. While pressure-fed, an aqueous solution of ammonium persulfate (concentration: 0.067% by mass) and an aqueous solution of disuccinic acid peroxide (concentration: 1.61% by mass) were added, and TFE was continuously supplied to maintain a constant pressure (0.78 MPa) inside the reaction vessel. The polymerization reaction was carried out for 50 minutes (hereinafter referred to as the polymerization time Y). During the polymerization reaction, the injected amounts of ammonium persulfate aqueous solution, disuccinic acid peroxide aqueous solution, and TFE were 20 mL, 20 mL, and 1735 g, respectively. After polymerization time Y, the supply of TFE and stirring of the contents of the reaction vessel were stopped, and the polymerization reaction was terminated. 100 mL of ammonium hydroperfluorononanoate aqueous solution (concentration: 10% by mass) was added to the latex-like reaction product obtained by the polymerization reaction. Next, warm water was added to the reaction product and the temperature was adjusted to 50°C. Next, 10 mL of nitric acid (concentration: 60% by mass) was added to the reaction product, and the reaction product was stirred at 250 rpm. As a result, negatively chargeable lubricating particles (NA) began to coagulate from the reaction product. Next, the reaction product was stirred for 1 hour to fully separate the negatively chargeable lubricating particles (NA) from the solvent. Next, the solvent was removed from the negatively chargeable lubricating particles (NA), and the particles were dried to obtain negatively chargeable lubricating particles (NA) having the number average primary particle diameter shown in Table 1.

[0135] <Preparation of negatively charged lubricant particles (NB) to (NE)> Negatively chargeable lubricating particles (NB) to (NE) were prepared in the same manner as in the preparation of negatively chargeable lubricating particles (NA), except that the stirring speed X and polymerization time Y were changed to the values ​​shown in Table 1.

[0136] [Resin particles] The resin particles shown in Table 2 were prepared by the following method. All of the prepared resin particles were cross-linked styrene acrylic resin particles. The preparation conditions for each resin particle are shown in Table 2. The number average primary particle diameter of the measured resin particles is also shown in Table 2. The "diameter" used in Table 2 refers to the number average primary particle diameter.

[0137] [Table 2]

[0138] <Preparation of Resin Particles (RA)> A four-neck flask equipped with a stirrer, condenser, thermometer, and nitrogen inlet tube was charged with 600 g of ion-exchanged water, 6 g of emulsifier sodium dodecylbenzenesulfonate, 100 g of n-butyl methacrylate, 20 g of styrene, 15 g of initiator benzoyl peroxide, and 70 g of crosslinker divinylbenzene. Nitrogen gas was then introduced into the flask while stirring the contents, creating a nitrogen atmosphere. The temperature of the flask contents was then raised to 90°C under a nitrogen atmosphere while stirring, and the contents were polymerized for 150 minutes (hereinafter referred to as polymerization time Z) under the nitrogen atmosphere and at 90°C conditions. This resulted in an emulsion containing the reaction product. The resulting emulsion was cooled, washed, and dehydrated to obtain resin particles (RA) having the number-average primary particle diameter shown in Table 2.

[0139] <Preparation of Resin Particles (RB) to (RE)> Resin particles (RB) to (RE) were prepared in the same manner as in the preparation of resin particles (RA), except that the polymerization time Z was changed to the value shown in Table 2.

[0140] [Silica particles] As the silica particles, commercially available silica particles shown below were used. Silica particles (Si-A): Hydrophobic silica particles ("TG-7120" manufactured by Cabot Specialty Chemicals, Inc., number-average primary particle diameter: 20 nm)

[0141] [Binder resin] A polyester resin (PE) used as a binder resin for toner base particles was prepared by the following method. 1.0 mol of polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, 4.5 mol of terephthalic acid, 0.5 mol of trimellitic anhydride, and 4 g of dibutyltin oxide were placed in a reaction vessel. The contents of the reaction vessel were reacted at 230°C for 8 hours under a nitrogen atmosphere. Next, unreacted raw materials in the reaction vessel were distilled off under reduced pressure at 8.3 kPa. The resulting reaction product was washed and then dried. This yielded a polyester resin (PE) with a softening point of 120°C.

[0142] [Preparation of toner base particles] 100 parts by weight of the polyester resin (PE) as a binder resin, 5 parts by weight of carbon black (REGAL® 330R, manufactured by Cabot Specialty Chemicals) as a colorant, 10 parts by weight of carnauba wax (Carnauba No. 1, manufactured by Kato Yoko Co., Ltd.) as a mold release agent, and 3 parts by weight of a quaternary ammonium salt compound (FCA210PS, manufactured by Fujikura Kasei Co., Ltd.) as a charge control agent were mixed using an FM mixer (FM20B, manufactured by Nippon Coke & Engineering Co., Ltd.). The resulting mixture was melted and kneaded at 150°C using a twin-screw extruder (TEM45, manufactured by Toshiba Machine Co., Ltd.). The resulting kneaded mixture was cooled. The cooled kneaded mixture was coarsely pulverized using an impact screen-type fine pulverizer (Feathermill® FM-2S 350 x 600, manufactured by Hosokawa Micron Corporation). The obtained coarsely pulverized material was finely pulverized using a supersonic jet pulverizer ("Jet Mill IDS-2" manufactured by Nippon Pneumatic Mfg. Co., Ltd.). The obtained finely pulverized material was classified using a classifier ("Elbow Jet EJ-LABO" manufactured by Nittetsu Mining Co., Ltd.). This resulted in the production of toner base particles. The volume median diameter (D 50 ) was 8 μm.

[0143] [Toner Preparation] Toners according to Examples and Comparative Examples were prepared by carrying out external addition treatment by the following method: Details of the external addition treatment for each toner are shown in Table 3 below.

[0144] [Table 3]

[0145] The external addition treatment was carried out in all cases using an FM mixer ("FM-10B" manufactured by Nippon Coke and Engineering Co., Ltd.) at a rotation speed of 3500 rpm.

[0146] <Preparation of Toner (T1-1)> 100.0 parts by mass of toner base particles and 2.0 parts by mass of silica particles (Si-A) were placed in the container of an FM mixer and stirred for 5 minutes (hereinafter referred to as the first stirring time). Subsequently, 0.8 parts by mass of resin particles (RA) were added to the container of the FM mixer and further stirred for 5 minutes (hereinafter referred to as the second stirring time). Subsequently, 0.5 parts by mass of negatively charged lubricating particles (NA) were added to the container of the FM mixer and further stirred for 5 minutes (hereinafter referred to as the third stirring time). As a result, toner (T1-1) was obtained. The stirring time TSi of the silica particles (Si-A) was 15 minutes (corresponding to the total time of the first stirring time, second stirring time, and third stirring time). The stirring time TR of the resin particles (RA) was 10 minutes (corresponding to the total time of the second stirring time and third stirring time). The stirring time TN of the negatively charged lubricating particles (NA) was 5 minutes (corresponding to the third stirring time).

[0147] <Preparation of Toner (T1-2)> 100.0 parts by mass of toner base particles and 0.8 parts by mass of resin particles (RA) were placed in the container of an FM mixer and stirred for 5 minutes (hereinafter referred to as the first stirring time). Subsequently, 0.5 parts by mass of negatively charged lubricating particles (NA) were added to the container of the FM mixer and further stirred for 5 minutes (hereinafter referred to as the second stirring time). Subsequently, 2.0 parts by mass of silica particles (Si-A) were added to the container of the FM mixer and further stirred for 5 minutes (hereinafter referred to as the third stirring time). As a result, toner (T1-2) was obtained. The stirring time TR of the resin particles (RA) was 15 minutes (corresponding to the total time of the first stirring time, the second stirring time, and the third stirring time). The stirring time TN of the negatively charged lubricating particles (NA) was 10 minutes (corresponding to the total time of the second stirring time and the third stirring time). The stirring time TSi of the silica particles (Si-A) was 5 minutes (corresponding to the third stirring time).

[0148] <Preparation of Toner (T1-3)> 100.0 parts by mass of toner base particles and 2.0 parts by mass of silica particles (Si-A) were placed in the container of an FM mixer and stirred for 5 minutes (hereinafter referred to as the first stirring time). Subsequently, 0.5 parts by mass of negatively charged lubricating particles (NA) were added to the container of the FM mixer and further stirred for 5 minutes (hereinafter referred to as the second stirring time). Subsequently, 0.8 parts by mass of resin particles (RA) were added to the container of the FM mixer and further stirred for 5 minutes (hereinafter referred to as the third stirring time). As a result, toner (T1-3) was obtained. The stirring time TSi of the silica particles (Si-A) was 15 minutes (corresponding to the total time of the first stirring time, second stirring time, and third stirring time). The stirring time TN of the negatively charged lubricating particles (NA) was 10 minutes (corresponding to the total time of the second stirring time and third stirring time). The stirring time TR of the resin particles (RA) was 5 minutes (corresponding to the third stirring time).

[0149] <Preparation of Toners (T2-1), (T3-1), (T4-1), (T5-1), (T6-1), (T7-1), (T8-1), and (T9-1)> Toners (T2-1), (T3-1), (T4-1), (T5-1), (T6-1), (T7-1), (T8-1), and (T9-1) were prepared in the same manner as in the preparation of toner (T1-1), except that the resin particles and negatively charged lubricating particles shown in Table 3 were used.

[0150] <Preparation of Toners (T2-2), (T3-2), (T4-2), (T5-2), (T6-2), (T7-2), (T8-2), and (T9-2)> Toners (T2-2), (T3-2), (T4-2), (T5-2), (T6-2), (T7-2), (T8-2), and (T9-2) were prepared in the same manner as in the preparation of toner (T1-2), except that the resin particles and negatively charged lubricating particles shown in Table 3 were used.

[0151] <Preparation of Toners (T2-3), (T3-3), (T4-3), (T5-3), (T6-3), (T7-3), (T8-3), and (T9-3)> Toners (T2-3), (T3-3), (T4-3), (T5-3), (T6-3), (T7-3), (T8-3), and (T9-3) were prepared in the same manner as in the preparation of toner (T1-3), except that the resin particles and negatively charged lubricating particles shown in Table 3 were used.

[0152] [Measurement of desorption rate] The detachment rate DR of the resin particles, the detachment rate DSi of the silica particles, and the detachment rate DN of the negatively chargeable lubricating particles were measured by the following methods. The measurement results are shown in Table 4 below.

[0153] <Measurement of the Detachment Rate DR of Resin Particles> The toner was subjected to the specified ultrasonic treatment described below, and a toner after the specified ultrasonic treatment was obtained. The toner after the specified ultrasonic treatment was subjected to the following GC / MS analysis, and a mass spectrum of the toner after the specified ultrasonic treatment was obtained. From the mass spectrum of the toner after the specified ultrasonic treatment, the peak area YA of the peak derived from the resin particles was determined. Next, the toner before the specified ultrasonic treatment (initial toner) was subjected to the following GC / MS analysis, and a mass spectrum of the initial toner was obtained. From the mass spectrum of the initial toner, the peak area YB of the peak derived from the resin particles was determined. Then, the detachment rate DR of the resin particles was calculated according to the formula "detachment rate DR = 100 × (YB - YA) / YB".

[0154] <Measurement of the Desorption Rate of Silica Particles DSi> The toner was subjected to the specified ultrasonic treatment described below, and a toner after the specified ultrasonic treatment was obtained. The toner after the specified ultrasonic treatment was subjected to the following fluorescent X-ray analysis, and a fluorescent X-ray spectrum (horizontal axis: energy, vertical axis: intensity (number of photons)) of the toner after the specified ultrasonic treatment was obtained. From the fluorescent X-ray spectrum of the toner after the specified ultrasonic treatment, the peak intensity XA of the peak attributed to the measured element (Si) was determined. Next, the toner before the specified ultrasonic treatment (initial toner) was subjected to the following fluorescent X-ray analysis, and a fluorescent X-ray spectrum (horizontal axis: energy, vertical axis: intensity (number of photons)) of the initial toner was obtained. From the fluorescent X-ray spectrum of the initial toner, the peak intensity XB of the peak attributed to the measured element (Si) was determined. Then, the detachment rate DSi of the silica particles was calculated according to the formula "detachment rate DSi = 100 × (XB - XA) / XB".

[0155] <Measurement of the Detachment Rate DN of Negatively Charged Lubricant Particles> The toner was subjected to the following specified ultrasonic treatment to obtain a toner after the specified ultrasonic treatment. The toner after the specified ultrasonic treatment was subjected to the following fluorescent X-ray analysis to obtain the fluorescent X-ray spectrum of the toner after the specified ultrasonic treatment (horizontal axis: energy, vertical axis: intensity (number of photons)). From the fluorescent X-ray spectrum of the toner after the specified ultrasonic treatment, the peak intensity ZA of the peak derived from the measured element (F) was determined. Next, the toner before the specified ultrasonic treatment (initial toner) was subjected to the following fluorescent X-ray analysis to obtain the fluorescent X-ray spectrum of the initial toner (horizontal axis: energy, vertical axis: intensity (number of photons)). From the fluorescent X-ray spectrum of the initial toner, the peak intensity ZB of the peak derived from the measured element (F) was determined. Then, the detachment rate DN of the negatively charged lubricating particles was calculated according to the formula "detachment rate DN = 100 × (ZB - ZA) / ZB".

[0156] <Prescribed ultrasonic treatment> 2 g of a nonionic surfactant (Kao Corporation's "Emulgen (registered trademark) 120", component: polyoxyethylene lauryl ether) and 98 g of ion-exchanged water were mixed to obtain an aqueous surfactant solution with a concentration of 2% by mass. 2 g of toner was dispersed in 100 g of the aqueous surfactant solution to obtain a toner dispersion. Using an ultrasonic disperser (Kosonic Co., Ltd.'s "Ultra Sonic Mini Welder P128", output: 100 W, oscillation frequency: 28 kHz), the toner dispersion was subjected to ultrasonic treatment for 5 minutes. Subsequently, qualitative filter paper (Advantec's "FILTER PAPER No. 1", pore size: approximately 5 μm) was set in a suction filtration device equipped with a filtering bell and a Buchner funnel. Using this suction filtration device, the toner dispersion subjected to ultrasonic treatment was suction filtered to obtain toner (toner after predetermined ultrasonic treatment) subjected to the predetermined ultrasonic treatment. The washing operation was repeated three times on the toner after the predetermined ultrasonic treatment to remove the surfactant adhering to the surface of the toner after the predetermined ultrasonic treatment. The washing operation consisted of a reslurrying operation in which 50 mL of ion-exchanged water was added to the toner after the predetermined ultrasonic treatment to obtain a slurry-like toner after the predetermined ultrasonic treatment, and a suction filtration operation in which the slurry-like toner after the predetermined ultrasonic treatment was suction filtered using a suction filtration device. The filter paper and the toner after the predetermined ultrasonic treatment remaining on the filter paper were transferred from the suction filtration device after the washing operation to an aluminum container. The aluminum container was placed in a vacuum isothermal dryer and vacuum dried at 40°C for 12 hours. As a result, dried toner after the predetermined ultrasonic treatment was obtained.

[0157] <GC / MS analysis> As an analyzer for GC / MS analysis, a gas chromatograph mass spectrometer (Shimadzu Corporation's "GCMS-QP2010 Ultra") connected to a multi-shot pyrolyzer (Agilent Technologies' "PY-3030D") was used. Using the above analyzer, GC / MS analysis was performed on 100 μg of the measurement target (either the toner after the predetermined ultrasonic treatment or the initial toner) under the following conditions. As a result of the GC / MS analysis, a mass spectrum (horizontal axis: mass / charge number of ions, vertical axis: detection intensity) containing peaks derived from resin particles was obtained.

[0158] (GC / MS analysis conditions) Column: Agilent Technologies "Agilent® J&W GC Column" (product number: DB-5ms Ultra Inert column, phase: arylene phase in which arylene is added to siloxane polymer to strengthen the polymer backbone, inner diameter: 0.25 mm, film thickness: 0.25 μm, length: 30 m) Pyrolysis temperature: Furnace temperature 600℃, interface temperature 320℃ Heating conditions: Heat from 40°C to 320°C at a rate of 28°C / min, and hold at 320°C for 5 minutes Carrier gas: Helium (He) gas Carrier gas linear velocity: 36.1 cm / min Column head pressure: 49.7kPa Injection mode: Split injection (split ratio 1:200) Carrier flow rate: Total flow rate 204 mL / min, column flow rate 1 mL / min, purge flow rate 3 mL / min

[0159] <X-ray fluorescence analysis> 1.5 g of the measurement object (either the toner after the specified ultrasonic treatment or the initial toner) was pressure-molded under conditions of 20 MPa and a pressure time of 3 seconds to prepare a cylindrical pellet with a diameter of 30 mm. The obtained pellet was subjected to fluorescent X-ray analysis under the following conditions to obtain a fluorescent X-ray spectrum (horizontal axis: energy, vertical axis: intensity (number of photons)) containing peaks derived from the measurement elements (Si and F).

[0160] (X-ray fluorescence analysis conditions) Analytical equipment: Scanning X-ray fluorescence analyzer (Rigaku Corporation "ZSX") X-ray tube (X-ray source): Rh (rhodium) Excitation conditions: Tube voltage 50 kV, tube current 50 mA Measurement area (X-ray irradiation range): 30 mm diameter ·Measurement elements: Si, F

[0161] [evaluation] Images printed using each toner were evaluated for white streaks and density unevenness using the following methods. The evaluation results are shown in Table 4 below.

[0162] <Print> A monochrome printer ("PA2000" manufactured by Kyocera Document Solutions Inc.) was used as the evaluation machine. This evaluation machine was equipped with an image carrier and a development unit equipped with a development roller and a regulating blade. The toner was set in the evaluation machine. Images (including an image portion with a print rate of 5% and a halftone image portion) were intermittently printed on 1,500 sheets of paper at intervals of 400 seconds using the evaluation machine in an environment of a temperature of 23°C and a relative humidity of 50%.

[0163] <White streaks> The image printed on the 1500th sheet was visually observed to determine whether or not there were any white streaks. The white streaks were determined according to the following criteria.

[0164] (White streak standard) A (good): No white streaks were observed. B (bad): White streaks were observed.

[0165] <Uneven density> The halftone image portion of the image printed on the 1500th sheet was visually observed to determine whether or not there was density unevenness. The density unevenness was determined according to the following criteria.

[0166] (Standard for uneven density) A (good): No uneven density was observed. B (poor): Uneven density was observed.

[0167] <Poor density and fogging> The image printed on the 1500th sheet was checked for the presence or absence of a decrease in image density (poor density) and fogging. If poor density or fogging was found, this was noted in the "Remarks" column of Table 4.

[0168] [Table 4]

[0169] Toners (T1-2), (T1-3), (T2-2), (T2-3), (T3-2), (T3-3), (T4-2), (T4-3), (T5-2), (T6-2), (T6-3), (T7-2), (T7-3), (T8-2), (T8-3), (T9-1), (T9-2), and (T9-3) did not satisfy formula (1). These toners were poor in either or both of the evaluation of white streaks and the evaluation of density unevenness.

[0170] On the other hand, the toners (T1-1), (T2-1), (T3-1), (T4-1), (T5-1), (T5-3), (T6-1), (T7-1), and (T8-1) each satisfied formula (1). These toners were evaluated as being good in both white streaks and density unevenness.

[0171] From the above, it is determined that the toners of the present invention, including toners (T1-1), (T2-1), (T3-1), (T4-1), (T5-1), (T5-3), (T6-1), (T7-1), and (T8-1), can form images with fewer white streaks and density unevenness. It is also determined that the image forming apparatus equipped with the toner of the present invention and the toner produced by the production method of the present invention can form images with fewer white streaks and density unevenness. [Industrial Applicability]

[0172] The toner of the present invention, the image-forming apparatus of the present invention, and the toner produced by the production method of the present invention can be used to form images in, for example, a multifunction machine or a printer. [Explanation of symbols]

[0173] 1: Image forming device 22: Development unit 23: Image carrier 230: Toner carrier 240: Regulating member T: Toner

Claims

1. A non-magnetic monocomponent toner comprising toner particles, The toner particles include toner base particles and an external additive attached to the surface of the toner base particles, the external additive includes silica particles, resin particles, and negatively charged lubricating particles; A non-magnetic single-component toner, wherein the detachment rate DSi of the silica particles, the detachment rate DR of the resin particles, and the detachment rate DN of the negatively chargeable lubricating particles, which are measured by subjecting the toner particles to ultrasonic treatment at a frequency of 28 kHz for 5 minutes, satisfy the following formula (1): DSi<DR<DN...(1)

2. the desorption rate DSi of the silica particles is 5% or more and 15% or less, the detachment rate DR of the resin particles is 15% or more and 50% or less, 2. The non-magnetic single-component toner according to claim 1, wherein the detachment rate DN of the negatively chargeable lubricating particles is 35% or more and 80% or less.

3. the resin particles are fluorine-free resin particles, 3. The non-magnetic one-component toner according to claim 1, wherein the negatively chargeable lubricating particles are fluorine-containing resin particles.

4. 4. The non-magnetic single-component toner according to claim 3, wherein the fluorine-containing resin particles are polytetrafluoroethylene particles.

5. 3. The non-magnetic single-component toner according to claim 1, wherein the number average primary particle diameter of the resin particles is larger than the number average primary particle diameter of the silica particles.

6. The number average primary particle diameter of the silica particles is less than 40 nm, the number average primary particle diameter of the resin particles is 40 nm or more and 130 nm or less; 3. The non-magnetic one-component toner according to claim 1, wherein the number average primary particle size of the negatively chargeable lubricating particles is 60 nm or more and 400 nm or less.

7. a content WSi of the silica particles, a content WR of the resin particles, and a content WN of the negatively chargeable lubricating particles relative to 100.0 parts by mass of the toner base particles satisfy the following formula (2):

3. The non-magnetic single-component toner according to claim 1, wherein the number average primary particle diameter SSi of the silica particles, the number average primary particle diameter SR of the resin particles, and the number average primary particle diameter SN of the negatively chargeable lubricating particles satisfy the following formula (3): WSi>WR>WN...(2) SSi<SR<SN...(3)

8. Toner and an image carrier; a developing unit that supplies the toner to the electrostatic latent image formed on the surface of the image carrier; Equipped with The developing unit a toner carrier that carries the toner in the form of a toner layer; a regulating member that comes into contact with the toner layer on the toner carrier and regulates the thickness of the toner layer; Equipped with 3. An image forming apparatus, wherein the toner is the non-magnetic one-component toner according to claim 1.

9. an external addition step of adhering the external additive to the surface of the toner base particles to obtain a toner containing the toner particles, The method for producing a toner, wherein the toner is the non-magnetic one-component toner according to claim 1 or 2.

10. In the external addition step, the toner base particles and the external additive are stirred, a mixing time TSi between the toner base particles and the silica particles, a mixing time TR between the toner base particles and the resin particles, and a mixing time TN between the toner base particles and the negatively chargeable lubricating particles satisfy the following formula (A): The number average primary particle diameter of the silica particles is less than 40 nm, the number average primary particle diameter of the resin particles is 40 nm or more and 130 nm or less; The method for producing a toner according to claim 9, wherein the negatively chargeable lubricating particles have a number average primary particle size of 60 nm or more and 400 nm or less. TSi>TR>TN...(A)

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