JP7246611B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

In image forming apparatuses, the use of titanate compound particles (for example, strontium titanate particles) as external additive particles contained in toner is being studied. The titanate compound particles have a relatively high dielectric constant, which facilitates charge transfer between toner particles. Therefore, an image forming apparatus using titanate compound particles as external additive particles can equalize the charge amount of each toner particle and prevent fogging (more specifically, even when printing is performed at a high printing rate after printing at a low printing rate). It is possible to suppress the occurrence of replenishment fog). On the other hand, the titanate compound particles have a shape close to a cube. Therefore, in an image forming apparatus using titanate compound particles as external additive particles, the surface of the image carrier (photosensitive drum) is excessively polished, and streaky image defects (image streaks) may occur. Also, the titanate compound particles have a relatively high resistivity. Therefore, an image forming apparatus using titanate compound particles as external additive particles may not be able to sufficiently suppress the occurrence of fogging in a low temperature and low humidity environment where the resistance of the external additive particles tends to increase.

The image forming apparatus described in Patent Document 1 uses titanate compound particles doped with lanthanum (hereinafter sometimes referred to as lanthanum-doped titanate compound particles) as the titanate compound particles contained in the toner. . The lanthanum-doped titanate compound particles have a dielectric constant comparable to that of titanate compound particles not doped with lanthanum, a low resistivity, and a nearly spherical shape. Therefore, the image forming apparatus using the lanthanum-doped titanate compound particles as the external additive particles can suppress the occurrence of fog even in a low-temperature and low-humidity environment. Further, the image forming apparatus using the lanthanum-doped titanate compound particles as the external additive particles can suppress excessive polishing of the surface of the photoreceptor drum.

JP 2018-155912 A

However, the image forming apparatus disclosed in Patent Document 1 tends to be unable to sufficiently suppress the occurrence of image streaks and photoreceptor pinholes.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of fogging, image streaks, and photoreceptor pinholes.

An image forming apparatus according to the present invention comprises a developer containing toner, an image carrier, a developing device for developing an electrostatic latent image formed on the surface of the image carrier into a toner image with the developer, and and a cleaning member that is pressed against the surface of the image carrier. In a cross-sectional view of the image carrier, when an imaginary straight line connecting the points of contact of the image carrier and the cleaning member and the center O of the image carrier is defined as a line segment X, the line segment X is a horizontal plane Y The angle θ formed with respect to is 0 degrees or more and 30 degrees or less. The cleaning member has a type A durometer hardness of 65 degrees or more and 80 degrees or less. The toner includes toner particles. The toner particles include toner base particles containing a binder resin and an external additive adhering to the surface of the toner base particles. The external additive contains titanate compound particles doped with lanthanum and a Group 5 element of the periodic table as external additive particles. The amount of lanthanum is 1.50% by mass or more with respect to the total mass of the titanate compound particles. The amount of the Group 5 element of the periodic table is 0.01% by mass or more and 0.30% by mass or less with respect to the total mass of the titanate compound particles.

According to the present invention, it is possible to provide an image forming apparatus capable of suppressing the occurrence of fogging, image streaks, and photoreceptor pinholes.

1 is a diagram showing a configuration of part of an image forming apparatus according to the present invention; FIG. 2 is a diagram showing the configuration of a developing roller in the image forming apparatus of FIG. 1; FIG. 2 is a diagram showing the configuration of toner particles in the image forming apparatus of FIG. 1; FIG.

Preferred embodiments of the present invention are described below. First, the terms used in this specification will be explained. Toner is an aggregate (for example, powder) of toner particles. The external additive is an aggregate (for example, powder) of external additive particles. Evaluation results (values indicating shape, physical properties, etc.) regarding powder (more specifically, powder of toner particles, powder of external additive particles, etc.) are the It is the number average of the values measured for each of the selected particles.

The measured value of the volume median diameter (D ₅₀ ) of the powder was measured using a laser diffraction/scattering particle size distribution analyzer ("LA-950" manufactured by Horiba, Ltd.) unless otherwise specified. is the median diameter. Unless otherwise specified, the number average primary particle diameter of the powder is the equivalent circle diameter of 100 primary particles (Haywood diameter: having the same area as the projected area of the primary particles) measured using a scanning electron microscope. circle diameter). Unless otherwise specified, the number average primary particle size of particles refers to the number average primary particle size of particles in powder (the number average primary particle size of powder).

The electrification strength is the ease of triboelectrification, unless otherwise specified. For example, a standard carrier provided by the Imaging Society of Japan (standard carrier for negatively charged polarity toner: N-01, standard carrier for positively charged polarity toner: P-01) and an object to be measured (for example, toner) are mixed and stirred. to triboelectrically charge the object to be measured. Before and after triboelectrification, the charge amount of the object to be measured is measured by, for example, a small suction type charge amount measuring device (“MODEL 212HS” manufactured by Trek). A measurement object with a greater change in charge amount before and after triboelectrification indicates a stronger electrification property.

A "major component" of a material means, by mass, the component that is the most abundant in the material, unless otherwise specified.

The strength of hydrophobicity can be represented, for example, by the contact angle of a water droplet (easiness of getting wet with water). The greater the contact angle of water droplets, the stronger the hydrophobicity. Hydrophobic treatment refers to treatment for enhancing hydrophobicity.

"Periodical Table" refers to the periodic table of the elements in the long period type as defined by the IUPAC (International Union of Pure and Applied Chemistry). "Periodic Table Group 5 element" is at least one element selected from vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). A "titanate compound" is a compound (crystal) containing at least titanium, oxygen, and a metal element other than titanium. "Titanate compound particles" are particles containing a titanate compound as a main component. The content of the titanate compound in the titanate compound particles is preferably 99% by mass or more and 100% by mass or less with respect to the total mass of the titanate compound particles.

Hereinafter, compounds and derivatives thereof may be collectively referred to by adding "system" to the name of the compound. When the polymer name is indicated by adding "system" after the compound name, it means that the repeating unit of the polymer is derived from the compound or its derivative.

Further, in the following description, the phrase "to be doped with an element (more specifically, lanthanum, a Group 5 element of the periodic table, etc.)" means that a part of the element constituting the crystal of the titanate compound serving as the base material is doped. is replaced with an element (more specifically, lanthanum, a Group 5 element of the periodic table, etc.) different from the element constituting the base material.

<Image forming apparatus>
The image forming apparatus according to the present embodiment includes a developer containing toner, an image carrier, a developing device that develops an electrostatic latent image formed on the surface of the image carrier into a toner image with the developer, and an image carrier. a cleaning member that is pressed against the surface of the body. An angle formed by a line segment X with respect to a horizontal plane Y when an imaginary straight line connecting the contact points of the image carrier and the cleaning member and the center O of the image carrier is defined as a line segment X in a cross-sectional view of the image carrier. θ is 0 degrees or more and 30 degrees or less. The type A durometer hardness of the cleaning member is 65 degrees or more and 80 degrees or less. The toner includes toner particles. The toner particles include toner base particles containing a binder resin and external additives adhering to the surfaces of the toner base particles. The external additive contains, as external additive particles, titanate compound particles doped with lanthanum and a Group 5 element of the periodic table (hereinafter sometimes referred to as specific titanate compound particles). The amount of lanthanum is 1.50% by mass or more with respect to the total mass of the titanate compound particles. The amount of the Group 5 element of the periodic table is 0.01% by mass or more and 0.30% by mass or less with respect to the total mass of the titanate compound particles.

Hereinafter, the amount of lanthanum with respect to the total mass of the specific titanate compound particles may be simply referred to as "amount of lanthanum". Also, the amount of the Group 5 element of the periodic table with respect to the total mass of the specific titanate compound particles may be simply referred to as "the amount of the Group 5 element of the periodic table". Both the amount of lanthanum and the amount of elements of Group 5 of the periodic table are measured by an inductively coupled plasma atomic emission spectrometer.

The image forming apparatus according to the present embodiment can suppress the occurrence of fogging, image streaks, and photoreceptor pinholes by providing the above-described configuration. The reason is presumed as follows.

Common titanate compound particles tend to be easily charged. Therefore, in an image forming apparatus using general titanate compound particles as an external additive, the titanate compound particles may be excessively charged and discharged to the surface of the photoreceptor drum. This phenomenon is particularly likely to occur in a low-temperature, low-humidity environment. When the titanate compound particles are discharged on the surface of the photoreceptor drum, pinholes are generated on the surface of the photoreceptor drum, resulting in dot-like image defects (for example, generation of black spots). Here, since general titanate compound particles have a nearly cubic shape, electric charges tend to escape from the vertices of the particles. On the other hand, lanthanum-doped titanate compound particles have a nearly spherical shape, and thus are more easily charged than general titanate compound particles.

On the other hand, in the image forming apparatus according to the present embodiment, specific titanate compound particles doped with a certain amount or more of a Group 5 element of the periodic table are used as the external additive particles. The Group 5 element of the periodic table moderately reduces the electrical resistance of the specific titanate compound particles.

Further, in an image forming apparatus in which a cleaning member is arranged above an image carrier, toner particles scraped off by the cleaning member may reattach to the image carrier. In such an image forming apparatus, the toner particles continue to remain on the image carrier, which may result in an excessive accumulation of electric charge on the external additive particles. On the other hand, in the image forming apparatus according to this embodiment, the cleaning member is arranged on the side of the image carrier. A cleaning member disposed on the side of the image carrier drops the scraped toner particles and quickly removes them from the image carrier.

As described above, in the image forming apparatus according to the present embodiment, excessive charging of the specific titanate compound particles can be suppressed, and as a result, the occurrence of photoreceptor pinholes can be suppressed.

Further, external additive particles having a nearly spherical shape (hereinafter sometimes referred to as spherical external additive particles) adhere to the image carrier and are difficult to remove with a cleaning member. Specifically, the spherical external additive particles adhering to the image bearing member slip through the cleaning member and contaminate the surface of the photosensitive drum in streaks. Streak-like contamination on the surface of the photoreceptor drum causes image streaks. On the other hand, in the image forming apparatus according to the present embodiment, the type A durometer hardness of the cleaning member is 65 degrees or more and 80 degrees or less, which is moderately hard. A moderately hard cleaning member can efficiently scrape off the spherical external additive particles (lanthanum-doped titanate compound particles) adhering to the image bearing member. Therefore, in the image forming apparatus according to the present embodiment, it is possible to suppress the occurrence of image streaks caused by streaky contamination of the photoreceptor.

Furthermore, since the specific titanate compound particles contain a titanate compound having a relatively high dielectric constant, the charge amount of the toner can be stably maintained. Further, usually, toner using external additive particles having excessively low electrical resistance tends to cause fogging. However, the specific titanate compound particles have a certain electrical resistance because the amount of the Group 5 element of the periodic table is 0.30% by mass or less with respect to the total mass. Therefore, the image forming apparatus according to this embodiment can suppress the occurrence of fogging.

An example of the configuration of the image forming apparatus according to the present embodiment will be described below with reference to the drawings. All of the image forming apparatuses described below are image forming apparatuses in the case of forming an image using a one-component developer. However, the image forming apparatus of the present embodiment also includes an image forming apparatus that forms an image using a two-component developer.

An example of the configuration of the image forming apparatus according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a view (specifically, a cross-sectional view) showing the configuration of part of the image forming apparatus according to the present embodiment. Specifically, FIG. 1 mainly shows a configuration centering on a developing device and a photosensitive drum included in the image forming apparatus according to the present embodiment.

The image forming apparatus according to the present embodiment includes a developing device 1, a photosensitive drum 20, a charging device 21, an exposure device 22, a cleaning member 23, a toner charging member 30, and a toner supply roller 40, as shown in FIG. . The developing device 1 includes a developing roller 10 as a toner carrier, a container R, and a transfer device (not shown). The container R contains a developer containing toner (specifically, a one-component developer). That is, the image forming apparatus according to this embodiment includes developer containing toner.

The developing roller 10 is configured to carry the toner supplied from the container R. Such a developing roller 10 includes a shaft 11, a magnet roll 12, and a cylindrical sleeve 13, as shown in FIGS. The magnet roll 12 is fixed to the shaft 11 and positioned inside the sleeve 13 (inside the cylinder). Moreover, the magnet roll 12 has a magnetic pole at least on its surface layer. The magnetic poles of the magnet roll 12 include, for example, N poles and S poles based on permanent magnets. The sleeve 13 is positioned on the surface layer of the developing roller 10 and supported so as to be rotatable around the shaft 11 . Specifically, the shaft 11 and the sleeve 13 are connected by flanges 13a and 13b so that the sleeve 13 can rotate around the magnet roll 12 which does not rotate. This structure allows the sleeve 13 to rotate in the circumferential direction of the shaft 11 (the direction of the arrow in FIG. 1).

In the image forming apparatus according to the present embodiment, the sleeve 13 of the developing roller 10, the photosensitive drum 20, and the toner supply roller 40 each rotate in the direction of the arrow in FIG. 1 to form an image. done. In the following, the configuration of the image forming apparatus according to the present embodiment will be further described by showing an image forming method using the image forming apparatus shown in FIG.

Specifically, first, the charging device 21 uniformly charges the photosensitive layer of the photosensitive drum 20 . Next, the exposure device 22 forms an electrostatic latent image on the photosensitive layer of the photoreceptor drum 20 based on the image data. Subsequently, the developing device 1 develops the electrostatic latent image formed on the photosensitive layer of the photosensitive drum 20 using toner containing the toner particles 60 .

Specifically, the toner supply roller 40 supplies the toner from the container R to the developing roller 10 . At this time, the sleeve 13 of the developing roller 10 attracts the toner particles 60 contained in the toner by the magnetic force of the magnet roll 12 . As a result, toner particles 60 are carried on the surface of sleeve 13 of developing roller 10 . The toner particles 60 carried on the surface of the sleeve 13 are charged by friction with the toner charging member 30 . At this time, the positively charged toner is positively charged by friction. Negatively charged toner is negatively charged by friction. Charged toner particles 60 are supplied to photoreceptor drum 20 by rotation of sleeve 13 of developer roller 10 . As a result, the toner particles 60 adhere to the electrostatic latent image formed on the photosensitive layer of the photoreceptor drum 20, thereby forming a toner image on the photosensitive layer. Thus, the electrostatic latent image formed on the photosensitive layer is developed.

Subsequently, the toner image on the photosensitive layer of the photoreceptor drum 20 is transferred to the transfer material by the transfer device. A recording medium (for example, printing paper) is preferable as the material to be transferred. A fixing device then applies heat and pressure to the toner particles 60 to fix the toner particles 60 to the recording medium. As a result, an image is formed on the recording medium. After the image is formed, the cleaning member 23 removes the toner particles 60 remaining on the photosensitive layer.

The cleaning member 23 is pressed against the surface of the photoreceptor drum 20 and removes substances remaining on the surface of the photoreceptor drum 20 . The cleaning member 23 is arranged on the side of the photoreceptor drum 20 . Specifically, in a cross-sectional view of the photoreceptor drum 20, when an imaginary straight line connecting the contact points of the photoreceptor drum 20 and the cleaning member 23 and the center O of the photoreceptor drum 20 is defined as a line segment X, the line segment The angle θ formed by X with respect to the horizontal plane Y is 0 degrees or more and 30 degrees or less. When the contact area between the photoreceptor drum 20 and the cleaning member 23 has a constant width in a cross-sectional view of the photoreceptor drum 20, the most upstream portion of the contact area in the rotation direction of the photoreceptor drum 20 is Make a point of contact.

A preferable material for the cleaning member 23 is rubber. Examples of specific rubbers include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, polyisobutylene, ethylene propylene rubber, chlorosulfonated polyethylene, acrylic rubber, fluororubber, epichlorohydrin rubber, Urethane rubber and silicone rubber are mentioned. Urethane rubber is preferable as the rubber.

The type A durometer hardness of the cleaning member 23 is 65 degrees or more and 80 degrees or less, preferably 70 degrees or more and 75 degrees or less. By setting the type A durometer hardness of the cleaning member 23 to 70 degrees or more and 75 degrees or less, it is possible to further suppress the occurrence of image streaks. The type A durometer hardness of the cleaning member 23 is a value measured at the point of contact with the photoreceptor drum 20 in accordance with “JIS (Japanese Industrial Standards) K6253-3:2012”.

The toner is, for example, positively charged toner. The toner is an aggregate (for example, powder) of toner particles 60 (particles each having a configuration described later). The toner constitutes a single component developer in FIG. However, the toner may constitute a two-component developer. Two-component developers are prepared by mixing toner and carrier using a mixing device (eg, ball mill).

The image forming apparatus according to the present embodiment has been described above with reference to FIGS. However, the image forming apparatus according to this embodiment is not limited to FIGS. For example, the charging device does not have to be in contact with the photoreceptor drum. Also, the toner charging member need not be in contact with the toner particles. Furthermore, the image forming apparatus according to this embodiment may not include the charging device. Details of the toner used in the image forming apparatus according to this embodiment will be described below.

[toner]
The toner is, for example, positively charged toner. The toner is an aggregate (for example, powder) of toner particles (particles each having a configuration described later). In FIG. 1, the toner constitutes a single component developer. However, the toner may constitute a two-component developer. Two-component developers are prepared by mixing toner and carrier using a mixing device (eg, ball mill).

The amount of the Group 5 element of the periodic table is 0.01% by mass or more and 0.30% by mass or less, preferably 0.10% by mass or more, relative to the total mass of the specific titanate compound particles.

The amount of lanthanum is 1.50% by mass or more, preferably 5.00% by mass or more, relative to the total mass of the specific titanate compound particles. The amount of lanthanum is preferably 12.00% by mass or less, more preferably 8.00% by mass or less, relative to the total mass of the specific titanate compound particles.

As the Group 5 element of the periodic table contained in the specific titanate compound particles, one or more elements selected from the group consisting of vanadium, niobium and tantalum are preferable, and niobium is more preferable.

The amount of the specific titanate compound particles in the toner is preferably from 0.1 parts by mass to 1.2 parts by mass and preferably from 0.5 parts by mass to 1.0 parts by mass with respect to 100 parts by mass of the toner base particles. more preferred. By setting the amount of the specific titanate compound particles to 0.1 parts by mass or more and 1.2 parts by mass or less, the occurrence of fogging can be further suppressed.

The dielectric constant of the specific titanate compound particles is preferably 120 or more and 1,000 or less, more preferably 250 or more and 400 or less. By setting the dielectric constant of the specific titanate compound particles to 120 or more and 1,000 or less, the occurrence of fogging can be further suppressed. The method for measuring the relative permittivity is the same method as in Examples described later or a method based thereon.

The toner particles may be particles without a shell layer, or particles with a shell layer (hereinafter sometimes referred to as capsule toner particles). In capsule toner particles, toner mother particles comprise a toner core containing a binder resin and a shell layer covering the surface of the toner core. The shell layer contains resin. For example, by covering a toner core that melts at a low temperature with a shell layer that has excellent heat resistance, it is possible to achieve both heat-resistant storage stability and low-temperature fixability of the toner. Additives may be dispersed in the resin forming the shell layer. The shell layer may cover the entire surface of the toner core, or may partially cover the surface of the toner core.

The toner base particles may further contain an internal additive (for example, at least one of a colorant, a release agent, a charge control agent, and magnetic powder), if necessary, in addition to the binder resin.

The configuration of the toner will be described below with reference to FIG. FIG. 3 is a diagram showing an example of the cross-sectional structure of the toner particles 60. As shown in FIG. It should be noted that FIG. 3 to be referred to schematically shows each component mainly for easy understanding, and the size, number, shape, etc. of each component shown in the figure may be changed for the convenience of drawing. may differ from the actual product.

The toner particles 60 shown in FIG. 3 include toner base particles 61 containing a binder resin and external additives adhering to the surfaces of the toner base particles 61 . The external additive contains specific titanate compound particles 62 as external additive particles.

In order to obtain a toner suitable for image formation, the volume median diameter (D ₅₀ ) of the toner base particles 61 is preferably 4 μm or more and 9 μm or less.

The number average circularity of the specific titanate compound particles 62 is preferably 0.79 or more and 1.00 or less, more preferably 0.80 or more and 0.92 or less, and even more preferably 0.82 or more and 0.86 or less. By setting the number-average circularity of the specific titanate compound particles 62 to 0.79 or more, it is possible to suppress the occurrence of image streaks due to excessive abrasion of the surface of the photoreceptor drum. By setting the number-average circularity of the specific titanate compound particles 62 to 0.86 or less, it is possible to further suppress the occurrence of image streaks due to streak-like contamination on the surface of the photoreceptor drum. The method for measuring the number average circularity is the same method as in Examples described later or a method according to it.

The number average primary particle diameter of the specific titanate compound particles 62 is preferably 20 nm or more and 80 nm or less, more preferably 20 nm or more and 40 nm or less. By setting the number average primary particle diameter of the specific titanate compound particles 62 to 20 nm or more and 80 nm or less, the occurrence of fogging can be further suppressed.

An example of the configuration of the toner particles 60 has been described above with reference to FIG. Next, the elements of the toner particles will be described. In addition, each component demonstrated below may be used individually by 1 type, and may be used in combination of 2 or more types.

(Binder resin)
The binder resin accounts for, for example, 70% by mass or more of the total components of the toner base particles. Therefore, it is considered that the properties of the binder resin have a great influence on the properties of the toner base particles as a whole. In order to obtain a toner excellent in low-temperature fixability, the toner base particles preferably contain a thermoplastic resin as a binder resin, and the thermoplastic resin should be contained at a rate of 85% by mass or more of the total binder resin. is more preferred. Examples of thermoplastic resins include styrene-based resins, acrylic acid ester-based resins, olefin-based resins (more specifically, polyethylene resins, polypropylene resins, etc.), vinyl resins (more specifically, vinyl chloride resins, polyvinyl alcohol, vinyl ether resin, N-vinyl resin, etc.), polyester resin, polyamide resin, and urethane resin. In addition, copolymers of these resins, that is, copolymers in which arbitrary repeating units are introduced into the above resins (more specifically, styrene-acrylic acid ester resins, styrene-butadiene resins, etc.) Can be used as a binder resin.

Thermoplastic resins are obtained by addition polymerization, copolymerization, or condensation polymerization of one or more thermoplastic monomers. The thermoplastic monomer is a monomer that becomes a thermoplastic resin by homopolymerization (more specifically, an acrylic acid ester-based monomer, a styrene-based monomer, etc.), or a monomer that becomes a thermoplastic resin by condensation polymerization (for example, polycondensation A combination of a polyhydric alcohol and a polycarboxylic acid resulting in a polyester resin).

In order to obtain a toner excellent in low-temperature fixability, the toner base particles preferably contain a polyester resin as a binder resin, and the polyester resin is contained at a rate of 80% by mass or more and 100% by mass or less based on the total binder resin. is more preferable. A polyester resin is obtained by condensation polymerization of one or more polyhydric alcohols and one or more polycarboxylic acids. Alcohols for synthesizing the polyester resin include, for example, dihydric alcohols (more specifically, aliphatic diols, bisphenols, etc.) and trihydric or higher alcohols as shown below. Carboxylic acids for synthesizing the polyester resin include, for example, divalent carboxylic acids and trivalent or higher carboxylic acids as shown below. Instead of the polycarboxylic acid, a polycarboxylic acid derivative capable of forming an ester bond by polycondensation, such as an anhydride of a polycarboxylic acid or a polycarboxylic acid halide, may be used.

Suitable examples of aliphatic diols include diethylene glycol, triethylene glycol, neopentyl glycol, 1,2-propanediol, α,ω-alkanediol (more specifically, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,12-dodecanediol, etc.) , 2-butene-1,4-diol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Suitable examples of bisphenols include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct.

Suitable examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, and 1,2,4-butane. triol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5- Trihydroxymethylbenzene is mentioned.

Suitable examples of dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, and malonic acid. , 1,10-decanedicarboxylic acid, succinic acid, alkyl succinic acid (more specifically, n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid, isododecyl succinic acid, etc.), and alkenylsuccinic acid (more specifically, n-butenylsuccinic acid, isobutenylsuccinic acid, n-octenylsuccinic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, etc.).

Preferable 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-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl) Methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid.

(coloring agent)
The toner base particles may contain a colorant. As the colorant, a known pigment or dye can be used according to the color of the toner. The amount of the coloring 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.

The toner base particles may contain a black colorant. Examples of black colorants include carbon black. Alternatively, the black colorant may be a colorant toned black using a yellow colorant, a magenta colorant, and a cyan colorant.

The toner base particles may contain a colorant. Color colorants include yellow colorants, magenta colorants, and cyan colorants.

As the yellow colorant, 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 can be used. Examples of yellow colorants include C.I. I. 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 C.I. I. Bat yellow is mentioned.

Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. One or more compounds can be used. Examples of magenta coloring agents include C.I. I. 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).

As the cyan colorant, for example, one or more compounds selected from the group consisting of copper phthalocyanine compounds, anthraquinone compounds, and basic dye lake compounds can be used. Cyan colorants include, for example, C.I. I. pigment blue (1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66), phthalocyanine blue, C.I. I. bat blue, and C.I. I. acid blue.

(Release agent)
The toner base particles may contain a releasing agent. A release agent is used, for example, to obtain a toner having excellent anti-offset properties. In order to obtain a toner excellent in offset resistance, the amount 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.

Release agents include, for example, ester wax, polyolefin wax (more specifically, polyethylene wax, polypropylene wax, etc.), microcrystalline wax, fluororesin wax, Fischer-Tropsch wax, paraffin wax, candelilla wax, montan wax, and castor wax. Ester waxes include natural ester waxes (more specifically, carnauba wax, rice wax, etc.) and synthetic ester waxes. Carnauba wax is preferred as the release agent.

A compatibilizer may be added to the toner base particles in order to improve compatibility between the binder resin and the release agent.

(Charge control agent)
The toner base particles may contain a charge control agent. A charge control agent is used, for example, to obtain a toner excellent in charge stability or charge rising property. The charging rise characteristic of the toner is an index of whether or not the toner can be charged to a predetermined charging level in a short period of time.

The cationic property (positive chargeability) of the toner base particles can be strengthened by including the positively chargeable charge control agent in the toner base particles. In addition, the anionicity (negative chargeability) of the toner base particles can be enhanced by incorporating a negatively chargeable charge control agent into the toner base particles.

Examples of positive charge control agents include pyridazine, pyrimidine, pyrazine, 1,2-oxazine, 1,3-oxazine, 1,4-oxazine, 1,2-thiazine, 1,3-thiazine, 1, 4-thiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6- oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1,2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1, azine compounds such as 2,4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxaline; azine fast red FC, azine fast red 12BK, azine violet BO, azine brown 3G, azine light Direct dyes such as Brown GR, Azin Dark Green BH/C, Azin Deep Black EW, Azin Deep Black 3RL; Acid dyes such as Nigrosine BK, Nigrosine NB, and Nigrosine Z; Alkoxylated amines; Alkylamides; Benzyldecylhexylmethyl quaternary ammonium salts such as ammonium chloride, decyltrimethylammonium chloride, 2-(methacryloyloxy)ethyltrimethylammonium chloride, dimethylaminopropylacrylamide methyl chloride quaternary salt; and resins containing quaternary ammonium cationic groups. A quaternary ammonium salt is preferred as the charge control agent.

From the viewpoint of obtaining a toner excellent in charging stability, the content of the charge control agent is preferably 0.1 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the binder resin.

(Magnetic powder)
The toner base particles may contain magnetic powder. Examples of magnetic powder materials include ferromagnetic metals (more specifically, iron, cobalt, nickel, etc.) and their alloys, and ferromagnetic metal oxides (more specifically, ferrite, magnetite, chromium dioxide, etc.). , and materials subjected to ferromagnetization treatment (more specifically, carbon materials and the like to which ferromagnetism is imparted by heat treatment).

The content of the magnetic powder is preferably 30 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the binder resin.

(external additive)
The toner particles comprise an external additive adhered to the surface of the toner base particles. The external additive contains specific titanate compound particles as external additive particles.

As the base material (titanate compound to be doped) of the specific titanate compound particles, for example, the composition is MTiO ₃ (M is a metal element other than titanium, excluding lanthanum and Group 5 elements of the periodic table). (representing an element) can be mentioned. Specific examples of titanate compounds whose composition is represented by MTiO ₃ include strontium titanate (SrTiO ₃ ), barium titanate (BaTiO ₃ ), calcium titanate (CaTiO ₃ ), magnesium titanate (MgTiO ₃ ), and Lead titanate (PbTiO ₃ ) is mentioned. The crystal structure of the titanic acid compound whose composition is represented by MTiO ₃ is usually a perovskite crystal structure.

When using a titanate compound whose composition is represented by _MTiO3 as the base material of the specific titanate compound particles, lanthanum and the Group 5 element of the periodic table, for example, the site where the metal represented by M is arranged. By substituting, it is incorporated into the crystal structure of the base material. The site where the metal represented by M is arranged is hereinafter referred to as the M site. Further, specific titanate compound particles obtained by substituting the M site with lanthanum and a Group 5 element of the periodic table are referred to as M site-substituted titanate compound particles.

The peak position of the powder X-ray diffraction pattern of the M-site substituted titanate compound particles coincides with the peak position of the powder X-ray diffraction pattern of the crystal structure of the base material (titanate compound represented by MTiO ₃ ). Therefore, when the peak position of the powder X-ray diffraction pattern of the specific titanate compound particles and the peak position of the powder X-ray diffraction pattern of the base material (titanate compound represented by _MTiO3 ) match, the base material was doped with lanthanum and an element of Group 5 of the periodic table. In addition, with regard to the powder X-ray diffraction patterns, "the peak positions match" means that the diffraction angle (2θ) values match within the range of ±0.5 degrees for the two peak positions to be compared.

The specific titanate compound particles are preferably strontium titanate particles doped with lanthanum and a Group 5 element of the periodic table, or calcium titanate particles doped with lanthanum and a Group 5 element of the periodic table. Strontium titanate particles doped with , or calcium titanate particles doped with lanthanum and niobium are more preferred. By using these specific titanate compound particles, it is possible to further suppress the occurrence of fogging, photoreceptor pinholes, and image streaks.

The method for producing the specific titanate compound particles is not particularly limited. In addition, commercially available specific titanate compound particles can also be used for the toner.

An example of the method for producing the specific titanate compound particles will be described below. First, a treated product obtained by peptizing a titanium source with a mineral acid (hereinafter sometimes referred to as a peptized titanium source product) and a metal element other than titanium constituting the base material (more specifically, strontium) , barium, calcium, etc.), a lanthanum source, and a periodic table group 5 element source are mixed. Then, while heating the resulting mixture to a temperature of 50° C. or higher, an alkaline aqueous solution is added to the mixture. Next, the mixture to which the alkaline aqueous solution has been added is held at a temperature of 50° C. or higher for a predetermined time (for example, 30 minutes or more and 2 hours or less). Then, after cooling the obtained product, a precipitate is obtained by adding hydrochloric acid to the product. Next, the obtained precipitate is washed and filtered (solid-liquid separation), and then the obtained solid content is dried to obtain a powder of specific titanate compound particles.

The amount of lanthanum can be adjusted, for example, by changing the amount of lanthanum source relative to the mass of the peptized titanium source material in the example of the method for producing the specific titanate compound particles. The amount of the Group 5 element of the periodic table can be adjusted by, for example, changing the amount of the Group 5 element source of the periodic table relative to the mass of the peptized titanium source material in the example of the method for producing the specific titanate compound particles. . The number-average circularity of the specific titanate compound particles can be adjusted, for example, by changing the amount of the lanthanum source relative to the mass of the titanium source peptized product in one example of the method for producing the specific titanate compound particles. The number-average primary particle diameter of the specific titanate compound particles can be obtained by, for example, mixing a compound of a metal element other than titanium constituting the base material with a titanium source peptized product in an example of the method for producing the specific titanate compound particles. It can be adjusted by changing at least one of the ratio, the concentration of alkali in the aqueous alkali solution, and the amount of addition of the aqueous alkali solution. The dielectric constant of the specific titanate compound particles can be determined, for example, by the type of metal element other than titanium constituting the base material, the type of Group 5 element of the periodic table, the type of titanium source, and the It can be adjusted by changing at least one of the amount of the periodic table group V element source relative to the mass of the peptized material and the amount of the lanthanum source relative to the mass of the titanium source peptized material.

The surface of the specific titanate compound particles may be subjected to a hydrophobizing treatment from the viewpoint of further suppressing the occurrence of fogging in a high-temperature and high-humidity environment. As a method for obtaining specific titanate compound particles whose surfaces have been hydrophobized, for example, particles composed of a titanate compound doped with lanthanum and an element of Group 5 of the periodic table (hereinafter, may be referred to as a substrate) There is a method of treating with a hydrophobizing agent.

The external additive may contain only the specific titanate compound particles as the external additive particles, or may further contain other external additive particles in addition to the specific titanate compound particles. In order to maintain good fluidity of the toner, the other external additive particles are preferably inorganic particles other than the specific titanate compound particles, more preferably silica particles.

Other external additive particles may be surface-treated. For example, when silica particles are used as other external additive particles, hydrophobicity and/or positive chargeability may be imparted to the surfaces of the silica particles by a surface treatment agent. Examples of surface treatment agents include coupling agents (more specifically, silane coupling agents, titanate coupling agents, aluminate coupling agents, etc.), silazane compounds (more specifically, chain silazane compounds, cyclic silazane compounds, etc.), and silicone oils (more specifically, dimethyl silicone oil, etc.). As the surface treatment agent, one or more selected from silane coupling agents and silazane compounds are particularly preferable. Suitable examples of silane coupling agents include silane compounds (more specifically, methyltrimethoxysilane, aminosilane, etc.). Suitable examples of silazane compounds include HMDS (hexamethyldisilazane). When the surface of a silica substrate (untreated silica particles) is treated with a surface treatment agent, many hydroxy groups (—OH) present on the surface of the silica substrate are partially or wholly derived from the surface treatment agent. is substituted with a functional group that As a result, silica particles having on the surface functional groups derived from the surface treatment agent (specifically, functional groups that are more hydrophobic and/or more positively charged than hydroxy groups) are obtained.

From the viewpoint of sufficiently exhibiting the function of the external additive while suppressing detachment of the external additive from the toner base particles, the amount of the external additive (when using other external additive particles, the specific titanate The total amount of the compound particles and other external additive particles) is preferably 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the toner base particles.

[Toner manufacturing method]
Next, a preferred method for producing the toner described above will be described. Hereinafter, descriptions of components that overlap with the toner described above will be omitted.

(Preparation step of toner base particles)
First, toner base particles are prepared by an aggregation method or a pulverization method.

Aggregation methods include, for example, aggregation and coalescence steps. In the aggregating step, fine particles containing components constituting toner base particles are aggregated in an aqueous medium to form aggregated particles. In the coalescing step, components contained in the aggregated particles are coalesced in an aqueous medium to form toner base particles.

Next, the pulverization method will be explained. According to the pulverization method, the toner base particles can be prepared relatively easily, and the manufacturing cost can be reduced. When the toner base particles are prepared by the pulverization method, the preparation process of the toner base particles includes, for example, a melt-kneading process and a pulverization process. The step of preparing the toner base particles may further include a mixing step before the melt-kneading step. Further, the step of preparing the toner base particles may further include at least one of a fine pulverization step and a classification step after the pulverization step.

In the mixing step, a mixture is obtained by mixing the binder resin and an internal additive added as necessary. In the melt-kneading step, the toner material is melted and kneaded to obtain a melt-kneaded product. As the toner material, for example, a mixture obtained in a mixing step is used. In the pulverization step, the obtained melt-kneaded material is cooled to room temperature (25° C.), for example, and then pulverized to obtain a pulverized material. If it is necessary to reduce the diameter of the pulverized material obtained in the pulverization step, a step of further pulverizing the pulverized product (fine pulverization step) may be carried out. Further, when the particle size of the pulverized material is uniform, a step of classifying the obtained pulverized material (classification step) may be carried out. Through the above steps, toner base particles, which are pulverized products, are obtained.

(External addition process)
After that, using a mixer, the obtained toner base particles and the external additive are mixed to adhere the external additive to the surfaces of the toner base particles. The external additive contains at least specific titanate compound particles. Examples of the mixer include FM mixer (manufactured by Nippon Coke Industry Co., Ltd.). Thus, a toner containing toner particles is produced.

Examples of the present invention will be described below, but the present invention is not limited to the scope of the examples.

[Manufacturing of cleaning member]
Cleaning blades A to E as cleaning members were manufactured by the following method. First, the polyols and curing agents used as raw materials for the cleaning blade are shown below.

(polyol)
PCL1000: "PCL1000" manufactured by Daicel Corporation, polycaprolactone diol, number average molecular weight 1000
PCL2000: "PCL2000" manufactured by Daicel Corporation, polycaprolactone diol, number average molecular weight 2000
(curing agent)
MDI: diphenylmethane diisocyanate (manufactured by Nikka Trading Co., Ltd.)

[Manufacturing of cleaning blade A]
77 parts by mass of PCL2000 and 19.7 parts by mass of MDI were mixed and reacted at 100° C. for 60 minutes to obtain a prepolymer. 3.3 parts by mass of 1,4-butanediol (Mitsubishi Chemical Co., Ltd.) was added to this prepolymer and cured at 130° C. for 30 minutes. A urethane rubber was thus obtained. A cleaning blade A was obtained by cutting this urethane rubber into a blade shape (thickness: 2 mm).

The type A durometer hardness (JIS-A hardness) of cleaning blade A was measured. For the measurement, a type A durometer ("Asker rubber hardness meter A type" manufactured by Kobunshi Keiki Co., Ltd.) was used.

[Manufacture of cleaning blades B to E]
Cleaning blades B to E were manufactured in the same manner as cleaning blade A, except that the raw materials used in the synthesis of urethane rubber were as shown in Table 1 below. In Table 1, "-" indicates that the corresponding component was not used.

<Method for evaluating external additive particles (evaluation device)>
First, an evaluation method (evaluation apparatus) for external additive particles (specifically, titanate compound particles or titanium oxide particles) will be described. A scanning electron microscope "JSM-7401F" manufactured by JEOL Ltd. and image analysis software ("WinROOF" manufactured by Mitani Shoji Co., Ltd.) were used to measure the number average primary particle size of the external additive particles. Also, the amount of elements in the external additive particles was measured with an inductively coupled plasma atomic emission spectrometer (“SPS1200VR” manufactured by Seiko Instruments Inc.). The powder X-ray diffraction pattern of the external additive particles was measured using a powder X-ray diffractometer ("RINT (registered trademark)-TTR III" manufactured by Rigaku Corporation, characteristic X-ray: Cu-Kα ray).

Also, the dielectric constant and the number average circularity of the external additive particles were measured by the methods described below.

[Method for measuring dielectric constant]
1 g of the external additive particles were compressed for 2 minutes at a pressure of 200 kg/cm ² to form a disk-shaped pellet (measurement sample) having a diameter of 25 mm and a thickness of 1 mm. Next, the measurement sample was set in a rotary rheometer ("ARES-G2" manufactured by TA Instruments) equipped with a dielectric constant measuring jig (electrode) having a diameter of 25 mm. Then, using an LCR meter (“4284A Precision LCR meter” manufactured by Keysight Technologies Inc.), the measurement sample (external additive The dielectric constant of the particles) was obtained.

[Method for measuring number average circularity]
The external additive particles were photographed with a transmission electron microscope (TEM) (“H-7100FA” manufactured by Hitachi High-Technologies Corporation), and the obtained image was analyzed with image analysis software (“WinROOF” manufactured by Mitani Shoji Co., Ltd.). Specifically, 100 particles were randomly selected from the external additive particles present in the image, and the circularity of each particle (perimeter of a circle equal to the projected area of the particle/perimeter of the particle) was measured. . A number average value was calculated from the measured circularity of 100 particles, and the obtained value was defined as the number average circularity of the external additive particles.

<Preparation of external additive particles>
A method for preparing the external additive particles A to L will be described below.

[Preparation of External Additive Particles I]
(Reaction preparation step)
First, the reaction preparatory step will be explained. A 4N sodium hydroxide aqueous solution was added to titanyl sulfate (manufactured by Yoneyama Pharmaceutical Co., Ltd.) to prepare a suspension of pH 9.0 (desulfurization treatment). Hydrochloric acid was then added to the resulting suspension to adjust the pH of the suspension to 5.8. Then, the suspension adjusted to pH 5.8 was filtered (solid-liquid separation), and the obtained solid content was washed with water. Next, ion-exchanged water was added to the washed solid content to obtain a slurry having a Ti concentration of 2.13 mol/L. Hydrochloric acid was added to the resulting slurry (peptization). The pH of the slurry after deflocculation was 1.4. Then, the peptized slurry (1.877 mol in terms of TiO ₂ ) was put into a 3 L reactor. Next, an aqueous solution of strontium chloride (SrCl ₂ ) was charged into the reaction vessel in an amount of 2.159 mol in terms of Sr. The contents of the reaction vessel after charging the strontium chloride aqueous solution (hereinafter referred to as the contents of the vessel) had a Sr/Ti molar ratio (Sr/Ti) of 1.15. Next, an aqueous solution of lanthanum chloride (LaCl ₃ ) was charged into the reaction vessel in an amount of 0.216 mol calculated as La. After the lanthanum chloride aqueous solution was added, the contents of the container had a La/Sr molar ratio (La/Sr) of 0.10. Next, 0.0188 mol of niobium pentoxide (Nb ₂ O ₅ ) in terms of Nb was introduced into the reactor. After charging niobium pentoxide, the contents of the container had a molar ratio (Nb/Ti) of Nb and Ti of 0.01. Then, ion-exchanged water was added to the container contents to obtain a slurry with a Ti concentration of 0.939 mol/L.

(Reaction step)
Next, the reaction process will be explained. While stirring the slurry (concentration of Ti: 0.939 mol/L) obtained by the above procedure, the internal temperature of the reaction vessel was raised to 90° C., and then 553 mL of sodium hydroxide aqueous solution was added to the reaction vessel. (Concentration of NaOH: 10 mol/L) was added at a constant rate over 1 hour. Then, after raising the internal temperature of the reaction vessel to 95°C, the contents of the reaction vessel were stirred for 1 hour while maintaining the internal temperature of the reaction vessel at 95°C. Next, the contents of the container were cooled to a temperature of 50° C., and hydrochloric acid was added to the cooled contents of the container to adjust the pH of the contents of the container to 5.0. Then, the contents of the reaction vessel were stirred for 1 hour while maintaining the internal temperature of the reaction vessel at 50° C. to obtain a precipitate.

The obtained precipitate was washed by decantation and filtered (solid-liquid separation). The obtained solid content was dried in the atmosphere at a temperature of 120° C. for 10 hours to obtain a powder of external additive particles I, which are titanate compound particles containing lanthanum and niobium.

(Number average primary particle size, number average circularity, and powder X-ray diffraction pattern)
The number average primary particle diameter of the obtained external additive particles I was 30 nm. The number average circularity of the obtained external additive particles I was 0.84. Also, the peak position of the powder X-ray diffraction pattern of the obtained external additive particles I coincided with the peak position of the powder X-ray diffraction pattern of the perovskite crystal structure of strontium titanate (base material). That is, the external additive particles I were strontium titanate particles doped with lanthanum and niobium. The number average primary particle diameter, number average circularity, and powder X-ray diffraction pattern of the external additive particles I are all measured for the external additive particles I separated from the toner particles after the toner is produced by the method described later. The same results were obtained when powder was used as the measurement target. The same applies to external additive particles A to H and J to L, which will be described later.

External additive particles A to H and J to K were prepared in the same manner as the preparation of external additive particles I, except for the following changes.

[Preparation of External Additive Particles A]
In the preparation of the external additive particles A, in the reaction preparation step, the amount of niobium pentoxide (Nb ₂ O ₅ ) introduced into the reaction vessel was changed to 0.0019 mol in terms of Nb.

[Preparation of External Additive Particles B]
In the preparation of the external additive particles B, an aqueous solution of lanthanum chloride (LaCl ₃ ) was not put into the reaction vessel in the reaction preparatory step.

[Preparation of External Additive Particles C]
In the preparation of the external additive particles C, in the reaction preparation step, the amount of the aqueous solution of lanthanum chloride (LaCl ₃ ) charged into the reaction vessel was changed to 0.065 mol in terms of La.

[Preparation of External Additive Particles D]
In the preparation of the external additive particles D, in the reaction preparation step, the amount of the aqueous solution of lanthanum chloride (LaCl ₃ ) charged into the reaction vessel was changed to 0.073 mol in terms of La.

[Preparation of External Additive Particles E]
In the preparation of the external additive particles E, an aqueous solution of calcium chloride (CaCl _{2 ) was used instead of an aqueous solution of strontium chloride (SrCl 2 )} in the reaction preparation step. The amount of calcium chloride (CaCl ₂ ) introduced into the reaction vessel in the preparation of the external additive particles E was 2.1590 mol in terms of Ca.

[Preparation of External Additive Particles F]
In the preparation of the external additive particles F, tantalum pentoxide (Ta ₂ O ₅ ) was used instead of niobium pentoxide (Nb ₂ O ₅ ) in the reaction preparation step. The amount of tantalum pentoxide introduced into the reaction vessel in the preparation of the external additive particles F was 0.0188 mol in terms of Ta.

[Preparation of External Additive Particles G]
In the preparation of the external additive particles G, vanadium pentoxide (V ₂ O ₅ ) was used instead of niobium pentoxide (Nb ₂ O ₅ ) in the reaction preparatory step. The amount of vanadium pentoxide introduced into the reaction vessel in the preparation of the external additive particles G was 0.0188 mol in terms of V.

[Preparation of External Additive Particles H]
In the preparation of the external additive particles H, niobium pentoxide (Nb ₂ O ₅ ) was not put into the reaction vessel in the reaction preparatory step.

[Preparation of External Additive Particles J]
In the preparation of the external additive particles J, in the reaction preparation step, the amount of niobium pentoxide (Nb ₂ O ₅ ) introduced into the reaction vessel was changed to 0.0564 mol in terms of Nb.

[Preparation of External Additive Particles K]
In the preparation of the external additive particles K, the amount of niobium pentoxide (Nb ₂ O ₅ ) introduced into the reaction vessel was changed to 0.6850 mol in terms of Nb in the reaction preparation step.

The peak positions of the powder X-ray diffraction patterns of the external additive particles A to D and F to K coincided with the peak positions of the powder X-ray diffraction pattern of the perovskite crystal structure of strontium titanate (base material). That is, external additive particles A to D and I to K were strontium titanate particles doped with lanthanum and niobium. External additive particles F were strontium titanate particles doped with lanthanum and tantalum. The external additive particles G were strontium titanate particles doped with lanthanum and vanadium. The external additive particles H were lanthanum-doped strontium titanate particles.

The peak position of the powder X-ray diffraction pattern of the external additive particles E coincided with the peak position of the powder X-ray diffraction pattern of the perovskite crystal structure of calcium titanate (base material). That is, the external additive particles E were calcium titanate particles doped with lanthanum and niobium.

[Preparation of External Additive Particles L]
A mixture of titanium tetrachloride and oxygen gas produced by the chlorine method was introduced into the gas phase oxidation reactor. Subsequently, titanium oxide (bulk) was obtained by subjecting the mixture to gas-phase oxidation reaction at a temperature of 1,000° C. in the reactor. After that, the obtained titanium oxide (bulk) was pulverized using a hammer mill. Subsequently, the obtained pulverized titanium oxide was washed and then dried at a temperature of 110°C. Further, the dried pulverized titanium oxide was pulverized using a jet mill. As a result, titanium oxide particles (number average primary particle size: 90 nm, crystal type: rutile type) were obtained. The number average primary particle size of the titanium oxide particles was adjusted by setting the hammer mill. These titanium oxide particles were used as the external additive particles L.

Table 2 shows the amount of Group 5 elements of the periodic table, the amount of lanthanum, and the dielectric constant of each of the external additive particles A to L. In Table 2, the amount of Group 5 elements of the periodic table and the amount of lanthanum are both amounts relative to the total mass of the external additive particles (unit: % by mass). In addition, in Table 2, "-" in the amount added indicates that the corresponding component was not added. "-" in the amount indicates that it was less than the detection limit of the inductively coupled plasma atomic emission spectrometer used for the measurement (0.01 mass ppm with respect to the total mass of the external additive particles). The amount of Group 5 elements of the periodic table, the amount of lanthanum, and the relative permittivity of each external additive particle are determined by each external additive particle separated from the toner particles after the toner is produced by the method described later. The same results were obtained when the powder was measured.

<Preparation of Toner>
A method for producing toner TA to toner TL will be described below.

[Synthesis of polyester resin A]
1.0 mol of bisphenol A ethylene oxide adduct (average number of added moles of ethylene oxide: 2 mol), 4.5 mol of terephthalic acid, 0.5 mol of trimellitic anhydride, and 4.0 g of dibutyl tin oxide. , was placed in the reaction vessel. Subsequently, the contents of the container were reacted at a temperature of 230° C. for 8 hours under atmospheric pressure in a nitrogen atmosphere. Thereafter, the pressure in the container was reduced to 8.3 kPa, and unreacted components were distilled off under reduced pressure to obtain polyester resin A (binder resin) having a softening point (Tm) of 120°C.

[Preparation of Toner TA-1]
(Preparation step of toner base particles)
100 parts by mass of a binder resin (polyester resin A), 4 parts by mass of carbon black (“Regal (registered trademark) 330R” manufactured by Cabot Corporation) as a coloring agent, and carnauba wax (manufactured by Kato Yoko Co., Ltd. “Carnauba No. 1”) and 3 parts by mass of a quaternary ammonium salt compound (“Acrybase (registered trademark) FCA-210-PS” manufactured by Fujikura Kasei Co., Ltd.) as a charge control agent were mixed in an FM mixer (Japan "FM-10B" manufactured by Coke Kogyo Co., Ltd.), and then mixed for 4 minutes at a rotational speed of 2000 rpm.

Subsequently, the resulting mixture was melt-kneaded at a temperature of 150° C. using a twin-screw extruder (“TEM-45” manufactured by Toshiba Machine Co., Ltd.). After that, the obtained kneaded product was cooled. Subsequently, the cooled kneaded product is coarsely pulverized using a pulverizer ("Rotoplex (registered trademark) 350 x 600 type" manufactured by Hosokawa Micron Corporation) so that the volume median diameter (D ₅₀ ) is about 2 mm. bottom. The obtained coarsely pulverized material was finely pulverized using a supersonic jet pulverizer (“Jet Mill IDS-2” manufactured by Nippon Pneumatic Industry Co., Ltd.). Subsequently, the obtained finely pulverized material was classified using a classifier ("EJ-LABO model EJ-L-3" manufactured by Nittetsu Mining Co., Ltd.). As a result, toner base particles having a volume median diameter (D ₅₀ ) of 7.0 μm were obtained. The volume median diameter (D ₅₀ ) of the toner base particles was measured using a particle size meter (“Coulter Counter Multisizer 3” manufactured by Beckman Coulter, Inc.).

(External addition process)
100 parts by mass of toner base particles (toner base particles obtained in the preparation process described above) and 1.5 parts by weight of positively charged silica particles (manufactured by Cabot Corporation "CAB-O-SIL (registered trademark) TG-308F ”) and 0.60 parts by mass of the external additive particles A were put into an FM mixer (“FM-10B” manufactured by Nippon Coke Industry Co., Ltd.). Next, using the FM mixer, the toner base particles and the external additive (external additive particles A and positively chargeable silica particles) were mixed for 15 minutes under the conditions of a rotation speed of 3500 rpm and a jacket temperature of 20.degree. As a result, the entire amount of the external additive was adhered to the surface of the toner base particles. As a result, a positively chargeable toner TA-1 was obtained.

[Production of Toners TA-2 to TA-12 and TB-1 to TB-5]
Positively chargeable toners TA-2 to TA-12 and TB- were prepared in the same manner as toner TA-1 except that the type and amount of the external additive particles were as shown in Table 3 below. 1 to TB-5 were produced respectively. In Table 3, "-" in the column of external additive particles means that external additive particles A to L were not used.

[Preparation of two-component developer]
(Process of manufacturing carrier)
A ferrite core (“EF-35B” manufactured by Powdertech Co., Ltd., volume median diameter (D ₅₀ ): 35 μm) was prepared as a carrier core. Further, as a liquid (coating liquid) containing raw materials for the coating layer covering the carrier core, 100 parts by mass of toluene and a heat-curable silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd. "KR-220L", curing start temperature: 170 ° C.) A mixed solution with 20 parts by mass (solid concentration: 17% by mass) was prepared. 1,000 parts by mass of the ferrite core is put into a rolling fluidized bed coating device (“Spiracoater (registered trademark) SP-25” manufactured by Okada Seiko Co., Ltd.), and the coating liquid is applied toward the ferrite core while flowing the ferrite core. 120 parts by mass were sprayed. Subsequently, the ferrite core covered with the coating liquid is heat-treated at a temperature of 200° C. for 2 hours to obtain carrier particles in which the entire surface of the ferrite core is covered with a coating layer (a layer made of silicone resin). A powder (carrier) was obtained.

(Mixing process of carrier and toner)
100 parts by mass of the carrier obtained by the above production process and 10 parts by mass of toner (any one of toners TA-1 to TA-12 and TB-1 to TB-5) were mixed for 30 minutes using a ball mill. By mixing, a two-component developer for evaluation was prepared.

<Preparation of image forming apparatus>
The methods of manufacturing the image forming apparatuses of Examples 1 to 14 and Comparative Examples 1 to 8 will be described below.

A cleaning member (cleaning blade) was removed from a color multifunction machine A (“TASKalfa (registered trademark) 8052ci” manufactured by Kyocera Document Solutions Inc.), and a cleaning blade B was mounted instead. The cleaning blade B was brought into pressure contact with the surface of the photosensitive drum, which is the image carrier. In the color multifunction machine A, in a cross-sectional view of the image carrier, when an imaginary straight line connecting the contact points of the image carrier and the cleaning member and the center O of the image carrier is defined as a line segment X, the line segment X is a horizontal plane. The angle θ formed with respect to Y was 0 degrees. In other words, in the color multifunction machine A, the cleaning member is arranged on the side of the image bearing member. In addition, a two-component developer (two-component developer containing toner TA-1) is put into the black developing device of color multifunction machine A, and replenishment toner (same toner as the toner contained in the two-component developer) is added. It was put into the black toner container of the color multifunction machine A. Thus, an image forming apparatus of Example 1 was obtained.

Image forming apparatuses of Examples 2 to 14 and Comparative Examples 1 to 8 were manufactured in the same manner as the image forming apparatus of Example 1, except that the following points were changed. In manufacturing the image forming apparatuses of Examples 2 to 14 and Comparative Examples 1 to 8, any one of toners TA-1 to TA-14 and TB-1 to TB-5 shown in Table 3 was used as the toner. . Further, in manufacturing the image forming apparatuses of Examples 2 to 14 and Comparative Examples 1 to 8, any one of cleaning blades A to E shown in Table 3 was used as the cleaning blade.

Furthermore, in the manufacture of the image forming apparatus of Comparative Example 5, instead of the color multifunction machine A, a color multifunction machine B (“TASKalfa (registered trademark) 8002i” manufactured by Kyocera Document Solutions Inc.) was used. In the color multifunction machine B, a cleaning blade is arranged vertically above the central axis of the image bearing member. In the color multifunction machine B, in a cross-sectional view of the image carrier, when an imaginary straight line connecting the contact points of the image carrier and the cleaning member and the center O of the image carrier is defined as a line segment X, the line segment X is a horizontal plane. The angle θ formed with Y was 90 degrees.

<Evaluation>
A first test and a second test were performed using an evaluation machine (one of the image forming apparatuses of Examples 1 to 14 and Comparative Examples 1 to 8). Then, image streaks, photoreceptor pinholes and fogging (specifically, LL fogging and replenishment fogging) of images formed by each evaluation machine were evaluated. Evaluation results are shown in Table 4 below.

[First test]
An image with a print rate of 5% was printed on 100,000 sheets of printing paper (A4 size) using the evaluation machine under a normal temperature and normal humidity environment with a temperature of 23° C. and a humidity of 50% RH. Next, the evaluator was allowed to stand for 24 hours in a low-temperature, low-humidity environment with a temperature of 10° C. and a humidity of 10% RH. Next, under a low-temperature, low-humidity environment with a temperature of 10° C. and a humidity of 10% RH, intermittent printing was performed on a total of 5,000 sheets of printing paper (A4 size plain paper) at a printing rate of 2%, three sheets at a time. In the intermittent printing, every time printing was performed on three sheets of printing paper, the third sheet of printing paper was used as the evaluation paper. Then, using a reflection densitometer ("SpectroEye (registered trademark)" manufactured by X-Rite), the reflection density A of the non-printed portion of the evaluation paper was measured. In addition, the reflection density B of the unprinted printing paper was separately measured using the above-described reflection densitometer. Then, the fogging density (FD) of the evaluation paper was obtained based on the following formula.
Fog density = Reflection density A of non-printed area - Reflection density B of unprinted paper

The highest fog density (maximum fog density, FD _MAX ) was determined among the fog densities (FD) of each evaluation sheet during intermittent printing of 5000 sheets. Based on this FD _MAX , fogging (LL fogging) in a low-temperature and low-humidity environment was evaluated. Fogging was judged according to the following criteria.

(Evaluation Criteria for Fogging)
A (particularly good): FD _MAX is 0.005 or less B (good): FD _MAX is more than 0.005 and less than 0.010 C (defective): FD _MAX is 0.010 or more

In addition, 5,000 sheets of evaluation paper during intermittent printing were visually observed to confirm the presence or absence of black spots (dot-shaped image defects) caused by photoreceptor pinholes. Photoreceptor pinholes were determined according to the following criteria.

(Evaluation Criteria for Photoreceptor Pinholes)
A (particularly good): No photoreceptor pinholes occurred even on the evaluation paper printed on the 5000th sheet. B (Good): No photoreceptor pinholes occurred on the evaluation paper printed on the 4000th sheet. , Photoreceptor pinholes occurred on the evaluation sheet printed on the 5000th sheet. C (defective): Photoreceptor pinholes occurred on the evaluation sheet printed on the 4000th sheet.

[Second test]
After the first test, an image with a print ratio of 20% was continuously printed on 500 sheets of printing paper (A4 size) using an evaluation machine under a low-temperature, low-humidity environment with a temperature of 10° C. and a humidity of 10% RH. After continuous printing, the reflection density A of the non-printing area of each printing sheet was measured using the above reflection densitometer. In addition, the reflection density B of the unprinted printing paper was separately measured using the above-described reflection densitometer. Then, the fog density (FD) on the printing paper was obtained based on the above formula.

The highest fog density (maximum fog density, FD _MAX ) among the fog densities (FD) of each of 500 sheets of printing paper was obtained. Fogging (more specifically, supplemental fogging) was determined based on the criteria described above.

In addition, each of the 500 sheets of printing paper was visually observed to confirm the presence or absence of image streaks. Image streaks were determined according to the following criteria.

(Evaluation criteria for image streaks)
A (particularly good): Image streaks were not observed.
B (Good): Image streaks were slightly confirmed.
C (Poor): Clear image streaks were confirmed.

The image forming apparatuses of Examples 1 to 14 include a developer containing toner, an image carrier, a developing device for developing an electrostatic latent image formed on the surface of the image carrier into a toner image with the developer, and an image. and a cleaning member that is pressed against the surface of the carrier. An angle formed by a line segment X with respect to a horizontal plane Y when an imaginary straight line connecting the contact points of the image carrier and the cleaning member and the center O of the image carrier is defined as a line segment X in a cross-sectional view of the image carrier. θ was 0 degrees or more and 30 degrees or less. The type A durometer hardness of the cleaning member was 65 degrees or more and 80 degrees or less. The toner contained toner particles. The toner particles consisted of toner base particles containing a binder resin and external additives adhering to the surfaces of the toner base particles. The external additive contained titanate compound particles doped with lanthanum and a Group 5 element of the periodic table as external additive particles. The amount of lanthanum was 1.50% by mass or more with respect to the total mass of the titanate compound particles. The amount of the Group 5 element of the periodic table was 0.01% by mass or more and 0.30% by mass or less with respect to the total mass of the titanate compound particles.

As shown in Table 4, in the image forming apparatuses of Examples 1 to 14, image streaks, fogging, LL fogging, and replenishment fogging were all good or particularly good. That is, the image forming apparatuses of Examples 1 to 14 were able to suppress the occurrence of fogging, image streaks, and photoreceptor pinholes.

On the other hand, the image forming apparatuses of Comparative Examples 1 to 8 did not have at least one of the above configurations. Specifically, in the image forming apparatuses of Comparative Examples 1 and 2, the type A durometer hardness of the cleaning member (cleaning blade) was less than 65 degrees or greater than 80 degrees. As a result, in the image forming apparatuses of Comparative Examples 1 and 2, the cleaning member could not remove the titanic acid compound particles adhering to the surface of the photoreceptor drum, and the surface of the photoreceptor drum was stained in streaks. Accordingly, in the image forming apparatuses of Comparative Examples 1 and 2, it is determined that image streaks have occurred.

In the image forming apparatus of Comparative Example 3, the titanate compound particles contained in the toner contained no group 5 element. As a result, in the image forming apparatus of Comparative Example 3, it was determined that the titanic acid compound particles were excessively charged and photoreceptor pinholes were generated.

In the image forming apparatus of Comparative Example 4, the titanate compound particles contained in the toner contained an excessive amount of Group 5 elements. As a result, the image forming apparatus of Comparative Example 4 could not stably maintain the charge amount of the toner, and it was determined that the LL fogging was unsatisfactory.

In the image forming apparatus of Comparative Example 5, the angle θ of the cleaning member was over 30 degrees. As a result, in the image forming apparatus of Comparative Example 5, the toner particles scraped off by the cleaning member reattached to the image carrier, and the toner particles continued to remain on the image carrier. As a result, it is determined that the image forming apparatus of Comparative Example 5 was excessively charged with titanic acid compound particles and caused photoreceptor pinholes.

In the image forming apparatus of Comparative Example 6, the titanate compound particles contained in the toner did not contain lanthanum. Therefore, the titanate compound particles used in the image forming apparatus of Comparative Example 6 had a nearly cubic shape and relatively high resistivity. As a result, in the image forming apparatus of Comparative Example 6, the surface of the photoreceptor was excessively polished, resulting in image streaks. Further, the image forming apparatus of Comparative Example 6 could not suppress LL fogging in a low-temperature, low-humidity environment where resistance tends to increase.

In the image forming apparatus of Comparative Example 7, the toner contained no titanate compound particles. As a result, the image forming apparatus of Comparative Example 7 could not suppress replenishment fogging.

In the image forming apparatus of Comparative Example 8, the toner contained titanium oxide particles instead of titanate compound particles. As a result, the image forming apparatus of Comparative Example 8 could not suppress LL fogging and replenishment fogging. In addition, in the image forming apparatus of Comparative Example 8, the cleaning member could not remove the titanium oxide particles adhering to the surface of the photoreceptor drum, and the surface of the photoreceptor drum was stained in streaks. As a result, it is determined that image streaks have occurred in the image forming apparatus of Comparative Example 8. FIG.

The image forming apparatus according to the present invention can be used for forming images, for example, as a multifunction machine or printer.

1 Developing Device 10 Developing Roller 11 Shaft 12 Magnet Roll 13 Sleeves 13a, 13b Flange 130 Sleeve Substrate 132 Sleeve Coat Layer 20 Photosensitive Drum 21 Charging Device 22 Exposure Device 23 Cleaning Member 30 Toner Charging Member 40 Toner Supply Roller 60 Toner Particles 61 Toner base particles 62 Specific titanate compound particles (titanate compound particles)
R housing part

Claims (8)

a developer including toner;
an image carrier;
a developing device that develops the electrostatic latent image formed on the surface of the image carrier into a toner image with the developer;
an image forming apparatus comprising: a cleaning member that is pressed against the surface of the image carrier,
In a cross-sectional view of the image carrier, when an imaginary straight line connecting the points of contact of the image carrier and the cleaning member and the center O of the image carrier is defined as a line segment X, the line segment X is a horizontal plane Y The angle θ formed with respect to is 0 degrees or more and 30 degrees or less,
The type A durometer hardness of the cleaning member is 65 degrees or more and 80 degrees or less,
the toner comprises toner particles;
The toner particles comprise toner base particles containing a binder resin and an external additive adhering to the surface of the toner base particles,
The external additive contains titanate compound particles doped with lanthanum and a Group 5 element of the periodic table as external additive particles,
The amount of lanthanum is 1.50% by mass or more with respect to the total mass of the titanate compound particles,
The image forming apparatus, wherein the amount of the Group 5 element of the periodic table is 0.01% by mass or more and 0.30% by mass or less with respect to the total mass of the titanate compound particles. 2. The image forming apparatus according to claim 1, wherein said Group 5 element of the periodic table is one or more elements selected from the group consisting of vanadium, niobium and tantalum. 3. The image forming apparatus according to claim 1, wherein the titanate compound particles have a number average circularity of 0.79 or more and 1.00 or less. The titanate compound particles are
Strontium titanate particles doped with said lanthanum and said Group 5 element of the periodic table, or calcium titanate particles doped with said lanthanum and said Group 5 element of the periodic table. 1. The image forming apparatus according to claim 1. The image forming apparatus according to any one of claims 1 to 4, wherein the amount of the titanate compound particles is 0.1 parts by mass or more and 1.2 parts by mass or less with respect to 100 parts by mass of the toner base particles. . The image forming apparatus according to any one of claims 1 to 5, wherein the amount of lanthanum is 12.00% by mass or less with respect to the total mass of the titanate compound particles. The image forming apparatus according to any one of claims 1 to 6, wherein the titanate compound particles have a number average primary particle diameter of 20 nm or more and 80 nm or less. The image forming apparatus according to any one of claims 1 to 7, wherein the titanate compound particles have a dielectric constant of 120 or more and 1,000 or less.

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