JP2020184042A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can form a high-density image even after printing on a large number of sheets (for example, 200,000 sheets), while preventing occurrence of fogging and a photoreceptor pinhole.SOLUTION: An image forming apparatus comprises a developing device 1 that is configured to develop an electrostatic latent image with toner. The developing device 1 includes a storage unit R that stores the toner, and a toner carrier that carries the toner supplied from the storage unit R. The toner carrier has a shaft 11, and a sleeve 13 that is rotatable around the shaft 11. The sleeve 13 has a sleeve base body 130 that contains aluminum, and a sleeve coat layer 132 that covers a surface of the sleeve base body 130. The sleeve coat layer 132 contains trivalent chromium and cobalt. The toner includes toner particles 60. The toner particles 60 include toner base particles 61 and an external additive. The external additive includes titanate compound particles 62.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus.

An image forming apparatus that forms an image using toner is required to be able to suppress fog even in printing in a low temperature and low humidity environment. For this reason, toners containing titanium acid compound particles (more specifically, strontium titanate particles and the like) are being studied as external additive particles. Since the titanium acid compound has a relatively high relative permittivity, the amount of charge of the toner can be stably maintained. Therefore, an image forming apparatus using titanium acid compound particles as an external additive for the toner can suppress fog.

However, since the titanium acid compound particles generally have a polyhedral shape (specifically, a polyhedral shape having corners), for example, the surface of the developing roller (toner carrier) becomes excessive due to the titanium acid compound particles during printing of a large number of sheets. May be polished. If the surface of the toner carrier is excessively polished, the toner carrier cannot properly convey the toner, and the image density decreases. Further, in an image forming apparatus using titanium acid compound particles as an external additive for toner, pinholes are likely to occur in the photoconductor, and dot-shaped image defects tend to occur.

In the toner described in Patent Document 1, lanthanum-doped titanium acid compound particles (hereinafter, may be referred to as lanthanum-doped titanium acid compound particles) are used as external additive particles. Since the lanthanum-doped titanium acid compound particles have a shape close to a sphere, excessive polishing of the surface of the toner carrier can be alleviated to some extent by using a toner containing the lanthanum-doped titanium acid compound particles as the external additive particles.

JP-A-2018-155912

However, only the technique disclosed in Patent Document 1 can obtain an image forming apparatus capable of maintaining a high image density even after printing a large number of sheets (for example, 200,000 sheets) while suppressing the occurrence of fog and photoconductor pinholes. It's difficult.

The present invention has been made in view of the above problems, and an object of the present invention is to produce high-density images even after printing a large number of sheets (for example, 200,000 sheets) while suppressing the occurrence of fog and photoconductor pinholes. It is to provide an image forming apparatus which can form.

The image forming apparatus according to the present invention includes a developing apparatus configured to develop an electrostatic latent image with toner. The developing device includes an accommodating portion for accommodating the toner and a toner carrier for supporting the toner supplied from the accommodating portion. The toner carrier has a shaft and a sleeve that is rotatable around the shaft. The sleeve has a sleeve substrate containing aluminum and a sleeve coat layer that covers the surface of the sleeve substrate. The sleeve coat layer contains trivalent chromium and cobalt. The toner contains toner particles. The toner particles include a toner mother particle containing a binder resin and an external additive adhering to the surface of the toner mother particle. The external additive contains titanium acid compound particles doped with a lanthanum and a Group 5 element of the periodic table as external additive particles. The amount of the lanthanum is 1.50% by mass or more with respect to the total mass of the titanium acid compound particles. The amount of the Group 5 element in 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 titanium acid compound particles.

According to the present invention, it is possible to provide an image forming apparatus capable of forming a high-density image even after printing a large number of sheets (for example, 200,000 sheets) while suppressing the occurrence of fog and photoconductor pinholes.

It is a figure which shows the structure of a part of the image forming apparatus which concerns on this invention. It is a figure which shows the structure of the developing roller in the image forming apparatus of FIG. It is a figure which shows the structure of the sleeve of the developing roller in the image forming apparatus of FIG. It is a figure which shows the composition of the toner particle in the image forming apparatus of FIG.

Hereinafter, preferred embodiments of the present invention will be described. First, terms used in the present specification will be described. Toner is an aggregate of toner particles (for example, powder). The external additive is an aggregate of external additive particles (for example, powder). Unless otherwise specified, the evaluation results (values indicating the shape, physical properties, etc.) of the powder (more specifically, the powder of the toner particles, the powder of the external additive particles, etc.) are obtained from the powder. It is the number average of the values measured for each of the particles selected in a considerable number.

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

The strength of chargeability is the ease of triboelectric charging unless otherwise specified. For example, a standard carrier provided by the Japan Imaging Society (standard carrier for negatively charged polar toner: N-01, standard carrier for positively charged polar toner: P-01) and a measurement target (for example, toner) are mixed and stirred. Then, the measurement target is triboelectrically charged. Before and after triboelectric charging, for example, a suction-type compact charge amount measuring device (“MODEL 212HS” manufactured by Trek Co., Ltd.) measures the charge amount to be measured. The larger the change in the amount of charge before and after triboelectric charging, the stronger the chargeability.

The "main component" of a material, unless otherwise specified, means the component most abundant in the material on a mass basis.

The strength of hydrophobicity can be expressed, for example, by the contact angle of water droplets (easiness of getting wet with water). The larger the contact angle of water droplets, the stronger the hydrophobicity. The hydrophobizing treatment refers to a treatment for strengthening the hydrophobicity.

The "alkyl group having 3 or more carbon atoms and 8 or less carbon atoms" is linear or branched and unsubstituted. Examples of the alkyl group having 3 or more carbon atoms and 8 or less carbon atoms include an n-propyl group, an n-butyl group, an isobutyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, and an n-octyl group. Be done.

The "Periodic Table" refers to the periodic table of long-period elements based on the provisions of the IUPAC (International Union of Pure and Applied Chemistry). The "Group 5 element of the periodic table" is at least one element selected from vanadium (V), niobium (Nb), tantalum (Ta) and dubnium (Db). The "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 titanium acid compound as a main component. The content of the titanium acid compound in the titanium acid compound particles is preferably 99% by mass or more and 100% by mass or less with respect to the total mass of the titanium acid compound particles.

Hereinafter, the compound and its derivative may be collectively referred to by adding "system" after the compound name. When the polymer name is represented 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, "elements (more specifically, lanthanum, Group 5 element of the periodic table, etc.) are doped" means a part of the elements constituting the crystal of the titanium acid compound as the base material. However, it means that it is replaced with an element different from the element constituting the base material (more specifically, a lantern, an element of Group 5 of the periodic table, etc.).

<Image forming device>
The image forming apparatus according to the present embodiment includes a developing apparatus configured to develop an electrostatic latent image with toner. The developing device includes an accommodating portion for accommodating toner and a toner carrier for supporting the toner supplied from the accommodating portion. The toner carrier has a shaft and a sleeve that is rotatable around the shaft. The sleeve has a sleeve substrate and a sleeve coat layer that covers the surface of the sleeve substrate. The sleeve has an aluminum-containing sleeve substrate and a sleeve coat layer that covers the surface of the sleeve substrate. The sleeve coat layer contains trivalent chromium and cobalt. The toner contains toner particles. The toner particles include a toner mother particle containing a binder resin and an external additive adhering to the surface of the toner mother particle. The external additive contains titanium acid compound particles (hereinafter, may be referred to as specific titanium acid compound particles) doped with a lanthanum and a Group 5 element of the periodic table as the external additive particles. The amount of lanthanum is 1.50% by mass or more with respect to the total mass of the titanium acid compound particles. The amount of Group 5 elements in 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 titanium acid compound particles.

Hereinafter, the amount of lanthanum with respect to the total mass of the specific titanic acid compound particles may be simply referred to as "amount of lanthanum". In addition, the amount of Group 5 elements in the periodic table with respect to the total mass of the specific titanic acid compound particles may be simply referred to as "amount of Group 5 elements in the periodic table". Both the amount of lantern and the amount of Group 5 elements in the periodic table are measured by an inductively coupled plasma emission spectrophotometer.

By providing the above-described configuration, the image forming apparatus according to the present embodiment forms a high-density image even after printing a large number of sheets (for example, 200,000 sheets) while suppressing the occurrence of fog and photoconductor pinholes. it can. The reason is presumed as follows.

General titanate compound particles tend to be easily charged. Therefore, in an image forming apparatus using general titanium acid compound particles as an external additive for toner, the titanium acid compound particles may be discharged to the surface of the photoconductor drum. This phenomenon is particularly likely to occur in a low temperature and low humidity environment. When the titanium acid compound particles are discharged to the surface of the photoconductor drum, pinholes may occur on the surface of the photoconductor drum. Pinholes on the surface of the photoconductor drum cause dot-shaped image defects (for example, generation of black spots).

On the other hand, in the image forming apparatus according to the present embodiment, the specific titanic acid compound particles doped with a certain amount or more of Group 5 elements of the periodic table are used as the outer additive particles of the toner. Group 5 elements of the periodic table moderately reduce the electrical resistance of the specific titanium acid compound particles. Therefore, the image forming apparatus according to the present embodiment can suppress excessive charging of the specific titanium acid compound particles. Therefore, the image forming apparatus according to the present embodiment can suppress the occurrence of photoconductor pinholes.

In addition, the specific titanic acid compound particles are also doped with a certain amount or more of lanthanum. The lanthanum-doped titanium acid compound particles have a shape close to a sphere. Therefore, the image forming apparatus according to the present embodiment can suppress excessive polishing of the toner carrier by the toner. Therefore, the image forming apparatus according to the present embodiment can form a high-density image even after printing a large number of sheets (for example, 200,000 sheets).

Further, since the specific titanium acid compound particles contain a titanium acid compound having a relatively high relative permittivity, the charge amount of the toner can be stably maintained. In addition, toner using external additive particles having an excessively low electrical resistance is usually prone to fogging. However, the specific titanic acid compound particles have a constant electric resistance because the amount of Group 5 elements in the periodic table is 0.30% by mass or less with respect to the total mass. Therefore, the image forming apparatus according to the present embodiment can suppress the occurrence of fog.

Further, the toner carrier provided in the image forming apparatus according to the present embodiment includes a sleeve having a sleeve substrate and a sleeve coat layer. The sleeve coat layer contains trivalent chromium and cobalt. Since the toner carrier has a sleeve coat layer, the surface is less likely to wear even if image formation is repeated. Further, the sleeve coat layer containing trivalent chromium and cobalt can suppress the influence on the charge amount of the toner as compared with other sleeve coat layers (for example, a nickel plating layer or a chrome plating layer). As a result, the image forming apparatus according to the present embodiment can more reliably form a high-density image even after printing a large number of sheets (for example, 200,000 sheets) while more reliably suppressing the occurrence of fog.

Hereinafter, an example of the configuration of the image forming apparatus according to the present embodiment will be shown with reference to the drawings. The image forming apparatus shown below is an image forming apparatus in the case of performing image forming using a one-component developer. However, the image forming apparatus of the present embodiment also includes an image forming apparatus in the case of performing image forming 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. FIG. 1 is a diagram showing a partial configuration of an image forming apparatus according to the present embodiment. Specifically, FIG. 1 mainly describes a configuration centered on a developing device and a photoconductor drum included in the image forming device according to the present embodiment. FIG. 2 is a diagram showing a configuration of a developing roller included in the image forming apparatus according to the embodiment of the present invention.

As shown in FIG. 1, the developing device 1 of the image forming apparatus according to the present embodiment includes a developing roller 10 as a toner carrier and an accommodating portion R accommodating toner. Hereinafter, the structure of the developing roller 10 will be described, and then the structure of the toner will be described.

The developing roller 10 is configured to support the toner supplied from the accommodating portion R. As shown in FIGS. 1 and 2, such a developing roller 10 includes a shaft 11, a magnet roll 12, and a tubular sleeve 13. The magnet roll 12 is fixed to the shaft 11 and is located in the sleeve 13 (inside the cylinder). Further, the magnet roll 12 has a magnetic pole at least on its surface layer. Examples of the magnetic poles of the magnet roll 12 include N pole and S pole based on a permanent magnet. The sleeve 13 is located on the surface layer of the developing roller 10 and is supported so as to be able to rotate around the shaft 11. Specifically, the shaft 11 and the sleeve 13 are connected by flange portions 13a and 13b so that the sleeve 13 can rotate around the non-rotating magnet roll 12. With such a structure, the sleeve 13 can rotate in the circumferential direction of the shaft 11 (the direction of the arrow in FIG. 1).

As shown in FIGS. 1 and 2, the sleeve 13 has a sleeve base 130 and a sleeve coat layer 132. The sleeve coat layer 132 is formed on the surface of the sleeve substrate 130 and contains trivalent chromium and cobalt. The sleeve coat layer 132 is, for example, a plating layer formed by plating.

The sleeve coat layer 132 may be formed on the entire surface region of the sleeve substrate 130, but may be formed on at least the region on which the toner particles 60 are supported in the surface region of the sleeve substrate 130.

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

As shown in FIG. 1, the image forming apparatus according to the present embodiment further includes a photoconductor 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. Hereinafter, the configuration of the image forming apparatus according to the present embodiment will be further shown by showing an image forming method using the image forming apparatus shown in FIG.

In the image forming apparatus according to the present embodiment, the sleeve 13 of the developing roller 10, the photoconductor drum 20, and the toner supply roller 40 are each rotated in the direction of the arrow in FIG. 1 to form an image. Will be done.

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

Specifically, the toner supply roller 40 supplies toner from the accommodating portion 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, the toner particles 60 are supported on the surface of the sleeve 13 of the developing roller 10. The toner particles 60 supported 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. The charged toner particles 60 are supplied to the photoconductor drum 20 by the rotation of the sleeve 13 of the developing roller 10. As a result, the toner particles 60 adhere to the electrostatic latent image formed on the photosensitive layer of the photoconductor drum 20, and thus the toner image is formed on the photosensitive layer. In this way, the electrostatic latent image formed on the photosensitive layer is developed.

Subsequently, the toner image on the photosensitive layer of the photoconductor drum 20 is transferred to a recording medium (for example, printing paper). After that, the toner particles 60 are heated and pressurized by the fixing device to fix the toner particles 60 on 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.

As shown in FIG. 2, the surface of the sleeve base 130 is not formed with irregularities, and the surface of the sleeve base 130 is smooth. However, it is preferable that the sleeve substrate 130 has irregularities formed on its surface. Hereinafter, FIG. 3 shows an example of the sleeve 13 in which irregularities are formed on the surface of the sleeve substrate 130. The surface of the sleeve coat layer 132 is formed with irregularities corresponding to the irregularities formed on the surface of the sleeve substrate 130. Specifically, on the surface of the sleeve coat layer 132, a convex portion P1 corresponding to the convex portion formed on the surface of the sleeve base 130 and a concave portion P2 corresponding to the concave portion formed on the surface of the sleeve base 130 are formed. It is formed. As a result, a thin layer of toner is stably formed on the surface of the sleeve substrate 130, and the developing roller 10 facilitates the transfer of toner. As a result, the image forming apparatus according to the present embodiment can form a high-density image even after printing a large number of sheets (for example, 200,000 sheets).

The 10-point average roughness Rz of the surface of the specific sleeve substrate 130 is preferably 3 μm or more and 20 μm or less, and more preferably 6 μm or more and 9 μm or less. By setting the 10-point average roughness Rz of the surface of the sleeve substrate 130 to 3 μm or more and 20 μm or less, the developing roller 10 can more easily convey the toner. The 10-point average roughness Rz of the surface of the sleeve substrate 130 is a value measured in accordance with "JIS B 0601: 2013" of the Japanese Industrial Standards (JIS).

The sleeve substrate 130 contains aluminum. The sleeve coat layer 132 contains trivalent chromium and cobalt. The trivalent chromium contained in the sleeve coat layer 132 constitutes, for example, Cr ₂ O ₃ . From an environmental point of view, the sleeve coat layer 132 preferably contains substantially no hexavalent chromium. The content ratio of hexavalent chromium in the sleeve coat layer 132 is preferably 0.01 ppm or less, preferably 0.00 ppm.

As a method of coating the surface of the sleeve base 130 with the sleeve coat layer 132, for example, a method of plating the sleeve base 130 can be mentioned. The plating treatment can be performed by immersing the sleeve substrate 130 in an aqueous solution containing, for example, a chromium compound (for example, chromium nitrate) and a cobalt compound (for example, cobalt nitrate).

The image forming apparatus according to the present embodiment has been described above with reference to FIGS. 1 to 3. However, the image forming apparatus according to this embodiment is not limited to FIGS. 1 to 3. For example, the charging device may not be in contact with the photoconductor drum. Further, the toner charging member does not have to be in contact with the toner particles. Hereinafter, details of the toner used in the image forming apparatus according to the present embodiment will be described.

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

The amount of the Group 5 element in the periodic table is 0.01% by mass or more and 0.30% by mass or less, preferably 0.10% by mass or more, based on the total mass of the specific titanium acid compound particles.

The amount of lanthanum is 1.50% by mass or more, preferably 4.00% by mass or more, based on the total mass of the specific titanium acid compound particles. On the other hand, the amount of lanthanum is preferably 15.0% by mass or less, more preferably 10.0% by mass or less, based on the total mass of the specific titanium acid compound particles.

As the Group 5 element of the periodic table contained in the specific titanic acid 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 titanium acid compound particles in the toner is preferably 0.1 parts by mass or more and 1.2 parts by mass or less, and 0.5 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the toner mother particles. More preferred. By setting the amount of the specific titanium acid compound particles to 0.1 parts by mass or more and 1.2 parts by mass or less, the occurrence of fog can be further suppressed.

The relative permittivity of the specific titanium acid compound particles is preferably 100 or more and 1,200 or less, and more preferably 200 or more and 400 or less. By setting the relative permittivity of the specific titanium acid compound particles to 100 or more and 1,200 or less, the occurrence of fog can be further suppressed. The method for measuring the relative permittivity is the same method as in Examples described later or a method similar thereto.

The toner particles may be particles having no shell layer or particles having a shell layer (hereinafter, may be referred to as capsule toner particles). In the capsule toner particles, the toner mother particles include a toner core containing a binder resin and a shell layer that covers the surface of the toner core. The shell layer contains a resin. For example, by covering the toner core that melts at a low temperature with a shell layer having excellent heat resistance, it is possible to achieve both heat storage stability and low temperature fixability of the toner. Additives may be dispersed in the resin constituting 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.

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

Hereinafter, the composition of the toner will be described with reference to FIG. FIG. 4 is a diagram showing an example of the cross-sectional structure of the toner particles 60. In addition, FIG. 4 to be referred to is schematically shown mainly for each component for easy understanding, and the size, number, shape, etc. of each of the illustrated components are shown for convenience of drawing creation. It may be different from the actual one.

The toner particles 60 shown in FIG. 4 include a toner mother particles 61 containing a binder resin and an external additive adhering to the surface of the toner mother particles 61. The external additive contains specific titanium acid 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 matrix particles 61 is preferably 4 μm or more and 9 μm or less.

The number average circularity of the specific titanium acid compound particles 62 is preferably 0.79 or more and 1.00 or less, more preferably 0.80 or more and 1.00 or less, and further preferably 0.84 or more and 0.92 or less. By setting the number average circularity of the specific titanium acid compound particles 62 to 0.79 or more and 1.00 or less, a high-density image can be formed even after printing a large number of sheets (for example, 200,000 sheets). The method for measuring the number average circularity is the same method as in Examples described later or a method similar thereto.

The number average primary particle diameter of the specific titanium acid compound particles 62 is preferably 20 nm or more and 80 nm or less, and more preferably 20 nm or more and 40 nm or less. By setting the number average primary particle diameter of the specific titanium acid compound particles 62 to 20 nm or more and 80 nm or less, a high-density image can be formed even after printing a large number of sheets (for example, 200,000 sheets).

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

(Bundling resin)
For example, the binder resin occupies 70% by mass or more of all the components of the toner mother particles. Therefore, it is considered that the properties of the binder resin have a great influence on the properties of the entire toner matrix particles. In order to obtain a toner having excellent low-temperature fixability, the toner mother particles preferably contain a thermoplastic resin as the binder resin, and contain the thermoplastic resin in a proportion of 85% by mass or more of the entire binder resin. Is more preferable. Examples of the thermoplastic resin include styrene resin, acrylic acid ester resin, olefin resin (more specifically, polyethylene resin, polypropylene resin, etc.), vinyl resin (more specifically, vinyl chloride resin, polyvinyl chloride, etc.). (Alcohol, vinyl ether resin, N-vinyl resin, etc.), polyester resin, polyamide resin, and urethane resin can be mentioned. Further, a copolymer of each of these resins, that is, a copolymer in which an arbitrary repeating unit is introduced into the above resin (more specifically, a styrene-acrylic acid ester resin, a styrene-butadiene resin, etc.) is also available. Can be used as a binder resin.

The thermoplastic resin is obtained by addition polymerization, copolymerization, or polycondensation of one or more kinds of 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 polycondensation (for example, polycondensation). A combination of a polyhydric alcohol and a polyvalent carboxylic acid that becomes a polyester resin).

In order to obtain a toner having excellent low-temperature fixability, the toner matrix particles preferably contain a polyester resin as the binder resin, and contain the polyester resin in a proportion of 80% by mass or more and 100% by mass or less of the entire binder resin. It is more preferable to do so. The polyester resin is obtained by polycondensing one or more polyhydric alcohols and one or more polyvalent carboxylic acids. Examples of the alcohol for synthesizing the polyester resin include divalent alcohols (more specifically, aliphatic diols, bisphenols, etc.) as shown below, and trihydric or higher alcohols. Examples of the carboxylic acid for synthesizing the polyester resin include a divalent carboxylic acid and a trivalent or higher carboxylic acid as shown below. In addition, instead of the polyvalent carboxylic acid, a polyvalent carboxylic acid derivative capable of forming an ester bond by polycondensation of an anhydride of the polyvalent carboxylic acid, polyvalent carboxylic acid halide or the like may be used.

(Colorant)
The toner mother particles may contain a colorant. As the colorant, a pigment or dye known according to the color of the toner can be used. The amount 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. However, when the toner mother particles contain magnetic powder, the toner mother particles do not have to contain a colorant.

The toner mother particles may contain a black colorant. An example of a black colorant is carbon black. Further, the black colorant may be a colorant that has been toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

The toner mother particles may contain a color colorant. Examples of the color colorant include a yellow colorant, a magenta colorant, and a cyan colorant.

(Release agent)
The toner mother particles may contain a release agent. The release agent is used, for example, to obtain a toner having excellent offset resistance. In order to obtain a toner having excellent 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.

Examples of the release agent include ester wax, polyolefin wax (more specifically, polyethylene wax, polypropylene wax, etc.), microcrystalline wax, fluororesin wax, Fishertroph wax, paraffin wax, candelilla wax, and Montan wax. And Custer wax. Examples of the ester wax include natural ester wax (more specifically, carnauba wax, rice wax, etc.) and synthetic ester wax. Carnauba wax is preferable as the release agent.

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

(Charge control agent)
The toner mother particles may contain a charge control agent. The charge control agent is used, for example, to obtain a toner having excellent charge stability or charge rise characteristics. 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 time.

By incorporating a positively chargeable charge control agent into the toner mother particles, the cationicity (positive chargeability) of the toner mother particles can be strengthened. Further, by incorporating a negatively charged charge control agent into the toner mother particles, the anionic property (negative charge) of the toner mother particles can be strengthened.

Examples of positively charged charge control agents include pyridazine, pyrimidine, pyrazine, 1,2-oxazine, 1,3-oxazine, 1,4-oxazine, 1,2-thiazine, 1,3-thiazine, 1, 4-thiadine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6- Oxaziazine, 1,3,4-triazine, 1,3,5-triazine, 1,2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1, Adin compounds such as 2,4,6-oxatriazine, 1,3,4,5-oxatriazine, phthalazine, quinazoline, quinoxalin; Adinfast Red FC, Adinfast Red 12BK, Adin Violet BO, Adin Brown 3G, Adinlite Direct dyes such as Brown GR, Azine Dark Green BH / C, Azin Deep Black EW, Azin Deep Black 3RL; Acidic dyes such as Niglosin BK, Niglosin NB, Niglosin Z; Alkalkylated amines; Alkylamides; benzyldecylhexylmethyl Quaternary ammonium salts such as ammonium chloride, decyltrimethylammonium chloride, 2- (methacryloyloxy) ethyltrimethylammonium chloride, dimethylaminopropylacrylamide methyl chloride quaternary salt; resins containing a quaternary ammonium cation group can be mentioned. As the charge control agent, an acid dye or a resin containing a quaternary ammonium cationic group is preferable.

From the viewpoint of obtaining a toner having excellent charge stability, the content of the charge control agent is preferably 0.1 part 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 mother particles may contain magnetic powder. Examples of the material of the magnetic powder include ferromagnetic metals (more specifically, iron, cobalt, nickel, etc.) and their alloys, ferromagnetic metal oxides (more specifically, ferrite, magnetite, chromium dioxide, etc.). , And a material that has been subjected to a ferromagnetism treatment (more specifically, a carbon material to which ferromagnetism has been imparted by heat treatment, etc.).

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 agent)
The toner particles include an external additive attached to the surface of the toner mother particles. The external additive contains specific titanium acid compound particles as the external additive particles.

As the base material (doped titanium acid compound) of the specific titanium acid compound particles, for example, the composition is MTIO ₃ (M is a metal element other than titanium excluding lantern and Group 5 element of the periodic table. A titanium acid compound represented by (representing an element) can be mentioned. Specific examples of the titanate compound composition represented by MTiO _3, strontium titanate (SrTiO _3), barium titanate (BaTiO _3), calcium titanate (CaTiO _3), magnesium titanate (MgTiO _3), and Lead titanate (PbTiO ₃ ) can be mentioned. The crystal structure of the titanium acid compound whose composition is represented by MTIO ₃ is usually a perovskite type crystal structure.

When a titanium acid compound whose composition is represented by MTIO ₃ is used as the base material of the specific titanium acid compound particles, the lanthanum and the Group 5 element of the periodic table are, for example, the sites where the metal represented by M is arranged. By substituting, it is incorporated into the crystal structure of the base metal. Hereinafter, the site where the metal represented by M is arranged is referred to as M site. Further, the specific titanium acid compound particles obtained by substituting the M sites with the lanthanum and the Group 5 element of the periodic table are referred to as M site-substituted titanium acid compound particles.

The peak position of the powder X-ray diffraction pattern of the M-site-substituted titanium acid 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 titanium acid compound particles and the peak position of the powder X-ray diffraction pattern of the base material (titanoic acid compound represented by MTIO ₃ ) match, the base material It can be determined that the lantern and the Group 5 element of the periodic table were doped in. Regarding the powder X-ray diffraction pattern, "the peak positions match" means that the values of the diffraction angles (2θ) match in the range of ± 0.5 degrees for the two peak positions to be compared.

Specific titanium acid compound particles include strontium titanate particles doped with lantern and Group 5 element of the Periodic Table, barium titanate particles doped with lantern and Group 5 element of the Periodic Table, or lantern and Periodic Table No. 1. Calcium titanate particles doped with Group 5 elements are preferred, with strontium titanate particles doped with lanthanum and niobium, barium titanate particles doped with lanthanum and niobium, or lanthanum and niobium doped. Calcium titanate particles are more preferred. By using these specific titanium acid compound particles, it is possible to form a higher density image even after printing a large number of sheets while further suppressing the occurrence of fog and photoconductor pinholes.

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

Hereinafter, an example of a method for producing the specific titanium acid compound particles will be described. First, a treated product in which the titanium source is defibrated with mineral acid (hereinafter, may be referred to as a titanium source deflated product) and a metal element other than titanium (more specifically, strontium) constituting the base material. , Barium, calcium, etc.), the lantern source, and the element source of Group 5 of the periodic table are mixed. Then, the alkaline aqueous solution is added to the mixture while heating the obtained mixture to a temperature of 50 ° C. or higher. Then, the mixture to which the alkaline aqueous solution is 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). The resulting product is then cooled and then hydrochloric acid is added to the product to give a precipitate. Next, the obtained precipitate is washed, filtered (solid-liquid separation), and then the obtained solid content is dried to obtain a powder of the specific titanium acid compound particles.

The amount of lanthanum can be adjusted in the above example of the method for producing the specific titanium acid compound particles by, for example, changing the amount of the lanthanum source with respect to the mass of the titanium source defibrated product. The amount of the Group 5 element of the Periodic Table can be adjusted in the above example of the method for producing the specific titanium acid compound particles by changing the amount of the Group 5 element of the Periodic Table with respect to the mass of the titanium source defibrated product, for example. .. The number average circularity of the specific titanium acid compound particles can be adjusted, for example, by changing the amount of the lanthanum source with respect to the mass of the titanium source defibrated product in the above example of the method for producing the specific titanium acid compound particles. The average number of primary particle diameters of the specific titanium acid compound particles is determined by, for example, in an example of the method for producing the specific titanium acid compound particles, a mixture of a compound of a metal element other than titanium constituting the base material and a titanium source defibrated product. It can be adjusted by changing at least one of the ratio, the concentration of alkali in the alkaline aqueous solution, and the amount of the alkaline aqueous solution added. The specific dielectric constant of the specific titanium acid compound particles is determined in the above example of the method for producing the specific titanium acid compound particles, for example, the type of metal element other than titanium constituting the base material, the type of Group 5 element of the periodic table, and the titanium source. It can be adjusted by changing at least one of the amount of the Group 5 element source in the periodic table relative to the mass of the defibrated product and the amount of the lantern source relative to the mass of the titanium source deflated product.

From the viewpoint of further suppressing the occurrence of fog in a high temperature and high humidity environment, the surface of the specific titanium acid compound particles is preferably hydrophobized. As a method for obtaining the specific titanium acid compound particles whose surface has been hydrophobized, for example, particles composed of a titanium acid compound doped with a lanthanum and a Group 5 element of the periodic table (hereinafter referred to as a substrate) may be described. There is a method of treating) with a hydrophobic agent. As the hydrophobizing agent, one or more selected from silicone oil, silazane compounds, and silane compounds are preferable, silane compounds are more preferable, and silane compounds having an alkoxy group and an alkyl group having 3 to 8 carbon atoms (more specific). Specifically, n-propyltrimethoxysilane, n-propyltriethoxysilane, isobutyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, etc.) are more preferable, and isobutyltrimethoxysilane is particularly preferable.

When the surface of a substrate is treated with a silane compound having an alkoxy group and an alkyl group having 3 or more and 8 or less carbon atoms, the hydroxy group generated by hydrolyzing the alkoxy group of the silane compound with water is the surface of the substrate. It undergoes a dehydration condensation reaction with the hydroxy group present in. By such a reaction, an alkyl group (hydrophobic group) having 3 to 8 carbon atoms is imparted to the surface of the substrate. That is, the surface of the specific titanoic acid compound particles hydrophobized with a silane compound having an alkoxy group and an alkyl group having 3 or more and 8 or less carbon atoms has an alkyl group having 3 or more and 8 or less carbon atoms.

Since the specific titanium acid compound particles having an alkyl group having 3 or more and 8 or less carbon atoms on the surface have relatively high hydrophobicity, the occurrence of fogging can be further suppressed in a high temperature and high humidity environment.

Examples of the method for hydrophobizing the substrate include a method of dropping or spraying the hydrophobizing agent toward the substrate while stirring the substrate, and then heating the substrate coated with the hydrophobizing agent, and a solution of the hydrophobizing agent. A method of heating the substrate coated with the hydrophobizing agent after adding the substrate to the inside can be mentioned. The hydrophobizing agent may be dissolved in an organic solvent. Alternatively, a commercially available hydrophobic agent may be diluted with an organic solvent before use.

The specific calcium titanate compound particles are preferably calcium titanate particles in which lanthanum and a Group 5 element of the periodic table are doped and have an alkyl group having 3 or more and 8 or less carbon atoms on the surface, and lanthanum and niobium are doped. Calcium titanate particles having an alkyl group having 3 or more and 8 or less carbon atoms on the surface are more preferable, and calcium titanate particles having lanthanum and niobium doped on the surface and having an isobutyl group on the surface are further preferable. By using these specific titanium acid compound particles, it is possible to form a higher density image even after printing a large number of sheets while further suppressing the occurrence of fog and photoconductor pinholes.

The external additive may contain only the specific titanium acid compound particles as the external additive particles, and may further contain other external additive particles in addition to the specific titanium acid compound particles. In order to maintain good toner fluidity, the other external additive particles are preferably inorganic particles other than the specific titanium acid compound particles, and more preferably one or more selected from silica particles and titanium oxide particles.

The other external additive particles may be surface-treated. For example, when silica particles are used as other external additive particles, the surface of the silica particles may be imparted with hydrophobicity and / or positive chargeability by a surface treatment agent. Examples of the surface treatment agent include coupling agents (more specifically, silane coupling agents, titanate coupling agents, aluminate coupling agents, etc.), silazane compounds (more specifically, chain silazane compounds, etc.). Cyclic silane compounds and the like) and silicone oils (more specifically, dimethyl silicone oils and the like) can be mentioned. As the surface treatment agent, one or more selected from a silane coupling agent and a silazane compound is particularly preferable. Preferable examples of the silane coupling agent include silane compounds (more specifically, methyltrimethoxysilane, aminosilane, etc.). Preferable examples of the silazane compound include HMDS (hexamethyldisilazane). When the surface of the silica substrate (untreated silica particles) is treated with a surface treatment agent, a large number of hydroxy groups (-OH) present on the surface of the silica substrate are partially or wholly derived from the surface treatment agent. Substituted with a functional group. As a result, silica particles having a functional group derived from the surface treatment agent (specifically, a functional group having a stronger hydrophobicity and / or positive charge than the hydroxy group) on the surface can be obtained.

Amount of external additive (when other external additive particles are used, specific titanium acid) from the viewpoint of fully exerting the function of the external additive while suppressing the detachment of the external agent from the toner mother particles. The total amount of the compound particles and other external additive particles) is preferably 0.1 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the toner mother particles.

[Toner manufacturing method]
Next, a preferred method for producing the above-mentioned toner will be described. Hereinafter, the description of the components overlapping with the toner described above will be omitted.

(Preparation process of toner matrix particles)
First, toner mother particles are prepared by an agglutination method or a pulverization method.

The agglutination method includes, for example, an agglutination step and a coalescence step. In the agglomeration step, fine particles containing components constituting the toner matrix particles are agglomerated in an aqueous medium to form agglomerated particles. In the coalescence step, the components contained in the aggregated particles are coalesced in an aqueous medium to form toner matrix particles.

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

In the mixing step, the binder resin and the internal additive added as needed are mixed to obtain a mixture. 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 product is cooled to, for example, room temperature (25 ° C.) and then pulverized to obtain a pulverized product. When it is necessary to reduce the diameter of the pulverized product 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 product is made uniform, a step of classifying the obtained pulverized product (classification step) may be carried out. By the above steps, toner matrix particles which are pulverized products can be obtained.

(External process)
Then, using a mixer, the obtained toner mother particles and the external additive are mixed, and the external additive is attached to the surface of the toner mother particles. The external additive contains at least specific titanium acid compound particles. Examples of the mixer include an FM mixer (manufactured by Nippon Coke Industries Co., Ltd.). In this way, the toner containing the toner particles is produced.

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

<Evaluation method of titanium acid compound particles (evaluation device)>
First, an evaluation method (evaluation device) for titanium acid compound 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 for measuring the number average primary particle size of the titanium acid compound particles. The amount of elements in the titanic acid compound particles was measured by an inductively coupled plasma emission spectrophotometer (“SPS1200VR” manufactured by Seiko Instruments Inc.). The powder X-ray diffraction pattern of the titanium acid compound particles was measured using a powder X-ray diffractometer (“RINT® TTR III” manufactured by Rigaku Co., Ltd., characteristic X-ray: Cu-Kα ray).

The relative permittivity and the number average circularity of the titanic acid compound particles were measured by the methods shown below, respectively.

[Relative permittivity measurement method]
1 g of the titanium acid compound particles were compressed under the condition of a pressure of 200 kg / cm ² for 2 minutes, and formed into disc-shaped pellets (measurement sample) having a diameter of 25 mm and a thickness of 1 mm. Next, the above-mentioned measurement sample was set in a rotary rheometer (“ARES-G2” manufactured by TA Instruments) equipped with a permittivity measuring jig (electrode) having a diameter of 25 mm. Then, using an LCR meter (“4284A Precision LCR Meter” manufactured by KeySight Technologies Co., Ltd.), a measurement sample (titanic acid compound) was used under the conditions of a measurement temperature of 25 ° C., a load of 150 g, an applied voltage of 1.0 V, and a frequency of 1.0 MHz. The relative permittivity of the particles) was obtained.

[Measuring method of number average circularity]
Titanate compound particles were photographed with a transmission electron microscope (TEM) (“H-7100FA” manufactured by Hitachi High-Technologies Corporation), and the obtained image was analyzed by image analysis software (“WinROOF” manufactured by Mitani Shoji Co., Ltd.). Specifically, 100 particles were randomly selected from the titanium acid compound particles existing in the image, and the circularity of each particle (circumferential length of a circle equal to the projected area of the particle / peripheral length of the particle) was measured. .. The number average value was calculated from the measured circularity of 100 particles, and the obtained value was taken as the number average circularity of the titanium acid compound particles.

<Preparation of titanium acid compound particles>
Hereinafter, a method for preparing the titanium acid compound particles A to H will be described.

[Preparation of Titanate Compound Particle A]
(Reaction preparation process)
First, the reaction preparation step will be described. A suspension having a pH of 9.0 was prepared by adding a 4N sodium hydroxide aqueous solution to titanyl sulfate (manufactured by Yoneyama Yakuhin Kogyo Co., Ltd.) (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 solid content after washing with water to obtain a slurry having a Ti concentration of 2.13 mol / L. Hydrochloric acid was added to the obtained slurry (glutination treatment). The pH of the slurry after the defibration treatment was 1.4. Next, the slurry after the deflocculation treatment (1.877 mol in terms of TiO ₂ ) was put into a 3 L reaction vessel. Next, 2.1590 mol of an aqueous solution of strontium chloride (SrCl ₂ ) was charged into the reaction vessel in terms of Sr. The contents of the reaction vessel (hereinafter referred to as the contents of the vessel) after the strontium chloride aqueous solution was added had a molar ratio of Sr to Ti (Sr / Ti) of 1.15. Next, 0.216 mol of an aqueous solution of lanthanum chloride (LaCl ₃ ) was charged into the reaction vessel in terms of La. The molar ratio (La / Sr) of La and Sr of the contents of the container after the aqueous solution of lanthanum chloride was added was 0.10. Next, 0.0188 mol of niobium pentoxide (Nb ₂ O ₅ ) was charged into the reaction vessel in terms of Nb. The contents of the container after adding niobium pentoxide had a molar ratio of Nb to Ti (Nb / Ti) of 0.01. Next, ion-exchanged water was added to the contents of the container to obtain a slurry having a Ti concentration of 0.939 mol / L.

(Reaction process)
Next, the reaction process will be described. While stirring the slurry (Ti concentration: 0.939 mol / L) obtained in the above procedure, the internal temperature of the reaction vessel was raised to 90 ° C., and then 535 mL of a sodium hydroxide aqueous solution was placed in 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 vessel were stirred for 1 hour while maintaining the internal temperature of the reaction vessel at 95 ° C. Next, the container contents were cooled to a temperature of 50 ° C., and then hydrochloric acid was added to the cooled container contents to adjust the pH of the container contents to 5.0. Next, the contents of the reaction vessel were stirred for 1 hour while the internal temperature of the reaction vessel was maintained 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 air at a temperature of 120 ° C. for 10 hours to obtain a powder of titanium acid compound particles a containing lantern and niobium.

(Hydrophobic treatment process)
Next, the hydrophobizing treatment step will be described. 100 parts by mass of the titanium acid compound particles a were put into a three-necked flask equipped with a thermometer and a stirrer, and the air in the flask was replaced with nitrogen to create a nitrogen atmosphere in the flask. Subsequently, while stirring the contents of the flask, 15 parts by mass of isobutyltrimethoxysilane and an amount of distilled water suitable for advancing the reaction (specifically, hydrolysis reaction) on the surface of the titanium acid compound particles a. And sprayed into the flask. Then, while stirring the contents of the flask, the titanium acid compound particles a and isobutyltrimethoxysilane were reacted for 2 hours under the condition of a temperature of 110 ° C. As a result, the powder of the titanic acid compound particles A having the titanic acid compound particles a (base) and the isobutyl group (specifically, the isobutyl group derived from isobutyltrimethoxysilane) imparted to the surface of the titanic acid compound particles a. Got

(Number average primary particle size, number average circularity, and powder X-ray diffraction pattern)
The number average primary particle diameter of the obtained titanium acid compound particles A was 30 nm. The number average circularity of the obtained titanium acid compound particles A was 0.84. The peak position of the powder X-ray diffraction pattern of the obtained titanium acid compound particles A coincided with the peak position of the powder X-ray diffraction pattern of the perovskite-type crystal structure of strontium titanate (base material). That is, the titanate compound particles A 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 titanic acid compound particles A are all the titanic acid compound particles A separated from the toner particles after the toner was prepared by the method described later. The same result was obtained when the powder of No. 1 was measured as a measurement target. The same applies to the titanium acid compound particles B to H described later.

[Preparation of Titanate Compound Particle B]
In the reaction preparation step, the amount (input amount) of the aqueous solution of lanthanum chloride was changed to 0.4320 mol in terms of La, and vanadium pentoxide (composition) instead of niobium pentoxide (0.0188 mol in terms of Nb). The powder of the titanic acid compound particles B was obtained by the same method as the preparation of the titanic acid compound particles A except that the formula: V ₂ O ₅ and the input amount: 0.0564 mol in terms of V were used. The titanium acid compound particles B were titanium acid compound particles having a titanium acid compound particles b (base) containing lanthanum and vanadium, and an isobutyl group imparted to the surface of the titanium acid compound particles b.

[Preparation of Titanate Compound Particle C]
In the reaction preparation step, an aqueous solution of barium chloride (BaCl ₂ ) (2.1590 mol in terms of Ba) was used instead of an aqueous solution of barium chloride (2.1590 mol in terms of Sr), and the amount of the aqueous solution of lanthanum chloride used. (Input amount) was changed to 0.0650 mol in La conversion, and tantalum pentoxide (composition formula: Ta ₂ O ₅ , input amount: Ta conversion) instead of niobium pentoxide (0.0188 mol in Nb conversion) The powder of the titanic acid compound particles C was obtained by the same method as the preparation of the titanic acid compound particles A except that 0.0019 mol) was used. The titanium acid compound particles C were titanium acid compound particles having a titanium acid compound particle c (base) containing lanthanum and tantalum and an isobutyl group attached to the surface of the titanium acid compound particle c.

[Preparation of Titanate Compound Particle D]
In the reaction preparation step, the aqueous solution of lanthanum chloride was not used (added), and instead of the aqueous solution of strontium chloride (2.1590 mol in Sr conversion), the aqueous solution of barium chloride (BaCl ₂ ) (2.1590 in Ba conversion) was used. Preparation of titanic acid compound particles A and the use of tantalum pentoxide (0.0653 mol in Ta equivalent) instead of niobide pentoxide (0.0188 mol in Nb conversion). The powder of the titanic compound particles D was obtained by the same method. The titanium acid compound particles D were titanium acid compound particles having titanate-containing titanium acid compound particles d (base) and isobutyl groups imparted to the surface of the titanium acid compound particles d.

[Preparation of Titanate Compound Particle E]
In the reaction preparation step, niobide pentoxide was not used (added), and instead of an aqueous solution of strontium chloride (2.1590 mol in Sr conversion), an aqueous solution of barium chloride (BaCl ₂ ) (2.1590 mol in Ba conversion) was used. ), And the amount (input amount) of the aqueous solution of lanthanum chloride used was changed to 0.0650 mol in terms of La, except that the titanic compound particles E were prepared in the same manner as in the preparation of the titanic compound particles A. Powder was obtained. The titanium acid compound particles E were titanium acid compound particles having lanthanum-containing titanium acid compound particles e (base) and isobutyl groups imparted to the surface of the titanium acid compound particles e.

[Preparation of Titanate Compound Particle F]
In the reaction preparation step, the same method as the preparation of the titanic acid compound particles A was used except that vanadium pentoxide (0.0657 mol in V conversion) was used instead of niobium pentoxide (0.0188 mol in Nb conversion). , Titanic acid compound particle F powder was obtained. The titanium acid compound particles F were titanium acid compound particles having a titanium acid compound particle f (base) containing lanthanum and vanadium, and an isobutyl group imparted to the surface of the titanium acid compound particle f.

[Preparation of Titanate Compound Particle G]
In the reaction preparation step, niobide pentoxide was not used (added), the amount of strontium chloride aqueous solution used (added amount) was changed to 1.8770 mol in terms of Sr, and the amount of lanthanum chloride aqueous solution used. The powder of the strontium compound particles G was obtained by the same method as the preparation of the strontium compound particles A except that the (input amount) was changed to 0.3380 mol in terms of La. The titanium acid compound particles G were titanium acid compound particles having lanthanum-containing titanium acid compound particles g (base) and isobutyl groups imparted to the surface of the titanium acid compound particles g.

[Preparation of Titanate Compound Particle H]
Titanic acid compound particles A except that an aqueous solution of calcium chloride (CaCl ₂ ) (2.1590 mol in terms of Ca) was used instead of an aqueous solution of strontium chloride (2.1590 mol in terms of Sr) in the reaction preparation step. The powder of the titanic acid compound particles H was obtained by the same method as the preparation of the above. The titanium acid compound particles H were titanium acid compound particles having a titanium acid compound particle h (base) containing lanthanum and niobium and an isobutyl group imparted to the surface of the titanium acid compound particle h.

The peak position of the powder X-ray diffraction pattern of the titanate compound particles B, F and G coincided with the peak position of the powder X-ray diffraction pattern of the perovskite type crystal structure of strontium titanate (base material). That is, the titanate compound particles B were strontium titanate particles doped with lanthanum and vanadium. The titanate compound particles F were strontium titanate particles doped with lanthanum and vanadium. The titanate compound particles G were lanthanum-doped strontium titanate particles.

The peak position of the powder X-ray diffraction pattern of the titanate compound particles C to E coincided with the peak position of the powder X-ray diffraction pattern of the perovskite-type crystal structure of barium titanate (base material). That is, the titanate compound particles C were barium titanate particles doped with lanthanum and tantalum. The titanate compound particles D were tantalum-doped barium titanate particles. The titanate compound particles E were lanthanum-doped barium titanate particles.

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

Table 1 shows the amounts of Group 5 elements, the amount of lanthanum, and the relative permittivity of each of the titanium acid compound particles A to H. In Table 1, the amounts of Group 5 elements and the amount of lanthanum in the periodic table are both amounts (unit: mass%) with respect to the total mass of the titanic acid compound particles. Further, in Table 1, "-" of the addition amount indicates that the corresponding component is not added. The amount "-" indicates that it was below the detection limit of the inductively coupled plasma emission spectrophotometer used for the measurement (0.01 mass ppm with respect to the total mass of the titanate compound particles). The amount of Group 5 element, the amount of lantern, and the relative permittivity of each titanic acid compound particle in the periodic table of each titanic acid compound particle are all separated from the toner particle after the toner was prepared by the method described later. The same result was obtained when the powder of Toner was measured as a measurement target.

<Making toner>
Hereinafter, a method for producing the toners TA-1 to TA-4 and TB-1 to TB-5 will be described.

[Preparation of toner TA-1]
(Preparation process of toner matrix particles)
100 parts by mass of polyester resin ("HP-313" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and 2 parts by mass of niglosin dye ("BONTRON (registered trademark) N-71" manufactured by Orient Chemical Industry Co., Ltd.) as a charge control agent. , 2 parts by mass of a resin containing a quaternary ammonium cation group as a charge control agent (“Acribase (registered trademark) FCA-201-PS” manufactured by Fujikura Kasei Co., Ltd.) and carnauba wax (Toa Kasei) as a release agent. 4 parts by mass of magnetic powder ("TN-15" manufactured by Mitsui Metal Mining Co., Ltd., magnetite with an average number of primary particle diameter of 0.2 μm) 77.3 parts by mass of FM mixer (Nippon Coke Industries Co., Ltd.) After being put into the company's "FM-10B"), the mixture was mixed at a rotation speed of 2000 rpm for 4 minutes.

Subsequently, the obtained mixture was melt-kneaded using a twin-screw extruder (“TEM-26SS” manufactured by Toshiba Machine Co., Ltd.) at a temperature of 150 ° C. Then, the obtained kneaded product was cooled. Subsequently, the cooled kneaded product is coarsely crushed using a crusher (formerly Toa Kikai Seisakusho "Rotoplex (registered trademark) 16/8 type") so that the median volume diameter (D ₅₀ ) is about 2 mm. Crushed. The obtained coarsely pulverized product was finely pulverized using a pulverizer (“Turbo Mill RS type” manufactured by Freund Turbo Co., Ltd.). Subsequently, the obtained finely pulverized product was classified using a classification machine (“EJ-LABO model EJ-L-3” manufactured by Nittetsu Mining Co., Ltd.). As a result, toner mother particles having a median volume diameter (D ₅₀ ) of 8.0 μm were obtained.

(External process)
100 parts by mass of toner mother particles (toner mother particles obtained in the above preparation step) and 1.5 parts by mass of positively charged silica particles (CAB-O-SIL (registered trademark) TG-308F manufactured by Cabot). ”), 0.5 parts by mass of titanium acid compound particles A, and 1.0 parts by mass of conductive titanium oxide particles (“EC-100” manufactured by Titanium Industry Co., Ltd.) are used in an FM mixer (Nippon Coke Industries Co., Ltd.). It was put into the company's "FM-10B"). Next, using the FM mixer, the toner mother particles and the external additive (titanate compound particles A, hydrophobic silica particles and conductive titanium oxide particles) were mixed for 5 minutes under the conditions of a rotation speed of 3500 rpm and a jacket temperature of 20 ° C. Mixed. As a result, the entire amount of the external additive was adhered to the surface of the toner matrix particles. As a result, a positively charged toner TA-1 was obtained.

[Preparation of toners TA-2 to TA-4 and TB-1 to TB-5]
Positively charged toners TA-2 to TA-4 and TB-2 to TB are produced by the same method as for producing toner TA-1, except that the types of titanium acid compound particles are as shown in Table 2 described later. -5 were prepared respectively. In addition, in Table 2, "-" in the column of the titanium acid compound particle means that the titanium acid compound particle was not used.

[Manufacturing of sleeves]
The sleeve provided in the black developing apparatus of the monochrome multifunction device (“TASKalfa (registered trademark) 3510i” manufactured by Kyocera Document Solutions Co., Ltd.) was used as the sleeve A. A plurality of sleeves A were prepared. The sleeve A was an aluminum sleeve having an outer diameter of 20 mm. That is, the sleeve A had only a sleeve substrate containing aluminum. The surface of the sleeve A was blasted, and its 10-point average roughness Rz was 7.5 μm. A surface roughness shape measuring machine (“SURFCOM (registered trademark) 1500DX” manufactured by Tokyo Seimitsu Co., Ltd.) was used for measuring the average surface roughness.

A part of the sleeve A was plated. Specifically, NaOH was added to an aqueous solution containing chromium nitrate (concentration: 4 g / L), cobalt nitrate (concentration: 3 g / L), and acetic acid (20 g / L) to adjust the pH to 4. As a result, a plating solution was obtained. By immersing the sleeve A in the plating solution, the surface of the sleeve A was plated. The immersion conditions were a temperature of 30 ° C. and a time of 60 seconds. As a result, a sleeve B including a sleeve base containing aluminum and a sleeve coat layer covering the surface of the sleeve base was obtained. The sleeve coat layer had a thickness of 0.2 μm and contained trivalent chromium and cobalt.

<Preparation of image forming device>
The sleeve A was removed from the black developing device of the monochrome multifunction device (“TASKalfa (registered trademark) 306i” manufactured by Kyocera Document Solutions Co., Ltd.), and the sleeve B was mounted instead. Further, the toner TA-1 was put into the black developing apparatus and the black toner container of the above-mentioned multifunction device. This was used as the image forming apparatus of Example 1.

The image forming apparatus of Examples 2 to 4 and Comparative Examples 1 to 7 was manufactured by the same method as the manufacturing of the image forming apparatus of Example 1 except that the following points were changed. In the production of the image forming apparatus of Examples 2 to 4 and Comparative Examples 1 to 7, toners TA-2 to TA-4 and TB-1 to TB-5 were used instead of the toner TA-1. Further, in the manufacture of the image forming apparatus of Comparative Examples 1 and 2, the sleeve A was mounted on the above-mentioned monochrome multifunction device instead of the sleeve B. The configuration of each image forming apparatus is shown in Table 2 below.

[An endurance test]
An image having a printing rate of 5% was printed on 200,000 sheets of printing paper (A4 size) using the above-mentioned evaluation machine in a normal temperature and humidity environment with a temperature of 23.0 ° C. and a humidity of 50% RH (durability test). After the durability test, an evaluation image including a solid image was printed on printing paper, and this image was designated as an evaluation image A. The image density (ID) of the solid image of the evaluation image A was measured using a reflection densitometer (“SpectroEye®” manufactured by X-Rite). Further, the image density (ID _X1 ) of the non-printed portion of the evaluation image A and the image density (ID _X2 ) of the base paper (unprinted paper) are measured using the above-mentioned reflection densitometer, and "ID _X1 " is measured. -ID _X2 "was calculated and used as the fog density (FD) of the non-printed portion. The image density and fog of the evaluation image A were evaluated based on the following evaluation criteria.

(Evaluation criteria for image density)
Good (A): ID is 1.00 or more Bad (B): ID is less than 1.00

(Evaluation criteria for fog)
Good (A): FD is less than 0.010 Bad (B): ID is 0.010 or more

[Printing test in LL environment]
An image with a printing rate of 2% was printed on 10,000 sheets of printing paper (A4 size) using the above-mentioned evaluation machine in a low-temperature and low-humidity environment with a temperature of 10.0 ° C. and a humidity of 10% RH (LL low printing rate test). ). After the LL low print rate test, an evaluation image including a solid image was printed on printing paper, and this image was designated as an evaluation image B. The evaluation image B was visually observed to confirm the presence or absence of dot-shaped image defects due to pinholes in the photoconductor. Then, it was determined that the case where the dot-shaped image defect could not be confirmed in the evaluation image B was good (A), and the case where the dot-shaped image defect could be confirmed was defective (B). In addition, the image density (ID) of the solid image of the evaluation image B was measured using the above-mentioned reflection densitometer. The image density of the evaluation image B was evaluated based on the following evaluation criteria.

(Evaluation criteria for image density)
Good (A): ID is 1.00 or more Bad (B): ID is less than 1.00

After the low printing rate test in the LL environment, printing was performed on 500 sheets of printing paper at a printing rate of 20% using the above-mentioned evaluation machine. The fog density was measured for each of the 500 printing sheets. Specifically, the image density (ID _Y1 ) of the non-printing portion of each printing paper and the image density (ID _Y2 ) of the base paper (unprinted paper) are measured using the above-mentioned reflection densitometer, and ""ID _Y1- ID _Y2 " was calculated and used as the fog concentration (FD). Of the respective fog concentrations (FD) of 500 printing sheets, the maximum value was defined as the post-replenishment fog density (FD _MAX ). The fog after the low print rate test was evaluated based on the following evaluation criteria. The evaluation results of each test are shown in Table 2 below.

(Evaluation criteria for fog)
Good (A): FD _MAD after replenishment is 0.010 or less Poor (B): FD _MAD after replenishment is over 0.010

The image forming apparatus of Examples 1 to 4 provided a developing apparatus configured to develop an electrostatic latent image with toner. The developing apparatus includes an accommodating portion for accommodating toner and a toner carrier for supporting the toner supplied from the accommodating portion. The toner carrier had a shaft and a sleeve that was rotatable around the shaft. The sleeve had an aluminum-containing sleeve substrate and a sleeve coat layer covering the surface of the sleeve substrate. The sleeve coat layer contained trivalent chromium and cobalt. The toner contained toner particles. The toner particles included a toner mother particle containing a binder resin and an external additive adhering to the surface of the toner mother particle. The external additive contained titanium acid compound particles doped with a 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 titanium acid compound particles. The amount of Group 5 elements in 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 titanium acid compound particles.

As shown in Table 2, the image forming apparatus of Examples 1 to 4 had good image density and fog after the durability test, and image density, fog and photoconductor pinhole after the LL low printing rate test. .. As described above, the image forming apparatus of Examples 1 to 4 was able to form a high-density image even after printing a large number of sheets (for example, 200,000 sheets) while suppressing the occurrence of fog and photoconductor pinholes.

On the other hand, the image forming apparatus of Comparative Examples 1 to 7 did not have at least one of the above configurations. Specifically, in the image forming apparatus of Comparative Examples 1 and 2, the sleeve of the developing apparatus did not include the sleeve coat layer. As a result, in the image forming apparatus of Comparative Examples 1 and 2, it is determined by the durability test that the sleeve is worn and the image density is lowered. Further, in the image forming apparatus of Comparative Example 2, the titanium acid compound particles contained in the toner did not contain the Group 5 element. As a result, in the image forming apparatus of Comparative Example 2, it is determined that the titanium acid compound particles were excessively charged and photoconductor pinholes were generated.

In the image forming apparatus of Comparative Example 3, the toner did not contain the titanium acid compound particles. As a result, it is determined that the image forming apparatus of Comparative Example 3 could not stably maintain the charge amount of the toner, and the image density and the fog were poor in the LL low printing rate test.

In the image forming apparatus of Comparative Example 4, the titanium acid compound particles contained in the toner did not contain lanthanum. The titanium acid compound particles used in the image forming apparatus of Comparative Example 4 had a relatively low average circularity of 0.78. As a result, in the image forming apparatus of Comparative Example 4, it is determined by the durability test that the sleeve is worn and the image density is lowered.

In the image forming apparatus of Comparative Examples 5 and 7, the titanium acid compound particles contained in the toner did not contain the Group 5 element. As a result, in the image forming apparatus of Comparative Examples 5 and 7, it is determined that the titanium acid compound particles were excessively charged and photoconductor pinholes were generated.

In the image forming apparatus of Comparative Example 6, the titanium acid compound particles contained in the toner contained an excess of Group 5 elements. As a result, it is determined that the image forming apparatus of Comparative Example 6 could not stably maintain the charge amount of the toner, and the image density and the fog were poor in the durability test.

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

1 Developing device 10 Developing roller 11 Shaft 12 Magnet roll 13 Sleeve 13a, 13b Flange 130 Sleeve base 132 Sleeve coat layer 20 Photoreceptor drum 21 Charging device 22 Exposure device 23 Cleaning member 30 Toner charging member 40 Toner supply roller 60 Toner particles 61 Toner mother particle 62 Specific titanic acid compound particle (titanic acid compound particle)
R housing

Claims (11)

An image forming apparatus including a developing apparatus configured to develop an electrostatic latent image with toner.
The developing apparatus includes an accommodating portion for accommodating the toner and a toner carrier for supporting the toner supplied from the accommodating portion.
The toner carrier has a shaft and a sleeve that is rotatable around the shaft.
The sleeve has an aluminum-containing sleeve substrate and a sleeve coat layer that covers the surface of the sleeve substrate.
The sleeve coat layer contains trivalent chromium and cobalt and contains
The toner contains toner particles and contains toner particles.
The toner particles include a toner mother particle containing a binder resin and an external additive adhering to the surface of the toner mother particle.
The external additive contains titanium acid compound particles doped with a lanthanum and a Group 5 element of the periodic table as external additive particles.
The amount of the lanthanum is 1.50% by mass or more with respect to the total mass of the titanium acid compound particles.
An image forming apparatus in which the amount of Group 5 elements in 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 titanium acid compound particles. The image forming apparatus according to claim 1, wherein the 10-point average roughness Rz of the surface of the sleeve substrate is 6 μm or more and 9 μm or less. The image forming apparatus according to claim 1 or 2, wherein the Group 5 element of the periodic table is one or more elements selected from the group consisting of vanadium, niobium and tantalum. The image forming apparatus according to any one of claims 1 to 3, wherein the number average circularity of the titanic compound particles is 0.79 or more and 1.00 or less. The titanium acid compound particles are
Strontium titanate particles doped with the lanthanum and the Group 5 element of the periodic table,
Any of claims 1 to 4, wherein the barium titanate particles are doped with the lanthanum and the Group 5 element of the periodic table, or calcium titanate particles are doped with the lanthanum and the Group 5 element of the periodic table. The image forming apparatus according to item 1. The image forming apparatus according to any one of claims 1 to 5, wherein the amount of the titanium acid compound particles is 0.1 part by mass or more and 1.2 parts by mass or less with respect to 100 parts by mass of the toner mother particles. .. The image forming apparatus according to any one of claims 1 to 6, wherein the amount of the lanthanum is 15.0% by mass or less with respect to the total mass of the titanium acid compound particles. The image forming apparatus according to any one of claims 1 to 7, wherein the number average primary particle diameter of the titanium acid compound particles is 20 nm or more and 80 nm or less. The image forming apparatus according to any one of claims 1 to 8, wherein the relative permittivity of the titanium acid compound particles is 100 or more and 1,200 or less. The image forming apparatus according to any one of claims 1 to 9, wherein the surface of the titanium acid compound particles is hydrophobized. The image forming apparatus according to claim 10, wherein the surface of the titanium acid compound particles has an alkyl group having 3 or more and 8 or less carbon atoms.

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