Toner and image forming apparatus
阅读说明：本技术 调色剂 (Toner and image forming apparatus ) 是由 溝部猛雄 荒山健 菅原正伦 小林亮太 大野一树 矢部成男 于 2020-04-08 设计创作，主要内容包括：本发明提供一种调色剂。调色剂含有调色剂颗粒。调色剂颗粒具备调色剂母粒和外部添加剂,调色剂母粒含有粘结树脂,外部添加剂附着在调色剂母粒的表面。外部添加剂中,掺杂了镧和周期表第5族元素的钛酸化合物颗粒作为外部添加剂颗粒。相对于钛酸化合物颗粒的总质量,镧的量是1.50质量％以上。相对于钛酸化合物颗粒的总质量,周期表第5族元素的量是0.01质量％以上0.60质量％以下。(The invention provides a toner. The toner contains toner particles. The toner particles include toner base particles and an external additive, the toner base particles contain a binder resin, and the external additive is attached to the surface of the toner base particles. In the external additive, particles of a titanic acid compound doped with lanthanum and an element of group 5 of the periodic table are used as the particles of the external additive. The amount of lanthanum is 1.50 mass% or more with respect to the total mass of the titanic acid compound particles. The amount of the group 5 element of the periodic table is 0.01 to 0.60 mass% based on the total mass of the titanic acid compound particles.)
1. A toner containing toner particles, characterized in that,
the toner particles are provided with toner base particles containing a binder resin and an external additive adhering to the surface of the toner base particles,
in the external additive, particles of a titanic acid compound doped with lanthanum and an element of group 5 of the periodic table are used as particles of the external additive,
the amount of lanthanum is 1.50 mass% or more with respect to the total mass of the titanic acid compound particles,
the amount of the group 5 element of the periodic table is 0.01 mass% or more and 0.60 mass% or less with respect to the total mass of the titanic acid compound particles.
2. The toner according to claim 1,
the group 5 element of the periodic table is one or more elements selected from the group consisting of vanadium, niobium and tantalum.
3. The toner according to claim 1 or 2,
The number average circularity of the titanic acid compound particles is 0.79 to 1.00.
4. The toner according to claim 1 or 2,
the particles of the titanic acid compound are strontium titanate particles doped with the lanthanum and the group 5 element of the periodic table, barium titanate particles doped with the lanthanum and the group 5 element of the periodic table, or calcium titanate particles doped with the lanthanum and the group 5 element of the periodic table.
5. The toner according to claim 1 or 2,
the amount of the titanic acid compound particles is 0.1 to 1.2 parts by mass with respect to 100 parts by mass of the toner base particles.
6. The toner according to claim 1 or 2,
the amount of lanthanum is 15.00 mass% or less with respect to the total mass of the titanic acid compound particles.
7. The toner according to claim 1 or 2,
the number average primary particle diameter of the titanic acid compound particles is 20nm to 80 nm.
8. The toner according to claim 1 or 2,
the relative dielectric constant of the titanic acid compound particles is 100 to 1200.
9. The toner according to claim 1 or 2,
The surfaces of the titanic acid compound particles are subjected to a hydrophobic treatment.
10. The toner according to claim 9,
the surface of the titanic acid compound particle has a C3-C8 alkyl group.
Technical Field
The present invention relates to a toner.
Background
An image forming apparatus that forms an image using toner is required to be capable of stably forming an image having an image density of a certain level or more even after a large amount of printing. Therefore, a toner containing particles of a titanic acid compound (more specifically, strontium titanate particles, etc.) as external additive particles is being studied. The titanic acid compound has a high relative dielectric constant, and therefore can stably maintain the charge amount of the toner even after a large amount of printing. Thus, when the titanic acid compound particles are used as the external additive particles in the toner, an image having an image density of a certain level or more can be stably formed even after a large amount of printing.
However, the titanic acid compound particles generally have a polyhedral shape (specifically, a polygonal shape with corners), and thus, in mass printing, for example, may cause the surface of the photosensitive drum to be excessively ground by the titanic acid compound particles. After the surface of the photosensitive drum is excessively polished, image failure (streaks) may occur.
In order to suppress excessive polishing of the surface of the photosensitive drum, for example, lanthanum-doped titanic acid compound particles (hereinafter, sometimes referred to as lanthanum-doped titanic acid compound particles) are used as the external additive particles. The lanthanum-doped titanic acid compound particles are nearly spherical in shape, and therefore, when the lanthanum-doped titanic acid compound particles are used as external additive particles in the toner, excessive grinding of the photosensitive drum surface can be suppressed.
Disclosure of Invention
However, when only the above-described technique is applied, it is difficult to form a high-quality image after a large number of (for example, 2 ten thousand) prints with the toner while suppressing the generation of fog.
The present invention has been made in view of the above-described problems, and an object thereof is to provide a toner capable of forming a high-quality image even after a large number of (e.g., 2 ten thousand) prints while suppressing the generation of fog.
The toner according to the present invention contains toner particles. The toner particles are provided with toner base particles containing a binder resin and an external additive attached to the surface of the toner base particles. In the external additive, particles of a titanic acid compound doped with lanthanum and an element of group 5 of the periodic table are used as particles of the external additive. The amount of lanthanum is 1.50 mass% or more with respect to the total mass of the titanic acid compound particles. The amount of the group 5 element of the periodic table is 0.01 mass% or more and 0.60 mass% or less with respect to the total mass of the titanic acid compound particles.
According to the present invention, it is possible to provide a toner capable of forming a high-quality image even after a large number of (for example, 2 ten thousand) prints while suppressing the generation of fog.
Drawings
Fig. 1 is a cross-sectional structural view of an example of toner particles contained in a toner according to an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described below. First, technical terms used in the present specification will be described. A toner is an aggregate (e.g., powder) of toner particles. The external additive is an aggregate (e.g., a powder) of external additive particles. As to the evaluation results (values indicating the shape, physical properties, and the like) of the powder (more specifically, the powder of the toner particles, the powder of the external additive particles, and the like), if not specified otherwise, a considerable number of particles are selected from the powder, and each of these particles is measured, and the arithmetic mean of the measured values is the evaluation result.
The volume median diameter (D) of the powder is not particularly limited50) The measured value of (A) is a volume median particle diameter measured by using a laser diffraction/scattering particle size distribution measuring apparatus ("LA-950" manufactured by horiba, Ltd.). The number-average primary particle diameter of the powder is not particularly limited, and is an arithmetic average of diameters equivalent to circles (Heywood diameter: diameter of a circle having an area equal to a projected area of the primary particle) of 100 primary particles measured by a scanning electron microscope (JSM-7401F, manufactured by Japan Electron Co., Ltd.) and image analysis software (Winoroof, manufactured by Sanko Co., Ltd.). In addition, the number-uniform primary particle diameter of the particles refers to the number-uniform primary particle diameter of the particles in the powder (number-uniform primary particle diameter of the powder), unless otherwise specified.
The strength of the chargeability is not particularly limited, and refers to the ease of triboelectrification. For example, a measurement object (e.g., toner) is triboelectrically charged by mixing and stirring a standard carrier (standard carrier for negative electrode-carrying toner: N-01; standard carrier for positive electrode-carrying toner: P-01) provided by the Japan image society. Before and after the triboelectrification, the charge amount of the measurement object is measured using, for example, a suction type small-sized charge amount measuring device ("MODEL 212 HS" manufactured by TREK corporation). The larger the change in the charge amount of the measurement object before and after triboelectrification, the stronger the charging property.
The measured value of the softening point (Tm) is not particularly limited, and is a value measured by using a flow tester of the Koshika type ("CFT-500D" manufactured by Shimadzu corporation). In the S-curve (horizontal axis: temperature; vertical axis: stroke) measured by using the Ko-Ko flow tester, the temperature at which the stroke is "(baseline stroke value + maximum stroke value)/2" corresponds to Tm (softening point).
The "main component" of a material is a component that is contained at the maximum in the material on a mass basis, unless otherwise specified.
The strength of hydrophobicity can be expressed by, for example, the contact angle of a water droplet (the ease of water permeation). A larger contact angle of a water droplet indicates a stronger hydrophobicity. The hydrophobic treatment refers to a treatment for enhancing hydrophobicity.
"C3-C8 alkyl" is straight-chain or branched-chain and unsubstituted. Examples of the C3-C8 alkyl group include: n-propyl, n-butyl, isobutyl, n-pentyl, n-hexyl, n-heptyl and n-octyl.
"periodic table" means: the long form of the periodic Table of the elements as specified by IUPAC (International Union of pure and applied chemistry). "group 5 elements of the periodic Table" means vanadium (V), niobium (Nb), tantalum (Ta) and(Dubnium) (Db). The "titanic acid compound" means a compound (crystal) containing at least titanium, oxygen and a metal element other than titanium. The "titanic acid compound particles" mean particles containing a titanic acid compound as a main component. In the particles of the titanic acid compound, the titanic acid compound is contained in the particles of the titanic acid compoundThe content is preferably 99 mass% or more and 100 mass% or less.
Hereinafter, the compound and its derivatives may be collectively referred to by adding "class" to the compound name. When a compound name is followed by "class" to indicate a polymer name, the repeating unit indicating the polymer is derived from the compound or a derivative thereof.
In the following description, "doping with an element (more specifically, lanthanum, a group 5 element of the periodic table, and the like)" means: among the constituent elements of the titanic acid compound crystal as the base material, a part is substituted with an element (more specifically, lanthanum, group 5 element of the periodic table, etc.) other than the base material element.
< toner >
The toner according to the present embodiment can be applied to development of an electrostatic latent image as, for example, a positively chargeable toner. The toner according to the present embodiment is an aggregate (e.g., powder) of toner particles (each of which is a particle having a structure described later). The toner can be used as a one-component developer. Further, a two-component developer may also be produced by mixing the toner with the carrier using a mixing device (e.g., a ball mill).
The toner particles contained in the toner according to the present embodiment include toner base particles and an external additive, the toner base particles contain a binder resin, and the external additive adheres to the surface of the toner base particles. In the external additive, particles of a titanic acid compound doped with lanthanum and an element of group 5 of the periodic table (hereinafter, sometimes referred to as specific titanic acid compound particles) are used as the external additive particles. The amount of lanthanum is 1.50 mass% or more with respect to the total mass of the specific titanic acid compound particles. The amount of the group 5 element in the periodic table is 0.01 to 0.60 mass% based on the total mass of the specific titanic acid compound particles.
Hereinafter, the amount of lanthanum in the total mass of the specific titanic acid compound particles may be abbreviated as "the amount of lanthanum". The amount of the group 5 element of the periodic table in the total mass of the specific titanic acid compound particles may be abbreviated as "the amount of the group 5 element of the periodic table". In addition, the amount of lanthanum in the total mass of the specific titanic acid compound particles and the content ratio of lanthanum in the total mass of the specific titanic acid compound particles are the same meaning. The amount of the group 5 element of the periodic table in the total mass of the specific titanic acid compound particles and the content ratio of the group 5 element of the periodic table in the total mass of the specific titanic acid compound particles are the same. The amount of lanthanum and the amount of group 5 elements of the periodic table were both measured by inductively coupled plasma emission spectroscopy.
The toner according to the present embodiment has the above-described configuration, and thus can form a high-quality image even after a large number of (e.g., 2 ten thousand) prints while suppressing the generation of fog. The reason is presumed as follows.
In general, when external additive particles having a shape close to a sphere are used, the external additive particles tend to be easily excessively charged. In a large number (for example, 2 ten thousand sheets) of printing, for example, the excessively charged external additive particles may discharge to the surface of the photosensitive drum to cause dielectric breakdown of the surface of the photosensitive drum. Dielectric breakdown is particularly prone to occur in low temperature and low humidity environments. When the surface of the photosensitive drum is subjected to dielectric breakdown, the surface of the photosensitive drum may be damaged. Damage to the surface of the photosensitive drum due to dielectric breakdown causes image failure (generation of black dots). Therefore, in the case of using lanthanum-doped titanic acid compound particles as the external additive particles in general, when an image is formed after a large amount of printing, image failure (black dots) is liable to occur.
In contrast, in the toner according to the present embodiment, specific titanic acid compound particles doped with a group 5 element of the periodic table are used as the external additive particles. The periodic table group 5 elements have a suitably low resistance. The amount of the group 5 element in the periodic table is 0.01% by mass or more. Thus, in the toner according to the present embodiment, it is possible to suppress excessive charging of the specific titanic acid compound particles. Further, the specific titanic acid compound particles are doped with lanthanum. The amount of lanthanum is 1.50% by mass or more. Thus, in the toner according to the present embodiment, for example, excessive polishing of the surface of the photosensitive drum can be suppressed. Further, since the specific titanic acid compound particles contain a titanic acid compound having a high relative dielectric constant, the charge amount of the toner can be stably maintained even after a large amount of printing.
Thus, according to the toner of the present embodiment, even after a large number (for example, 2 ten thousand sheets) of printing, it is possible to stably form an image having an image density of a certain level or more while suppressing the occurrence of image failure (more specifically, the occurrence of black dots, the occurrence of streaks, and the like). Therefore, according to the toner of the present embodiment, a high-quality image can be formed even after a large number (for example, 2 ten thousand sheets) of printing.
In general, when external additive particles having low electric resistance are used, fogging tends to occur. Fog is particularly prone to occur in high temperature and high humidity environments.
In contrast, in the toner according to the present embodiment, the amount of the group 5 element of the periodic table is 0.60 mass% or less. In this way, in the toner according to the present embodiment, the upper limit of the amount of the group 5 element of the periodic table is set to such an extent that the resistance of the specific titanic acid compound particle does not become too low. Therefore, the toner according to the present embodiment can suppress the generation of fog.
In the present embodiment, the amount of the group 5 element in the periodic table is preferably 0.10 mass% or more in order to form an image with higher image quality after mass printing.
In the present embodiment, the amount of lanthanum is preferably 1.80 mass% or more in order to form an image with higher image quality after printing in large quantities. In the present embodiment, the amount of lanthanum is preferably 15.00 mass% or less, and more preferably 12.50 mass% or less, in order to suppress the occurrence of black spots more favorably when an image is formed after a large amount of printing.
In the present embodiment, in order to form an image with higher image quality after printing in a large amount, the group 5 element of the periodic table contained in the specific titanic acid compound particle is preferably one or more elements selected from the group consisting of vanadium, niobium, and tantalum, and more preferably niobium.
In the present embodiment, in order to form an image with higher image quality after mass printing, the amount of the specific titanic acid compound particles is preferably 0.1 part by mass or more, and more preferably 0.5 part by mass or more, per 100 parts by mass of the toner base particles. In the present embodiment, the amount of the specific titanic acid compound particles is preferably 1.2 parts by mass or less, more preferably 1.0 part by mass or less, per 100 parts by mass of the toner base particles, in order to more preferably suppress the generation of the fog.
In the present embodiment, in order to form an image with higher image quality after printing in a large amount, the specific dielectric constant of the specific titanic acid compound particles is preferably 100 to 1200, and more preferably 150 to 1180. The method of measuring the relative dielectric constant is the same as or similar to the embodiment described later.
The toner particles contained in the toner according to the present embodiment may be toner particles having no shell layer, or may be toner particles having a shell layer (hereinafter, may be referred to as capsule toner particles). In the capsule toner particles, the toner base particles include a toner core containing a binder resin and a shell layer covering the surface of the toner core. The shell layer contains a resin. For example, by covering a toner core melted at a low temperature with a shell layer having excellent heat resistance, both heat-resistant storage property and low-temperature fixing property of the toner can be satisfied. The resin constituting the shell layer may contain an additive dispersed therein. The shell layer may cover the entire surface of the toner core, or may cover a partial surface of the toner core.
In the present embodiment, 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) as necessary in addition to the binder resin.
Hereinafter, the toner according to the present embodiment will be described in detail with reference to the drawings as appropriate. In fig. 1, the components are schematically illustrated for the sake of easy understanding, and the size, number, shape, and the like of the components may be different from those of the actual components.
[ Structure of toner particles ]
Hereinafter, the structure of toner particles contained in the toner according to the present embodiment will be described with reference to fig. 1. Fig. 1 is a cross-sectional structural view of an example of toner particles contained in the toner according to the present embodiment.
The
In order to obtain a toner suitable for forming an image, the volume median diameter (D) of the toner base particles 1150) Preferably 4 to 9 μm.
In order to more effectively suppress the occurrence of streaks when forming an image after a large amount of printing, the number average circularity of the specific titanic
In order to form an image with higher image quality after mass printing, the number-average primary particle diameter of the specific titanic
As described above, an example of the structure of the toner particles contained in the toner according to the present embodiment is described with reference to fig. 1.
[ elements of toner particles ]
Next, the elements of the toner particles contained in the toner according to the present embodiment will be described.
(Binder resin)
The binder resin is contained in the toner base particles by, for example, 70 mass% or more of the total components. Therefore, it is considered that the properties of the binder resin greatly affect the properties of the entire toner base particles. In order to obtain a toner having excellent low-temperature fixability, the binder resin in the toner base particles preferably contains a thermoplastic resin, and more preferably contains the thermoplastic resin in a proportion of 85 mass% or more with respect to the total amount of the binder resin. Examples of the thermoplastic resin include: styrene-based resins, acrylic resin, olefin-based resins (more specifically, polyethylene resins, polypropylene resins, etc.), vinyl resins (more specifically, vinyl chloride resins, polyvinyl alcohol, vinyl ether resins, N-vinyl resins, etc.), polyester resins, polyamide resins, and polyurethane resins. In addition, a copolymer of the above resins, that is, a copolymer obtained by introducing an optional repeating unit into the above resin (more specifically, a styrene-acrylic resin, a styrene-butadiene resin, or the like) may be used as the binder resin.
The thermoplastic resin can be obtained by addition polymerization, copolymerization, or polycondensation of one or more thermoplastic monomers. In addition, the thermoplastic monomer is a monomer that can be a thermoplastic resin by homopolymerization (more specifically, an acrylate-based monomer, a styrene-based monomer, or the like) or a monomer that can be a thermoplastic resin by polycondensation (for example, a combination of a polyhydric alcohol and a polycarboxylic acid that can be a polyester resin by polycondensation).
In order to obtain a toner having excellent low-temperature fixability, the binder resin in the toner base particles preferably contains a polyester resin, and more preferably contains the polyester resin in a proportion of 80 mass% to 100 mass% with respect to the total amount of the binder resin. The polyester resin can be obtained by polycondensing one or more polyhydric alcohols with one or more polycarboxylic acids. The polyhydric alcohol used for synthesizing the polyester resin is, for example, the following dihydric alcohols (more specifically, aliphatic diols, bisphenols, etc.) and trihydric or higher alcohols. Examples of the polycarboxylic acid used for synthesizing the polyester resin include the following dicarboxylic acids and tricarboxylic acids. In place of the polycarboxylic acid, a polycarboxylic acid derivative (more specifically, polycarboxylic anhydride, polycarboxylic acid halide, etc.) capable of forming an ester bond by polycondensation may be used.
Preferred examples of aliphatic diols are: diethylene glycol, triethylene glycol, neopentyl glycol, 1, 2-propanediol, α, ω -alkanediols (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.
Preferred examples of the bisphenol include; bisphenol a, hydrogenated bisphenol a, bisphenol a ethylene oxide adducts, and bisphenol a propylene oxide adducts.
Preferred examples of trihydric or higher alcohols include: sorbitol, 1, 2, 3, 6-hexanetetraol, 1, 4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1, 2, 4-butanetriol, 1, 2, 5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1, 2, 4-butanetriol, trimethylolethane, trimethylolpropane and 1, 3, 5-trihydroxytoluene.
Preferred examples of dicarboxylic acids are: maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, 1, 10-decanedicarboxylic acid, succinic acid, alkylsuccinic acids (more specifically, n-butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, etc.) and alkenylsuccinic acids (more specifically, n-butenylsuccinic acid, isobutenylsuccinic acid, n-octenylsuccinic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, etc.).
Preferred examples of the tri-or more carboxylic acids include: 1, 2, 4-benzenetricarboxylic acid (trimellitic acid), 2, 5, 7-naphthalenetricarboxylic acid, 1, 2, 4-butanetricarboxylic acid, 1, 2, 5-hexanetricarboxylic acid, 1, 3-dicarboxy-2-methyl-2-methylenecarboxypropane, 1, 2, 4-cyclohexanetricarboxylic acid, tetrakis (methylenecarboxy) methane, 1, 2, 7, 8-octanetetracarboxylic acid, pyromellitic acid and Empol trimer acid.
(coloring agent)
The toner base particle may also contain a colorant. The colorant may use a well-known pigment or dye according to the color of the toner. In order to form a high-quality image using the toner, 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.
The toner base particle may contain a black colorant. Examples of black colorants are: carbon black. Further, the black colorant may be a colorant toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.
The toner base particle may contain a color colorant. The chromatic colorants are, for example, yellow colorants, magenta colorants, and cyan colorants.
Examples of the yellow coloring agent include: at least one compound selected from the group consisting of a condensed azo compound, an isoindolinone compound, an anthraquinone compound, an azo metal complex, a methine compound and an arylamide compound. Examples of the yellow coloring agent include: 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. vat yellow.
Examples of magenta colorants are: at least one compound selected from the group consisting of a condensed azo compound, a pyrrolopyrrole dione compound, an anthraquinone compound, a quinacridone compound, a basic dye lake compound, a naphthol compound, a benzimidazolone compound, a thioindigo compound, and a perylene compound. Examples of magenta colorants are: 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).
Cyan colorants are, for example: at least one compound selected from the group consisting of copper phthalocyanine compounds, anthraquinone compounds and basic dye lake compounds. Cyan colorants are, for example: c.i. pigment blue (1, 7, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62 and 66), phthalocyanine blue, c.i. vat blue and c.i. acid blue.
(mold releasing agent)
The toner base 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 waxes, polyolefin waxes (more specifically, polyethylene waxes, polypropylene waxes, etc.), microcrystalline waxes, fluororesin waxes, fischer-tropsch waxes, paraffin waxes, candelilla waxes, montan waxes, and castor waxes. Examples of the ester wax include: natural ester waxes (more specifically, carnauba wax, rice bran wax, etc.) and synthetic ester waxes. In the present embodiment, one kind of release agent may be used alone, or a plurality of kinds of release agents may be used in combination.
In order to improve the compatibility of the binder resin with the release agent, a compatibilizer may be added to the toner base particles.
(Charge control agent)
The toner base particles may contain a charge control agent. The purpose of using the charge control agent is, for example, to obtain a toner excellent in charging stability or charge growth characteristics. The charge growth characteristic of the toner is an index of whether or not the toner can be charged to a predetermined charge level in a short time.
By containing a positively chargeable charge control agent in the toner base particles, the cationic properties (positively chargeable properties) of the toner base particles can be enhanced. Further, by containing a negatively chargeable charge control agent in the toner base particles, the anionicity (negatively chargeable) of the toner base particles can be enhanced.
Examples of positively charged charge control agents are: azine compounds such as 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, 2, 4, 6-oxatriazine, 1, 3, 4, 5-oxatriazine, phthalazine, quinazoline, quinoxaline and the like; azine fast red FC, azine fast red 12BK, azine violet BO, azine brown 3G, azine light brown GR, azine dark green BH/C, azine dark black EW, azine dark black 3RL and like direct dyes; acid dyes such as nigrosine BK, nigrosine NB, nigrosine Z; an alkoxyamine; an alkylamide; quaternary ammonium salts such as benzyldecylhexylmethylammonium chloride, decyltrimethylammonium chloride, 2- (methacryloyloxy) ethyltrimethylammonium chloride, dimethylaminopropylacrylamide methylchloroquaternary salts; resins containing quaternary ammonium cationic groups. One of these charge control agents may be used alone, or two or more kinds of charge control agents may be used in combination.
Examples of negatively chargeable charge control agents are: belonging to the class of chelate organometallic complexes. The organometallic complex is preferably: at least one selected from the group consisting of acetylacetone metal complexes, salicylic acid metal complexes, and salts thereof.
In order to obtain a toner having excellent charging stability, the content of the charge control agent is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the binder resin.
(magnetic powder)
The toner base particle may contain magnetic powder. Examples of the material of the magnetic powder include: ferromagnetic metals (more specifically, iron, cobalt, nickel, etc.) and alloys thereof, ferromagnetic metal oxides (more specifically, ferrite, magnetite, chromium dioxide, etc.), and materials subjected to a ferromagnetic treatment (more specifically, carbon materials having a ferromagnetic property by a heat treatment, etc.). In this embodiment, one kind of magnetic powder may be used alone, or a plurality of kinds of magnetic powders may be used in combination.
(external additive)
The toner particles contained in the toner according to the present embodiment include an external additive attached to the surface of the toner base particles. In the external additive, one or two or more kinds of particles of a specific titanic acid compound are used as particles of the external additive.
Base material of specific titanic acid compound particles (titanic acid compound for doping)Products) are, for example: the component is MTiO3(M is a metal element other than lanthanum and the group 5 element of the periodic table among metal elements other than titanium). The component is MTiO3Specific examples of the titanic acid compound are: strontium titanate (SrTiO)3) Barium titanate (BaTiO)3) Calcium titanate (CaTiO)3) Magnesium titanate (MgTiO)3) And lead titanate (PbTiO)3). In addition, the component is MTiO3The crystal structure of the titanic acid compound represented is generally a perovskite crystal structure.
In the using component of MTiO3When the titanic acid compound is represented as a base material of specific titanic acid compound particles, lanthanum and an element of group 5 of the periodic table are incorporated into crystals of the base material by, for example, substituting a site where a metal represented by M is located. Hereinafter, a position point where a metal indicated by M is located is referred to as M position. In addition, specific titanic acid compound particles obtained by substituting M-position with lanthanum and group 5 elements of the periodic table are described as M-position substituted titanic acid compound particles.
The peak position of the powder X-ray diffraction pattern of the M-substituted titanic acid compound particles and the matrix material thereof (component MTiO)3The titanic acid compound shown) are consistent in the peak position of the powder X-ray diffraction pattern of the crystal structure. Thereby, the peak position of the powder X-ray diffraction pattern of the specific titanic acid compound particle and the matrix material (component MTiO) 3The titanic acid compound) was doped with lanthanum and the group 5 element of the periodic table in the matrix material. In addition, regarding the powder X-ray diffraction pattern, "the peak positions coincide" means that: the difference in the values of the diffraction angles (2 θ) for the 2 peak positions compared was within a range of ± 0.5 degrees.
In order to form an image of higher image quality after a large amount of printing, the specific titanic acid compound particles are preferably strontium titanate particles doped with lanthanum and a group 5 element of the periodic table, barium 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, and more preferably strontium titanate particles doped with lanthanum and niobium, barium titanate particles doped with lanthanum and niobium, or calcium titanate particles doped with lanthanum and niobium.
The method for producing the specific titanic acid compound particles is not particularly limited. In the toner according to the present embodiment, commercially available specific titanic acid compound particles may be used.
An example of a method for producing the specific titanic acid compound particles will be described below. First, a treated product obtained by dispergating a titanium source with an inorganic acid (hereinafter, sometimes referred to as a dispergated product of a titanium source), a compound of a metal element other than titanium (more specifically, strontium, barium, calcium, etc.) constituting a base material, a lanthanum source, and a source of a group 5 element of the periodic table are mixed. Then, the resulting mixture is heated to a temperature of 50 ℃ or higher, and an aqueous alkali solution is added to the mixture during the heating. Then, the mixture to which the aqueous alkali solution is added is held at a temperature of 50 ℃ or higher for a predetermined time (for example, for a time of 30 minutes or longer and 2 hours or shorter). Then, the resultant was cooled, and then hydrochloric acid was added to the resultant to obtain a precipitate. Then, the obtained precipitate is washed and filtered (solid-liquid separation), and the obtained solid component is dried, thereby obtaining a powder of particles of the specific titanic acid compound.
In one example of the method for producing the specific titanic acid compound particles, the amount of lanthanum can be adjusted by changing the relative amount of the lanthanum source with respect to the mass of the titanium source dispergation treatment product, for example. In one example of the method for producing the specific titanic acid compound particles, the amount of the group 5 element in the periodic table can be adjusted by changing the relative amount of the group 5 element source with respect to the mass of the titanium source disperged product, for example. In one example of the method for producing the specific titanic acid compound particles, the number average roundness of the specific titanic acid compound particles can be adjusted by changing the relative amount of the lanthanum source with respect to the mass of the titanium source dispergation treatment product, for example. In one example of the above-mentioned method for producing the specific titanic acid compound particles, the number-average primary particle diameter of the specific titanic acid compound particles can be adjusted by changing at least one of the mixing ratio of the compound of the metal element other than titanium constituting the base material and the titanium-source dispergation-treated product, the alkali concentration in the alkali aqueous solution, and the addition amount of the alkali aqueous solution. In one example of the method for producing the specific titanic acid compound particles, the relative dielectric constant of the specific titanic acid compound particles can be adjusted by changing at least one of the kind of the metal element other than titanium, the kind of the group 5 element of the periodic table, the relative mass amount of the source of the group 5 element of the periodic table with respect to the disperged treatment substance of the titanium source, and the relative mass amount of the lanthanum source with respect to the disperged treatment substance of the titanium source, which constitute the base material.
In order to suppress the generation of the fog even more in a high-temperature and high-humidity environment, it is preferable that the surfaces of the specific titanic acid compound particles are subjected to a hydrophobic treatment. Examples of the method for obtaining the specific titanic acid compound particles having the surface subjected to the hydrophobic treatment include: particles (hereinafter, sometimes referred to as a matrix) composed of a titanic acid compound doped with lanthanum and a periodic table group 5 element are treated with a water repellent agent. The water repellent is preferably at least one selected from the group consisting of silicone oils, silazane compounds and silane compounds, more preferably a silane compound, still more preferably a silane compound having an alkoxy group and a C3-C8 alkyl group (more specifically, n-propyltrimethoxysilane, n-propyltriethoxysilane, isobutyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, etc.), and particularly preferably isobutyltrimethoxysilane.
When the surface of the substrate is treated with a silane compound having an alkoxy group and a C3-C8 alkyl group, a hydroxyl group formed by hydrolysis of the alkoxy group of the silane compound by moisture and a hydroxyl group present on the surface of the substrate undergo a dehydration condensation reaction. By such a reaction, at least a part of the hydroxyl groups present on the surface of the substrate is substituted with a functional group containing an alkyl group (specifically, a C3-C8 alkyl group) derived from a silane compound. That is, the surface of the substrate has C3-C8 alkyl groups (hydrophobic groups) by the above reaction. Thus, the specific titanic acid compound particles have C3-C8 alkyl groups on the surfaces thereof after being subjected to a hydrophobic treatment using a silane compound having an alkoxy group and a C3-C8 alkyl group.
The specific titanic acid compound particles having a C3-C8 alkyl group on the surface become higher in hydrophobicity, and therefore the generation of fog under a high-temperature and high-humidity environment can be further suppressed.
Examples of the method for hydrophobizing the substrate include: dripping or spraying a hydrophobic agent into the matrix while stirring the matrix, and then heating the matrix coated with the hydrophobic agent; alternatively, after the base is added to a solution of the water repellent agent, the base coated with the water repellent agent is heated. The hydrophobizing agent may also be dissolved in an organic solvent. Further, a commercially available hydrophobizing agent may be diluted with an organic solvent and used.
In order to both better suppress the generation of fog and form a better high-quality image after a large amount of printing, the specific titanic acid compound particles are preferably strontium titanate particles doped with lanthanum and a group 5 element of the periodic table and having a C3-C8 alkyl group on the surface, more preferably strontium titanate particles doped with lanthanum and niobium and having a C3-C8 alkyl group on the surface, and further preferably strontium titanate particles doped with lanthanum and niobium and having an isobutyl group on the surface.
In the external additive, the external additive particles may contain only the specific titanic acid compound particles, or may further contain other external additive particles in addition to the specific titanic acid compound particles. In order to maintain good fluidity of the toner, the other external additive particles are preferably inorganic particles other than the specific titanic acid compound particles, and more preferably one or more particles selected from the group consisting of silica particles and titania particles.
Other external additive particles may also be surface treated. For example, in the case of using silica particles as other external additive particles, the surfaces of the silica particles may be rendered hydrophobic and/or positively charged by the surface treatment agent. Examples of the surface treatment agent include: a coupling agent (more specifically, a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, etc.), a silazane compound (more specifically, a chain silazane compound, a cyclic silazane compound, etc.), and a silicone oil (more specifically, dimethylsilane oil, etc.). The surface treatment agent is particularly preferably one or more selected from the group consisting of a silane coupling agent and a silazane compound. Preferred examples of the silane coupling agent include: silane compounds (more specifically, methyltrimethoxysilane, aminosilane, etc.). Preferred examples of silazane compounds are: HMDS (hexamethyldisilazane). After the surface of the silica substrate (untreated silica particles) is treated with the surface treatment agent, a part or all of a large number of hydroxyl groups (-OH) present on the surface of the silica substrate is substituted with a functional group derived from the surface treatment agent. As a result, silica particles having a functional group derived from the surface treatment agent (specifically, a functional group more hydrophobic and/or more positively charged than a hydroxyl group) on the surface thereof are obtained.
In order to suppress the external additive from coming off the toner base particle and sufficiently exert the effect of the external additive, the amount of the external additive (the total amount of the specific titanic acid compound particles and the other external additive particles in the case where other external additive particles are used) 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 particle.
< method for producing toner >
Next, a preferred method for producing a toner according to the above-described embodiment will be described. Hereinafter, description of the structural elements overlapping with those of the toner according to the above embodiment will be omitted.
[ Process for preparing toner base particles ]
First, toner base particles are prepared by an aggregation method or a pulverization method.
The agglutination method includes, for example, an agglutination step and an integration step. In the aggregating step, fine particles whose component is composed of toner base particles are aggregated in an aqueous medium to form aggregated particles. In the integration step, components contained in the aggregated particles are integrated in an aqueous medium to form toner base particles.
Next, the pulverization method will be explained. The pulverization method can relatively easily produce the toner base particles and can reduce the production cost. In the case of preparing the toner base particles by the pulverization method, the preparation step of the toner base particles includes, for example, a melt-kneading step and a pulverization step. The toner base particles may be further provided with a mixing step before the melt-kneading step in the preparation step. In the step of preparing the toner base particles, at least one of the fine pulverization step and the classification step may be further provided after the pulverization step.
In the mixing step, the binder resin is mixed with an internal additive added as needed to obtain a mixture. In the melt-kneading step, the toner material is melted and kneaded to obtain a melt-kneaded product. For example, the mixture obtained in the mixing step is used as a toner material. In the pulverization step, the obtained melt-kneaded product is cooled to, for example, room temperature (25 ℃), and then pulverized to obtain a pulverized product. When the obtained pulverized material needs to have a small diameter in the pulverization step, a step of further pulverizing the pulverized material (fine pulverization step) may be performed. In the case where the particle size of the pulverized material needs to be uniform, a step of classifying the obtained pulverized material (classification step) may be performed. The pulverized product obtained by the above-described steps is the toner base particles.
[ external addition Process ]
Then, the obtained toner base particles and the external additive are mixed by using a mixer, and the external additive is attached to the surface of the toner base particles. The external additive contains at least specific titanic acid compound particles. The mixer is, for example, an FM mixer (NIPPON coin & engine. Thereby, a toner containing toner particles is produced.
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