Toner additives and toner

Abstract

To provide an external additive which offers sufficient charged amount of charge, superior charging performance stability, and high fluidity, and to provide a toner.SOLUTION: A toner external additive is provided, containing silica particles surface-treated with polyacid metal salt particles, where the polyacid metal salt particles are composed of a salt of a polyacid and a titanium compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to toner additives and toners used in image forming methods such as electrophotography. [Background technology]

[0002] In recent years, image forming apparatuses using electrophotography have been utilized in a wide range of fields, from printers and copiers to commercial printing presses. Consequently, there is a growing demand for image forming apparatuses to be even faster and higher quality. Typically, the toner used in image forming apparatuses has its charging properties, fluidity, and durability controlled by external additives present on its surface, resulting in properties optimized for the electrophotographic process. These external additives include inorganic fine particles such as silica and titanium dioxide.

[0003] While general silica has excellent fluidity, it tends to overcharge easily, has low environmental stability, and low stability of charging performance. On the other hand, titanium dioxide has high conductivity and therefore excellent stability of charging performance, but it is prone to charge leakage and tends to have a low amount of charge. Also, because of its low fluidity, the additive is more likely to become embedded in the toner particles with long-term use, and the toner degradation progresses more easily. Furthermore, inorganic oxides such as silica used as additives have hydroxyl groups on their surface, making them hydrophilic and prone to hygroscopicity. Therefore, the hydroxyl groups on the surface dissociate due to absorbed moisture, which can easily have a significant impact on the electrical properties such as the amount of charge and conductivity.

[0004] Thus, there is a need for external additives that have a sufficient amount of charge, excellent stability in charging performance, and high fluidity, and various surface treatment methods for external additives using silica and titanium dioxide have been proposed. Patent Document 1 discloses titanium dioxide hydrophobically treated with alkyltrialkoxysilane with an alkyl group having 6 to 8 carbon atoms as an external additive for the purpose of improving the fluidity of toner. Patent Document 2 discloses an external additive in which titania fine particles are attached to the surface of a silica core and the titania fine particles are coated with a thermosetting nitrogen resin. Patent Document 3 discloses an external additive that uses in combination a silica particle powder having an alkyl group having 8 to 16 carbon atoms and an amino group on its surface, and titania particles having an amino group on its surface. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 59-52255 [Patent Document 2] Japanese Patent Publication No. 2017-134157 [Patent Document 3] Japanese Patent Publication No. 2018-163209 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The external additive disclosed in Patent Document 1 contains titanium dioxide. Titanium dioxide powder typically has a volume resistivity of 1.0 × 10⁻⁶ 7 (Ω m) or more 1.0×10 9 Having conductivity of (Ω·m) or less Because titanium dioxide has high conductivity, toners using external additives containing titanium dioxide tend to experience a decrease in the amount of charged charge and a deterioration in charge decay characteristics, making them prone to transfer defects.

[0007] In Patent Document 2, composite particles of silica particles and titania particles are used as an external additive, but the silica particles and the titania particles are not chemically bonded. Further, it is extremely difficult to uniformly disperse the titania particles on the surface of the silica particles having the same polarity code. Furthermore, since titania has high conductivity, the volume resistivity of the toner becomes small. Therefore, there is room for improvement in order to achieve both ensuring the amount of charged charge and stability. Since the electrical conductivity is high, the volume resistivity of the toner becomes small. Therefore, there is room for improvement in order to achieve both ensuring the amount of charged charge and stability.

[0008] When using the external additive disclosed in Patent Document 3, the volume resistivity of the toner tends to be relatively small compared to the volume resistivity of the printing intermediate transfer body or the transfer roller using the toner. Therefore, the amount of charged charge of the toner decreases, and transfer based on Coulomb force is less likely to occur. Therefore, the external additive disclosed in Cited Document 3 is likely to cause transfer failure similarly to Patent Document 1, and there is room for improvement.

[0009] An object of the present disclosure is to provide an external additive and a toner having a sufficient amount of charged charge, excellent stability of charging performance, and high fluidity.

Means for Solving the Problems

[0010] The present disclosure is an external additive for toner containing silica particles surface-treated with polyvalent metal salt particles, where the polyvalent metal salt particles are Particles of titanium phosphate compounds and the law of nature, The relative permittivity of the toner additive at the frequency in which the dielectric loss tangent tanδ is minimized is 2.10 or more and 2.20 or less. relates to an external additive for toner, characterized by being such.

[0011] Further, the present disclosure is a toner containing toner particles and an external additive for toner on the surface of the toner particles, where the external additive for toner is the above external additive for toner, relating to a toner.

Effects of the Invention

[0012] According to this disclosure, it is possible to provide an external additive and toner that have a sufficient amount of charge, excellent stability in charging performance, and high fluidity. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows the relationship between relative permittivity and conductivity index for external additives 1-19. [Figure 2] A diagram showing the relationship between the amount of titanium lactate added and the dielectric constant. [Figure 3] A diagram showing the relationship between the amount of titanium lactate added and the conductivity index. [Modes for carrying out the invention]

[0014] The embodiments will be described in detail below, but this disclosure is not limited to the following description. In this disclosure, the expressions "XX or more and YY or less" or "XX to YY" that represent a numerical range mean a numerical range that includes the lower and upper limits, which are the endpoints, unless otherwise specified. Furthermore, when a numerical range is described in steps, the upper and lower limits of each numerical range can be combined in any way.

[0015] This disclosure relates to an external additive for toner containing silica particles surface-treated with polyvalent metal salt particles, The toner additive is characterized in that the polyhydric acid metal salt particles are a salt of a polyhydric acid and a titanium compound.

[0016] Furthermore, this disclosure relates to a toner containing toner particles and the toner additive.

[0017] The inventors have discovered that by using particles of a salt of a polyhydric acid and a titanium compound as a surface modifier for silica particles, it is possible to provide an external additive for toner and a toner that have a sufficient amount of charge, excellent stability of charging performance, and ensure high fluidity. The inventors consider the reasons for this as follows.

[0018] Silica particles have high volume resistivity, but are also hydrophilic due to the presence of hydroxyl groups (silanol groups) on their surface, making them prone to hygroscopicity. When silica particles absorb moisture, the hydroxyl groups dissociate due to the moisture, significantly affecting their electrical properties, such as the amount of charge and conductivity. The inventors of this invention hypothesized that by chemically surface-treating the surface of silica particles with a titanium-based material that exhibits excellent charge stability, the amount of charge and charge stability could be ensured.

[0019] Titanium dioxide is commonly used as an external additive for toners, but it is difficult to achieve chemical interaction with silica particles with titanium dioxide. Another method involves using titanium alkoxide and utilizing hydrolysis and polycondensation reactions to chemically bond with the hydroxyl groups on the surface of silica particles. However, titanium alkoxide reacts quickly in aqueous systems, making reaction control difficult, and presents challenges in terms of dispersibility. This is because, after water coordinates with the titanium alkoxide, it forms a Ti-OH group, which then reacts with other titanium alkoxide molecules to form a metalloxane bond (Ti-O-Ti bond). Furthermore, this reaction occurs continuously, forming a polytitanoxane structure.

[0020] Therefore, the present inventors have found that by using polyhydric acid metal salt particles, which are particles of a salt of a polyhydric acid and a titanium compound, as a surface treatment agent, the reaction rate can be controlled while stable and uniform interaction with silica particles can be obtained.

[0021] Polyhydric acids readily accept electron pairs and become negatively charged. Furthermore, titanium is a group 4 element, and its most stable state is when its oxidation state is +4. Therefore, titanium compounds form a cross-linked structure with polyhydric acids, and this cross-linked structure promotes electron transfer, improving the rate of charge buildup and suppressing charge-up, thereby ensuring excellent charge stability. In addition, the reaction product of polyhydric acid and group 4 element titanium exhibits good environmental stability because the cross-linked structure blocks water molecules. Moreover, it is thought that polyhydric acid metal salt particles, which are salt particles of polyhydric acid and titanium compounds, react with hydroxyl groups on the surface of silica particles to form metalloxane bonds (Si-O-Ti bonds). As a result, it is possible to obtain external additive particles that integrate the properties of silica and metal particles. Also, because the hydroxyl groups on the surface of silica particles react with polyhydric acid metal salt particles to form metalloxane bonds, the number of hydroxyl groups that dissociate on the surface of silica particles decreases. Generally, if the conductivity is too high, i.e., if the volume resistivity is too low, the amount of charge decreases due to leakage current. If the conductivity is too low, i.e., if the volume resistivity is too high, charge-up occurs. On the other hand, when silica particles are surface-treated with polyvalent metal salt particles, electron movement is controlled as described above, resulting in appropriate conductivity (volume resistivity). Therefore, leakage current can be controlled, and both improved capacitance, charging speed, and charge-up suppression can be achieved, improving the stability of charging performance.

[0022] Thus, by using silica particles as a core, it is possible to obtain a toner additive that ensures high fluidity while simultaneously achieving both sufficient charge and stable charge by using polyvalent metal salt particles as a surface treatment agent. No toner additive with the above configuration has existed before, and the inventors have succeeded in obtaining a toner additive with the above configuration and a toner using this toner additive for the first time.

[0023] There are no particular limitations on the method for surface-treating silica particle surfaces with polyvalent metal salt particles, but examples include the following: One method involves adding and mixing a polyvalent acid and a titanium compound into a silica particle dispersion to react with the polyvalent metal salt particles, obtaining a reaction product. Simultaneously, the dispersion is stirred to allow the reaction product to adhere to and react with the silica particle surface, thereby obtaining surface-treated silica particles. Another method involves adding and mixing pre-formed polyvalent metal salt particles into a silica particle dispersion to allow them to adhere to and react with the silica particle surface, thereby obtaining surface-treated silica particles.

[0024] As for the polyhydric acid, there are no particular restrictions and conventionally known polyhydric acids can be used. Examples include inorganic acids such as phosphoric acid (trivalent), carbonic acid (divalent), and sulfuric acid (divalent); and organic acids such as dicarboxylic acids (divalent) and tricarboxylic acids (trivalent). Specific examples of organic acids include dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, and terephthalic acid; and tricarboxylic acids such as citric acid, aconitic acid, and trimellitic anhydride.

[0025] The polyhydric acid preferably contains an inorganic acid. Inorganic acids have a more rigid molecular skeleton compared to organic acids, so their properties change less during long-term storage. Therefore, stable properties can be obtained even after long-term storage. The polyhydric acid more preferably contains at least one selected from the group consisting of phosphoric acid, carbonic acid, and sulfuric acid, and even more preferably phosphoric acid. When the polyhydric acid is phosphoric acid, when the salt particles of phosphoric acid and titanium compound react with the hydroxyl groups on the surface of the silica particles to form metalloxane bonds (Si-O-Ti bonds), a pyrophosphate skeleton is formed as a crosslink between the polyhydric acid and the titanium compound, thus forming a stronger and more stable surface layer. Furthermore, when added to an aqueous medium, the polyhydric acid itself may be added, or water-soluble polyhydric acid metal salt particles may be added to the aqueous medium and dissociated in the aqueous medium.

[0026] Any known titanium compound can be used as the titanium compound, as long as it reacts with polyhydric acid ions to yield polyhydric acid metal salts. Specifically, at least one selected from the group consisting of titanium lactate, titanium tetraacetylacetonate, titanium lactate ammonium salt, titanium triethanolamine, etc. Among these, titanium chelates are preferred because the reaction is easy to control and reacts quantitatively with polyhydric acid ions. Furthermore, lactic acid chelates such as titanium lactate are more preferred from the viewpoint of solubility in aqueous media.

[0027] Specific examples of polyvalent metal salt particles include salt particles of a titanium compound with a polyvalent acid such as phosphoric acid, sulfuric acid, carbonic acid, or oxalic acid. Examples include titanium phosphate compounds, titanium sulfate compounds, titanium carbonate compounds, and titanium oxalate compounds. It is preferable that the polyvalent acid contains at least one selected from the group consisting of sulfuric acid, carbonic acid, and phosphoric acid, and it is more preferable that the polyvalent acid is phosphoric acid. Since phosphate ions have high strength due to crosslinking between metals and also have excellent charge rise due to having ionic bonds within the molecule, it is more preferable that the polyvalent metal salt particles include salt particles of phosphoric acid and a titanium compound.

[0028] In surface-treated silica particles, it is preferable that Si-O-Ti bonds are formed by polyvalent metal salt particles. Surface-treated silica particles with polyvalent metal salt particles preferably form metalloxane bonds (Si-O-Ti bonds) between the hydroxyl groups (silanol groups) on the silica particle surface and the polyvalent metal salt particles. This increases capacitance (i.e., increases relative permittivity), ensuring a sufficient amount of charge. Furthermore, since the number of hydroxyl groups on the silica particle surface decreases, conductivity decreases (i.e., volume resistivity increases), which suppresses the decrease in charge due to leakage current and ensures a sufficient amount of charge. In addition, it is preferable that the polyvalent metal salt particles form a crosslink between the polyvalent acid and the titanium compound. This crosslink promotes electron movement, resulting in appropriate conductivity, improving the charging response to toner and suppressing charge-up, thus ensuring excellent charging stability. Moreover, since the polyvalent metal salt particles can block water molecules with this crosslink, environmental stability is improved.

[0029] The number-average particle size of the primary particles of polyvalent metal salt particles can be observed using a transmission electron microscope (TEM). The number-average particle size of the primary particles of these polyvalent metal salt particles is between 2.0 nm and 10.0 nm in order to enhance the adhesion force (van der Waals force) between silica particles and toner particles. The size is preferably less than or equal to nm, and more preferably between 2.0 nm and 5.0 nm. Furthermore, the polyvalent metal salt particles may be present in a partially aggregated state within the silica particles, and it is preferable that the height of the aggregates relative to the normal direction of the silica particles is 50 nm or less. The primary particle size and aggregation state of polyvalent metal salt particles can be controlled by the shear energy of the stirring device and the addition rate and concentration of the titanium compound.

[0030] The content of polyvalent metal salt particles in the silica particles is preferably 0.01% by mass or more and 1.00% by mass or less, and more preferably 0.05% by mass or more and 0.20% by mass or less. When the content is 0.01% by mass or more and 1.00% by mass or less, a certain amount of hydroxyl groups on the surface of the silica particles react with the polyvalent metal salt particles to form metalloxane bonds, which reduces conductivity, increases volume resistivity and relative permittivity, thereby suppressing charge buildup and obtaining a sufficient amount of charged material. Furthermore, the content of polyvalent metal salt particles in the silica particles can be controlled by the amount of silica particles, polyvalent acid, titanium compound, or polyvalent metal salt particles added, the specific surface area of ​​the silica particles, and the type of polyvalent metal salt particles.

[0031] The number-average particle size of the silica particles is preferably between 7 nm and 600 nm, and more preferably between 10 nm and 500 nm. If the number-average particle size is less than 7 nm, van der Waals forces become dominant in the silica particles, increasing non-electrostatic adhesion between toners and between the toner and the developing roller or intermediate transfer body. This non-electrostatic adhesion tends to reduce the toner's fluidity, durability, and transferability. If the number-average particle size of the silica particles exceeds 600 nm, external forces are easily applied to the silica particles added to the toner during toner agitation, causing the silica particles to become embedded or migrate. As a result, the toner surface becomes heterogeneous, which tends to cause fogging and a decrease in image density. For similar reasons, the number-average particle size of silica particles surface-treated with polyvalent metal salt particles is preferably 9 nm to 604 nm, and more preferably 14 nm to 504 nm.

[0032] The BET specific surface area of ​​silica particles is 6 m². 2 / g or more 290m 2 It is preferable that it is less than or equal to / g, and 7m 2 / g or more 210m 2 It is more preferable that the value is less than or equal to / g. A larger BET specific surface area of ​​silica particles indicates a smaller number-average particle size, and a smaller BET specific surface area indicates a larger number-average particle size. A BET specific surface area of ​​290m² is preferable.2 When the BET specific surface area of ​​silica particles exceeds 6 m², van der Waals forces become dominant, increasing non-electrostatic adhesion between toners and between toners and developing rollers or intermediate transfer media. This non-electrostatic adhesion can easily reduce the toner's fluidity, durability, and transferability. 2 If the amount is less than / g, external force is more easily applied to the silica particles added to the toner during agitation, causing the silica particles to become embedded or migrate. As a result, the toner surface becomes heterogeneous, which can easily lead to fogging and a decrease in image density.

[0033] There are no particular restrictions on the silica particles, but examples include silica particles obtained by wet methods such as sol-gel silica particles, gel silica particles, aqueous colloidal silica particles, and alcoholic silica particles, as well as silica particles obtained by gas-phase methods such as molten silica particles and deflagration silica particles. Among these, sol-gel silica particles obtained by the sol-gel method are preferred. The sol-gel method is a method in which alkoxysilane is hydrolyzed and condensed with a catalyst in an organic solvent containing water to obtain a silica sol suspension, and then the solvent is removed from the silica sol suspension and dried to obtain silica fine particles. Because sol-gel silica particles have many hydroxyl groups (silanol groups) on their surface, the surface treatment is more easily formed uniformly by the reaction of these hydroxyl groups with polyvalent metal salt particles. In addition, because sol-gel silica particles have high circularity and a sharp particle size distribution, fluctuations in the properties as an external additive are less likely to occur.

[0034] The relative permittivity of the toner additive at the frequency where the dielectric loss tangent tanδ is minimized is 2.10 It is preferable that the relative permittivity is 2.20 or less. When the relative permittivity is 2.10 or higher, a certain amount of hydroxyl groups on the surface of the silica particles react with the polyvalent acid metal salt particles to form metalloxane bonds, and a crosslinked material between the polyvalent acid and the titanium compound is formed, which can impart a sufficient amount of charge to the toner additive. Furthermore, the relative permittivity can be controlled by the amount of silica particles, polyvalent acid, titanium compound, or polyvalent acid metal salt particles added. The measurement of the relative permittivity will be described later.

[0035] When the reciprocal of the conductivity κ at a measurement frequency of 0.021 Hz is defined as the volume resistivity, the volume resistivity of the external additive for toner is preferably 1.54×10 12 (Ω·m) or more, more preferably 2.19×10 12 (Ω·m) or more, and still more preferably 6.58×10 12 (Ω·m) or more. Also, the volume resistivity is preferably 1.32×10 14 (Ω·m) or less, more preferably 1.10×10 14 (Ω·m) or less. When the volume resistivity is 1.54×10 12 (Ω·m) or more, the hydroxyl groups on the surface of a certain amount of silica particles react with polyvalent acid metal salt particles to form a metalloxane bond, and a crosslinked product of a polyvalent acid and a titanium compound is formed. In the external additive for toner, charge-up is suppressed and the stability of the charging performance is improved. Therefore, the toner produced using the external additive for toner exhibits good developability and transferability. Also, the volume resistivity can be controlled by the addition amounts of silica particles, polyvalent acid, titanium compound, or polyvalent acid metal salt particles. The measurement of the volume resistivity will be described later.

[0036] When the value obtained by dividing the conductivity κ at a measurement frequency of 1 Hz by the angular frequency ω is defined as the conductivity index κ / ω, the conductivity index κ / ω of the external additive for toner is preferably 6.44×10 -12 (S / m)·s or less, more preferably 4.51×10 -12 (S / m)·s or less, and still more preferably 1.50×10 -12 (S / m)·s or less. Also, the conductivity index κ / ω of the external additive for toner is preferably 7.56×10[[ID=2S]] -14 (S / m)·s or more, more preferably 9.02×10 -14 (S / m)·s or more. When the conductivity index κ / ω is 6.44×10 -12When the conductivity index κ / ω is less than or equal to (S / m)·s, a certain amount of hydroxyl groups on the surface of silica particles react with polyvalent acid metal salt particles to form metalloxane bonds, and a crosslinked material is formed between the polyvalent acid and the titanium compound. In this state, charge-up is suppressed in the toner additive, and the stability of the charging performance is improved. Furthermore, the conductivity index κ / ω can be controlled by the amount of silica particles, polyvalent acid, titanium compound, or polyvalent acid metal salt particles added. The measurement of the conductivity index κ / ω will be described later.

[0037] Regarding the electrical properties of the toner additive, the relative permittivity is 2.12 or higher and 2.21 or lower, and the conductivity index κ / ω at a measurement frequency of 1 Hz is 9.02 × 10⁻⁶. -14 (S / m)·s or more 4.51×10 -12 (S / m)·s or less, or resistivity of 2.19 × 10 at a measurement frequency of 0.021 Hz 12 (Ω m) or more 1.10×10 14 It is preferable that the value be within the range of (Ω·m) or less.

[0038] Silica particles surface-treated with polyvalent metal salt particles may be further surface-treated, such as hydrophobic treatment, as necessary, to the extent that the properties of the toner additives of this disclosure are not impaired. Examples of hydrophobic treatment agents include unmodified silicone varnish, various modified silicone varnishes, unmodified silicone oil, various modified silicone oils, silane compounds, and silane coupling agents. These treatment agents may be used alone or in combination.

[0039] Next, we will describe toners using the toner additives of this disclosure. The toner of this disclosure is a toner comprising toner particles and an external toner additive on the surface of the toner particles, The toner additive is the toner additive of this disclosure, and the toner is the toner.

[0040] The toner particles may contain known binder resins, colorants, waxes, etc. Furthermore, they may contain charge control agents as needed, within limits that do not impair the properties of the present invention. Additionally, external additives other than those disclosed herein may be added to the toner particles.

[0041] The method for producing toner particles is not particularly limited, and methods such as grinding, emulsification and agglutination, suspension polymerization, and dissolution and suspension can be used. Furthermore, the toner additives disclosed herein can be added to the toner particles by known methods. The weight-average particle size (D4) of the toner particles is preferably 4 to 12 μm, and more preferably 5 to 8 μm.

[0042] Toner prepared using the toner additives disclosed herein requires a volume resistivity of 1.15 × 10⁻⁶ at 0.021 Hz to suppress charge-up and achieve both good developability and transferability. 13 (Ω m) or more 1.00×10 14 It is preferable that the value is less than or equal to (Ω·m).

[0043] There are no particular restrictions on the binder resin as long as it can form toner particles. For example, the following types of resins can be used: styrene resin, acrylic resin, methacrylic resin, styrene-acrylic resin, styrene-methacrylic resin, polyethylene resin, polyethylene-vinyl acetate resin, vinyl acetate resin, polybutadiene resin, phenolic resin, polyurethane resin, polybutyral resin, polyester resin, and hybrid resins formed by arbitrarily combining these resins.

[0044] Examples of colorants include known organic pigments or dyes, carbon black, and magnetic materials. Pigments may be used alone, or dyes and pigments may be used in combination.

[0045] For magenta coloring pigments, use CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48:1, 48:2, 48:3, 48:4, 48:5, 49, 50, 51, 52, 53, 54, 55, 57:1, 58, 60, 63, Examples include 64, 68, 81:1, 81:2, 81:3, 81:4, 81:5, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 185, 202, 206, 207, 209, 238, 269, 282; CI Pigment Violet 19; CI Bat Red 1, 2, 10, 13, 15, 23, 29, 35.

[0046] Examples of cyan coloring pigments include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specifically, examples include CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0047] Examples of yellow coloring pigments include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specifically, these include CI Pigment Yellows 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; and CI Bat Yellows 1, 3, and 20.

[0048] Examples of black colorants include carbon black, aniline black, acetylene black, titanium black; iron oxide; and colorants for yellow, magenta, and cyan that have been mixed to produce black.

[0049] The amount of colorant in the toner particles is not particularly limited, as long as it is sufficient to achieve the desired coloring effect. For example, it may be 3.0 to 15.0 parts by mass per 100 parts by mass of binder resin or polymerizable monomer.

[0050] Examples of waxes include paraffin wax, microcrystalline wax, petrolatum and other petroleum-based waxes and their derivatives, montan wax and its derivatives, hydrocarbon waxes and their derivatives produced by the Fischer-Tropsch process, polyolefin waxes represented by polyethylene and their derivatives, natural waxes such as carnauba wax and candelilla wax and their derivatives. These derivatives also include oxides, block copolymers with vinyl monomers, and graft-modified products. Other examples include alcohols such as higher aliphatic alcohols, fatty acids such as stearic acid and palmitic acid, or acid amides and esters of these compounds, hydrogenated castor oil and its derivatives, plant waxes, and animal waxes. Waxes can be used alone or in mixtures of two or more. The wax content in the toner particles is preferably 2.5 to 15.0 parts by mass per 100 parts by mass of the binder resin or polymerizable monomer.

[0051] Known charge control agents can be used. Examples of charge control agents that control the load charge of toner particles include polymer compounds having sulfonic acid groups, sulfonic acid bases, or sulfonic acid ester groups; salicylic acid derivatives and their metal complexes; monoazo metal compounds; acetylacetone metal compounds; aromatic oxycarboxylic acids, aromatic monocarboxylic acids, or polycarboxylic acids and their metal salts, anhydrides, or esters; phenol derivatives such as bisphenol; urea derivatives; boron compounds; and calixarenes. Charge control agents that control negative charge can be used alone or in combination of two or more. On the other hand, examples of charge control agents that control the positive charge of toner particles include nigrosine and nigrosine-modified products such as fatty acid metal salts, guanidine compounds, imidazole compounds, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts which are analogs thereof, and their lake pigments, triphenylmethane dyes and their lake pigments (lake agents include phosphate tungstic acid, phosphate molybdic acid, phosphate tungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids, diorganostin oxides such as dibutyltin oxide, dioctyltin oxide, and dicyclohexyltin oxide, and diorganostin borates such as dibutyltin borate, dioctyltin borate, and dicyclohexyltin borate. Charge control agents that control positive charge can be used alone or in combination of two or more. The content of the charge control agent in the toner particles is preferably 0.1 parts by mass to 10.0 parts by mass, and more preferably 0.1 parts by mass to 5.0 parts by mass, per 100 parts by mass of the binder resin or polymerizable monomer.

[0052] The following describes methods for measuring various physical properties of external additives and toners. <Relative permittivity and volume resistivity of external additives and toners> The electrical properties of external additives and toners are evaluated by measuring the capacitance and conductivity of air and powder using impedance measurements with the parallel plate capacitor method.

[0053] The apparatus uses a powder measurement jig consisting of a 4-terminal sample holder SH2-Z (manufactured by Toyo Technica Co., Ltd.) and a torque wrench adapter SH-TRQ-AD (manufactured by Toyo Technica Co., Ltd., optional), as well as a ModuLab XM MTS material testing system (manufactured by Solartron Corporation). In addition, a noise-cutting transformer NCT-I3 1.4kVA (manufactured by Denken Seiki Kenkyusho Co., Ltd.) to suppress commercial power supply noise and a shielded box to suppress electromagnetic noise are used.

[0054] The powder measurement jig uses a 4-terminal sample holder and the optional torque wrench adapter SH-TRQ-AD. Parallel plate electrodes are used: an upper electrode (Φ25mm solid electrode) SH-H25AU and a lower electrode for liquids / powder (center electrode Φ10mm; guard electrode Φ26mm) SH-2610AU. This configuration allows for the measurement of resistances from 0.1Ω to 1TΩ for electrical signals up to 500Vp-p and DC~AC 1MHz. Furthermore, to adjust the pressure of the powder sample, the torque wrench adapter SH-TRQ-AD is attached to a micrometer used for measuring film thickness between the upper and lower electrodes, which is mounted on the 4-terminal sample holder. For pressure control, torque drivers RTD15CN and RTD30CN (manufactured by Tohnichi Manufacturing Co., Ltd.) and a 6.35mm square bit are used, allowing for tightening torque control of 6.5cN·m for toner measurement and 20.0cN / m for external additives.

[0055] Electrical AC characteristics are measured using the ModuLab XM MTS material testing system (manufactured by Solartron), with impedance measurements being performed. The ModuLab XM MTS consists of a control module XM MAT 1MHz, a high-voltage module XM MHV100, a femtocurrent module XM MFA, and a frequency response analysis module XM MRA 1MHz. The control software used is Solartron's XM-studio MTS Ver.3.4.

[0056] For measuring insulating powder materials such as toner, the measurement conditions are set to Normal Mode, which is for measurement only, with an AC level of 7Vrms, a DC bias of 0V, and a sweep frequency of 1MHz to 0.01Hz (12 points / decade or 6 points / decade). For highly conductive powder materials such as external additives, the AC level should be set to 7 × 10⁻¹⁰ to fit within the current range of the measuring instrument. -3 Set the value within the range of Vrms to 7Vrms.

[0057] Furthermore, considering noise suppression and reduction of measurement time, the following settings will be added for each sweep frequency. Sweep frequency 1MHz~10Hz, measurement integration time 64 cycles Sweep frequency 10Hz~1Hz, measurement integration time 24 cycles Sweep frequency 1Hz~0.01Hz, measurement integration time 1 cycle Under the above measurement conditions, the impedance characteristics, which are electrical AC characteristics, will be measured.

[0058] By performing measurements under the above conditions, the impedance characteristics of air and sample at a film thickness d corresponding to the pressurized torque can be obtained using a powder measurement jig based on the parallel plate condenser method, with a Φ10 mm measuring electrode S.

[0059] From the obtained impedance characteristics of the air and sample, data correction processing of the measurement system is performed to obtain highly reliable capacitance C and conductance G. From the obtained capacitance C, conductance G, and the geometric shape of the powder measurement jig (parallel plate electrode size S and sample film thickness), the electrical properties relative permittivity and conductivity are determined.

[0060] When using the SH2-Z 4-terminal sample holder for the first time, there are individual differences between the SH2-Z 4-terminal sample holders used in powder measurement jigs. Therefore, the following two verifications must be performed to find the optimal measurement conditions. The first verification is the film thickness dependence characteristic of the 4-terminal sample holder. Measure the dependence on air thickness (distance between upper and lower electrodes), check the error between the theoretical value and the measured value of capacitance, and determine the optimal range or film thickness at which the measurement error is minimized. The second verification is the measurement of mechanical errors. When measuring powder samples, a torque-controlled load is applied to maintain a constant volume density. In contrast, air measurements are performed under no-load conditions. In this case, film thickness errors occur due to the influence of dimensional factors such as mechanical processing accuracy. Therefore, the tightening torque control value (6.5 cN·m in this jig) Check the offset value between the loaded and unloaded states, and use this as the offset correction value.

[0061] The specific sample preparation and measurement procedures are as follows: (1) Place the powder sample on the central electrode portion of the lower electrode and shape it into a trapezoidal shape with a height of 5 mm. (2) Attach the lower electrode, on which the powder sample is placed, to the 4-terminal sample holder SH2-Z, and lower the upper electrode. (3) At this time, the upper electrode is lowered to the upper end of the powder sample while keeping it constant so as not to rotate unintentionally. (4) While rotating the upper electrode from side to side, perform a smoothing process to make the powder sample smooth. (5) Using a micrometer, adjust the film thickness to the desired level while maintaining the rotation direction of the upper electrode in a uniform, consistent direction. (6) In the case of toner, pressurize using a torque driver with a tightening torque controlled to 6.5 cN·m. In the case of external additives, pressurize using a torque driver with a tightening torque controlled to 20.0 cN·m. (7) Use a micrometer to measure the film thickness of the powder sample. (8) Perform impedance measurements under the above conditions. (9) After the measurement is complete, raise the upper electrode and remove the lower electrode. At this time, remove the lower electrode carefully, making sure that no powder sample enters the contact terminals for the lower electrode of the 4-terminal sample holder, and protect them with masking tape. (10) Clean the upper and lower electrodes. (11) Remove the masking tape and attach the lower electrode. (12) Adjust the air thickness t to the sample film thickness d obtained in step (7), taking into account the offset correction under no-load conditions, and maintain the rotation direction of the upper electrode in a uniform, constant direction. (13) Measure the impedance of the air. (14) If the measured air data (dielectric loss tangent; tanδ) measured in step (13) is greater than 0.001 in the frequency range of 100Hz to 0.021Hz, the cleaning is insufficient, and the process is repeated starting from the cleaning step in step (10). The measurement will be conducted at 25°C.

[0062] The specific data processing procedure is as follows: (15) From the measured impedance characteristics of the air, the error in the phase characteristics relative to the theoretical value is calculated, and phase correction data is obtained for the ModuLab XM MTS material testing system (manufactured by Solartron). (16) The phase correction data calculated in step (15) is applied to the impedance characteristics of the air measured in step (13) to obtain the impedance characteristics of the air after phase correction processing. (17) The capacitance Ca is calculated from the admittance Ya = Ga + jωCa of the phase-corrected air impedance characteristics, and the error with the theoretical value is calculated to obtain correction data α for the film thickness error. (18) The phase correction process obtained in step (15) is applied to the impedance characteristics of the powder sample measured in step (8). (19) The relative permittivity and conductivity of the powder sample can be obtained with high reliability by calculating the complex admittance Ym = Gm + jωCm of the characteristic after the phase correction processing in step (18) using the capacitance of air Ca obtained in step (17) and its correction data α.

[0063] The following describes methods for quantifying electrical properties such as relative permittivity and volume resistivity. (Method for quantifying relative permittivity) Relative permittivity is a factor related to the charging properties of particles, and if an increase in relative permittivity is observed, polyvalent gold It can be confirmed that the silica particles have been surface-treated with polyvalent metal salt particles. In the external additives of this disclosure, it is thought that the capacitance increases and the relative permittivity increases as polyvalent metal salt particles chemically adsorb onto the hydroxyl groups present on the surface of the silica particles. Specifically, as shown in Figure 2, compared to untreated silica particles (external additive 16 in the examples described later), the relative permittivity increases and saturates in proportion to the amount of titanium lactate, which is a surface treatment agent, added (external additives 1, 2, and 3 in the examples described later). The relative permittivity indicating the orientation polarization component of the powder sample is the value of the relative permittivity at the frequency at which the dielectric loss tangent tanδ in the measured high-frequency range is minimized.

[0064] (Quantification method for the conductivity index κ / ω) Generally, the conductivity κ of a dielectric (insulator) is proportional to the angular frequency. Therefore, it is useful to use the conductivity index κ / ω, obtained by dividing the conductivity κ by the angular frequency ω, as the conductivity parameter value. The conductivity index κ / ω exhibits frequency characteristics similar to the dielectric loss tangent tanδ, and a maximum value is obtained when the dielectric relaxation of the electrode interface component and the powder bulk component are different. The maximum value of the conductivity index κ / ω is considered to represent the conductivity of the powder bulk, including the inside of the particles, the particle surface, and the (particle-particle) interface. Therefore, this maximum value is defined as the conductivity parameter of the powder bulk component. It is believed that conductivity arises from the dissociation of hydroxyl groups present on the surface of silica particles. Therefore, it is thought that when a surface treatment agent chemically adsorbs onto these hydroxyl groups, the number of dissociating hydroxyl groups, which are the conductive factors, decreases, and thus the conductivity also decreases. Specifically, as shown in Figure 3, for untreated silica particles (external additive 16), the conductivity index κ / ω decreases in proportion to the amount of titanium lactate, a component of the surface treatment agent, exhibiting characteristics similar to those of general hydrophobic treatment (external additives 1, 2, and 3). Furthermore, since the frequency characteristics at which the maximum values ​​of the conductivity index κ / ω for external additives 1, 2, and 3 are obtained were at 1 Hz, the value at 1 Hz is used as the conductivity index κ / ω for the external additives.

[0065] (Methods for quantifying electrical conductivity and volume resistivity) A powder sample possessing both capacitance and conductivity can be recognized as an RC parallel circuit model, exhibiting a constant conductivity κ in the low-frequency range. The reciprocal of this conductivity κ is defined as the volume resistivity.

[0066] Determining the true volume resistivity of dielectric (insulating) powder samples is difficult because they fall outside the measurement range of the measuring device. Therefore, we use the conductivity κ at a measurement frequency of 0.021 Hz, where the accuracy of the measuring device can be guaranteed, and define its reciprocal as the volume resistivity (f = 0.021 Hz).

[0067] <Method for detecting polyvalent metal salt particles> Using time-of-flight secondary ion mass spectrometry (TOF-SIMS), polyvalent metal salt particles present on the surface of silica particles are detected by the following method.

[0068] The external additive samples were analyzed using TOF-SIMS (TRIFTIV: ULVAC-PHI) under the following conditions. • Primary ion species: Gold ion (Au) + ) • Primary ion current value: 2 pA ·Analysis area: 300×300μm 2 • Pixel count: 256 pixels × 256 pixels ·Analysis time: 3min • Repetition frequency: 8.2kHz • Neutralizing static charge: ON • Secondary ion polarity: Positive Secondary ion mass range: m / z 0.5~1850 • Sample substrate: Indium

[0069] From the peaks obtained by the above analysis, polyvalent metal salt particles present on the silica particle surface are identified. If peaks originating from secondary ions containing metal ions and polyvalent ions (for example, TiPO3 (m / z 127), TiP2O5 (m / z 207), etc., in the case of salts of phosphoric acid and titanium compounds) are detected, polyvalent metal salt particles are present on the silica particle surface.

[0070] <Method for measuring the content of polyvalent metal salt particles in silica particles> The content of polyvalent metal salt particles in silica particles is calculated by measuring X-ray fluorescence. The measurement of X-ray fluorescence for each element conforms to JIS K 0119-1969, specifically as follows: The measurement equipment used is the wavelength-dispersive X-ray fluorescence analyzer "Axios" (PANalytical Corporation) and the accompanying dedicated software "SuperQ ver.4.0F" (PANalytical Corporation) for setting measurement conditions and analyzing measurement data. Rh is used as the anode of the X-ray tube, the measurement atmosphere is vacuum, the measurement diameter (collimator mask diameter) is 27 mm, and the measurement time is 10 seconds. A proportional counter (PC) is used when measuring light elements, and a scintillation counter (SC) is used when measuring heavy elements.

[0071] For the measurement sample, 4.0g of toner is placed in a dedicated aluminum ring for pressing, leveled, and then compressed at 20MPa for 60 seconds using a tablet molding compressor "BRE-32" (manufactured by Maekawa Testing Machinery Co., Ltd.) to form a pellet with a thickness of 2mm and a diameter of 39mm. Measurements are performed under the above conditions, and the element is identified based on the peak position of the obtained X-rays. The concentration is then calculated from the counting rate (unit: cps), which is the number of X-ray photons per unit time.

[0072] <Method for measuring the number-average particle size of silica particles and external additive particles> The particle size distribution of silica particles and external additive particles is measured using a dynamic light scattering particle size distribution analyzer, NanoTrack UPA-EX150 (manufactured by Nikkiso), according to the operation manual of the analyzer. Specifically, the sample is adjusted in the sample introduction section of the analyzer so that the transmittance is within the measurable range (70% to 95%), and the particle size (median diameter) corresponding to 50% of the cumulative number distribution standard is measured.

[0073] <Method for measuring the BET specific surface area of ​​core particles> The BET specific surface area of ​​core particles such as silica particles can be determined by a low-temperature gas adsorption method using a dynamic constant-pressure method, according to the BET method (preferably the BET multi-point method). For example, by using a specific surface area measuring device "Gemini 2375 Ver. 5.0" (manufactured by Shimadzu Corporation), nitrogen gas is adsorbed onto the sample surface, and the BET specific surface area (m²) can be determined by measuring using the BET multi-point method. 2 The value ( / g) was calculated. Specifically, the measurement was performed using the following procedure.

[0074] After measuring the mass of an empty sample cell, fill the sample cell with the sample to be measured to approximately 80% of its volume. Then, place the sample-filled sample cell in the degassing device and degas it at room temperature for 7 hours. After degassing is complete, measure the total mass of the sample cell and calculate the exact mass of the sample from the difference between the mass of the sample cell and the empty sample cell. Next, place the empty sample cell in the balance port and analysis port of the BET measuring device. Place a Dewar flask containing liquid nitrogen in the designated position and measure the saturated vapor pressure (P0) using the P0 measurement command. After the P0 measurement is complete, place the degassed sample cell in the analysis port, input the sample mass and P0, and start the measurement using the BET measurement command. The BET specific surface area will then be calculated automatically.

[0075] <Method for measuring the weight-average particle size (D4) of toner particles> The weight-average particle size (D4) of toner (particles) is measured using the "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter), a precision particle size distribution analyzer using the pore electrical resistance method with a 100 μm aperture tube, and the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting measurement conditions and analyzing measurement data. The measurement is performed with 25,000 effective measurement channels, and the measurement data is analyzed to calculate the D4. The electrolytic aqueous solution used for measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter).

[0076] Before performing measurements and analysis, configure the dedicated software as follows: In the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (manufactured by Beckman Coulter). Press the Threshold / Noise Level measurement button to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the "Flush Aperture Tube After Measurement" option. In the "Pulse to Particle Size Conversion Settings" screen of the dedicated software, set the bottle spacing to logarithmic particle size, the particle size bottle to 256 particle size bottle, and the particle size range to 2 μm or more and 60 μm or less.

[0077] The specific measurement method is as follows: (1) Pour approximately 200 ml of the electrolytic solution into a 250 ml round-bottom glass beaker specifically designed for the Multisizer 3, set it on the sample stand, and stir the mixture with the stirrer rod at 24 revolutions per second in a counterclockwise direction. Then, use the "Aperture Flash" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube. (2) Place approximately 30 ml of the electrolytic aqueous solution into a 100 ml flat-bottomed glass beaker, and add approximately 0.3 ml of a diluted solution of "Contaminon N" (a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted three times by mass with deionized water as a dispersant. (3) Two oscillators with an oscillation frequency of 50 kHz are built in with their phases shifted by 180 degrees, and a predetermined amount of deionized water is placed in the water tank of an ultrasonic dispersion device called "Ultrasonic Dispersion System Tetora150" (manufactured by Nikko Bios Co., Ltd.) with an electrical output of 120 W. Approximately 2 ml of the aforementioned Contaminon N is added to this water tank. (4) Place the beaker from (2) into the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic aqueous solution inside the beaker is maximized. (5) While irradiating the electrolytic aqueous solution in the beaker described in (4) with ultrasound, add approximately 10 mg of toner (particles) to the electrolytic aqueous solution in small amounts and disperse it. Continue the ultrasonic dispersion treatment for another 60 seconds. During ultrasonic dispersion, adjust the water temperature in the tank to be between 10°C and 40°C as appropriate. (6) Using a pipette, the electrolytic aqueous solution from (5) containing dispersed toner (particles) is dropped into the round-bottom beaker from (1) placed in the sample stand, and the concentration is adjusted to approximately 5%. The measurement is then continued until the number of particles to be measured reaches 50,000. (7) The measurement data is analyzed using the dedicated software attached to the device, and the weight-average particle size (D4) is calculated. Note that the "Average Diameter" on the Analysis / Volume Statistics (Arithmetic Mean) screen when the dedicated software is set to Graph / Volume % is the weight-average particle size (D4).

[0078] <Method for identifying polyvalent metal salt particles on the surface of silica particles> In external additives, the surface treatment of silica particles with particulate polyvalent metal salts can be confirmed by scanning electron microscopy (SEM, TEM). TEM observation is Follow these steps:

[0079] The cross-section of silica particles is observed using a transmission electron microscope (TEM) in the following manner. First, silica particles are sufficiently dispersed in a room-temperature curing epoxy resin, and then cured for two days in a 40°C atmosphere. From the resulting cured material, a 50 nm thick flaky sample is cut using a microtome (EMUC: Leica) equipped with a diamond blade. This sample is magnified 500,000 times using a TEM (JEM2800: JEOL) with an acceleration voltage of 200 V and an electron probe size of 1 mm, and the cross-section of the silica particles is observed. At this time, the cross-section of the silica particle having a maximum diameter 0.9 to 1.1 times the number-average particle size measured according to the method for measuring the number-average particle size of silica particles is selected. At this time, it can be confirmed that polyvalent metal salt particles are present on the surface of the silica particles. In addition, the cross-sectional area of ​​the confirmed polyvalent metal salt particles (primary particles) is measured, and the equivalent diameter of a circle is calculated. The same process is performed on 100 or more particles, and the number-average particle size of the primary particles is calculated.

[0080] Next, the constituent elements of the obtained cross-section are analyzed using energy-dispersive X-ray spectroscopy (EDX), and an EDX mapping image (256 pixels × 256 pixels, 2.2 nm / pixel, 200 integrations) is prepared. In the prepared EDX mapping image, signals of silicon can be observed inside the silica particles, and signals of phosphorus, titanium, etc., originating from polyvalent metal salt elements can be observed on the surface of the silica particles. Furthermore, by analyzing with the time-of-flight secondary ion mass spectrometry method described above (TOF-SIMS analysis), it is determined that a reaction product between a polyvalent acid and a compound containing a group 4 element is present.

[0081] <Separation of external additives from toner> When separating external additives from toner, use the following method. Weigh 1g of toner and disperse it in 100ml of water to which 1mg of "Contaminon N" (a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) is added. The dispersion is irradiated with ultrasound and processed in a centrifuge at a predetermined intensity, and the supernatant is dried to separate only the external additive. [Examples]

[0082] The present disclosure will be further described below with reference to manufacturing examples and embodiments, but these are not intended to limit the present disclosure in any way. All parts used in the embodiments refer to parts by mass.

[0083] <Example of silica particle production> In a 1.5 L glass reaction vessel equipped with a stirrer, dropping nozzle, and thermometer, 500 parts methanol and 70 parts 10% by mass aqueous ammonia were added and mixed to obtain an alkaline catalyst solution. After adjusting this alkaline catalyst solution to 30°C, 100 parts tetramethoxysilane (TMOS) and 20 parts 8.0% by mass aqueous ammonia were simultaneously added dropwise over 60 minutes while stirring to obtain a hydrophilic spherical silica particle dispersion. The obtained spherical silica particle dispersion was filtered, washed, and dried to obtain silica particles 1, which are sol-gel silica particles. The number-average particle size of the obtained silica particles 1 was 100 nm.

[0084] <Manufacturing examples of silica particles 2-9> In the production of silica particle 1, silica particles 2 to 9, which are sol-gel silica particles, were obtained in the same manner as in the production example of silica particle 1, except that the preparation temperature and amount of the alkaline catalyst solution, and the dropping time of tetramethoxysilane were appropriately changed. The physical properties of the obtained silica particles 2 to 9 are shown in Table 1.

[0085] <Silica particles 10, 11> For silica particle 10, dry silica particles with a particle size of 7 nm (AEROSIL® 300, manufactured by Nippon Aerosil Co., Ltd.) were prepared, and for silica particle 11, dry silica particles with a particle size of 600 nm (SO-E2, manufactured by Admatex Co., Ltd.) were prepared. The physical properties of silica particles 10 and 11 are shown in Table 1.

[0086] [Table 1]

[0087] <Example of manufacturing of external additive 1> • 100.0 parts of deionized water • Sodium phosphate (decadal hydrate) [manufactured by Rasa Industries Co., Ltd.] 8.5 parts The above components were mixed to prepare an aqueous phosphoric acid solution. Next, 63.0 parts of the aqueous phosphoric acid solution and 1:7.0 parts of silica particles were added to the reaction vessel and stirred at 12,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at 55°C, and 13.8 parts of a 44% titanium lactate aqueous solution (TC-310: manufactured by Matsumoto Fine Chemical Co., Ltd.) were added. Subsequently, while mixing with a propeller stirring blade, the pH was adjusted to 9.5 using a 1.0 mol / L NaOH aqueous solution, and the temperature was maintained at 55°C while stirring for 3 hours.

[0088] After lowering the temperature to 25°C, the solid was extracted by centrifugation. This process of dispersing the mixture again in deionized water and extracting the solid by centrifugation was repeated three times to remove ions such as sodium. The mixture was then dispersed again in deionized water and dried by spray drying to obtain silica particles coated with a salt of phosphoric acid and titanium compound. This was designated as external additive 1. Analysis of external additive 1 by time-of-flight secondary ion mass spectrometry (TOF-SIMS) revealed a peak originating from the salt of phosphoric acid and titanium compound. Furthermore, the content of the salt particles of phosphoric acid and titanium compound was calculated using X-ray fluorescence. Other physical properties are shown in Table 2. The frequency at which the maximum value of the conductivity index κ / ω for external additive 1 was obtained was 1 Hz.

[0089] <Manufacturing examples of external additives 2-11> External additives 2-11 were obtained in the same manner as in the preparation example of external additive 1, except that the type of silica particles and the amount of titanium lactate added were changed as shown in Table 2. All of the obtained external additives 2-11 showed peaks originating from the salt of phosphoric acid and titanium compound. Other physical properties are shown in Table 2. Furthermore, the frequency at which the maximum values ​​of the conductivity index κ / ω for external additives 2 and 3 were obtained was 1 Hz.

[0090] <Manufacturing example of external additive 12> External additive 12 was obtained in the same manner as the production example of external additive 1, except that silica particles 11 were used and the amount of titanium lactate added was changed to the amount shown in Table 2. In all cases of the obtained external additive 12, peaks originating from the salt of phosphoric acid and titanium compound were observed. Other physical properties are shown in Table 2.

[0091] <Manufacturing example of 13 external additives> External additive 13 was obtained in the same manner as the production example of external additive 1, except that silica particles 10 were used and the amount of titanium lactate added was changed to the amount shown in Table 2. The obtained external additive 13 showed a peak originating from the salt of phosphoric acid and titanium compound. Other physical properties are shown in Table 2.

[0092] <Manufacturing example of external additive 14> In the preparation example of external additive 1, external additive 14 was obtained in the same manner as in the preparation example of external additive 1, except that sodium phosphate was replaced with sodium carbonate. In all cases of the obtained external additive 14, peaks originating from titanium carbonate compounds were observed. Other physical properties are shown in Table 2.

[0093] <Manufacturing example of external additive 15> In the preparation example of external additive 1, external additive 15 was obtained in the same manner as in the preparation example of external additive 1, except that sodium sulfate was replaced with sodium phosphate. In all cases of the obtained external additive 15, peaks originating from titanium sulfate compounds were observed. Other physical properties are shown in Table 2.

[0094] <External Additive 16> Silica particles 1 were used as the external additive 16.

[0095] <Manufacturing example of external additive 17> Ilmenite ore containing 50% by mass of TiO2 was used as the starting material. After drying this material at 150°C for 2 hours, sulfuric acid was added and dissolved to obtain an aqueous solution of TiO4. This was concentrated, and 4.5 parts by mass of titania sol containing rutile crystals were added as a seed. Hydrolysis was then carried out at 110°C to obtain a slurry of TiO(OH)2 containing impurities. This slurry was repeatedly washed with water at pH 5-6 to thoroughly remove sulfuric acid, FeSO4, and impurities. A slurry of high-purity metatitanic acid [TiO(OH)2] was then obtained. This slurry was filtered and calcined at 180°C for 2 hours, and then repeatedly crushed using a jet mill until no aggregates of fine particles remained. This titanium dioxide was dispersed in ethanol, and 4.6% by mass of isobutyltrimethoxysilane and 4.6% by mass of trifluoropropyltrimethoxysilane were added dropwise to 100 parts by mass of titanium dioxide solids, while stirring thoroughly to prevent particle coalescence, and the mixture was allowed to react. Furthermore, the pH of the slurry was adjusted to 6.5 while thoroughly stirring. After filtration and drying, it was heat-treated at 170°C for 2 hours, and then repeatedly crushed using a jet mill until the titanium dioxide aggregates were gone, thereby obtaining titanium dioxide particles. These were designated as external additive 17. The physical properties of the obtained external additive 17 are shown in Table 2.

[0096] <Manufacturing example of external additive 18> Ilmenite ore containing 50% by mass of TiO2 was used as the starting material. After drying this material at 150°C for 2 hours, sulfuric acid was added and dissolved to obtain an aqueous solution of TiO2. This was concentrated, and 4.5 parts by mass of titania sol containing rutile crystals were added as a seed. Hydrolysis was then carried out at 110°C to obtain a slurry of TiO(OH)2 containing impurities. This slurry was repeatedly washed with water at pH 5-6 to thoroughly remove sulfuric acid, FeSO4, and impurities. Then, high-purity metatitanic acid [TiO(OH) A slurry of (2) was obtained. This slurry was filtered and calcined at 180°C for 2 hours, and then repeatedly crushed using a jet mill until the aggregates of fine particles were gone, thereby obtaining titanium oxide core particles. The BET specific surface area of ​​the titanium oxide core particles was measured and found to be 75.3 m². 2 It was / g.

[0097] Next, the following components were mixed to prepare an aqueous phosphoric acid solution. • 100.0 parts of deionized water • Sodium phosphate (decadal hydrate) [manufactured by Rasa Industries Co., Ltd.] 8.5 parts

[0098] Next, 63.0 parts of an aqueous phosphoric acid solution and 7.0 parts of titanium dioxide core particles were added to the reaction vessel and stirred at 12,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at 55°C. Then, 3.27 parts of a 44% aqueous titanium lactate solution (TC-310: manufactured by Matsumoto Fine Chemical Co., Ltd.) were added. Subsequently, while mixing with a propeller stirring blade, the pH was adjusted to 9.5 using a 1.0 mol / L aqueous NaOH solution, and the temperature was maintained at 55°C while stirring for 3 hours. After lowering the temperature to 25°C, the solids were removed by centrifugation. Then, the process of dispersing again in deionized water and removing the solids by centrifugation was repeated three times to remove ions such as sodium. The mixture was dispersed again in deionized water and dried by spray drying to obtain titanium dioxide particles coated with particles of a salt of phosphoric acid and titanium compound. This was designated as external additive 18. Analysis of external additive 18 by time-of-flight secondary ion mass spectrometry (TOF-SIMS) revealed a peak originating from a salt of phosphoric acid and a titanium compound. Other physical properties are shown in Table 2.

[0099] <Manufacturing example of external additive 19> 100 parts by mass of dry silica powder with a median volume diameter (D50) of 80 nm, obtained by gas-phase synthesis, and 25 parts by mass of titania powder (AEROXIDE® NKT90, manufactured by Nippon Aerosil Co., Ltd.) with a median volume diameter (D50) of 15 nm were mixed for 30 seconds at a rotation speed of 600 rpm using a pin mill (Sample Mill SAM-0, manufactured by Nara Machine Works Co., Ltd.). As a result, silica-titania composite particles were obtained in which multiple titania particles (externally added titania particles) were attached to the surface of each silica particle contained in the silica powder. These were designated as external additive 19. The physical properties of external additive 19 are shown in Table 2.

[0100] [Table 2]

[0101] In the external additives disclosed herein, polyvalent metal salt particles, which are surface treatment agents, are chemically adsorbed onto the surface of untreated silica particles. It is believed that a reaction occurs between at least some of the polyvalent metal salt particles and the surface of the untreated silica particles, resulting in bonding. This is suggested by the changes in the electrical properties, namely the relative permittivity and conductivity. The results are shown in Figure 1.

[0102] Figure 2 shows the dependence of the amount of surface treatment agent (titanium lactate) added on the relative permittivity of external additives 1-3 and 16, and will be explained below. Figure 2 suggests that the chemical adsorption of polyvalent metal salt particles onto the hydroxyl groups present on the surface of external additive 16 (untreated silica particles) improves the capacitance, which contributes to the charging properties, and increases the relative permittivity. Furthermore, it was shown that the relative permittivity increases and saturates in proportion to the amount of titanium lactate added.

[0103] Figure 3 shows the dependence of conductivity in external additives 1-3 and 16 on the amount of surface treatment agent (titanium lactate) added, and will be explained below. When polyvalent metal salt particles chemically adsorb onto the hydroxyl groups present on the surface of external additive 16 (untreated silica particles), the number of dissociating hydroxyl groups, which are conductive factors, decreases, and the conductivity decreases.

[0104] Furthermore, the conductivity κ of titanium phosphate and titanium trioxide phosphate manufactured by Mitsuwa Chemical Co., Ltd. is 1.27 × 10⁻⁶. -4 , and 9.80×10 -6 The value was ((S / m)·s). Thus, generally speaking, polyvalent metal salt particles exhibit high conductivity. Considering the conductivity of the toner additive of this disclosure, it is considered that the polyvalent metal salt particles are not simply adhering to the silica particles, but rather that at least a portion of the polyvalent metal salt particles are reacting with the surface of the silica particles.

[0105] <Example of toner particle 1 manufacturing> [Examples of preparation of polymerizable monomer compositions] The following composition was mixed and then dispersed in a ball mill for 3 hours. • Styrene 82.0 parts 2-ethylhexyl acrylate 18.0 parts • Divinylbenzene 0.1 part ·CIPigment Blue 15:3 5.5 parts • Polyester resin 5.0 parts [Polycondensate of propylene oxide-modified bisphenol A and isophthalic acid (glass transition temperature 65°C, weight-average molecular weight (Mw) 10000, number-average molecular weight (Mn) 6000)]

[0106] The resulting dispersion was heated to 60°C while stirring at 300 rpm. Then, 12.0 parts of ester wax (with a peak temperature of the maximum endothermic peak in differential scanning calorimetry at 70°C and a number-average molecular weight (Mn) of 704) and 3.0 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) were added and dissolved to obtain a polymerizable monomer composition.

[0107] [Examples of preparing aqueous dispersion media] 710 parts of deionized water and 450 parts of 0.1 mol / L sodium phosphate aqueous solution were added to a 2 L four-necked flask equipped with a high-speed stirring device TK Homomixer (Primix Corporation), and the mixture was heated to 60°C while stirring at 12,000 rpm. 68.0 parts of 1.0 mol / L calcium chloride aqueous solution were then gradually added to prepare an aqueous dispersion medium containing calcium phosphate as a minute, poorly water-soluble dispersion stabilizer.

[0108] [Granulation / polymerization process] A polymerizable monomer composition was added to an aqueous dispersion medium and granulated for 15 minutes while maintaining a rotation speed of 12,000 rpm. Then, the stirrer was replaced from a high-speed stirrer to a propeller-type stirrer, and polymerization was continued at an internal temperature of 60°C for 5 hours. Afterward, the internal temperature was raised to 80°C, and polymerization was continued for another 3 hours. After the polymerization reaction was complete, the remaining monomers were removed by distillation at 80°C under reduced pressure, and then cooled to 30°C to obtain a polymer fine particle dispersion.

[0109] [Washing and drying process] The obtained polymer microparticle dispersion was transferred to a washing container, and while stirring, dilute hydrochloric acid was added to adjust the pH to 1.5. After stirring the dispersion for 2 hours, solid-liquid separation was performed using a filter to obtain polymer microparticles. The obtained polymer microparticles were added to 1.0 L of deionized water and stirred to form a dispersion again, and then solid-liquid separation was performed using a filter. After repeating this operation three times, the polymer microparticles that were finally separated solid-liquid were thoroughly dried in a dryer at 30°C to obtain toner particles 1 with a weight-average particle size (D4) of 6.8 μm.

[0110] <Example of Toner 1 manufacturing> 100 parts toner particles were mixed with 2.0 parts of external additive 1 using an FM mixer (manufactured by Nippon Coke Industries Co., Ltd.). The external additive conditions were 1.8 kg of toner particles, a rotation speed of 3600 rpm, and an external additive time of 30 minutes. The mixture was then sieved through a 200 μm mesh to obtain toner 1.

[0111] <Manufacturing examples for toners 2-19> Toners 2 to 19 were obtained in the same manner as in the manufacturing example of toner 1, except that the external additives used were changed as shown in Table 3.

[0112] <Example of Toner 20 manufacturing> For every 100 toner particles, 2.0 parts of external additive 16 and 1.0 part of external additive 17 were mixed using an FM mixer (manufactured by Nippon Coke Industries Co., Ltd.). The external additive was added under the following conditions: a toner particle input of 1.8 kg, a rotation speed of 3600 rpm, and an external additive time of 30 minutes. The mixture was then sieved through a 200 μm mesh to obtain toner 20.

[0113] <Examples 1, 4-15, and Comparative Examples 1-5> The evaluation methods for Toner 1 and Toners 4-20 are described below. The evaluation results are shown in Table 3. A Canon LBP652C laser beam printer was used for the evaluation. Toner was removed from the cyan cartridge, and Toners 1, 4-20 were refilled, and the following evaluations were performed. Examples 4, 14, and 15 were evaluated as reference examples.

[0114] <Evaluation of overlap> Performance evaluation of external additives by controlling the charge amount was performed by evaluating fogging. Fogging was evaluated under harsh conditions of 15°C and 10.0% RH humidity. After outputting 3000 images, an image with a white background was output, and the fogging density (%) was calculated from the difference between the whiteness of the white background of the output image and the whiteness of the evaluation paper, measured using a "REFLECTMETER MODELTC-6DS" (Tokyo Denshoku Co., Ltd.). Image fogging was evaluated according to the following criteria. An amber light filter was used. A score of C or higher was considered good. A: 0.5% or less B: 0.6% or more and 1.5% or less C: 1.6% or more and 2.5% or less D: 2.6% or more

[0115] <Evaluation of transferability> Performance evaluations related to leakage of external additives were conducted by evaluating transferability. The transferability evaluation was performed in a high-temperature, high-humidity environment (temperature 30.0°C, relative humidity 85%), which is considered to be more demanding on transferability. The evaluation paper used was FOX RIVER BOND rough paper (110 g / m²).2 The following method was used. After transferring a solid black image, the remaining toner on the photoreceptor was taped off using polyester adhesive tape (No. 31B, 15 mm wide) (manufactured by Nitto Denko Corporation). At this time, the Macbeth reflectance of the tape attached to paper was defined as C, the Macbeth density of the tape attached to paper with toner on it before fixing after transfer was defined as D, and the Macbeth density of the tape attached to unused paper was defined as E. The following formula was used for approximation. A higher value indicates better transferability. A value of C or higher was considered good. Transferability (%) = {(DC) / (DE)} × 100 A: The transferability is 95% or higher. B: The transferability is 90% or more but less than 95%. C: The transferability is 85% or more but less than 90%. D: The transcription rate is less than 85%.

[0116] <Evaluation of image density> The durability of the external additive was evaluated by measuring changes in image density. Image density was evaluated in a high-temperature, high-humidity environment (temperature 30.0°C, relative humidity 80%). To simulate long-term durability testing, a horizontal line pattern with a print density of 1% was used as one job per sheet. A total of 12,000 print tests were conducted in a mode where the machine stopped briefly between jobs before the next job started. The difference in image density between the first sheet and the 12,000th sheet was measured. A4 color laser copier paper (Canon, 80g / m²) was used. 2 The following was used: Image density was measured by outputting a 5mm x 5mm solid black patch image and measuring the reflectance density using a Macbeth densitometer (manufactured by Macbeth Corporation) with an SPI filter. A smaller difference in image density between the first and 12,000th images indicated better durability, and a score of C or higher was considered good. A: The difference in image density is less than 0.10. B: The difference in image density is 0.10 or greater and less than 0.20. C: The difference in image density is 0.20 or greater and less than 0.25. D: The difference in image density is 0.25 or greater. The results of each evaluation are shown in Table 3.

[0117] [Table 3]

[0118] This disclosure relates to the following configuration. (Composition 1) An external additive for toner containing silica particles surface-treated with polyvalent metal salt particles, An external additive for toner, characterized in that the polyhydric acid metal salt particles are a salt of a polyhydric acid and a titanium compound. (Configuration 2) The toner additive according to configuration 1, wherein the content of the polyvalent metal salt particles in the silica particles is 0.01% by mass or more and 1.00% by mass or less. (Composition 3) The toner additive according to composition 1 or 2, wherein the polyhydric acid contains at least one selected from the group consisting of sulfuric acid, carbonic acid, and phosphoric acid. (Composition 4) The toner additive according to composition 3, wherein the polyhydric acid is phosphoric acid. (Composition 5) An external additive for toner according to any of configurations 1 to 4, wherein the number-average particle size of the silica particles is 10 nm or more and 500 nm or less. (Composition 6) An external additive for toner according to any one of configurations 1 to 5, wherein the silica particles are sol-gel silica particles. (Composition 7) A toner comprising toner particles and an external toner additive on the surface of the toner particles, A toner in which the toner additive is the toner additive described in any of the components 1 to 6.

Claims

1. An external additive for toner containing silica particles surface-treated with polyvalent metal salt particles, The polyvalent metal salt particles are particles of a titanium phosphate compound. The relative permittivity of the toner additive at the frequency where the dielectric loss tangent tanδ is minimized is 2.10 or more and 2.20 or less. An external additive for toner characterized by the following features.

2. The toner additive according to claim 1, wherein the content of the polyvalent metal salt particles in the silica particles is 0.01% by mass or more and 1.00% by mass or less.

3. The toner additive according to claim 1 or 2, wherein the number-average particle size of the silica particles is 7 nm or more and 600 nm or less.

4. The toner additive according to claim 3, wherein the number-average particle size of the silica particles is 10 nm or more and 500 nm or less.

5. The toner additive according to claim 1 or 2, wherein the number-average particle size of the silica particles surface-treated with the polyvalent metal salt particles is 9 nm or more and 604 nm or less.

6. The toner additive according to claim 5, wherein the number-average particle size of the silica particles surface-treated with the polyvalent metal salt particles is 14 nm or more and 504 nm or less.

7. The toner additive according to claim 1 or 2, wherein the silica particles are sol-gel silica particles.

8. A toner comprising toner particles and an external toner additive on the surface of the toner particles, A toner characterized in that the toner additive is the toner additive described in claim 1 or 2.

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