Toner and two-component developer including the same

Abstract

To provide toner having chargeability sufficiently developed and expressing antibacterial properties even after being fixed to a printed matter, and a two-component developer including the same.SOLUTION: Toner is constituted of at least toner mother particles and an external component externally added to the surfaces of the toner mother particles. The external component includes at least titanium oxide particles, zinc oxide particles and an external additive; the titanium oxide particles and the zinc oxide particles have average primary particle diameters of 75-200 nm and 80-300 nm, respectively; and when setting external addition rates of the titanium oxide particles and zinc oxide particles to the toner mother particles to A mass% and B mass%, respectively, a relation between the formula (1):0.5≤A / B≤2.0 and the formula (2):7≤(A+B)≤12 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a toner and a two-component developer containing the same. [Background technology]

[0002] Metals such as copper and silver have antibacterial properties and have traditionally been used in tableware, coins, and other items. The recent pandemic has led to the development of a variety of products that incorporate these antibacterial and antiviral properties. For example, antibacterial properties can be imparted to products by molding materials incorporating these antibacterial agents into desired shapes, such as sheets, or by spraying liquids containing these agents onto objects.

[0003] Also, a technique has been proposed in which an antibacterial agent is kneaded into electrophotographic toner to impart antibacterial properties to the surface of the toner fixed on the printed matter. For example, Japanese Patent Laid-Open No. 2003-241414 (Patent Document 1) discloses a coating method in which the surface of an image body is coated with a transparent toner containing an antibacterial agent, and then the toner is fixed to impart antibacterial properties to the image body. Furthermore, Japanese Patent Laid-Open Publication No. 2022-122546 (Patent Document 2) discloses an image forming method capable of stably forming an image having antibacterial and antiviral properties using a toner containing particles made of a binder resin, a release agent, and an inorganic antibacterial and antiviral agent that meets specific requirements, and discloses silver, copper, zinc, titanium oxide, and the like as the inorganic antibacterial and antiviral agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-241414 [Patent Document 2] Japanese Patent Publication No. 2022-122546 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the techniques described in Patent Documents 1 and 2 are unable to impart sufficient antibacterial properties to the surface of the toner fixed on the printed matter. The reasons for this are thought to be: (1) when an antibacterial component is added internally to the toner, there is a low probability that the antibacterial component will be exposed to the surface during fixing; (2) a single antibacterial component is not effective enough; and (3) when a large amount of a single antibacterial component is added externally to the toner in order to obtain a sufficient antibacterial effect, the antibacterial component is released from the toner surface, and only toner with a high electrostatic charge is selectively developed and fixed, resulting in a decrease in the antibacterial component on the printed matter.

[0006] Therefore, an object of the present disclosure is to provide a toner that has sufficient chargeability for development and that can exhibit antibacterial properties even after being fixed to a printed matter, and a two-component developer containing the toner. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that by externally adding titanium oxide particles and zinc oxide particles having a specific average primary particle size to toner base particles in a specific ratio, it is possible to maintain chargeability while exhibiting excellent antibacterial properties, thereby solving the above-mentioned problems, and have thus completed the present invention.

[0008] Thus, according to the present disclosure, a toner is composed of at least toner base particles and an externally added component externally added to the surface of the toner base particles, the externally added components include at least titanium oxide particles, zinc oxide particles, and an external additive; the titanium oxide particles and zinc oxide particles have average primary particle sizes of 75 to 200 nm and 80 to 300 nm, respectively; When the external addition ratios of the titanium oxide particles and zinc oxide particles to the toner base particles are A mass % and B mass %, respectively, the following formulas (1) and (2): 0.5≦A / B≦2.0 (1) 7≦(A+B)≦12 (2) The toner is characterized by satisfying the following relationship:

[0009] The present disclosure also provides a two-component developer containing the above toner and a carrier. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a toner that has sufficient chargeability for development and that can exhibit antibacterial properties even after being fixed to a printed matter, and a two-component developer containing the toner. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an SEM image of a toner of the present disclosure. [Figure 2] 1 is an SEM image of titanium oxide particles externally added to a toner of the present disclosure. [Figure 3] 1 is an SEM image of zinc oxide particles externally added to a toner of the present disclosure. [Figure 4] 2A and 2B are schematic diagrams illustrating the mechanism by which the toner of the present disclosure exhibits antibacterial properties. DETAILED DESCRIPTION OF THE INVENTION

[0012] Below, we will explain the "mechanism for manifesting antibacterial properties" of the toner of the present disclosure, its main components "titanium oxide particles and zinc oxide particles," "external additives," and "conductive agents," and then explain (1) the toner, (2) its manufacturing method, (3) a two-component developer containing the toner of the present disclosure, and (4) its applications.

[0013] [Mechanism of antibacterial activity] In general, the mechanism by which antibacterial agents exhibit antibacterial properties is largely unknown, but the following mechanism is speculated. (1) Antibacterial agents steal electrons from water, generating OH radicals (·OH), which destroy the cell membrane of bacteria and stop their activity. Antibacterial agents also donate electrons to oxygen in the air, generating superoxide anions (O 2- ), which destroys the bacterial cell membrane and stops the bacteria's activity. This effect is more effective when the surface area of ​​the antibacterial agent is larger and the opportunities for contact with bacteria and viruses are greater, since the substances that exert the antibacterial action are relatively unstable, such as radicals, and act on bacteria and viruses near the surface of the antibacterial agent. (2) Positively charged metal ions are generated from the antibacterial agent, which come into contact with negatively charged bacteria and viruses, penetrate into their interiors, and bind to their proteins, stopping their activity. This effect is more effective as it lasts longer than effect (1) and the total number of generated metal ions is greater, since the antibacterial action is exerted by metal ions.

[0014] In the toner of the present disclosure, titanium oxide and zinc oxide, each of which exhibits antibacterial properties by itself, exhibit antibacterial effects through a synergistic effect. FIG. 4 is a schematic diagram illustrating the mechanism by which the toner of the present disclosure exhibits antibacterial properties, and the description will be based on this diagram. When titanium oxide, which has a relatively high ionization tendency, comes into contact with zinc oxide, which has a relatively low ionization tendency, the titanium oxide steals electrons from the zinc oxide and becomes a metal ion. These metal ions then come into contact with bacteria or viruses and penetrate their interiors, bonding with proteins and stopping the activity of the bacteria (see effect (2) above, bottom of Figure 4). On the other hand, zinc oxide, which has stolen electrons from titanium oxide, gives electrons to oxygen in the air, forming superoxide anions (O 2- ), which destroys the bacterial cell membrane and stops the bacterial activity (see effect (1) above, top of Figure 4).

[0015] In order for a printed matter to which a toner containing an antibacterial agent has been fixed to exhibit sufficient antibacterial properties, the antibacterial agent must be exposed on the surface when the toner is fixed to the print object. Adding a small amount of antibacterial agent is ineffective, and adding a large amount, if the antibacterial agent has conductivity, can affect the charging performance of the toner, preventing efficient development. The toner of the present disclosure enhances antibacterial power through the synergistic effect of titanium oxide and zinc oxide, thereby enabling a reduction in the total amount of titanium oxide and zinc oxide to be added, allowing development without problems even when charged as in the conventional method, and imparting sufficient antibacterial properties to printed matter. In order to fully utilize the synergistic effect of titanium oxide and zinc oxide, they must be brought into contact with each other efficiently, and the preferred conditions for this are shown below.

[0016] [Titanium oxide particles and zinc oxide particles] <Average primary particle diameter> In the toner of the present disclosure, the titanium oxide particles and zinc oxide particles have average primary particle sizes of 75 to 200 nm and 80 to 300 nm, respectively. If the average primary particle size of the titanium oxide particles is less than 75 nm, the particles have a high cohesion force, making them difficult to disperse, and the desired effect may not be obtained.On the other hand, if the average primary particle size of the titanium oxide particles is more than 200 nm, the particles tend to detach from the toner surface, and even if they do not detach, they may have adverse effects such as localized current leakage, and the desired effect may not be obtained. The average primary particle size of the titanium oxide particles is preferably 80 to 150 nm, more preferably 85 to 100 nm.

[0017] If the average primary particle size of zinc oxide is less than 80 nm, the particles have a high cohesion force, making them difficult to disperse, and the desired effect may not be obtained. On the other hand, if the average primary particle size of zinc oxide is more than 300 nm, the particles tend to detach from the toner surface, and even if they do not detach, adverse effects such as localized current leakage may occur, making it difficult to obtain the desired effect. The average primary particle size of the zinc oxide particles is preferably 85 to 200 nm, more preferably 90 to 150 nm.

[0018] If the difference in particle size between the two particles is too large, the contact area and contact opportunity between the two particles will decrease, and the synergistic effect may not be efficiently achieved. From this perspective, it is preferable that the particle sizes of the two particles are approximately the same. Furthermore, since the particle shape also affects the contact area and contact frequency of the two particles, the particle shape must also be taken into consideration when setting the optimum particle size of the two particles. Titanium oxide particles have a relatively cubic shape, while zinc oxide particles have a shape in which columnar particles are occasionally found. Therefore, when converted into a sphere-equivalent diameter, as described above, it is preferable that the zinc oxide particles have a particle size range that is slightly larger than that of the titanium oxide particles. The method for measuring the average primary particle diameter of titanium oxide particles and zinc oxide particles will be described in the Examples.

[0019] <External addition ratio> In the toner of the present disclosure, the external addition ratio A / B of titanium oxide particles and zinc oxide particles is expressed by the following formula (1): 0.5≦A / B≦2.0 (1) The relationship between the two particles is satisfied. If one particle is present unevenly, the opportunities for contact between the two will decrease, and ultimately the result will be the same as if they were added alone. Therefore, it is thought that an external addition rate of at least one particle should be about half that of the other. By satisfying this relationship, a synergistic effect between the titanium oxide particles and zinc oxide particles will be realized, and antibacterial performance can be improved. If the external addition ratio A / B is less than 0.5, the amount of titanium oxide is too small, and if the external addition ratio A / B exceeds 2.0, the amount of zinc oxide is too small, so that a sufficient synergistic effect may not be obtained. The external addition ratio A / B is preferably 0.7 or more and 1.5 or less, and more preferably 0.8 or more and 1.2 or less.

[0020] <Total external addition rate> In the toner of the present disclosure, the total external addition ratio (A+B) of the titanium oxide particles and zinc oxide particles as externally added components is expressed by the following formula (2): 7≦(A+B)≦12 (2) By satisfying this relationship, a synergistic effect between the titanium oxide particles and the zinc oxide particles is exhibited, and the antibacterial performance can be enhanced. If the total external addition ratio (A+B) is less than 7% by mass, a sufficient antibacterial effect may not be obtained, whereas if the total external addition ratio (A+B) is more than 12% by mass, sufficient charging properties may not be obtained, resulting in poor developability. The total external addition ratio (A+B) is preferably 8% by mass or more and 11.5% by mass or less, and more preferably 9% by mass or more and 11% by mass or less.

[0021] <External addition ratio> The toner of the present disclosure satisfies the following formula (3): 2.5≦(A+B) / E≦20 (3) It is preferable that the following relationship is satisfied. If the ratio (A+B) / E is less than 2.5, the fluidity of the toner may be insufficient, whereas if the ratio (A+B) / E is more than 20, the charging performance of the toner may be adversely affected. The ratio (A+B) / E is more preferably 5 or more and 15 or less, and particularly preferably 7 or more and 10 or less.

[0022] <Adhesion strength> In the toner of the present disclosure, the titanium oxide particles and zinc oxide particles each preferably have an adhesion strength of 60 to 100%. If the adhesion strength is less than 60%, many particles will be detached from the toner surface, increasing the number of free particles, which may adversely affect the charging performance of the toner. The adhesive strength is more preferably 70 to 97%, and particularly preferably 80 to 95%. The method for measuring the adhesive strength will be specifically explained in the Examples.

[0023] <Surface treatment and hydrophobicity rate> Surface-untreated titanium oxide particles and zinc oxide particles are hydrophilic, and when added to a toner, they aggregate and cannot be added in a highly dispersed state. Therefore, in the toner of the present disclosure, it is preferable that the titanium oxide particles and zinc oxide particles are subjected to an appropriate surface (hydrophobic) treatment. By subjecting these particles to surface treatment, it is possible to prevent particle aggregation and, since the particles become more compatible with the binder resin of the toner, when these particles are externally added to the toner base particles, it is expected that the adhesion strength to the toner surface will be improved, making it more difficult for the particles to detach. Known methods can be applied for the surface treatment, and examples of the surface treatment agent include silane coupling agents, titanium coupling agents, silicone oil, and hydrogen dimethicone.

[0024] The degree of the surface treatment can be expressed by the hydrophobicity ratio, and in the toner of the present disclosure, the titanium oxide particles and zinc oxide particles each preferably have a hydrophobicity ratio of 40 to 80%. If the hydrophobicity ratio is less than 40%, the effect of preventing particle aggregation may be insufficient, while if the hydrophobicity ratio exceeds 80%, the opportunity for contact with water and oxygen to generate radicals decreases, which in turn hinders contact between particles and between particles and the conductive agent, and may result in a deterioration of the antibacterial effect. The hydrophobicity is preferably 45 to 75%, and particularly preferably 50 to 70%. The method for measuring the hydrophobicity will be specifically explained in the Examples.

[0025] [External additives] The external additives have functions such as improving powder flowability, improving triboelectric charging properties, heat resistance, improving long-term storage properties, improving cleaning properties, and controlling photoreceptor surface wear properties. As the external additive, for example, inorganic fine particles such as silica particles, titanium oxide particles, and alumina particles having an average primary particle diameter of 7 to 200 nm can be mentioned, and inorganic fine particles whose surfaces are made hydrophobic by surface treatment with a silane coupling agent, a titanium coupling agent, or silicone oil are more preferred because they reduce the decrease in electrical resistance and charge amount under high humidity conditions.Among these, surface-treated silica particles are particularly preferred.

[0026] <Surface-treated silica particles> Examples of surface-treated silica particles include silica particles that have been surface-treated with dimethyldichlorosilane (dimethylsilyl: DDS), hexamethyldisilazane (trimethylsilyl: HMDS), and silicone oil (dimethylpolysiloxane). Silica particles that have been surface-treated with DDS and silicone oil are preferred, and silica particles that have been surface-treated with silicone oil are particularly preferred because they have an excellent effect of improving fogging in high-temperature, high-humidity environments.

[0027] The silica particles (silica raw material) before surface treatment can be produced by known methods such as a dry method (gas phase method), a wet method, or a sol-gel method, with the gas phase method being preferred since it does not use a solvent. The gas phase method is a method for producing silica raw material by the vapor phase oxidation of a silicon halide compound. For example, a silica raw material called dry process (gas phase method) silica or fumed silica is produced by the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame (basic reaction: SiCl4 + 2H2 + O2 → SiO2 + 4HCl). The silica base material may also be a composite of silica and another metal oxide obtained by using a metal halide compound such as aluminum chloride or titanium chloride together with a silicon halide compound in the above-mentioned production process.

[0028] Silica particles surface-treated with silicone oil can be produced, for example, by directly mixing silica raw material treated with an organosilicon compound with silicone oil using a mixer such as a Henschel mixer; by diluting with an appropriate solvent such as normal hexane, spraying the silicone oil onto the silica raw material, and then heat-treating; or by dissolving or dispersing silicone oil in an appropriate solvent, adding and mixing the silica raw material, and then removing the solvent. The heat treatment after the spraying is preferably carried out in an inert gas atmosphere such as helium, nitrogen, or argon for safety reasons, and nitrogen gas is preferred in consideration of cost, etc. The heat treatment temperature is preferably 200 to 400°C.

[0029] Examples of the silicone oil include straight silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil; epoxy-modified silicone oil, carboxyl-modified silicone oil, carbinol-modified silicone oil, methacrylic-modified silicone oil, mercapto-modified silicone oil, phenol-modified silicone oil, one-end reactive modified silicone oil, heterofunctional group-modified silicone oil, polyether-modified silicone oil, methylstyryl-modified silicone oil, alkyl-modified silicone oil, higher fatty acid ester-modified silicone oil, hydrophilic special modified silicone oil, higher alkoxy-modified silicone oil, higher fatty acid-containing modified silicone oil, and fluorine-modified silicone oil. These may be used alone or in combination of two or more.

[0030] Examples of the organosilicon compound include hexamethyldisilazane, trimethylsilane, trimethylethoxysilane, isobutyltrimethoxysilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyldiethoxysilane, and hexamethyldisiloxane. These compounds may be used alone or in combination of two or more. Silicone oil-treated silica particles can be produced, for example, by the method described in Japanese Patent No. 6849352. The desired fine particles can be obtained by changing the average primary particle diameter of the base silica particles and the amount of silicone oil used. The specific surface area of ​​the silicone oil-treated silica particles as measured by the BET method is not particularly limited, but is preferably 30 to 400 m 2 / g.

[0031] Silica particles can be produced by known methods as described above, but commercially available silica particles, such as those used in the examples, manufactured by Nippon Aerosil Co., Ltd. under the product name RX-200 (both treated with hexamethyldisilazane) and those manufactured by Nippon Aerosil Co., Ltd. under the product names R974 and R976S (both treated with dimethoxydimethylsilane), can also be used.

[0032] <Average primary particle diameter> The silica particles preferably have an average primary particle size of 7 to 16 nm, which ensures uniform toner fluidity and toner surface coverage. If the average primary particle diameter of the silica particles is less than 7 nm, they may become embedded in the toner base particles, adhere too strongly, and the spacer effect may not be maintained. On the other hand, if the average primary particle diameter of the silica particles is more than 12 nm, the adhesion to the toner base particles may be weak, and the coating effect may not be obtained. Furthermore, if the average primary particle diameter of the silica particles is more than 16 nm, the amount of external additives must be increased to ensure the coating rate of the external additives, which is not preferable. The average primary particle size of the silica particles is more preferably 8 to 15 nm, and even more preferably 9 to 13 nm. The method for measuring the average primary particle diameter of the silica particles will be described in the Examples.

[0033] <External addition rate> The ratio of the external additive to the toner base particles is preferably 80 to 150% by mass. If the external additive content is less than 80% by mass, it may be difficult to improve the flowability, whereas if the external additive content exceeds 150% by mass, the fixability may decrease. The external addition ratio of the external additive is more preferably 85 to 140 mass %, and even more preferably 90 to 130 mass %.

[0034] [Conductive agent] In the toner of the present disclosure, the toner base particles preferably further contain a conductive agent (conductive substance). The introduction of a conductive agent increases the contact opportunities between titanium oxide particles and zinc oxide particles in the toner, increasing the transfer of electrons between the two particles, which in turn allows for more efficient release of metal ions and improves antibacterial performance.

[0035] <Material> The conductive agent is not particularly limited as long as it is a material that is conductive, increases the contact opportunity between titanium oxide particles and zinc oxide particles in the toner, does not adversely affect the charging performance of the toner, and does not inhibit the effects of the toner of the present disclosure, and examples thereof include carbon black and magnetite. In the present disclosure, the above-mentioned conductive agents can be used alone or in combination of two or more, and among the above-mentioned conductive agents, carbon black is particularly preferred. In black toner containing carbon black as a colorant, the carbon black is highly dispersed in the toner and is uniformly present inside the toner particles and on the surface of the toner, which also effectively increases the chances of contact between titanium oxide particles and zinc oxide particles.

[0036] <Volume average particle size> The conductive agent desirably has a particle size equivalent to that of titanium oxide particles and zinc oxide particles, and preferably has a volume average particle size of 10 to 1000 nm. If the volume average particle size is less than 10 nm, the particle size is too small to be highly dispersed in the toner, whereas if the volume average particle size is more than 1000 nm, the particle size is too large relative to the toner particle size, resulting in a large deviation. The volume average particle size is more preferably 15 to 800 nm, and particularly preferably 20 to 500 nm.

[0037] <Internal addition rate> In the toner of the present disclosure, the conductive agent is preferably contained in the toner base particles at an internal addition rate of 1 to 20% by mass. If the internal addition rate is less than 1% by mass, the effect of increasing the contact opportunity between titanium oxide particles and zinc oxide in the toner may not be fully exerted, whereas if the internal addition rate exceeds 20% by mass, conduction (percolation) may occur within the toner base particles, which may adversely affect the charging performance of the toner. The internal addition rate is more preferably 2 to 15 mass %, and particularly preferably 4 to 10 mass %. The amount of the conductive agent is about 1 to 25 parts by mass per 100 parts by mass of the binder resin described below, although this depends on the content of other components contained in the toner base particles.

[0038] (1) Toner The toner of the present disclosure is composed of at least toner base particles and externally added components that are externally added to the surfaces of the toner base particles.

[0039] [Toner base particles] The toner base particles contain at least a binder resin, a colorant, and a release agent, and may also contain the above-mentioned conductive agent, charge control agent, etc., as required.

[0040] <Binder resin> The binder resin may be a resin commonly used in the art, such as a polyester resin, a polystyrene resin such as a styrene-acrylic resin, a (meth)acrylic acid ester resin, a polyolefin resin, a polyurethane resin, or an epoxy resin, and may be used alone or in combination of two or more. Among these, polystyrene resins and polyester resins are preferred, and polyester resins are particularly preferred.

[0041] As the polystyrene-based resin, styrene-acrylic resin (styrene-acrylic copolymer resin) is preferred, and examples of styrene monomers that can be used as the resin raw material include styrene derivatives such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, and 2,4-dimethylstyrene. Examples of acrylic monomers include acrylic acid derivatives and methacrylic acid derivatives such as acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, phenyl methacrylate, and dimethylamino methacrylate. Furthermore, vinyl monomers such as maleic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid monophenyl ester, maleic acid monoallyl ester, and divinylbenzene may be used as resin raw materials.

[0042] Polyester resins are typically obtained by subjecting one or more selected from dihydric alcohol components and trihydric or higher polyhydric alcohol components to a condensation polymerization reaction, esterification, or transesterification reaction using a known method with one or more selected from dicarboxylic acids and trihydric or higher polycarboxylic acids. The conditions for the polycondensation reaction may be appropriately set depending on the reactivity of the monomer components, and the reaction may be terminated when the polymer has reached suitable physical properties. For example, the reaction temperature is about 170 to 250°C, and the reaction pressure is about 5 mmHg to atmospheric pressure.

[0043] Examples of the dihydric alcohol component include alkylene oxide adducts of bisphenol A such as polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(3.3)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene(2.0)-polyoxyethylene(2.0)-2,2-bis(4-hydroxyphenyl)propane, and polyoxypropylene(6)-2,2-bis(4-hydroxyphenyl)propane; ethylene glycol; Examples of suitable olefin copolymers include diols such as ethanol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; bisphenol A; propylene adducts of bisphenol A; ethylene adducts of bisphenol A; and hydrogenated bisphenol A.

[0044] Examples of trihydric or higher polyhydric alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose (cane sugar), 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene. In the toner of the present disclosure, the above dihydric alcohol components and trihydric or higher polyhydric alcohol components can be used alone or in combination of two or more.

[0045] Examples of dicarboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, n-dodecylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinic acid, and acid anhydrides or lower alkyl esters thereof.

[0046] Examples of trivalent or higher polyvalent carboxylic acids include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, and acid anhydrides or lower alkyl esters thereof. In the toner of the present disclosure, the above dicarboxylic acids and tricarboxylic or higher polycarboxylic acids may be used alone or in combination of two or more.

[0047] The polyester resin preferably has a mass average molecular weight in the range of 3,000 to 50,000. If the mass average molecular weight is less than 3,000, the release properties may be poor on the high temperature side of the fixable region (non-offset region). On the other hand, if the mass average molecular weight exceeds 50,000, the low temperature fixability may be poor. The polyester resin preferably has an acid value of 5 to 30 mgKOH / g. If the acid value is less than 5 mgKOH / g, the charging characteristics of the polyester resin may be reduced, and the charge control agent may be difficult to disperse in the polyester resin, which may adversely affect the charge buildup and charging stability during continuous use. On the other hand, if the acid value exceeds 30 mgKOH / g, the hygroscopicity may increase and the charging characteristics may become unstable.

[0048] <Coloring agent> As the colorant, various types and colors of organic and inorganic pigments and dyes commonly used in the art can be used, including, for example, black, white, yellow, orange, red, purple, blue and green colorants.

[0049] Examples of black colorants include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite, and magnetite. Carbon black is classified into channel black, roller black, disc black, gas furnace black, oil furnace black, thermal black, acetylene black, etc. depending on the production method, etc., and an appropriate carbon black can be selected from these according to the design properties of the toner to be obtained. Examples of white colorants include zinc oxide, titanium oxide, antimony white, and zinc sulfide.

[0050] Examples of yellow colorants include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake, CI pigment yellow 12, CI pigment yellow 13, CI pigment yellow 14, CI pigment yellow 15, CI pigment yellow 17, CI pigment yellow 74, CI pigment yellow 93, CI pigment yellow 94, CI pigment yellow 138, and CI pigment yellow 185.

[0051] Examples of orange colorants include red lead yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, induthrene brilliant orange RK, benzidine orange G, induthrene brilliant orange GK, CI pigment orange 31, and CI pigment orange 43.

[0052] Examples of red colorants include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, lithol red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B, CI pigment red 2, CI pigment red 3, CI pigment red 5, CI pigment red 6, CI pigment red 7, Examples of pigments include CI Pigment Red 15, CI Pigment Red 16, CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 139, CI Pigment Red 144, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 222, and CI Pigment Red 269.

[0053] Examples of purple colorants include manganese violet, fast violet B, and methyl violet lake.

[0054] Examples of blue colorants include Prussian blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, indanthrene blue BC, CI pigment blue 15, CI pigment blue 15:2, CI pigment blue 15:3, CI pigment blue 16, and CI pigment blue 60.

[0055] Examples of green colorants include chrome green, chromium oxide, pigment green B, mica light green lake, final yellow green G, and CI pigment green 7.

[0056] In the present disclosure, the above colorants can be used alone or in combination of two, and the combination can be of different colors or the same color. Two or more kinds of colorants may be used in the form of composite particles. The composite particles can be produced, for example, by adding an appropriate amount of water, a lower alcohol, etc. to two or more colorants, granulating the mixture in a general granulator such as a high-speed mill, and drying the granulated mixture. Furthermore, in order to disperse the colorant uniformly in the binder resin, it may be used in the form of a masterbatch. The composite particles and masterbatches are incorporated into the toner composition during dry blending.

[0057] The colorant is not particularly limited, but is preferably contained in the toner base particles at an internal addition rate of 2 to 10% by mass. If the internal addition rate of the colorant is less than 2% by mass, sufficient coloring power cannot be obtained, and the image density may be too low. On the other hand, if the internal addition rate exceeds 10% by mass, depending on the colorant, the charging performance of the toner may be affected, and the filler effect may increase the melt viscosity of the toner near the colorant, making it difficult to uniformly disperse the colorant in the toner, and the colorant may be easily unevenly distributed. The internal addition rate is more preferably 2.5 to 8 mass %, and even more preferably 3 to 7 mass %. The amount of colorant is about 2 to 15 parts by mass per 100 parts by mass of binder resin, although this depends on the content of other components contained in the toner base particles.

[0058] <Release agent> The release agent may be any release agent commonly used in the art, such as petroleum waxes such as paraffin wax, microcrystalline wax, and their derivatives; hydrocarbon synthetic waxes such as Fischer-Tropsch wax, polyolefin wax (polyethylene wax, polypropylene wax, etc.), low molecular weight polypropylene wax, polyolefin polymer wax (low molecular weight polyethylene wax, etc.), and their derivatives; plant-based waxes such as carnauba wax, rice wax, candelilla wax, and their derivatives, and Japan wax; animal-based waxes such as beeswax and spermaceti; oil-based synthetic waxes such as fatty acid amides and phenol fatty acid esters; long-chain carboxylic acids and their derivatives; long-chain alcohols and their derivatives; silicone polymers; higher fatty acids, etc. The above-mentioned derivatives include oxides, block copolymers of vinyl monomers and wax, and graft-modified products of vinyl monomers and wax. In the present disclosure, the above-mentioned release agents can be used alone or in combination of two or more.

[0059] The releasing agent is not particularly limited, but is preferably contained in the toner base particles at an internal addition rate of 1 to 10% by mass. If the internal addition rate of the release agent is less than 1% by mass, the release agent will not exude sufficiently onto the surface of the molten toner when the toner is fixed to the printed material, making it difficult for the toner to separate from the fixing roller and causing micro-offset, particularly at high temperatures. On the other hand, if it exceeds 10% by mass, the amount of release agent present near the toner surface will increase, and the release agent will melt and bleed out in an environment above the melting point of the release agent or the glass transition point of the toner, which may cause aggregation of toner particles. The internal addition rate is more preferably 2 to 9 mass %, and even more preferably 3 to 8 mass %. The amount of the release agent is about 1 to 13 parts by mass per 100 parts by mass of the binder resin, although this depends on the content ratio of other components contained in the toner base particles.

[0060] <Conductive agent> The conductive agent is as described above.

[0061] <Charge control agents (charge control agents)> The toner base particles of the present disclosure may be blended with a charge control agent, if necessary. Examples of the charge control agent include charge control agents commonly used in the art for controlling positive charge and negative charge. Examples of charge control agents for positive charge control include nigrosine dyes and derivatives thereof, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrine, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, triphenylmethane derivatives, guanidine salts, and amidine salts. Examples of charge control agents for negative charge control include oil-soluble dyes such as oil black and Spiron black, metal-containing azo compounds, azo complex dyes, metal naphthenate salts, metal complexes and metal salts of salicylic acid and its derivatives (metals include chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylate salts, and resin acid soaps.

[0062] The charge control agent is not particularly limited, but is preferably contained in the toner base particles at an internal addition rate of 0.1 to 5% by mass. If the internal addition rate of the charge control agent is less than 0.1% by mass, the amount of charge control agent added may be too small to have any effect on the charging performance of the toner, whereas if it exceeds 5% by mass, the amount of charge control agent added may be too large to have an adverse effect on the charging performance of the toner. The internal addition rate is more preferably 0.2 to 4 mass %, and even more preferably 0.5 to 3 mass %. The amount of the charge control agent is about 0.1 to 8 parts by mass per 100 parts by mass of the binder resin, although this depends on the content of other components contained in the toner base particles.

[0063] <Volume average particle diameter of toner base particles> The volume average particle diameter of the toner base particles is not particularly limited and can be set appropriately depending on the purpose, but the toner base particles preferably have a volume average particle diameter of 4 to 10 μm. If the volume average particle size is less than 4 μm, the particles are too small to be electrostatically positioned, which can lead to scattering and fogging, whereas if it exceeds 10 μm, the particles are too large and can adversely affect the resolution of fine lines and images. The volume average particle size is more preferably 5 to 9 μm, and even more preferably 5.5 to 7 μm. The coefficient of variation of the volume average particle size is not particularly limited, but is about 18 to 28%. The method for measuring the volume average particle diameter and the coefficient of variation of the toner base particles will be described in the Examples.

[0064] (2) Toner manufacturing method The toner of the present disclosure can be produced by a known method using a known device commonly used in the technical field. In the production process, toner base particles are produced, and external additives are added to the resulting toner base particles to obtain a toner. Examples of methods for producing toner base particles include dry methods such as pulverization, and wet methods such as suspension polymerization, emulsion aggregation, dispersion polymerization, solution suspension, and melt emulsification. Compared to wet methods, dry methods are preferred because they require fewer steps and require less equipment cost, and pulverization is particularly preferred. Below, the pulverization method for producing a toner is described by dividing it into individual steps. The conditions for each step may be appropriately set depending on the target material and the desired physical properties.

[0065] <Mixing (melting) process S1> In the kneading step S1, toner raw materials including, for example, a binder resin, a colorant, a release agent, and optionally a charge control agent are dry-mixed in a mixer, and then kneaded in a kneader to obtain a molten mixture. The kneading is performed by heating to a temperature equal to or higher than the softening point of the binder resin and lower than its thermal decomposition temperature. This melts or softens the binder resin, allowing the other toner raw materials to be dispersed in the binder resin. The specific heating temperature during kneading is preferably, for example, 80 to 200°C, and more preferably 100 to 180°C.

[0066] For mixing, known devices commonly used in the technical field can be used, for example, Henschel-type (airflow mixing) mixers such as Henschel Mixer (product name, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke and Engineering Co., Ltd.)), Super Mixer (product name, manufactured by Kawata Corporation), and Mechano Mill (product name, manufactured by Okada Seiko Co., Ltd.), as well as mixers such as Ang Mill (product name, manufactured by Hosokawa Micron Corporation), Hybridization System (product name, manufactured by Nara Machinery Works, Ltd.), and Cosmo System (product name, manufactured by Kawasaki Heavy Industries, Ltd.).

[0067] For melt-kneading, known devices commonly used in the relevant technical field, such as general kneaders such as twin-screw extruders, triple-roll mills, and lab blast mills, can be used. Examples of such kneaders include single- or twin-screw extruders such as TEM-100B (product name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, and PCM-30 (all product names, manufactured by Ikegai Corporation), and open-roll kneaders such as Kneadex (product name, manufactured by Mitsui Mining Co., Ltd.). Among these, open-roll kneaders are preferred, and the kneading process may be carried out using multiple kneaders.

[0068] <Crushing (cooling and grinding) process S2> In the pulverization step S2, the molten kneaded product obtained in the kneading step S1 is cooled and solidified, and the solidified product is coarsely pulverized to obtain a coarsely pulverized product, which is further finely pulverized to obtain a finely pulverized product. For cooling, a known device commonly used in the art, such as a cooling belt, can be used. For the coarse pulverization, known devices commonly used in the art, such as a speed mill with a screen, a hammer mill, or a cutter mill, can be used. For the fine pulverization, known devices commonly used in the art, such as a jet pulverizer that pulverizes using a supersonic jet stream, or an impact pulverizer that pulverizes a solidified material by introducing it into the space formed between a rotor and a stator (liner) that rotate at high speed, can be used. It is also possible to collect the finely pulverized particles having a desired volume average particle size obtained in the pulverization step S2 as toner base particles without carrying out the following classification step S3.

[0069] <Classification process S3> In the classification step S3, the finely pulverized product obtained in the pulverization step S2 is classified using a classifier to obtain toner base particles having a desired volume average particle size. For classification, a known device commonly used in the art, for example, a classifier capable of removing over-pulverized toner particles by centrifugal force and wind force, such as a rotary wind classifier (rotary wind classifier), can be used.

[0070] <External addition process S4> In the external addition step S4, the toner base particles obtained in the classification step S3 are mixed with the external additives described in the <External Additives> section using a mixer to adhere the external additives to the surfaces of the toner base particles, thereby obtaining toner (external additive toner). For mixing, a known device commonly used in the art, such as the mixing device described in the kneading step S1, can be used. The toner of the present disclosure can be used as a single-component developer as it is, or can be mixed with a carrier to be used as a two-component developer. When used as a single-component developer, the toner is transported by frictionally charging it with a developing sleeve using a blade and a fur brush, causing the toner to adhere to the sleeve, and image formation is performed.

[0071] (3) Two-component developer The two-component developer of the present disclosure is characterized by containing the toner of the present disclosure and a carrier. [Career] As the carrier, carriers commonly used in the relevant technical field can be used, and examples thereof include simple or composite ferrite particles made of iron, copper, zinc, nickel, cobalt, manganese, chromium, etc., resin-coated carriers in which the surfaces of carrier core particles are coated with a known coating material, and resin-dispersed carriers in which magnetic particles are dispersed in a resin.

[0072] As the coating material, materials commonly used in the technical field can be used, and examples thereof include polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester-based resin, metal compound of di-tert-butylsalicylic acid, styrene-based resin, acrylic resin, polyamide, polyvinyl butyral, nigrosine, aminoacrylate resin, basic dye, lake of basic dye, silica fine powder, alumina fine powder, etc. The resin used in the resin dispersion type carrier is not particularly limited, but examples thereof include styrene acrylic resin, polyester resin, fluorine resin, and phenol resin. The above-mentioned coating materials and resins used in the resin dispersion type carrier can be used either alone or in combination of two or more, and are preferably selected according to the toner components.

[0073] The shape of the carrier is not particularly limited, but spherical and flat shapes are preferred. The average particle size of the carrier is not particularly limited, but in consideration of achieving high image quality, it is preferably 30 to 80 μm, and more preferably 40 to 60 μm.

[0074] The volume resistivity of the carrier is determined by dividing the carrier particles into particles with a cross-sectional area of ​​0.50 cm 2 After placing it in a container and tapping, the particles packed in the container are charged with 1 kg / cm 2The volume resistivity is the value obtained from the current value when a load of 1.0×10 is applied and a voltage is applied that generates an electric field of 1000 V / cm between the load and the bottom electrode. If the volume resistivity is low, the carrier will be charged when a bias voltage is applied to the developing sleeve, and the carrier particles will be more likely to adhere to the photoreceptor. Also, breakdown of the bias voltage will be more likely to occur. The preferred volume resistivity of the carrier is 1.0×10 9 ~1.0×10 13 (Ω·cm).

[0075] The carrier's magnetization strength (maximum magnetization) is preferably 10 to 60 emu / g, more preferably 15 to 40 emu / g. Under the magnetic flux density conditions of a typical developing roller, if the magnetization strength is less than 10 emu / g, the magnetic binding force will not work, which may cause carrier scattering. Furthermore, if the magnetization strength exceeds 60 emu / g, in non-contact development, the carrier will become too stiff, making it difficult to maintain a non-contact state between the image carrier and the toner, and in contact development, sweeping marks may easily appear in the toner image.

[0076] The blending ratio of toner and carrier in a two-component developer is not particularly limited and can be appropriately selected depending on the type of toner and carrier. For example, when mixed with a resin-coated carrier (density 5 to 8 g / cm2), the toner content should be 2 to 30% by mass, preferably 2 to 20% by mass, of the total developer weight. In addition, the coverage of the carrier by the toner is preferably 40 to 80% by mass.

[0077] (4) Toner applications The toner of the present disclosure can be fixed on a recording medium such as paper or resin to produce a printed matter having antibacterial properties. Furthermore, in order to maximize the antibacterial properties of the toner of the present disclosure, it is preferable to form an antibacterial sheet (film) by solid printing on the entire surface of a recording medium (antibacterial coating). When the resin material of the binder resin constituting the toner of the present disclosure is poorly compatible with the resin material constituting the recording medium (resin sheet), for example, when a polyester resin (PES) and a polyethylene terephthalate resin (PET) are used in combination, the surface of the recording medium may be roughened beforehand, and then the toner of the present disclosure may be fixed. Alternatively, it is also effective to mix a polyethylene terephthalate resin (PET) with the main resin of the toner to increase the compatibility between the toner and the recording medium (resin sheet). [Example]

[0078] The toner of the present disclosure and the two-component developer containing the toner will be specifically described below using examples and comparative examples, but the present invention is not limited to these examples as long as they do not depart from the gist of the present disclosure. In the examples and comparative examples, the materials used, the toner obtained, and the two-component developer containing the toner were measured for physical properties by the following methods.

[0079] (1) Volume average particle size of toner base particles and its coefficient of variation 20 mg of sample and 1 ml of sodium alkyl ether sulfate were added to 50 ml of electrolyte (Beckman Coulter, product name: ISOTON-II), and the mixture was dispersed using an ultrasonic disperser (SMT Corporation, model: UH-50) at a frequency of 20 kHz for 3 minutes to obtain a measurement sample. The resulting measurement sample was measured using a particle size distribution analyzer (Beckman Coulter, model: Multisizer4e) under conditions of an aperture diameter of 100 μm and a particle count of 50,000, and the volume average particle size and its coefficient of variation were determined from the volume particle size distribution of the sample particles.

[0080] (2) Average primary particle size of titanium oxide particles and zinc oxide particles SEM images (10,000 times magnification) were taken of titanium oxide particles and zinc oxide particles from 10 different fields of view, and 20 particles were randomly selected from each. The long and short axes of each particle were calculated by image analysis. The average of the long and short axes was taken as the average primary particle diameter. 2 and 3 are SEM images of the titanium oxide particles and zinc oxide particles used in Example 1, respectively.

[0081] (3) Hydrophobicity of titanium oxide particles and zinc oxide particles 1.0 g of titanium oxide or zinc oxide particles as a measurement sample and 100 mL of ion-exchanged water W are placed in a 500 mL beaker and stirred with a magnetic stirrer. Methanol is then dripped from the top of the beaker using a burette, and the amount of methanol dripped M (mL) is measured until all of the measurement sample on the water surface has dispersed into the solution and disappeared. The hydrophobicity rate is calculated from the obtained results using the following formula. Hydrophobicity rate (%) = M / (M+W) x 100

[0082] (4) Adhesion strength of titanium oxide particles and zinc oxide particles (a) 2.0 g of toner is added to 40 ml of a 0.2% by mass aqueous solution of Triton (polyoxyethylene octylphenyl ether) and stirred with a stirrer for 1 minute to allow the toner to penetrate. (b) The resulting aqueous solution is irradiated with ultrasonic waves at an output of 40 μA for 4 minutes using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., model: US-300T) to remove the external additives from the toner. (c) After the ultrasonic irradiation, the aqueous solution is left to stand for 3 hours, and the toner and the released external additives are separated. (d) After removing the supernatant, add approximately 50 ml of pure water to the precipitate and stir with a stirrer for 5 minutes. (e) The solution is subjected to suction filtration using a membrane filter with a pore size of 1 μm (manufactured by Advantec Co., Ltd.). (f) The toner remaining on the filter is vacuum dried for 24 hours in a desiccator containing silica gel. (g) Using an X-ray fluorescence analyzer (Rigaku Corporation, Model: ZSX Primus II), the intensity of elements (Ti, Zn) in the external additives of 1 g of toner is analyzed before and after ultrasonic treatment under the following conditions. 1 g of toner is pelletized to prepare a measurement sample. X-ray source target: Rh Voltage and current applied to the X-ray source: 40 kV, 50 mA Optical crystal: LiF (target: Ti) or pentaerythritol (PET, target: Zn) Detectors: scintillation counters and photocounters Spectroscopic scanning: skip-scan method PHA range: 100-300, 0.05 degrees per step (h) Calculate the adhesive strength of the external additive using the following formula. Titanium oxide adhesion strength (%) = [(fluorescent X-ray intensity of Ti element after treatment) / (fluorescent X-ray intensity of Ti element before treatment)] × 100 Zinc oxide adhesion strength (%) = [(fluorescent X-ray intensity of Zn element after treatment) / (fluorescent X-ray intensity of Zn element before treatment)] x 100

[0083] (5) Average primary particle size of silica particles The average primary particle diameter of the silica particles is measured twice using a dynamic light scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., model: Nanotrac Wave Series), and the average value is taken as the average primary particle diameter (μm) of the silica particles. The measurement conditions are a measurement time of 30 seconds, a sample particle refractive index of 1.49, and water as the dispersion medium, with a dispersion medium refractive index of 1.33. The volumetric particle size distribution of the measurement sample is measured, and the particle size at which the cumulative volume from the small particle size side in the cumulative volume distribution becomes 50% is calculated from the measurement results as the average primary particle size (μm) of the silica particles.

[0084] Titanium oxide microparticles and zinc oxide microparticles having the desired average primary particle diameter were prepared in advance, and then hydrophobized titanium oxide microparticles and zinc oxide microparticles were prepared by hydrophobization treatment to achieve the desired hydrophobicity ratio.

[0085] (Production Example T1) Preparation of titanium oxide microparticles 1 (1) 900 mL of 13.3N hydrochloric acid solution was added to 150 g of barium titanate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the mixture was stirred for 96 hours, after which the undissolved matter was separated by filtration. (2) The resulting solution, from which the undissolved matter was filtered, was diluted five times with pure water, heated to 80°C, and allowed to react for 12 hours while maintaining that temperature, yielding a milky white liquid in which titanium oxide was dispersed. (3) Ammonia water was added to the obtained titanium oxide dispersion to adjust the pH to 4.5 to 6.0, and then the precipitated titanium oxide was separated by filtration. (4) The separated titanium oxide was washed several times with pure water and then dried at 120° C. to obtain titanium oxide microparticles 1 having an average primary particle diameter of 87.6 nm.

[0086] (Production Example T2) Preparation of titanium oxide microparticles 2 Titanium oxide fine particles 2 having an average primary particle diameter of 69.5 nm were obtained in the same manner as in Production Example T1, except that the concentration of the hydrochloric acid aqueous solution was 13.0 normal (13.0N).

[0087] (Production Example T3) Preparation of titanium oxide microparticles 3 Titanium oxide fine particles 3 having an average primary particle diameter of 76.1 nm were obtained in the same manner as in Production Example T1, except that the concentration of the hydrochloric acid aqueous solution was 13.1 normal (13.1N).

[0088] (Production Example T4) Preparation of Titanium Oxide Microparticles 4 Titanium oxide fine particles 4 having an average primary particle diameter of 81.4 nm were obtained in the same manner as in Production Example T1, except that the concentration of the hydrochloric acid aqueous solution was 13.2 normal (13.2N).

[0089] (Production Example T5) Preparation of Titanium Oxide Microparticles 5 Titanium oxide fine particles 5 having an average primary particle diameter of 192.4 nm were obtained in the same manner as in Production Example T1, except that the concentration of the hydrochloric acid aqueous solution was 14.5 normal (14.5N).

[0090] (Production Example T6) Preparation of Titanium Oxide Microparticles 6 Titanium oxide microparticles 6 having an average primary particle diameter of 211.4 nm were obtained in the same manner as in Production Example T1, except that the concentration of the hydrochloric acid aqueous solution was 14.6 normal (14.6N).

[0091] (Production Example TH1) Preparation of Hydrophobized Titanium Oxide Microparticles 1 (1) 1000 g of titanium oxide microparticles 1 (average particle size 87.6 nm) were placed in a 20 L mixer (Heater Henschel Mixer, manufactured by Nippon Coke Co., Ltd., model: MH-20), and a mixture of 2800 g of methylhydrogenpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KF9901, hydrogen dimethicone) and 100 g of isopropyl alcohol (IPA) was added dropwise with low-speed stirring using N2 gas as seal air. (2) After the dropping, the mixture was stirred at low speed for 10 minutes, and then the mixed powder was taken out and dried in a hot air dryer at 40°C for 3 hours, and then further dried at 130°C for 5 hours. (3) The obtained powder was pulverized in a pulverizer (V Turbo, manufactured by Freund Turbo Corporation) to obtain hydrophobic treated titanium oxide fine particles 1 having a hydrophobicity rate of 67%.

[0092] (Production Example TH2) Preparation of Hydrophobized Titanium Oxide Microparticles 2 Hydrophobized titanium oxide particles 2 with a hydrophobicity of 70% were obtained in the same manner as in Production Example TH1, except that titanium oxide particles 1 were changed to titanium oxide particles 2 and the amount of methyl hydrogen polysiloxane was changed from 2800 g to 3700 g.

[0093] (Production Example TH3) Preparation of Hydrophobized Titanium Oxide Microparticles 3 Hydrophobized titanium oxide particles 3 with a hydrophobicity of 79% were obtained in the same manner as in Production Example TH1, except that titanium oxide particles 1 were changed to titanium oxide particles 3 and the amount of methylhydrogenpolysiloxane was changed from 2800 g to 3800 g.

[0094] (Production Example TH4) Preparation of Hydrophobized Titanium Oxide Microparticles 4 Hydrophobized titanium oxide particles 4 with a hydrophobicity of 90% were obtained in the same manner as in Production Example TH1, except that titanium oxide particles 1 were changed to titanium oxide particles 4 and the amount of methylhydrogenpolysiloxane was changed from 2800 g to 4050 g.

[0095] (Production Example TH5) Preparation of Hydrophobized Titanium Oxide Microparticles 5 Hydrophobized titanium oxide fine particles 5 having a hydrophobicity rate of 35% were obtained in the same manner as in Production Example TH1, except that the amount of methylhydrogenpolysiloxane was changed from 2800 g to 1460 g.

[0096] (Production Example TH6) Preparation of Hydrophobized Titanium Oxide Microparticles 6 Hydrophobized titanium oxide particles 6 with a hydrophobicity of 61% were obtained in the same manner as in Production Example TH1, except that titanium oxide particles 1 were changed to titanium oxide particles 5 and the amount of methylhydrogenpolysiloxane was changed from 2800 g to 1160 g.

[0097] (Production Example TH7) Preparation of Hydrophobized Titanium Oxide Microparticles 7 Hydrophobized titanium oxide particles 7 with a hydrophobicity rate of 65% were obtained in the same manner as in Production Example TH1, except that titanium oxide particles 1 were changed to titanium oxide particles 6 and the amount of methylhydrogenpolysiloxane was changed from 2800 g to 1140 g.

[0098] (Production Example Z1) Preparation of zinc oxide microparticles 1 (1) 100 g of zinc oxide (primary particle diameter 20 nm, manufactured by Sakai Chemical Industry Co., Ltd., product name: FINEX-50) as seed particles was redissolved in 1500 ml of a zinc acetate aqueous solution prepared by dissolving 154.22 g of zinc acetate dihydrate (manufactured by Fujifilm Wako Pure Chemical Industries Co., Ltd.) in pure water to prepare a slurry. (2) The resulting slurry was heated to 70°C over 45 minutes while stirring, and then aged at 70°C for 3 hours with continued stirring. (3) The obtained aqueous zinc acetate solution was filtered and washed with pure water to obtain a solid. (4) The obtained solid was dispersed in 3 L of pure water, and the temperature was raised again to 70°C over 45 minutes while stirring, and the mixture was heated and washed at 70°C for 30 minutes while stirring. (5) The obtained aqueous zinc acetate solution was filtered, washed with pure water, and dried at 110° C. for 12 hours to obtain zinc oxide microparticles 1 having an average primary particle diameter of 102.9 nm.

[0099] (Production Example Z2) Preparation of zinc oxide microparticles 2 Zinc oxide microparticles 2 having an average primary particle diameter of 78.6 nm were obtained in the same manner as in Production Example Z1, except that the amount of zinc acetate dihydrate was changed from 154.22 g to 123.54 g.

[0100] (Production Example Z3) Preparation of zinc oxide microparticles 3 Zinc oxide microparticles 3 having an average primary particle diameter of 88.2 nm were obtained in the same manner as in Production Example Z1, except that the amount of zinc acetate dihydrate was changed from 154.22 g to 135.66 g.

[0101] (Production Example Z4) Preparation of zinc oxide microparticles 4 Zinc oxide microparticles 4 having an average primary particle diameter of 291.1 nm were obtained in the same manner as in Production Example Z1, except that the amount of zinc acetate dihydrate was changed from 154.22 g to 391.87 g.

[0102] (Production Example Z5) Preparation of Zinc Oxide Microparticles 5 Zinc oxide microparticles 5 having an average primary particle diameter of 323.3 nm were obtained in the same manner as in Production Example Z1, except that the amount of zinc acetate dihydrate was changed from 154.22 g to 432.53 g.

[0103] (Production Example ZH1) Preparation of Hydrophobized Zinc Oxide Microparticles 1 (1) 3000 g of zinc oxide microparticles 1 (average particle size 102.9 nm) were placed in a 20 L mixer (Heater Henschel Mixer, manufactured by Nippon Coke Co., Ltd., Model: MH-20), and a mixture of 910 g of aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBE903) and 100 g of isopropyl alcohol (IPA) was added dropwise under slow stirring using N2 gas as seal air. (2) After the dropping, the mixture was stirred at low speed for 10 minutes, and then the mixed powder was taken out and dried in a hot air dryer at 40°C for 3 hours, and then further dried at 130°C for 5 hours. (3) The obtained powder was pulverized in a pulverizer (V Turbo, manufactured by Freund Turbo Corporation) to obtain hydrophobic treated zinc oxide fine particles 1 having a hydrophobicity rate of 71%.

[0104] (Production Example ZH2) Preparation of Hydrophobized Zinc Oxide Microparticles 2 Hydrophobized zinc oxide particles 2 with a hydrophobicity rate of 76% were obtained in the same manner as in Production Example ZH1, except that zinc oxide particles 1 were changed to zinc oxide particles 2 and the amount of aminopropyltriethoxysilane was changed from 910 g to 1270 g.

[0105] (Production Example ZH3) Preparation of Hydrophobized Zinc Oxide Microparticles 3 Hydrophobized zinc oxide particles 3 with a hydrophobicity rate of 75% were obtained in the same manner as in Production Example ZH1, except that zinc oxide particles 1 were changed to zinc oxide particles 3 and the amount of aminopropyltriethoxysilane was changed from 910 g to 1,120 g.

[0106] (Production Example ZH4) Preparation of Hydrophobized Zinc Oxide Microparticles 4 Hydrophobized zinc oxide fine particles 4 having a hydrophobicity rate of 35% were obtained in the same manner as in Production Example ZH1, except that the amount of aminopropyltriethoxysilane was changed from 910 g to 450 g.

[0107] (Production Example ZH5) Preparation of Hydrophobized Zinc Oxide Microparticles 5 Hydrophobized zinc oxide fine particles 5 having a hydrophobicity rate of 90% were obtained in the same manner as in Production Example ZH1, except that the amount of aminopropyltriethoxysilane was changed from 910 g to 1,150 g.

[0108] (Production Example ZH6) Preparation of Hydrophobized Zinc Oxide Microparticles 6 Hydrophobized zinc oxide particles 6 with a hydrophobicity rate of 64% were obtained in the same manner as in Production Example ZH1, except that zinc oxide particles 1 were changed to zinc oxide particles 4 and aminopropyltriethoxysilane was changed from 910 g to 290 g.

[0109] (Production Example ZH7) Preparation of Hydrophobized Zinc Oxide Microparticles 7 Hydrophobized zinc oxide particles 7 with a hydrophobicity rate of 64% were obtained in the same manner as in Production Example ZH1, except that zinc oxide particles 1 were changed to zinc oxide particles 5 and the amount of aminopropyltriethoxysilane was changed from 910 g to 260 g.

[0110] Example 1 [Mixing (melting) process] The following toner raw materials were introduced into a 20 L air flow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke & Engineering Co., Ltd.), model: FM20C) and premixed at a rotation speed of 1500 rpm for 3 minutes to obtain a mixture. Binder resin: Polyester resin (glass transition point 52°C, softening temperature 105°C) 100 parts by mass (86.2% by mass of toner base particles) Colorant: Cyan (CI Pigment Blue 15:3, manufactured by DIC Corporation, product name: FASTOGEN (registered trademark) BLUE GR-6LK) 10 parts by mass (8.6% by mass of toner base particles) Charge control agent (Hodogaya Chemical Co., Ltd., product name: TRH) 2 parts by mass (1.7% by mass of toner base particles) Release agent: Carnauba wax (manufactured by Towa Kasei, product name: Carnauba Wax TOWAX-131) 4 parts by mass (3.5% by mass of toner base particles) The obtained mixture was melt-kneaded using a twin-screw extruder (manufactured by Ikegai Corporation, model: PCM-30) under conditions of a cylinder setting temperature of 110°C, a barrel rotation speed of 150 rpm, and a raw material supply rate of 15 kg / hour, to obtain approximately 4 kg of molten kneaded product.

[0111] [Crushing (cooling crushing) process] The resulting molten mixture was cooled and solidified on a cooling belt, and then coarsely pulverized using a power mill (manufactured by Dalton Co., Ltd., model: P-3) equipped with a φ2 mm screen to obtain a coarsely pulverized product with a particle size of approximately 2 mm. The obtained coarsely crushed product was finely crushed using a jet crusher (manufactured by Nippon Pneumatic Mfg. Co., Ltd., model: IDS-2) to obtain a finely crushed product with a particle size of about 6.7 μm.

[0112] [Classification process] The resulting finely pulverized product was classified using an elbow jet classifier (manufactured by Nittetsu Mining Co., Ltd., model: EJ-LABO) to obtain approximately 1 kg of unadded toner base particles with a volume average particle diameter of 7.0 μm (coefficient of variation: 23%).

[0113] [External addition process] 100 parts by mass of the obtained toner base particles, 1.3 parts by mass (external addition rate 1.3%) of silica particles (average primary particle diameter 12 nm, hexamethyldisilazane-treated, manufactured by Nippon Aerosil Co., Ltd., product name: RX200) as an external additive, and 5.0 parts by mass (external addition rate 5.0%) of hydrophobic treated titanium oxide microparticles 1 (average primary particle diameter 87.6 nm, hydrophobicity rate: 67%) as external additives and 5.0 parts by mass (external addition rate 5.0%) of hydrophobic treated zinc oxide microparticles 1 (average primary particle diameter 102.9 nm, hydrophobicity rate: 71%) as external additives were added to an air flow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke and Engineering Co., Ltd.), model: FM20C), and mixed for 1 minute with the peripheral speed at the outermost circumference of the stirring blade tip set to 40 m / s to obtain approximately 980 g of externally added toner (volume average particle diameter 7.0 μm, coefficient of variation 23%). FIG. 1 is an SEM image of the toner containing the external additives obtained in Example 1.

[0114] [Preparation of two-component developer] The obtained externally added toner and coated carrier (manufactured by Sharp Corporation, name: genuine carrier for MX-6151) were put into a V-type mixer (manufactured by Tokuju Kogyosho Co., Ltd., model: V-5) so that the toner concentration was 7.5% by mass, and mixed for 20 minutes to obtain approximately 5 kg of two-component developer.

[0115] [Preparation of test sheets] The obtained two-component developer was placed in the developing tank of a multifunction printer (Model: MX-6151, manufactured by Sharp Corporation), and a solid image of an 80 mm x 80 mm patch was printed on an OHP sheet to prepare test sheet 1 for antibacterial evaluation.

[0116] Example 2 Toner 2 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobized titanium oxide microparticles 1 was changed from 5.0% by mass to 3.3% by mass, and the external addition rate of hydrophobized zinc oxide microparticles 1 was changed from 5.0% by mass to 6.7% by mass, and test sheet 2 was produced.

[0117] Example 3 Toner 3 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobized titanium oxide microparticles 1 was changed from 5.0% by mass to 6.7% by mass, and the external addition rate of hydrophobized zinc oxide microparticles 1 was changed from 5.0% by mass to 3.3% by mass, and test sheet 3 was produced.

[0118] Example 4 Toner 4 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobized titanium oxide microparticles 1 was changed from 5.0% by mass to 3.5% by mass, and the external addition rate of hydrophobized zinc oxide microparticles 1 was changed from 5.0% by mass to 3.5% by mass, and test sheet 4 was produced.

[0119] Example 5 Toner 5 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobized titanium oxide microparticles 1 was changed from 5.0% by mass to 6.0% by mass, and the external addition rate of hydrophobized zinc oxide microparticles 1 was changed from 5.0% by mass to 6.0% by mass, and test sheet 5 was produced.

[0120] Example 6 Toner 6 was prepared in the same manner as in Example 1, except that hydrophobic treated titanium oxide particles 3 (average primary particle diameter 76.1 nm, hydrophobicity rate 79%) were used instead of hydrophobic treated titanium oxide particles 1 in the toner external addition process, and test sheet 6 was produced.

[0121] Example 7 Toner 7 was prepared in the same manner as in Example 1, except that hydrophobic treated zinc oxide particles 3 (average primary particle diameter 88.2 nm, hydrophobicity rate 75%) were used instead of hydrophobic treated zinc oxide particles 1 in the toner external addition process, and test sheet 7 was produced.

[0122] Example 8 Toner 8 was prepared in the same manner as in Example 1, except that hydrophobic treated titanium oxide particles 6 (average primary particle diameter 192.4 nm, hydrophobicity rate 61%) were used instead of hydrophobic treated titanium oxide particles 1 in the toner external addition process, and test sheet 8 was produced.

[0123] Example 9 Toner 9 was prepared in the same manner as in Example 1, except that hydrophobic treated zinc oxide particles 6 (average primary particle diameter 291.1 nm, hydrophobicity rate: 64%) were used instead of hydrophobic treated zinc oxide particles 1 in the toner external addition process, and test sheet 9 was produced.

[0124] Example 10 Toner 10 was prepared in the same manner as in Example 1, except that in the toner external addition step, the external addition rate of hydrophobic silica fine particles was changed from 1.3% by mass to 4.5% by mass, and test sheet 10 was produced.

[0125] Example 11 Toner 11 was prepared in the same manner as in Example 1, except that in the toner external addition step, the external addition rate of hydrophobic silica fine particles was changed from 1.3% by mass to 0.4% by mass, and test sheet 11 was produced.

[0126] Example 12 Toner 12 was prepared in the same manner as in Example 1, except that in the toner external addition process, the outermost peripheral speed of the stirring blade tip of the Henschel mixer was set from 40 m / s to 20 m / s, and test sheet 12 was produced.

[0127] Example 13 In the toner base particle preparation process, carbon black (manufactured by Mitsubishi Chemical Corporation, product name: MA-100) with an average primary particle diameter of 20 nm was used instead of cyan as the colorant, and the amount added was 8.0 parts by mass (internal addition rate 7.0 mass%). Except for this, the same procedure as in Example 1 was repeated to obtain unadded toner base particles with a volume average particle diameter of 7.0 μm (coefficient of variation 24%), prepare toner 13, and produce test sheet 13.

[0128] Example 14 In the toner base particle preparation process, 0.5 parts by mass (internal addition rate: 0.43 mass%) of carbon black (manufactured by Mitsubishi Chemical Corporation, product name: MA-100) with an average primary particle diameter of 20 nm was additionally added in addition to cyan as a colorant. The same procedure as in Example 1 was repeated to obtain unadded toner base particles with a volume average particle diameter of 7.0 μm (coefficient of variation: 22%), prepare toner 14, and produce test sheet 14.

[0129] Example 15 In the toner base particle preparation process, the same procedure as in Example 13 was repeated except that the amount of carbon black added was changed from 8.0 parts by mass to 12.0 parts by mass (internal addition rate 10.2% by mass), to obtain unadded toner base particles with a volume average particle diameter of 7.0 μm (coefficient of variation 21%), prepare toner 15, and produce test sheet 15.

[0130] Example 16 In the toner base particle preparation process, the same procedure as in Example 13 was repeated except that carbon black with an average primary particle diameter of 8 nm (manufactured by Mitsubishi Chemical Corporation, product name: #2650) was used, and unadded toner base particles with a volume average particle diameter of 7.0 μm (coefficient of variation: 23%) were obtained, toner 16 was prepared, and test sheet 16 was produced.

[0131] Example 17 In the toner base particle preparation process, unadded toner base particles having a volume average particle diameter of 7.0 μm (coefficient of variation: 24%) were obtained in the same manner as in Example 13, except that carbon black 17 having an average primary particle diameter of 1200 nm, which had been produced in advance as described below, was used, toner 17 was prepared, and test sheet 17 was produced.

[0132] <Production of Carbon Black 17> (1) 30.0 parts by mass of Ester Gum (manufactured by Arakawa Chemical Industries, Ltd., product name: Ester Gum H) and 0.21 parts by mass of sodium hydroxide (a neutralization amount) were added to 70.0 parts by mass of pure water, heated to 80°C with stirring, and then allowed to react for 1 hour with stirring to prepare a rosin soap liquid with a rosin content of approximately 30%. (2) 40.0 parts by mass of carbon black (manufactured by Mitsubishi Chemical Corporation, carbon black, product name: #45, average primary particle size 24 nm, pH 8.0), 40.0 parts by mass of the obtained rosin soap liquid, 3.0 parts by mass of a surfactant and antifoaming agent (manufactured by Nissin Chemical Industry Co., Ltd., product name: Surfynol 104), and 70.0 parts by mass of water were charged into a paint conditioner containing glass beads, which serves as a disperser, and the mixture was vibrated for 90 minutes to finely disperse the carbon black. (3) The obtained concentrated dispersion was transferred to a Disper (manufactured by Primix Corporation, model: Homo Disper 2.5), and water was added so that the carbon black content was 5%, followed by stirring for 60 minutes to obtain a uniform dispersion. (4) Next, 105 parts by mass of a 5% aqueous solution of calcium chloride dihydrate was added, and stirring was continued for another 60 minutes. (5) Thereafter, the dispersion was heated to a temperature of 80°C and aged for 10 minutes. (6) The carbon black was filtered out from the resulting dispersion, washed with water, and then dried at 70°C for 24 hours. Coarse particles that had aggregated during drying were pulverized in a sample mill to obtain carbon black powder with an average particle size of 1,200 nm.

[0133] Example 18 Carbon black 18 having an average primary particle diameter of 800 nm was prepared in the same manner as in Example 13, except that in step (4) of the production method for carbon black 17, the amount of 5% aqueous calcium chloride dihydrate solution was changed from 105 parts by mass to 70 parts by mass. Unadded toner base particles having a volume average particle diameter of 7.0 μm (coefficient of variation: 24%) were obtained, toner 18 was prepared, and test sheet 18 was produced in the same manner as in Example 13, except that carbon black 18 having an average primary particle diameter of 800 nm was used instead of carbon black 17. Example 19 Toner 18 was prepared in the same manner as in Example 1, except that hydrophobic treated titanium oxide microparticles 5 (average primary particle diameter 102.9 nm, hydrophobicity: 35%) and hydrophobic treated zinc oxide microparticles 4 (average primary particle diameter 88.2 nm, hydrophobicity: 35%) were used in the toner external addition process, and test sheet 19 was produced.

[0134] Example 20 Toner 20 was prepared in the same manner as in Example 1, except that hydrophobic treated titanium oxide microparticles 4 (average primary particle diameter 81.4 nm, hydrophobicity 90%) and hydrophobic treated zinc oxide microparticles 5 (average primary particle diameter 102.9 nm, hydrophobicity 90%) were used in the toner external addition process, and test sheet 20 was produced.

[0135] (Comparative Example 1) Toner C1 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobic treated titanium oxide microparticles 1 was changed from 5.0% by mass to 10% by mass, and hydrophobic treated zinc oxide microparticles 1 were not used, and test sheet C1 was produced.

[0136] (Comparative Example 2) Toner C2 was prepared in the same manner as in Example 1, except that in the toner external addition process, hydrophobic treated titanium oxide microparticles 1 were not used and the external addition rate of hydrophobic treated zinc oxide microparticles 1 was changed from 5.0% by mass to 10% by mass, and test sheet C2 was produced.

[0137] (Comparative Example 3) Toner C3 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobic treated titanium oxide microparticles 1 was changed from 5.0% by mass to 3.0% by mass, and the external addition rate of hydrophobic treated zinc oxide microparticles 1 was changed from 5.0% by mass to 7.0% by mass, and test sheet C3 was produced.

[0138] Comparative Example 4 Toner C4 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobic treated titanium oxide microparticles 1 was changed from 5.0% by mass to 7.0% by mass, and the external addition rate of hydrophobic treated zinc oxide microparticles 1 was changed from 5.0% by mass to 3.0% by mass, and test sheet C4 was produced.

[0139] (Comparative Example 5) Toner C5 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobic treated titanium oxide microparticles 1 was changed from 5.0% by mass to 3.0% by mass, and the external addition rate of hydrophobic treated zinc oxide microparticles 1 was changed from 5.0% by mass to 3.0% by mass, and test sheet C5 was produced.

[0140] (Comparative Example 6) Toner C6 was prepared in the same manner as in Example 1, except that in the toner external addition process, the external addition rate of hydrophobic treated titanium oxide microparticles 1 was changed from 5.0% by mass to 7.0% by mass, and the external addition rate of hydrophobic treated zinc oxide microparticles 1 was changed from 5.0% by mass to 7.0% by mass, and test sheet C6 was produced.

[0141] (Comparative Example 7) Toner C7 was prepared in the same manner as in Example 1, except that hydrophobic treated titanium oxide particles 2 (average primary particle diameter 69.5 nm, hydrophobicity rate 70%) were used instead of hydrophobic treated titanium oxide particles 1 in the toner external addition process, and test sheet C7 was produced.

[0142] (Comparative Example 8) Toner C8 was prepared in the same manner as in Example 1, except that hydrophobic treated zinc oxide particles 2 (average primary particle diameter 78.6 nm, hydrophobicity rate 76%) were used instead of hydrophobic treated zinc oxide particles 1 in the toner external addition process, and test sheet C8 was produced.

[0143] Comparative Example 9 Toner C9 was prepared in the same manner as in Example 1, except that hydrophobic treated titanium oxide particles 6 (average primary particle diameter 211.4 nm, hydrophobicity rate 65%) were used instead of hydrophobic treated titanium oxide particles 1 in the toner external addition process, and test sheet C9 was produced.

[0144] (Comparative Example 10) Toner C10 was prepared in the same manner as in Example 1, except that hydrophobic treated zinc oxide particles 7 (average primary particle diameter 323.3 nm, hydrophobicity rate: 64%) were used instead of hydrophobic treated zinc oxide particles 1 in the toner external addition process, and test sheet C10 was produced.

[0145] [evaluation] The test sheets for evaluating antibacterial properties and image density prepared in Examples 1 to 19 and Comparative Examples 1 to 10 were evaluated for (1) antibacterial properties and (2) image density as follows.

[0146] (1) Antibacterial properties The antibacterial activity value of the test sheet was measured in accordance with Antibacterial Products - Antibacterial Test Methods - Antibacterial Effect (JIS Z2801:2012; revised May 21, 2012), and the antibacterial activity was evaluated according to the following criteria. <Evaluation criteria> ◎: Activity value is 3.5 or higher (high antibacterial activity is observed) 〇: Activity value is 3.0 or more but less than 3.5 (antibacterial activity is sufficiently confirmed) △: Activity value is 2.0 or more but less than 3.0 (antibacterial properties are recognized) ×: Activity value is less than 2.0 (no antibacterial activity observed)

[0147] (2) Image density A blank sheet of paper was placed on the backside of the image printed on the test sheet, and the image density on the front side was measured using a densitometer (X-Rite eXact spectrophotometer / densitometer, manufactured by X-Rite Corporation). The image density was evaluated based on the measured density values ​​according to the following criteria. <Evaluation criteria> ◎: Image density is 1.30 or higher (sufficient density) ○: Image density is 1.25 or more and less than 1.30 (density is visible) △: Image density is 1.00 or more and less than 1.25 (minimum density is achieved) ×: Image density is less than 1.00 (insufficient density)

[0148] Tables 1 to 3 show the internal and external components that make up the toner base particles, as well as their physical properties. Table 4 shows the evaluation results of test sheets prepared using the resulting two-component developer. In the evaluation of (1) antibacterial properties and (2) image density, if at least one of them was rated "x", it was deemed unusable as a toner, and otherwise it was deemed usable.

[0149] [Table 1]

[0150] [Table 2]

[0151] [Table 3]

[0152] [Table 4]

[0153] From Tables 1 to 4, the following can be seen: (1) The toners having the constituent features of the present disclosure and the two-component developers containing them (Examples 1 to 20) are excellent in both antibacterial properties and image density, whereas the toners not having the constituent features of the present disclosure and the two-component developers containing them (Comparative Examples 1 to 10) are inferior.

[0154] (2) When the external addition ratio (A / B) of titanium oxide particles to zinc oxide particles is at the lower and upper limits (Examples 2 and 3, respectively), the synergistic effect of the two types of particles is weak, and although antibacterial properties can be confirmed, the effect is weak. On the other hand, when the external addition ratio (A / B) of titanium oxide particles to zinc oxide particles is less than the lower limit and exceeds the upper limit (Comparative Examples 3 and 4, respectively), the synergistic effect of the two types of particles is too weak, resulting in insufficient antibacterial properties.

[0155] (3) When the total external addition ratio (A+B) of titanium oxide particles and zinc oxide particles is the lower limit and the upper limit (Examples 4 and 5, respectively), antibacterial properties can be confirmed, but the effect is weak. On the other hand, when the total external addition ratio (A+B) of titanium oxide particles and zinc oxide particles is less than the lower limit (Comparative Example 5), the external addition ratio is too low and antibacterial properties are insufficient. On the other hand, when it exceeds the upper limit, although a sufficient antibacterial effect can be confirmed, the external addition ratio is too high and the toner chargeability is too low, making it impossible to obtain a sufficient image density.

[0156] (4) When the average primary particle size of titanium oxide particles is the lower limit (Example 6), the titanium oxide particles aggregate, and although the antibacterial effect is observed, the effect is reduced. Furthermore, when the average primary particle size of the zinc oxide particles is at the lower limit (Example 7), the zinc oxide particles begin to aggregate, and although the antibacterial effect is observed, the effect is reduced. On the other hand, when the average primary particle diameter of the titanium oxide particles is at the upper limit (Example 8), the particles are large and easily detached from the toner surface, the detached titanium oxide is not developed, the titanium oxide concentration on the test sheet is low, and although the antibacterial effect is recognized, its effect is reduced. Furthermore, when the average primary particle diameter of zinc oxide particles is at the upper limit (Example 9), the particles are large and easily detached from the toner surface, the detached zinc oxide is not developed, the concentration of zinc oxide on the test sheet is low, and although antibacterial action is observed, its effect is reduced.

[0157] (5) When the average primary particle size of titanium oxide particles is less than the lower limit (Comparative Example 7), the titanium oxide particles aggregate, and a sufficient antibacterial effect cannot be confirmed. Furthermore, when the average primary particle size of the zinc oxide particles is less than the lower limit (Comparative Example 8), the zinc oxide particles aggregate, and a sufficient antibacterial effect cannot be confirmed. On the other hand, when the average primary particle diameter of the titanium oxide particles exceeds the upper limit (Comparative Example 9), the particles are too large and detach from the toner surface, the detached titanium oxide particles are not developed, the concentration of titanium oxide on the test sheet is low, and no antibacterial effect is observed. Furthermore, when the average primary particle diameter of zinc oxide particles exceeds the upper limit (Comparative Example 10), the zinc oxide particles are large and easily detach from the toner surface, the detached titanium oxide particles are not developed, the concentration of zinc oxide on the test sheet becomes too low, and the antibacterial effect cannot be confirmed.

[0158] (6) When the external addition rate of the hydrophobic silica fine particles in the external additive is high and the ratio (A+B) / E of the total external addition rate (A+B) of the titanium oxide particles and zinc oxide particles to the external addition rate E of the external additive is less than the lower limit (Example 10), the toner is highly charged, the image density decreases, and although the antibacterial effect can be confirmed, its effect decreases. Furthermore, when the external addition rate of the hydrophobic silica fine particles in the external additive is low and the ratio (A+B) / E of the total external addition rate (A+B) of the titanium oxide particles and zinc oxide particles to the external addition rate E of the external additive exceeds the upper limit (Example 11), the toner fluidity is poor, the image density decreases, and although the antibacterial effect can be confirmed, its effect decreases.

[0159] (7) When the adhesive strength of both the titanium oxide particles and the zinc oxide particles is less than the lower limit (Example 12), these particles are detached from the toner, and the rate of external addition developed on the sheet is reduced accordingly. Therefore, although the antibacterial effect is observed, the effect is reduced.

[0160] (8) When the toner base particles further contain conductive carbon black (Example 13), the carbon black enters between the titanium oxide particles and the zinc oxide particles, increasing the contact opportunity between the two, enhancing the synergistic effect and improving the antibacterial effect. Furthermore, when the internal addition rate of carbon black to the toner base particles is low, less than the specified value of 1% by mass (Example 14), a sufficient antibacterial effect is observed, but it is difficult to observe an improvement in the antibacterial effect due to a boost in the synergistic effect. On the other hand, when the internal addition rate of carbon black to the toner base particles is high and exceeds the specified value of 10% by mass (Example 15), although an improvement in antibacterial activity due to a boost in the synergistic effect is observed, the toner charging property is reduced and an adverse effect is observed on the image density.

[0161] (9) When the volume average particle diameter of the carbon black is small, less than the specified value of 10 nm (Example 16), the carbon black is difficult to disperse in the toner, and although the antibacterial effect can be confirmed, the improvement of the antibacterial effect due to the increased synergistic effect is weak. On the other hand, when the volume average particle diameter of the carbon black is large and exceeds the specified value of 1000 nm (Example 17), a sufficient antibacterial effect is observed, but the contact opportunity between the titanium oxide particles and the zinc oxide particles cannot be efficiently increased, and it is difficult to observe an improvement in the antibacterial effect.

[0162] (10) When the hydrophobicity rate of titanium oxide particles and zinc oxide particles is less than the specified value of 40% (Example 19), the aggregation of these particles cannot be sufficiently prevented, and although an antibacterial effect is observed, the effect is low. Furthermore, when the hydrophobicity rate of titanium oxide particles and zinc oxide particles exceeds the specified value of 80% (Example 20), the contact between particles and the opportunity for metal ions to be eluted from the particle surface are reduced, and although antibacterial action is observed, the effect is low.

[0163] (11) When the volume average particle diameter of the carbon black is close to the upper limit of the specified value (1200 nm) (Example 18), the antibacterial effect is good, but is inferior to that when the volume average particle diameter of the carbon black is 20 nm (Example 13). (12) When titanium oxide particles are used alone (Comparative Example 1), a certain degree of antibacterial effect is observed, but there is no synergistic effect with zinc oxide particles, so the antibacterial effect is insufficient. On the other hand, when zinc oxide particles are used alone (Comparative Example 2), although a certain degree of antibacterial effect is observed, there is no synergistic effect with titanium oxide particles, and therefore the antibacterial effect is insufficient.

Claims

1. The toner particle is composed of at least a toner base particle and an externally added component externally added to the surface of the toner base particle, the externally added components include at least titanium oxide particles, zinc oxide particles, and an external additive; the titanium oxide particles and zinc oxide particles have average primary particle sizes of 75 to 200 nm and 80 to 300 nm, respectively; When the external addition rates of the titanium oxide particles and zinc oxide particles relative to the toner base particles are A% by mass and B% by mass, respectively, the following formulas (1) and (2) are satisfied: 0.5≦A / B≦2.0 (1) 7≦(A+B)≦12 (2) A toner characterized by satisfying the relationship:

2. When the external addition ratios of the titanium oxide particles, zinc oxide particles, and external additives to the toner base particles are A mass %, B mass %, and E mass %, respectively, the toner satisfies the following formula (3): 2.5≦(A+B) / E≦20 (3) 2. The toner according to claim 1, which satisfies the relationship:

3. 3. The toner according to claim 1, wherein the titanium oxide particles and the zinc oxide particles each have an adhesive strength of 60 to 100%.

4. 3. The toner according to claim 1, wherein the titanium oxide particles and the zinc oxide particles each have a hydrophobicity of 40 to 80%.

5. 3. The toner according to claim 1, wherein the toner base particles further contain a conductive agent.

6. 6. The toner according to claim 5, wherein the conductive agent has a volume average particle diameter of 10 to 1,000 nm and is contained in the toner base particles at an internal addition rate of 1 to 10% by mass.

7. 6. The toner according to claim 5, wherein the conductive agent is carbon black.

8. A two-component developer comprising the toner according to claim 1 or 2 and a carrier.

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