Toner and method for manufacturing the same

Abstract

The present invention provides a toner capable of forming images exhibiting excellent antibacterial or antiviral properties, and possessing sufficient electrostatic properties and resistance to aggregation, as well as a method for manufacturing the same. [Solution] In a toner containing toner particles and an antibacterial or antiviral agent having antibacterial or antiviral properties, the antibacterial or antiviral agent is a water-soluble organic acid metal salt, and the antibacterial or antiviral agent is fixed to the surface of the toner particles.

Description

Technical Field

[0001] The present disclosure relates to toner and a method for manufacturing the same.

Background Art

[0002] Toner (toner for developing an electrostatic charge image) used in image forming apparatuses such as copiers, multifunction peripherals, printers, and facsimile apparatuses that utilize an electrophotographic method generally has a configuration in which an external additive is adhered to the surface of toner particles (toner core). By fixing such toner on a recording medium such as paper, an image is formed on the recording medium.

[0003] There are cases where it is desired to impart antibacterial and antiviral properties to an image on a recording medium due to circumstances such as contact by an unspecified number of people. For example, Patent Document 1 discloses a toner in which an inorganic antibacterial agent is added as an external additive to spherical toner particles having a shape factor SF1 of 140 or less, and in its examples, hydroxyapatite-supported silver is used as the inorganic antibacterial agent.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As an attempt to add an antibacterial and antiviral agent to toner, the inventor prototyped a toner in which a powder of an antibacterial agent was added as an external additive to toner particles. However, since there are particles in the antibacterial agent that have a larger particle diameter than the toner particles, most of the antibacterial agent in the prototyped toner was present in a free state without adhering to the surface of the toner particles. When development was performed using that toner, a large amount of the antibacterial agent remained in the developer during the development process, and the amount of the antibacterial agent present on the image became very small, and antibacterial properties could not be imparted to the image.

[0006] The toner and method for manufacturing the same described herein were discovered in view of the above circumstances, and the primary objective is to provide a toner that can form images exhibiting excellent antibacterial or antiviral properties, and that has sufficient electrostatic properties and resistance to aggregation, as well as a method for manufacturing the same.

[0007] In this disclosure, "antibacterial / antiviral agent" refers to a substance having at least one of antibacterial and antiviral properties. Furthermore, in the following, a substance known to have antibacterial properties will be simply referred to as an "antibacterial agent," but this does not mean that this substance may also have antiviral properties. In this disclosure, antibacterial properties mean the property of suppressing the increase of bacteria attached to a surface and reducing the number of such bacteria, and antiviral properties mean the property of suppressing the increase of viruses attached to a surface and reducing the number of such viruses.

[0008] Furthermore, in this disclosure, "internal addition" means adding the additive so that it is contained within the substance being added, and "external addition" means adding the additive so that it adheres to the outer surface (surface) of the substance being added. [Means for solving the problem]

[0009] The toner described in this disclosure, which was made to solve the above problems, A toner comprising toner particles and an antibacterial or antiviral agent having antibacterial or antiviral properties, The aforementioned antibacterial and antiviral agent is a water-soluble organic acid metal salt. The antibacterial and antiviral agent is characterized by being fixed to the surface of the toner particles.

[0010] In the case of the toner described above, the antibacterial and antiviral agent is preferably copper gluconate.

[0011] Furthermore, in the case of the toner described above, it is preferable that the content of the antibacterial / antiviral agent in the toner is 0.1% or more and 10% or less.

[0012] Furthermore, in the case of the toner described above, it is preferable that the antibacterial and antiviral agent is fixed to the surface of the toner particles in the form of a plate-like deposit.

[0013] Furthermore, in the case of the toner described above, it is preferable that the antibacterial and antiviral agent is the antibacterial and antiviral agent dissolved in an aqueous medium and recrystallized on the surface of the toner particles.

[0014] Furthermore, in the case of the toner described above, it is preferable that the coverage rate of the toner particle surface by the antibacterial / antiviral agent is 35% or more.

[0015] The toner manufacturing method described herein, which was developed to solve the above problems, An antibacterial and antiviral agent dissolution step is performed to prepare an antibacterial and antiviral agent aqueous solution by dissolving the antibacterial and antiviral agent in an aqueous medium, The present invention is characterized by comprising an antibacterial and antiviral agent application step, which involves recrystallizing the antibacterial and antiviral agent in the aqueous solution of the antibacterial and antiviral agent on the surface of the toner particles, thereby fixing the antibacterial and antiviral agent to the surface of the toner particles.

[0016] In the toner manufacturing method described above, In the antibacterial / antiviral agent dissolution step, the aqueous solution of the antibacterial / antiviral agent is prepared so that the concentration of the antibacterial / antiviral agent is 0.6 g / mL or less. In the antibacterial / antiviral agent application step, it is preferable that a vacuum drying process is performed in which the antibacterial / antiviral agent aqueous solution and the toner particles are dried under reduced pressure while being stirred, thereby fixing the antibacterial / antiviral agent to the surface of the toner particles.

[0017] Furthermore, in the above-described method for manufacturing toner, it is preferable to continue stirring during the vacuum drying process until the temperature of the toner particles reaches 40°C or higher and 55°C or lower. [Effects of the Invention]

[0018] According to the toner of the present disclosure, an image exhibiting excellent antibacterial or antiviral properties can be formed, and excellent effects such as sufficient chargeability and low agglomeration can be achieved.

Brief Description of the Drawings

[0019] [Figure 1] It is a schematic diagram showing a method for manufacturing a toner according to an embodiment of the present disclosure. [Figure 2] It is an image of a toner according to an embodiment of the present disclosure taken using a scanning electron microscope (SEM).

Modes for Carrying Out the Invention

[0020] Hereinafter, the toner of the present disclosure and its manufacturing method will be described.

[0021] 1. Overall Configuration of Toner, etc. The toner according to the present embodiment is a toner containing toner particles and an antibacterial / antiviral agent having antibacterial or antiviral properties, wherein the antibacterial / antiviral agent is a water-soluble organic acid metal salt, and the antibacterial / antiviral agent is adhered to the surface of the toner particles.

[0022] FIG. 1 is a schematic diagram showing a method for manufacturing a toner according to an embodiment of the present disclosure. It shows that through an antibacterial / antiviral agent dissolution step (left side of FIG. 1) and an antibacterial / antiviral agent application step (center of FIG. 1), a toner 10 (right side of FIG. 1) in which an antibacterial / antiviral agent 12 is adhered to the surface of toner particles 11 is manufactured. In the antibacterial / antiviral agent dissolution step, the antibacterial / antiviral agent 12 is dissolved in an aqueous medium to prepare an antibacterial / antiviral agent aqueous solution 12A. Next, in the antibacterial / antiviral agent application step, the antibacterial / antiviral agent 12 in the antibacterial / antiviral agent aqueous solution 12A is recrystallized on the surface of the toner particles 11 to adhere the antibacterial / antiviral agent 12 to the surface of the toner particles 11.

[0023] Here, first, the reason for manufacturing the toner according to the present embodiment by the manufacturing method shown in FIG. 1 will be described.

[0024] As described above, the inventors attempted to add antibacterial and antiviral agents to toner by creating a prototype toner in which antibacterial powder was added as an external additive to the toner particles. However, because some antibacterial particles were larger in diameter than the toner particles, much of the antibacterial agent in the prototype toner remained free and did not adhere to the surface of the toner particles. When this toner was used for development, a large amount of the antibacterial agent remained in the developer during the development process, resulting in only a very small amount of antibacterial agent being present on the image, making it impossible to impart antibacterial properties to the image.

[0025] Therefore, the inventors focused on water-soluble antibacterial and antiviral agents. In the antibacterial and antiviral agent application process, toner particles 11 and an aqueous solution of the antibacterial and antiviral agent 12A are mixed and stirred while subjected to reduced-pressure drying, thereby coating the surface of the toner particles 11 with the antibacterial and antiviral agent 12. The coated antibacterial and antiviral agent 12 is not released during the developing process and is carried to the recording medium such as paper. Therefore, according to the toner of this embodiment, it is possible to form an image that exhibits excellent antibacterial or antiviral properties.

[0026] In contrast, a toner manufacturing method in which antibacterial and antiviral agents are added to the toner particles can be considered. However, since a large portion of the antibacterial and antiviral agents would be located inside the toner particles, the agents would not be easily exposed to the surface of the formed image, and it may not be possible to obtain sufficient antibacterial or antiviral effects.

[0027] In other words, in this embodiment, the toner is coated with an antibacterial / antiviral agent by recrystallizing the antibacterial / antiviral agent on the surface of the toner particles. As a result, the release of the antibacterial / antiviral agent during the image formation process is suppressed, and it is possible to form an image in which the antibacterial / antiviral agent is exposed on the surface. This allows the effect of the antibacterial / antiviral agent to be maximized. Consequently, since the antibacterial or antiviral effect can be obtained with the minimum necessary amount of antibacterial / antiviral agent, the decrease in electrostatic charge caused by adding the antibacterial / antiviral agent to the toner can be minimized.

[0028] As described above, the toner according to this embodiment is manufactured by recrystallizing an antibacterial and antiviral agent on the surface of the toner particles. Therefore, when observed with a scanning electron microscope (SEM), a portion of the toner surface is covered with plate-like crystals, which are deposits of the antibacterial and antiviral agent fixed in a plate-like form. Figure 2 is an image of the toner according to this embodiment taken using a scanning electron microscope (SEM). In the example image in Figure 2, copper gluconate is used as the antibacterial and antiviral agent, and it can be confirmed that plate-like copper gluconate crystals 12C are present on the surface of the toner particles 11.

[0029] In contrast, when antibacterial and antiviral agents are internally added to toner particles, such plate-like crystals do not exist on the surface of the toner particles. However, when antibacterial and antiviral agents are simply externally added to toner particles (adhered by stirring and mixing), it is thought that granular antibacterial and antiviral agents adhere to the surface of the toner particles. In other words, the presence of plate-like crystals of antibacterial and antiviral agents on the surface of the toner particles confirms that the water-soluble antibacterial and antiviral agents have been recrystallized and used as a coating.

[0030] 2. Toner manufacturing method Next, a method for manufacturing toner according to this embodiment will be described. The method for manufacturing toner according to this embodiment includes a toner particle manufacturing step for producing toner particles and an antibacterial / antiviral agent application step for fixing an antibacterial / antiviral agent to the surface of the toner particles, and may further include an external additive step for attaching an external additive to the toner particles after the antibacterial / antiviral agent has been applied.

[0031] <Toner Particle Manufacturing Process> In the toner particle manufacturing process, toner particles, which form the core of the toner, are produced. Toner particles are particles that contain a binder resin and, if necessary, internal additives such as release agents, colorants, and antistatic agents. Methods for producing toner particles include dry methods such as pulverization, and wet methods such as suspension polymerization, emulsification and agglutination, dispersion polymerization, dissolution and suspension, and melt emulsification. The following describes the method for producing toner particles by pulverization.

[0032] When toner particles are produced by the pulverization method, a toner composition containing a binder resin and, if necessary, internal additives such as a mold release agent, colorant, and electrostatic control agent is dry-mixed in a mixer, and then melt-kneaded in a kneader. The kneaded mixture obtained by melt-kneading is cooled and solidified, and the solidified material is pulverized in a pulverizer. After that, the particle size is adjusted by classification or other means as necessary to obtain toner particles.

[0033] Examples of mixers include Henschel-type mixing devices such as the Henschel mixer (product name, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke Industries Co., Ltd.)), Super Mixer (product name, manufactured by Kawata Corporation), and MechanoMill (product name, manufactured by Okada Seikou Co., Ltd.), as well as the OngMill (product name, manufactured by Hosokawa Micron Corporation) and Hybridization System (product name, manufactured by Nara Machine Works Co., Ltd.).

[0034] For the mixing machine, general-purpose mixers such as twin-screw extruders, three-roll mills, and lab blast mills can be used. Specifically, examples include single-screw or twin-screw extruders such as the TEM-100B (product name, manufactured by Toshiba Machine Co., Ltd. (now Shibaura Machine Co., Ltd.)), PCM-65 / 87, and PCM-30 (all product names, manufactured by Ikegai Co., Ltd.), and open-roll type mixers such as the Nidex (product name, manufactured by Mitsui Mining Co., Ltd.). Among these, open-roll type mixers are preferred.

[0035] Examples of pulverizers include jet-type pulverizers that utilize a supersonic jet stream, such as the Counter Jet Mill AFG (product name, manufactured by Hosokawa Micron Corporation), and impact-type pulverizers that introduce solidified material into the space formed between a high-speed rotating rotor and stator to pulverize it.

[0036] Examples of classifiers include rotary wind classifiers (swivel-type wind classifiers) such as the TSP separator (product name, manufactured by Hosokawa Micron Corporation).

[0037] <Antibacterial / Antiviral Agent Application Process> The antibacterial and antiviral agent application process involves fixing the antibacterial and antiviral agent to the surface of the toner particles. Specifically, it is a process of coating at least a portion of the surface of the toner particles with the antibacterial and antiviral agent. Before performing this process, an antibacterial and antiviral agent dissolution process is carried out first.

[0038] In other words, an antimicrobial / antiviral agent is dissolved in an aqueous medium beforehand to prepare an aqueous solution of the antimicrobial / antiviral agent (antimicrobial / antiviral agent dissolution step). The aqueous medium used is not particularly limited and includes water, a mixed solvent of water and a water-soluble solvent (for example, water-soluble organic substances such as alcohols and ketones), and water is preferred.

[0039] The concentration of the antibacterial and antiviral agent in the aqueous solution is preferably 0.6 g / mL or less, more preferably 0.5 g / mL or less, even more preferably 0.4 g / mL or less, and particularly preferably 0.3 g / mL or less. If the concentration of the antibacterial and antiviral agent in the aqueous solution exceeds 0.6 g / mL, the antibacterial and antiviral agent may not be sufficiently dissolved. If such an aqueous solution is used in the antibacterial and antiviral agent application process, the undissolved antibacterial and antiviral agent may segregate on the surface of the toner particles, potentially resulting in insufficient antibacterial and antiviral effect relative to the amount of antibacterial and antiviral agent added. Furthermore, the antibacterial and antiviral agent may precipitate in a way that connects the toner particles, potentially causing aggregation of the toner particles. Aggregation of toner particles can lead to decreased electrostatic properties and a decrease in the apparent density (AD) of the toner. On the other hand, if the concentration of the antibacterial and antiviral agent in the aqueous solution is low, there is no adverse effect on the performance of the resulting toner. However, to avoid the high moisture content and the resulting longer drying time, it is preferable that the concentration of the antibacterial and antiviral agent in the aqueous solution be 0.2 g / mL or higher.

[0040] Next, the antibacterial and antiviral agent in the aqueous solution of the antibacterial and antiviral agent prepared in the antibacterial and antiviral agent dissolution step is recrystallized on the surface of the toner particles, thereby fixing the antibacterial and antiviral agent to the surface of the toner particles (antibacterial and antiviral agent application step). Specifically, the toner particles and the aqueous solution of the antibacterial and antiviral agent are mixed and stirred while undergoing a vacuum drying treatment, thereby coating at least a portion of the surface of the toner particles with the antibacterial and antiviral agent. By applying the antibacterial and antiviral agent to the toner particles in this way, the antibacterial and antiviral agent is less likely to be released from the toner particles than when it is attached by stirring and mixing, in other words, the antibacterial and antiviral agent can be fixed to the surface of the toner particles. That is, "fixed" as used in this disclosure means a state in which it is firmly attached than "attached" by stirring and mixing, and "antibacterial and antiviral agent fixed" does not include the case where the antibacterial and antiviral agent is simply added externally and adheres to the surface of the toner particles.

[0041] In other words, in this embodiment, in the antibacterial and antiviral agent application step, a vacuum drying process is performed in which the antibacterial and antiviral agent aqueous solution and toner particles are dried under reduced pressure while being stirred, thereby fixing the antibacterial and antiviral agent to the surface of the toner particles.

[0042] One specific method involves, for example, placing toner particles and an antibacterial / antiviral aqueous solution into the mixer tank of a Henschel mixer vacuum drying system (manufactured by Mitsui Mining Co., Ltd., product name: FM20C), stirring at a peripheral speed of 10 m / sec to 30 m / sec, and then reducing the pressure inside the mixer tank. By mixing and drying under reduced pressure in this way, toner particles (toner particles after application of antibacterial / antiviral agents) can be obtained that have been dried to a moisture content of less than 1% by mass.

[0043] In the antibacterial and antiviral agent application process, the mixing ratio of toner particles to the antibacterial and antiviral agent is preferably such that the surface of the toner particles is thinly coated with the antibacterial and antiviral agent. Specifically, it is preferable to mix in a ratio of 0.1 to 10 parts by mass of antibacterial and antiviral agent per 100 parts by mass of toner particles. If a large amount of antibacterial and antiviral agent is added to the toner in excess of this ratio, the electrostatic properties of the toner may decrease, or the toner may become more prone to aggregation.

[0044] In this vacuum drying process, it is preferable to continue stirring until the temperature of the toner particles reaches 40°C to 55°C. More specifically, in the vacuum drying process using the Henschel mixer vacuum drying system, it is preferable to continue stirring until the temperature inside the mixer tank (internal temperature) rises to 40°C to 55°C and then stop. This temperature is more preferably 40°C to 50°C, and even more preferably 42°C to 48°C. If the temperature is below the above lower limit, drying may not be sufficient, and in that case, some of the antibacterial and antiviral agents may precipitate without being uniformly coated on the surface of the toner particles, potentially resulting in insufficient antibacterial and antiviral effects relative to the amount of antibacterial and antiviral agents added. In addition, the antibacterial and antiviral agents may precipitate in a way that connects the toner particles, potentially causing aggregation of the toner particles. If the temperature exceeds the above upper limit, depending on the thermophysical properties of the toner particles, the surface of the toner particles may soften, potentially causing aggregation of the toner particles. Aggregation of toner particles may lead to a decrease in electrostatic charge and a decrease in the apparent density (AD) of the toner.

[0045] <External addition process> In the toner manufacturing method according to this embodiment, when an external additive step is performed, the toner particles after the application of the antibacterial / antiviral agent are mixed with the external additive to adhere the external additive to the surface of the toner particles. As the mixer in the external additive step, a known device commonly used in the art can be used, for example, the mixer exemplified in the "toner particle manufacturing step" above.

[0046] The toner according to this embodiment, manufactured through the above process, can be mixed with a carrier and used as a two-component developer.

[0047] 3. Components of toner Next, the toner according to this embodiment will be described for each component.

[0048] <Antibacterial and antiviral agents> In this embodiment, the toner has an antibacterial and antiviral agent fixed to the surface of the toner particles. As described above, since the antibacterial and antiviral agent is recrystallized on the surface of the toner particles, the antibacterial and antiviral agent adheres more firmly to the surface of the toner particles than when it is simply added externally (adhered by stirring and mixing). In other words, "antibacterial and antiviral agent fixed" as used in this disclosure does not include the case where the antibacterial and antiviral agent is simply added externally to the surface of the toner particles and adheres thereto.

[0049] The antibacterial and antiviral agent used in this embodiment is a water-soluble organic acid metal salt. Because it is water-soluble, toner can be produced using the manufacturing method described above.

[0050] The metals that make up the organic acid metal salt are preferably metals that have antibacterial or antiviral properties, such as copper, silver, zinc, platinum, and nickel. Among these, copper, silver, and zinc are preferred from the viewpoint of having strong antibacterial and antiviral properties. The metal in the organic acid metal salt contained in the toner according to this embodiment may consist of only one type, or it may be composed of a combination of two or more types.

[0051] As the organic acid constituting the organic acid metal salt, water-soluble organic acids can be used, such as gluconic acid, formic acid, acetic acid, propionic acid, butyric acid, citric acid, malic acid, lactic acid, maleic acid, succinic acid, etc. The organic acid in the organic acid metal salt contained in the toner according to this embodiment may consist of only one type, or it may be composed of a combination of two or more types.

[0052] In the toner according to this embodiment, copper gluconate is preferred among organic acid metal salts. Copper gluconate is a water-soluble copper compound with antibacterial properties and is a copper salt of gluconic acid. The molecular formula of copper gluconate is C 12 H 22 CuO 14Generally, many copper-containing compounds (copper-based compounds) are classified as hazardous substances, but copper gluconate is not classified as a hazardous substance and is a highly safe chemical substance designated as a food additive. When copper gluconate dissolves in an aqueous medium, copper ions are generated, and this solution turns blue.

[0053] The average particle size of the antibacterial / antiviral agent before dissolving it in an aqueous medium is not particularly limited, but is preferably 3 μm or larger. This is because the toner manufacturing method according to this embodiment has the advantage that even antibacterial / antiviral agents with a particle size larger than that of the toner particles can be fixed to the surface of the toner particles. Antibacterial / antiviral agents with a small average particle size may adhere to the surface of the toner particles simply by being added externally, without using the toner manufacturing method according to this embodiment.

[0054] The melting point of the antibacterial / antiviral agent is not particularly limited, but it is preferably between 50°C and 200°C in order not to impair the storage stability and fixation properties of the toner.

[0055] The antibacterial and antiviral agent content in the toner according to this embodiment is preferably 0.1% to 10%, more preferably 0.5% to 9%, even more preferably 0.5% to 5%, and particularly preferably 0.5% to 3%. If the antibacterial and antiviral agent content is below the above lower limit, the antibacterial and antiviral effect will be weakened, and if the density of the image formed on the recording medium is low, the image may not exhibit sufficient antibacterial and antiviral properties. Furthermore, if the antibacterial agent content exceeds the above upper limit, the proportion of the antibacterial and antiviral agent in the toner may be too high, potentially reducing the electrostatic properties of the toner.

[0056] In the toner according to this embodiment, the coverage rate of the toner particle surface with the antibacterial / antiviral agent is preferably 35% or more, more preferably 40% or more, even more preferably 45% or more, and particularly preferably 50% or more. If the coverage rate of the toner particle surface with the antibacterial / antiviral agent is less than the above lower limit, the antibacterial / antiviral agent may segregate and crystallize on the toner particle surface, or the content of the antibacterial / antiviral agent may be insufficient, making it impossible to form an image with sufficient antibacterial / antiviral properties. On the other hand, if the coverage rate of the toner particle surface with the antibacterial / antiviral agent is high, the antibacterial / antiviral properties of the formed image will also be high, but the proportion of the antibacterial / antiviral agent in the toner may be too high, which may reduce the electrostatic properties of the toner. Considering this, the coverage rate of the toner particle surface with the antibacterial / antiviral agent is preferably 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less.

[0057] Furthermore, experiments have confirmed that when the toner produced by the manufacturing method according to this embodiment contains an antibacterial / antiviral agent at a concentration of 0.1% to 10%, the coating rate of the toner particle surface by the antibacterial / antiviral agent is 40% or more. Toners in which the coating rate of the toner particle surface by the antibacterial / antiviral agent is less than 40% are thought to have the antibacterial / antiviral agent either internally added to the toner particles or simply externally added (attached by stirring and mixing).

[0058] In this disclosure, toner is added to a solvent in which at least one component contained in the toner particles dissolves, but the antibacterial / antiviral agent does not dissolve. The toner is then stirred to dissolve the solvent-soluble components contained in the toner (dissolution treatment), and the residual rate of the dissolved components remaining in the toner is defined as the "coverage rate of the toner particle surface by the antibacterial / antiviral agent." The specific measurement method is as described in the "Method for measuring the coverage rate of the toner particle surface by the antibacterial / antiviral agent" in the examples listed below.

[0059] The reason why this residue rate can be considered as the "coating rate of the toner particle surface by antibacterial and antiviral agents" is as follows: When toner particles are coated with antibacterial and antiviral agents, the antibacterial and antiviral agents reduce the contact area between the toner particle surface and the solvent, inhibiting the elution of dissolved components contained in the toner. Therefore, by quantifying the dissolved components through elemental analysis, the "coating rate of the toner particle surface by antibacterial and antiviral agents" can be measured. On the other hand, if the toner is not coated with antibacterial and antiviral agents, the contact area between the toner particle surface and the solvent is large, so not much dissolved component remains, and the residue rate of dissolved components is small. In other words, if the residue rate of dissolved components is small, it can be judged that the "coating rate of the toner particle surface by antibacterial and antiviral agents" is also small.

[0060] <Toner particles (toner core)> The toner particles according to this embodiment include a binder resin and internal additives such as a mold release agent and a colorant, with these internal additives dispersed in the binder resin. Furthermore, optional components may be included as needed, provided that they do not impair the effects of this disclosure. The volume-average particle diameter of the primary particles of the toner particles can be appropriately selected depending on the purpose, for example, 5 μm to 8 μm. The components constituting the toner particles will be described below.

[0061] (resin) Examples of binder resins in the toner particles according to this embodiment include polyester resins, polystyrene resins such as styrene-acrylic resins, (meth)acrylic acid ester resins, polyolefin resins, polyurethane resins, and epoxy resins. One of these may be used alone, or two or more may be used in combination.

[0062] Polyester resins used as binder resins are typically obtained by polycondensation reactions via esterification or transesterification reactions using known methods, involving one or more components selected from divalent alcohol components and trivalent or higher polyvalent alcohol components, and one or more components selected from divalent carboxylic acids and trivalent or higher polyvalent carboxylic acids.

[0063] The conditions for the condensation polymerization reaction can be appropriately set depending on the reactivity of the monomer components, and the reaction should be terminated when the polymer achieves desirable physical properties. For example, the reaction temperature is approximately 170°C to 250°C, and the reaction pressure is approximately 5 mmHg to atmospheric pressure.

[0064] Examples of divalent alcohol components 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 Examples include diols such as lycopropyl glycol, 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.

[0065] Examples of polyhydric alcohol components with a valency of 3 or higher include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

[0066] In the toner according to this embodiment, one of the above-mentioned divalent alcohol component and trivalent or higher polyvalent alcohol component may be used alone, or two or more may be used in combination.

[0067] Examples of divalent carboxylic 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 their acid anhydrides, lower alkyl esters, etc.

[0068] Examples of polycarboxylic acids with three or more valent values ​​include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalentricarboxylic acid, 1,2,4-naphthalentricarboxylic 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, empoletrimeric acid, and their acid anhydrides and lower alkyl esters.

[0069] In the toner according to this embodiment, one of the above-mentioned divalent carboxylic acids and trivalent or higher polyvalent carboxylic acids may be used alone, or two or more may be used in combination.

[0070] The toner particles according to this embodiment preferably contain a crystalline polyester resin and an amorphous polyester resin. In this case, the crystalline polyester resin is dispersed in the amorphous polyester resin.

[0071] In this disclosure, crystalline resins and amorphous resins are distinguished by their crystallinity index. Resins with a crystallinity index in the range of 0.6 to 1.5 are defined as crystalline resins, and resins with a crystallinity index of less than 0.6 or greater than 1.5 are defined as amorphous resins. Resins with a crystallinity index greater than 1.5 are amorphous, and resins with a crystallinity index less than 0.6 have low crystallinity and a large amorphous portion.

[0072] The crystallinity index is a physical property that indicates the degree of crystallization of a resin, and is defined by the ratio of the softening point to the highest endothermic peak temperature (softening point / highest endothermic peak temperature). Here, the highest endothermic peak temperature refers to the temperature of the highest-temperature peak among the observed endothermic peaks. In crystalline polyester resins, the highest peak temperature is defined as the melting point, and in amorphous polyester resins, the highest-temperature peak is defined as the glass transition point.

[0073] The degree of crystallization can be controlled by adjusting the type and ratio of raw material monomers, as well as the manufacturing conditions (e.g., reaction temperature, reaction time, cooling rate).

[0074] -Amorphous polyester resin- Amorphous polyester resin is a polyester resin with a crystallinity index of less than 0.6 or greater than 1.5, but a polyester resin with a crystallinity index greater than 1.5 is preferred. Amorphous polyester resin can be obtained, for example, by polycondensation of a polybasic acid and a polyhydric alcohol.

[0075] As polybasic acids, known monomers for polyester synthesis can be used, such as aromatic carboxylic acids including terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic acid, pyromellitic acid, and naphthalenedicarboxylic acid; aliphatic carboxylic acids including maleic anhydride, fumaric acid, succinic acid, alkenyl succinic anhydride, and adipic acid; and methyl esters of these polybasic acids. These polybasic acids may be used individually or in combination of two or more.

[0076] As polyhydric alcohols, known monomers for polyester synthesis can be used, such as aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, and glycerin; alicyclic polyhydric alcohols such as cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A; and aromatic diols such as ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A. These polyhydric alcohols may be used individually or in combination of two or more.

[0077] The polycondensation reaction between a polybasic acid and a polyhydric alcohol can be carried out according to conventional methods. For example, it is carried out by contacting the polybasic acid and the polyhydric alcohol in the presence or absence of an organic solvent and in the presence of a polycondensation catalyst (such as tin octoate), and the reaction is terminated when the acid value and softening point of the resulting polyester reach the desired values. This yields an amorphous polyester resin. If a methyl ester of a polybasic acid is used as part of the polybasic acid, a demethanol polycondensation reaction is carried out. In this polycondensation reaction, by appropriately changing the mixing ratio and reaction rate of the polybasic acid and polyhydric alcohol, for example, the carboxyl group content at the ends of the polyester can be adjusted, and consequently, the properties of the resulting amorphous polyester resin can be modified. Furthermore, if trimellitic anhydride is used as the polybasic acid, carboxyl groups can be easily introduced into the main chain of the polyester.

[0078] Furthermore, the polycondensation reaction between polybasic acids and polyhydric alcohols is usually carried out under temperature conditions of 150°C to 300°C, preferably 170°C to 280°C. In addition, the above polycondensation reaction can be carried out under atmospheric pressure, reduced pressure, or pressurized pressure, but it is desirable to appropriately adjust the pressure in the system while monitoring the progress of the polycondensation reaction using physical properties (e.g., acid value, melting point, etc.) and the stirring torque or power value of the reactor.

[0079] The acid value of the amorphous polyester resin is preferably 10 KOH mg / g or more and 30 KOH mg / g or less, and more preferably 15 KOH mg / g or more and 25 KOH mg / g or less.

[0080] The weight-average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 to 50,000, and the number-average molecular weight (Mn) is preferably 1,000 to 10,000. In this disclosure, the weight-average molecular weight and number-average molecular weight are values ​​measured by gel permeation chromatography (GPC), with tetrahydrofuran (THF) used as the mobile phase and polystyrene used as the standard substance.

[0081] The glass transition temperature (Tg) of amorphous polyester resin is preferably between 55°C and 70°C.

[0082] -Crystalline polyester resin- Crystalline polyester resin is a polyester resin having a crystallinity index of 0.6 to 1.5, but a polyester resin having a crystallinity index of 0.8 to 1.2 is preferred. Furthermore, crystalline polyester resin can be obtained, for example, by polycondensation of a polybasic acid and a polyhydric alcohol. For example, it can be produced by a known method such as that described in Japanese Patent Application Publication No. 2006-113473.

[0083] Examples of polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, and 1,4-butenediol. However, it is preferable to use polyhydric alcohols that promote the crystallinity of the resin, such as aliphatic diols having 2 to 8 carbon atoms. These polyhydric alcohols may be used individually or in combination of two or more.

[0084] From the viewpoint of improving the crystallinity of the resin, the content of aliphatic diols having 2 to 8 carbon atoms in the polyhydric alcohol is preferably 80 mol% or more. Furthermore, when two or more aliphatic diols having 2 to 8 carbon atoms are used, it is desirable that the content of one type of aliphatic diol having 2 to 8 carbon atoms be 70 mol% or more in the polyhydric alcohol.

[0085] Examples of polybasic acids include aliphatic dicarboxylic acids having 2 to 30 carbon atoms, preferably 2 to 8, such as fumaric acid, adipic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, sebacic acid, azelaic acid, n-dodecylsuccinic acid, and n-dodecenylsuccinic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; and polycarboxylic acids with a valency of 3 or more, such as trimellitic acid and pyromellitic acid. To obtain a high degree of crystallinity (crystallinity index), aliphatic dicarboxylic acids are preferred, and aliphatic dicarboxylic acids having 2 to 8 carbon atoms are even more preferred. These polybasic acids may be used individually or in combination of two or more.

[0086] The acid value of the crystalline polyester resin is preferably between 5 mg KOH / g and 20 mg KOH / g. Furthermore, the hydroxyl value of the crystalline polyester resin is preferably between 5 mg KOH / g and 20 mg KOH / g.

[0087] The molecular weight of the crystalline polyester resin is preferably such that the weight-average molecular weight (Mw) is between 5,000 and 100,000, and the number-average molecular weight (Mn) is between 3,000 and 20,000. In this disclosure, the weight-average molecular weight and the number-average molecular weight are values ​​measured by gel permeation chromatography (GPC), with chloroform used as the mobile phase and polystyrene used as the standard substance.

[0088] (Coloring agent) The toner particles according to this embodiment may contain a colorant. As the colorant, various types and colors of organic and inorganic pigments and dyes commonly used in the field of electrophotography can be used, for example, black, white, yellow, orange, red, purple, blue, and green colorants can be used.

[0089] Examples of black colorants include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite, and magnetite.

[0090] Examples of white colorants include zinc oxide, titanium dioxide, antimony white, and zinc sulfide.

[0091] Examples of yellow colorants include lead yellow, 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 93, CI pigment yellow 94, and CI pigment yellow 138.

[0092] Examples of orange colorants include red lead, molybdenum orange, permanent orange GTR, pyrazolone orange, balkan orange, induthrene brilliant orange RK, benzidine orange G, induthrene brilliant orange GK, CI pigment orange 31, and CI pigment orange 43.

[0093] Examples of red colorants include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, lysol 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 Examples include CI Pigment Red 7, 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, and CI Pigment Red 222.

[0094] Examples of purple colorants include manganese purple, fast violet B, and methyl violet lake.

[0095] 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, First Sky Blue, Induthlene 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.

[0096] Examples of green colorants include chromium green, chromium oxide, pigment green B, micalite green lake, final yellow green G, and CI pigment green 7.

[0097] In the toner according to this embodiment, one of the above-mentioned colorants may be used alone or in combination of two or more, and the combination may be of different colors or the same color. The colorant content in the toner particles is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 3% by mass or more and 15% by mass or less.

[0098] (Release agent) The toner particles according to this embodiment may contain a release agent. As the release agent, waxes commonly used in the field of electrophotography can be used. Examples include petroleum-based waxes such as paraffin wax and its derivatives, microcrystalline wax and its derivatives; hydrocarbon-based synthetic waxes such as Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, polypropylene wax and its derivatives, polyolefin polymer waxes (such as low molecular weight polyethylene wax) and its derivatives; plant-based waxes such as carnauba wax and its derivatives, rice wax and its derivatives, candelilla wax and its derivatives, and wood wax; animal-based waxes such as beeswax and whale wax; oil-based synthetic waxes such as fatty acid amides, phenolic fatty acid esters and their derivatives; silicone polymers, higher fatty acids, etc. One of these may be used alone, or two or more may be used in combination. Derivatives include oxides, block copolymers of vinyl monomers and waxes, graft-modified vinyl monomers and waxes, etc.

[0099] In this embodiment, the content of the release agent in the toner particles is preferably 0.5% by mass or more and 10% by mass or less.

[0100] (Other oral additives) In the toner according to this embodiment, other internal additives may be included as needed. Examples of other internal additives include charge control agents. Charge control agents are added to impart desirable charge properties to the toner. The charge control agent is not particularly limited, and charge control agents used in the field of electrophotography for controlling positive and negative charges can be used.

[0101] Examples of charge control agents for controlling positive charge include quaternary ammonium salts, pyrimidine compounds, triphenylmethane derivatives, guanidine salts, and amidine salts.

[0102] Examples of charge control agents for controlling negative charge include metal-containing azo compounds, azo complex dyes, metal complexes and metal salts of salicylic acid and its derivatives (metals such as chromium, zinc, and zirconium), organobentonite compounds, and boron compounds.

[0103] <External additives> In this embodiment, the toner may have an external additive attached to the surface of the toner particles described above. Specifically, as described in the external additive step above, the toner may be configured in which the external additive is attached to the surface of the toner particles after the antibacterial and antiviral agents have been applied.

[0104] As external additives, those commonly used in this field can be used, for example, inorganic particles such as silica, titanium oxide, and aluminum oxide (alumina) with an average particle size of 7 nm to 200 nm. These inorganic particles may be used individually or in combination of two or more. These inorganic particles are preferred when surface-treated with hydrophobic agents such as silane coupling agents, titanium coupling agents, and silicone oils to impart hydrophobicity, as this reduces the decrease in electrical resistance and charge in high-humidity environments.

[0105] Examples of silica particles used as external additives include silica particles commonly used in the relevant field, such as fumed silica particles obtained by burning silicon tetrachloride, dry silica particles such as arc silica which is atomized in the gas phase using high energy such as plasma; wet silica particles such as precipitated silica synthesized under alkaline conditions using an aqueous sodium silicate solution as a raw material, and gel silica synthesized under acidic conditions; colloidal silica particles obtained by polymerizing acidic silicic acid in an alkaline state; and sol-gel silica particles obtained by hydrolysis of organosilane compounds.

[0106] For the silica particles used as an external additive, commercially available hydrophobized silica particles may be used, or unhydrophobized silica particles may be treated before use.

[0107] The titanium dioxide particles used as an external additive may be anatase-type titanium dioxide particles or rutile-type titanium dioxide particles. One method for producing rutile-type titanium dioxide particles is described in Japanese Patent Publication No. 2001-26423, which involves hydrolyzing an aqueous titanium tetrachloride solution to prepare a fine titania sol containing rutile nuclei, separating it, and then heat-treating it to obtain titanium dioxide particles. Another method for producing anatase-type titanium dioxide particles is described in Japanese Patent Publication No. 2000-10335, which involves hydrolyzing a solution of raw materials such as ilmenite ore dissolved in sulfuric acid, granulating it, drying it, and then firing it at a high temperature to obtain titanium dioxide particles.

[0108] The amount of external additive is preferably 0.2 parts by mass or more and 5 parts by mass or less per 100 parts by mass of toner particles. If the amount of external additive is below the lower limit, the effect of improving toner fluidity may not be sufficiently obtained. If the amount of external additive exceeds the upper limit, the toner's fixation performance may decrease. [Examples]

[0109] The toners of this disclosure will be described in detail below based on examples and comparative examples.

[0110] 1.Measurement / calculation method <Method for measuring the volume-average particle size of toner particles> 50 mL of electrolyte (Beckman Coulter, Inc., product name: ISOTON-II) is mixed with 20 mg of toner particles and 1 mL of alkyl ether sulfate sodium. The mixture is then dispersed for 3 minutes at a frequency of 20 kHz using an ultrasonic disperser (AS ONE Corporation, tabletop dual-frequency ultrasonic cleaner, model: VS-D100) to obtain a sample for measurement. The obtained sample is then measured using a particle size distribution analyzer (Beckman Coulter, Inc., model: Multisizer3) under conditions of aperture diameter: 100 μm and number of particles measured: 50,000 counts. The volume-average particle size is determined from the volume particle size distribution of the toner particles.

[0111] <Method for measuring the coverage rate of toner particle surfaces with antibacterial and antiviral agents> After immersing toner in a solvent in which at least one component contained in the toner particles (toner core) dissolves, but the antibacterial / antiviral agent does not dissolve, and stirring to dissolve the solvent-soluble components contained in the toner (dissolution treatment), the residual rate of the dissolved components remaining in the toner is defined as the "coating rate of the toner particle surface by the antibacterial / antiviral agent."

[0112] If the toner is coated with an antibacterial or antiviral agent, the agent reduces the contact area between the toner particle surface and the solvent, inhibiting the elution of dissolved components contained in the toner. Therefore, the "coverage rate of the toner particle surface by the antibacterial or antiviral agent" can be measured by quantifying the dissolved components through elemental analysis. If the toner is not coated with an antibacterial or antiviral agent, the contact area between the toner particle surface and the solvent is large, and not much dissolved component remains, resulting in a low residue rate of dissolved components. In other words, a low residue rate of dissolved components indicates a low "coverage rate of the toner particle surface by the antibacterial or antiviral agent." Although there is a possibility that the antibacterial or antiviral agent may be released in the solvent, if the specific gravity of the antibacterial or antiviral agent is greater than that of the solvent, the released antibacterial or antiviral agent can be separated by collecting the supernatant liquid.

[0113] Specifically, in this disclosure, "coverage rate of toner particle surface by antibacterial / antiviral agents" is defined as a value measured by the following procedure. First, prepare a solvent that meets the following conditions. (1) The antibacterial agent is insoluble in the solvent. (2) At least one of the components contained in the toner particles dissolves in the solvent, and the amount of the dissolved component can be quantified by elemental analysis. (3) The specific gravity of the solvent is lower than that of the antibacterial agent.

[0114] Next, the toner is stirred in the solvent for about 1 minute. After that, it is allowed to stand for about 1 minute, and the supernatant is collected (elution treatment). The collected supernatant is allowed to air dry, and the obtained toner is subjected to fluorescent X-ray analysis. From the results of this analysis, the "residual rate of dissolved components," which is the ratio of dissolved components in the toner after elution treatment to dissolved components in the toner before elution treatment, is determined. This "residual rate of dissolved components" is defined as the "coating rate of the toner particle surface by antibacterial / antiviral agents."

[0115] In this example, ethanol was used as the solvent and copper gluconate as the antibacterial agent. It was confirmed that copper gluconate is insoluble in ethanol, while potassium derived from the charge control agent contained in the toner is soluble in ethanol. In other words, this potassium is the soluble component.

[0116] 2. Toner production <Preparing toner raw materials> -Preparation of amorphous polyester resin A- In a reaction vessel, 440 g (2.7 mol) of terephthalic acid, 235 g (1.4 mol) of isophthalic acid, 7 g (0.05 mol) of adipic acid, 554 g (8.9 mol) of ethylene glycol, and 0.5 g of tetrabutoxytitanate as a polymerization catalyst were added. The mixture was reacted at 210°C under a nitrogen stream for 5 hours while distilling off the water and ethylene glycol produced, and then reacted under reduced pressure of 5-20 mmHg for 1 hour. Next, 103 g (0.54 mol) of trimellitic anhydride was added and reacted under atmospheric pressure for 1 hour, and then reacted under reduced pressure of 20-40 mmHg, and the resin was removed at the predetermined softening point. The recovered ethylene glycol amounted to 219 g (3.5 mol). After cooling the obtained resin to room temperature, it was pulverized into particles. This was designated as amorphous polyester resin A. Amorphous polyester resin A had a glass transition temperature (Tg) of 56°C, a softening temperature (Tm) of 135°C, an SP value of 11.0, an acid value of 37 mgKOH / g, and a hydroxyl value of 50 mgKOH / g.

[0117] -Preparation of crystalline polyester resin C- In a reaction vessel, 132 g (1.12 mol) of 1,6-hexanediol, 230 g (1.0 mol) of 1,10-decanedicarboxylic acid, and 3 g of tetrabutoxytitanate as a polymerization catalyst were added, and the reaction was carried out at 210°C under atmospheric pressure for 5 hours while distilling off the water produced. The reaction was then continued under reduced pressure of 5-20 mmHg, and the resin was removed when the acid value fell to 2 mg KOH / g or less. After the obtained resin was cooled to room temperature, it was pulverized into particles. This was designated as crystalline polyester resin C. Crystalline polyester resin C had a melting point Tmp of 80°C, a softening point Tm of 88°C (Tm / Tmp = 1.1), and an SP value of 9.5.

[0118] -List of antibacterial agents- Table 1 below summarizes the antibacterial agents used in the examples and comparative examples. Note that "C" in Table 1 indicates a sample used in the comparative example and does not possess antibacterial properties. Specifically, in Table 1, "○" under "Antibacterial Properties" indicates that the substance has antibacterial properties, and "×" indicates that it does not. Also in Table 1, "○" under "Water Soluble Properties" indicates that the substance is water soluble, and "×" indicates that it is not water soluble. Under "Organic Acid Metal Salt," "○" indicates that the substance is an organic acid metal salt, and "×" indicates that the substance is not an organic acid metal salt.

[0119] [Table 1]

[0120] <Toner particle production> (Mixing and kneading process) Toner particles (toner cores) were prepared using the following toner raw materials. • Binding resin: Amorphous polyester resin A 80% by mass • Crystalline polyester resin: Crystalline polyester resin C 8% by mass • Coloring agent: CI Pigment Blue 15:3 (DIC brand) 6% by mass • Release agent: Ester wax (manufactured by NOF Corporation, product name: WEP-3) 5% by mass • Charge control agent: Salicylic acid compound (Orient Chemical Industry Co., Ltd., product name: Bontro E84) 1% by mass

[0121] The above materials were pre-mixed for 5 minutes using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd., model: FM20C), and then melt-kneaded using an open-roll continuous kneader (product name: MOS320-1800, manufactured by Mitsui Mining Co., Ltd.).

[0122] The open roll settings were as follows: the heating roll's supply side temperature was 130°C and its discharge side temperature was 100°C; the cooling roll's supply side temperature was 40°C and its discharge side temperature was 25°C. Both the heating and cooling rolls had a diameter of 320 mm and an effective length of 1550 mm, with a roll gap of 0.3 mm on both the supply and discharge sides. The heating roll rotated at 75 rpm, the cooling roll rotated at 65 rpm, and the toner material was supplied at 5.0 kg / h.

[0123] (Fine grinding process) The resulting molten mixture was cooled using a cooling belt and then coarsely ground using a speed mill with a φ2 mm screen. The resulting coarsely ground material was then finely ground using a jet-type pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd., model: IDS-2) to obtain finely ground material.

[0124] (Classification process) Next, the obtained finely ground material was classified using an elbow jet classifier (manufactured by Nippon Steel Mining Co., Ltd., model: EJ-LABO) to obtain toner particles.

[0125] <Production of standard toner> First, a standard toner without antibacterial agents was prepared. This standard toner was used to obtain the "unprocessed test piece" in "Evaluation Item 1: Antibacterial Test" described later, and the evaluation criteria in "Evaluation Item 2: Evaluation of Electrostatic Properties" and "Evaluation Item 3: Evaluation of Aggregation Resistance (AD)". The "unprocessed test piece" was an image sample obtained by printing a solid image using the standard toner according to the procedure in "Evaluation Item 1: Antibacterial Test" described later, and was used to measure the antibacterial activity value.

[0126] (External addition process) In the "Preparation of Toner Particles" described above, 100 parts by mass of toner particles and 1.3 parts by mass of hydrophobic silica particles (manufactured by Nippon Aerosil Co., Ltd., product name: RX200) with an average primary particle diameter of 12 nm were placed in a Henschel mixer (manufactured by Mitsui Mining Co., Ltd., model: FM20C). The mixing was performed for 1 minute with the peripheral speed of the stirring blade tip set to 40 m / sec to obtain standard toner (volume average particle diameter 7.0 μm, coefficient of variation 23%).

[0127] <Example 1> An antibacterial agent was added to the toner particles obtained in the "Preparation of Toner Particles" described above. Specifically, copper gluconate (labeled "A" in Table 1, manufactured by Fuso Chemical Industries, Ltd., product name: Helsius Cu) was first dissolved in pure water to prepare an antibacterial aqueous solution with a concentration of 0.3 g / mL (antibacterial agent dissolution step).

[0128] Next, toner particles and an aqueous antibacterial agent solution were placed in the mixer tank of a Henschel mixer vacuum drying system (manufactured by Mitsui Mining Co., Ltd., model: FM20C). The amount added was 1.01 parts by mass of antibacterial agent per 100 parts by mass of toner particles (resulting in an antibacterial agent content of 1% in the toner after external addition). Then, a vacuum drying process was performed by stirring under reduced pressure with the peripheral speed of the stirring blade tip set to 10 m / sec to 30 m / sec, and continued until the temperature inside the mixer tank (internal temperature) rose to 45°C (antibacterial agent application process). After that, the toner particles obtained after antibacterial agent application were subjected to external addition in the same manner as the external addition process in "Preparation of Standard Toner" described above, to obtain the toner of Example 1.

[0129] <Examples 2-19> As shown in Table 2 below, toners for Examples 2 to 19 were obtained in the same manner as in Example 1, except that the antibacterial agent content, the concentration of the antibacterial agent aqueous solution, and the equipment stop temperature during the reduced-pressure drying process (temperature inside the mixer tank when the Henschel mixer vacuum drying system is stopped) were changed.

[0130] <Comparative Example 1> Comparative Example 1 is an example in which, instead of fixing the antibacterial agent to the toner particles by vacuum drying as in Examples 1 to 19, the antibacterial agent was mixed with the external additive in the external additive process to adhere to the toner particles. Specifically, the external additive process is as follows.

[0131] (External addition process) In the "Preparation of Toner Particles" described above, 100 parts by mass of toner particles, 1.3 parts by mass of hydrophobic silica particles (manufactured by Nippon Aerosil Co., Ltd., product name: RX200) with an average primary particle diameter of 12 nm, and 10 parts by mass of copper gluconate (A in Table 1, manufactured by Fuso Chemical Industries, Ltd., product name: Helsius Cu) as an antibacterial agent (9% antibacterial agent content in the toner after external addition) were added to a Henschel mixer (manufactured by Mitsui Mining Co., Ltd., model: FM20C), and the mixture was stirred for 1 minute with the peripheral speed of the stirring blade tip set to 40 m / sec to obtain the toner of Comparative Example 1 (volume average particle diameter 7.0 μm, coefficient of variation 23%).

[0132] <Comparative Example 2> Comparative Example 2 toner was obtained in the same manner as Comparative Example 1, except that a mixed powder of copper and tin alloy powder and titanium oxide powder (B in Table 1, manufactured by Aida Chemical Industries Co., Ltd., product name: Asgard CST) was used instead of copper gluconate. In other words, Comparative Example 2 is an example in which an antibacterial agent that is not water-soluble is used.

[0133] <Comparative Example 3> Comparative Example 3 toner was obtained in the same manner as Comparative Example 1, except that zinc stearate (C in Table 1, manufactured by NOF Corporation, trade name: MZ-2) was used in the content ratio shown in Table 2 instead of copper gluconate. In other words, Comparative Example 3 is an example in which an organic acid metal salt that does not have antibacterial properties or water solubility is used.

[0134] [Table 2]

[0135] In Table 2, "○" under "Water-soluble" indicates that the substance is water-soluble, while "×" indicates that it is not water-soluble. Under "Presence or absence of plate-like crystals," "○" indicates that the substance exists as plate-like crystals on the surface of the toner particles, while "×" indicates that the substance does not exist as plate-like crystals on the surface of the toner particles.

[0136] Furthermore, in the "Manufacturing Method for the Antimicrobial Agent Application Process," "vacuum drying" means that the antimicrobial agent was fixed to the surface of the toner particles by the vacuum drying process described above, and "stirring and mixing" means that an attempt was made to attach the antimicrobial agent to the surface of the toner particles by stirring and mixing, as in the external addition process described above. In "Adhesion to the Toner Particle Surface," "○" indicates that it was confirmed that the substance was attached (fixed in the case of vacuum drying) to the surface of the toner particles, and "×" indicates that it was not confirmed.

[0137] 3. Evaluation When an antibacterial agent is added to the toner to impart antibacterial properties to the image, depending on the manufacturing conditions, the toner's electrostatic properties may decrease or the toner may become more prone to aggregation. Therefore, the toner was evaluated based on three criteria: antibacterial properties, electrostatic properties, and resistance to aggregation.

[0138] <Evaluation Item 1: Antimicrobial Test (Evaluation of Antimicrobial Properties)> First, image samples for the antibacterial test were prepared using the following procedure. A two-component developer was prepared by mixing toner and a ferrite core carrier with an average particle size of 60 μm to achieve a toner concentration of 10% by mass. The prepared two-component developer and toner were then filled into the developer unit and toner cartridge of a color multifunction printer (Sharp Corporation, model: BP-20C25), respectively, and a solid image was printed. The printed solid image was cut into 5cm x 5cm squares to obtain image samples for the antibacterial test.

[0139] Next, in accordance with JIS Z2801 (Antibacterial processed products - Antibacterial test methods and antibacterial effects), the antibacterial activity values ​​of the obtained image samples were measured, and the "antibacterial properties" were evaluated according to the following criteria. Specifically, products with an antibacterial activity value of 2.0 or higher were judged to have antibacterial properties.

[0140] ◎ (Excellent: High antibacterial activity is recognized): The antibacterial activity value is 4.0 or higher. ○ (Good: Sufficient antibacterial activity is observed): The antibacterial activity value is 3.0 or higher and less than 4.0. △ (Acceptable: Antibacterial properties are observed): The antibacterial activity value is 2.0 or higher and less than 3.0. × (Not acceptable: No antibacterial properties observed): The antibacterial activity value is less than 2.0.

[0141] <Evaluation Item 2: Evaluation of Electrical Chargeability> A two-component developer was prepared by blending and mixing toner and a ferrite core carrier with an average particle size of 60 μm to a toner concentration of 5% by mass. The amount of charge of the prepared two-component developer was measured using a blow-off charge measuring device (manufactured by Toshiba Chemical Corporation). The charge of the test samples using the toners of the examples and comparative examples was denoted as Q1, and the charge of the standard sample using the standard toner was denoted as Q2. Q1 / Q2 × 100 [%] was used as an index of chargeability, and the following criteria were used to evaluate the samples based on this index.

[0142] ◎ (Excellent): The electrostatic charge index is 95% or higher. ○ (Good): The electrostatic charge index is between 75% and 95%. △ (Acceptable): The electrostatic charge index is between 25% and 75%. × (Unacceptable): The electrostatic charge index is less than 25%.

[0143] <Evaluation Item 3: Evaluation of resistance to aggregation> The agglomeration resistance of the toner was evaluated using apparent density (AD). Apparent density was measured in accordance with JIS K5101-12-1 (Pigment Test Methods - Part 12: Apparent Density or Apparent Specific Volume - Section 1: Static Method). AD(1) ​​was the apparent density of the toners in the examples and comparative examples, and AD(2) was the apparent density of the standard toner. AD(1) / AD(2) × 100 [%] was used as an index of agglomeration resistance, and the following criteria were used to evaluate it based on this index.

[0144] ◎ (Excellent): The index for resistance to aggregation is 100% or higher. ○ (Good): The index of resistance to aggregation is 90% or more but less than 100%. △ (Acceptable): The index of resistance to aggregation is 50% or more but less than 90%. × (Unacceptable): The index of resistance to aggregation is less than 50%.

[0145] <Overall Rating> According to Table 3 below, each of the above evaluation items 1 to 3 was scored, and an overall evaluation was made based on the total score. For example, in Example 1, evaluation item 1 (antibacterial activity) was scored at 3.5 points based on the antibacterial activity value itself, evaluation item 2 (static activity) was scored at 0.5 points for an evaluation of "◎", and evaluation item 3 (resistance to aggregation) was scored at 0.5 points for an evaluation of "◎", so the total score was 4.5 points, resulting in an overall evaluation of "◎". Note that if evaluation item 1 (antibacterial activity) was scored at "×", the objective of imparting antibacterial properties to the image could not be achieved, so the overall evaluation was set to "×" regardless of the scores of evaluation item 2 (static activity) and evaluation item 3 (resistance to aggregation).

[0146] [Table 3]

[0147] [Table 4]

[0148] Table 4 shows the evaluation results for each example and comparative example. According to Table 4, the toners of Examples 1 to 19, in which the antibacterial agent, which is a water-soluble organic acid metal salt, is fixed to the surface of the toner particles, were able to form images exhibiting excellent antibacterial properties and also possessed sufficient electrostatic properties and resistance to aggregation. Furthermore, from these evaluation results, it can be inferred that toners using an antiviral agent, which is a water-soluble organic acid metal salt, are able to form images exhibiting excellent antiviral properties and also possess sufficient electrostatic properties and resistance to aggregation.

[0149] In contrast, Comparative Examples 1-3, which did not meet these requirements, showed inferior antibacterial activity compared to the examples.

[0150] Comparative Example 1 is an example in which, instead of fixing copper gluconate as an antibacterial agent to toner particles by vacuum drying as in Examples 1 to 19, copper gluconate was mixed with an external additive in the external additive process to attempt to attach copper gluconate to the toner particles. However, sufficient copper gluconate did not adhere to the surface of the toner particles, and no plate-like crystals of copper gluconate were present on the surface. Comparative Examples 2 and 3 are examples in which copper gluconate in Comparative Example 1 was replaced with a different substance. Specifically, Comparative Example 2 is an example in which a mixed powder (a mixture of copper and tin alloy powder and titanium oxide powder) was used as an antibacterial agent that is not a water-soluble organic acid metal salt, and Comparative Example 3 is an example in which zinc stearate was used as a water-soluble organic acid metal salt, but it does not have antibacterial properties.

[0151] Examples such as Example 5, in which the antibacterial agent content in the toner is 10% or less, are found to be particularly superior in the evaluation of resistance to aggregation compared to Example 6, in which the antibacterial agent content exceeds the upper limit. Furthermore, Examples such as Example 7, in which the antibacterial agent content in the toner is 0.1% or more, are found to be particularly superior in the evaluation of antibacterial properties compared to Example 8, in which the antibacterial agent content is below the lower limit.

[0152] Examples such as Example 3, where the coverage rate of the toner particle surface with the antibacterial agent is 35% or higher, are found to be superior in the evaluation of electrostatic properties and also superior in antibacterial activity values ​​compared to Example 4, where the coverage rate is below the lower limit. Furthermore, Examples such as Example 1, where the coverage rate of the toner particle surface with the antibacterial agent is 70% or less, are found to be particularly superior in the evaluation of electrostatic properties compared to Example 2, where the coverage rate exceeds the upper limit.

[0153] Comparing Example 9 and Example 11, both containing 1% antibacterial agent, it can be seen that Example 9, where the concentration of antibacterial agent in the antibacterial agent aqueous solution used in the toner manufacturing process is 0.6 g / mL or less, performs better in terms of electrostatic evaluation and antibacterial activity than Example 11, where the concentration of antibacterial agent exceeds the upper limit. Furthermore, comparing Example 10 and Example 12, both containing 9% antibacterial agent, it can be seen that Example 10, where the concentration of antibacterial agent in the antibacterial agent aqueous solution used in the toner manufacturing process is 0.6 g / mL or less, performs better in terms of electrostatic evaluation and antibacterial activity than Example 12, where the concentration of antibacterial agent exceeds the upper limit.

[0154] Examples such as Example 14, in which the equipment stop temperature during the reduced-pressure drying process (the temperature inside the mixer tank when the Henschel mixer vacuum drying system is stopped, i.e., the temperature of the toner particles) is 55°C or lower, are superior to Example 15, in terms of evaluation of electrostatic properties and resistance to aggregation, compared to Example 15, in which the equipment stop temperature exceeds the upper limit.

[0155] Comparing Example 16 and Example 18, both containing 1% antibacterial agent, Example 16, where the equipment stop temperature during vacuum drying was 40°C or higher, performed better in the evaluation of electrostatic properties and resistance to aggregation than Example 18, where the equipment stop temperature was below that lower limit, and also showed superior antibacterial activity values. Furthermore, comparing Example 17 and Example 19, both containing 9% antibacterial agent, Example 17, where the equipment stop temperature during vacuum drying was 40°C or higher, showed superior values ​​in the measured values ​​of electrostatic properties and resistance to aggregation than Example 19, where the equipment stop temperature was below that lower limit.

[0156] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of this disclosure is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the claims. [Explanation of Symbols]

[0157] 10 Toners 11 Toner particles 12. Antibacterial and antiviral agents 12A Antibacterial and antiviral aqueous solution 12C Antibacterial and antiviral plate-like crystals

Claims

1. A toner comprising toner particles and an antibacterial or antiviral agent having antibacterial or antiviral properties, The aforementioned antibacterial and antiviral agent is a water-soluble organic acid metal salt. The toner is characterized in that the antibacterial and antiviral agent is fixed to the surface of the toner particles.

2. The toner according to claim 1, The toner is characterized in that the antibacterial and antiviral agent is copper gluconate.

3. The toner according to claim 1, The toner is characterized in that the content of the antibacterial / antiviral agent in the toner is 0.1% or more and 10% or less.

4. The toner according to claim 1, A toner characterized by containing plate-like deposits on the surface of the toner particles, which are formed by the antibacterial and antiviral agent.

5. The toner according to claim 1, The toner is characterized in that the antibacterial and antiviral agent is dissolved in an aqueous medium and recrystallized on the surface of the toner particles.

6. The toner according to claim 1, The toner is characterized in that the coating rate of the toner particle surface with the antibacterial / antiviral agent is 35% or more.

7. A method for manufacturing toner according to any one of claims 1 to 6, An antibacterial and antiviral agent dissolution step is performed to prepare an antibacterial and antiviral agent aqueous solution by dissolving the antibacterial and antiviral agent in an aqueous medium, A method for producing toner, characterized by comprising an antibacterial and antiviral agent application step, which involves recrystallizing the antibacterial and antiviral agent in the aforementioned aqueous solution of the antibacterial and antiviral agent on the surface of the toner particles to fix the antibacterial and antiviral agent to the surface of the toner particles.

8. A method for manufacturing toner according to claim 7, In the antibacterial / antiviral agent dissolution step, the aqueous solution of the antibacterial / antiviral agent is prepared so that the concentration of the antibacterial / antiviral agent is 0.6 g / mL or less. A method for manufacturing toner, characterized in that the antibacterial and antiviral agent application step involves a vacuum drying process in which the antibacterial and antiviral agent aqueous solution and the toner particles are dried under reduced pressure while being stirred, thereby fixing the antibacterial and antiviral agent to the surface of the toner particles.

9. A method for manufacturing toner according to claim 8, A method for producing toner, characterized in that, during the vacuum drying process, stirring is continued until the temperature of the toner particles reaches 40°C or higher and 55°C or lower.

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