Method for manufacturing toner

Abstract

To provide a method for manufacturing toner in which external additive particles exhibit excellent adhesion, the external additive particles do not easily detach from the toner even after long-term use, and in which change in coverage of the external additive particles remains small.SOLUTION: The method for manufacturing toner includes the step of obtaining toner particles by melt-kneading and pulverizing a mixture containing a toner-particle raw material. The mixture contains a specified amount of water in which ultrafine bubbles containing oxygen are dispersed. The concentration of dissolved oxygen in the water in which the ultrafine bubbles are dispersed is at least 10 mg / L. The ultrafine bubbles have a specified particle diameter, and the water in which the ultrafine bubbles are dispersed contains 1.0×104 bubbles / mL or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing toner used in electrophotography, electrostatic recording, electrostatic printing, and toner jet methods. [Background technology]

[0002] In recent years, electrophotographic full-color multifunction printers have become widely used, and their expansion into the printing market is progressing. The printing market requires stable output of high-quality images even after long-term use. To meet this requirement, toners must exhibit high developability and transferability even after long-term use. To this end, studies are being conducted to prevent the detachment of external additive particles such as inorganic fine particles and to prevent changes in the coverage of external additive particles on the toner surface after long-term use.

[0003] If external additive particles detach from the toner after long-term use, the external additive particles migrate to the photoreceptor surface, and some of them even slip through the cleaning blade during the cleaning process. This causes a difference in latent image potential during the charging process between areas where many external additive particles have slipped through and areas where few have, which can manifest as differences in image density (hereinafter referred to as image density unevenness). To address this issue, for example, Patent Document 1 proposes a technology in which the toner is heat-treated to thermally fix the external additive particles, thereby improving stability during long-term use.

[0004] Furthermore, if the coverage of the external additive particles decreases significantly after long-term use, for example, the adhesive force between the transfer member and the toner increases, which may cause a decrease in transfer efficiency. As a result, image density may decrease. To address this issue, Patent Documents 2 to 5 propose techniques for fixing the external additive to the surface of the toner base particles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-020897 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-197371 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-158789 [Patent Document 4] Japanese Patent Application Laid-Open No. 2010-176063 [Patent Document 5] Japanese Patent Application Laid-Open No. 2009-288667 Summary of the Invention [Problem to be solved by the invention]

[0006] The toners described in Patent Documents 1 to 5 above have room for further improvement in terms of stability during long-term use. The present disclosure provides a method for producing a toner that has an excellent adhesion rate of external additive particles, is less likely to detach from the toner after long-term use, and has little change in coverage rate of the external additive particles. [Means for solving the problem]

[0007] The present disclosure provides a method for producing a toner having toner particles containing a binder resin and external additive particles present on the surfaces of the toner particles, the method comprising: The manufacturing method comprises: (i) a melt-kneading step of melt-kneading a mixture containing the toner particle raw material containing the binder resin to obtain a kneaded product; (ii) a pulverization step of pulverizing the kneaded mixture to obtain toner particles; and (iii) an external addition step of externally adding the external additive particles to the toner particles; and the mixture contains 1.0 to 30.0 parts by mass of a liquid relative to 100 parts by mass of the toner particle raw material to be melt-kneaded, the liquid is water in which ultrafine bubbles containing oxygen are dispersed, the dissolved oxygen concentration in the water in which the ultrafine bubbles are dispersed is 10 mg / L or more; The particle size distribution of the bubbles in the water in which the ultrafine bubbles are dispersed is as follows: (a) a peak particle size of 10 to 1000 nm; (b) the number average particle size of the bubble particles having a particle size of 10 to 1000 nm is 50 to 800 nm; The water in which the ultra-fine bubbles are dispersed has a particle size of 1.0 x 10 4 The present invention relates to a method for producing a toner containing at least 1000 particles / mL. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a method for producing a toner that has an excellent adhesion rate of external additive particles, is less likely to detach from the toner after long-term use, and has little change in coverage rate of external additive particles. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the upper and lower limits, which are the endpoints, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

[0010] According to the present disclosure, it is possible to provide a method for producing a toner that has an excellent adhesion rate of external additive particles and that exhibits little change in the coverage rate of external additive particles on the toner surface after long-term use. The present inventors consider the reasons for this to be as follows.

[0011] In the external addition process to toner particles, external additive particles such as inorganic fine particles are mainly added. In particular, for external additive particles with a relatively large particle size, such as those with a particle size distribution peaking in the range of 50 nm to 300 nm, the contact area between the external additive particles and the toner particle surface may be insufficient. Therefore, the adhesive force between the external additive particles and the toner particles is insufficient, which may cause the external additive particles to detach (Problem 1).

[0012] In addition, external additive particles with a relatively small particle size, such as those with a particle size distribution peaking in the range of 20 nm to 50 nm, may move on the toner particle surface after long-term use and become unevenly distributed in the recesses of the toner particle surface, resulting in a decrease in the coverage of the toner with external additive particles, an increase in the adhesive force between the toner and the transfer member, and a decrease in transfer efficiency (image density) (Problem 2).

[0013] As a means of solving the above-mentioned problem 1, the authors have conducted extensive research into methods for increasing the contact area between toner particles and external additive particles in order to improve the adhesion rate of the external additive particles, and have found that the following method is effective.

[0014] Specifically, water in which ultrafine bubbles (hereinafter also referred to as UFB) are dispersed (hereinafter also referred to as UFB water) is added to a mixture containing raw toner particle materials to be melted and kneaded. As a result, voids resulting from the UFB are obtained in the kneaded product after melting and kneading. The UFB is, for example, a small number of These are bubbles with a size of about 10 nm to 1 μm (1000 nm). By kneading a mixture in the presence of UFB, voids of a size similar to that of the UFB are formed in the kneaded product.

[0015] Next, on the surface of the toner particles obtained through the pulverization process of the kneaded material, recesses are formed due to the toner particles being crushed with the formed voids as fracture surfaces. It is thought that the final external addition process brings the external additive particles into contact with the recesses on the toner particle surface, thereby increasing the contact area between the external additive particles and the toner particles and improving the adhesion rate of the external additive particles.

[0016] Adding UFB water to a mixture containing raw toner particle materials and then melt-kneading the mixture is also an effective means of solving the above-mentioned problem 2. The inventors believe the reason for this is as follows: After long-term use, external additive particles tend to localize, particularly in recesses on the surface of toner particles. By adding UFB water, the number of recesses where external additive particles can localize increases after long-term use, and the amount of external additive particles unevenly concentrated and accumulated in one recess decreases compared to when there are fewer recesses. As a result, it is presumed that changes in the coverage rate of the external additive in the toner after long-term use are kept low.

[0017] It is believed that the above mechanism makes it possible to provide a method for producing a toner that has an excellent adhesion rate of external additive particles and has a small change in the coating rate of the external additives even after long-term use. A preferred toner configuration will be described below.

[0018] The present disclosure provides a method for producing a toner having toner particles containing a binder resin and external additive particles present on the surfaces of the toner particles, the method comprising: The manufacturing method comprises: (i) a melt-kneading step of melt-kneading a mixture containing the toner particle raw material containing the binder resin to obtain a kneaded product; (ii) a pulverization step of pulverizing the kneaded mixture to obtain toner particles; and (iii) an external addition step of externally adding the external additive particles to the toner particles; and the mixture contains 1.0 to 30.0 parts by mass of a liquid relative to 100 parts by mass of the toner particle raw material to be melt-kneaded, the liquid is water in which ultrafine bubbles containing oxygen are dispersed, the dissolved oxygen concentration in the water in which the ultrafine bubbles are dispersed is 10 mg / L or more; The particle size distribution of the bubbles in the water in which the ultrafine bubbles are dispersed is as follows: (a) a peak particle size of 10 to 1000 nm; (b) the number average particle size of the bubble particles having a particle size of 10 to 1000 nm is 50 to 800 nm; The water in which the ultra-fine bubbles are dispersed has a particle size of 1.0 x 10 4 The present invention relates to a method for producing a toner containing at least 1000 particles / mL.

[0019] Each of the components of the toner will be described below. <Binder resin> The toner particles contain a binder resin. The raw materials for the toner particles contain a binder resin. Known polymers can be used as the binder resin. Specifically, for example, the following polymers can be used. Homopolymers of styrene and its substituted derivatives such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, and styrene-vinyl methyl ketone copolymer. Examples of suitable resins include styrene-based copolymers such as styrene-acrylonitrile-indene copolymers, polyvinyl chloride, phenolic resins, natural resin-modified phenolic resins, natural resin-modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyester resins, polyurethane resins, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone-indene resins, and petroleum-based resins. These resins may be used alone or in combination of two or more.

[0020] Among these, amorphous polyester resins are preferred. The amorphous polyester resin is preferably a condensation polymer of a carboxylic acid component and an alcohol component. Known carboxylic acid components and alcohol components can be used. The carboxylic acid component preferably contains at least one selected from the group consisting of terephthalic acid and fumaric acid. The alcohol component preferably contains an alkylene oxide adduct of bisphenol A (average number of added moles is preferably 1 to 5 mol). As the acid component, a trivalent carboxylic acid such as trimellitic acid may be used.

[0021] The binder resin may contain a crystalline polyester resin, which is preferably a condensation polymer of an alcohol containing an aliphatic diol having 2 to 23 carbon atoms and a carboxylic acid containing an aliphatic dicarboxylic acid having 3 to 24 carbon atoms.

[0022] The crystalline polyester resin is more preferably a condensation polymer of an alcohol containing an aliphatic diol having 4 to 12 carbon atoms in an amount of 80 mol% to 100 mol% (more preferably 85 mol% to 100 mol%) relative to the total alcohol constituting the crystalline polyester resin, and an aliphatic dicarboxylic acid having 4 to 20 carbon atoms in an amount of 80 mol% to 100 mol% (more preferably 85 mol% to 100 mol%) relative to the total carboxylic acid constituting the crystalline polyester resin.

[0023] The aliphatic diol is preferably a straight-chain aliphatic diol, such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, or a derivative thereof. The derivative is not particularly limited as long as it can be obtained by condensation polymerization with a similar resin structure. For example, a derivative obtained by esterifying the diol may be used.

[0024] The aliphatic dicarboxylic acid is preferably a straight-chain aliphatic dicarboxylic acid, and examples thereof include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, hexadecanedioic acid, eicosanedioic acid, and derivatives thereof. The derivative is not particularly limited as long as it can obtain a similar resin structure by condensation polymerization. Examples include acid anhydrides of the dicarboxylic acids and derivatives obtained by alkyl esterification or acid chloride of the dicarboxylic acid component. On the other hand, the carboxylic acid may be used in combination with a carboxylic acid other than the aliphatic dicarboxylic acid.

[0025] The content of the crystalline polyester resin is preferably 0.1 to 5.0% by mass, and more preferably 1.0 to 4.0% by mass, based on the toner particles.

[0026] <Coloring agent> The toner particles may contain a colorant. The toner particle raw material may also contain a colorant. Examples of colorants include pigments and dyes. The colorant preferably contains a pigment. Examples of the pigment include known organic pigments, carbon black, and magnetic materials.

[0027] Examples of cyan pigments include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specific examples include CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66. Examples of magenta pigments include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specific examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254, and CI Pigment Violet 19.

[0028] Examples of yellow pigments include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specific examples include CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191, 194, and 214. Examples of black pigments include carbon black, magnetic materials, and pigments toned to black using the above-mentioned yellow pigments, magenta pigments, and cyan pigments. Examples of white pigments include titanium oxide, magnesium oxide, aluminum oxide, zinc oxide, barium sulfate, calcium carbonate, calcium titanate, strontium titanate, silica, clay, and talc.

[0029] The pigments can be used singly or in combination. They can also be used in the form of a solid solution. The pigments are preferably selected from the viewpoints of hue angle, saturation, brightness, lightfastness, OHP transparency, and dispersibility in toner particles.

[0030] The content of the pigment is preferably 1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the binder resin in the case of cyan, magenta, yellow, and black pigments, and is preferably 20 parts by mass or more and 50 parts by mass or less relative to 100 parts by mass of the binder resin in the case of white pigments, from the viewpoint of concealing the color of the base and making it unrecognizable in order to express a sufficient white color.

[0031] <Release agent> The toner particles may contain a release agent, i.e., the raw toner particles may contain a release agent. Examples of the release agent include the following: Hydrocarbon waxes such as low molecular weight polyolefins (low molecular weight polyethylene, low molecular weight polypropylene), alkylene copolymers, ceresin, paraffin wax, microcrystalline wax, and Fischer-Tropsch wax; silicones with melting points; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide; ester waxes such as stearyl stearate; vegetable waxes such as carnauba wax, rice wax, candelilla wax, Japan wax, and jojoba oil; animal waxes such as beeswax; mineral and petroleum waxes such as montan wax, ozokerite, and ester wax; and modified products thereof.

[0032] The release agent may be used alone or in combination of two or more. The release agent preferably contains a hydrocarbon wax. The melting point of the release agent is preferably 150°C or lower, more preferably 40°C or higher and 130°C or lower, and even more preferably 40°C or higher and 110°C or lower. The content of the release agent in the toner particle raw material is 1 mass part per 100 mass parts of binder resin. It is preferable that the amount is from 1 part to 30 parts by mass.

[0033] <Ultra-fine bubble water> The mixture containing the toner particle raw material contains a liquid, which is water in which ultra-fine bubbles containing oxygen are dispersed. Typically, bubbles with a particle size of 100 μm or more (submillimeter bubbles) rise to the surface in water and disappear at the air-liquid interface. Bubbles with a particle size of more than 1 μm but less than 100 μm (microbubbles) rise less quickly in water, but are unable to withstand water pressure and are prone to disappearing in water. In contrast, ultrafine bubbles (nanobubbles) with a particle size of 1 μm (1000 nm) or less can remain stable in water for several months.

[0034] By incorporating extremely fine bubbles such as ultrafine bubbles into the mixture of raw materials for toner particles during melting and kneading, depressions of approximately the same size as UFBs are formed on the surface of the toner particles, which is thought to increase the contact area between the external additive particles and the toner particles and improve the adhesion rate.

[0035] In addition, regarding the particle size distribution of the bubbles in the water in which the ultrafine bubbles are dispersed, (a) the peak particle size is 10 nm to 1000 nm; (b) The number average particle size of the bubble particles having a particle size of 10 to 1000 nm is 50 to 800 nm.

[0036] If the particle diameter of the bubbles exceeds 1000 nm, the diameter will be larger than the diameter at which the bubbles undergo Brownian motion. Therefore, it is necessary to satisfy the above (a) and (b). It is more preferable that the peak particle diameter of the ultrafine bubbles is 40 to 1000 nm, and that the number-average particle diameter of the 10 to 1000 nm bubble particles is 60 to 200 nm. By keeping the diameter within this range, the contact area between the formed recesses and the external additive particles becomes more appropriate, and the adhesion rate of the external additive particles is further improved.

[0037] When the number-average particle size of the UFB is less than 50 nm, it is presumed that the recesses formed on the toner particle surface are small relative to the external additive particles, and a contact area sufficient for achieving a sufficient adhesion rate cannot be obtained. Furthermore, when the number-average particle size of the UFB particles in the water exceeds 800 nm, the diameter approaches the size at which the bubbles undergo Brownian motion, making it difficult for the bubbles to exist stably in the water. Therefore, it is thought that the number of bubbles decreases during the time between mixing the toner particle raw material and the UFB water and feeding it into the kneader.

[0038] UFB contains oxygen. Compared to other gases, oxygen bubbles have a lower surface tension, which is thought to prolong the time the bubbles remain in water. If UFB contains oxygen, it may also contain other gases. UFB may contain air as long as it satisfies the dissolved oxygen concentration described below. The gas may be at least one gas selected from the group consisting of rare gases, nitrogen gas, carbon dioxide, ozone gas, and air. It is desirable to store UFB water in a sealed state in a low-temperature environment at 10°C or below.

[0039] The mixture containing the toner particle raw materials contains 1.0 to 30.0 parts by mass or less of UFB water relative to 100 parts by mass of the toner particle raw materials to be melted and kneaded. When the amount of UFB water is 1.0 to 30.0 parts by mass or less relative to 100 parts by mass of the toner particle raw materials, a sufficient number of recesses are formed to cause the external additive particles to adhere.

[0040] If the amount of UFB water is less than 1.0 part by mass, the liquid does not reach the surface of the toner particle raw material sufficiently, so the number of recesses formed on the toner particle surface is small, and the external additive particles do not adhere sufficiently. Does not appear. When the amount of UFB water exceeds 30.0 parts by mass, the adhesion rate of external additive particles increases as the number of recesses on the toner particle surface increases, but the amount of external additive particles that transfer to the photoreceptor after long-term use decreases. As a result, the layer formed by the accumulation of external additive particles between the cleaning blades (hereinafter referred to as the accumulation layer) becomes so thin that the external additive particles slip through, making it impossible to consistently output high-quality images. The content of UFB water is preferably 5.0 to 25.0 parts by mass, and more preferably 10.0 to 20.0 parts by mass, relative to 100 parts by mass of the toner particle raw material.

[0041] In addition, UFB water is 1.0 x 10 4 It is necessary for UFB water to contain 1.0 x 10 ultrafine bubbles / mL or more. 4 When the number density of UFB is 1.0×10 or more, the depressions on the surface of the toner particles are sufficiently formed, and the adhesion rate of the external additive particles is improved.4 If the number density of UFB is less than 1.0 × 10 / mL, the number of recesses is insufficient, and it is thought that the adhesion rate of the external additive particles cannot be sufficiently improved. 4 The number of cells / mL must be 1.0 x 10 5 8.0 × 10 5 Although there is no particular upper limit, from the viewpoint of productivity, the number density of bubbles is preferably, for example, 3.0 × 10 10 pcs / mL or less, 2.0×10 10 Preferably, it is less than 1 / mL.

[0042] Furthermore, the dissolved oxygen concentration in the water in which the ultrafine bubbles are dispersed is 10 mg / L or higher. When the dissolved oxygen concentration is 10 mg / L or higher, the surface tension of the bubbles becomes appropriate, and the bubbles tend to remain in the water and during melt-kneading. Therefore, voids resulting from the UFB are likely to form in the kneaded product, resulting in recesses on the surfaces of the toner particles after the pulverization process and improving the adhesion rate of the external additive particles. When the dissolved oxygen concentration is less than 10 mg / L, it is believed that the amount of oxygen in the bubbles is low. As a result, the surface tension of the bubbles is high, making it difficult for the bubbles to be retained during melt-kneading, and therefore it is believed that voids are less likely to form in the kneaded product. The dissolved oxygen concentration is preferably 15 to 50 mg / L, more preferably 20 to 40 mg / L, and even more preferably 25 to 35 mg / L.

[0043] <Measurement of number average bubble diameter and number density of UFB> The number average particle size of the bubbles and the number density of the UFBs were measured as follows. The average particle size of bubbles in the prepared UFB water was measured on a number basis using a particle size distribution analyzer (product name "SALD-7500nano" manufactured by Shimadzu Corporation). The batch cell (SALD-BC75) for the SALD-7500nano connected to the analyzer was filled with UFB water, and the refractive index of the particles was set to 1.25-0.00i (i is a complex number). The measurement range of 10 nm to 3000 nm was analyzed using the accompanying software (WingSALD II). The position of the peak particle size was then confirmed, and the number-average particle size for particles with a particle size of 10 nm to 1000 nm was calculated.

[0044] Additionally, the number density of UFBs below 1000 nm was calculated using a nanotracking particle size analyzer (product name "Nanosight NS300" manufactured by Malvern Panalytical). UFB water was loaded into the sample chamber of the Nanosight unit, and a video was recorded for 60 seconds at a frame rate of 25 fps. The particle movement was analyzed using the accompanying software (NTA software version 3.2) to calculate the number density (number / mL) of bubbles between 10 nm and 1000 nm.

[0045] <Measurement of dissolved oxygen concentration> The dissolved oxygen concentration is measured under conditions of 1 atmosphere and 30° C. Specifically, the measurement is performed using a dissolved oxygen concentration meter (optical dissolved oxygen concentration meter, FDO Multi3510 model (manufactured by WTW (W.T.W.))).

[0046] <Preparation of ultra-fine bubble water> The means for producing water containing UFBs is not particularly limited, and any known method can be used as long as it can produce water containing bubbles with the desired particle size and particle concentration. For example, water containing fine bubbles can be produced using known devices for producing water containing fine bubbles, such as the fine bubble generating nozzle described in JP 2014-104441 A or the fluid mixing device described in WO 2009 / 088085 A. By appropriately setting the operating conditions of these devices, it is possible to obtain bubble-containing water in which the particle size distribution of the bubbles is controlled within the desired range.

[0047] Alternatively, bubble-containing water can be produced by using a liquid ejection head, as described in JP 2001-301180 A, which applies thermal energy to a liquid to eject it, to generate bubbles through film boiling. By appropriately setting the film boiling conditions, bubble-containing water can be obtained in which the particle size distribution of the bubbles is controlled within a desired range. Furthermore, commercially available (for research use) bubble-containing water (e.g., products under the trade names "High Density Ultrafine Bubble" and "Ultra High Density Ultrafine Bubble" (both manufactured by Nanox)) may also be used. The resulting UFB water is added to a mixture containing raw toner particle material before melt-kneading to produce the toner.

[0048] <External additive particles> The toner has external additive particles present on the surface of the toner particles. Examples of the external additive particles include inorganic fine particles such as inorganic oxide fine particles. The external additive particles are preferably inorganic fine particles (inorganic fine powder) such as silica, titanium oxide, or aluminum oxide, but may also be resin fine particles. The inorganic fine particles or resin fine particles are preferably hydrophobized with a hydrophobizing agent such as a silane compound, silicone oil, or a mixture thereof.

[0049] As an external additive to improve fluidity, 2 / g or more 400m 2 In order to stably output high-quality images during long-term use, inorganic fine particles with a specific surface area of ​​10 m or less are preferred. 2 / g or more 50m 2 In order to simultaneously improve the fluidity of the toner and the image stability during long-term use, inorganic fine particles having a specific surface area within the above range may be used in combination.

[0050] The external additive is preferably added in an amount of 0.1 to 10.0 parts by mass relative to 100 parts by mass of toner particles. The toner particles and the external additive can be mixed using a known mixer such as a Henschel mixer.

[0051] The external additive particles preferably contain external additive particles (external additive particles L) having a particle size distribution peak in the range of 50 nm to 300 nm, with the number average particle size of the primary particles in the range of 50 nm to 300 nm being 50 to 200 nm (more preferably 70 to 150 nm). By having the particle size in this range, the contact area between the external additive particles and the recesses on the toner particle surface becomes suitable while the toner fluidity remains appropriate, and the adhesion rate of the external additive particles is further improved. The amount of the external additive particles L added is preferably 0.1 to 5.0 parts by mass, more preferably 1.0 to 3.0 parts by mass, relative to 100 parts by mass of the toner particles.

[0052] When the number average particle size of the primary particles of the external additive particles having a particle size in the range of 50 nm to 300 nm is A and the number average particle size of the ultrafine bubbles having a particle size in the range of 10 nm to 1000 nm is B, it is preferable that B / A is 0.40 to 1.80. This range ensures a more appropriate contact area between the external additive particles and the recesses on the surface of the toner particles, thereby further improving the adhesion rate of the external additive particles.

[0053] The external additive particles preferably contain external additive particles (external additive particles S) having a particle size distribution peak in the range of 20 nm to 50 nm (more preferably 30 to 50 nm). This results in a more appropriate coverage of the external additive particles on the toner. In addition, over long-term use, the change in the adhesion rate of the external additive particles becomes smaller, and the increase in the adhesive force between the toner and the transfer member is suppressed, resulting in more stable transfer performance. The amount of the external additive particles S added is preferably 0.1 to 5.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, relative to 100 parts by mass of the toner particles.

[0054] The external additive particles preferably include external additive particles having a number-average particle size of primary particles of 20 nm or more and less than 50 nm (more preferably 30 nm or more and less than 50 nm).Furthermore, the external additive particles preferably include both external additive particles having a number-average particle size of primary particles of 50 to 200 nm (more preferably 70 to 150 nm) and external additive particles having a number-average particle size of primary particles of 20 nm or more and less than 50 nm (more preferably 30 nm or more and less than 50 nm).

[0055] <Method for measuring peak particle size and number average particle size in the range of 50 nm to 300 nm of external additive particles> The peak particle size and number-average particle size of the external additive particles can be determined by centrifugal sedimentation. Specifically, 0.01 g of dried external additive particles are placed in a 25 ml glass vial, and 0.2 g of 5% Triton solution and 19.8 g of RO water are added to prepare a solution. Next, the tip of the probe of an ultrasonic disperser is immersed in the solution, and ultrasonic dispersion is performed at an output of 20 W for 15 minutes to obtain a dispersion. Next, using this dispersion, the peak particle size and number-average particle size of primary particles in the range of 50 nm to 300 nm are measured using a CPS Instruments DC24000 centrifugal sedimentation particle size distribution analyzer. The disk rotation speed is set to 18,000 rpm, and the true density is 1.3 g / cm. 3 Before measurement, the instrument is calibrated using polyvinyl chloride particles with an average particle size of 0.476 μm.

[0056] <Toner manufacturing method> The procedure for producing the toner will be described. (i) a melt-kneading step of melt-kneading a mixture containing the toner particle raw material containing the binder resin to obtain a kneaded product; (ii) a pulverization step of pulverizing the kneaded mixture to obtain toner particles; and (iii) an external addition step of externally adding the external additive particles to the toner particles; It has. The timing of adding UFB water is not particularly limited as long as the mixture containing the toner particle raw materials contains UFB water during melt-kneading. For example, UFB water can be added to the mixture containing the toner particle raw materials in a raw material mixing step in which the toner particle raw materials are mixed before melt-kneading.

[0057] <Raw material mixing process> In the raw material mixing process, predetermined amounts of binder resin, UFB water, and, if necessary, colorant, etc. are weighed, blended, and mixed to obtain a mixture containing toner particle raw materials. The mixing device is not particularly limited, but examples include a Henschel mixer (manufactured by Nippon Coke Company), a Supermixer (manufactured by Kawata Corporation), a Ribocone (manufactured by Okawara Manufacturing Co., Ltd.), a Nauta mixer, a Turbulizer, and a Cyclomix (manufactured by Hosokawa Micron Corporation), a Spiral Pin Mixer (manufactured by Pacific Machinery Works, Ltd.), and a Loedige mixer (manufactured by Matsubo Corporation).

[0058] <Melting and kneading process> A mixture containing raw toner particle materials is melt-kneaded, for example, using a twin-screw extruder. In the melt-kneading process, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used, with a single-screw or twin-screw extruder being preferred due to its advantage of enabling continuous production. The melt-kneading temperature is preferably about 100 to 200°C.

[0059] The melt kneading device is not particularly limited, but examples thereof include a pressure kneader, a Banbury kneader, and the like. Examples include a batch kneader such as a mixer, a TEM extruder (manufactured by Toshiba Machine Co., Ltd.), a TEX twin-screw kneader (manufactured by The Japan Steel Works, Ltd.), a PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.), and a Kneedex (manufactured by Mitsui Mining Co., Ltd.) Continuous kneaders such as single-screw or twin-screw extruders are preferred over batch kneaders because of their advantages such as the ability to perform continuous production.

[0060] <Crushing process> The pulverization step is a step in which the kneaded product obtained after the melt-kneading step is cooled to a pulverizable hardness, and then mechanically pulverized to a toner particle size using a known pulverizer such as an impact plate jet mill, a fluidized bed jet mill, or a rotary mechanical mill. From the viewpoint of pulverization efficiency, it is desirable to use a fluidized bed jet mill as the pulverizer.

[0061] Examples of grinding machines include counter jet mills, micron jets, and inomizers (manufactured by Hosokawa Micron Corporation); IDS-type mills and PJM jet grinders (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); cross jet mills (manufactured by Kurimoto Iron Works); Urmax (manufactured by Nisso Engineering Co., Ltd.); SK Jet-O-Mill (manufactured by Seishin Enterprise Co., Ltd.); Cryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.); and Super Rotor (manufactured by Nisshin Engineering Co., Ltd.).

[0062] <Classification process> If necessary, a classification step may be carried out to classify the toner particles. The classification step is a step in which the finely pulverized product obtained in the pulverization step is classified to obtain toner particles having a desired particle size distribution. The classifier used for classification may be a known device such as an air classifier, an inertial classifier, or a sieve classifier. Specific examples include Cruseal, Micron Classifier, and Spedic Classifier (manufactured by Seishin Enterprise Co., Ltd.), Turbo Classifier (manufactured by Nisshin Engineering Inc.), Micron Separator, Turboflex (ATP), and TSP Separator (manufactured by Hosokawa Micron Corporation), Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), and YM Microcut (manufactured by Yaskawa Corporation).

[0063] <External addition process> External additive particles are added to the toner particles produced through the above process. For example, inorganic fine particles such as silica, alumina, titania, etc., or resin fine particles such as vinyl resin, polyester resin, or silicone resin may be added by applying shear force in a dry state. These inorganic fine particles and resin fine particles function as external additives such as flow aids and cleaning aids. The weight average particle diameter of the toner is preferably 3.0 μm or more and 20.0 μm or less, and more preferably 4.0 μm or more and 10.0 μm or less. [Example]

[0064] The present disclosure will be described in more detail below using examples and comparative examples, but these are not intended to limit the present disclosure in any way.

[0065] <Production of ultra-fine bubble water> The UFB water used in the examples and comparative examples of the present disclosure was prepared by the method described below. In this disclosure, UFB water with a high number density was produced by film boiling due to sudden heat generation or by providing a circulation mechanism, as described in the patent document (JP 2019-42732 A). In addition, the number density of bubbles in the UFB water was appropriately adjusted by diluting the produced UFB water with pure water or concentrating it under reduced pressure using a rotary evaporator. The particle size and number density of bubbles in the prepared UFB water are shown in Table 1.

[0066] (Oxygen UFB Water 1) Oxygen UFB water 1 is commercially available (for research use) oxygen UFB water (product name "Oxygen Ultra Fine Bubble Water", manufactured by Nanox).

[0067] (Oxygen UFB water 2-8, 10-12, Fine bubble water 1) Using a micro-nano bubble generator (OM4-MDG-05, manufactured by Auratech), oxygen or air bubbles were added to pure water at 25°C and a flow rate of 1.8 L / min. This process was repeated five times for 10 hours, making up one cycle. The number of passes and repetitions of this process were adjusted appropriately, and the resulting solution was diluted with pure water to obtain oxygen UFB water 2-8, 10-12, and air fine bubble water 1.

[0068] (Oxygen UFB Water 9) Oxygen UFB water 1 was diluted with pure water and concentrated under reduced pressure using a rotary evaporator (N-1300E-W, manufactured by Tokyo Rikakikai) to adjust the number density of UFB to the value shown in Table 1, thereby obtaining oxygen UFB water 9.

[0069] (Air UFB Water 1) Air UFB water 1 is commercially available (for research use) air UFB water (product name "Air Ultra Fine Bubble Water", manufactured by Nanox).

[0070] Details of the UFB water used in the examples and comparative examples are shown in Table 1.

[0071] [Table 1]

[0072] <Production of Toner Particles 1> Amorphous polyester A: 81.0 parts by mass (Monomer composition: ethylene glycol, terephthalic acid) ·Pigment Blue 15:3: 10.0 parts by mass Synthetic wax 1: 9.0 parts by weight (hydrocarbon wax, melting point 90℃) ·Oxygen UFB water 1: 15.0 parts by mass The above materials were mixed in a Henschel mixer (FM-75 model, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 20 s. -1 The mixture was then kneaded at 130°C in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation). The resulting kneaded material was cooled and coarsely pulverized in a pin mill to a weight average particle size of 100 μm or less to obtain a coarsely pulverized material. The resulting coarsely pulverized material was finely pulverized in a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.) by adjusting the rotation speed and number of passes to obtain the target particle size. Further, classification was performed using a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) to obtain toner particles. The operating conditions of the rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) were such that the rotation speed was adjusted to obtain the target particle size and particle size distribution.

[0073] <Production of Toner Particles 2 to 16 and Comparative Toner Particles 1 to 8> Toner particles 2 to 16 and comparative toner particles 1 to 8 were obtained in the same manner as in the production example of toner particles 1, except that in the production of toner particles 1, the type and amount (parts by mass) of water added were changed as shown in Table 2.

[0074] [Table 2]

[0075] <Production of Toner 1> Toner particles 1: 100 parts by mass Silica fine particles L: 1.8 parts by mass Silica fine particles S: 0.8 parts by mass The above materials were mixed in a Henschel mixer (FM-75 model, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 30 s -1 The mixture was mixed for a rotation time of 10 minutes to obtain Toner 1. The toner particle size (D3) was 6.5 μm. Silica fine particles L are external additive particles whose particle size distribution has a peak in the range of 50 nm to 300 nm, and the number-average particle size of the primary particles in the range of 50 nm to 300 nm is 110 nm, and which have been hydrophobized with silicone oil. Silica fine particles S are external additive particles whose particle size distribution has a peak in the range of 20 nm to 50 nm, and the number-average particle size of the primary particles is 40 nm, and which have been hydrophobized with silicone oil.

[0076] <Production of Toners 2 to 16 and Comparative Toners 1 to 8> Toners 2 to 16 and comparative toners 1 to 8 were obtained in the same manner as in the production example of toner 1, except that in the production of toner 1, the type of external additive particles added was changed as shown in Table 3.

[0077] [Table 3]

[0078] <Magnetic Carrier 1 Manufacturing Example> Number average particle size: 0.30 μm, magnetization strength: 65 Am under a magnetic field of 1000 / 4π (kA / m) 2 / kg) of magnetite 1 Number average particle size: 0.50 μm, magnetization strength: 65 Am under a magnetic field of 1000 / 4π (kA / m) 2 / kg) magnetite2 To 100 parts of each of the above materials, 4.0 parts of a silane compound (3-(2-aminoethylaminopropyl)trimethoxysilane) was added, and the mixture was mixed and stirred at high speed in a container at 100° C. or higher to treat each of the fine particles.

[0079] Phenol: 10% by weight Formaldehyde solution: 6% by mass (40% by mass of formaldehyde, 10% by mass of methanol, 50% by mass of water) Magnetite treated with the above silane compound 1: 58 mass% Magnetite 2 treated with the above silane compound: 26% by mass 100 parts of the above material, 5 parts of a 28% by weight aqueous ammonia solution, and 20 parts of water were placed in a flask, and the mixture was heated to 85°C over 30 minutes while stirring and mixing, and then maintained at that temperature for 3 hours to polymerize and harden the resulting phenolic resin. The hardened phenolic resin was then cooled to 30°C, and water was added. The supernatant was removed, and the precipitate was washed with water and air-dried. This was then dried under reduced pressure (5 mmHg or less) at 60°C to obtain spherical magnetic carrier 1 with dispersed magnetic material. The volume-based 50% particle size (D50) of magnetic carrier 1 was 34.2 μm.

[0080] <Manufacturing example of two-component developer 1> To 92.0 parts of magnetic carrier 1, 8.0 parts of toner 1 were added and mixed in a V-type mixer (V-20, manufactured by Seishin Enterprises) to obtain two-component developer 1.

[0081] <Production Examples of Two-Component Developers 2 to 16 and Comparative Two-Component Developers 1 to 8> In the production example of two-component developer 1, the same operation was carried out except that the combinations were changed to toners 2 to 16 and comparative toners 1 to 8, to obtain two-component developers 2 to 16 and comparative two-component developers 1 to 8.

[0082] Using the two-component developers 1 to 16 and the comparative two-component developers 1 to 8, image density unevenness and transfer stability were evaluated by the following methods.

[0083] <Image density unevenness evaluation> A modified Canon imageRUNNER ADVANCE C5560 full-color copier was used as the image forming apparatus, and the above-mentioned two-component developer 1 was placed in the cyan developer of the image forming apparatus, and the cyan toner bottle was filled with toner 1, and the evaluation described below was carried out. The modification involved removing the mechanism for discharging excess magnetic carrier from the developer.

[0084] The amount of toner on the paper in a FFh image (solid image) is 0.45 mg / cm 2 The value was adjusted so that it was as follows: FFh is the 256 gradations expressed in hexadecimal, with 00h being the 1st gradation of the 256 gradations (white background) and FF being the 256th gradation of the 256 gradations (solid area). The test was carried out in a normal temperature and low humidity (NL) environment (temperature 23°C, relative humidity 5%).

[0085] The evaluation paper was copy paper GF-C081 (A4, basis weight 81.4 g / m 2 (sold by Canon Marketing Japan Inc.) was used. First, 100 sheets were printed with an image ratio of 10%, with vertical bands parallel to the paper feed direction and the rest of the image being white. The vertical bands were FFh images (solid images). During continuous paper feed, the sheets were fed under the same development and transfer conditions (no calibration) as the first sheet. After 100 sheets had been fed, a full-face halftone image (80h) was printed and used to evaluate initial image density unevenness.

[0086] After that, 10,000 more images were printed with vertical bands parallel to the paper feed direction and white areas other than the vertical bands at an image ratio of 10%. During the continuous paper feed, the paper was fed under the same development and transfer conditions (without calibration) as the first sheet. After passing 10,000 sheets, a full-page halftone image (80h) was printed and used to evaluate image density unevenness after long-term use.

[0087] An X-Rite color reflection densitometer (500 series: manufactured by X-Rite) was used to measure the image density of the part where the vertical bands were printed and the part where the white background was printed in the halftone image (80 hours). The difference Δ between the two image densities was taken as the image density unevenness. The difference Δ between the initial (after 100 sheets) and long-term use (after 10,000 sheets) was ranked according to the following criteria. The evaluation results are shown in Table 4.

[0088] (Evaluation criteria) A: Less than 0.01 (very good) B+: 0.01 or more and less than 0.02 (very good) B: 0.02 or more and less than 0.03 (very good) B-: 0.03 or more and less than 0.04 (very good) C+: 0.04 or more and less than 0.05 C: 0.05 or more and less than 0.06 C-: 0.06 or more and less than 0.07 D+: 0.07 or more and less than 0.08 D: 0.08 or more and less than 0.09 D-: 0.09 or more and less than 0.10 E+: 0.10 or more and less than 0.11 E: 0.11 or more and less than 0.12 E-: 0.12 or more

[0089] [Table 4]

[0090] <Evaluation of transcription stability> A durability test was conducted using a modified Canon imageRUNNER ADVANCE C5560 full-color copier at room temperature and humidity (23°C / 50%RH) with a low print rate (1%). The developer carrier was not replaced (auto-refresh mechanism) during long-term use. The evaluation paper was CS-680 (68.0 g / m 2 ) (sold by Canon Marketing Japan) was used. The long-term use was for A4 charts, with 100,000 sheets passed continuously. 2 The toner was developed onto the photosensitive drum, the machine was shut down during the transfer process, and the residual toner remaining on the photosensitive drum was taped off. The density was measured and the transfer efficiency was calculated from the value. The transfer current was set to the optimum value according to the toner charge amount. The density was measured using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite).

[0091] (Evaluation criteria) A: Transfer efficiency is 96% or more (very good) B+: Transfer efficiency is between 95% and 96% (very good) B: Transfer efficiency is 94% or more but less than 95% (very good) B-: Transfer efficiency is 93% or more but less than 94% (very good) C+: Transfer efficiency is 92% or more but less than 93% C: Transfer efficiency is 91% or more but less than 92% C-: Transfer efficiency is 90% or more but less than 91% D+: Transfer efficiency is between 89% and 90% D: Transfer efficiency is 88% or more but less than 89% D-: Transfer efficiency is 87% or more but less than 88% E+: Transfer efficiency is between 86% and 87% E: Transfer efficiency is 85% or more but less than 86% E-: Transfer efficiency is less than 85%

[0092] [Table 5]

[0093] The present disclosure relates to the following methods: (Method 1) A method for producing a toner having toner particles containing a binder resin and external additive particles present on the surfaces of the toner particles, the method comprising: The manufacturing method comprises: (i) a melt-kneading step of melt-kneading a mixture containing the toner particle raw material containing the binder resin to obtain a kneaded product; (ii) a pulverization step of pulverizing the kneaded mixture to obtain toner particles; and (iii) an external addition step of externally adding the external additive particles to the toner particles; and the mixture contains 1.0 to 30.0 parts by mass of a liquid relative to 100 parts by mass of the toner particle raw material to be melt-kneaded, the liquid is water in which ultrafine bubbles containing oxygen are dispersed, the dissolved oxygen concentration in the water in which the ultrafine bubbles are dispersed is 10 mg / L or more; The particle size distribution of the bubbles in the water in which the ultrafine bubbles are dispersed is as follows: (a) a peak particle size of 10 to 1000 nm; (b) the number average particle size of the bubble particles having a particle size of 10 to 1000 nm is 50 to 800 nm; The water in which the ultra-fine bubbles are dispersed has a particle size of 1.0 x 10 4 1. A method for producing a toner, comprising: (Method 2) The method for producing a toner according to Method 1, wherein the external additive particles have a particle size distribution peak in the range of 50 nm to 300 nm, and the number average particle size of primary particles in the range of 50 nm to 300 nm is 70 to 150 nm. (Method 3) 3. The toner manufacturing method according to Method 1 or 2, wherein the external additive particles include external additive particles having a particle size distribution peak in the range of 20 nm to 50 nm. (Method 4) 4. The toner manufacturing method according to any one of methods 1 to 3, wherein the ultrafine bubbles have a peak particle size of 40 to 1000 nm, and the number average particle size of the 10 nm to 1000 nm bubble particles is 60 to 200 nm. (Method 5) When the number average particle size of the primary particles of the external additive particles having a particle size in the range of 50 nm to 300 nm is defined as A and the number average particle size of the ultra-fine bubbles having a particle size in the range of 10 nm to 1000 nm is defined as B, 5. The toner manufacturing method according to any one of methods 1 to 4, wherein B / A is 0.40 to 1.80.

Claims

1. A method for producing a toner having toner particles containing a binder resin and external additive particles present on the surfaces of the toner particles, the method comprising: The manufacturing method comprises: (i) a melt-kneading step of melt-kneading a mixture containing the toner particle raw material containing the binder resin to obtain a kneaded product; (ii) a pulverization step of pulverizing the kneaded mixture to obtain toner particles; and (iii) an external addition step of externally adding the external additive particles to the toner particles; and the mixture contains 1.0 to 30.0 parts by mass of a liquid relative to 100 parts by mass of the toner particle raw material to be melt-kneaded, the liquid is water in which ultrafine bubbles containing oxygen are dispersed, the dissolved oxygen concentration in the water in which the ultra-fine bubbles are dispersed is 10 mg / L or more; The particle size distribution of the bubbles in the water in which the ultrafine bubbles are dispersed is as follows: (a) a peak particle size of 10 to 1000 nm; (b) the number average particle size of the bubble particles having a particle size of 10 to 1000 nm is 50 to 800 nm; The water in which the ultra-fine bubbles are dispersed has a concentration of 1.0 x 10 ４ 1. A toner manufacturing method comprising:

2. 2. The method for producing a toner according to claim 1, wherein the external additive particles have a particle size distribution peak in the range of 50 nm to 300 nm, and the number average particle size of primary particles in the range of 50 nm to 300 nm is 70 to 150 nm.

3. 3. The method for producing a toner according to claim 1, wherein the external additive particles include external additive particles having a particle size distribution peak in the range of 20 nm to 50 nm.

4. 3. The method for producing a toner according to claim 1, wherein the ultrafine bubbles have a peak particle size of 40 to 1000 nm, and the number-average particle size of the 10 nm to 1000 nm bubble particles is 60 to 200 nm.

5. When the number average particle size of the primary particles of the external additive particles having a particle size in the range of 50 nm to 300 nm is defined as A and the number average particle size of the ultra-fine bubbles having a particle size in the range of 10 nm to 1000 nm is defined as B, 3. The method for producing a toner according to claim 1, wherein B / A is 0.40 to 1.80.

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