Toner manufacturing method and toner

Abstract

To provide a method for manufacturing a toner excellent in charge stability and high in transfer efficiency.SOLUTION: A method for manufacturing toner including: the first step of filtering toner particles obtained by a wet manufacturing method; the second step of compressing the toner particles to cause water to permeate into the toner particles; and the third step of compressing the toner particles to aerating compressed air into to the toner particles satisfies the following conditions (1) and (2). The condition (1): the temperature T of the water permeating in the second step satisfies 10°C≤T≤35°C, and the condition (2): a compression pressure P1 in the second step and a compression pressure P2 in the third step satisfy 0.2 MPa≤P1<P2≤0.8 MPa.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a toner, and to a toner. [Background technology]

[0002] Patent Document 1 proposes "a method for producing a polymerization toner, which comprises salting out / fusing at least resin fine particles in an aqueous medium to form colored particles, filtering the particles from the aqueous medium, and drying the particles, and which is characterized in that a filter press method is used in the step of filtering the colored particles from the aqueous medium." Patent Document 2 proposes "a method for producing polymerized toner particles, comprising polymerizing a polymerizable monomer composition containing at least a polymerizable monomer and a colorant in a liquid medium to produce colored resin particles, filtering the colored resin particles from the liquid medium, and drying the particles, wherein the filtering of the colored resin particles from the liquid medium is carried out by a filter press method." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-221823 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-010341 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a toner manufacturing method including a first step of filtering toner particles obtained by a wet process, a second step of passing water through the toner particles after squeezing the toner particles, and a third step of passing compressed air through the toner particles after squeezing the toner particles. In the manufacturing method of the toner, when the temperature T of the water passed through in the second step satisfies 10 °C > T, or T > 35 °C, or when P1 and P2 are less than 0.2 MPa, or when P1 and P2 are less than 0.2 MPa and exceed 0.8 MPa, or when the relationship P1 ≧ P2 is satisfied, it is to provide a toner manufacturing method excellent in charging stability and high in transfer efficiency as compared with these cases.

Means for Solving the Problems

[0005] The above problems are solved by the following means. That is <1> A first step of filtering toner particles obtained by a wet process, a second step of passing water through the toner particles after squeezing the toner particles, a third step of passing compressed air through the toner particles after squeezing the toner particles, and including a toner manufacturing method satisfying the following conditions (1) and (2). Condition (1): The temperature T of the water passed through in the second step satisfies 10 °C ≦ T ≦ 35 °C. Condition (2): The squeezing pressure P1 in the second step and the squeezing pressure P2 in the third step satisfy 0.2 MPa ≦ P1 < P2 ≦ 0.8 MPa. <2> The toner manufacturing method according to <1> above, in which in the second step, water is passed through until the conductivity of the filtrate becomes 0.10 mS / cm or less. <3> The toner manufacturing method according to <2> above, in which the amount of water passed through in the second step is 600 parts by mass or more with respect to 100 parts by mass of the toner particles. <4> The toner manufacturing method according to any one of <1> to <3> above, in which the difference (P2 - P1) between the squeezing pressure P1 in the second step and the squeezing pressure P2 in the third step is 0.05 MPa or more and 0.4 MPa or less. <5> The third step is performed for a ventilation time of 60 seconds or more. <1> ~ <4> 10. The method for producing the toner according to claim 9, wherein the toner is a fluororesin. <6> The pressure of the compressed air in the third step is 0.2 MPa or more and 0.6 MPa or less. <5> 10. The method for producing the toner according to claim 9. <7> The method of aerating compressed air multiple times in the third step <1> ~ <6> 10. The method for producing the toner according to claim 9, wherein the toner is a fluororesin. <8> In the third step, compressed air is passed through the toner particles to reduce the amount of moisture contained in the toner particles to 45% by mass or less based on the total amount of the toner particles. <1> ~ <7> 10. The method for producing the toner according to claim 9, wherein the toner is a fluororesin. <9> The content of ammonium ions measured by the following procedure is 1.0 mg / L or less, and the net intensity of Na element in fluorescent X-ray analysis is 0.50 kcps or less, and the net intensity of S element is 1.50 kcps or less. <1> ~ <8> 10. The method for producing the toner according to claim 9, wherein the toner is a fluororesin. (Procedure for measuring ammonium ion content) 0.5 g of toner particles are weighed and dispersed in 100 g of ion-exchanged water containing 0.1 g of a nonionic surfactant, equivalent to 20% by mass of the total toner particles, and the dispersion is carried out for 30 minutes using an ultrasonic disperser in a thermostatic chamber controlled at 30±1°C. The liquid after ultrasonic dispersion is subjected to solid-liquid separation by suction filtration to remove the toner particles, and the amount of ammonium contained in the resulting filtrate is measured using ion chromatography. The ion chromatography used is an ICS-2000 manufactured by Nippon Dionex Corporation, and analysis is carried out under the following conditions. Cation separation column: Nippon Dionex, IonPacCS12A Cation guard column: Nippon Dionex, IonPacCG12A Eluent: methanesulfonic acid 20 mM (mmol / l) ·Flow rate: 1ml / min ·Temperature: 30℃ Detection method: Electrical conductivity method (suppressor type) <10> The ammonium ion content measured by the following procedure is 1.0 mg / L or less, The net intensity of Na element in X-ray fluorescence analysis is 0.50 kcps or less, A toner having a net intensity of S element of 1.50 kcps or less. (Procedure for measuring ammonium ion content) 0.5 g of toner particles are weighed and dispersed in 100 g of ion-exchanged water containing 0.1 g of a nonionic surfactant, equivalent to 20% by mass of the total toner particles, and the dispersion is carried out for 30 minutes using an ultrasonic disperser in a thermostatic chamber controlled at 30±1°C. The liquid after ultrasonic dispersion is subjected to solid-liquid separation by suction filtration to remove the toner particles, and the amount of ammonium contained in the resulting filtrate is measured using ion chromatography. The ion chromatography used is an ICS-2000 manufactured by Nippon Dionex Corporation, and analysis is carried out under the following conditions. Cation separation column: Nippon Dionex, IonPacCS12A Cation guard column: Nippon Dionex, IonPacCG12A Eluent: methanesulfonic acid 20 mM (mmol / l) ·Flow rate: 1ml / min ·Temperature: 30℃ Detection method: Electrical conductivity method (suppressor type) <11> The content of the ammonium ion is 0.1 mg / L or more and 1.0 mg / L or less. <10> The toner according to claim 1. [Effects of the Invention]

[0006] <1> According to the invention, in a method for producing toner including a first step of filtering toner particles obtained by a wet production method, a second step of squeezing the toner particles and then passing water through the toner particles, and a third step of squeezing the toner particles and then passing compressed air through the toner particles, the method provides a toner production method that has excellent charging stability and high transfer efficiency compared to when the temperature T of the water passed through in the second step satisfies 10°C > T or T > 35°C, or when P1 and P2 are less than 0.2 MPa, or when P1 and P2 are less than 0.2 MPa and exceed 0.8 MPa, or when the relationship P1≧P2 is satisfied. <2> According to the invention, a method for producing a toner having excellent charging stability and high transfer efficiency is provided, compared to when the water flow is stopped when the conductivity of the filtrate exceeds 0.10 mS / cm in the second step. <3> According to the present invention, a method for producing a toner is provided which has excellent charging stability and high transfer efficiency compared to when the amount of water passed in the second step is less than 600 parts by mass per 100 parts by mass of toner particles. <4> According to the present invention, a method for producing a toner having excellent charging stability and high transfer efficiency is provided, compared to when the difference (P2-P1) between the compression pressure P1 in the second step and the compression pressure P2 in the third step is less than 0.1 MPa or exceeds 0.4 MPa. <5> According to the invention, a method for producing a toner having excellent charge stability and high transfer efficiency is provided, compared to when the aeration time in the third step is less than 60 seconds. <6> According to the invention, a method for producing a toner having excellent charge stability and high transfer efficiency is provided, compared to when the pressure of the compressed air in the third step is less than 0.2 MPa or more than 0.6 MPa. <7> According to the invention, a method for producing a toner that is superior in charging stability and transfer efficiency compared to when compressed air is passed through once in the third step is provided. <8> According to the invention, a method for producing a toner having excellent charging stability and high transfer efficiency is provided, compared to when compressed air is passed through the toner particles in the third step to set the amount of moisture contained in the toner particles to a value exceeding 45% by mass of the entire toner particles. <9> According to the present invention, a method for producing a toner having excellent charge stability and high transfer efficiency is provided, compared to a method for producing a toner having an ammonium ion content of more than 1.0 mg / L as measured by the procedure described below, a method for producing a toner having a net intensity of Na element of more than 0.50 kcps in fluorescent X-ray analysis, or a method for producing a toner having a net intensity of S element of more than 1.5 kcps. According to the invention according to <10> or <11>, when the ammonium ion content measured by the following procedure exceeds 1.0 mg / L, when the Net intensity of Na element in X-ray fluorescence analysis exceeds 0.50 kcps, or when the Net intensity of S element exceeds 1.5 kcps, a toner having excellent charging stability and high transfer efficiency is provided as compared with the case where these conditions are not met.

Mode for Carrying Out the Invention

[0007] Hereinafter, embodiments which are examples of the present invention will be described. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the invention. In the numerical ranges described step by step in this specification, the upper limit value or lower limit value described in one numerical range may be replaced with the upper limit value or lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in this specification, the upper limit value or lower limit value of the numerical range may be replaced with the value shown in the examples.

[0008] Each component may contain a plurality of corresponding substances. When referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it means the total amount of the plurality of substances present in the composition.

[0009] <Method for Manufacturing Toner> The method for manufacturing a toner according to this embodiment includes a first step of filtering toner particles obtained by a wet method, a second step of passing water through the toner particles after squeezing the toner particles, and a third step of passing compressed air through the toner particles after squeezing the toner particles, and satisfies the following conditions (1) and (2). Condition (1): The temperature T of the water passed through in the second step satisfies 10°C ≤ T ≤ 35°C. Condition (2): The squeezing pressure P1 in the second step and the squeezing pressure P2 in the third step satisfy 0.2 MPa ≤ P1 < P2 ≤ 0.8 MPa.

[0010] The toner manufacturing method according to the present embodiment, due to the above-described configuration, is a method for manufacturing toner that is excellent in charge stability and high in transfer efficiency. The reason for this is presumed to be as follows.

[0011] A wet process for producing toner particles is used as a means for intentionally controlling the shape and surface structure of toner particles. Toner particles produced by a wet process require a washing process to remove impurities (e.g., ions) adhering to the toner particles. A method for washing toner particles using a pressure filter such as a filter press is one example. For example, a method for washing toner particles using a filter press involves squeezing toner particles produced by a wet process and then ventilating the toner particles. However, washing toner particles using a pressure filter can easily leave some of the impurities adhering to the toner particles, which can cause a decrease in the charging stability and transfer efficiency of the toner.

[0012] In the toner manufacturing method according to this embodiment, after the toner particles are compressed, in the second step of passing water over the toner particles, the temperature T of the water passing through satisfies 10°C≦T≦35°C. By setting the temperature T of the water passing through to 10°C or higher, impurities adhering to the toner particles can be more easily removed by passing water through. As a result, the resulting toner has excellent charge stability. Furthermore, by setting the temperature T of the water passing through to 35°C or lower, peeling of the toner particle surface due to the water passing through can be suppressed. As a result, the resulting toner suppresses charge injection during transfer caused by peeling of the toner particle surface, resulting in high transfer efficiency. In addition, in the toner manufacturing method according to this embodiment, the pressing pressure P1 in the second step and the pressing pressure P2 in the third step satisfy 0.2 MPa ≤ P1 < P2 ≤ 0.8 MPa. By setting the pressing pressure P1 and the pressing pressure P2 to 0.2 MPa or more, when pressing the toner particles, a pressure close to uniform is likely to be applied to the entire toner particles. Therefore, the entire toner particles are likely to be cleaned. And by making the pressing pressure P2 greater than the pressing pressure P1, the moisture contained in the toner particles is likely to be removed. By these means, it becomes easier to further remove the impurities contained in the toner particles. And by setting the pressing pressure P1 and the pressing pressure P2 to 0.8 MPa or less, the pressure applied to the toner during pressing does not become too large, so deformation of the toner particles is suppressed. Thereby, a decrease in transfer efficiency due to deformation of the toner particles is suppressed.

[0013] From the above, it is presumed that the toner manufacturing method according to this embodiment is a toner manufacturing method excellent in charging stability and high in transfer efficiency.

[0014] (First Step) The first step is a step of filtering the pre-washing toner particles obtained by a wet manufacturing method. Hereinafter, the toner particles before passing through the second step and the third step are referred to as "pre-washing toner particles". -Pre-washing toner particles- The pre-washing toner particles are pre-washing toner particles manufactured by a wet manufacturing method. Examples of the wet manufacturing method include the coagulation aggregation method, the suspension polymerization method, the dissolution suspension method, and the like. Among these, it is preferable to obtain the pre-washing toner particles by the coagulation aggregation method. Hereinafter, as an example, the manufacturing method of the pre-washing toner particles by the coagulation aggregation method will be described.

[0015] Specifically, for example, when manufacturing the pre-washing toner particles by the coagulation aggregation method, Pre-washed toner particles are manufactured through the following steps: a step of preparing a resin particle dispersion in which resin particles that will become the binder resin are dispersed (resin particle dispersion preparation step); a step of aggregating the resin particles (and other particles, if necessary) in the resin particle dispersion (in a dispersion after mixing other particle dispersions, if necessary) to form aggregated particles (aggregated particle formation step); a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form pre-washed toner particles (fusion and coalescence step); and a step of removing coarse particles (sieving step).

[0016] Each step will be described in detail below. In the following description, a method for obtaining pre-washed toner particles containing a colorant and a release agent will be described, but the colorant and the release agent are used as needed. Of course, other additives than the colorant and the release agent may also be used.

[0017] -Resin particle dispersion preparation process- First, a resin particle dispersion in which resin particles serving as a binder resin are dispersed, as well as a colorant particle dispersion in which colorant particles are dispersed and a release agent particle dispersion in which release agent particles are dispersed are prepared.

[0018] Here, the resin particle dispersion liquid is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0019] Examples of the dispersion medium used in the resin particle dispersion include aqueous media. Examples of aqueous media include water such as distilled water and ion-exchanged water, alcohols, etc. These may be used alone or in combination of two or more.

[0020] Examples of surfactants include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly preferred. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants. The surfactants may be used alone or in combination of two or more.

[0021] In the resin particle dispersion, resin particles can be dispersed in a dispersion medium by a general dispersion method such as a rotary shear homogenizer, a ball mill having a medium, a sand mill, a dyno mill, etc. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion by, for example, a phase inversion emulsification method. The phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, adding a base to the organic continuous phase (O phase) to neutralize it, and then adding an aqueous medium (W phase), thereby converting the resin from W / O to O / W (so-called phase inversion) and forming a discontinuous phase, and dispersing the resin in particulate form in the aqueous medium.

[0022] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably from 0.01 μm to 1 μm, more preferably from 0.04 μm to 0.8 μm, and even more preferably from 0.0.06 μm to 0.6 μm. The volume average particle size of the resin particles is measured using a particle size distribution obtained by measurement with a laser diffraction particle size distribution analyzer (e.g., LA-700 manufactured by Horiba, Ltd.), and the cumulative distribution for the volume of the divided particle size range (channel) is subtracted from the small particle size side, and the particle size at which the cumulative 50% of all particles is measured is defined as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same way.

[0023] The content of resin particles contained in the resin particle dispersion is, for example, preferably from 5% by mass to 50% by mass, and more preferably from 10% by mass to 40% by mass.

[0024] Note that, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same for the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0025] -Agglomerated particle formation process- Next, the colorant particle dispersion and the release agent particle dispersion are mixed together with the resin particle dispersion. Then, in the mixed dispersion, the resin particles, colorant particles, and release agent particles are hetero-aggregated to form aggregated particles containing the resin particles, colorant particles, and release agent particles, which have a diameter close to the diameter of the target toner particles before cleaning.

[0026] Specifically, for example, an aggregating agent is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, a pH of 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. After that, the mixed dispersion is heated to the glass transition temperature of the resin particles (specifically, for example, a temperature of the glass transition temperature of the resin particles -30°C or more and the glass transition temperature -10°C or less), and the particles dispersed in the mixed dispersion are aggregated to form aggregated particles. In the aggregate particle formation step, for example, the above-mentioned aggregating agent may be added to the mixed dispersion at room temperature (e.g., 25°C) while stirring with a rotary shear homogenizer, the pH of the mixed dispersion may be adjusted to an acidic value (e.g., pH 2 or more and 5 or less), and a dispersion stabilizer may be added as necessary, followed by the heating.

[0027] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. In particular, when a metal complex is used as the flocculant, the amount of surfactant used can be reduced and the charging characteristics can be improved. If necessary, an additive that forms a complex or a similar bond with the metal ions of the flocculant may be used, and a chelating agent is preferably used as this additive.

[0028] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. The chelating agent may be a water-soluble chelating agent, such as hydroxycarboxylic acid (e.g., tartaric acid, citric acid, gluconic acid), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), etc. The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, relative to 100 parts by mass of the resin particles.

[0029] -Fusion / unification process- Next, the aggregated particle dispersion liquid in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10 to 30°C higher than the glass transition temperature of the resin particles) to fuse and coalesce the aggregated particles, thereby forming pre-washed toner particles.

[0030] -Sieving process- Before cleaning, the suspension solution (slurry) containing the toner particles is passed through a mesh, for example, to remove coarse particles from the suspension solution. The mesh size is adjusted appropriately depending on the particle size of the toner particles before cleaning. For example, the mesh size (unit: μm) relative to the volume average particle size D50v (unit: μm) of the toner particles before cleaning [D50v / mesh size] is preferably 2 or more and 6 or less, and more preferably 3 or more and 5 or less.

[0031] Through the above steps, pre-cleaned toner particles are obtained. The pre-washed toner particles may be produced through the following steps: after obtaining an aggregated particle dispersion in which aggregated particles are dispersed, further mixing the aggregated particle dispersion with a resin particle dispersion in which resin particles are dispersed, and aggregating the aggregated particles so that further resin particles adhere to the surfaces of the aggregated particles to form second aggregated particles; and heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles to form pre-washed toner particles having a core / shell structure.

[0032] - Filtration - In the first step, the unwashed toner particles obtained by the above method are filtered. Methods for filtering the toner particles before cleaning include vacuum filtration, centrifugal filtration, and pressure filtration. From the viewpoint of filtration efficiency, pressure filtration is preferred as a method for filtering the toner particles before cleaning.

[0033] From the viewpoint of filtration efficiency, pressure filtration is preferably carried out using a filter press. When filtration is performed using a filter press, specifically, it is preferable to add a suspension solution (slurry) containing the toner particles before cleaning to the filter chamber of the filter press and apply pressure.

[0034] The pressure applied to the unwashed toner particles when filtering the unwashed toner particles is preferably 0.2 MPa or more and 0.7 MPa or less, more preferably 0.3 MPa or more and 0.6 MPa or less, and even more preferably 0.3 MPa or more and 0.5 MPa or less.

[0035] The filter press conditions are preferably as follows: ·Filtration area: 30m 2 More than 200m 2 below ·Filter chamber volume: 0.5m 3 More than 5m 3 below ·Filter chamber thickness: 20mm or more and 50mm or less Filter 125Pa airflow: 0.1cm 3 / cm 2·s or more 0.5cm 3 / cm 2 ·s or less

[0036] When filtration is performed using a filter press, the amount of pre-washed toner particles in the suspension solution containing the pre-washed toner particles is preferably 5% by mass or more and 30% by mass or less, more preferably 7% by mass or more and 25% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less, based on the total amount of the suspension solution.

[0037] (2nd process) The second step is a step of squeezing the uncleaned toner particles and then passing water through the uncleaned toner particles. -Compression- The filtered and unwashed toner particles obtained in the first step are squeezed. The compression pressure P1 is preferably 0.2 MPa or more and 0.7 MPa or less, more preferably 0.3 MPa or more and 0.6 MPa or less, and even more preferably 0.3 MPa or more and 0.5 MPa or less.

[0038] The toner particles before cleaning are preferably squeezed using a filter press. The filter press conditions are preferably the same as those described in the first step.

[0039] -Water flow- Water is passed through the compressed pre-cleaned toner particles. A preferred method for passing water is, for example, passing water through a pipe connected to the filter chamber.

[0040] The water to be passed through is not particularly limited, and ion-exchanged water, ultrapure water, distilled water, ultrafiltered water, etc. may be used. However, from the viewpoint of reducing the ions remaining in the toner particles before washing, it is preferable to use at least one of ion-exchanged water and ultrapure water. Furthermore, when the conductivity of the filtrate recovered by passing water in the second step is 0.05 mS / cm or less, the filtrate may be passed through the system.

[0041] It is preferable to pass water through the filtrate until the conductivity of the filtrate is 0.10 mS / cm or less, more preferably 0.08 mS / cm or less, and even more preferably 0.05 mS / cm or less. From the viewpoint of improving production efficiency, water may be passed through the filtrate until the conductivity of the filtrate reaches 0.01 mS / cm or more.

[0042] By passing water through the filtrate until the conductivity of the filtrate falls within the above range, the impurities remaining in the toner particles before washing are further reduced, resulting in more excellent charge stability of the resulting toner.

[0043] The conductivity is a value measured with a conductivity meter. As the conductivity meter, for example, MPC227 (pH / Conductivity Meter, manufactured by Mettler-Toledo) can be used.

[0044] The amount of water passed through is preferably 600 parts by mass or more, more preferably 800 parts by mass or more, and even more preferably 1000 parts by mass or more, relative to 100 parts by mass of the toner particles before cleaning.

[0045] By setting the amount of water to pass within the above range, the impurities remaining in the toner particles before washing can be further reduced, and therefore the resulting toner has better charge stability. From the viewpoint of improving production efficiency, the amount of water to be passed through may be 2000 parts by mass or less, 1900 parts by mass or less, or 1800 parts by mass or less, relative to 100 parts by mass of the toner particles before cleaning.

[0046] The temperature T of the water passing through the pipe satisfies 10℃≦T≦35℃. From the viewpoint of improving the charging stability of the obtained toner, the temperature T of the water passing through preferably satisfies 12°C≦T≦33°C, more preferably satisfies 14°C≦T≦31°C, and even more preferably satisfies 16°C≦T≦29°C.

[0047] (3rd step) The third step is a step of squeezing the uncleaned toner particles and then blowing compressed air through the uncleaned toner particles. -Compression- The toner particles obtained in the second step after passing water and before being washed are squeezed. The compression pressure P2 is preferably 0.3 MPa or more and 0.8 MPa or less, more preferably 0.4 MPa or more and 0.7 MPa or less, and even more preferably 0.5 MPa or more and 0.7 MPa or less.

[0048] The toner particles before cleaning are preferably squeezed using a filter press. The filter press conditions are preferably the same as those described in the first step.

[0049] -Ventilation- Compressed air is passed through the compressed pre-cleaned toner particles. A preferred method for passing compressed air is, for example, passing compressed air through a pipe connected to the filter chamber.

[0050] The ventilation time is preferably 60 seconds or more, more preferably 80 seconds or more, and even more preferably 100 seconds or more. From the viewpoint of improving production efficiency, the ventilation time may be set to 900 seconds or less.

[0051] By setting the ventilation time to 60 seconds or more, excess moisture can be easily removed from the unwashed toner particles contained in the filter chamber, and impurities contained in the unwashed toner particles can be further reduced, thereby further improving the charge stability of the resulting toner.

[0052] The pressure of the compressed air is preferably 0.2 MPa or more and 0.6 MPa or less, more preferably 0.3 MPa or more and 0.6 MPa or less, and even more preferably 0.3 MPa or more and 0.5 MPa or less.

[0053] By setting the compression pressure within the above range, excess moisture can be more easily removed from the uncleaned toner particles contained in the filter chamber, and impurities contained in the uncleaned toner particles can be further reduced, thereby further improving the charge stability of the resulting toner.

[0054] It is preferable to pass the compressed air multiple times. Here, it is preferable that the ventilation time per ventilation and the pressure of the compressed air are as described above.

[0055] By passing compressed air through the filter chamber multiple times, excess moisture can be more easily removed from the uncleaned toner particles contained in the filter chamber, and impurities contained in the uncleaned toner particles can be more easily reduced, thereby further improving the charge stability of the resulting toner.

[0056] Compressed air is passed through the pre-cleaned toner particles, and the amount of moisture contained in the pre-cleaned toner particles is preferably 45% by mass or less, more preferably 43% by mass or less, and even more preferably 40% by mass or less, based on the total amount of the pre-cleaned toner particles. From the viewpoint of improving production efficiency, compressed air may be passed through the pre-cleaned toner particles to make the amount of water contained in the pre-cleaned toner particles 25% by mass or more relative to the total amount of the pre-cleaned toner particles.

[0057] By passing compressed air through the pre-cleaned toner particles and adjusting the amount of moisture contained in the pre-cleaned toner particles to 45% by mass or less based on the total amount of the pre-cleaned toner particles, excess moisture can be more easily removed from the pre-cleaned toner particles contained in the filter chamber, and impurities contained in the pre-cleaned toner particles can be more easily reduced, thereby further improving the charge stability of the resulting toner.

[0058] Here, the amount of water contained in the toner particles before cleaning after ventilation is measured as follows. After ventilation, 3 g of the toner particles before cleaning is measured using a heat-drying type moisture content meter (manufactured by A&D Co., Ltd., product name: ML-50).

[0059] (Relationship between the pressing pressure P1 and the pressing pressure P2) The pressing pressure P1 in the second step and the pressing pressure P2 in the third step satisfy 0.2 MPa ≤ P1 < P2 ≤ 0.8 MPa. From the viewpoint of obtaining a toner with better charge stability and higher transfer efficiency, the difference (P2 - P1) between the pressing pressure P1 in the second step and the pressing pressure P2 in the third step is preferably 0.05 MPa or more and 0.4 MPa or less, more preferably 0.1 MPa or more and 0.35 MPa or less, and still more preferably 0.1 MPa or more and 0.3 MPa or less.

[0060] (Drying process) It is preferable to have a step of drying the toner particles after the third step. The drying process is not particularly limited in method, but from the viewpoint of productivity, freeze drying, airflow drying, fluid drying, vibration type fluid drying, etc. are preferably applied.

[0061] The toner particles are manufactured by the above steps.

[0062] (Manufacture of toner) -External addition process- When the toner contains an external additive, it can be obtained by externally adding the external additive to the toner particles after manufacturing the toner particles. The external addition process is, for example, a process of adding and mixing an external additive to the obtained dried toner particles. The mixing may be performed, for example, by a V blender, a Henschel mixer, a Lodige mixer, etc. Further, if necessary, coarse particles of the toner may be removed using a vibration sieve, an air classifier, etc.

[0063] It is preferable that the toner manufacturing method according to this embodiment has an ammonium ion content of 1.0 mg / L or less, a Na element Net intensity of 0.50 kcps or less, and a S element Net intensity of 1.5 kcps or less measured by the following procedure.

[0064] For reasons to be described later, a toner having an ammonium ion content, a net Na intensity, and a net S intensity within the above ranges has excellent charge stability and high transfer efficiency. Therefore, by using a method for producing the toner described above, a toner having excellent charge stability and high transfer efficiency can be easily produced.

[0065] The methods for measuring the content of ammonium ions, the net strength of Na element, and the net strength of S element will be described later.

[0066] <Toner> The toner according to this embodiment has an ammonium ion content of 1.0 mg / L or less as measured by the procedure described below, a net intensity of Na element of 0.50 kcps or less as measured by fluorescent X-ray analysis, and a net intensity of S element of 1.50 kcps or less.

[0067] The toner according to the present embodiment has the above-described structure, and is therefore excellent in charge stability and transfer efficiency. The reasons for this are presumed to be as follows.

[0068] By setting the ammonium ion content to 1.0 mg / L or less, the toner charge amount tends to be within a suitable range when forming images in a low-temperature, low-humidity environment. Furthermore, by setting the net intensity of Na element in fluorescent X-ray analysis to 0.50 kcps or less, the toner charge amount tends to be within a suitable range when forming images in a high-temperature, high-humidity environment. Therefore, the toner according to this embodiment has excellent charge stability. Furthermore, by setting the net intensity of the S element to 1.50 kcps or less, transfer defects are easily suppressed, and therefore the toner according to this embodiment has high transfer efficiency.

[0069] From the above, it is presumed that the toner according to this embodiment has excellent charge stability and higher transfer efficiency.

[0070] (Ammonium ion content) The ammonium ion content is 1.0 mg / L or less. From the viewpoint of further improving the charging stability in a low-temperature, low-humidity environment, the content of ammonium ions is preferably 0.9 mg / L or less, more preferably 0.8 mg / L or less, and even more preferably 0.7 mg / L or less. The content of ammonium ions is most preferably 0.0 mg / L, but may be 0.1 mg / L or more from the viewpoint of improving the efficiency of toner production.

[0071] The content of ammonium ions is measured as follows. 0.5 g of toner particles are weighed and dispersed in 100 g of ion-exchanged water containing 0.1 g of a nonionic surfactant (e.g., Nonipol 10 manufactured by Sanyo Chemical Industries, Ltd.), equivalent to 20% by mass of the total toner particles, and dispersed for 30 minutes in an ultrasonic disperser in a thermostatic chamber controlled at 30±1°C. The liquid after ultrasonic dispersion is subjected to solid-liquid separation by suction filtration to remove the toner particles, and the amount of ammonium contained in the obtained filtrate is measured using ion chromatography. The ion chromatography used is an ICS-2000 manufactured by Nippon Dionex Corporation, and analysis is performed under the following conditions. Cation separation column: Nippon Dionex, IonPacCS12A Cation guard column: Nippon Dionex, IonPacCG12A Eluent: methanesulfonic acid 20 mM (mmol / l) ·Flow rate: 1ml / min ·Temperature: 30℃ Detection method: Electrical conductivity method (suppressor type)

[0072] Examples of sources of ammonium ions include ammonia used as a neutralizing agent when preparing a resin particle dispersion by phase inversion emulsification, and cationic surfactants such as quaternary ammonium salts.

[0073] (Net intensity of Na element) The net intensity of Na element in fluorescent X-ray analysis is 0.50 kcps or less. From the viewpoint of further improving the charging stability in a high-temperature, high-humidity environment, the net intensity of Na element in fluorescent X-ray analysis is preferably 0.45 kcps or less, more preferably 0.4 kcps or less, and even more preferably 0.30 kcps or less. The net strength of Na element is most preferably 0.00 kcps, but may be 0.10 kcps or more from the viewpoint of improving the efficiency of toner production.

[0074] The net intensity of Na element in fluorescent X-ray analysis is measured as follows. 0.12 g of the sample was compressed using a compression molding machine under a load of 6 t for 60 seconds to produce a disk with a diameter of 50 mm and a thickness of 2 mm. This disk was used as a sample for total element analysis using a Shimadzu X-ray fluorescence analyzer (XRF-1500) under measurement conditions of a tube voltage of 40 kV and a tube current of 70 mA, and the net intensity of the Na element was measured.

[0075] As a source of Na element, anionic surfactants of sulfonate salts such as sodium dodecylbenzenesulfonate can be mentioned.

[0076] (Net intensity of S element) The net intensity of S element in fluorescent X-ray analysis is 1.50 kcps or less. From the viewpoint of further improving the transfer efficiency, the net intensity of the S element in fluorescent X-ray analysis is preferably 1.45 kcps or less, more preferably 1.40 kcps or less, and even more preferably 1.30 kcps or less. The net strength of the S element is most preferably 0.00 kcps, but may be 0.10 kcps or more from the viewpoint of improving the efficiency of toner production.

[0077] The net intensity of the S element in the X-ray fluorescence analysis is measured in the same way as the net intensity of the Na element.

[0078] Examples of the source of S element include sulfur-containing additives (surfactants, flocculants, etc.) Specific examples of the source of S element include sulfate ester salt-based anionic surfactants, sulfonate salt-based anionic surfactants, and metal salts such as aluminum sulfate.

[0079] (Toner Composition) The toner according to this embodiment contains toner particles and, if necessary, an external additive. The toner particles are composed of, for example, a binder resin, and, if necessary, a colorant, a release agent, and other additives. The binder resin, colorant, release agent, other additives, and external additives contained in the toner particles are not particularly limited, and may include conventionally known ones used in toner.

[0080] (Characteristics of toner particles, etc.) The toner particles may be toner particles of a single layer structure, or may be toner particles of a so-called core-shell structure composed of a core part (core particle) and a coating layer (shell layer) that coats the core part. Here, the toner particles having a core-shell structure may be composed of, for example, a core containing a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer containing the binder resin.

[0081] The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 3 μm or more and 8 μm or less.

[0082] The various average particle sizes and particle size distribution indices of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, cumulative distributions of volume and number are drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at 16% of the cumulative total is defined as the volume particle size D16v, the number particle size D16p, the particle size at 50% of the cumulative total as the volume average particle size D50v, the cumulative number average particle size D50p, and the particle size at 84% of the cumulative total as the volume particle size D84v and the number particle size D84p. Using these, the volumetric particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 , the number particle size distribution index (GSDp) is (D84p / D16p) 1 / 2 It is calculated as:

[0083] The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

[0084] The average circularity of toner particles is calculated by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)]. Specifically, this value is measured by the following method. First, the toner particles to be measured are sucked and collected, forming a flat flow, and a still image of the particles is captured by instantaneously activating a strobe light, and the particle image is analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation).The number of samples to be sampled when calculating the average circularity is 3,500. When the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed. [Example]

[0085] Examples will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, all "parts" and "%" are by mass.

[0086] <Preparation of various dispersions> (Preparation of Polyester Resin Particle Dispersion) -Synthesis of polyester resin- A reactor equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube was charged with 80 moles of polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane, 10 moles of ethylene glycol, 10 moles of cyclohexanediol, 80 moles of terephthalic acid, 10 moles of isophthalic acid, and 10 moles of n-dodecenylsuccinic acid, and the atmosphere in the reactor was purged with dry nitrogen gas. Then, 0.25 parts by mass of titanium tetrabutoxide was added as a catalyst per 100 parts by mass of the monomer components. After stirring and reacting for 3 hours at 170°C under a nitrogen gas stream, the temperature was further increased to 210°C over 1 hour, the pressure in the reactor was reduced to 3 kPa, and the reaction was continued under reduced pressure for 13 hours with stirring to obtain a polyester resin. The glass transition temperature of the resulting resin was measured using a differential scanning calorimeter (DSC) and found to be 58°C.

[0087] -Preparation of dispersion- Polyester resin 100 parts by weight 70 parts by weight of ethyl acetate Isopropyl alcohol 15 parts by weight The ethyl acetate and isopropyl alcohol mixed solvent was placed in a jacketed stainless steel vessel, and the polyester resin was gradually added and completely dissolved with stirring to obtain an oil phase. A 10% by weight aqueous ammonia solution was gradually added dropwise to the stirred oil phase using a pump until a total of 3 parts by weight was achieved. 230 parts by weight of ion-exchanged water was then gradually added dropwise at a rate of 10 L / min to induce phase inversion emulsification. Subsequently, vacuum distillation was performed to obtain Resin Dispersion 1 (solids concentration: 40% by weight) containing polyester resin particles. The solids concentration was measured using a moisture meter MA35 (manufactured by Sartorius Mechatronics Japan Co., Ltd.). The solids concentration of each sample below was measured in the same manner. The volume average particle size (D50v) of the polyester resin particles in the obtained first dispersion was 180 nm.

[0088] (Preparation of release agent dispersion) Paraffin wax (manufactured by Nippon Seiro Co., Ltd., FNP92, endothermic peak onset 81°C): 45 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts Ion-exchanged water: 200 parts The above ingredients were mixed and heated to 95°C, and dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA). After that, a dispersion treatment was carried out using a Manton-Gaulin high-pressure homogenizer (Gaulin), and a release agent dispersion 1 (solid content concentration: 20%) was prepared by dispersing the release agent. The volume average particle size of the release agent particles was 0.19 μm.

[0089] (Preparation of Colorant Dispersion) Cyan pigment (Dainichi Seikagaku Co., Ltd., Pigment Blue 15:3 (copper phthalocyanine)): 98 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen R): 2 parts Ion-exchanged water: 400 parts After mixing the above, the mixture was dispersed for 10 minutes using a homogenizer (IKA Ultra Turrax) to obtain a colorant dispersion having a volume average particle size of 0.16 μm and a solid content of 20%. <Preparation of toner particle-containing slurry> Polyester resin particle dispersion: 100 parts by weight Colorant particle dispersion: 10 parts by weight Release agent particle dispersion: 9 parts by weight Ion-exchanged water: 200 parts by weight The raw materials were placed in a tank equipped with a heatable / coolable jacket, and 3 parts of a 0.3 M aqueous nitric acid solution was added to adjust the pH to 3.0. Next, while circulating the mixture through a disperser (Cavitron, manufactured by Pacific Machinery Works, Ltd.) installed outside the mixing tank, 50 parts of a 10% aqueous aluminum sulfate solution was added dropwise as a coagulant. After mixing and dispersing, the mixture was heated to a jacket temperature of 50°C while stirring with a stirring blade to obtain aggregated particles. Next, a resin particle dispersion for coating the aggregated particles, previously adjusted to pH 3.0 by mixing 25 parts of a polyester resin dispersion and 10 parts of ion-exchange water, was added and held for 10 minutes. To stop the growth of the coated aggregated particles, a 1 M aqueous sodium hydroxide solution was added to adjust the pH of the solution to 8.0. Next, to fuse the coated aggregated particles, the temperature was raised to 96°C at a rate of 1°C / min, and after reaching 90°C, the temperature was held for 4 hours. The mixture was then cooled to 40°C to obtain a coarse toner particle-containing slurry. The volume average particle size of the coarse toner particles contained in the coarse toner particle slurry was 6.0 μm. Further, this coarse toner particle-containing slurry was sieved with a mesh having an opening of 25 μm to obtain a toner particle-containing slurry.

[0090] Example 1 (1st step) The obtained toner particle-containing slurry was fed to a filter press (manufactured by Tokyo Engineering Co., Ltd.) and filtered to form a cake layer. (2nd process) Next, the cake layer was squeezed at a pressure of 0.3 MPa, and 1500 parts by mass of deionized water adjusted to 15°C was passed through the toner particles per 100 parts by mass of the toner particles. The conductivity of the filtrate after passing 1500 parts by mass of water was 0.05 mS / cm. (3rd step) Next, the cake layer was squeezed at a pressure of 0.7 MPa. After that, compressed air at 0.4 MPa was passed through once for 120 seconds. The moisture content of the toner particles contained in the cake layer was measured and found to be 40% by mass relative to the total amount of toner particles. (drying process) The cake layer was then removed and dried to obtain toner particles having a volume average particle size of 5.9 μm. (External addition process) 100 parts of toner particles and 1.5 parts of hydrophobic silica (RY50, manufactured by Nippon Aerosil Co., Ltd.) were mixed and mixed for 30 seconds at a rotation speed of 13,000 rpm using a sample mill. The mixture was sieved using a vibrating sieve with 45 μm openings to obtain a toner.

[0091] <Examples 2 to 4 and Comparative Examples 1 to 6> A toner was produced in the same manner as in Example 1, except that the conditions in the second and third steps were changed to those shown in Table 1.

[0092] <Evaluation> The developer prepared by the following procedure was filled into the developing device of a modified "DocuCentreColor400 (manufactured by Fuji Xerox Co., Ltd.)" and the charging stability and transfer efficiency were evaluated.

[0093] (Developer manufacturing procedure) -Creating a carrier- 100 parts of ferrite particles (manufactured by Powder Tech Co., Ltd., average particle size 50 μm) and 1.5 parts of polymethyl methacrylate resin (manufactured by Mitsubishi Rayon Co., Ltd., weight average molecular weight 95,000, proportion of components with a weight average molecular weight of 10,000 or less is 5%) were placed in a pressure kneader together with 500 parts of toluene, stirred and mixed at room temperature for 15 minutes, then heated to 70°C while mixing under reduced pressure to distill off the toluene, then cooled and classified using a 105 μm sieve to obtain a resin-coated carrier. - Developer production - 10 parts of the toner obtained in each example and 100 parts of the resin-coated carrier were placed in a V-type blender and stirred for 20 minutes, and then sieved through a vibrating sieve with 212 μm openings to obtain a developer.

[0094] (Charging stability evaluation) The developer was filled into a developing device and left for 24 hours or more in a high-temperature, high-humidity environment (30°C, 85% RH) and a low-temperature, low-humidity environment (10°C, 15% RH). After that, the developing device was run idle for 3 minutes under the same conditions. The charge amount of this developer was measured using a blow-off powder charge amount measuring device (TB-200) manufactured by Toshiba Chemical Co., Ltd. The evaluation criteria for charge stability are as follows: A (◎): (charge value in a high-temperature, high-humidity environment / charge value in a low-temperature, low-humidity environment) is 0.7 or more B (〇): (charge value in a high-temperature, high-humidity environment / charge value in a low-temperature, low-humidity environment) is 0.5 or more and less than 0.7 C(×): (charge value in a high-temperature, high-humidity environment / charge value in a low-temperature, low-humidity environment) is less than 0.5

[0095] (Transfer efficiency evaluation) The test procedure consisted of first adjusting the development potential so that the toner coverage on the photoconductor was 5 g / m2 in an environment with a temperature of 10°C and humidity of 20% RH. Next, the evaluation machine was stopped immediately after the developed toner on the photoconductor was transferred to the intermediate transfer body (intermediate transfer belt). This left toner remaining on the photoconductor in the state after transfer (before cleaning). This toner was removed with mending tape and the toner weight at that time was measured. Transfer efficiency was calculated using the following formula from the ratio of the toner coverage during development to the toner coverage after transfer. Transfer efficiency was measured after continuously printing 50,000 sheets of A4 paper with an image area of 5%. Formula: Transfer efficiency = Amount of toner on paper after transfer / Amount of toner on photoconductor × 100 The transfer efficiency evaluation criteria are as follows: A(◎): Transfer efficiency 98% or more B (〇): Transfer efficiency 95% or more but less than 98% C (△): Transfer efficiency is 90% or more but less than 95% D(×): Transfer efficiency less than 90%

[0096] [Table 1-1]

[0097] [Table 1-2]

[0098] From the above results, it is apparent that the toner manufacturing method of this example can produce a toner that is excellent in charge stability and has high transfer efficiency.

Claims

1. A first step of filtering toner particles obtained by a wet process; a second step of passing water through the toner particles after squeezing the toner particles; a third step of blowing compressed air through the toner particles after squeezing the toner particles; A method for producing a toner, which satisfies the following conditions (1), (2), (3), and (4), and wherein the difference (P2-P1) between the compression pressure P1 in the second step and the compression pressure P2 in the third step is 0.05 MPa or more and 0.35 MPa or less: Condition (1): The temperature T of the water passed through in the second step satisfies 14°C≦T≦31°C. Condition (2): The compression pressure P1 in the second step and the compression pressure P2 in the third step satisfy 0.3 MPa≦P1<P2≦0.7 MPa. Condition (3): The amount of water passed in the second step satisfies 1,000 parts by mass or more and 2,000 parts by mass or less with respect to 100 parts by mass of the toner particles. Condition (4): The ventilation time in the third step is 60 seconds or more and 900 seconds or less.

2. 2. The method for producing a toner according to claim 1, wherein in the second step, water is passed through until the conductivity of the filtrate becomes 0.10 mS / cm or less.

3. 2. The method for producing toner according to claim 1, wherein the pressure of the compressed air in the third step is 0.2 MPa or more and 0.6 MPa or less.

4. 4. The method for producing a toner according to claim 1, wherein the third step includes passing compressed air through the toner particles a plurality of times.

5. 5. The method for producing a toner according to claim 1, wherein in the third step, compressed air is passed through the toner particles, and the amount of moisture contained in the toner particles is set to 45% by mass or less with respect to the total amount of the toner particles.

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