Toner for developing electrostatic charge images, electrostatic charge image developer, and toner cartridge

Abstract

Toner for developing an electrostatic charge image, electrostatic charge image developer, and toner cartridge. A toner for developing an electrostatic charge image includes: toner particles containing a binder resin; and an external additive containing silica particles, wherein, after performing a process of dispersing the toner in water and drying the dispersed toner, a coefficient of variation of Si content is determined by determining the Si content in a plurality of 0.5 μm × 0.5 μm square regions on the surface of each of the toner particles, and a change amount ((coefficient of variation of Si content after the process) - (coefficient of variation of Si content before the process)) between the coefficient of variation of Si content after the process and the coefficient of variation of Si content before the process is 0.05 or more and 0.60 or less.

Description

Technical Field

[0001] The present disclosure relates to a toner for developing an electrostatic charge image, an electrostatic charge image developer, and a toner cartridge. Background Art

[0002] Methods such as electrophotography for visualizing image information by an electrostatic charge image are now used in various fields.

[0003] The electrophotography method generally adopted so far includes the following steps: forming an electrostatic latent image on a photoreceptor or an electrostatic recording member by using various units, causing charge-detecting particles called toner to adhere to the electrostatic latent image to develop the electrostatic latent image (toner image), transferring the toner image onto the surface of a recording medium, and fixing the toner image by heating.

[0004] For example, Japanese Unexamined Patent Application Publication No. 2015-125256 discloses "a non-magnetic toner including inorganic fine particles and toner particles containing a binder resin and a crystalline polyester, wherein the crystalline polyester has a melting point (Tm) of 60°C or higher and 100°C or lower and has a weight-average molecular weight (Mw) of 20,000 or higher and 50,000 or lower; 1.5 parts by mass or more and 3.0 parts by mass or less of inorganic fine particles are contained with respect to 100.0 parts by mass of the toner particles; the silica fine particles account for 30.0 mass% or more of the inorganic fine particles and have a number-average primary particle diameter (D1) of 4.0 nm or higher and 15.0 nm or lower; the proportion of free inorganic fine particles is 10.0 mass% or more and 25.0 mass% or lower; and the coefficient of variation of the portion of the toner particles covered with the inorganic fine particles is 6.0% or lower".

[0005] For example, Japanese Unexamined Patent Application Publication No. 2017-015817 discloses "a toner containing at least one binder resin and a release agent, and two or more types of inorganic fine particles as external additives, one of the external additives being silica, wherein when ultrasonic vibration is applied to a toner dispersion prepared by dispersing the toner in a dispersant, the ultrasonic energy applied to separate 20% of the silica from the toner is 8 kJ or higher and 14 kJ or lower with respect to the total amount of the silica, and the ultrasonic energy applied to separate 50% of the silica is 70 kJ or higher and 130 kJ or lower".

[0006] For example, Japanese Unexamined Patent Application Publication No. 2011-043759 discloses "a toner for developing an electrostatic charge image, in which an external additive is added to toner mother particles, the external additive having a number average primary particle diameter of 20 nm or more and less than 80 nm, a ratio of the minimum particle diameter to the number average primary particle diameter (minimum particle diameter / number average primary particle diameter) of 0.5 or more, a ratio of the maximum particle diameter to the number average primary particle diameter (maximum particle diameter / number average primary particle diameter) of 1.7 or less, and the external additive being monodispersed particles on the surface of the toner mother particles". SUMMARY OF THE INVENTION

[0007] Accordingly, an object of the present disclosure is to provide a toner for developing an electrostatic charge image, the toner including: toner particles containing a binder resin and an external additive containing silica particles, and suppressing contamination of a recording medium caused by clogging of a transfer residual toner recovery route regardless of whether the toner is heated, as compared with cases including: when a change amount ((Si content change coefficient after treatment) - (Si content change coefficient before treatment)) between a Si content change coefficient after a specific treatment and a Si content change coefficient before the specific treatment is less than 0.05 or greater than 0.60; when a content of a low molecular weight compound containing a hydroxyl group is less than 500 ppm or greater than 50000 ppm; or when a proportion of a component having a molecular weight of 50000 or more in a molecular weight distribution obtained by measuring a tetrahydrofuran-soluble portion of the toner particles by gel permeation chromatography is less than 15 mass% or greater than 50 mass%.

[0008] The following aspects are provided to achieve the above object.

[0009] According to a first aspect of the present disclosure, there is provided a toner for developing an electrostatic charge image, the toner including: toner particles containing a binder resin; and an external additive containing silica particles, wherein, after performing a treatment of dispersing the toner in water and drying the dispersed toner, a Si content change coefficient is determined by determining a Si content in a plurality of 0.5 μm × 0.5 μm square regions on the surface of each of the toner particles, and a change amount ((Si content change coefficient after treatment) - (Si content change coefficient before treatment)) between the Si content change coefficient and the Si content change coefficient before treatment is 0.05 or more and 0.60 or less.

[0010] According to a second aspect of the present disclosure, there is provided the toner according to the first aspect, wherein the Si content change coefficient after treatment is 0.20 or more and 0.80 or less.

[0011] According to a third aspect of the present disclosure, there is provided the toner according to the second aspect, wherein a coefficient of change in Si content after treatment is 0.25 or more and 0.70 or less.

[0012] According to a fourth aspect of the present disclosure, there is provided a toner for developing an electrostatic charge image, the toner including: toner particles containing a binder resin and a low molecular weight compound having a hydroxyl group; and an external additive containing silica particles, wherein, relative to the toner particles, the content of the low molecular weight compound is 500 ppm or more and 50000 ppm or less, and a proportion of a component having a molecular weight of 50000 or more in a molecular weight distribution obtained by measuring a tetrahydrofuran-soluble portion of the toner particles by gel permeation chromatography is 15% by mass or more and 50% by mass or less.

[0013] According to a fifth aspect of the present disclosure, there is provided the toner according to the fourth aspect, wherein the low molecular weight compound is at least one compound selected from phenolic compounds, hydroxycarboxylic acids or their ester compounds, and alcohol compounds.

[0014] According to a sixth aspect of the present disclosure, there is provided the toner according to the fifth aspect, wherein the low molecular weight compound is an alcohol compound.

[0015] According to a seventh aspect of the present disclosure, there is provided the toner according to the fifth aspect, wherein the content of the low molecular weight compound is 1000 ppm or more and 40000 ppm or less.

[0016] According to an eighth aspect of the present disclosure, there is provided the toner according to the sixth aspect, wherein the content of the low molecular weight compound is 2000 ppm or more and 30000 ppm or less.

[0017] According to a ninth aspect of the present disclosure, there is provided the toner according to the first aspect or the fourth aspect, wherein the binder resin contains a polyester resin formed by a condensate of a polycarboxylic acid and a polyol.

[0018] According to a tenth aspect of the present disclosure, there is provided the toner according to the fourth aspect, wherein the binder resin contains a polyester resin formed by a condensate of a polycarboxylic acid and a polyol, and an absolute value of a difference between an average number of carbon atoms Cp of the polyol constituting the polyester resin and the number of carbon atoms CL of the low molecular weight compound is |Cp - CL| ≤ 8.

[0019] According to an eleventh aspect of the present disclosure, there is provided the toner according to the first aspect or the fourth aspect, wherein a water content of the silica particles is 0.5% by mass or more and 5.0% by mass or less.

[0020] According to a twelfth aspect of the present disclosure, there is provided the toner according to the first aspect or the fourth aspect, wherein the ratio B1 / B2 is 1.2 or more and 5.0 or less, where B1 represents a measured value of the specific surface area of the toner particles, and B2 represents the calculated specific surface area of the toner particles calculated based on the volume average particle diameter.

[0021] According to a thirteenth aspect of the present disclosure, there is provided an electrostatic charge image developer including the electrostatic charge image developing toner according to the first aspect or the fourth aspect.

[0022] According to a fourteenth aspect of the present disclosure, there is provided a toner cartridge detachably attached to an image forming apparatus, the toner cartridge including the electrostatic charge image developing toner according to the first aspect or the fourth aspect.

[0023] According to the first aspect, there is provided an electrostatic charge image developing toner including toner particles containing a binder resin and an external additive containing silica particles, and compared with a case where the change amount ((the coefficient of change in Si content after treatment) - (the coefficient of change in Si content before treatment)) between the coefficient of change in Si content after a specific treatment and the coefficient of change in Si content before the specific treatment is less than 0.05 or greater than 0.60, whether or not the toner is heated, the toner suppresses contamination of a recording medium caused by clogging of a transfer residual toner recovery route.

[0024] According to the second aspect or the third aspect, there is provided an electrostatic charge image developing toner, and compared with a case where the coefficient of change in Si content after treatment is less than 0.20 or greater than 0.80, whether or not the toner is heated, the toner suppresses contamination of a recording medium caused by clogging of a transfer residual toner recovery route.

[0025] According to the fourth aspect, the fifth aspect or the sixth aspect, there is provided an electrostatic charge image developing toner, and compared with a case where the content of the low molecular weight compound containing a hydroxyl group is less than 500 ppm or greater than 50000 ppm, or compared with a case where the proportion of a component having a molecular weight of 50000 or more in the molecular weight distribution obtained by measuring the tetrahydrofuran-soluble portion of the toner particles by gel permeation chromatography is less than 15% by mass or greater than 50% by mass, whether or not the toner is heated, the toner suppresses contamination of a recording medium caused by clogging of a transfer residual toner recovery route.

[0026] According to the seventh aspect or the eighth aspect, there is provided a toner for developing an electrostatic charge image, and compared with the case where the amount of the low molecular weight compound is less than 1000 ppm or greater than 40000 ppm, regardless of whether the toner is heated, the toner suppresses the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0027] According to the ninth aspect, there is provided a toner for developing an electrostatic charge image, and compared with the case where the binder resin is a styrene acrylic resin, regardless of whether the toner is heated, the toner suppresses the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0028] According to the tenth aspect, there is provided a toner for developing an electrostatic charge image, and compared with the case where the absolute value (|Cp - CL|) of the difference between the average number of carbon atoms Cp of the polyol constituting the polyester resin and the number of carbon atoms CL of the low molecular weight compound is greater than 8, regardless of whether the toner is heated, the toner suppresses the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0029] According to the eleventh aspect, there is provided a toner for developing an electrostatic charge image, and compared with the case where the water content of the silica particles is less than 0.5 mass% or greater than 5.0 mass%, regardless of whether the toner is heated, the toner suppresses the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0030] According to the twelfth aspect, there is provided a toner for developing an electrostatic charge image, and compared with the case where the ratio B1 / B2 is less than 1.2 or greater than 5.0 (where B1 represents the measured value of the specific surface area of the toner particles and B2 represents the calculated specific surface area of the toner particles calculated based on the volume average particle diameter), regardless of whether the toner is heated, the toner suppresses the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0031] According to the thirteenth aspect or the fourteenth aspect, there is provided an electrostatic charge image developer or an image forming apparatus that uses an electrostatic charge image developing toner, the toner including toner particles containing a binder resin and an external additive containing silica particles, and compared with when using a toner in which the change amount ((the coefficient of change in Si content after treatment) - (the coefficient of change in Si content before treatment)) between the coefficient of change in Si content after a specific treatment and the coefficient of change in Si content before the specific treatment is less than 0.05 or greater than 0.60, compared with when using a toner in which the amount of a low molecular weight compound containing a hydroxyl group is less than 500 ppm or greater than 50,000 ppm, or compared with when using a toner in which the proportion of components having a molecular weight of 50,000 or more in the molecular weight distribution obtained by measuring the tetrahydrofuran-soluble portion of the toner particles by gel permeation chromatography is less than 15% by mass or greater than 50% by mass, the toner suppresses contamination of a recording medium caused by clogging of a transfer residual toner recovery route regardless of whether the toner is heated. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Exemplary embodiments of the present disclosure will be described in detail based on the following drawings, in which:

[0033] Figure 1 is a schematic diagram of an image forming apparatus according to an exemplary embodiment;

[0034] Figure 2 is a schematic diagram of a process cartridge according to an exemplary embodiment; and

[0035] Figure 3 is a diagram showing a method for determining the Si content in a 0.5 μm × 0.5 μm region on the surface of toner particles and a method for calculating the coefficient of change in Si content. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Exemplary embodiments as an example of the present disclosure will now be described.

[0037] In the present specification, when referring to the amount of a component in a composition and when there are two or more types of substances in the composition corresponding to the component, unless otherwise specified, the amount is the total amount of the two or more types of substances in the composition.

[0038] In the present specification, "electrostatic charge image developing toner" may be abbreviated as "toner", and "electrostatic charge image developer" may be abbreviated as "developer".

[0039] Electrostatic Charge Image Developing Toner

[0040] The toner for electrostatic charge image development according to the first exemplary embodiment includes toner particles containing a binder resin and an external additive containing silica particles.

[0041] When determining the Si content in a 0.5 μm × 0.5 μm square region on the surface of each toner particle after performing the process of dispersing the toner in water and drying the dispersed toner, the change amount between the coefficient of variation of the Si content after the process and the coefficient of variation of the Si content before the process ((the coefficient of variation of the Si content after the process) - (the coefficient of variation of the Si content before the process), hereinafter, this range may be referred to as "the change amount of the coefficient of variation of the Si content before and after a specific process") is 0.05 or more and 0.60 or less.

[0042] Due to the above characteristics, the toner of the first exemplary embodiment suppresses the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route, regardless of whether the toner is heated. The reason behind this is probably as follows.

[0043] Generally, when the toner in the toner cartridge is heated, the external additive is completely buried in the surface of the toner particles. Such toner exhibits reduced transferability, and thus the amount of transfer residual toner increases. "Transfer residual toner" refers to the toner remaining on the image carrier after the transfer of the toner image.

[0044] The transfer residual toner is scraped off by a cleaning blade, passes through the toner recovery route, and is sent to a recovery container or the like. Clogging may occur in the transfer residual toner recovery route. Once the recovery route is clogged, the transfer residual toner cannot be recovered, and the recording medium may be contaminated due to, for example, the toner blown out inside the device.

[0045] Specifically, when there is a difference in image density in the in-out direction (in other words, between the right and left sides relative to the paper supply direction), the transfer residual toner remains in the recovery route, easily forms toner lumps, and sometimes causes clogging.

[0046] This is probably because heat is applied to the toner, causing the external additive to be buried in the toner particles, thereby enhancing the adhesion between the toner particles and creating a state where the toner particles are densely packed.

[0047] At the same time, controlling the glass transition temperature Tg of the toner, the molecular weight of the binder resin in the toner, etc. suppresses the burial of the external additive caused by heat.

[0048] However, in this case, the mechanical load applied inside the developing unit causes the external additives to separate from the toner particles. Therefore, due to the separation of the external additives, the amount of the external additives on the transferred residual toner also decreases. As a result, the amount of the transferred residual toner increases, the adhesiveness between the toner particles is enhanced, the transfer residual toner recovery route becomes clogged, and the recording medium may be contaminated.

[0049] On the contrary, for the toner according to the first exemplary embodiment, the surface of a toner particle has the following structure: regions where silica particles serving as external additives adhere with high adhesiveness and regions where silica particles serving as external additives adhere with low adhesiveness are distributed therein.

[0050] Specifically, the change amount of the coefficient of variation of the Si content before and after a specific treatment is set to be 0.05 or more and 0.60 or less.

[0051] Here, the "Si content in each 0.5 μm × 0.5 μm square region on the surface of the toner particle" refers to the abundance of the silica particles serving as external additives in each region. A large coefficient of variation of the Si content indicates that the silica particles adhere to the toner particles almost uniformly, while a small coefficient of variation of the Si content indicates that the silica particles adhere to the toner particles almost non-uniformly.

[0052] In other words, the fact that the change amount of the coefficient of variation of the Si content before and after the treatment is within the above range indicates that, compared with before the treatment, the silica particles after the treatment adhere to the toner particles more non-uniformly.

[0053] Therefore, when the change amount of the coefficient of variation of the Si content before and after the treatment is within the above range, a toner particle has the following structure: regions where silica particles serving as external additives adhere with high adhesiveness and regions where silica particles serving as external additives adhere with low adhesiveness are distributed therein.

[0054] When the toner having the above structure is heated, the silica particles that adhere to the toner particles with high adhesiveness are buried in the toner particles, while the silica particles that adhere to the toner particles with low adhesiveness are not easily buried. Therefore, the silica particles that adhere to the toner particles with low adhesiveness exhibit a spacing function between the toner particles, and an increase in the amount of the transferred residual toner and an increase in the adhesiveness between the toner particles are suppressed. As a result, even when the toner is heated, contamination of the recording medium caused by clogging of the transfer residual toner recovery route is suppressed.

[0055] Furthermore, even when a mechanical load is applied to the toner having the above structure, although the silica particles adhered to the toner particles with a low adhesion force tend to separate first, the silica particles adhered to the toner particles with a high adhesion force tend to remain without being separated from the toner particles. Therefore, the silica particles adhered to the toner particles with a high adhesion force suppress an increase in the amount of transfer residual toner and an increase in adhesion between the toner particles. As a result, even when the toner is not heated, contamination of the recording medium caused by clogging of the transfer residual toner recovery route is suppressed.

[0056] Probably due to the above-described features, the toner of the first exemplary embodiment suppresses contamination of the recording medium caused by clogging of the transfer residual toner recovery route regardless of whether the toner is heated.

[0057] Meanwhile, the electrostatic charge image developing toner according to the second exemplary embodiment includes toner particles containing a binder resin and a hydroxyl-containing low-molecular weight compound, and an external additive containing silica particles.

[0058] The content of the low molecular weight compound relative to the toner particles is 500 ppm or more and 50,000 ppm or less, and the proportion of components having a molecular weight of 50,000 or more in the molecular weight distribution obtained by measuring the tetrahydrofuran soluble portion of the toner particles by gel permeation chromatography is 15% by mass or more and 50% by mass or less.

[0059] Due to the above-described features, the toner of the second exemplary embodiment suppresses contamination of the recording medium caused by clogging of the transfer residual toner recovery route regardless of whether the toner is heated. The reason behind this is probably as follows.

[0060] The hydroxyl group-containing low molecular weight compound strongly adheres to the silica particles used as an external additive. Therefore, when the low molecular weight compound is present on the surface of the toner particles, the adhesion to the silica particles increases.

[0061] When the toner particles contain 15% or more and 50% or less of components having a molecular weight of 50,000 or more in the molecular weight distribution obtained by measuring the tetrahydrofuran soluble portion of the toner particles by gel permeation chromatography, the low molecular weight compound is not easily dispersed over the entire toner particles. As a result, a region rich in the low molecular weight compound and a region scarce in the low molecular weight compound are formed on the surface of one toner particle.

[0062] In other words, on the surface of a toner particle, a region rich in low-molecular-weight compounds constitutes "a region to which silica particles used as an external additive adhere with high adhesion", and a region scarce in low-molecular-weight compounds constitutes "a region to which silica particles used as an external additive adhere with low adhesion", thereby forming a structure in which these regions are distributed.

[0063] Therefore, similar to the toner of the first exemplary embodiment to a large extent, the toner of the second exemplary embodiment suppresses contamination of the recording medium caused by clogging of the transfer residual toner recovery route, regardless of whether the toner is heated.

[0064] Now, a toner corresponding to the two toners of the first exemplary embodiment and the second exemplary embodiment will be described in detail. Hereinafter, this toner may be referred to as "the toner of the exemplary embodiment". However, it is sufficient that one example of the toner of the present disclosure is a toner corresponding to one of the toners of the first exemplary embodiment and the second exemplary embodiment.

[0065] In the following description, the toner for developing a static charge image of this exemplary embodiment is described in detail.

[0066] Si content variation coefficient

[0067] In the toner of the exemplary embodiment, the change amount of the Si content variation coefficient before and after a specific treatment is 0.05 or more and 0.60 or less, and from the viewpoint of suppressing contamination of the recording medium, it is preferably 0.10 or more and 0.55 or less, and more preferably 0.15 or more and 0.50 or less.

[0068] From the viewpoint of suppressing contamination of the recording medium, the Si content variation coefficient after a specific treatment is preferably 0.20 or more and 0.80 or less, more preferably 0.25 or more and 0.75 or less, and still more preferably 0.30 or more and 0.70 or less.

[0069] Here, specifically, the treatment of dispersing the toner in water and drying the dispersed toner includes the following steps.

[0070] 1) A step of preparing an aqueous solution by adding 2 g of toner to 100 mL of a 0.2 mass% aqueous solution of Triton X-100 (produced by FUJIFILM Wako Pure Chemical Corporation).

[0071] 2) The step of stirring the prepared solution at 250 rpm for 10 minutes using a magnetic stirrer "HS-360 (AS ONE Corporation)", and then treating the resulting solution in a centrifugal separator to remove the silica particles that have been separated from the toner particles.

[0072] 3) The step of removing the silica particles that have been separated from the toner particles, and then drying the toner at a temperature of 40 °C for 24 hours.

[0073] The method for determining the Si content in a 0.5 μm × 0.5 μm square region on the surface of toner particles and the method for calculating the coefficient of variation of the Si content use a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDX device). The specific method is as follows.

[0074] First, observe one toner particle with the SEM at a magnification of 20,000x. Divide the surface of the observed one toner particle into 0.5 μm × 0.5 μm square regions (see Figure 3 , note that in Figure 3 , TN represents toner particles and SiO2 represents silica particles). Divide the surface so that the surface of the one toner particle contains the maximum number of 0.5 μm × 0.5 μm square regions.

[0075] Next, use the EDX device to perform elemental analysis on each divided region at an acceleration voltage of 5 kV to measure the Si element content (mass %).

[0076] Based on the Si content of each region, calculate the coefficient of variation of the Si content through the following formula: Coefficient of variation of Si content = (standard deviation) / (average value).

[0077] Perform this operation on ten toner particles and calculate the average value of the obtained coefficients of variation of the Si content.

[0078] Structure of the toner

[0079] The toner of the exemplary embodiment includes toner particles and external additives.

[0080] The toner particles contain a binder resin and a low molecular weight compound containing a hydroxyl group. If necessary, the toner particles may further contain a colorant, a release agent, and other additives.

[0081] Examples of the toner particles include, but are not limited to, yellow toner particles, magenta toner particles, cyan toner particles, black toner particles, white toner particles, transparent toner particles, and photoluminescent toner particles.

[0082] Binder resin

[0083] Examples of the binder resin include vinyl resins composed of homopolymers of monomers and copolymers obtained by combining two or more monomers. Examples of the monomers include styrene (e.g., styrene, p-chlorostyrene, and α-methylstyrene), (meth)acrylates (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, and 2-ethylhexyl methacrylate), ethylenically unsaturated nitriles (e.g., acrylonitrile and methacrylonitrile), vinyl ethers (e.g., vinyl methyl ether and vinyl isobutyl ether), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone), and olefins (e.g., ethylene, propylene, and butadiene).

[0084] Examples of the binder resin also include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin, mixtures of the above non-vinyl resins and vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in their co-presence.

[0085] These binder resins can be used alone or in combination.

[0086] The binder resin can be a polyester resin.

[0087] Examples of the polyester resin include known polyester resins.

[0088] Examples of the polyester resin are condensates of polycarboxylic acids and polyols. Commercially available polyester resins can be used, or polyester resins prepared by synthesis can be used.

[0089] Examples of the polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaric acid, succinic acid, alkenyl succinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid), their acid anhydrides, and their lower (e.g., having 1 to 5 carbon atoms) alkyl esters. Among them, aromatic dicarboxylic acids can be used as the polycarboxylic acids.

[0090] For the polycarboxylic acids, polyvalent carboxylic acids having a crosslinked structure or a branched structure can be used in combination with the dicarboxylic acids. Examples of the polyvalent carboxylic acids include trimellitic acid, pyromellitic acid, their acid anhydrides, and their lower (e.g., having 1 to 5 carbon atoms) alkyl esters.

[0091] The polycarboxylic acids can be used alone or in combination.

[0092] Examples of the polyol include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, hexylene glycol, and neopentyl glycol), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A), and aromatic diols (e.g., ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A). Among them, the polyol is preferably an aromatic diol or an alicyclic diol, and more preferably an aromatic diol.

[0093] For the polyol, a triol or higher polyol having a crosslinked structure or a branched structure can be used in combination with the diol. Examples of the triol or higher polyol include glycerin, trimethylolpropane, and pentaerythritol.

[0094] The polyol can be used alone or in combination.

[0095] The glass transition temperature (Tg) of the polyester resin is preferably 45 °C or higher and 80 °C or lower, and more preferably 50 °C or higher and 70 °C or lower.

[0096] The glass transition temperature is determined by the DSC curve obtained by differential scanning calorimetry (DSC). More specifically, the glass transition temperature is determined by the "extrapolated glass transition start temperature" described in the method for determining the glass transition temperature in JIS K7121-1987 "Test Method for Transition Temperature of Plastics".

[0097] The weight average molecular weight (Mw) of the polyester resin is preferably 5000 or higher and 1000000 or lower, and more preferably 7000 or higher and 500000 or lower.

[0098] The number average molecular weight (Mn) of the polyester resin can be 2000 or higher and 100000 or lower.

[0099] The molecular weight distribution Mw / Mn of the polyester resin is preferably 1.5 or higher and 100 or lower, and more preferably 2 or higher and 60 or lower.

[0100] The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement of GPC is carried out using GPC HLC-8120PC produced by TOSOH CORPORATION, TSKgel Super HM-M (15 cm) produced by TOSOH CORPORATION, and THF solvent as the measuring instrument with a chromatographic column. The weight average molecular weight and the number average molecular weight are calculated from the measurement results by using the molecular weight calibration curve obtained from the monodisperse polystyrene standard sample.

[0101] The polyester resin is obtained by a known production method. Specifically, for example, by setting the polymerization temperature to 180 °C or higher and 230 °C or lower, reducing the pressure in the reaction system as needed, and reacting while removing the water and alcohol generated during the condensation process, the polyester resin is obtained.

[0102] When the monomers used as raw materials are insoluble or incompatible with each other at the reaction temperature, a solvent with a high boiling point can be added as a co-solvent to dissolve the monomers. In this case, the polycondensation reaction is carried out while distilling off the co-solvent. When there are incompatible monomers, the incompatible monomers and the acid or alcohol to be polycondensed with the monomer can be preliminarily condensed, and then the resulting product can be polycondensed with another component.

[0103] The amount of the binder resin relative to the entire toner particles is preferably, for example, 40% by mass or more and 98% by mass or less, more preferably 50% by mass or more and 96% by mass or less, and still more preferably 60% by mass or more and 94% by mass or less.

[0104] Low molecular weight compound

[0105] The low molecular weight compound has a hydroxyl group. Here, the low molecular weight compound refers to an organic compound having a molecular weight of 50 or more and 600 or less (preferably 60 or more and 500 or less, more preferably 80 or more and 400 or less).

[0106] Examples of the low molecular weight compound include phenolic compounds, hydroxycarboxylic acids or their ester compounds, alcohol compounds, and ester compounds of polyols. The low molecular weight compounds can be used alone or in combination.

[0107] Among them, from the perspective of suppressing the contamination of the recording medium, at least one selected from phenolic compounds, hydroxycarboxylic acids and their ester compounds, and alcohol compounds can be used as the low molecular weight compound.

[0108] Phenolic compounds are compounds having a phenolic hydroxyl group. Examples of phenolic compounds include substituted phenols containing one hydroxyl group (phenol, cresol, xylenol, p-alkylphenol, p-phenylphenol, etc.), substituted phenols containing two hydroxyl groups (catechol, resorcinol, hydroquinone, etc.), bisphenols (bisphenol A, bisphenol Z, etc.), and substituted phenols containing three or more hydroxyl groups (pyrogallol, phloroglucinol, hexahydroxybenzene, etc.).

[0109] Examples of the hydroxycarboxylic acids and their ester compounds include lactic acid, malic acid, citric acid, 12-hydroxy stearic acid, ricinoleic acid, salicylic acid, and their ester compounds.

[0110] Alcohol compounds are compounds having an alcohol hydroxyl group. Examples of alcohol compounds are as follows.

[0111] Examples of monohydric alcohols include fatty alcohols (decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, and ricinoleyl alcohol) and aromatic alcohols (benzyl alcohol, phenethyl alcohol, salicyl alcohol, and diphenylmethanol).

[0112] Examples of dihydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, hexylene glycol, and neopentyl glycol) and alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A).

[0113] Aromatic diols (e.g., alkylene oxide adducts of bisphenol A (bisphenol A-ethylene oxide adduct, bisphenol A-propylene oxide adduct, and bisphenol A-butylene oxide adduct)).

[0114] Trihydric alcohols or higher polyhydric alcohols (e.g., glycerin, trimethylolpropane, and pentaerythritol).

[0115] Examples of ester compounds of polyhydric alcohols include ester compounds having a hydroxyl group, such as monoglyceride fatty acids and diglyceride fatty acids, and the like.

[0116] In particular, from the viewpoint of suppressing contamination of the recording medium, the low molecular weight compound is preferably an alcohol compound, more preferably a monohydric or dihydric aromatic alcohol, and still more preferably a bisphenol A-alkylene oxide adduct.

[0117] When the polyester resin is used as the binder resin, from the viewpoint of suppressing contamination of the recording medium, the absolute value |Cp - CL| of the difference between the average number of carbon atoms Cp in the polyhydric alcohol constituting the polyester resin and the number of carbon atoms CL in the low molecular weight compound is preferably |Cp - CL| ≤ 8, more preferably |Cp - CL| ≤ 7, and still more preferably |Cp - CL| ≤ 6.

[0118] When the relationship between the polyester resin and the low molecular weight compound is the above relationship, the low molecular weight compound is easily and appropriately dispersed over the entire toner particle. Therefore, in the surface of one toner particle, a structure in which regions rich in the low molecular weight compound (in other words, regions where silica particles used as external additives adhere with high adhesion) and regions scarce in the low molecular weight compound (in other words, regions where silica particles used as external additives adhere with low adhesion) are almost uniformly distributed is more likely to be formed.

[0119] As a result, regardless of whether the toner is heated, contamination of the recording medium due to clogging of the transfer residual toner recovery route is easily suppressed.

[0120] The content of the low molecular weight compound is 500 ppm or more and 50,000 ppm or less. From the perspective of suppressing the contamination of the recording medium, the content of the low molecular weight compound is preferably 1,000 ppm or more and 40,000 ppm or less, more preferably 2,000 ppm or more and 30,000 ppm or less, and still more preferably 2,500 ppm or more and 25,000 ppm or less. ppm is based on mass.

[0121] The measurement of the content of the low molecular weight compound is as follows.

[0122] 1) Disperse 1 g of the toner in 10 ml of methanol, apply ultrasonic waves, and extract the supernatant.

[0123] 2) Using the obtained supernatant, identify the low molecular weight compound containing a hydroxyl group by H-NMR.

[0124] 3) Measure a methanol solution containing a specific low molecular weight compound with a known concentration by high performance liquid chromatography (HPLC), and prepare a calibration curve based on the obtained spectrum.

[0125] 4) Measure the supernatant obtained by high performance liquid chromatography (HPLC), and calculate the content of the specified low molecular weight compound based on the obtained spectrum and the calibration curve.

[0126] The instruments and conditions used in high performance liquid chromatography (HPLC) are as follows.

[0127] Analyzer: Lachromelite L-2000, Hitachi High-Technologies Corporation

[0128] Column: Gelpack GL-W520-S (diameter 7.8 mm × 300 mm), Hitachi Chemical Co., Ltd.

[0129] Detector: Type L-2455 diode array detector, Hitachi High-Technologies Corporation

[0130] Measurement wavelength: UV 190 nm to 400 nm

[0131] Quantitative analysis wavelength: UV 284 nm

[0132] Mobile phase: 50 mM dipotassium hydrogen phosphate

[0133] Liquid feed rate: 1.0 mL / min

[0134] Sample injection volume: 10 μL

[0135] Colorant

[0136] Examples of colorants include pigments such as carbon black, chrome yellow, Hansa yellow, benzidine yellow, Vat yellow, quinoline yellow, pigment yellow, Permanent Orange GTR, pyrazolone orange, Vulcan Orange, juice red, Permanent Red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, Lithol red, rhodamine B lake, lake red C, pigment red, rose red, aniline blue, ultramarine blue, Calco oil blue, methylene chloride blue, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, and dyes such as acridine dyes, xanthene dyes, azo dyes, benzoquinone dyes, azine dyes, anthraquinone dyes, thioindigo dyes, dioxazine dyes, thiazine dyes, azomethine dyes, indigo dyes, phthalocyanine dyes, aniline black dyes, polymethine dyes, triphenylmethane dyes, diphenylmethane dyes, and thiazole dyes.

[0137] These colorants can be used alone or in combination.

[0138] The colorant can be a surface-treated colorant, or if necessary, it can be used in combination with a dispersant. Two or more colorants can be used in combination.

[0139] The amount of the colorant relative to the entire toner particles is preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less.

[0140] Release agent

[0141] Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral or petroleum waxes such as lignite wax, and ester waxes such as fatty acid esters and montanic acid esters. The release agent is not limited thereto.

[0142] The melting temperature of the release agent is preferably 50°C or more and 110°C or less, and more preferably 60°C or more and 100°C or less.

[0143] The melting temperature is determined by the method described in "melting peak temperature" based on the DSC curve obtained by differential scanning calorimetry (DSC), which is one of the methods for determining the melting temperature in JIS K7121-1987 "Test Method for Plastics Transition Temperature".

[0144] The content of the release agent relative to, for example, the entire toner particles is preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less.

[0145] Other additives

[0146] Examples of other additives include known additives such as magnetic materials, charge controllers, and inorganic powders. These additives are internal additives and are contained inside the toner particles.

[0147] Properties of toner particles, etc.

[0148] The toner particles may be single-layer structured toner particles or core-shell structured toner particles, and each core-shell structured toner particle is composed of a core (core particle) and a coating layer (shell) coating the core.

[0149] The core-shell toner particles may include, for example, a core containing a binder resin, optionally a colorant, and other additives (such as a release agent, etc.), and a coating layer containing a binder resin.

[0150] The low molecular weight compound may be present at least on the surface of the toner particles and may be included in the core and coating portions.

[0151] The proportion of the component having a molecular weight of 50,000 or more in the molecular weight distribution obtained by measuring the tetrahydrofuran-soluble portion (hereinafter also referred to as "THF-soluble portion") of the toner particles by gel permeation chromatography (hereinafter also referred to as "GPC measurement") is 15% by mass or more and 50% by mass or less (preferably 20% by mass or more and 45% by mass or less, and more preferably 22% by mass or more and 42% by mass or less).

[0152] When the proportion of the component having a molecular weight of 50,000 or more in the molecular weight distribution obtained by GPC measurement of the THF-soluble portion in the toner particles is within the above range, the low molecular weight compound is not easily dispersed over the entire toner particles. As a result, contamination of the recording medium due to clogging of the transfer residual toner recovery route is suppressed regardless of whether the toner is heated.

[0153] The molecular weight distribution and the proportion of the component having a molecular weight of 50,000 or more in the GPC measurement of the THF-soluble portion in the toner particles are measured as follows.

[0154] First, 0.5 mg of the toner particles (or toner) to be measured is dissolved in 1 g of tetrahydrofuran (THF). The resulting mixture is ultrasonically dispersed and adjusted to a concentration of 0.5%. Then the dissolved components are measured by GPC.

[0155] As a GPC system, “HLC-8120PC, SC-8020 (manufactured by Tosoh Corporation)” was used. Two chromatographic columns were used: “TSKgel, SuPermH-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15 cm)”. THF was used as the eluent. The experimental conditions were as follows: sample concentration: 0.5%, flow rate: 0.6 ml / min, sample injection volume: 10 μl, measurement temperature: 40 °C, and the experiment was carried out using a refractive index (RI) detector. The calibration curve was made from ten samples of “polystyrene standard sample, TSK standard”: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”, “F-4”, “F-40”, “F-128”, and “F-700”. The data collection interval in the sample analysis was set to 300 ms.

[0156] Based on the obtained molecular weight distribution (in other words, the GPC chart), the area with a molecular weight of 50,000 or more was integrated to calculate the proportion of the component with a molecular weight of 50,000.

[0157] From the perspective of suppressing the contamination of the recording medium, the ratio B1 / B2 of the measured specific surface area B1 of the toner particles to the calculated specific surface area B2 of the toner particles determined based on the volume average particle diameter is preferably 1.2 or more and 5.0 or less, more preferably 1.4 or more and 4.5 or less, and still more preferably 1.5 or more and 4.0 or less.

[0158] It is considered that by setting the ratio of the measured value B1 to the specific surface area B2 within the aforementioned range, appropriate irregularities are formed on the surface of the toner particles. Therefore, it is easy to suppress the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route, regardless of whether the toner is heated.

[0159] From the perspective of suppressing the contamination of the recording medium, the measured specific surface area B1 of the toner particles is preferably 0.5 m 2 / g or more and 10.0 m 2 / g or less, and more preferably 0.6 m 2 / g or more and 8.0 m 2 / g or less.

[0160] At the same time, the calculated specific surface area B2 of the toner particles determined based on the volume average particle diameter is preferably 0.4 m 2 / g or more and 5 m 2 / g or less, and more preferably 0.5 m 2 / g or more and 4.0 m 2 / g or less.

[0161] The measured value B1 of the specific surface area of the toner particles is the value measured by the nitrogen adsorption method. Specifically, it is measured by the BET method and the single-point measurement method of the nitrogen adsorption method. The equilibrium relative pressure is set to 0.3.

[0162] Meanwhile, the calculated specific surface area B2 of the toner particles determined according to the volume average particle diameter is measured as follows. B2 = (surface area of the toner particles) / {(specific gravity of the toner particles)×(volume of the toner particles)}

[0163] Here, when the volume average particle diameter of the toner is D50v,

[0164] (surface area of the toner) = 4×π×(D50v / 2) 2

[0165] (volume of the toner) = 4 / 3×π×(D50v / 2) 3

[0166] The volume average particle diameter (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0167] Use a Coulter Counter II (manufactured by Beckman Coulter Inc.) and use ISOTON-II (manufactured by Beckman Coulter Inc.) as the electrolyte to measure various average particle diameters and particle size distribution indices of the toner particles.

[0168] In the measurement, a measurement sample of 0.5 mg or more and 50 mg or less is added to a 5% aqueous solution of 2 ml of a surfactant (which can be sodium alkylbenzene sulfonate) used as a dispersant. The resulting mixture is added to an electrolyte of 100 ml or more and 150 ml or less.

[0169] The electrolyte in which the sample is suspended is dispersed in an ultrasonic disperser for 1 minute, and a Coulter Counter II with a pore diameter of 100 μm is used to measure the particle size distribution of particles in the range of 2 μm or more and 60 μm or less in diameter. The number of sampled particles is 50,000.

[0170] Regarding the particle size ranges (channels) divided based on the measured particle size distribution, the cumulative distributions of volume and number are plotted from the small diameter side. The particle diameter at which the cumulative is 16% is defined as the volume particle diameter D16v and the number particle diameter D16p, the particle diameter at which the cumulative is 50% is defined as the volume average particle diameter D50v and the cumulative number average particle diameter D50p, and the particle diameter at which the cumulative is 84% is defined as the volume particle diameter D84v and the number particle diameter D84p.

[0171] By using these values, the volume grain size distribution index (GSDv) is calculated as (D84v / D16v) 1 / 2 , and the number grain size distribution index (GSDp) is calculated as (D84p / D16p) 1 / 2 .

[0172] The average roundness 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.

[0173] The average roundness of the toner particles is determined according to (circular equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)]. Specifically, it is a value measured by the following method.

[0174] First, the toner particles to be measured are sampled by suction to form a laminar flow, and the particle image as a still image is captured by performing instantaneous flash illumination. The particle image is analyzed by a flow particle image analyzer (FPIA - 3000 manufactured by Sysmex Corporation) to determine the average roundness. When determining the average roundness, the number of sampled particles is 3500.

[0175] When the toner contains an external additive, 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 additive has been removed.

[0176] External additive

[0177] Silica particles are used as the external additive.

[0178] The volume - average particle diameter of the silica particles is preferably 40 nm or more and 400 nm or less, more preferably 50 nm or more and 300 nm or less, still more preferably 55 nm or more and 250 nm or less, and still more preferably 60 nm or more and 200 nm or less.

[0179] When the average particle diameter of the silica particles is within the above range, it is easy to control the adhesion force to the toner particles, and the silica particles easily exhibit a spacing function between the toner particles. Therefore, it is easy to suppress the contamination of the recording medium caused by the clogging of the transfer - residual toner recovery route.

[0180] The volume - average particle diameter of the silica particles is measured by the following method.

[0181] The primary particles of the silica particles were observed and imaged using a scanning electron microscope (SEM) (S-4100 manufactured by Hitachi, Ltd.). The obtained image was captured in an image analyzer (LUZEX III manufactured by NIRECO) to calculate the area of each particle by image analysis of the primary particles and calculate the equivalent circle diameter from the area value. The equivalent circle diameters of 100 silica particles were calculated. Then, assuming that 50% of the diameter (D50V) in the volume-based cumulative frequency of the obtained equivalent circle diameters is the volume average particle diameter of the silica particles.

[0182] The magnification of the electron microscope was adjusted so that 10 to 50 silica particles were included in one observation area, and multiple observation areas were combined to determine the equivalent circle diameter of the primary particles.

[0183] The average roundness of the silica particles is preferably 0.75 or more and 1.0 or less, more preferably 0.9 or more and 1.0 or less, and still more preferably 0.92 or more and 0.98 or less.

[0184] When the average roundness is within the above range, the silica particles become more spherical, the adhesion force to the toner particles is easily controlled, and the silica particles easily exhibit a spacing function between the toner particles. Therefore, it is easy to suppress the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0185] The average roundness of the silica particles was measured by the following method.

[0186] First, the primary particles of the silica particles were observed using SEM, and the roundness of the silica particles was determined by calculating "100 / SF2" obtained by the following formula from the planar image analysis of the obtained primary particles:

[0187] Formula: Roundness (100 / SF2) = 4π×(A / I 2 )

[0188] Wherein, I represents the perimeter of the primary particles on the image, and A represents the projected area of the primary particles.

[0189] The average roundness of the obtained silica particles is the 50% roundness in the cumulative frequency of the roundness of 100 primary particles obtained by the above planar image analysis.

[0190] The water content of the silica particles is preferably 0.5% by mass or more and 5.0% by mass or less, more preferably 0.6% by mass or more and 4.5% by mass or less, and still more preferably 0.8% by mass or more and 4.0% by mass or less.

[0191] When the water content of the silica particles is within the above range, the adhesion force to the toner particles is easily controllable. Therefore, it is easy to suppress the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0192] The water content of the silica particles is measured as follows.

[0193] First, toner is added to a methanol-ethanol (1:1) mixed solution, suspended and ultrasonicated, and the resulting mixture is separated into toner particles and external additives by using a centrifugal separator to obtain a supernatant, which is a suspension containing silica particles. The supernatant is dried to obtain the dried external additives, and the dried silica particles are stored in a constant temperature oven at 30 °C and 80% for 24 hours. Then, the water content of the silica particles after being stored in the constant temperature oven is measured using a thermal dry moisture analyzer.

[0194] The surface of the silica particles can be hydrophobized. Hydrophobization includes, for example, immersing the inorganic particles in a hydrophobizing agent. The hydrophobizing agent can be any hydrophobizing agent, examples of which include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These hydrophobizing agents can be used alone or in combination.

[0195] The amount of the hydrophobizing agent is usually 1 part by mass or more and 50 parts by mass or less relative to 100 parts by mass of the silica particles.

[0196] The content of the silica particles is preferably 0.5% by mass or more and 5.0% by mass or less, more preferably 0.8% by mass or more and 4.6% by mass or less, and still more preferably 1.0% by mass or more and 4.2% by mass or less relative to the toner particles.

[0197] External additives other than the silica particles can be used in combination with the silica particles.

[0198] Examples of additional external additives are inorganic particles. Examples of the inorganic particles include TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2)n, Al2O 3· 2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0199] The surface of the inorganic particles used as additional external additives can be hydrophobized. Hydrophobization can include, for example, immersing the inorganic particles in a hydrophobizing agent. The hydrophobizing agent can be any hydrophobizing agent, examples of which include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These hydrophobizing agents can be used alone or in combination.

[0200] The amount of the hydrophobic agent is usually 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles.

[0201] Examples of additional external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), melamine resin, etc.) and cleaning activators (for example, particles of higher fatty acid metal salts (such as zinc stearate, etc.) and fluorine-based high molecular weight materials).

[0202] The external addition amount of the additional external additives with respect to the toner particles is, for example, preferably 0.01 mass% or more and 5 mass% or less, and more preferably 0.01 mass% or more and 2.0 mass% or less.

[0203] Method for producing toner

[0204] Next, a method for producing the toner of the exemplary embodiment will be described.

[0205] The toner of the exemplary embodiment is obtained by preparing toner particles and then externally adding external additives to the toner particles.

[0206] The toner particles can be produced by a dry method (for example, a kneading and pulverizing method) or a wet method (for example, an aggregation and coalescence method, a suspension polymerization method, or a dissolution suspension method). The toner particles can be made by any known process.

[0207] Among these methods, the aggregation and coalescence method can be used to produce toner particles.

[0208] Specifically, for example, when the toner particles are produced by the aggregation and coalescence method, the toner particles are produced through the following steps: preparing a resin particle dispersion liquid containing dispersed resin particles that will be used as a binder resin (resin particle dispersion liquid preparation step); causing resin particles (if necessary, other particles) to aggregate in the resin particle dispersion liquid (if necessary, a dispersion liquid after mixing with other particle dispersion liquids) to form aggregated particles (aggregated particle formation step); and heating the aggregated particle dispersion liquid containing the dispersed aggregated particles to fuse and coalesce the aggregated particles to form toner particles (fusion and coalescence step).

[0209] When producing toner particles by the aggregation and coalescence method, the method for adding the low molecular weight compound to the toner particles is not particularly limited. One example of the method is a method including the following steps: adding the low molecular weight compound to the resin particle dispersion liquid, and causing resin particles (if necessary, other particles) to aggregate in the resin particle dispersion liquid containing the low molecular weight compound, thereby forming aggregated particles.

[0210] These steps will now be described in detail.

[0211] In the following description, a method for obtaining toner particles containing a colorant and a release agent is described; however, the colorant and the release agent are optional. Of course, additives other than the colorant and the release agent can be used.

[0212] Resin particle dispersion preparation step

[0213] First, a resin particle dispersion containing dispersed resin particles to be used as a binder resin is prepared, and for example, a colorant particle dispersion containing dispersed colorant particles and a release agent particle dispersion containing dispersed release agent particles are prepared.

[0214] The resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0215] Examples of the dispersion medium used in the resin particle dispersion include aqueous media.

[0216] Examples of the aqueous medium include water (such as distilled water and ion-exchanged water, etc.) and alcohols. These aqueous media can be used alone or in combination.

[0217] Examples of the surfactant include: anionic surfactants such as sulfates, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol, alkylphenol-ethylene oxide adducts, and polyols. Among them, anionic surfactants or cationic surfactants can be used. Nonionic surfactants can be used in combination with anionic surfactants or cationic surfactants.

[0218] The surfactant can be used alone or in combination.

[0219] Examples of the method for dispersing resin particles in a dispersion medium to obtain a resin particle dispersion include typical dispersion methods such as using a rotary shear homogenizer and ball mills, sand mills, and Dyno mills using a medium. Depending on the type of resin particles, for example, the resin particles can be dispersed in the resin particle dispersion by a phase inversion emulsification method.

[0220] The phase inversion emulsification method is a method including the following steps: dissolving the resin to be dispersed in a hydrophobic organic solvent capable of dissolving the resin, adding an alkali to the organic continuous phase (O phase) for neutralization, and injecting an aqueous medium (W phase) to perform resin conversion (phase inversion) from W / O to O / W, thereby forming a discontinuous phase and dispersing the resin particles in the aqueous medium.

[0221] The volume average particle diameter of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and still more preferably 0.1 μm or more and 0.6 μm or less.

[0222] The volume average particle diameter of the resin particles is measured by the following steps: The particle size distribution is obtained by measurement using a laser diffraction scattering particle size distribution analyzer (for example, LA-700 manufactured by Horiba Ltd.), the volume cumulative distribution is plotted from the small particle size side with respect to the divided particle size ranges (channels), and the particle diameter at which 50% of all the particles are cumulative is determined as the volume average particle diameter D50v. The volume average particle diameter of other particles in the dispersion is also measured in the same manner.

[0223] The resin particle content in the resin particle dispersion is, for example, preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0224] For example, the colorant particle dispersion and the mold release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. Matters related to the volume average particle diameter, dispersion medium, dispersion method, and particle content of the resin particle dispersion also apply to the colorant particles dispersed in the colorant particle dispersion and the mold release agent particles dispersed in the mold release agent particle dispersion.

[0225] Agglomerate particle formation step

[0226] Next, the resin particle dispersion is mixed with the colorant particle dispersion and the mold release agent particle dispersion.

[0227] In the mixed dispersion, hetero-aggregation of the resin particles, colorant particles, and mold release agent particles is induced to form agglomerate particles containing the resin particles, colorant particles, and mold release agent particles and having a diameter close to the toner particle diameter.

[0228] Specifically, for example, while adjusting the pH of the mixed dispersion to acidic (for example, pH of 2 or more and 5 or less), an aggregating agent is added to the mixed dispersion, and after adding a dispersion stabilizer as needed, the dispersion is heated to a temperature equal to or lower than the glass transition temperature of the resin particles (specifically, for example, a temperature 10°C to 30°C lower than the glass transition temperature of the resin particles) to cause the particles dispersed in the mixed dispersion to aggregate and form agglomerate particles.

[0229] In the step of forming aggregated particles, for example, when a dispersion is stirred and mixed in a rotary shear homogenizer, a flocculant can be added to the mixed dispersion at room temperature (e.g., 25 °C), and the pH of the mixed dispersion can be adjusted to acidic (e.g., pH of 2 or more and 5 or less), and then heating can be carried out after adding a dispersion stabilizer as needed.

[0230] Examples of the flocculant include surfactants having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, inorganic metal salts, and metal complexes having a valence of 2 or more. In particular, when a metal complex is used as the flocculant, the amount of the surfactant used is reduced, and the charge properties are improved.

[0231] An additive that forms a complex or a similar bond with the metal ion in the flocculant can be used as needed. Examples of such an additive are chelating agents.

[0232] Examples of the inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0233] Water-soluble chelating agents can be used as chelating agents. Examples of the chelating agents include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA).

[0234] The addition amount of the chelating agent 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 3.0 parts by mass or less with respect to 100 parts by mass of the resin particles.

[0235] Fusion and coalescence step

[0236] Next, the aggregated particle dispersion containing the dispersed aggregated particles is heated to a temperature equal to or higher than the glass transition temperature of the resin particles (e.g., a temperature 10 °C to 30 °C higher than the glass transition temperature of the resin particles) so that the aggregated particles fuse and bond to form toner particles.

[0237] Toner particles are obtained through the above steps.

[0238] Note that toner particles can be produced by performing the following steps after obtaining an aggregate particle dispersion liquid containing dispersed aggregate particles: a step of forming second aggregate particles, which includes mixing a resin particle dispersion liquid containing dispersed resin particles with the aggregate particle dispersion liquid to initiate aggregation so as to adhere the resin particles to the surface of the aggregate particles; and heating the second aggregate particle dispersion liquid containing dispersed second aggregate particles to cause the second aggregate particles to fuse and combine to form toner particles having a core / shell structure.

[0239] Here, after the fusion and coalescence step is completed, the toner particles formed in the solution are subjected to known washing steps, solid-liquid separation steps, and drying steps to obtain toner particles in a dry state.

[0240] From the perspective of chargeability, the washing step may include thorough replacement washing with ion-exchanged water. The solid-liquid separation step is not particularly limited; however, from the perspective of productivity, suction filtration, pressure filtration, etc. can be performed. The drying step is also not particularly restricted; however, from the perspective of productivity, freeze drying, rapid drying, fluid drying, vibration type fluid drying, etc. can be performed.

[0241] The toner of this exemplary embodiment is produced by, for example, adding an external additive to the obtained toner particles in a dry state and mixing the resulting mixture. The mixing can be performed by using a V-type mixer, a Hensche mixer, a Loedige mixer, etc. If necessary, a vibrating sieve, an air sieve, etc. can be used to remove coarse particles of the toner.

[0242] Electrostatic charge image developer

[0243] The electrostatic charge image developer of the exemplary embodiment contains at least the toner of the exemplary embodiment.

[0244] The electrostatic charge image developer of the exemplary embodiment can be a one-component developer containing only the toner of the exemplary embodiment, or a two-component developer that is a mixture of the toner and a carrier.

[0245] The carrier is not particularly limited and can be any known carrier. Examples of the carrier include a coated carrier prepared by covering the surface of a magnetic powder core with a coating resin, a magnetic powder dispersed carrier prepared by dispersing and mixing magnetic powder in a matrix resin, and a resin-impregnated carrier prepared by impregnating porous magnetic powder with a resin.

[0246] The magnetic powder dispersed carrier and the resin-impregnated carrier can each be a carrier prepared by covering a core formed of the particles constituting the carrier with a coating resin.

[0247] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0248] Examples of the coating resin and the base resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylate copolymer, linear silicone resin containing organosiloxane bonds and modified products thereof, fluororesin, polyester, polycarbonate, phenolic resin, and epoxy resin.

[0249] The coating resin and the base resin may contain other additives such as conductive particles.

[0250] Examples of the conductive particles include particles of metals such as gold, silver, and copper, and particles of carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0251] For example, in order to cover the surface of the core with the coating resin, the following method can be used, which includes using a coating-forming solution prepared by dissolving the coating resin and various additives (if necessary) in a suitable solvent. The solvent is not particularly limited and can be selected by considering the coating resin used, the applicability of the application, etc.

[0252] Specific examples of the resin coating method include an impregnation method of immersing the core in the coating-forming solution, a spraying method of spraying the coating-forming solution onto the surface of the core, a fluidized bed method of spraying the coating-forming solution while floating the core on an air bed, and a kneader coater method of mixing the core used as a carrier and the coating-forming solution in a kneader coater and removing the solvent.

[0253] In the two-component developer, the mixing ratio (mass ratio) of the toner to the carrier is preferably 1:100 to 30:100, and more preferably 3:100 to 20:100.

[0254] Image forming apparatus and image forming method

[0255] Now, the image forming apparatus and the image forming method of this exemplary embodiment will be described.

[0256] An image forming apparatus according to an exemplary embodiment includes: an image carrier; a charging unit that charges the surface of the image carrier; an electrostatic charge image forming unit that forms an electrostatic charge image on the charged surface of the image carrier; a developing unit that contains an electrostatic charge image developer and develops the electrostatic charge image on the surface of the image carrier by using the electrostatic charge image developer, thereby forming a toner image; a transfer unit that transfers the toner image on the surface of the image carrier to the surface of a recording medium; and a fixing unit that fixes the toner image on the surface of the recording medium. The electrostatic charge image developer of the exemplary embodiment is used as the above-described electrostatic charge image developer.

[0257] An image forming method (image forming method of an exemplary embodiment) is performed by using the image forming apparatus of the exemplary embodiment. The method includes a charging step of charging the surface of the image carrier, an electrostatic charge image forming step of forming an electrostatic charge image on the charged surface of the image carrier, a developing step of developing the electrostatic charge image on the surface of the image carrier by using the electrostatic charge image developer of the exemplary embodiment, thereby forming a toner image, a transfer step of transferring the toner image on the surface of the image carrier to the surface of the recording medium, and a fixing step of fixing the toner image on the surface of the recording medium.

[0258] The image forming apparatus of the exemplary embodiment is applied to known image forming apparatuses. Examples thereof include: a direct transfer type apparatus in which the toner image formed on the surface of the image carrier is directly transferred to the recording medium; an intermediate transfer type apparatus in which the toner image formed on the surface of the image carrier is first transferred to the surface of an intermediate transfer member, and then the toner image on the surface of the intermediate transfer member is transferred to the surface of the recording medium; an apparatus equipped with a cleaning unit that cleans the surface of the image carrier after the transfer of the toner image and before charging; and an apparatus equipped with a charge erasing unit that erases the charge on the surface of the image carrier by applying charge erasing light after the transfer of the toner image and before charging.

[0259] In the intermediate transfer type apparatus, the transfer unit includes, for example, an intermediate transfer member having a surface on which the toner image is to be transferred, a first transfer unit that transfers the toner image on the surface of the image carrier to the surface of the intermediate transfer member for the first time, and a second transfer unit that transfers the toner image on the surface of the intermediate transfer member to the surface of the recording medium for the second time.

[0260] In the image forming apparatus of the exemplary embodiment, for example, a portion including the developing unit may be configured to be detachably attached to a cartridge structure (processing cartridge) of the image forming apparatus. The processing cartridge equipped with the developing unit containing the electrostatic charge image developer of the exemplary embodiment can be used as the processing cartridge.

[0261] Although some examples of an image forming apparatus according to an exemplary embodiment are described below, these examples are not restrictive. Only the relevant parts shown in the drawings are described, and the description of other parts is omitted.

[0262] Figure 1 is a schematic diagram of an image forming apparatus according to an exemplary embodiment.

[0263] Figure 1 The illustrated image forming apparatus is provided with a first electrophotographic image forming unit 10Y, a second electrophotographic image forming unit 10M, a third electrophotographic image forming unit 10C, and a fourth electrophotographic image forming unit 10K (image forming units), and the first electrophotographic image forming unit 10Y to the fourth electrophotographic image forming unit 10K output a yellow (Y) image, a magenta (M) image, a cyan (C) image, and a black (K) image based on color-separated image data, respectively. These image forming units (hereinafter may be simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side in the horizontal direction at a predetermined distance from each other. Each of these units 10Y, 10M, 10C, and 10K may be a process cartridge detachably attached to the image forming apparatus.

[0264] An intermediate transfer belt 20 serving as an intermediate transfer body for all the units extends above the units 10Y, 10M, 10C, and 10K in the drawing. The intermediate transfer belt 20 is wound around a driving roller 22 and a support roller 24 spaced apart from each other in the horizontal direction in the drawing, and extends in the direction from the first unit 10Y to the fourth unit 10K. The support roller 24 is in contact with the inner surface of the intermediate transfer belt 20. A force is applied to the support roller 24 in a direction away from the driving roller 22 by a spring or the like (not shown), thereby applying tension to the intermediate transfer belt 20 wound around these two rollers. An intermediate transfer body cleaning device 30 is mounted on the image carrier side surface of the intermediate transfer belt 20 to face the driving roller 22.

[0265] The toners of four colors (i.e., yellow, magenta, cyan, and black) contained in the toner cartridges 8Y, 8M, 8C, and 8K are respectively supplied to the developing devices (developing units) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K.

[0266] Since the first unit 10Y to the fourth unit 10K are identical in structure, the first unit 10Y that forms a yellow image and is provided on the upstream side in the running direction of the intermediate transfer belt is described as a representative example. By replacing the reference numerals of yellow with those of magenta (M), cyan (C), and black (K), the description of the second unit 10M to the fourth unit 10K can be omitted.

[0267] The first unit 10Y has a photoreceptor 1Y that serves as an image carrier. Around the photoreceptor 1Y, there are provided: a charging roller (an example of a charging unit) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic charge image forming unit) 3 that forms an electrostatic charge image by exposing the charged surface with a laser beam 3Y based on a color-separated image signal; a developing device (an example of a developing unit) 4Y that develops the electrostatic charge image by supplying charged toner to the electrostatic charge image; a first transfer roller 5Y (an example of a first transfer unit) that transfers the developed toner image onto an intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning unit) 6Y that removes the toner remaining on the surface of the photoreceptor 1Y after the first transfer.

[0268] The first transfer roller 5Y is disposed inside the intermediate transfer belt 20 and is positioned to face the photoreceptor 1Y. The first transfer rollers 5Y, 5M, 5C, and 5K are respectively connected to a bias power source (not shown) that applies a first transfer bias. The transfer bias applied to each first transfer roller from the corresponding bias power source is controlled by a controller (not shown in the figure) and is variable.

[0269] Now, the operation of forming a yellow image by using the first unit 10Y will be described.

[0270] Before the operation, the surface of the photoreceptor 1Y is charged to a potential of -600 V to -800 V by using the charging roller 2Y.

[0271] The photoreceptor 1Y is formed by stacking a photosensitive layer on a conductive (e.g., volume resistivity at 20 °C: 1 × 10 -6 Ωcm or less) substrate. The photosensitive layer generally has a high resistivity (resistivity of ordinary resin), but when irradiated with the laser beam 3Y, the resistivity of the portion irradiated with the laser beam changes. The laser beam 3Y is output to the charged surface of the photoreceptor 1Y through the exposure device 3 according to the yellow image data transmitted from a controller (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic charge image of a yellow image pattern on the surface of the photoreceptor 1Y.

[0272] The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging. A part of the photosensitive layer irradiated with the laser beam 3Y undergoes a decrease in resistivity. Therefore, the charge on the surface of the photoreceptor 1Y in this part flows out, while the charge in the remaining part of the photosensitive layer not irradiated with the laser beam 3Y remains. Therefore, the electrostatic charge image is a negative latent image.

[0273] When the photoreceptor 1Y is running, the electrostatic charge image formed on the photoreceptor 1Y rotates to a predetermined development position. The electrostatic charge image on the photoreceptor 1Y is visualized (developed) by the developing device 4Y at this development position, thereby forming a toner image.

[0274] For example, the electrostatic charge image developer containing at least yellow toner and carrier is included in the developing device 4Y. The yellow toner is triboelectrically charged when agitated in the developing device 4Y, and is carried on the developing roller (an example of a developer carrying member) by having the same polarity (negative) charge as the charge on the photoreceptor 1Y. When the surface of the photoreceptor 1Y passes by the developing device 4Y, the yellow toner electrostatically adheres to the latent image portion where the charge on the photoreceptor 1Y has been erased, thereby developing the latent image with the yellow toner. The photoreceptor 1Y on which the yellow toner image has been formed runs continuously at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transferred to a predetermined first transfer position.

[0275] After the yellow toner image on the photoreceptor 1Y is transferred to the first transfer position, a first transfer bias is applied to the first transfer roller 5Y. The electrostatic force acting from the photoreceptor 1Y towards the first transfer roller 5Y also acts on the toner image, and the toner image on the photoreceptor 1Y is transferred to the intermediate transfer belt 20. At this time, the polarity of the applied transfer bias is opposite to the polarity of the toner (negative), that is, the polarity of the transfer bias is positive. For example, the transfer bias of the first unit 10Y is controlled by a controller (not shown) to be about +10 μA.

[0276] The toner remaining on the photoreceptor 1Y is removed and recycled by the photoreceptor cleaning device 6Y.

[0277] The first transfer bias applied to the first transfer rollers 5M, 5C, and 5K after the second unit 10M is also controlled in the same way as the first unit.

[0278] The intermediate transfer belt 20 onto which the yellow toner image has been transferred by using the first unit 10Y travels through the second unit 10M to the fourth unit 10K, and toner images of various colors are superimposed on the yellow toner image to achieve multiple transfers.

[0279] Then, the intermediate transfer belt 20 onto which toner images of four colors are transferred by using the first unit to the fourth unit reaches the second transfer portion, which is composed of the intermediate transfer belt 20, a support roller 24 that contacts the inner surface of the intermediate transfer belt, and a second transfer roller (an example of a second transfer unit) 26 provided on the image-carrying surface side of the intermediate transfer belt 20. At the same time, a recording sheet P (an example of a recording medium) is supplied to the space where the second transfer roller 26 and the intermediate transfer belt 20 are in contact with each other at a predetermined timing by a supply mechanism, and a second transfer bias is applied to the support roller 24. The transfer bias applied at this time has the same polarity (negative) as the toner. An electrostatic force acting from the intermediate transfer belt 20 toward the recording sheet P acts on the toner image, and the toner image on the intermediate transfer belt 20 is transferred onto the recording sheet P. The second transfer bias is determined by the resistance of the second transfer portion detected by a resistance detector (not shown) and is controlled by voltage.

[0280] Subsequently, the recording sheet P is sent to the contact portion (nip) between a pair of fixing rollers in a fixing device (an example of a fixing unit) 28, and the toner image is fixed onto the recording sheet P to form a fixed image.

[0281] Examples of the recording sheet P onto which the toner image is transferred include plain paper used in electrophotographic system copiers and printers. In addition to the recording sheet P, examples of the recording medium are OHP sheets.

[0282] In order to further improve the smoothness of the image surface after fixing, the surface of the recording sheet P can be smooth. For example, coated paper of plain paper with a resin or the like coated on the surface and art paper for printing can be used.

[0283] The recording sheet P after fixing the color image is conveyed to the discharge unit, thus completing a series of color image forming operations.

[0284] Processing cartridge and toner cartridge

[0285] A processing cartridge according to an exemplary embodiment is described.

[0286] The processing cartridge of the exemplary embodiment is detachably connected to an image forming apparatus and includes a developing unit that contains the electrostatic charge image developer of the exemplary embodiment and develops an electrostatic charge image on the surface of an image carrier by using the electrostatic charge image developer to form a toner image.

[0287] The processing cartridge of the exemplary embodiment is not limited to the processing cartridge having the above structure and may have a structure equipped with a developing device, and may also have at least one of an image carrier, a charging unit, an electrostatic charge image forming unit, and a transfer unit if necessary.

[0288] An example of a process cartridge according to an exemplary embodiment will be described below, but this example is not restrictive. Only the relevant parts shown in the drawings will be described, and the description of other parts will be omitted.

[0289] Figure 2 is a schematic diagram of a process cartridge according to an exemplary embodiment.

[0290] Figure 2 The illustrated process cartridge 200 includes, for example, a photoreceptor 107 (an example of an image carrier), a charging roller 108 (an example of a charging unit), a developing device 111 (an example of a developing unit), and a photoreceptor cleaning device 113 (an example of a cleaning unit) disposed around the photoreceptor 107. A housing 117 having an assembly track 116 and an opening 118 for exposure combines and integrates the above components into the cartridge.

[0291] In Figure 2 109 represents an exposure device (an example of an electrostatic charge image forming unit), 112 represents a transfer device (an example of a transfer unit), 115 represents a fixing device (an example of a fixing unit), and 300 represents a recording sheet (an example of a recording medium).

[0292] Next, a toner cartridge according to an exemplary embodiment will be described.

[0293] The toner cartridge of the exemplary embodiment is detachably connected to the image forming apparatus and contains toner according to the exemplary embodiment. The toner cartridge is used to store refill toner to be supplied to a developing unit provided inside the image forming apparatus.

[0294] Figure 1 The illustrated image forming apparatus has detachable toner cartridges 8Y, 8M, 8C, and 8K, and developing devices 4Y, 4M, 4C, and 4K are respectively connected to the corresponding color toner cartridges through toner supply tubes (not shown in the figure). When the toner contained in the toner cartridge is insufficient, the toner cartridge is replaced.

[0295] Example

[0296] Examples of the present disclosure will now be described in more detail, but the present disclosure is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are based on mass.

[0297] Preparation of Polyester Resin Particle Dispersion

[0298] Preparation of Polyester Resin Particle Dispersion (P1-a)

[0299] · Terephthalic acid: 80 parts by mole

[0300] ·Isophthalic acid: 20 mol parts

[0301] ·Bisphenol A-ethylene oxide adduct: 20 mol parts

[0302] ·Bisphenol A-propylene oxide adduct: 80 mol parts

[0303] Load the above materials into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and raise the temperature to 210 °C within 1 hour. Then add 1 part of tetraethoxy titanium to 100 parts of the above materials. When the generated water is distilled off, raise the temperature to 230 °C within 0.5 hour, and continue the dehydration condensation reaction at this temperature for 1 hour, and then cool the reaction product. Thus, polyester resin (P1) is synthesized. The weight average molecular weight (Mw) of the obtained polyester resin (P1) is 20,000.

[0304] In a container equipped with a temperature control unit and a nitrogen replacement unit, load 40 parts of ethyl acetate and 25 parts of 2-butanol to prepare a mixed solvent, and gradually add 100 parts of polyester resin (P1) thereto for dissolution. Add a 10 mass% aqueous ammonia solution (equivalent to three times the molar ratio equivalent of the resin acid value), and then stir for 30 minutes.

[0305] Next, replace the inside of the container with dry nitrogen, and dropwise add 400 parts of ion-exchanged water to the container at a rate of 2 parts / minute while maintaining the temperature at 40 °C and stirring the mixture for emulsification. After the dropping is completed, return the emulsion to room temperature (20 °C - 25 °C), and bubble dry nitrogen through it with stirring for 48 hours to reduce ethyl acetate and 2-butanol to below 1000 ppm. Then, add ion-exchanged water to adjust the solid content to 20 mass%. As a result, a polyester resin particle dispersion (P1-a) with a volume average particle size of 180 nm is obtained.

[0306] Preparation of polyester resin particle dispersion (P1-b)

[0307] Except for adding 1.0 part of bisphenol A-propylene oxide adduct when adding 100 parts of polyester resin (P1), a polyester resin particle dispersion (P1-b) with a volume average particle size of 180 nm is obtained in the same manner as the preparation of polyester resin particle dispersion (P1-a).

[0308] Preparation of polyester resin particle dispersion (P1-c)

[0309] Except for adding 0.15 part of bisphenol A-ethylene oxide adduct when adding 100 parts of polyester resin (P1), a polyester resin particle dispersion (P1-c) with a volume average particle size of 180 nm is obtained in the same manner as the preparation of polyester resin particle dispersion (P1-a).

[0310] Preparation of Polyester Resin Particle Dispersion (P1-d)

[0311] A polyester resin particle dispersion (P1-d) with a volume average particle size of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that 2.0 parts of bisphenol A-propylene oxide adduct was added when 100 parts of polyester resin (P1) was added.

[0312] Preparation of Polyester Resin Particle Dispersion (P1-e)

[0313] A polyester resin particle dispersion (P1-e) with a volume average particle size of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that 0.3 part of bisphenol A-propylene oxide adduct was added when 100 parts of polyester resin (P1) was added.

[0314] Preparation of Polyester Resin Particle Dispersion (P1-f)

[0315] A polyester resin particle dispersion (P1-f) with a volume average particle size of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that 1.0 part of 12-hydroxystearic acid was added when 100 parts of polyester resin (P1) was added.

[0316] Preparation of Polyester Resin Particle Dispersion (P1-g)

[0317] A polyester resin particle dispersion (P1-g) with a volume average particle size of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that 1.0 part of myristyl alcohol was added when 100 parts of polyester resin (P1) was added.

[0318] Preparation of Polyester Resin Particle Dispersion (P1-h)

[0319] A polyester resin particle dispersion (P1-h) with a volume average particle size of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that 1.0 part of 1,12-dodecanediol was added when 100 parts of polyester resin (P1) was added.

[0320] Preparation of Polyester Resin Particle Dispersion (P1-i)

[0321] A polyester resin particle dispersion (P1-i) with a volume average particle size of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that 4.0 parts of bisphenol A-propylene oxide adduct was added when 100 parts of polyester resin (P1) was added.

[0322] Preparation of Polyester Resin Particle Dispersion (P1-j)

[0323] A polyester resin particle dispersion (P1-j) with a volume average particle diameter of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that 0.09 part of bisphenol A-ethylene oxide adduct was added when 100 parts of the polyester resin (P1) was added.

[0324] Preparation of Polyester Resin Particle Dispersion (P2-a)

[0325] · Terephthalic acid: 80 mol parts

[0326] · Isophthalic acid: 15 mol parts

[0327] · Trimellitic anhydride: 5 mol parts

[0328] · Bisphenol A-ethylene oxide adduct: 20 mol parts

[0329] · Bisphenol A-propylene oxide adduct: 80 mol parts

[0330] A polyester resin particle dispersion (P2-a) was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that the above components were used instead. The weight average molecular weight (Mw) of the polyester resin (P2-a) is 95,000.

[0331] Preparation of Polyester Resin Particle Dispersion (P2-b)

[0332] A polyester resin particle dispersion (P2-b) with a volume average particle diameter of 180 nm was obtained in the same manner as the preparation of the polyester resin particle dispersion (P2-a), except that 7.0 parts of bisphenol A-ethylene oxide adduct was added when 100 parts of the polyester resin (P2) was added.

[0333] Preparation of Polyester Resin Particle Dispersion (P3)

[0334] · Terephthalic acid: 80 mol parts

[0335] · Isophthalic acid: 17 mol parts

[0336] · Trimellitic anhydride: 3 mol parts

[0337] · Bisphenol A-ethylene oxide adduct: 20 mol parts

[0338] · Bisphenol A-propylene oxide adduct: 80 mol parts

[0339] A polyester resin particle dispersion (P3) was obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that the above components were used instead. The weight average molecular weight (Mw) of the polyester resin (P3) is 55,000.

[0340] Preparation of Polyester Resin Particle Dispersion (P4)

[0341] · Terephthalic acid: 78 mol parts

[0342] · Isophthalic acid: 15 mol parts

[0343] · Trimellitic anhydride: 7 mol parts

[0344] · Bisphenol A-ethylene oxide adduct: 20 mol parts

[0345] · Bisphenol A-propylene oxide adduct: 80 mol parts

[0346] The polyester resin particle dispersion (P4) is obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that the above components are used instead. The weight-average molecular weight (Mw) of the polyester resin (P4) is 124,000.

[0347] Preparation of Polyester Resin Particle Dispersion (P5)

[0348] · Terephthalic acid: 80 mol parts

[0349] · Isophthalic acid: 15 mol parts

[0350] · Trimellitic anhydride: 5 mol parts

[0351] · Propylene glycol: 80 mol parts

[0352] · Bisphenol A-propylene oxide adduct: 20 mol parts

[0353] The polyester resin particle dispersion (P6) is obtained in the same manner as the preparation of the polyester resin particle dispersion (P1-a), except that the above components are used instead. The weight-average molecular weight (Mw) of the polyester resin (P6) is 95,000.

[0354] Preparation of Colorant Particle Dispersion

[0355] Preparation of Colorant Particle Dispersion (1)

[0356] · Carbon black Regal 330 (produced by Cabot Corporation): 100 parts

[0357] · Ionic surfactant (TAYCAPOWER BN2060 produced by Tayca Corporation): 10 parts

[0358] · Ion-exchanged water: 400 parts

[0359] The above components were mixed and processed in a high-pressure impact disperser Ultramizer (manufactured by SUGINO MACHINE LIMITED) at 240 MPa for 10 minutes to obtain a colorant particle dispersion (1) (solid concentration: 20% by mass).

[0360] Preparation of release agent particle dispersion

[0361] Preparation of release agent particle dispersion (1)

[0362] · Paraffin wax (HNP9 manufactured by Nippon Seiro Co., Ltd.): 100 parts

[0363] · Anionic surfactant (TAYCAPOWER BN2060 manufactured by Nippon Kayaku Co., Ltd.): 2 parts

[0364] · Ion-exchanged water: 400 parts

[0365] The above materials were mixed, heated to 100 °C, and dispersed in a homogenizer (ULTRA-TURRAX T50 manufactured by IKA Japan). The resulting dispersion was further dispersed in a Manton-Gaulin high-pressure homogenizer (manufactured by Gaulin Company), and as a result, a release agent particle dispersion (1) containing dispersed release agent particles with a volume average particle size of 210 nm was obtained (solid content: 20% by mass).

[0366] Preparation of silica particles

[0367] Preparation of silica particles (1)

[0368] After water, methanol, and ammonia water were sufficiently mixed, tetraethoxysilane and ammonia water were added dropwise thereto under heating. Subsequently, hexamethyldisilazane (HMDS) was added to the resulting silica sol suspension for hydrophobization, and the silica sol was dried to obtain silica particles. Subsequently, the silica particles were pulverized to obtain silica particles (1) with a volume average particle size D50v of 160 nm. The water content of the silica particles (1) was 1.7% by mass.

[0369] Preparation of silica particles (2)

[0370] Except for adjusting the addition amount of hexamethyldisilazane, silica particles (2) with a volume average particle size D50v of 160 nm were obtained in the same manner as in the preparation of silica particles (1). The water content of the silica particles (2) was 5.2% by mass.

[0371] Preparation of silica particles (3)

[0372] Except for adjusting the addition amount of hexamethyldisilazane, silica particles (3) with a D50v of 160 nm were obtained in the same manner as in the preparation of silica particles (1).

[0373] The water content of the silica particles (3) was 0.7% by mass.

[0374] Preparation of silica particles (4)

[0375] Except for adjusting the dropping conditions, silica particles (4) with a D50v of 38 nm were obtained in the same manner as in the preparation of silica particles (1). The water content of the silica particles (4) was 2.6% by mass.

[0376] Preparation of silica particles (5)

[0377] Except for adjusting the dropping conditions, silica particles (5) with a D50v of 420 nm were obtained in the same manner as in the preparation of silica particles (1). The water content of the silica particles (5) was 1.4% by mass.

[0378] Example 1

[0379] Preparation of toner particles (1)

[0380] · Resin particle dispersion (P1-b): 300 parts (resin particle dispersion with loading)

[0381] · Resin particle dispersion (P2-a): 300 parts (resin particle dispersion with loading)

[0382] · Release agent particle dispersion (1): 50 parts

[0383] · Colorant particle dispersion (1): 50 parts

[0384] The above components were placed in a cylindrical stainless-steel container and dispersed and mixed in a homogenizer (ULTRA-TURRAX T50 manufactured by IKA Japan) at 4000 rpm for 10 minutes while applying a shear force. Then, a 10% aqueous nitric acid solution of 1.75 parts of polyaluminum chloride used as a flocculant was gradually added dropwise thereto, and the resulting mixture was dispersed and mixed for 15 minutes by setting the rotation speed of the homogenizer to 5000 rpm. As a result, a raw material dispersion was obtained.

[0385] Subsequently, the raw material dispersion was transferred to a polymerization container equipped with a thermometer and a stirring device using four-blade stirring blades, heated with a heating jacket while stirring at a rotation speed of 700 rpm, and the growth of aggregated particles was accelerated at 45°C. During this process, the pH of the dispersion was controlled within the range of 2.2 to 3.5 by using 0.3N nitric acid or 1N aqueous sodium hydroxide solution. The dispersion was maintained within the above pH range for about 2 hours to form aggregated particles.

[0386] Next, 150 parts of a resin particle dispersion (P1-b) and 150 parts of a resin particle dispersion (P2-a) used as an additional resin particle dispersion were added thereto so that the resin particles of the binder resin adhered to the surface of the aggregated particles. The temperature was further raised to 47 °C, and the aggregated particles were adjusted by monitoring the size and morphology of the particles using an optical microscope and a Multisizer II. Subsequently, 2.25 parts of a chelating agent (HIDS produced by NIPPON SHOKUBAI CO., LTD.) was added thereto, and then the pH was adjusted to 7.8 using a 5% aqueous sodium hydroxide solution. This state was maintained for 15 minutes. Then the pH was raised to 8.0 to fuse the aggregated particles, and then the temperature was raised to 85 °C. After confirming the fusion of the aggregated particles with an optical microscope, the temperature was lowered at a rate of 1.0 °C / min. The resulting product was sieved through a 20-μm sieve, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles (1). The volume average particle diameter of the obtained toner particles (1) was 5.6 μm.

[0387] Preparation of toner (1).

[0388] · Toner particles (1): 100 parts

[0389] · Silica particles (1): 2.3 parts

[0390] The above components were mixed in a Henschel mixer at a circumferential speed of 20 m / s for 15 minutes to obtain toner (1).

[0391] Examples 2 to 17 and Comparative Examples 1 to 5

[0392] Toner was obtained as in Example 1, except that in the preparation of toner particles (1), as shown in Table 1, the types and amounts of the loaded resin particle dispersion and the additional resin particle dispersion were changed, and the type and amount of the silica particles were changed.

[0393] Evaluation

[0394] Various measurements

[0395] The following properties of the toner obtained in each example were measured by the above method.

[0396] · Change amount of the coefficient of variation of the Si content before and after treatment ((coefficient of variation of the Si content after treatment) - (coefficient of variation of the Si content before treatment)) (abbreviated as "change amount of the coefficient of variation of the Si content" in the table)

[0397] · Coefficient of variation of the Si content after treatment (abbreviated as "coefficient of variation of the Si content" in the table)

[0398] · Content of low-molecular-weight compound

[0399] · Proportion of components with a molecular weight of 50,000 or more in the molecular weight distribution obtained by measuring the tetrahydrofuran-soluble part of toner particles by gel permeation chromatography (referred to as "proportion of components with a molecular weight of 50,000 or more" in the table)

[0400] · Ratio B1 / B2 of the measured specific surface area B1 of toner particles to the calculated specific surface area B2 of toner particles determined based on the volume average particle diameter

[0401] · Absolute value |Cp - CL| of the difference between the average number of carbon atoms Cp in the polyol constituting the polyester resin and the number of carbon atoms CL in the low-molecular-weight compound

[0402] Paper contamination

[0403] Place the toner in the Doucentre-V7080N developing device and toner cartridge produced by Fuji Xerox Co., Ltd.

[0404] Next, prepare toner cartridges stored for one week in an environment of 48°C and toner cartridges stored at room temperature (25°C).

[0405] Load the toner cartridge stored for one week in an environment of 48°C onto the Docucentre-V7080N produced by Fuji Xerox Co., Ltd. Then, use this device to output a stripe pattern with an image density of 30% on 30,000 sheets of A4 paper. Then output blank paper, observe the contaminants on the paper with the naked eye, and evaluate according to the following evaluation criteria.

[0406] Load the toner cartridge stored at room temperature (25°C) onto the Docucentre-V7080N produced by Fuji Xerox Co., Ltd. Then, in the same manner as above, observe the contamination on the paper with the naked eye and evaluate according to the following evaluation criteria.

[0407] Evaluation criteria

[0408] A: No contamination was observed on the paper with the naked eye.

[0409] B: Very slight contamination was observed with the naked eye, but this contamination does not cause any problems. C: Slight contamination was observed with the naked eye, but the contamination level is acceptable.

[0410] D: Contamination was observed with the naked eye, and the contamination level is unacceptable.

[0411] E: A large amount of contamination was observed with the naked eye.

[0412] Table 1

[0413]

[0414]

[0415]

[0416] These results indicate that, compared with the toner of the comparative example, the toner of the example has less paper contamination after storage at high temperature and after storage at room temperature.

[0417] Therefore, it has been found that, whether or not the toner is heated, the toner of the embodiment suppresses the contamination of the recording medium caused by the clogging of the transfer residual toner recovery route.

[0418] For purposes of illustration and description, the foregoing description of exemplary embodiments of the present disclosure has been provided. It is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Obviously, many modifications and variations are possible to those skilled in the art. The embodiments were chosen and described in order to best explain the principles of the present disclosure and its practical application, thereby enabling others skilled in the art to understand the present disclosure in various embodiments and various variations suitable for the particular purposes contemplated. The scope of the invention is intended to be defined by the appended claims and their equivalents.

Claims

1. A toner for developing an electrostatic charge image, the toner comprising: Toner particles containing a binder resin and a low-molecular-weight compound having a hydroxyl group; and an external additive containing silica particles, wherein, relative to the toner particles, the content of the low-molecular-weight compound is 500 ppm or more and 50,000 ppm or less, and the proportion of the component having a molecular weight of 50,000 or more in the molecular weight distribution obtained by measuring the tetrahydrofuran-soluble portion of the toner particles by gel permeation chromatography is 15% by mass or more and 50% by mass or less, wherein, after performing the treatment of dispersing the toner in water and drying the dispersed toner, the coefficient of variation of the Si content after the treatment is determined by determining the Si content in a plurality of 0.5 μm × 0.5 μm square regions on the surface of each toner particle in the toner particles, and the change amount between the coefficient of variation of the Si content after the treatment and the coefficient of variation of the Si content before the treatment, that is, the coefficient of variation of the Si content after the treatment - the coefficient of variation of the Si content before the treatment, is 0.05 or more and 0.60 or less, wherein the coefficient of variation of the Si content after the treatment is calculated by the following formula: Coefficient of variation of Si content after treatment = (standard deviation) / (average value), and wherein the average value is a value calculated based on the Si content in each of the plurality of 0.5 μm × 0.5 μm square regions on the surface of each toner particle, wherein the treatment of dispersing the toner in water and drying the dispersed toner includes the following steps: preparing an aqueous solution by adding 2 g of the toner to a 0.2 mass% aqueous solution of Triton X-100 of 100 mL, stirring the aqueous solution at a rotation speed of 250 rpm for 10 minutes using a magnetic stirrer, then treating the obtained solution in a centrifugal separator to remove the silica particles that have been separated from the toner particles, and removing the silica particles that have been separated from the toner particles, and then drying the toner at a temperature of 40 °C for 24 hours, and wherein the ratio B1 / B2 is 1.2 or more and 5.0 or less, wherein B1 represents the measured value of the specific surface area of the toner particles, and B2 represents the specific surface area of the toner particles calculated based on the volume average particle diameter, and wherein the coefficient of variation of the Si content after the treatment is 0.20 or more and 0.80 or less.

2. The toner according to claim 1, wherein, The coefficient of variation of the Si content after the treatment is 0.25 or more and 0.70 or less.

3. The toner according to claim 1, wherein, The low-molecular-weight compound is at least one compound selected from phenolic compounds, hydroxycarboxylic acids or their ester compounds, and alcohol compounds.

4. The toner according to claim 3, wherein, The low-molecular-weight compound is an alcohol compound.

5. The toner according to claim 3, wherein, The content of the low-molecular-weight compound is 1000 ppm or more and 40,000 ppm or less.

6. The toner according to claim 4, wherein, The content of the low-molecular-weight compound is 2000 ppm or more and 30,000 ppm or less.

7. The toner according to claim 1, wherein, The binder resin contains a polyester resin formed by a condensate of a polycarboxylic acid and a polyol.

8. The toner according to claim 1, wherein, The adhesive resin contains a polyester resin formed from a condensate of a polycarboxylic acid and a polyol, and the absolute value of the difference between the average number of carbon atoms Cp of the polyol constituting the polyester resin and the number of carbon atoms CL of the low molecular weight compound is |Cp - CL| ≤ 8.

9. The toner according to claim 1, wherein, The water content of the silica particles is 0.5 mass% or more and 5.0 mass% or less.

10. An electrostatic charge image developer, the electrostatic charge image developer comprising the toner for developing an electrostatic charge image according to claim 1.

11. A toner cartridge detachably attached to an image forming apparatus, the toner cartridge comprising the toner for developing an electrostatic charge image according to claim 1.

Images