Toner, toner cartridge, and image forming apparatus

Abstract

To provide a new toner having both low-temperature fixability and storage stability.SOLUTION: The toner includes particles containing a binder resin, a colorant and a wax, wherein the binder resin contains a styrene copolymer resin or a poly (meth) acrylic resin, and the wax contains an ester wax containing 60 mass% or more of a component having 22 or more carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a toner that has low-temperature fixability and storage stability and can be used, for example, for developing electrostatic images. [Background technology]

[0002] Electrostatic image developing toners are used in image forming devices such as printers, copiers, and facsimiles to visualize electrostatic images. For example, in electrophotographic image formation, an electrostatic latent image is first formed on a photosensitive drum. This electrostatic latent image is then developed with toner, transferred to transfer paper, etc., and the toner is heated to fuse the image.

[0003] Toner for developing electrostatic images generally has a structure in which solid fine particles such as silica are attached as an external additive to the surface of toner base particles containing a binder resin, a colorant, wax, etc.

[0004] Conventionally, this type of toner has been produced by a pulverization method in which raw materials such as binder resin and colorant are kneaded together to produce a mass, which is then pulverized to produce fine particles. However, in order to produce high-quality images, there is an increasing demand for uniform particle size, and as a result, toner particles are now mainly produced by a polymerization method in which a polymer is synthesized from a monomer. In this case, known polymer polymerization methods include, for example, suspension polymerization, emulsion aggregation, and solution suspension.

[0005] As mentioned above, when forming an image on paper, the heat required to heat the toner to fix it accounts for a large portion of the power consumption of devices such as copiers, and therefore toner is required to have the property of being fixed at a lower temperature (low-temperature fixability). One method for improving the low-temperature fixability of a toner is to produce the toner using a binder resin with a low melting temperature or melt viscosity. However, if the binder resin used in the toner is soft, the heat resistance and storage stability will decrease. Therefore, it is not easy to achieve both low-temperature fixability and storage stability.

[0006] For example, Patent Document 1 discloses a toner for electrostatic charge development, which contains a crystalline polyester resin and a release agent, and has a structure in which the crystalline polyester resin is in contact with the release agent, as a toner having little dependency on the fixing temperature in fixing performance and excellent thermal storage stability.

[0007] Patent Document 2 proposes a toner for developing electrostatic images that has heat-resistant storage stability and low-temperature fixability, and contains a crystalline organic compound with a melting point of 50 to 150°C as a fixing aid, in which the resin and the fixing aid become compatible when heated.

[0008] Furthermore, Patent Document 3 discloses a toner for developing electrostatic images that can achieve low-temperature fixability, heat-resistant storage stability, and fixation separation properties, in which a styrene acrylic resin and a release agent are dispersed as domain phases in a matrix phase made of polyester resin. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-33057 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-22331 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-53677 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention aims to provide a new toner that has both low-temperature fixability and storage stability. [Means for solving the problem]

[0011] The present invention provides a toner comprising particles containing a binder resin, a colorant, and a wax, In differential scanning calorimetry (DSC) in which a temperature program is performed including steps of increasing the temperature from 40°C to 100°C or higher at a temperature increase rate of 10°C / min (first temperature increase), then decreasing the temperature to 40°C or lower at a temperature decrease rate of 10°C / min (first temperature decrease), and then increasing the temperature to 100°C or higher at a temperature increase rate of 10°C / min (second temperature increase), the total amount of heat absorbed from 40°C to 100°C during the first temperature increase, HA1, and the total amount of heat absorbed from 40°C to 100°C during the second temperature increase, HA2, satisfy the following relationship (1), and the difference between the half-width of the endothermic peak during the second temperature increase and the half-width of the exothermic peak during the first temperature decrease is 7.00°C or less. (1) HA2 / HA1>0.80

[0012] The present invention also provides a toner comprising particles containing a binder resin, a colorant, and a wax, In differential scanning calorimetry (DSC) in which a temperature program is carried out including steps of increasing the temperature from 40°C to 100°C or higher at a temperature increase rate of 10°C / min (first temperature increase), then decreasing the temperature to 40°C or lower at a temperature decrease rate of 10°C / min (first temperature decrease), and then increasing the temperature to 100°C or higher at a temperature increase rate of 10°C / min (second temperature increase), the toner is proposed in which the total amount of heat absorbed from 40°C to 100°C during the first temperature increase, HA1, and the total amount of heat absorbed from 40°C to 100°C during the second temperature increase, HA2, satisfy the following relationships (1) and (3): (1) HA2 / HA1>0.80 (3) HA2≧20J / g

[0013] That is, the gist of the present invention lies in the following [1] to

[15] .

[0014] [1] A toner containing particles containing a binder resin, a colorant, and a wax, wherein, in a differential scanning calorimetry (DSC) measurement carried out using a temperature program including steps of increasing the temperature from 40°C to 100°C or higher at a temperature increase rate of 10°C / min (first temperature increase), then decreasing the temperature to 40°C or lower at a temperature decrease rate of 10°C / min (first temperature decrease), and then increasing the temperature to 100°C or higher at a temperature increase rate of 10°C / min (second temperature increase), the total amount of heat absorbed from 40°C to 100°C during the first temperature increase, HA1, and the total amount of heat absorbed from 40°C to 100°C during the second temperature increase, HA2, satisfy the following relationship (1), and the difference between the half-width of the endothermic peak during the second temperature increase and the half-width of the exothermic peak during the first temperature decrease is 7.00°C or less. (1) HA2 / HA1>0.80

[0015] [2] The toner according to [1], wherein the HA2 satisfies the following relationship (3): (3) HA2≧19J / g

[0016] [3] The toner according to [1] or [2], wherein in differential scanning calorimetry (DSC) in which the temperature program is carried out, the difference between the half-value width of the endothermic peak during the first temperature increase and the half-value width of the exothermic peak during the first temperature decrease is 7.0°C or less.

[0017] [4] A toner containing particles containing a binder resin, a colorant, and a wax, wherein in differential scanning calorimetry (DSC) in which a temperature program including steps of heating from 40°C to 100°C or higher at a heating rate of 10°C / min (first heating), then cooling to 40°C or lower at a heating rate of 10°C / min (first cooling), and then heating to 100°C or higher at a heating rate of 10°C / min (second heating), the total amount of heat absorbed from 40°C to 100°C during the first heating, HA1, and the total amount of heat absorbed from 40°C to 100°C during the second heating, HA2, satisfy the following relationships (1) and (3): (1) HA2 / HA1>0.80 (3) HA2≧20J / g

[0018] [5] The toner according to [4], wherein, in differential scanning calorimetry (DSC) in which the temperature program is carried out, the difference between the half-width of the endothermic peak during the first heating and the half-width of the exothermic peak during the first cooling is 7.0°C or less, and the difference between the half-width of the endothermic peak during the second heating and the half-width of the exothermic peak during the first cooling is 7.00°C or less.

[0019] [6] The toner according to any one of [1] to [5], wherein the difference between the half width of the endothermic peak during the second temperature increase and the half width of the exothermic peak during the first temperature decrease is 6.0° C. or less. [7] The toner according to any one of [1] to [6], wherein the HA1 satisfies the following relationship (2): (2) HA1≧20J / g

[0020] [8] The toner according to any one of [1] to [7], wherein the wax is an ester wax. [9] The toner according to any one of [1] to [8], wherein the wax is two or more types of ester waxes.

[10] The toner according to any one of [1] to [9], wherein the total content of the waxes is 10.0 to 20.0% by mass.

[11] The toner according to [8] or [9], wherein at least one of the ester waxes has a melting point of 70 to 80°C and is an ester wax (referred to as a "low-temperature fixing wax") that is incompatible with the binder resin even when melted.

[12] The toner according to

[11] , wherein the content of the low-temperature fixing wax is 30 to 80% by mass of the total content (100% by mass) of waxes.

[0021]

[13] The toner according to any one of [1] to

[12] , wherein the volume median particle size is 6.5 μm or less, and the number percentage of particles having a particle size of 1.0 μm or less is 3.0% or less.

[0022]

[14] A toner cartridge containing the toner according to any one of [1] to

[13] .

[15] An image forming apparatus containing the toner according to any one of [1] to

[13] . [Effects of the Invention]

[0023] The toner proposed by the present invention can improve low-temperature fixability while maintaining storage stability. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 2 is a diagram showing DSC curves of the toner obtained in Example 1 at the time of the first temperature rise and at the time of the second temperature rise. [Figure 2] FIG. 2 is a diagram showing DSC curves of the toner obtained in Comparative Example 1 at the time of the first temperature rise and at the time of the second temperature rise. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will now be described based on embodiments, although the present invention is not limited to the embodiments described below.

[0026] <<This toner>> A toner according to an embodiment of the present invention (hereinafter referred to as "the toner") is preferably a toner comprising toner base particles (hereinafter referred to as "the toner base particles") containing a binder resin, a colorant, and a wax, and further containing a charge control agent and other components as needed, and an external additive. However, the toner according to the present invention is not necessarily limited to the above-described constitution of the toner, and for example, it may not contain a charge control agent or an external additive.

[0027] The toner has the following characteristics: That is, in differential scanning calorimetry (DSC) in which a temperature program including steps of increasing the temperature from 40°C to 100°C or higher at a temperature increase rate of 10°C / min (first temperature increase), then decreasing the temperature to 40°C or lower at a temperature decrease rate of 10°C / min (first temperature decrease), and then increasing the temperature to 100°C or higher at a temperature increase rate of 10°C / min (second temperature increase), the toner is characterized in that the total amount of heat absorbed from 40°C to 100°C during the first temperature increase, HA1, and the total amount of heat absorbed from 40°C to 100°C during the second temperature increase, HA2, satisfy the following relationship (1): (1) HA2 / HA1>0.80

[0028] Hereinafter, a case where the compound that exhibits endothermic properties when heated between 40° C. and 100° C. and exothermic properties when cooled is wax will be described. However, as long as the technical concept described below is applicable, the present toner is not limited to a case where the compound exhibiting such thermal properties is a wax. Therefore, it is not necessary to prove that the thermal properties described below are derived from (attributed to) a wax.

[0029] When HA2 / HA1=1.0, that is, when the total amount of heat absorbed from 40°C to 100°C during the first temperature rise is equal to the total amount of heat absorbed from 40°C to 100°C during the second temperature rise, it indicates that the wax in the toner is in the same crystalline state during the first temperature rise and the second temperature rise. In other words, even if the wax becomes liquid when heated to a temperature above its melting point, it does not dissolve or mix with the binder resin of the toner, and recrystallizes when cooled, returning to the same crystalline state as before the temperature rise. On the other hand, when HA2 / HA1=0, that is, when the total amount of heat absorbed from 40°C to 100°C during the second heating is zero, it indicates that no crystalline wax components remain in the toner during the second heating. In other words, when the wax becomes liquid by heating to a temperature above its melting point, it becomes compatible with or mixes with the binder resin of the toner, and is unable to recrystallize when the temperature is lowered.

[0030] This toner satisfies the relationship HA2 / HA1>0.80. This means that a certain percentage or more of the wax is recrystallized even after the temperature increase and decrease steps. The recrystallization of a certain percentage or more of the wax increases the hardness, which is thought to result in good low-temperature fixability and storage stability.

[0031] It should be noted that the wax that has become liquid after the first temperature increase may have an increased degree of crystallinity when cooled. In such cases, the HA2 / HA1 value exceeds 1.0, but such cases are also included in the present toner. This is because even if the wax becomes liquid, it is similar in that it is not compatible with or mixes with the binder resin of the toner. From this viewpoint, it is more preferable that HA2 / HA1 is 0.85 or more or 1.0 or less.

[0032] In the present toner, it is preferable that HA2 satisfies the following relationship (3). (3) HA2≧19J / g If HA2≧19 J / g, it is evidence that the wax recrystallizes when cooled, and the toner has excellent storage stability. From this viewpoint, HA2 is more preferably 20 J / g or more, even more preferably 22 J / g or more, and particularly preferably 25 J / g or more. The upper limit is usually 50 J / g or less from the viewpoint of the balance of printing properties.

[0033] In the present toner, it is preferable that the HA1 satisfies the following relationship (2). (2) HA1≧20J / g When the HA1 value is equal to or greater than the lower limit, it can be expected that the toner has sufficient releasing ability for low-temperature fixing. From this viewpoint, HA1 is more preferably 22 J / g or more, and particularly preferably 25 J / g or more, with the upper limit usually being 50 J / g or less from the viewpoint of the balance of printing properties.

[0034] By keeping the HA1 and HA2 values ​​at or below the upper limit values, the wax content in the toner is appropriate, making it possible to suppress problems during printing such as filming and contamination of the charging roller (PCR).

[0035] In differential scanning calorimetry (DSC), if all endothermic or exothermic peaks fall between 40°C and 100°C, the entire range is considered to be the target of HA1 and HA2. On the other hand, there are cases where the peaks do not converge (partway along the slope of the peak) at the boundary of the measurement range, i.e., at least one of 40°C and 100°C. In such cases, the peaks are first identified using the baseline as a reference, including the range below 40°C and above 100°C, and only the calorific values ​​within the range from 40°C to 100°C are used as the values ​​for HA1 and HA2.

[0036] The difference between the half-width of the endothermic peak during heating and the half-width of the exothermic peak during cooling indicates the degree of sharp melting property of the wax in the toner. Here, "sharp melting" refers to the wax in the toner rapidly changing from solid to liquid when it reaches its melting point. The wax in the toner acts as a release agent by changing from solid to liquid upon heating and migrating to the toner surface. Therefore, to achieve low-temperature fixability, the wax in the toner must have high sharp melting property, i.e., it must be completely liquefied within the extremely short time (approximately 1 second) of passing through the fixing unit of the image forming apparatus. Furthermore, for wax with high sharp melting property, i.e., wax that instantly changes from solid to liquid, the endothermic peak during heating and the exothermic peak during cooling are sharp, and the difference between the half-width of the endothermic peak during heating and the half-width of the exothermic peak during cooling is small. It is preferable that the present toner has a "difference between the half-width of the endothermic peak during the second heating and the half-width of the exothermic peak during the first heating" of 7.00°C or less. In addition, it is more preferable that the "difference between the half-width of the endothermic peak during the first heating and the half-width of the exothermic peak during the first heating" is also 7.0°C or less. In other words, it is more preferable that the "difference between the half-width of the endothermic peak during the first heating and the half-width of the exothermic peak during the first heating" and the "difference between the half-width of the endothermic peak during the second heating and the half-width of the exothermic peak during the first heating" are both 7.00°C or less. In other words, it is more preferable that the present toner has the same level of sharp melting property of the wax in the toner during the first heating and the second heating.

[0037] If the difference between the half-width of the endothermic peak during the first temperature increase and the half-width of the exothermic peak during the first temperature decrease is 7.0°C or less, the sharp melting property of the wax is sufficiently high and the low-temperature fixing property of the toner is excellent. Therefore, in the present toner, the difference in half width is preferably 7.0°C or less, more preferably 6.0°C or less, even more preferably 5.0°C or less, still more preferably 3.0°C or less, and particularly preferably 1.5°C or less.

[0038] If the difference between the half-width of the endothermic peak during the second temperature increase and the half-width of the exothermic peak during the first temperature decrease is 7.00° C. or less, the crystallinity of the wax is sufficiently high and the storage stability of the toner is excellent. Therefore, in the present toner, the difference in half width is preferably 7.00°C or less, more preferably 6.0°C or less, even more preferably 5.0°C or less, still more preferably 3.0°C or less, and particularly preferably 1.5°C or less.

[0039] In differential scanning calorimetry (DSC), when the peak does not converge at at least either 40°C or 100°C (in the middle of the slope of the peak), it is handled as follows: That is, the endothermic peak or exothermic peak is identified based on the baseline, including the range below 40°C and above 100°C, and the half-width value of the peak itself is used. That is, the temperatures subject to the half-width value may include the range below 40°C and above 100°C.

[0040] There are no specific limitations on the means by which the toner satisfies the above-mentioned physical properties. Among these, as will be described later, the properties can be more suitably achieved by optimizing the selection of compounds used as waxes and their content ratios, or, when multiple waxes are used in combination, by combining them and adjusting their blending ratios. Furthermore, when the wax is a mixture or contains impurities or by-products, the properties can also be achieved by adjusting the purity, etc. This can also be suitably achieved by selecting and combining the binder resin and wax described later. For example, even when the toner contains the same amount of the same ester wax, the toner tends to be able to more easily satisfy the above-mentioned physical properties when a polystyrene copolymer resin or a poly(meth)acrylic resin is used as the binder resin than when a polyester resin is used.

[0041] In the present invention, when differential scanning calorimetry (DSC) of the toner is performed, the first temperature increase, first temperature decrease, and second temperature increase must all be performed at a rate of 10°C / min as described above. More specifically, a rate of 10.0°C / min is desirable, but a rate within 10.0±0.5°C / min is acceptable. The endothermic and exothermic amounts, and the half-widths of the endothermic and exothermic peaks all depend greatly on the rate of temperature increase or decrease. For example, measurements at a rate of 5°C / min or 15°C / min will yield values ​​that are significantly different from those measured at a rate of 10°C / min.

[0042] A conventional technique for improving the low-temperature fixability of a toner involves blending a crystalline polyester. The mechanism of action of this technique is as follows. When the temperature rises above the melting temperature of the crystalline polyester, the crystalline polyester melts and becomes compatible with the binder resin, thereby lowering the glass transition temperature (also referred to as "Tg") of the binder resin, which allows the toner to melt at a lower temperature and improves the low-temperature fixability of the toner. However, if the crystalline polyester is compatible with the binder resin and has the property of lowering the Tg of the binder resin, the toner will also be affected by heat when exposed to high temperatures in a storage environment such as inside a cartridge. This can cause a problem of reduced heat resistance during storage of the toner. Furthermore, since the crystalline polyester compatible with the binder resin does not exhibit release properties, it is necessary to add a wax separately from the crystalline polyester.

[0043] In contrast, it is presumed that the toner of the present invention exhibits low-temperature fixability through, for example, the following mechanism. This toner contains a compound (also referred to as a "compound exhibiting specific thermal properties") that exhibits endothermic properties when heated between 40°C and 100°C and exothermic properties when cooled. When the toner is heated to a sufficient temperature, the compound exhibiting specific thermal properties quickly melts, and most of it is incompatible with or immiscible in the binder resin and bleeds out to the toner surface. As a result, the compound exhibiting specific thermal properties exhibits release properties on the toner surface, improving the toner's low-temperature fixability. Furthermore, because the compound exhibiting specific thermal properties is incompatible with or immiscible in the binder resin, the Tg of the binder resin does not decrease, and the heat resistance of the toner does not deteriorate during storage or after fixing. As a result of the investigations conducted by the present inventors, it has been found that such properties of the present toner appear as the following characteristics in differential scanning calorimetry (DSC). During the first heating, an endothermic peak appears due to melting of the compound that exhibits specific thermal properties, but since the compound is not compatible with or mixes with the binder resin even after melting, not only does an exothermic peak appear due to recrystallization during the first cooling, but also an endothermic peak appears again due to melting during the second heating. In the above-mentioned conventionally known techniques, it is believed that the crystalline polyester is compatible with the binder resin, so that recrystallization is reduced and the endothermic peak due to re-melting during the second temperature increase is also reduced. Therefore, as will be described later, in the present toner, even when the temperature of the compound exhibiting specific thermal properties rises above the melting point and the compound enters a molten state, the compound remains incompatible with the binder resin and enhances the low-temperature fixability in this state, which is a mechanism that is completely different from that of conventional toners. Furthermore, since the Tg of the binder resin in the toner does not decrease, storage stability can also be improved.

[0044] <Toner base particles> The toner base particles may have a single-layer structure or a multi-layer structure including a core layer and an outer layer (also referred to as a "shell layer"). When the toner base particles have a single layer structure, they preferably contain a binder resin, a colorant and a wax, and further contain a charge control agent and other components as required. When the toner base particles have a multilayer structure including a core layer and a shell layer, the core layer preferably contains a binder resin, a colorant, and a wax, and further preferably contains a charge control agent and other components as needed. It is more preferable to use two or more types of wax in the core layer. On the other hand, the shell layer preferably contains highly heat-resistant resin particles, a charge control agent, and wax. When the shell layer contains wax, it is more effective in preventing offset at high temperatures.

[0045] <Binder resin> The binder resin is not particularly limited as long as it is a resin generally used as a binder resin when producing toner, and examples thereof include thermoplastic resins such as polystyrene resins, poly(meth)acrylic resins, polyolefin resins, epoxy resins, and polyester resins, and mixtures of these resins.

[0046] These binder resins are prepared, for example, by polymerizing monomer components during the process of producing toner by a polymerization method. As the monomer component used to prepare the binder resin, any monomer generally used in producing a binder resin for a toner can be used as appropriate. For example, any polymerizable monomer can be used, including a polymerizable monomer having an acidic group (hereinafter sometimes simply referred to as an acidic monomer), a polymerizable monomer having a basic group (hereinafter sometimes simply referred to as a basic monomer), and a polymerizable monomer having neither an acidic group nor a basic group (hereinafter sometimes referred to as an other monomer).

[0047] (Polystyrene copolymer resin or poly(meth)acrylic resin) When the binder resin is a polystyrene copolymer resin or a poly(meth)acrylic resin, the following monomers can be exemplified: Here, "(meth)acrylic" means "acrylic or methacrylic". The "styrene-based or (meth)acrylic monomer" may be hereinafter simply abbreviated as "monomer composition."

[0048] Examples of the acidic monomer include polymerizable monomers having a carboxyl group, such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, and cinnamic acid; polymerizable monomers having a sulfonic acid group, such as sulfonated styrene; and polymerizable monomers having a sulfonamide group, such as vinylbenzenesulfonamide.

[0049] Examples of basic monomers include aromatic vinyl compounds having an amino group, such as aminostyrene; nitrogen-containing heterocycle-containing polymerizable monomers, such as vinylpyridine and vinylpyrrolidone; and (meth)acrylic acid esters having an amino group, such as dimethylaminoethyl acrylate and diethylaminoethyl methacrylate.

[0050] These acidic and basic monomers contribute to the dispersion stabilization of the toner base particles. They may be used alone or in combination, and may exist as a salt together with a counter ion.

[0051] Examples of other monomers include styrenes such as styrene, methylstyrene, chlorostyrene, dichlorostyrene, pt-butylstyrene, pn-butylstyrene, and pn-nonylstyrene; acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, and 2-ethylhexyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, and 2-ethylhexyl methacrylate; and acrylamides such as acrylamide, N-propylacrylamide, N,N-dimethylacrylamide, N,N-dipropylacrylamide, and N,N-dibutylacrylamide. These "other monomers" may be used alone or in combination.

[0052] When the binder resin is a crosslinkable resin, a polyfunctional monomer is used together with the above-mentioned polymerizable monomer, such as divinylbenzene, hexanediol diacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, hexaethylene glycol dimethacrylate, nonaethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl glycol diacrylate, and diallyl phthalate.

[0053] Among the polyfunctional monomers, bifunctional polymerizable monomers are preferred, with divinylbenzene, hexanediol diacrylate, and the like being particularly preferred. These polyfunctional monomers may be used alone or in combination. Polymerizable monomers having a reactive group in the pendant group, such as glycidyl methacrylate, methylol acrylamide, and acrolein, may also be used.

[0054] If necessary, a known chain transfer agent can be used. Specific examples of the chain transfer agent include t-dodecyl mercaptan, dodecanethiol, diisopropyl xanthogen, carbon tetrachloride, trichlorobromomethane, etc. The chain transfer agent may be used alone or in combination of two or more kinds, and is preferably used in an amount of 0 to 5% by mass based on the polymerizable monomer.

[0055] When a polystyrene copolymer resin or a poly(meth)acrylic resin is used as the binder resin, the number average molecular weight measured by gel permeation chromatography (hereinafter referred to as GPC) is preferably 5,000 or more, more preferably 8,000 or more, and even more preferably 10,000 or more, and is preferably 30,000 or less, more preferably 20,000 or less, and even more preferably 15,000 or less. The mass average molecular weight is preferably 70,000 or more, more preferably 90,000 or more, and preferably 300,000 or less, and more preferably 250,000 or less.

[0056] (Polyester resin) When the binder resin is a polyester resin, examples of the monomer include the following dihydric alcohols and the following dihydric acids.

[0057] Examples of dihydric alcohols include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, 1,5-pentanediol, and 1,6-hexanediol; bisphenol A alkylene oxide adducts such as bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, and polyoxypropylenated bisphenol A; and the like.

[0058] Examples of divalent acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, anhydrides or lower alkyl esters of these acids; alkenylsuccinic acids or alkylsuccinic acids such as n-dodecenylsuccinic acid and n-dodecylsuccinic acid; and other divalent organic acids.

[0059] When the binder resin is a crosslinkable resin, a polyfunctional monomer is used together with the above-mentioned polymerizable monomer. In this case, examples of the polyfunctional monomer include trihydric or higher polyhydric alcohols such as sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, and the like. On the other hand, examples of trivalent or higher acids include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, anhydrides thereof, and the like.

[0060] These polyester resins can be synthesized by conventional methods. Specifically, conditions such as reaction temperature (170 to 250°C) and reaction pressure (5 mmHg to atmospheric pressure) are determined according to the reactivity of the monomers, and the reaction is terminated when the desired physical properties are obtained. When a polyester resin is used as a binder resin, the number average molecular weight (polystyrene equivalent) measured by GPC is preferably 2,000 to 20,000, more preferably 3,000 to 12,000.

[0061] <Coloring agent> Any known colorant can be used as the colorant. Specific examples of the colorant include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow, rhodamine dyes and pigments, chrome yellow, quinacridone dyes, benzidine yellow, rose bengal, triallylmethane dyes, monoazo dyes, disazo dyes, and condensed azo dyes and pigments, and any known dyes and pigments can be used alone or in combination. In the case of full-color toners, it is preferable to use monoazo-, disazo-, polyazo-, or condensed azo-based dyes and pigments for yellow, quinacridone- and / or monoazo-based dyes and pigments for magenta, phthalocyanine-based dyes and pigments for cyan, and carbon black for black. As for the combination of toner sets, from the viewpoint of adjusting TP2 / TP1, it is preferable that the magenta toner contains a quinacridone-based dyes and pigments and / or monoazo-based dyes and pigments, the black toner contains carbon black, the cyan toner contains a copper phthalocyanine-based dyes and pigments, and the yellow toner contains at least one dyes and pigments selected from monoazo-, disazo-, and condensed azo-based dyes and pigments. Specific examples of cyan include CI Pigment Blue 15:3 and CI Pigment Blue 15:4; examples of yellow include CI Pigment Yellow 74, CI Pigment Yellow 83, which is a disazo dye / pigment, and CI Pigment Yellow 93, CI Pigment Yellow 155, CI Pigment Yellow 180, and CI Pigment Yellow 185, which are condensed azo dye / pigment; and examples of magenta include CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 5, CI Pigment Red 122 and CI Pigment Red 209, which are quinacridone dye / pigment, and CI Pigment Red 269(238), which is a monoazo dye / pigment.

[0062] The colorant is preferably used in an amount of 3 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the present toner.

[0063] <Wax> The melting point peak of the wax contained in the toner (top of the endothermic peak in the second DSC temperature rise of the toner) is preferably 90°C or less, more preferably 85°C or less, even more preferably 80°C or less, and preferably 50°C or more, more preferably 60°C or more, and even more preferably 65°C or more. If the wax melting point peak temperature is too low, blocking resistance tends to deteriorate, while if the wax melting point peak is too high, low-temperature fixability and high gloss tend to be impaired. In addition, the difference between the wax melting point peak and the wax onset temperature (the intersection temperature of the baseline before the endothermic peak and the tangent to the first inflection point that appears before the endothermic peak in the second DSC of the toner) is preferably 15°C or less, more preferably 10°C or less.

[0064] The onset temperature of the wax is preferably 86° C. or lower, more preferably 81° C. or lower, even more preferably 76° C. or lower, and preferably 46° C. or higher, more preferably 56° C. or higher, and even more preferably 61° C. or higher. When the onset temperature is low, low-temperature fixability and high gloss tend to improve, and when the onset temperature is high, blocking resistance tends to improve.

[0065] The type of wax contained in the present toner is not limited, but it is preferable that the toner contains an ester wax, and it is particularly preferable that the toner contains at least two types of ester wax. By containing two or more types of ester waxes, the effect of low-temperature fixation can sometimes be increased.

[0066] Examples of ester waxes include ester waxes having a long-chain aliphatic group, such as behenyl behenate, montanic acid ester, stearyl stearate, and erythritol tetrabehenate. Among these, monoester waxes containing primarily C18 and / or C22 hydrocarbons are more preferred, and among these, behenyl behenate, stearyl behenate, behenyl stearate, and those containing primarily these are particularly preferred from the viewpoints of low dust and low-temperature fixation. From the viewpoint of low dust, the number of carbon atoms in one molecule of the ester wax is preferably 36 or more, and more preferably 40 or more. On the other hand, from the viewpoint of low temperature fixation, the number of carbon atoms in one molecule of the ester wax is preferably 95 or less, more preferably 60 or less, even more preferably 48 or less, and particularly preferably 44 or less.

[0067] (low temperature fixing wax) In the present toner, at least one of the ester waxes preferably has a melting point of 70 to 80° C. and is an ester wax that is incompatible with the binder resin even when melted (referred to as "low-temperature fixing wax"). Here, the melting point means the temperature of the endothermic peak (peak top) during the second temperature rise in differential scanning calorimetry (DSC) of the toner.

[0068] It is preferable to select and use a compound for the low-temperature fixing wax that has a relatively low melting point and is incompatible with the binder resin even in a molten state. If such a compound is blended with toner particles, even when the temperature rises above the melting point and the toner particles are in a molten state, the compound is incompatible with the binder resin and dissolves outside the toner particles, thereby improving the low-temperature fixability of the toner.

[0069] The melting point of the low-temperature fixing wax is preferably 70 to 80°C, more preferably 78°C or lower, and even more preferably 75°C or lower.

[0070] Among the above ester waxes, examples of the low-temperature fixing wax include behenyl behenate and erythritol tetrabehenate. However, not all of these ester waxes function as low-temperature fixation waxes. For example, behenyl behenate, which has been commonly used in the past, contains short-chain components, which are compatible with the binder resin and make it impossible to improve low-temperature fixability. Therefore, in the case of behenyl behenate, it is preferable to use one that contains 60% by mass or more of components with 22 or more carbon atoms.

[0071] (Other waxes) The toner may contain other waxes in addition to the ester wax, or other waxes may be used in combination with the ester wax. Examples include olefin waxes such as low-molecular-weight polyethylene, low-molecular-weight polypropylene, and copolymerized polyethylene; paraffin wax; vegetable waxes such as hydrogenated castor oil and carnauba wax; ketones having a long-chain alkyl group such as distearyl ketone; silicones having an alkyl group; higher fatty acids such as stearic acid; higher fatty acid amides such as oleic acid amide and stearic acid amide; etc. Preferred examples include hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax; and silicone waxes.

[0072] (amount of wax) The amount of wax (total of two or more types) is preferably 10.0% by mass or more relative to 100% by mass of the toner, and is preferably 30% by mass or less, and more preferably 20% by mass or less.

[0073] Of the total wax content (100% by mass), the content of the low-temperature fixing wax is preferably 30% by mass or more, more preferably 40% by mass or more, and is preferably 80% by mass or less.

[0074] <Charge control agent> Any known charge control agent can be used. Specific examples of charge control agents include nigrosine dyes, amino group-containing vinyl copolymers, quaternary ammonium salt compounds, polyamine resins, etc. for positively chargeable agents, and metal-containing azo dyes containing metals such as chromium, zinc, iron, cobalt, and aluminum, as well as salts and metal complexes of salicylic acid or alkylsalicylic acid with the above-mentioned metals, etc. for negatively chargeable agents.

[0075] The amount of the charge control agent is preferably 0.1 to 25 parts by mass, more preferably 1 to 15 parts by mass, per 100 parts by mass of the present toner. The charge control agent may be mixed inside the toner base particles, or may be attached to the surface of the toner base particles.

[0076] <Highly heat-resistant resin particles> The high heat-resistant resin particles are particles that are not compatible with the binder resin and exist as particles within the toner base particles or on the surface (shell layer) of the base particles. The resin that constitutes the high heat-resistant resin particles may be selected from resins that are generally used as binder resins in toner production. Examples include thermoplastic resins such as polystyrene resins, poly(meth)acrylic resins, polyolefin resins, epoxy resins, and polyester resins, as well as mixtures of these resins.

[0077] <External additives> The toner generally contains an external additive to improve the fluidity and charge controllability of the toner.

[0078] The external additive may be selected from various inorganic or organic fine particles and used in combination. Two or more types of external additives may also be used in combination.

[0079] Examples of inorganic fine particles that can be used include various carbides such as silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, and calcium carbide; various nitrides such as boron nitride, titanium nitride, and zirconium nitride; various borides such as zirconium boride; various oxides such as titanium oxide, calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, cerium oxide, silica, and colloidal silica; various titanate compounds such as calcium titanate, magnesium titanate, and strontium titanate; phosphate compounds such as calcium phosphate; sulfides such as molybdenum disulfide; fluorides such as magnesium fluoride and carbon fluoride; various metal soaps such as aluminum stearate, calcium stearate, zinc stearate, and magnesium stearate; talc, bentonite, various carbon blacks, conductive carbon blacks, magnetite, and ferrite.

[0080] Examples of organic fine particles that can be used include fine particles of styrene-based resins, acrylic-based resins, epoxy-based resins, and melamine-based resins. Fluorine-containing fine particles can also be used to improve charging stability. Among these external additives, silica, titanium oxide, alumina, zinc oxide, various carbon blacks, and conductive carbon black are particularly preferred. Furthermore, the external additives used may include inorganic or organic fine particles whose surfaces have been subjected to a surface treatment, such as hydrophobic treatment, using a treatment agent, such as a silane coupling agent (e.g., hexamethyldisilazane (HMDS) or dimethyldichlorosilane (DMDS)), a titanate-based coupling agent, a silicone oil treatment agent (e.g., silicone oil, dimethylsilicone oil, modified silicone oil, or amino-modified silicone oil), a silicone varnish, a fluorine-based silane coupling agent, a fluorine-based silicone oil, or a coupling agent having an amino group or a quaternary ammonium base. Two or more of these treatment agents can also be used in combination.

[0081] The amount of the external additive added is preferably 1.0 part by mass or more, particularly preferably 1.5 parts by mass or more, and is preferably 6.5 parts by mass or less, particularly preferably 5.5 parts by mass or less, relative to 100 parts by mass of the toner base particles.

[0082] In the present toner, from the viewpoint of charge control, conductive fine particles may be used as an external additive. Examples of conductive fine particles include metal oxides such as conductive titanium oxide, silica, and magnetite, or those doped with a conductive substance, organic fine particles obtained by doping a polymer having conjugated double bonds such as polyacetylene, polyphenylacetylene, and poly-p-phenylene with a conductive substance such as a metal, and carbon such as carbon black and graphite. However, from the viewpoint of imparting conductivity without impairing the fluidity of the toner, conductive titanium oxide or those doped with a conductive substance are more preferred.

[0083] The content of the conductive fine particles is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and particularly preferably 0.2 parts by mass or more, relative to 100 parts by mass of the toner base particles, and the upper limit of the content of the conductive fine particles is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and particularly preferably 1 part by mass or less.

[0084] <Form of this toner> From the viewpoint of image reproducibility and toner consumption, the volume median particle size of the present toner is preferably 6.5 μm or less, more preferably 6.3 μm or less, and even more preferably 6.0 μm or less. On the other hand, from the viewpoint of environmental safety against dust, the particle size is preferably 3.0 μm or more, more preferably 4.0 μm or more, and even more preferably 4.5 μm or more. In the present invention, the volume median particle size (Dv 50 )" is defined as being measured by the method described in the Examples according to its size and as being measured in that manner.

[0085] Furthermore, in order to suppress fogging, white background smearing, etc. and to stably obtain high-quality images, the percentage by number of particles having a particle size of 1.0 μm or less is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less.

[0086] The shape of the toner is preferably such that the average circularity measured using a flow particle image analyzer FPIA-3000 (manufactured by Malvern Instruments) is 0.92 or more and 0.99 or less, more preferably 0.95 or more, and even more preferably 0.96 or more.

[0087] <<Manufacturing Method of the Toner>> The present toner can be produced by producing the present toner base particles by a known method and externally adding an external additive to the present toner base particles.

[0088] <Method of manufacturing the toner base particles> From the viewpoint of stable productivity, the toner base particles are preferably produced by a method including an aggregation step, that is, an aggregation method. The following describes a method for producing the toner base particles by the aggregation method. However, the method is not limited to this. Other production methods, such as emulsion polymerization, aggregation, suspension polymerization, bulk polymerization, solution polymerization, dissolution suspension, and melt-kneading / pulverization, may also be used as long as they can provide the characteristics of the toner.

[0089] In the aggregation method, it is preferable to prepare each raw material as particles smaller than the size of the toner base particles, and then mix and aggregate these to produce the toner base particles.

[0090] It is preferable that the binder resin is prepared as "primary polymer particles" smaller than the size of the toner base particles, and a dispersion of the primary polymer particles is prepared. For example, polymer primary particles containing a styrene-based or (meth)acrylic monomer (monomer composition) as a constituent element can be obtained by emulsion polymerization of the above-mentioned monomer composition and, if necessary, a chain transfer agent using an emulsifier. In this case, known emulsifiers can be used, but one or more emulsifiers selected from cationic surfactants, anionic surfactants, and nonionic surfactants can also be used in combination.

[0091] The median diameter (D50) of the polymer primary particles is preferably 100 nm or more, more preferably 150 nm or more, and even more preferably 180 nm or more, and is preferably 350 nm or less, more preferably 300 nm or less, and even more preferably 280 nm or less. The mass average molecular weight (Mw) of the polymer primary particles is preferably 30,000 or more, more preferably 40,000 or more, and even more preferably 50,000 or more, and is preferably 500,000 or less, more preferably 300,000 or less, and even more preferably 150,000 or less.

[0092] In the aggregation step, the aforementioned components, such as the polymer primary particles, colorant particles, and optionally the charge control agent and wax, are mixed simultaneously or sequentially. From the viewpoint of uniformity of composition and particle size, it is preferable to prepare dispersions of each component, i.e., the polymer primary particle dispersion, the colorant particle dispersion, optionally the charge control agent dispersion, and the wax microparticle dispersion, in advance, and then mix them to obtain a mixed dispersion. The colorant is preferably used in a state of being dispersed in water in the presence of an emulsifier.

[0093] In the aggregation step, aggregation is usually carried out in a tank equipped with a stirrer, and there are a method of heating, a method of adding an electrolyte, and a method of combining these. When polymer primary particles are aggregated under stirring to obtain particle aggregates of a desired size, the particle size of the particle aggregates is controlled by the balance between the cohesive force between the particles and the shear force caused by stirring, and the cohesive force can be increased by heating or adding an electrolyte.

[0094] When an electrolyte is added to perform aggregation, the electrolyte may be any of an acid, an alkali, or a salt, and may be either organic or inorganic. Specific examples of acids include hydrochloric acid, nitric acid, sulfuric acid, and citric acid; alkalis include sodium hydroxide, potassium hydroxide, and aqueous ammonia; and salts include NaCl, KCl, LiCl, NaSO, KSO, LiSO, MgCl, CaCl, MgSO, CaSO, ZnSO, Al(SO), Fe(SO), CHCOONa, and CHSONa. Among these, inorganic salts having a divalent or higher polyvalent metal cation are preferred.

[0095] The amount of electrolyte added varies depending on the type of electrolyte, the target particle size, etc. It is preferably 0.02 parts by mass or more, more preferably 0.05 parts by mass or more, per 100 parts by mass of the solid components of the mixed dispersion. It is also preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. If the amount added is too small, the aggregation process may be slowed down, resulting in problems such as fine powder of 1 μm or less remaining after aggregation, or the average particle size of the resulting particle aggregates not reaching the target particle size. On the other hand, if the amount added is too large, rapid aggregation may occur, making it difficult to control the particle size, and problems such as the inclusion of coarse powder or irregularly shaped particles in the resulting aggregated particles may occur. When aggregation is carried out by adding an electrolyte, the aggregation temperature is preferably 20°C or higher, particularly preferably 30°C or higher, and preferably 70°C or lower, particularly preferably 60°C or lower.

[0096] The time required for aggregation is preferably optimized depending on the shape of the apparatus and the processing scale. In order for the particle size of the toner base particles to reach the target particle size, it is preferable to maintain the above-mentioned predetermined temperature for at least 30 minutes. The temperature may be increased at a constant rate or in stages until the predetermined temperature is reached.

[0097] After the aggregation step, preferably before or during the aging step, it is preferable to add a surfactant, adjust the pH, or use both. The surfactant used here can be one or more selected from emulsifiers that can be used when producing the polymer primary particles, and it is particularly preferable to use the same emulsifier as that used when producing the polymer primary particles.

[0098] By adding a surfactant or adjusting the pH after the aggregation step and before the completion of the aging step, it is possible to suppress the aggregation of the particle aggregates obtained in the aggregation step, and in some cases it is possible to suppress the generation of coarse particles after the aging step.

[0099] By controlling the time of the aging process, it is possible to produce toner base particles of various shapes depending on the purpose, such as grape-shaped particles in which the aggregated shape of the polymer primary particles is maintained, potato-shaped particles in which fusion has progressed, and spherical particles in which fusion has progressed even further.

[0100] <Method of adding external additives> Examples of methods for adding external additives include a method using a high-speed mixer such as a Henschel mixer, and a method using a device capable of applying compressive shear stress. The toner can be produced by a one-stage external addition method in which all external additives are added to the toner base particles at the same time, or by a separate-stage external addition method in which the external additives are added separately. To prevent the temperature from rising during the external addition, a cooling device may be installed in the vessel, or external addition may be carried out in stages.

[0101] <<Others>> The present toner may be used in either the form of a two-component developer in which a toner is used together with a carrier, or a magnetic or non-magnetic one-component developer in which no carrier is used. When used as a two-component developer, the carrier may be a magnetic substance such as iron powder, magnetite powder, ferrite powder, or the like, or a known substance such as a magnetic carrier or a resin-coated magnetic substance. The coating resin of the resin-coated carrier may be a commonly known styrene resin, acrylic resin, styrene-acrylic copolymer resin, silicone resin, modified silicone resin, fluororesin, or a mixture thereof.

[0102] <<Cartridges, image forming devices>> Next, an embodiment of an image forming apparatus using the toner (image forming apparatus of the present invention) will be described. However, the embodiment is not limited to the following description, and can be modified as desired without departing from the gist of the present invention.

[0103] The image forming apparatus is configured to include an electrophotographic photosensitive member, a charging device, an exposure device, a developing device, and a toner, and may further include a transfer device, a cleaning device, and a fixing device as required.

[0104] The electrophotographic photosensitive member is not particularly limited, but for example, a drum-shaped photosensitive member having the above-described photosensitive layer formed on the surface of a cylindrical conductive support can be used. The charging device is a device for uniformly charging the surface of the electrophotographic photosensitive member to a predetermined potential. Typical charging devices include non-contact corona charging devices such as corotrons and scorotrons, and contact charging devices.

[0105] The type of the exposure device is not particularly limited as long as it can expose an electrophotographic photosensitive member to light to form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member. The transfer device applies a predetermined voltage (transfer voltage) with a polarity opposite to the charged potential of the toner, and transfers the toner image formed on the electrophotographic photosensitive member onto recording paper (paper, medium). There are no particular limitations on the type of transfer device, and any device using any method, such as corona transfer or roller transfer, can be used. The cleaning device scrapes off residual toner adhering to the electrophotographic photosensitive member with a cleaning member and collects the residual toner. However, if there is little or almost no toner remaining on the surface of the electrophotographic photosensitive member, a cleaning device may not be necessary. There are no particular restrictions on the cleaning device, and any cleaning device such as a brush cleaner, a magnetic roller cleaner, or a blade cleaner can be used.

[0106] In the image forming apparatus configured as above, an image is recorded as follows.

[0107] First, the surface (photosensitive surface) of the electrophotographic photoreceptor is charged to a predetermined potential by a charging device. At this time, charging may be performed by a DC voltage or by superimposing an AC voltage on the DC voltage. Next, the charged photosensitive surface of the electrophotographic photoreceptor is exposed by an exposure device in accordance with the image to be recorded, forming an electrostatic latent image on the photosensitive surface, and then the electrostatic latent image formed on the photosensitive surface of the electrophotographic photoreceptor is developed by a development device. The developing device forms a thin layer of toner using a regulating member such as a developing blade, frictionally charges the toner to a predetermined polarity, and transports the toner while carrying it on a developing roller, bringing it into contact with the surface of an electrophotographic photosensitive member.

[0108] When the charged toner carried on the developing roller comes into contact with the surface of the electrophotographic photosensitive member, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the electrophotographic photosensitive member. This toner image is then transferred onto recording paper or the like by a transfer device. After this, toner that has not been transferred and remains on the photosensitive surface of the electrophotographic photosensitive member is removed by a cleaning device. After the toner image is transferred onto recording paper or the like, the toner image is thermally fixed onto the recording paper or the like by passing it through a fixing device, thereby obtaining a final image. In addition to the above-described configuration, the image forming apparatus may be configured to be capable of performing, for example, a charge removal process. The charge removal process is a process of removing charge from an electrophotographic photosensitive member by exposing the electrophotographic photosensitive member to light.

[0109] Furthermore, the image forming apparatus may be further modified and configured, for example, to be capable of performing processes such as a pre-exposure process and an auxiliary charging process, or to be configured to perform offset printing, or even to be configured as a full-color tandem system using multiple types of toner.

[0110] In addition, a member for storing toner may be combined with one or more of a charging device, an exposure device, a developing device, a transfer device, a cleaning device, and a fixing device to form an integrated cartridge (hereinafter referred to as a "toner cartridge" as appropriate), and this toner cartridge may be configured to be detachable from the main body of an image forming device such as a copier or laser beam printer.

[0111] <<Explanation of terms>> In this specification, when the expression "X to Y" (X and Y are any numbers) is used, unless otherwise specified, it means "X or more and Y or less," as well as "preferably larger than X" or "preferably smaller than Y." Furthermore, when it is expressed as "X or more" (X is any number) or "Y or less" (Y is any number), it also includes the intention that "it is preferable that it is greater than X" or "it is preferable that it is less than Y." [Example]

[0112] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. In the following examples and comparative examples, "parts" simply means "parts by mass."

[0113] <Median diameter measurement (D50)> The median diameter (D50) of particles having a median diameter (D50) of less than 1 micron was measured using a Microtrac Nanotrac 150 (hereinafter referred to as Nanotrac) manufactured by Nikkiso Co., Ltd. and the company's analysis software, Microtrac Particle Analyzer Ver. 10.1.2-0.19EE. The measurement was performed using ion-exchanged water with an electrical conductivity of 0.5 μS / cm as the solvent, with a solvent refractive index of 1.333, a measurement time of 120 seconds, and five measurements, according to the method described in the instruction manual, and the average value was calculated. Other setting conditions were particle refractive index of 1.59, transparency, shape: spherical, and density: 1.04.

[0114] <Volume Median Particle Size Measurement (Dv50)> The volume median particle size (Dv50) of particles with a volume median particle size (Dv50) of 1 micron or more was measured using a Beckman Coulter Multisizer III (aperture diameter 100 μm: hereafter abbreviated as Multisizer). The particles were dispersed in Beckman Coulter's Isoton II as the dispersing medium to a dispersoid concentration of 0.03 mass%. The measurement results are shown in Table 1 below as "volume median particle size."

[0115] <Measurement of average circularity and percentage of particles with a particle size of 1.0 μm or less> The average circularity and the percentage of particles with a particle size of 1.0 μm or less were measured by dispersing the dispersoid in a dispersion medium (Celsius, manufactured by Malvern Instruments) to a concentration of 5720 to 7140 particles / μL and using a flow particle analyzer (FPIA3000, manufactured by Malvern Instruments) in HPF mode under the conditions of an HPF analysis volume of 0.35 μL and an HPF detection volume of 2000 to 2500 particles. The measured average circularity and the percentage by number of particles having a particle size of 1.0 μm or less are shown in Table 1 below as "average circularity" and "percent by number of particles having a particle size of 1.0 μm or less."

[0116] <Mass average molecular weight (Mw)> The polymer primary particle dispersion was freeze-dried to remove water, and then the tetrahydrofuran (THF) soluble components were measured by gel permeation chromatography (GPC) under the following conditions. Apparatus: Tosoh GPC apparatus HLC-8320, Column: TOSOH TSKgel SuperHM-H (diameter 6 m x length 150 mm x 2), Solvent: THF, Column temperature: 40°C, Flow rate: 0.5 mL / min, Sample concentration: 0.1% by mass, Calibration curve: Standard polystyrene

[0117] <Emulsion solids concentration> The solid content concentration of the emulsion was determined by heating 2 g of the sample at 195°C for 90 minutes to evaporate the water using an infrared moisture meter FD-610 manufactured by Kett Electric Laboratory.

[0118] Next, the wax dispersion, pigment dispersion, and polymer primary particle dispersion used in the examples and comparative examples will be described.

[0119] <Wax dispersion W1> The wax used was Ester Wax 1 (NOF Corporation product name: WEP-3, melting point 73°C, acid value 0.1 mg KOH / g, hydroxyl value 3 mg KOH / g or less (all catalog values), chemical formula C 21 H 43 COOC 22 H 45) 30 parts, Decaglycerin decabehenate (Mitsubishi Chemical Foods Corporation, product name: B100D, hydroxyl value 27, melting point 70 ° C) 0.24 parts, 20% sodium dodecylbenzenesulfonate aqueous solution (hereinafter referred to as 20% DBS aqueous solution) 1.93 parts, demineralized water 67.83 parts were heated to 90 ° C and mixed for 20 minutes in a CSTR-type stirring bed equipped with a 45-degree inclined three-stage paddle blade. Next, while this dispersion was heated to 90 ° C, circulation emulsification was started under pressure conditions of 25 MPa using a valve homogenizer (Gaulin, 15-M-8PA type), and the particle size was measured with a Nanotrac. The median diameter (D50) was dispersed until it reached 245 nm, and wax dispersion W1 (emulsion solids concentration = 30.5%) was prepared.

[0120] <Wax dispersion W2> Ester wax 1 15.0 parts, Ester wax 2 (NOF Corporation product name: WEP-5, melting point 82°C, acid value 0.1 mg KOH / g, hydroxyl value 3 mg KOH / g or less (all catalog values), chemical formula C(CH2OCOC) 21 H 43 )4) Wax dispersion W2 (emulsion solids concentration = 30.5%) was prepared in the same manner as W1, except that 15.0 parts of PEG-4, 1.93 parts of 20% DBS aqueous solution, and 68.7 parts of demineralized water were used.

[0121] <Wax dispersion W3> Ester wax 3 (chemical formula C 21 H 43 COOC 22 H 45 Wax dispersion W3 (emulsion solids concentration=31.2%) was prepared in the same manner as in W1, except that 30 parts of the 20% DBS aqueous solution, 1.93 parts, and 68.7 parts of demineralized water were used.

[0122] <Wax dispersion W4> Ester wax 4 (chemical formula C 40 H 80 Wax dispersion W4 (emulsion solids concentration=30.3%) was prepared in the same manner as in W1 above, except that 30 parts of O2), 1.93 parts of a 20% DBS aqueous solution, and 68.7 parts of demineralized water were used.

[0123] <Pigment dispersion P1> A pigment premix liquid was obtained by adding 24 parts of Pigment Blue 15:3 (cyan pigment (copper phthalocyanine complex) manufactured by Dainichiseika Color & Chemicals Co., Ltd.), 1 part of a 20% DBS aqueous solution, 9 parts of a nonionic surfactant (Emulgen 120 manufactured by Kao Corporation), and 67 parts of ion-exchanged water with a conductivity of 2 μS / cm to a container of a mixer equipped with a propeller blade, and pre-dispersing the mixture. This premix liquid was then supplied as a raw material slurry to a wet bead mill, where it was dispersed. The inner diameter of the stator was 120 mm, the diameter of the separator was 60 mm, and zirconia beads with a diameter of 0.1 mm were used as dispersion media. The effective internal volume of the stator was approximately 2 liters, and the media filling volume was 1.4 liters, resulting in a media filling rate of 70%. The rotor rotation speed was kept constant (circumferential speed of the rotor tip was approximately 11 m / sec), and the premix slurry was fed from the feed port at a feed rate of approximately 40 liters / hr using a non-pulsating metering pump. When the specified particle size was reached, pigment dispersion P1 was obtained from the discharge port. During operation, cooling water at about 10° C. was circulated from the jacket. The pigment dispersion median diameter D50 was 83 nm, the dispersion solid content was 34.3%, and the pigment solid content was 24.1%.

[0124] <Polymer primary particle dispersion A1> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 35.3 parts of wax dispersion W1, 258 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate, and the internal temperature was raised to 70°C under a nitrogen stream while stirring. Then, with stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, 300 minutes after the start of polymerization, the internal temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring continued until 540 minutes after the start of polymerization.

[0125] (monomers) Styrene 71.8 parts Butyl acrylate 28.2 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 0.60 parts

[0126] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 66.7 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 8% L-(+) ascorbic acid aqueous solution 30.1 parts (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0127] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white polymer primary particle dispersion A1. The median diameter (D50) measured using a Nanotrac was 239 nm. The mass average molecular weight (Mw) of the polymer primary particles was 80,000. The Tg measured by DSC was 51.2°C.

[0128] <Polymer primary particle dispersion A2> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 44.1 parts of wax dispersion W2 and 252 parts of demineralized water, and the internal temperature was raised to 90°C under a nitrogen stream while stirring. With stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added over 30 to 420 minutes from the start of polymerization. 300 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. 330 minutes after the start of polymerization, the internal temperature was raised to 95°C. Heating and stirring was continued until 540 minutes after the start of polymerization.

[0129] (monomers) Styrene 76.8 parts Butyl acrylate 23.2 parts Acrylic acid 1.5 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 1.0 parts

[0130] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 67.3 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 29.7 parts of 8% L-(+) ascorbic acid aqueous solution (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.05 part

[0131] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white polymer primary particle dispersion A2. The median diameter (D50) measured using a Nanotrac was 238 nm. The mass average molecular weight (Mw) of the polymer primary particles was 75,000.

[0132] <Polymer primary particle dispersion A3> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices was charged with 102.4 parts of the following wax dispersion W3, 283 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate, and the internal temperature was raised to 70°C under a nitrogen stream while stirring. Thereafter, with stirring continued, the following mixture of monomers and emulsifier solution was added over 300 minutes. The time when the addition of the mixture began was considered the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. 300 minutes after the start of polymerization, the internal temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring continued until 540 minutes after the start of polymerization.

[0133] (monomers) Styrene 71.8 parts Butyl acrylate 28.2 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 parts Hexanediol diacrylate 0.60 parts

[0134] (emulsifier aqueous solution) ·20% DBS aqueous solution 1.0 part 66.7 parts demineralized water (Aqueous initiator solution) 15.5 parts 8% hydrogen peroxide solution 8% L-(+) ascorbic acid aqueous solution 30.1 parts (iron sulfate aqueous solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0135] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white polymer primary particle dispersion A3. The median diameter (D50) measured using Nanotrac was 211 nm. The weight average molecular weight (Mw) was 94345. The Tg measured by DSC was 50.7°C.

[0136] <Polymer primary particle dispersion A4> A polymer primary particle dispersion A4 was obtained in the same manner as in the preparation of polymer primary particle dispersion A3, except that wax dispersion W3 was changed to wax dispersion W1. The median diameter (D50) measured using Nanotrac was 215 nm. The mass average molecular weight (Mw) of the polymer primary particles was 84,000. The Tg measured by DSC was 50.9°C.

[0137] <Polymer primary particle dispersion A5> A polymer primary particle dispersion A5 was obtained in the same manner as in the preparation of polymer primary particle dispersion A4, except that wax dispersion W1 was changed to wax dispersion W4. The median diameter (D50) measured using Nanotrac was 195 nm. The mass average molecular weight (Mw) of the polymer primary particles was 79,000. The Tg measured by DSC was 50.5°C.

[0138] [Example 1] Toner C1 was prepared as follows.

[0139] To a mixer equipped with a stirrer, a heating / cooling device, and devices for feeding raw materials and auxiliaries, 31.2 parts (solid content) of the polymer primary particle dispersion A1, 35.0 parts (solid content) of the polymer primary particle dispersion A3, 0.2 parts (solid content) of a 20% aqueous DBS solution, 0.10 parts (solid content) of a 5% aqueous iron (II) sulfate heptahydrate solution, and 4.4 parts (solid content) of the pigment dispersion P1 were added in this order with stirring. The internal temperature was raised to 42.0°C over 60 minutes, and then to 45.0°C over 210 minutes. The volume median particle diameter (Dv50) was measured using a Multisizer and found to be 4.95 μm. 22.3 parts (solids) of polymer primary particle dispersion A2 was added over 30 minutes. After 30 minutes, 10.0 parts (solids) of polymer primary particle dispersion A2 was added over an additional 10 minutes. After 30 minutes, 4.1 parts (solids) of a 20% DBS aqueous solution and 23 parts of deionized water were added, and the mixture was heated to 80°C over 95 minutes, and then to 83°C over 60 minutes. It was then cooled to 30°C over 30 minutes.

[0140] The resulting dispersion was extracted and filtered using a No. 5C filter paper manufactured by Toyo Roshi Kaisha, Ltd., under suction with an aspirator. The cake remaining on the filter paper was transferred to a stainless steel container equipped with a stirrer (propeller blade), and ion-exchanged water with an electrical conductivity of 1 μS / cm was added and stirred to uniformly disperse the mixture. This process was repeated until the electrical conductivity of the filtrate reached 2 μS / cm. The resulting cake was then dried for 48 hours in a fan dryer set at 40°C, yielding toner base particles B1.

[0141] Toner base particles B1 (100 parts) prepared in this way were added polymer / silica composite particles (ATLAS100: manufactured by Cabot Corporation; silica / polymer ratio = 70 / 30, true specific gravity = 1.7 g / cm 3 4 parts of a mixture of titania and silica (containing octahydropentalene), 0.5 parts of titania and silica composite oxide particles (STX50.1: manufactured by Nippon Aerosil Co., Ltd.), and 0.4 parts of small particle silica (RY200L: manufactured by Nippon Aerosil Co., Ltd.) were added, and the mixture was stirred and mixed in a Henschel mixer at 3000 rpm for 15 minutes, followed by sieving to obtain toner C1. The volume median particle diameter of the obtained toner C1 was 5.41 μm, and the average circularity was 0.966.

[0142] [Example 2] In Example 1, toner C2 was prepared in the same manner as toner C1, except that the polymer primary particle dispersion liquid A1 was 16.2 parts (solid content) and the polymer primary particle dispersion liquid A3 was 50.0 parts (solid content). The volume median particle diameter of the obtained toner C2 was 5.54 μm, and the average circularity was 0.967.

[0143] [Example 3] In Example 1, toner C3 was prepared in the same manner as toner C1, except that the polymer primary particle dispersion liquid A1 was 31.2 parts (solid content) and the polymer primary particle dispersion liquid A5 was 35.0 parts (solid content). The volume median particle diameter of the obtained toner C3 was 5.48 μm, and the average circularity was 0.966.

[0144] [Comparative Example 1] In Example 1, toner C4 was prepared in the same manner as toner C1, except that the polymer primary particle dispersion liquid A1 was 64.7 parts (solid content) and the polymer primary particle dispersion liquid A3 was 0 parts (solid content). The volume median particle diameter of the obtained toner C4 was 5.75 μm, and the average circularity was 0.965.

[0145] [Comparative Example 2] In Example 1, toner C5 was prepared in the same manner as toner C1, except that the polymer primary particle dispersion liquid A3 was changed to the polymer primary particle dispersion liquid A4. <D= The volume median particle diameter of the obtained toner C5 was 5.46 μm, and the average circularity was 0.965.

[0146] [DSC Measurement Method] The DSC measurement of the toner was performed by the following method. The apparatus used was AAQ20 manufactured by TA Instruments and the cooling device RCS90. A TzeroStandard was used as the sample pan, and 3.0 mg of the measurement sample was weighed out.

[0147] The measurements were carried out as follows. The temperature was adjusted to 20°C, and the first temperature increase was made to 120°C at 10°C / min, held at 120°C for 5 minutes, and then decreased to 0°C at 10°C / min. The temperature was held at 0°C for 5 minutes. The second temperature increase was made to 120°C at 10°C / min. The endothermic heat amounts during the first and second temperature rises were measured. The endothermic amount was measured by drawing a straight line from the high-temperature base line to the rise of the endothermic peak on the low-temperature side. Figure 1 shows DSC curves for the toner obtained in Example 1 at the first and second temperature rises. Figure 2 shows DSC curves for the toner obtained in Comparative Example 1 at the first and second temperature rises. In both figures, the upward direction of the vertical axis represents heat generation, the downward direction of the vertical axis represents heat absorption, and the horizontal axis represents temperature.

[0148] <Fixation test: Printing test and evaluation> The resulting developing toner was applied to a commercially available printer with a printing speed of 16 ppm (Paper Per Minutes), a non-magnetic single-component developing rubber roller, a metal blade, an organic photoreceptor charged by a charging roller (PCR), and the fixing unit removed, at a toner adhesion rate of approximately 0.5 mg / cm on recording paper (OKI Excellent White (product name)). 2 An unfixed toner image was printed.

[0149] The heat roll fixing machine used had a roller diameter of 27 mm, a nip width of 9 mm, a heater on the upper roller, and a roller surface made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) without silicone oil coating. The roller surface temperatures were set to 145°C, 150°C, and 155°C, and fixing was performed at each temperature at a fixing speed of 229 mm / sec to prepare evaluation samples.

[0150] The evaluation criteria for the fixation test are as follows: ◯: The fixed image did not offset, and no image defects occurred even when rubbed. △: The fixed image did not offset, but image defects occurred when rubbed. x: The fixed image was offset.

[0151] <Storage stability test> A metal cylinder with a diameter of 2 cm was placed upright on a metal plate, and a medical paper was wrapped around the inside of the cylinder. 10 g of developing toner was gently poured into the vertically placed metal cylinder, and then a 20 g weight was placed on top of the toner. The metal cylinder was placed on the metal plate and placed in a thermo-hygrostat at a temperature of 50°C and a relative humidity of 55% for 48 hours. After removing the sample from the thermo-hygrostat, the metal cylinder and wrapping paper were gently removed, and the toner that had adhered to the cylindrical shape was removed while still in the upright position. Loads were applied in increments of 10 g to the toner particles in a vertically placed, fixed state, and the load at which the cylindrical shape collapsed was measured. The evaluation results are shown in Table 2.

[0152] The evaluation criteria are as follows: ◯: Collapsed under a load of 80 g or less. This means that the toner was weakly adhered and the storage stability was good. △: It did not collapse under a load of 80 g, but collapsed under a load of 150 g or less. x: No collapse under a load of 150 g. This means that the toner adhered strongly and the storage stability was poor.

[0153] [Table 1]

[0154] [Table 2]

[0155] (Consideration) From the above examples and the results of tests conducted by the inventors up to now, it has been found that in the present toner, even when a compound exhibiting specific thermal properties, for example, wax, is partially heated to a temperature above its melting point during fixing and becomes liquid, it does not dissolve or mix with other components of the toner, such as the binder resin or pigment, and remains as a single wax, thereby maintaining a high release force, enabling the toner to be fixed at low temperatures, and further exhibiting good storage stability.

Claims

1. A toner comprising particles containing a binder resin, a colorant, and a wax, The binder resin includes a styrene copolymer resin or a poly(meth)acrylic resin, The toner contains, as the wax, an ester wax containing 60% by mass or more of components having 22 or more carbon atoms.

2. 2. The toner according to claim 1, wherein the ester wax has a melting point of 70 to 80° C. and is incompatible with the binder resin even when melted (referred to as "low-temperature fixing wax").

3. 3. The toner according to claim 1, wherein the ester wax comprises at least one selected from the group consisting of behenyl behenate, montanic acid ester, stearyl stearate, and pentaerythritol tetrabehenate.

4. In differential scanning calorimetry (DSC) in which a temperature program including steps of increasing the temperature from 40° C. to 100° C. or higher at a temperature increase rate of 10° C. / min (first temperature increase), then decreasing the temperature to 40° C. or lower at a temperature decrease rate of 10° C. / min (first temperature decrease), and subsequently increasing the temperature to 100° C. or higher at a temperature increase rate of 10° C. / min (second temperature increase), The toner according to any one of claims 1 to 3, wherein a difference between a half width of an endothermic peak during a first temperature increase and a half width of an exothermic peak during a first temperature decrease is 7.0°C or less, and a difference between a half width of an endothermic peak during a second temperature increase and a half width of an exothermic peak during a first temperature decrease is 7.00°C or less.

5. In differential scanning calorimetry (DSC) in which a temperature program including steps of increasing the temperature from 40° C. to 100° C. or higher at a temperature increase rate of 10° C. / min (first temperature increase), then decreasing the temperature to 40° C. or lower at a temperature decrease rate of 10° C. / min (first temperature decrease), and subsequently increasing the temperature to 100° C. or higher at a temperature increase rate of 10° C. / min (second temperature increase), 5. The toner according to claim 1, wherein a total amount HA2 of heat absorption from 40° C. to 100° C. during the second temperature rise satisfies the following relationship (3): (3) HA2≧19J / g

6. In differential scanning calorimetry (DSC) in which a temperature program including steps of increasing the temperature from 40° C. to 100° C. or higher at a temperature increase rate of 10° C. / min (first temperature increase), then decreasing the temperature to 40° C. or lower at a temperature decrease rate of 10° C. / min (first temperature decrease), and subsequently increasing the temperature to 100° C. or higher at a temperature increase rate of 10° C. / min (second temperature increase), 6. The toner according to claim 1, wherein a total amount HA1 of heat absorption during the first temperature rise from 40° C. to 100° C. satisfies the following relationship (2): (2) HA1≧20J / g

7. In differential scanning calorimetry (DSC) in which a temperature program including steps of increasing the temperature from 40° C. to 100° C. or higher at a temperature increase rate of 10° C. / min (first temperature increase), then decreasing the temperature to 40° C. or lower at a temperature decrease rate of 10° C. / min (first temperature decrease), and subsequently increasing the temperature to 100° C. or higher at a temperature increase rate of 10° C. / min (second temperature increase), The toner according to any one of claims 1 to 6, wherein a total amount HA1 of heat absorption from 40°C to 100°C during the first temperature rise and a total amount HA2 of heat absorption from 40°C to 100°C during the second temperature rise satisfy the following relationship (1): (1) HA2 / HA1>0.80

8. 8. The toner according to claim 1, wherein the total content of the waxes is 10.0 to 20.0% by mass, and the content of the ester wax is 30 to 80% by mass of the total content (100% by mass) of the waxes.

9. 9. The toner according to claim 1, wherein the toner comprises toner base particles and an external additive, the toner base particles having a multilayer structure comprising a core layer and an outer layer, the core layer containing a binder resin, a colorant, and a wax, the outer layer containing resin fine particles that are not compatible with the binder resin and exist as particles within or on the surface of the toner base particles, a charge control agent, and a wax, and the core layer contains the ester wax.

10. 5. The toner according to claim 4, wherein in differential scanning calorimetry (DSC) in which the temperature program is performed, the difference between the half-width of the endothermic peak during the first temperature increase and the half-width of the exothermic peak during the first temperature decrease is 6.0°C or less.

11. 5. The toner according to claim 4, wherein in differential scanning calorimetry (DSC) in which the temperature program is carried out, the difference between the half-width of the endothermic peak during the second temperature increase and the half-width of the exothermic peak during the first temperature decrease is 6.0° C. or less.

12. The toner according to any one of claims 1 to 10, wherein the styrene copolymer resin or the poly(meth)acrylic resin is a polymer of a monomer composition containing an acidic monomer or a basic monomer.

13. A toner cartridge containing the toner according to any one of claims 1 to 12.

14. An image forming apparatus containing the toner according to any one of claims 1 to 12.

Images