Toner, toner cartridge, image formation device, and printed matter

Abstract

This toner has at least a binding resin. The binding resin includes at least a polyester resin. The contained amount of the polyester resin is not less than 2.5 mass% with respect to the total mass of the toner. In a printed matter obtained by fixing, on a PET-coated paper, the toner in a printing condition of a printing temperature of 175°C, a printing speed of 16 ppm, and a printing density of 0.8 mg / cm2, if A represents the total length at which the polyester resin and the PET-coated paper are in contact with each other in a cross section of the printed matter and B represents the total length at which the toner and the PET-coated paper are in contact with each other, a ratio A / B of A and B satisfies formula (1).　(1): 0.05≤ A / B ≤0.55

Description

Toner, toner cartridge, image forming device and printed matter

[0001] The present invention relates to a toner that has excellent adhesion to a print medium, low-temperature fixability, and storage stability, a toner cartridge and image forming apparatus that contain this toner, and printed matter that uses this toner.

[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, and transferred to a printing medium such as transfer paper. The toner is then heated and fixed to form an 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, a wax, etc. Styrene acrylic resin is usually used as the binder resin for the toner base particles.

[0004] Such toners are required to have excellent adhesion to print media such as paper. In particular, in recent years, PET-coated paper has been widely used as a print medium for the purpose of improving the variety, design, luxury, and durability of printed matter. Therefore, toners are required to have excellent adhesion to PET-coated paper.

[0005] When forming an image on a print medium, the toner is heated to fix it. Because the power required for this heating accounts for the majority of the power consumed by image forming devices such as copiers, toner is required to have the property of being fixed at a lower temperature (low-temperature fixability).

[0006] Conventionally, as a toner with improved transferability, low-temperature fixability, and heat-resistant storage stability, there has been proposed a toner for developing electrostatic latent images, which contains toner base particles having a core-shell structure and an external additive, the toner base particles having core particles containing a vinyl-based resin and a shell covering the surface of the core particle at a coverage rate in the range of 60 to 99%, the shell containing an amorphous polyester resin, the external additive containing crosslinked vinyl-based resin particles, and the crosslinked vinyl-based resin particles having a number-average particle size in the range of 30 to 300 nm (Patent Document 1).

[0007] Japanese Patent Application Laid-Open No. 2017-156543

[0008] Conventional toners that use styrene-acrylic resin as the binder resin for toner base particles have had insufficient adhesion to print media, particularly PET-coated paper. This is thought to be due to the poor compatibility of styrene-acrylic resin with PET-coated paper as a material, as well as the fact that styrene-acrylic resin is hard and brittle, resulting in poor adhesion at the interface between the toner particles and the print medium.

[0009] The toner base particles of Patent Document 1 have a core-shell structure in which the core particles are coated with a shell made of an amorphous polyester resin, which improves adhesion to a printing medium to a certain extent, but has the following drawbacks: The coverage by the shell is too high, and the amount of the relatively expensive amorphous polyester resin is large, resulting in high costs. Furthermore, the surface has a more hydrophilic structure, which makes the toner particles more susceptible to moisture absorption, resulting in poor storage stability, particularly under high humidity conditions and poor environmental stability.

[0010] The present invention aims to provide a toner that has good adhesion to printing media, exhibits good adhesion even to PET-coated paper, has excellent low-temperature fixing properties and storage stability, and can be manufactured at relatively low cost; a toner cartridge and image forming device containing this toner; and printed matter using this toner.

[0011] The present inventors have discovered that the above-mentioned problems can be solved by using a predetermined amount of polyester resin as the binder resin of the toner, and producing a toner in which the ratio A / B, where A is the total length of contact between the polyester resin and the printing medium and B is the total length of contact between the toner and the printing medium, as evaluated by a specific method, falls within a predetermined range.

[0012] [1] A toner having at least a binder resin, wherein the binder resin contains at least a polyester resin, and the content of the polyester resin is 2.5% by mass or more relative to the total mass of the toner, and the toner is printed at a printing temperature of 175°C, a printing speed of 16 ppm, and a printing density of 0.8 mg / cm ２ In a printed matter obtained by fixing the toner on PET-coated paper under the printing conditions above, when the total length of contact between the polyester resin and the PET-coated paper in the cross section of the printed matter is A and the total length of contact between the toner and the PET-coated paper is B, A and B satisfy the following formula (1): 0.05≦A / B≦0.55 (1)

[0013] [2] The toner according to [1], wherein the binder resin further contains a styrene-acrylic resin.

[0014] [3] The toner according to [1] or [2], wherein the polyester resin is an amorphous polyester resin.

[0015] [4] The toner according to any one of [1] to [3], wherein the content of the polyester resin is 2.5% by mass or more and 40% by mass or less with respect to the total mass of the toner.

[0016] [5] The toner according to any one of [1] to [4], further comprising a wax.

[0017] [6] The toner according to [5], wherein the content of the wax is 5% by mass or more and 30% by mass or less with respect to the total mass of the toner.

[0018] [7] The toner according to [5] or [6], wherein the wax is a crystalline wax.

[0019] [8] The toner according to [7], wherein in differential scanning calorimetry (DSC) where 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 subsequently increasing the temperature to 100°C or higher at a temperature increase rate of 10°C / min (second temperature increase), the difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the first temperature increase [(first temperature decrease) - (first temperature increase)] is 7.0°C or less, and the difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the second temperature increase [(first temperature decrease) - (second temperature increase)] is 7.0°C or less.

[0020] [9] The toner according to any one of [1] to [8], wherein the polyester resin has an acid value of 5 mgKOH / g or more.

[0021]

[10] The toner according to any one of [1] to [9], wherein the glass transition temperature (Tg) of the polyester resin is 50° C. or higher and 70° C. or lower.

[0022]

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

[10] , which has a core-shell structure, the binder resin of the core being the styrene acrylic resin, and the binder resin of the shell being the polyester resin.

[0023]

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

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

[0024]

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

[12] , further comprising a colorant.

[0025]

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

[13] .

[0026]

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

[13] .

[0027]

[16] A printed matter having a toner fixed on a printing medium, wherein the toner is a toner having at least a binder resin, the binder resin includes at least a polyester resin, and the content of the polyester resin is 2.5 mass % or more relative to the total mass of the toner, and the toner is printed at a printing temperature of 175°C, a printing speed of 16 ppm, and a printing density of 0.8 mg / cm ２ In a printed matter obtained by fixing to PET-coated paper under the printing conditions above, when the total length of contact between the polyester resin and the PET-coated paper in a cross section of the printed matter is A and the total length of contact between the toner and the PET-coated paper is B, A and B satisfy the following formula (1): 0.05≦A / B≦0.55 (1)

[0028]

[17] The printed matter according to

[16] , wherein the binder resin further contains a styrene-acrylic resin.

[0029] According to the present invention, there are provided a toner that exhibits good adhesion to printing media, exhibits good adhesion even to PET-coated paper, and has excellent low-temperature fixing properties and storage stability, a toner cartridge and image forming device containing this toner, and printed matter using this toner.

[0030] 1 is a cross-sectional SEM photograph of a fixed image of toner C1 produced in Example 1.

[0031] The following describes in detail the mode for carrying out the present invention (hereinafter, "embodiments of the invention"). The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.

[0032] In this specification, when an expression is used such as "x to y" (x and y are any numbers), it means "not less than x and not more than y," and also includes the meaning of "preferably greater than x" or "preferably less than y," unless otherwise specified. Furthermore, when an expression is used such as "not less than x" (x is any number) or "not more than y" (y is any number), it also includes the meaning of "preferably greater than x" or "preferably less than y."

[0033] [Toner] The toner according to the embodiment of the present invention (hereinafter referred to as "the toner") is a toner having at least a binder resin, the binder resin including at least a polyester resin, and the content of the polyester resin relative to the total mass of the toner, and the toner is printed at a printing temperature of 175°C, a printing speed of 16 ppm (Paper Per Minutes), and a printing density of 0.8 mg / cm. ２ In a printed matter obtained by fixing the toner on PET-coated paper under the printing conditions above, when the total length of contact between the polyester resin and the PET-coated paper in the cross section of the printed matter is A and the total length of contact between the toner and the PET-coated paper is B, the ratio A / B of A and B (hereinafter referred to as "A / B ratio") satisfies the following formula (1): 0.05≦A / B≦0.55 (1)

[0034] The present toner contains a binder resin, and the binder resin contains at least a polyester resin. The binder resin preferably further contains a styrene-acrylic resin. The present toner is preferably a toner comprising toner base particles (hereinafter referred to as "the present toner base particles") that further contain a colorant, a charge control agent, and other components as necessary, and an external additive. However, the present toner is not necessarily limited to the above configuration. For example, it may not contain a colorant (clear toner), or it may not contain a charge control agent or an external additive.

[0035] <A / B Ratio> The A / B ratio of the present toner is characterized by satisfying the above formula (1). The fact that the A / B ratio satisfies the above formula (1) indicates that the amount of polyester resin present on the surface of the present toner is appropriate. Furthermore, the present toner preferably has a core-shell structure, with the binder resin of the core preferably being a styrene-acrylic resin and the binder resin of the shell preferably being a polyester resin. When the A / B ratio is 0.05 or higher, the polyester resin present on the surface of the toner particles provides good adhesion to the print medium. Particularly for PET-coated paper, the presence of a polyester resin having the same ester structure on the surface of the toner particles significantly improves adhesion and increases fixing strength. Furthermore, the presence of the polyester resin on the surface of the toner particles increases the tenacity of the contact surface between the polyester resin particles at the toner particle / toner particle interface due to its hydrogen bonding properties, thereby also increasing adhesion strength. On the other hand, the presence of a relatively small amount of polyester resin, such that the A / B ratio is 0.55 or less, improves the storage stability of the present toner. Furthermore, the increase in cost due to the use of a relatively expensive polyester resin can be suppressed.

[0036] The A / B ratio can be determined as follows: The toner is printed at a printing temperature of 175° C., a printing speed of 16 ppm (Paper Per Minutes), and a printing density of 0.8 mg / cm ２ The toner is fixed onto PET-coated paper under the printing conditions to produce a print, and the cross section of the PET-coated paper is observed at 10,000 magnifications using a backscattered electron detector in a scanning electron microscope (SEM). The observation procedure described above is repeated for a sufficient number of different visual fields, and observation images are taken. A sufficient number of visual fields can be considered 30 or more. In the examples described below, observations were made for 40 visual fields. The length of the portion of the polyester resin on the toner surface that is in contact with the surface of the printing medium is determined for each image, and the sum (A) of these values ​​is then divided by the sum (B) of the length of the portion of the toner that is in contact with the surface of the printing medium for each image to obtain a value (A / B). Even if the observed cross section contains a portion where the toner has peeled off from the fixing surface, the length is still measured as if there is contact.

[0037] (A) and (B) will be explained in more detail using FIG. 1. In FIG. 1, in the SEM image, each component in the toner appears with different contrast due to atomic number, density differences, and edge effects. In FIG. 1, the continuous layer represents the styrene acrylic resin. Of the discontinuous layers, the low-contrast portion located at the outer interface of the toner particle represents the polyester resin. The highest-contrast portion present inside the toner particle represents the wax. The low-contrast portion finely dispersed inside the toner particle represents the colorant. The fine, low-contrast portion at the outermost part of the toner represents the inorganic external additive. Therefore, the dotted line portion in FIG. 1 corresponds to the "area where the polyester resin on the toner surface is in contact with the surface of the printing medium (PET-coated paper)." The total length of the dotted line portion corresponds to (A). Meanwhile, the total length of the dashed line portion in FIG. 1 corresponds to the "area where the toner is in contact with the surface of the printing medium (PET-coated paper)." This corresponds to (B).

[0038] The toner in Fig. 1 is a toner having a core-shell structure in which the core component is a styrene acrylic resin and the shell component is a polyester resin. In the present invention, the "core-shell structure" refers to a structure in which the surface of the core component is covered with the shell component, but is not limited to a structure in which the core component is completely covered with the shell component, and may have a structure in which the surface of the core component is partially exposed and the shell component is discontinuous, as shown in Fig. 1.

[0039] The A / B ratio calculated as described above can be considered as the area ratio of the polyester resin on the toner surface in contact with the PET-coated paper surface, or in other words, the proportion of polyester resin present on the surface of the toner. In a printed matter with fixed toner, the orientation of each fixed toner particle is considered to be randomly oriented. Therefore, even when observing a cross section of a printed matter in one direction, the orientation (orientation state) and position of each toner particle are different, so if a sufficient number of fields of view are observed in one direction, it can be considered that a sufficient number of directions and positions have been observed. Therefore, by adding up a sufficient number of length information pieces obtained from each field of view, this can be considered as the area calculated by integration, and can be considered as the area ratio as described above. The procedure will be described in more detail in the Examples below, but the techniques and equipment are not limited to these, and any cross-section preparation method or microscope observation method that can produce appropriate results for the purpose can be used.

[0040] From the viewpoints of improving adhesion and fixability to a printing medium and storage stability, the A / B ratio of the toner is preferably 0.05 or more, more preferably 0.10 or more, even more preferably 0.20 or more, and particularly preferably 0.30 or more, while it is preferably 0.55 or less, more preferably 0.50 or less, even more preferably 0.45 or less, and particularly preferably 0.40 or less.

[0041] In order for the present toner to satisfy the above A / B ratio, it is preferable that the present toner has a core-shell structure in which the binder resin of the core is a styrene acrylic resin and the binder resin of the shell is a polyester resin, and that the amount of polyester resin constituting the shell is an appropriate amount.

[0042] <Ratio (X / Y) of Calculated Coverage Rate of Polyester Resin on Toner Surface to Measured Coverage Rate of Polyester Resin Y> The present toner preferably has a ratio (X / Y) of 1.5 or more of calculated coverage rate of polyester resin on the toner surface to measured coverage rate of polyester resin Y. Among these, 2.0 or more is more preferable, 2.25 or more is even more preferable, 2.5 or more is even more preferable, and 3.0 or more is particularly preferable. On the other hand, this ratio is preferably 20.0 or less, more preferably 10.0 or less, even more preferably 5.0 or less, and particularly preferably 3.9 or less. The larger this ratio, the thicker the polyester resin layer. By setting the thickness within an appropriate range, the toner exhibits good adhesion to the printing medium. The polyester resin layer refers to a state in which the polyester resin is unevenly distributed on the toner surface, and its shape may be either fine particles or a thin film. Furthermore, the layer may cover the toner surface continuously or discontinuously. In the present invention, from the viewpoint of satisfying the A / B ratio, the layer preferably covers the toner surface discontinuously. The calculated value X and the measured value Y of the coverage of the polyester resin on the toner surface can be determined by the following methods.

[0043] <Method for calculating calculated value X of coverage rate of polyester resin on toner surface> The coverage rate of polyester resin particles on the toner particle surface when polyester resin particles are uniformly dispersed and adhered one by one on the toner particle surface is defined as the theoretical coverage rate, and this theoretical coverage rate is synonymous with the calculated value X.

[0044] In the following, an example will be described in which the toner mother particles have a core-shell structure, the binder resin of the core is a styrene acrylic resin, and the binder resin of the shell is a polyester resin. The coverage of the shell particles on the surface of a core particle when the shell particles are uniformly dispersed and attached one by one to the surface of the core particle is defined as the theoretical coverage, and this theoretical coverage is synonymous with the calculated value X below. The calculated value X is defined as in the following formula (2). In this case, the core particles and shell particles are assumed to be true spheres. X = {(number of shells per core particle) x (projected area of ​​one shell particle)} ÷ surface area of ​​one core particle ... (2)

[0045] (Method for calculating the number of shells per core particle) When the mass ratio of the core is A, the mass ratio of the shell is expressed as (1-A). This value can be calculated from the actual charge ratio. The mass of each of the core particle and the shell particle can be calculated as follows: {(π / 6) x (diameter of the particle)} ３ × specific gravity The specific gravity can be calculated as 1.0 for styrene acrylic resin, and 1.1 for polyester resin, for example. Here, the mass of one core particle is S, and the mass of one shell particle is s. Furthermore, if the number of core particles is K and the number of shell particles is k, then when S × K = A, s × k = (1 - A) holds. Therefore, (the number of shells per core particle) can be expressed as follows: (number of shells per core particle) = k ÷ K In other words, if A, S, and s are known values, it is possible to calculate (the number of shells per core particle) using the above formula.

[0046] (Method for measuring the projected area of ​​shell 1 particle and the surface area of ​​core 1 particle) Assuming that the shell particle is a perfect sphere, the area occupied by the shell 1 particle on the core particle surface can be determined as the projected area when the shell particle is viewed from directly above. The projected area when a sphere is viewed from directly above is synonymous with the area of ​​a two-dimensional circle having the same diameter as the diameter of the sphere. Therefore, the projected area of ​​the shell 1 particle can be determined by the following formula (3): (Projected area of ​​shell 1 particle) = {(Diameter of shell particle) / 2} ２ ×π (3) Furthermore, assuming that the core particle is a perfect sphere, the surface area of ​​one core particle can be calculated using the formula for the surface area of ​​a sphere, as follows: (Surface area of ​​one core particle)=4×{(Diameter of core particle) / 2} ２ ×π... (4)

[0047] In this manner, the number of shells per core particle, the projected area of ​​one shell particle, and the surface area of ​​one core particle are determined, and then substituted into formula (2), to obtain the calculated value X, i.e., the theoretical coverage.

[0048] <Method for Measuring the Actual Value Y of the Coverage of Polyester Resin on the Toner Surface> Any means may be used to measure the actual value Y. For example, the aforementioned A / B ratio can be used as the actual value Y. Alternatively, the actual value Y can be determined by dyeing toner particles with ruthenium and analyzing images of the dyed toner particles observed using a scanning electron microscope. The ease with which ruthenium is dyed varies depending on the type of resin. For example, the rate at which ruthenium dyeing progresses differs between polyester resin and styrene-acrylic resin. Therefore, in the backscattered electron image of the obtained toner particle surface, a difference in brightness occurs between the surface formed by the polyester resin and the surface formed by the styrene-acrylic resin, making it possible to distinguish between the surface formed by the polyester resin and the surface formed by the styrene-acrylic resin.

[0049] <Average Thickness of Polyester Resin on Toner Surface> The average thickness of the polyester resin on the toner surface of the present toner is preferably 0.20 μm or more. Among these, 0.23 μm or more is more preferred, 0.25 μm or more is even more preferred, 0.28 μm or more is particularly preferred, and 0.30 μm or more is particularly preferred. On the other hand, this average thickness is preferably 0.70 μm or less, more preferably 0.55 μm or less, even more preferably 0.40 μm or less, and particularly preferably 0.35 μm or less. The average thickness of the polyester resin on the toner surface can be determined by the following method.

[0050] <Method for Measuring the Average Thickness of Polyester Resin on Toner Surface> Any method can be used to measure the average thickness of the polyester resin on the toner surface. For example, it can be determined by directly measuring the cross-sectional SEM image of the printed matter. In this case, a sufficient number of visual fields is considered to be 30 or more. In the examples described below, observations were made for each of 40 visual fields. It is also possible to calculate the average thickness of the polyester resin on the toner surface from the ratio (X / Y) of the calculated value X to the measured value Y of the polyester resin coverage on the toner surface. When the polyester resin adheres to the toner surface as single particles without aggregation, the average thickness of the polyester resin can be considered to coincide with the average particle size of the polyester resin latex. Since (X / Y) can be considered to represent a deviation from this theoretical value, the average thickness can be calculated using the following formula (5): (Average Thickness of Polyester Resin on Toner Surface) = (Average Particle Size of Polyester Resin Latex) x (X / Y) (5)

[0051] <Difference in Half Width of Exothermic Peak> The present toner preferably contains a wax, particularly a crystalline wax, as described below, so that in differential scanning calorimetry (DSC) in which a temperature program including steps of heating from 40°C to 100°C or higher, for example 40 to 130°C, 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 heating), and subsequently heating to 100°C or higher, for example 40 to 130°C, at a heating rate of 10°C / min (second heating), the difference between the half width of the endothermic peak during the first heating [(first heating) - (first heating)] is 7.0°C or less, and the difference between the half width of the endothermic peak during the first heating [(first heating) - (second heating)] is 7.0°C or less.

[0052] The difference between the half-width of the endothermic peak during temperature drop and the half-width of the exothermic peak during temperature rise 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 liquid within an extremely short time (approximately 1 second) of passing through the fixing unit of an 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 temperature rise and the exothermic peak during temperature drop are sharp, and the difference between the half-width of the endothermic peak during temperature drop and the half-width of the exothermic peak during temperature rise is small.

[0053] For these reasons, it is preferable that the present toner has a "difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the second temperature increase [(first temperature decrease) - (second temperature increase)]" of 7.0°C or less. In addition, it is more preferable that the "difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the first temperature increase [(first temperature decrease) - (first temperature increase)]" is also 7.0°C or less. In other words, it is preferable that both the "difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the first temperature increase [(first temperature decrease) - (first temperature increase)]" and the "difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the second temperature increase [(first temperature decrease) - (second temperature increase)]" are 7.0°C or less, and more preferably both are 3.6°C or less. That is, it is preferable that the sharp melting property of the wax in the toner is about the same level during the first temperature rise and the second temperature rise.

[0054] If the difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the first temperature increase [(first temperature decrease) - (first temperature increase)] is 7.0°C or less, the sharp melting property of the wax is sufficiently high and the low-temperature fixability 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, particularly preferably 3.0°C or less, and especially preferably 1.5°C or less.

[0055] If the difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the second temperature increase [(first temperature decrease) - (second temperature increase)] is 7.0°C or less, the crystallinity of the wax is sufficiently high and the toner has excellent storage stability. 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, particularly preferably 3.0°C or less, and especially preferably 1.5°C or less.

[0056] 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: After identifying the endothermic peak or exothermic peak based on the baseline, including the range below 40°C and above 100°C, the half-width value of the peak itself is used. In other words, the temperatures subject to the half-width value may include the range below 40°C and above 100°C.

[0057] There are no specific limitations on the means by which the toner satisfies the above-mentioned physical properties. In particular, as described below, 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 adjusting the combination and blending ratio of the waxes. When the wax is a mixture or contains impurities or by-products, the properties can also be achieved by adjusting the purity of the wax. Furthermore, the properties can also be suitably achieved by selecting and combining the binder resin and wax, as described below.

[0058] In the present invention, when differential scanning calorimetry (DSC) of a 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 temperature increase rate or temperature decrease rate. Therefore, for example, when measured at a rate of 5°C / min or 15°C / min, the values ​​obtained will be significantly different from those obtained when measured at a rate of 10°C / min.

[0059] <Toner Base Particles> The toner base particles may be a single-layer structure or a multilayer structure (core-shell structure) having a core and an outer layer (also referred to as a "shell"), but a core-shell structure is preferred to satisfy the above-mentioned A / B ratio. The binder resin of the core is preferably a styrene-acrylic resin. The binder resin of the shell is preferably a polyester resin. Furthermore, it is more preferred that the binder resin of the core is a styrene-acrylic resin and the binder resin of the shell is a polyester resin.

[0060] In the present invention, the term "core-shell structure" refers to a structure in which the surface of a core component is covered with a shell component, but is not limited to a structure in which the core component is completely covered with the shell component, and the surface of the core component may be partially exposed, or may be partially dispersed in the shell component.

[0061] In any of the methods for preparing toner base particles described below, the shell component refers to a component that is unevenly distributed on the surface of the toner base particle. The shape of the shell component when made into a toner may be a fine particle or a thin film, and may cover the core component continuously or discontinuously. In the present invention, it is preferable that the shell component discontinuously cover the core component in order to satisfy the A / B ratio.

[0062] When toner base particles are prepared in a wet medium having an aqueous and / or organic solvent as a continuous phase, there are two methods: one is to add shell particles simultaneously with the core components and thermodynamically arrange the shell particles at the interface between the core components and the wet medium (a method for controlling polarity), and the other is to add the shell particles after the core components and physically arrange them on the surface of the core components.Furthermore, it is also possible to combine the method for thermodynamically arranging the shell particles at the interface between the core components and the wet medium (a method for controlling polarity) and the method for adding the shell particles after the core components and physically arrange them on the surface of the core components.

[0063] When adding the shell fine particles after the core component, a method of adding the shell fine particles after the composition and / or shape of the core component is determined (the shape, physical properties, compatibility, etc. of the core component may change due to subsequent heating, aging, stirring, etc.) may also be used.

[0064] When the toner base particles have a multilayer structure having a core and a shell, the core preferably contains a binder resin and, if necessary, a colorant or wax, and preferably further contains a charge control agent and other components. The shell preferably uses a binder resin alone, but may contain, if necessary, a colorant or wax, and may further contain a charge control agent and other components.

[0065] From the above, it is preferable that the toner base particles have a core-shell structure, and that the binder resin of the core is a styrene acrylic resin and the binder resin of the shell is a polyester resin. In order to achieve such a structure, the toner can have the following composition, for example: 1) The content of styrene acrylic segments in the polyester resin of the shell is equal to or less than a certain value. 2) The content of polyester segments in the styrene acrylic resin of the core is equal to or less than a certain value. 3) The ratio of the acid values ​​of the styrene acrylic resin of the core to the polyester resin of the shell ([acid value of styrene acrylic resin of the core] / [acid value of polyester resin of the shell]) is 0.85 or more and 2.9 or less.

[0066] In the case of 1) above, the content of the styrene acrylic segment in the polyester resin of the shell is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the polyester resin. It is particularly preferable that the content is 0 part by mass, i.e., the polyester resin of the shell does not contain a styrene acrylic segment, in other words, it is not a styrene acrylic-modified polyester resin.

[0067] In the case of 2) above, the content of the polyester segment in the styrene-acrylic resin of the core is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of the styrene-acrylic resin. It is also preferable that the content is 0 part by mass, i.e., the styrene-acrylic resin of the core does not contain any polyester segment.

[0068] The method for polymerizing a polyester segment with a styrene-acrylic resin includes, for example, the following methods, but any method may be used: 2-1) A method of reacting a bireactive monomer with a polyester polymer segment, followed by a styrene-acrylic raw material monomer; 2-2) A method of reacting a bireactive monomer with a styrene-acrylic resin, followed by a polycarboxylic acid monomer and a polyhydric alcohol monomer; 2-3) A method of reacting a bireactive monomer with a styrene-acrylic resin and a polyester resin, followed by chemical bonding between them.

[0069] In the case of 3), the lower limit of the ratio of the acid values ​​of the styrene-acrylic resin of the core to the polyester resin of the shell ([acid value of styrene-acrylic resin of the core] / [acid value of polyester resin of the shell]) is more preferably 0.90 or more, and even more preferably 1.0 or more, and the upper limit is more preferably 2.5 or less, and even more preferably 2.0 or less. If it is above the lower limit, the hydrophilicity of the shell becomes higher than that of the core, making it difficult for the shell to penetrate into the toner particles during the aging process. If it is below the upper limit, the hydrophilicity of the shell is not too high, and the stabilization of the polyester resin dispersion becomes appropriate, resulting in an appropriate core-shell structure.

[0070] When the toner base particles have a core-shell structure, the binder resin of the shell preferably has a storage modulus at 70°C (G'(70°C)) (hereinafter, sometimes simply referred to as "G'(70°C)") of 500,000 Pa or more when measured with a rheometer. When the G'(70°C) of the binder resin of the shell is 500,000 Pa or more, better storage stability can be obtained. From the viewpoint of storage stability, the G'(70°C) of the binder resin of the shell is more preferably 700,000 Pa or more, and even more preferably 1,000,000 Pa or more. On the other hand, from the viewpoint of low-temperature fixability, the G'(70°C) of the binder resin of the shell is preferably 5,000,000 Pa or less, and more preferably 3,000,000 Pa or less.

[0071] When the toner base particles have a core-shell structure, the binder resin of the shell preferably has a storage modulus at 100°C (G'(100°C)) (hereinafter, sometimes simply referred to as "G'(100°C)") of 5000 Pa or less when measured with a rheometer. When the G'(100°C) of the binder resin of the shell is 5000 Pa or less, better low-temperature fixability can be obtained. From the viewpoint of low-temperature fixability, the G'(100°C) of the binder resin of the shell is more preferably 3000 Pa or less, and even more preferably 2000 Pa or less. On the other hand, from the viewpoint of storage stability, the G'(100°C) of the binder resin of the shell is preferably 500 Pa or more, and more preferably 1000 Pa or more.

[0072] As described above, in the present invention, the binder resin of the shell is preferably made of a polyester resin, and therefore, it is preferable that the polyester resin constituting the shell satisfies the above G'(70°C) and G'(100°C).

[0073] In the present invention, in order to obtain a binder resin having contradictory physical properties as G'(70°C) and G'(100°C), a method may be used in which a polyester resin that satisfies only the above G'(70°C) and G'(100°C) is used alone as the binder resin for the shell, or a polyester resin that satisfies only the above G'(70°C) and a polyester resin that satisfies only the above G'(100°C) are mixed together so that the G'(70°C) and G'(100°C) of the polyester resin mixture satisfy the above conditions.

[0074] The G' (70°C) and G' (100°C) of the binder resin can be measured by dynamic viscoelasticity measurement. For example, a solid obtained by vacuum drying a polyester dispersion can be used as a sample for dynamic viscoelasticity measurement. For example, an ARES rheometer manufactured by TA Instruments can be used as an apparatus for dynamic viscoelasticity measurement. Specific measurement methods include the following: Approximately 1.3 g of the sample is placed in a 25 mm diameter jig and pressed with a 30 kg load for 10 minutes using a press heated to 50°C to form a pellet. The obtained pellet is placed in a measuring device equipped with circular parallel plates with a diameter of 25 mm, and the upper plate is lowered while the temperature is raised to 120°C to adjust the pellet thickness to 3.0 to 3.5 mm. The temperature is then lowered, and measurements are performed under the following conditions: measurement frequency 6.28 rad / sec, initial temperature 40°C, pre-measurement delay time 3 minutes, automatic tension adjustment (tensile direction, initial force 0, automatic tension sensitivity 2.0 g, automatic tension switching elastic modulus 1.0E+08 Pa), final temperature 150°C, temperature rise rate 4°C / min, measurement cycle time 1 minute, initial strain 0.1%, and automatic strain adjustment.

[0075] <Styrene-acrylic resin> Styrene-acrylic resin (hereinafter sometimes abbreviated as "StAc") is a copolymer formed using a styrene-based monomer and a (meth)acrylic acid ester-based monomer. Preferably, the copolymer is a copolymer formed using a (meth)acrylic acid-based monomer in addition to the styrene-based monomer and the (meth)acrylic acid ester-based monomer.

[0076] Examples of styrene-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-ethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, 2,4-dimethylstyrene, and dichlorostyrene. These can be used alone or in combination of two or more. Among these, from the viewpoints of reactivity, ease of polymerization, and cost, styrene and p-methylstyrene are preferred, and styrene is more preferred.

[0077] Examples of (meth)acrylic acid ester monomers include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, cyclohexyl acrylate, heptyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, heptyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. These may be used alone or in combination of two or more. Among these, from the viewpoints of toner fixability, anti-offset properties, and cost, propyl acrylate, n-butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate are preferred, n-butyl acrylate and 2-ethylhexyl acrylate are more preferred, and n-butyl acrylate is even more preferred.

[0078] Examples of (meth)acrylic acid monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and cinnamic acid. These may be used alone or in combination of two or more. Among these, from the viewpoints of reactivity and ease of polymerization, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred.

[0079] The proportion of styrene-based monomers in 100% by mass of all monomers constituting the styrene-acrylic resin is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more, from the viewpoint of toner storage stability. Meanwhile, from the viewpoint of toner fixability, it is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. Meanwhile, the proportion of (meth)acrylic acid ester-based monomers in 100% by mass of all monomers constituting the styrene-acrylic resin is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of toner fixability. Meanwhile, from the viewpoint of toner storage stability, it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less. Meanwhile, the proportion of (meth)acrylic acid-based monomers in 100% by mass of all monomers constituting the styrene-acrylic resin is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.7% by mass or more, from the viewpoint of toner developability. On the other hand, from the viewpoint of the environmental stability of the toner, the content is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, and even more preferably 2.0% by mass or less.

[0080] The content ratio of the styrene-based monomer and (meth)acrylic acid ester-based monomer constituting the styrene-based monomer is preferably 0.18 or more, more preferably 0.25 or more, and on the other hand, is preferably 0.67 or less, more preferably 0.54 or less. In particular, by setting the content ratio in the range of 0.49 to 0.54, excellent low-temperature fixability can be achieved while maintaining storage stability at a practically usable level. The content ratio of the styrene-based monomer and (meth)acrylic acid monomer constituting the styrene-based monomer is preferably 0.005 or more, more preferably 0.006 or more, and on the other hand, is preferably 0.035 or less, more preferably 0.030 or less.

[0081] Furthermore, other polyfunctional monomers can be used to make the styrene-acrylic resin have a crosslinked structure. Examples of other polyfunctional monomers include hexanediol diacrylate, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, and neopentyl glycol diacrylate. Among these, hexanediol diacrylate is preferred.

[0082] The styrene-acrylic resin preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 30,000 to 150,000 as measured by gel permeation chromatography (GPC). When the styrene-acrylic resin has a weight average molecular weight (Mw) of 30,000 or more, sufficient heat-resistant storage stability is obtained. When the styrene-acrylic resin has a weight average molecular weight (Mw) of 150,000 or less, sufficient low-temperature fixability is obtained. The method for measuring the weight average molecular weight (Mw) of the styrene-acrylic resin is as described in the Examples section below.

[0083] The styrene-acrylic resin may be used alone, or two or more types having different monomer compositions, physical properties, etc. may be used in combination.

[0084] The content of the styrene acrylic resin in the present toner is preferably 60 to 85% by mass, and more preferably 65 to 80% by mass, relative to the total mass (100% by mass) of the present toner from the viewpoints of toner cost reduction, environmental stability, fixability, and storage stability. If the content of the styrene acrylic resin is equal to or greater than the above lower limit, there is a significant cost advantage, and environmental stability and storage stability under high-humidity conditions are maintained. If the content of the styrene acrylic resin is equal to or less than the above upper limit, the content of the polyester resin on the surface is sufficient, and therefore improved adhesion to the medium is observed, which is preferable.

[0085] <Polyester Resin> The polyester resin (sometimes abbreviated as "PES") used as the binder resin of the present toner is preferably an amorphous polyester resin from the viewpoints of fixability, storage stability, and adhesion to a medium.

[0086] The amorphous polyester resin is a polyester resin that has a glass transition point (Tg) in an endothermic curve obtained by differential scanning calorimetry (DSC), but does not have a melting point, i.e., a clear endothermic peak upon heating, and exhibits amorphous properties.

[0087] The amorphous polyester resin is obtained by polycondensation reaction of polycarboxylic acid monomers (derivatives) and polyhydric alcohol monomers (derivatives) in the presence of a suitable polymerization catalyst. Examples of the polycarboxylic acid monomer derivatives include alkyl esters, acid anhydrides, and acid chlorides of polycarboxylic acid monomers. Examples of the polyhydric alcohol monomer derivatives include esters of polyhydric alcohol monomers and hydroxycarboxylic acids.

[0088] Examples of polycarboxylic acid monomers include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenyl Examples of suitable carboxylic acids include dicarboxylic acids such as acetic acid, p-phenylene diacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracene dicarboxylic acid, and dodecenyl succinic acid; and tricarboxylic acids such as trimellitic acid, pyromellitic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, and pyrene tetracarboxylic acid. These may be used alone or in combination of two or more. Among these, from the viewpoints of storage stability, handling properties, cost, and supply amount of the toner, the dicarboxylic acid is preferably maleic acid, adipic acid, fumaric acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, isophthalic acid, or terephthalic acid, more preferably adipic acid, isophthalic acid, or terephthalic acid, and even more preferably isophthalic acid or terephthalic acid. From the viewpoint of ease of adjusting the polymerization rate, the tricarboxylic acid is preferably trimellitic acid or pyromellitic acid, and more preferably trimellitic acid.

[0089] Examples of polyhydric alcohol monomers include dihydric alcohols such as ethylene glycol, neopentyl glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, octanediol, decanediol, dodecanediol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A; and trihydric or higher polyols such as glycerin, pentaerythritol, trimethylolpropane, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine. These may be used alone or in combination of two or more. Among these, from the viewpoints of reducing colorability of the resin, ease of raw material availability, and charging properties, preferred dihydric alcohols are ethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A, more preferred are ethylene glycol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A, and even more preferred are ethylene glycol and a propylene oxide adduct of bisphenol A. From the viewpoint of ease of adjusting the polymerization rate, preferred trihydric or higher polyols are glycerin, pentaerythritol, and trimethylolpropane, and more preferred is trimethylolpropane.

[0090] The ratio of polycarboxylic acid to polyhydric alcohol is preferably such that the equivalent ratio (OH) / (COOH) of the hydroxyl group (OH) of the polyhydric alcohol to the carboxyl group (COOH) of the polycarboxylic acid is in the range of 1.5 / 1 to 1 / 1.5.

[0091] The acid value of the polyester resin is preferably 5 mgKOH / g or more. If the acid value of the polyester resin is equal to or higher than the above lower limit, sufficient stability can be obtained for use as a polyester dispersion in the aggregation step when preparing toner base particles. On the other hand, from the viewpoint of ease of preparation of particles having a polyester on the surface, it is preferable that the acid value of the polyester resin is 20 mgKOH / g or less. The acid value of the polyester resin is more preferably 8 mgKOH / g or more, even more preferably 10 mgKOH / g or more, more preferably 18 mgKOH / g or less, and even more preferably 15 mgKOH / g or less. The acid value of the polyester resin is measured by the method described in the Examples section below.

[0092] The glass transition temperature (Tg) of the polyester resin is preferably in the range of 50 to 70°C. If the glass transition temperature of the polyester resin is above the lower limit, the storage stability of the toner is maintained. If the glass transition temperature of the polyester resin is below the upper limit, the low-temperature fixability of the toner is not deteriorated, and the surface of the particles is easily covered uniformly in the aging process when preparing the toner base particles. The glass transition temperature of the polyester resin is more preferably 53°C or higher, even more preferably 55°C or higher, and more preferably 65°C or lower, even more preferably 63°C or lower, and particularly preferably 60°C or lower. The glass transition temperature of the polyester resin is measured by the method described in the Examples section below.

[0093] The softening temperature of the polyester resin is preferably in the range of 90 to 150°C. If the softening temperature of the polyester resin is equal to or higher than the lower limit, the storage stability of the toner is maintained. If the softening temperature of the polyester resin is equal to or lower than the upper limit, the low-temperature fixability of the toner is not deteriorated. The softening temperature of the polyester resin is more preferably 95°C or higher, even more preferably 100°C or higher, more preferably 135°C or lower, even more preferably 125°C or lower, and particularly preferably 115°C or lower. The softening temperature of the polyester resin is measured by the method described in the Examples section below.

[0094] The polyester resin preferably has a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 20,000 or more, more preferably 25,000 or more, and preferably 150,000 or less, more preferably 100,000 or less, and even more preferably 80,000 or less. The method for measuring the weight average molecular weight (Mw) of the polyester resin is as described in the Examples section below.

[0095] The present toner may contain only one type of polyester resin, or may contain two or more types of polyester resins having different monomer compositions, physical properties, and the like.

[0096] The polyester resin is contained in an amount of 2.5% by mass or more relative to the total mass of the toner, and is preferably contained in an amount of 2.5 to 40% by mass in order to satisfy the above-mentioned ratio A / B. The content ratio of the polyester resin relative to the total mass of the toner is more preferably 5% by mass or more, even more preferably 10% by mass or more, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0097] <Colorant> Any known colorant can be used as the colorant contained in the toner of the present invention. 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.

[0098] 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 a combination of toner sets, 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.

[0099] Specifically, examples of cyan include C.I. Pigment Blue 15:3 and C.I. Pigment Blue 15:4. Examples of yellow include C.I. Pigment Yellow 74, C.I. Pigment Yellow 83, which is a disazo dye / pigment, and C.I. Pigment Yellow 93, C.I. Pigment Yellow 155, C.I. Pigment Yellow 180, and C.I. Pigment Yellow 185, which are condensed azo dye / pigments. Examples of magenta include C.I. Pigment Red 48:1, C.I. Pigment Red 53:1, C.I. Pigment Red 57:1, C.I. Pigment Red 5, and C.I. Pigment Red 122, which is a quinacridone dye / pigment. Pigment Red 209, and monoazo dye pigments such as C.I. Pigment Red 269 (238).

[0100] The colorant is preferably used in an amount of 3 to 20% by mass relative to the total mass (100% by mass) of the toner.

[0101] <Wax> The toner may further contain a wax. By containing a wax, it is possible to improve low-temperature fixability and high-temperature offset property. The wax may be contained in any form in the toner. For example, the binder resin and the wax may be present in a partially or entirely compatible state, the core may be separated as a domain and encapsulated, the shell may be separated as a domain and encapsulated, or the wax may be present separated on the surface of the toner.

[0102] By including wax, particularly crystalline wax, the wax melts instantly when the toner is heated, improving fixability to the printing medium. Furthermore, if the wax is encapsulated separately from the core, with the core acting as a domain, it does not plasticize the toner, thereby maintaining storage stability. Specifically, if the wax is a crystalline wax with a more distinct melting point than ordinary wax, its compatibility with the binder resin decreases, resulting in a structure in which the wax and the binder resin in the core are completely separated, making it less likely to plasticize the resin and maintaining storage stability.

[0103] The type of wax contained in the present toner is not limited, but it is preferable to contain an ester wax, and more preferable to contain a crystalline wax, which will be described later.

[0104] Examples of ester waxes include ester waxes having a long-chain aliphatic group, such as behenyl behenate, stearyl behenate, montanic acid ester, stearyl stearate, and erythritol tetrabehenate. Of these, monoester waxes containing primarily C18 and / or C22 hydrocarbons are more preferred, and from the viewpoints of low dust and low-temperature fixation, behenyl behenate, stearyl behenate, behenyl stearate, and waxes containing primarily these are particularly preferred.

[0105] 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.

[0106] The crystalline wax preferably used in the present toner has a melting point peak (top of the endothermic peak in the second DSC temperature rise of the toner) of 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. If the wax melting point peak temperature is too high, low-temperature fixability and high gloss tend to be impaired. 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.

[0107] (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 of other waxes 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; and the like. Preferred examples include hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax; and silicone waxes.

[0108] (Amount of Wax) The amount of wax contained in the toner is preferably 5 to 30% by mass, more preferably 10 to 20% by mass, based on the total mass (100% by mass) of the toner. 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 80% by mass or less.

[0109] <Charge Control Agent> The toner may contain a charge control agent to improve the charging characteristics of the toner. Any known charge control agent can be used. Specific examples of charge control agents for positive charging include nigrosine dyes, amino group-containing vinyl copolymers, quaternary ammonium salt compounds, polyamine resins, etc. Specific examples of charge control agents for negative charging include metal-containing azo dyes containing metals such as chromium, zinc, iron, cobalt, and aluminum, and salts and metal complexes of salicylic acid or alkylsalicylic acid with the above metals.

[0110] The amount of the charge control agent is preferably 0.1 to 25% by mass, and more preferably 1 to 15% by mass, based on the total mass (100% by mass) of the 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.

[0111] <External Additive> The present toner usually contains an external additive to improve the fluidity and charge controllability of the toner. The external additive is usually attached to the surface of the toner base particles, but the degree to which the external additive is embedded in the base particles may be in any state. That is, some or all of the external additive may be attached to the base particle surface in a point-contact manner or embedded therein, and some or all of the external additive may be present in a dispersed or aggregated form on the base particle surface. The particle size of the external additive particles is preferably such that the ratio (particle size of external additive particles) / (average particle size of toner base particles) is in the range of 0.1% to 5% of the average particle size of the toner base particles.

[0112] The external additive may be selected from various inorganic or organic fine particles and used. Two or more types of external additives may be used in combination.

[0113] 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 titanic acid 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 black, magnetite, and ferrite.

[0114] As the organic fine particles, fine particles of styrene-based resin, acrylic-based resin, epoxy-based resin, melamine-based resin, etc. The charging stability can be improved by using fine particles containing fluorine atoms.

[0115] Among these external additives, silica, titanium oxide, alumina, zinc oxide, various carbon blacks, conductive carbon blacks, etc. are particularly suitable.

[0116] The external additive may be the inorganic or organic fine particles whose surfaces have been subjected to a surface treatment such as hydrophobization with a treatment agent such as a silane coupling agent such as hexamethyldisilazane (HMDS) or dimethyldichlorosilane (DMDS), a titanate-based coupling agent, a silicone oil treatment agent such as 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 may also be used in combination.

[0117] 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.

[0118] 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 in which a polymer having conjugated double bonds such as polyacetylene, polyphenylacetylene, and poly-p-phenylene is doped with a conductive substance such as a metal; and carbon such as carbon black and graphite. From the viewpoint of imparting conductivity without impairing the fluidity of the toner, conductive fine particles are more preferably conductive titanium oxide or those doped with a conductive substance.

[0119] 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.

[0120] <Form of the Toner> From the viewpoint of image reproducibility and toner consumption, the volume median particle diameter of the 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 with respect to dust, the volume median particle diameter of the toner is preferably 3.0 μm or more, more preferably 4.0 μm or more, and even more preferably 4.5 μm or more.

[0121] The "volume median particle size (Dv50)" in the present invention is defined as a value measured by the method described in the Examples section below, and is also defined as a value measured on toner particles finally obtained in a production process, which include toner base particles and, if necessary, external additives.

[0122] In order to suppress fogging, white background smearing, etc. and stably obtain high-quality images, the number percentage of particles having a primary particle diameter of 1.0 μm or less in the present toner is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less.

[0123] The shape of the toner of the present invention preferably has an average circularity of 0.92 to 0.99, more preferably 0.95 or more, and even more preferably 0.96 or more, as measured using a flow particle image analyzer FPIA-3000 (manufactured by Malvern Instruments).

[0124] The percentage by number of particles having a particle size of 1.0 μm or less and the average circularity are measured by the method described in the Examples section below.

[0125] [Method for Producing Toner] The present toner can be produced by producing the present toner base particles by a known method, and then externally adding an external additive to the present toner base particles as needed.

[0126] <Method for Producing the Present Toner Base Particles> The present toner base particles can be produced by preparing each raw material as particles smaller than the toner base particles, and then mixing, aggregating, and aging these to obtain toner base particles. For example, toner base particles can be obtained by mixing binder resin fine particles (primary polymer particles), colorant particles, and, if necessary, wax or a charge control agent, aggregating and aging (thermal fusion), filtering, washing, and drying. The binder resin fine particles (primary polymer particles) can be obtained by emulsion polymerization, or by obtaining a binder resin by any polymerization method (bulk polymerization, solution polymerization, suspension polymerization, etc.) and then mixing and emulsifying the binder resin with an aqueous medium. Because aggregating particles using an aqueous emulsion aggregation method makes it easier to control the circularity of the final base particles, primary polymer particles of styrene-acrylic resins are preferably obtained by emulsion polymerization, which produces an aqueous emulsion. For the same reason, primary polymer particles of polyester resins are preferably obtained as an aqueous emulsion using the latter emulsification method. Any of the above-mentioned methods for obtaining primary polymer particles can be used both when preparing primary polymer particles of a binder resin for the core and when preparing primary polymer particles of a binder resin for the shell.

[0127] (Method for producing primary polymer particles: emulsion polymerization) For example, primary polymer particles containing the raw material monomer of the styrene-acrylic resin as a constituent element can be obtained by emulsion polymerization using the monomer and, if necessary, an emulsifier, a polymerization initiator, and a chain transfer agent. Known emulsifiers can be used. As the emulsifier, one or more emulsifiers selected from cationic surfactants, anionic surfactants, and nonionic surfactants can be used in combination. Among these, anionic surfactants are preferred from the viewpoints of ease of particle production, washability, and waste liquid treatment.

[0128] Examples of cationic surfactants include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, and hexadecyl trimethyl ammonium bromide.

[0129] Examples of anionic surfactants include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate.

[0130] Examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, and monodecanoyl sucrose.

[0131] The amount of emulsifier used is preferably 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of raw material monomer. When the amount of emulsifier used is increased, the particle size of the resulting polymer primary particles becomes smaller. When the amount of emulsifier used is decreased, the particle size of the resulting polymer primary particles becomes larger. These emulsifiers can be used in combination with one or more protective colloids, such as polyvinyl alcohols (e.g., partially or completely saponified polyvinyl alcohol) and cellulose derivatives (e.g., hydroxyethyl cellulose).

[0132] As the polymerization initiator, known initiators can be used alone or in combination of two or more. Examples of the polymerization initiator include persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; redox initiators in which these persulfates are combined as a component with a reducing agent such as sodium sulfite; water-soluble polymerization initiators such as hydrogen peroxide, 4,4'-azobiscyanovaleric acid, t-butyl hydroperoxide, and cumene hydroperoxide; and redox initiators in which these water-soluble polymerization initiators are combined as a component with a reducing agent such as a ferrous salt; benzoyl peroxide, 2,2'-azobisisobutyronitrile, and the like. Among these, hydrogen peroxide is preferred from the viewpoints of reactivity and cost. These polymerization initiators may be added to the polymerization system before, simultaneously with, or after the addition of the monomer, and these addition methods may be combined as necessary.

[0133] As the chain transfer agent, known agents can be used alone or in combination of two or more. Examples of chain transfer agents that can be used include trichlorobromomethane, carbon tetrachloride, t-dodecyl mercaptan, and 2-mercaptoethanol. Among these, trichlorobromomethane is preferred from the viewpoints of low molecular weight, sharp molecular weight distribution, and cost.

[0134] Among emulsion polymerization methods, it is preferable to use so-called seed polymerization, in which wax is added as a seed during emulsion polymerization. By using seed polymerization, the wax is finely and uniformly dispersed in the toner, thereby preventing deterioration of the chargeability and heat resistance of the toner. It is also possible to prepare a wax / long-chain monomer dispersion by dispersing wax and a long-chain monomer such as stearyl acrylate in an aqueous dispersion medium in advance, and then polymerize the monomer in the presence of the wax / long-chain monomer.

[0135] (Method for producing primary polymer particles: a method in which a binder resin is obtained by any polymerization method, and then mixed with an aqueous medium and emulsified) After a binder resin is obtained by any polymerization method such as bulk polymerization, solution polymerization, or suspension polymerization, the binder resin is mixed with an aqueous medium and emulsified by applying a shear force, whereby primary polymer particles of the binder resin can be obtained.

[0136] Examples of emulsifiers for applying shear force include homogenizers, homomixers, pressure kneaders, extruders, media dispersers, etc. When the viscosity of the binder resin during emulsification is high and the primary polymer particles do not become small enough to reach the desired particle size, an emulsifier capable of applying pressure equal to or higher than atmospheric pressure can be used to raise the temperature to the higher of either the melting point or the glass transition temperature of the resin, thereby emulsifying the resin in a state where the viscosity of the resin is reduced, thereby obtaining primary polymer particles having the desired particle size.

[0137] Another method for reducing the resin viscosity may involve premixing an organic solvent with the binder resin. The organic solvent used is not particularly limited as long as it dissolves the styrene-acrylic resin, but examples include ketone-based solvents such as tetrahydrofuran (THF), methyl acetate, ethyl acetate, and methyl ethyl ketone, and benzene-based solvents such as benzene, toluene, and xylene. Furthermore, alcohol-based solvents such as ethanol and isopropyl alcohol may be added to water or the resin for the purposes of improving affinity with the aqueous medium and controlling the particle size distribution. When an organic solvent is added, it is necessary to remove the organic solvent from the emulsion after emulsification. Methods for removing the organic solvent include volatilizing the organic solvent at room temperature or under reduced pressure with heating.

[0138] For the purpose of controlling particle size distribution, salts such as sodium chloride and potassium chloride, ammonia, etc. may be added, and emulsifiers and dispersants may also be added. Examples of these emulsifiers and dispersants include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, and sodium polyacrylate; the aforementioned emulsifiers; and inorganic compounds such as tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, and barium carbonate. The amount of emulsifier and dispersant used is preferably 0.01 to 20 parts by mass per 100 parts by mass of the binder resin.

[0139] In addition to the above-mentioned methods, a phase inversion emulsification method may be used as a method for emulsifying a binder resin obtained by any polymerization method by mixing it with an aqueous medium. The phase inversion emulsification method involves adding an organic solvent, a neutralizing agent, and a dispersion stabilizer to the binder resin as needed, adding an aqueous medium dropwise under stirring to obtain emulsified particles, and then removing the organic solvent from the resin dispersion to obtain an emulsion. The organic solvent may be the same as the organic solvent described above. The neutralizing agent may be a common acid or alkali such as nitric acid, hydrochloric acid, sodium hydroxide, or ammonia.

[0140] (Particle size and molecular weight of primary polymer particles) The median diameter (D50) of the primary polymer particles of the binder resin is preferably 100 nm or more, more preferably 150 nm or more, even more preferably 180 nm or more, and 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 primary polymer particles of the binder resin is preferably 25,000 or more, and more preferably 30,000 or more, more preferably 40,000 or more, even more preferably 50,000 or more, and particularly preferably 70,000 or more, while preferably 500,000 or less, more preferably 300,000 or less, even more preferably 150,000 or less, and particularly preferably 100,000 or less. The median diameter (D50) and mass average molecular weight (Mw) of the primary polymer particles of the binder resin are measured by the method described in the Examples section below.

[0141] (Aggregation Step) In the aggregation step, the polymer primary particles, and optionally colorant particles, a charge control agent, wax, etc., are mixed simultaneously or sequentially. From the viewpoint of uniformity of composition and particle size, it is preferable to prepare dispersions of the respective components in advance, i.e., a polymer primary particle dispersion, optionally a colorant particle dispersion, a charge control agent dispersion, and a wax dispersion, and then mix them to obtain a mixed dispersion.

[0142] When the toner base particles have a core-shell structure, the primary polymer particles of the binder resin for the core and the primary polymer particles of the binder resin for the shell may be charged at the same time, or a part or all of the primary polymer particles of the binder resin for the core may be aggregated with other components, and then the primary polymer particles of the binder resin for the shell may be added.

[0143] When primary polymer particles of a core binder resin (also referred to as a core component) and primary polymer particles of a shell binder resin (also referred to as a shell component) are charged simultaneously, the shell component will spontaneously adhere to the periphery of the core component if the polarity of the shell component is designed so that it is thermodynamically intermediate between the polarity of the core component and that of the medium (for example, water). When the shell component is adhered in a wet medium such as water and / or an organic solvent, it is preferable to add the shell component after the composition of the raw material of the core component has been determined (when toner base particles are prepared by aggregating particles smaller than the toner base particles, part or all of the core component has been aggregated), from the viewpoint of arranging the shell component more closely on the surface of the core component.

[0144] The shell component may be added once or multiple times. The shell component added in the first addition may be different from the shell component added in the subsequent additions, and any combination thereof may be used. In order to increase the stability of the particle aggregates having a core-shell structure obtained in the aggregation step, it is preferable to fuse the aggregated particles in the aging step after the aggregation step.

[0145] The colorant particles are preferably used in a state of being dispersed in water in the presence of an emulsifier. The median diameter (D50) of the colorant particles is preferably 0.01 μm or more, particularly preferably 0.05 μm or more, and preferably 3 μm or less, particularly preferably 1 μm or less. The median diameter of the colorant particles is measured by the method described in the Examples section below.

[0146] The wax is preferably used in a state of being dispersed in water. The wax has a median diameter (D50) of preferably 100 nm or more, more preferably 150 nm or more, even more preferably 200 nm or more, and preferably 400 nm or less, more preferably 350 nm or less, even more preferably 300 nm or less. The wax median diameter is measured by the method described in the Examples section below.

[0147] In the aggregation step, aggregation is usually carried out in a tank equipped with a stirrer. The aggregation method includes a method of aggregating by heating, a method of aggregating by adding an electrolyte, and a method that combines these.

[0148] When an electrolyte is added to perform coagulation, the electrolyte may be any of an acid, an alkali, and a salt, and may be either organic or inorganic. Specific examples of the electrolyte include acids such as hydrochloric acid, nitric acid, sulfuric acid, and citric acid; alkalis such as sodium hydroxide, potassium hydroxide, and aqueous ammonia; and salts such as NaCl, KCl, LiCl, and Na ２ SO ４ , K. ２ SO ４ , Li ２ SO ４ , MgCl ２ , CaCl ２ , MgSO ４ , CaSO ４ , ZnSO ４ , Al ２ (SO ４ ) ３ , Fe ２ (SO ４ ) ３ , C.H. ３ COONa, C ６ H ５ SO ３ Among these, inorganic salts having a polyvalent metal cation of divalent or higher are preferred.

[0149] The amount of electrolyte added varies depending on the type of electrolyte, the target particle size, etc., but is preferably 0.02 parts by mass or more, more preferably 0.05 parts by mass or more, and preferably 25 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the solid components of the mixed dispersion. The aggregation temperature when aggregation is carried out by adding an electrolyte is preferably 20° C. or more, particularly preferably 30° C. or more, and preferably 70° C. or less, particularly preferably 60° C. or less.

[0150] The time required for aggregation is 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 temperature at 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.

[0151] (Aging Step) In the aging step, the mixed dispersion obtained in the aggregation step is heated under sufficient stirring conditions. In the case of a core-shell structure, the temperature in the aging step is preferably equal to or higher than the Tg of the primary polymer particles of the shell binder resin, more preferably equal to or higher than the Tg of the primary polymer particles of the shell binder resin. The time required for the aging step varies depending on the shape of the toner base particles to be targeted, but it is desirable to maintain the temperature for preferably 0.1 to 10 hours, particularly preferably 0.5 to 5 hours, after the temperature reaches or exceeds the Tg of the primary polymer particles of the shell binder resin.

[0152] 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 emulsifiers selected from those that can be used when producing polymer primary particles. It is particularly preferable to use the same emulsifier as that used when producing polymer primary particles.

[0153] When a surfactant is added, the amount added is not limited, but is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of the solid components of the mixed dispersion.

[0154] After the aggregation step, by adding a surfactant or adjusting the pH before the completion of the aging step, it is possible to suppress aggregation between particle aggregates obtained in the aggregation step, and it may be possible to suppress the generation of coarse particles in the aging step.

[0155] 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.

[0156] <Method of Adding External Additives> Examples of methods for adding external additives include a method using a high-speed agitator 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. It can also be produced by a step-by-step external addition method in which external additives are added separately. To prevent a temperature rise during external addition, a cooling device can be installed in the container, or the external addition can be performed in steps.

[0157] [Use Form] The present toner may be used in either the form of a two-component developer in which the toner is used together with a carrier, or a magnetic or non-magnetic one-component developer in which no carrier is used.

[0158] 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.

[0159] [Cartridge / Image Forming Apparatus] Next, an embodiment of an image forming apparatus (image forming apparatus of the present invention) using the toner 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.

[0160] The image forming apparatus includes 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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 devices using any method, such as corona transfer or roller transfer, can be used.

[0165] 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.

[0166] In the image forming apparatus configured as above, an image is recorded as follows.

[0167] First, the surface (photosensitive surface) of the electrophotographic photosensitive member 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 a DC voltage. Next, the charged photosensitive surface of the electrophotographic photosensitive member is exposed to light by an exposure device according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. Then, the electrostatic latent image formed on the photosensitive surface of the electrophotographic photosensitive member is developed by a developing device. In the developing device, the toner is formed into a thin layer by a regulating member such as a developing blade, and is triboelectrically charged to a predetermined polarity, and is carried on a developing roller while being transported and brought into contact with the surface of the electrophotographic photosensitive member.

[0168] 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 to recording paper or the like by a transfer device. After this, toner remaining on the photosensitive surface of the electrophotographic photosensitive member without being transferred is removed by a cleaning device. After the toner image is transferred to the printing medium such as recording paper, the toner image is thermally fixed to the printing medium such as recording paper by passing it through a fixing device, thereby obtaining the final image.

[0169] 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, which is a process of removing charge from an electrophotographic photosensitive member by exposing the electrophotographic photosensitive member to light.

[0170] The image forming apparatus may be further modified, for example, to be configured to perform a pre-exposure process, an auxiliary charging process, etc., to perform offset printing, or to be configured as a full-color tandem system using multiple types of toner.

[0171] 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 apparatus such as a copier or a laser beam printer. The present toner is applied to this toner cartridge, thereby constituting the toner cartridge of the present invention.

[0172] [Printed Matter] A printed matter according to an embodiment of the present invention (hereinafter referred to as the present printed matter) is a printed matter having a fixed toner on a printing medium, wherein the toner is a toner having at least a binder resin, the binder resin includes at least a polyester resin, and the content of the polyester resin is 3% by mass or more relative to the total mass of the toner, and the toner is printed at a printing temperature of 175°C, a printing speed of 16 ppm, and a printing density of 0.8 mg / cm. ２In a printed matter obtained by fixing the toner to a printing medium under the printing conditions, when the total length of contact between the polyester resin and the printing medium in the cross section of the printed matter is A and the total length of contact between the toner and the printing medium is B, the A / B ratio, which is the ratio of A to B, satisfies the following formula (1): 0.05≦A / B≦0.55 (1)

[0173] The present printed matter is produced by printing on a print medium using the present toner in a conventional manner. Therefore, the explanation of each constituent element described above for the present toner applies to the toner in the present printed matter.

[0174] The print medium for the present printed matter is not particularly limited, and may be any medium generally used in image forming devices, such as general printing paper (including cardboard, postcards, envelopes, plain paper, thin paper, etc.), resin (plastic) such as PET or metal coated paper, OHP sheets, OHP film, tracing paper, etc. Of these, the present toner is particularly suitable for prints using PET coated paper, as it has excellent adhesion to PET coated paper.

[0175] The present invention will be described in more detail below with reference to examples. 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."

[0176] The methods for measuring various physical properties are as follows.

[0177] <Median diameter (D50) of polymer primary particles, wax, and colorant (pigment)> The median diameter (D50) of the polymer primary particles, wax, and colorant (pigment) was measured using a Microtrac Nanotrac 150 (hereinafter abbreviated as Nanotrac) manufactured by Nikkiso Co., Ltd. and the company's analysis software, Microtrac Particle Analyzer Ver. 10.1.2-0.19EE. Measurements were performed using ion-exchanged water with an electrical conductivity of 0.5 μS / cm as the solvent, under the following measurement conditions: solvent refractive index: 1.333, measurement time: 120 seconds, number of measurements: 5, and the average value was calculated. Other setting conditions were particle refractive index: 1.59, transmittance: transparent, shape: spherical, and density: 1.04.

[0178] <Volume Median Particle Diameter (Dv50) of Toner> The volume median particle diameter (Dv50) of the toner was measured using a Multisizer III (aperture diameter: 100 μm or less, abbreviated as Multisizer) manufactured by Beckman Coulter, Inc. The toner was dispersed using Isoton II manufactured by the same company as a dispersion medium so that the dispersoid concentration was 0.03% by mass, and the measurement was performed. The measurement results were shown as "volume particle diameter."

[0179] <Average circularity and percentage by number of particles with a particle size of 1.0 μm or less> The average circularity and percentage by number 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 conditions of an HPF analysis volume of 0.35 μL and an HPF detection volume of 2000 to 2500 particles. The measurement results were shown as "circularity" and "number percentage of particles with a particle size of 1.0 μm or less."

[0180] <Weight Average Molecular Weight (Mw)> The weight average molecular weight of the styrene-acrylic resin was measured by freeze-drying a styrene-acrylic dispersion described below to remove water, and then measuring the THF-soluble component by gel permeation chromatography (GPC) under the following conditions. The weight average molecular weight of the amorphous polyester resin was measured by gel permeation chromatography (GPC) under the same conditions as above for the amorphous polyester resin obtained by the procedure described below. Apparatus: GPC apparatus HLC-8320 manufactured by Tosoh Corporation Column: TOSOH TSKgel Super HM-H (diameter 6 m × length 150 mm × 2 columns) Solvent: THF Column temperature: 40°C Flow rate: 0.5 mL / min Sample concentration: 0.1 mass% Calibration curve: Standard polystyrene

[0181] <Emulsion Solids Concentration> The emulsion solids concentration was determined by heating a 2 g sample at 195° C. for 90 minutes to evaporate the water using an infrared moisture meter FD-610 manufactured by Kett Electric Laboratory.

[0182] <Glass Transition Temperature (Tg)> The glass transition temperature of the polyester resin was measured using a differential scanning calorimeter ("DSC-60" manufactured by Shimadzu Corporation) from the intersection of the baseline of the chart and the tangent to the endothermic curve at a heating rate of 5°C / min. 10 mg±0.5 mg of the sample was weighed into an aluminum pan, melted at 100°C, which is higher than the glass transition temperature, for 10 minutes, and then rapidly cooled using dry ice.

[0183] <Softening Temperature (T4)> The softening temperature of the polyester resin was measured using a flow tester (manufactured by Shimadzu Corporation, "CFT-500D"), using a 1 mmφ×10 mm nozzle, a load of 294 N, and a uniform temperature increase rate of 3°C / min, at which the temperature at which half of 1.0 g of the resin sample flowed out was measured, and this was taken as the softening temperature.

[0184] <Acid Value> The acid value of the polyester resin was measured as follows. Approximately 0.2 g of the measurement sample was accurately weighed (a(g)) into a side-arm Erlenmeyer flask, 20 mL of benzyl alcohol was added, and the sample was heated in a nitrogen atmosphere using a heater at 230°C for 15 minutes to dissolve the measurement sample. After cooling to room temperature, 20 mL of chloroform and a few drops of cresol red solution were added, and the mixture was titrated with a 0.02 N KOH solution (titer amount = b(mL), titer of the KOH solution = p). A blank measurement was performed in the same manner (titer amount = c(mL)), and the acid value was calculated according to the following formula: Acid value (mgKOH / g) = {(b-c) x 0.02 x 56.11 x p} / a

[0185] Next, the wax dispersion, colorant dispersion, and polymer primary particle dispersion (styrene acrylic dispersion, polyester dispersion) used in the examples and comparative examples will be described.

[0186] <Wax dispersion W1> Ester wax 1 (chemical formula C ２１ H ４３ COOC ２２ H ４５ ), 30 parts of a 20% aqueous solution of sodium dodecylbenzenesulfonate (hereinafter referred to as 20% DBS aqueous solution), 1.93 parts of a 20% aqueous solution of sodium dodecylbenzenesulfonate, and 68.7 parts of demineralized water were placed in a CSTR-type stirring vessel equipped with a 45-degree inclined three-stage paddle blade, heated to 90 ° C in the stirring vessel, and mixed for 20 minutes. Next, while this dispersion was heated to 90 ° C, a valve homogenizer (Gaulin, 15-M-8PA type) was used to perform circulation emulsification under a pressure of 25 MPa, and the particle diameter was measured with a Nanotrac and dispersed until the median diameter (D50) reached 245 nm, producing wax dispersion W1 (emulsion solids concentration: 30.5%).

[0187] <Wax Dispersion W2> Wax Dispersion W2 (emulsion solids concentration: 30.5%) was prepared in the same manner as in W1, except that 30 parts of Ester Wax 2 (stearyl behenate, melting point 67°C), 1.93 parts of a 20% aqueous DBS solution, and 68.7 parts of demineralized water were used.

[0188] <Wax Dispersion W3> Wax Dispersion W2 (emulsion solids concentration: 30.8%) was prepared in the same manner as in W1, except that 30 parts of Ester Wax 3 (stearyl stearate, melting point 60°C), 1.93 parts of a 20% aqueous DBS solution, and 68.7 parts of demineralized water were used.

[0189] <Wax Dispersion W4> Wax Dispersion W4 (emulsion solids concentration: 30.2%) was prepared in the same manner as in W1 except that 30 parts of Ester Wax 4 (NOF Corporation product name: WEP-3, melting point 73°C, acid value 0.1 mgKOH / g, hydroxyl value 3 mgKOH / g or less (all catalog values)), 0.24 parts of Decaglycerin Decabehenate (Mitsubishi Chemical Corporation product name: B100D, hydroxyl value 27, melting point 70°C), 1.93 parts of a 20% aqueous DBS solution, and 67.83 parts of demineralized water were used.

[0190] <Wax Dispersion W5> Wax Dispersion W5 (emulsion solids concentration: 31.0%) was prepared in the same manner as in W1, except that 15.0 parts of Ester Wax 1, 15.0 parts of Ester Wax 4, 1.93 parts of a 20% aqueous DBS solution, and 68.7 parts of demineralized water were used.

[0191] <Wax Dispersion W6> Wax Dispersion W6 (emulsion solids concentration: 31.0%) was prepared in the same manner as in W1, except that 15.0 parts of Ester Wax 4, 15.0 parts of Ester Wax 5 (NOF Corporation product name: WEP-5, melting point 82°C, acid value 0.1 mgKOH / g, hydroxyl value 3 mgKOH / g or less (all catalog values)), 1.93 parts of a 20% aqueous DBS solution, and 68.7 parts of demineralized water were used.

[0192] <Colorant Dispersion G1> 24 parts of Pigment Blue 15:3 (cyan pigment (copper phthalocyanine complex) manufactured by Dainichiseika Color & Chemicals Co., Ltd.) as a colorant, 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 were added to a container of a stirrer equipped with a propeller blade and pre-dispersed to obtain a pigment premix. This premix was supplied as a raw material slurry to a wet bead mill and dispersed. The wet bead mill's stator had an inner diameter of 120 mmφ and a separator diameter of 60 mmφ, 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 (the peripheral speed of the rotor tip was approximately 11 m / sec), and the raw material slurry was fed from the feed port at a feed rate of approximately 40 L / hr using a non-pulsating metering pump. When the predetermined particle size was reached, dispersion was stopped, and colorant dispersion G1 was obtained from the discharge port. During operation, cooling water at approximately 10°C was circulated from the jacket. The median diameter (D50) of the colorant was 83 nm, the dispersion solids content was 34.3%, and the colorant solids content was 24.1%.

[0193] <Styrene Acrylic Dispersion A1> 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 were charged into a reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices. The temperature was then raised to 70°C under a nitrogen stream while stirring. Then, with continued stirring, 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 designated the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C 300 minutes after the start of polymerization. The following aqueous iron sulfate solution was added 330 minutes after the start of polymerization. Heating and stirring were continued until 540 minutes after the start of polymerization.

[0194] (Monomers) Styrene 70.0 parts Butyl acrylate 30.0 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.60 parts

[0195] (Emulsifier aqueous solution) 20% DBS aqueous solution 1.0 parts Demineralized water 66.7 parts (Initiator aqueous solution) 8% hydrogen peroxide aqueous solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 30.1 parts (Iron sulfate aqueous solution) 0.5% iron (II) sulfate heptahydrate aqueous solution 0.08 parts

[0196] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A1. The median diameter (D50) of the polymer primary particles measured using a Nanotrac was 230 nm. The mass average molecular weight (Mw) of the polymer primary particles was 81,608.

[0197] <Styrene Acrylic Dispersion A2> A reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material / auxiliary agent charging devices was charged with 70.7 parts of wax dispersion W1, 269 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate. The mixture was heated to an internal temperature of 70°C under a nitrogen stream while stirring. Then, with continued stirring, 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 designated 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 were continued until 540 minutes after the start of polymerization.

[0198] (Monomers) Styrene 70.0 parts Butyl acrylate 30.0 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.60 parts

[0199] (Emulsifier aqueous solution) 20% DBS aqueous solution 1.0 parts Demineralized water 66.7 parts (Initiator aqueous solution) 8% hydrogen peroxide aqueous solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 30.1 parts (Iron sulfate aqueous solution) 0.5% iron (II) sulfate heptahydrate aqueous solution 0.08 parts

[0200] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A2. The median diameter (D50) of the polymer primary particles measured using a Nanotrac was 234 nm. The mass average molecular weight (Mw) of the polymer primary particles was 80056.

[0201] <Styrene Acrylic Dispersion A3> 71.3 parts of Wax Dispersion W2, 271 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate were charged into a reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices. The temperature was then raised to 70°C under a nitrogen stream while stirring. Subsequently, the following mixture of monomers and emulsifier solutions was added over 300 minutes while continuing to stir, to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was designated the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C 300 minutes after the start of polymerization. The following aqueous iron sulfate solution was added 330 minutes after the start of polymerization. Heating and stirring were continued until 540 minutes after the start of polymerization.

[0202] (Monomers) Styrene 70.0 parts Butyl acrylate 30.0 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.60 parts

[0203] (Emulsifier aqueous solution) 20% DBS aqueous solution 1.0 parts Demineralized water 66.7 parts (Initiator aqueous solution) 8% hydrogen peroxide aqueous solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 30.1 parts (Iron sulfate aqueous solution) 0.5% iron (II) sulfate heptahydrate aqueous solution 0.08 parts

[0204] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A3. The median diameter (D50) of the polymer primary particles measured using a Nanotrac was 206 nm. The mass average molecular weight (Mw) of the polymer primary particles was 83,212.

[0205] <Styrene Acrylic Dispersion A4> 70.6 parts of Wax Dispersion W3, 272 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate were charged into a reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices. The temperature was then raised to 70°C under a nitrogen stream while stirring. Subsequently, the following mixture of monomers and emulsifier solutions was added over 300 minutes while continuing to stir, to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was designated the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C 300 minutes after the start of polymerization. The following aqueous iron sulfate solution was added 330 minutes after the start of polymerization. Heating and stirring were continued until 540 minutes after the start of polymerization.

[0206] (Monomers) Styrene 70.0 parts Butyl acrylate 30.0 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.60 parts

[0207] (Emulsifier aqueous solution) 20% DBS aqueous solution 1.0 parts Demineralized water 66.7 parts (Initiator aqueous solution) 8% hydrogen peroxide aqueous solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 30.1 parts (Iron sulfate aqueous solution) 0.5% iron (II) sulfate heptahydrate aqueous solution 0.08 parts

[0208] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A4. The median diameter (D50) of the polymer primary particles measured using a Nanotrac was 220 nm. The mass average molecular weight (Mw) of the polymer primary particles was 79,851.

[0209] <Styrene Acrylic Dispersion A5> 35.7 parts of Wax Dispersion W4, 257 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate were charged into a reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices. The temperature was then raised to 70°C under a nitrogen stream while stirring. Subsequently, the following mixture of monomers and emulsifier solutions was added over 300 minutes while continuing to stir, to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was designated the start of polymerization, and the following aqueous initiator solution was added dropwise between 30 and 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C 300 minutes after the start of polymerization. The following aqueous iron sulfate solution was added 330 minutes after the start of polymerization. Heating and stirring were continued until 540 minutes after the start of polymerization.

[0210] (Monomers) Styrene 70.0 parts Butyl acrylate 30.0 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.60 parts

[0211] (Emulsifier aqueous solution) 20% DBS aqueous solution 1.0 parts Demineralized water 66.7 parts (Initiator aqueous solution) 8% hydrogen peroxide aqueous solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 30.1 parts (Iron sulfate aqueous solution) 0.5% iron (II) sulfate heptahydrate aqueous solution 0.08 parts

[0212] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A5. The median diameter (D50) of the polymer primary particles measured using a Nanotrac was 273 nm. The mass average molecular weight (Mw) of the polymer primary particles was 79,487.

[0213] <Styrene Acrylic Dispersion A6> 34.8 parts of Wax Dispersion W5, 258 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate were charged into a reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices. The temperature was then raised to 70°C under a nitrogen stream while stirring. Subsequently, with continued stirring, the following mixture of monomers and emulsifier solutions was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was designated 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 temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring were continued until 540 minutes after the start of polymerization.

[0214] (Monomers) Styrene 70.0 parts Butyl acrylate 30.0 parts Acrylic acid 0.95 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.60 parts

[0215] (Emulsifier aqueous solution) 20% DBS aqueous solution 1.0 parts Demineralized water 66.7 parts (Initiator aqueous solution) 8% hydrogen peroxide aqueous solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 30.1 parts (Iron sulfate aqueous solution) 0.5% iron (II) sulfate heptahydrate aqueous solution 0.08 parts

[0216] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A6. The median diameter (D50) of the polymer primary particles measured using a Nanotrac was 222 nm. The mass average molecular weight (Mw) of the polymer primary particles was 80201.

[0217] <Styrene Acrylic Dispersion A7> 34.8 parts of Wax Dispersion W5, 258 parts of demineralized water, and 0.02 parts of a 0.5% aqueous solution of iron (II) sulfate heptahydrate were charged into a reactor equipped with a stirrer, a heating / cooling device, a concentrator, and various raw material and auxiliary agent charging devices. The temperature was then raised to 70°C under a nitrogen stream while stirring. Subsequently, with continued stirring, the following mixture of monomers and emulsifier solutions was added over 300 minutes to obtain an aqueous solution of monomers and emulsifier. The time when the addition of the mixture began was designated 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 temperature was raised to 90°C. 330 minutes after the start of polymerization, the following aqueous iron sulfate solution was added. Heating and stirring were continued until 540 minutes after the start of polymerization.

[0218] (Monomers) Styrene 76.8 parts Butyl acrylate 23.2 parts Acrylic acid 1.5 parts Trichlorobromomethane 1.0 part Hexanediol diacrylate 0.60 parts

[0219] (Emulsifier aqueous solution) 20% DBS aqueous solution 1.0 parts Demineralized water 66.7 parts (Initiator aqueous solution) 8% hydrogen peroxide aqueous solution 15.5 parts 8% L-(+) ascorbic acid aqueous solution 30.1 parts (Iron sulfate aqueous solution) 0.5% iron (II) sulfate heptahydrate aqueous solution 0.08 parts

[0220] After the polymerization reaction was completed, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A7. The median diameter (D50) of the polymer primary particles measured using a Nanotrac was 234 nm. The mass average molecular weight (Mw) of the polymer primary particles was 75,601.

[0221] <Polyester Resin> Amorphous polyester resins A, B, and C were produced as follows. The polycarboxylic acid component, polyhydric alcohol component, and polymerization catalyst, with the charge compositions shown in Table 1, were charged into a reaction vessel equipped with a distillation column. The amount of polymerization catalyst is the amount (ppm) relative to the acid component. Next, the stirring blade rotation speed in the reaction vessel was maintained at 120 rpm, and the temperature was raised. The reaction system was heated to a temperature of 265°C, and this temperature was maintained to carry out the esterification reaction. After the esterification reaction was completed when water no longer distilled from the reaction system, the temperature in the reaction system was lowered to 240°C, and the pressure in the reaction vessel was reduced over approximately 40 minutes to a vacuum of 133 Pa. The polycondensation reaction was carried out while distilling the alcohol component from the reaction system. The viscosity of the reaction system increased as the reaction proceeded. The vacuum was increased as the viscosity increased, and the condensation reaction was carried out until the torque of the stirring blade reached a value indicating the desired softening temperature. Then, when a predetermined torque was reached, stirring was stopped, the reaction system was returned to normal pressure, and the reaction mixture was pressurized with nitrogen and removed (discharged) from the reaction vessel to obtain each amorphous polyester resin. The mass average molecular weights (Mw) of the obtained amorphous polyester resins A and B were 26,000 and 72,960, respectively. The mass average molecular weights (Mw) were measured by the method described above. The physical properties (glass transition temperature, softening temperature, acid value) of the obtained amorphous polyester resins A, B, and C were measured. The results are shown in Table 1.

[0222] In Table 1, "BPA-PO 2.3 mol adduct" and "BPA-EO 2.3 mol adduct" mean the following: BPA-PO 2.3 mol adduct: propylene oxide derivative of bisphenol A (polyoxypropylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane (PO 2.3 mol adduct)) BPA-EO 2.3 mol adduct: ethylene oxide derivative of bisphenol A (polyoxyethylene-(2.3)-2,2-bis(4-hydroxyphenyl)propane (EO 2.3 mol adduct))

[0223]

[0224] <Polyester Dispersion P1> 25 parts of amorphous polyester resin A was dissolved in 75 parts of methyl ethyl ketone (MEK), and 22.7 g of 5% aqueous ammonia was added and stirred uniformly with a stirrer to prepare a resin solution. Next, 100 parts of demineralized water was placed in a round-bottom flask, and the prepared resin solution was added. The mixture was then dispersed at 8,000 rpm for 10 minutes using a homogenizer (IKA T25 model). The solvent was then removed by vacuum distillation at 80°C using an aspirator to obtain Polyester Dispersion P1. The median diameter (D50) of the primary polymer particles of the polyester resin particles in Polyester Dispersion P1 was measured using Nanotrac and found to be 180 nm. The storage modulus (G') of amorphous polyester resin A was G' (70°C) = 31,750,000 Pa and G' (100°C) = 5,317 Pa. The storage modulus (G'(70°C), G'(100°C)) was measured by the method described above.

[0225] <Polyester Dispersion P2> 25 parts of amorphous polyester resin B was dissolved in 75 parts of methyl ethyl ketone (MEK), and 9.46 g of 5% aqueous ammonia was added and stirred uniformly with a stirrer to prepare a resin solution. Next, 100 parts of demineralized water was added to a round-bottom flask, and the prepared resin solution was added. The mixture was then dispersed at 8,000 rpm for 10 minutes using a homogenizer (IKA T25 model). The solvent was then removed by vacuum distillation at 80°C using an aspirator to obtain polyester dispersion P2. The median diameter (D50) of the primary polymer particles of the polyester resin particles in polyester dispersion P2 was measured using a Nanotrac and found to be 230 nm. The storage modulus (G') of amorphous polyester resin B was G' (70°C) = 25,170,870 Pa, G' (100°C) = 25,814 Pa. The storage modulus (G'(70°C), G'(100°C)) was measured by the method described above.

[0226] <Polyester Dispersion P3> 25 parts of amorphous polyester resin C was dissolved in 75 parts of methyl ethyl ketone (MEK), and 20.8 g of 5% aqueous ammonia was added and stirred uniformly with a stirrer to prepare a resin solution. Next, 100 parts of demineralized water was added to a round-bottom flask, and the prepared resin solution was added. The mixture was then dispersed at 8,000 rpm for 10 minutes using a homogenizer (IKA T25 model). The solvent was then removed by vacuum distillation at 80°C using an aspirator to obtain Polyester Dispersion P3. The median diameter (D50) of the primary polymer particles of the polyester resin particles in Polyester Dispersion P3 was measured using a Nanotrac and found to be 200 nm. The storage modulus (G') of Amorphous Polyester Resin C was G' (70°C) = 5,540,400 Pa and G' (100°C) = 167,544 Pa. The storage modulus (G'(70°C), G'(100°C)) was measured by the method described above.

[0227] Example 1 Toner C1 was prepared as follows.

[0228] In a mixer equipped with a stirrer, a heating / cooling device, and various raw material and auxiliary agent charging devices, 85.0 parts (solids) of styrene acrylic dispersion A1, 0.17 parts (solids) of a 20% DBS aqueous solution, 0.56 parts (solids) of a 5% iron (II) sulfate heptahydrate aqueous solution, and 4.4 parts (solids) of colorant dispersion G1 were added in sequence while stirring. The internal temperature was raised to 41.0 ° C. over 60 minutes, and then raised to 45.0 ° C. over 180 minutes. Next, a mixture of 15.0 parts (solids) of polyester dispersion P1 and 0.3 parts (solids) of a 20% DBS aqueous solution (2 parts per 100 parts of polyester)) was added dropwise over 30 minutes. Thirty minutes after the completion of the dropwise addition, the pH of the system was adjusted to 8.0 using a 4.8% aqueous potassium hydroxide solution, and 6.0 parts (solid content) of a 20% aqueous DBS solution and 232.4 parts of deionized water were added, followed by heating to 75°C over 90 minutes, then heating to 80°C over 60 minutes, and then cooling to 30°C over 30 minutes.

[0229] The resulting dispersion was extracted and filtered under suction with an aspirator using No. 5C filter paper manufactured by Toyo Roshi Kaisha, Ltd. 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, followed by stirring for 30 minutes. This process was repeated until the electrical conductivity of the filtrate reached 2 μS / cm, and the resulting cake was then dried for 48 hours in a blower dryer set at 40° C. to obtain toner base particles B1.

[0230] To the thus prepared toner base particles B1 (100 parts), polymer / silica composite particles ATLAS100 (manufactured by Cabot Corporation, silica / polymer ratio = 70 / 30, true specific gravity = 1.7 g / cm ３4 parts of titania / silica composite oxide particles STX50.1 (manufactured by Nippon Aerosil Co., Ltd.), 0.5 parts of small particle size 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, and then sieved to obtain toner C1. The core / shell structure of this toner C1 is shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained toner C1 were measured. The results are shown in Table 2.

[0231] [Example 2] Toner C2 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A2. The core / shell structure of this Toner C2 is as shown in Table 3. The volume median particle size, average circularity, and number percentage of particles of 1.0 μm or less of the obtained Toner C2 were measured. The results are shown in Table 2.

[0232] [Example 3] Toner C3 was produced in the same manner as Toner C1 in Example 1, except that the styrene acrylic dispersion A1 was changed to 95.0 parts (solids content) and the polyester dispersion P1 was changed to 5.0 parts (solids content). The core / shell structure of this Toner C3 is as shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C3 were measured. The results are shown in Table 2.

[0233] [Example 4] Toner C4 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A3. The core / shell structure of this Toner C4 is as shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C4 were measured. The results are shown in Table 2.

[0234] [Example 5] Toner C5 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A4. The core / shell structure of this Toner C5 is as shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C5 were measured. The results are shown in Table 2.

[0235] [Example 6] Toner C6 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A5. The core / shell structure of this Toner C6 is as shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C6 were measured. The results are shown in Table 2.

[0236] [Example 7] Toner C7 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with 97.0 parts (solids) of styrene acrylic dispersion A5 and 3.0 parts (solids) of polyester dispersion P1. The core / shell structure of Toner C7 is shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C7 were measured. The results are shown in Table 2.

[0237] Example 8 Toner C8 was prepared in the same manner as Toner C1 in Example 1, except that 70.0 parts (solids) of Styrene Acrylic Dispersion A5 was used instead of Styrene Acrylic Dispersion A1, and 30.0 parts (solids) of Polyester Dispersion P1 were used. The core / shell structure of Toner C8 is shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C8 were measured. The results are shown in Table 2.

[0238] [Example 9] Toner C9 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A5 and polyester dispersion P1 was replaced with polyester dispersion P2. The core / shell structure of this Toner C9 is shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C9 were measured. The results are shown in Table 2.

[0239] [Example 10] Toner C10 was produced in the same manner as Toner C1 in Example 1, except that styrene acrylic dispersion A1 was replaced with styrene acrylic dispersion A6. The core / shell structure of this Toner C10 is as shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C10 were measured. The results are shown in Table 2.

[0240] Comparative Example 1 Toner C11 was prepared as follows.

[0241] In a mixer equipped with a stirrer, a heating / cooling device, and various raw material and auxiliary agent charging devices, 85.0 parts (solids) of styrene acrylic dispersion A5, 0.17 parts (solids) of a 20% DBS aqueous solution, 0.56 parts (solids) of a 5% iron (II) sulfate heptahydrate aqueous solution, and 4.4 parts (solids) of colorant dispersion G1 were added in this order while stirring. The internal temperature was raised to 41.0°C over 60 minutes, and then raised to 45.0°C over 180 minutes. Next, 15.0 parts (solids) of styrene acrylic dispersion A7 were added dropwise over 30 minutes. After 30 minutes, 4.0 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 90 minutes, then to 83°C over 60 minutes. The mixture was then cooled to 30°C over 30 minutes.

[0242] The resulting dispersion was extracted and filtered under suction with an aspirator using No. 5C filter paper manufactured by Toyo Roshi Kaisha, Ltd. 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, followed by stirring for 30 minutes. This process was repeated until the electrical conductivity of the filtrate reached 2 μS / cm, and the resulting cake was then dried for 48 hours in a blower dryer set at 40° C. to obtain toner base particles B11.

[0243] To the thus prepared toner base particles B11 (100 parts), polymer / silica composite particles ATLAS100 (manufactured by Cabot Corporation, silica / polymer ratio = 70 / 30, true specific gravity = 1.7 g / cm ３4 parts of titania / silica composite oxide particles STX50.1 (manufactured by Nippon Aerosil Co., Ltd.), 0.5 parts of small particle size silica RY200L (manufactured by Nippon Aerosil Co., Ltd.) were added, and the mixture was stirred and mixed in a Henschel mixer at 3,000 rpm for 15 minutes, and then sieved to obtain toner C11. The core / shell structure of this toner C11 is shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained toner C11 were measured. The results are shown in Table 2.

[0244] Comparative Example 2 Toner C12 was prepared in the same manner as Toner C1 in Example 1, except that Styrene Acrylic Dispersion A1 was replaced with 99.0 parts (solids) of Styrene Acrylic Dispersion A5 and 1.0 part (solids) of Polyester Dispersion P1. The core / shell structure of Toner C12 is shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C12 were measured. The results are shown in Table 2.

[0245] Comparative Example 3 Toner C13 was prepared in the same manner as Toner C1 in Example 1, except that Styrene Acrylic Dispersion A1 was replaced with Styrene Acrylic Dispersion A5 and Polyester Dispersion P1 was replaced with 15.0 parts (solids) of Polyester Dispersion P3. The core / shell structure of this Toner C13 is shown in Table 3. The volume median particle size, average circularity, and number percentage of particles 1.0 μm or less of the obtained Toner C13 were measured. The results are shown in Table 2.

[0246]

[0247] <Procedure for cross-sectional SEM observation of fixed image and calculation of polyester resin contact length ratio (A / B) of fixed surface> A 0.8 mg / cm2 ink was applied to a print medium (PET coated paper) under the same printing conditions as in the <Scraping test> described later. ２ The toner was fixed onto the entire surface at a density of 10,000, and the cross section of the PET coated paper was observed at 10,000 magnifications using a backscattered electron detector of a scanning electron microscope (SEM).

[0248] The observation procedure described above was repeated 40 times for each different field of view, and 40 observation images were taken. The length of the portion of the polyester resin on the toner surface that was in contact with the surface of the printing medium was determined for each image, and the sum (A) of these values ​​was then calculated. The length of the portion of the toner that was in contact with the surface of the printing medium for each image was then calculated. The sum (B) of these values ​​was then divided by this sum to obtain the value (A / B) that was used as the length ratio of the polyester resin on the toner surface that was in contact with the surface of the PET-coated paper. Note that even if there was a portion of the toner peeled off from the fixing surface in the observed cross section, this was still considered to be in contact and the length was measured.

[0249] The (A) and (B) were determined as described above. For example, for toner C1 produced in Example 1, the dotted line portion in FIG. 1 corresponds to the "portion where the polyester resin on the toner surface is in contact with the surface of the printing medium (PET-coated paper)," and the total length of the dotted line portion was determined as (A). On the other hand, the total length of the dashed line portion in FIG. 1 corresponds to the total length of the "portion where the toner is in contact with the surface of the printing medium (PET-coated paper)," and this was determined as (B). The procedure will be described in more detail below, but the techniques and devices are not limited to these, and any cross-section preparation method or microscope observation method that can obtain appropriate results for the purpose can be used.

[0250] The fixed image on the PET-coated paper was cut into pieces several millimeters square, and the PET-coated paper was thinned from the opposite side (non-printed side) with a razor to a degree that would not damage the fixed image. The thinned PET-coated paper pieces were attached with instant adhesive to a metal plate approximately 0.3 mm thick, with the fixed image side facing up. The metal plate with the attached PET-coated paper piece was fixed to the sample stage of a JEOL cross-section polisher SM-9010 so that the ion beam was irradiated from the metal plate side. At this time, the paper pieces protruding from the metal plate were cut off by cutting the razor blade from the fixed image side toward the metal plate side. The sample stage holding the metal plate was attached to the chamber of the cross-section polisher, and the metal plate was cut using an argon ion beam at an acceleration voltage of 4 kV and a current of approximately 100 μA for 3 hours. The processed sample piece was held on an SEM sample stage with the cut surface facing up, and the interface (contact surface) between the toner and the PET-coated paper on the cut surface was observed using a backscattered electron detector (JEM JSM-F100) manufactured by JEOL Ltd. at an acceleration voltage of 3 to 5 kV and a probe current of approximately 1 nA. 40 fields of view were photographed at 10,000 magnification. For each photographed image, the length of the portion of the polyester resin on the toner surface in contact with the PET-coated paper surface was measured, and the sum was designated A. The lengths of the portions of the toner and the PET-coated paper surface in the same image were also measured and the sum was designated B. The contact length ratio of the polyester resin on the toner surface to the PET-coated paper surface was calculated using the following formula. The results are shown in Table 4. (Ratio of the length of the polyester resin on the toner surface in contact with the PET-coated paper surface) = A / B. A cross-sectional SEM photograph of the fixed image of toner C1 produced in Example 1 is shown in Figure 1.

[0251] <Calculation of the ratio (X / Y) of the calculated value X of the coverage rate of the polyester resin on the toner surface to the measured value Y> The calculated value X of the coverage rate of the polyester resin on the toner surface was calculated by the method described above. The measured value Y was the A / B ratio expressed as a percentage. The results are shown in Table 5.

[0252] <Calculation of Average Thickness of Polyester Resin on Toner Surface> The thickness of the polyester resin on the toner surface was directly measured for each of the images captured above. In one field of view (one image), the length of the thickest point of each polyester resin portion in contact with the print medium was measured, and the average value was calculated. This was performed for 40 fields of view (40 images), and the average value of all measurements was taken as the average thickness of the polyester resin on the toner surface. The results are shown in Table 5.

[0253] <DSC Measurement> DSC measurement of the toner was carried out as follows. An AAQ20 instrument and an RCS90 cooling device (both manufactured by TA Instruments) were used. A TzeroStandard sample pan was used, and 3.0 mg of the measurement sample was weighed out. The measurement was carried out as follows: the temperature was adjusted to 20°C, and the temperature was first increased to 120°C at 10°C / min, held at 120°C for 5 minutes, and then decreased to 0°C at 10°C / min. After that, the temperature was held at 0°C for 5 minutes, and then increased to 120°C for a second time at 10°C / min. In this DSC measurement, the difference between the half width of the endothermic peak during the first temperature decrease and the half width of the exothermic peak during the first temperature increase [(first temperature decrease) - (first temperature increase)], and the difference between the half width of the endothermic peak during the first temperature decrease and the half width of the exothermic peak during the second temperature increase [(first temperature decrease) - (second temperature increase)] are shown in Table 4.

[0254] <Adhesion Evaluation (Scraping Test)> The obtained toner was applied to a PET-coated glossy recording paper (water-resistant paper Kareka, manufactured by Kokusai Pulp & Paper Co., Ltd.) in an amount of adhesion of approximately 0.8 mg / cm using two toner cartridges, using a commercially available printer equipped with a non-magnetic single-component developing rubber roller, a metal blade, and an organic photoreceptor charged by a charging roller (PCR), with the fixing unit removed, at a printing speed of 16 ppm. ２ The heat roll fixing machine had a roller diameter of 27 mm, a nip width of 9 mm, a fixing speed of 95 mm / sec, 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 temperature was set to 175°C, and the adhesion amount was about 0.8 mg / cm.２ A recording sheet bearing an unfixed toner image was transported to the fixing nip section, and a fixed image was obtained. An abrasion test was performed by abrading the fixed image with a vertically placed flathead screwdriver. The tip width of the flathead screwdriver was 1 mm, and a weight of 250 g was applied to the tip. The distance traveled was 2 cm, and the abrasion test was performed three times in total. The travel speed was approximately 1 cm / s, and the angle between the direction of travel and the tip of the flathead screwdriver was 90°. The degree of abrasion was visually observed and evaluated according to the following criteria. The evaluation results are shown in Table 4. (Evaluation Criteria) ⊚: No abrasion at all. ◯: Abrasion resulted in one or fewer small white dots. Δ: Abrasion resulted in a line less than 3 mm long, or multiple small white dots. ×: Abrasion resulted in a line 3 mm or longer.

[0255] <Evaluation of low-temperature fixability> The obtained toner was applied to a recording paper (OKI Excellent White (trade name)) at a printing speed of 16 ppm using a commercially available printer equipped with a non-magnetic one-component developing rubber roller, a metal blade, and an organic photoreceptor charged by a charging roller (PCR), with the fixing unit removed, at a toner adhesion amount of about 0.5 mg / cm ２ An unfixed toner image of 1000 ppm was printed on the sheet. 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), with no silicone oil applied. The roller surface temperatures were set to 145°C, 150°C, and 155°C, and the image was fixed at a fixing speed of 229 mm / sec at each temperature to prepare an evaluation sample. The evaluation criteria for the fixing test were as follows. The evaluation results are shown in Table 4. (Evaluation Criteria) ○: The fixed image did not offset, and no image defects occurred when rubbed. △: The fixed image did not offset, but image defects occurred when rubbed. ×: The fixed image offset.

[0256] <Storage Stability Evaluation> A metal cylinder with a diameter of 2 cm was placed upright on a metal plate, and wrapping paper was wrapped around the inside of the cylinder. 10 g of toner was gently poured into the vertically placed metal cylinder to fill it, and then a 20 g weight was placed on the toner. The metal cylinder, still on the metal plate, was placed in a thermo-hygrostat at 50°C and 55% relative humidity (normal humidity conditions) for 48 hours, or in a high-temperature, high-humidity chamber at 50°C and 80% relative humidity (high humidity conditions) for 24 hours. After removing the sample from the thermo-hygrostat, the metal cylinder and wrapping paper were gently removed, and the toner, which had solidified into a cylindrical shape, was removed while still in the vertical position. Loads were applied to the vertically placed, solidified toner in 10 g increments, and the load at which the cylindrical shape collapsed was measured. The load measurements were used to evaluate the toner according to the following criteria. The evaluation results are shown in Table 4. (Evaluation Criteria) ○: Collapsed under a load of 500 g or less. This means that the toner adhesion is weak and the storage stability is good. Δ: No collapse under a load of 500 g, but collapsed under a load of 1500 g or less. ×: No collapse under a load of 1500 g This means that the toner adhesion is strong and the storage stability is poor.

[0257]

[0258]

[0259]

[0260] <Discussion> From the above examples and comparative examples, it was found that the toner of the present invention has an improved particle-to-printing medium and particle-to-particle strength due to the placement of an appropriate amount of polyester resin on the particle surface, and as a result, has excellent adhesion to printing media such as PET-coated paper, low-temperature fixability, and does not cause deterioration of storage stability under high humidity conditions.

[0261] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese Patent Application No. 2022-055334, filed on March 30, 2022, and is incorporated by reference in its entirety.

Claims

1. A toner having at least a binder resin, The binder resin contains at least a polyester resin, the content of the polyester resin is 2.5% by mass or more based on the total mass of the toner, The toner was printed at a printing temperature of 175° C., a printing speed of 16 ppm, and a printing density of 0.8 mg / cm ２ In a printed matter obtained by fixing the toner to PET-coated paper under the printing conditions described above, when the total contact length between the polyester resin and the PET-coated paper in a cross section of the printed matter is A and the total contact length between the toner and the PET-coated paper is B, A and B satisfy the following formula (1): 0.05≦A / B≦0.55...(1)

2. The toner according to claim 1 , wherein the binder resin further comprises a styrene-acrylic resin.

3. 2. The toner according to claim 1, wherein the polyester resin is an amorphous polyester resin.

4. The toner according to claim 1 , wherein the content of the polyester resin is from 2.5% by mass to 40% by mass with respect to the total mass of the toner.

5. The toner of claim 1 further comprising a wax.

6. The toner according to claim 5 , wherein the content of the wax is from 5% by mass to 30% by mass with respect to the total mass of the toner.

7. The toner of claim 5, wherein the wax is a crystalline wax.

8. 8. The toner according to claim 7, wherein, in a differential scanning calorimetry (DSC) carried out with 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 difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the first temperature increase [(first temperature decrease)-(first temperature increase)] is 7.0° C. or less, and the difference between the half-width of the endothermic peak during the first temperature decrease and the half-width of the exothermic peak during the second temperature increase [(first temperature decrease)-(second temperature increase)] is 7.0° C. or less.

9. 2. The toner according to claim 1, wherein the polyester resin has an acid value of 5 mgKOH / g or more.

10. 2. The toner according to claim 1, wherein the polyester resin has a glass transition temperature (Tg) of 50° C. or more and 70° C. or less.

11. 2. The toner according to claim 1, which has a core-shell structure, the binder resin of the core being the styrene acrylic resin, and the binder resin of the shell being the polyester resin.

12. 2. The toner according to claim 1, wherein the volume median particle size is 6.5 μm or less, and the percentage by number of particles having a primary particle size of 1.0 μm or less is 3.0% or less.

13. The toner of claim 1 further comprising a colorant.

14. A toner cartridge comprising the toner according to any one of claims 1 to 13.

15. An image forming apparatus comprising the toner according to any one of claims 1 to 13.

16. A printed matter having a toner fixed on a print medium, the toner contains at least a binder resin, The binder resin contains at least a polyester resin, the content of the polyester resin is 2.5% by mass or more based on the total mass of the toner, The toner was printed at a printing temperature of 175° C., a printing speed of 16 ppm, and a printing density of 0.8 mg / cm ２ In a printed matter obtained by fixing the toner to PET-coated paper under the printing conditions above, when a total contact length between the polyester resin and the PET-coated paper in a cross section of the printed matter is A and a total contact length between the toner and the PET-coated paper is B, A and B satisfy the following formula (1): 0.05≦A / B≦0.55...(1)

17. The printed matter according to claim 16 , wherein the binder resin further comprises a styrene-acrylic resin.