Toner, toner cartridges, image forming apparatus, and printed materials

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

[Technical Field]

[0001] The present invention relates to a toner with excellent adhesion to printing media, low-temperature fixability, and storage stability, a toner cartridge containing this toner, an image forming apparatus, and printed materials using this toner. [Background technology]

[0002] Toner for developing electrostatic images is used in image forming devices such as printers, copiers, and facsimile machines to visualize electrostatic images. Taking electrophotographic image formation as an example, an electrostatic latent image is first formed on the photosensitive drum. Then, this electrostatic latent image is developed with toner, transferred to a printing medium such as transfer paper, and the toner is heated and fixed to form the image.

[0003] Toners for electrostatic image development typically consist of toner matrix particles containing a binder resin, colorant, wax, etc., to which solid fine particles such as silica are attached as an external additive. Styrene-acrylic resin is usually used as the binder resin for the toner matrix particles.

[0004] Such toners require excellent adhesion to printing media such as paper. In particular, in recent years, PET-coated paper is often used as a printing medium to improve the versatility, design, premium feel, and durability of printed materials. Therefore, excellent adhesion to PET-coated paper is required.

[0005] When forming an image on a printing medium, the toner is heated to fix it in place. Since the power required for this heating accounts for the majority of the power consumption of image forming equipment such as photocopiers, toners are required to have properties that allow them to fix at lower temperatures (low-temperature fixing properties).

[0006] Conventionally, a toner for electrostatic latent image development has been proposed that improves transferability, low-temperature fixability, and heat-resistant storage properties, comprising toner matrix particles having a core-shell structure and an external additive, wherein the toner matrix particles consist of core particles containing a vinyl resin and a shell that covers the surface of the core particles with a coverage rate in the range of 60 to 99%, the shell containing an amorphous polyester resin, and the external additive containing crosslinked vinyl resin particles, the crosslinked vinyl resin particles having a number-average particle size in the range of 30 to 300 nm (Patent Document 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2017-156543 [Overview of the project] [Problems that the invention aims to solve]

[0008] Conventional toners using styrene-acrylic resin as the binder resin for toner matrix particles have exhibited insufficient adhesion to printing 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 hard and brittle nature of styrene-acrylic resin, which results in poor adhesion at the interface between toner particles and the printing media.

[0009] The toner matrix particles described in Patent Document 1 have a core-shell structure in which the core particles are coated with a shell made of amorphous polyester resin, which improves adhesion to the printing medium to some extent, but has the following drawbacks. The high degree of shell coverage and the large amount of relatively expensive amorphous polyester resin result in high costs. Furthermore, because the surface has a more hydrophilic structure, the toner particles are more prone to absorbing moisture, resulting in poor storage stability, especially under high humidity conditions, and poor environmental stability.

[0010] The present invention aims to provide a toner that exhibits good adhesion to printing media, including good adhesion to PET coated paper, and also has excellent low-temperature fixing properties and storage stability, and can be manufactured at a relatively low cost; a toner cartridge containing this toner; an image forming apparatus; and printed materials using this toner. [Means for solving the problem]

[0011] The inventors have found that the above problem can be solved by using a predetermined amount of polyester resin as the binder resin for the toner, and by using a toner in which the ratio A / B of the total length A of the polyester resin and the printing medium in contact with the printing medium, evaluated by a specific method, is within a predetermined range. In other words, the gist of this invention is as follows:

[0012] [1] A toner having at least a binder resin, The binder resin comprises at least a polyester resin. The polyester resin content is 2.5% by mass or more relative to the total mass of the toner. The aforementioned toner was used at a printing temperature of 175°C, a printing speed of 16 ppm, and a print density of 0.8 mg / cm². 2 In a printed material obtained by fixing to PET coated paper under the printing conditions, when A is the total length of contact between the polyester resin and the PET coated paper in the cross-section of the printed material, and B is the total length of contact between the toner and the PET coated paper, the toner satisfies the following formula (1) for A and B. 0.05 ≤ A / B ≤ 0.55 ···(1)

[0013] [2] The toner according to [1], further comprising the binder resin, 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 based on the total mass of the toner.

[0016] [5] The toner according to any one of [1] to [4], further containing 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 based on the total mass of the toner.

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

[0019] [8] In differential scanning calorimetry (DSC) that includes a temperature program of heating from 40°C to 100°C or higher at a heating rate of 10°C / min (first heating), then cooling from 100°C or higher to 40°C or lower at a cooling rate of 10°C / min (first cooling), and subsequently heating to 100°C or higher at a heating rate of 10°C / min (second heating), the difference [(first cooling) - (first heating)] between the half-width of the endothermic peak during the first cooling and the half-width of the exothermic peak during the first heating is 7.0°C or less, and the difference [(first cooling) - (second heating)] between the half-width of the endothermic peak during the first cooling and the half-width of the exothermic peak during the second heating is 7.0°C or less. The toner according to [7].

[0020] [9] The toner according to any one of [1] to [8], wherein the acid value of the polyester resin is 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 more and 70°C or less.

[0022]

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

[10] , having a core-shell structure, wherein the binder resin of the core is the styrene-acrylic resin and the binder resin of the shell is the polyester resin.

[0023]

[12] A toner according to any of [1] to

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

[0024]

[13] Toners containing colorants as described in any of [1] to

[12] .

[0025]

[14] A toner cartridge containing the toner described in any of [1] to

[13] .

[0026]

[15] An image forming apparatus containing the toner described in any of [1] to

[13] .

[0027]

[16] A printed material having a toner fixative on a printing medium, The toner is a toner having at least a binder resin, The binder resin comprises at least a polyester resin. The polyester resin content is 2.5% by mass or more relative to the total mass of the toner. The aforementioned toner was used at a printing temperature of 175°C, a printing speed of 16 ppm, and a print density of 0.8 mg / cm². 2 In a printed material obtained by fixing to PET coated paper under the printing conditions, when the total length of contact between the polyester resin and the PET coated paper in the cross-section of the printed material is A, and the total length of contact between the toner and the PET coated paper is B, the printed material satisfies the following formula (1) when A and B. 0.05 ≤ A / B ≤ 0.55 ···(1)

[0028]

[17] The printed material according to

[16] , further comprising the binder resin, styrene acrylic resin. [Effects of the Invention]

[0029] The present invention provides a toner that exhibits good adhesion to printing media, good adhesion to PET coated paper, and excellent low-temperature fixing properties and storage stability, as well as a toner cartridge containing this toner, an image forming apparatus, and a printed material using this toner. [Brief explanation of the drawing]

[0030] [Figure 1] This is a cross-sectional SEM image of the fixed toner C1 manufactured in Example 1. [Modes for carrying out the invention]

[0031] The embodiments for carrying out the present invention (hereinafter referred to as embodiments of the invention) will be described in detail below. The present invention is not limited to the following embodiments, and can be implemented in various ways within the scope of its gist.

[0032] In this specification, when we use the expression "x~y" (where x and y are any numbers), unless otherwise specified, it means "greater than or equal to x and less than or equal to y," and also includes the meanings of "preferably greater than x" or "preferably less than y." Furthermore, when we use expressions like "greater than or equal to x" (where x is any number) or "less than or equal to y" (where y is any number), we also imply that "greater than x is preferable" or "less than y is preferable."

[0033] [toner] The toner according to an embodiment of the present invention (referred to as "this toner") is a toner having at least a binder resin, wherein the binder resin contains at least a polyester resin, and the polyester resin content is 2.5% by mass or more of the total mass of the toner, and the toner is used at a printing temperature of 175°C, a printing speed of 16 ppm (Paper Per Minute), and a printing density of 0.8 mg / cm². 2In a printed material obtained by fixing to PET coated paper under the printing conditions, when the total length of contact between the polyester resin and the PET coated paper in the cross-section of the printed material is A, and the total length of contact between the toner and the PET coated paper is B, the ratio of A to B, A / B (hereinafter referred to as the "A / B ratio"), satisfies the following formula (1). 0.05 ≤ A / B ≤ 0.55 ···(1)

[0034] This toner contains a binder resin, the binder resin comprising at least a polyester resin. Preferably, the binder resin further comprises a styrene-acrylic resin. Furthermore, it is preferable that this toner comprises toner matrix particles (referred to as "this toner matrix particles") which optionally further contain a colorant, a charge control agent, and other components, and an external additive. However, this toner is not necessarily limited to the above configuration. For example, it does not need to contain a colorant (clear toner), nor does it need to contain an antistatic agent or external additives.

[0035] The A / B ratio of this toner is characterized by satisfying the above formula (1). The fact that this A / B ratio satisfies formula (1) indicates that the amount of polyester resin present on the surface of this toner is appropriate. It also indicates that this toner preferably has a core-shell structure, with the binder resin of the core preferably being styrene-acrylic resin and the binder resin of the shell being polyester resin. This toner has an A / B ratio of 0.05 or higher, and the polyester resin present on the surface of the toner particles provides excellent adhesion to the printing medium. In particular, the presence of polyester resin with the same ester structure on the surface of the toner particles significantly improves adhesion to PET coated paper, increasing the fixing strength. Furthermore, the presence of polyester resin on the surface of the toner particles increases the viscosity of the contact surfaces between polyester resins at the toner particle / toner particle interface due to its hydrogen bonding properties, which also improves 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, results in good storage stability for this toner. Furthermore, it helps to minimize the cost increase associated with using relatively expensive polyester resin.

[0036] The A / B ratio can be calculated as follows: Toner was used at a printing temperature of 175°C, a printing speed of 16 ppm (Paper Per Minute), and a print density of 0.8 mg / cm². 2 The printed material was prepared by fixing the material onto PET-coated paper under the specified printing conditions, and the cross-section of the PET-coated paper was observed at 10,000x magnification using a backscattered electron detector of a scanning electron microscope (SEM). The observation procedure described above is repeated for a sufficient number of different fields of view, and observation images are taken. At this time, a sufficient number of fields of view can be considered to be 30 or more. In the embodiment described later, observations were performed for each of 40 fields of view. For each captured image, determine the length of the portion where the polyester resin on the toner surface is in contact with the printing medium surface. The sum of these lengths (A) is then divided by the sum of the lengths of the portions where the toner and the printing medium surface are in contact (B) for each image to obtain the value (A / B). Even if there are areas in the observed cross-section where the toner has peeled away from the fixing surface, it is considered to be in contact and its length is measured.

[0037] The above (A) and (B) will be explained in more detail with reference to Figure 1. In Figure 1, the SEM image shows that each component in the toner appears with different contrasts due to atomic number, density difference, and edge effect. In Figure 1, the continuous layer represents styrene-acrylic resin. Among the discontinuous layers, the low-contrast portion located at the outer interface of the toner particles represents polyester resin. The highest-contrast portion located inside the toner particles represents wax. The low-contrast portion finely dispersed inside the toner particles represents the colorant. The fine particulate low-contrast portion on the outermost edge of the toner represents the inorganic external additive. Therefore, the area indicated by the dotted line in Figure 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 area corresponds to (A) above. On the other hand, the total length of the dashed lines in Figure 1 corresponds to the total length of the "area where the toner and the surface of the printing medium (PET coated paper) are in contact." This corresponds to (B) above.

[0038] The toner in Figure 1 is a core-shell structure toner in which the core component is styrene-acrylic resin and the shell component is polyester resin. In the present invention, "core-shell structure" refers to a structure in which the surface of a core component is covered by a shell component. However, it is not limited to a structure in which the core component is completely covered by the shell component. As shown in Figure 1, the surface of the core component may be partially exposed and the shell component may be discontinuous.

[0039] The A / B ratio obtained as described above can be considered, based on the following reasoning, as the ratio of the area in contact between the polyester resin on the toner surface and the PET coated paper surface, or in other words, the proportion of polyester resin present on the surface of this toner. In printed materials with fixed toner, the orientation of each fixed toner particle is considered to be random. Therefore, even when observing a cross-section of the printed material in one direction, the orientation (orientation state) and position of each toner particle will differ. Thus, by observing a sufficient number of fields of view for a cross-section in one direction, it can be considered that a sufficient number of directions and positions have been observed. Consequently, by adding up a sufficient number of length information obtained from each field of view, this can be considered as an area obtained by integration, and as mentioned above, it can be considered as an area ratio. The procedure will be described in more detail in the examples below, but the methods and apparatus are not limited to those described, and any cross-sectional preparation method or microscopic observation method that yields appropriate results for the purpose can be used.

[0040] From the viewpoint of improving adhesion and fixation to the printing medium and storage stability, the A / B ratio of this toner is preferably 0.05 or higher, more preferably 0.10 or higher, even more preferably 0.20 or higher, and particularly preferably 0.30 or higher. On the other hand, it is preferably 0.55 or lower, more preferably 0.50 or lower, even more preferably 0.45 or lower, and particularly preferably 0.40 or lower.

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

[0042] <Ratio (X / Y) of calculated and measured polyester resin coverage on the toner surface (X / Y)> In this toner, the ratio (X / Y) of the calculated value X to the measured value Y of the polyester resin coating rate on the toner surface is preferably 1.5 or higher. Among these, 2.0 or higher is more preferable, 2.25 or higher is even more preferable, 2.5 or higher is even more preferable, and 3.0 or higher is particularly preferable. On the other hand, this ratio is preferably 20.0 or lower, more preferably 10.0 or lower, even more preferably 5.0 or lower, and particularly preferable 3.9 or lower. A larger ratio indicates a greater thickness of 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 fine particles or a thin film. Furthermore, the layer may cover the toner surface continuously or discontinuously. In this invention, from the viewpoint of satisfying the A / B ratio, it is preferable that the layer covers the toner surface discontinuously. The calculated value X and the measured value Y of the polyester resin coverage rate on the toner surface can be determined by the following methods.

[0043] <Method for calculating the calculated value X of the polyester resin coating rate on the toner surface> The theoretical coverage rate is defined as the coverage rate of polyester resin particles on the surface of toner particles when polyester resin particles are uniformly dispersed and attached to the surface of toner particles, and this theoretical coverage rate is equivalent to the calculated value X.

[0044] In the following explanation, we will use the example where the toner matrix particles have a core-shell structure, the core binder resin is styrene-acrylic resin, and the shell binder resin is polyester resin. Theoretical coverage is defined as the coverage rate of shell particles on the core particle surface when shell particles are uniformly dispersed and attached to the core particle surface one particle at a time. This theoretical coverage rate is equivalent to the calculated value X below. The calculated value X is defined as shown in equation (2) below. Note that the core particle and shell particle are assumed to be perfect spheres. X = {(Number of shells per core particle) × (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 filling ratio. Furthermore, the mass of each individual core particle and shell particle can be calculated as follows. {(π / 6) × (particle diameter)} 3 ×Specific gravity The specific gravity can be calculated as, for example, 1.0 for styrene-acrylic resin and 1.1 for polyester resin. Here, let S be the mass of one core particle and s be the mass of one shell particle. Also, if K is the number of core particles and k is the number of shell particles, then when S × K = A, then s × k = (1 - A) holds true. 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 ​​one shell particle and the surface area of ​​one core particle) Assuming that the shell particles are perfect spheres, the area occupied by one shell 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 equivalent to the area of ​​a two-dimensional circle with the same diameter as the sphere. Therefore, the projected area of ​​one shell particle can be determined by the following equation (3). (Projected area of ​​one shell particle) = {(Diameter of the shell particle) / 2} 2 ×π···(3) Furthermore, assuming 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, following equation (4) below. (Surface area of ​​one core particle) = 4 × {(Diameter of core particle) / 2} 2 ×π···(4)

[0047] As described above, the number of shells per core particle, the projected area of ​​one shell particle, and the surface area of ​​one core particle can be determined and substituted into equation (2) to obtain the calculated value X, i.e., the theoretical coverage.

[0048] <Method for measuring the actual value Y of the polyester resin coating rate on the toner surface> Any method may be used to measure the measured value Y. For example, the aforementioned A / B ratio can be used as the measured value Y. Alternatively, the toner particles can be identified by staining them with ruthenium and analyzing the images obtained using a scanning electron microscope. The ease with which ruthenium stains the toner particles varies depending on the type of resin. For example, the rate at which ruthenium staining progresses differs significantly between polyester resin and styrene-acrylic resin. As a result, in the backscattered electron image of the obtained toner particle surface, a difference in brightness occurs between the surface formed by polyester resin and the surface formed by styrene-acrylic resin, making it possible to distinguish between the polyester resin surface and the styrene-acrylic resin surface.

[0049] <Average thickness of polyester resin on the toner surface> In this toner, the average thickness of the polyester resin on the toner surface is preferably 0.20 μm or more. More preferably 0.23 μm or more, even more preferably 0.25 μm or more, particularly preferably 0.28 μm or more, and especially preferably 0.30 μm or more. 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 the 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 from the cross-sectional SEM image of the printed material mentioned above. In this case, a field of view of 30 points or more can be considered sufficient. In the example described later, observations were performed for each of the 40 field of view points. Furthermore, it is also possible to calculate the average thickness of the polyester resin coating on the toner surface from the ratio (X / Y) of the calculated value X and the measured value Y. If the polyester resin adheres to the toner surface as single particles without aggregation, the average thickness of the polyester resin can be considered to be equal to the average particle size of the polyester resin latex. Since (X / Y) can be considered to represent the deviation from this theoretical value, the average thickness can be calculated using the following formula (5). (Average thickness of polyester resin on the toner surface) = (Average particle size of latex in polyester resin) × (X / Y) ... (5)

[0051] <Difference in the full width at half maximum of the heat peak> The toner preferably contains a wax described later, particularly a crystalline wax, and in differential scanning calorimetry (DSC) that performs a temperature program including the steps of raising the temperature 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 lowering the temperature to 40°C or lower at a cooling rate of 10°C / min (first cooling), and then raising the temperature to 100°C or higher, for example 40 to 130°C, at a heating rate of 10°C / min (second heating), it is preferable that the difference between the full width at half maximum of the endothermic peak during the first cooling and the full width at half maximum of the exothermic peak during the first heating [(first cooling) - (first heating)] is 7.0°C or less, and that the difference between the full width at half maximum of the endothermic peak during the first cooling and the full width at half maximum of the exothermic peak during the second heating [(first cooling) - (second heating)] is 7.0°C or less.

[0052] The difference between the full width at half maximum (FWHM) of the endothermic peak during cooling and the exothermic peak during heating indicates the degree of sharp meltability of the wax in the toner. Here, sharp melt refers to the rapid change from solid to liquid when the wax in the toner reaches its melting point. The wax in the toner provides the effect of a mold release agent by changing from solid to liquid upon heating and migrating to the toner surface. Therefore, in order to achieve low-temperature fixation, the wax in the toner must be highly sharp meltable, meaning that the entire amount becomes liquid in the extremely short time (about 1 second) it passes through the fuser of the image forming apparatus. When the wax has high sharp meltability, that is, changes instantaneously from solid to liquid, the endothermic peak during heating and the exothermic peak during cooling become sharp, and the difference between the FWHM of the endothermic peak during cooling and the FWHM of the exothermic peak during heating becomes small.

[0053] For these reasons, it is preferable that the toner has a difference of 7.0°C or less between the full width at half maximum (FMAX) of the endothermic peak during the first cooling cycle and the full width at half maximum (FMAX) of the exothermic peak during the second heating cycle. In addition, it is more preferable that the difference of 7.0°C or less between the full width at half maximum (FMAX) of the endothermic peak during the first cooling cycle and the full width at half maximum (FMAX) of the exothermic peak during the first heating cycle. In other words, it is preferable that both the difference of 7.0°C or less between the full width at half maximum (FMAX) of the endothermic peak during the first cooling cycle and the full width at half maximum (FMAX) of the exothermic peak during the first heating cycle and the difference of 7.0°C or less between the full width at half maximum (FMAX) of the endothermic peak during the first cooling cycle and the full width at half maximum (FMAX) of the exothermic peak during the second heating cycle. In other words, it is preferable that the sharp meltability of the wax in the toner is equally high during the first and second heating cycles.

[0054] If the difference between the full width at half maximum of the endothermic peak during the first cooling cycle and the full width at half maximum of the exothermic peak during the first heating cycle [(first cooling cycle) - (first heating cycle)] is 7.0°C or less, the wax has sufficiently high sharp melt properties and the toner has excellent low-temperature fixation properties. Therefore, in this 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 full width at half maximum of the endothermic peak during the first cooling cycle and the full width at half maximum of the exothermic peak during the second heating cycle [(first cooling cycle) - (second heating cycle)] is 7.0°C or less, the wax has sufficiently high crystallinity and the toner has excellent storage stability. Therefore, in this 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), if the peak has not converged (is in the middle of the peak slope) at at least 40°C or 100°C, it shall be handled as follows. After identifying endothermic or exothermic peaks based on a baseline, including ranges below 40°C and above 100°C, the full width at half maximum (FWHM) of the peak itself is adopted. In other words, the temperature range for which the FWHM value is calculated may include ranges below 40°C and above 100°C.

[0057] The specific means by which this toner satisfies the aforementioned physical properties are not limited. In particular, as will be described later, the properties can be more favorably achieved by selecting the compounds used as wax, optimizing their content ratio, and, when multiple waxes are used in combination, by optimizing their combination and blending ratio. If the wax is a mixture or contains impurities or by-products, the properties can also be achieved by optimizing its purity. Furthermore, this can also be suitably achieved by selecting and combining the binder resin and wax as described later.

[0058] In this invention, when performing differential scanning calorimetry (DSC) of toner, the first heating, first cooling, and second heating 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 amount of heat absorbed, the amount of heat released, and the full width at half maximum of the endothermic and exothermic peaks all depend heavily on the heating rate or cooling rate. Therefore, for example, measurements taken at a rate of 5°C / min or 15°C / min will yield significantly different values ​​than measurements taken at a rate of 10°C / min.

[0059] <Main toner particles> The toner matrix particles may be a single-layer structure or a multilayer structure (core-shell structure) comprising a core and an outer layer (also called a "shell"), but a core-shell structure is preferred in order to satisfy the aforementioned A / B ratio. The binder resin of the core is preferably styrene-acrylic resin. The binder resin of the shell is preferably polyester resin. Furthermore, it is more preferable that the binder resin of the core is styrene-acrylic resin and the binder resin of the shell is polyester resin.

[0060] In the present invention, "core-shell structure" refers to a structure in which the surface of a core component is covered by a shell component. However, it is not limited to a structure in which the core component is completely covered by the shell component. The surface of the core component may be partially exposed, or a portion may be dispersed within the shell component.

[0061] In any of the toner matrix particle preparation methods described later, the shell component refers to the component that is unevenly distributed on the surface of the toner matrix particle. The shape of the shell component when it becomes toner may be fine particles or thin films, and it may cover the core component continuously or discontinuously. In the present invention, from the viewpoint of satisfying the A / B ratio, it is preferable that the shell component covers the core component discontinuously.

[0062] When preparing toner matrix particles in a wet medium with an aqueous and / or organic solvent as the continuous phase, there are two methods: one involves adding shell microparticles simultaneously with the core component and thermodynamically positioning the shell microparticles at the interface between the core component and the wet medium (a method for controlling polarity); the other involves adding the shell microparticles after the core component and physically positioning them on the surface of the core component. Furthermore, a combination of these two methods can be used.

[0063] When adding shell particles after the core components, one possible method is to add them after the composition and / or shape of the core components has been determined (the shape, physical properties, and compatibility of the core components may change due to subsequent heating, aging, stirring, etc.).

[0064] When the toner matrix particles are a multilayer structure comprising a core and a shell, the core preferably contains a binder resin and, optionally, a colorant and wax, and further preferably, a charge control agent and other components. The shell preferably uses a binder resin alone, but may optionally contain a colorant and wax, and may further contain a charge control agent and other components.

[0065] Based on the above, it is preferable that the toner matrix particles have a core-shell structure, with the core binder being styrene-acrylic resin and the shell binder being polyester resin. To achieve such a structure, the toner composition can be, for example, as follows. 1) The content of styrene acrylic segments in the polyester resin of the shell is below a certain value. 2) The polyester segment content in the styrene-acrylic resin of the core is below a certain value. 3) The ratio of the acid values ​​of the styrene-acrylic resin in the core to the polyester resin in the shell ([acid value of the styrene-acrylic resin in the core] / [acid value of the polyester resin in the shell]) is between 0.85 and 2.9.

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

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

[0068] Methods for polymerizing polyester segments into styrene-acrylic resin include, for example, the following, but any method is acceptable. 2-1) A method of reacting both reactive monomers with a polyester polymerization segment to react with a styrene-acrylic raw material monomer. 2-2) A method for reacting polycarboxylic acid monomers and polyhydric alcohol monomers with styrene-acrylic resin by reacting both reactive monomers. 2-3) A method of chemically bonding styrene-acrylic resin and polyester resin by reacting them with monomers of both reactivity.

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

[0070] When the toner matrix particles have a core-shell structure, it is preferable that the binder resin of the shell has a storage modulus of elasticity (G'(70°C)) at 70°C measured by a rheometer (hereinafter sometimes simply referred to as "G'(70°C)") of 500,000 Pa or more. Superior storage stability can be obtained by having a G'(70°C) of 500,000 Pa or higher for the shell binder resin. From the viewpoint of storage stability, it is more preferable that the G'(70°C) of the shell binder resin be 700,000 Pa or higher, and even more preferable that it be 1,000,000 Pa or higher. On the other hand, from the viewpoint of low-temperature fixing properties, it is preferable that the G'(70°C) of the shell binder resin be 5,000,000 Pa or lower, and more preferably 3,000,000 Pa or lower.

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

[0072] As described above, in the present invention, the binding resin of the shell is preferably made of 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 opposing physical properties as G'(70°C) and G'(100°C), one method is to use a polyester resin that satisfies both G'(70°C) and G'(100°C) on its own as the binder resin for the shell, or to mix a polyester resin that satisfies only G'(70°C) with a polyester resin that satisfies only G'(100°C) 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) values ​​of the binder resin can be measured by dynamic viscoelasticity measurement. For example, a sample obtained by vacuum drying a polyester dispersion can be used as a sample for dynamic viscoelasticity measurements. For dynamic viscoelasticity measurements, for example, a rheometer ARES manufactured by TA Instruments can be used. For example, the measurement can be performed using the following procedure. Approximately 1.3g of the sample is placed in a jig designed for a 25mm diameter, and pressed with a 30kg load for 10 minutes using a press heated to 50°C to form a pellet. The resulting pellet is then placed in a measuring device equipped with a 25mm diameter circular parallel plate, and the upper plate is lowered while the device is heated to 120°C to adjust the pellet thickness to 3.0-3.5mm. Subsequently, the temperature was lowered, and measurements were taken 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 modulus 1.0E+08 Pa), final temperature 150°C, heating 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 styrene monomers and (meth)acrylic acid ester monomers. Preferably, the copolymer is formed using (meth)acrylic acid monomers in addition to styrene monomers and (meth)acrylic acid ester monomers.

[0076] Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene, and dichlorostyrene. These can be used individually or in combination of two or more. Among these, styrene and p-methylstyrene are preferred from the viewpoint of reactivity, ease of polymerization, and cost, with styrene being 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, β-hydroxyacrylate, γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. These can be used individually or in combination of two or more. Among these, propyl acrylate, n-butyl acrylate, isobutyl acrylate, and 2-ethylhexyl acrylate are preferred from the viewpoint of toner fixation, non-offset properties, and cost, with n-butyl acrylate and 2-ethylhexyl acrylate being more preferred, and n-butyl acrylate being even more preferred.

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

[0079] From the viewpoint of toner storage stability, 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. On the other hand, from the viewpoint of toner fixation, it is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. From the viewpoint of toner fixation, the proportion of (meth)acrylic acid ester 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. On the other hand, 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. From the viewpoint of toner developability, 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. On the other hand, from the viewpoint of toner environmental stability, it 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 styrene monomers and (meth)acrylic acid ester monomers constituting the styrene-acrylic resin is preferably 0.18 or more, more preferably 0.25 or more, with 0.67 or less and more preferably 0.54 or less relative to the styrene monomer. In particular, by setting the ratio in the range of 0.49 to 0.54, excellent low-temperature fixation can be achieved while maintaining storage stability at a level suitable for practical use. The content ratio of styrene monomers and (meth)acrylic acid monomers constituting the styrene-acrylic resin is preferably 0.005 or more, more preferably 0.006 or more, with respect to the styrene monomer, while preferably 0.035 or less, and more preferably 0.030 or less.

[0081] Furthermore, other polyfunctional monomers can be used to create a crosslinked structure in the styrene-acrylic resin. Examples of other polyfunctional monomers include hexanediol diacrylate, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, 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-based mass-average molecular weight (Mw) of 30,000 to 150,000, as measured by gel permeation chromatography (GPC). A styrene-acrylic resin with a mass-average molecular weight (Mw) of 30,000 or more provides sufficient heat resistance for storage. A styrene-acrylic resin with a weight-average molecular weight (Mw) of 150,000 or less provides sufficient low-temperature fixation. The method for measuring the mass-average molecular weight (Mw) of styrene-acrylic resin is as described in the Examples section below.

[0083] Styrene acrylic resin may be used alone, or two or more types with different monomer compositions and physical properties may be used in combination.

[0084] The styrene-acrylic resin content in this toner is preferably 60-85% by mass, and more preferably 65-80% by mass, relative to the total mass (100% by mass) of the toner, from the viewpoint of reducing toner costs, environmental stability, fixability, and storage stability. If the styrene-acrylic resin content is above the lower limit, there are significant cost advantages, and environmental stability and storage stability under high humidity conditions are maintained. If the styrene-acrylic resin content is below the upper limit, the polyester resin content on the surface becomes sufficient, resulting in improved adhesion to the medium, which is preferable.

[0085] <Polyester resin> The polyester resin (sometimes abbreviated as "PES") used as the binder resin for this toner is preferably an amorphous polyester resin from the viewpoint of fixation, storage stability, and adhesion to the medium.

[0086] Amorphous polyester resin refers to a polyester resin that exhibits amorphous properties in its endothermic curve obtained by differential scanning calorimetry (DSC), where it has a glass transition temperature (Tg) but lacks a clear endothermic peak at the melting point, i.e., at the temperature increase.

[0087] Amorphous polyester resins are obtained by polycondensation reactions using polycarboxylic acid monomers (derivatives) and polyhydric alcohol monomers (derivatives) as raw materials in the presence of a suitable polymerization catalyst. Examples of polycarboxylic acid monomer derivatives include alkyl esters, acid anhydrides, and acid chlorides of polycarboxylic acid monomers. Examples of polyhydric alcohol monomer derivatives include esters and hydroxycarboxylic acids of polyhydric alcohol monomers.

[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, mucoic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, and p-carboxyphenyl Examples include divalent carboxylic acids such as acetic acid, p-phenylenediacetic 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, anthracenedicarboxylic acid, and dodecenylsuccinic acid; and trivalent carboxylic acids such as trimellitic acid, pyromellitic acid, naphthalentricarboxylic acid, naphthalenetetracarboxylic acid, pyrentricarboxylic acid, and pyrenetetracarboxylic acid. These can be used individually or in combination of two or more. Among these, maleic acid, adipic acid, fumaric acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, isophthalic acid, and terephthalic acid are preferred as divalent carboxylic acids from the viewpoint of toner storage stability, handling, cost, and supply volume, adipic acid, isophthalic acid, and terephthalic acid are more preferred, and isophthalic acid and terephthalic acid are even more preferred. As for trivalent carboxylic acids, trimellitic acid and pyromellitic acid are preferred from the viewpoint of ease of adjusting the polymerization rate, with trimellitic acid being more preferred.

[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, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A; and trihydric or higher polyols such as glycerin, pentaerythritol, trimethylolpropane, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine. These can be used individually or in combination of two or more. Among these, as dihydric alcohols, ethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A are preferred from the viewpoint of reducing the coloration of the resin, ease of obtaining raw materials, and electrostatic properties; ethylene glycol, ethylene oxide adduct of bisphenol A, and propylene oxide adduct of bisphenol A are more preferred; and ethylene glycol and propylene oxide adduct of bisphenol A are even more preferred. As for polyols with a valentity of 3 or higher, glycerin, pentaerythritol, and trimethylolpropane are preferred from the viewpoint of ease of adjusting the polymerization rate, with trimethylolpropane being more preferred.

[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 within the range of 1.5 / 1 to 1 / 1.5.

[0091] The acid value of the polyester resin is preferably 5 mg KOH / g or higher. If the acid value of the polyester resin is above the lower limit mentioned above, sufficient stability can be obtained for use as a polyester dispersion in the agglomeration process when creating toner matrix particles. On the other hand, it is preferable that the acid value of the polyester resin be 20 mgKOH / g or less from the viewpoint of ease of creating particles having polyester on the surface. The acid value of the polyester resin is more preferably 8 mg KOH / g or more, even more preferably 10 mg KOH / g or more, more preferably 18 mg KOH / g or less, and even more preferably 15 mg KOH / 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 does not deteriorate, and the surface of the particles is easily covered uniformly during the maturation process when creating the toner matrix particles. The glass transition temperature of the polyester resin is more preferably 53°C or higher, even more preferably 55°C or higher, 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 within the range of 90 to 150°C. If the softening temperature of the polyester resin is above the lower limit, the storage stability of the toner is maintained. If the softening temperature of the polyester resin is below the upper limit, the low-temperature fixability of the toner does not deteriorate. 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 mass-average molecular weight (Mw) of 20,000 or more on a polystyrene basis, measured by gel permeation chromatography (GPC), more preferably 25,000 or more, while it is preferably 150,000 or less, more preferably 100,000 or less, and even more preferably 80,000 or less. The method for measuring the mass-average molecular weight (Mw) of the polyester resin is as described in the Examples section below.

[0095] This toner may contain only one type of polyester resin, or it may contain two or more types with different monomer compositions and physical properties.

[0096] The polyester resin is contained in an amount of 2.5% by mass or more relative to the total mass of the toner, but it is preferable that it is contained in a proportion of 2.5 to 40% by mass in order to satisfy the aforementioned A / B ratio. The proportion of 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, even more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0097] <Coloring agent> Any known colorants can be used as the colorants in this toner. Specific examples of colorants include carbon black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow, rhodamine-based dyes and pigments, chrome yellow, quinacridone-based dyes, benzidine yellow, rose bengal, triallylmethane-based dyes, monoazo-based dyes, disazo-based dyes and pigments, etc. Any known dyes and pigments can be used individually or in mixtures.

[0098] In the case of full-color toner, it is preferable to use monoazo, disazo, polyazo, or condensed azo dyes for yellow; quinacridone and / or monoazo dyes for magenta; phthalocyanine dyes for cyan; and carbon black for black. Preferably, the toner set combination includes a magenta toner containing a quinacridone-based dye and / or a monoazo-based dye, a black toner containing carbon black, a cyan toner containing a copper phthalocyanine-based dye, and a yellow toner containing at least one dye selected from monoazo, disazo, and condensed azo dyes.

[0099] Specifically, examples of cyan include CI Pigment Blue 15:3 and CI Pigment Blue 15:4. Examples of yellow include CI Pigment Yellow 74, the disazo-based CI Pigment Yellow 83, the condensed azo-based CI Pigment Yellow 93, CI Pigment Yellow 155, CI Pigment Yellow 180, and CI Pigment Yellow 185. Examples of magenta include CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 5, the quinacridone-based CI Pigment Red 122 and CI Pigment Red 209, and the monoazo-based CI Pigment Red 269 (238).

[0100] The coloring agent is preferably used in a ratio of 3 to 20% by mass relative to the total mass (100% by mass) of the toner.

[0101] <wax> This toner may further contain wax. The inclusion of wax can improve low-temperature fixation and high-temperature offset properties. The wax may be contained in the toner in any form. For example, some or all of the binder resin and wax may be miscible, the core may be separated and encapsulated as domains, the shell may be separated and encapsulated as domains, or the wax may be present separately on the surface of the toner.

[0102] By including wax, especially crystalline wax, the wax melts instantly when heat is applied to the toner, improving its adhesion to the printing medium. Furthermore, if the wax is encapsulated within the core as separate domains, it does not plasticize the toner, thus maintaining retention stability. Specifically, if the wax is a crystalline wax with a more distinct melting point compared to ordinary wax, its compatibility with the binder resin decreases, resulting in a structure where the wax and the binder resin of the core are completely separated. This makes it less likely to plasticize the resin, thus maintaining storage stability.

[0103] The type of wax contained in this toner is not limited. In particular, it is preferable that it contains an ester-based wax, and more preferably a crystalline wax as described later.

[0104] Examples of ester waxes include ester waxes having long-chain aliphatic groups such as behenyl behenate, stearyl behenate, montanate ester, stearyl stearate, and erythritol tetrabehenate. Among these, monoester waxes mainly containing C18 and / or C22 hydrocarbons are more preferred, and among these, behenyl behenate, stearyl behenate, behenyl stearate, and those mainly containing these are particularly preferred from the viewpoint of low dust and low-temperature fixing.

[0105] From the viewpoint of low dust, the number of carbon atoms in one molecule of ester wax is preferably 36 or more, and more preferably 40 or more. On the other hand, from the viewpoint of low-temperature fixing, the number of carbon atoms in one molecule of 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 suitable for use in this toner has a melting point peak (endothermic peak top during the second DSC heating of the toner) of 90°C or lower, more preferably 85°C or lower, even more preferably 80°C or lower, preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 65°C or higher. If the melting point peak temperature of the wax is too low, the blocking resistance tends to deteriorate. If the melting point peak temperature of the wax is too high, the low-temperature fixation and high gloss tend to be impaired. The difference between the melting point peak of the wax and the onset temperature of the wax (the temperature at which the tangent line intersects at the first inflection point appearing before the endothermic peak in the second DSC of the toner) is preferably 15°C or less, and more preferably 10°C or less.

[0107] (Other waxes) This toner may contain other waxes in addition to the ester-based waxes mentioned above, or other waxes may be used in combination with the ester-based waxes mentioned above. Other waxes include, for example, olefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and copolymerized polyethylene; paraffin wax; plant-based waxes such as hydrogenated castor oil and carnauba wax; ketones having long-chain alkyl groups such as distearyl ketone; alkyl-containing silicones; higher fatty acids such as stearic acid; higher fatty acid amides such as oleic acid amide and stearic acid amide; and the like. Preferably, hydrocarbon waxes such as paraffin wax and Fischer-Tropsch wax; silicone waxes; and the like.

[0108] (Amount of wax) The amount of wax contained in this toner is preferably 5 to 30% by mass, and more preferably 10 to 20% by mass, relative to 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 preferably 80% by mass or less.

[0109] <Static control agent> This toner may contain a charge control agent to improve the toner's charge characteristics. Any known charge control agent can be used. Specific examples of charge control agents include, for positive charge properties, nigrosine dyes, amino group-containing vinyl copolymers, quaternary ammonium salt compounds, and polyamine resins. For negative charge properties, examples include metal-containing azo dyes containing metals such as chromium, zinc, iron, cobalt, and aluminum, salts of salicylic acid or alkyl salicylic acid with the aforementioned metals, and metal complexes.

[0110] The amount of the charge control agent is preferably 0.1 to 25% by mass, and more preferably 1 to 15% by mass, relative to the total mass (100% by mass) of the toner. The charge control agent may be mixed inside the toner matrix particles, or it may be used in a form attached to the surface of the toner matrix particles.

[0111] <External additives> This toner typically contains an external additive to improve toner fluidity and charge control. The external additive is usually attached to the surface of the toner matrix particles, but the degree to which the external additive is embedded in the matrix particles can be in any state. That is, some or all of the external additive may be attached to the matrix particle surface in a point contact manner, or it may be embedded, and some or all of the external additive may be dispersed on the matrix particle surface, or it may be aggregated. The particle size of the external additive particles should preferably be in the range of 0.1% to 5% of the average particle size of the toner matrix particles, where (particle size of external additive particles) / (average particle size of toner matrix particles) is within that range.

[0112] As external additives, various inorganic or organic fine particles can be appropriately selected and used. Two or more external additives may be used in combination.

[0113] As inorganic fine particles, 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 can be used; various nitrides such as boron nitride, titanium nitride, and zirconium nitride; various borides such as zirconium boride; various oxides such as titanium oxide, calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, cerium oxide, silica, and colloidal silica; various titanate compounds such as calcium titanate, magnesium titanate, and strontium titanate; phosphate compounds such as calcium phosphate; sulfides such as molybdenum disulfide; fluorides such as magnesium fluoride and carbon fluoride; various metal soaps such as aluminum stearate, calcium stearate, zinc stearate, and magnesium stearate; talc, bentonite, various carbon blacks and conductive carbon blacks, magnetite, ferrite, etc. can be used.

[0114] As organic microparticles, microparticles of styrene resins, acrylic resins, epoxy resins, melamine resins, etc., can be used. Electrostatic stability can be improved by using microparticles containing fluorine atoms.

[0115] Among these external additives, silica, titanium dioxide, alumina, zinc oxide, various types of carbon black, and conductive carbon black are particularly suitable for use.

[0116] External additives may also be used in which the surface of the inorganic or organic fine particles has been treated with a treatment agent such as hydrophobization, using a silane coupling agent such as hexamethyldisilazane (HMDS) or dimethyldichlorosilane (DMDS), a titanate coupling agent, a silicone oil treatment agent such as silicone oil, dimethyl silicone 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 be used in combination.

[0117] The amount of external additive added is preferably 1.0 part by mass or more, particularly preferably 1.5 parts by mass or more, preferably 6.5 parts by mass or less, and particularly preferably 5.5 parts by mass or less, per 100 parts by mass of the toner mother particles.

[0118] In this toner, conductive fine particles may be used as an external additive from the viewpoint of charge control. Examples of conductive fine particles include conductive titanium oxide, metal oxides such as silica and magnetite, or those doped with conductive substances; organic fine particles obtained by doping polymers having conjugated double bonds, such as polyacetylene, polyphenylacetylene, and poly-p-phenylene, with conductive substances such as metals; and carbon, represented by carbon black and graphite. From the viewpoint of imparting conductivity without impairing the fluidity of the toner, conductive titanium oxide or those doped with conductive substances are more preferable as conductive fine particles.

[0119] The content of conductive fine particles is preferably at a lower limit of 0.05 parts by mass or more, more preferably at 0.1 parts by mass or more, and particularly preferably at 0.2 parts by mass or more, per 100 parts by mass of the toner base particles. The upper limit of the content of 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] <Format of this toner> From the viewpoint of image reproducibility and toner consumption, the volume median particle size of this 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 regarding dust, the volume median particle size of this toner is preferably 3.0 μm or larger, more preferably 4.0 μm or larger, and even more preferably 4.5 μm or larger.

[0121] In this invention, "volume median particle size (Dv50)" is defined as the particle size measured by the method described in the Examples section below. It is also defined as the particle size measured for the toner particles finally obtained in the manufacturing process, comprising toner matrix particles and, if necessary, external additives.

[0122] In order to suppress fogging, white background staining, etc., and to obtain stable, high-quality images, this toner preferably has a primary particle diameter of 1.0 μm or less in percentage of particles, more preferably 2.0% or less, more preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.3% or less.

[0123] The shape of this toner is preferably such that the average circularity measured using a flow-type particle image analyzer FPIA-3000 (manufactured by Malvern) is 0.92 or higher, more preferably 0.95 or higher, and even more preferably 0.96 or higher.

[0124] The percentage of particles with 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] [Toner manufacturing method] This toner can be manufactured by producing toner matrix particles using a known method and adding external additives to the toner matrix particles as needed.

[0126] <Manufacturing method for toner matrix particles> To produce these toner matrix particles, a method can be used in which each raw material is prepared as particles smaller than the toner matrix particles, and these are mixed, agglomerated, and matured to obtain the toner matrix particles. For example, toner matrix particles can be obtained by mixing fine particles of binder resin (polymer primary particles), colorant particles, and, if necessary, wax or an antistatic agent, agglomerating and maturing (heat fusion), followed by filtration, washing, and drying. The fine particles (primary polymer particles) of the binder resin 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 emulsifying it by mixing it with an aqueous medium. From the viewpoint of easily controlling the roundness of the final mother particles by agglomerating the particles using an emulsification and coagulation method performed in an aqueous system, it is preferable to obtain the primary polymer particles of styrene-acrylic resin by emulsification polymerization that yields an aqueous emulsion. For similar reasons, it is preferable to obtain the primary polymer particles of polyester resin as an aqueous emulsion by the latter emulsification method. The aforementioned methods for obtaining polymer primary particles can be used both when producing polymer primary particles of the core binder resin and when producing polymer primary particles of the shell binder resin.

[0127] (Method for producing primary polymer particles: Emulsion polymerization) For example, the polymer primary particles, which are composed of the aforementioned styrene-acrylic resin raw material monomers, can be obtained by emulsion polymerization using the monomers and, if necessary, emulsifiers, polymerization initiators, and chain transfer agents. Known emulsifiers can be used. 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 viewpoint of ease of particle formation, washability, and wastewater treatment.

[0128] Examples of cationic surfactants include dodecylammonium chloride, dodecylammonium bromide, dodecyltrimethylammonium bromide, dodecylpyridinium chloride, dodecylpyridinium bromide, and hexadecyltrimethylammonium 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. Increasing the amount of emulsifier results in smaller particle sizes of the resulting polymer primary particles. Decreasing the amount of emulsifier results in larger particle sizes of the resulting polymer primary particles. These emulsifiers can be used in combination with one or more protective colloids, such as polyvinyl alcohols including partially or fully saponified polyvinyl alcohol, or cellulose derivatives including hydroxyethylcellulose.

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

[0133] As the chain transfer agent, one or more known types can be used in combination. Examples of chain transfer agents include trichlorobromomethane, carbon tetrachloride, t-dodecyl mercaptan, and 2-mercaptoethanol. Among these, trichlorobromomethane is preferred from the viewpoint 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, which can suppress deterioration of the toner's electrostatic properties and heat resistance. Alternatively, a wax-long-chain monomer dispersion can be prepared by pre-dispersing the wax with a long-chain monomer such as stearyl acrylate in an aqueous dispersion medium, and the monomer can be polymerized in the presence of the wax-long-chain monomer.

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

[0136] Examples of emulsifiers used to apply shear force include homogenizers, homomixers, pressurized kneaders, extruders, and media dispersers. If the viscosity of the binder resin is high during emulsification and the polymer primary particles do not decrease to the desired particle size, polymer primary particles of the desired particle size can be obtained by using an emulsifier capable of pressurizing above atmospheric pressure to raise the temperature above the melting point or glass transition temperature of the resin, whichever is higher, thereby lowering the resin viscosity during emulsification.

[0137] Another method for reducing resin viscosity is to pre-mix an organic solvent with the binder resin. The organic solvent used is not particularly limited as long as it dissolves styrene-acrylic resin, but examples include ketone 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 or isopropyl alcohol may be added to water or the resin to improve affinity with aqueous media and to control particle size distribution. If an organic solvent is added, it is necessary to remove the organic solvent from the emulsion after emulsification is complete. Methods for removing the organic solvent include volatilizing it at room temperature or under reduced pressure while heated.

[0138] For the purpose of controlling the particle size distribution, salts such as sodium chloride and potassium chloride, or ammonia may be added, and emulsifiers and dispersants may also be added. Examples of emulsifiers and dispersants include water-soluble polymers such as polyvinyl alcohol, methylcellulose, carboxymethylcellulose, 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 method described above, a phase inversion emulsification method may be used to emulsify 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, neutralizing agent, and dispersion stabilizer to the binder resin as needed, adding an aqueous medium dropwise under stirring to obtain emulsion particles, and then removing the organic solvent from the resin dispersion to obtain an emulsion. The organic solvent can be the same as the organic solvent described above. As a neutralizing agent, general acids or alkalis such as nitric acid, hydrochloric acid, sodium hydroxide, and ammonia can be used.

[0140] (Particle size and molecular weight of polymer primary 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, 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, 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. On the other hand, it is 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] (Agglutination process) In the aggregation process, the polymer primary particles, and optionally colorant particles, charge control agents, waxes, etc., are mixed simultaneously or sequentially. It is preferable from the viewpoint of uniformity of composition and particle size to prepare dispersions of each component in advance, i.e., a dispersion of polymer primary particles, and optionally a dispersion of colorant particles, a dispersion of charge control agents, and a dispersion of wax, and then mix them to obtain a mixed dispersion.

[0142] If the toner matrix particles have a core-shell structure, the polymer primary particles of the core binder resin and the polymer primary particles of the shell binder resin may be added simultaneously, or some or all of the polymer primary particles of the core binder resin may be aggregated with other components before adding the polymer primary particles of the shell binder resin.

[0143] When polymer primary particles of the core binder resin (also referred to as core components) and polymer primary particles of the shell binder resin (also referred to as shell components) are loaded simultaneously, if the polarity of the shell components is designed to be thermodynamically intermediate in polarity between the core components and the medium (e.g., water), the shell components will spontaneously adhere to the core components. When attaching the shell components in a wet medium such as water and / or an organic solvent, it is preferable to add the shell components after the composition of the core component raw materials has been determined (or, in the case of producing toner mother particles by agglomerating particles smaller than toner mother particles, agglomerating some or all of the core components) to better position the shell components on the surface of the core components.

[0144] The shell component may be added once or multiple times. The shell component added the first time may be different from the shell component added in subsequent additions, and any combination is permitted. To increase the stability of the core-shell structure particle aggregates obtained in the aggregation process, it is preferable to perform fusion within the aggregated particles in the maturation process following the aggregation process.

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

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

[0147] In the coagulation process, coagulation is usually carried out in a tank equipped with a stirring device. Coagulation methods include heating, adding electrolytes, and combinations of these methods.

[0148] When adding an electrolyte to induce coagulation, the electrolyte can be an acid, alkali, or salt, and can be either organic or inorganic. Examples of electrolytes include, specifically, 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, Na2SO4, K2SO4, Li2SO4, MgCl2, CaCl2, MgSO4, CaSO4, ZnSO4, Al2(SO4)3, Fe2(SO4)3, CH3COONa, and C6H5SO3Na. Of these, inorganic salts having polyvalent metal cations of 2 or higher are preferred.

[0149] The amount of electrolyte added varies depending on the type of electrolyte, the desired particle size, etc., but is preferably 0.02 parts by mass or more, more preferably 0.05 parts by mass or more, 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, per 100 parts by mass of the solid component of the mixed dispersion. When adding an electrolyte to induce coagulation, the coagulation temperature is preferably 20°C or higher, particularly preferably 30°C or higher, preferably 70°C or lower, and particularly preferably 60°C or lower.

[0150] The time required for aggregation is optimized depending on the apparatus shape and processing scale. To achieve the desired particle size of the toner matrix particles, it is preferable to maintain the predetermined temperature for at least 30 minutes. The temperature can be raised at a constant rate or in stages.

[0151] (ripening process) In the maturation process, the mixed dispersion obtained in the coagulation process is heated under conditions of sufficient stirring. In the case of a core-shell structure, the temperature during the maturation process is preferably at or above the Tg of the primary polymer particles of the shell binder resin, and more preferably at or above 5°C higher than the Tg of the primary polymer particles of the shell binder resin. The time required for the maturation process varies depending on the shape of the target toner matrix particles, but it is desirable to hold it for 0.1 to 10 hours, and particularly preferably 0.5 to 5 hours, after reaching a Tg of or above that of the primary polymer particles of the shell binder resin.

[0152] It is preferable to add a surfactant, adjust the pH, or use both in combination at a stage after the coagulation step, preferably before or during the maturation step. The surfactant used here can be selected from one or more emulsifiers that can be used when producing polymer primary particles. It is particularly preferable to use the same emulsifier that was used when producing the polymer primary particles.

[0153] The amount of surfactant to be added is not limited, but is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, 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, per 100 parts by mass of the solid component of the mixed dispersion.

[0154] By adding a surfactant or adjusting the pH between the aggregation step and the completion of the maturation step, it may be possible to suppress the aggregation of particle aggregates obtained in the aggregation step, thereby suppressing the generation of coarse particles in the maturation step.

[0155] By controlling the maturation process time, it is possible to produce toner matrix particles of various shapes depending on the purpose, such as grape-shaped particles that maintain the aggregated shape of the polymer primary particles, potato-shaped particles with further fusion, and spherical particles with even further fusion.

[0156] <Method of adding external additives> Methods for adding external additives include using a high-speed agitator such as a Henschel mixer, or using a device capable of applying compressive shear stress. Toner can be manufactured using a single-stage excipient method, in which all excipients are added simultaneously to the toner matrix particles. It can also be manufactured using a multi-stage excipient method, in which each excipient is added separately. To prevent temperature rise during external addition, methods such as installing a cooling device in the container or performing multi-stage external addition can be used.

[0157] [Usage form] This toner may be used in either a two-component developer that uses the toner together with a carrier, or a magnetic or non-magnetic one-component developer that does not use a carrier.

[0158] When used as a two-component developer, known magnetic materials such as iron powder, magnetite powder, ferrite powder, or those with a resin coating on their surface, or magnetic carriers can be used as carriers. As the coating resin for the resin-coated carrier, commonly known styrene resins, acrylic resins, styrene-acrylic copolymer resins, silicone resins, modified silicone resins, fluororesins, or mixtures thereof can be used.

[0159] [Cartridge / Image Forming System] Next, embodiments of an image forming apparatus having this toner (the image forming apparatus of the present invention) will be described. However, the embodiments are not limited to the following description and can be modified and implemented as such without departing from the spirit of the present invention.

[0160] The image forming apparatus comprises an electrophotographic photoreceptor, a charging device, an exposure device, a developing device, and a toner, and further includes a transfer device, a cleaning device, and a fixing device as needed.

[0161] There are no particular restrictions on the electrophotographic photoreceptor, but for example, a drum-shaped photoreceptor can be used in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support.

[0162] The aforementioned charging device uniformly charges the surface of an electrophotographic photoreceptor to a predetermined potential. Common charging devices include non-contact corona charging devices such as Corotron and Scorotron, or contact-type charging devices.

[0163] The type of exposure apparatus is not particularly limited, as long as it is capable of exposing an electrophotographic photoreceptor to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor.

[0164] The transfer device applies a predetermined voltage value (transfer voltage) with the opposite polarity to the charging potential of the toner, and transfers the toner image formed on the electrophotographic photoreceptor to recording paper (paper, medium). There are no particular restrictions on the type of transfer device, and any device 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 photoreceptor using a cleaning element and recovers the residual toner. However, if there is little or almost no toner remaining on the surface of the electrophotographic photoreceptor, the cleaning device is not necessary. There are no particular restrictions on the cleaning device; any cleaning device such as a brush cleaner, magnetic roller cleaner, or blade cleaner can be used.

[0166] In the image forming apparatus configured as described above, images are recorded in the following manner.

[0167] First, the surface (photosensitive surface) of the electrophotographic photoreceptor is charged to a predetermined potential by a charging device. This charging may be performed using a DC voltage, or by superimposing an AC voltage on a DC voltage. Next, the photosensitive surface of the charged electrophotographic photoreceptor is exposed by an exposure device according to the image to be recorded, forming an electrostatic latent image on the photosensitive surface. Then, the electrostatic latent image formed on the photosensitive surface of the electrophotographic photoreceptor is developed by a developing device. The developing device thins the toner using regulating members such as developing blades, applies a frictional charge to a predetermined polarity, and transports it while supported on developing rollers to bring it into contact with the surface of the electrophotographic photoreceptor.

[0168] When the charged toner carried on the developing roller comes into contact with the surface of the electrophotographic photoreceptor, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the electrophotographic photoreceptor. This toner image is then transferred to recording paper or the like by a transfer device. After this, any toner that remains on the photosensitive surface of the electrophotographic photoreceptor without being transferred is removed by a cleaning device. After transferring the toner image to a printing medium such as recording paper, the toner image is passed through a fixing device to be heat-fixed to the printing medium, thereby obtaining the final image.

[0169] In addition to the configuration described above, the image forming apparatus may also be configured to perform, for example, a static elimination process. The static elimination process is a process of eliminating static electricity from an electrophotographic photoreceptor by exposing it to light.

[0170] The image forming apparatus may be further modified in its configuration. For example, it may be configured to perform processes such as a pre-exposure process and an auxiliary charging process, or to perform offset printing, or even to use a full-color tandem system with multiple types of toner.

[0171] A component for storing toner may be combined with one or more of the following: 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 "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. This toner is applied to this toner cartridge, and the toner cartridge of the present invention is constructed.

[0172] [Printed material] A printed article according to an embodiment of the present invention (hereinafter referred to as "this printed article") is a printed article having a toner fixer on a printing medium, wherein the toner is a toner having at least a binder resin, the binder resin contains at least a polyester resin, the polyester resin content is 3% by mass or more of 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 / cm². 2In a printed material obtained by fixing 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 material 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] This printed material is manufactured by using this toner and printing on a printing medium in accordance with conventional methods. Therefore, the explanations of the constituent requirements described above apply to the toner in this printed material.

[0174] There are no particular restrictions on the printing medium for this printed material; any paper commonly used in image forming machines is acceptable, including general printing paper (including cardboard, postcards, envelopes, plain paper, thin paper, etc.), coated paper made of resin (plastic) such as PET or metal, OHP sheets, OHP films, tracing paper, etc. Of these, this toner is particularly suitable for printed materials using PET coated paper because of its excellent adhesion to PET coated paper. [Examples]

[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 unless it exceeds the scope of its essence. 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, waxes, and colorants (pigments)> The median diameter (D50) of polymer primary particles, wax, and colorants (pigments) was measured using a MicrotracNanotrac150 (hereinafter abbreviated as Nanotrac) manufactured by Nikkiso Co., Ltd. and its analysis software, MicrotracParticle Analyzer Ver10.1.2-0.19EE. Deionized water with an electrical conductivity of 0.5 μS / cm was used as the solvent, and measurements were taken using the method described in the instruction manual, under the following conditions: solvent refractive index: 1.333, measurement time: 120 seconds, and number of measurements: 5. The average value was then calculated. Other setting conditions were: particle refractive index: 1.59, permeability: permeable, shape: spherical, density: 1.04.

[0178] <Toner volume medium particle size (Dv50)> The median volume particle size (Dv50) of the toner was measured using a Beckman Coulter Multisizer III (aperture diameter: 100 μm or less, abbreviated as Multisizer). The toner was dispersed using Beckman Coulter Isoton II as the dispersion medium, with a dispersion concentration of 0.03 mass%. The measurement results are shown as "volume particle size".

[0179] <Average circularity and percentage of particles with a particle size of 1.0 μm or less> The average circularity and the percentage of particles with a particle size of 1.0 μm or less were measured using a flow-type particle analyzer (FPIA3000: Malvern) in HPF mode, under the conditions of HPF analysis volume of 0.35 μL and HPF detection volume of 2000 to 2500 particles. The dispersed phase was dispersed in a dispersion medium (Celseas: Malvern) to a concentration of 5720 to 7140 particles / μL. The measurement results are shown as "Circularity" and "Percentage of particles 1.0 μm or less".

[0180] <Mass average molecular weight (Mw)> The mass-average molecular weight of the styrene-acrylic resin was determined by freeze-drying the styrene-acrylic dispersion (described later) to remove water, and then measuring the THF-soluble components by gel permeation chromatography (GPC) under the following conditions. The mass-average molecular weight of the amorphous polyester resin was determined by gel permeation chromatography (GPC) using the amorphous polyester resin obtained by the procedure described below, under the same conditions. Equipment: Tosoh Corporation GPC system HLC-8320 Column: TOSOH TSKgel SuperHM-H (6mm diameter x 150mm length x 2 columns) Solvent: THF Column temperature: 40℃ Flow rate: 0.5mL / min Sample concentration: 0.1% by mass Calibration curve: Standard polystyrene

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

[0182] <Glass transition temperature (Tg)> The glass transition temperature of polyester resin was measured using a differential calorimeter (Shimadzu Corporation, "DSC-60"), at a heating rate of 5°C / min, from the intersection of the baseline of the chart and the tangent to the endothermic curve. The sample used for measurement was prepared by weighing 10 mg ± 0.5 mg into an aluminum pan, melting it at 100°C (above the glass transition temperature) for 10 minutes, and then rapidly cooling it with dry ice.

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

[0184] <Acid value> The acid value of the polyester resin was measured as follows. Weigh approximately 0.2 g of the measurement sample accurately into a triangular flask with a branch (a(g)), add 20 mL of benzyl alcohol, and heat it with a heater at 230 °C for 15 minutes under a nitrogen atmosphere to dissolve the measurement sample. After cooling to room temperature, add 20 mL of chloroform and a few drops of cresol red solution, and titrate with 0.02 N KOH solution (titration volume = b(mL), titer of KOH solution = p). Perform a blank measurement in the same manner (titration volume = c(mL)), and calculate the acid value according to the following formula. Acid value (mgKOH / g) = {(b - c) × 0.02 × 56.11 × 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> As the wax, 30 parts of ester wax 1 (chemical formula C 21 H 43 COOC 22 H 45 ), 1.93 parts of 20% aqueous sodium dodecylbenzenesulfonate solution (hereinafter abbreviated as 20% DBS aqueous solution), and 68.7 parts of deionized water were placed in a CSTR type stirring layer equipped with a three-stage paddle blade inclined at 45 degrees, and heated to 90 °C in the stirring layer and mixed for 20 minutes. Next, while heating this dispersion at 90 °C, circulation emulsification was performed under a pressure condition of 25 MPa using a valve homogenizer (manufactured by Gorin, 15-M-8PA type), and the particle size was measured with a nanotrack and dispersed until the median diameter (D50) reached 245 nm to prepare a wax dispersion W1 (emulsion solid content concentration: 30.5%).

[0187] <Wax dispersion W2> A wax dispersion W2 (emulsion solid content concentration: 30.5%) was prepared in the same manner as W1 above, except that 30 parts of ester wax 2 (stearyl behenate, melting point 67 °C), 1.93 parts of 20% DBS aqueous solution, and 68.7 parts of deionized water were used.

[0188] <Wax dispersion W3> A wax dispersion W2 (emulsion solid content concentration: 30.8%) was prepared in the same manner as W1 described above, except that 30 parts of ester wax 3 (stearyl stearate, melting point 60°C), 1.93 parts of a 20% DBS aqueous solution, and 68.7 parts of desalinated water were used.

[0189] <Wax dispersion W4> A wax dispersion W4 (emulsion solid content concentration: 30.2%) was prepared in the same manner as W1 described above, except that 30 parts of ester wax 4 (manufactured by NOF Corporation, product name: WEP-3, melting point 73℃, acid value 0.1 mg KOH / g, hydroxyl value 3 mg KOH / g or less (all catalog values)) were used, 0.24 parts of decaglycerin decabehenate (manufactured by Mitsubishi Chemical Corporation, product name: B100D, hydroxyl value 27, melting point 70℃) were used, 1.93 parts of 20% DBS aqueous solution were used, and 67.83 parts of desalinated water were used.

[0190] <Wax Dispersion W5> A wax dispersion W5 (emulsion solid content concentration: 31.0%) was prepared in the same manner as W1, except that 15.0 parts of ester wax 1, 15.0 parts of ester wax 4, 1.93 parts of 20% DBS aqueous solution, and 68.7 parts of desalinated water were used.

[0191] <Wax dispersion W6> A wax dispersion W6 (emulsion solid content concentration: 31.0%) was prepared in the same manner as W1 described above, except that 15.0 parts of ester wax 4, 15.0 parts of ester wax 5 (manufactured by NOF Corporation, product name: WEP-5, melting point 82℃, acid value 0.1 mg KOH / g, hydroxyl value 3 mg KOH / g or less (all catalog values)) were used, 1.93 parts of 20% DBS aqueous solution and 68.7 parts of desalinated water.

[0192] <Colorant Dispersion G1> In a container of a stirrer equipped with propeller blades, 24 parts of pigment blue 15:3 (manufactured by Dainichi Seika Co., Ltd., cyanide pigment (copper phthalocyanine complex)), 1 part of a 20% DBS aqueous solution, 9 parts of a nonionic surfactant (manufactured by Kao Corporation, Emulgen 120), and 67 parts of ion-exchanged water with a conductivity of 2 μS / cm were added as colorants and pre-dispersed to obtain a pigment premix solution. This premix solution was supplied to a wet bead mill as a raw material slurry and dispersed. The inner diameter of the stator of the wet bead mill was 120 mmφ, the diameter of the separator was 60 mmφ, and zirconia beads with a diameter of 0.1 mm were used as the dispersion media. The effective internal volume of the stator was approximately 2 liters, and the media filling volume was 1.4 liters, so the media filling rate was 70%. With the rotor rotation speed kept constant (circumferential speed of the rotor tip approximately 11 m / sec), the raw material slurry was supplied from the supply port at a supply rate of approximately 40 liters / hr using a pulsation-free metering pump. When the predetermined particle size was reached, the dispersion was stopped, and the 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 solid content was 34.3%, and the colorant solid content was 24.1%.

[0193] <Styrene-acrylic dispersion A1> In a reactor equipped with a stirring device, a heating and cooling device, a concentration device, and devices for charging each raw material and auxiliary agent, 35.3 parts of wax dispersion W1, 258 parts of demineralized water, and 0.02 parts of 0.5% iron(II) sulfate heptahydrate aqueous solution were charged, and the mixture was heated under a nitrogen stream while stirring until the internal temperature reached 70°C. Subsequently, while continuing to stir, the mixture of monomers and emulsifiers listed below was added over 300 minutes to obtain an aqueous monomer and emulsifier solution. In this case, the time when the addition of the mixture began was defined as the start of polymerization, and the following initiator aqueous solution was added dropwise from 30 to 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C at 300 minutes from the start of polymerization. The following ferrous sulfate aqueous solution was added at 330 minutes from the start of polymerization. Heating and stirring were continued until 540 minutes from 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 part • Desalinated water 66.7 parts (Initiator aqueous solution) 15.5 parts of 8% hydrogen peroxide solution 30.1 parts of 8% L-(+) ascorbic acid aqueous solution (Iron sulfate solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0196] After the polymerization reaction was complete, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A1. The median diameter (D50) of the polymer primary particles, measured using NanoTrac, was 230 nm. The mass-average molecular weight (Mw) of the polymer primary particles was 81608.

[0197] <Styrene-acrylic dispersion A2> In a reactor equipped with a stirring device, a heating and cooling device, a concentration device, and devices for charging each raw material and auxiliary agent, 70.7 parts of wax dispersion W1, 269 parts of demineralized water, and 0.02 parts of 0.5% iron(II) sulfate heptahydrate aqueous solution were charged, and the mixture was heated under a nitrogen stream while stirring until the internal temperature reached 70°C. Subsequently, while continuing to stir, the mixture of monomers and emulsifiers listed below was added over 300 minutes to obtain an aqueous monomer and emulsifier solution. In this case, the time when the addition of the mixture began was defined as the start of polymerization, and the following initiator aqueous solution was added dropwise from 30 to 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C at 300 minutes from the start of polymerization. The following ferrous sulfate aqueous solution was added at 330 minutes from the start of polymerization. Heating and stirring were continued until 540 minutes from 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 part • Desalinated water 66.7 parts (Initiator aqueous solution) 15.5 parts of 8% hydrogen peroxide solution 30.1 parts of 8% L-(+) ascorbic acid aqueous solution (Iron sulfate solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

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

[0201] <Styrene-acrylic dispersion A3> In a reactor equipped with a stirring device, a heating and cooling device, a concentration device, and devices for charging each raw material and auxiliary agent, 71.3 parts of wax dispersion W2, 271 parts of demineralized water, and 0.02 parts of 0.5% iron(II) sulfate heptahydrate aqueous solution were charged, and the mixture was heated under a nitrogen stream while stirring until the internal temperature reached 70°C. Subsequently, while continuing to stir, the mixture of monomers and emulsifiers listed below was added over 300 minutes to obtain an aqueous monomer and emulsifier solution. In this case, the time when the addition of the mixture began was defined as the start of polymerization, and the following initiator aqueous solution was added dropwise from 30 to 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C at 300 minutes from the start of polymerization. The following ferrous sulfate aqueous solution was added at 330 minutes from the start of polymerization. Heating and stirring were continued until 540 minutes from 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 part • Desalinated water 66.7 parts (Initiator aqueous solution) 15.5 parts of 8% hydrogen peroxide solution 30.1 parts of 8% L-(+) ascorbic acid aqueous solution (Iron sulfate solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

[0204] After the polymerization reaction was complete, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A3. The median diameter (D50) of the polymer primary particles, measured using NanoTrac, was 206 nm. The mass-average molecular weight (Mw) of the polymer primary particles was 83212.

[0205] <Styrene-acrylic dispersion A4> In a reactor equipped with a stirring device, a heating and cooling device, a concentrating device, and devices for charging each raw material and auxiliary agent, 70.6 parts of wax dispersion W3, 272 parts of demineralized water, and 0.02 parts of 0.5% iron(II) sulfate heptahydrate aqueous solution were charged, and the mixture was heated to an internal temperature of 70°C under a nitrogen stream while stirring. Subsequently, while continuing to stir, the mixture of monomers and emulsifiers listed below was added over 300 minutes to obtain an aqueous monomer and emulsifier solution. In this case, the time when the addition of the mixture began was defined as the start of polymerization, and the following initiator aqueous solution was added dropwise from 30 to 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C at 300 minutes from the start of polymerization. The following ferrous sulfate aqueous solution was added at 330 minutes from the start of polymerization. Heating and stirring were continued until 540 minutes from 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 part

[0207] (Emulsifier aqueous solution) · 20% DBS aqueous solution 1.0 part · 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 part

[0208] After the polymerization reaction was completed, it was cooled to obtain a milky white styrene-acrylic dispersion A4. The median diameter (D50) of the polymer primary particles measured using a nanotrack was 220 nm. The mass average molecular weight (Mw) of the polymer primary particles was 79851.

[0209] <Styrene-acrylic dispersion A5> 35.7 parts of wax dispersion W4, 257 parts of demineralized water, and 0.02 part of 0.5% iron(II) sulfate heptahydrate aqueous solution were charged into a reactor equipped with a stirring device, a heating and cooling device, a concentration device, and each raw material and auxiliary agent charging device, and the temperature was raised to 70 °C under a nitrogen stream while stirring. Thereafter, while continuing stirring, a mixture of the following monomers and emulsifier solution was added over 300 minutes to obtain a monomer and emulsifier aqueous solution. At this time, the time when the addition of the mixture was started was taken as the polymerization start time, and the following initiator aqueous solution was dropped between 30 minutes and 420 minutes after the polymerization start. Next, the internal temperature was raised to 90 °C at 300 minutes after the polymerization start. The following iron sulfate aqueous solution was added at 330 minutes after the polymerization start. Heating and stirring were continued until 540 minutes after the polymerization start.

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

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

[0212] After the polymerization reaction was complete, the mixture was cooled to obtain a milky white styrene-acrylic dispersion A5. The median diameter (D50) of the polymer primary particles, measured using NanoTrac, was 273 nm. The mass-average molecular weight (Mw) of the polymer primary particles was 79487.

[0213] <Styrene-acrylic dispersion A6> In a reactor equipped with a stirring device, a heating and cooling device, a concentration device, and devices for charging each raw material and auxiliary agent, 34.8 parts of wax dispersion W5, 258 parts of demineralized water, and 0.02 parts of 0.5% iron(II) sulfate heptahydrate aqueous solution were charged, and the mixture was heated under a nitrogen stream while stirring until the internal temperature reached 70°C. Subsequently, while continuing to stir, the mixture of monomers and emulsifiers listed below was added over 300 minutes to obtain an aqueous monomer and emulsifier solution. In this case, the time when the addition of the mixture began was defined as the start of polymerization, and the following initiator aqueous solution was added dropwise from 30 to 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C at 300 minutes from the start of polymerization. The following ferrous sulfate aqueous solution was added at 330 minutes from the start of polymerization. Heating and stirring were continued until 540 minutes from 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 part • Desalinated water 66.7 parts (Initiator aqueous solution) 15.5 parts of 8% hydrogen peroxide solution 30.1 parts of 8% L-(+) ascorbic acid aqueous solution (Iron sulfate solution) ·0.5% iron(II) sulfate heptahydrate aqueous solution 0.08 part

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

[0217] <Styrene-acrylic dispersion A7> In a reactor equipped with a stirring device, a heating and cooling device, a concentration device, and devices for charging each raw material and auxiliary agent, 34.8 parts of wax dispersion W5, 258 parts of demineralized water, and 0.02 parts of 0.5% iron(II) sulfate heptahydrate aqueous solution were charged, and the mixture was heated under a nitrogen stream while stirring until the internal temperature reached 70°C. Subsequently, while continuing to stir, the mixture of monomers and emulsifiers listed below was added over 300 minutes to obtain an aqueous monomer and emulsifier solution. In this case, the time when the addition of the mixture began was defined as the start of polymerization, and the following initiator aqueous solution was added dropwise from 30 to 420 minutes after the start of polymerization. Next, the temperature was raised to 90°C at 300 minutes from the start of polymerization. The following ferrous sulfate aqueous solution was added at 330 minutes from the start of polymerization. Heating and stirring were continued until 540 minutes from 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) · 1.0 part of 20% DBS aqueous solution · 66.7 parts of deionized water (Initiator aqueous solution) · 15.5 parts of 8% hydrogen peroxide aqueous solution · 30.1 parts of 8% L-(+)-ascorbic acid aqueous solution (Ferrous sulfate aqueous solution) · 0.08 part of 0.5% ferrous sulfate (II) heptahydrate aqueous solution

[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 nanotrack was 234 nm. The mass average molecular weight (Mw) of the polymer primary particles was 75601.

[0221] <Polyester resin> Amorphous polyester resins A, B, and C were produced as follows. A polycarboxylic acid component, a polyhydric alcohol component, and a polymerization catalyst having the charge compositions shown in Table 1 were charged into a reaction vessel equipped with a distillation column. The amount of the polymerization catalyst is the amount (ppm) relative to the acid component. Next, the rotation speed of the stirring blade in the reaction vessel was maintained at 120 rpm, heating was started, and the reaction system was heated so that the temperature in the reaction system reached 265 °C, and the esterification reaction was carried out while maintaining this temperature. After the distillation of water from the reaction system ceased and the esterification reaction ended, the temperature in the reaction system was lowered and maintained at 240 °C, the inside of the reaction vessel was depressurized over about 40 minutes to a vacuum degree of 133 Pa, and a polycondensation reaction was carried out while distilling out the alcohol component from the reaction system. As the reaction proceeded, the viscosity of the reaction system increased. Along with the increase in viscosity, the vacuum degree was 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 shown, the stirring was stopped, the reaction system was returned to normal pressure, and the reaction product was taken out (discharged) from the reaction vessel by pressurizing with nitrogen to obtain each amorphous polyester resin. The mass average molecular weights (Mw) of the obtained amorphous polyester resins A and B were 26000 and 72960, respectively. The mass average molecular weight (Mw) was measured by the method described above. The physical properties (glass transition temperature, softening temperature, and acid value) of the obtained amorphous polyester resins A, B, and C were measured. These results are shown in Table 1.

[0222] In Table 1, "BPA-PO2.3mol addition" and "BPA-EO2.3mol addition" mean the following: BPA-PO2.3mol addition: Propylene oxide derivative of bisphenol A (polyoxypropylene-(2,3)-2,2-bis(4-hydroxyphenyl)propane (PO2.3mol adduct)) BPA-EO2.3mol addition: Ethylene oxide derivative of bisphenol A (polyoxyethylene-(2,3)-2,2-bis(4-hydroxyphenyl)propane, (EO2.3mol adduct))

[0223] [Table 1]

[0224] <Polyester dispersion P1> A resin solution was prepared by dissolving 25 parts of amorphous polyester resin A in 75 parts of methyl ethyl ketone (MEK), adding 22.7 g of 5% aqueous ammonia solution, and stirring uniformly with a stirrer. Next, 100 parts of demineralized water were placed in a round-bottom flask, and the prepared resin solution was added to it. The mixture was then homogenized in a homogenizer (IKA T25 model) for 10 minutes at a rotation speed of 8000 rpm. Subsequently, the solvent was 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 NanoTrack 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) and G'(100°C)) were measured using the method described above.

[0225] <Polyester dispersion P2> A resin solution was prepared by dissolving 25 parts of amorphous polyester resin B in 75 parts of methyl ethyl ketone (MEK), adding 9.46 g of 5% aqueous ammonia solution, and stirring uniformly with a stirrer. Next, 100 parts of demineralized water were placed in a round-bottom flask, and the prepared resin solution was added to it. The mixture was then homogenized in a homogenizer (IKA T25 model) for 10 minutes at a rotation speed of 8000 rpm. Subsequently, the solvent was 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 NanoTrac and found to be 230 nm. The storage modulus (G') of amorphous polyester resin B was G'(70°C) = 25170870 Pa and G'(100°C) = 25814 Pa. The storage modulus (G'(70°C) and G'(100°C)) were measured using the method described above.

[0226] <Polyester dispersion P3> A resin solution was prepared by dissolving 25 parts of amorphous polyester resin C in 75 parts of methyl ethyl ketone (MEK), adding 20.8 g of 5% aqueous ammonia solution, and stirring uniformly with a stirrer. Next, 100 parts of demineralized water were placed in a round-bottom flask, and the prepared resin solution was added to it. The mixture was then homogenized in a homogenizer (IKA T25 model) for 10 minutes at a rotation speed of 8000 rpm. Subsequently, the solvent was 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 NanoTrack 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) and G'(100°C)) were measured using the method described above.

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

[0228] In a mixer equipped with a stirring device, a heating and cooling device, and a device for adding each raw material and auxiliary agent, 85.0 parts (solids) of styrene acrylic dispersion A1, 0.17 parts (solids) of 20% DBS aqueous solution, 0.56 parts (solids) of 5% iron(II) sulfate heptahydrate aqueous solution, and 4.4 parts (solids) of colorant dispersion G1 were added sequentially 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 equivalent to 2 parts per 100 parts of polyester) of 20% DBS aqueous solution was added dropwise over 30 minutes. 30 minutes after the addition was complete, the pH of the system was adjusted to 8.0 using a 4.8% potassium hydroxide aqueous solution. Then, 6.0 parts (solids) of 20% DBS aqueous solution and 232.4 parts of deionized water were added, and the temperature was raised to 75°C over 90 minutes, followed by a further increase to 80°C over 60 minutes. The mixture was then cooled to 30°C over 30 minutes.

[0229] The obtained dispersion was extracted and filtered by suction using an aspirator with Toyo Filter Paper Co., Ltd. No. 5C filter paper. The cake remaining on the filter paper was transferred to a stainless steel container equipped with a stirrer (propeller blades), and ion-exchanged water with an electrical conductivity of 1 μS / cm was added and stirred to uniformly disperse the cake, which was then stirred for 30 minutes. This process was repeated until the electrical conductivity of the filtrate reached 2 μS / cm, and the resulting cake was dried in a forced-air dryer set to 40°C for 48 hours to obtain toner matrix particles B1.

[0230] To the toner matrix particles B1 (100 parts) prepared in this manner, polymer / silica composite particles ATLAS100 (manufactured by Cabot, silica / polymer ratio = 70 / 30, true specific gravity = 1.7 g / cm³) were added. 3Four parts of (containing octahydropentalene), 0.5 parts of titania / silica composite oxide particles STX50.1 (manufactured by Nippon Aerosil Co., Ltd.), and 0.4 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, after which toner C1 was obtained by sieving. The core / shell structure of this toner C1 is as shown in Table 3. The volume-median particle size, average circularity, and percentage of particles 1.0 μm or smaller were measured for the obtained toner C1. The results are shown in Table 2.

[0231] [Example 2] In Example 1, toner C2 was prepared in the same manner as toner C1, 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 percentage of particles 1.0 μm or smaller were measured for the obtained toner C2. The results are shown in Table 2.

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

[0233] [Example 4] In Example 1, toner C4 was prepared in the same manner as toner C1, 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 percentage of particles 1.0 μm or smaller were measured for the obtained toner C4. The results are shown in Table 2.

[0234] [Example 5] In Example 1, toner C5 was prepared in the same manner as toner C1, 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 percentage of particles 1.0 μm or smaller were measured for the obtained toner C5. The results are shown in Table 2.

[0235] [Example 6] In Example 1, toner C6 was prepared in the same manner as toner C1, 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 percentage of particles 1.0 μm or smaller were measured for the obtained toner C6. The results are shown in Table 2.

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

[0237] [Example 8] In Example 1, toner C8 was prepared in the same manner as toner C1, except that styrene-acrylic dispersion A1 was replaced with 70.0 parts (solids) of styrene-acrylic dispersion A5 and polyester dispersion P1 was replaced with 30.0 parts (solids). The core / shell structure of this toner C8 is as shown in Table 3. The volume-median particle size, average circularity, and percentage of particles 1.0 μm or smaller were measured for the obtained toner C8. The results are shown in Table 2.

[0238] [Example 9] In Example 1, toner C9 was prepared in the same manner as toner C1, 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 as shown in Table 3. The volume-median particle size, average circularity, and percentage of particles 1.0 μm or smaller were measured for the obtained toner C9. The results are shown in Table 2.

[0239] [Example 10] In Example 1, toner C10 was prepared in the same manner as toner C1, 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 percentage of particles 1.0 μm or smaller were measured for the obtained toner C10. The results are shown in Table 2.

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

[0241] In a mixer equipped with a stirring device, a heating and cooling device, and a device for adding each raw material and auxiliary agent, 85.0 parts (solids) of styrene acrylic dispersion A5, 0.17 parts (solids) of 20% DBS aqueous solution, 0.56 parts (solids) of 5% iron(II) sulfate heptahydrate aqueous solution, and 4.4 parts (solids) of colorant dispersion G1 were added sequentially 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 20% DBS aqueous solution and 23 parts of deionized water were added, and the temperature was raised to 80°C over 90 minutes, then to 83°C over 60 minutes. After that, it was cooled to 30°C over 30 minutes.

[0242] The obtained dispersion was extracted and filtered by suction using an aspirator with Toyo Filter Paper Co., Ltd. No. 5C filter paper. The cake remaining on the filter paper was transferred to a stainless steel container equipped with a stirrer (propeller blades), and ion-exchanged water with an electrical conductivity of 1 μS / cm was added and stirred to uniformly disperse the cake, which was then stirred for 30 minutes. This process was repeated until the electrical conductivity of the filtrate reached 2 μS / cm, and the resulting cake was dried in a forced-air dryer set to 40°C for 48 hours to obtain toner matrix particles B11.

[0243] To the toner matrix particles B11 (100 parts) prepared in this manner, polymer / silica composite particles ATLAS100 (manufactured by Cabot, silica / polymer ratio = 70 / 30, true specific gravity = 1.7 g / cm³) were added. 3 Four parts of (containing octahydropentalene), 0.5 parts of titania / silica composite oxide particles STX50.1 (manufactured by Nippon Aerosil Co., Ltd.), and 0.4 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, after which toner C11 was obtained by sieving. The core / shell structure of this toner C11 is as shown in Table 3. The volume-median particle size, average circularity, and percentage of particles 1.0 μm or smaller were measured for the obtained toner C11. The results are shown in Table 2.

[0244] [Comparative Example 2] In Example 1, toner C12 was prepared in the same manner as toner C1, except that styrene-acrylic dispersion A1 was replaced with 99.0 parts (solids) of styrene-acrylic dispersion A5 and polyester dispersion P1 was replaced with 1.0 part (solids). The core / shell structure of this toner C12 is as shown in Table 3. The volume-median particle size, average circularity, and percentage of particles 1.0 μm or smaller were measured for the obtained toner C12. The results are shown in Table 2.

[0245] [Comparative Example 3] Toner C13 was prepared in the same manner as toner C1, 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 as shown in Table 3. The volume-median particle size, average circularity, and percentage of particles 1.0 μm or smaller were measured for the obtained toner C13. The results are shown in Table 2.

[0246] [Table 2]

[0247] <Procedure for cross-sectional SEM observation of fixed images, and calculation of the polyester resin contact length ratio (A / B) of the fixed surface> Using the same printing conditions as described in the <scraping test>, 0.8 mg / cm² was applied to the printing medium (PET coated paper). 2 The toner was fixed to the entire surface at a certain concentration, and the cross-section of the PET-coated paper was observed at 10,000x magnification using a backscattered electron detector of a scanning electron microscope (SEM).

[0248] The observation procedure described above was repeated a total of 40 times for each different field of view, and 40 observation images were taken. For each image taken, the length of the portion where the polyester resin on the toner surface was in contact with the printing medium surface was determined, and the sum of these lengths (A) was divided by the sum of the lengths of the portions where the toner and the printing medium surface were determined for each image, and the resulting value (A / B) was taken as the length ratio of the polyester resin on the toner surface in contact with the PET coated paper surface. In addition, even if there was a portion in the observed cross-section where the toner had peeled off from the fixing surface, it was considered to be in contact and its length was measured.

[0249] The above (A) and (B) were determined as described above. For example, for toner C1 manufactured in Example 1, in Figure 1, the portion indicated by the dotted line 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 portion was defined as (A). On the other hand, the total length of the portion indicated by the dashed line in Figure 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 defined as (B). The procedure will be described in more detail below, but the methods and equipment are not limited to these, and any cross-sectional preparation method or microscopic observation method that yields appropriate results for the purpose can be used.

[0250] The PET-coated paper image was cut into pieces a few millimeters square, and the PET-coated paper was thinned with a razor blade from the opposite side (non-printed side) without damaging the image. The thinned PET-coated paper pieces were then glued with super glue to a metal plate about 0.3 mm thick, with the image side facing up. A metal plate with PET-coated paper pieces attached was fixed to the sample stage of a JEOL Cross-Section Polisher SM-9010 so that an ion beam was irradiated from the metal plate side. At this time, the paper pieces protruding from the metal plate were cut away by cutting with a razor blade, which advanced from the fixed image side toward the metal plate side. A sample stage holding a metal plate was attached to the chamber of a cross-section polisher, and cutting was performed for 3 hours using an argon ion beam at an acceleration voltage of 4kV and a current of approximately 100μA. The processed sample piece was held on the SEM sample stage with the cut surface facing upwards, and the interface (contact surface) between the toner and PET coated paper on the cut surface was observed using a backscattered electron detector with an acceleration voltage of 3-5kV and an irradiation current of approximately 1nA using a JEOL Ltd. JSM-F100. 40 fields of view were captured at 10,000x magnification. For each captured image, the length of the portion where the polyester resin on the toner surface was in contact with the PET coated paper surface was measured, and the sum of these lengths was defined as A. For the same image, the length of the portion where the toner and the PET coated paper surface were in contact was calculated and the sum of these lengths was defined as B. The ratio of the length of the polyester resin on the toner surface in contact with the PET coated paper surface was calculated using the following formula. The results are shown in Table 4. (Ratio of the length where the polyester resin on the toner surface contacts the surface of the PET-coated paper) = A / B A cross-sectional SEM photograph of the fixed image of toner C1 manufactured in Example 1 is shown in FIG. 1.

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

[0252] <Calculation of the average thickness of the polyester resin on the toner surface> For each of the images taken above, the thickness of the polyester resin on the toner surface was directly measured. In one field of view (one image), the length of the thickest part among the polyester resin parts in contact with the printing medium was measured, and the average value was calculated. This was done for 40 fields of view (40 images), and all the average values were taken as the average thickness of the polyester resin on the toner surface. The results are shown in Table 5.

[0253] <DSC measurement> The DSC measurement of the toner was performed by the following method. The apparatus used was AAQ20 and a cooling device RCS90 (both manufactured by TA Instruments). A TzeroStandard was used as the sample pan, and 3.0 mg of the measurement sample was weighed. The measurement was performed as follows. It was adjusted to 20°C, heated to 120°C at 10°C / min for the first temperature rise, held at 120°C for 5 minutes, and then cooled to 0°C at 10°C / min. After that, it was held at 0°C for 5 minutes and then heated to 120°C at 10°C / min for the second temperature rise. In this DSC measurement, the difference between the full width at half maximum (FMAX) of the endothermic peak during the first cooling cycle and the FMAX of the exothermic peak during the first heating cycle [(first cooling cycle) - (first heating cycle)], and the difference between the FMAX of the endothermic peak during the first cooling cycle and the FMAX of the exothermic peak during the second heating cycle [(first cooling cycle) - (second heating cycle)] are shown in Table 4.

[0254] <Adhesion evaluation (scraping test)> The obtained toner was used in a commercially available printer with a print speed of 16 ppm, equipped with a non-magnetic, single-component organic photoreceptor charged by a developing rubber roller, metal blade, and charging roller (PCR), and with the fuser unit removed. Using two toner cartridges, the amount of toner deposited onto glossy recording paper (water-resistant paper Kareka, manufactured by Kokusai Paper & Pulp Trading Co., Ltd.), which is PET coated paper, was approximately 0.8 mg / cm². 2 The unfixed toner image was printed. The hot roll fixing machine used had a roller diameter of 27 mm, a nip width of 9 mm, and a fixing speed of 95 mm / sec. It had a heater on the upper roller, and the roller surface was made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) without silicone oil coating. The roller surface temperature was set to 175°C, and the amount of material adhering was approximately 0.8 mg / cm². 2 A recording paper bearing an unfixed toner image was transported to the fixing nip to obtain a fixed image. A scraping test was performed by scraping the fixed image with a vertically positioned flathead screwdriver. The tip width of the flathead screwdriver was 1 mm, and a load of 250 g was applied to the tip using a weight. The travel distance was 2 cm, and a total of three back-and-forth scraping tests were performed. The travel speed was approximately 1 cm / s, and the angle between the direction of travel and the tip surface of the flathead screwdriver was 90°. The degree of scraping was observed visually and evaluated according to the following criteria. The evaluation results are shown in Table 4. (Evaluation Criteria) ◎: It didn't shave off at all. ○: There was one or fewer small white spots caused by scraping. △: The length of the lines created by scraping was less than 3 mm, or there were multiple small white dots. ×: The length of the line created by the scraping was 3 mm or more.

[0255] <Evaluation of low-temperature fixation ability> The obtained toner was used in a commercially available printer with a print speed of 16 ppm, equipped with a non-magnetic, single-component organic photoreceptor charged by a developing rubber roller, metal blade, and charging roller (PCR), and with the fuser unit removed. The toner was then transferred to recording paper (OKI Excellent White (product name)) with a toner adhesion amount of approximately 0.5 mg / cm². 2 The unfixed toner image was printed. The hot roll fixing machine used had a roller diameter of 27 mm, a nip width of 9 mm, and a heater on the upper roller. The roller surface was made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) and no silicone oil was applied. The roller surface temperature was set to 145°C, 150°C, and 155°C, and fixing was performed at a fixing speed of 229 mm / sec at each temperature to obtain evaluation samples. The evaluation criteria for the fixing test were as follows. The evaluation results are shown in Table 4. (Evaluation Criteria) ○: The fixed image was not offset, and no image defects occurred even when rubbed. △: The fixed image was not offset, but rubbing it resulted in image defects. ×: The fixed image was offset.

[0256] <Storage Stability Evaluation> A metal cylinder with a diameter of 2 cm was placed upright on a metal plate, and a weighing paper was wrapped around the inside of the cylinder. 10 g of toner was gently poured into the upright metal cylinder, and then a 20 g weight was placed on top of the toner. The metal cylinder, still placed on a metal plate, was placed in a constant temperature and humidity chamber at 50°C and 55% relative humidity (normal humidity conditions) for 48 hours, or placed in a high temperature and high humidity chamber at 50°C and 80% relative humidity (high humidity conditions) for 24 hours. After removing the sample from the constant temperature and humidity chamber, the metal cylinder and weighing paper were carefully removed, and the cylindrical toner was removed while still in its upright position. A load was applied in 10g increments to a vertically positioned, solidified toner, and the load at which the cylindrical shape collapsed was measured. The measured loads were evaluated according to the following criteria. The evaluation results are shown in Table 4. (Evaluation Criteria) ○: Collapsed under a load of 500g or less. This indicates that the toner adhesion is weak and the storage stability is good. △: It did not collapse under a load of 500g, but collapsed under a load of 1500g or less. ×: It did not collapse under a load of 1500g. This means that the toner is strongly adhered and has poor storage stability.

[0257] [Table 3]

[0258] [Table 4]

[0259] [Table 5]

[0260] <Consideration> From the above examples and comparative examples, it was found that by placing an appropriate amount of polyester resin on the particle surface, the strength between particles and the printing medium, and between particles themselves, is improved. As a result, this toner exhibits excellent adhesion to printing media such as PET coated paper, low-temperature fixation, and does not cause deterioration of storage performance 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 are possible without departing from the intent and scope of the invention. This application is based on Japanese Patent Application No. 2022-055334, filed on March 30, 2022, which is incorporated herein by reference in its entirety.

Claims

1. A toner having at least a binder resin, The binder resin comprises at least a polyester resin. The polyester resin content is 5% by mass or more relative to the total mass of the toner. The aforementioned toner was used at a printing temperature of 175°C, a printing speed of 16 ppm, and a print density of 0.8 mg / cm². ２ In a printed material obtained by fixing to PET coated paper under the printing conditions, when A is the total length of contact between the polyester resin and the PET coated paper in the cross-section of the printed material, and B is the total length of contact between the toner and the PET coated paper, the toner satisfies the following formula (1) for A and B. 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. The toner according to claim 1, wherein the polyester resin is an amorphous polyester resin.

4. The toner according to claim 1, wherein the polyester resin content is 2.5% by mass or more and 40% by mass or less based on the total mass of the toner.

5. The toner according to claim 1, further containing wax.

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

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

8. In a differential scanning calorimetry (DSC) measurement that performs a temperature program including the steps of raising the temperature from 40°C to 100°C or higher at a heating rate of 10°C / min (first heating), then lowering the temperature to 40°C or lower at a cooling rate of 10°C / min (first cooling), and then raising the temperature to 100°C or higher at a heating rate of 10°C / min (second heating), the toner according to claim 7, wherein the difference between the full width at half maximum of the endothermic peak during the first cooling and the full width at half maximum of the exothermic peak during the first heating [(first cooling) - (first heating)] is 7.0°C or less, and the difference between the full width at half maximum of the endothermic peak during the first cooling and the full width at half maximum of the exothermic peak during the second heating [(first cooling) - (second heating)] is 7.0°C or less.

9. The toner according to claim 1, wherein the acid value of the polyester resin is 5 mg KOH / g or more.

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

11. The toner according to claim 1, having a core-shell structure, wherein the binder resin of the core is the styrene-acrylic resin, and the binder resin of the shell is the polyester resin.

12. The toner according to claim 11, wherein the ratio of the acid values ​​of the styrene-acrylic resin and the polyester resin ([acid value of the styrene-acrylic resin of the core] / [acid value of the polyester resin of the shell]) is 0.85 or more and 2.9 or less.

13. The toner according to claim 1, wherein the average thickness of the polyester resin on the toner surface is 0.20 μm or more.

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

15. The toner according to claim 1, further containing a coloring agent.

16. A toner cartridge containing the toner described in any one of claims 1 to 15.

17. An image forming apparatus containing the toner according to any one of claims 1 to 15.

18. A printed material having a toner fixative on a printing medium, The toner is a toner having at least a binder resin, The binder resin comprises at least a polyester resin. The polyester resin content is 5% by mass or more relative to the total mass of the toner. The aforementioned toner was used at a printing temperature of 175°C, a printing speed of 16 ppm, and a print density of 0.8 mg / cm². ２ In a printed material obtained by fixing to PET coated paper under the printing conditions, when A is the total length of contact between the polyester resin and the PET coated paper in the cross-section of the printed material, and B is the total length of contact between the toner and the PET coated paper, the printed material satisfies the following formula (1) when A and B. 0.05≦A / B≦0.55...(1)

19. The printed article according to claim 18, wherein the binder resin further comprises a styrene-acrylic resin.

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