Toner for developing electrostatic images, electrostatic image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method

Abstract

To provide an electrostatic image developing toner which suppresses streaky image defects.SOLUTION: An electrostatic image developing toner provided herein comprises toner particles containing a binder resin containing an amorphous resin comprising an amorphous resin a1 and an amorphous resin a2, and a crystalline resin comprising a crystalline resin c1, and satisfies the following expressions (1) and (2): 10,000≤Mw(a2)-Mw(a1)≤150,000 ...(1), |SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≤0.9 ...(2), where Mw(a1) represents weight-average molecular weight of the amorphous resin a1, Mw(a2) represents weight-average molecular weight of the amorphous resin a2, SP(a1) represents a solubility parameter value (SP value) of the amorphous resin a1, SP(a2) represents a solubility parameter value (SP value) of the amorphous resin a2, and SP(c1) represents a solubility parameter value (SP value) of the crystalline resin c1.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an electrostatic charge image developing toner, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method.

Background Art

[0002] Methods for visualizing image information, such as the electrophotographic method, are currently used in various fields. In the electrophotographic method, an electrostatic charge image is formed as image information on the surface of an image carrier by charging and electrostatic charge image formation. Then, a toner image is formed on the surface of the image carrier by a developer containing toner, and after transferring this toner image to a recording medium, the toner image is fixed to the recording medium. Through these steps, the image information is visualized as an image.

[0003] For example, Patent Document 1 discloses "a toner binder containing two or more amorphous polyester resins (P) formed by reacting a carboxylic acid component (x) and an alcohol component (y) as constituent components, wherein at least one of the (P) is an amorphous polyester resin (P1) containing an aliphatic diol (y1) having 2 to 4 carbon atoms in the alcohol component (y) in an amount of 50 to 100 mol% based on the number of moles of the alcohol component (y), and at least one of the (P) is an amorphous polyester resin (P2) containing an alkylene oxide adduct (y2) of bisphenol A in the alcohol component (y) in an amount of 51 to 100 mol% based on the number of moles of the alcohol component (y), the weight average molecular weight of the amorphous polyester resin (P1) is 3000 to 30000, and the weight average molecular weight of the amorphous polyester resin (P2) is 10000 to 300000, the amorphous polyester resin (P2) is a non-linear polyester, and the solubility parameters (SP values) of the (P1) and the (P2) satisfy 0.84 < SPP2 / SPP1 < 0.98".

[0004] Furthermore, Patent Document 2 describes a toner containing toner particles containing a binder resin and a colorant, wherein the binder resin contains a crystalline resin A and an amorphous resin B, and when the toner is measured by a differential scanning calorimeter, the endothermic amount of the endothermic peak derived from the crystalline resin A is 1.0 J / g or more and 20.0 J / g or less, and the SP value SPa((J / cm 3 ) 1 / 2 ) and the SP value SPb ((J / cm 3 ) 1 / 2 ) satisfies |SPa-SPb|≦2.0, and in a cross section of the toner observed with a transmission electron microscope (TEM), the crystalline resin A forms dendrites. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-141967 [Patent Document 2] Japanese Patent Application Publication No. 2018-017786 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventionally, electrostatic image developing toners containing toner particles containing a binder resin containing an amorphous resin and a crystalline resin have sometimes caused streak-like image defects. Therefore, an object of the present invention is to provide an electrostatic image developing toner containing toner particles containing a binder resin containing an amorphous resin and a crystalline resin, in which streak-like image defects are suppressed compared to when the formula (2) described below is not satisfied, or when Voronoi tessellation is performed using the centers of gravity of the islands in a sea-island structure as the generating points, and the coefficient of variation of the area of ​​the Voronoi polygon is less than 0.3. [Means for solving the problem]

[0007] The means for solving the above problems include the following aspects.

[0008] <1> The toner particles contain a binder resin, the binder resin includes an amorphous resin including an amorphous resin a1 and an amorphous resin a2, and a crystalline resin including a crystalline resin c1, The weight average molecular weight of the amorphous resin a1 is Mw(a1), the weight average molecular weight Mw(a2) of the amorphous resin a2, The solubility parameter value (SP value) of the amorphous resin a1 is SP(a1), The solubility parameter value (SP value) of the amorphous resin a2 is SP(a2), The toner for developing electrostatic images satisfies the following formulae (1) and (2), where SP(c1) is the solubility parameter value (SP value) of the crystalline resin c1. Formula (1): 10,000≦Mw(a2)-Mw(a1)≦150,000 Formula (2):|SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.9 <2> The formula (2) further satisfies the following formula (2-2): <1> 2. The toner for developing electrostatic images according to claim 1. Formula (2-2): 0.2≦|SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.9 <3> The above further satisfies the following formula (3): <1> or <2> 2. The toner for developing electrostatic images according to claim 1. Formula (3): 0.8≦|SP(a2)-SP(c1)|≦2.5 <4> The content of the crystalline resin c1 is 2% by mass or more and 25% by mass or less with respect to the toner particles. <1> ~ <3> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <5> The content of the crystalline resin c1 is 2% by mass or more and 40% by mass or less with respect to the amorphous resin. <4> 2. The toner for developing electrostatic images according to claim 1. <6> The toner particles contain a binder resin, The toner particles have a sea-island structure including a sea portion containing an amorphous resin and an island portion containing a crystalline resin, and The toner for developing electrostatic images, wherein when Voronoi tessellation is performed using the centers of gravity of the islands in the sea-island structure as kernel points, the coefficient of variation of the area of ​​Voronoi polygons is 0.3 or more. <7> The toner particles have a coefficient of variation of the area of ​​the Voronoi polygon of 0.3 or more and 1.5 or less. <6> 2. The toner for developing electrostatic images according to claim 1. <8> The average diameter of the island portions is 100 nm or more and 800 nm or less. <6> or <7> 2. The toner for developing electrostatic images according to claim 1. <9> The content of the amorphous resin is 35% by mass or more and 95% by mass or less with respect to the toner particles. <1> ~ <8> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <10> The amorphous resin includes at least one of an amorphous polyester resin and a hybrid resin having a polyester resin segment and a styrene-acrylic copolymer segment. <1> ~ <9> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <11> The crystalline resin includes a crystalline polyester resin. <1> ~ <10> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <12> The aforementioned <1> ~ <11> 10. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 9. <13> The aforementioned <1> ~ <11> 10. A toner cartridge containing the toner for developing electrostatic images according to any one of claims 1 to 9, which is detachably mounted on an image forming apparatus. <14> The aforementioned <12> and a developing means for developing an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image, the process cartridge being detachably mountable to an image forming apparatus. <15> an image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; The aforementioned <12> a developing means for developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing means for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising: [Effects of the Invention]

[0009] <1> , <10> or <11> According to the invention, there is provided a toner for developing electrostatic images that includes toner particles containing a binder resin that includes an amorphous resin and a crystalline resin, and that suppresses streak-like image defects compared to when the formula (2) is not satisfied, that is, when |SP(a1)-SP(c1)| / |SP(a2)-SP(c1)| is more than 0.9.

[0010] <2> According to the invention relating to (1), a toner for developing electrostatic images is provided in which streak-like image defects are suppressed compared to when the formula (2-2) is not satisfied, that is, when |SP(a1) - SP(c1)| / |SP(a2) - SP(c1)| is less than 0.2 or exceeds 0.9.

[0011] <3> According to the invention, a toner for developing electrostatic images is provided in which streak-like image defects are suppressed compared to when the formula (3) is not satisfied, i.e., when SP(a2)-SP(c1) is less than 0.8 or exceeds 2.5.

[0012] <4> According to the present invention, a toner for developing electrostatic images is provided in which streak-like image defects are suppressed compared to when the content of crystalline resin c1 is less than 2% by mass or more than 25% by mass relative to the toner particles.

[0013] <5> According to the present invention, a toner for developing electrostatic images is provided in which streak-like image defects are suppressed compared to when the content of crystalline resin c1 is less than 2% by mass or more than 40% by mass relative to the amorphous resin.

[0014] <6> , <10> or <11> According to the invention, there is provided a toner for developing electrostatic images, which includes toner particles containing a binder resin including an amorphous resin and a crystalline resin, and which, when Voronoi tessellated using the centers of gravity of the islands in the sea-island structure as the kernel points, suppresses streak-like image defects compared to when the coefficient of variation of the area of ​​the Voronoi polygon is less than 0.3.

[0015] <7> According to the invention, there is provided a toner for developing electrostatic images in which streak-like image defects are suppressed compared to when the coefficient of variation of the area of ​​the Voronoi polygon is less than 0.3 or more than 1.5.

[0016] <8> According to the invention, there is provided a toner for developing electrostatic images in which streak-like image defects are suppressed compared to when the average diameter of the island portions is less than 100 nm or exceeds 800 nm.

[0017] <9> According to the present invention, there is provided a toner for developing electrostatic images in which streak-like image defects are suppressed compared to when the content of the amorphous resin is less than 35% by mass or more than 95% by mass relative to the toner particles.

[0018] <12> , <13> , <14> or <15> According to the invention, in a toner for developing electrostatic images that includes toner particles containing a binder resin that contains an amorphous resin and a crystalline resin, an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method is provided in which streak-like image defects are suppressed compared to when "the formula (2) is not satisfied, that is, when |SP(a1) - SP(c1)| / |SP(a2) - SP(c1)| is greater than 0.9" or when "when Voronoi tessellation is performed using the centers of gravity of the islands in the sea-island structure as the generating points, the coefficient of variation of the area of ​​the Voronoi polygon is less than 0.3." [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Figure 2]1 is a schematic diagram illustrating an example of a process cartridge that is detachably mounted to an image forming apparatus according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following describes an embodiment of the present invention, which is an example of the present invention. These descriptions and examples are for illustrating the present invention, but are not intended to limit the present invention.

[0021] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the present specification, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this disclosure, the upper or lower limit of the numerical range may be replaced by the values ​​shown in the examples.

[0022] In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0023] When embodiments are described in this specification with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these.

[0024] In this specification, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in this disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified.

[0025] In this specification, the particles corresponding to each component may contain multiple types. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0026] In this specification, "toner for developing electrostatic images" is also referred to simply as "toner," and "electrostatic image developer" is also referred to simply as "developer."

[0027] <Toner for developing electrostatic images> The toner according to the first embodiment has toner particles containing a binder resin, and the binder resin contains an amorphous resin containing amorphous resin a1 and amorphous resin a2, and a crystalline resin containing crystalline resin c1, and when the weight average molecular weight of the amorphous resin a1 is Mw(a1), the weight average molecular weight of the amorphous resin a2 is Mw(a2), the solubility parameter value (SP value) of the amorphous resin a1 is SP(a1), the solubility parameter value (SP value) of the amorphous resin a2 is SP(a2), and the solubility parameter value (SP value) of the crystalline resin c1 is SP(c1), the following formulas (1) and (2) are satisfied. Formula (1): 10,000≦Mw(a2)-Mw(a1)≦150,000 Formula (2):|SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.9

[0028] The toner according to the second embodiment has toner particles containing a binder resin, and the toner particles have a sea-island structure containing a sea portion containing an amorphous resin and island portions containing a crystalline resin, and when Voronoi tessellation is performed using the centers of gravity of the island portions in the sea-island structure as kernel points, the coefficient of variation of the area of ​​the Voronoi polygon is 0.3 or more.

[0029] The toner according to the first and second embodiments has the above-described structure, which suppresses streak-like image defects. The reason for this is presumed to be as follows.

[0030] It has been known that toner particles containing a binder resin including an amorphous resin and a crystalline resin form a sea-island structure containing a sea portion containing an amorphous resin and an island portion containing a crystalline resin. Toner particles that form this conventional sea-island structure tend to have highly dispersed island portions containing the crystalline resin within the particles. Therefore, for example, the toner may be deformed due to thermal or mechanical factors in the fixing device, and the deformed toner may easily adhere to components such as the carrier and the developing device. As a result, streak-like image defects may occur when repeatedly forming images.

[0031] The toner according to the first embodiment includes a binder resin containing amorphous resin a1, amorphous resin a2, and crystalline resin c1, each having a different solubility parameter value (SP value) and weight-average molecular weight, and each resin satisfies formulas (1) and (2). This tends to form island regions containing crystalline resin c1 and sea regions containing amorphous resin a1 and amorphous resin a2. In this case, the solubility parameter values ​​(SP value) and weight-average molecular weights satisfying formulas (1) and (2) increase the affinity between a portion of the amorphous resin a1 in the sea regions, which has a relatively small weight-average molecular weight, and the crystalline resin c1 in the island regions. This tends to result in the island regions containing crystalline resin c1 being locally unevenly distributed within the toner particles. Therefore, even if thermal or mechanical factors occur in the fixing device, the toner is less likely to deform and adhere to the carrier, developer, or the like. This is believed to result in suppression of streak-like image defects.

[0032] In a second embodiment of the toner, the toner particles have a sea-island structure containing a sea portion containing an amorphous resin and island portions containing a crystalline resin, and the coefficient of variation of the area of ​​the Voronoi polygon is 0.3 or greater. The coefficient of variation of the area of ​​the Voronoi polygon specifies the variation in the area of ​​the Voronoi polygon, i.e., the variation in the occupancy of the island portions within the toner particles. When the coefficient of variation of the area of ​​the Voronoi polygon is 0.3 or greater, the island portions containing the crystalline resin within the toner particles do not vary too much, i.e., the island portions tend to be locally unevenly distributed. Therefore, even if there are thermal or mechanical factors in the fixing device, for example, the toner is less likely to deform and adhere to the carrier, developer, etc. It is believed that this results in suppression of streak-like image defects.

[0033] The toner corresponding to both the toner according to the first and second embodiments (hereinafter also referred to as "toner according to the present embodiment") will be described in detail below. However, an example of the toner of the present invention may be a toner corresponding to either the toner according to the first or second embodiment.

[0034] The toner according to the exemplary embodiment includes toner particles, and may include an external additive that is externally added to the toner particles.

[0035] -Properties of toner particles- (sea-island structure) From the viewpoint of further suppressing streak-like image defects, the toner particles according to the first embodiment preferably have a sea-island structure containing a sea portion containing an amorphous resin and island portions containing a crystalline resin. The toner particles according to the second embodiment have a sea-island structure containing a sea portion containing an amorphous resin and island portions containing a crystalline resin.

[0036] From the viewpoint of further suppressing streak-like image defects, the toner particles preferably have an average island diameter of 100 nm or more and 800 nm or less, more preferably 150 nm or more and 700 nm or less, and even more preferably 200 nm or more and 650 nm or less.

[0037] As a method for controlling the average diameter of the island portions of the sea-island structure within the above range, for example, when a toner is produced by a kneading and pulverizing method, the average diameter of the island portions can be controlled by adjusting the kneading temperature or the screw rotation speed to control the kneading state, or by adjusting the temperature at which the kneaded mixture is cooled to control the crystallization rate.When a toner is produced by an emulsion aggregation method, the average diameter can be controlled by adjusting the dispersion diameter of the crystalline resin or by adjusting the temperature at which particles are fused.

[0038] The sea-island structure and the average diameter of the islands are measured by the following method. The toner is embedded in epoxy resin, sliced ​​using a diamond knife or similar, and stained with osmium tetroxide or ruthenium tetroxide in a desiccator. The stained slices are then observed under a scanning electron microscope (SEM). The sea and islands of the sea-island structure are distinguished by the degree of staining of the resin by osmium tetroxide or ruthenium tetroxide, and this is used to confirm the presence or absence of a sea-island structure. 100 islands are randomly selected from the obtained SEM image, and the longest diameter of each island is measured. The arithmetic mean of the longest diameters of the 100 islands is taken as the average diameter.

[0039] (Voronoi polygon variation coefficient) In order to further suppress streak-like image defects, when the toner particles according to the first embodiment are subjected to Voronoi tessellation using the centers of gravity of the islands in the sea-island structure as the generating points, the coefficient of variation of the area of ​​the Voronoi polygons is preferably 0.3 or more, more preferably 0.3 or more and 1.5 or less, and even more preferably more than 0.5 and less than 1.20. In order to further suppress streak-like image defects, when the toner particles according to the second embodiment are subjected to Voronoi tessellation using the centers of gravity of the islands in the sea-island structure as the generating points, the coefficient of variation of the area of ​​the Voronoi polygons is 0.3 or more, preferably 0.3 or more and 1.5 or less, and more preferably more than 0.5 and less than 1.20.

[0040] The coefficient of variation of the area of ​​the Voronoi polygon is calculated as follows. As explained above in the confirmation of the sea-island structure, the cross section of the toner particle is observed. Using the center of gravity of all islands present on the cross section of one toner particle as the kernel point, Voronoi polygon division is performed (drawing a perpendicular bisector on the line connecting adjacent kernel points to divide the area nearest to each kernel point), and the area of ​​all Voronoi polygons formed is measured. The center of gravity of the island is defined as the number of pixels in the island area, n, and the x and y coordinates of each pixel, x i , y i When (i=1,2,…,n), the x coordinate of the center of gravity = (x i y coordinate of the center of gravity = (y i (total of ) / n. This operation is carried out for 300 toner particles, and the arithmetic mean value and standard deviation of the areas of the Voronoi polygons are calculated.

[0041] The coefficient of variation of the area of ​​the Voronoi polygon is calculated by the following formula. Coefficient of variation of the area of ​​Voronoi polygons = {S1 / K1} x 100 (%) In the above formula, S1 represents the standard deviation of the area of ​​the Voronoi polygon of the island portion present in the toner particle, and K1 represents the arithmetic mean value of the area of ​​the Voronoi polygon.

[0042] For example, if the observation field contains toner particles that are not the target of observation (such as toner particles with no observable island portions), or if there are black image areas that become noise around the toner particles that are the target of observation, the image analysis should be specified to exclude areas other than the toner particles that are the target of observation.

[0043] The specific method for setting the coefficient of variation of the area of ​​the Voronoi polygon within the above range is not particularly limited, but examples thereof include adjusting the solubility parameter value (SP value) and weight average molecular weight (Mw) of each of the amorphous resin and crystalline resin in the binder resin, which will be described later, in a toner manufacturing method including a step of heating and mixing an amorphous resin and a crystalline resin, such as a kneading and pulverization method.Furthermore, in a wet toner manufacturing method such as an emulsion aggregation method, the coefficient of variation can also be adjusted by changing the ratio of the amorphous resin dispersion to the crystalline resin dispersion each time the resin particle dispersion is dropped multiple times.

[0044] The toner particles may be toner particles of a single layer structure, or may be toner particles of a so-called core-shell structure composed of a core part (core particle) and a coating layer (shell layer) that coats the core part.

[0045] The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0046] The various average particle sizes and particle size distribution indices of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5 mass % aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute, and the particle size distribution of particles in the range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, cumulative distributions of volume and number are drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at 16% of the cumulative total is defined as the volume particle size D16v, the number particle size D16p, the particle size at 50% of the cumulative total as the volume average particle size D50v, the cumulative number average particle size D50p, and the particle size at 84% of the cumulative total as the volume particle size D84v and the number particle size D84p. Using these, the volumetric particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 , the number particle size distribution index (GSDp) is (D84p / D16p) 1 / 2 It is calculated as:

[0047] The average circularity of the toner particles is preferably 0.90 or more and 1.00 or less, and more preferably 0.92 or more and 0.98 or less.

[0048] The average circularity of toner particles is calculated by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)]. Specifically, this value is measured by the following method. The toner particles to be measured are sucked and collected, forming a flat flow, and a still image of the particles is captured by instantly emitting a strobe light, which is then analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Spectris). The number of samples to be taken when calculating the average circularity is 4,500. When the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0049] - Composition of toner particles - The toner particles contain, for example, a binder resin, and may also contain a colorant, a release agent, and other additives, as necessary.

[0050] -Binder resin- The binder resin according to the first embodiment includes an amorphous resin including an amorphous resin a1 and an amorphous resin a2, and a crystalline resin including a crystalline resin c1. The binder resin according to the second embodiment includes an amorphous resin and a crystalline resin. In the binder resin according to the second embodiment, the amorphous resin may include an amorphous resin a1 and an amorphous resin a2, or the crystalline resin may include a crystalline resin c1.

[0051] For example, when the binder resin contains three or more amorphous resins that satisfy formula (1), amorphous resin a1 refers to the resin that exhibits the smallest solubility parameter value (SP value), and amorphous resin a2 refers to the resin that exhibits the largest solubility parameter value (SP value).

[0052] For example, when the binder resin contains two or more kinds of crystalline resins, the crystalline resin c1 refers to the resin that accounts for the largest proportion of all the crystalline resins.

[0053] For example, when the binder resin contains two or more types of crystalline resins and the contents of the two or more types of crystalline resins are equal, the solubility parameter value of crystalline resin c1, SP(c1), is the arithmetic mean value of the solubility parameter values ​​of the two or more types of crystalline resins.

[0054] (Weight average molecular weight) The binder resin according to the first embodiment satisfies the following formula (1), where Mw(a1) is the weight average molecular weight of the amorphous resin a1 and Mw(a2) is the weight average molecular weight of the amorphous resin a2. From the viewpoint of further suppressing streak-like image defects, the binder resin may also satisfy the following formula (1-2) or (1-3):

[0055] From the viewpoint of further suppressing streak-like image defects, the binder resin according to the second embodiment preferably satisfies the following formula (1), and may also satisfy the following formula (1-2) or formula (1-3).

[0056] Formula (1): 10,000≦Mw(a2)-Mw(a1)≦150,000 Formula (1-2): 15,000≦Mw(a2)-Mw(a1)≦140,000 Formula (1-3): 30,000≦Mw(a2)-Mw(a1)≦100,000

[0057] In the binder resin according to the present embodiment, from the viewpoint of further suppressing streak-like image defects, the weight average molecular weight Mw(a1) of the amorphous resin a1 may be 7,000 or more and 30,000 or less, 10,000 or more and 25,000 or less, or 12,000 or more and 22,000 or less. In the binder resin according to the present embodiment, from the viewpoint of further suppressing streak-like image defects, the weight average molecular weight Mw(a2) of the amorphous resin a2 may be 25,000 or more and 180,000 or less, 30,000 or more and 150,000 or less, or 50,000 or more and 90,000 or less. In the binder resin according to this embodiment, from the viewpoint of further suppressing streak-like image defects, the weight average molecular weight Mw(c1) of the crystalline resin c1 may be 8,000 or more and 100,000 or less, 10,000 or more and 80,000 or less, or 12,000 or more and 60,000 or less.

[0058] The weight-average molecular weight is measured using a gel permeation chromatography (GPC) system (HLC-8420GCP, manufactured by Tosoh Corporation) with a Tosoh TSKgel SuperHM-M (15 cm) column in THF solvent. A molecular weight curve is created from the measurement results using monodisperse polystyrene standard samples. The weight-average molecular weight is then calculated using the molecular weight curve created.

[0059] The means for making the weight-average molecular weight of each resin satisfy the above-mentioned values ​​and formulas (1) to (1-3) is not particularly limited, and examples thereof include a method of adjusting the ratio of monomers, crosslinking agents, etc. that form the resin; a method of adjusting the ratio of the monomers and polymerization catalyst; and a method of adjusting polymerization conditions such as polymerization temperature and polymerization time.

[0060] (Solubility parameter value) The binder resin according to the first embodiment satisfies the following formula (2), where the solubility parameter value (SP value) of the amorphous resin a1 is SP(a1), the solubility parameter value (SP value) of the amorphous resin a2 is SP(a2), and the solubility parameter value (SP value) of the crystalline resin c1 is SP(c1). From the viewpoint of further suppressing streak-like image defects, the binder resin preferably satisfies the following formula (2-2), and more preferably satisfies the following formula (2-3).

[0061] From the viewpoint of further suppressing streak-like image defects, the binder resin according to the second embodiment preferably satisfies the following formula (2), more preferably satisfies the following formula (2-2), and further preferably satisfies the following formula (2-3).

[0062] Equation (2): |SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.9 Formula (2-2): 0.2≦|SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.9 Formula (2-3): 0.4≦|SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.7

[0063] From the viewpoint of further suppressing streak-like image defects, the binder resin according to this embodiment preferably satisfies the following formula (3), more preferably satisfies the following formula (3-2), and further preferably satisfies the following formula (3-3). Equation (3) :0.8≦|SP(a2)-SP(c1)|≦2.5 Formula (3-2): 1.1≦|SP(a2)-SP(c1)|≦2.3 Formula (3-3): 1.2≦|SP(a2)-SP(c1)|≦2.1

[0064] In order to more easily satisfy the above formulae, the binder resin according to this embodiment may have a value of SP(a1) of 9.8 or more and 10.5 or less, 9.9 or more and 10.4 or less, or 9.95 or more and 10.3 or less. In order to more easily satisfy the above formulae, the binder resin according to this embodiment may have a value of SP(a2) of 10.1 or more and 11.5 or less, 10.3 or more and 11.30 or less, or 10.5 or more and 11.2 or less. In order to more easily satisfy the above formulae, the binder resin according to this embodiment may have an SP(c1) value of 8.6 or more and 10.2 or less, 8.7 or more and 10.0 or less, or 8.9 or more and 9.9 or less.

[0065] The solubility parameter (SP value) of each resin is a value calculated by the Fedors method (Polym. Eng. Sci., 14, 147 (1974)).

[0066] There are no particular limitations on the means for ensuring that the solubility parameter value (SP value) of each resin satisfies the above values ​​and formulas (2) to (2-3), but examples include a method of adjusting the types and ratios of monomers that form the resin. More specifically, for example, when the binder resin is a polyester resin, the SP value of the resulting polyester resin can be increased by, for example, changing from an aromatic diol such as bisphenol A to an aliphatic diol such as propylene glycol or neopentyl glycol. Furthermore, when the binder resin is a polyester resin, the SP value of the resulting polyester resin can be increased by, for example, changing the type of dicarboxylic acid used as the acid component from an aromatic dicarboxylic acid such as terephthalic acid to an aliphatic dicarboxylic acid such as sebacic acid. Furthermore, when the binder resin is a hybrid resin having a polyester resin segment and a styrene-acrylic copolymer segment, the SP value of the resulting hybrid resin can be adjusted by adjusting the ratio of the polyester resin segment to the styrene-acrylic copolymer segment in addition to the preparation of the polyester resin segment.

[0067] Here, the term "amorphous resin" refers to a resin that, in thermal analysis measurement using differential scanning calorimetry (DSC), does not show a clear endothermic peak but only a stepwise endothermic change, is solid at room temperature, and becomes thermoplastic at a temperature equal to or higher than the glass transition temperature. On the other hand, a crystalline resin is one that exhibits a clear endothermic peak rather than a stepwise change in endothermic amount in differential scanning calorimetry (DSC). Specifically, for example, a crystalline resin means a resin whose half-width of the endothermic peak when measured at a heating rate of 10°C / min is within 10°C, and an amorphous resin means a resin whose half-width exceeds 10°C or a resin in which no clear endothermic peak is observed.

[0068] The amorphous resin will be described. Examples of amorphous resins include known amorphous resins such as amorphous polyester resins, amorphous vinyl resins (e.g., styrene-acrylic resins), epoxy resins, polycarbonate resins, polyurethane resins, etc. Among these, amorphous polyester resins and amorphous vinyl resins (particularly styrene-acrylic resins) are preferred, and amorphous polyester resins are more preferred. In addition, it is also a preferred embodiment to use an amorphous polyester resin and a styrene-acrylic resin in combination as the amorphous resin.It is also a preferred embodiment to use an amorphous resin having an amorphous polyester resin segment and a styrene-acrylic resin segment as the amorphous resin.

[0069] Amorphous polyester resin The amorphous polyester resin may be, for example, a condensation polymer of a polycarboxylic acid and a polyhydric alcohol. As the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0070] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. The polycarboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acids may be used alone or in combination of two or more.

[0071] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyhydric alcohols, and aromatic diols are more preferred. As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more.

[0072] Amorphous polyester resins can be obtained by known production methods. Specifically, for example, the polymerization temperature is set to 180°C or higher and 230°C or lower, and the reaction system is reduced in pressure as necessary, and the reaction is carried out while removing water and alcohol generated during condensation. If the raw material monomers are not soluble or compatible at the reaction temperature, a high-boiling solvent may be added as a solubilizer to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the solubilizer. If a monomer with poor compatibility is present in the copolymerization reaction, it is recommended that the poorly compatible monomer be condensed in advance with the acid or alcohol to be polycondensed, and then polycondensed with the main component.

[0073] Examples of the amorphous polyester resin include unmodified amorphous polyester resins and modified amorphous polyester resins. Modified amorphous polyester resins include amorphous polyester resins containing bonding groups other than ester bonds, and amorphous polyester resins in which a resin component other than polyester is bonded by a covalent bond, an ionic bond, or the like. Examples of modified amorphous polyester resins include resins in which an amorphous polyester resin having a functional group such as an isocyanate group introduced into the terminal thereof is reacted with an active hydrogen compound to modify the terminal.

[0074] The proportion of the amorphous polyester resin in the total binder resin is preferably 60% by mass or more and 98% by mass or less, more preferably 65% ​​by mass or more and 96% by mass or less, and even more preferably 70% by mass or more and 95% by mass or less.

[0075] Styrene acrylic resin Styrene-acrylic resins are copolymers obtained by copolymerizing at least a styrene-based monomer (a monomer having a styrene skeleton) and a (meth)acrylic-based monomer (a monomer having a (meth)acrylic group, preferably a monomer having a (meth)acryloxy group). The styrene-acrylic resins include, for example, copolymers of a styrene monomer and a (meth)acrylic acid ester monomer. The acrylic resin portion of the styrene-acrylic resin is a partial structure formed by polymerizing either an acrylic monomer or a methacrylic monomer, or both. Furthermore, the term "(meth)acrylic" includes both "acrylic" and "methacrylic."

[0076] Examples of styrene-based monomers include styrene, α-methylstyrene, metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, meta-tert-butoxystyrene, para-tert-butoxystyrene, paravinylbenzoic acid, paramethyl-α-methylstyrene, etc. One type of styrene-based monomer may be used alone, or two or more types may be used in combination.

[0077] Examples of the (meth)acrylic monomer include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. One (meth)acrylic monomer may be used alone, or two or more may be used in combination.

[0078] The polymerization ratio of the styrene-based monomer to the (meth)acrylic monomer is preferably styrene-based monomer:(meth)acrylic monomer=70:30 to 95:5 on a mass basis.

[0079] The styrene-acrylic resin may have a crosslinked structure. The styrene-acrylic resin having a crosslinked structure can be produced, for example, by copolymerizing a styrene-based monomer, a (meth)acrylic monomer, and a crosslinkable monomer. The crosslinkable monomer is not particularly limited, but is preferably a bifunctional or higher functional (meth)acrylate compound.

[0080] The method for producing the styrene-acrylic resin is not particularly limited, and for example, solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization is applied. For the polymerization reaction, a known operation (for example, a batch system, a semi-continuous system, or a continuous system) is applied.

[0081] The proportion of the styrene acrylic resin in the total binder resin is preferably 0% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 2% by mass or more and 10% by mass or less.

[0082] Amorphous resins having an amorphous polyester resin segment and a styrene-acrylic resin segment (hereinafter also referred to as "hybrid amorphous resins") The hybrid amorphous resin is an amorphous resin in which an amorphous polyester resin segment and a styrene-acrylic resin segment are chemically bonded. Examples of hybrid amorphous resins include resins having a main chain made of polyester resin and a side chain made of styrene-acrylic resin chemically bonded to the main chain; resins having a main chain made of styrene-acrylic resin and a side chain made of polyester resin chemically bonded to the main chain; resins having a main chain made of polyester resin and styrene-acrylic resin chemically bonded to the main chain; and resins having a main chain made of polyester resin and styrene-acrylic resin chemically bonded to the main chain, and at least one side chain made of polyester resin chemically bonded to the main chain and a side chain made of styrene-acrylic resin chemically bonded to the main chain.

[0083] The amorphous polyester resin and styrene-acrylic resin in each segment are as described above, and therefore further explanation will be omitted.

[0084] The amorphous resin preferably contains at least one of an amorphous polyester resin and an amorphous resin having a polyester resin segment and a styrene-acrylic segment.

[0085] The total amount of the polyester resin segment and the styrene-acrylic resin segment in the entire hybrid amorphous resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

[0086] In the hybrid amorphous resin, the proportion of the styrene-acrylic resin segment in the total amount of the polyester resin segment and the styrene-acrylic resin segment is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less.

[0087] The hybrid amorphous resin is preferably produced by any one of the following methods (i) to (iii). (i) After preparing a polyester resin segment by condensation polymerization of a polyhydric alcohol and a polycarboxylic acid, a monomer constituting a styrene-acrylic resin segment is subjected to addition polymerization. (ii) After preparing a styrene-acrylic resin segment by addition polymerization of an addition-polymerizable monomer, polyhydric alcohol and polycarboxylic acid are condensation-polymerized. (iii) Polycondensation of a polyhydric alcohol and a polycarboxylic acid and addition polymerization of an addition-polymerizable monomer are carried out in parallel.

[0088] The proportion of the hybrid amorphous resin in the total binder resin is preferably 60% by mass or more and 98% by mass or less, more preferably 65% ​​by mass or more and 96% by mass or less, and even more preferably 70% by mass or more and 95% by mass or less.

[0089] The characteristics of the amorphous resin will be explained. The glass transition temperature (Tg) of the amorphous resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 70°C or lower. The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, from the "extrapolated glass transition onset temperature" described in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0090] The crystalline resin will now be described. Examples of the crystalline resin include known crystalline resins such as crystalline polyester resins and crystalline vinyl resins (e.g., polyalkylene resins, long-chain alkyl (meth)acrylate resins, etc.) Among these, crystalline polyester resins are preferred in terms of the mechanical strength and low-temperature fixability of the toner.

[0091] Crystalline polyester resin Examples of the crystalline polyester resin include a polycondensate of a polycarboxylic acid and a polyhydric alcohol. As the crystalline polyester resin, a commercially available product or a synthesized product may be used. The crystalline polyester resin is preferably a polycondensate using a straight-chain aliphatic polymerizable monomer rather than a polymerizable monomer having an aromatic ring, since it easily forms a crystalline structure.

[0092] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acid may be a tricarboxylic or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the tricarboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polycarboxylic acids may be used alone or in combination of two or more.

[0093] Examples of polyhydric alcohols include aliphatic diols (for example, straight-chain aliphatic diols having 7 to 20 carbon atoms in the main chain). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. The polyhydric alcohol may be a trihydric or higher alcohol having a crosslinked or branched structure, such as glycerin, trimethylolethane, trimethylolpropane, or pentaerythritol, in combination with the diol. The polyhydric alcohols may be used alone or in combination of two or more.

[0094] The polyhydric alcohol may have an aliphatic diol content of 80 mol % or more, preferably 90 mol % or more.

[0095] The crystalline polyester resin can be obtained by a known production method, for example, in the same manner as the amorphous polyester resin.

[0096] The crystalline polyester resin is preferably a polymer of an α,ω-straight-chain aliphatic dicarboxylic acid and an α,ω-straight-chain aliphatic diol.

[0097] The α,ω-linear aliphatic dicarboxylic acid is preferably an α,ω-linear aliphatic dicarboxylic acid in which the alkylene group connecting the two carboxy groups has 3 to 14 carbon atoms, more preferably 4 to 12 carbon atoms, and even more preferably 6 to 10 carbon atoms. Examples of the α,ω-linear aliphatic dicarboxylic acid include succinic acid, glutaric acid, adipic acid, 1,6-hexanedicarboxylic acid (commonly known as suberic acid), 1,7-heptanedicarboxylic acid (commonly known as azelaic acid), 1,8-octanedicarboxylic acid (commonly known as sebacic acid), 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid. Of these, 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, and 1,10-decanedicarboxylic acid are preferred. The α,ω-linear aliphatic dicarboxylic acids may be used alone or in combination of two or more.

[0098] The α,ω-linear aliphatic diol is preferably an α,ω-linear aliphatic diol in which the alkylene group connecting the two hydroxy groups has 3 to 14 carbon atoms, more preferably 4 to 12 carbon atoms, and even more preferably 6 to 10 carbon atoms. Examples of the α,ω-linear aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, and 1,18-octadecanediol. Of these, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred. The α,ω-linear aliphatic diols may be used alone or in combination of two or more.

[0099] The polymer of an α,ω-linear aliphatic dicarboxylic acid and an α,ω-linear aliphatic diol is preferably a polymer of at least one selected from the group consisting of 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid, and at least one selected from the group consisting of 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

[0100] The content of the binder resin is preferably 40% by mass to 96% by mass, more preferably 50% by mass to 93% by mass, and even more preferably 60% by mass to 90% by mass, based on the total mass of the toner particles.

[0101] In order to further suppress streak-like image defects, the content of crystalline resin c1 is preferably 2% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and even more preferably 4% by mass or more and 15% by mass or less, relative to the toner particles.

[0102] In order to further suppress streak-like image defects, the content of the crystalline resin c1 is preferably 2% by mass or more and 40% by mass or less, more preferably 3% by mass or more and 35% by mass or less, and even more preferably 4% by mass or more and 30% by mass or less, relative to the amorphous resin.

[0103] From the viewpoint of further suppressing streak-like image defects, the content of the crystalline resin (c1) is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more and 100% by mass or less, relative to the total amount of the crystalline resin.

[0104] From the viewpoint of further suppressing streak-like image defects, the mass ratio (a1 / a2) of the amorphous resin (a1) to the amorphous resin (a2) is preferably 0.2 to 10.0, more preferably 0.5 to 9.0, and even more preferably 0.8 to 8.0.

[0105] From the viewpoint of further suppressing streak-like image defects, the total content of the amorphous resin (a1) and the amorphous resin (a2) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more and 100% by mass or less, based on the amount of the amorphous resin.

[0106] From the viewpoint of further suppressing streak-like image defects, the content of the amorphous resin relative to the toner particles is preferably 35% by mass or more and 95% by mass or less, more preferably 40% by mass or more and 92% by mass or less, and even more preferably 45% by mass or more and 90% by mass or less.

[0107] The mass ratio of the crystalline resin to the amorphous resin (crystalline resin / amorphous resin) is preferably 2 / 98 or more and 50 / 50 or less, and more preferably 4 / 96 or more and 40 / 60 or less.

[0108] -Coloring agent- Examples of colorants include carbon black, chrome yellow, Hansa Yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, Examples of suitable dyes include pigments such as ultramarine blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; and dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes. The colorant may be used alone or in combination of two or more kinds.

[0109] The colorant may be surface-treated as needed, or may be used in combination with a dispersant. Furthermore, a plurality of colorants may be used in combination.

[0110] The content of the colorant is preferably from 1% by mass to 30% by mass, and more preferably from 3% by mass to 15% by mass, based on the total mass of the toner particles.

[0111] -Mold release agent- Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but are not limited thereto.

[0112] The melting temperature of the release agent is preferably 50°C or higher and 140°C or lower, and more preferably 60°C or higher and 120°C or lower. The melting temperature of the release agent is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121:1987 "Method for measuring transition temperatures of plastics."

[0113] The content of the release agent is preferably 1% by mass or more and 20% by mass or less, and more preferably 4% by mass or more and 15% by mass or less, based on the total mass of the toner particles.

[0114] -Other additives- Examples of other additives include known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the toner particles as internal additives.

[0115] [External additives] Examples of external additives include inorganic particles, such as SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, and K2O·(TiO2). n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0116] The surfaces of inorganic particles as external additives are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is usually, for example, 1 part by mass or more and 60 parts by mass or less per 100 parts by mass of the inorganic particles.

[0117] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate, and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based polymers).

[0118] The amount of the external additive added is preferably 0.01% by mass or more and 10.0% by mass or less, and more preferably 0.1% by mass or more and 6.0% by mass or less, based on the toner particles.

[0119] [Toner manufacturing method] The toner according to this exemplary embodiment is obtained by producing toner particles and then externally adding an external additive to the toner particles.

[0120] The toner particles may be produced by any of a dry production method (for example, a kneading and pulverization method) and a wet production method (for example, an aggregation and coalescence method, a suspension polymerization method, a dissolution and suspension method). There are no particular limitations on these production methods, and any known production method may be used.

[0121] For example, an example of a method for producing toner particles by kneading and pulverizing will be described. The kneading and pulverizing method is a method for producing toner particles by, for example, melting and kneading a binder resin containing an amorphous resin and a crystalline resin with a colorant, followed by pulverizing and classifying the mixture. In the kneading and pulverizing method, toner particles are produced through, for example, a kneading step for melting and kneading components containing the binder resin and the colorant, a cooling step for cooling the molten and kneaded mixture, a pulverizing step for pulverizing the cooled kneaded mixture, and a classification step for classifying the pulverized mixture.

[0122] Each step of the kneading and pulverizing method will be described in detail below.

[0123] -Kneading process- The kneading step is a step in which components including a binder resin containing an amorphous resin and a crystalline resin are melt-kneaded to obtain a kneaded product. Examples of kneaders used in the kneading step include a three-roll type, a single-screw type, a twin-screw type, and a Banbury mixer type. The melting temperature may be determined depending on the type and compounding ratio of the binder resin to be kneaded.

[0124] -Cooling process- The cooling step is a step of cooling the kneaded material formed in the kneading step. Examples of the cooling method in the cooling step include a method using a rolling roll through which cold water or brine is circulated and a pinching cooling belt, etc. When cooling is performed by the above method, the cooling rate is determined by the speed of the rolling roll, the flow rate of brine, the supply amount of the kneaded material, the slab thickness of the kneaded material when rolling, etc.

[0125] -Crushing process- The kneaded product cooled in the cooling step is pulverized in the pulverization step to form particles. In the pulverization step, for example, a mechanical pulverizer, a jet pulverizer, or the like is used.

[0126] -Classification process- The pulverized product (particles) obtained in the pulverization step may be classified in a classification step, if necessary, to obtain toner particles having a desired average particle size. In the classification process, conventional centrifugal classifiers, inertial classifiers, etc. are used to remove fine particles (particles smaller than the target particle size range) and coarse particles (particles larger than the target particle size range).

[0127] -Hot air treatment process- After the classification step, if necessary, hot air treatment may be carried out in a hot air treatment step in order to obtain toner particles with a desired circularity.

[0128] The toner according to this embodiment is produced by, for example, adding an external additive to the obtained dry toner particles and mixing them. The mixing can be carried out using, for example, a V blender, a Henschel mixer, a Loedige mixer, etc. Furthermore, if necessary, coarse particles may be removed from the toner using a vibrating sieve, an air sieve, etc.

[0129] <Electrostatic image developer> The electrostatic image developer according to this embodiment contains at least the toner according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the toner according to this embodiment, or may be a two-component developer containing the toner mixed with a carrier.

[0130] The carrier is not particularly limited, and examples thereof include known carriers, such as coated carriers in which the surface of a core material made of magnetic powder is coated with a coating resin, magnetic powder dispersion carriers in which magnetic powder is dispersed and blended in a matrix resin, and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material and are coated with a coating resin.

[0131] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0132] Examples of coating resins and matrix resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resins containing organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenolic resins, and epoxy resins. The coating resin and the matrix resin may contain other additives such as conductive particles. Examples of conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0133] Here, the method of coating the surface of the core material with a coating resin includes a method of coating with a solution for forming a coating layer, in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be selected taking into consideration the coating resin to be used, its applicability, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer, a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material, a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air, and a kneader coater method in which the core material of the carrier and the solution for forming a coating layer are mixed in a kneader coater and the solvent is removed.

[0134] In the two-component developer, the mixing ratio (mass ratio) of toner to carrier is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0135] <Image forming device / image forming method> An image forming apparatus and an image forming method according to this embodiment will be described. The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, an electrostatic image forming unit that forms an electrostatic image on the surface of the charged image carrier, a developing unit that contains an electrostatic image developer and develops the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer, a transfer unit that transfers the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing unit that fixes the toner image transferred to the surface of the recording medium. The electrostatic image developer according to the present embodiment is used as the electrostatic image developer.

[0136] The image forming apparatus according to this embodiment carries out an image forming method (the image forming method according to this embodiment) that includes a charging step of charging the surface of an image carrier, an electrostatic image forming step of forming an electrostatic image on the surface of the charged image carrier, a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to this embodiment, a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0137] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; an intermediate transfer type apparatus that primarily transfers a toner image formed on the surface of an image carrier to the surface of an intermediate transfer medium, and then secondarily transfers the toner image transferred to the surface of the intermediate transfer medium to the surface of a recording medium; an apparatus equipped with a cleaning means that cleans the surface of the image carrier after the transfer of the toner image but before charging; and an apparatus equipped with a discharging means that irradiates the surface of the image carrier with discharging light to discharge it after the transfer of the toner image but before charging. In the case of an intermediate transfer type device, the transfer means is configured to have, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of the recording medium.

[0138] In the image forming apparatus according to the present embodiment, for example, a portion including the developing means may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with developing means that accommodates the electrostatic image developer according to the present embodiment is preferably used.

[0139] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0140] FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to this embodiment. The image forming apparatus shown in Figure 1 includes first through fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming means) that output images in the colors yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side horizontally spaced a predetermined distance apart from one another. Note that these units 10Y, 10M, 10C, and 10K may also be process cartridges that are detachable from the image forming apparatus.

[0141] Above each of the units 10Y, 10M, 10C, and 10K in the drawing, an intermediate transfer belt 20 serving as an intermediate transfer body extends through each unit. The intermediate transfer belt 20 is wound around a drive roll 22 and a support roll 24 that are spaced apart from each other and arranged from left to right in the drawing, and is configured to run in a direction from the first unit 10Y to the fourth unit 10K. A force is applied to the support roll 24 in a direction away from the drive roll 22 by a spring or the like (not shown), thereby applying tension to the intermediate transfer belt 20 wound around them. In addition, an intermediate transfer body cleaning device 30 is provided on the image carrier side of the intermediate transfer belt 20, facing the drive roll 22. In addition, the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K are supplied with toner including four colors of toner, yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K, respectively.

[0142] Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, the first unit 10Y, which forms a yellow image and is disposed upstream in the direction of travel of the intermediate transfer belt, will be described here as a representative. Note that parts equivalent to those of the first unit 10Y are given reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y), and descriptions of the second to fourth units 10M, 10C, and 10K will be omitted.

[0143] The first unit 10Y has a photoreceptor 1Y that acts as an image carrier. Around the photoreceptor 1Y, there are arranged in this order: a charging roll (an example of a charging means) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic image forming means) 3 that exposes the charged surface to a laser beam 3Y based on a color-separated image signal to form an electrostatic image; a developing device (an example of a developing means) 4Y that supplies charged toner to the electrostatic image to develop it; a primary transfer roll 5Y (an example of a primary transfer means) that transfers the developed toner image onto an intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer. The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20 and is positioned opposite the photoreceptor 1Y. Furthermore, a bias power supply (not shown) that applies a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

[0144] The operation of forming a yellow image in first unit 10Y will be described below. First, prior to operation, the surface of the photosensitive member 1Y is charged to a potential of −600V to −800V by the charging roll 2Y. The photoconductor 1Y has conductivity (for example, volume resistivity at 20°C: 1×10 -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate with a resistivity of Ωcm or less. This photosensitive layer normally has a high resistance (the resistance of ordinary resins), but when irradiated with a laser beam 3Y, the resistivity of the irradiated portion changes. Therefore, a laser beam 3Y is output to the charged surface of the photosensitive element 1Y via an exposure device 3 in accordance with image data for yellow sent from a control unit (not shown). The laser beam 3Y is irradiated onto the photosensitive layer on the surface of the photosensitive element 1Y, thereby forming an electrostatic charge image of a yellow image pattern on the surface of the photosensitive element 1Y.

[0145] An electrostatic image is an image formed on the surface of the photosensitive element 1Y by charging it; the laser beam 3Y reduces the resistivity of the irradiated portion of the photosensitive layer, causing the charged charges on the surface of the photosensitive element 1Y to flow, while the charges remain in the portions not irradiated by the laser beam 3Y, forming a so-called negative latent image. The electrostatic image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic image on the photoreceptor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0146] The developing device 4Y contains an electrostatic image developer containing, for example, at least yellow toner and a carrier. The yellow toner is frictionally charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. The photoreceptor 1Y on which the yellow toner image has been formed continues to travel at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0147] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y to the primary transfer roll 5Y acts on the toner image, causing the toner image on the photoreceptor 1Y to be transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the (-) polarity of the toner, and in the first unit 10Y, for example, it is controlled to +10 μA by a control unit (not shown). On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

[0148] Furthermore, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit 10M and subsequent units is also controlled in accordance with the first unit. In this way, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is conveyed sequentially through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are transferred onto the intermediate transfer belt 20 in a superimposed manner.

[0149] The intermediate transfer belt 20, onto which the four-color toner images have been multiplex-transferred through the first to fourth units, reaches a secondary transfer section composed of the intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer means) 26 arranged on the image bearing surface side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a negative polarity, the same as the negative polarity of the toner. Electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined according to resistance detected by resistance detection means (not shown) that detects resistance in the secondary transfer section, and is voltage-controlled.

[0150] Thereafter, the recording paper P is sent to the pressure contact portion (nip portion) of a pair of fixing rolls in a fixing device (an example of fixing means) 28, where the toner image is fixed onto the recording paper P, forming a fixed image.

[0151] Examples of the recording paper P onto which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, examples of the recording medium include overhead projector sheets and the like. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper in which the surface of plain paper is coated with resin or the like, or art paper for printing, is preferably used.

[0152] The recording paper P on which the color image has been fixed is conveyed toward the discharge section, and the series of color image forming operations is completed.

[0153] <Process cartridges / toner cartridges> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment is a process cartridge that is detachably attached to an image forming apparatus and that contains the electrostatic image developer according to this embodiment and is equipped with a developing means that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image.

[0154] The process cartridge according to this embodiment is not limited to the above configuration, but may also be configured to include a developing device and, if necessary, at least one other means selected from an image carrier, a charging means, an electrostatic image forming means, and a transfer means.

[0155] An example of a process cartridge according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of other parts will be omitted.

[0156] FIG. 2 is a schematic diagram showing the configuration of the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured to integrally combine and hold a photosensitive member 107 (an example of an image carrier), a charging roll 108 (an example of a charging means) provided around the photosensitive member 107, a developing device 111 (an example of a developing means), and a photosensitive member cleaning device 113 (an example of a cleaning means), which are held by a housing 117 provided with, for example, mounting rails 116 and an opening 118 for exposure, and is made into a cartridge. In FIG. 2, 109 denotes an exposure device (an example of an electrostatic image forming means), 112 denotes a transfer device (an example of a transfer means), 115 denotes a fixing device (an example of a fixing means), and 300 denotes recording paper (an example of a recording medium).

[0157] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to the present embodiment is a toner cartridge that contains the toner according to the present embodiment and is detachably attached to an image forming apparatus. The toner cartridge contains replenishment toner to be supplied to a developing unit provided in the image forming apparatus.

[0158] 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to each developing device (color) by toner supply pipes (not shown). When the toner stored in a toner cartridge runs low, the toner cartridge is replaced. [Example]

[0159] Hereinafter, embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are based on mass.

[0160] <Synthesis of amorphous resin (a1-1)> Terephthalic acid: 90 parts by mole Fumaric acid: 10 mole parts Bisphenol A propylene oxide 2 mole adduct: 95 mole parts Neopentyl glycol: 5 parts by mole The above materials were placed in a flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column, and the temperature was raised to 210°C over 1 hour. 1 part of titanium tetraethoxide was then added for every 100 parts of the above materials. The temperature was raised to 230°C over 0.5 hours while distilling off the resulting water. The dehydration condensation reaction was continued at this temperature for 1 hour, and the reaction mixture was then cooled. In this way, an amorphous resin (a1-1) was obtained with a weight-average molecular weight (Mw) of 18,000 and an SP value calculated by the Fedors method of 10.20.

[0161] <Synthesis of amorphous resin (a2-1)> Terephthalic acid: 86 parts by mole Fumaric acid: 10 mole parts Trimellitic anhydride: 4 mole parts Bisphenol A propylene oxide 2 mole adduct: 15 mole parts Bisphenol A ethylene oxide 2 mole adduct: 10 mole parts 75 parts propylene glycol The above materials were placed in a flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column, and the temperature was raised to 210°C over 1 hour. 1 part of titanium tetraethoxide was then added to 100 parts of the above materials. The temperature was raised to 230°C over 0.5 hours while distilling off the resulting water. The dehydration condensation reaction was continued at this temperature for 2 hours, and the reaction mixture was then cooled. In this way, an amorphous resin (a2-1) was obtained with a weight-average molecular weight (Mw) of 65,000 and an SP value calculated by the Fedors method of 10.98.

[0162] <Synthesis of amorphous resin (a2-2)> Terephthalic acid: 96 parts Trimellitic anhydride: 4 parts Bisphenol A propylene oxide 2 mole adduct: 95 parts Neopentyl glycol: 5 parts Amorphous resin (a2-2) was obtained using the same specifications as for amorphous resin (a2-1), except that the above-mentioned materials were used.

[0163] <Synthesis of crystalline resin (c1-1)> Sebacic acid: 202 parts 1,6-Hexanediol: 118 parts Dibutyltin oxide (catalyst): 0.5 parts The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed for 5 hours at 180°C using mechanical stirring. In this way, a crystalline resin (c1-1) was obtained with a weight-average molecular weight (Mw) of 21,000 and an SP value calculated by the Fedors method of 9.19.

[0164] <Synthesis of amorphous resins (a1-2) to (a1-8)> Amorphous resins (a1-2) to (a1-8) were obtained in the same manner as for amorphous resin (a1-1), except that the raw materials were used in the manner shown in Table 1. Table 1 shows the SP value and Mw of each resin.

[0165] <Synthesis of amorphous resins (a2-2) to (a2-12)> Amorphous resins (a2-2) to (a2-12) were obtained in the same manner as for amorphous resin (a2-1), except that the raw materials were used in the manner shown in Table 1. Table 1 shows the SP value and Mw of each resin.

[0166] <Synthesis of crystalline resins (c1-2) to (c1-4)> Crystalline resins (c1-2) to (c1-4) were obtained in the same manner as for crystalline resin (c1-1), except that the raw materials were used in the manner shown in Table 2. Table 1 shows the SP value and Mw of each resin.

[0167] In Table 1, each item indicates the following compound. Note that blank spaces in Table 1 indicate that the corresponding material is not included. TPA: Terephthalic acid IPA: Isophthalic acid AA: Adipic acid TMA: Trimellitic anhydride BPA-2PO: Bisphenol A-propylene oxide 2 mole adduct BPA-3PO: Bisphenol A-propylene oxide 3-mol adduct BPA-2EO: Bisphenol A-ethylene oxide 2 mole adduct NPG: Neopentyl glycol PG: Propylene glycol

[0168] [Example 1] Amorphous polyester resin (a1-1): 60 parts Amorphous polyester resin (a2-1): 21 parts Crystalline polyester resin (c1-1): 7 parts Colorant 1 (carbon black, Mitsubishi Chemical #25): 7 parts Wax (paraffin wax, Nippon Seiro HNP9): 5 parts The above materials were mixed in a Henschel mixer (FM75L; manufactured by Nippon Coke and Engineering Co., Ltd.), then kneaded in a twin-screw kneading extruder (TEM-48SS; manufactured by Shibaura Machinery) at a temperature of 110°C and a screw rotation speed of 250 rpm, and the kneaded product was rolled and cooled. The kneaded product obtained was coarsely pulverized in a hammer mill, then pulverized in a jet mill (AFG; manufactured by Hosokawa Micron Corporation), and classified in an elbow jet classifier (EJ-LABO; manufactured by Nittetsu Mining Co., Ltd.) to obtain toner particles 1.

[0169] Toner particles 1:100 parts Sol-gel silica particles (number average particle size = 120 nm): 2.0 parts Strontium titanate particles (number average particle size = 50 nm): 0.2 parts The above materials were mixed in a Henschel mixer to obtain Toner 1.

[0170] [Examples 2 to 14, Example 19 and Comparative Examples 1 to 5] The toner of each example was obtained in the same manner as in Example 1, except that the type, content, etc. of each resin were set to the specifications shown in Tables 1 to 3.

[0171] [Example 15] Toner 15 was obtained in the same manner as in Example 1, except that the temperature during kneading was 100° C. and the rotation speed was 600 rpm.

[0172] [Example 16] Toner 16 was obtained in the same manner as in Example 1, except that the temperature during kneading was 100° C. and the rotation speed was 560 rpm.

[0173] [Example 17] Toner 17 was obtained in the same manner as in Example 1, except that the kneading temperature was 130° C. and the rotation speed was 200 rpm.

[0174] [Example 18] Toner 18 was obtained in the same manner as in Example 1, except that the kneading temperature was 130° C. and the rotation speed was 180 rpm.

[0175] The following properties were measured for the obtained toner of each example according to the methods already described. The results are shown in Table 3. In Table 3, "-" indicates that the respective material was not included. Weight average molecular weight Mw(a1) of amorphous resin a1 Weight average molecular weight Mw(a2) of amorphous resin a2 Weight average molecular weight Mw(c1) of amorphous resin c1 Mw(a2)-Mw(a1) Solubility parameter value (SP value) of amorphous resin a1 SP(a1) Solubility parameter value (SP value) of amorphous resin a2 SP(a2) Solubility parameter value (SP value) of crystalline resin c1 SP(c1) ·|SP(a1)-SP(c1)| / |SP(a2)-SP(c1)| ·|SP(a2)-SP(c1)| SP(a1) SP(a2) SP(c1) Crystalline resin c1 content in toner particles Crystalline resin c1 content relative to amorphous resin Coefficient of variation of the area of ​​Voronoi polygons Average diameter of the islands Amorphous resin content in toner particles Types of amorphous resins Crystalline resin types

[0176] Details of the abbreviations in Table 3 are shown below. PES: Polyester resin Hybrid: Hybrid resin with polyester resin segments and styrene-acrylic copolymer segments

[0177] (Evaluation of streak-like image defects) An Apeos C2570d multifunction printer manufactured by Fujifilm Business Innovation Co., Ltd. was placed in a 30°C environment, and the developer using each example toner was loaded into the developing device. Using this image forming device, 2,000 A4 images with an image density of 0.4% were continuously printed. An A4-sized full-page halftone image and a full-page text-only image were then printed, and the resulting images were visually evaluated for the presence or absence of streak-like image defects using the following criteria. The results are shown in Table 3. -Judgment criteria- A: Streaks have not yet developed. B: If you look closely, you can see slight lines, but it is acceptable. C: The presence of streaks can be seen slightly in halftone images, but this does not pose a problem in practice and is acceptable. D: The presence of streaks is clearly visible in halftone images and character images.

[0178] [Table 1]

[0179] [Table 2]

[0180] [Table 3]

[0181] From the above results, it was found that the present embodiment suppresses streaky image defects more effectively than the comparative example. [Explanation of symbols]

[0182] 1Y, 1M, 1C, 1K Photoconductor (an example of an image carrier) 2Y, 2M, 2C, 2K Charging roll (an example of charging means) 3. Exposure device (an example of an electrostatic image forming means) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (an example of developing means) 5Y, 5M, 5C, 5K Primary transfer roll (an example of a primary transfer means) 6Y, 6M, 6C, 6K: Photoconductor cleaning device (an example of a cleaning means) 8Y, 8M, 8C, 8K toner cartridges 10Y, 10M, 10C, 10K image forming units 20 Intermediate transfer belt (an example of an intermediate transfer body) 22 Drive Roll 24 Support Roll 26 Secondary transfer roll (an example of a secondary transfer means) 28 Fixing device (an example of fixing means) 30 Intermediate transfer body cleaning device P Recording paper (an example of a recording medium) 107 Photoconductor (an example of an image carrier) 108 Charging roll (an example of charging means) 109 Exposure device (an example of electrostatic image forming means) 111 Developing device (an example of developing means) 112 Transfer device (an example of transfer means) 113 Photosensitive drum cleaning device (an example of cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting Rail 117 Cabinet 118 Exposure opening 200 Process Cartridge 300 Recording paper (an example of a recording medium)

Claims

1. The toner particles contain a binder resin, the binder resin includes an amorphous resin including an amorphous resin a1 and an amorphous resin a2, and a crystalline resin including a crystalline resin c1, the toner particles have a sea-island structure including a sea portion containing the amorphous resin and an island portion containing the crystalline resin, and the island portion has an average diameter of 100 nm or more and 800 nm or less; The weight average molecular weight of the amorphous resin a1 is Mw(a1), The weight average molecular weight of the amorphous resin a2 is Mw(a2), The solubility parameter value (SP value) of the amorphous resin a1 is SP(a1), The solubility parameter value (SP value) of the amorphous resin a2 is SP(a2), When the solubility parameter value (SP value) of the crystalline resin c1 is SP(c1), the following formulas (1) and (2) are satisfied: The toner for developing electrostatic images has an Mw(a1) value of 12,000 or more and 22,000 or less. Formula (1): 10,000≦Mw(a2)−Mw(a1)≦150,000 Formula (2): |SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.9 2. The toner for developing electrostatic images according to claim 1, wherein the formula (1) further satisfies the following formula (1-3): Formula (1-3): 30,000≦Mw(a2)-Mw(a1)≦100,000

3. 3. The toner for developing electrostatic images according to claim 1, wherein the formula (2) further satisfies the following formula (2-2): Formula (2-2): 0.2≦|SP(a1)-SP(c1)| / |SP(a2)-SP(c1)|≦0.9

4. The toner for developing electrostatic images according to any one of claims 1 to 3, further satisfying the following formula (3): Formula (3): 0.8≦|SP(a2)−SP(c1)|≦2.5

5. 5. The toner for developing electrostatic images according to claim 1, wherein the content of the crystalline resin c1 is 2% by mass or more and 25% by mass or less with respect to the toner particles.

6. 6. The toner for developing electrostatic images according to claim 5, wherein the content of the crystalline resin c1 is 2% by mass or more and 40% by mass or less with respect to the amorphous resin.

7. 7. The toner for developing electrostatic images according to claim 1, wherein the content of the amorphous resin is 35% by mass or more and 95% by mass or less based on the toner particles.

8. 8. The toner for developing electrostatic images according to claim 1, wherein the amorphous resin comprises at least one of an amorphous polyester resin and a hybrid resin having a polyester resin segment and a styrene-acrylic copolymer segment.

9. 9. The toner for developing electrostatic images according to claim 1, wherein the crystalline resin comprises a crystalline polyester resin.

10. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 9.

11. A toner cartridge containing the toner for developing electrostatic images according to any one of claims 1 to 9, which is detachably mounted on an image forming apparatus.

12. 11. A process cartridge detachably mounted to an image forming apparatus, the process cartridge containing the electrostatic image developer according to claim 10 and comprising a developing unit that develops an electrostatic image formed on a surface of an image carrier using the electrostatic image developer into a toner image.

13. an image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; a developing unit containing the electrostatic image developer according to claim 10 and developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing means for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising:

Images