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

Abstract

To provide a toner for electrostatic charge image development that allows acquisition of good fixability and acquisition of a fixed image with a small image density unevenness between an area with a small toner placement amount and an area with a large toner placement amount.SOLUTION: A toner for electrostatic charge image development includes toner particles containing a binder resin. In dynamic viscoelasticity measurement of the toner, the loss elastic moduli G''5(150) and G''50(180) are 1×103 Pa or more and 1×104 Pa or less, respectively. The relationship between the loss elastic modulus G''5(t1) at a strain amount of 5% and a first temperature t1 within a temperature range of 150°C or more and 180°C or less, and the loss elastic modulus G''50(t2) at a strain amount of 50% and a second temperature t2 within a temperature range of 150°C or more and 180°C or less and higher than the first temperature t1 satisfies the following formula (1) when the temperature difference (t2-t1) between the first temperature t1 and the second temperature t2 is 15°C or more. Formula (1) 1<G''5(t1) / G''50(t2)<3.0.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a toner for developing electrostatic latent images, which includes toner particles containing a binder resin, and the binder resin contains an amorphous resin and a crystalline resin. The toner is characterized in that strain dispersion measurement of dynamic viscoelasticity is performed under conditions of a temperature of 130°C, a frequency of 1 Hz, and a strain amplitude of 1.0 to 500%, and when the integral value of stress in a stress-strain curve at a strain amplitude of 100% is S130 and the slope of the major axis is θ130, the S130 is more than 0 Pa and 350,000 Pa or less, and the θ130 is more than 22° and less than 90°.

[0003] Patent Document 2 discloses a toner for developing electrostatic images, which contains at least a binder resin and a release agent, characterized in that the binder resin contains at least a crystalline resin, and the toner has a storage modulus that satisfies a specific relationship when measured at a frequency of 1 Hz, at 150°C, and with a strain changed from 0.01% to 1000%.

[0004] Patent Document 3 discloses a toner for developing electrostatic latent images, which includes toner particles containing a binder resin, and the binder resin contains an amorphous vinyl resin and a crystalline resin. The toner is characterized in that strain dispersion measurement of dynamic viscoelasticity is performed under conditions of a temperature of 130°C, a frequency of 1 Hz, and a strain amplitude of 1.0 to 500%, and when the integral value of stress in a stress-strain curve at a strain amplitude of 100% is S130 and the slope of the major axis is θ130, the S130 is more than 0 Pa and 350,000 Pa or less, and the θ130 is 0° or more and less than 10°.

[0005] Patent Document 4 discloses a toner for developing electrostatic images, which contains toner base particles containing at least a binder resin and a release agent, and an external additive, wherein the binder resin contains at least a crystalline resin, and the peak top value of the loss tangent, tanδ6°C / min, measured from 25°C to 100°C at a frequency of 1 Hz and a temperature rise rate of 6°C / min, and the peak top value of the loss tangent, tanδ3°C / min, measured from 25°C to 100°C at a frequency of 1 Hz and a temperature rise rate of 3°C / min, satisfy a specific relationship.

[0006] Patent Document 5 describes a toner for developing electrostatic images containing at least a binder resin, a colorant, and a release agent, and the toner has a change rate γG' of storage modulus G' of 50%<γG'<86%, and a change rate γG" of loss modulus G" is greater than 50%, and the storage modulus G' of the toner in the range of 1 to 50% strain at a temperature of 150°C is 5×10 2 ~3.5×10 3 The toner for developing electrostatic images is disclosed, characterized in that the binder resin contains a non-crystalline resin and a crystalline resin.

[0007] Patent Documents 6 and 7 disclose a toner for developing electrostatic images, which is made of toner particles containing a binder resin, and in an elasticity image of a cross section of the toner particle taken by an atomic force microscope (AFM), the binder resin has a domain-matrix structure made of a high-elasticity resin that constitutes the domains and a low-elasticity resin that constitutes the matrix, and the arithmetic mean value of the ratio (L / W) of the major axis L to the minor axis W of each domain is in the range of 1.5 to 5.0, and 80% or more of the domains have a major axis L in the range of 60 to 500 nm, and 80% or more of the domains have a minor axis W in the range of 45 to 100 nm. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2020-042122 [Patent Document 2] Japanese Patent Publication No. 2020-106685 [Patent Document 3] Japanese Patent Publication No. 2020-042121 [Patent Document 4] Japanese Patent Application Publication No. 2019-144368 [Patent Document 5] Japanese Patent Application Laid-Open No. 2013-160886 [Patent Document 6] Japanese Patent Application Laid-Open No. 2011-237793 [Patent Document 7] Japanese Patent Application Laid-Open No. 2011-237792 Summary of the Invention [Problem to be solved by the invention]

[0009] In image formation using a toner for developing an electrostatic image, for example, a toner image transferred to a recording medium is fixed to the recording medium by applying heat and pressure. Here, when a toner for developing an electrostatic image containing toner particles that melt easily by heating is used to obtain good fixability, if a fixed image including an area with a low toner amount and an area with a high toner amount is formed, the image density may differ depending on the area, resulting in density unevenness in the image.

[0010] The object of the present invention is to provide a toner for developing electrostatic images that can obtain a fixed image with good fixing properties and less unevenness in image density between areas with a low toner amount and areas with a high toner amount, compared to when formula (1) is not satisfied. [Means for solving the problem]

[0011] The above problems can be solved by the following means. <1> toner particles containing a binder resin, In the dynamic viscoelasticity measurement of the toner for developing electrostatic images, The loss modulus G''5(150) at a temperature of 150°C and a strain of 5% and the loss modulus G''50(180) at a temperature of 180°C and a strain of 50% are 1 x 10 3 Pa or more 1×10 4 Pa or less, A toner for developing electrostatic images, wherein the relationship between the loss modulus G''5(t1) at a strain of 5% at a first temperature t1 in the temperature range of 150°C or higher and 180°C or lower and the loss modulus G''50(t2) at a strain of 50% at a second temperature t2 in the temperature range of 150°C or higher and 180°C or lower, which is higher than the first temperature t1, satisfies the following formula (1) when the temperature difference (t2-t1) between the first temperature t1 and the second temperature t2 is 15°C or higher: Formula (1) 1 <G’’5(t1) / G’’50(t2)<3.0 <2> the toner particles further contain resin particles, In the dynamic viscoelasticity measurement of the resin particles at a temperature rise of 2°C / min, the storage modulus G' in the range of 30°C to 180°C is 1 x 10 5 Pa or more 5×10 7 Pa or less <1> 2. The toner for developing electrostatic images according to claim 1. <3> In a dynamic viscoelasticity measurement of the resin particles at a temperature rise of 2°C / min, the loss tangent tanδ is 0.01 or more and 2.5 or less in a range of 30°C or more and 180°C or less. <2> 2. The toner for developing electrostatic images according to claim 1. <4> The number average particle diameter of the resin particles is 60 nm or more and 300 nm or less. <2> or <3> 2. The toner for developing electrostatic images according to claim 1. <5> The content of the resin particles is 2% by mass or more and 30% by mass or less with respect to the total mass of the toner particles. <2> ~ <4> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <6> The resin particles are crosslinked resin particles. <2> ~ <5> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <7> The crosslinked resin particles are styrene (meth)acrylic resin particles. <6> 2. The toner for developing electrostatic images according to claim 1. <8> the difference between the solubility parameter SP value (S) of the resin particles and the solubility parameter SP value (R) of the binder resin (SP value (S) - SP value (R)) is -0.32 or more and -0.12 or less; <2> ~ <7> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <9> In a dynamic viscoelasticity measurement of the components of the toner particles excluding the resin particles at a temperature rise of 2°C / min, the storage modulus G' in the range of 30°C to 50°C is 1 x 10 8 Pa or more, and the storage modulus G' is 1 x 10 5 The temperature at which the temperature at which the resistance reaches less than 100 Pa is 65°C or higher and 90°C or lower. <2> ~ <8> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <10> In the dynamic viscoelasticity measurement of the components excluding the resin particles from the toner particles at a temperature rise of 2°C / min, the storage modulus G' is 1 x 10 5 The loss tangent tanδ at a temperature reaching less than Pa is 0.8 or more and 1.6 or less, <9> 2. The toner for developing electrostatic images according to claim 1. <11> wherein logG'p is the common logarithm of the storage modulus G' in the range of 90°C to 180°C in a dynamic viscoelasticity measurement of the resin particles at a temperature rise of 2°C / min, and logG'r is the common logarithm of the storage modulus G' in the range of 90°C to 180°C in a dynamic viscoelasticity measurement of the toner particles excluding the resin particles at a temperature rise of 2°C / min, and the value of logG'p-logG'r is 1.0 to 4.0 <2> ~ <10> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <12> In the dynamic viscoelasticity measurement of the toner for developing electrostatic images at a temperature rise of 2°C / min, the storage modulus G' in the range of 30°C to 50°C is 1 x 10 8 Pa or more, and the storage modulus G' is 1 x 10 5 The temperature at which the temperature at which the resistance reaches less than 100 Pa is 70°C or higher and 90°C or lower. <1> ~ <11> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <13> the binder resin contains a crystalline resin, The content of the crystalline resin is 4% by mass or more and 50% by mass or less with respect to the total amount of the binder resin. <1> ~ <12> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <14> The binder resin contains a polyester resin. <1> ~ <13> 10. The toner for developing electrostatic images according to claim 9, wherein the toner is a toner for developing electrostatic images. <15> The aforementioned <1> ~ <14> 10. An electrostatic image developer comprising the toner for developing electrostatic images according to any one of claims 1 to 9. <16> The aforementioned <1> ~ <14> The toner for developing electrostatic images according to any one of the above items is contained in the container. A toner cartridge that is detachably attached to an image forming device. <17> The aforementioned <15> and a developing means for developing an electrostatic image formed on the surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge is detachably mounted in an image forming apparatus. <18> 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 <15> 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: <19> a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; The aforementioned <15> 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 claim 1; a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; An image forming method comprising the steps of: [Effects of the Invention]

[0012] <1> According to the invention relating to (1), a toner for developing electrostatic images is provided that can obtain a fixed image with good fixing properties and less unevenness in image density between areas with a low toner amount and areas with a high toner amount, compared to when formula (1) is not satisfied.

[0013] <2> According to the invention, when no resin particles are contained or when the storage modulus G' of the resin particles at 180°C is 1 x 10 5 In comparison with the case where the toner density is less than 1 Pa, a toner for developing an electrostatic image is provided which has less unevenness in image density between areas with a small amount of toner and areas with a large amount of toner. <3> According to the invention, a toner for developing electrostatic images is provided which has less unevenness in image density between areas with low toner loading and areas with high toner loading, compared to when the loss tangent tanδ of the resin particles at 180°C exceeds 2.5. <4> According to the invention, a toner for developing electrostatic images is provided which has less unevenness in image density between areas with a low toner loading amount and areas with a high toner loading amount, compared to when the number average particle size of the resin particles exceeds 300 nm. <5> According to the invention, a toner for developing electrostatic images is provided that has less unevenness in image density between areas with a low toner load and areas with a high toner load, compared to when the resin particle content is less than 2% by mass. <6> According to the invention, there is provided a toner for developing electrostatic images which has less unevenness in image density between areas with a low toner loading amount and areas with a high toner loading amount, compared to when the resin particles are non-crosslinked resin particles. <7> According to the invention, there is provided a toner for developing electrostatic images which has less unevenness in image density between areas with a low toner loading amount and areas with a high toner loading amount, compared to when the resin particles are polyester resin particles.

[0014] <8> According to the invention, a toner for developing electrostatic images is provided which has less unevenness in image density between areas with low toner loading and areas with high toner loading, compared to when the difference (SP value (S) - SP value (R)) is less than -0.32. <9> According to the invention, the storage modulus G' of the components excluding the resin particles from the toner particles is 1×10 5 When the temperature reaches less than 90°C, a toner for developing electrostatic images having good fixing properties is provided, as compared with a case where the temperature exceeds 90°C. <10> According to the invention, the storage modulus G' of the components excluding the resin particles from the toner particles is 1×10 5 Compared to when the loss tangent tanδ exceeds 1.6 at a temperature below 1 Pa, an electrostatic charge image developing toner is provided which has less unevenness in image density between regions with a low toner amount and regions with a high toner amount.

[0015] <11> According to the invention, a toner for developing electrostatic images is provided that achieves both good fixing properties and reduced image density unevenness between areas with low toner loading and areas with high toner loading, compared to when the value of logG'p-logG'r is less than 1.0. <12> According to the invention, the storage modulus G' of the toner for developing electrostatic images is 1×10 5 When the temperature reaches less than 90°C, a toner for developing electrostatic images having good fixing properties is provided, as compared with a case where the temperature exceeds 90°C. <13> According to the invention, a toner for developing electrostatic images is provided that has less unevenness in image density between areas with low toner loading and areas with high toner loading, compared to when the crystalline resin content exceeds 50% by mass. <14> According to the invention, a toner for developing electrostatic images having better fixability than a toner containing a binder resin made of a styrene acrylic resin is provided.

[0016] <15> , <16> , <17> , <18> , or <19> According to the invention, there is provided an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method that can obtain a fixed image with less unevenness in image density between areas with a low toner amount and areas with a high toner amount while obtaining good fixing properties compared to when a toner for developing an electrostatic image that does not satisfy formula (1) is used. [Brief explanation of the drawings]

[0017] [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

[0018] Hereinafter, an embodiment of the present invention will be described. These descriptions and examples are intended to illustrate the embodiment and are not intended to limit the scope of the invention. In the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of a numerical range may be replaced with a value shown in the examples. In this specification, (meth)acrylic means both acrylic and methacrylic.

[0019] 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. Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0020] [Electrostatic image developing toner] The electrostatic image developing toner (hereinafter also referred to as "toner") according to the present embodiment contains toner particles containing a binder resin, and in a dynamic viscoelasticity measurement of the electrostatic image developing toner, The loss modulus G''5(150) at a temperature of 150°C and a strain of 5% and the loss modulus G''50(180) at a temperature of 180°C and a strain of 50% are 1 x 10 3 Pa or more 1×10 4 Pa or less, The relationship between the loss modulus G''5(t1) when the strain is 5% at a first temperature t1 in the temperature range of 150°C or higher and 180°C or lower and the loss modulus G''50(t2) when the strain is 50% at a second temperature t2 in the temperature range of 150°C or higher and 180°C or lower that is higher than the first temperature t1 satisfies the following formula (1) when the temperature difference (t2-t1) between the first temperature t1 and the second temperature t2 is 15°C or higher.

[0021] Formula (1) 1 <G’’5(t1) / G’’50(t2)<3.0

[0022] Hereinafter, the toner having the above-described structure will also be referred to as "specific toner." Hereinafter, the area with a small amount of applied toner will be referred to as a "low-application area," and the area with a large amount of applied toner will be referred to as a "high-application area."

[0023] As mentioned above, a technique for using a toner for developing electrostatic images containing toner particles that melt easily upon heating is known to achieve good fixability. However, when an image is formed using a toner containing toner particles that melt easily upon heating, for example, during the fixing process, the toner particles melt and the viscosity becomes excessively low, which tends to weaken the cohesive force between the toner particles in the fixed image layer and reduce the strength of the fixed image layer. This can result in the surface of the fixed image becoming rough, such as partially adhering to the fixing member or the like and partially damaging the surface of the fixed image. Furthermore, when the pressure of the fixing roll is high, the cohesive force between the toner particles in the fixed image layer tends to further weaken, making the surface of the fixed image more susceptible to damage and making the roughness of the fixed image more noticeable. For example, if an image contains regions with different toner loading amounts and the roughness of the fixed image occurs, the roughness is difficult to see in the high-load areas, but is easily visible in the low-load areas, which is visually perceived as a difference in image density (image density unevenness) between the low-load areas and the high-load areas.

[0024] Furthermore, for example, when an image is formed using a toner containing toner particles that are difficult to melt by heating, the melting property of the toner particles in the lightly loaded area tends to be relatively low, and there tends to be both unmelted and molten areas within a single image, which results in a visible difference in image density (image density unevenness) between the lightly loaded area and the heavily loaded area.

[0025] The image density unevenness tends to be particularly noticeable when an image is formed using a recording medium with a large uneven surface, such as rough paper or embossed paper.

[0026] On the other hand, the electrostatic image developing toner according to the present embodiment, due to the above-described configuration, achieves good fixability while reducing image density unevenness between areas with low toner coverage and areas with high toner coverage in the fixed image. The reason for this is presumed to be as follows.

[0027] In the dynamic viscoelasticity measurement, the toner for developing electrostatic images according to the present embodiment has a loss modulus G''5(150) at a temperature of 150°C and a strain of 5%, and a loss modulus G''50(180) at a temperature of 180°C and a strain of 50%, both of which are 1×10 3 Pa or more 1×10 4 Pa or less. In other words, even when the specific toner is subjected to pressure at high temperatures by a fixing member or the like, the proportion of energy generated by pressure and strain that contributes to deformation of the toner particles is appropriate. Furthermore, the electrostatic image developing toner according to this embodiment satisfies the above formula (1). In other words, the specific toner has appropriate hardness, and the strain amount dependency of the storage modulus G' at temperatures of 150°C and 180°C is small. Therefore, even if the low-loading region becomes hotter than the high-loading region and is significantly affected by pressure, the amount of deformation of the toner particles in the low-loading region is prevented from becoming relatively large. As a result of the above, for example, even when a recording medium with large irregularities is used under high-temperature and high-pressure fixing conditions, it is believed that good fixing properties can be obtained and image density unevenness between areas with low toner loading and areas with high toner loading in the fixed image can be reduced, regardless of the toner loading.

[0028] (Toner characteristics) - Viscoelasticity of toner - In the dynamic viscoelasticity measurement of a specific toner, when the temperature is 150°C and the strain is 5%, the loss modulus is G''5(150), and G''5(150) is 1 x 10 3 Pa or more 1×10 4 Pa or less, and from the viewpoint of further reducing unevenness in image density between areas with a low toner amount and areas with a high toner amount in the fixed image, 3 Pa or more 8.0×10 3 Pa or less is more preferable, and 4.0 × 10 3 Pa or more 6.0×10 3 It is more preferable that the viscosity is 0.05 Pa or less.

[0029] In the dynamic viscoelasticity measurement of a specific toner, when the temperature is 180°C and the strain amount is 50%, the loss modulus is G''50(180), and G''50(180) is 1 x 10 3 Pa or more 1×10 4 Pa or less, and from the viewpoint of further reducing unevenness in image density between areas with a low toner amount and areas with a high toner amount in the fixed image, 3 Pa or more 5.0×10 3 Pa or less is more preferable, and 1.0 × 10 3 Pa or more 3.0×10 3 It is more preferable that the viscosity is 0.05 Pa or less.

[0030] In the dynamic viscoelasticity measurement of a specific toner, when the loss modulus G'' at a temperature of 150°C and a strain of 1% is defined as G''1(150), G''1(150) is 1 x 10 3 Pa over 1×10 5 Pa, and preferably less than 2.0 × 10 3 Pa or more 5.0×10 4 Pa or less is more preferable, and 4.0 × 10 3 Pa or more 1.0×10 4 It is more preferable that the viscosity is 0.05 Pa or less. In the dynamic viscoelasticity measurement of a specific toner, when the loss modulus G'' at a temperature of 150°C and a strain of 50% is defined as G''50(150), G''50(150) is 1 x 10 3 Pa over 1×10 5 Pa, and preferably less than 2.0 × 10 3 Pa or more 1.0×10 4 More preferably, it is less than 3.0×10 Pa. 3 Pa or more 5.0×10 3 It is more preferable that the viscosity is 0.05 Pa or less. In the dynamic viscoelasticity measurement of a specific toner, when the loss modulus G'' at a temperature of 180°C and a strain of 1% is defined as G''1(180), G''1(180) is 1 x 10 3 Pa over 1×10 5 Pa, and preferably less than 1.0 × 10 3 Pa or more 1.0×104 Pa or less is more preferable, and 2.0 × 10 3 Pa or more 5.0×10 3 It is more preferable that the viscosity is 0.05 Pa or less.

[0031] When G''1(150), G''50(150), and G''1(180) are within the above ranges, better fixing properties are obtained than when they are greater than the above ranges, and image density unevenness is reduced compared to when they are less than the above ranges.

[0032] The upper limit of G''50(150) / G''50(180) in the specific toner is preferably 2.2 or less, more preferably 2.0 or less, and even more preferably 1.8 or less. When the value of G''50(150) / G''50(180) is within the above range, image density unevenness is reduced compared to when the value is greater than the above range. The lower limit of G''50(150) / G''50(180) in the specific toner is preferably more than 1, and may be 1.2 or more, or may be 1.4 or more.

[0033] The upper limit of G''1(150) / G''50(180) in the specific toner is preferably 3.1 or less, more preferably 2.9 or less, and even more preferably 2.7 or less. When the upper limit of G''1(150) / G''50(180) is within the above range, image density unevenness is reduced compared to when the upper limit is greater than the above range. The lower limit of G''1(150) / G''50(180) in the specific toner is not particularly limited as long as it is greater than 1, and may be 1.2 or greater, or may be 1.5 or greater.

[0034] The value of G''1(180) / G''50(180) in the specific toner is preferably less than 1.5, more preferably 1.4 or less, and even more preferably 1.35 or less. When the value of G''1(180) / G''50(180) is in the above range, image density unevenness is reduced compared to when the value is greater than the above range. The value of G''1(180) / G''50(180) is not particularly limited as long as it is greater than 1, and may be 1.1 or greater, or 1.2 or greater.

[0035] The value of G''1(150) / G''1(180) in the specific toner is preferably less than 2.5, more preferably 2.3 or less, and even more preferably 2.2 or less. When the value of G''1(150) / G''1(180) is within the above range, image density unevenness is reduced compared to when the value is greater than the above range. The value of G''1(150) / G''1(180) is not particularly limited as long as it is greater than 1, and may be 1.5 or greater, or 1.8 or greater.

[0036] , G''5(150), G''50(180), G''1(150), G''50(150), G''1(180), G''50(180), G''50(150) / G''50(180) and G''1(150) / G''50(180) may be within the above ranges by any method without particular limitation, but examples thereof include a method in which the aforementioned specific resin particles are dispersed within toner particles.

[0037] For the specific toner, when the loss modulus G'' at a strain of 5% at any temperature t1 in the range of 150°C to 180°C is G''5(t1), G''5(t1) is 2.0 x 10 3 Pa or more 8.0×10 3 Pa or less, and 3 Pa or more 6.0×10 3 It is more preferable that G''5(t1) is equal to or less than Pa. When G''5(t1) is within the above range, unevenness in image density is reduced compared to when it is greater than the above range.

[0038] When the loss modulus G'' of the specific toner at a strain of 50% at a temperature t2 higher than the temperature t1 in the temperature range of 150°C or higher and 180°C or lower is defined as G''50(t2), G''50(t2) is 1.0 x 10 3 Pa or more 5.0×10 3Pa or less, and 1.0 × 10 3 Pa or more 3.0×10 3 It is more preferable that G''50(t2) is equal to or less than 100 Pa. When G''50(t2) is within the above range, unevenness in image density is reduced compared to when it is greater than the above range.

[0039] The specific toner has a loss modulus G''5(t1) at a strain of 5% at a first temperature t1 in the temperature range of 150°C or higher and 180°C or lower, and a loss modulus G''50(t2) at a strain of 50% at a second temperature t2 in the temperature range of 150°C or higher and 180°C or lower, which is higher than the first temperature t1, such that when the temperature difference (t2-t1) between the first temperature t1 and the second temperature t2 is 15°C or higher, the relationship satisfies the following formula (1): Formula (1) 1 <G’’5(t1) / G’’50(t2)<3.0 Formula (1-2) 1.20 <G’’5(t1) / G’’50(t2)<2.90 Formula (1-3) 1.30 <G’’5(t1) / G’’50(t2)<2.80 Formula (1-4) 1.40 <G’’5(t1) / G’’50(t2)<2.75 2.75

[0040] The temperature difference (t2-t1) between the first temperature t1 and the second temperature t2 is 15°C or more, and may be 15°C or more and 30°C or less, or 25°C or more and 30°C or less, or may be 30°C.

[0041] The loss modulus of the toner is determined as follows. Specifically, the toner to be measured is molded into a tablet shape at room temperature (25°C) using a press molding machine to prepare a measurement sample. Then, using this measurement sample, dynamic viscoelasticity measurement is carried out using a rheometer under the following conditions. From each of the resulting loss modulus curves, the loss modulus at each temperature and strain is determined. -Measurement conditions- Measurement device: Rheometer ARES-G2 (manufactured by TA Instruments) Measurement jig: 8mm parallel plate Gap: Adjusted to 3mm Frequency: 1Hz

[0042] The toner has a storage modulus G' of 1 x 10 in the range of 30°C to 50°C. 8 Pa or more, and the storage modulus G' is 1 x 10 5 The temperature at which the storage modulus G' reaches less than 1×10 Pa (i.e., the specific elastic modulus reaching temperature) is preferably 70° C. or higher and 90° C. or lower. A toner whose storage modulus G' satisfies the above condition has a high elastic modulus at low temperatures and a low elastic modulus at temperatures of 70° C. or higher and 90° C. or lower. Therefore, when the storage modulus G' of a toner satisfies the above condition, the storage modulus G' is 1×10 5 When the temperature reaches less than 90° C., the toner melts more easily by heating, resulting in better fixability, compared to when the temperature exceeds 90° C.

[0043] The storage modulus G' of the toner at 30°C to 50°C is 1×10 8 Pa or more, and 1 × 10 8 Pa or more 1×10 9 Pa is more preferable, and 2×10 8 Pa or more 6×10 8 It is more preferable that the viscosity is 0.05 Pa or less. When the storage modulus G' of the toner at 30°C or higher and 50°C or lower is within the above range, the toner has better storage stability than when the storage modulus G' is lower than the above range, and better fixability is more likely to be obtained than when the storage modulus G' is higher than the above range.

[0044] The temperature at which the toner reaches the specific elastic modulus is preferably 65°C or higher and 90°C or lower, more preferably 70°C or higher and 87°C or lower, and even more preferably 75°C or higher and 84°C or lower. When the specific elastic modulus reaching temperature of the toner is within the above range, the toner has better storage stability than when it is lower than the above range, and is more likely to have better fixability than when it is higher than the above range.

[0045] The storage modulus G' of the toner at 30° C. or higher and 50° C. or lower and the temperature at which the specific modulus is reached are determined as follows. Specifically, a measurement sample is prepared by molding the toner to be measured into a tablet shape at room temperature (25°C) using a press molding machine. The obtained measurement sample is then sandwiched between parallel plates with a diameter of 8 mm, and the measurement temperature is raised from 30°C to 180°C at a rate of 2°C / min with a strain of 0.1 to 100%, and dynamic viscoelasticity measurement is performed under the following conditions. The storage modulus G' is determined from the storage modulus and loss modulus curves obtained by the measurement. -Measurement conditions- Measurement device: Rheometer ARES-G2 (manufactured by TA Instruments) Measurement jig: 8mm parallel plate Gap: Adjusted to 3mm Frequency: 1Hz

[0046] There are no particular limitations on the specific method for setting the storage modulus G' and specific elastic modulus reaching temperature of the toner to the above ranges of 30°C or more and 50°C or less, but examples include a method in which the aforementioned specific resin particles are dispersed within the toner particles.

[0047] The method for obtaining the specific toner is not particularly limited. For example, the specific toner may be obtained by measuring the dynamic viscoelasticity at a temperature rise of 2°C / min, and determining whether the storage modulus G' in the range of 30°C to 180°C is 1×10 5 Pa or more 5×10 7 For example, resin particles having a viscosity of 100 Pa or less are dispersed in toner particles. The storage modulus G' in the range of 30°C to 180°C is 1 × 10 5 Pa or more 5×10 7 Resin particles having a viscosity of 0.1 Pa or less are also referred to as "specific resin particles." The reason why the specific toner can be more easily obtained by dispersing the specific resin particles in the toner particles is not clear, but is presumed to be as follows.

[0048] As mentioned above, the specific resin particles have a storage modulus G' of 1 x 10 even when the temperature is raised to 180°C. 5 Pa or more. In other words, the specific resin particles are particles with a high elastic modulus at high temperatures. Therefore, it is presumed that when the toner particles contain the specific resin particles, the loss elastic modulus of the toner as a whole at high temperatures and high strain amounts is less likely to become high, the temperature dependency and strain amount dependency of the loss elastic modulus are likely to become small, and the specific toner is more likely to be obtained.

[0049] The storage modulus G' and the loss tangent tan δ, which will be described later, of the resin particles are determined as follows. Specifically, pressure is applied to the resin particles to be measured to prepare a disk-shaped sample with a thickness of 2 mm and a diameter of 8 mm, which is used as the measurement sample. When measuring resin particles contained in toner particles, the resin particles are removed from the toner particles before preparing the measurement sample. Examples of methods for removing resin particles from toner particles include a method in which the toner particles are immersed in a solvent that dissolves the binder resin but not the resin particles, and the resin particles are removed by dissolving the binder resin in the solvent. The resulting disk-shaped sample is then sandwiched between parallel plates with a diameter of 8 mm, and the measurement temperature is raised from 30°C to 150°C at a rate of 2°C / min at a strain of 0.1 to 100%, and dynamic viscoelasticity measurement is performed under the following conditions: The storage modulus G' and loss tangent tanδ are determined from the storage modulus and loss modulus curves obtained by the measurement. -Measurement conditions- Measurement device: Rheometer ARES-G2 (manufactured by TA Instruments) Gap: Adjusted to 3mm Frequency: 1Hz

[0050] The toner according to this embodiment will be described in detail below.

[0051] The toner according to this embodiment contains toner particles and, if necessary, an external additive.

[0052] (toner particles) The toner particles contain at least a binder resin, and may contain other components as required. As described above, from the viewpoint of obtaining a specific toner, it is preferable that the toner particles further contain specific resin particles. Hereinafter, as an example of the toner particles contained in the specific toner, toner particles containing a binder resin and specific resin particles will be described. The toner particles are composed of, for example, a binder resin, specific resin particles, and, if necessary, a colorant, a release agent, and other additives.

[0053] -Binder resin- Examples of binder resins include homopolymers of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), and vinyl resins made of copolymers of two or more of these monomers. Examples of the binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin, mixtures of these with the vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These binder resins may be used alone or in combination of two or more.

[0054] The binder resin preferably contains a polyester resin. By including a polyester resin as the binder resin, when styrene (meth)acrylic resin particles are used as the specific resin particles, the difference between the solubility parameter SP value (S) of the specific resin particles described below and the solubility parameter SP value (R) of the binder resin (SP value (S) - SP value (R)) tends to fall within a preferred range. This makes it easier for the specific resin particles to disperse in the toner particles, thereby further reducing image density unevenness.

[0055] The binder resin preferably contains a crystalline resin and an amorphous resin. Here, the crystalline resin refers to a resin that exhibits a clear endothermic peak rather than a stepwise change in endothermic amount in differential scanning calorimetry (DSC). On the other hand, an amorphous resin is one that does not show a clear endothermic peak but only a stepwise endothermic change in thermal analysis measurement using differential scanning calorimetry (DSC), is a solid at room temperature, and becomes thermoplastic at temperatures above its glass transition temperature. 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.

[0056] 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.

[0057] Crystalline polyester resin The crystalline polyester resin may be, for example, a polycondensate of a polycarboxylic acid and a polyhydric alcohol. Note that, as the crystalline polyester resin, a commercially available product or a synthesized product may be used. Here, the crystalline polyester resin is preferably a polycondensate using a polymerizable monomer having a linear aliphatic group rather than a polymerizable monomer having an aromatic group, since it easily forms a crystalline structure.

[0058] 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.

[0059] 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.

[0060] Here, the polyhydric alcohol has an aliphatic diol content of 80 mol % or more, preferably 90 mol % or more.

[0061] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) 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."

[0062] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0063] The crystalline polyester resin can be obtained by a known manufacturing method, for example, in the same manner as the amorphous polyester.

[0064] When the toner particles contain a crystalline resin, the content of the crystalline resin relative to the total binder resin is preferably 4% by mass or more and 50% by mass or less, more preferably 6% by mass or more and 30% by mass or less, and even more preferably 8% by mass or more and 20% by mass or less. By having the crystalline resin content within the above range, better fixability can be obtained than when the content is less than the above range. Furthermore, by having the crystalline resin content within the above range, excessive thinning of the image density in the low-load area of ​​the fixed image due to an excessive amount of crystalline resin with relatively low elasticity can be suppressed compared to when the content is greater than the above range. As a result, image density unevenness can be reduced.

[0065] 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.

[0066] Amorphous polyester resin Examples of the amorphous polyester resin include a condensation polymer of a polycarboxylic acid and a polyhydric alcohol. Note that, as the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0067] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (such as 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 (such as cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (such as 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.

[0068] 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, preferred polyhydric alcohols are aromatic diols and alicyclic diols, and more preferred are aromatic diols. 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.

[0069] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°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."

[0070] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). Molecular weight measurements by GPC are performed using a Tosoh GPC HLC-8120GPC measuring device and a Tosoh TSKgel SuperHM-M (15 cm) column in THF solvent. The weight-average molecular weight and number-average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0071] The amorphous polyester resin can be obtained by a known manufacturing method, for example, by carrying out the reaction at a polymerization temperature of 180°C or higher and 230°C or lower, reducing the pressure in the reaction system as necessary, and removing water and alcohol generated during the condensation. If the raw material monomer is not soluble or compatible at the reaction temperature, a high-boiling solvent may be added as a solubilizer to dissolve it. In this case, the polycondensation reaction is carried out while distilling off the solubilizer. If a monomer with poor compatibility is present, it is advisable to first condense the poorly compatible monomer with the acid or alcohol to be polycondensed, and then polycondense the monomer with the main component.

[0072] The content of the binder resin is, for example, preferably 40% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and even more preferably 60% by mass to 85% by mass, based on the total mass of the toner particles.

[0073] -Specific resin particles- The specific resin particles have a storage modulus G' of 1 x 10 in the range of 30°C to 180°C in dynamic viscoelasticity measurement at a temperature rise of 2°C / min. 5 Pa or more 5×10 7 There are no particular limitations on the resin particles as long as they have a viscosity of 100 Pa or less. The storage modulus G' of the specific resin particles in the range of 30°C to 180°C is 1 x 10 5 Pa or more 2×10 7 Pa or less, and 1×10 5 Pa or more 1×10 7 It is more preferable that the viscosity is 0.05 Pa or less. By using resin particles having a storage modulus G' in the range of 30°C to 180°C inclusive within the above range, the decrease in image density in low-load areas of the fixed image is more suppressed than when resin particles having a storage modulus G' lower than the above range are used. This further reduces image density unevenness. Furthermore, by using resin particles having a storage modulus G' in the range of 30°C to 180°C inclusive within the above range, the decrease in fixability caused by the toner particles having too high elasticity is suppressed compared to when resin particles having a storage modulus G' higher than the above range are used, and good fixability is more likely to be obtained.

[0074] The specific resin particles preferably have a loss tangent tanδ of 0.01 or more and 2.5 or less in the range of 30°C to 180°C in dynamic viscoelasticity measurement at a temperature rise rate of 2°C / min, more preferably 0.01 or more and 1.0 or less, and even more preferably 0.01 or more and 0.5 or less, particularly at temperatures of 65°C to 150°C. By having the loss tangent tanδ of the specific resin particles in the above range in the range of 30°C or higher and 180°C or lower, the toner particles are more likely to deform during fixing, making it easier to obtain good fixing properties, compared to when the temperature is lower than the above range. Furthermore, by having the loss tangent tanδ of the specific resin particles in the above range in the range of 65°C or higher and 180°C or lower, at which the toner particles are more likely to deform, the decrease in image density in low-load areas of the fixed image is more suppressed, compared to when the temperature is higher than the above range. As a result, image density unevenness is further reduced.

[0075] The specific resin particles are preferably crosslinked resin particles. Here, the term "crosslinked resin particles" refers to resin particles that have a bridge structure between specific atoms in the polymer structure contained in the resin particles.

[0076] By using crosslinked resin particles as the specific resin particles, the specific resin particles tend to have a storage modulus G' within the range of 30° C. or higher and 180° C. or lower, and the specific toner is easily obtained.

[0077] Examples of the crosslinked resin particles include crosslinked resin particles crosslinked by ionic bonds (ionically crosslinked resin particles), crosslinked resin particles crosslinked by covalent bonds (covalently crosslinked resin particles), etc. Among these, crosslinked resin particles crosslinked by covalent bonds are preferred.

[0078] Examples of resins used in the crosslinked resin particles include polyolefin resins (polyethylene, polypropylene, etc.), styrene resins (polystyrene, α-polymethylstyrene, etc.), (meth)acrylic resins (polymethyl methacrylate, polyacrylonitrile, etc.), epoxy resins, polyurethane resins, polyurea resins, polyamide resins, polycarbonate resins, polyether resins, polyester resins, and copolymer resins thereof. These resins may be used alone or in combination of two or more types, as needed.

[0079] Of the above resins, styrene-(meth)acrylic copolymer resins are preferred as the resins used for the crosslinked resin particles. That is, the crosslinked resin particles are preferably styrene-(meth)acrylic copolymer resin particles.

[0080] When the crosslinked resin particles are styrene-(meth)acrylic copolymer resin particles, the specific resin particles tend to have a storage modulus G' within the range of 30° C. or higher and 180° C. or lower, and the specific toner tends to be obtained.

[0081] Examples of the styrene-(meth)acrylic copolymer resin include resins obtained by radical polymerization of the following styrene monomer and (meth)acrylic acid monomer.

[0082] Examples of styrene-based monomers include styrene, α-methylstyrene, vinylnaphthalene, alkyl-substituted styrenes having alkyl chains such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene, halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene, and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene, etc. Among these, styrene and α-methylstyrene are preferred.

[0083] Examples of (meth)acrylic acid monomers include (meth)acrylic acid, n-methyl (meth)acrylate, n-ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, amyl (meth)acrylate, (meth)acrylate, Examples of such acrylates include neopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, t-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, β-carboxyethyl (meth)acrylate, (meth)acrylonitrile, and (meth)acrylamide. Among these, n-butyl (meth)acrylate and β-carboxyethyl (meth)acrylate are preferred.

[0084] Examples of crosslinking agents for crosslinking the resin in the crosslinked resin particles include aromatic polyvinyl compounds such as divinylbenzene and divinylnaphthalene; polyvinyl esters of aromatic polycarboxylic acids such as divinyl phthalate, divinyl isophthalate, divinyl terephthalate, divinyl homophthalate, divinyl trimesate, trivinyl trimesate, divinyl naphthalenedicarboxylate, and divinyl biphenylcarboxylate; divinyl esters of nitrogen-containing aromatic compounds such as divinyl pyridinedicarboxylate; vinyl esters of unsaturated heterocyclic carboxylic acids such as vinyl pyromethane, vinyl furancarboxylate, vinyl pyrrole-2-carboxylate, and vinyl thiophenecarboxylate; and divinyl esters of butanediol diacrylate, butanediol dimethacrylate, hexanediol diacrylate, octanediol dimethacrylate, decanediol diacrylate, and dodecanediol dimethacrylate. Examples of suitable crosslinking agents include (meth)acrylic acid esters of branched or substituted polyhydric alcohols such as neopentyl glycol dimethacrylate and 2-hydroxy-1,3-diacryloxypropane; (meth)acrylic acid esters of branched or substituted polyhydric alcohols such as polyethylene glycol di(meth)acrylate, polypropylene polyethylene glycol di(meth)acrylates, and polyvinyl esters of polycarboxylic acids such as divinyl succinate, divinyl fumarate, vinyl maleate, divinyl maleate, divinyl diglycolate, vinyl itaconate, divinyl itaconate, divinyl acetonedicarboxylate, divinyl glutarate, divinyl 3,3'-thiodipropionate, divinyl trans-aconitate, trivinyl trans-aconitate, divinyl adipate, divinyl pimelate, divinyl suberate, divinyl azelaate, divinyl sebacate, divinyl dodecanedioate, and divinyl brassylate. These crosslinking agents may be used singly or in combination of two or more.

[0085] When the specific resin particles are polymers of a specific resin particle-forming composition containing a styrene-based monomer, a (meth)acrylic acid-based monomer, and a crosslinking agent, the viscoelasticity of the specific resin particles can be controlled by adjusting the amount of crosslinking agent contained in the composition. For example, increasing the amount of crosslinking agent contained in the composition makes it easier to obtain resin particles with a high storage modulus G'. The content of the crosslinking agent in the specific resin particle-forming composition is, for example, preferably 0.3 to 5.0 parts by mass, more preferably 0.5 to 2.5 parts by mass, and even more preferably 1.0 to 2.0 parts by mass, per 100 parts by mass of the total of the styrene-based monomer, the (meth)acrylic acid-based monomer, and the crosslinking agent.

[0086] The number average particle size of the specific resin particles is preferably 60 nm or more and 300 nm or less, more preferably 100 nm or more and 200 nm or less, and even more preferably 130 nm or more and 170 nm or less. By having the number-average particle diameter of the specific resin particles within the above range, the toner particles are more susceptible to the influence of the high elasticity of the specific resin particles, which suppresses the deterioration of fixability, and good fixability is obtained, compared to when the number-average particle diameter is smaller than the above range. Furthermore, by having the number-average particle diameter of the specific resin particles within the above range, the specific resin particles are more easily dispersed uniformly within the toner particles, compared to when the number-average particle diameter is larger than the above range, and the toner is more likely to have low temperature dependence and strain amount dependence of viscoelasticity. As a result, image density unevenness is reduced.

[0087] The number average particle size of the specific resin particles is a value measured using a transmission electron microscope (TEM). As a transmission electron microscope, for example, JEM-1010 manufactured by JEOL Datum Co., Ltd. can be used. Hereinafter, a method for measuring the number average particle diameter of the specific resin particles will be specifically described. Toner particles are cut into slices of approximately 0.3 μm thick using a microtome. The cross sections of the toner particles are photographed at 4,500x magnification using a transmission electron microscope, and the circular equivalent diameters of 1,000 resin particles dispersed in the toner particles are calculated from the individual cross-sectional areas, and the arithmetic average of these is used as the number-average particle diameter.

[0088] The specific resin particles are highly dispersible in the toner particles and form domains, It is preferable that the specific resin particles are present. This reduces image density unevenness compared to, for example, when the specific resin particles are present locally or without forming domains within the toner particles. For example, when the specific resin particles are contained only in the central region, the specific resin particles tend to be present unevenly in the toner-fixed image, and the area where the specific resin particles are present tends to have high elasticity. As a result, the area where the specific resin particles are not present has low elasticity, which may result in greater image density unevenness. Furthermore, when no domains are formed, the content of components other than the specific resin particles is higher, and the physical properties of these components become dominant, thereby reducing the effect of reducing image density unevenness. Therefore, when the specific resin particles are highly dispersible within the toner particles and form domains, it is presumed that image density unevenness is reduced, unlike when the specific resin particles are contained only in the central region.

[0089] The content of the specific resin particles is preferably 2% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 25% by mass or less, and even more preferably 8% by mass or more and 20% by mass or less, based on the total mass of the toner particles. By ensuring that the content of the specific resin particles is within the above range, the toner tends to have lower temperature dependence and strain amount dependence of viscoelasticity than when the content is below the above range, thereby reducing image density unevenness. Furthermore, by ensuring that the content of the specific resin particles is within the above range, the deterioration of fixability due to the toner particles having too high elasticity is suppressed compared to when the content is above the above range, and good fixability is obtained.

[0090] -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, ultramarine blue, and the like. Examples of the dye include various pigments such as phosphorus blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, and various 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.

[0091] 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.

[0092] The content of the colorant is, for example, 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.

[0093] -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.

[0094] The melting temperature of the release agent is preferably 50°C or higher and 110°C or lower, and more preferably 60°C or higher and 100°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" as described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0095] The content of the release agent is, for example, preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the total mass of the toner particles.

[0096] -Other additives- Examples of other additives include well-known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the toner particles as internal additives.

[0097] -Relationship between the composition of toner particles- Difference (SP value (S) - SP value (R)) The difference between the solubility parameter SP value (S) of the specific resin particles and the solubility parameter SP value (R) of the binder resin (SP value (S) - SP value (R)) is preferably -0.32 or more and -0.12 or less.

[0098] When the difference (SP value (S) - SP value (R)) is within the above range, the specific resin particles are more easily dispersed in a nearly uniform state within the toner particles, and the state of existence is easier to control, compared to when the difference is smaller than the above range. Therefore, when the specific resin particles are highly dispersed within the toner particles, the toner tends to have low temperature dependency and strain amount dependency of viscoelasticity, and image density unevenness is further reduced. Furthermore, when the difference (SP value (S) - SP value (R)) is within the above range, the increase in the melt viscosity of the entire toner due to excessive mixing and compatibility of the specific resin particles and the binder resin when the toner melts is suppressed compared to when the difference is greater than the above range. This has the advantage of suppressing a decrease in fixability due to excessively high viscoelasticity, thereby achieving good fixability. When the binder resin is a mixed resin, the solubility parameter of the resin with the highest content in the binder resin is taken as the SP value (R).

[0099] The difference (SP value (S) - SP value (R)) is more preferably -0.32 or more and -0.12 or less, and even more preferably -0.29 or more and -0.18 or less.

[0100] The solubility parameter SP value (S) of the specific resin particles is preferably 9.00 or more and 9.15 or less, more preferably 9.03 or more and 9.12 or less, and even more preferably 9.06 or more and 9.10 or less.

[0101] Here, the solubility parameter SP value (S) of the specific resin particles and the solubility parameter SP value (R) of the binder resin (unit: (cal / cm 3 ) 1 / 2 ) is calculated using the Okitsu method. The Okitsu method is described in detail in the Journal of the Adhesion Society of Japan, Vol. 29, No. 5 (1993).

[0102] Viscoelasticity of components excluding specific resin particles (excluded components) The storage modulus G' of the components excluding the specific resin particles from the toner particles in the range of 30°C to 50°C is 1 x 10 8 Pa or more, and the storage modulus G' is 1 x 10 5 The temperature at which the toner reaches a temperature of less than 10 Pa is preferably 65° C. or higher and 90° C. or lower. Hereinafter, the components excluding the specific resin particles from the toner particles are also referred to as “excluded components.” 5 The temperature at which the storage modulus G' of an excluded component satisfies the above condition is also called the "specific elastic modulus attainment temperature." The excluded component, whose storage modulus G' satisfies the above condition, has a high elastic modulus at low temperatures and a low elastic modulus at temperatures between 65°C and 90°C. Therefore, if the storage modulus G' of an excluded component satisfies the above condition, the storage modulus G' will be 1 x 10 5 When the temperature reaches less than 90° C., the toner particles are more easily melted by heating, resulting in better fixability, compared to when the temperature exceeds 90° C.

[0103] The storage modulus G' of the excluded components at temperatures between 30°C and 50°C is 1 x 10 8 Pa or more, and 1 × 10 8 Pa or more 1×10 9Pa or less is more preferable, and 2×10 8 Pa or more 6×10 8 It is more preferable that the viscosity is 0.05 Pa or less. When the storage modulus G' of the excluded component at 30°C or higher and 50°C or lower is within the above range, the toner has better storage stability than when it is lower than the above range, and better fixability is more likely to be obtained than when it is higher than the above range.

[0104] The temperature at which the specific elastic modulus is reached in the excluded components is preferably 65°C or higher and 90°C or lower, more preferably 68°C or higher and 80°C or lower, and even more preferably 70°C or higher and 75°C or lower. When the specific elastic modulus reaching temperature of the excluded component is within the above range, the toner has better storage stability than when the temperature is lower than the above range, and better fixability is more likely to be obtained than when the temperature is higher than the above range.

[0105] The loss tangent tan δ of the excluded component at the specific elastic modulus attainment temperature is preferably 0.8 or more and 1.6 or less, more preferably 0.9 or more and 1.5 or less, and even more preferably 1.0 or more and 1.4 or less. When the loss tangent tanδ of the excluded component at the specific elastic modulus reaching temperature is within the above range, better fixability is likely to be obtained than when the loss tangent tanδ is lower than the above range.Furthermore, when the loss tangent tanδ of the excluded component at the specific elastic modulus reaching temperature is within the above range, image density unevenness tends to be reduced compared to when the loss tangent tanδ is higher than the above range.

[0106] The storage modulus G' and loss tangent tan δ of the excluded component are determined as follows. Specifically, first, resin particles are removed from toner particles to extract only the removed components, and the removed components are then molded into tablets at 25° C. using a press molding machine to prepare a measurement sample. Examples of a method for removing resin particles from toner particles to extract only the removed components include a method in which the toner particles are immersed in a solvent that dissolves the binder resin but does not dissolve the resin particles, and the removed components are extracted and extracted. The obtained measurement sample is then sandwiched between parallel plates with a diameter of 8 mm, and the measurement temperature is raised from 30°C to 150°C at a rate of 2°C / min at a strain of 0.1 to 100%, and dynamic viscoelasticity measurement is performed under the following conditions: The storage modulus G' and loss tangent tanδ are determined from the storage modulus and loss modulus curves obtained by the measurement. -Measurement conditions- Measurement device: Rheometer ARES-G2 (manufactured by TA Instruments) Measurement jig: 8mm parallel plate Gap: Adjusted to 3mm Frequency: 1Hz

[0107] Relationship between specific resin particles and excluded components When the common logarithm of the storage modulus G' of the specific resin particles in the range of 90°C to 180°C is logG'p and the common logarithm of the storage modulus G' of the excluded component in the range of 90°C to 180°C is logG'r, the value of logG'p - logG'r is preferably 1.0 to 3.5, more preferably 1.1 to 3.4, and even more preferably 1.2 to 3.3. When the value of logG'p-logG'r is in the above range, both good fixability and reduced unevenness in image density are achieved, compared to when the value is smaller or larger than the above range.

[0108] -Characteristics of toner particles, etc.- 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. Here, the toner particles having a core-shell structure may be composed of, for example, a core containing a binder resin, specific resin particles, and, if necessary, other additives such as a colorant and a release agent, and a coating layer containing the binder resin and the specific resin particles.

[0109] When the toner particles have a core-shell structure, it is preferable that the specific resin particles are contained in at least the core layer, and the specific resin particles may be contained in both the core particles and the shell layer. When the specific resin particles are contained in both the core particles and the shell layer, it is preferable that the content of the specific resin particles in the core particles and the shell layer is approximately the same, from the viewpoint of further reducing unevenness in image density by making the specific resin particles highly dispersible in the toner particles.

[0110] 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.

[0111] 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% 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 for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size 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:

[0112] The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

[0113] 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. First, the toner particles to be measured are sucked and collected, forming a flat flow, and a still image of the particles is captured by instantaneously activating a strobe light, and the particle image is analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation).The number of samples to be sampled when calculating the average circularity is 3,500. 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.

[0114] (external additives) Examples of external additives include inorganic particles such as SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, KO, Na2O, ZrO2, CaO·SiO2, KO·(TiO2)n, Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0115] 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 10 parts by mass or less per 100 parts by mass of the inorganic particles.

[0116] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based polymers).

[0117] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less, based on the toner particles.

[0118] (Toner manufacturing method) Next, a method for producing the toner according to this embodiment will be described. The toner according to the exemplary embodiment can be obtained by producing toner particles and then externally adding an external additive to the toner particles, if necessary.

[0119] 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). The method for producing the toner particles is not particularly limited, and any well-known production method may be used. Among these, it is preferable to obtain toner particles by the aggregation and coalescence method.

[0120] Specifically, for example, when toner particles are produced by the aggregation and coalescence method, Toner particles are manufactured through the following steps: a step of preparing a resin particle dispersion in which resin particles that will become the binder resin are dispersed, and a specific resin particle dispersion in which the specific resin particles will become the specific resin particles (resin particle dispersion preparation step); a step of aggregating resin particles (and other particles, if necessary) in the resin particle dispersion (in a dispersion after mixing other particle dispersions, if necessary) to form aggregated particles (aggregated particle formation step); and a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed, fusing and coalescing the aggregated particles to form toner particles (fusion and coalescence step).

[0121] Each step will be described in detail below. In the following description, a method for obtaining toner particles containing a colorant and a release agent will be described, but the colorant and the release agent are used as needed. Of course, additives other than the colorant and the release agent may also be used.

[0122] -Resin particle dispersion preparation process- First, a resin particle dispersion in which resin particles serving as a binder resin are dispersed, as well as a colorant particle dispersion in which colorant particles are dispersed and a release agent particle dispersion in which release agent particles are dispersed are prepared.

[0123] Here, the resin particle dispersion liquid is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0124] Examples of the dispersion medium used in the resin particle dispersion include aqueous media. Examples of aqueous media include water such as distilled water and ion-exchanged water, alcohols, etc. These may be used alone or in combination of two or more.

[0125] Examples of surfactants include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly preferred. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants. The surfactants may be used alone or in combination of two or more.

[0126] In the resin particle dispersion, resin particles can be dispersed in a dispersion medium by a general dispersion method such as a rotary shear homogenizer, a ball mill having a medium, a sand mill, a dyno mill, etc. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion by, for example, a phase inversion emulsification method. The phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, adding a base to the organic continuous phase (O phase) to neutralize it, and then adding an aqueous medium (W phase), thereby converting the resin from W / O to O / W (so-called phase inversion) and forming a discontinuous phase, and dispersing the resin in particulate form in the aqueous medium.

[0127] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably from 0.01 μm to 1 μm, more preferably from 0.08 μm to 0.8 μm, and even more preferably from 0.1 μm to 0.6 μm. The volume average particle size of the resin particles is measured using a particle size distribution obtained by measurement with a laser diffraction particle size distribution analyzer (e.g., LA-700 manufactured by Horiba, Ltd.), and the cumulative distribution for the volume of the divided particle size range (channel) is subtracted from the small particle size side, and the particle size at which the cumulative 50% of all particles is measured is defined as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same way.

[0128] The content of resin particles contained in the resin particle dispersion is, for example, preferably from 5% by mass to 50% by mass, and more preferably from 10% by mass to 40% by mass.

[0129] Note that, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same for the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0130] Preparation of specific resin particle dispersion The specific resin particle dispersion may be prepared by any known method, such as emulsion polymerization, melt-kneading using a Banbury mixer or kneader, suspension polymerization, or spray drying, with emulsion polymerization being preferred.

[0131] From the viewpoint of setting the storage modulus G' and loss tangent tanδ of the specific resin particles within preferred ranges, it is preferred to use a styrene-based monomer and a (meth)acrylic acid-based monomer as the monomers and polymerize them in the presence of a crosslinking agent. In addition, in the production of the specific resin particles, it is preferable to carry out emulsion polymerization multiple times. The method for producing the specific resin particles will be described in more detail below.

[0132] The method for preparing the specific resin particle dispersion liquid is as follows: a step of obtaining an emulsion containing a monomer, a crosslinking agent, a surfactant, and water (emulsion preparation step); a step of adding a polymerization initiator to the emulsion and heating the emulsion to polymerize the monomers (first emulsion polymerization step); It is preferable to include a step (second emulsion polymerization step) of adding an emulsion containing a monomer and a crosslinking agent to the reaction solution after the first emulsion polymerization step and heating the mixture to polymerize the monomer.

[0133] -Emulsion preparation process- This is a step of obtaining an emulsion containing a monomer, a crosslinking agent, a surfactant, and water. It is preferable to obtain an emulsion by emulsifying the monomer, crosslinking agent, surfactant, and water using an emulsifier. Examples of emulsifiers include rotary agitators equipped with propeller-type, anchor-type, paddle-type, or turbine-type agitating blades, static mixers such as static mixers, rotor-stator emulsifiers such as homogenizers and Clearmix, mill-type emulsifiers equipped with a grinding function, high-pressure emulsifiers such as Manton-Gaulin pressure emulsifiers, high-pressure nozzle-type emulsifiers that generate cavitation under high pressure, high-pressure collision-type emulsifiers such as microfluidizers that apply shear force by causing liquids to collide with each other under high pressure, ultrasonic emulsifiers that generate cavitation using ultrasound, and membrane emulsifiers that emulsify uniformly through fine pores.

[0134] As the monomer, it is preferable to use a styrene-based monomer and a (meth)acrylic acid-based monomer. As the crosslinking agent, those already mentioned above are applicable.

[0135] Examples of surfactants include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants. Among these, anionic surfactants are preferred. The surfactants may be used alone or in combination of two or more.

[0136] The emulsion may contain a chain transfer agent. There are no particular limitations on the chain transfer agent, but a compound having a thiol component can be used. Specifically, alkyl mercaptans such as hexyl mercaptan, heptyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, and dodecyl mercaptan are preferred.

[0137] From the viewpoint of setting the storage modulus G' and loss tangent tanδ of the specific resin particles within a preferred range, the mass ratio of the styrene-based monomer to the (meth)acrylic acid-based monomer in the emulsion (styrene-based monomer / (meth)acrylic acid-based monomer) is preferably 0.2 or more and 1.1 or less. Furthermore, from the viewpoint of keeping the storage modulus G' and loss tangent tanδ of the specific resin particles within preferred ranges, the content of the crosslinking agent relative to the entire emulsion is preferably 0.5% by mass or more and 3% by mass or less.

[0138] -First emulsion polymerization process- This is a process in which a polymerization initiator is added to the emulsion and heated to polymerize the monomers. Here, when carrying out the polymerization, it is preferable to stir the emulsion (reaction solution) containing the polymerization initiator with a stirrer. Examples of the agitator include rotary agitators equipped with propeller-type, anchor-type, paddle-type, or turbine-type agitator blades. As the polymerization initiator, ammonium persulfate is preferably used. When a polymerization initiator is used, the viscoelasticity of the resulting specific resin particles may be controlled by adjusting the amount of the polymerization initiator added. For example, by reducing the amount of the polymerization initiator added, resin particles with a high storage modulus G' are more likely to be obtained.

[0139] -Second emulsion polymerization process- This is a step in which an emulsion containing a monomer is added to the reaction solution after the first emulsion polymerization step, and the mixture is heated to polymerize the monomer. During the polymerization, it is preferable to stir the reaction solution in the same manner as in the first emulsion polymerization step. In this step, the viscoelasticity of the resulting specific resin particles may be controlled by adjusting the time taken to add the emulsion containing the monomer. For example, extending the time taken to add the emulsion containing the monomer makes it easier to obtain resin particles with a high storage modulus G'. The time taken to add the emulsion containing the monomer can be, for example, in the range of 2 hours to 5 hours. In this step, the viscoelasticity of the resulting specific resin particles may be controlled by adjusting the temperature at which the reaction solution is stirred. For example, lowering the temperature at which the reaction solution is stirred makes it easier to obtain resin particles with a high storage modulus G'. The temperature at which the reaction solution is stirred may be, for example, in the range of 55°C to 75°C. The emulsion containing the monomer is preferably obtained by emulsifying the monomer, surfactant, and water using an emulsifier, for example.

[0140] -Agglomerated particle formation process- Next, the colorant particle dispersion, the release agent particle dispersion, and the specific resin particle dispersion are mixed together with the resin particle dispersion. Then, in the mixed dispersion, the resin particles, colorant particles, release agent particles, and specific resin particles are hetero-aggregated to form aggregated particles containing the resin particles, colorant particles, release agent particles, and specific resin particles, which have a diameter close to the diameter of the target toner particles.

[0141] Specifically, for example, an aggregating agent is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, a pH of 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. After that, the mixed dispersion is heated to the glass transition temperature of the resin particles (specifically, for example, a temperature of the glass transition temperature of the resin particles -30°C or more and the glass transition temperature -10°C or less), and the particles dispersed in the mixed dispersion are aggregated to form aggregated particles. In the aggregate particle formation step, for example, the mixed dispersion may be stirred with a rotary shear homogenizer, the above-mentioned aggregating agent may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to an acidic value (e.g., pH 2 or more and 5 or less), a dispersion stabilizer may be added as needed, and then the above-mentioned heating may be carried out.

[0142] In this step, the temperature of the mixed dispersion liquid when adding the aggregating agent may be adjusted to control the dispersion state of the specific resin particles in the resulting toner particles. For example, lowering the temperature of the mixed dispersion liquid improves the dispersibility of the specific resin particles. The temperature of the mixed dispersion liquid may be, for example, in the range of 5°C or higher and 40°C or lower. In this step, the dispersion state of the specific resin particles in the toner particles obtained may be controlled by adjusting the stirring speed after adding the aggregating agent. For example, by increasing the stirring speed after adding the aggregating agent, the dispersibility of the specific resin particles can be improved.

[0143] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. In particular, when a metal complex is used as the flocculant, the amount of surfactant used can be reduced and the charging characteristics can be improved. If necessary, an additive that forms a complex or a similar bond with the metal ions of the flocculant may be used, and a chelating agent is preferably used as this additive.

[0144] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. The chelating agent may be a water-soluble chelating agent, such as hydroxycarboxylic acid (e.g., tartaric acid, citric acid, gluconic acid), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), etc. The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, per 100 parts by mass of the resin particles.

[0145] -Fusion / coalescence process- Next, the aggregated particle dispersion liquid in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10 to 30°C higher than the glass transition temperature of the resin particles), to fuse and coalesce the aggregated particles and form toner particles.

[0146] Through the above steps, toner particles are obtained. After obtaining an aggregated particle dispersion in which aggregated particles are dispersed, the toner particles may be produced through the following steps: a step of further mixing the aggregated particle dispersion, a resin particle dispersion in which resin particles are dispersed, and a specific resin particle dispersion in which specific resin particles are dispersed, and aggregating the aggregated particles so that the resin particles and the specific resin particles adhere to the surfaces of the aggregated particles to form second aggregated particles; and a step of heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles to form toner particles having a core / shell structure.

[0147] In the step of forming the second aggregated particles, the addition of the resin particle dispersion and the specific resin particle dispersion and the adhesion of the resin particles and the specific resin particles to the surfaces of the aggregated particles may be repeated multiple times, thereby obtaining toner particles in which the specific resin particles are evenly contained in both the surface region and the center region of the toner particles.

[0148] In the fusion / coalescence process, the domain state of the specific resin particles in the resulting toner particles (more specifically, the aggregation state of the specific resin particles within the toner particles) may be controlled by adjusting the heating temperature and heating time. For example, by extending the heating time, the specific resin particles aggregate within the toner particles, making it easier to form a strong domain state. This allows for the formation of toner particles in which the contribution of the specific resin particles is greater due to better control of the dispersibility of the specific resin particles. Furthermore, by fusion / coalescence at a higher temperature (for example, a temperature 30°C or higher than the glass transition temperature of the resin particles), a strong domain state of the specific resin particles is formed, as described above.

[0149] After the fusion and coalescence process, the toner particles formed in the solution are subjected to a known washing process, a solid-liquid separation process, and a drying process to obtain dry toner particles. In the washing step, it is preferable to carry out sufficient replacement washing with ion-exchanged water from the viewpoint of electrostatic chargeability. Furthermore, the solid-liquid separation step is not particularly limited, but from the viewpoint of productivity, it is preferable to carry out suction filtration, pressure filtration, etc. Furthermore, in the drying step, there is no particular limitation on the method, but from the viewpoint of productivity, it is preferable to carry out freeze drying, flash drying, fluidized drying, vibration-type fluidized drying, etc.

[0150] 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, or the like. Furthermore, if necessary, coarse particles may be removed from the toner using a vibrating sieve, an air sieve, or the like.

[0151] <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.

[0152] 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.

[0153] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] <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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] 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).

[0166] 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.

[0167] 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.

[0168] 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 stirring 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 with the yellow toner image formed thereon continues to travel at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] 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.

[0175] <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.

[0176] 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.

[0177] 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.

[0178] 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).

[0179] 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.

[0180] 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]

[0181] Examples will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, all "parts" and "%" are by mass.

[0182] [Preparation of specific resin particle dispersion and comparative resin particle dispersion] <Preparation of specific resin particle dispersion 1> Styrene: 47.9 parts n-Butyl acrylate: 51.8 parts β-Carboxyethyl acrylate: 0.3 parts Anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company): 0.8 parts Butanediol diacrylate (crosslinking agent): 1.65 parts The above raw materials were mixed and dissolved, and 60 parts of ion-exchanged water was added thereto, followed by dispersion and emulsification in a flask to prepare an emulsion. Next, 1.3 parts of an anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company) was dissolved in 90 parts of ion-exchanged water, and 1 part of the emulsion was added thereto. Further, 10 parts of ion-exchanged water in which 5.4 parts of ammonium persulfate had been dissolved was added. The remainder of the emulsion was then added over 180 minutes, and the atmosphere in the flask was replaced with nitrogen.The solution in the flask was then heated to 65°C in an oil bath while stirring, and emulsion polymerization was continued for 500 minutes, after which specific resin particle dispersion 1 was obtained with a solids content adjusted to 24.5% by mass.

[0183] <Preparation of Specific Resin Particle Dispersions 2 to 9 and Comparative Resin Particle Dispersions C1 and C2> Specific resin particle dispersions 2 to 9 and comparative resin particle dispersions C1 and C2 were obtained in the same manner as for specific resin particle dispersion 1, except that the amount of styrene added, the amount of n-butyl acrylate added, the amount of acrylic acid added, the amount of β-carboxyethyl acrylate added, the amount of anionic surfactant dissolved in 90 parts of ion-exchanged water, the amount of butanediol diacrylate added (crosslinking agent in the table), the amount of ammonium peroxide added, the temperature heated in the oil bath (polymerization temperature in the table), the time when the remainder of the emulsion was added (addition time in the table), and the time when emulsion polymerization was continued after heating (retention time in the table) were as shown in Table 1.

[0184] The resin particles contained in the obtained specific resin particle dispersion and comparative resin particle dispersion were as follows: The minimum value ("G' (small)" in the table) and maximum value ("G' (large)" in the table) of storage modulus G' at 30°C or higher and 180°C or lower, the minimum value ("tanδ30-180 (small)" in the table) and maximum value ("tanδ30-180 (large)" in the table) of loss tangent tanδ at 30°C or higher and 180°C or lower, the minimum value ("tanδ65-180 (small)" in the table) and maximum value ("tanδ65-180 (large)" in the table) of loss tangent tanδ in the range of 65°C or higher and 180°C or lower, the number average particle size, and the SP value (S) were determined using the above-mentioned methods and the results are shown in Table 1.

[0185] [Table 1]

[0186] <Preparation of Amorphous Resin Particle Dispersion 1> Terephthalic acid: 28 parts Fumaric acid: 174 parts Bisphenol A ethylene oxide 2 mole adduct: 26 parts Bisphenol A propylene oxide 2 mole adduct: 542 parts The above materials were charged into a reaction vessel equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a rectification column, the temperature was raised to 190°C over 1 hour, and 1.2 parts of dibutyltin oxide was added per 100 parts of the above materials. The temperature was raised to 240°C over 6 hours while distilling off the produced water, and the dehydration condensation reaction was continued for 3 hours while maintaining the temperature at 240°C, after which the reaction product was cooled.

[0187] The reaction product was transferred in a molten state to a Cavitron CD1010 (manufactured by Eurotech) at a rate of 100 g per minute. At the same time, a separately prepared ammonia water with a concentration of 0.37 mass % was heated to 120°C in a heat exchanger and transferred to the Cavitron CD1010 at a rate of 0.1 L per minute. The rotor rotation speed was 60 Hz, and the pressure was 5 kg / cm. 2 The Cavitron CD1010 was operated under the conditions shown above to obtain a resin particle dispersion in which resin particles of an amorphous polyester resin having a volume average particle size of 175 nm were dispersed. Ion-exchanged water was added to the resin particle dispersion to adjust the solid content to 20 mass % to obtain Amorphous Resin Particle Dispersion 1. The SP value (R) of the obtained amorphous polyester resin was 9.43.

[0188] <Preparation of Amorphous Resin Particle Dispersion 2> Styrene: 72 parts n-Butyl acrylate: 27 parts β-Carboxyethyl acrylate: 1.3 parts Dodecanethiol: 2 parts The mixture obtained by mixing and dissolving the above materials was dispersed and emulsified in a flask with a surfactant solution prepared by dissolving 1.2 parts by weight of an anionic surfactant (TaycaPower, manufactured by Tayca Corporation) in 100 parts by weight of ion-exchanged water. Next, an aqueous solution prepared by dissolving 6 parts by weight of ammonium persulfate in 50 parts by weight of ion-exchanged water was added to the flask over a period of 20 minutes while stirring. After nitrogen substitution, the contents of the flask were heated in an oil bath with stirring until the temperature reached 75°C, and the temperature was maintained at 75°C for 4 hours to continue emulsion polymerization. This resulted in a resin particle dispersion containing amorphous styrene-acrylic resin particles with a volume-average particle size of 160 nm and a weight-average molecular weight of 56,000. Ion-exchanged water was added to this resin particle dispersion to adjust the solids content to 31.4% by weight, resulting in amorphous resin particle dispersion 2. The SP value (R) of the obtained amorphous styrene acrylic resin was 9.14.

[0189] <Preparation of Crystalline Resin Particle Dispersion> 1,10-dodecanedioic acid: 225 parts 1,6-Hexanediol: 143 parts The above materials were charged into a reaction vessel equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column. The temperature was raised to 160°C over 1 hour, and 0.8 parts by mass of dibutyltin oxide was added. The temperature was raised to 180°C over 6 hours while distilling off the produced water, and the dehydration condensation reaction was continued for 5 hours while maintaining the temperature at 180°C. The temperature was then gradually raised to 230°C under reduced pressure, and stirring was continued for 2 hours while maintaining the temperature at 230°C. The reaction product was then cooled. After cooling, solid-liquid separation was performed, and the solid was dried to obtain a crystalline polyester resin.

[0190] Crystalline polyester resin: 100 parts Methyl ethyl ketone: 40 parts Isopropyl alcohol: 30 parts 10% ammonia solution: 6 parts The above materials were added to a 3-liter jacketed reactor (Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, thermometer, water dripper, and anchor blade. The resin was dissolved by stirring at 100 rpm while maintaining the temperature at 80°C in a water-circulating thermostatic bath. The water-circulating thermostatic bath was then set to 50°C, and a total of 400 parts of ion-exchanged water maintained at 50°C was added dropwise at a rate of 7 parts by mass / min to induce phase inversion, yielding an emulsion. 576 parts by mass of the resulting emulsion and 500 parts by mass of ion-exchanged water were placed in a 2-liter recovery flask and placed in an evaporator (Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. The recovery flask was heated in a 60°C hot water bath while rotating, and the pressure was reduced to 7 kPa, taking care to avoid bumping, to remove the solvent. The volume average particle size (D50v) of the resin particles in this dispersion was 185 nm. Thereafter, ion-exchanged water was added to obtain a crystalline resin particle dispersion liquid with a solid content concentration of 22.1% by mass.

[0191] <Preparation of Colorant Dispersion> Cyan pigment (Dainichi Seikagaku Co., Ltd., Pigment Blue 15:3 (copper phthalocyanine)): 98 parts Anionic surfactant (Tayca Power manufactured by Tayca Corporation): 2 parts Ion-exchanged water: 420 parts The above ingredients were mixed and dissolved, and dispersed for 10 minutes using a homogenizer (IKA Ultra Turrax), to obtain a colorant dispersion having a median particle size of 164 nm and a solid content of 21.1% by mass.

[0192] <Preparation of release agent dispersion> Synthetic wax (Nippon Seiro Co., Ltd., FNP92, melting temperature Tw: 92°C): 50 parts Anionic surfactant (Tayca Power manufactured by Tayca Corporation): 1 part Ion-exchanged water: 200 parts The above materials were mixed and heated to 130°C, dispersed using a homogenizer (Ultra Turrax T50 manufactured by IKA), and then dispersed using a Manton-Gaulin high-pressure homogenizer (manufactured by Gaulin) to obtain a release agent dispersion liquid (solid content 20% by mass) in which release agent particles were dispersed. The volume average particle size of the release agent particles was 214 nm.

[0193] Example 1 ·Amorphous resin particle dispersion 1: 169 parts ·Specified resin particle dispersion liquid 1: 33 parts ·Crystalline resin particle dispersion: 53 parts Release agent dispersion: 25 parts Colorant dispersion: 33 parts Anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company): 4.8 parts The above raw materials, the liquid temperature of which was adjusted to 10°C, were placed in a 3 L cylindrical stainless steel container and dispersed and mixed for 2 minutes while applying shear force at 4000 rpm using a homogenizer (IKA, Ultra Turrax T50). Next, 1.75 parts of a 10% aqueous solution of aluminum sulfate in nitric acid as a flocculant was gradually added dropwise, and the homogenizer was rotated at 10,000 rpm for 10 minutes to disperse and mix, thereby obtaining a raw material dispersion.

[0194] The raw material dispersion was then transferred to a polymerization kettle equipped with a stirrer using two paddle stirrers and a thermometer, and the stirring speed was set to 550 rpm and heating was started using a mantle heater to promote the growth of aggregated particles at 40°C. The pH of the raw material dispersion was controlled in the range of 2.2 to 3.5 using 0.3 M nitric acid and 1 M aqueous sodium hydroxide. The pH was maintained within this range for approximately 2 hours to form aggregated particles. Next, a dispersion liquid obtained by mixing 1:21 parts of amorphous resin particle dispersion and 1:8 parts of specific resin particle dispersion was added, and the mixture was maintained for 60 minutes, allowing the binder resin particles and specific resin particles to adhere to the surfaces of the aggregated particles. The temperature was further increased to 53°C, and then 1:21 parts of amorphous resin particle dispersion was added, and the mixture was maintained for 60 minutes, allowing the binder resin particles to adhere to the surfaces of the aggregated particles.

[0195] The aggregated particles were adjusted while checking the particle size and shape using an optical microscope and a Multisizer 3. Thereafter, the pH was adjusted to 7.8 using a 5% aqueous sodium hydroxide solution, and the mixture was maintained for 15 minutes. Thereafter, the pH was increased to 8.0 to fuse the aggregated particles, and the temperature was then raised to 95°C. After confirming that the aggregated particles had fused using an optical microscope, heating was stopped after 6 hours, and the mixture was cooled at a rate of 1.0°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles 1.

[0196] 100 parts of the obtained toner particles and 0.7 parts of dimethyl silicone oil-treated silica particles (RY200 manufactured by Nippon Aerosil Co., Ltd.) were mixed in a Henschel mixer to obtain Toner 1.

[0197] <Examples 2 to 11, Comparative Examples C1 and C2> Toners 2 to 11 and Toners C1 to C2 were obtained in the same manner as Toner 1, except that instead of Specific Resin Particle Dispersion 1, specific resin particle dispersions or comparative resin particle dispersions of the types shown in Table 2 were used in amounts such that the content of resin particles (i.e., specific resin particles or comparative resin particles) relative to the total toner particles would be the value shown in Table 2.

[0198] <Examples 12 to 14> Toners 12 to 14 were obtained in the same manner as Toner 1, except that the amount of crystalline resin particle dispersion added was adjusted so that the content of the crystalline resin relative to the total binder resin would be the value shown in the table.

[0199] Example 15 Toner 15 was obtained in the same manner as Toner 1, except that instead of using Amorphous Resin Particle Dispersion 1, an Amorphous Resin Particle Dispersion of the type shown in the table was used in the amount shown in the table.

[0200] Example 16 Toner 16 was obtained in the same manner as Toner 1, except that the rotation speed of the homogenizer was changed from 10,000 rpm to 5,000 rpm.

[0201] Example 17 Toner 17 was obtained in the same manner as Toner 1, except that the amount of the crystalline resin particle dispersion added was adjusted so that the content of the crystalline resin relative to the total binder resin would be the value shown in the table.

[0202] Example 18 Toner 18 was obtained in the same manner as Toner 1, except that specific resin particle dispersion 1 was used in an amount such that the content of specific resin particles relative to all toner particles was the value shown in the table, and the amount of crystalline resin particle dispersion added was adjusted so that the content of crystalline resin relative to all binder resins was the value shown in the table.

[0203] Example 19 Toner 19 was obtained in the same manner as Toner 1, except that the pH during the fusion of the aggregated particles was changed from 8.0 to 9.0.

[0204] Example 20 Toner 20 was obtained in the same manner as Toner 1, except that the pH during the fusion of the aggregated particles was changed from 8.0 to 5.5.

[0205] Example 21 ·Amorphous resin particle dispersion 1: 169 parts ·Crystalline resin particle dispersion: 53 parts Release agent dispersion: 25 parts Colorant dispersion: 33 parts Anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company): 4.8 parts The above raw materials, the liquid temperature of which was adjusted to 30°C, were placed in a 3 L cylindrical stainless steel container and dispersed and mixed for 2 minutes while applying shear force at 4000 rpm using a homogenizer (IKA Ultra Turrax T50). Next, 1.75 parts of a 10% aqueous nitric acid solution of polyaluminum chloride as a flocculant was slowly added dropwise, and the homogenizer was rotated at 4000 rpm for 3 minutes (a shorter time than in the examples) to disperse and mix the mixture to obtain a raw dispersion.

[0206] The raw material dispersion was then transferred to a polymerization kettle equipped with a stirrer using two paddle stirrers and a thermometer, and the stirring speed was set to 550 rpm and heating was started using a mantle heater to promote the growth of aggregated particles at 40°C. The pH of the raw material dispersion was controlled in the range of 2.2 to 3.5 using 0.3 M nitric acid and 1 M aqueous sodium hydroxide. The pH was maintained within this range for approximately 2 hours to form aggregated particles. Next, a dispersion liquid obtained by mixing 1:42 parts of amorphous resin particle dispersion liquid and 1:41 parts of specific resin particle dispersion liquid was divided into two halves and added in two portions. The mixture was then held for 60 minutes, and the resin particles of the binder resin and the specific resin particles were allowed to adhere to the surfaces of the aggregated particles.

[0207] The aggregated particles were adjusted while checking the particle size and shape using an optical microscope and a Multisizer 3. Thereafter, the pH was adjusted to 7.8 using a 5% aqueous sodium hydroxide solution, and the mixture was maintained for 15 minutes. Thereafter, the pH was increased to 8.0 to fuse the aggregated particles, and the temperature was raised to 85°C. After confirming that the aggregated particles had fused using an optical microscope, heating was stopped after 2 hours, and the mixture was cooled at a rate of 1.0°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles C5.

[0208] 100 parts of the obtained toner particles and 0.7 parts of dimethyl silicone oil treated silica particles (RY200 manufactured by Nippon Aerosil Co., Ltd.) were mixed in a Henschel mixer to obtain Toner 21.

[0209] Example 22 Toner 22 was obtained in the same manner as Toner 1, except that the temperature during fusion in Example 1 was changed from 95° C. to 85° C., the pH from 8.0 to 7.0, and the time from 6 hours to 2 hours.

[0210] <Comparative Example C3> ·Amorphous resin particle dispersion 1: 169 parts ·Specified resin particle dispersion liquid 1: 33 parts ·Crystalline resin particle dispersion: 53 parts Release agent dispersion: 25 parts Colorant dispersion: 33 parts Anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company): 4.8 parts The above raw materials, the liquid temperature of which was adjusted to 30°C, were placed in a 3 L cylindrical stainless steel container and dispersed and mixed for 2 minutes while applying shear force at 4000 rpm using a homogenizer (IKA Ultra Turrax T50). Next, 1.75 parts of a 10% aqueous solution of aluminum sulfate in nitric acid as a flocculant was slowly added dropwise, and the homogenizer was rotated at 4000 rpm for 3 minutes (a shorter time than in the examples) to disperse and mix the mixture to obtain a raw dispersion.

[0211] The raw material dispersion was then transferred to a polymerization kettle equipped with a stirrer using two paddle stirrers and a thermometer, and the stirring speed was set to 550 rpm and heating was started using a mantle heater to promote the growth of aggregated particles at 40°C. The pH of the raw material dispersion was controlled in the range of 2.2 to 3.5 using 0.3 M nitric acid and 1 M aqueous sodium hydroxide. The pH was maintained within this range for approximately 2 hours to form aggregated particles. Next, a dispersion liquid obtained by mixing 1:21 parts of amorphous resin particle dispersion and 1:8 parts of specific resin particle dispersion was added, and the mixture was maintained for 60 minutes, allowing the binder resin particles and specific resin particles to adhere to the surfaces of the aggregated particles. The temperature was further increased to 53°C, and then 21 parts of amorphous resin particle dispersion was added, and the mixture was maintained for 60 minutes, allowing the binder resin particles to adhere to the surfaces of the aggregated particles.

[0212] The aggregated particles were adjusted while checking the particle size and shape using an optical microscope and a Multisizer 3. Thereafter, the pH was adjusted to 7.8 using a 5% aqueous sodium hydroxide solution, and the mixture was maintained for 15 minutes. The pH was then increased to 8.0 to fuse the aggregated particles, and the temperature was then raised to 85°C. After confirming that the aggregated particles had fused using an optical microscope, heating was stopped after 2 hours, and the mixture was cooled at a rate of 1.0°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles C3.

[0213] 100 parts of the obtained toner particles and 0.7 parts of dimethyl silicone oil treated silica particles (RY200 manufactured by Nippon Aerosil Co., Ltd.) were mixed in a Henschel mixer to obtain toner C3.

[0214] <Comparative example C4> ·Amorphous resin particle dispersion 1: 169 parts ·Specified resin particle dispersion 1: 41 parts ·Crystalline resin particle dispersion: 53 parts Release agent dispersion: 25 parts Colorant dispersion: 33 parts Anionic surfactant (Dowfax2A1, manufactured by The Dow Chemical Company): 4.8 parts The above raw materials, the liquid temperature of which was adjusted to 30°C, were placed in a 3 L cylindrical stainless steel container and dispersed and mixed for 2 minutes while applying shear force at 4000 rpm using a homogenizer (IKA Ultra Turrax T50). Next, 1.75 parts of a 10% aqueous solution of aluminum sulfate in nitric acid as a flocculant was slowly added dropwise, and the homogenizer was rotated at 4000 rpm for 3 minutes (a shorter time than in the examples) to disperse and mix the mixture to obtain a raw dispersion.

[0215] The raw material dispersion was then transferred to a polymerization kettle equipped with a stirrer using two paddle stirrers and a thermometer, and the stirring speed was set to 550 rpm and heating was started using a mantle heater to promote the growth of aggregated particles at 40°C. The pH of the raw material dispersion was controlled in the range of 2.2 to 3.5 using 0.3 M nitric acid and 1 M aqueous sodium hydroxide. The pH was maintained within this range for approximately 2 hours to form aggregated particles. Next, 1:42 parts of the amorphous resin particle dispersion liquid was added and the mixture was kept for 60 minutes, so that the resin particles of the binder resin were adhered to the surfaces of the aggregated particles.

[0216] The aggregated particles were adjusted while checking the particle size and shape using an optical microscope and a Multisizer 3. Thereafter, the pH was adjusted to 7.8 using a 5% aqueous sodium hydroxide solution, and the mixture was maintained for 15 minutes. The pH was then increased to 8.0 to fuse the aggregated particles, and the temperature was then raised to 85°C. After confirming that the aggregated particles had fused using an optical microscope, heating was stopped after 2 hours, and the mixture was cooled at a rate of 1.0°C / min. The mixture was then sieved through a 20 μm mesh, washed repeatedly with water, and dried in a vacuum dryer to obtain toner particles C4.

[0217] 100 parts of the obtained toner particles and 0.7 parts of dimethyl silicone oil treated silica particles (RY200 manufactured by Nippon Aerosil Co., Ltd.) were mixed in a Henschel mixer to obtain toner C4.

[0218] Table 2 shows the type of specific resin particle dispersion or comparative resin particle dispersion in the obtained toner ("Particle type" in the table), the content of specific resin particles or comparative resin particles relative to the entire toner particles ("Particle content (%)" in the table), the content of crystalline resin relative to the entire toner particles ("Crystalline content (%)" in the table), and the type of amorphous resin particle dispersion ("Amorphous type" in the table).

[0219] The storage modulus G' (indicated as "G' (Pa)" in the table) of the excluded components in the range of 30°C or higher and 50°C or lower, the temperature at which the specific elastic modulus is reached (indicated as "Temperature reached (°C)" in the table), and the loss tangent tanδ (indicated as "tanδ" in the table) at the specific elastic modulus temperature were determined using the methods described above. The results are shown in Table 2.

[0220] The loss moduli G''5(150), G''50(180), G''1(150), G''50(150), G''1(180), ratio G''50(150) / G''50(180) ("Ratio 50(150-180)" in the table), and ratio G''1(180) / G''50(180) ("Ratio 1-50(180)" in the table) of the obtained toner are shown in Tables 3 and 4, respectively. Tables 3 and 4 show the minimum and maximum values ​​of the loss modulus G''5(t1) at 5% strain at 150°C (t1) (G''5(t1)min and G''5(t1)max in the tables), the minimum and maximum values ​​of the loss modulus G''50(t2) at 50% strain at 180°C (t2) (G''50(t2)min and G''50(t2)max in the tables, the ratio of the minimum values ​​of the loss modulus (G''5(t1) / G''50(t2)min), and the ratio of the maximum values ​​of the loss modulus (G''5(t1) / G''50(t2)max), respectively. The temperature difference (t2-t1) between the first temperature t1 and the second temperature t2 was 30°C. In Tables 3 and 4, the part after E in each loss modulus value represents an exponential function. For example, in Table 3, the value of G''5(t1)min in Example 1, "4.2E+0.3", indicates 4200. The storage modulus G' in the range of 30°C or higher and 50°C or lower ("G'(30-50)" in the table), the temperature at which a specific modulus is reached ("Temperature reached (°C)" in the table), and the value of logG'p-logG'r ("Difference in viscoelasticity" in the table) of the obtained toner were determined using the methods described above, and the results are shown in Tables 3 and 4, respectively.

[0221] [Preparation of developer] 8 parts of the obtained toner and 100 parts of the following carrier were mixed to obtain a developer.

[0222] -Creating a carrier- Ferrite particles (average particle size 50 μm) 100 parts Toluene 14 parts Styrene / methyl methacrylate copolymer (copolymerization ratio 15 / 85) 3 parts Carbon black 0.2 parts The above components except for the ferrite particles were dispersed in a sand mill to prepare a dispersion, and this dispersion was placed in a vacuum degassing kneader together with the ferrite particles, and the mixture was dried under reduced pressure while stirring to obtain a carrier.

[0223] [evaluation] <Image density unevenness> The obtained developer was filled into the developing unit of a color copier ApeosPortIV C3370 (manufactured by Fujifilm Business Innovation Co., Ltd.) from which the fixing unit had been removed, and a toner loading amount of 0.30 mg / cm was measured on a 50 mm x 50 mm sheet. 2 The area where the toner amount is 0.90 mg / cm is 50 mm x 50 mm. 2 An unfixed image was output, including areas where the toner was not fixed (high-load areas). The image density of the output image was 100%. The recording medium used was Lezac 66 paper, 12 inches x 18 inches (basis weight 151 gsm), manufactured by Fujifilm Business Innovation Co., Ltd.

[0224] The fixing evaluation device used was an ApeosPortIV C3370 manufactured by Fujifilm Business Innovation Co., Ltd., with the fixing unit removed and modified so that the nip pressure and fixing temperature could be changed. The process speed was 175 mm / sec. Under these conditions, the unfixed image was fixed under high temperature and high pressure conditions (specifically, the temperature of the fixing unit was 180° C., and the nip pressure was 6.0 kgf / cm 2 ) to obtain a fixed image. The image density in the lightly loaded area and the heavy loaded area of ​​the obtained fixed image were measured using an image densitometer X-Rite 938 (manufactured by X-Rite Corporation). The difference in image density between the lightly loaded area and the heavy loaded area was determined, and the image density unevenness was evaluated according to the following criteria. The results are shown in Tables 3 and 4. A: The image density difference is 0.2 or less and is not visible. B: The image density difference is more than 0.2 and 0.25 or less, and is difficult to see. C: The image density difference is more than 0.25 and not more than 0.3, which is within the allowable range. D: The image density difference exceeds 0.3 and is outside the allowable range.

[0225] <Fixation> In the evaluation of image density unevenness, the heavy-loaded area of ​​the fixed image was bent using a weight, and the image quality was evaluated based on the degree of image loss in that area. The evaluation criteria were as follows, and the results are shown in Tables 3 and 4. G1: No image defects were observed. G2: Image defects were observed, but were minor. G3: Slight image defects were observed, but within acceptable limits. G4: Image defects are observed and are outside the acceptable range. G5: Significant image defects are observed and are outside the acceptable range.

[0226] [Table 2]

[0227] [Table 3]

[0228] [Table 4]

[0229] From the above results, it can be seen that the toner of this example can obtain a fixed image with good fixing properties and small image density unevenness between areas with a small amount of toner and areas with a large amount of toner. [Explanation of symbols]

[0230] 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 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) P Recording paper (an example of a recording medium)

Claims

1. toner particles containing a binder resin, the binder resin contains a polyester resin, the toner particles further contain resin particles, the resin particles are crosslinked resin particles, the crosslinked resin particles are styrene (meth)acrylic resin particles, In a dynamic viscoelasticity measurement of the resin particles at a temperature rise rate of 2°C / min, the storage modulus G' is 1 x 105 Pa or more and 5 x 107 Pa or less in the range of 30°C or more and 180°C or less; a content of the resin particles is 2% by mass or more and 30% by mass or less with respect to the total mass of the toner particles, In the dynamic viscoelasticity measurement of the toner for developing electrostatic images, The loss modulus G''5(150) at a temperature of 150°C and a strain of 5% and the loss modulus G''50(180) at a temperature of 180°C and a strain of 50% are each 1 x 10 ３ Pa or more 1×10 ４ Pa or less, A toner for developing electrostatic images, wherein the relationship between a loss modulus G''5(t1) at a strain of 5% at a first temperature t1 in the temperature range of 150°C or higher and 180°C or lower and a loss modulus G''50(t2) at a strain of 50% at a second temperature t2 in the temperature range of 150°C or higher and 180°C or lower, which is higher than the first temperature t1, satisfies the following formula (1) when a temperature difference (t2-t1) between the first temperature t1 and the second temperature t2 is 15°C or higher: Formula (1) 1<G''5(t1) / G''50(t2)<3.0

2. 2. The toner for developing electrostatic images according to claim 1, wherein the resin particles have a loss tangent tanδ of 0.01 to 2.5 in a dynamic viscoelasticity measurement at a temperature rise of 2°C / min in a range of 30°C to 180°C.

3. 3. The toner for developing electrostatic images according to claim 1, wherein the number average particle diameter of the resin particles is 60 nm or more and 300 nm or less.

4. 4. The toner for developing electrostatic images according to claim 1, wherein a difference between a solubility parameter SP value (S) of the resin particles and a solubility parameter SP value (R) of the binder resin (SP value (S) - SP value (R)) is -0.32 or more and -0.12 or less.

5. In a dynamic viscoelasticity measurement of the components excluding the resin particles from the toner particles at a temperature rise of 2° C. / min, the storage modulus G′ in the range of 30° C. to 50° C. is 1×10 ８ Pa or more, and the storage modulus G' is 1×10 ５ 5. The toner for developing electrostatic images according to claim 1, wherein the temperature at which the toner reaches a value of less than 100 Pa is 65° C. or higher and 90° C. or lower.

6. In the dynamic viscoelasticity measurement of the components excluding the resin particles from the toner particles at a temperature rise of 2° C. / min, the storage modulus G′ is 1×10 ５ 6. The toner for developing electrostatic images according to claim 5, wherein the loss tangent tan δ at a temperature reaching a pressure of less than 100 Pa is 0.8 or more and 1.6 or less.

7. In the dynamic viscoelasticity measurement of the resin particles at a temperature rise of 2°C / min, the common logarithm of the storage modulus G' in the range of 90°C to 180°C is represented by logG'p.

7. The toner for developing electrostatic images according to claim 1, wherein, in a dynamic viscoelasticity measurement of components excluding the resin particles from the toner particles, when the common logarithm of the storage modulus G' in the range of 90°C to 180°C is defined as log G'r, the value of log G'p - log G'r is 1.0 to 4.

0.

8. In the dynamic viscoelasticity measurement of the toner for developing electrostatic images at a temperature rise of 2° C. / min, the storage modulus G′ in the range of 30° C. to 50° C. is 1×10 ８ Pa or more, and the storage modulus G' is 1×10 ５ The toner for developing electrostatic images according to any one of claims 1 to 7, wherein the temperature at which the toner reaches a value of less than Pa is 70°C or higher and 90°C or lower.

9. the binder resin contains a crystalline resin, 9. The toner for developing electrostatic images according to claim 1, wherein the content of the crystalline resin is 4% by mass or more and 50% by mass or less with respect to the total amount of the binder 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 for developing electrostatic images according to any one of claims 1 to 9 is contained therein, A toner cartridge that is detachably attached to an image forming device.

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

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:

14. a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; a developing step of developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer according to claim 10; a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; An image forming method comprising the steps of:

Images