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 prevents a variation in image glossiness occurring when solid images are repeatedly formed on a small and thick recording medium in a low humidity environment.SOLUTION: A toner for electrostatic charge image development has toner particles including first toner particles having a luminance of less than 90 and second toner particles having a luminance of 90 or more. The ratio of the second toner particles to the toner particles is 0.1 number% or more and 10 number% or less. In the particle size distribution of the second toner particles, the ratio of particles having a particle diameter equal to or less than the number average particle diameter Dn of the toner particles is 70 number% or more.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] Methods for visualizing image information, such as electrophotography, are currently used in various fields. In electrophotography, an electrostatic image is formed as image information on the surface of an image carrier by charging and forming an electrostatic image. Then, a toner image is formed on the surface of the image carrier by a developer containing a toner, and the toner image is transferred to a recording medium, and then fixed to the recording medium. Through these steps, the image information is visualized as an image.

[0003] For example, Patent Document 1 discloses "a yellow toner in which the number of binder resin particles having a shape factor SF1 of 110 or less, not including a colorant and a releasing agent, is 50 or less per 5,000 particles of toner for developing electrostatic charges."

[0004] Furthermore, Patent Document 2 discloses a magenta toner in which "the number of binder resin particles having a shape factor SF1 of 110 or less, not including a colorant and a releasing agent, is 50 or less per 5,000 particles of the toner for developing electrostatic charges."

[0005] Furthermore, Patent Document 3 discloses "a toner in which a crystalline polyester exists as a domain in the toner, and a colorant is dispersed inside the crystalline polyester domain."

[0006] Furthermore, Patent Document 4 discloses "a toner containing a styrene-acrylic resin and a crystalline resin, in which the average dispersion diameter of the colorant is within the range of 100 to 400 nm."

[0007] Furthermore, Patent Document 5 discloses "a magenta toner which contains a specific colorant and in which the cross-sectional length of the crystal of the crystalline polyester in the cross section of the toner particle is 50 nm or less." [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2010-249919 A [Patent Document 2] JP 2010-249918 A [Patent Document 3] JP 2012-078423 A [Patent Document 4] JP 2018-087901 A [Patent Document 5] JP 2019-101279 A Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide a toner for developing electrostatic images, which has toner particles including first toner particles having a brightness of less than 90 and second toner particles having a brightness of 90 or more, and which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low-humidity environment, compared to a case in which the ratio of second toner particles to toner particles is less than 0.1% by number, or the ratio of particles having a number average particle size Dn or less in the particle size distribution of the second toner particles is less than 70%. [Means for solving the problem]

[0010] Means for solving the above problems include the following aspects.

[0011] <1> having toner particles including first toner particles having a brightness of less than 90 and second toner particles having a brightness of 90 or more; a ratio of the second toner particles to the toner particles is 0.1% by number or more and 10% by number or less; The electrostatic image developing toner, wherein the rate of particles having a number average particle diameter Dn or less of the toner particles in the particle size distribution of the second toner particles is 70% by number or more. <2> The second toner particles have a higher average circularity than the first toner particles. <1> 2. The toner for developing electrostatic images according to claim 1 . <3> The difference in average circularity between the first toner particles and the second toner particles is 0.01 or more. <2> 2. The toner for developing electrostatic images according to claim 1 . <4> The average circularity of the first toner particles is 0.930 or more and 0.960 or less. <2> or <3> 2. The toner for developing electrostatic images according to claim 1 . <5> The first toner particles and the second toner particles contain an amorphous resin and a crystalline resin as a binder resin. <1> ~ <4> 2. The toner for developing an electrostatic image according to claim 1 . <6> the crystalline resin is a crystalline polyester resin, The melting temperature of the crystalline polyester resin is 60° C. or higher and 110° C. or lower. <5> 2. The toner for developing electrostatic images according to claim 1 . <7> When cross sections of the first toner particle and the second toner particle are observed, an area ratio Ss of the domain of the crystalline resin to a cross-sectional area of ​​the second toner particle is larger than an area ratio Sf of the domain of the crystalline resin to a cross-sectional area of ​​the first toner particle. <5> or <6> 2. The toner for developing electrostatic images according to claim 1 . <8> a relationship between an area ratio Sf of the domain of the crystalline resin to a cross-sectional area of ​​the first toner particle and an area ratio Ss of the domain of the crystalline resin to a cross-sectional area of ​​the second toner particle satisfies Ss / Sf≧1.2 <7> 2. The toner for developing electrostatic images according to claim 1 . <9> The area ratio Ss of the domain of the crystalline resin to the cross-sectional area of ​​the second toner particle is 50% or more and 80% or less. <7> or <8> 2. The toner for developing electrostatic images according to claim 1 . <10> <1> ~ <9> 2. An electrostatic image developer comprising the toner for developing electrostatic images according to claim 1. <11> <1> ~ <9> The toner for developing an electrostatic image according to any one of claims 1 to 4 is contained in the container. A toner cartridge that is detachably attached to an image forming apparatus. <12> <10> and a developing unit which develops an electrostatic image formed on a surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge that is detachably attached to 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; <10> 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 a 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 a surface of an image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; <10> 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 1; a transfer step of transferring the toner image formed on the surface of the image carrier onto a surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; The image forming method according to claim 1, Effect of the Invention

[0012] <1> According to the invention, there is provided a toner for developing electrostatic images, which has toner particles including first toner particles having a brightness of less than 90 and second toner particles having a brightness of 90 or more, and which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low-humidity environment, compared to a case in which the ratio of second toner particles to toner particles is less than 0.1% by number, or the ratio of particles having a number average particle size Dn or less in the particle size distribution of the second toner particles is less than 70%. <2> According to the present invention, there is provided a toner for developing electrostatic images which suppresses fluctuations in image glossiness that occur when solid images are repeatedly formed on a small and thick recording medium in a low humidity environment, compared to a case in which the average circularity of second toner particles is smaller than that of the first toner particles. <3> According to the present invention, there is provided a toner for developing electrostatic images which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low-humidity environment, compared to a case in which the difference in average circularity between the first toner particles and the second toner particles is less than 0.01. <4> According to the present invention, there is provided a toner for developing electrostatic images which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low humidity environment, compared to when the average circularity of the first toner particles is less than 0.930 or exceeds 0.960.

[0013] <5> According to the present invention, there is provided a toner for developing electrostatic images which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low-humidity environment, compared to when the first toner particles and the second toner particles contain only an amorphous resin as a binder resin. <6> According to the present invention, there is provided a toner for developing electrostatic images which suppresses fluctuations in image glossiness that occur when solid images are repeatedly formed on a small and thick recording medium in a low-humidity environment, as compared to when the melting temperature of the crystalline polyester resin is less than 60°C or more than 110°C.

[0014] <7> According to the invention, there is provided a toner for developing electrostatic images which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low-humidity environment, compared to a case in which the area ratio Ss of the crystalline resin domain to the cross-sectional area of ​​the second toner particle is smaller than the area ratio Sf of the crystalline resin domain to the cross-sectional area of ​​the first toner particle when the cross-sections of the first toner particle and the second toner particle are observed. <8> According to the invention, there is provided a toner for developing electrostatic images which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low-humidity environment, compared to a case in which the relationship between the area ratio Sf of the crystalline resin domain to the cross-sectional area of ​​the first toner particle and the area ratio Ss of the crystalline resin domain to the cross-sectional area of ​​the second toner particle does not satisfy Ss / Sf≧1.2. <9> According to the present invention, a toner for developing electrostatic images is provided which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low humidity environment, compared to when the area ratio Ss of the crystalline resin domain to the cross-sectional area of ​​the second toner particle is less than 50% or exceeds 80%.

[0015] <10> , <11> , <12> , <13> or <14> 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, which suppresses fluctuations in image glossiness that occur when a solid image is repeatedly formed on a small and thick recording medium in a low-humidity environment, compared to a case in which an electrostatic image developing toner having toner particles including first toner particles having a brightness of less than 90 and second toner particles having a brightness of 90 or more is used, and in which the ratio of second toner particles to toner particles is less than 0.1% by number, or the ratio of particles having a number average particle diameter Dn or less in the particle size distribution of the second toner particles is less than 70%. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram illustrating an example of a process cartridge that is detachably mounted to the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described as an example. These descriptions and examples are for illustrating the present invention, but are not intended to limit the present invention.

[0018] In this specification, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in another stepwise manner. In addition, in the numerical ranges described in this disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[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, so long as the intended purpose of the process is achieved.

[0020] When an embodiment is described with reference to the drawings in this specification, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0021] In the present specification, each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified.

[0022] In the present specification, the particles corresponding to each component may include multiple types. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0023] In this specification, "toner for developing electrostatic images" is also referred to simply as "toner", and "electrostatic image developer" is also referred to simply as "developer".

[0024] <Toner for developing electrostatic images> The toner according to this embodiment has toner particles including first toner particles (hereinafter also referred to as “colored toner particles”) having a brightness of less than 90, and second toner particles (hereinafter also referred to as “transparent toner particles” for convenience) having a brightness of 90 or more. The ratio of transparent toner particles to the total toner particles is 0.1% by number or more and 10% by number or less, In the particle size distribution of the transparent toner particles, the proportion of particles having a number average particle size Dn or less of the toner particles is 70% by number or more.

[0025] The toner according to the present embodiment, with the above-described configuration, suppresses the fluctuation in image glossiness that occurs when a solid image is repeatedly formed on a small and thick recording medium in a low humidity environment. The reason for this is presumed to be as follows.

[0026] In a low temperature environment (for example, at 8°C), a solid image (for example, with a toner load of 5 g / m2) is printed on a small and thick recording medium (cardboard such as a postcard or postcard). 2 When the above-mentioned images are repeatedly formed, the image gloss may vary within an image on the same recording medium or between images on different recording media. This is believed to be due to temperature unevenness within the fixing member or temperature unevenness in the control temperature of the fixing device.

[0027] Conventionally, in toner particles containing a colorant, the colorant may form a network structure during heating and melting, and become elastic. In this case, the occurrence of elasticity depends on temperature, so when the fixing temperature fluctuates, the elasticity of the toner particles changes, and the unevenness of the image surface fluctuates, which causes the image glossiness to be temperature-dependent. In contrast, conventionally, it has been considered to reduce the viscosity change with temperature change and reduce the temperature dependency of the image glossiness by controlling the crosslinked structure or molecular weight distribution of the binder resin in the toner particles. However, it is difficult to eliminate the viscosity change with temperature change, and still, the image glossiness may fluctuate.

[0028] In contrast, in the toner according to this embodiment, toner particles including colored toner particles having a brightness of less than 90 and transparent toner particles having a brightness of 90 or more are used. Here, colored toner particles having a brightness of less than 90 are ordinary colored toner particles having low brightness and containing a colorant, while transparent toner particles having a brightness of 90 or more are substantially colorless or transparent toner particles having high brightness and containing no colorant or containing a colorant in an amount of 1% by mass or less based on the binder resin. That is, the transparent toner particles are less likely to be elasticized by the colorant, and have relatively lower elasticity than the colored toner particles. When transparent toner particles having such properties are small, with the ratio of particles having a number-average particle diameter Dn or less being 70% or more by number, and exist in a low amount, with the ratio to the total toner particles being 0.1% or more and 10% or less by number, they will exist between the colored toner particles during fixing. In this way, even if there are differences in the unevenness of the surface of the toner image, the transparent toner particles melt and penetrate so as to fill the gaps between the colored toner particles due to the pressure during fixing. This makes the image smooth regardless of the melting state of the colored toner particles, and as a result, the image glossiness becomes less dependent on the fixing temperature, and fluctuations in the image glossiness are suppressed even when solid images are repeatedly formed on a small and thick recording medium in a low humidity environment.

[0029] From the above, it is presumed that the toner according to this embodiment suppresses the fluctuation in image glossiness that occurs when a solid image is repeatedly formed on a small and thick recording medium in a low humidity environment.

[0030] The toner according to this embodiment will be described in detail below.

[0031] The toner according to the exemplary embodiment includes toner particles, and may include an external additive that is added to the toner particles.

[0032] [Toner particles] The toner particles include colored toner particles having a brightness of less than 90 and clear toner particles having a brightness of 90 or more.

[0033] (Toner particle number ratio) The ratio of transparent toner particles to toner particles (i.e., all toner particles) is 0.1% by number or more and 10% by number or less, but from the viewpoint of suppressing fluctuations in image glossiness, it is preferably 2% by number or more and 9% by number or less, and more preferably 4% by number or more and 8% by number or less. The ratio of colored toner particles to the total toner particles (that is, the total toner particles) corresponds to the ratio of toner particles other than transparent toner particles.

[0034] In the particle size distribution of transparent toner particles, the ratio of toner particles (that is, all toner particles) having a number average particle size Dn or less is 70% by number or more, preferably 80% by number or more, and more preferably 90% by number or more. In the particle size distribution of transparent toner particles, the upper limit of the proportion of toner particles (that is, all toner particles) having a number average particle size Dn or less is ideally 100% by number.

[0035] The number average particle diameter Dn of the toner particles (that is, all the toner particles) is preferably 3 μm or more and 7 μm or less, more preferably 3.5 μm or more and 6.5 μm or less, and further preferably 4 μm or more and 6 μm or less.

[0036] The number average particle size Dn of the toner particles (that is, all the toner particles), and the particle size distribution and ratio of the transparent toner are measured as follows.

[0037] The toner particles to be measured are sucked and collected, formed into a flat flow, and a still image of the particles is captured by instantly emitting a strobe light. The particle size and shape are then determined using a wet flow type particle size and shape analyzer (FPIA-3000; manufactured by Malvern Panalytical) which performs image analysis. Specifically, a particle image of the toner particles to be measured is obtained, and the particle size distribution of the toner particles is calculated based on the particle size (circle equivalent diameter) of the obtained particle image. Based on the particle size distribution thus obtained, a cumulative distribution is drawn from the small diameter side on a numerical basis, and the particle size at which the cumulative 50% is reached is calculated as the number-average particle size Dn of the toner particles. Based on the circle equivalent diameter and brightness of the obtained particle images, particle images corresponding to transparent toner particles are selected, and the number of transparent toner particles is counted. Based on this, the ratio of transparent toner particles to toner particles (i.e., all toner particles) is calculated. Based on the circle equivalent diameter and brightness of the obtained particle image, the particle image corresponding to the transparent toner particle is selected, and the particle size distribution of the transparent toner particles is obtained. Based on this, the ratio of particles having a number average particle size Dn or less of the toner particles in the particle size distribution of the transparent toner particles is calculated. Here, the number of toner particles to be measured (i.e., all toner particles) is 5000. The brightness for selecting colored toner particles and transparent toner particles is based on monochrome 256 gradations (0 to 255) (brightness 0: dark, brightness 255: light). When the toner contains an external additive, 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 additive has been removed.

[0038] (Circularity of toner particles) It is preferred that the transparent toner particles have a greater average circularity than the colored toner particles. Specifically, the difference in average circularity between the colored toner particles and the transparent toner particles is preferably 0.01 or more, more preferably 0.015 or more, and even more preferably 0.02 or more. It is considered that when the second toner particles have a larger average circularity than the first toner particles, the transparent toner particles melt and penetrate easily so as to fill the gaps between the colored toner particles due to the pressure during fixing of the toner image, which further facilitates suppression of fluctuations in image gloss.

[0039] The average circularity of the colored toner particles is preferably 0.930 or more and 0.960 or less, more preferably 0.935 or more and 0.955 or less, and even more preferably 0.94 or more and 0.95 or less. When the average circularity of the colored toner particles is within the above range, the colored toner particles have a moderate irregular shape. Therefore, when the toner image is fixed, gaps between the colored toner particles are likely to be formed. It is considered that the transparent toner particles are likely to melt and penetrate so as to fill the gaps between the colored toner particles due to the pressure during fixing. As a result, the fluctuation of the image glossiness is further easily suppressed.

[0040] The average circularity of colored toner particles and transparent 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, it is a value measured by the following method. The toner particles to be measured are sucked and collected, formed into a flat flow, and a still image of the particles is captured by instantly emitting a strobe light. The particle size and shape are then determined using a wet flow type particle size and shape analyzer (FPIA-3000; manufactured by Malvern Panalytical) which performs image analysis. Specifically, first, a particle image of the toner particles to be measured is obtained. Based on the brightness of the obtained particle images, particle images corresponding to transparent toner particles are selected, the circularity of the transparent toner particles is determined, and the arithmetic average thereof is regarded as the average circularity of the colored toner particles. Particle images corresponding to transparent toner particles are selected based on the brightness of the obtained particle images, and the circularity of the transparent toner particles is determined, and the arithmetic average thereof is regarded as the average circularity of the transparent toner particles. Here, the brightness is based on monochrome 256 gradations (0 to 255) (brightness 0: dark, brightness 255: light) for separating colored toner particles and transparent toner particles. When the toner contains an external additive, 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 additive has been removed.

[0041] (area ratio of crystalline resin domain) When the cross sections of the colored toner particles and the transparent toner particles are observed, it is preferable that the area ratio Ss of the crystalline resin domain to the cross-sectional area of ​​the transparent toner particle is larger than the area ratio Sf of the crystalline resin domain to the cross-sectional area of ​​the colored toner particle. Specifically, the relationship between the area ratio Sf of the crystalline resin domain to the cross-sectional area of ​​the colored toner particle and the area ratio Ss of the crystalline resin domain to the cross-sectional area of ​​the transparent toner particle preferably satisfies Ss / Sf≧1.2, more preferably Ss / Sf≧2.5, and even more preferably Ss / Sf≧3.0. The affinity between the crystalline resin and the colorant is low, and when the area ratio of the crystalline resin in the toner particles is high, the toner particles do not contain the colorant or the amount of the colorant is very small. Therefore, even in the kneading and pulverizing method, it is easy to produce transparent toner particles. In addition, the area ratio of the crystalline resin in the transparent toner is increased, so that the transparent toner particles are more easily melted, which makes it easier to achieve a smooth surface of the image, and as a result, it is easier to suppress fluctuations in the image glossiness.

[0042] The area ratio Ss of the crystalline resin domain to the cross-sectional area of ​​the transparent toner particle is preferably 50% or more and 80% or less, more preferably 55% or more and 75% or less, and even more preferably 60% or more and 70% or less, from the viewpoint of suppressing fluctuations in image glossiness.

[0043] The area ratio of the domain of the crystalline resin is measured as follows. Toner particles (or toner particles with external additives) are mixed and embedded in epoxy resin, and the epoxy resin is solidified. The solidified material obtained is cut using an ultramicrotome device (Ultracut UCT manufactured by Leica) to prepare a thin section sample with a thickness of 80 nm to 130 nm. Next, the obtained thin section sample is stained with ruthenium tetroxide for 3 hours in a desiccator at 30°C. Then, an ultra-high resolution field emission scanning electron microscope (FE-SEM, S-4800 manufactured by Hitachi High-Technologies Corporation) is used to obtain a STEM observation image (accelerating voltage: 30 kV, magnification: 20,000 times) in the transmission image mode of the stained thin section sample. Among the toner particles, the crystalline polyester resin and the release agent are judged from the contrast and shape. In the SEM image, the crystalline resin stained with ruthenium is different from the amorphous resin, the release agent, etc., in that the binder resin other than the release agent has many double bond parts and is stained with ruthenium tetroxide, so the release agent part and the resin part other than the release agent can be distinguished. In other words, the release agent is the domain that is dyed the lightest with ruthenium, followed by the crystalline resin (e.g., crystalline polyester resin). is dyed, with the amorphous resin (for example, amorphous polyester resin) being dyed the darkest. By adjusting the contrast, it is possible to distinguish the domains in which the release agent appears white, the amorphous resin appears black, and the crystalline resin appears light gray.

[0044] The ruthenium-stained crystalline resin area is subjected to image analysis to determine the area ratio of the crystalline resin domain to the cross-sectional area of ​​the toner particle. Then, the above operation is carried out for each of 500 toner particles corresponding to the colored toner particles (i.e., first toner particles having a brightness of less than 90), and the arithmetic average is calculated, which is the area ratio of the crystalline resin domain to the cross-sectional area of ​​the colored toner particles. In addition, the above operation is also carried out on 500 toner particles corresponding to transparent toner (i.e., second toner particles having a brightness of 90 or more), and the arithmetic average is calculated, which is the area ratio of the crystalline resin domain to the cross-sectional area of ​​the transparent toner particle. The brightness for distinguishing between colored toner particles and transparent toner particles is based on 256 monochrome gradations (0 to 255) (brightness 0: dark, brightness 255: light).

[0045] (Composition of toner particles) The colored toner particles are configured to contain, for example, a binder resin, a colorant, and, if necessary, a release agent and other additives. On the other hand, the transparent toner particles are composed of a binder resin and, if necessary, a release agent and other additives, but may contain a small amount of a colorant.

[0046] -Binding resin- Examples of the binder resin include vinyl resins made of 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.), or 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 coexistence of these. These binder resins may be used alone or in combination of two or more kinds.

[0047] In particular, it is preferable to use a combination of an amorphous resin and a crystalline resin as the binder resin. However, the mass ratio of the amorphous resin to the crystalline resin (crystalline resin / amorphous resin) is preferably from 2 / 98 to 50 / 50, and more preferably from 4 / 96 to 30 / 70. However, in the case of colored toner particles, the mass ratio of the amorphous resin to the crystalline resin (crystalline resin / amorphous resin) is particularly preferably 3 / 97 or more and 30 / 70 or less. On the other hand, in the case of transparent toner particles, the mass ratio of the amorphous resin to the crystalline resin (crystalline resin / amorphous resin) is particularly preferably 60 / 40 or more and 95 / 5 or less.

[0048] Here, the term "amorphous resin" refers to a resin that, in a thermal analysis measurement using differential scanning calorimetry (DSC), has only a stepwise endothermic change rather than a clear endothermic peak, is a solid at room temperature, and is thermoplasticized at a temperature equal to or higher than the glass transition temperature. On the other hand, a crystalline resin refers to a resin that has a clear endothermic peak rather than a stepwise change in endothermic amount in differential scanning calorimetry (DSC). Specifically, for example, a crystalline resin means a resin whose half-width of an endothermic peak is within 10°C when measured at a heating rate of 10°C / min, and an amorphous resin means a resin whose half-width exceeds 10°C or a resin in which no clear endothermic peak is observed.

[0049] The amorphous resin will be described. Examples of the amorphous resin include known amorphous resins such as amorphous polyester resin, amorphous vinyl resin (e.g., styrene-acrylic resin, etc.), epoxy resin, polycarbonate resin, polyurethane resin, etc. Among these, amorphous polyester resin and amorphous vinyl resin (particularly styrene-acrylic resin) are preferred, and amorphous polyester resin is more preferred. In addition, it is also a preferred embodiment to use an amorphous polyester resin and a styrene-acrylic resin in combination as the amorphous resin. It is also a preferred embodiment to use an amorphous resin having an amorphous polyester resin segment and a styrene-acrylic resin segment as the amorphous resin.

[0050] Amorphous polyester resin The amorphous polyester resin may be, for example, a condensation polymer of a polyvalent carboxylic acid and a polyhydric alcohol. As the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0051] Examples of polyvalent carboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as the polyvalent carboxylic acid. The polyvalent carboxylic 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 (e.g., carbon number 1 to 5) alkyl esters thereof. The polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

[0052] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyhydric alcohols, and aromatic diols are more preferred. As the polyhydric alcohol, a polyhydric alcohol having a crosslinked or branched structure of three or more may be used in combination with the diol. Examples of the polyhydric alcohol having a trihydric or higher valence include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more kinds.

[0053] The amorphous polyester resin is obtained by a known manufacturing method. Specifically, for example, the polymerization temperature is set to 180°C or more and 230°C or less, the reaction system is depressurized as necessary, and the reaction is carried out while removing water and alcohol generated during condensation. If the raw material monomer is not dissolved or compatible at the reaction temperature, a high-boiling point solvent may be added as a dissolution aid to dissolve it. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. If a monomer with poor compatibility is present in the copolymerization reaction, it is recommended that the monomer with poor compatibility is condensed in advance with the acid or alcohol to be polycondensed with the monomer and then polycondensed with the main component.

[0054] The amorphous polyester resin may be a modified amorphous polyester resin in addition to an unmodified amorphous polyester resin. The modified amorphous polyester resin is an amorphous polyester resin having a bond group other than an ester bond, or an amorphous polyester resin having a resin component different from polyester bonded by a covalent bond or an ionic bond. The modified amorphous polyester resin may be, for example, a resin modified at the end by reacting an amorphous polyester resin having a functional group such as an isocyanate group introduced at the end with an active hydrogen compound.

[0055] The proportion of the amorphous polyester resin in the total binder resin is preferably 60% by mass or more and 98% by mass or less, more preferably 65% ​​by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less.

[0056] Styrene acrylic resin The styrene-acrylic resin is a copolymer obtained by copolymerizing at least a styrene-based monomer (a monomer having a styrene skeleton) and a (meth)acrylic-based monomer (a monomer having a (meth)acrylic group, preferably a monomer having a (meth)acryloxy group). The styrene-acrylic resin includes, for example, a copolymer of a styrene monomer and a (meth)acrylic acid ester monomer. The acrylic resin portion of the styrene-acrylic resin is a partial structure formed by polymerizing either an acrylic monomer or a methacrylic monomer, or both. In addition, the term "(meth)acrylic" includes both "acrylic" and "methacrylic".

[0057] Examples of the styrene monomer include styrene, α-methylstyrene, metachlorostyrene, parachlorostyrene, parafluorostyrene, paramethoxystyrene, meta-tert-butoxystyrene, para-tert-butoxystyrene, paravinylbenzoic acid, paramethyl-α-methylstyrene, etc. The styrene monomer may be used alone or in combination of two or more kinds.

[0058] Examples of the (meth)acrylic monomer include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. The (meth)acrylic monomer may be used alone or in combination of two or more.

[0059] The polymerization ratio of the styrene-based monomer to the (meth)acrylic monomer is preferably styrene-based monomer:(meth)acrylic monomer=70:30 to 95:5 on a mass basis.

[0060] The styrene-acrylic resin may have a crosslinked structure. The styrene-acrylic resin having a crosslinked structure can be produced, for example, by copolymerizing a styrene-based monomer, a (meth)acrylic monomer, and a crosslinkable monomer. The crosslinkable monomer is not particularly limited, but is preferably a bifunctional or higher (meth)acrylate compound.

[0061] The method for producing the styrene-acrylic resin is not particularly limited, and for example, solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc. The polymerization reaction is carried out by a known operation (for example, a batch system, a semi-continuous system, a continuous system, etc.).

[0062] The proportion of the styrene-acrylic resin in the total binder resin is preferably from 0% to 20% by mass, more preferably from 1% to 15% by mass, and even more preferably from 2% to 10% by mass.

[0063] Amorphous resin having an amorphous polyester resin segment and a styrene-acrylic resin segment (hereinafter also referred to as "hybrid amorphous resin") The hybrid amorphous resin is an amorphous resin in which an amorphous polyester resin segment and a styrene-acrylic resin segment are chemically bonded to each other. Examples of the hybrid amorphous resin include a resin having a main chain made of a polyester resin and a side chain made of a styrene-acrylic resin chemically bonded to the main chain; a resin having a main chain made of a styrene-acrylic resin and a side chain made of a polyester resin chemically bonded to the main chain; a resin having a main chain formed by chemically bonding a polyester resin and a styrene-acrylic resin; a resin having a main chain formed by chemically bonding a polyester resin and a styrene-acrylic resin, and at least one of a side chain made of a polyester resin chemically bonded to the main chain and a side chain made of a styrene-acrylic resin chemically bonded to the main chain; and the like.

[0064] The amorphous polyester resin and the styrene-acrylic resin in each segment are as described above, and therefore the description thereof will be omitted.

[0065] The total amount of the polyester resin segment and the styrene-acrylic resin segment in the entire hybrid amorphous resin is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and even more preferably 100 mass%.

[0066] In the hybrid amorphous resin, the proportion of the styrene-acrylic resin segment in the total amount of the polyester resin segment and the styrene-acrylic resin segment is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 55% by mass or less, and even more preferably 30% by mass or more and 50% by mass or less.

[0067] The hybrid amorphous resin is preferably produced by any one of the following methods (i) to (iii). (i) After preparing a polyester resin segment by condensation polymerization of a polyhydric alcohol and a polycarboxylic acid, a monomer constituting a styrene-acrylic resin segment is addition-polymerized. (ii) A styrene-acrylic resin segment is prepared by addition polymerization of an addition-polymerizable monomer, and then a polyhydric alcohol and a polycarboxylic acid are condensation-polymerized. (iii) Polycondensation of a polyhydric alcohol and a polycarboxylic acid and addition polymerization of an addition-polymerizable monomer are carried out in parallel.

[0068] The proportion of the hybrid amorphous resin in the total binder resin is preferably 60% by mass or more and 98% by mass or less, more preferably 65% ​​by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less.

[0069] The characteristics of the amorphous resin will be described. The characteristics of the amorphous resin will be described. The glass transition temperature (Tg) of the amorphous resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 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 the method for determining glass transition temperature in JIS K 7121-1987 "Method for measuring transition temperature of plastics."

[0070] The weight average molecular weight (Mw) of the amorphous 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 resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the amorphous 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). The molecular weight measurement by GPC is performed using a Tosoh GPC HLC-8120GPC as the measuring device, a Tosoh TSKgel SuperHM-M (15 cm) column, and THF solvent. The weight average molecular weight and number average molecular weight are calculated from the measurement results using a molecular weight calibration curve created with a monodisperse polystyrene standard sample.

[0071] 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 from the viewpoints of the mechanical strength and low-temperature fixability of the toner.

[0072] Crystalline polyester resin The crystalline polyester resin may be, for example, a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the crystalline polyester resin, a commercially available product or a synthesized product may be used. Since the crystalline polyester resin easily forms a crystalline structure, a polycondensation product using a straight-chain aliphatic polymerizable monomer is preferable to a polymerizable monomer having an aromatic ring.

[0073] Examples of polyvalent carboxylic 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, naphthalene-2,6-dicarboxylic acid, etc.), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polyvalent carboxylic 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 carboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, and their lower (e.g., carbon number 1 to 5) alkyl esters. As the polyvalent carboxylic 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 polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

[0074] 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 in combination with the diol. Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more kinds.

[0075] The polyhydric alcohol may have an aliphatic diol content of 80 mol % or more, and preferably 90 mol % or more.

[0076] The crystalline polyester resin can be obtained, for example, by a known production method, like the amorphous polyester resin.

[0077] As the crystalline polyester resin, a polymer of an α,ω-straight-chain aliphatic dicarboxylic acid and an α,ω-straight-chain aliphatic diol is preferable.

[0078] The α,ω-linear aliphatic dicarboxylic acid is preferably an α,ω-linear aliphatic dicarboxylic acid in which the alkylene group connecting the two carboxy groups has 3 or more and 14 or less carbon atoms, more preferably the alkylene group has 4 or more and 12 or less carbon atoms, and even more preferably the alkylene group has 6 or more and 10 or less carbon atoms. Examples of α,ω-linear aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, 1,6-hexanedicarboxylic acid (commonly known as suberic acid), 1,7-heptanedicarboxylic acid (commonly known as azelaic acid), 1,8-octanedicarboxylic acid (commonly known as sebacic acid), 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid. Of these, 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, and 1,10-decanedicarboxylic acid are preferred. The α,ω-linear aliphatic dicarboxylic acids may be used alone or in combination of two or more kinds.

[0079] The α,ω-linear aliphatic diol is preferably an α,ω-linear aliphatic diol in which the alkylene group connecting the two hydroxy groups has 3 to 14 carbon atoms, more preferably the alkylene group has 4 to 12 carbon atoms, and further preferably the alkylene group has 6 to 10 carbon atoms. Examples of the α,ω-linear aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, and 1,18-octadecanediol. Of these, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred. The α,ω-linear aliphatic diols may be used alone or in combination of two or more kinds.

[0080] As the polymer of an α,ω-linear aliphatic dicarboxylic acid and an α,ω-linear aliphatic diol, a polymer of at least one selected from the group consisting of 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid and at least one selected from the group consisting of 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol is preferred, and among these, a polymer of 1,10-decanedicarboxylic acid and 1,6-hexanediol is more preferred.

[0081] The proportion of the crystalline polyester resin in the total binder resin is preferably from 1% by mass to 20% by mass, more preferably from 2% by mass to 15% by mass, and even more preferably from 3% by mass to 10% by mass. The characteristics of the crystalline resin will be described. The melting temperature of the crystalline 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) based on the "melting peak temperature" described in the method for determining melting temperature in JIS K7121-1987 "Method for measuring transition temperature of plastics."

[0082] The weight average molecular weight (Mw) of the crystalline resin is preferably 6,000 or more and 35,000 or less.

[0083] The content of the binder resin is preferably from 40% by mass to 95% by mass, more preferably from 50% by mass to 90% by mass, and even more preferably from 60% by mass to 85% by mass, based on the total mass of the toner particles.

[0084] -Coloring agent- Examples of colorants include carbon black, chrome yellow, Hansa Yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, Examples of the dyes include pigments such as ultramarine blue, chalcoil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; and dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes. The colorant may be used alone or in combination of two or more kinds.

[0085] The colorant may be surface-treated as necessary, or may be used in combination with a dispersant. In addition, a plurality of types of colorants may be used in combination.

[0086] The content of the colorant is preferably from 1% by mass to 30% by mass, and more preferably from 3% by mass to 15% by mass, based on the total mass of the toner particles. However, in the case of colored toner particles, the content of the colorant is particularly preferably from 1% by mass to 30% by mass. On the other hand, in the case of transparent toner particles, the content of the colorant is particularly preferably from 0% by mass to 1% by mass.

[0087] -Release agent- Examples of the release agent 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 montan acid esters. The release agent is not limited to these.

[0088] 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 of the release agent is determined from a DSC curve obtained by differential scanning calorimetry (DSC) based on the "melting peak temperature" described in the method for determining melting temperature in JIS K7121:1987 "Method for measuring transition temperature of plastics."

[0089] The content of the release agent is preferably from 1% by mass to 20% by mass, and more preferably from 5% by mass to 15% by mass, based on the total mass of the toner particles.

[0090] -Other additives- Examples of other additives include known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the toner particles as internal additives.

[0091] -Characteristics of toner particles- The toner particles may be toner particles having a single layer structure, or may be toner particles having a so-called core-shell structure composed of a core portion (core particle) and a coating layer (shell layer) that coats the core portion. The toner particles having a core-shell structure may be composed of, for example, a core containing a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer containing the binder resin.

[0092] [External additives] The external additive may be, for example, inorganic particles. Examples of inorganic particles include SiO 2 , TiO 2 , Al 2 O 3 , CuO, ZnO, SnO 2 , CEO2 , Fe 2 O 3 , MgO, BaO, CaO, K 2 O, Na 2 O, ZrO 2 , CaO SiO 2 , K 2 O (TiO 2 ) n , Al 2 O 3 2SiO 2 , CaCO 3 , MgCO 3 , BaSO 4 , MgSO 4 etc.

[0093] The surface of the inorganic particles as an external additive may be hydrophobized. The hydrophobization may be performed, for example, by immersing the inorganic particles in a hydrophobizing agent. The hydrophobizing 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 hydrophobizing agent is usually, for example, 1 to 10 parts by mass relative to 100 parts by mass of the inorganic particles.

[0094] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate, and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and fluorine-based polymer particles), and the like.

[0095] The amount of the external additive is preferably from 0.01% by mass to 5% by mass, and more preferably from 0.01% by mass to 2.0% by mass, based on the toner particles.

[0096] [Toner manufacturing method] The toner according to the exemplary embodiment is obtained by producing toner particles and then externally adding an external additive to the toner particles.

[0097] The toner particles may be produced by any of a dry production method (e.g., a kneading and grinding method, etc.) and a wet production method (e.g., an aggregation and coalescence method, a suspension polymerization method, a dissolution suspension method, etc.). There are no particular limitations on these production methods, and any known production method may be used.

[0098] For example, an example of a method for producing toner particles by a kneading and pulverizing method will be described. The kneading and pulverizing method is a method for producing toner particles by melting and kneading a binder resin containing an amorphous resin and a crystalline resin with a colorant, followed by pulverizing and classifying the mixture. In the kneading and pulverizing method, toner particles are produced through, for example, a kneading step for melting and kneading components containing the binder resin and the colorant, a cooling step for cooling the molten and kneaded mixture, a pulverizing step for pulverizing the kneaded mixture after cooling, and a classification step for classifying the pulverized mixture.

[0099] In the kneading and pulverizing method, when the domain size of the crystalline resin in the kneaded product is increased and then pulverized, toner particles including colored toner particles and transparent toner particles are obtained. When a kneaded product with a large domain size of the crystalline resin is pulverized, it is likely to be pulverized at the boundary of the domain of the crystalline resin. Therefore, it is easy to obtain a pulverized product containing a large amount of the domain of the crystalline resin. Since the affinity between the crystalline resin and the colorant is low, the colorant is likely to exist in the amorphous resin, and the pulverized product containing a large amount of the domain of the crystalline resin is unlikely to contain the colorant. In other words, it becomes easier to obtain a pulverized product that contains a large amount of coloring agent and a pulverized product that does not contain any coloring agent or contains only a small amount of coloring agent. Therefore, toner particles including colored toner particles and transparent toner particles are obtained.

[0100] Each step of the kneading and pulverizing method will be described in detail below.

[0101] -Kneading process- The kneading step is a step in which a binder resin including an amorphous resin and a crystalline resin, and a component including a colorant are melt-kneaded to obtain a kneaded product. Examples of kneading machines used in the kneading step include three-roll type, single-screw type, twin-screw type, and Banbury mixer type. The melting temperature may be determined depending on the types and compounding ratios of the binder resin and colorant to be kneaded.

[0102] -Cooling process- The cooling step is a step of cooling the kneaded material formed in the kneading step. In the cooling step, for example, the kneaded mixture is cooled from the temperature at the end of the kneading step to 40° C. or less at an average temperature decreasing rate of 10° C. / sec or less, which facilitates the growth of domains of the crystalline resin in the kneaded mixture. The average temperature decreasing rate refers to the average rate at which the temperature of the kneaded material is decreased from the temperature at the end of the kneading step to 40°C.

[0103] The cooling method in the cooling step may be, for example, a method using a rolling roll in which cold water or brine is circulated and a pinching cooling belt, etc. When cooling is performed by the above method, the cooling rate is determined by the speed of the rolling roll, the flow rate of the brine, the supply amount of the kneaded material, the slab thickness of the kneaded material when it is rolled, etc.

[0104] -Crushing process- The kneaded product cooled in the cooling step is pulverized in the pulverizing step to form particles. In the pulverizing step, for example, a mechanical pulverizer, a jet pulverizer, or the like is used. Here, before pulverization, the kneaded material may be heated to a temperature not exceeding the melting point of the crystalline resin (for example, below the melting temperature of the crystalline resin (melting temperature -10°C). This makes it easier for the domains of the crystalline resin in the kneaded material to grow.

[0105] -Classification process- The pulverized product (particles) obtained in the pulverization step may be classified in a classification step, if necessary, in order to obtain toner particles having a desired average particle size. In the classification process, a conventional centrifugal classifier, inertial classifier, or the like is used to remove fine powder (particles smaller than the desired particle size range) and coarse powder (particles larger than the desired particle size range).

[0106] -Hot air treatment process- After the classification step, if necessary, a hot air treatment may be performed in a hot air treatment step in order to obtain toner particles having a desired circularity.

[0107] Through the above steps, toner particles containing colored toner particles and transparent toner particles are obtained. The method for producing the toner particles is not limited to the above-described method. Colored toner particles and transparent toner particles may be separately produced by a normal method, and the resulting colored toner particles and transparent toner particles may be mixed to produce the toner particles.

[0108] The toner according to the present embodiment is produced, for example, by adding an external additive to the obtained toner particles in a dry state and mixing them. The mixing may be performed, for example, by using a V blender, a Henschel mixer, a Loedige mixer, etc. Furthermore, if necessary, coarse particles of the toner may be removed using a vibration sieve, an air sieve, etc.

[0109] <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 the present embodiment may be a one-component developer containing only the toner according to the present embodiment, or may be a two-component developer in which the toner is mixed with a carrier.

[0110] The carrier is not particularly limited, and may be any known carrier, such as a coated carrier in which the surface of a core material made of magnetic powder is coated with a coating resin, a magnetic powder dispersion type carrier in which magnetic powder is dispersed and mixed in a matrix resin, or a resin impregnated type carrier 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.

[0111] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0112] Examples of the coating resin and matrix resin 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 resin containing an organosiloxane bond or a modified product thereof, fluororesin, polyester, polycarbonate, phenolic resin, and epoxy resin. The coating resin and the matrix resin may contain other additives such as conductive particles. Examples of the 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.

[0113] Here, the method of coating the surface of the core material with the 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, etc. The solvent is not particularly limited and may be selected taking into consideration the coating resin to be used, the suitability for application, 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 a carrier and the solution for forming a coating layer are mixed in a kneader coater and the solvent is removed.

[0114] In the two-component developer, the mixture ratio (mass ratio) of the toner and the carrier is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0115] <Image forming device / image forming method> An image forming apparatus / 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 means for charging the surface of the image carrier, an electrostatic image forming means for forming an electrostatic image on the surface of the charged image carrier, a developing means for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image carrier as a toner image with 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, and a fixing means for fixing 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.

[0116] In the image forming apparatus according to this embodiment, an image forming method (the image forming method according to this embodiment) is carried out, which 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.

[0117] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as a direct transfer type apparatus in which a toner image formed on the surface of an image holder is directly transferred to a recording medium; an intermediate transfer type apparatus in which a toner image formed on the surface of an image holder is primarily transferred to the surface of an intermediate transfer body, and the toner image transferred to the surface of the intermediate transfer body is then secondarily transferred to the surface of a recording medium; an apparatus equipped with a cleaning means for cleaning the surface of the image holder before charging after the transfer of the toner image; and an apparatus equipped with a discharging means for irradiating the surface of the image holder with discharging light to discharge it before charging after the transfer of the toner image. In the case of an intermediate transfer type device, the transfer means has, 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 a recording medium.

[0118] 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 including a developing means that contains the electrostatic image developer according to the present embodiment is preferably used.

[0119] 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 the rest will be omitted.

[0120] FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to the present embodiment. The image forming apparatus shown in Fig. 1 includes first to fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming means) that output images of each color of 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 in parallel at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

[0121] Above each of the units 10Y, 10M, 10C, and 10K in the drawing, an intermediate transfer belt 20 is provided as an intermediate transfer body extending through each unit. The intermediate transfer belt 20 is provided wound around a drive roll 22 and a support roll 24 that are arranged from left to right in the drawing at a distance from each other and contact the inner surface of the intermediate transfer belt 20, and is adapted to run in a direction from the first unit 10Y to the fourth unit 10K. Note that 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), and tension is applied 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. Further, 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.

[0122] Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, the first unit 10Y that forms a yellow image and is disposed upstream in the direction in which the intermediate transfer belt travels will be described here as a representative example. Note that by assigning reference numerals of magenta (M), cyan (C), and black (K) instead of yellow (Y) to parts equivalent to those of the first unit 10Y, descriptions of the second to fourth units 10M, 10C, and 10K will be omitted.

[0123] The first unit 10Y has a photoconductor 1Y that acts as an image carrier. Around the photoconductor 1Y, a charging roll (an example of a charging means) 2Y that charges the surface of the photoconductor 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 photoconductor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer are arranged in this order. The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20 and is provided at a position facing the photoconductor 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).

[0124] Hereinafter, an operation of forming a yellow image in first unit 10Y will be described. First, prior to operation, the surface of the photoconductor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y. The photoconductor 1Y has a conductivity (for example, a volume resistivity at 20° C. of 1×10 -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate having a resistivity of Ωcm or less. This photosensitive layer is usually highly resistive (the resistance of ordinary resins), but when irradiated with a laser beam 3Y, the resistivity of the portion irradiated with the laser beam changes. A laser beam 3Y is output to the charged surface of the photoreceptor 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 photoreceptor 1Y, and an electrostatic charge image of a yellow image pattern is formed on the surface of the photoreceptor 1Y.

[0125] An electrostatic image is an image formed on the surface of the photoconductor 1Y by electrostatic charging. The laser beam 3Y reduces the resistivity of the irradiated parts of the photosensitive layer, causing the charged charges on the surface of the photoconductor 1Y to flow, while the charges remain in the parts not irradiated by the laser beam 3Y. This is a so-called negative latent image. The electrostatic image formed on the photoconductor 1Y is rotated to a predetermined developing position as the photoconductor 1Y travels. Then, at this developing position, the electrostatic image on the photoconductor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0126] The developing device 4Y contains an electrostatic image developer including at least yellow toner and a carrier, for example. The yellow toner is triboelectrically charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoconductor 1Y. As the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoconductor 1Y, and the latent image is developed with the yellow toner. The photoconductor 1Y on which the yellow toner image has been formed continues to travel at a predetermined speed, and the toner image developed on the photoconductor 1Y is transported to a predetermined primary transfer position.

[0127] 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 toward the primary transfer roll 5Y acts on the toner image, and the toner image on the photoreceptor 1Y is 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 photoconductor 1Y is removed and collected by the photoconductor cleaning device 6Y.

[0128] Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K subsequent to the second unit 10M is also controlled in accordance with the first unit. In this manner, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is conveyed successively through the second to fourth units 10M, 10C, and 10K, where the toner images of the respective colors are transferred in a superimposed manner.

[0129] The intermediate transfer belt 20 onto which the four color toner images have been transferred in multiple layers through the first to fourth units reaches a secondary transfer section that is composed of the intermediate transfer belt 20, a support roll 24 that contacts 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, a recording paper (an example of a recording medium) P is fed at a predetermined timing into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 via a supply mechanism, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a (-) polarity that is the same as the (-) polarity of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, so that the toner image on the intermediate transfer belt 20 is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0130] Thereafter, the recording paper P is sent to a pressure contact portion (nip portion) of a pair of fixing rolls in a fixing device (one example of a fixing means) 28, where the toner image is fixed onto the recording paper P, forming a fixed image.

[0131] The recording paper P onto which the toner image is transferred can be, for example, plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, other examples of the recording medium include overhead projector sheets, etc. 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 ordinary paper is coated with resin or the like, art paper for printing, or the like is preferably used.

[0132] After the color image has been fixed, the recording paper P is conveyed toward the discharge section, and the series of color image forming operations is completed.

[0133] <Process cartridge / toner cartridge> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment is a process cartridge that contains the electrostatic image developer according to this embodiment, 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, and is detachably attached to an image forming apparatus.

[0134] In addition, the process cartridge according to this embodiment is not limited to the above configuration, and may be configured to include a developing device and, as necessary, at least one other means selected from an image carrier, a charging means, an electrostatic image forming means, and a transfer means.

[0135] An example of a process cartridge according to the present embodiment will be described below, but the present invention is not limited to this example. Note that only the main parts shown in the drawings will be described, and descriptions of the rest will be omitted.

[0136] FIG. 2 is a schematic diagram showing the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured by, for example, a housing 117 having a mounting rail 116 and an opening 118 for exposure, and integrally combining and holding a photoconductor 107 (an example of an image carrier), a charging roll 108 (an example of a charging means) provided around the photoconductor 107, a developing device 111 (an example of a developing means), and a photoconductor cleaning device 113 (an example of a cleaning means), which are assembled 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).

[0137] 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.

[0138] 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to the respective developing devices (colors) through toner supply pipes (not shown). When the toner contained in the toner cartridge becomes low, the toner cartridge is replaced. EXAMPLES

[0139] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are based on mass.

[0140] <Synthesis of amorphous polyester resin (A1)> Terephthalic acid: 68 parts Fumaric acid: 32 parts Ethylene glycol: 42 parts 1,5-Pentanediol: 47 parts The above materials were placed in a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and the temperature was raised to 220°C over 1 hour under a nitrogen gas flow, and 1 part of titanium tetraethoxide was added for a total of 100 parts of the above materials. The temperature was raised to 240°C over 0.5 hours while distilling off the generated water, and the dehydration condensation reaction was continued at 240°C for 1 hour, after which the reaction product was cooled. In this way, an amorphous polyester resin (A1) with a weight average molecular weight of 97,000 and a glass transition temperature of 60°C was obtained.

[0141] <Preparation of crystalline polyester resin (B1)> 1,10-Decanedicarboxylic acid: 260 parts 1,6-Hexanediol: 167 parts Dibutyltin oxide (catalyst): 0.3 parts The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed at 180°C for 5 hours using mechanical stirring. The temperature was then gradually increased to 230°C under reduced pressure and stirred for 2 hours, and when the mixture became viscous, it was air-cooled to stop the reaction. Thus, a crystalline polyester resin with a weight average molecular weight of 12,500 and a melting temperature of 73°C was obtained.

[0142] <Preparation of crystalline polyester resin (B2)> 1,16-Hexadecanedicarboxylic acid: 260 parts 1,14-Tetradecanediol: 190 parts Dibutyltin oxide (catalyst): 0.3 parts The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed at 180°C for 6 hours using mechanical stirring. The temperature was then gradually increased to 230°C under reduced pressure and stirred for 3 hours, and when the mixture became viscous, it was air-cooled to stop the reaction. Thus, a crystalline polyester resin with a weight average molecular weight of 25,000 and a melting temperature of 112°C was obtained.

[0143] <Preparation of crystalline polyester resin (B3)> 1,12-dodecanedicarboxylic acid: 252 parts 1,12-dodecanediol: 198 parts Dibutyltin oxide (catalyst): 0.3 parts The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed at 180°C for 6 hours using mechanical stirring. The temperature was then gradually increased to 230°C under reduced pressure and stirred for 3.25 hours, and when the mixture became viscous, it was air-cooled to stop the reaction. Thus, a crystalline polyester resin with a weight average molecular weight of 18,000 and a melting temperature of 105°C was obtained.

[0144] <Preparation of crystalline polyester resin (B4)> Sebacic acid: 284 parts 1,6-Hexanediol: 166 parts Dibutyltin oxide (catalyst): 0.3 parts The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed at 180°C for 6 hours using mechanical stirring. The temperature was then gradually increased to 230°C under reduced pressure and stirred for 3.25 hours, and when the mixture became viscous, it was air-cooled to stop the reaction. Thus, a crystalline polyester resin with a weight average molecular weight of 10,000 and a melting temperature of 63°C was obtained.

[0145] <Preparation of crystalline polyester resin (B5)> Adipic acid: 249 parts 1,6-Hexanediol: 201 parts Dibutyltin oxide (catalyst): 0.3 parts The above materials were placed in a heated and dried three-necked flask, the air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed at 180°C for 6 hours using mechanical stirring. The temperature was then gradually increased to 230°C under reduced pressure and stirred for 3.25 hours, and when the mixture became viscous, it was air-cooled to stop the reaction. Thus, a crystalline polyester resin with a weight average molecular weight of 8000 and a melting temperature of 54°C was obtained.

[0146] <Example 1> Amorphous polyester resin (A1): 65 parts Crystalline polyester resin (B1): 23 parts Colorant (carbon black, Mitsubishi Chemical #25): 7 parts Release agent (paraffin wax, Nippon Seiro HNP9): 5 parts The above materials were mixed in a Henschel mixer (FM75L; manufactured by Nippon Coke & Co., Ltd.), then mixed in a twin-screw extruder (TEM-48SS; manufactured by Shibaura Machine Co., Ltd.), and the mixture was rolled and cooled. In this case, the amount of the mixture fed and the water flow of the cooler were adjusted so that the time it took for the surface temperature of the mixture to reach 40°C was 30 seconds or more, and the mixture was cooled at an average temperature drop rate of 5°C / s. The resulting mixture was coarsely pulverized in a hammer mill, stored in a thermostatic chamber at 50°C for 24 hours, pulverized in a jet mill (AFG; manufactured by Hosokawa Micron Corporation), and classified with an elbow jet classifier (EJ-LABO; manufactured by Nittetsu Mining Co., Ltd.) under conditions adjusted to Dn of 5.0 μm, and then subjected to hot air treatment in a 150°C atmosphere to obtain toner particles 1.

[0147] Toner particles 1: 100 parts Sol-gel silica particles (number average particle size = 120 nm): 2.0 parts Strontium titanate particles (number average particle size = 50 nm): 0.2 parts The above materials were mixed in a Henschel mixer to obtain Toner 1.

[0148] <Example 2> -Preparation of toner particles 2-1- Amorphous polyester resin (A1): 68 parts Crystalline polyester resin (B1): 20 parts Colorant (carbon black, Mitsubishi Chemical #25): 7 parts Release agent (paraffin wax, Nippon Seiro HNP9): 5 parts The above materials were mixed in a Henschel mixer (FM75L; manufactured by Nippon Coke & Co., Ltd.), then mixed in a twin-screw extruder (TEM-48SS; manufactured by Shibaura Machine Co., Ltd.), and the mixture was rolled and cooled. In this case, the amount of the mixture fed and the water flow of the cooler were adjusted so that the time required for the surface temperature of the mixture to reach 40°C was 10 seconds or less, and the mixture was cooled at an average temperature drop rate of 10°C / s. The resulting mixture was coarsely pulverized in a hammer mill, stored in a thermostatic chamber at 20°C for 12 hours, pulverized in a jet mill (AFG; manufactured by Hosokawa Micron Corporation), and classified with an elbow jet classifier (EJ-LABO; manufactured by Nittetsu Mining Co., Ltd.) under conditions adjusted to Dn of 5.0 μm, and then subjected to hot air treatment in a 150°C atmosphere to obtain toner particles 2-1.

[0149] -Preparation of toner particles 2-2- Amorphous polyester resin (A1): 30 parts Crystalline polyester resin (B1): 65 parts Release agent (paraffin wax, Nippon Seiro HNP9): 5 parts The above materials were mixed in a Henschel mixer (FM75L; manufactured by Nippon Coke & Co., Ltd.), then mixed in a twin-screw extruder (TEM-48SS; manufactured by Shibaura Machine Co., Ltd.), and the mixture was rolled and cooled. In this case, the flow rate of the mixture and the water flow of the cooler were adjusted so that the time for the surface temperature of the mixture to reach 40°C was 10 seconds or less, and the mixture was cooled at an average temperature drop rate of 10°C / s. The obtained mixture was coarsely crushed in a hammer mill, stored in a thermostatic chamber at 20°C for 12 hours, crushed in a jet mill (AFG; manufactured by Hosokawa Micron Corporation), and classified with an elbow jet classifier (EJ-LABO; manufactured by Nittetsu Mining Co., Ltd.) under conditions adjusted to Dn of 4.0 μm, and then subjected to hot air treatment in a 150°C atmosphere to obtain toner particles 2-2.

[0150] - Preparation of Toner 2 - Toner particles 2-1: 94 parts Toner particles 2-2: 6 parts Sol-gel silica particles (number average particle size = 120 nm): 2.0 parts Strontium titanate particles (number average particle size = 50 nm): 0.2 parts The above materials were mixed in a Henschel mixer to obtain Toner 2.

[0151] <Example 3> Toner 3 was obtained in the same manner as in Example 1, except that the average temperature lowering rate of the kneaded material was changed to 6° C. / s.

[0152] <Example 4> Toner 4 was obtained in the same manner as in Example 1, except that the average temperature lowering rate of the kneaded material was changed to 4° C. / s.

[0153] <Example 5> Toner 5 was obtained in the same manner as in Example 1, except that the amount of amorphous polyester (A1) was changed to 80 parts and the amount of crystalline polyester (B1) was changed to 8 parts.

[0154] <Example 6> Toner 6 was obtained in the same manner as in Example 2, except that in the preparation of toner 2, the amount of toner particles 2-1 was 90.2 parts and the amount of toner particles 2-2 was 9.8 parts.

[0155] <Example 7> Toner 7 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-2, classification was carried out under conditions adjusted so that Dn was 3.5 μm.

[0156] <Example 8> Toner 8 was obtained in the same manner as in Example 2, except that the hot air treatment temperature in the preparation of toner particles 2-2 was set to 100°C.

[0157] <Example 9> Toner 9 was obtained in the same manner as in Example 2, except that the hot air treatment temperature in the preparation of toner particles 2-2 was set to 130°C.

[0158] <Example 10> Toner 10 was obtained in the same manner as in Example 2, except that the hot air treatment temperature in the preparation of toner particles 2-2 was set to 140°C.

[0159] <Example 11> Toner 11 was obtained in the same manner as in Example 1, except that the hot air treatment temperature was 130°C.

[0160] <Example 12> Toner 12 was obtained in the same manner as in Example 1, except that the hot air treatment temperature was 135°C.

[0161] <Example 13> Toner 13 was obtained in the same manner as in Example 1, except that the hot air treatment temperature was 160°C.

[0162] <Example 14> Toner 14 was obtained in the same manner as in Example 1, except that the hot air treatment temperature was 165°C.

[0163] <Example 15> Toner 15 was obtained in the same manner as in Example 1, except that the crystalline polyester resin (B5) was used instead of the crystalline polyester resin (B1).

[0164] <Example 16> Toner 16 was obtained in the same manner as in Example 1, except that the crystalline polyester resin (B4) was used instead of the crystalline polyester resin (B1).

[0165] <Example 17> Toner 17 was obtained in the same manner as in Example 1, except that the crystalline polyester resin (B3) was used instead of the crystalline polyester resin (B1).

[0166] <Example 18> Toner 18 was obtained in the same manner as in Example 1, except that the crystalline polyester resin (B2) was used instead of the crystalline polyester resin (B1).

[0167] <Example 19> Toner 19 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-1, the amount of amorphous polyester resin (A1) was changed to 43 parts, the amount of crystalline polyester resin (B1) to 45 parts, and the hot air treatment temperature was changed to 140°C, and in the preparation of toner particles 2-2, the amount of amorphous polyester resin (A1) was changed to 44 parts, and the amount of crystalline polyester resin (B1) to 51 parts.

[0168] <Example 20> Toner 20 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-1, the amount of amorphous polyester resin (A1) was changed to 48 parts, the amount of crystalline polyester resin (B1) to 40 parts, and the hot air treatment temperature was changed to 140°C, and in the preparation of toner particles 2-2, the amount of amorphous polyester resin (A1) was changed to 44 parts, and the amount of crystalline polyester resin (B1) to 51 parts.

[0169] <Example 21> Toner 21 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-1, the amount of amorphous polyester resin (A1) was changed to 73.1 parts and the amount of crystalline polyester resin (B1) was changed to 14.9 parts, and in the preparation of toner particles 2-2, the amount of amorphous polyester resin (A1) was changed to 50 parts and the amount of crystalline polyester resin (B1) was changed to 45 parts.

[0170] <Example 22> Toner 22 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-1, the amount of amorphous polyester resin (A1) was changed to 71 parts, and the amount of crystalline polyester resin (B1) was changed to 17 parts, and in the preparation of toner particles 2-2, the amount of amorphous polyester resin (A1) was changed to 43 parts, and the amount of crystalline polyester resin (B1) was changed to 52 parts.

[0171] <Example 23> Toner 23 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-1, the amount of amorphous polyester resin (A1) was changed to 62.5 parts and the amount of crystalline polyester resin (B1) was changed to 25.5 parts, and in the preparation of toner particles 2-2, the amount of amorphous polyester resin (A1) was changed to 17 parts and the amount of crystalline polyester resin (B1) was changed to 78 parts.

[0172] <Example 24> Toner 24 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-1, the amount of amorphous polyester resin (A1) was changed to 61 parts and the amount of crystalline polyester resin (B1) was changed to 27 parts, and in the preparation of toner particles 2-2, the amount of amorphous polyester resin (A1) was changed to 13 parts and the amount of crystalline polyester resin (B1) was changed to 82 parts.

[0173] <Comparative Example 1> Toner C1 was obtained in the same manner as in Example 1, except that the amount of amorphous polyester resin (A1) was changed to 67 parts, the amount of crystalline polyester resin (B1) was changed to 21 parts, and the average temperature decreasing rate of the kneaded material was changed to 15° C. / s.

[0174] <Comparative Example 2> Toner C2 was obtained in the same manner as in Example 2, except that in the preparation of toner 2, the amount of toner particles 2-1 was 88 parts and the amount of toner particles 2-2 was 12 parts.

[0175] <Comparative Example 3> Toner C3 was obtained in the same manner as in Example 2, except that in the preparation of toner particles 2-2, classification was carried out under conditions adjusted so that Dn was 3.3 μm.

[0176] <Evaluation> (Various measurements) The toner of each example thus obtained was measured for the following properties according to the methods described above. Number average particle diameter Dn of toner particles (referred to as "Particle diameter Dn" in the table) - Proportion of transparent toner particles to toner particles (in the table, simply indicated as "proportion") The percentage of particles with a number average particle size Dn or less in the particle size distribution of transparent toner particles (in the table, this is indicated as "Particle percentage below Dn") Average circularity Cf of colored toner particles (referred to as "circularity Cf" in the table) Average circularity Cs of transparent toner particles (referred to as "circularity Cs" in the table) The area ratio Sf of the crystalline resin domain to the cross-sectional area of ​​the colored toner particle (referred to as "crystalline resin area ratio Sf" in the table) The area ratio Ss of the domain of the crystalline resin relative to the cross-sectional area of ​​the transparent toner particle (referred to as "crystalline resin area ratio Ss" in the table)

[0177] (Image gloss fluctuation evaluation) Using the toner of each example, a developer for the following image forming apparatus was prepared. The prepared developer was filled in the developing device of an image forming apparatus "DocuPrint 4400d manufactured by Fuji Xerox Co., Ltd.". This image forming device can print a 4cm x 4cm sheet with a toner load of 5g / m2 in an environment of 8°C. 2 The solid image was printed on 50 postcards in a row. The 60 degree gloss value of the 50th printed image was measured using a portable gloss meter (BYK Gardner Micro Trigloss, manufactured by Toyo Seiki Seisakusho). The gloss value was measured 10 times at random in five locations, namely the leading left end, leading right end, trailing left end, trailing right end, and center of the solid image, with the leading edge being the side in the paper transport direction.The difference between the maximum and minimum gloss values ​​obtained was then calculated and evaluated according to the following criteria. A: The difference between the maximum and minimum gloss values ​​is less than 1.0 B: The difference between the maximum and minimum gloss values ​​is 1.0 or more and less than 2.0 C: The difference between the maximum and minimum gloss values ​​is 2.0 or more and less than 3.0 D: The difference between the maximum and minimum gloss values ​​is 3.0 or more and less than 4.0 E: The difference between the maximum and minimum gloss values ​​is 4.0 or more.

[0178] The results are shown in Table 1. The abbreviations in Table 1 are as follows. ·Amo: Crystalline resin species ·Cry: Crystalline resin species ·Cry-MT: Melting temperature of crystalline polyester resin

[0179] [Table 1]

[0180] From the above results, it can be seen that in this embodiment, compared to the comparative example, the fluctuation in image glossiness that occurs when a solid image is repeatedly formed on a small and thick recording medium in a low humidity environment is suppressed. [Explanation of symbols]

[0181] 1Y, 1M, 1C, 1K Photoconductor (an example of an image carrier) 2Y, 2M, 2C, 2K Charging roll (an example of a 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 Driving Roll 24 Support roll 26 Secondary transfer roll (an example of a secondary transfer means) 28 Fixing device (an example of fixing means) 30 Intermediate transfer body cleaning device P Recording paper (an example of a recording medium) 107 Photoconductor (an example of an image carrier) 108 Charging roll (an example of charging means) 109 Exposure device (an example of electrostatic image forming means) 111 Developing device (an example of developing means) 112 Transfer device (an example of a transfer means) 113 Photoconductor cleaning device (an example of a cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting Rail 117 Cabinet 118 Exposure Aperture 200 Process Cartridge 300 Recording paper (an example of a recording medium)

Claims

1. having toner particles including first toner particles having a brightness of less than 90 and second toner particles having a brightness of 90 or more; a ratio of the second toner particles to the toner particles is 0.1% by number or more and 10% by number or less; a ratio of particles having a number average particle diameter Dn or less of the toner particles in a particle size distribution of the second toner particles is 70% by number or more; the first toner particles and the second toner particles contain, as binder resins, an amorphous resin and a crystalline resin; when cross sections of the first toner particle and the second toner particle are observed, an area ratio Ss of the domain of the crystalline resin to a cross-sectional area of ​​the second toner particle is larger than an area ratio Sf of the domain of the crystalline resin to a cross-sectional area of ​​the first toner particle, The toner for developing electrostatic images according to the present invention, wherein a relationship between an area ratio Sf of the domain of the crystalline resin to a cross-sectional area of ​​the first toner particle and an area ratio Ss of the domain of the crystalline resin to a cross-sectional area of ​​the second toner particle satisfies Ss / Sf≧1.

2.

2. 2. The toner for developing an electrostatic image according to claim 1, wherein the second toner particles have an average circularity greater than that of the first toner particles.

3. 3. The toner for developing an electrostatic image according to claim 2, wherein the difference in average circularity between the first toner particles and the second toner particles is 0.01 or more.

4. 4. The toner for developing electrostatic images according to claim 2, wherein the average circularity of the first toner particles is 0.930 or more and 0.960 or less.

5. the crystalline resin is a crystalline polyester resin, 5. The toner for developing electrostatic images according to claim 1, wherein the melting temperature of the crystalline polyester resin is 60° C. or higher and 110° C. or lower.

6. 6. The toner for developing electrostatic images according to claim 1, wherein an area ratio Ss of a domain of the crystalline resin to a cross-sectional area of ​​the second toner particle is 50% or more and 80% or less.

7. 7. An electrostatic image developer comprising the toner for developing electrostatic images according to claim 1.

8. The toner for developing an electrostatic image according to any one of claims 1 to 6 is contained therein, A toner cartridge that is detachably attached to an image forming apparatus.

9. a developing unit that contains the electrostatic image developer according to claim 7 and develops an electrostatic image formed on a surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge that is detachably attached to an image forming apparatus.

10. 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 that contains the electrostatic image developer according to claim 7 and develops the electrostatic image formed on the surface of the image carrier into a toner image by the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to a 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:

11. a charging step of charging a surface of an 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 7; a transfer step of transferring the toner image formed on the surface of the image carrier onto a surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; The image forming method according to claim 1,

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