toner

Abstract

To provide a toner which maintains low-temperature fixability and image fastness, does not change in charging performance even after long-term use, and can output excellent image quality over a long period of time.SOLUTION: The toner contains toner particles containing a binder resin and an external additive, wherein the binder resin contains an amorphous polyester A and a crystalline polyester C, the external additive contains strontium titanate fine particles, the crystalline polyester C has a crystalline polyester segment c2 having a SP value of 9.0 to 12.0 (cal / cm3)0.5, and the following (i) or (ii) is satisfied: (I) a protrusion formed of silica is present on the surface of the strontium titanate fine particle, and (ii) a silica fine particle is fixed to the surface of the strontium titanate fine particle.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to toners used in electrophotography, electrostatic recording, electrostatic printing, and the like. [Background technology]

[0002] In recent years, as electrophotographic full-color copiers have become more widespread, there has been a demand for additional performance improvements, such as higher speed and higher image quality, as well as energy saving and compatibility with a wide variety of media. As a toner that responds to energy saving, a toner that can be fixed at a lower temperature and has excellent low-temperature fixability is required in order to reduce power consumption in the fixing process.

[0003] Furthermore, demand for print-on-demand (POD) printing is also increasing, requiring support for a wide variety of media, including not only plain paper but also cardboard and coated paper. Furthermore, images printed on these media must have robust image strength, such as heat resistance, regardless of the environment in which the printed material is used or stored.

[0004] Furthermore, toners with higher charging performance than ever before are required to meet the increasing demands for faster process speeds, long-term continuous use of machines, and to achieve stable image density. Toner contains external additives to impart charging properties. Generally, external additives are detached or migrate from the toner particle surface over long-term use, causing changes in charging properties.

[0005] To prevent this phenomenon, Patent Document 1 proposes a toner containing, as an external additive, fine powder of strontium titanate having Si-containing particles with a number-average equivalent circular diameter of 5 nm to 15 nm on the surface thereof. However, there is room for technical improvement in order to simultaneously achieve low-temperature fixability and image fastness as described above and to achieve charging stability. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-190724 Summary of the Invention [Problem to be solved by the invention]

[0007] The present disclosure provides a toner that maintains low-temperature fixability and image fastness, does not change in charging performance even with long-term use, and can output excellent image quality over a long period of time. [Means for solving the problem]

[0008] The present inventors have found that the above problems can be solved by using a toner having the following composition.

[0009] That is, the present disclosure provides a toner containing toner particles containing a binder resin and an external additive, the binder resin contains an amorphous polyester A and a crystalline polyester C, the external additive contains strontium titanate microparticles, The crystalline polyester C has an SP value of 9.0 to 12.0 (cal / cm 3 ) 0.5 Crystal a soluble polyester segment c2, Meet either (i) or (ii) below (i) The strontium titanate microparticles have convex portions formed of silica on their surfaces. (ii) Silica particles are fixed to the surface of the strontium titanate particles. The present invention relates to a toner characterized by the above-mentioned. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a toner that maintains low-temperature fixability and image fastness, does not change in charging performance even with long-term use, and can output excellent image quality over a long period of time. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of an apparatus for removing external additives from toner. DETAILED DESCRIPTION OF THE INVENTION

[0012] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Note that when XX is a group, multiple XXs may be selected, and the same applies to YY and ZZ.

[0013] The toner of the present disclosure is a toner containing toner particles containing a binder resin and an external additive, the binder resin contains an amorphous polyester A and a crystalline polyester C, the external additive contains strontium titanate microparticles, The crystalline polyester C has an SP value of 9.0 to 12.0 (cal / cm 3 ) 0.5 Crystal a soluble polyester segment c2, Meet either (i) or (ii) below (i) The strontium titanate microparticles have convex portions formed of silica on their surfaces. (ii) Silica particles are fixed to the surface of the strontium titanate particles. The toner is characterized by the above.

[0014] The present inventors have conducted research into toners that exhibit excellent image heat resistance and low-temperature fixability that allows fixing at lower temperatures, and have found the following. When a crystalline polyester is made compatible with an amorphous polyester to improve low-temperature fixability, the crystalline polyester acts as a plasticizer for the amorphous polyester, but on the other hand, the image heat resistance is deteriorated, and it is not possible to achieve both low-temperature fixability and image heat resistance.

[0015] Therefore, the present inventors have considered that it is important to achieve a certain degree of phase separation between the amorphous polyester and the crystalline polyester in order to achieve both good image heat resistance without impairing low-temperature fixability. In order to achieve phase separation between the amorphous polyester and the crystalline polyester, we considered increasing the crystallinity of the crystalline polyester to make it easier to form a folded structure.

[0016] The toner of the present disclosure contains a binder resin that contains an amorphous polyester A and a crystalline polyester C, and the crystalline polyester C has an SP value of 9.0 to 12.0 (cal / cm 3 ) 0.5 The result It has a crystalline polyester segment c2. When the SP value of the crystalline polyester segment c2 of the present disclosure is within the above range, phase separation of the crystalline polyester C from the amorphous polyester A can be suppressed. This makes it possible to increase the crystallinity of the crystalline polyester C, and to achieve both excellent low-temperature fixability and heat and pressure resistance.

[0017] The SP value of the crystalline polyester segment c2 is 9.0 (cal / cm 3 ) 0.5 If it is smaller, the compatibility with the amorphous polyester A cannot be controlled, and low-temperature fixability is impaired. The SP value of the crystalline polyester segment c2 is 12.0 (cal / cm 3 ) 0. 5 If it exceeds this value, the crystallization rate of the crystalline polyester C does not increase, and the heat and pressure resistance of the image does not improve.

[0018] The toner of the present disclosure further contains an external additive, and the external additive contains strontium titanate fine particles. (i) There are protrusions formed of silica on the surface of the strontium titanate fine particles. (ii) Silica particles are fixed to the surface of the strontium titanate particles.

[0019] The toner of the present disclosure may contain, as an external additive, strontium titanate microparticles having a plurality of silica protrusions on the surface thereof, or strontium titanate microparticles having silica microparticles fixed thereto. The strontium titanate microparticles of the present disclosure may have a surface covered with silica protrusions or silica microparticles.

[0020] In this disclosure, the SP value is 9.0 to 12.0 (cal / cm 3 ) 0.5 Crystalline polyester The charging performance of the toner is improved by externally adding, to a toner containing crystalline polyester C having segment c2, protrusions formed of silica as described above or strontium titanate microparticles with silica microparticles fixed to their surfaces.

[0021] In this specification, improved charging performance means that the charge amount of the toner does not change even when the toner is left in a high-temperature, high-humidity environment for a long period of time, and that there is no significant difference in the charge amount of the toner between a high-temperature, high-humidity environment and a low-temperature, low-humidity environment.

[0022] In the present disclosure, the present inventors believe that the reason why the charge amount of the toner does not change even when the toner is left in a high-temperature, high-humidity environment for a long period of time is as follows. The strontium titanate microparticles of the present disclosure have silica on their surfaces, which has a higher resistivity than strontium titanate, and therefore have less charge leakage during charging than conventional strontium titanate. As a result, even if the toner is left in a high-temperature, high-humidity environment for a long period of time, charge leakage from the toner is reduced, and change in charge amount is small.

[0023] Furthermore, in a low-temperature, low-humidity environment, the toner surface is uniformly protected by the strontium titanate fine particles, which prevents the problem of excessive toner charging.

[0024] Furthermore, since the toner contains a crystalline polyester resin having segments in the above-described range of SP values, it may be prone to adsorbing moisture, and it is believed that the effect of this is fully exerted when combined with the external additive according to the present disclosure.

[0025] The bulk density of the strontium titanate microparticles is preferably 0.20 to 0.65 g / mL, more preferably 0.30 to 0.60 g / mL, and particularly preferably 0.35 to 0.55 g / mL. By setting the bulk density of the strontium titanate particles to 0.20 to 0.65 g / mL, the fluidity of the particles as an external additive is improved, and the particles are uniformly added to the toner surface, which results in suppressing toner charge-up under low humidity conditions and improving charging performance. The bulk density of the strontium titanate microparticles can be changed by adjusting the amount of silica source added during synthesis and the synthesis temperature.

[0026] The BET specific surface area of ​​strontium titanate particles is 100-120m 2 / g, and 105 to 115m 2 / g is more preferred. When the BET specific surface area of ​​the strontium titanate fine particles is within the above range, the strontium titanate fine particles are uniformly added to the toner surface. The BET specific surface area of ​​the strontium titanate microparticles can be changed by the amount of silica source added during the synthesis of the strontium titanate microparticles and the synthesis temperature, just like the bulk density.

[0027] The strontium titanate fine particles preferably have a number average particle size D1 of primary particles of 15 to 70 nm, more preferably 20 to 50 nm, and particularly preferably 30 to 40 nm. By setting D1 to 15 nm to 70 nm, strontium titanate fine particles are externally added to the toner surface, and the charging performance of the toner can be improved. Like the BET specific surface area and bulk density, D1 can be varied by, for example, the amount of silica source added during the synthesis of strontium titanate and the synthesis temperature. Furthermore, D1 can be adjusted within the above range by, for example, the mixing ratio of the titanium oxide source and the metal source other than titanium when producing metal titanate particles by the atmospheric pressure heating reaction method described below, the reaction temperature when adding the alkaline aqueous solution, the reaction time, etc.

[0028] The content of the strontium titanate fine particles is preferably 0.4 to 1.4 parts by mass, more preferably 0.6 to 1.2 parts by mass, and particularly preferably 0.8 to 1.1 parts by mass, relative to 100 parts by mass of the toner particles. By ensuring that the content of the strontium titanate fine particles is within the above range, it is possible to achieve both good charging performance, low-temperature fixability, and image heat resistance.

[0029] Furthermore, it is preferable that the relationship between the abundance ratio x (atomic %) of Ti elements derived from strontium titanate microparticles on the toner surface, as measured by X-ray photoelectron spectroscopy (ESCA), and the abundance ratio y (atomic %) of Ti elements derived from strontium titanate desorbed from the toner when the external additives are desorbed from the toner using a shaker under the specified conditions described below, satisfies the following formula (1): 0≦y<0.75x-0.089 (1) When the relationship between x and y satisfies the above formula (1), it becomes possible to maintain the charging performance even after the durability test. It is more preferable that the relationship between x and y satisfies the following formula (2). 0≦y<0.75x-0.140 (2)

[0030] The above formula (1) indicates that the strontium titanate fine particles are difficult to separate from the toner. This is because strontium titanate fine particles are covered with Si elements having a higher electronegativity than Ti elements, and thus can strongly attract the non-bonding electron pairs of the ester groups derived from the crystalline polyester resin present on the toner particle surface. In order for the relationship between x and y to satisfy the above formula (1), it is possible to adjust the addition amount of the silica source and adjust DS1 described later to a suitable range.

[0031] The average number particle size DS1 of the primary particles of the convex portions formed of silica or silica fine particles of the strontium titanate fine particles is preferably 0 nm < DS1 < 5.0 nm, more preferably 2.0 nm < DS1 < 5.0 nm, and particularly preferably 4.0 nm < DS1 < 4.5 nm. When DS1 is within the above range, the release of the convex portions formed of silica or silica fine particles is reduced, and thus the charging property of the toner is improved.

[0032] The toner of the present disclosure contains an amorphous polyester A and a crystalline polyester C. The amorphous polyester A preferably has an amorphous polyester segment a1 and an amorphous polyester segment a2. For example, the amorphous polyester A is a block copolymer having an amorphous polyester segment a1 and an amorphous polyester segment a2. Here, the block copolymer refers to a copolymer obtained by bonding two types of polyesters.

[0033] In addition, the difference (SP value of a2 - SP value of a1) between the SP value of the amorphous polyester segment a2 and the SP value of the amorphous polyester segment a1 is preferably 0.80 (cal / cm 3 ) 0.5 or more. When the amorphous polyester A has an amorphous polyester segment a1 and an amorphous polyester segment a2, a polarity difference can be imparted within the molecule, and it is possible to achieve both a site with high affinity and a site with low affinity to the crystalline polyester C. As a result, the binder resin is easily plasticized, resulting in excellent low-temperature fixability, while the crystallization rate of the crystalline polyester C is increased, resulting in efficient crystallization in the toner fixing process and excellent heat and pressure resistance.

[0034] The difference between the SP value of the amorphous polyester segment a2 and the SP value of the amorphous polyester segment a1 (the SP value of a2 - the SP value of a1) is preferably 1.00 (cal / cm 3 ) 0.5 More preferably, it is 1.20 (cal / cm 3 ) 0.5 The upper limit is not particularly limited, but is preferably 1.80 (cal / cm 3 ) 0.5 More preferably, it is 1.60 (cal / cm 3 ) 0.5 The following is the result. A preferred range of (the SP value of a2 - the SP value of a1) is, for example, 1.00 to 1.80 (cal / cm 3 ) 0.5 , 1.00 to 1.60 (cal / cm 3 ) 0.5 , 1.20~1.80(cal / cm 3 ) 0.5 , 1.20~1.60(cal / cm 3 ) 0.5 is. The difference in SP value between the amorphous polyester segment a1 and the amorphous polyester segment a2 can be controlled by the type of monomer.

[0035] SP value of amorphous polyester segment a1 (cal / cm 3 ) 0.5 is preferably 10.00 to 11.00, more preferably 10.20 to 10.40. SP value of amorphous polyester segment a2 (cal / cm 3 )0.5 is preferably 11.00 to 12.00, more preferably 11.50 to 11.80.

[0036] The crystalline polyester C is preferably a polymer having a crystalline polyester segment c2 and a crystalline portion c1 bonded to the end of the crystalline polyester segment c2. The difference between the SP value of the crystalline polyester segment c2 and the SP value of the crystalline portion c1 (SP value of c2 - SP value of c1) is 0.75 (cal / cm 3 ) 0.5 It is preferable that this is equal to or greater than this. When crystalline polyester C has crystalline polyester segment c2 and a crystalline portion c1 at its end, a polarity difference can be created within the molecule, making it possible to have both portions with high and low affinity for amorphous polyester A. Therefore, the binder resin is easily plasticized, and excellent low-temperature fixability is obtained, while the crystallization rate of the crystalline polyester is increased, and the toner is efficiently crystallized in the fixing process, resulting in excellent heat and pressure resistance.

[0037] In addition, the difference between the SP value of the crystalline polyester segment c2 and the SP value of the crystalline portion c1 ( When the SP value of c2 - the SP value of c1 is within the above range, the compatibility of the crystalline polyester C with the amorphous polyester A can be suppressed, and therefore the crystallinity of the crystalline polyester C can be increased, resulting in excellent heat and pressure resistance. The difference between the SP value of the crystalline polyester segment c2 and the SP value of the crystalline portion c1 (SP value of c2 - SP value of c1) is preferably 0.80 (cal / cm 3 ) 0.5 More preferably, it is 1.00 (cal / cm 3 ) 0.5 More preferably, it is 1.20 (cal / cm 3 ) 0.5 The upper limit is not particularly limited, but is preferably 1.50 (cal / cm 3 ) 0.5More preferably, it is 1.30 (cal / cm 3 ) 0.5 The following is the result. A preferred range of (SP value of c2 - SP value of c1) is, for example, 0.80 to 1.50 (cal / cm 3 ) 0.5 , 0.80 to 1.30 (cal / cm 3 ) 0.5 , 1.00 to 1.50 (cal / cm 3 ) 0.5 , 1.00 to 1.30 (cal / cm 3 ) 0.5 is. The difference in SP value between the crystalline portion c1 and the crystalline polyester segment c2 can be controlled by the type of monomer.

[0038] SP value of crystalline portion c1 (cal / cm 3 ) 0.5 is preferably 8.50 to 9.20, more preferably 8.60 to 9.00. SP value of crystalline polyester segment c2 (cal / cm 3 ) 0.5 is preferably 9.50 to 10.50, more preferably 9.80 to 10.20.

[0039] The difference between the SP value of the amorphous polyester segment a1 and the SP value of the crystalline polyester segment c2 (SP value of a1 - SP value of c2) is 0.80 (cal / cm 3 ) 0.5 It is preferable that: When the difference in SP value between the amorphous polyester segment a1 and the crystalline polyester segment c2 is within the above range, it indicates that the amorphous polyester A and the crystalline polyester C each have a segment with high affinity. Therefore, the compatibility of the crystalline polyester C with the amorphous polyester A can be improved. Therefore, excellent low-temperature fixability can be obtained.

[0040] The difference between the SP value of the amorphous polyester segment a1 and the SP value of the crystalline polyester segment c2 (the SP value of a1 - the SP value of c2) is preferably 0.70 (cal / cm 3 ) 0.5 Less than or equal to 0.60 (cal / cm 3 ) 0.5 It is preferably 0.40 (cal / cm 3 ) 0.5 The lower limit is not particularly limited, but is 0.10 (cal / cm 3 ) 0.5 It is preferable that this is equal to or greater than this. A preferred range of (SP value of a1 - SP value of c2) is, for example, 0.10 to 0.70 (cal / cm 3 ) 0.5 , 0.10 to 0.60 (cal / cm 3 ) 0.5 , 0.10 to 0.40 (cal / cm 3 ) 0.5 is. The difference in SP value between the amorphous polyester segment a1 and the crystalline polyester segment c2 can be controlled by the type of monomer.

[0041] The difference between the SP value of the amorphous polyester segment a2 and the SP value of the crystalline portion c1 (SP value of a2 - SP value of c1) is 2.00 (cal / cm 3 ) 0.5 It is preferable that this is equal to or greater than this. When the difference in SP value between the amorphous polyester segment a2 and the crystalline portion c1 is within the above range, the compatibility of the crystalline polyester C with the amorphous polyester A can be suppressed, thereby increasing the degree of crystallinity and achieving the effect of excellent heat and pressure resistance.

[0042] The difference in SP value between the amorphous polyester segment a2 and the crystalline portion c1 (the SP value of a2 - the SP value of c1) is preferably 2.20 (cal / cm 3 ) 0.5 More preferably, it is 2.40 (cal / cm 3 ) 0.5 That is all. There is no particular upper limit, but it is preferred 3.50 (cal / cm 3 ) 0.5 More preferably, it is 3.00 (cal / cm 3 ) 0.5 The following is the result. A preferred range of (the SP value of a2 - the SP value of c1) is, for example, 2.00 to 3.50 (cal / cm 3 ) 0.5 , 2.00 to 3.00 (cal / cm 3 ) 0.5 , 2.20 to 3.50 (cal / cm 3 ) 0.5 , 2.20~3.00(cal / cm 3 ) 0.5 , 2.40 to 3.50 (cal / cm 3 ) 0.5 , 2.40~3.00(cal / cm 3 ) 0.5 is. The difference in SP value between the amorphous polyester segment a2 and the crystalline portion c1 can be controlled by the type of monomer.

[0043] <Strontium titanate fine particles> The strontium titanate microparticles of the present disclosure can be produced, for example, by a normal pressure heating reaction method. In this case, it is preferable to use a mineral acid peptized product of a hydrolyzed titanium compound as the titanium oxide source, and a water-soluble acidic strontium source compound as the strontium source. A method for forming convex portions formed of silica on the surface of strontium titanate microparticles or for fixing silica microparticles to the surface involves mixing a mineral acid peptized product of a hydrolyzed titanium compound, a strontium source, and a silica-containing particle source. The raw material mixture is reacted with an aqueous alkaline solution at 60 to 100° C., and then treated with an acid, whereby the product can be produced.

[0044] The atmospheric pressure heating reaction method will be explained below. The titanium oxide source is a mineral acid peptized product of a titanium compound hydrolyzate. Preferably, metatitanic acid obtained by a sulfuric acid method and having an SO content of 1.0 mass % or less, more preferably 0.5 mass % or less, is peptized by adjusting the pH to 0.8 to 1.5 with hydrochloric acid.

[0045] On the other hand, as a strontium source, strontium nitrate or hydrochloride can be used. The nitrate may be, for example, strontium nitrate. The hydrochloride may be, for example, strontium chloride. The strontium titanate particles obtained here have a perovskite crystal structure, which is preferable in that the environmental stability of charging is further improved. Examples of silica-containing particle sources include sodium silicate and silica. Addition of the silica-containing particle source can form silica-containing convex portions. Furthermore, it is preferable that Si elements are exposed on the surface of the silica-containing particles, as this can easily counteract the positive properties of the strontium titanate portion.

[0046] Factors that affect the number average particle size DS1 include the amount of silica-containing particle source added, which can be adjusted appropriately to obtain the desired particle size and particle shape. As the alkaline aqueous solution, a caustic alkali can be used, but among these, an aqueous sodium hydroxide solution is preferred.

[0047] In this production method, factors that affect the particle size and DS1 of the resulting metal titanate particles include the following. These include the pH when metatitanic acid is peptized with hydrochloric acid, the mixing ratio of the titanium oxide source, the strontium source, and the silica-containing particle source, the concentration of the titanium oxide source at the start of the reaction, the concentration of the silica-containing particle source, the temperature when the alkaline aqueous solution is added, the addition rate, the reaction time, and the stirring conditions.

[0048] Furthermore, in the step of adding the alkaline aqueous solution, the half-value width of the strontium titanate microparticles can be controlled by adding the alkaline aqueous solution while applying ultrasonic vibrations. By applying ultrasonic vibrations in the reaction step, the crystal precipitation rate increases, and particles with a small crystallite size can be obtained. It is preferable to rapidly cool the aqueous solution after the reaction by adding an aqueous alkali solution in order to control the half-value width.

[0049] Examples of methods for rapid cooling include adding pure water cooled to 10° C. or below until the temperature reaches the desired level. Rapid cooling can prevent the crystallite size from increasing during the cooling process. Furthermore, if the reaction is stopped by suddenly lowering the temperature of the system, for example by immersing the system in ice water, after the addition of the alkaline aqueous solution, the reaction can be forcibly stopped before the crystal growth reaches saturation, and the particle size distribution can be controlled.

[0050] Furthermore, the particle size distribution can also be controlled by reducing the stirring speed or changing the stirring method to make the reaction system non-uniform. These factors can be adjusted as appropriate to obtain metal titanate particles, DS1, with the desired particle size and particle size distribution. In order to prevent the formation of carbonates during the reaction process, it is preferable to prevent contamination with carbon dioxide gas, for example by carrying out the reaction under a nitrogen gas atmosphere.

[0051] The mixing ratio of the titanium oxide source and the strontium source during the reaction, where strontium is represented by Sr and its oxide is represented by SrO, is preferably SrO / TiO2 molar ratio of 0.90 or more and 1.40 or less, more preferably 1.05 or more and 1.20 or less.

[0052] When the SrO / TiO2 (molar ratio) is 1.00 or less, the reaction product tends to contain not only metal titanate but also unreacted titanium oxide. Because strontium has a relatively high solubility in water, while the titanium oxide source has a low solubility in water, when the SrO / TiO2 (molar ratio) is 1.00 or less, the reaction product tends to contain not only metal titanate but also unreacted titanium oxide.

[0053] The concentration of the titanium oxide source at the beginning of the reaction is preferably 0.050 mol / L or more and 1.300 mol / L or less, and more preferably 0.080 mol / L or more and 1.200 mol / L or less, in terms of TiO2. By increasing the concentration of the titanium oxide source at the beginning of the reaction, the number average particle size of the primary particles of the strontium titanate fine particles can be reduced.

[0054] When adding the aqueous alkaline solution, if the temperature is 100°C or higher, a pressure vessel such as an autoclave will be required, and practically, the temperature is preferably in the range of 60°C to 100°C.

[0055] Furthermore, the slower the addition rate of the alkaline aqueous solution, the larger the particle size of the strontium titanate microparticles and the convex portions formed of silica or the silica microparticles obtained, whereas the faster the addition rate, the smaller the particle size of the strontium titanate microparticles and the convex portions formed of silica or the silica microparticles obtained. The rate of addition of the aqueous alkaline solution is preferably 0.001 to 1.2 equivalents / h, more preferably 0.002 to 1.1 equivalents / h, relative to the charged raw material. These rates can be adjusted appropriately depending on the particle size to be obtained.

[0056] In this production method, it is preferable to further treat the strontium titanate microparticles obtained by the atmospheric pressure heating reaction with an acid. When the atmospheric pressure heating reaction is carried out to produce strontium titanate microparticles, if the mixing ratio of the titanium oxide source and the strontium source exceeds 1.00 in terms of SrO / TiO2 (molar ratio), the unreacted strontium remaining after the reaction is completed is released into the air. In order to facilitate uniform coating of the surface treatment agent, it is advisable to add an alkaline aqueous solution and then perform an acid treatment to remove any unreacted metal source.

[0057] In the acid treatment, the pH is preferably adjusted to 2.5 or more and 7.0 or less using hydrochloric acid, and more preferably adjusted to 4.5 or more and 6.0 or less. As the acid, in addition to hydrochloric acid, nitric acid, acetic acid, etc. can be used for the acid treatment. When sulfuric acid is used, metal sulfates that have low solubility in water are likely to be generated. The shape of the strontium titanate microparticles may be controlled. The strontium titanate microparticles are preferably cubic or rectangular. Furthermore, a dry mechanical treatment may be used as a method for controlling the shape of the strontium titanate microparticles.

[0058] The strontium titanate fine particles may be surface-treated with a surface treatment agent, which is not particularly limited, but may include a disilylamine compound, a halogenated silane compound, a silicone compound, or a silane coupling agent.

[0059] The disilylamine compound is a compound having a disilylamine (Si-N-Si) moiety. Examples of the disilylamine compound include hexamethyldisilazane (HMDS), N-methyl-hexamethyldisilazane, and hexamethyl-N-propyldisilazane. Examples of the halogenated silane compound include dimethyldichlorosilane.

[0060] Examples of silicone compounds include silicone oils and silicone resins (varnishes). Examples of silicone oils include dimethyl silicone oils, methylphenyl silicone oils, α-methylstyrene-modified silicone oils, chlorophenyl silicone oils, and fluorine-modified silicone oils. Examples of silicone resins (varnishes) include methyl silicone varnishes and phenylmethyl silicone varnishes.

[0061] Examples of the silane coupling agent include a silane coupling agent having an alkyl group and an alkoxy group, a silane coupling agent having an amino group and an alkoxy group, and a fluorine-containing silane coupling agent.

[0062] More specific examples of the silane coupling agent include dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, trimethylmethoxysilane, trimethyldiethoxysilane, triethylmethoxysilane, triethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyldimethoxymethylsilane, γ-aminopropyldiethoxymethylsilane, 3,3,3-trifluoropropyldimethoxysilane, 3,3,3-trifluoropropyldiethoxysilane, perfluorooctylethyltriethoxysilane, and 1,1.1-trifluorohexyldiethoxysilane.

[0063] In particular, it is preferable that the surface is treated with a fluorine-based silane coupling agent such as trifluoropropyltrimethoxysilane or perfluorooctylethyltriethoxysilane. The amount of the treatment agent is preferably 0.5 to 20.0 parts by mass per 100 parts by mass of the strontium titanate fine particles. The above-mentioned surface treatment agents may be used alone or in combination of two or more.

[0064] <Amorphous polyester A> Amorphous polyester segment a1 and amorphous polyester segment a2 of amorphous polyester A Examples of the monomer used for the segment a2 include the linear aliphatic polyhydric alcohol a having 2 to 10 carbon atoms and the following.

[0065] Polyhydric alcohols (dihydric, trihydric or higher alcohols), polycarboxylic acids (dihydric, trihydric or higher carboxylic acids), acid anhydrides thereof or lower alkyl esters thereof are used. As the polyhydric alcohol monomer, the following polyhydric alcohol monomers can be used.

[0066] Examples of dihydric alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenol represented by formula (A) and derivatives thereof, and diols represented by formula (B).

[0067] [ka] (In formula (A), R is an ethylene or propylene group, x and y are each an integer of 0 or more, and the average value of x+y is 0 or more and 10 or less.)

[0068] [ka]

[0069] Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene. Among these, glycerol, trimethylolpropane, and pentaerythritol are preferred. These dihydric and trihydric or higher alcohols can be used alone or in combination.

[0070] As the polycarboxylic acid monomer for the polyester resin, the following polycarboxylic acid monomers can be used. Examples of the dicarboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, and n-octenylsuccinic acid. Examples of the acid include octyl succinic acid, isooctyl succinic acid, isooctyl succinic acid, anhydrides of these acids, and lower alkyl esters of these acids. Of these, maleic acid, fumaric acid, terephthalic acid, and n-dodecenyl succinic acid are preferred.

[0071] Examples of trivalent or higher carboxylic acids, their acid anhydrides, and their lower alkyl esters include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid, their acid anhydrides, and their lower alkyl esters.

[0072] Among these, 1,2,4-benzenetricarboxylic acid, i.e., trimellitic acid or its derivatives, is particularly preferred because it is inexpensive and the reaction can be easily controlled. These dicarboxylic acids and tricarboxylic or higher carboxylic acids can be used alone or in combination.

[0073] The amorphous polyester A has an amorphous polyester segment a1 and an amorphous polyester segment a2. The amorphous polyester segment a2 has a monomer unit of a linear aliphatic polyhydric alcohol a having 2 to 10 carbon atoms as a unit forming a polyester skeleton. Examples of the linear aliphatic polyhydric alcohol a having 2 to 10 carbon atoms include ethylenediol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, and decanediol.

[0074] The amorphous polyester segment a2 is preferably a condensation polymer of a linear aliphatic polyhydric alcohol a and a dicarboxylic acid component. The content of the monomer unit of the linear aliphatic polyhydric alcohol a in the amorphous polyester segment a2 is preferably 20 to 50 mass%, more preferably 25 to 40 mass%. The content of the monomer unit of the dicarboxylic acid component in the amorphous polyester segment a2 is preferably 50.0 to 80.0 mass%, more preferably 60.0 to 75.0 mass%.

[0075] The amorphous polyester segment a1 preferably has a monomer unit based on a polyhydric aromatic phenol. The polyhydric aromatic phenol is preferably at least one selected from the group consisting of hydrogenated bisphenol A, bisphenol represented by the above formula (A), and derivatives thereof. More preferably, it is at least one selected from the group consisting of alkylene (ethylene or propylene) oxide adducts of bisphenol A represented by formula (A). The amorphous polyester segment a1 preferably contains 50.0 to 70.0 mass %, more preferably 60.0 to 70.0 mass %, of the monomer unit based on a polyhydric aromatic phenol.

[0076] The amorphous polyester segment a1 is preferably a condensation polymer of a dicarboxylic acid component containing a linear aliphatic polyhydric alcohol having 6 to 14 carbon atoms (preferably 8 to 12 carbon atoms) and a polyhydric aromatic phenol. The content of the monomer unit of the dicarboxylic acid component containing a linear aliphatic polyhydric alcohol having 6 to 14 carbon atoms in the amorphous polyester segment a1 is preferably 30.0 to 50.0 mass%, more preferably 30.0 to 40.0 mass%.

[0077] The content of amorphous polyester segment a1 in amorphous polyester A is preferably 70.0 to 95.0 mass%, more preferably 75.0 to 85.0 mass%. The content of amorphous polyester segment a2 in amorphous polyester A is 5.0 to 30. The content is preferably 0% by mass, and more preferably 15.0 to 25.0% by mass.

[0078] The method for producing the polyester is not particularly limited, and known methods can be used. For example, the aforementioned alcohol monomer and carboxylic acid monomer are simultaneously charged and polymerized via an esterification reaction or transesterification reaction and a condensation reaction to produce a polyester resin. The polymerization temperature is not particularly limited, but is preferably in the range of 180°C to 290°C. For polyester polymerization, a polymerization catalyst such as a titanium-based catalyst, a tin-based catalyst, zinc acetate, antimony trioxide, or germanium dioxide can be used. In particular, it is more preferable that the amorphous polyester A is a polyester resin polymerized using a tin-based catalyst.

[0079] <Crystalline Polyester C> The crystalline polyester C is preferably a polymer having a crystalline polyester segment c2 and a crystalline portion c1 bonded to the end of the crystalline polyester segment c2.

[0080] Monomers used for the crystalline polyester segment c2 include polyhydric alcohols (dihydric, trihydric or higher alcohols), polycarboxylic acids (dihydric, trihydric or higher carboxylic acids), their acid anhydrides or their lower alkyl esters. The crystalline polyester segment c2 is preferably a condensation polymer of a linear aliphatic polyhydric alcohol b having 2 to 10 carbon atoms (preferably 2 to 6, more preferably 2 to 4, and even more preferably 2) and an aliphatic dicarboxylic acid.

[0081] The polyhydric alcohol monomer used in the crystalline polyester C may be any of the following polyhydric alcohol monomers. The polyhydric alcohol monomer is not particularly limited, but is preferably a chain (more preferably a linear) aliphatic diol, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,4-butadiene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, and neopentyl glycol. Among these, linear aliphatic α,ω-diols such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol are particularly preferred.

[0082] Polyhydric alcohol monomers other than the above polyhydric alcohols can also be used. Among the polyhydric alcohol monomers, dihydric alcohol monomers include aromatic alcohols such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A; 1,4-cyclohexanedimethanol; and the like. Furthermore, among the polyhydric alcohol monomers, trihydric or higher polyhydric alcohol monomers include aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; and aliphatic alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, and trimethylolpropane.

[0083] The polycarboxylic acid monomer used in the crystalline polyester C may be any of the following polycarboxylic acid monomers. The polycarboxylic acid monomer is not particularly limited, but is preferably a chain (more preferably a linear) aliphatic dicarboxylic acid. Specific examples include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, glutaconic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, and decanedicarboxylic acid. Examples of the acid include carboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and itaconic acid, and also include those obtained by hydrolyzing the acid anhydrides or lower alkyl esters of these acids.

[0084] Polycarboxylic acids other than the above polycarboxylic acid monomers can also be used. Among the other polycarboxylic acid monomers, examples of dicarboxylic acids include aromatic carboxylic acids such as isophthalic acid and terephthalic acid, aliphatic carboxylic acids such as n-dodecylsuccinic acid and n-dodecenylsuccinic acid, and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, as well as acid anhydrides or lower alkyl esters thereof.

[0085] Furthermore, among the other carboxylic acid monomers, examples of trivalent or higher polyvalent carboxylic acids include aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and pyromellitic acid, and aliphatic carboxylic acids such as 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, and 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, as well as derivatives such as acid anhydrides and lower alkyl esters of these.

[0086] The content of monomer units derived from linear aliphatic polyhydric alcohol b having 2 to 10 carbon atoms (preferably 2 to 6, more preferably 2 to 4, and even more preferably 2) in the crystalline polyester segment c2 is preferably 15.0 to 40.0 mass%, more preferably 17.0 to 35.0 mass%. The content of monomer units derived from aliphatic dicarboxylic acids in the crystalline polyester segment c2 is preferably 60.0 to 85.0 mass%, more preferably 65.0 to 83.0 mass%.

[0087] The content of the crystalline polyester segment c2 in the crystalline polyester C is preferably 80.0 to 99.0 mass %, more preferably 90.0 to 98.0 mass %, and even more preferably 94.0 to 97.0 mass %.

[0088] The content of the monomer unit constituting the crystalline portion c1 in the crystalline polyester C is preferably 1.0 to 20.0% by mass, and more preferably 2.0 to 10.0% by mass.

[0089] The content of the crystalline polyester C in the binder resin is preferably 3 to 20% by mass, more preferably 8 to 15% by mass. Within this range, the low-temperature fixability, heat and pressure resistance, and blooming resistance become better. The content of the amorphous polyester A in the binder resin is preferably from 80 to 97% by mass, more preferably from 85 to 92% by mass.

[0090] The crystalline polyester C can be produced by a conventional polyester synthesis method. For example, the carboxylic acid monomer and the alcohol monomer are subjected to an esterification reaction or a transesterification reaction, followed by a conventional polycondensation reaction under reduced pressure or by introducing nitrogen gas to obtain the crystalline polyester segment c2. Thereafter, at least one selected from the group consisting of aliphatic monocarboxylic acids and aliphatic monoalcohols (preferably aliphatic monocarboxylic acids) having 10 to 30 carbon atoms (preferably 15 to 25, more preferably 19 to 23) is added and an esterification reaction is carried out to form a crystalline portion c1 at the end of the crystalline polyester segment c2, thereby obtaining crystalline polyester C.

[0091] The above esterification or transesterification reaction may be carried out, if necessary, using a conventional esterification catalyst such as sulfuric acid, titanium butoxide, dibutyltin oxide, manganese acetate, magnesium acetate, or the like. can be carried out using a transesterification catalyst.

[0092] The polycondensation reaction can be carried out using a conventional polymerization catalyst, such as titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide, etc. The polymerization temperature and the amount of catalyst are not particularly limited and may be determined appropriately.

[0093] In the esterification or transesterification reaction or polycondensation reaction, in order to increase the strength of the resulting crystalline polyester C, it is also possible to use a method in which all of the monomers are charged at once, or in order to reduce the amount of low-molecular-weight components, a divalent monomer is first reacted, and then a trivalent or higher valent monomer is added and reacted.

[0094] <Developer> The toner of the present disclosure can be used as a one-component developer, but in order to suppress localized charge on the toner surface, it can also be mixed with a magnetic carrier and used as a two-component developer.

[0095] Examples of the magnetic carrier that can be used include generally known ones such as iron oxide; metal particles such as iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium, and rare earth elements, alloy particles thereof, and oxide particles thereof; magnetic materials such as ferrite; and magnetic material-dispersed resin carriers (so-called resin carriers) containing a magnetic material and a binder resin that holds the magnetic material in a dispersed state.

[0096] When the toner is mixed with a magnetic carrier to be used as a two-component developer, the mixing ratio of the magnetic carrier in this case is preferably 2% by mass or more and 15% by mass or less, and more preferably 4.0% by mass or more and 13.0% by mass or less, in terms of the toner concentration in the two-component developer.

[0097] <Toner manufacturing method> The method for producing toner particles is not particularly limited, but a pulverization method is preferred from the viewpoint of dispersing toner materials such as pigments. The procedure for producing toner by the pulverization method will be described below.

[0098] In the raw material mixing process, predetermined amounts of materials constituting the toner particles, such as binder resin, release agent, colorant, and optionally other components such as charge control agent, are weighed, blended, and mixed. Examples of mixing devices include a double cone mixer, a V-type mixer, a drum mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a Mechano Hybrid (manufactured by Nippon Coke and Engineering Co., Ltd.).

[0099] Next, the mixed materials are melt-kneaded to disperse the pigment and other components in the binder resin. For this melt-kneading process, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. Single- or twin-screw extruders are the mainstream due to their advantage of continuous production. Examples include a KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), a TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), a PCM kneader (manufactured by Ikegai Iron Works), a twin-screw extruder (manufactured by KCK Corporation), a Ko-Kneader (manufactured by Buss Co., Ltd.), and a Kneadex (manufactured by Nippon Coke and Engineering Co., Ltd.). Furthermore, the resin composition obtained by melt-kneading may be rolled using a twin roll or the like and cooled with water or the like in a cooling process.

[0100] The cooled resin composition is then crushed to a desired particle size in a crushing process. In the crushing process, the resin composition is coarsely crushed using a crusher such as a crusher, a hammer mill, or a feather mill, and then further crushed into a desired particle size using a crusher such as a Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.) or a Super Rotor (manufactured by Nisshin E&C Co., Ltd.). The mixture is then finely pulverized using a Turbo Mill (manufactured by Turbo Kogyo) or an air jet type fine pulverizer.

[0101] Thereafter, as necessary, the mixture is classified using a classifier or sieve such as an inertial classification type Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), a centrifugal classification type Turboplex (manufactured by Hosokawa Micron Corporation), a TSP Separator (manufactured by Hosokawa Micron Corporation), or a Faculty (manufactured by Hosokawa Micron Corporation). The obtained toner particles are treated by adding an external additive to the surface of the toner particles to obtain a toner.

[0102] Examples of methods for externally adding external additives include a method in which classified toner and various known external additives are mixed in predetermined amounts, and stirred and mixed using a mixing device such as a double con mixer, a V-type mixer, a drum mixer, a super mixer, a Henschel mixer, a Nauta mixer, a Mechano Hybrid (manufactured by Nippon Coke and Engineering Co., Ltd.), or a Nobilta (manufactured by Hosokawa Micron Corporation) as an external additive machine. In the present disclosure, the strontium titanate fine particles can be externally added by the external addition treatment described above.

[0103] The methods for measuring various physical properties of the toner and raw materials are described below. <Method for separating each material from toner> The materials contained in the toner can be separated from the toner by utilizing the difference in solubility in the solvent of each material.

[0104] First separation: The toner is dissolved in methyl ethyl ketone (MEK) at 23°C, and the soluble matter (amorphous polyester A) is separated from the insoluble matter (crystalline polyester C, wax, colorant, external additives, etc.). Second separation: The insoluble matter obtained in the first separation (crystalline polyester C, wax, colorant, inorganic fine particles, etc.) is dissolved in MEK at 100°C, and the soluble matter (crystalline polyester C, wax) is separated from the insoluble matter (colorant, external additives, etc.). Third separation: The soluble matter (crystalline polyester C, wax) obtained in the second separation is dissolved in chloroform at 23°C, and the soluble matter (crystalline polyester C) is separated from the insoluble matter (wax).

[0105] <Method for separating strontium titanate microparticles, silica microparticles, and other external additives> When measuring the physical properties of the strontium titanate fine particles, silica fine particles, and toner particles from the toner, the strontium titanate fine particles and other external additives can be separated from the toner and then measured. The toner is ultrasonically dispersed in methanol to remove the strontium titanate particles and other external additives, and then allowed to stand for 24 hours. The settled toner particles are separated from the strontium titanate particles and other external additives dispersed in the supernatant, and the toner particles are isolated by separating and recovering them and thoroughly drying them. The supernatant can also be centrifuged to isolate the strontium titanate particles and silica particles.

[0106] <Content of strontium titanate microparticles and silica microparticles> Strontium titanate microparticles and silica microparticles are isolated from the toner using the method described above. The masses of the resulting toner particles, strontium titanate microparticles, and silica microparticles are measured. The respective contents per 100 parts by mass of toner particles are calculated from the masses of the resulting toner particles, strontium titanate microparticles, and silica microparticles.

[0107] <Method for measuring the content of monomer units of various polymerizable monomers in amorphous polyester A and crystalline polyester C> The content ratio of the monomer units of various polymerizable monomers in amorphous polyester A and crystalline polyester C was measured as follows: 1 H-NMR was performed under the following conditions.

[0108] Measuring device: FT NMR device JNM-EX400 (manufactured by JEOL Ltd.) Measurement frequency: 400MHz Pulse condition: 5.0 μs Frequency range: 10500Hz Accumulation count: 64 times Measurement temperature: 30℃ Sample: 50 mg of the measurement sample is placed in a sample tube with an inner diameter of 5 mm, deuterated chloroform (CDCl3) is added as a solvent, and the sample is dissolved in a thermostatic bath at 40°C.

[0109] obtained 1 From the H-NMR chart, the integral value S of the peaks assigned to the constituent elements of the monomer units of various polymerizable monomers 1、 S 2、 S3, S n Calculate.

[0110] The content ratio of the monomer units of various polymerizable monomers is expressed by the above integral values ​​S1, S2, S3 and S n It is calculated as follows using the following: 2、 n3···n n is the number of hydrogen atoms in the constituent element to which the peak of interest for each site is assigned. Content ratio (mol%) of monomer units by various polymerizable monomers = {(S n / n n ) / ((S1 / n1) + (S2 / n2) + (S3 / n3) ··· + (S n / n n ))} × 100

[0111] Change the numerator term of the same operation to calculate the amount of monomer units by various polymerizable monomers. When a polymerizable monomer that does not contain a hydrogen atom is used in the monomer units by various polymerizable monomers, 13 Use 13C-NMR to measure the nuclei to be 13 13C and perform the measurement in single pulse mode, 1 and calculate in the same way by 1H-NMR.

[0112] <SP value calculation method> The SP values of the amorphous polyester segment a1, the amorphous polyester segment a2, the crystalline part c1, and the crystalline polyester segment c2 are obtained as follows according to the calculation method proposed by Fedors. For the monomer units by each polymerizable monomer, for the atoms or atomic groups in the molecular structure, the evaporation energy (Δei) (cal / mol) and the molar volume (Δvi) (cm 3 / mol) are obtained from the table described in "Polym. Eng. Sci., 14(2), 147 - 154(1974)", and (ΣΔei / ΣΔvi) 0.5 is taken as the SP value (cal / cm 3 ) 0.5 and denoted as such.

[0113] <Measurement of bulk density> The method for measuring the bulk density of the external additive of the present disclosure is performed using a graduated cylinder. Specifically, it is as follows. (1) Weigh (m) 1.0 g of the external additive for toner with an accuracy of ±0.02%. (2) Gently put the weighed external additive for toner into a dry 200 mL graduated cylinder (minimum scale unit: 2 mL) without consolidation. (3) Carefully level the upper surface of the externally added toner additive without compacting it, and after a certain period of time, read the expansion volume at its minimum scale unit (V0). (4) Calculate the bulk density using m / V0.

[0114] <Measurement of BET Specific Surface Area> The BET specific surface area of the silica fine particles can be determined by the low-temperature gas adsorption method according to the BET method (BET multipoint method) and the dynamic constant pressure method. Using a specific surface area measuring device (product name: Gemini 2375 Ver.5.0, manufactured by Shimadzu Corporation), adsorb nitrogen gas on the sample surface, and measure using the BET multipoint method to calculate the BET specific surface area (m 2 / g).

[0115] <Measurement Method for Number-Average Particle Size (D1) of Primary Particles of Strontium Titanate Fine Particles and Number-Average Particle Size (DS1) of Primary Particles of Protrusions Formed by Silica or Silica Fine Particles> The number-average particle size of the primary particles of strontium titanate fine particles and the number-average particle size (DS1) of the primary particles of the protrusions formed by silica present on the surface or silica fine particles are measured using a transmission electron microscope (TEM) "JEM2800" (manufactured by JEOL Ltd.). First, prepare the measurement sample. Add 1 mL of isopropanol to approximately 5 mg of the externally added agent (strontium titanate fine particles or silica fine particles to be measured), and disperse it for 5 minutes using an ultrasonic disperser (ultrasonic cleaner) to obtain a dispersion. Next, prepare the measurement sample by dropping 1 drop of the above dispersion onto a microgrid with a support film for TEM (150 mesh) and drying it. When preparing the measurement sample, the externally added agent separated from the toner can be used according to the method described in the above <Method for Separating Each Material from Toner>.

[0116] Next, images are taken using a transmission electron microscope (TEM) at an accelerating voltage of 200 kV at a magnification (e.g., 200k to 1M) that allows sufficient measurement of the external additives in the field of view, and the particle sizes of 100 randomly selected primary particles of the external additives are measured to determine the number-average particle size. The particle size of the primary particles is measured using the image processing software "Image-Pro Plus ver. 4.0 (manufactured by Media Cybernetics)." The particle size of the external additive other than the convex portions is measured by measuring the major axis. The convex portions will be described later. The criterion for determining whether silica microparticles are adhered to the surface of strontium titanate microparticles is that if there is an area where only Si is mapped outside the Sr mapping area in the EDS elemental mapping image of the strontium titanate microparticles shown below, silica microparticles are deemed to be adhered. If the silica particles were simply attached to the surface of the strontium titanate particles, they would separate from the surface of the strontium titanate particles due to centrifugation when separating them from the toner or ultrasonic dispersion when preparing the measurement sample, and would not appear in the EDS elemental mapping image. However, if they are firmly attached, they will not separate, and there will be an area outside the Sr mapping area where only Si is mapped.

[0117] The convex portions formed by silica are determined by observing secondary electron image (SEI) and EDS mapping measurements of the strontium titanate microparticles separated by the above-mentioned method using a transmission electron microscope (TEM) "JEM2800" (manufactured by JEOL). For EDS mapping measurements, a silicon drift detector with a large detection element area is used, allowing for highly sensitive EDS mapping measurements. The conditions are as follows:

[0118] (Shape image acquisition conditions) Mode: STEM observation mode Accelerating voltage: 200 kV Magnification: 1,000,000x Probe size: 1 nm Detector: Secondary electron detector (SEI detector) SEI image size: 1024 x 1024 pixels

[0119] (STEM-EDS elemental mapping image acquisition conditions) A STEM-EDS elemental mapping image is acquired in the same field of view as the SEI image observation field. EDS detector: JEOL JED-2300T dry SD100GV detector (detector area: 100 mm 2 ) EDS analyzer: Thermo Fisher Scientific NORAN System 7 Drift correction factor: 2 Dwell Time: 30 μs Accumulation count: 100 frames X-ray CountRate:4000~10000cps Elemental mapping image size: 256 x 256 pixels Quantitative map images were extracted from the collected spectral mapping data using the quantitative map mode in the measurement command of the NORAN System 7. The settings were as follows: Kernel size: 3×3 Quantitative map setting: High (slow) Filter Fit Type: High Precision (Slow)

[0120] First, a morphology image of the strontium titanate microparticle is acquired. Then, EDS elemental quantitative mapping images of Si and Sr elements are acquired at the same position at the same magnification, and these EDS elemental mapping images are superimposed. In the area where the Si mapping and Sr mapping overlap, it is difficult to precisely separate the silica-containing portion. On the other hand, in the outer periphery of the strontium titanate microparticle, there is an area where only Si is mapped outside the Sr mapping area, so the silica-containing portion can be clearly identified. In the outer periphery where silica is confirmed to be contained, convex portions are identified from the previously acquired morphology image. In the convex portion observed in the outer periphery containing silica, a straight line is drawn connecting the valleys at both ends of the convex portion, and in this disclosure, a convex portion is defined as a convex portion where the distance between the apex of the convex and the line is 1 nm or more. The length of the line connecting the valleys at both ends of the convex portion is defined as the particle size of the convex portion.

[0121] <Proportion of Ti element originating from strontium titanate microparticles on the toner surface> The sample holder is a platen with an inner diameter of 60 mm (equipped with a screw hole with a diameter of approximately 1 mm for fixing the sample) that comes with the device. The screw hole in the platen is a through hole, so it is plugged with resin or similar to create a recess about 0.5 mm deep for powder measurement. The measurement sample is packed into the recess with a spatula or similar tool and leveled off to create the sample.

[0122] The ESCA equipment and measurement conditions are as follows: Equipment used: ULVAC-PHI PHI5000VersaProbe II Analysis method: Narrow analysis Measurement conditions: X-ray source: Al-Kα X-ray conditions: 100μ25W15kV Photoelectron capture angle: 45° Pass Energy: 58.70 eV Measurement range: 300 μm x 200 μm Measurements are carried out under the above conditions.

[0123] The analysis method involves first correcting the peak derived from the C-C bond of the carbon 1s orbital to 285 eV. Then, from the peak area derived from the Ti element, whose peak top is detected between 100 eV and 105 eV, the amount derived from each atom relative to the total amount of the constituent elements is calculated using the relative sensitivity factor provided by ULVAC-PHI.

[0124] <Proportion of Ti element derived from strontium titanate separated from toner> 0.85 g of the externally added toner and 9.15 g of the magnetic carrier are precisely weighed into a 50 mL resin bottle and shaken for 5 minutes in a shaker (YS-8D model: manufactured by Yayoi Co., Ltd.) at a shaking speed of 200 rpm and a shaking width of 80 mm. A 635 mesh screen 3 is placed in a metallic measuring container 2 of the apparatus shown in FIG. 1, and about 0.1 g of the mixture is placed on the screen 3, and a metallic lid 4 is placed on the screen. Next, in the suction device 1 (at least the part in contact with the measurement container 2 is insulated), an Amano Cleaner V-3SDR (manufactured by Amano Corporation) is used as the suction device to suck from the suction port 7, and the air flow control valve 6 is adjusted to make the pressure on the vacuum gauge 5 0.8 kPa. In this state, suction is applied for 1 minute to remove the external additives from the mixture. The external additives adhering to the magnetic carrier remaining on the mesh are considered to be external additives detached from the toner, and the abundance ratio of Ti element derived from strontium titanate is calculated in the same manner as the abundance ratio of Ti element derived from strontium titanate microparticles on the toner surface. In FIG. 1, reference numeral 8 denotes a capacitor and reference numeral 9 denotes an electrometer. [Example]

[0125] The present disclosure will be specifically described below with reference to examples, but these examples are not intended to limit the present disclosure in any way. In the following formulations, parts are by mass unless otherwise specified.

[0126] [Example 1] <Production of amorphous polyester segment a1-1> Polyhydric alcohol; Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane 65 parts Polycarboxylic acid; tetradodecanedioic acid 35 parts The above monomer components were placed in a reaction vessel equipped with a stirrer that had been thoroughly heated and dried, and 0.05 parts of titanium tetrabutoxide was added per 100 parts of the above mixture. Nitrogen gas was introduced into the vessel to maintain an inert atmosphere, and the temperature was raised to 260°C to polymerize the amorphous polyester segment a1-1.

[0127] <Production of amorphous polyester segment a1-2> Amorphous polyester segment a1-2 was obtained in the same manner as in the production example of amorphous polyester segment a1-1, except that the types and amounts of the polycarboxylic acid monomer and polyhydric alcohol monomer were changed to those shown in Table 1.

[0128] [Table 1] The abbreviations in Table 1 are as follows: BPA-PO: Bisphenol A propylene oxide adduct BPA-EO: Bisphenol A ethylene oxide adduct TDA: tetradecanedioic acid SA: Suberic acid

[0129] <Production of amorphous polyester segment a2-1> Polycarboxylic acid; terephthalic acid 73 parts Linear aliphatic polyhydric alcohol a; ethylenediol 27 parts The above monomer components were placed in a reaction vessel equipped with a stirrer that had been thoroughly heated and dried, and 0.05 parts of titanium tetrabutoxide was added per 100 parts of the above mixture. Nitrogen gas was introduced into the vessel to maintain an inert atmosphere, and the temperature was raised to 260°C to polymerize the amorphous polyester segment a2-1.

[0130] <Production of amorphous polyester segment a2-2> Amorphous polyester segment a2-2 was obtained in the same manner as in the production example of amorphous polyester segment a2-1, except that the types and amounts of the polycarboxylic acid monomer and polyhydric alcohol monomer were changed to those shown in Table 2.

[0131] [Table 2] The abbreviations in Table 2 are as follows: TPA: Terephthalic acid ED: Ethylenediol (ethylene glycol) BD: butanediol

[0132] <Production example of amorphous polyester A1> Amorphous polyester segment a1-1: 80 parts Amorphous polyester segment a2-1: 20 parts The above materials were placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. Then, 1.0 part of tin 2-ethylhexanoate (esterification catalyst) was added as a catalyst for 100 parts of the total amount of segments. The atmosphere in the flask was then purged with nitrogen gas, and the temperature was gradually raised with stirring. The reaction was allowed to proceed for 2.5 hours while stirring at 200°C. The pressure in the reaction vessel was then reduced to 8.3 kPa and maintained at this temperature for 1 hour. The reaction was then cooled to 180°C and returned to atmospheric pressure (first reaction step).

[0133] Trimellitic anhydride: 0.04 parts tert-Butylcatechol (polymerization inhibitor): 0.1 parts The above materials were then added, the pressure in the reactor was reduced to 8.3 kPa, and the reaction was continued for 15 hours while maintaining the temperature at 160°C. After confirming that the softening point of the reaction product measured according to ASTM D36-86 reached 140°C, the temperature was reduced to stop the reaction (second reaction step). In this way, amorphous polyester A1 was obtained.

[0134] <Production of amorphous polyesters A2 to A4> Amorphous polyesters A2 to A4 were obtained in the same manner as in the production example of amorphous polyester A1, except that the types and amounts of amorphous polyester segments a1 and a2 were changed to those shown in Table 3. Table 4 shows the physical properties of the amorphous polyesters A1 to A4.

[0135] [Table 3]

[0136] [Table 4] In Table 4, the SP value difference is the difference (a2-a1) between the SP value of the amorphous polyester segment a2 and the SP value of the amorphous polyester segment a1. The unit of the SP value is (cal / cm 3 ) 0.5 is.

[0137] <Production of crystalline polyester segment c2-1> Linear aliphatic polyhydric alcohol b; ethylenediol 20 parts Aliphatic dicarboxylic acid; dodecanedioic acid 80 parts The above monomer components were placed in a reaction vessel equipped with a stirrer that had been thoroughly heated and dried, and 0.05 parts of titanium tetrabutoxide was added to 100 parts of the above mixture. Nitrogen gas was introduced into the vessel to maintain an inert atmosphere, and the temperature was raised to 260°C to polymerize the crystalline polyester segment c2-1.

[0138] <Production of Crystalline Polyester Segments c2-2 to c2-5> Crystalline polyester segments c2-2 to c2-5 were obtained in the same manner as in the production example of crystalline polyester segment c2-1, except that the types and amounts of linear aliphatic polyhydric alcohol b and aliphatic dicarboxylic acid were changed to those shown in Table 5.

[0139] [Table 5] The abbreviations in Table 5 are as follows: ED: Ethylenediol OD: Octanediol BD: butanediol DD: Dodecanediol DD2: Docosanediol DDA: Dodecanedioic acid DDA2: Docosanedioic acid

[0140] <Production example of crystalline polyester C1> Crystalline part c1; Behenic acid: 4 parts Crystalline polyester segment c2-1: 96 parts Esterification catalyst: titanium tetrabutoxide: 0.5 parts The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. After the atmosphere in the flask was replaced with nitrogen gas, the temperature was gradually raised with stirring, and the mixture was allowed to react at 200°C for 2 hours with stirring. The pressure inside the reaction vessel was then reduced to 8.3 kPa, and the reaction was carried out for 5 hours while maintaining the temperature at 200° C. After that, the temperature was lowered to stop the reaction, and a crystalline polyester C1 was obtained.

[0141] <Production Examples of Crystalline Polyesters C2 to C5> Crystalline polyesters C2 to C5 were obtained by carrying out the reaction in the same manner as in the production example of crystalline polyester C1, except that the types and parts of each crystalline portion c1 and crystalline polyester segment c2 were changed as shown in Table 6. The physical properties of crystalline polyesters C1 to C5 are shown in Table 7.

[0142] [Table 6] The abbreviations in Table 6 are as follows: BA: Behenic acid HA: hexanoic acid MA: melissic acid

[0143] [Table 7]

[0144] In Table 7, the SP value difference indicates the difference (c2-c1) between the SP value of the crystalline polyester segment c2 and the SP value of the crystalline portion c1. The unit of the SP value is (cal / cm 3 ) 0.5 is.

[0145] <Production Example of Toner Particle 1> Amorphous polyester A1: 90 parts Crystalline polyester C1: 10 parts Fischer-Tropsch wax (maximum endothermic peak temperature 76°C): 5 parts Carbon black: 10 parts The above materials were mixed using a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 1,500 rpm for 5 minutes, and then kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) set at a temperature of 150°C. The resulting kneaded mixture was cooled and coarsely pulverized to 1 mm or less using a hammer mill to obtain a coarsely pulverized product. The coarsely pulverized product was then finely pulverized using a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). Further, classification was performed using a Faculty (F-300, manufactured by Hosokawa Micron Corporation) to obtain toner particles 1. The operating conditions were a classifying rotor rotation speed of 11,000 rpm and a dispersing rotor rotation speed of 7,200 rpm.

[0146] <Production Examples of Toner Particles 2 to 9> Toner particles 2 to 9 were obtained in the same manner as in Production Example of Toner 1, except that in Production Example of Toner Particle 1, the type of amorphous polyester A and the type of crystalline polyester C were changed as shown in Table 8. The obtained physical properties are shown in Table 8. For the toner particles 8, the crystalline polyester C was not used.

[0147] [Table 8]

[0148] The difference in SP value between a1 and c2 indicates the difference (a1-c2) between the SP value of the amorphous polyester segment a1 and the SP value of the crystalline polyester segment c2. The difference in SP value between a2 and c1 indicates the difference (a2-c1) between the SP value of the amorphous polyester segment a2 and the SP value of the crystalline portion c1. The unit of SP value is (cal / cm 3 ) 0.5 is.

[0149] <Production example of strontium titanate microparticles 1> Metatitanic acid produced by the sulfuric acid method was deironized and bleached, then desulfurized by adding a 3 mol / L aqueous solution of sodium hydroxide to adjust the pH to 9.0, and then neutralized to pH 5.6 with 5 mol / L hydrochloric acid, filtered, and washed with water. Water was added to the washed cake to make a 1.90 mol / L slurry in terms of TiO2, and hydrochloric acid was added to adjust the pH to 1.4, which was then subjected to peptization. After desulfurization and peptization, 1.90 moles of metatitanic acid was collected in terms of TiO2 and placed in a 3 L reaction vessel. 2.185 moles of strontium chloride aqueous solution was added to the peptized metatitanic acid slurry so that the SrO / TiO2 (molar ratio) was 1.15, and the TiO2 concentration was then adjusted to 1.039 moles / L.

[0150] Next, an aqueous sodium silicate solution was prepared so that the amount of Si added was equivalent to 5.0 mol% relative to strontium, and the solution was heated to 90°C while stirring and mixing. 440 mL of a 10 mol / L aqueous sodium hydroxide solution was then added over 40 minutes under ultrasonic vibration. After that, stirring was continued at 95°C for 45 minutes, and then the mixture was poured into ice water to rapidly cool it down and terminate the reaction.

[0151] The reaction slurry was heated to 70°C, 12 mol / L hydrochloric acid was added until the pH reached 5.0, and stirring was continued for 1 hour. The resulting precipitate was washed by decantation, separated by filtration, and then dried in the air at 120°C for 8 hours to obtain strontium titanate microparticles 1. The physical properties of the obtained strontium titanate microparticles are shown in Table 9.

[0152] <Strontium titanate nanoparticles 2-16> In the production example of strontium titanate microparticles 1, the production conditions were appropriately changed to obtain strontium titanate microparticles 2 to 16 with the following different physical properties. The following physical properties are bulk density, BET specific surface area, average particle size of primary particles, convex portions formed by silica on the surface of strontium titanate microparticles, or average particle size of primary particles of silica microparticles. The physical properties of the obtained strontium titanate microparticles are shown in Table 9. It should be noted that no protrusions formed of silica or silica particles were present on the surface of the strontium titanate particles 16.

[0153] [Table 9]

[0154] <Toner 1 manufacturing example> 100 parts of toner particles Strontium titanate fine particles 1 0.9 parts Silica fine particles (median diameter (D50) based on number of particles is 15 nm) 0.8 parts The materials shown in the above recipe were mixed using a Henschel mixer (FM-10C, manufactured by Nippon Coke Co., Ltd.) at a rotation speed of 2000 rpm for 2 minutes, and then passed through an ultrasonic vibration sieve with 54 μm openings to obtain Toner 1.

[0155] <Toner 2-30 manufacturing example> Toners 2 to 30 were obtained by the same procedure as in the production example of Toner 1, except that the external addition conditions were changed so that the toner particles, type of strontium titanate microparticles, number of parts added, proportion of Ti element originating from strontium titanate microparticles on the toner surface, and proportion of Ti element originating from strontium titanate microparticles detached from the toner were as shown in Table 10.

[0156] The proportion of Ti elements originating from the strontium titanate microparticles on the toner surface and the proportion of Ti elements originating from the strontium titanate microparticles detached from the toner can be changed by changing the rotation speed and time of the Henschel mixer. By increasing the rotation speed or lengthening the time, the strontium titanate particles are strongly externally added to the toner surface. If the external additive strength is too strong, the external additive may become embedded in the toner, reducing the proportion of Ti element present on the toner surface. Also, by increasing the external additive strength, the proportion of Ti element originating from the strontium titanate microparticles that are released from the toner decreases.

[0157] [Table 10]

[0158] <Production example of magnetic core particle 1> Process 1 (weighing and mixing process): Fe2O362.7 parts MnCO329.5 parts Mg(OH)26.8 parts SrCO31.0 parts The ferrite raw materials were weighed so as to achieve the above composition ratio, and then pulverized and mixed for 5 hours in a dry vibration mill using stainless steel beads with a diameter of 1 / 8 inch.

[0159] Step 2 (pre-baking): The obtained pulverized material was made into pellets of approximately 1 mm square using a roller compactor. The pellets were passed through a vibrating sieve with 3 mm openings to remove coarse particles, and then through a vibrating sieve with 0.5 mm openings to remove fine particles. After that, the pellets were fired in a burner-type firing furnace at 1000°C for 4 hours in a nitrogen atmosphere (oxygen concentration 0.01% by volume) to produce calcined ferrite. The composition of the sintered body is as follows: (MnO) a (MgO) b (SrO) c (Fe2O3) d In the above formula, a=0.257, b=0.117, c=0.007, d=0.393

[0160] Step 3 (Crushing): The obtained calcined ferrite was crushed to about 0.3 mm using a crusher, and then 30 parts of water was added to 100 parts of the calcined ferrite and crushed in a wet ball mill using zirconia beads with a diameter of 1 / 8 inch for 1 hour. The obtained slurry was crushed in a wet ball mill using alumina beads with a diameter of 1 / 16 inch for 4 hours to obtain a ferrite slurry (finely crushed calcined ferrite).

[0161] ·Process 4 (granulation process): To the ferrite slurry, 1.0 part of ammonium polycarboxylate as a dispersant and 2.0 parts of polyvinyl alcohol as a binder were added per 100 parts of calcined ferrite, and the mixture was granulated into spherical particles using a spray dryer (manufacturer: Okawahara Kakoki Co., Ltd.). After adjusting the particle size of the resulting particles, they were heated in a rotary kiln at 650°C for 2 hours to remove the organic components of the dispersant and binder.

[0162] Step 5 (firing): To control the firing atmosphere, the material was heated from room temperature to 1300°C in a nitrogen atmosphere (oxygen concentration 1.00% by volume) in an electric furnace over two hours, and then fired at 1150°C for four hours. The material was then cooled to 60°C over four hours, returned from the nitrogen atmosphere to the air, and removed at a temperature of 40°C or below.

[0163] Step 6 (sorting): After crushing the agglomerated particles, low magnetic particles were removed by magnetic separation, and coarse particles were removed by sieving through a sieve with a mesh size of 250 μm to obtain magnetic core particles 1 with a volume distribution-based 50% particle size (D50) of 37.0 μm.

[0164] <Preparation of Coating Resin 1> Cyclohexyl methacrylate monomer 26.8% by mass Methyl methacrylate monomer 0.2% by mass Methyl methacrylate macromonomer 8.4% by mass (a macromonomer with a weight-average molecular weight of 5000 and a methacryloyl group at one end) Toluene 31.3% by mass Methyl ethyl ketone 31.3% by mass Azobisisobutyronitrile 2.0% by mass

[0165] Of the above materials, cyclohexyl methacrylate monomer, methyl methacrylate monomer, methyl methacrylate macromonomer, toluene, and methyl ethyl ketone were placed in a four-neck separable flask equipped with a reflux condenser, thermometer, nitrogen inlet tube, and stirrer, and nitrogen gas was introduced to create a sufficient nitrogen atmosphere. The mixture was then heated to 80°C, azobisisobutyronitrile was added, and the mixture was refluxed for 5 hours to polymerize. Hexane was then poured into the resulting reaction mixture to precipitate the copolymer. The precipitate was then filtered and vacuum dried to obtain Coating Resin 1. Next, 30 parts of coating resin 1 was dissolved in 40 parts of toluene and 30 parts of methyl ethyl ketone to obtain polymer solution 1 (solid content 30% by mass).

[0166] <Preparation of Coating Resin Solution 1> Polymer solution 1 (resin solids concentration 30%) 33.3% by mass Toluene 66.4% by mass Carbon black Regal 330 (manufactured by Cabot) 0.3% by mass (Primary particle size 25 nm, nitrogen adsorption specific surface area 94 m 2 / g, DBP oil absorption 75mL / 100g) The above materials were dispersed for 1 hour using zirconia beads with a diameter of 0.5 mm in a paint shaker. The resulting dispersion was filtered through a 5.0 μm membrane filter to obtain coating resin solution 1.

[0167] <Magnetic Carrier 1 Manufacturing Example> (Resin coating process): Magnetic core particles 1 and coating resin solution 1 were added to a vacuum degassing kneader maintained at room temperature (the amount of coating resin solution added was 2.5 parts as resin component per 100 parts of magnetic core particles 1). After addition, the mixture was stirred at a rotation speed of 30 rpm for 15 minutes, and after a certain amount of solvent (80 mass%) had evaporated, the mixture was heated to 80°C while mixing under reduced pressure, and the toluene was distilled off over 2 hours, after which it was cooled. The obtained magnetic carrier was separated into low magnetic particles by magnetic separation, passed through a sieve with 70 μm openings, and then classified with an air classifier to obtain magnetic carrier 1 having a 50% particle size (D50) based on volume distribution of 38.2 μm.

[0168] <Production examples of two-component developers 1 to 30> 92.0 parts of magnetic carrier 1 and 8.0 parts of toner were mixed in a V-type mixer (V-20, manufactured by Seishin Enterprises) to obtain two-component developers 1 to 30. The toners used in two-component developers 1 to 30 are toners 1 to 30, respectively.

[0169] Example 1 The following evaluations were carried out using a Canon full-color copier, imagePRESS C800, or a modified version thereof. The image forming apparatus has a photosensitive member as an image carrier on which an electrostatic latent image is formed, and has a developing step in which the electrostatic latent image on the photosensitive member is developed into a toner image with a two-component developer. The developed toner image is then transferred to an intermediate transfer member in a transfer step, and then the toner image on the intermediate transfer member is transferred to paper, followed by a fixing step in which the toner image on the paper is fixed by heat. Two-component developer 1 was placed in the developing device of the cyan station of this image forming apparatus, and the following evaluations were carried out.

[0170] <Evaluation of electrostatic charge> The toner on the electrostatic latent image bearing member was collected by suction using a metal cylindrical tube and a cylindrical filter, and the amount of triboelectric charge and amount of toner carried on the toner were calculated. Specifically, the triboelectric charge amount and toner amount on the electrostatic latent image carrier were measured using a Faraday cage. A Faraday cage is a coaxial double cylinder, with the inner and outer cylinders insulated. If a charged object with a charge Q is placed inside this inner cylinder, electrostatic induction will create the same effect as if a metal cylinder with a charge Q were present. This induced charge was measured with an electrometer (Kesley 6517A, manufactured by Kesley), and the charge Q (mC) divided by the toner mass M (kg) in the inner cylinder (Q / M) was determined as the toner's triboelectric charge.

[0171] In addition, by measuring the sucked area S, the toner mass M can be calculated by the sucked area S (cm 2 ) to obtain the amount of toner applied per unit area. The amount of toner applied was measured by stopping the rotation of the electrostatic latent image carrier before the toner layer formed on the electrostatic latent image carrier was transferred to the intermediate transfer body, and then directly sucking the toner image on the electrostatic latent image carrier with air. 2 )=M / S Toner triboelectric charge (mC / kg) = Q / M

[0172] In the above image forming apparatus, the amount of toner carried on the electrostatic latent image carrier in a high temperature and high humidity environment (30.0°C, 80% RH) is 0.35 mg / cm 2 The toner was collected by suction using the cylindrical metal tube and cylindrical filter. The amount of charge Q stored in the capacitor through the cylindrical metal tube and the mass M of the collected toner were measured, and the amount of charge Q / M (mC / kg) per unit mass was calculated, which was taken as the amount of charge Q / M (mC / kg) per unit mass on the electrostatic latent image carrier (initial evaluation).

[0173] After the above evaluation (initial evaluation), the developing unit was removed from the machine and left in a high temperature and high humidity environment (30.0°C, 80% RH) for 72 hours, and then the developing unit was reinserted into the machine and subjected to the same DC voltage V as in the initial evaluation. DC The charge amount Q / M per unit mass on the electrostatic latent image bearing member was measured (evaluation after leaving it standing).

[0174] The Q / M per unit mass on the electrostatic latent image carrier in the above initial evaluation was set to 100%, and the maintenance rate of the charge Q / M per unit mass on the electrostatic latent image carrier after being left for 72 hours (evaluation after being left for 72 hours) (evaluation after being left for 72 hours / initial evaluation x 100) was calculated and evaluated according to the following criteria. (Evaluation criteria) A: Retention rate is over 80% B: Retention rate is 70% or more but less than 80% C: Retention rate is 60% or more but less than 70% D: Retention rate is less than 60%

[0175] <Environmental Stability Evaluation> The change rate of image density in the HH and NL environments relative to the image density in the NN environment was used as the evaluation standard for environmental stability. The test environments were normal temperature and humidity (NN) environment (temperature 23°C, relative humidity 50% to 60%), normal temperature and low humidity (NL) environment (temperature 23°C, relative humidity 5%), and high temperature and humidity (HH) environment (temperature 30°C, relative humidity 80%). When the initial (first sheet) image density under the NN environment is DNNi, the image density under the HH environment is DHHi, and the image density under the NL environment is DNLi, the initial image density environmental change rate Vi was calculated using the following formula. Vi(%) = {(DHHi-DNLi) / DNNi} × 100

[0176] Similarly, after the durability test (10,000 sheets), the image density in the NN environment was DNNf, the image density in the HH environment was DHHf, and the image density in the NL environment was DNLf. The environmental change rate of image density after durability test Vf was calculated using the following formula. Vf(%)={(DHHf-DNLf) / DNNf}×100

[0177] These Vi and Vf values ​​were ranked according to the following evaluation criteria. A: Less than 35% B: 35% or more but less than 50% C: 50% or more but less than 60% D: 60% or more

[0178] <Durable image density evaluation> The image forming apparatus was modified in that the mechanism for discharging excess magnetic carrier from the developing unit was removed. The amount of toner on the paper in a FFh image (solid image) is 0.45 mg / cm 2 FFh is the 256 gradations expressed in hexadecimal, with 00h being the first gradation of the 256 gradations (white background) and FFh being the 256th gradation of the 256 gradations (solid area).

[0179] In this evaluation, a durability image output test was conducted on 10,000 sheets at an image ratio of 1% under three test environments: normal temperature and normal humidity (NN) (temperature 23°C, relative humidity 50% to 60%), normal temperature and low humidity (NL) (temperature 23°C, relative humidity 5%), and high temperature and humidity (HH) (temperature 30°C, relative humidity 80%).

[0180] During the continuous printing of 10,000 sheets, the sheets were printed under the same development and transfer conditions (without calibration) as the first sheet. The paper used for evaluation was plain copy paper GF-C081 (A4, basis weight 81.4 g / m 2 (sold by Canon Marketing Japan Inc.) was used.

[0181] The items and evaluation criteria for image output evaluation at the initial stage (first sheet) and after 10,000 sheets of paper were shown below. An X-Rite color reflection densitometer (500 series: manufactured by X-Rite) was used to measure the image density of the FFh image area (solid area) initially (first sheet) and after durability testing (10,000 sheets), and the absolute value of the difference between the two image densities was ranked according to the following criteria. A: Less than 0.05 B: 0.05 or more and less than 0.10 C: 0.10 or more and less than 0.15 D: 0.15 or more

[0182] <Low temperature fixability> As the image forming apparatus, a modified Canon imageRUNNER ADVANCE C5560 digital commercial printing printer was used, and a two-component developer was placed in the black developing unit. The modifications to the device include the fixing temperature, process speed, and DC voltage V DC , the charging voltage V of the electrostatic latent image carrier D The image output evaluation was carried out by outputting a FFh image (solid image) with the desired image ratio, and adjusting V so that the amount of toner on the FFh image on the paper was the desired amount. DC , V D The temperature and laser power were adjusted and the evaluation described below was carried out.

[0183] Paper: GFC-081 (81.0g / m 2 ) (Sold by Canon Marketing Japan Inc.) Toner amount on paper: 0.50 mg / cm 2 (The DC voltage of the developer carrier V DC , the charging voltage V of the electrostatic latent image carrier D , and adjusted by laser power) Evaluation image: A 2cm x 5cm image placed in the center of the A4 paper. Test environment: Low temperature and humidity environment: Temperature 15°C / Humidity 10% RH (hereinafter referred to as "L / L") Fixing temperature: 150℃ Process speed: 377 mm / sec

[0184] The above evaluation image was output, and the low-temperature fixability was evaluated. The value of the image density reduction rate was used as an evaluation index for the low-temperature fixability. The image density reduction rate was measured using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite Corporation), and the image density at the center was first measured. Next, the part where the image density was measured was subjected to pressure of 4.9 kPa (50 g / cm 2 The fixed image was rubbed (five times back and forth) with Silbon paper under a load of 1000 kJ / cm2, and the image density was measured again.

[0185] The rate of decrease in image density before and after rubbing was calculated using the following formula: The rate of decrease in image density obtained was evaluated according to the following evaluation criteria. Image density reduction rate = (image density before friction - image density after friction) / image density before friction x 100 (Evaluation criteria) A: Image density reduction rate less than 3% B: Image density reduction rate: 3% to less than 5% C: Image density reduction rate: 5% to less than 8% D: Image density reduction rate 8% or more

[0186] <Image heat resistance (heat and pressure resistance)> Paper:CS-680(68.0g / m 2 ) (Sold by Canon Marketing Japan Inc.) Toner loading: 1.20mg / cm 2 Evaluation image: 100cm in the center of the above A4 paper 2 Place an image (10cm x 10cm) Fixing test environment: Low temperature and low humidity environment, 15°C / 10%RH (hereinafter referred to as "L / L") Process speed: 450 mm / sec Fixing temperature: Low temperature fixability evaluation temperature + 10°C

[0187] Using the image forming apparatus described above, one fixed image was output under the above conditions, and a stack of paper (500 sheets of CS-680) was placed on top of it. The output and the stack of paper were then placed in a thermostatic chamber set to 65°C and 40% RH and left for 10 hours.

[0188] Next, the printed matter and the sheet of paper on it were removed from the thermostatic chamber and left to cool for one hour. The density of the image adhered to the paper was evaluated using an X-Rite color reflection densitometer (500 series, manufactured by X-Rite Corporation).

[0189] (Evaluation criteria: Image density adhered to paper) A: Less than 0.10 B: 0.10 or more and less than 0.30 C: 0.30 or more and less than 0.50 D: 0.50 or more

[0190] The same series of evaluations as above were also carried out on two-component developers 2 to 30. The evaluation results are shown in Table 11.

[0191] [Table 11]

[0192] From the above results, the SP value is 9.0 to 12.0 (cal / cm 3 ) 0.5 Crystalline polyester It has been shown that by externally adding strontium titanate microparticles having convex portions formed of silica or having silica microparticles fixed to the surface to a toner containing crystalline polyester C having steric segment c2, it is possible to provide a toner that maintains low-temperature fixing properties and image robustness, whose charging performance does not change even with long-term use, and which can output excellent image quality over a long period of time.

[0193] The present disclosure relates to the following configurations. (Configuration 1) A toner containing toner particles containing a binder resin and an external additive, the binder resin contains an amorphous polyester A and a crystalline polyester C, the external additive contains strontium titanate microparticles, The crystalline polyester C has an SP value of 9.0 to 12.0 (cal / cm 3 ) 0.5 Crystal a soluble polyester segment c2, Meet either (i) or (ii) below (i) The strontium titanate microparticles have convex portions formed of silica on their surfaces. (ii) Silica particles are fixed to the surface of the strontium titanate particles. A toner characterized by: (Configuration 2) 2. The toner according to claim 1, wherein the strontium titanate fine particles have a bulk density of 0.20 to 0.65 g / mL. (Configuration 3) The BET specific surface area of ​​the strontium titanate microparticles is 100~120m2 The toner according to Configuration 1 or 2, which is / g. (Configuration 4) The toner according to any one of Configurations 1 to 3, wherein the number average particle diameter D1 of the primary particles of the strontium titanate fine particles is 15 to 70 nm. (Configuration 5) The toner according to any one of Configurations 1 to 4, wherein the content of the strontium titanate fine particles with respect to 100 parts by mass of the toner particles is 0.4 to 1.4 parts by mass. (Configuration 6) The relationship between the abundance ratio x (atomic%) of Ti element derived from the strontium titanate fine particles on the toner surface measured by X-ray photoelectron spectroscopy (ESCA) and the abundance ratio y (atomic%) of Ti element derived from the strontium titanate desorbed from the toner when the external additive is desorbed from the toner under predetermined conditions using a shaker satisfies the following formula (1). The toner according to any one of Configurations 1 to 5. 0≦y<0.75x - 0.089 ···(1) (Configuration 7) The toner according to any one of Configurations 1 to 6, wherein the number average particle diameter DS1 of the primary particles of the convex portion formed of the silica or the silica fine particles is 0 nm < DS1 < 5 nm. (Configuration 8) The amorphous polyester A has an amorphous polyester segment a1 and an amorphous polyester segment a2, The difference (SP value of a2 - SP value of a1) between the SP value of the amorphous polyester segment a2 and the SP value of the amorphous polyester segment a1 is 0.80 (cal / cm 3 ) 0.5 The toner according to any one of Configurations 1 to 7, which is 0.80 (cal / cm (Configuration 9) The crystalline polyester C is a polymer having a crystalline site c1 bonded to the end of the crystalline polyester segment c2, The difference (SP value of c2 - SP value of c1) between the SP value of the crystalline polyester segment c2 and the SP value of the crystalline site c1 is 0.75 (cal / cm 3 )0.5 That's all, The difference between the SP value of the amorphous polyester segment a1 and the SP value of the crystalline polyester segment c2 (the SP value of a1 - the SP value of c2) is 0.80 (cal / cm 3 ) 0.5 is as follows: The difference between the SP value of the amorphous polyester segment a2 and the SP value of the crystalline portion c1 (the SP value of a2 - the SP value of c1) is 2.00 (cal / cm 3 ) 0.5 End 9. The toner according to claim 8, wherein

Claims

1. A toner containing toner particles containing a binder resin and an external additive, the binder resin contains an amorphous polyester A and a crystalline polyester C, the external additive contains strontium titanate microparticles, The crystalline polyester C has an SP value of 9.0 to 12.0 (cal / cm ３ ) ０．５ Crystal a hydroxylated polyester segment c2; Satisfy the following (i) or (ii): (i) The strontium titanate fine particles have convex portions formed of silica on their surfaces. (ii) Silica fine particles are fixed to the surface of the strontium titanate fine particles. A toner characterized by:

2. 2. The toner according to claim 1, wherein the strontium titanate fine particles have a bulk density of 0.20 to 0.65 g / mL.

3. The BET specific surface area of ​​the strontium titanate microparticles is 100 to 120 m ２ 3. The toner according to claim 1, wherein the toner has a molecular weight of 1 / g.

4. 3. The toner according to claim 1, wherein the number average particle diameter D1 of the primary particles of the strontium titanate fine particles is 15 to 70 nm.

5. 3. The toner according to claim 1, wherein the content of the strontium titanate fine particles is 0.4 to 1.4 parts by mass relative to 100 parts by mass of the toner particles.

6. 3. The toner according to claim 1, wherein the relationship between the abundance ratio x (atomic %) of Ti element derived from strontium titanate microparticles on the toner surface measured by X-ray photoelectron spectroscopy analysis (ESCA) and the abundance ratio y (atomic %) of Ti element derived from strontium titanate desorbed from the toner when the external additive is desorbed from the toner using a shaker under predetermined conditions satisfies the following formula (1): 0≦y<0.75x-0.089...(1)

7. 3. The toner according to claim 1, wherein the number average particle diameter DS1 of the convex portions formed of silica or the primary particles of the silica fine particles is in the range of 0 nm<DS1<5 nm.

8. the amorphous polyester A has an amorphous polyester segment a1 and an amorphous polyester segment a2, The difference between the SP value of the amorphous polyester segment a2 and the SP value of the amorphous polyester segment a1 (the SP value of a2 - the SP value of a1) is 0.80 (cal / cm ３ ) ０．５ The toner according to claim 1 or 2, wherein the toner is a toner having the above properties.

9. the crystalline polyester C is a polymer having a crystalline portion c1 bonded to an end of the crystalline polyester segment c2, The difference between the SP value of the crystalline polyester segment c2 and the SP value of the crystalline portion c1 (SP value of c2 - SP value of c1) is 0.75 (cal / cm ３ ) ０．５ That's all, The difference between the SP value of the amorphous polyester segment a1 and the SP value of the crystalline polyester segment c2 (the SP value of a1 - the SP value of c2) is 0.80 (cal / cm ３ ) ０．５ is as follows: The difference between the SP value of the amorphous polyester segment a2 and the SP value of the crystalline portion c1 (the SP value of a2 - the SP value of c1) is 2.00 (cal / cm ３ ) ０．５ End 9. The toner according to claim 8, wherein

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