JP4716014B2 - Negatively chargeable toner and image forming apparatus - Google Patents

Description

  The present invention relates to a negatively chargeable toner used for electrophotography, electrostatic recording, electrostatic printing, and the like, and an image forming apparatus.

  In electrophotography, an electrostatic latent image formed on a latent image carrier provided with a photoconductive substance is developed using a toner containing a colorant, and then transferred to an intermediate transfer medium, and further, paper or the like. The toner image is transferred to the recording material and fixed by heat, pressure or the like to form a copy or printed matter. In order to improve the quality of printed images in such printed matter, or to reduce the cost, size, power consumption, and resource of equipment, the need for toner includes (1) printed images by reducing the toner particle size. Improvement of resolution and gradation, reduction of toner layer, reduction of waste toner amount, reduction of toner consumption per page, (2) reduction of power consumption by lowering fixing temperature, (3 There are simplification of a fixing device by oilless fixing, (4) improvement of hue, transparency and gloss in a full color image, and (5) reduction of harmful VOC (volatile organic compound) at the time of toner fixing.

  Even in powder toners by the pulverization method that has been used for a long time, it is basically possible to reduce the particle size, but as the particle size decreases, the release of the colorant, wax, etc. exposed on the toner particle surface As the ratio of the agent increases, charging control becomes difficult, the toner particles are irregularly shaped, the powder fluidity deteriorates, and the energy cost required for production rises. It is practically difficult to sufficiently satisfy the above needs.

  Against this background, development of toners (hereinafter referred to as chemical toners) by polymerization methods and emulsion dispersion methods has been actively conducted. Various methods are known for the toner by the polymerization method. Among them, a monomer, a polymerization initiator, a colorant, a charge control agent, and the like are added to an aqueous medium with stirring in an aqueous medium in the presence of a dispersion stabilizer. A suspension polymerization method is widely known in which toner particles are obtained by raising the temperature and then performing a polymerization reaction. Alternatively, an association method has been proposed in which toner particles are obtained by forming fine particles by emulsion polymerization or suspension polymerization, aggregating the fine particles, and further fusing the aggregated fine particles. However, the polymerization method or the association method using fine particles produced by the polymerization method has no problem in reducing the particle size of the toner particles, but the main component of the binder resin is limited to a vinyl polymer capable of radical polymerization. Therefore, it is not possible to produce a toner made of polyester resin or epoxy resin suitable for color toners. In addition, the polymerization method has a problem that it is difficult to reduce VOC (volatile organic compounds composed of unreacted monomers), and improvement thereof is desired.

  On the other hand, a method for producing a toner by an emulsion dispersion method is a method in which a mixture of a binder resin and a colorant is mixed with an aqueous medium and emulsified to obtain toner particles. In addition to easily adapting to spheroidization and spheroidization, the choice of binder resin is wider than the polymerization method, residual monomer can be easily reduced, and the concentration of colorants, etc., can be set from low to high It has the advantage that it can be changed to. As the binder resin for toner, which has a relatively low fixing temperature and tends to melt sharply at the time of fixing and the image surface becomes smooth, a polyester resin is preferable to a styrene-acrylic resin. A polyester resin excellent in flexibility is preferred. However, as described above, the polymerization method cannot produce toner particles having a polyester resin as a main component of the binder resin. Therefore, in recent years, attention has been focused on producing a small particle size toner using a polyester resin as a binder resin by an emulsification dispersion method.

  The method for producing a small particle toner using a polyester resin as a binder resin is as follows: (1) After emulsifying and dispersing using a polyester resin as a binder resin, the resulting fine particles are agglomerated and further heated and fused. A production method by “association” in which two steps of an aggregation step and a fusion step are sequentially performed to form toner aggregates to form toner particles, and (2) after producing fine particles by emulsion dispersion, There is a production method by “unification” in which the step of aggregating the fine particles and the step of fusing the agglomerated fine particles together are performed, that is, the aggregation and fusion of the fine particles produced by emulsion dispersion are performed in one step. It is known that the production method according to “Unification” makes it possible to obtain spherical toner particles easily and in a short time. In particular, in Patent Document 1 and the like, a mixture containing a polyester resin or the like is emulsified to form a dispersion, and then a dispersion stabilizer / electrolyte can be added to stably perform the “unification” treatment, resulting in an emulsion loss. No chemical toner with a sharp particle size distribution is obtained, and it is described that it can be obtained easily, in a short time, and in a high yield.

  However, when the toner base particles are used, the polyester resin fine particles treated with “union” are separated from the aqueous medium, washed, and dried, but in the production, the resin particles are dispersed stabilizers, electrolytes, etc. The surface of the toner base particles is likely to adsorb moisture, and after durable printing such as printing on multiple sheets. There is a problem that only the toner having a problem in durability is obtained because the charge amount is lowered.

  In addition, when the chargeability of the toner is reduced, the toner falls off from the developing roller, causing a problem in that the toner conveyance amount is non-uniform and the printed image is uneven. Therefore, from the viewpoint of improving the chargeability of the negatively chargeable toner, the toner base particles are externally added with a fluidity imparting agent such as silica fine particles and a chargeability imparting agent such as alumina to stabilize the chargeability (Patent Documents). 2) In addition, it is known that inorganic fine particles are externally added together with resin fine particles from the viewpoint of assisting charging (Patent Document 3), but this is insufficient to solve the problem due to unstable charging.

On the other hand, in the external addition process, a mixture processing tank having a spherical shape with an improved rolling state is known (Patent Documents 4 and 5). However, when toner base particles having a high sphericity are employed, However, although it has excellent rolling properties, its surface area is relatively small compared to that of an irregular shaped toner, and the amount of external additives that are liberated due to the reduction in surface irregularities is large. It also contributes to stabilization.
JP2003-122051 JP2003-280253 JP-A-2005-70187 Japanese Patent Laid-Open No. 8-173783 JP 2002-268277 A

  The present invention comprises toner base particles obtained by aggregating and coalescing polyester resin particles by adding a dispersion stabilizer and an electrolyte to a phase inversion emulsion comprising anionic self-water-dispersed polyester resin particles and an aqueous medium. An object of the present invention is to provide a negatively chargeable toner which is excellent in charging stability when printing a large number of sheets and has excellent durability without causing unevenness in a printed image, and a method for producing the same.

The negatively chargeable toner of the present invention is obtained by adding a dispersion stabilizer and an electrolyte to a phase inversion emulsion composed of an anionic self-water-dispersed polyester resin particle containing a colorant and a wax component, and an aqueous medium. Toner base particles obtained by agglomerating and coalescing,
Hydrophobic silica fine particles having a number average primary particle diameter of 7 to 60 nm externally added to the toner base particles ;
Hydrophobic titanium oxide fine particles having a number average primary particle diameter of 10 to 40 nm externally added to the toner base particles ,
Hydrophobic silica fine particles having a number average primary particle diameter of 100 to 600 nm externally added to the toner base particles ;
It is characterized by having.

Further, the toner base particles include positively chargeable silica fine particles externally treated to the toner base particles , and metal soap particles externally treated to the toner base particles .

In the image forming apparatus of the present invention, a dispersion stabilizer and an electrolyte are added to a phase inversion emulsion comprising an anionic self-water-dispersed polyester resin particle containing a colorant and a wax component and an aqueous medium, and the polyester resin particle is added. Toner base particles obtained by agglomeration and coalescence
Hydrophobic silica fine particles having a number average primary particle size of 7 to 60 nm,
Hydrophobic titanium oxide fine particles having a number average primary particle size of 10 to 40 nm,
A negatively chargeable toner externally treated with hydrophobic silica fine particles having a number average primary particle size of 100 to 600 nm is used.

  The toner base particles in the present invention are obtained by adding a dispersion stabilizer and an electrolyte to a phase inversion emulsion composed of anionic self-water-dispersed polyester resin particles and an aqueous medium, and aggregating and coalescing the polyester resin particles. The toner base particles have no emulsification loss and a sharp particle size distribution. However, the silica particles or α-type alumina particles having a large particle size exceeding at least 100 nm are used as external additive particles by a method having excellent adhesion. By performing the addition process, it is possible to prevent a decrease in chargeability after printing a large number of sheets, and it is possible to obtain a negatively chargeable toner that does not cause unevenness in a printed image. Although the detailed reason is unknown, as is clear from comparison with Comparative Examples described later, even toner base particles produced using hydrophilic components such as a dispersion stabilizer and an electrolyte are large particles. It has been found that the chargeability can be prevented from being lowered by externally adding silica particles having a diameter or α-type alumina particles.

  The method for producing a negatively chargeable toner according to the present invention is such that, when externally added fine particles having a large particle size are added to the toner base particles using a spherical mixing treatment tank, the work function of the toner base particles is set to be large. By making the work function larger (at least 0.02 eV) than that of silica fine particles having a large diameter or α-type alumina fine particles having a large particle diameter, it is possible to perform an external addition process with excellent adhesion, and further externally treating metal soap particles. As a result, the toner base particles and the external additive particles having a large particle diameter can be further adhered by the adhesive function, and thus a negatively chargeable toner having excellent durability can be produced.

  The toner base particles in the present invention are (1) a first step of emulsifying a mixture containing at least a polyester resin and an organic solvent in an aqueous medium in the presence of a basic compound to form fine particles, and then (2) dispersion. A second step of adding a stabilizer and further adding an electrolyte in order to coalesce the fine particles to produce fine particle aggregates, (3) removing the organic solvent contained in the aggregates, It is manufactured through a third step of separating, washing, and drying fine particle aggregates from the medium.

  The polyester resin is synthesized by dehydration condensation of a polybasic acid and a polyhydric alcohol. Examples of polybasic acids include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, alkenyl succinic anhydride And aliphatic carboxylic acids such as adipic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. These polybasic acids can be used alone or in combination of two or more. Of these polybasic acids, aromatic carboxylic acids are preferably used.

  Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, and pentaerythritol; cyclohexanediol and cyclohexanedimethanol. And alicyclic diols such as hydrogenated bisphenol A; aromatic diols such as ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A. These polyhydric alcohols can be used alone or in combination of two or more. Among these polyhydric alcohols, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.

  In addition, monocarboxylic acid and / or monoalcohol is further added to the polyester resin obtained by polycondensation of polycarboxylic acid and polyhydric alcohol to esterify the hydroxyl group and / or carboxyl group at the polymerization terminal. The acid value of the polyester resin can be adjusted. Examples of the monocarboxylic acid used for such a purpose include acetic acid, acetic anhydride, benzoic acid, trichloroacetic acid, trifluoroacetic acid, and propionic anhydride. Examples of the monoalcohol include methanol, ethanol, propanol, octanol, 2-ethylhexanol, trifluoroethanol, trichloroethanol, hexafluoroisopropanol, and phenol.

  The polyester resin can be produced by subjecting the polyhydric alcohol and the polyvalent carboxylic acid to a condensation reaction according to a conventional method. For example, the above polyhydric alcohol and polyvalent carboxylic acid are mixed in a reaction vessel equipped with a thermometer, a stirrer, and a flow-down condenser, and heated at 150 to 250 ° C. in the presence of an inert gas such as nitrogen, The low molecular compound produced as a by-product is continuously removed from the reaction system, and when a predetermined physical property value is reached, the reaction is stopped and cooled to obtain the desired reactant.

  Such a polyester resin can be synthesized by adding a catalyst. Examples of the esterification catalyst used include organic metals such as dibutyltin dilaurate and dibutyltin oxide, and metal alkoxides such as tetrabutyl titanate. Further, when the carboxylic acid component to be used is a lower alkyl ester, a transesterification catalyst can be used. Examples of the transesterification catalyst include metal acetates such as zinc acetate, lead acetate, and magnesium acetate; metal oxides such as zinc oxide and antimony oxide; metal alkoxides such as tetrabutyl titanate. About the addition amount of a catalyst, it is preferable to set it as the range of 0.01-1 mass% with respect to the total amount of a raw material.

  In such a polycondensation reaction, in order to produce a branched or cross-linked polyester resin, in particular, a polybasic acid having three or more carboxyl groups in one molecule or an anhydride thereof, and / or one molecule What is necessary is just to use the polyhydric alcohol which has a 3 or more hydroxyl group in as an essential synthetic | combination raw material.

  In order to have a good fixing / offset temperature range without using an anti-offset liquid as a toner used in the heat roll fixing method, the polyester resin is obtained by a constant load extrusion type capillary rheometer (hereinafter referred to as a flow tester). It is preferable to be in the following range in the measurement. That is, the outflow start temperature (Tfb) by the flow tester is in the range of 80 ° C to 120 ° C, the T1 / 2 temperature is in the range of 100 ° C to 160 ° C, and the outflow end temperature (Tend) is in the range of 110 ° C to 210 ° C. By using a polyester resin having such a flow tester value, a good oil-less fixing property is obtained. Moreover, it is preferable that a glass transition temperature (Tg) is 40-75 degreeC.

The outflow start temperature Tfb, T1 / 2 temperature, and outflow end temperature Tend by the flow tester are obtained using a flow tester (CFT-500) manufactured by Shimadzu Corporation. This flow tester includes a cylinder 2 having a nozzle 1 having a nozzle diameter D of 1.0 mmΦ and a nozzle length (depth) L of 1.0 mm as shown in FIG. Load when resin 3 (weight 1.5 g) is filled, a load of 10 kg per unit area (cm ² ) is applied from the side opposite to nozzle 1 and heated at a temperature rising rate of 6 ° C. per minute in that state. It is obtained by measuring the stroke S of the surface 4 (sink value of the load surface 4). That is, the relationship between the raised temperature and the stroke S is obtained as shown in FIG. 1B of Japanese Patent Laid-Open No. 2003-122051, and the outflow of the resin 3 from the nozzle 1 starts and the stroke S suddenly increases. The temperature when the curve rises is Tfb, and the temperature when the flow of the resin 3 from the nozzle 1 almost ends and the curve is bent is Tend. The temperature at S1 / 2, which is an intermediate value between the stroke Sfb at Tfb and the stroke Send at Tend, is defined as T1 / 2 temperature. Measurement by the temperature rising method using this device is performed by testing while raising the temperature at a constant rate as the test time elapses, so that the sample reaches from the solid region to the transition region, the rubbery elastic region, and the fluidized region. The process can be measured continuously. With this apparatus, the shear rate and viscosity at each temperature in the flow region can be easily measured.

  The outflow start temperature Tfb is an index of the sharp melt property and low temperature fixability of the polyester resin. If the temperature is too high, the low temperature fixability is deteriorated and cold offset is likely to occur. On the other hand, when the temperature is too low, the storage stability is lowered, and hot offset tends to occur. Accordingly, the outflow start temperature Tfb of the toner is more preferably 90 ° C. to 115 ° C., and particularly preferably 90 ° C. to 110 ° C.

  Also, the toner melting temperature T1 / 2 and the outflow end temperature Tend by the 1/2 method are indicators of hot offset resistance, and if both are too high, the solution viscosity increases, so the particle size at the time of particle formation Distribution deteriorates. Moreover, when all are too low temperature, it will become easy to generate | occur | produce offset and practicality will fall. Therefore, the melting temperature T1 / 2 by the 1/2 method needs to be 120 ° C to 160 ° C, more preferably 130 to 160 ° C, and the outflow end temperature Tend is preferably 130 ° C to 210 ° C, 130 to 180 degreeC is more preferable. By setting Tfb, T1 / 2, and Tend within the above ranges, fixing can be performed in a wide temperature range.

  The polyester resin described above contains a crosslinked polyester resin, and the tetrahydrofuran-insoluble content of the binder resin is in the range of 0.1 to 20% by mass, more preferably in the range of 0.2 to 10% by mass. Preferably it is the range of 0.2-6 mass%. As described above, it is preferable that the binder resin is a polyester resin having a tetrahydrofuran insoluble content of 0.1 to 20% by mass because good hot offset resistance can be secured. If it is less than 0.1% by mass, the effect of improving hot offset resistance is insufficient, which is not preferable. If it exceeds 20% by mass, the solution viscosity becomes too high, the fixing start temperature becomes high, and the fixing property is unbalanced. Moreover, since sharp melt property is impaired, transparency, color reproducibility, and gloss in color images are inferior, which is not preferable.

  The tetrahydrofuran-insoluble content of the binder resin was precisely weighed 1 g of the resin, completely dissolved in 40 ml of tetrahydrofuran, and radiolite (Showa Chemical) on a funnel (diameter 40 mm) on which Kiriyama filter paper (No. 3) was placed. Company # 700) 2 g is uniformly spread and filtered, the cake is placed on an aluminum petri dish, then dried at 140 ° C. for 1 hour, and the dry weight is measured. Then, a value obtained by dividing the residual resin amount in the dry weight by the initial resin sample amount is calculated as a percentage, and this value is defined as the tetrahydrofuran insoluble content of the binder resin.

  The binder resin preferably contains a highly viscous crosslinked polyester resin and a low viscosity branched or linear polyester resin. That is, in the polyester resin of the present invention, the binder resin may be composed of one type of polyester resin, but generally a cross-linked polyester resin (cross-linked polyester resin) having a high molecular weight and high viscosity, It is practical and preferable to use a branched or linear polyester resin having a low molecular weight for the production of the resin and to obtain a good fixing start temperature and hot offset resistance. . When blended and used, the flow tester value of the blended resin may be in the above numerical range. In the present invention, the crosslinked polyester resin indicates a resin having a component insoluble in tetrahydrofuran, and the branched or linear polyester resin indicates a resin that has no gel content and dissolves in tetrahydrofuran as measured by the gel content.

  In the present invention, a plurality of polyester resins having different melt viscosities can be used as the binder resin. For example, when a mixture of a low-viscosity branched or linear polyester resin and a high-viscosity cross-linked polyester resin is used, It is more preferable to use a mixture of a branched or linear polyester resin (A) and a crosslinked or branched polyester resin (B) under the conditions shown below. At this time, the melt viscosity and blending amount of the resin (A) and the resin (B) are appropriately adjusted so that the flow tester value of the blended resin falls within the above numerical range.

  That is, the polyester resin (A) is a branched or linear polyester resin having a T1 / 2 temperature of 80 ° C. or higher and lower than 120 ° C. and a glass transition temperature Tg of 40 ° C. to 70 ° C. As B), a T1 / 2 temperature measured by a flow tester is 120 ° C. or more and 210 ° C. or less, a crosslinked or branched polyester resin having a glass transition temperature Tg of 50 to 75 ° C., and these polyester resins (A) and The weight ratio with the polyester resin (B) is (A) / (B) = 20/80 to 80/20, and the T1 / 2 temperatures are T1 / 2 (A) and T1 / 2 (B), respectively. , Those having a relationship of 20 ° C. <T1 / 2 (B) −T1 / 2 (A) <100 ° C. are preferably used.

  Considering each temperature characteristic by the flow tester, the melting temperature T1 / 2 (A) of the resin (A) by the 1/2 method is an index for imparting sharp melt property and low temperature fixability. (A) is more preferably in the range of 80 to 115 ° C, particularly preferably in the range of 90 to 110 ° C.

  The resin (A) defined by these performances has a low softening temperature, and even in the fixing process using a heat roll, it melts sufficiently even if the heat energy provided by the lowering of the heat roll or the increase in the process speed is reduced. Excellent performance in cold offset resistance and low-temperature fixability.

  If both the melting temperature T1 / 2 (B) of the resin (B) by the 1/2 method and the end-of-flow temperature Tend (B) are too low, hot offset is likely to occur. T1 / 2 (B) is more preferably 125 ° C. to 210 ° C., and particularly preferably 130 ° C. to 200 ° C., because the particle size distribution at the time of formation deteriorates and the productivity is lowered.

  The resin (B) defined by these performances has a strong rubber elasticity and a high melt viscosity, so that the internal cohesive force of the melted toner layer is maintained even during heat melting in the fixing process, and hot offset occurs. It is difficult to resist and exhibits excellent friction resistance due to its toughness even after fixing.

  By blending the resin (A) and the resin (B) in a well-balanced manner, a toner that sufficiently satisfies offset resistance and low-temperature fixing performance in a wide temperature range can be provided. If the weight ratio (A) / (B) of the resin (A) to the resin (B) is too small, the fixing property is affected. If it is too large, the offset resistance is affected. It is preferably ˜80 / 20, more preferably 30/70 to 70/30.

  Moreover, when the melting temperatures of the resin (A) and the resin (B) by the 1/2 method are T1 / 2 (A) and T1 / 2 (B), respectively, both low-temperature fixability and offset resistance can be achieved. From the point of view and in order to facilitate uniform mixing without causing problems due to the difference in viscosity between the resins, the range of T1 / 2 (B) -T1 / 2 (A) exceeds 20 ° C. and 90 ° C. It is more preferable that the temperature is below 20 and 80 ° C. is particularly preferable.

  The glass transition temperature (Tg) is a value obtained by using a differential scanning calorimeter (DSC-50) manufactured by Shimadzu Corporation at a rate of temperature increase of 10 ° C. per second by the second run method. When the Tg of the polyester resin (A) is less than 40 ° C. or the Tg of the polyester resin (B) is less than 50 ° C., the resulting toner is blocked during storage or in a developing machine (toner particles are aggregated into a lump. This phenomenon is not preferable. On the other hand, if the Tg of the polyester resin (A) exceeds 70 ° C., or if the Tg of the polyester resin (B) exceeds 75 ° C., the toner fixing temperature increases, which is not preferable. As described above, it is preferable to use the polyester resin (A) and the polyester resin (B) having the above relationship as the polyester resin as the binder resin, so that the obtained toner has better fixability.

  Furthermore, as a binder resin composed of a polyester resin, a molecular weight measurement by a gel permeation chromatography (GPC) method of a soluble content of tetrahydrofuran (THF) has a weight average molecular weight of 30,000 or more, preferably 37,000 or more, Weight-average molecular weight (Mw) / number-average molecular weight (Mn) is 12 or more, preferably 15 or more, and the area ratio of components having a molecular weight of 600,000 or more is 0.3% or more, preferably 0.5% or more, and molecular weight 1 In order to obtain good fixability, it is preferable that the area ratio of components of 10,000 or less is 20 to 80%, preferably 30 to 70%. When blending a plurality of resins, the GPC measurement result of the final resin mixture may be within the above numerical range.

  In the polyester resin of the present invention, a high molecular weight component having a molecular weight of 600,000 or more has a function of ensuring hot offset resistance. On the other hand, a low molecular weight component having a molecular weight of 10,000 or less is effective for lowering the melt viscosity of the resin, manifesting a sharp melt property and lowering the fixing start temperature, and may contain a resin component having a molecular weight of 10,000 or less. preferable. In order to obtain good thermal characteristics such as low-temperature fixing, hot offset resistance, and transparency in the oilless fixing method, it is preferable that the binder resin has such a broad molecular weight distribution.

  The molecular weight of the THF-soluble component of the binder resin was determined by filtering the THF-soluble matter with a 0.2 μm filter, and then using three Tosoh GPC / HLC-8120 and Tosoh columns “TSKgelSuperHM-M” (15 cm). The molecular weight was calculated by using a molecular weight calibration curve measured with a THF solvent (flow rate 0.6 ml / min, temperature 40 ° C.) and prepared with a monodisperse polystyrene standard sample.

  The acid value of the polyester resin (mg number of KOH necessary to neutralize 1 g of resin) is obtained because it is easy to obtain the molecular weight distribution as described above, and it is easy to ensure the granulation properties of the fine particles by emulsification dispersion. The range of 1 to 20 mgKOH / g is preferable because the environmental stability of the toner (the stability of the chargeability when the temperature and humidity change) is easily maintained. As mentioned above, the acid value of the polyester resin is not limited to the addition of monocarboxylic acid and / or monoalcohol to the polyester resin obtained by condensation polymerization of polyvalent carboxylic acid and polyhydric alcohol. It can adjust by controlling the carboxyl group of the terminal of polyester with the compounding ratio and reaction rate of a polybasic acid of this, and a polyhydric alcohol. Or what has a carboxyl group in the principal chain of polyester can be formed by using trimellitic anhydride as a polybasic acid component.

  Next, the toner base particles can contain a release agent. Mold release agent selected from the group of hydrocarbon waxes such as polypropylene wax, polyethylene wax and Fiescher-Tropsch wax, natural ester waxes such as synthetic ester wax, carnauba wax and rice wax An agent is used. Of these, natural ester waxes such as carnauba wax and rice wax, and synthetic ester waxes obtained from polyhydric alcohols and long-chain monocarboxylic acids are preferably used. As the synthetic ester wax, for example, WEP-5 (manufactured by NOF Corporation) is preferably used. If the content of the release agent is less than 1% by mass, the releasability is likely to be insufficient, and if it exceeds 40% by mass, the wax is likely to be exposed on the toner particle surface, and the chargeability and storage stability are reduced. Since it becomes easy, the inside of the range of 1-40 mass% is preferable.

  Moreover, a charge control agent can be contained. Negatively chargeable charge control agents include trimethylethane dyes, salicylic acid metal complexes, benzylic acid metal complexes, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, and other heavy metal-containing acid dyes And, for example, a calixarene-type phenol condensate, a cyclic polysaccharide, a resin containing a carboxyl group and / or a sulfonyl group. The content of the charge control agent is preferably 0.01 to 10% by mass. It is especially preferable that it is 0.1-6 mass%.

  Moreover, there is no restriction | limiting in particular as a coloring agent, Although a well-known and usual thing is used, Especially a pigment is used suitably. Examples of the black pigment include carbon black, cyanine black, aniline black, ferrite, and magnetite. Moreover, what mix | blended the following chromatic pigment so that it might become black can also be used.

  Examples of yellow pigments include yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, ocher, titanium yellow, naphthol yellow S, Hansa Yellow 10G, Hansa Yellow 5G, Hansa Yellow G, Hansa Yellow GR, Hansa Yellow A, Hansa Yellow RN, Hansa Yellow R, Pigment Yellow L, Benzidine Yellow, Benzidine Yellow G, Benzidine Yellow GR, Permanent Yellow NCG, Vulcan First Yellow 5G, Vulcan First Yellow R, Quinoline Yellow Lake, Anslagen Yellow 6GL, Permanent Yellow FGL, Permanent Yellow H10G, Permanent Yellow HR, Anthrapyrimidine Yellow, Other Isoindolinone Yellow, Chromophthal Yellow, Novo Palm Yellow H2G Condensed azo yellow, nickel azo yellow, copper azomethine yellow, etc..

  Examples of red pigments include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, Indanthrene Brilliant Orange RK, Indanthrene Brilliant Orange GK, Benzidine Orange G, Permanent Red 4R, Permanent Red BL, Permanent Red F5RK. , Risor Red, Pyrazolone Red, Watching Red, Lake Red C, Lake Red D, Brilliant Carmine 6B, Brilliant Carmine 3B, Rhodamine Lake B, Alizarin Lake, Permanent Carmine FBB, Verinon Orange, Isoindolinone Orange, Anthanthrone Orange, Pilanthrone Orange, Quinacridone Red, Quinacridone Magenta, Quinacridone Scarlet, Perylene Tsu de, and the like.

  Examples of blue pigments include cobalt blue, cerulean blue, alkali blue rake, peacock blue rake, fanatone blue 6G, Victoria blue rake, metal-free phthalocyanine blue, copper phthalocyanine blue, first sky blue, indanthrene blue RS, and indanthrene blue. BC, Indico, etc. are mentioned.

  The amount of these colorants used is preferably in the range of 1 to 50 parts by weight, particularly preferably in the range of 2 to 15 parts by weight, per 100 parts by weight of the binder resin.

Next, a method for producing toner mother particles will be described.
In the first step, a polyester resin is put into an organic solvent, and the mixture containing the polyester resin and the organic solvent is prepared by dissolving and dispersing the resin (heating as necessary). In this case, one or more selected from various colorants, release agents or charge control agents, or other additives can be used together with the polyester resin as the toner raw material. In the present invention, it is preferable to disperse the colorant in the organic solvent together with the polyester resin, and it is particularly preferable to dissolve or disperse various additives such as a release agent and a charge control agent.

  As a means for dissolving or dispersing a polyester resin and various additives such as a colorant, a release agent, and a charge control agent in an organic solvent, the following method is preferably used. A polyester resin, a colorant, a release agent, a mixture containing various additives such as a charge control agent, etc. using a pressure kneader, a heated two-roll, two-screw extrusion kneader, etc. In addition, the mixture is heated and kneaded at a temperature lower than the thermal decomposition temperature. At this time, the colorant and the like may be melt-kneaded as a master batch. Thereafter, the kneaded chips obtained are prepared by dissolving or dispersing in an organic solvent with a stirrer such as a desper. Or various additives, such as a polyester resin and a coloring agent, a mold release agent, a charge control agent, are mixed with an organic solvent, and this is wet-kneaded with a ball mill etc. In this case, the colorant, the release agent and the like may be mixed after preliminary dispersion separately in advance.

  As a more specific means, a resin solution in which a polyester resin is previously dissolved in an organic solvent, a colorant and a mold release agent are used in a mixing / dispersing machine using a medium such as a ball mill, a bead mill, a sand mill, or a continuous bead mill. Add a colorant, stir and disperse it into a masterbatch, and further mix a polyester resin for dilution and an additional organic solvent to produce a resin solution in which colorants, release agents, etc. are finely dispersed in the organic solvent. There is a way. At this time, rather than putting the colorant or the release agent untreated directly into a mixing / dispersing machine such as a ball mill, a low-viscosity polyester resin and a colorant, or a release agent, etc. in a pressure kneader, It is preferable to use a master batch obtained by kneading and dispersing with two heated rolls. According to the above production method, since the polymer component (gel component) of the polyester resin is not cut, it is preferable to the method of dispersing by melt kneading.

  Examples of the organic solvent for dissolving or dispersing the polyester resin and a colorant or a release agent added as necessary include hydrocarbons such as pentane, hexane, heptane, benzene, toluene, xylene, cyclohexane, and petroleum ether. Halogenated hydrocarbons such as methylene chloride, chloroform, dichloroethane, dichloroethylene, trichloroethane, trichloroethylene, carbon tetrachloride; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone; esters such as ethyl acetate, butyl acetate, etc. Used. These solvents can be used in combination of two or more, but from the viewpoint of solvent recovery, it is preferable to use the same type of solvent alone. The organic solvent is a solvent that dissolves the binder resin, has a relatively low toxicity, and preferably has a low boiling point that can be easily removed in a subsequent step. As such a solvent, methyl ethyl ketone is most preferable.

  Next, as a method of emulsifying a mixture containing a polyester resin and an organic solvent in an aqueous medium, a mixture prepared by the above method comprising a polyester resin, a coloring agent added as necessary, and an organic solvent, It is preferable to mix and emulsify with an aqueous medium in the presence of a basic neutralizing agent. In this step, a method of gradually adding an aqueous medium (water or a liquid medium containing water as a main component) to a mixture composed of a polyester resin, a colorant, and the like and an organic solvent is preferable. In that case, by gradually adding water to the organic continuous phase of the mixture, a water-in-oil discontinuous phase is generated, and by adding additional water, the oil-in-water discontinuous phase is added. To form a suspension / emulsion in which the mixture is suspended as particles (droplets) in an aqueous medium (hereinafter, this method is referred to as phase inversion emulsification). In phase inversion emulsification, water is added so that the ratio of water to the total amount of the organic solvent and added water is 30 to 70%. More preferably, it is 35 to 65%, and particularly preferably 40 to 60%. The aqueous medium used is preferably water, more preferably deionized water.

  The polyester resin is preferably an acidic group-containing polyester resin, and is preferably a polyester resin that becomes self-dispersible by neutralizing the acidic group. The acid value of the self-water-dispersible polyester resin is preferably 1 to 20 mgKOH / g. The resin having self-water dispersibility becomes an anionic type by neutralizing an acidic group with a basic neutralizing agent. As a result, the hydrophilicity of the resin increases, and the resin can be stably dispersed in the aqueous medium without using a dispersion stabilizer or a surfactant (anionic self-water-dispersible polyester resin). Examples of the acidic group include an acidic group such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Among these, a carboxyl group is preferable from the viewpoint of charging characteristics of the toner. The basic substance for neutralization is not particularly limited, and for example, inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonia, and organic bases such as diethylamine, triethylamine, and isopropylamine are used. Of these, inorganic bases such as ammonia, sodium hydroxide and potassium hydroxide are preferred. In order to disperse the polyester resin in the aqueous medium, there is a method of adding a dispersion stabilizer such as a suspension stabilizer or a surfactant. However, the suspension stabilizer or the surfactant is added and emulsified. The method requires high shear forces. As a result, the generation of coarse particles and the particle size distribution become broad, which is not preferable. Therefore, it is preferable to use a self-water dispersible resin and neutralize the acidic group of the resin with a basic compound.

  As a method for neutralizing the acidic group (carboxyl group) of the polyester resin with a base, for example, (1) after producing a mixture containing a polyester resin having an acidic group, a colorant, a wax and an organic solvent, Or (2) a method in which a basic neutralizing agent is mixed in advance in an aqueous medium and the acidic groups of the polyester resin contained in the mixture are neutralized during phase inversion emulsification. Examples of the phase inversion emulsification method include (A) a method in which the mixture is added to an aqueous medium to emulsify, or (B) a method in which the aqueous medium is added to the mixture. By adopting a method combining the above (1) and (B), the particle size distribution becomes sharp, which is preferable.

  In phase inversion emulsification, homomixer (Special Machine Industries Co., Ltd.), Thrasher (Mitsui Mining Co., Ltd.), Cavitron (Eurotech Co., Ltd.), Microfluidizer (Mizuho Industry Co., Ltd.), Menton Gorin homogenizer (Gorin Inc.) ), Nanomizer (Nanomizer Co., Ltd.), Static Mixer (Noritake Company), etc., high share emulsifying disperser, continuous emulsifying disperser and the like can be used. However, rather than using a disperser with such a high share, for example, a stirring device, an anchor blade, a turbine blade, a fiddler blade, a full zone blade, a max blend blade, a meniscus blade, etc. described in JP-A-9-114135. It is preferable to use it. Among these, a large wing excellent in uniform mixing properties such as a Max blend wing and a full zone wing is more preferable. In the emulsification step (phase inversion emulsification step) for forming fine particles of the mixture in the aqueous medium, the peripheral speed of the stirring blade is preferably 0.2 to 10 m / s. A method of dropping water while stirring at a low shear of less than 0.2 to 8 m / s is more preferable. Most preferably, it is 0.2-6 m / s. When the peripheral speed of the stirring blade is faster than 10 m / s, the dispersion diameter at the time of phase inversion emulsification becomes large, which is not preferable. On the other hand, when the peripheral speed is lower than 0.2 m / s, the stirring is not uniform, phase inversion does not occur uniformly, and coarse particles tend to be generated, which is not preferable. Moreover, the temperature at the time of phase inversion emulsification is not particularly limited, but is not preferable because the higher the temperature, the more coarse particles are generated. On the other hand, when the temperature is too low, the viscosity of the mixture containing the polyester resin and the organic solvent is increased, and the generation of coarse particles is increased. The temperature range during phase inversion emulsification is preferably 10 to 40 ° C. More preferably, it is the range of 20-30 degreeC.

  By performing phase inversion emulsification under a low share using a self-water dispersible resin, the generation of fine powder and coarse particles can be suppressed, and as a result, agglomeration of fine particles having a uniform particle size distribution in the next coalescence process. It becomes easy to manufacture the aggregate. In addition, when a polyester resin having no self-water dispersibility is used, or when phase inversion emulsification is performed under a high share, the generation of coarse particles or the low molecular weight component of the resin generates fine powder, and toner particles The particle size distribution of the toner is widened, and furthermore, particles containing low molecular weight components are removed by sieving performed in the subsequent process, which causes a problem that the low temperature fixing property of the toner is deteriorated. Such inconvenience does not occur by using a water dispersible resin or performing phase inversion emulsification under a low share.

  The 50% volume average particle size of the fine particles produced in the first step is more than 1 μm and not more than 6 μm, more preferably more than 1 μm and 4 μm. If it is 1 μm or less, when a colorant or a release agent is used, it is not preferable because it is not sufficiently encapsulated by the polyester resin, which adversely affects charging characteristics and development characteristics. If the particle size is large, the particle size of the toner to be obtained is limited. Therefore, it is necessary to make the particle size smaller than the particle size of the target toner, but if it is larger than 6 μm, coarse particles are likely to be generated. Therefore, it is not preferable. The particle size distribution of the fine particles produced in the first step is such that the volume particle size ratio of 10 μm or more is 2% or less, more preferably 1% or less, and the volume particle size ratio of 5 μm or more is 10% or less. Preferably it is 6% or less.

  Next, in the second step, the fine particles obtained in the first step are coalesced to generate an aggregate of the fine particles, thereby forming toner particles having a desired particle diameter. In the second step, desired aggregates can be obtained by appropriately controlling the amount of solvent, temperature, type and amount of dispersion stabilizer and electrolyte, and stirring conditions. A method for producing aggregates by producing fine particles by emulsion polymerization, and then aggregating the fine particles and then fusing at a high temperature is well known. The production method in the present invention is different from the aggregate produced through the two-stage process of aggregation and fusion as described above, and the production method for obtaining the aggregate in a single-stage process including the fusion process at the same time as the aggregation. It is a (manufacturing method based on coalescence) and has a feature that spherical or substantially spherical particles can be obtained in a short time without heating.

  In the second step, the fine particle dispersion obtained in the first step is diluted with water to adjust the amount of solvent. Thereafter, a dispersion stabilizer is added and coalescence is advanced by dropping an aqueous electrolyte solution in the presence of the dispersion stabilizer to obtain an aggregate having a predetermined particle diameter. The fine particles formed from the self-water dispersible resin obtained up to the first step are stably dispersed in the aqueous medium by the action of the electric double layer by the carboxylate. In the second step, the particles are destabilized by adding an electrolyte that destroys or reduces the electric double layer to the aqueous medium in which the fine particles are dispersed.

  Examples of the electrolyte include acidic substances such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and oxalic acid. In addition, organic and inorganic water-soluble salts such as sodium sulfate, ammonium sulfate, potassium sulfate, magnesium sulfate, sodium phosphate, sodium dihydrogen phosphate, sodium chloride, potassium chloride, ammonium chloride, calcium chloride, sodium acetate, etc. It can be used effectively. These electrolytes to be added for unity may be used alone or in combination of two or more kinds. Among them, monovalent cation sulfates such as sodium sulfate and ammonium sulfate are preferable for promoting uniform coalescence. The fine particles obtained in the first step are swollen by a solvent, and the electric double layer of the particles is in an unstable state due to contraction due to the addition of an electrolyte. Therefore, the particles are produced by stirring with low shear (low shear force). Coalescence easily proceeds even in the collision between each other.

  However, only by adding an electrolyte or the like, the dispersion stability of the fine particles in the system is unstable, so that coalescence is not uniform and coarse particles and aggregates are generated. In order to prevent agglomerates of fine particles produced by electrolytes or acidic substances from repeating reunion and forming aggregates larger than the target particle size, before adding electrolytes etc., hydroxyapatite It is necessary to add an inorganic dispersion stabilizer such as ionic or nonionic surfactant as a dispersion stabilizer. The dispersion stabilizer to be used is required to have a property capable of maintaining dispersion stability even in the presence of an electrolyte added later. Examples of the dispersion stabilizer having such characteristics include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, Examples thereof include polyoxyethylene sorbitan fatty acid esters and the like, nonionic emulsifiers such as various pluronics, alkyl sulfate ester salt type anionic emulsifiers, and quaternary ammonium salt type cationic dispersion stabilizers. Among these, even if an anion type or nonionic type dispersion stabilizer is added in a small amount, the dispersion stability of the system is effective, which is preferable. The cloud point of the nonionic surfactant is preferably 40 ° C. or higher. The surfactants described above may be used alone or in combination of two or more. By adding an electrolyte in the presence of a dispersion stabilizer (emulsifier), it becomes possible to prevent non-uniform coalescence, resulting in a sharp particle size distribution and a corresponding increase in yield. Is done.

  Further, in order to promote uniform coalescence, the temporary stirring conditions are important. For example, a stirrer as disclosed in JP-A-9-114135, an anchor blade, a turbine blade, a fiddler blade, a full zone blade, a max blend blade, a cone cape blade, a helical blade, a double helical blade, a meniscus blade, etc. Used. Among these, a large wing excellent in uniform mixing properties such as a Max blend wing and a full zone wing is preferable. The fine particles swollen by the solvent are coalesced and aggregated by collision by stirring. For this reason, a high shearing device consisting of a stator and a rotor such as a homomixer or a high shearing device such as a turbine blade that is locally subjected to high shearing and a stirring blade that has a weak ability to uniformly stir the whole result in non-uniform coalescence. It tends to lead to generation of particles. Therefore, as stirring conditions, it is preferable that a circumferential speed is 0.2-10 m / s, and less than 0.2-8 m / s is more preferable. Most preferably, it is 0.2-6 m / s. When the peripheral speed is faster than 10 m / s, non-uniform coalescence occurs and coarse particles are easily generated, which is not preferable. On the other hand, if it is slower than 0.2 m / s, the stirring share is insufficient, so that non-uniform coalescence tends to occur and coarse particles tend to be generated. The coalescence proceeds only by the collision of the fine particles, and the coalesced aggregate does not dissociate and disperse again. Therefore, the generation of ultrafine particles is small and the particle size distribution becomes sharp, so that the yield can be improved.

  In the second step, it is preferable to further dilute the fine particle dispersion obtained by phase inversion emulsification in the first step with water as necessary. Thereafter, a dispersion stabilizer and an electrolyte are sequentially added to perform coalescence. Alternatively, it is preferable to adjust the amount of the solvent in the dispersion by adding an aqueous solution of a dispersion stabilizer and / or an electrolyte to obtain particles having a predetermined particle diameter. The amount of the solvent contained in the system after adding the electrolyte is preferably in the range of 5 to 25% by mass. Moreover, the inside of the range of 5-20 mass% is more preferable, and the inside of the range of 5-18 mass% is especially preferable. When the amount of the solvent is less than 5% by mass, the electrolytic mass required for coalescence is increased, which is not preferable. On the other hand, if the amount of the solvent is more than 25% by mass, the generation of aggregates due to non-uniform coalescence increases, and the amount of dispersion stabilizer added increases, which is not preferable.

  The shape of the toner particles after coalescence can be controlled by adjusting the amount of the solvent. When the amount of solvent is in the range of 13 to 25% by mass, the degree of swelling of the fine particles by the solvent is large, so that spherical to substantially spherical particles can be easily obtained by coalescence. On the other hand, when the amount of the solvent is in the range of 5 to 13% by mass, the degree of swelling of the fine particles by the solvent is small, so that irregularly to substantially spherical toner particles can be easily obtained.

  The amount of the dispersion stabilizer to be used is preferably in the range of 0.5 to 3.0% by mass with respect to the solid content of the fine particles, for example. A range of 0.5 to 2.5% by mass is more preferable, and a range of 1.0 to 2.5% by mass is particularly preferable. If it is less than 0.5% by mass, the desired effect of preventing the generation of coarse particles cannot be obtained. On the other hand, if the amount is more than 3.0% by mass, coalescence does not proceed sufficiently even if the amount of the electrolyte is increased, and particles having a predetermined particle diameter cannot be obtained. As a result, fine particles remain and yield. Is not preferable.

  Moreover, it is preferable that the quantity of the electrolyte to be used exists in the range of 0.5-15 mass% with respect to solid content content of microparticles | fine-particles. It is more preferably within a range of 1 to 12% by mass, and particularly preferably within a range of 1 to 10% by mass. When the amount of the electrolyte is less than 0.5% by mass, the coalescence does not proceed sufficiently, which is not preferable. On the other hand, when the amount of the electrolyte is more than 15% by mass, the coalescence becomes non-uniform, which is not preferable because aggregates and coarse particles are generated and the yield is lowered.

  The temporary temperature is preferably in the range of 10 to 50 ° C. More preferably, it exists in the range of 20-40 degreeC, and it is especially preferable that it is 20-35 degreeC. When the temperature is lower than 10 ° C., it is difficult to perform coalescence, which is not preferable. On the other hand, when the temperature is higher than 50 ° C., the coalescence speed is increased, and aggregates and coarse particles are easily generated, which is not preferable. Aggregates can be formed by coalescence under low temperature conditions of 20 to 40 ° C.

  Various embodiments can be adopted in the first step and the second step. Among these, preferred embodiments include the following (1) to (4). (1) A method in which fine particles are produced by the above first step using a resin solution comprising a polyester resin and a colorant, and if necessary, a release agent and a charge control agent, and the second step (unification step) is performed. (2) Using a resin solution comprising a polyester resin and a colorant, and if necessary, a mold release agent, fine particles are produced by the first step, and a dispersion of the charge control agent is mixed. (3) A method of performing (unification step), (3) A fine particle comprising a polyester resin is produced by the first step, and a dispersion of a colorant and, if necessary, a release agent and a dispersion of a charge control agent A method of performing the second step (unification step) after separately preparing one or more of the above, and (4) using the resin solution comprising the polyester resin and the release agent, the first step To produce fine particles, colorant dispersion, and By mixing the dispersion of the control agent, a method of performing a second step (coalescing step).

  Various dispersions such as a colorant dispersion, a charge control agent dispersion, and a release agent dispersion used here can be obtained as follows. For example, nonionic surfactants represented by polyoxyethylene alkylphenyl ethers, anionic surfactants represented by alkylbenzene sulfonates, alkyl sulfate esters, etc., or quaternary ammonium salts. It can be prepared by a mechanical pulverization method using a medium by adding it to water with a cationic surfactant represented by Alternatively, instead of the surfactant, a self-water dispersible polyester resin can be used to prepare a dispersion by the same dispersing means in the presence of a basic neutralizing agent. The colorant, release agent, and charge control agent used here may be those previously melt-kneaded with a polyester resin. In this case, when the resin is adsorbed, the degree to which various materials are exposed on the particle surface is alleviated, and preferable characteristics are provided in charging characteristics and development characteristics.

  In order to maintain the frictional charging performance satisfactorily, it is effective to prevent the colorant and the like from being exposed on the surface of the toner base particles, that is, to form a toner structure in which the colorant and the like are included in the toner base particles. The deterioration of the chargeability accompanying the reduction in the toner particle size is caused by the fact that a part of the contained colorant and other additives (usually wax etc.) are exposed on the surface of the toner base particles. That is, even if the content (% by mass) of the colorant and the like is the same, the surface area of the toner base particles is increased by reducing the particle size, and the ratio of the colorant and wax exposed on the surface of the toner base particles is increased. As a result, the composition of the surface of the toner base particles changes greatly, and the triboelectric charging performance of the toner base particles changes greatly, making it difficult to obtain an appropriate chargeability.

  It is desirable that the toner base particles include a colorant, wax, or the like included in the binder resin, and a favorable printed image can be obtained by the structure including the toner. In order to positively encapsulate the colorant and the release agent, the above method (1) or (2) is preferable. Whether the colorant, wax or the like is not exposed on the surface of the toner base particles can be easily determined by observing the cross section of the particles with a TEM (transmission electron microscope), for example. More specifically, a cross section obtained by embedding the toner base particles with a resin and cutting with a microtome is dyed with ruthenium oxide or the like if necessary, and observed with a TEM. It can be confirmed that the particles are uniformly dispersed. Further, the method (2) is preferable in order to localize the charge control agent on the surface of the toner particle and to express its function.

  The shape of the fine particle aggregate obtained in the second step can be changed from an indeterminate shape to a spherical shape depending on the degree of coalescence. For example, it can be changed from 0.94 to 0.99 in terms of average circularity. The average circularity can also be obtained by taking a SEM (scanning electron microscope) photograph of the toner particles obtained by drying the aggregates of fine particles, and measuring and calculating them. It can be easily obtained by using a flow type particle image analyzer FPIP-1000 manufactured by Electronics Corporation.

  The shape of the toner particles is substantially spherical or spherical with an average circularity of 0.97 or more, so that powder fluidity and transfer efficiency are improved. It is preferable. When the spherical shape approaches an indeterminate shape, the fluidity in the mixing tank described later is poor during the external addition process, and the yield decreases even when the peripheral speed of the stirring blade is reduced, and the amount of positively charged toner increases. There is a problem that the charge amount distribution is widened. Further, when the spherical shape approaches a true sphere, it is difficult to uniformly attach the external additive particles to the toner base particles, and therefore the peripheral speed of the stirring blade must be increased, and the welding to the tip of the blade or the tank wall is difficult. The amount of free external additives and the amount of positively charged toner increase, and the charge amount distribution tends to widen.

  The third step is a step of removing the organic solvent from the slurry by subsequently removing the solvent from the fine particle aggregate dispersion obtained in the second step. Subsequently, dust and coarse particles such as resin pieces are removed by passing through a wet vibrating screen, and solid-liquid separation can be performed by a known and commonly used means such as a centrifugal separator, a filter press, a belt filter or the like. Next, toner base particles can be obtained by drying the particles. The toner base particles produced using an emulsifier or a dispersion stabilizer are preferably washed more thoroughly.

  As the drying method, any known and commonly used method can be adopted. For example, a method in which the toner base particles are dried at normal or reduced pressure at a temperature at which the toner base particles are not thermally fused or aggregated, a freeze-dried method, and the like. Can be mentioned. Another example is a method of simultaneously separating and drying the toner base particles from the aqueous medium using a spray dryer or the like. In particular, a method in which the powder is stirred and dried under reduced pressure while heating at a temperature at which the toner base particles are not thermally fused or aggregated, or a flash jet dryer (Seishin) that is instantly dried using a heated and dried air stream. A method using a company corporation) is efficient and preferable.

  Regarding the particle size distribution of the toner base particles, the 50% volume particle size / 50% number particle size is preferably 1.25 or less, more preferably 1.20 or less, as measured by Multisizer TAII type manufactured by Coulter. is there. It is preferable that it is 1.25 or less because good images can be easily obtained. Moreover, GSD is preferably 1.30 or less, and more preferably 1.25 or less. The GSD is a value obtained from the square root of (16% volume particle size / 84% volume particle size) as measured by a multisizer TAII type manufactured by Coulter. The smaller the GSD value, the sharper the particle size distribution and the better the image.

  The toner base particles preferably have a volume average particle diameter in the range of 1 to 13 μm from the viewpoint of image quality to be obtained, and about 3 to 10 μm may be easily matched with the current machine. More preferable. For color toners, a volume average particle size of about 3 to 8 μm is preferred. When the volume average particle size is reduced, not only the resolution and gradation are improved, but also the effect that the thickness of the toner layer forming the printed image is reduced and the toner consumption per page is reduced is preferable. .

  Hereinafter, production examples of polyester resins, physical properties, and production examples of toner base particles will be shown. Unless otherwise indicated, parts are parts by mass, and water is deionized water.

(Example of polyester resin synthesis)
Terephthalic acid (TPA), isophthalic acid (IPA) as the divalent carboxylic acid, polyoxypropylene (2.4) -2,2-bis (4-hydroxyphenyl) propane (BPA-PO), polyoxy as the aromatic diol Table 1 below shows ethylene (2.4) -2,2-bis (4-hydroxyphenyl) propane (BPA-EO), ethylene glycol (EG) as an aliphatic diol, and trimethylolpropane (TMP) as an aliphatic triol. Using tetrabutyl titanate as a polymerization catalyst at 0.3% by mass with respect to the total amount of monomers, charging it into a separable fresco, and attaching a thermometer, stirring rod, condenser and nitrogen inlet tube to the top of the flask Decrease in order after reacting in an electric mantle heater at 220 ° C for 15 hours under normal pressure nitrogen flow. And, the reaction was continued at 10mmHg. The reaction was followed by a softening point according to ASTM E28-517. When the softening point reached a predetermined temperature, the vacuum was stopped and the reaction was terminated. Table 1 shows the composition and physical property values (characteristic values) of the synthesized resin.

In the table,>600,000; area ratio of components having a molecular weight of 600,000 or more <10,000; area ratio of components having a molecular weight of 10,000 or less TPA; terephthalic acid IPA; isophthalic acid BPA-PO; polyoxypropylene (2.4)- 2,2-bis (4-hydroxyphenyl) propane BPA-EO; polyoxyethylene (2.4) -2,2-bis (4-hydroxyphenyl) propane EG; ethylene glycol TMP; trimethylolpropane FT value; flow Tester Value In Table 1, “T1 / 2 temperature” is a load per unit area (cm ² ) using a flow tester (CFT-500) manufactured by Shimadzu Corporation as described above. It is a value measured at a heating rate of 10 kg, 6 ° C. per minute. The glass transition temperature “Tg” (° C.) is a value measured at a rate of temperature increase of 10 ° C. per minute by a second run method using a differential scanning calorimeter (DSC-50) manufactured by Shimadzu Corporation.

(Example of preparation of mold release agent dispersion)
After kneading 50 parts of carnauba wax “Carnauba Wax No. 1” (imported by Kato Yoko) and 50 parts of polyester resin (R1 in Table 1) with a pressure kneader, the kneaded product and 185 parts of methyl ethyl ketone were charged into a ball mill. After stirring for 6 hours, it was taken out and the solid content was adjusted to 20% by mass to obtain a fine dispersion (W1) of a release agent.

(Preparation of colorant master chip and preparation example of colorant dispersion)
Colorant master chips P1 and P2 were prepared by kneading carbon black and a color pigment in a weight ratio of 50/50 with a resin according to the formulation shown in Table 2 below. Carbon black and resin were kneaded using a pressure kneader. Further, the color pigment and the resin were kneaded with two rolls. The obtained kneaded product P2 was charged into a ball mill together with methyl ethyl ketone so that the solid content was 40% by mass, stirred for 36 hours, and then taken out. The solid content was adjusted to 20% by mass, and the colorant dispersion of P2 was dispersed. Liquid.

    The colorants shown in Table 2 are as follows.

Carbon: “ELFTEX-8” (Cabot)
Cyan pigment: Fast Gen Blue TGR (Dainippon Ink Chemical Co., Ltd.)
(Preparation of wet kneading mill base)
The above mold release agent dispersion, colorant dispersion, dilution resin (additional resin), and methyl ethyl ketone were mixed with Desper and the solid content was adjusted to 55% to prepare mill bases (MB1 to MB3). Table 3 shows the formulation of the produced mill base.

  The properties of the blend resin used in Table 3 are shown in Table 4. The resin blend was obtained by blending resin particles having passed through 200 mesh at the above weight ratio and measuring each physical property value.

In the table,>600,000; area ratio of components having a molecular weight of 600,000 or more <10,000; area ratio of components having a molecular weight of 10,000 or less (production of toner mother particles 1)
Add 545.5 parts of Millbase MB1 and 23.8 parts of 1N ammonia water to a cylindrical 2 L separable flask with a Max Blend blade as a stirring blade, and thoroughly stir at 350 rpm with a three-one motor. 133 parts of water was added and further stirred to adjust the temperature to 30 ° C. Subsequently, 133 parts of deionized water was added dropwise under the same conditions to prepare a fine particle dispersion by phase inversion emulsification. The peripheral speed of the stirring blade at this time was 1.19 m / s. Next, the amount of solvent was adjusted by adding 333 parts of deionized water.

  Next, 4.1 parts of Epan 450 (Daiichi Kogyo Seiyaku Co., Ltd.), which is a nonionic emulsifier, was diluted with water and added, and then the temperature was adjusted to 30 ° C. and the rotation speed was adjusted to 250 rpm. 410 parts of an aqueous solution of ammonium sulfate was added dropwise to adjust the amount of solvent in the dispersion to 15.5% by mass. Thereafter, stirring was continued for 5 minutes under the same conditions to complete the coalescence operation. The peripheral speed of the stirring blade at this time was 0.85 m / s. The obtained slurry was subjected to solid-liquid separation and washing with a centrifugal separator, and then dried with a vacuum dryer to obtain toner mother particles 1. The characteristics of the obtained toner mother particles are shown in Tables 5-7. The work function of the toner mother particles 1 was 5.47 eV.

(Manufacture of toner mother particles 2)
With the inter 70 minutes coalescence operation for 5 minutes in the manufacture of toner mother particles 1, except that the mill base MB1 and MB2, to obtain toner mother particles 2 in the same manner as manufacturing the toner base particles 1. The characteristics of the obtained toner mother particles are shown in Tables 5-7. The work function of the toner mother particles 2 was 5.33 eV.

(Manufacture of toner mother particles 3)
Toner base particles 3 were obtained in the same manner as in the manufacture of toner base particles 1 except that the coalescence operation for 5 minutes in the manufacture of toner base particles 1 was set to 70 minutes and mill base MB1 was changed to MB3. The characteristics of the obtained toner mother particles are shown in Tables 5-7. In addition, the work function of the toner base particles 3 was 5.39 eV.

  The particle size and particle size distribution in Table 6 were measured using a Coulter Multisizer II 100 micron aperture tube from Coulter Beckman. Dv50 is a 50% volume average diameter, and Dv50 / Dn50 is the ratio of volume and number 50% average diameter. GSD is the square root of the value obtained by dividing the 84% volume average diameter by the 16% volume average diameter.

  The circularity distribution was measured using a flow type particle image analyzer FPIP-1000 manufactured by Toa Medical Electronics Co., Ltd.

The yield is obtained by removing the solvent of the obtained toner mother particle dispersion and passing it through a 530 mesh sieve. The following formula yield (%) = {(solid content of mill base charged) − (residue on the sieve) Solid content)} × 100 / (solid content of mill base charged)
In the value obtained in step 90, 90% to 100% were taken as ◯.

  The work function (Φ) is known as energy necessary for extracting electrons from the substance. The smaller the work function, the easier it is to emit electrons, and the larger the work function, the less difficult it is to emit electrons. Therefore, it is considered that when negatively chargeable silicon oxide particles having a work function smaller than that of the toner base particles are externally added to the negatively chargeable toner base particles, the toner base particles are more negatively charged.

  The work function is measured by the following measurement method, and is quantified as energy (eV) for extracting electrons from the material, and the chargeability by contact between various materials can be evaluated. The work function is measured using a surface analyzer (AC-2, low energy electronic counting method manufactured by Riken Keiki Co., Ltd.). In the present invention, in the apparatus, a developing roller using a deuterium lamp and metal plating is set to an irradiation light amount of 10 nW, and for other measurements, the irradiation light amount is set to 500 nW, and monochromatic light is selected by a spectroscope. The sample is irradiated with a spot size of 4 mm square, an energy scanning range of 3.4 to 6.2 eV, and a measurement time of 10 sec / 1 point. The photoelectrons emitted from the sample surface can be detected and processed using work function meter software. The work function is measured with a repeatability (standard deviation) of 0.02 eV. . Note that, as a measurement environment for ensuring data reproducibility, a 24-hour left-over product is used as a measurement sample under the conditions of operating temperature and humidity of 25 ° C. and 55% RH.

  As shown in FIGS. 1 (a) and 1 (b), the toner dedicated measurement cell has a shape having a toner containing recess having a diameter of 10mm and a depth of 1mm at the center of a stainless steel disk having a diameter of 13mm and a height of 5mm. The sample toner is put into the concave portion of the cell without being solidified using a weighing sledge, and then subjected to measurement in a state where the surface is leveled and flattened using a knife edge. After the measurement cell filled with toner is fixed on the specified position of the sample stage, the irradiation light quantity is set to 500 nW, the spot size is set to 4 mm square, and the measurement is performed under the conditions of the energy scanning range of 4.2 to 6.2 eV.

  In addition, when the image forming apparatus member having a cylindrical shape such as the photosensitive member or the developing roller is used as a sample, the cylindrical image forming apparatus member is cut to a width of 1 to 1.5 cm, and then along the ridgeline. 2b, the sample piece for measurement having the shape shown in FIG. 2 (a) is obtained, and then the measurement light is irradiated on the specified position of the sample stage as shown in FIG. 2 (b). The surface to be irradiated is fixed so as to be smooth. Thereby, the emitted photoelectrons are efficiently detected by the detector (photoelectron tube).

  In this surface analysis, when the excitation energy of monochromatic light is scanned from low to high, photon emission starts from a certain energy value (eV), and this energy value is called a work function (eV). FIG. 3 shows an example of a chart obtained for the toner. FIG. 3 shows the excitation energy (eV) as the horizontal axis and the normalized photon yield (photon yield per unit photon as the nth power) as the vertical axis, and a constant slope (Y / eV) is obtained. . In the case of FIG. 3, the work function is indicated by the excitation energy value (eV) at the inflection point (A).

  The work function of the toner base particles in the present invention is preferably 5.3 to 5.7 eV.

Next, the external additive will be described.
In the present invention, the number average primary particle size defining the external additive is such that a droplet in which the external additive is dispersed in isopropyl alcohol is dropped on a measurement sample stage, and after drying, the fine particles on the sample stage are 100,000 times larger. These are obtained by actually measuring the particle diameter of 500 arbitrary particles of the scanning electron microscope image of “S-4800” manufactured by Hitachi Technology Co., Ltd.

  (1) Hydrophobic silica fine particles are hydrophobic silica fine particles having a negatively chargeable number average primary particle diameter of 7 to 60 nm, preferably 10 to 50 nm, and obtained by vapor phase oxidation (dry method) of a silicon halogen compound. Are exemplified. The silica fine particles (1) are added in an amount of 0.5 to 2.0 parts by mass, preferably 0.7 to 1.5 parts by mass with respect to 100 parts by mass of the toner base particles.

  The smaller the number average primary particle diameter of the negatively chargeable silica fine particles, the higher the fluidity of the resulting toner. However, if the particle diameter is smaller than 7 nm, the silica fine particles may be buried in the toner base particles. Further, if the number average primary particle diameter exceeds 60 nm, the fluidity may be deteriorated.

  As the negatively chargeable silica fine particles, “RX50” (number average primary particle diameter 32 nm, 5.16 eV), “RX200” (number average primary particle diameter 12 nm, work function 5.21 eV) manufactured by Nippon Aerosil Co., Ltd. Etc. are exemplified.

  (2) The negatively charged hydrophobic spherical silica fine particles having a number average primary particle size of 100 to 600 nm, preferably 100 to 300 nm, are so-called “large particle size” silica fine particles. The spherical silica fine particles are monodispersed, that is, the standard deviation with respect to the average particle size including aggregates is D50 * 0.22 or less, and as a shape, Wadell's sphericity is 0.6 or more, preferably 0.8 or more. It is. Such monodispersed spherical silica fine particles are obtained by a sol-gel method which is a wet method, and have a specific gravity of 1.3 to 2.1. The large particle size silica (2) is added in an amount of 0.2 to 2.0 parts by weight, preferably 0.3 to 1.5 parts by weight, based on 100 parts by weight of the toner base particles.

  If the average particle size is smaller than 100 nm, it is impossible to maintain the fluidity and charging stability by preventing the embedding of fine silica particles on the surface of the toner base particles, and the spacer effect cannot be obtained. On the other hand, if it is larger than 600 nm, it is difficult to adhere to the toner base particles and it is easy to be detached from the surface of the toner base particles.

  Hydrophobic negatively chargeable silica fine particles (2) include “Seahoster KEP10” (number average primary particle diameter 140 nm, work function 5.07 eV) manufactured by Nippon Shokubai Co., Ltd., and “Seahoster KE-P30” (number average primary). Examples thereof include a particle diameter of 280 nm and a work function of 5.02 eV).

  The addition ratio (mass ratio) of the large particle size silica (2) to the small particle size silica (1) is 1: 3 to 3: 1, preferably 1: 2.8 to 2.8: 1. It is preferable to provide fluidity to the toner and to obtain long-term charging stability. The large particle size silica and the small particle size silica may be added and mixed simultaneously with the toner base particles in the production of the negatively chargeable one-component toner. The large particle size silica and the small particle size silica are 1.0 to 2.5 parts by mass, preferably 1.5 to 2.3 parts in total with respect to 100 parts by mass of the toner base particles in consideration of the mixing ratio of both. Part by mass is added.

  The silica fine particles (1) and (2) are preferably hydrophobized. By making the surface of the silica fine particles hydrophobic, the fluidity and chargeability of the toner are further improved. Hydrophobization of silica fine particles depends on the chargeability of silane compounds such as aminosilane, hexamethyldisilazane and dimethyldichlorosilane; or dimethylsilicone, methylphenylsilicone, fluorine-modified silicone oil, alkyl-modified silicone oil, amino-modified silicone oil Using a hydrophobizing agent selected from silicone oils such as epoxy-modified silicone oils, it is carried out by methods commonly used by those skilled in the art, such as wet methods and dry methods.

  The work function of the hydrophobic silica particles (1) and (2) is in the range of 5.0 to 5.3 eV. In particular, the work function of the hydrophobic silica particles (2) having a large particle size is The work function is preferably at least 0.05 ev smaller than the work function of the toner base particles, and the silica particles having a large particle size can be fixed to the toner base particles by charge transfer due to the work function difference.

  Next, (3) Hydrophobic titanium oxide fine particles having a number average primary particle diameter of 10 to 40 nm have a relatively small electrical resistivity and can take various crystal forms such as a rutile type, anatase type, and rutile-anatase type. In particular, rutile-anatase type titanium oxide is preferably used because it has a spindle shape and is easy to adjust the charge, and even if the number of printed sheets is increased, it is difficult for titanium oxide particles to be embedded in toner base particles. The titanium oxide fine particles are added in an amount of 0.2 to 2.0 parts by weight, preferably 0.3 to 1.5 parts by weight, based on 100 parts by weight of the toner base particles.

  The surface of the titanium oxide fine particles is hydrophobic in order to reduce the change in chargeability with respect to the change in the external environment of the toner (that is, maintain stable chargeability) and improve the fluidity of the toner. Is preferred. Hydrophobization of the titanium oxide fine particles is carried out by the same method as that of the negatively chargeable silica fine particles. Examples of the hydrophobic rutile-anatase type titanium oxide fine particles include “STT-30S” (number average primary particle size 35 nm, work function 5.64 eV) manufactured by Titanium Industry Co., Ltd.

  The work function of the hydrophobic titanium oxide particles is in the range of 5.5 to 5.7 eV. The hydrophobic silica particles may be first externally added to the toner base particles and then added as a subsequent process.

  When the work function is substantially the same as that of the toner base particles, it is difficult to adhere directly to the toner base particles. However, since the work function can be attached to the toner base particles through the surface of the hydrophobic silica particles having a small work function, it is excessive. Charge transfer from the charged hydrophobic silica particles can be facilitated, and overcharging in the hydrophobic silica particles can be more effectively prevented, which is preferable.

  Next, (4) α-type alumina fine particles having a number average primary particle size of 100 to 600 nm, preferably 100 to 300 nm are industrially obtained by treating aluminum hydroxide obtained by treating bauxite raw material with sodium hydroxide in the atmosphere. The α-type alumina fine particles are obtained by the so-called Bayer method, and the α-type alumina fine particles have an indefinite shape and are externally added to the toner base particles. In this case, it has the effect of digging up the buried external additive, and can provide stable fluidity and charging characteristics. If the number average primary particle diameter is too large, the adhesion to the toner base particles is also lowered, which is not preferable.

  Examples of the α-type alumina fine particles include “AKP50” (number average primary particle diameter 190 nm, work function 4.81 eV), “AKP30” (number average primary particle diameter 410 nm, work function 4.80 eV) and the like manufactured by Sumitomo Chemical Co., Ltd. Illustrated.

  The α-type alumina fine particles may be 0.05 to 1.3 parts by mass, preferably 0.1 to 1.0 parts by mass with respect to 100 parts by mass of the toner base particles. When the amount is less than 0.05 parts by mass, the function as a spacer is not achieved, and when the amount is more than 1.3 parts by mass, the amount of released alumina particles having a large particle size increases, which is not preferable.

  The work function of the α-type alumina particles is 4.9 to 5.2 eV, and by making the work function (5.3 to 5.7 eV) of the toner base particles at least 0.05 eV, the negatively charged toner base is obtained. The particles can be made more negatively charged, and the adhesion with the externally added alumina fine particles can be enhanced.

Next, the metal soap particles will be described.
Metal soap particles can reduce the liberation rate of externally added particles such as silica fine particles and α-type alumina fine particles and prevent fogging. The photoconductor (OPC) can be protected from the polishing action caused by the above, and the life can be extended. The metal soap particles are metal salts selected from zinc, magnesium, calcium, and aluminum of higher fatty acids, and examples include magnesium stearate, calcium stearate, zinc stearate, monoaluminum stearate, and trialuminum stearate. The number average primary particle diameter of the metal soap particles is 0.1 to 1.5 μm, preferably 0.5 to 1.3 μm. The work function of the metal soap particles is in the range of 5.3 to 5.8 eV.

  The addition amount of the metal soap particles is 0.05 to 0.5 parts by mass, preferably 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the toner base particles. When the amount is less than 0.05 parts by mass, the function as a lubricant and the function as a binder are insufficient, and when the amount is more than 0.5 parts by mass, the fog tends to increase. The addition amount of the metal soap particles is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the external additive. When the amount is less than 2 parts by mass, there is no effect as a lubricant or a binder. On the other hand, when the amount exceeds 10 parts by mass, fluidity is lowered and fog is increased.

  Further, in the case of non-contact development, if continuous printing is performed for a long period of time, the negative charge amount of the toner becomes too high, resulting in a decrease in the development toner amount and a decrease in print image density. However, when the positively-charged silica fine particles are mixed in the subsequent processing, overcharging is suppressed and a decrease in image density can be prevented.

  The positively chargeable silica fine particles have a number average primary particle diameter of 20 nm to 40 nm. The positively chargeable silica fine particles are preferably hydrophobized to reduce the change in chargeability with respect to changes in the external environment (that is, maintain stable chargeability) and improve the fluidity of the toner. Therefore, it is preferable. Hydrophobization of the positively chargeable silica fine particles is performed using an aminosilane coupling agent, amino-modified silicone oil, or the like. The positively chargeable silica fine particles are added in an amount of 0.1 to 1.0 parts by weight, preferably 0.2 to 0.8 parts by weight, based on 100 parts by weight of the toner base particles.

  Examples of the hydrophobic positively chargeable silica fine particles include commercially available NA50H manufactured by Nippon Aerosil Co., Ltd. and TG820F manufactured by Cabot Co., Ltd. The work function of the positively chargeable hydrophobic silica fine particles is 5.2 to 5.4 eV.

  (3) Hydrophobic titanium oxide fine particles, (4) α-type alumina fine particles, (5) metal soap particles are (1) negatively chargeable hydrophobic silica fine particles and (2) negatively chargeable hydrophobic particles. After adding the silica fine particles, it may be added as a post-treatment.

  In addition, the negatively chargeable one-component toner of the present invention can be externally added within the range not impairing the object of the present invention, in addition to the external additive particles described above. For example, as inorganic fine particles, metal oxide fine particles such as strontium oxide, tin oxide, zirconia oxide, magnesium oxide, and indium oxide, nitride fine particles such as silicon nitride, carbide fine particles such as silicon carbide, calcium sulfate, barium sulfate, Examples thereof include fine particles of metal salts such as calcium carbonate, inorganic fine particles such as composites thereof, and fine resin particles.

  In the latter stage treatment, at least the hydrophobic titanium oxide fine particles and the α-type alumina fine particles are additionally mixed in the second step, and the metal soap particles and the positively charged silica fine particles are preferably added in the last step for the purpose of addition.

  Next, the process for mixing the toner base particles and the external additive particles in the present invention will be described. In the mixing process of the toner base particles and the external additive particles, the spherical mixing tank shown in FIGS. 4 and 5 is used. 4 is a central sectional view, and FIG. 5 is a plan view of an example of a mixing blade. In the figure, 1 is a processing tank, 2 is a horizontal disk-shaped tank bottom, 3 is a drive shaft, 4 is a donut disk, 5 is a stirring blade, 6 is an air seal hole, 7 is a cylindrical member, 8 is a flange, 9 is a jacket, 11 is a disk to which a stirring blade is attached.

  As shown in the figure, the spherical mixing treatment tank 1 has a horizontal disk-shaped tank bottom 2 and a stirring blade 11 having a conical section on a rotary drive shaft 3 penetrating the center of the tank bottom 2 vertically. A plurality of agitating blades 5 are respectively attached on the outer peripheral end portion. The stirring blade 11 is a turbine blade, and the shearing action by the blade is relatively small, so that mixing can proceed. In addition, a donut disk 4 for reinforcement is attached to the upper part of the stirring blade 5.

  A cylindrical member 7 penetrating the top of the mixing treatment tank on the extension line of the rotary drive shaft 3 is arranged on the top of the container 1 so that the front end of the tank is located in the upper hemisphere, thereby enabling sealing air bleeding. The upper hemisphere in the mixed treatment layer can be opened and closed from the flange 8 at the center, and the workpiece is introduced by opening the upper hemisphere. The charged object to be processed is spirally released along the inner wall surface of the processing tank 1 by a centrifugal force generated by the rotation of the stirring blade 11 (not shown) and is discharged upward as shown by the arrows in FIG. Drop with reduced kinetic energy. The dropped processing object slides down the conical upper surface and is re-supplied to the stirring blade 5. By repeating this process, dispersion mixing proceeds. A discharge port (not shown) for an object to be processed after external addition is provided in the lower part of the processing tank 1. In addition, the spherical mixing treatment tank is provided with a water cooling jacket 9, and the contents can be cooled by passing cooling water having a water temperature described later at a flow rate described later.

  A stirring blade 11 is rotatably attached to the rotary drive shaft 3 through a seal air hole 6, and the tip of the stirring blade 5 is connected to the outer periphery of the donut disk 4 and the inner wall of the tank as shown in FIGS. 4 and 5. It arrange | positions so that it may be located between. Further, the lower edge of the stirring blade 5 is formed in an arc shape along the spherical inner wall of the processing tank 1 as shown in FIG. 4, and the object to be processed is rotated along the curved surface of the inner surface of the processing tank by rotating. It is set as the shape which can discharge | release spirally toward a processing tank top part. The seal air hole 6 is an air supply hole for preventing the workpiece from entering the rotary drive shaft portion that is at a high temperature, and the supplied air is discharged from the cylindrical member 7.

  From the viewpoint of uniform processability of the workpiece and the ability to discharge the supplied air, the length of the charging member 7 inside the container is 1/20 or more of the height from the donut-shaped disk 4 inside the container, The length is preferably 1/3 or more, but the upper limit is preferably a length that does not come into contact with the powder surface when the workpiece is left standing. Further, the cylindrical member 7 may have a structure other than the cylindrical shape so that the seal air can escape, and may have a structure having a slit, for example.

  Further, the ratio of the diameter of the horizontal tank bottom 2 to the diameter of the treatment tank 1 is 0.25 to 0.80, and the ratio of the outer diameter of the donut disk 4 to the diameter of the horizontal tank bottom 2 is. Is 0.50 to 1.20, and the ratio of the diameter of the stirring blade 5 to the diameter of the treatment tank 1 is preferably 0.50 to 0.90. The ratio of the inner diameter to the outer diameter of the donut disk 4 is 0.5 to 0.95, preferably 0.7 to 0.8. Moreover, the preparation amount of the processing object to a spherical mixing processing tank is 0.1-0.9 by the ratio with respect to the volume of a processing tank, Preferably it is good to set it as 0.3-0.5.

  The spherical mixing treatment tank does not cause the object to be treated to rise abruptly like a Henschel mixer as shown in FIG. 6, but the toner mother particles and external additive particles that are the object to be treated are curved in the shape of a curved tank wall. In addition, the wall surface distance through which the material to be processed flows is long, and the toner base particles are easy to roll, enabling uniform external addition processing in a short time. Furthermore, after moving the object to be processed to the ceiling of the mixing treatment tank, it is supplied to the stirring blades at the bottom of the tank and reprocessed, so that the vertical movement of the object to be treated, which is dependent on gravity, is a cylinder like a Henschel mixer. Compared to the shape of the mixing treatment tank, it is more dynamic and has the advantage that it is not necessary to provide an upper blade. Moreover, when the aggregation of the external additive particles is strong, a convex portion can be provided in the tank to generate a turbulent flow and disintegrate.

  When mixing a plurality of external additive particles having an average particle size different from that of the toner base particles, a “multistage mixing process” can be used. However, if the mixing process time is short, the mixing process becomes insufficient. When the mixing treatment time is long, the object to be treated is welded to the tank wall, the stirring blade, etc., and the yield is lowered. Therefore, the treatment time at each stage is 0.5 to 10 minutes, preferably 1 to 5 Must be within minutes. In addition, in order to avoid a temperature rise, the process in each step may be divided into several times and mixed. From the same point of view, the peripheral speed (π × outermost diameter of blade × rotational speed / hour) of the tip of the stirring blade in the spherical mixing treatment tank is in the range of 10 m / s to 100 m / s.

  In external addition to the toner base particles, after the toner base particles are filled in the spherical mixing treatment tank, as a first stage, silica particles having a large particle size and a small particle size are added, externally added, and then rotated. After stopping, as the second stage, titanium oxide particles and α-type alumina fine particles are additionally added and externally added. Then, after the rotation is stopped, as the third stage (final stage), positively-charged silica particles and metal soap particles are additionally added and externally added.

  In the method for producing a negatively chargeable toner of the present invention, silica fine particles are externally added to the toner base particles as a first-stage external addition treatment. The silica fine particles adhere to the toner base particles due to the work function difference. It has excellent properties and can be satisfactorily adhered to spherical toner base particles having a high degree of circularity. In the second and subsequent stages, the α-type alumina fine particles having a large particle size can be externally added by utilizing charge transfer due to the work function difference from the toner base particles, and negative adhesion with excellent adhesion of the external additive can be achieved. A chargeable toner can be produced. Thereby, it is possible to obtain a negatively chargeable toner which is excellent in charging stability and does not cause unevenness in a printed image.

  The toner produced in the present invention can be applied to both an image forming apparatus using a one-component toner described in detail in JP-A-2002-202622 and an image forming apparatus using a two-component toner. The image forming apparatus can be applied to both a contact developing type image forming apparatus and a non-contact type image forming apparatus, but is preferably a one-component non-magnetic color toner and has a non-contact type developing system. Negatively chargeable toner suitable for application to a toner.

Hereinafter, specific examples will be described.
Example 1
The toner base particles 2 produced above are used, and 3.0 kg of the toner base particles 2 is loaded into a spherical mixing tank (Q type 20L, blade-shaped turbine manufactured by Mitsui Mining Co., Ltd.) shown in FIG. {“RX200” (number average primary particle size 12 nm, work function 5.21 eV) 36 g and “RX50 (average particle size 32 nm, 5.16 eV) 15 g” manufactured by Nippon Aerosil Co., Ltd. “Seahoster KEP10” manufactured by Nippon Shokubai Co., Ltd. (Number average primary particle diameter 140 nm, work function 5.07 eV) was added.

The spherical mixing tank has an internal volume of 20 liters, the length of the cylindrical member 7 inside the container is 1/11 of the height from the donut disk 4 inside the container, and the diameter of the tank bottom 2 and the processing tank 1 is 0.57, the ratio of the outer diameter of the donut disk 4 to the diameter of the horizontal tank bottom 2 is 1.10, the diameter of the stirring blade (turbine blade) 5 and the treatment tank 1 The ratio with the diameter is 0.75, and the ratio between the inner diameter and the outer diameter of the donut disk 4 is 0.73. This spherical mixing treatment tank was mixed with a seal air amount of 1.0 Nm ³ / h, a turbine blade peripheral speed of 50 m / s, and a mixing time of 2 minutes.

After the mixing was stopped, as the second-stage external addition treatment, “STT-30S” (number average primary particle size 35 nm, work function 5.64 eV) 12 g manufactured by Titanium Industry Co., Ltd. and “AKP50” (number average manufactured by Sumitomo Chemical Co., Ltd.) were used. 6 g of a primary particle diameter of 190 nm and a work function of 4.81 eV) was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, as the third stage external addition treatment, 9 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 3 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s and mixing The mixture was processed for 2 minutes to obtain a toner.

  Next, 220 g of each toner was filled in the developing unit of a color printer (“LP7000C” manufactured by Seiko Epson Corporation) with the obtained toner, and 6,000 sheets of durable printing were performed with 5% original and A4 (25 ° C, 50% RH).

  The amount of charge (average of negative charge Q / m) and the amount of toner (number%) before and after durable printing were measured with an Espart analyzer (manufactured by Hosokawa Micron Corporation). Further, after 100% solid printing after the durability, the uniformity of the image was visually determined and evaluated with no unevenness (O) and presence (X). The results are shown in Table 8.

  FIG. 7 shows the charge amount distribution before endurance by line (1) and the charge amount distribution after endurance by line (2).

(Example 2)
The toner base particles 2 produced as described above were used, and 3.0 kg of the toner base particles 2 were charged in the same spherical mixing tank as in Example 1. Then, negatively charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) "RX50" (average particle size 32 nm, 5.16 eV) 15 g and "Seahoster KEP10" (number average primary particle size 140 nm, work function 5.07 eV) manufactured by Nippon Shokubai Co., Ltd. 12 g was added, the seal air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After mixing was stopped, 10 g of “STT-30S” (number average primary particle diameter 35 nm, work function 5.64 eV) manufactured by Titanium Industry Co., Ltd. was added as the second stage external addition treatment, and the seal air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes.

After the mixing was stopped, as the third-stage external addition treatment, 8 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 3 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s and mixing The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

(Example 3)
The toner base particles 2 produced as described above were used, and 3.0 kg of the toner base particles 2 were charged in the same spherical mixing tank as in Example 1. Then, negatively charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) , Work function 5.21 eV) 36 g and the same “RX50” (average particle diameter 32 nm, 5.16 eV) 13 g are added, the seal air amount is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s. The mixing process was performed with a mixing time of 2 minutes.

After the mixing was stopped, as the second-stage external addition treatment, “STT-30S” (number average primary particle diameter 35 nm, work function 5.64 eV) 14 g manufactured by Titanium Industry Co., Ltd. and “AKP50” (number average manufactured by Sumitomo Chemical Co., Ltd.) were used. 12 g of a primary particle diameter of 190 nm and a work function of 4.81 eV were added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, as the third stage external addition treatment, 9 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 3 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s and mixing The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

Example 4
The toner base particles 2 produced as described above were used, and 3.0 kg of the toner base particles 2 were charged in the same spherical mixing tank as in Example 1. Then, negatively charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) "RX50" (average particle diameter 32 nm, 5.16 eV) 13 g and "Seahoster KEP10" manufactured by Nippon Shokubai Co., Ltd. (number average primary particle diameter 140 nm, work function 5.07 eV) 6 g was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, as the second-stage external addition treatment, “STT-30S” (number average primary particle size 35 nm, work function 5.64 eV) 12 g manufactured by Titanium Industry Co., Ltd. and “AKP50” (number average manufactured by Sumitomo Chemical Co., Ltd.) were used. 3 g of a primary particle diameter of 190 nm and a work function of 4.81 eV) were added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes.

After the mixing was stopped, as the third-stage external addition treatment, 8 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 2 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s. The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

(Example 5)
The toner base particles 2 produced as described above were used, and 3.0 kg of the toner base particles 2 were charged in the same spherical mixing tank as in Example 1. Then, negatively charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) "RX50" (average particle diameter 32 nm, 5.16 eV) 17 g and "Seahoster KEP10" manufactured by Nippon Shokubai Co., Ltd. (number average primary particle diameter 140 nm, work function 5.07 eV) 12 g was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, as the second-stage external addition treatment, “STT-30S” (number average primary particle size 35 nm, work function 5.64 eV) 12 g manufactured by Titanium Industry Co., Ltd. and “AKP50” (number average manufactured by Sumitomo Chemical Co., Ltd.) were used. 9 g of a primary particle diameter of 190 nm and a work function of 4.81 eV) was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes.

After the mixing was stopped, as the third stage external addition treatment, 9 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 2 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s. The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

(Example 6)
The toner base particles 2 produced as described above were used, and 3.0 kg of the toner base particles 2 were charged in the same spherical mixing tank as in Example 1. Then, negatively charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) "RX50" (average particle diameter 32 nm, 5.16 eV) 17 g and "Seahoster KEP30" manufactured by Nippon Shokubai Co., Ltd. (number average primary particle diameter 280 nm, work function 5.02 eV) 15 g was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 60 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, as the second-stage external addition treatment, “STT-30S” (number average primary particle size 35 nm, work function 5.64 eV) 12 g manufactured by Titanium Industry Co., Ltd. and “AKP30” (number average manufactured by Sumitomo Chemical Co., Ltd.) were used. 12 g of a primary particle diameter of 410 nm and a work function of 4.80 eV were added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 60 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, 7 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.)} and metal soap “magnesium stearate” particles {“Nissan Electric” Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 2 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 60 m / s. The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

(Example 7)
The toner base particles 1 produced above were used, and 3.0 kg of the toner base particles 1 were charged in the same spherical mixing tank as in Example 1. Then, negatively charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) "RX50" (average particle diameter 32 nm, 5.16 eV) 15 g and "Seahoster KEP10" manufactured by Nippon Shokubai Co., Ltd. (number average primary particle diameter 140 nm, work function 5.07 eV) 9 g was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, as the second-stage external addition treatment, “STT-30S” (number average primary particle size 35 nm, work function 5.64 eV) 12 g manufactured by Titanium Industry Co., Ltd. and “AKP50” (number average manufactured by Sumitomo Chemical Co., Ltd.) were used. 6 g of a primary particle diameter of 190 nm and a work function of 4.81 eV) was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes, and the mixing process was performed.

After the mixing was stopped, as the third stage external addition treatment, 9 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 3 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s and mixing The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

(Example 8)
The toner base particles 3 produced above were used, and 3.0 kg of the toner base particles 3 were charged in the same spherical mixing tank as in Example 1. Then, negatively-charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) "RX50" (average particle diameter 32 nm, 5.16 eV) 15 g and "Seahoster KEP10" manufactured by Nippon Shokubai Co., Ltd. (number average primary particle diameter 140 nm, work function 5.07 eV) 9 g was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 40 m / s, and the mixing time was 2 minutes, and the mixing treatment was performed.

After the mixing was stopped, as the second-stage external addition treatment, “STT-30S” (number average primary particle size 35 nm, work function 5.64 eV) 12 g manufactured by Titanium Industry Co., Ltd. and “AKP50” (number average manufactured by Sumitomo Chemical Co., Ltd.) were used. 6 g of a primary particle diameter of 190 nm and a work function of 4.81 eV) was added, the sealing air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 40 m / s, and the mixing time was 2 minutes.

After the mixing was stopped, as the third stage external addition treatment, 9 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 3 g is added, the seal air amount is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 40 m / s. The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

(Comparative Example 1)
The toner base particles 2 produced above were used, and 3.0 kg of the toner base particles 2 were loaded into a Henschel mixer (Mitsui Mining Co., Ltd., 20L, YiA0) shown in FIG. 15 g of number average primary particle diameter 15 nm, work function 5.10 eV) and 15 g titania fine particles {“JMT150AO” (number average primary particle diameter 15 nm, work function 5.60 eV) manufactured by Teica Co., Ltd. are added, and the peripheral speed of the blade is 50 m. / S was mixed to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

(Comparative Example 2)
50:50 (weight ratio) mixture of polycondensed polyester of aromatic dicarboxylic acid and alkylene etherified bisphenol A and a partially cross-linked product of the polycondensed polyester with a polyvalent metal compound (manufactured by Sanyo Chemical Industries, Ltd.) 100 mass Part, 5 parts by mass of cyan pigment phthalocyanine blue, 5 parts by mass of polypropylene having a melting point of 152 ° C. and a weight average molecular weight Mw of 4000 as a release agent, and salicylic acid metal complex E-81 (Orient Chemical Industries ( 4 parts by mass) were mixed uniformly using a Henschel mixer, kneaded with a twin-screw extruder having an internal temperature of 150 ° C., and then cooled. Next, the cooled product is coarsely pulverized to 2 mm square or less, then finely pulverized by a jet mill, classified by a classifier by rotating a rotor, and then 0.5% by mass of silica fine particles (primary particle diameter 40 nm) as an anti-fusing agent. , Using a hot-air spheronizing device surfing system (SFS-3 type, manufactured by Nippon Pneumatic Industry), setting the heat treatment temperature to 200 ° C., partially spheroidizing, and classifying again in the same manner As a result, cyan toner base particles were obtained. The obtained toner base particles had an average particle size of 8.1 μm and a flow softening point (Tf1 / 2) of 108.8 ° C.

  Using the toner mother particles produced as described above, 3.0 kg of the toner mother particles were loaded into a spherical mixing tank (Mitsui Mining Co., Ltd., Q-type 20L, blade-shaped turbine) shown in FIG. Externally added to obtain toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

  FIG. 7 shows the charge amount distribution before endurance by line (3) and the charge amount distribution after endurance by line (4).

(Comparative Example 3)
The toner base particles 2 produced as described above were used, and 3.0 kg of the toner base particles 2 were charged in the same spherical mixing tank as in Example 1. Then, negatively charged silica fine particles {“RX200” manufactured by Nippon Aerosil Co., Ltd. (number average primary particle size: 12 nm) , Work function 5.21 eV) and 36 g of the same “RX50” (average particle diameter 32 nm, 5.16 eV) are added, the seal air amount is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s. The mixing process was performed with a mixing time of 2 minutes.

After mixing was stopped, 10 g of “STT-30S” (number average primary particle diameter 35 nm, work function 5.64 eV) manufactured by Titanium Industry Co., Ltd. was added as the second stage external addition treatment, and the seal air amount was 1.0 Nm ³ / h, the peripheral speed of the turbine blade was 50 m / s, and the mixing time was 2 minutes.

After the mixing was stopped, as the third-stage external addition treatment, 8 g of positively charged silica particles {“NA50H” (number average primary particle size 40 nm) manufactured by Nippon Aerosil Co., Ltd.} and metal soap “magnesium stearate” particles {“Nissan Elect Toll MM-2 ”(number average primary particle size 1.3 μm, work function 5.32 eV)} 3 g is added, the amount of seal air is 1.0 Nm ³ / h, and the peripheral speed of the turbine blade is 50 m / s and mixing The mixture was processed for 2 minutes to obtain a toner.

  Similarly to Example 1, the charge amount (average of Q / m) before and after the durable printing (Q / m average), + toner amount (number%), and image uniformity were evaluated, and the results are also shown in Table 8.

  From the table, it can be seen that Examples 1 to 8 are smaller in charge amount before and after durable printing than in Comparative Example 3, and are excellent in image uniformity without unevenness.

  In Comparative Example 1, silica particles having a small particle diameter and titanium oxide particles having a small particle diameter are externally added by a Henschel mixer. However, the charge amount after endurance becomes too low, and the amount of + toner is Many leaks and scattering occurred, and the image was uneven.

  Comparative Example 2 is a case where toner base particles are obtained by a pulverization method, and there are a lot of fine powders and the charge amount distribution is high. It was expressed and became a beetle.

FIG. 1 is a diagram showing a measurement cell used for measuring a work function, in which (a) is a front view and (b) is a side view. 2A and 2B are diagrams for explaining a method for measuring a work function of a cylindrical image forming apparatus member. FIG. 2A is a perspective view showing a shape of a measurement sample piece, and FIG. 2B is a view showing a measurement state. . FIG. 3 is an example of a chart in which the work function of the toner is measured using a surface analyzer. FIG. 4 is a central sectional view of the spherical mixing treatment tank. FIG. 5 is a plan view of an example of a mixing blade. FIG. 6 is a central sectional view of the Henschel type mixing treatment tank. FIG. 7 is a graph showing the charge amount distribution before and after durable printing using the negatively chargeable toner obtained in Example 1 and Comparative Example 2.

Explanation of symbols

1 is a treatment tank, 2 is a horizontal disk-shaped tank bottom, 3 is a drive shaft, 4 is a donut disk, 5 is a stirring blade, 6 is an air seal hole, 7 is a cylindrical member, 8 is a flange, 9 is a jacket

Claims (3)

Obtained by aggregating and coalescing the polyester resin particles by adding a dispersion stabilizer and an electrolyte to a phase inversion emulsion comprising anionic self-water-dispersed polyester resin particles containing a colorant and a wax component and an aqueous medium. Toner base particles,
Hydrophobic silica fine particles having a number average primary particle diameter of 7 to 60 nm externally added to the toner base particles ;
Hydrophobic titanium oxide fine particles having a number average primary particle diameter of 10 to 40 nm externally added to the toner base particles ,
Hydrophobic silica fine particles having a number average primary particle diameter of 100 to 600 nm externally added to the toner base particles ;
A negatively chargeable toner characterized by comprising: Negatively chargeable toner according to claim 1 containing the toner base particles in external addition treated positively chargeable silica fine particles, and the toner base particles externally added metal soap particles. Obtained by aggregating and coalescing the polyester resin particles by adding a dispersion stabilizer and an electrolyte to a phase inversion emulsion comprising anionic self-water-dispersed polyester resin particles containing a colorant and a wax component and an aqueous medium. Toner base particles,
Hydrophobic silica fine particles having a number average primary particle size of 7 to 60 nm,
Hydrophobic titanium oxide fine particles having a number average primary particle size of 10 to 40 nm,
An image forming apparatus comprising: a negatively chargeable toner externally treated with hydrophobic silica fine particles having a number average primary particle size of 100 to 600 nm.

Images