JP4765760B2 - Electrostatic latent image developing toner and image forming method - Google Patents

Description

  The present invention relates to an electrostatic latent image developing toner for developing and visualizing an electrostatic latent image in an electrophotographic method, an electrostatic recording method, and the like, and an image forming method.

  As an electrophotographic process, many methods are known as described in Japanese Patent Publication No. 42-23910. In general, a latent image is electrically formed by various means on the surface of a photoreceptor (latent image holding body) using a photoconductive substance, and the formed latent image is developed with toner. After the image is formed, the toner image on the surface of the photosensitive member is transferred to the surface of a transfer material such as paper with or without an intermediate transfer member, and the transferred image is heated, pressurized, heated and pressurized, or solvent vapor. A fixed image is formed through a plurality of steps of fixing by, for example. The toner remaining on the surface of the photoreceptor is cleaned by various methods as necessary, and is again subjected to the above-described plurality of steps.

  Conventionally, as an electrophotographic developer used for developing an electrostatic latent image formed on an electrophotographic photosensitive layer, a toner composed of a toner obtained by dispersing a colorant in a binder resin is used. In general, a component developer or a two-component developer obtained by mixing toner and particles of iron, ferrite, nickel or the like or a carrier obtained by coating these with various resins is used. By the way, these developers alone do not have sufficient properties such as storage stability (blocking resistance), fluidity, developability, transferability, charge retention, and the like. To improve these properties, toner particles such as silica particles are used. Often, inorganic particle additives are externally added. However, silica particles have strong negative chargeability, and there is a problem that a large difference is caused in chargeability between low temperature and low humidity and high temperature and high humidity, which may cause poor density reproduction and background fog. .

  In order to improve these points, various types using hydrophobized silica particles have been proposed, and silane coupling treatment as disclosed in JP-A-63-139367 has been performed. After that, those using silica particles or the like that have been further treated with silicone oil to improve hydrophobicity have been proposed. However, these materials do not provide a sufficient effect, and the silica particles treated with silicone oil have a high viscosity of the oil. Therefore, the silica particles are agglomerated during the treatment, which adversely affects the powder flowability. there were. Further, when conventional hydrophobic silica particles are externally added to the toner, there is a drawback in that it adversely affects characteristics such as charging speed, charge amount distribution, and toner admixability.

  In order to remedy this drawback, a method of using hydrophobic silica particles and titanium oxide particles in combination has been proposed. However, although this method can improve the above-mentioned characteristics, there is a problem that the charge amount becomes very low. On the other hand, hydrophobic titanium oxide in which titanium oxide is treated with a silane compound, a silane coupling agent, silicone oil, etc. has been proposed. Although this can improve the degree of charge reduction to some extent, On the other hand, the effect of improving the charging speed and toner admixability by adding titanium oxide is lost.

  In addition, titanium oxide dehydrated and fired by the conventional sulfuric acid method has secondary and tertiary agglomeration, and has the disadvantage of adversely affecting the fluidity of the toner. For this reason, when the toner particle size is reduced, this tendency appears more remarkably.

  JP-A-3-89358 and JP-A-3-93605 disclose toners to which metal oxide particles surface-treated with a silicon compound containing a perfluoroalkyl group are added. It has been reported that the slipperiness due to the group is improved and the fluidity of the toner is improved. However, in particular, when silica particles surface-treated with a silicon compound containing a perfluoroalkyl group are used, although there are excellent effects in charge amount, environmental stability of charge, and admixability of toner, sleeves and carriers and There is a drawback that particles easily adhere to the surface of the photoreceptor and have an adverse effect on durability, charging stability over time, and filming.

  Furthermore, due to the demand for higher image quality in full-color images, as the diameter of the toner decreases, the adhesion of the toner to the electrostatic latent image carrier becomes greater in the transfer process compared to the Coulomb force applied to the toner particles. There was a tendency that the residual toner increased (residual toner) and the charging failure of the electrostatic latent image carrier was accelerated.

  As a means for improving the transfer efficiency of toner, it has been proposed to make the toner shape close to a spherical shape (Japanese Patent Laid-Open No. 62-184469, etc.). Further, a developer that comprehensively considers transfer efficiency by defining the toner particle size and particle size distribution and the average circularity and circularity distribution of the toner has been proposed (Japanese Patent Laid-Open Nos. 11-344829 and 11). -295931.

  In these proposals, the transfer efficiency is improved by making the toner shape / shape distribution close to a sphere, but by making the toner spheroid, the fluidity as a developer is increased, and at the same time, the solidification and the bulk density are increased. As a result, a phenomenon occurs in which the toner conveyance amount in the developing unit becomes unstable. By controlling the surface roughness of the mag roll surface and reducing the distance between the conveyance amount control material and the mag roll, it is possible to improve the toner conveyance amount, but the toner bulk density becomes higher and the toner accordingly The stress applied to the toner also becomes strong, and the toner structure maintainability against this stress is weakened.

  On the other hand, it has been disclosed that it is effective to use inorganic particles having a large particle size in order to suppress the burying of external additives in the toner (colored particles) against such stress (Japanese Patent Laid-Open No. Hei 7). No. 28276, JP-A-9-319134, JP-A-10-312089, etc.).

  However, in any case, if the external additive particles are enlarged, peeling of the external additive is unavoidable due to the agitation stress in the developing device.

  Also disclosed is a technique for adding spherical organic resin particles having a particle size in the range of 50 to 200 nm to the toner (JP-A-6-266152, etc.). By using the spherical organic resin particles, it is possible to effectively exhibit a spacer function in the initial stage.

  However, since the spherical organic resin particles themselves are deformed, it is difficult to stably develop a high spacer function, and at the same time, influence on powder properties such as fluidity inhibition of inorganic particle-added toner and deterioration of thermal aggregation, and The organic resin particles themselves have a charge-imparting ability, which causes an influence on charging and development in that the degree of freedom of control in terms of charging is reduced.

Japanese Patent Publication No.42-23910 JP-A-63-139367 JP-A-3-89358 Japanese Patent Laid-Open No. 3-93605 Japanese Patent Laid-Open No. 62-184469 Japanese Patent Laid-Open No. 11-344829 Japanese Patent Laid-Open No. 11-295931 JP-A-7-28276 JP-A-9-319134 Japanese Patent Laid-Open No. 10-312089 JP-A-6-266152

  An object of the present invention is to solve the conventional problems and to achieve the following problems. That is, the object of the present invention is to have a high charge amount, excellent charging environment dependency, stable charging over time and toner admixability, and excellent toner fluidity and development / transferability. An electrostatic latent image developing toner and an image forming method are provided.

The above problem is solved by the following means. That is,
The electrostatic latent image developing toner of the present invention is a volume average particle that has been hydrophobized using a toner particle having a volume average particle size of 4 to 12 μm and an alkyl silane coupling agent having an alkyl group having 10 or more carbon atoms. A large-diameter external additive composed of silica particles having a diameter of 80 to 300 nm and obtained by burning silicon tetrachloride in an oxyhydrogen flame, and a small-diameter external additive having a volume average particle diameter of 5 to 20 nm , And a basic fluidity energy amount of 300 mJ or less when measured with a powder rheometer under conditions of an air flow rate of 0 ml / min, a tip speed of the rotor blade of 50 mm / sec, and an entrance angle of the rotor blade of -10 ° It is characterized by that.

  In the electrostatic latent image developing toner of the present invention, the silica particles are measured with a powder rheometer under conditions of an air flow rate of 0 ml / min, a tip speed of the rotor blade of 50 mm / sec, and an entrance angle of the rotor blade of -10 °. The basic fluidity energy amount is preferably 40 to 100 mJ.

On the other hand, the image forming method of the present invention comprises:
A charging step for charging the electrostatic latent image carrier;
A latent image forming step of forming an electrostatic latent image on the surface of the charged electrostatic latent image carrier;
A development step of developing the electrostatic latent image with a developer containing the electrostatic latent image developing toner of the present invention to form a toner image on the electrostatic latent image carrier;
A transfer step of transferring the toner image onto a recording medium to form an unfixed transfer image;
A fixing step of fixing the unfixed transfer image transferred onto the recording medium;
It is characterized by having.

  According to the present invention, an electrostatic charge having a high charge amount, excellent charging environment dependency, charging stability over time and toner admixability, and excellent toner fluidity and development / transferability. A latent image developing toner and an image forming method can be provided.

  Hereinafter, the present invention will be described in detail.

<Toner for electrostatic latent image development>
The electrostatic latent image developing toner of the present invention (hereinafter simply referred to as “toner”) contains hydrophobized silica particles having a volume average particle diameter of 80 to 300 nm, an aeration flow rate of 0 ml / min, and a rotating blade. The basic fluidity energy amount is 300 mJ or less as measured by a powder rheometer under the conditions of a tip speed of 50 mm / sec and an approach angle of the rotating blade of −10 °. Here, the toner of the present invention includes toner particles and an external additive, and at least one of the external additives as the at least one external additive has a volume average particle diameter of 80 subjected to a hydrophobic treatment. It is preferable to contain silica particles of ˜300 nm.
However, the toner of the present invention has a volume average particle diameter of 80 to 300 nm that is hydrophobized using toner particles having a volume average particle diameter of 4 to 12 μm and an alkyl-based silane coupling agent having an alkyl group having 10 or more carbon atoms. A large-diameter external additive composed of silica particles obtained by burning silicon tetrachloride in an oxyhydrogen flame, and a small-diameter external additive having a volume average particle diameter of 5 to 20 nm. Is adopted.

  The toner of the present invention has the above-described configuration, has a high charge amount, is excellent in charging environment dependency, charging stability with time, and toner admixability. Excellent transferability. This is presumed to be due to the following reason.

  Development and transfer are affected by the uniform developer transport, current during transfer, etc., but basically the toner particles are pulled away from the binding force of the carrier carrying the toner particles, and the object (latent image carrier) Since it is a process of adhering to the body or transfer material, it depends on the balance between the electrostatic attraction and the adhesion between the toner particles and the charging member or the adhesion between the toner particles and the latent image carrier. Control of this balance is very difficult, but this process directly affects the image quality, and if efficiency is improved, it is expected to improve reliability and save labor by cleaning less, etc. Transferability is required. Development / transfer occurs when F electrostatic attraction> F adhesion.

  Therefore, in order to improve the efficiency of development / transfer, it is sufficient to increase the electrostatic attractive force (increase the development / transfer force) or to reduce the adhesion force. When the transfer electric field is increased, secondary toner is easily generated, such as generation of reverse polarity toner. For this reason, it is more effective to reduce the adhesive force.

Examples of the adhesion force include van der Waals force (non-electrostatic adhesion force) and mirror image force due to charges of colored particles. There is a level difference of almost one order between the two, which can be interpreted as being almost discussed by van der Waals forces. Van der Waals force F between spherical particles is expressed by the following equation:
_{Formula: F = H · r 1 ·} r 2/6 (r 1 + r 2) · a 2
(H: constant, r ₁ , r ₂ : radius of contacting particles (nm), a: distance between particles (nm))
In order to reduce the adhesive force, a fine powder having a radius r (r ₁ , r ₂ ) that is extremely smaller than that of the toner is interposed between the colored particles and the surface of the latent image carrier or the surface of the charge imparting member. In order to maintain the effect stably, it is effective to use silica particles with a volume average particle diameter of 80 to 300 nm.

  Further, when a large particle size external additive is added to the toner like the silica particles, the charging effect of the large particle size external additive is also increased. In order to stabilize the chargeability of the toner, it is necessary to make a difference in charge level between high temperature and high humidity and low temperature and low humidity, and charge stability (admixability) when adding toner is necessary. This can be achieved by using the applied silica particles.

  This is because the hydrophobization treatment contributes to the improvement of the environmental stability of the charging because the contact charging greatly affects the properties in the vicinity of the contact surface, and also serves as a catalytic agent that mediates the exchange of charges in the contact charging between the toner and the carrier. It is thought to play a role.

  In addition, the degree of hydrophobicity of silica particles increases and the level of charge at high temperatures and high humidity increases, as well as the widening of the charge distribution and poor admixing properties that are characteristic of silica particles are prevented by the effect of hydrophobic treatment. can do.

  In addition to the above, stable fluidity and developability / transferability can be obtained by setting the basic fluidity energy amount of toner (toner particles having an external additive attached) to 300 mJ or less.

  As described above, the toner of the present invention has a high charge amount, is excellent in charging environment dependency, charging stability with time, and toner admixability, and is also excellent in toner fluidity and development / transfer properties. It will be.

  Here, the amount of fluidity energy will be described. The fluidity energy amount is the fluidity energy amount obtained by fluidity measurement with a powder rheometer.

  When measuring the fluidity of particles, it is more influenced by many factors than when measuring the fluidity of liquids, solids, or gases. It is difficult to specify the exact fluidity of the particles. In addition, even if a factor to be measured (for example, particle size) is determined to specify fluidity, the factor actually has little effect on fluidity or only in combination with other factors. The significance of measuring the factor may arise, and even determining the measurement factor is difficult.

  Furthermore, the fluidity of the powder varies significantly depending on external environmental factors. For example, in the case of a liquid, even if the measurement environment changes, the fluctuation range of the fluidity is not so large, but the fluidity of the particles is greatly influenced by external environmental factors such as humidity and the state of the flowing gas. fluctuate. It is not clear which measurement factors are affected by these external environmental factors, so even if measured under strict measurement conditions, the reproducibility of the measured values obtained is actually poor. is there.

  In addition, the flowability when the developer (toner) is filled in the development tank has been taken as an index of repose angle and bulk density, but these physical property values are indirect to the flowability of the developer. In other words, it is difficult to quantify and manage the flowability of the developer.

  However, since the powder rheometer can measure the amount of fluid energy applied from the toner to the rotating blades of the measuring machine, the powder rheometer can be obtained as a sum of the factors attributable to fluidity. Therefore, in the powder rheometer, as in the past, for the toner obtained by adjusting the physical property value and particle size distribution of the surface, determine the items to be measured and find the optimum physical property value for each item and measure it. The flowability can be measured directly.

  As a result, it is possible to determine whether it is suitable as a toner used for developing an electrostatic image only by confirming whether it falls within the above numerical range with a powder rheometer. Such toner production management is a method that is extremely suitable for practical use as compared to the conventional method of managing by indirect values with respect to keeping the toner fluidity constant. Moreover, it is easy to make measurement conditions constant, and the reproducibility of measured values is high.

  That is, the method for specifying the fluidity by the value obtained by the powder rheometer is simple, accurate and highly reliable as compared with the conventional method.

Next, a method for measuring fluidity using a powder rheometer will be described.
The powder rheometer is a fluidity measuring device that directly measures fluidity by simultaneously measuring rotational torque and vertical load obtained by rotating a rotating blade spirally in packed particles. By measuring both the rotational torque and the vertical load, the fluidity including the characteristics of the powder itself and the influence of the external environment can be detected with high sensitivity. In addition, since the measurement is performed with the particle filling state kept constant, data with good reproducibility can be obtained.

  Measurement is performed using FT4 manufactured by freeman technology as a powder rheometer. In addition, in order to eliminate the influence of temperature and humidity before the measurement, toner that has been allowed to stand for 8 hours at a temperature of 22 ° C. and a humidity of 50% RH is used.

  First, a toner container is filled with an amount of toner exceeding a height of 89 mm in a split container having an inner diameter of 50 mm (a cylinder having a height of 51 mm placed on a 160 mL container having a height of 89 mm so that it can be separated vertically).

  After the toner is filled, the sample is homogenized by gently stirring the filled toner. This operation will be called conditioning in the following.

  During conditioning, the rotor blades are gently agitated in a rotating direction that does not receive any resistance from the toner so as not to stress the toner in the filled state, thereby removing most of the excess air and partial stress, making the sample almost homogeneous To make sure Specific conditioning conditions are agitation at a tip angle of 60 mm / sec with an approach angle of 5 °.

  At this time, the propeller-type rotor blades move downward simultaneously with the rotation, so that the tip draws a spiral, and the angle of the spiral path drawn by the propeller tip at this time is called the entry angle.

  After repeating the conditioning operation four times, the container upper end of the split container is gently moved, and the carrier inside the vessel is worn at a position of 89 mm in height to obtain a carrier that fills the 160 mL container. The conditioning operation is performed because it is important to always obtain a powder having a constant volume in order to obtain the fluid energy amount stably.

  The toner thus obtained is transferred to a 200 mL container having an inner diameter of 50 mm and a height of 140 mm. After the toner was transferred to the 200 mL container, this operation was further performed 5 times, and then the tip speed of the rotor blades was 50 mm / mm while moving in the container from a height of 110 mm to 10 mm from the bottom surface at an entrance angle of -10 °. Measure the rotational torque and vertical load when rotating in sec. The direction of rotation of the propeller at this time is the reverse direction to the conditioning (clockwise as viewed from above).

The relationship between the rotational torque or the vertical load with respect to the height H from the bottom surface is shown in FIGS. FIG. 2 shows the energy gradient (mJ / mm) with respect to the height H obtained from the rotational torque and the vertical load. The area obtained by integrating the energy gradient in FIG. 2 (shaded area in FIG. 2) is the fluid energy amount (mJ). The flow energy amount is obtained by integrating the section from 10 mm to 110 mm in height from the bottom.
Moreover, in order to reduce the influence by an error, let the average value obtained by performing this conditioning and energy measurement operation cycle 5 times be a fluid energy amount (mJ).

  The rotor blade has a diameter of 48 mm of a two-blade propeller type shown in FIG. 3 manufactured by freeman technology.

  Then, when measuring the rotational torque and vertical load of the rotor blades, the amount of fluidity energy measured at a ventilation flow rate of 0 ml / min without being vented from the bottom of the container is the “basic fluidity energy amount”. The amount of fluid energy measured while flowing air at a predetermined aeration flow rate from the bottom of the container is referred to as “aeration fluid energy amount”. In the FT4 manufactured by freeman technology, the inflow state of the air flow rate is controlled.

  In order to make the amount of fluid energy of the developer (toner) measured within the above conditions within the above range, for example, the shape of the toner particles, the amount of wax, the particle size distribution, the type of external additive (the (Including characteristics) and a method of adjusting the addition amount, and a combination of these methods is also suitable.

  Hereinafter, each composition and physical properties of the toner will be described.

The toner of the present invention includes toner particles and an external additive. The toner particles include at least a binder resin, a colorant, and a release agent.

  As described above, the toner of the present invention needs to have a basic fluid energy amount of 300 mJ or less, preferably 20 to 200 mJ, and more preferably 50 to 150 mJ. When the basic fluidity energy amount is larger than 300 mJ, toner clogging occurs due to the deterioration of the dispensing property, and the development / transferability is adversely affected. On the other hand, if the basic fluidity energy amount is too small, the toner fluidity is too good, and the toner may flow out more than necessary when the toner is replenished, or an admix failure in the developing machine may occur. This is not preferable.

[Binder resin]
As the binder resin contained in the toner particles, a known resin that can be used for the toner particles can be appropriately selected. Specifically, for example, styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate, acrylic acid Esters of α-methylene aliphatic monocarboxylic acids such as methyl, ethyl acrylate, butyl acrylate, octyl acrylate, dodecyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate , Homopolymers and copolymers of vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, etc. Examples of typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene. Mention may be made of maleic anhydride copolymers, polyethylene, polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, and modified rosin.
Among these, styrene- (meth) acrylic acid ester copolymer resins and polyester resins are preferably used.

The molecular weight of the binder resin varies depending on the type of resin, but the weight average molecular weight Mw is preferably 10,000 to 500,000, more preferably 15,000 to 300,000, and 20,000. More preferably, it is -200,000. The number average molecular weight Mn is preferably 2,000 to 30,000, more preferably 2,500 to 20,000, and still more preferably 3,000 to 15,000.
The values of the weight average molecular weight and the number average molecular weight are those measured using gel permeation chromatography (GPC). GPC uses HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation), and column uses two TSKgel and SuperHM-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15 cm). THF (tetrahydrofuran) is used. As experimental conditions, the sample concentration is 0.5 mass%, the flow rate is 0.6 ml / min, the sample injection amount is 10 μl, the measurement temperature is 40 ° C., and an IR detector is used.

  The glass transition temperature of the binder resin is preferably 40 ° C. to 80 ° C., and preferably 45 ° C. to 75 ° C. from the viewpoints of preventing deterioration of fluidity in a high temperature environment and achieving low temperature fixability. More preferred.

  The glass transition point (Tg) refers to a value obtained by measurement under a temperature rising rate of 10 ° C./min using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-50). The glass transition point is the temperature at the intersection of the extension line of the base line and the rising line in the endothermic part.

[Colorant]
There is no restriction | limiting in particular as a coloring agent contained in a toner particle, The coloring agent known per se can be mentioned, According to the objective, it can select suitably. Examples of the colorant include carbon black, lamp black, Dupont Oil Red, Orient Oil Red, Rose Bengal, C.I. I. Pigment Red 5, 112, 123, 139, 144, 149, 166, 177, 178, 222, 48: 1, 48: 2, 48: 3, 53: 1, 57: 1, 81: 1, C.I. I. Pigment orange 31, 43, quinoline yellow, chrome yellow, C.I. I. Pigment Yellow 12, 14, 17, 93, 94, 97, 138, 174, 180, 188, ultramarine blue, aniline blue, calcoyl blue, methylene blue chloride, copper phthalocyanine, C.I. I. Pigment Blue 15, 60, 15: 1, 15: 2, 15: 3, C.I. I. Pigment Green 7 and malachite green oxalate, nigrosine dye, and the like can be used, and these can be used alone or in combination. These may have been subjected to flashing dispersion processing in advance.

Moreover, magnetic powder can also be used as a coloring agent. Examples of the magnetic powder include known magnetic materials, for example, metals such as iron, cobalt, nickel and alloys thereof, metal oxides such as Fe ₃ O ₄ , γ-Fe ₂ O ₃ , cobalt-added iron oxide, MnZn ferrite, Various ferrites such as NiZn ferrite, magnetite, hematite and other powders can be used, and the surface thereof is treated with a surface treatment agent such as a silane coupling agent or titanate coupling agent, and inorganic compounds such as silicon compounds and aluminum compounds Those coated with a system material or those coated with a polymer may be used.

  The colorant is preferably added in the range of 3% by mass to 15% by mass and more preferably in the range of 4% by mass to 10% by mass with respect to the toner particles. However, when magnetic powder is used as the colorant, it is preferably added in the range of 12% by mass to 48% by mass and more preferably in the range of 15% by mass to 40% by mass with respect to the toner particles. preferable. By appropriately selecting the type of the colorant, each color toner such as yellow toner, magenta toner, cyan toner, black toner, and green toner can be obtained.

(Release agent)
As the release agent contained in the toner particles, for example, paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, and the like can be used. Derivatives include oxides, polymers with vinyl monomers, graft modified products, and the like. In addition, alcohols, fatty acids, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides, and the like can be used.

  Specifically, hydrocarbon waxes such as low molecular weight polypropylene and low molecular weight polyethylene, microcrystalline wax, silicone resin, rosins, ester wax, rice wax, carnauba wax, Fischer-Tropsch wax, montan wax, candelilla wax, etc. Is mentioned.

  The ratio of the release agent is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 1 to 8% by mass with respect to the toner particles. If the content of the release agent is less than the above lower limit value, the toner release performance may deteriorate and offset may occur. On the other hand, if it exceeds the upper limit value, it tends to exist on the toner surface. In some cases, performance is deteriorated and external additives are embedded, which is not preferable.

[External additive]
As at least one external additive attached to the surface of the toner particles, at least one silica particle is used. The silica particles are hydrophobized silica particles having a volume average particle size of 80 to 300 nm.

  The volume average particle diameter of the silica particles is 80 to 300 nm, preferably 90 to 250 nm, more preferably 100 to 200 nm. If the volume average particle size is smaller than 80 nm, it tends to not work effectively to reduce non-electrostatic adhesion. In particular, due to stress in the developing machine, the toner is easily embedded in the toner, and the development and transfer improvement effects are significantly reduced. On the other hand, when the volume average particle size exceeds 300 nm, it tends to be detached from the toner particles, and does not work effectively for reducing non-electrostatic adhesion, and at the same time, easily moves to the contact member, causing problems such as charging inhibition and image quality defects. May be caused.

Here, the volume average particle size refers to the volume with respect to the divided particle size range (channel) using the particle size distribution obtained by measurement with a laser diffraction particle size distribution measuring device (LA-910, manufactured by Horiba, Ltd.). The cumulative distribution is drawn from the small particle size side, and the particle size that becomes 50% cumulative with respect to all external additives can be determined as the volume average particle size D _50p .

  Hydrophobizing agents can be used to hydrophobize silica particles. Specific hydrophobizing agents include alkyl coupling agents, silane coupling agents, titanate coupling agents, and aluminate coupling agents. Examples include coupling agents such as coupling agents and zirconium coupling agents, silicone oils, and polymer coating treatment agents.

  Among these, an alkyl coupling agent, particularly an alkyl coupling agent having an alkyl group having 10 or more carbon atoms (preferably 10 to 20 carbon atoms, more preferably 12 to 18 carbon atoms) is preferable.

  Alkyl coupling agents, especially alkyl coupling agents having an alkyl group having 10 or more carbon atoms, are particularly excellent in the environmental stability of the charge amount because the chargeability greatly affects the properties near the contact surface. The large-diameter particles coated with the catalyst have substantially the same function as the alkyl-based coupling agent itself, and the alkyl-based coupling agent acts as a catalyst that mediates charge exchange in contact charging between the toner and the carrier. Can play a role.

  Further, when a large particle size external additive coated with the alkyl coupling agent is used, the effect can be exhibited even with a small amount of the hydrophobizing agent present on the surface of the large particle size external additive. Furthermore, since the silica particles have higher hardness than the alkyl coupling agent, there is an advantage that it is difficult to remove the treatment agent from the particles.

  Further, by having an alkyl group having 10 or more carbon atoms, the degree of hydrophobicity of the silica particles is increased, and the charge level at high temperature and high humidity is increased. The poor mixability can be prevented by the effect of the treatment agent. When the number of carbon atoms is less than 10, these effects are not sufficient, and stable charging may not be obtained.

  Here, the hydrophobizing treatment method may be liquid phase treatment or gas phase treatment, and is not particularly limited. For example, in the liquid phase treatment, the alkyl coupling agent and silica particles are added to a solvent in which the alkyl coupling agent is soluble, and the mixture is stirred and mixed. Thereafter, the solvent is removed, followed by drying and grinding. The method of surface-treating by this is mentioned.

  As the gas phase treatment, a solvent in which the alkyl coupling agent is dissolved is sprayed onto the suspended particles, adsorbed on the surface and dried, and the alkyl coupling agent and silica particles are mixed. Thereafter, there is a mechanical method in which the alkyl coupling agent is stretched and fixed to the surface of the particles to be treated by applying mechanical shear stress. In the liquid phase treatment or spray drying method, the generation of aggregated particles is unavoidable, and since a large amount of solvent is used, the mechanical method is preferable in consideration of the environment.

  Silica particles have a basic fluidity energy of 40 to 100 mJ when measured with a powder rheometer under conditions of an aeration flow rate of 0 ml / min, a tip speed of the rotor blade of 50 mm / sec, and an entrance angle of the rotor blade of -10 °. Is preferable, More preferably, it is 45-90 mJ, More preferably, it is 50-80 mJ. The basic fluidity energy amount is as described above.

  Here, the external additive having a large particle size is weak in adhesion to the toner, and shifts to a contact member, resulting in a decrease in transferability. In order to maintain stable chargeability and transferability over a long period of time, the large-diameter external additive must adhere to the toner surface without being detached or buried. In addition, when the toner and the external additive are blended, the fluidity of the external additive becomes an important factor.

  That is, if the fluidity of the external additive is too good, it exists in a floating state without being mixed with the toner and cannot adhere to the toner surface. On the other hand, even if the flowability of the external additive is too bad, the external additive is present in an aggregated state, and the aggregate is present on the toner surface as it is, or it is not preferable because it is unevenly adhered. Even if the blend share is strengthened to break up the aggregation of the external additive and disperse it uniformly on the toner surface, the external additive is buried in the toner or the toner deteriorates. To do.

  Thus, by using silica particles whose basic fluidity energy measured by a powder rheometer is in the above range, it is possible to achieve uniform adhesion to toner particles without desorption / embedding.

  For this reason, as described above, when the basic fluidity energy amount is less than 40 mJ, the silica particles may not be mixed with the toner particles during the blending, and may not float on the toner surface. . On the other hand, when the basic fluidity energy amount is larger than 100 mJ, the silica particles may be present in an aggregated state, and may be unevenly distributed on the surface of the toner particles or may remain in an aggregated state.

  In addition, the silica particle whose basic fluid energy amount measured by a powder rheometer is 40 to 100 mJ can be obtained, for example, by further heating and pressurizing a silica particle produced by a known method. Specifically, it can be realized by storing silica particles in a chamber under high temperature and high humidity for a certain period of time and then pressurizing them with a compression molding machine. Moreover, it becomes possible to satisfy | fill the prescribed | regulated basic fluidity energy amount by adjusting the conditions of a heating and pressurization with a silica particle.

  Further, since the silica particles are not completely hardened by pressure molding, they exist as powders, and the fluidity of the external additive is actually lowered by changing the apparent density. Compared with the aggregates generated in the surface treatment process of silica particles, the aggregates newly generated by the heat and pressure treatment have a weak binding force, so the dispersibility on the toner particle surface does not deteriorate. It can be more easily loosened during blending. In short, when blending with toner particles, silica particles that tend to float are suppressed to improve the mixing with the toner particles, and it becomes possible to uniformly adhere to the surface of the toner particles by the share at the time of blending. .

  As an external additive, in addition to the above silica particles, any of other inorganic particles and organic particles may be used in order to control transferability, fluidity, cleaning properties, chargeability controllability, particularly fluidity energy amount. Can do.

  Examples of inorganic particles include aluminum oxide, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, cerium chloride, and bengara. And metal oxides such as chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, magnesium carbonate, zirconium oxide, silicon carbide, silicon nitride, calcium carbonate, and barium sulfate, and ceramic particles.

  Examples of the organic particles include vinyl polymers such as styrene polymers, (meth) acrylic polymers, and ethylene polymers, and various polymers such as ester, melamine, amide, and allyl phthalate. Fluoropolymers such as vinylidene fluoride and particles made of higher alcohols such as unilin.

  In addition, for example, if the external additive having a large particle size (for example, volume average particle size of 80 to 300 nm) and the external additive having a small particle size (for example, volume average particle size of 5 to 20 nm) are not combined, the particle size is different. By using more than one type of external additive, fine irregularities on the surface of the toner particles are controlled, and the adhesion between the toner particles and the ease of rolling of the toner particles are adjusted, thereby reducing the fluid energy amount in the powder rheometer. It can control suitably. Further, for example, by preparing the toner by adding inorganic particles having a large particle size prior to the inorganic particles having a small particle size, the small particle size inorganic particles coat the toner particle surface, and at the same time, outside the large particle size. By coating the surface of the additive, fine unevenness on the outermost surface of the toner can be controlled, and thereby desired fluidity can be secured.

  The amount of the external additive used as a whole is preferably 0.5% by mass to 10% by mass, more preferably 0.6% by mass to 8% by mass, and 0.8% with respect to the toner particles. It is still more preferable that it is mass%-6 mass%.

[Other additives]
In addition to the above composition, known materials used for developers can be added as appropriate to the toner of the present invention. For example, an internal additive, a charge control agent, an inorganic particle, an organic particle, a lubricant, an abrasive and the like can be mentioned.

Examples of the internal additive include metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys, and magnetic materials such as compounds containing these metals.
Examples of the charge control agent include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments. In addition, as the charge control agent in the present invention, a material that is difficult to dissolve in water is preferable in terms of controlling ionic strength that affects stability during aggregation and fusion and reducing wastewater contamination.
Examples of the inorganic particles include all particles usually used as an external additive on the toner surface, such as silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate, and cerium oxide. Examples of the organic particles include all particles usually used as external additives on the toner surface, such as vinyl resins, polyester resins, and silicone resins. These inorganic particles and organic particles can be used as fluidity aids, cleaning aids, etc. Examples of lubricants include fatty acid amides such as ethylene bisstearyl amide and oleic acid amide, and stearic acid. Examples include fatty acid metal salts such as zinc and calcium stearate. Examples of the abrasive include the aforementioned silica, alumina, cerium oxide, and the like.

[Production method]
The toner of the present invention can be obtained by attaching or fixing the external additive to the surface of the toner particle by applying a mechanical impact force between the toner particle and the external additive using a sample mill or a Henschel mixer.

  The toner particles can be produced according to a known production method. There is no restriction | limiting in particular as said manufacturing method, According to the objective, it can determine suitably.

  For example, after pre-mixing a binder resin, a colorant, a release agent, and a charge control agent, if desired, melt-kneading in a kneader, pulverizing after cooling, and vibration sieving machine or wind sieving machine as described above Etc., and can be produced using a kneading and pulverizing method. Further, it can be produced by a wet spheronization method, a suspension granulation method, a suspension polymerization method, an emulsion polymerization aggregation method or the like.

[Physical properties]
(Volume average particle diameter of toner particles)
The volume average particle size of the toner particles is preferably 4 μm to 12 μm, more preferably 4.5 μm to 10 μm, and still more preferably 5 μm to 9 μm. When the volume average particle size of the toner particles is less than 4 μm, the fluidity is remarkably lowered, so that the developer layer is not sufficiently formed by the layer regulating member or the like, and the image may be fogged or dirtied. On the other hand, if it exceeds 12 μm, the resolution is lowered and a high-quality image may not be obtained, or the charge amount per developer unit weight is lowered, and the layer formation maintenance property of the developer layer is lowered, Fog and dirt may occur in the image.

As a method for measuring the volume average particle diameter of the toner particles, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% by weight aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant, and this is added to the electrolytic solution. Added in 100-150 ml. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute. Using the Coulter Multisizer II type, an aperture having an aperture diameter of 100 μm is used, and the particle diameter is 2.0 to 60 μm. The particle size distribution of the particles in the range is measured. The number of particles to be measured is 50,000.
For the particle size range (channel) obtained by dividing the obtained particle size distribution, the volume cumulative distribution is subtracted from the small particle size side, and the particle size that becomes 50% cumulative is _defined as the volume average particle size D _50v .

(Particle size distribution of toner particles)
The preferred particle size distribution of the toner particles is when the proportion of toner particles having a particle size of 4 μm or less is 45% by number or less, more preferably 40% by number or less, and even more preferably 35% by number or less.
Similarly to the determination of the volume average particle size D _50v , the particle size that becomes 84% cumulative when the volume cumulative distribution is subtracted from the small particle size side is D _84v, and the number cumulative distribution is calculated from the small particle size side. It is preferable that D _84v / D _50v is 1.35 or less, where D _{16p is} the particle size that is 16% cumulative when subtracted, and D _50p (number average particle size) is the particle size that is 50%. More preferably, it is 30 or less. _It is preferable that D 50p _{/ D 16p} is 1.45 or less, more preferably 1.40 or less.

  In order to obtain toner particles having such a particle size distribution, the toner particle size can be adjusted to a desired particle size distribution by using a gravity classifier, a centrifugal classifier, an inertia classifier, or a sieve.

  When the particle size distribution of the toner particles is wider than the above range, the fluid energy amount by the powder rheometer described above tends to be out of the specified range.

The particle size distribution of the toner particles is obtained by subtracting the volume cumulative distribution from the small particle size side with respect to the particle size range (channel) obtained by dividing the particle size distribution obtained by the same method as the measurement of the volume average particle size. When the particle size of 84% is _D84v , the cumulative number distribution is subtracted from the small particle size side, the particle size of 50% is _D50p , and the particle size of 16% is _D16p. the particle size distribution index and the volume average particle diameter _{D 84v} / volume average particle diameter _{D 50v,} refers to a value obtained fine powder side particle size distribution index as the number average particle diameter _{D 50p} / number average particle diameter _{D 16p.}

(Toner particle shape factor)
The shape of the toner particles is preferably controlled in order to obtain the fluid energy amount according to the present invention. The shape factor SF1 of the toner particles represented by the following formula is preferably 135 or less, and more preferably 130 or less.

Formula: SF1 = (ML ² / A) × (π / 4) × 100
In the above formula, ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.
The toner shape factor SF1 is obtained by taking toner particles dispersed on a slide glass or an optical microscope image of the toner into a Luzex image analysis device through a video camera, obtaining a maximum length and a projected area of 1000 or more toners, and using the above formula. It is obtained by calculating and obtaining the average value. SF1 is considered to be a true sphere as it approaches 100, and becomes larger as the numerical value increases.

  The toner particles having the above toner shape factor are subjected to heat treatment after pulverization and classification, treatment by mechanical impact force, etc. to control the spheroidization of the toner shape, or by applying a wet production method such as an emulsion aggregation method. Obtainable.

(Average circularity of toner particles)
The average circularity of the toner particles is preferably between 0.94 and 0.99. If it falls below the above range, the shape becomes indeterminate, and transferability, durability, fluidity and the like are lowered, which is not preferable. On the other hand, when the above range is exceeded, the ratio of the spherical particles increases and the cleaning property becomes difficult. A more preferable range of the average circularity is 0.95 to 0.98.

  Here, the average circularity is obtained by (circle equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projection area as the particle image) / (perimeter of the particle projection image)] A flow-type particle image analyzer (for example, manufactured by Sysmex Corporation) takes a particle image as a still image by instantly strobe light emission, and forms a very flat flow. FPIA-2100). The number of samplings when obtaining the average circularity is 3500.

  The toner of the present invention may be used as a so-called one-component developer that is used alone or as a two-component developer that is used in combination with a carrier.

<Image forming method>
The image forming method of the present invention comprises at least a charging step for charging an electrostatic latent image carrier, a latent image forming step for forming an electrostatic latent image on the surface of the charged electrostatic latent image carrier, and development including toner. A development step of developing the electrostatic latent image with an agent to form a toner image on the electrostatic latent image carrier, and a transfer step of transferring the toner image onto a recording medium to form an unfixed transfer image. And a fixing step of fixing the unfixed transferred image transferred onto the recording medium. And the toner of the said invention is applied as a toner.

  In the image forming method of the present invention, known techniques can be appropriately applied to the charging step, latent image forming step (exposure step), developing step, and transfer step. Further, in addition to these steps, a cleaning step for cleaning the electrostatic latent image carrier after the transfer step, a fixing step for fixing the transferred toner image on the recording material, and the like may be performed.

  Here, FIG. 4 shows a schematic configuration diagram of an image forming apparatus suitably applied to the image forming method of the present invention. An image forming apparatus 100 illustrated in FIG. 4 includes an electrophotographic photosensitive member 107, a charging device 108 that charges the electrophotographic photosensitive member 107, a power source 109 connected to the charging device 108, and an electrophotographic image that is charged by the charging device 108. An exposure device 110 that exposes the photosensitive member 107 to form an electrostatic latent image, a developing device 111 that develops the electrostatic latent image formed by the exposure device 110 with toner and forms a toner image, and a developing device 111 A transfer device 112 that transfers the formed toner image to the transfer medium 500, a cleaning device 113 that removes toner remaining on the electrophotographic photosensitive member 107 after transfer, a static eliminator 114, and a fixing device 115 are provided. .

  In the present invention, an image forming apparatus in which the static eliminator 114 is not provided may be used. In the image forming apparatus 100 of FIG. 4, the charging device 108 is a contact type charger, but may be a non-contact type charger.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In the text, “parts” means “parts by weight”.

<Measuring method of various characteristics>
First, methods for measuring physical properties of developers and the like used in Examples and Comparative Examples will be described.

-Volume average particle size, particle size distribution-
As described above, the particle size was measured using Coulter Multisizer II type (manufactured by Beckman-Coulter) and ISOTON-II (manufactured by Beckman-Coulter) as the electrolyte.

  As a measurement method, 0.5 to 50 mg of a measurement sample was added to 2 ml of a 5% by weight aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this was added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute. Using the Coulter Counter TA-II type, an aperture having an aperture diameter of 100 μm is used. The particle size distribution of particles in the range of 60 μm was measured. The number of particles to be measured was 50,000.

For the divided particle size range (channel), a cumulative distribution is drawn from the smaller diameter side for each of the volume and number, and the cumulative volume particle size that is 16% cumulative in volume is D _16v and cumulative 16 in number. % Cumulative particle diameter is defined as D _16p . Similarly, define a volume cumulative 50% become particle diameter Volume average particle diameter D _50v, the particle diameter at a cumulative 50% by number as number-average particle diameter D _50p. Similarly, the cumulative volume particle diameter _{D 84v} as a 84% cumulative volume, the cumulative number particle diameter at cumulative 84% by number is defined as _{D 84p.} The volume average particle diameter is the D _50v .
For the toner particles, the proportion of particles having a particle size of 4 μm or less was determined from the particle size distribution obtained above.

  On the other hand, when the particle diameter to be measured was less than 2 μm, the particle size was measured using a laser diffraction particle size distribution analyzer (LA-700: manufactured by Horiba, Ltd.). As a measurement method, a sample in a dispersion is adjusted to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained volume average particle diameter for each channel was accumulated from the smaller volume average particle diameter, and the volume average particle diameter was determined to be 50%.

-Measurement of molecular weight distribution-
The molecular weight distribution of the resin of the toner was performed under the following conditions.
Tosoh Corporation HLC-8120GPC, SC-8020 apparatus was used, TSK gei, SuperHM-H (6.0 mmID × 15 cm) was used as a column, and THF (tetrahydrofuran) was used as an eluent. As measurement conditions, the sample concentration was 0.5% by mass, the flow rate was 0.6 ml / min, the sample injection amount was 10 μl, the measurement temperature was 40 ° C., and the measurement was performed using an IR detector.
The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: A-500, F-1, F-10, F-80, F-380, A-2500, F-4, F-40, F-128. , F-700 was prepared from 10 samples. The data collection interval in the sample analysis was 300 ms.

-Measurement of glass transition temperature-
The glass transition point (Tg) of the binder resin was determined by measurement using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-50) under a temperature increase rate of 10 ° C./min. In addition, the glass transition point was made into the temperature of the intersection of the extended line of the base line in a heat absorption part, and a rising line.

-Measurement of weight average molecular weight-
Measurement was performed by the method described above.

[Example 1]
(Manufacture of toner)
-Manufacture of toner particles-
(Adjustment of resin particle dispersion)
-Styrene: 480 parts-n-butyl acrylate: 119 parts-Dodecanethiol: 9.4 parts-Decanediol diacrylate: 4.2 parts-Ion exchange water: 250 parts-Anionic surfactant: 12 parts

  The above components are mixed and dissolved to prepare a mixed solution A. On the other hand, 1 part by weight of an anionic surfactant (manufactured by Dow Chemical Co., Ltd., Dowfax) is dissolved in 550 parts by weight of ion-exchanged water, and 430 parts by weight of the mixed solution A Was added and dispersed and emulsified in the flask. Subsequently, 52 parts by weight of ion-exchanged water in which 9 parts by weight of ammonium persulfate was dissolved was charged, and the inside of the system was sufficiently replaced with nitrogen. Then, the system was heated with an oil bath to 70 ° C. while stirring the flask, The emulsion polymerization was continued for 2 hours.

  Further, a solution obtained by adding 5 parts by weight of dodecanethiol to 444.6 parts by weight of the mixed solution A and dispersing and emulsifying the solution is put into the system, and emulsion polymerization is performed at 70 ° C. for 3 hours. The center diameter of the particles is 178 nm, and the glass transition A resin particle dispersion having a point of 58.2 ° C., a weight average molecular weight of 38,000, and a solid content of 42% was obtained.

(Preparation of colorant particle dispersion)
Black pigment (Cabot, carbon part): 50 parts by weight Nonionic surfactant (Kao Corporation, Nonipol 400): 5 parts by weight Ion exchange water: 200 parts by weight

  The above components were mixed and dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA, Ultra Turrax) to obtain a colorant particle dispersion having a center diameter of 123 nm and a solid content of 21.5%.

(Preparation of release agent particle dispersion)
-Wax (Toyo Petrolite, polywax 725; melting point 98 ° C): 50 parts by weight-Cationic surfactant (Kao Corporation, Sanizol B50)): 5 parts by weight-Ion exchange water: 200 parts by weight

  The components were heated to 95 ° C. and sufficiently dispersed with a homogenizer (IKA, Ultra Tarrax T50), and then dispersed with a pressure discharge type homogenizer (Gorin homogenizer, Gorin), with a center diameter of 180 nm, solid A release agent particle dispersion having a content of 21.0% was obtained.

(Preparation of toner particles)
Resin particle dispersion: 278 parts by weight Colorant particle dispersion: 60 parts by weight Release agent particle dispersion: 88 parts by weight Polyaluminum chloride (10% aqueous solution): 3.6 parts by weight

  After thoroughly mixing and dispersing the above components in a round stainless steel flask with a homogenizer (IKA, Ultra Turrax T50), the flask was heated to 52 ° C. with stirring in an oil bath for heating, and then heated at 52 ° C. to 60 ° C. After maintaining for a minute, 137 parts by weight of the resin particle dispersion was added and gently stirred.

  Then, after adjusting the pH in the system to 6.5 with a 0.5 mol / liter sodium hydroxide aqueous solution, the stainless steel flask was sealed and heated to 95 ° C. while continuing to stir using a magnetic seal. Hold for 4 hours. After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then solid-liquid separated by Nutsche suction filtration. And it re-dispersed in 3 liters of ion exchange water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes.

  This washing operation was repeated 5 times, and solid-liquid separation was performed by Nutsche suction filtration using No5A filter paper, and then vacuum drying was continued for 12 hours to obtain toner particles.

  When the particle diameter of the toner particles was measured with a Coulter counter, the cumulative volume average particle diameter D50 was 6.4 μm.

(External toner adjustment)
Toner particles: 100 parts of rutile-type titanium oxide (volume average particle size 15 nm) 1.0 part and 2.0 parts of silica particles below are blended for 15 minutes at a peripheral speed of 30 m / s using a 5-liter Henschel mixer. Thereafter, coarse particles were removed using a sieve having an opening of 45 μm to prepare a toner. The basic fluid energy amount of this toner was 210 mJ.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. 100 parts of 90 nm silica particles obtained by burning purified silicon tetrachloride in an oxyhydrogen flame and 5 parts of decylsilane were dissolved in 500 parts of ethanol, mixed with stirring, and then the solvent ethanol was removed using an evaporator. And dried to obtain treated silica particles. Next, the treated product was crushed using an automatic mortar and sieved using a 105 μm mesh sieve to obtain silica particles.

  The obtained silica particles (decylsilane hydrophobized) had a basic fluidity energy of 65 mJ and a volume average particle size of 100 nm.

(Developer adjustment)
100 parts of the following carrier and 6 parts of externally added toner were stirred at 40 rpm for 20 minutes with a V-blender, and sieved with a sieve having an opening of 212 μm to prepare an electrophotographic developer.

-Fabrication of carrier-
17 parts of toluene, 3 parts of a styrene-methyl methacrylate copolymer (component ratio: 40/60), and 0.2 part of carbon black (R330: manufactured by Cabot) were mixed and stirred with a stirrer for 10 minutes. A solution for forming a coating layer in which was dispersed was prepared. Next, this coating solution and 100 parts of ferrite particles (volume average particle size: 45 μm) are put into a vacuum degassing type kneader and stirred at 60 ° C. for 30 minutes, and then degassed by further reducing pressure while heating. The carrier was prepared by drying. This carrier had a volume resistivity of 10 ¹⁴ Ωcm when an electric field of 1000 V / cm was applied.

[Example 2]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were prepared in the same manner as described in Example 1 except that 260 nm silica particles obtained by burning purified silicon tetrachloride in an oxyhydrogen flame were used.

  The obtained silica particles (n-decylsilane hydrophobized) had a basic fluidity energy of 75 mJ and a volume average particle size of 280 nm.

[Example 3]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were prepared in the same manner as described in Example 1 except that 75 nm silica particles obtained by burning purified silicon tetrachloride in an oxyhydrogen flame were used.

  The obtained silica particles (n-decylsilane hydrophobized) had a basic fluidity energy of 53 mJ and a volume average particle size of 85 nm.

[Example 4]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were produced in the same manner as described in Example 1 except that 5 parts of decylsilane was changed to 20 parts in the production of silica particles described in Example 1.

  The obtained silica particles (n-decylsilane hydrophobized) had a basic fluidity energy of 98 mJ and a volume average particle size of 100 nm.

[Example 5]
-Examples in which the basic flow energy amount of silica particles is close to 40-
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were produced in the same manner as described in Example 1 except that 5 parts of decylsilane were changed to 2 parts in the production of silica particles described in Example 1.

  The obtained silica particles (n-decylsilane hydrophobized) had a basic fluidity energy of 42 mJ and a volume average particle size of 100 nm.

[Example 6]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were prepared in the same manner as described in Example 1 except that 5 parts of decylsilane were changed to 5 parts of C16 silane in preparation of the silica particles described in Example 1.

  The obtained silica particles (C16 silane hydrophobized) had a basic fluidity energy of 90 mJ and a volume average particle size of 100 nm.

[Example 7]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were prepared in the same manner as described in Example 1 except that 5 parts of decylsilane was changed to 5 parts of C24 silane in preparation of the silica particles described in Example 1.

  The obtained silica particles (C24 silane hydrophobized) had a basic fluidity energy of 100 mJ and a volume average particle size of 100 nm.

[Comparative Example 1]
An external toner was prepared in the same manner as in Example 1 except that 2.0 parts of the following silica particles were blended for 15 minutes at a peripheral speed of 30 m / s using a 5-liter Henschel mixer. Obtained. The basic fluidity energy of the externally added toner was 350 mJ.

  Further, 100 parts of the carrier and 6 parts of the externally added toner were stirred with a V-blender at 40 rpm for 20 minutes, and sieved with a sieve having an opening of 212 μm to prepare an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were prepared in the same manner as described in Example 1 except that 5 parts of decylsilane were changed to 10 parts of silicone oil in the preparation of silica particles described in Example 1.

  The obtained silica particles (silicone oil hydrophobized) had a basic fluidity energy of 150 mJ and a volume average particle size of 100 nm.

[Comparative Example 2]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were prepared in the same manner as described in Example 1 except that 350 nm silica particles obtained by burning purified silicon tetrachloride in an oxyhydrogen flame were used.

  The obtained silica particles (decylsilane hydrophobized) had a basic fluidity energy of 125 mJ and a volume average particle size of 360 nm.

[Comparative Example 3]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were produced in the same manner as described in Example 1 except that 40 nm silica particles obtained by burning purified silicon tetrachloride in an oxyhydrogen flame were used.

  The obtained silica particles (decylsilane hydrophobized) had a basic fluidity energy of 35 mJ and a volume average particle size of 45 nm.

[Comparative Example 4]
-Comparative example in which the basic fluid energy of silica particles exceeded 100-
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the sol-gel method as follows. A silica sol obtained by the sol-gel method was treated with decylsilane, and dried and pulverized to obtain monodispersed spherical silica.

  The obtained silica particles (decylsilane hydrophobized) had a basic fluidity energy of 320 mJ and a volume average particle size of 100 nm.

[Comparative Example 5]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. The same method as described in Example 1, except that 12 nm silica particles obtained by burning purified silicon tetrachloride in an oxyhydrogen flame were used, and that 5 parts of decylsilane was changed to 10 parts of silicone oil. Silica particles were prepared.

  The obtained silica particles (silicone oil hydrophobized) had a basic fluid energy amount of 12 mJ and a volume average particle size of 15 nm.

[Comparative Example 6]
An external toner was prepared in the same manner as in Example 1 except that the following silica particles were used to obtain an electrophotographic developer.

-Production of silica particles-
Silica particles were produced by the vapor phase oxidation method as follows. Silica particles were prepared in the same manner as described in Example 1 except that 5 parts of decylsilane was changed to 5 parts of HMDS (hexamethyldisilazane) in the preparation of silica particles described in Example 1.

  The obtained silica particles (HMDS hydrophobized) had a basic fluidity energy of 26 mJ and a volume average particle size of 30 nm.

[Evaluation]
Using each of the developers described above, transferability was evaluated by DocuCenterColor400 (Fuji Xerox Co., Ltd.) by the following method.

-Toner charge measurement-
The developer on the surface of the sleeve (developer carrier) of the developing unit at the initial stage and after 10,000 sheets under low temperature and low humidity (temperature 10 degrees / humidity 15%) and high temperature and high humidity (temperature 30 degrees / humidity 85%) is 0. About 3 to 0.7 g was collected and measured by a blow-off method using a charge amount measuring device (TB200: manufactured by Toshiba Corporation).

-Evaluation of transferability at the initial stage and after 10,000 sheets-
Hard stop at the end of the transfer process under high temperature and high humidity (temperature 30 degrees / humidity 85%), transfer the toner weight on the two intermediate transfer members onto the tape in the same manner as above, measure the weight of the toner adhering tape, The transfer toner amount a was determined by averaging after subtracting the tape weight, the toner amount b remaining on the photoconductor was determined in the same manner, and the transfer efficiency was determined by the following equation.
Transfer efficiency η (%) = a × 100 / (a + b)
Preferable values were evaluated such that transfer efficiency η ≧ 99%, η ≧ 99% as ◯, 90% ≦ η <99% as Δ, and η <90% as ×.

-Toner powder characteristics-
2 g of the external toner was placed on a sieve having an opening of 75 μm, vibrated for 90 seconds with an amplitude of 1 mm, and judged based on the amount of powder remaining on the sieve. Specific evaluation criteria are as follows.
○: No toner remains on the screen Δ: Some toner remains on the screen ×: A considerable amount of toner remains on the screen

-Evaluation of developability at the initial stage and after 10,000 sheets-
Under high temperature and high humidity (temperature 30 degrees / humidity 85%), a solid patch of 5 cm × 2 cm is developed, and the developed toner image on the surface of the photoreceptor is transferred using the adhesiveness of the tape surface, and its mass (W1 ) Was measured.

[Development evaluation criteria]
・ ○: W1 is 4.0 g / m ² or more ・ Δ: W1 is 3.5 or more and less than 4.0 g / m ² *: W1 is less than 3.5 g / m ²

  Along with the above evaluation results, Table 1 and Table 2 collectively show the composition characteristics of the obtained developer (externally added toner).

  From the above results, this embodiment has a high charge amount, is excellent in charging environment dependency, charging stability over time and toner admixability, and further in toner fluidity and development / transferability. It turns out that it is excellent. In particular, by using a silica particle hydrophobized with an alkyl-based coupling agent having an alkyl group having 10 or more carbon atoms, or using silica particles having a predetermined basic fluidity energy amount as an external additive, charging properties can be obtained over a long period of time. -It turns out that it becomes the toner with the stable transferability.

It is a figure for demonstrating the measuring method of the fluid energy amount in a powder rheometer. It is a figure which shows the relationship between the vertical load and energy gradient which were obtained with the powder rheometer. It is a figure for demonstrating the shape of the rotary blade used with a powder rheometer. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus used in an image forming method of the present invention.

Explanation of symbols

100 Image Forming Device 107 Electrophotographic Photoreceptor 108 Charging Device (Charging Roll)
110 EXPOSURE DEVICE 111 DEVELOPING DEVICE
112 Transfer Device 115 Fixing Device (Fixing Roll)

Claims (3)

Silica particles having a volume average particle diameter of 80 to 300 nm and hydrophobized using toner particles having a volume average particle diameter of 4 to 12 μm and an alkyl-based silane coupling agent having an alkyl group having 10 or more carbon atoms. A large-diameter external additive composed of silica particles obtained by burning silicon in an oxyhydrogen flame, and a small-diameter external additive having a volume average particle diameter of 5 to 20 nm , and an aeration flow rate of 0 ml / min, A toner for developing an electrostatic latent image, characterized by having a basic fluidity energy of 300 mJ or less as measured by a powder rheometer under conditions of a tip speed of the rotor blade of 50 mm / sec and an entrance angle of the rotor blade of -10 ° .   The silica particles have a basic fluid energy amount of 40 to 100 mJ when measured with a powder rheometer under conditions of an air flow rate of 0 ml / min, a tip speed of the rotor blade of 50 mm / sec, and an entrance angle of the rotor blade of -10 °. The toner for developing an electrostatic latent image according to claim 1. A charging step for charging the electrostatic latent image carrier;
A latent image forming step of forming an electrostatic latent image on the surface of the charged electrostatic latent image carrier;
A developing step of forming the developed toner image to said electrostatic latent image on the latent electrostatic image bearing member with a developer containing an electrostatic latent image developing toner according to claim 1 or 2,
A transfer step of transferring the toner image onto a recording medium to form an unfixed transfer image;
A fixing step of fixing the unfixed transfer image transferred onto the recording medium;
An image forming method comprising:

Images