JP7175648B2 - toner - Google Patents

Description

The present invention relates to toners used in image forming methods such as electrophotography.

Electrophotographic image forming apparatuses are required to be faster, have a longer life, and save energy. Toners in particular are required to have further improved quality stability from the standpoint of longer life.

In order to meet such demands, attempts have been made to use fine alumina particles as an external additive.

Patent Documents 1 and 2 propose techniques for preventing filming on a photosensitive drum by specifying the shape and particle size distribution of alumina.

Japanese Patent Application Laid-Open No. 2002-200003 proposes a technique of preventing embedding in toner particles by specifying the purity of alumina and using amorphous fine alumina particles.

JP-A-10-326028 JP-A-2000-250251 JP 2007-17654 A

As a result of studies by the present inventors, it was found that embedding into the surface of toner particles still occurs when alumina fine particles, which have been conventionally used, are used. Since the alumina fine particles have a positive charging characteristic, the embedded toner exhibits a positive charging characteristic and acts as a microcarrier in the developer. As a result, when images are formed on a large number of sheets, some of the excessively charged toner may adhere firmly to the developing roller or the like, resulting in image defects.

SUMMARY OF THE INVENTION The present invention provides a toner that solves the above problems.

The present invention
A toner having toner particles containing a binder resin and a colorant and fine alumina particles,
The average projected area of the alumina fine particles on the toner surface is 0.17 μm ² or more and 0.30 μm ² or less, and the average value of the values obtained by dividing the peripheral length of the projected image of the alumina fine particles by the projected area is 7.5 or more. and
The toner is characterized in that the amount of alumina fine particles adhering to the polycarbonate thin film is 0.40 area % or more and 1.00 area % or less based on the area of the polycarbonate thin film in the polycarbonate thin film adhesion measurement method. Regarding.

According to the present invention, it is possible to provide a toner that can provide a stable image density even when used for a long period of time and can form an image in which fogging and streaks are well suppressed.

Schematic diagram showing the polycarbonate thin film adhesion measurement method

In the present invention, unless otherwise specified, the descriptions of "○○ or more and XX or less" and "○○ to XX", which represent numerical ranges, mean numerical ranges including the lower and upper limits that are endpoints.

The present inventors attempted to agglomerate the alumina fine particles in order to suppress the alumina fine particles from being embedded in the toner particle surfaces.

As a result, on the surface of the toner particles, the alumina fine particles
(1) The average projected area is 0.17 μm ² or more and 0.30 μm ² or less (2) The average value of the value obtained by dividing the peripheral length of the projected image by the projected area (= peripheral length / projected area) satisfies 7.5 or more It has been found that embedding in the toner particle surface is suppressed when present in a state. Further, when the above-mentioned requirements are satisfied, the alumina fine particles are appropriately retained on the surface of the toner particles, so that a good charge control effect and polishing effect can be obtained.

The average projected area is preferably 0.17 μm ² or more and 0.25 μm ² or less.

The fact that the average value of perimeter/projected area is 7.5 or more indicates that there are many irregularities on the surface of the aggregated alumina particles. Furthermore, since alumina is a harder material than silica or the like, it is easy to maintain an aggregated state and has good durability and stability. The presence of the unevenness facilitates the presence of the fine alumina particles on the surface of the toner particles in a stable manner, thereby suppressing the occurrence of charge-up caused by the migrated fine alumina particles. Migration refers to a phenomenon in which an external additive moves from a toner particle to another toner particle or another member. In other words, it means a phenomenon that the external additive does not remain on the toner particles. The average perimeter/projected area is preferably 7.5 or more and 11.0 or less, more preferably 7.5 or more and 10.0 or less, more preferably 7.5 or more and 9.0 or less. . The average value of perimeter/projected area can be controlled by the type and amount of alumina fine particles added.

In the toner of the present invention, the adhesion state of alumina fine particles is also important. In the present invention, the value measured by the later-described polycarbonate thin film adhesion measurement method was used as an indicator of the state of adhesion of fine alumina particles. The polycarbonate thin film adhesion measurement method uses a polycarbonate thin film as a member that substitutes for a photoreceptor, and is a measurement that simulates adhesion of fine alumina particles to a photoreceptor in an actual electrophotographic system.

In the toner of the present invention, the amount of alumina fine particles adhering to the polycarbonate thin film is 0.40 area % or more and 1.00 area % or less when the entire surface of the polycarbonate thin film is taken as 100 area % in the polycarbonate thin film adhesion measurement method. When the fine alumina particles are in such an adhering state, the charging of the toner is stabilized, and the occurrence of image defects can be suppressed. The amount of adhering alumina fine particles is determined by the amount of alumina fine particles added and the physical properties of the toner particles.

In addition, it is preferable that the alumina fine particles adhered by the following polycarbonate thin film adhesion measurement method show similar values with respect to the average projected area observed on the toner and the average value of perimeter/projected area. This indicates that the alumina fine particles observed on the toner surface behave with the observed size.

The details of the polycarbonate thin film adhesion measurement method are shown below.

<Polycarbonate thin film adhesion measurement method>
FIG. 1 shows each process of the polycarbonate thin film adhesion measurement method.

(1) The first diagram in FIG. 1 shows a method of arranging the toner T on the substrate 12 . As the substrate 12, in order to simulate the surface layer of the photoreceptor, a square aluminum sheet with a side of about 3 mm and a thickness of 50 μm was coated with polycarbonate (Iupilon Z-400, Mitsubishi Engineering-Plastics Co., Ltd., viscosity average molecular weight (Mv)). 40,000) is used. Specifically, the polycarbonate is dissolved in toluene to a concentration of 10% by mass to prepare a coating solution, and the coating solution is applied to the aluminum sheet using a No. 50 wire bar. Then, it is dried at 100° C. for 10 minutes to form a 10 μm-thick polycarbonate film on the aluminum sheet.

First, about 10 mg of toner is placed on a stainless steel mesh sieve 11 with an opening of 75 μm, and the sieve is placed at a position 20 mm above the substrate 12 placed on the substrate holder 13 . It is preferable to use a sieve with openings having a diameter of 10 mm so that the fallen toner is efficiently deposited on the substrate. Then, to the frame holding the sieve, a sawtooth vibration with an amplitude of 1 mm and a duty ratio of 33%, equivalent to an acceleration of 5 G, was applied at 5 Hz for 30 seconds in the in-plane direction of the sieve, thereby sifting the toner onto the substrate.

Next, a sawtooth wave vibration with an amplitude of 1 mm and a duty ratio of 33%, which corresponds to an acceleration of 0.5 G, is applied to the substrate on which the toner is deposited in the in-plane direction of the substrate at 3 Hz for 20 seconds to promote contact between the substrate and the toner. .

(2) The second view of FIG. 1 shows a method of removing toner on a substrate. After vibration is applied to the substrate, as a suction means 14, an elastomer suction port with an inner diameter of about 5 mm connected to the tip of the nozzle of a vacuum cleaner is brought close to the toner placement surface so as to remove the toner adhering to the substrate. The suction is performed at a suction pressure of 6 kPa while visually confirming the degree of remaining toner. By this operation, substrates with fine alumina particles adhered thereto are obtained as shown in the third and fourth figures.

(3) Observation and image measurement with a scanning electron microscope are used to quantify the amount and shape of fine alumina particles remaining on the substrate after toner removal.

First, a thin film of platinum is formed on the substrate from which the toner has been removed by sputtering (current of 20 mA, 60 seconds) to prepare an observation sample. Next, as a scanning electron microscope, Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Co., Ltd.) is used, and the backscattered electron image of S-4800 is observed. Although the observation magnification depends on the particle size of the alumina fine particles, for example, if the particles are about 100 nm, they can be observed under the conditions of 20,000 times, an acceleration voltage of 10 kV, and a working distance of 3 mm. The observation area at 20000 times is an area of about 30 μm×20 μm. The judgment as to whether or not the particles were fine alumina particles was made by composition analysis using EDAX.

In the image obtained by observation, the alumina fine particles are represented with high brightness and the substrate is represented with low brightness, so that the amount of alumina fine particles in the field of view can be quantified by binarization. The binarization conditions can be appropriately selected according to the observation device and sputtering conditions. For example, image analysis software Image J (developed by Wayne Rasband) can be used for binarization. In the example, the background luminance distribution was removed from the Subtract Background menu with a flattening radius of 40 pixels and then binarized with a luminance threshold of 50.

From the obtained binarized image, the particle analysis of image analysis software Image J was used to calculate the adhesion amount, projected area, and peripheral length of the alumina fine particles. Incidentally, the peripheral length of the fine alumina particles is calculated by tracing the contour of the aggregated particles as one particle from the binarized image of the aggregated alumina. The adhesion amount of alumina fine particles is the ratio of the area occupied by the alumina fine particles (area %) when the area of the observation region is 100%. The above measurement was performed on 100 binarized images, and the arithmetic average value was taken as the adhesion amount of alumina fine particles. Further, the average projected area of alumina fine particles and the average value of (peripheral length/projected area) are arithmetic mean values of 100 fine particles.

[Alumina fine particles]
Next, alumina fine particles will be described. There are no particular limitations as long as the above characteristics can be achieved. Alumina can be produced by the thermal decomposition method of ammonium aluminum carbonate, the gas phase oxidation method, the deflagration method, the Bayer method, the hydrolysis method of aluminum alkoxide, etc., using transition alumina or an alumina raw material that becomes transition alumina by heat treatment. manufactured. By transitional alumina is meant all aluminas having polymorphs represented as Al ₂ —O ₃ , other than the α form. Specific examples include γ-alumina, δ-alumina, θ-alumina, and the like.

The alumina raw material to be the transition alumina is subjected to a sintering step to obtain the target powdery α-alumina. A method for producing fine alumina particles in which a special gas atmosphere is used in addition to heat during firing is preferred.

The hydrolysis method of aluminum alkoxide is a method of synthesizing high-purity aluminum alkoxide from the reaction of metal aluminum and alcohol, hydrolyzing it to obtain alumina hydrate, and then calcining it to obtain high-purity alumina. is. In this method, the produced aluminum alkoxide can be purified by an operation such as distillation, and a highly pure aluminum alkoxide can be obtained. In addition, since the hydrolysis rate of aluminum alkoxide is very fast and it is easy to form fine alumina hydrate, it is important to control the conditions during hydrolysis and drying appropriately so as not to form strong agglomerated particles. is. Alumina other than α-Al ₂ O ₃ in the high-temperature stable phase is called transition alumina, and is ultrafine particles with primary particles of several tens of nanometers.

The above transition alumina or alumina raw material that becomes transition alumina by heat treatment is added to the atmosphere gas in an amount of 1% by volume or more, preferably 5% by volume or more, more preferably 10% by volume or more of hydrogen chloride gas with respect to the total volume of the atmosphere gas. and bake. Nitrogen, hydrogen, an inert gas such as argon, and air can be used as a diluent gas for the hydrogen chloride gas, which is the atmospheric gas. The pressure of the atmosphere gas containing hydrogen chloride gas is not particularly limited, and can be arbitrarily selected within the range of industrial use. By firing in such an atmospheric gas, the desired powdery α-alumina can be obtained at a relatively low firing temperature as described later.

A mixed gas of chlorine gas and water vapor can also be used instead of hydrogen chloride gas. Chlorine gas is 1% by volume or more, preferably 5% by volume or more, more preferably 10% by volume of the total volume of the atmosphere gas in the atmosphere gas in which chlorine gas and water vapor are introduced into the transition alumina or the alumina raw material that becomes the transition alumina by heat treatment. At least 0.1% by volume, preferably at least 1% by volume, and more preferably at least 5% by volume of water vapor are introduced and baked. Nitrogen, hydrogen, an inert gas such as argon, and air can be used as a diluent gas for chlorine gas and water vapor to be introduced. The pressure of the atmospheric gas containing chlorine gas and water vapor is not particularly limited, and can be arbitrarily selected within the range of industrial use. By firing in such an atmospheric gas, the desired powdery α-alumina can be obtained at a relatively low firing temperature as described later.

The firing temperature is 600°C or higher, preferably 600°C or higher and 1400°C or lower, more preferably 700°C or higher and 1300°C or lower, still more preferably 800°C or higher and 1200°C or lower. By controlling the temperature within this range for firing, it is easy to obtain particles in which the generated α-alumina particles are moderately agglomerated on the surface of the externally added toner at an industrially advantageous generation rate.

An appropriate firing time depends on the concentration of the atmospheric gas and the firing temperature and is not necessarily limited, but is preferably 1 minute or longer, more preferably 10 minutes or longer. Firing until the alumina raw material crystallizes into α-alumina is sufficient. The target α-alumina can be obtained in a shorter time than the firing time of conventional methods.

The supply source and supply method of the atmospheric gas are not particularly limited. It suffices if the atmosphere gas can be introduced into a reaction system in which a raw material such as transition alumina exists. For example, cylinder gas can typically be used as a source. When a hydrochloric acid solution, a chlorine compound such as ammonium chloride, or a chlorine-containing polymer compound is used as a raw material for chlorine gas or the like, it can be used by adjusting the vapor pressure or decomposition thereof to the predetermined gas composition described above. . When a decomposition gas such as ammonium chloride is used, the operation may be hindered due to deposition of solid substances in the kiln. In addition, the higher the hydrogen chloride gas concentration, the lower the temperature and the shorter the firing time, and the higher the purity of alumina can be obtained. It is preferable to As a gas supply method, either a continuous system or a batch system can be used.

The firing device is not necessarily limited, and a so-called firing furnace can be used. The firing furnace is desirably made of a material that is not corroded by hydrogen chloride gas, chlorine gas, etc., and is desirably equipped with a mechanism capable of adjusting the atmosphere. In addition, since acid gases such as hydrogen chloride gas and chlorine gas are used, it is preferable that the firing furnace be airtight. Industrially, it is preferable to carry out the firing in a continuous manner, and for example, a tunnel furnace, a rotary kiln, a pusher furnace, or the like can be used.

The purity of aluminum oxide in the fine alumina particles is preferably 99.99% or more and 100.00% or less. If the purity of aluminum oxide is less than 99.99%, the fine alumina particles tend to have irregular shapes.

It is preferable that the number average particle size of the primary particles of the alumina fine particles on the toner is 200 nm or more and 400 nm or less.

The volume resistivity of the fine alumina particles is preferably 1.0×10 ⁶ Ω·cm or more and 1.0×10 ¹² Ω·cm or less. If the volume resistivity of the fine alumina particles is within the above range, it is possible to satisfactorily suppress charge build-up without causing charge leakage. The volume resistivity can be controlled by surface-treating the fine alumina particles.

Alumina fine particles that are not surface-treated can be used, but if surface-treated, they are hydrophobized oil, coupling agent, and hydrophobized resin. Among these, silicone-based oils, coupling agents, organic acid-based resins, and the like are preferably used. Examples of oils that can be used include silicone oils such as dimethylpolysiloxane and methylhydrogenpolysiloxane, paraffin, and mineral oil.

The treatment amount is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the particles before treatment, and preferably 3 to 40 parts by mass for uniform treatment without coalescence of the particles.

A known manufacturing method can be used to treat the surface of alumina fine particles with these hydrophobizing agents. For example, it is possible to use a known method such as a method of spraying the treating agent while the fine alumina particles are in a fluidized state, or a method of dropping droplets onto the mechanically stirred alumina fine particles. Further, after the surface treatment, heat treatment may be performed for the purpose of accelerating the reaction or removing the solvent.

The content of the fine alumina particles is preferably 0.02 parts by mass or more and 1.50 parts by mass or less with respect to 100 parts by mass of the toner particles.

[Toner particles]
Methods for producing toner particles include, for example, a method for producing toner particles directly in an aqueous medium (hereinafter also referred to as a polymerization method) such as a suspension polymerization method, an interfacial polymerization method, or a dispersion polymerization method. Further, a pulverization method may be used, and the toner obtained by the pulverization method may be thermally spheroidized to adjust the average circularity.

Among them, the suspension polymerization method is preferable. The toner particles produced by the suspension polymerization method are preferable because the individual particles are almost spherical and the distribution of the charge amount is relatively uniform, so that the charging property is stable.

Incidentally, the average circularity of the toner particles is preferably 0.960 or more.

In the suspension polymerization method, a polymerizable monomer composition containing a polymerizable monomer capable of forming a binder resin, a colorant, wax, etc. is dispersed in an aqueous medium to form a polymerizable monomer composition. Toner particles are produced by forming particles of and polymerizing the polymerizable monomer in the particles.

The toner particles may be toner particles having a core portion and a shell portion on the surface of the core portion. By adopting a core-shell structure, it is possible to prevent defective charging caused by exudation of the core portion to the surface of the toner particles.

The shell preferably contains polyester, styrene-acrylic copolymer, or styrene-methacrylic copolymer, more preferably polyester.

The amount of the resin forming the shell is preferably 0.01 parts by mass or more and 20.0 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass with respect to 100 parts by mass of the resin forming the core. .0 parts by mass or less.

The weight average molecular weight of the polyester contained in the shell is preferably 5000 or more and 50000 or less. When the weight average molecular weight is within the above range, the chargeability of the toner is stable, which is more preferable.

Examples of polymerizable monomers capable of forming a binder resin include vinyl-based polymerizable monomers. Specifically, the following can be exemplified.

styrene; styrene derivatives such as α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, Acrylic polymerizable monomers such as iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate , n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate methacrylic polymerizable monomers; methylene aliphatic monocarboxylic acid esters; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, formic acid Vinyl esters such as vinyl can be mentioned.

The toner particles may contain charge control agents. Known charge control agents include those that control toner particles to be negatively charged and those that control toner particles to be positively charged. be able to.

The followings can be mentioned as means for controlling the toner particles to be negatively charged.

Organometallic complexes (monoazo metal complexes; acetylacetone metal complexes); metal complexes or metal salts of aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids; aromatic mono- and polycarboxylic acids and their metal salts, anhydrides and esters; bisphenols phenol derivatives such as These can be used singly or in combination of two or more.

Among these, a metal complex or a metal salt of an aromatic hydroxycarboxylic acid is preferred because of which stable charging performance can be obtained.

On the other hand, the followings can be mentioned as means for controlling the toner particles to be positively charged.

Modifications with nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogues thereof; onium salts such as phosphonium salts. and these lake pigments; triphenylmethane dyes and these lake pigments (as lake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid, ferrocyanic compounds, etc.); metal salts of higher fatty acids. These can be used singly or in combination of two or more.

Among these, nigrosine compounds and quaternary ammonium salts are preferred.

Since the fine alumina particles are positively chargeable, it is preferable to use a charge control agent that controls the toner particles to be negatively chargeable, since the electrostatic adhesion between the toner particles and the fine alumina particles increases.

The content of the charge control agent is preferably 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer capable of forming the binder resin or the binder resin.

It is also a preferred embodiment to use a charge control resin. When the toner particles contain the charge control resin, the negative chargeability of the toner particle surfaces is improved. As a result, the electrostatic adhesion to the positively chargeable alumina fine particles is increased, making it difficult for the alumina fine particles to adequately migrate from the toner particle surfaces. Furthermore, in long-term durable use, the presence of fine alumina particles exerts an effect of leaking charges, and charge-up is easily suppressed.

A polymer having a sulfonic acid functional group is preferable as the charge control resin. A polymer having a sulfonic acid functional group is a polymer having a sulfonic acid group, a sulfonate group, or a sulfonate ester group. Among these, polymers having sulfonic acid groups are preferred.

Specifically, a homopolymer of a monomer such as styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, methacrylsulfonic acid, or Copolymers of said monomer and other monomers are included. In addition, the sulfonic acid group of the polymer may be converted to a sulfonic acid group or esterified. The charge control resin preferably has a glass transition temperature (Tg) of 40° C. or higher and 90° C. or lower.

The content of the charge control resin is preferably 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer capable of forming the binder resin or the binder resin. In addition, the charge control resin can further improve the charging state of the toner particles when used in combination with a water-soluble polymerization initiator.

When A is the amount of carbon element present on the surface of the toner particles and E is the amount of sulfur element present on the surface, E/A, which is the ratio of E to A, is expressed by the following formula (1). is preferably satisfied, and more preferably the following formula (1)' is satisfied.

E/A can be adjusted, for example, by incorporating the charge control resin into the toner particles.

3×10 ⁻⁴ ≦E/A≦50×10 ⁻⁴ (1)
5×10 ⁻⁴ ≦E/A≦30×10 ⁻⁴ (1)′
Setting E/A within the above range tends to further increase the electrostatic adhesion between the toner particles and the alumina fine particles. Furthermore, since the alumina fine particles are also present on the toner surface, the alumina fine particles tend to be moderately difficult to migrate from the toner particle surface, thereby suppressing charge-up of the toner.

The toner particles may contain wax. Waxes include the following.

petroleum-based waxes and their derivatives such as paraffin wax, microcrystalline wax and petrolatum; montan wax and its derivatives; Fischer-Tropsch hydrocarbon waxes and their derivatives; polyolefin waxes and their derivatives such as polyethylene and polypropylene; Natural waxes such as candelilla wax and derivatives thereof; higher fatty alcohols; fatty acids such as stearic acid and palmitic acid; acid amide waxes; ester waxes.

Examples of derivatives include oxides, and block copolymers and graft-modified products with vinyl monomers.

The content of the wax is preferably 2.0 parts by mass or more and 15.0 parts by mass or less with respect to 100.0 parts by mass of the polymerizable monomer capable of forming the binder resin or the binder resin. It is more preferable that it is 0 mass part or more and 10.0 mass parts or less.

The toner particles may contain colorants.

Examples of black colorants include carbon black, magnetic substances, and those toned black using yellow, magenta, and cyan colorants shown below.

Yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 128, 129, 138, 147, 150, 151, 154, 155, 168, 180, 185, 214.

Magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.

Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 238, 254, 269, C.I. I. Pigment Violet 19 can be mentioned.

Cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, basic dye lake compounds.

Specifically, C.I. I. Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, 66.

The colorants can be used singly, mixed, or in the form of a solid solution.

The colorant may be selected from the viewpoint of hue angle, saturation, brightness, light resistance, OHP transparency, and dispersibility in toner particles.

The content of the colorant is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer capable of forming the binder resin or the binder resin.

The toner particles can be made into magnetic toner particles by containing a magnetic substance. Magnetic substances include iron oxides such as magnetite, hematite and ferrite; metals such as iron, cobalt and nickel, or these metals and aluminum, copper, magnesium, tin, zinc, beryllium, calcium, manganese, selenium, titanium, Alloys with metals such as tungsten, vanadium and mixtures thereof are included.

The magnetic material is preferably a magnetic material whose surface has been modified.

When a magnetic toner is prepared by a polymerization method, it is preferably subjected to hydrophobic treatment with a surface modifier, which is a substance that does not inhibit polymerization. Examples of such surface modifiers include silane coupling agents and titanium coupling agents.

The number average particle size of the magnetic material is preferably 2.0 μm or less, more preferably 0.1 μm or more and 0.5 μm or less.

The content of the magnetic substance is preferably 20 parts by mass or more and 200 parts by mass or less, more preferably 40 parts by mass or more and 150 parts by mass, with respect to 100 parts by mass of the polymerizable monomer capable of forming the binder resin or the binder resin. Part or less is more preferable.

On the other hand, an example of a manufacturing method for manufacturing toner particles by a pulverization method will be described below.

In the raw material mixing step, predetermined amounts of a binder resin, a coloring agent, a wax, and the like are weighed, blended, and mixed as materials constituting the toner particles.

Examples of the mixing device include a double-con mixer, V-type mixer, drum-type mixer, super mixer, FM mixer, Nauta mixer, and Mechanohybrid (manufactured by Nippon Coke Kogyo Co., Ltd.).

Next, the mixed materials are melt-kneaded to disperse the coloring agent and wax in the binder resin. In the melt-kneading step, a pressure kneader, a batch type kneader such as a Banbury mixer, or a continuous kneader can be used. A single-screw or twin-screw extruder is the mainstream because of its superiority in continuous production. For example, KTK type twin-screw extruder (manufactured by Kobe Steel, Ltd.), TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), PCM kneader (manufactured by Ikegai), twin-screw extruder (manufactured by KCK Corporation) , Co-Kneader (manufactured by Buss Co., Ltd.), and Kneedex (manufactured by Nippon Coke Industry Co., Ltd.). Further, the resin composition obtained by melt-kneading may be rolled with two rolls or the like and cooled with water or the like in the cooling step.

The resulting cooled product is then ground to the desired particle size in a grinding process.

In the pulverization step, for example, coarse pulverization is performed using a pulverizer such as a crusher, hammer mill, or feather mill. After that, it is preferable to finely pulverize with a Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), Turbo Mill (manufactured by Freund Turbo Co., Ltd.), or an air jet type fine pulverizer.

After that, if necessary, inertial classification method Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), centrifugal force classification method Turboplex (manufactured by Hosokawa Micron Corporation), TSP Separator (manufactured by Hosokawa Micron Corporation), Faculty (manufactured by Hosokawa Micron Corporation) The particles are classified using a classifier or a sieving machine to obtain toner particles.

Also, the toner particles may be spherical. For example, after pulverization, spheroidization is performed using a hybridization system (manufactured by Nara Machinery Works), a mechanofusion system (manufactured by Hosokawa Micron Corporation), a faculty (manufactured by Hosokawa Micron Corporation), or a Meteor Rainbow MR Type (manufactured by Nippon Pneumatic Industry Co., Ltd.). Good.

The toner of the present invention is obtained by externally adding alumina fine particles to toner particles, but the toner can be obtained by mixing other external additives as necessary. Mixers for mixing external additives include FM mixer (manufactured by Nippon Coke Kogyo Co., Ltd.), high-speed fluidization type mixer Super Mixer (manufactured by Kawata), Nobilta (manufactured by Hosokawa Micron), and Hybridizer (Nara manufactured by Kikaisha). In the external addition step, the fixed state of the fine alumina particles can be controlled by adjusting the rotational speed and time of the blade and by controlling the temperature of the toner during the external addition. Incidentally, the temperature of the toner can be adjusted by introducing hot water or the like into the jacket portion of the mixing tank.

Coarse particles may be sieved after mixing the external additive. Sieving devices used for this purpose include the following.

Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonator sieve, gyro shifter (manufactured by Tokuju Kosakusho); Vibra Sonic System (manufactured by Dalton); Sonic Clean (manufactured by Shinto Kogyo); ); Micro shifter (manufactured by Makino Sangyo Co., Ltd.).

The toner may contain an external additive other than the fine alumina particles. In particular, a fluidity improver may be added to improve the fluidity and chargeability of the toner.

As the fluidity improver, the following can be used.

Fluorine-based resin powder such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder; Silica fine particles such as wet-process silica or dry-process silica fine particles; Titanium oxide fine particles; Hydrophobizing fine particles surface-treated with a hydrophobizing agent such as oil; oxides such as zinc oxide and tin oxide; strontium titanate, barium titanate, calcium titanate, strontium zirconate and calcium zirconate double oxides; carbonate compounds such as calcium carbonate and magnesium carbonate;

Among these, dry-process silica fine particles, which are fine particles produced by vapor-phase oxidation of a silicon halogen compound and are called dry-process silica or fumed silica, are preferable. The dry process utilizes, for example, the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.

SiCl ₄ +2H ₂ +O ₂ →SiO ₂ +4HCl
In this production process, it is also possible to obtain composite fine particles of silica and other metal oxides by using other metal halide compounds such as aluminum chloride or titanium chloride together with silicon halide compounds, and silica fine particles also include them. do.

The number average particle diameter of the primary particles of the fluidity improver is preferably 5 nm or more and 30 nm or less, since high chargeability and fluidity can be imparted.

Further, the silica fine particles are more preferably hydrophobized silica fine particles surface-treated with the above hydrophobizing agent.

The fluidity improver preferably has a specific surface area of 30 m ² /g or more and 300 m ² /g or less by nitrogen adsorption measured by the BET method.

The total content of the fluidity improver is preferably 0.01 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the toner particles.

[Measurement method of each physical property]
Methods for measuring various physical properties of toner and other materials will be described below.

The physical properties of alumina fine particles are measured using a toner as a sample.

When the physical properties of the alumina fine particles and the toner particles are measured from the toner to which the alumina fine particles are externally added, the alumina fine particles and other external additives are preferably separated from the toner and measured as follows.

The toner is ultrasonically dispersed in methanol to remove alumina fine particles and other external additives, and allowed to stand still for 24 hours. The toner particles, the alumina microparticles and other external additives are separated and collected by centrifugation and sufficiently dried to isolate the toner particles and the alumina microparticles.

<Method for Measuring Average Projected Area and Circumference/Projected Area of Alumina Fine Particles on Toner Surface>
The toner surface is observed using a Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Co., Ltd.), and a backscattered electron image is observed. Although the observation magnification depends on the particle size of the alumina fine particles, for example, if the particles are about 100 nm, they can be observed under the conditions of 20,000 times, an acceleration voltage of 10 kV, and a working distance of 3 mm. The observation area at 20000 times is an area of about 30 μm×20 μm. The judgment as to whether or not the particles were fine alumina particles was made by composition analysis using EDAX.

As observation conditions, the magnification is appropriately adjusted to 100,000 to 200,000 times depending on the size of the external additive. In addition, in order to perform image processing on the inorganic fine particles, the acceleration voltage during observation is adjusted to a high value (for example, 10 kV), and observation is performed using a backscattered electron image, whereby the brightness of the inorganic fine particles is high and the brightness of the toner particle surface is low. preferred because it is represented

In the image obtained by observation, the alumina fine particles are represented with high brightness and the toner particle surfaces are represented with low brightness, so that the alumina fine particles within the field of view can be extracted by binarization. The binarization conditions can be appropriately selected according to the observation device and sputtering conditions. For example, image analysis software Image J (developed by Wayne Rasband) can be used for binarization. In the example, the background luminance distribution was removed from the Subtract Background menu with a flattening radius of 40 pixels and then binarized with a luminance threshold of 50.

From the obtained binarized image, the projected area and perimeter of the alumina fine particles were calculated using particle analysis using image analysis software Image J. The average projected area of alumina fine particles and the average value of (peripheral length/projected area) are arithmetic mean values of 100 fine particles.

<Method for measuring purity of alumina fine particles>
Specific examples of devices for measuring the purity of alumina fine particles include ICP emission spectrometry, AES, and SIMS, which are highly sensitive and capable of quantifying impurity levels. The amount of impurities in the fine alumina particles in this example was measured by ICP emission spectrometry. As a more specific device, Vista-PRO manufactured by Seiko Instruments Inc. was used. The measurement was performed for each metal oxide according to the following JIS standard measurement method.
・Fe ₂ O ₃ (%): sodium carbonate-boric acid melting, 0-phenanthroline absorption photometry (JIS H 1901)
・SiO ₂ (%): sodium carbonate-boric acid melting, molybdenum blue spectrophotometry (JIS H 1901)
・Na ₂ O (%): boric acid welding extraction - flame photometry (JIS H 1901)
Further, the purity of the alumina fine particles was calculated from the following formula. It is defined as a value rounded to the third decimal place.

Purity of alumina fine particles [Al ₂ O ₃ (%)]=
100 (%)-[Fe ₂ O ₃ (%)]-[SiO ₂ (%)]-[Na ₂ O (%)]
<Method for measuring volume resistivity of fine alumina particles>
The volume resistivity of alumina fine particles is measured as follows.

As a device, Keithley Instruments Model 6517 Electrometer/High Resistance System is used. Electrodes having a diameter of 25 mm are connected to the apparatus described above, and the distance between the electrodes is measured in a state in which 0.1 g or more and 0.5 g or less of alumina fine particles are placed between the electrodes and a load of 1.5 N is applied.

A voltage of 1,000 V is applied to the sample for 1 minute, the resistance value is measured using the apparatus described above, and the volume resistivity is calculated using the following formula.

Volume resistivity (Ω cm) = R/L
R: Resistance value (Ω)
L: Distance between electrodes (cm)
<Measurement of Average Circularity of Toner Particles>
The average circularity of toner particles is measured by a flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation) under measurement and analysis conditions during calibration work.

A specific measuring method is as follows.

First, about 20 mL of ion-exchanged water, from which solid impurities have been removed in advance, is placed in a glass container. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a dispersant. ) is diluted with ion-exchanged water to about 3 times the mass, and about 0.2 mL of the diluted solution is added. Further, about 0.02 g of a measurement sample is added, and dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion liquid for measurement. At that time, the temperature of the dispersion liquid is appropriately cooled to 10.degree. C. to 40.degree. As the ultrasonic disperser, a desktop ultrasonic cleaner disperser (for example, "VS-150" (manufactured by Vervoclea) with an oscillation frequency of 50 kHz and an electrical output of 150 W) is used, and a predetermined amount of Ion-exchanged water is added, and about 2 mL of the contaminon N is added to the water tank.

For the measurement, a flow-type particle image analyzer equipped with "LUCPLFLN" (magnification 20 times, numerical aperture 0.40) was used as the objective lens, and particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. use. The dispersion liquid prepared according to the above procedure is introduced into the flow type particle image analyzer, and 2000 toner particles are counted in the HPF measurement mode and the total count mode.

Then, the binarization threshold during particle analysis is set to 85%, the analysis particle diameter is limited to a circle equivalent diameter of 1.977 μm or more and less than 39.54 μm, and the average circularity of the toner particles is obtained.

In the measurement, automatic focus adjustment is performed using standard latex particles (for example, "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5100A" manufactured by Duke Scientific diluted with deionized water) before starting the measurement. After that, it is preferable to perform focus adjustment every two hours from the start of measurement.

In the examples, a flow-type particle image analyzer that was calibrated by Sysmex and received a calibration certificate issued by Sysmex was used. Except for limiting the analyzed particle diameter to a circle equivalent diameter of 1.977 μm or more and less than 39.54 μm, the measurement is performed under the measurement and analysis conditions when the calibration certificate was received.

<Method for Measuring Weight Average Particle Size (D4) of Toner>
The weight average particle diameter (D4) of toner is calculated as follows. As a measuring device, a precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.) using a pore electrical resistance method equipped with a 100 μm aperture tube is used. The attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.) is used for setting the measurement conditions and analyzing the measurement data. The measurement is performed with 25,000 effective measurement channels.

As the electrolytic aqueous solution used for measurement, a solution obtained by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.) can be used.

Before conducting the measurement and analysis, the dedicated software was set as follows.

On the "Change standard measurement method (SOMME)" screen of the dedicated software, set the total count number in control mode to 50000 particles, set the number of measurements to 1, and set the Kd value to "standard particle 10.0 μm" (Beckman Coulter (manufactured by Co., Ltd.) is used to set the value obtained. By pressing the "threshold/noise level measurement button", the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and put a check in the “Flush aperture tube after measurement” box.

On the "pulse-to-particle size conversion setting" screen of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

A specific measuring method is as follows.

(1) About 200 mL of the electrolytic aqueous solution is placed in a 250 mL glass round-bottomed beaker exclusively for Multisizer 3, set on a sample stand, and stirred counterclockwise at 24 rpm with a stirrer rod. Then, remove dirt and air bubbles inside the aperture tube using the dedicated software's "Flush Aperture" function.

(2) About 30 mL of the electrolytic aqueous solution is placed in a 100 mL flat-bottom glass beaker. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a dispersant. ) is diluted with ion-exchanged water to about 3 times the mass, and about 0.3 mL of the diluted solution is added.

(3) Prepare an ultrasonic disperser "Ultrasonic Dispension System Tetra 150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two oscillators with an oscillation frequency of 50 kHz built in with a phase shift of 180 degrees. About 3.3 L of ion-exchanged water is placed in the water tank of the ultrasonic disperser, and about 2 mL of Contaminon N is added to this water tank.

(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized.

(5) While the electrolytic aqueous solution in the beaker in (4) above is being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. In the ultrasonic dispersion, the temperature of the water in the water tank is appropriately adjusted to 10°C or higher and 40°C or lower.

(6) Using a pipette, drop the electrolytic aqueous solution of (5) in which the toner is dispersed into the round-bottomed beaker of (1) set in the sample stand, and adjust the measured concentration to about 5%. . The measurement is continued until the number of measured particles reaches 50,000.

(7) Analyze the measurement data with the dedicated software attached to the apparatus, and calculate the weight average particle size (D4). Incidentally, the weight average particle diameter (D4) is the "average diameter" on the "analysis/volume statistical value (arithmetic mean)" screen when graph/vol% is set in the dedicated software.

<Measurement of E/A of Toner Particle Surface>
The ratio (E/A) of the content (E) of the sulfur element to the content (A) of the carbon element present on the surface of the toner particles was measured using an X-ray photoelectron spectrometer (ESCA) "Type 1600S" (Physical Electronics Industries, Inc.). Co.) is used to analyze the composition of the surface of the toner particles, and the calculation is performed based on the analysis results.

The measurement conditions are an X-ray source MgKα (400 W) and a spectral region of 800 μmφ.

From the measured peak intensity of each element, Physical Electronics Industries, Inc. Calculate the surface atomic concentration (atomic %) using the relative sensitivity factor provided by the company, and use it as the content of each element.

The measurement peak top range of each element used for measurement is carbon element: 283 to 293 eV and sulfur element: 166 to 172 eV.

<Method for measuring fine particle ratio>
The fine particle ratio of the toner particles was measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under measurement and analysis conditions during calibration work.

A specific measuring method is as follows. First, about 20 mL of ion-exchanged water, from which solid impurities have been removed in advance, is placed in a glass container. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a dispersant. ) is diluted with ion-exchanged water to about 3 times the mass, and about 0.2 mL of the diluted solution is added. Further, about 0.02 g of a measurement sample is added, and dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion liquid for measurement. At that time, the temperature of the dispersion liquid is appropriately cooled to 10° C. or higher and 40° C. or lower. As the ultrasonic disperser, a desktop ultrasonic cleaner disperser (for example, "VS-150" (manufactured by Vervoclea) with an oscillation frequency of 50 kHz and an electrical output of 150 W) is used, and a predetermined amount of Ion-exchanged water is added, and about 2 mL of the contaminon N is added to the water tank.

For the measurement, the flow-type particle image analyzer equipped with "LUCPLFLN" (magnification 20 times, numerical aperture 0.40) as the objective lens was used, and the sheath liquid was the particle sheath "PSE-900A" (manufactured by Sysmex Corporation). It was used. The dispersion liquid prepared according to the above procedure is introduced into the flow type particle image analyzer, and 2000 toner particles are counted in the HPF measurement mode and the total count mode. Then, the binarization threshold during particle analysis was set to 85%, the analyzed particle diameter was set to the particle circumference length, and the existence ratio of particles less than 6.332 μm was set to fine particles.

In the measurement, automatic focus adjustment is performed using standard latex particles (for example, "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5100A" manufactured by Duke Scientific diluted with deionized water) before starting the measurement. After that, it is preferable to perform focus adjustment every two hours from the start of measurement.

In the examples of the present application, a flow-type particle image analyzer that was calibrated by Sysmex and received a calibration certificate issued by Sysmex was used.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these. All parts and percentages in Examples and Comparative Examples are based on mass unless otherwise specified.

<Production Example of Alumina Fine Particles 1>
Using alumina hydroxide A as an alumina raw material, adding 0.02 parts of α-alumina C as a seed crystal (the amount added is based on 100 parts of alumina obtained from the alumina raw material, the same applies hereinafter), and hydrogen chloride as an atmospheric gas Experiments were conducted by introducing gas into a tubular furnace. The introduction temperature of the atmospheric gas was 900° C., the holding temperature (firing temperature) was 1200° C., and the holding time (firing time) was 30 minutes. Table 1 shows the physical properties of the alumina fine particles.

<Production Examples of Alumina Fine Particles 2, 3, and 6>
Alumina fine particles 2, 3, and 6 were obtained by changing the manufacturing conditions of alumina fine particles 1. Table 1 shows the physical properties of the alumina fine particles.

<Production Example of Alumina Fine Particles 4>
Alumina fine particles 4 were obtained by surface-treating the alumina fine particles 3 with calcium stearate. Table 1 shows the physical properties of the alumina fine particles.

<Alumina fine particles 5>
Bayer alumina (AES-12) manufactured by Sumitomo Chemical Co., Ltd. was used. Table 1 shows the physical properties of the alumina fine particles.

<Alumina fine particles 7>
Deflagration alumina (AO-502) manufactured by Admatechs was used. Table 1 shows the physical properties of the alumina fine particles.

<Production example of charge control resin 1>
250 parts of methanol, 150 parts of 2-butanone and 100 parts of 2-propanol as a solvent, and styrene as a monomer were placed in a pressurizable reaction vessel equipped with a reflux tube, a stirrer, a thermometer, a nitrogen inlet tube, a dropping device and a pressure reducing device. 83 parts, 12 parts of butyl acrylate and 5 parts of 2-acrylamido-2-methylpropanesulfonic acid were added and heated to the reflux temperature with stirring.

To this, a solution prepared by diluting 0.45 parts of t-butylperoxy-2-ethylhexanoate as a polymerization initiator with 20 parts of 2-butanone was added dropwise over 30 minutes, and stirring was continued for 5 hours. A solution prepared by diluting 0.28 parts of -butylperoxy-2-ethylhexanoate with 20 parts of 2-butanone was added dropwise over 30 minutes, and the mixture was stirred for 5 hours to complete the polymerization.

The polymer obtained after distilling off the polymerization solvent under reduced pressure was coarsely pulverized to 100 μm or less using a cutter mill fitted with a 150-mesh screen to obtain charge control resin 1 . The glass transition temperature (Tg) of the obtained polymer was about 70°C.

<Production Example of Toner Particle 1>
710 parts of ion-exchanged water and 850 parts of 0.1 mol/L Na ₃ PO ₄ aqueous solution were added to a four-necked container, and a high-speed stirring device T.I. K. The temperature was maintained at 60° C. while stirring at 200 s ⁻¹ using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). 68 parts of a 1.0 mol/L CaCl ₂ aqueous solution was gradually added thereto to prepare an aqueous dispersion medium containing a dispersion stabilizer.
・Styrene 125 parts ・n-Butyl acrylate 35 parts ・Copper phthalocyanine pigment (Pigment Blue 15:3) 12 parts ・Polyester resin 1 10 parts (terephthalic acid-propylene oxide modified bisphenol A (2 mol adduct) copolymer, acid value: 10 mgKOH/g, glass transition temperature (Tg): 70°C, weight average molecular weight (Mw): 10500)
・Charge control resin 1 1.85 parts ・Fischer-Tropsch wax (melting point: 78 ° C.) 15 parts The above materials are stirred for 3 hours using an attritor (manufactured by Nippon Coke Kogyo Co., Ltd.), and each component is converted into a polymerizable monomer. to prepare a monomer mixture.

20.0 parts of 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate (50% toluene solution) as a polymerization initiator was added to the monomer mixture to form a polymerizable monomer composition. was prepared.

The polymerizable monomer composition was put into an aqueous dispersion medium and granulated for 5 minutes while maintaining the rotation speed of the stirrer at 167 s ⁻¹ . After that, the high-speed stirring device was changed to a propeller-type stirrer, the internal temperature was raised to 75° C., and the mixture was reacted for 6 hours while stirring slowly.

Then, the temperature inside the container was raised to 85° C. and maintained for 5 hours, and then cooled to obtain a slurry. Dilute hydrochloric acid was added into the vessel containing the slurry to remove the dispersion stabilizer. Further, toner particles 1 were obtained by filtration, washing and drying. Table 2 shows the physical properties of the toner particles 1 thus obtained.

<Production Example of Toner Particles 2>
Toner Particles 2 were produced in the same manner as in Production Example of Toner Particles 1, except that the type of polyester resin was changed to the following resin.
Polyester resin 2 (terephthalic acid-propylene oxide-modified bisphenol A (2 mol adduct) copolymer, acid value: 8 mgKOH/g, glass transition temperature (Tg): 71°C, weight average molecular weight (Mw): 10600)

<Production Example of Toner Particles 3>
Toner Particles 3 was produced in the same manner as in Production Example of Toner Particles 1 except that the number of parts of the polyester resin was changed to 8 parts.

<Production Example of Toner Particles 4>
Toner Particle 4 was produced in the same manner as in Production Example of Toner Particle 1 except that the number of parts of the polyester resin was changed to 12 parts.

<Production Example of Toner Particles 5>
Toner Particles 5 were produced in the same manner as in Production Example of Toner Particles 4 except that the number of parts of Charge Control Resin 1 was changed to 2.00 parts.

<Production Example of Toner Particles 6>
Toner particles 6 were produced in the same manner as in the production example of toner particles 4 except that the number of parts of charge control resin 1 was changed to 1.46 parts.

<Production Example of Toner Particles 7>
Toner particles 7 were produced in the same manner as in the production example of toner particles 3 except that the charge control resin 1 was not added.

<Production Example of Toner Particles 8>
(Production of Resin Fine Particle Dispersion 1)
・Styrene: 350 parts ・n-Butyl acrylate: 75 parts ・Acrylic acid: 10 parts ・Dodecanethiol: 10 parts 420 parts of a solution obtained by mixing the above materials and a nonionic surfactant (manufactured by Sanyo Kasei Co., Ltd., Nonipol 400 ) and 10 parts of an anionic surfactant (Neogen R, manufactured by Daiichi Pharmaceutical Co., Ltd.) dissolved in 550 parts of ion-exchanged water were placed in a flask and dispersed and emulsified. While slowly stirring and mixing for 10 minutes, 50 parts of ion-exchanged water containing 4 parts of ammonium persulfate dissolved therein was added. Thereafter, the atmosphere in the flask was sufficiently replaced with nitrogen, and the system was heated in an oil bath with stirring until the system reached 70°C.

The volume average particle diameter (D50) of the latex in Resin Particle Dispersion 1 was measured with a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.) and found to be 155 nm. Further, when the glass transition point of the resin was measured at a temperature increase rate of 10°C/min using a differential scanning calorimeter (DSC-50, manufactured by Shimadzu Corporation), it was 54°C. HLC-8020) was used to measure the weight average molecular weight (converted to polystyrene) using THF as a solvent, and it was 33,000.

(Production of Resin Fine Particle Dispersion 2)
・Styrene: 400 parts ・n-Butyl acrylate: 100 parts ・Acrylic acid: 4 parts ・N-dodecyl mercaptan: 6 parts The above components are mixed to prepare a monomer solution, and an anionic surfactant (Daiichi Kogyo A surfactant aqueous solution obtained by dissolving 10 g of Neogen RK) in 1,130 g of ion-exchanged water and the monomer solution were put into a two-necked flask, and a homogenizer (manufactured by IKA: Ultra Turrax T50) was used to The emulsion was emulsified by stirring at a rotation speed of 10,000 r/min. Thereafter, the inside of the flask was replaced with nitrogen, and the contents were heated in a water bath with slow stirring until the temperature reached 70°C. Then, 350 parts of ion-exchanged water in which 6.56 g of ammonium persulfate was dissolved was added to initiate polymerization. . After continuing the reaction for 7 hours, the reaction solution was cooled to room temperature to obtain a fine resin particle dispersion 2 .

The latex in the fine resin particle dispersion 2 has a volume average particle diameter (D50) of 180 nm as measured by a laser diffraction particle size distribution analyzer (LA-700, manufactured by Horiba, Ltd.). The glass transition point of the resin was measured at a heating rate of 10 ° C./min using DSC-50, manufactured by Tosoh Corporation), and it was 65 ° C. Using a molecular weight analyzer (HLC-8020, manufactured by Tosoh Corporation), THF was used as a solvent. It was 26000 when the weight average molecular weight (polystyrene conversion) was measured as .

(Production of colorant fine particle dispersion)
- Cyan pigment 100.0 parts (Pigment Blue 15:3, manufactured by Dainichi Seika Co., Ltd.)
・ Anionic surfactant (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.: Neogen RK) 15.0 parts ・ Ion-exchanged water 885.0 parts Mix and dissolve the above, and use a high-pressure impact disperser Nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) For about 1 hour, a coloring agent fine particle dispersion (solid content concentration: 10% by mass) in which the coloring agent is dispersed was prepared. The volume-based median diameter of the fine colorant particles was 0.2 μm.

(Manufacturing Example of Wax Fine Particle Dispersion)
・Ester wax (behenyl behenate, melting point 75°C) 100.0 parts ・Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.: Neogen RK) 10.0 parts ・Ion-exchanged water 880.0 parts with a stirring device After putting it into a container, it is heated to 90 ° C., and using Clearmix W Motion (manufactured by M Technic Co., Ltd.), while circulating, the rotor rotates at a shear stirring part with a rotor outer diameter of 3 cm and a clearance of 0.3 mm. 310 s ⁻¹ and 310 s ⁻¹ screen rotation, and dispersed for 60 minutes. After that, the ^{wax fine} particle dispersion (solid content concentration 10 mass %) was obtained. The volume-based median diameter of the wax microparticles was 0.15 μm.

(Formation of toner particles)
Resin fine particle dispersion 1 45.0 parts Colorant fine particle dispersion 10.0 parts Wax fine particle dispersion 15.0 parts 1% by mass calcium chloride aqueous solution 20.0 parts Ion-exchanged water 110.0 parts Homogenizer ( After mixing and dispersing the above materials using Ultra Turrax T50 (manufactured by IKA), the mixture was heated to 45°C in a water bath while stirring with a stirring blade. After holding at 45° C. for 1 hour, observation with an optical microscope confirmed that aggregated particles having a weight average particle size (D4) of 5.7 μm were formed (aggregation step).

After adding 40.0 parts of a 5% by mass trisodium citrate aqueous solution, the temperature was raised to 85° C. while stirring was continued and held for 120 minutes to obtain an aqueous dispersion containing fused core particles (primary fusion process). When the particle size of the core particles was measured, the weight average particle size (D4) was 6.4 μm.

Next, while continuing to stir, water was added to the water bath to cool the aqueous dispersion of core particles to 25°C.

Then, 12.1 parts of resin fine particle dispersion 2 was added. After that, stirring was performed for 10 minutes, 60.0 parts of a 2% by mass calcium chloride aqueous solution was added dropwise, and the temperature was raised to 35°C. In this state, a small amount of liquid was extracted at any time, passed through a 2 μm microfilter, and stirring was continued at 35° C. until the filtrate became clear.

After confirming that the filtrate became transparent and that the fine resin particles adhered to the core particles and that the shell adherents were formed, the aqueous dispersion of the shell adherents was heated to 40°C and stirred for 1 hour. 35.0 parts by mass of trisodium citrate aqueous solution was added, the temperature was raised to 65° C., and stirring was performed for 3.0 hours (secondary fusion step).

After that, the obtained liquid was cooled to 25° C., filtered and solid-liquid separated, and then 800 parts of ion-exchanged water was added to the solid content and washed with stirring for 30 minutes. After that, filtration and solid-liquid separation were performed again.

Filtration and washing are repeated as described above until the electric conductivity of the filtrate becomes 150 μS/cm or less in order to eliminate the influence of the residual surfactant. got

<Production Example of Toner Particles 9>
Toner Particle 1 was prepared in the same manner as in Production Example of Toner Particles 1, except that the number of parts of the polyester resin was changed to 12 parts and that Charge Control Resin 1 was not added.

<Production Example of Toner Particles 10>
- Cyan pigment 6 parts (Pigment Blue 15:3, manufactured by Dainichi Seika Co., Ltd.)
・Styrene-butyl acrylate-butyl maleate half ester copolymer (glass transition point Tg = 63 ° C.) 100 parts ・Iron complex of monoazo dye (negative charge control agent) 2 parts ・Low molecular weight polyethylene (DSC endothermic peak 106.7°C, Mw/Mn = 1.08) 4 parts The above materials are mixed in a blender, then melt-kneaded in a twin-screw extruder heated to 110°C, and the cooled kneaded product is coarsely pulverized in a hammer mill. Then, the coarsely pulverized product was finely pulverized by a mechanical pulverizer, and the obtained finely pulverized product was classified by a multi-division classifier using the Coanda effect to obtain toner particles 10 .

<Example 1>
For 100 parts of the obtained toner particles 1,
・Alumina fine particles 1 0.05 parts ・Silica fine particles (silica raw material having a number average particle diameter of primary particles of 10 nm and a BET specific surface area of 125 m ² /g subjected to surface treatment with hexamethyldisilazane and silicone oil)
1.0 part was externally mixed with FM10C (manufactured by Nippon Coke Kogyo Co., Ltd.).

The external addition conditions were as follows: amount of toner particles charged: 1.8 kg; number of revolutions: 60 s ^-1 ; external addition time: 15 minutes. Thereafter, the toner 1 was obtained by sieving with a mesh having an opening of 200 μm. Table 3 shows the external addition conditions, and Table 4 shows the physical properties of Toner 1.

Using Toner 1 thus obtained, the following evaluations were carried out. Tables 5 and 6 show the evaluation results.

(evaluation)
A laser beam printer HP Color LaserJet Enterprise M651n was modified so that it could be operated even if only one color process cartridge was installed, and the evaluation was performed. As the evaluation paper, CS-680 sold by Canon Marketing Japan was used. The toner was filled in a predetermined process cartridge.

For long-term use, evaluation was performed in a low-temperature, low-humidity environment (temperature of 10° C., relative humidity of 14%) and a high-temperature, high-humidity environment (temperature of 30° C., relative humidity of 80%), which are susceptible to electrification. In a low-temperature and low-humidity environment, the chargeability of the toner is high and charge-up is likely to occur.

For long-term use, a horizontal line pattern with a print rate of 2% is set to 2 sheets per job, and the machine stops between jobs before starting the next job. Imaging tests were performed. Evaluation was performed at the initial stage and after image formation on 15,000 sheets.

• Image Density The image density was measured by outputting a 5 mm round solid image and measuring the reflection density with a reflection densitometer X-Rite 500 series (manufactured by Videojet X-Rite Co., Ltd.). Image densities were measured both in the high-temperature and high-humidity environment and in the low-temperature and low-humidity environment, and both at the initial stage and after image formation on 15,000 sheets.

The width of change in density at the initial stage and after durability was calculated and evaluated according to the following criteria.
A: Reflection density difference less than 0.05 B: Reflection density difference 0.05 or more and less than 0.10 C: Reflection density difference 0.10 or more and less than 0.15 D: Reflection density difference 0.15 or more

• Image fogging Ds is the lowest value of reflection density in the solid white image of a solid white image, Dr is the reflection average density of the transfer material before image formation, and Dr - Ds is the fogging value. As the evaluation paper, gloss paper (HP Laser Brochure Paper 200 g paper manufactured by HP) was used. A reflection densitometer (reflectometer model TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.) was used to measure the reflection density, and an amber light filter was used as the filter. A smaller value indicates a better fog level. Evaluation was performed both at the initial stage and after image formation on 15,000 sheets in both a high-temperature, high-humidity environment and a low-temperature, low-humidity environment.

Halftone streak Evaluation of halftone streak was performed after image formation on 15,000 sheets in a high-temperature and high-humidity environment.

A halftone image with a reflection density of 0.60 is output, the obtained image is observed along the longitudinal direction, and the image density at five low density points is measured. Halftone streaks were evaluated by calculating the average image density of all multiple births and the average value of density differences at 5 points. Evaluation criteria are shown below.
A: Reflection density difference less than 0.05 B: Reflection density difference 0.05 or more and less than 0.10 C: Reflection density difference 0.10 or more and less than 0.15 D: Reflection density difference 0.15 or more

• Poor regulation The evaluation of the faulty regulation was performed after forming 15,000 sheets of images in a low-temperature, low-humidity environment. The amount of spot-like streaks and toner lumps appearing on the halftone image was evaluated.
A: Not generated B: No spotty streaks, but 2 or 3 small toner lumps C: Slight spotty streaks at edges or 4 or 5 small toner lumps D: Entire surface There are spot-like streaks on the surface, or there are small toner masses or obvious toner masses in 5 or more locations.

・^Fixability rubbing test Using the evaluation machine used in the above evaluation under a low temperature and low humidity environment, a 10 mm × 10 mm 3 dot 3 space (10 mm × 10 mm 3 dot 3 space ( 600 dpi) image with many images was output. The obtained fixed image was rubbed 5 times with Silbon paper loaded with a weight of 50 g/cm ² (0.49 N/cm ² ), and the reduction rate of the image density after rubbing was evaluated based on the following. The fixing temperature was set to 180.degree. Further, for the measurement of image density, the X-Rite 500 series (manufactured by Videojet X-Rite Co., Ltd.) was used to measure the relative density of the white background portion of the document with a density of 0.00 with respect to the printout image. The rate of decrease in image density after rubbing was calculated.
A: Less than 5.0% B: 5.0% or more and less than 10.0% C: 10.0% or more and less than 15.0% D: 15.0% or more

<Examples 2 to 14, Comparative Examples 1 to 8>
Toners 2 to 14 and Comparative Toners 1 to 8 were obtained in the same manner as in Example 1, except that the types and amounts of the toner particles and alumina fine particles were changed as shown in Table 3. Table 4 shows the physical properties of the obtained toner. Moreover, the same evaluation as in Example 1 was performed using the obtained toner. Tables 5 and 6 show the evaluation results.

Claims (5)

A toner having toner particles containing a binder resin and a colorant and fine alumina particles,
The alumina fine particles exist as aggregated particles in which primary particles are aggregated on the surface of the toner, and the number average particle diameter of the primary particles is 200 nm or more and 400 nm or less,
The average projected area of the alumina fine particles on the toner surface is 0.17 μm ² or more and 0.30 μm ² or less, and the average value of the values obtained by dividing the peripheral length of the projected image of the alumina fine particles by the projected area is 7.5 or more. and
The toner is characterized in that the amount of alumina fine particles adhering to the polycarbonate thin film is 0.40 area % or more and 1.00 area % or less based on the area of the polycarbonate thin film in the polycarbonate thin film adhesion measurement method. . Regarding the alumina fine particles adhering to the polycarbonate thin film, the average projected area is 0.17 μm ² or more and 0.30 μm ² or less, and the average value of the values obtained by dividing the peripheral length of the projected image by the projected area is 7.5 or more. The toner of claim 1. 3. The toner according to claim 1, wherein the content of said alumina fine particles is 0.02 parts by mass or more and 1.50 parts by mass or less per 100 parts by mass of said toner particles. 4. The toner according to any one of claims 1 to 3, wherein the alumina fine particles have a purity of aluminum oxide of 99.99% or more and 100.00% or less. 5. The toner according to any one of claims 1 to 4, wherein the toner particles have an average circularity of 0.960 or more.

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