JP2020086076A - toner - Google Patents

Abstract

To provide toner using large particle size silica for durability improvement capable of improving the unevenness of low-printed images during high-speed printing while maintaining durability.SOLUTION: The toner contains toner particles and an external additive, in which the external additive contains an external additive A and an external additive B, the number average particle diameter of the external additive A is 70 nm or more and 250 nm or less, and the zeta potential of the external additive B is -45.0 mV or higher and -10.0 mV or lower. When the volume resistivity of the external additive A is TA and the volume resistivity of the external additive B is TB, TA is 5.0×10Ω m or more and 9.0×10Ω m or less, and satisfies the following formula: 4.70≤TA/TB≤10.00.SELECTED DRAWING: None

Description

The present invention relates to a toner used in electrophotography, electrostatic recording, magnetic recording and the like.

In recent years, electrophotographic image forming apparatuses are required to have characteristics such as higher definition, higher quality and higher image quality, as well as higher speed, long-term high reliability, and long life. In particular, in order to extend the life, it is important that the quality does not change significantly even after long-term durable use, and various external additives have been proposed for toner.
Among them, many proposals have been made in which an external additive having a large particle diameter is added to toner particles for the purpose of maintaining stable fluidity for a long period of time.
For example, Patent Document 1 proposes to add silica particles formed by a sol-gel method. Patent Document 2 proposes to externally add titanium oxide, which has a low resistivity and a rapid charging rise, together with an external additive having a large particle size.

Patent No. 5724401 JP, 2017-138590, A

However, the silica particles as described in Patent Document 1 have a slow rising of charging, and may cause a problem with respect to the step unevenness as described below. The step unevenness is an image adverse effect that occurs particularly in a high-speed machine due to the effects of eccentricity of the sleeve and drum and the effects of gear vibration. Specifically, within one round of the sleeve, rubbing is strong, and there are portions that are easily charged and portions that are weakly rubbing and have low charging, which appear in the image in the form of step unevenness. Step unevenness may occur more markedly during high-speed printing or in low-density images such as halftone images. Therefore, a toner having a fast charging rise is required as the toner, but the above-mentioned silica particles cannot provide a sufficient effect.
Further, even in Patent Document 2, there is room for improvement of step unevenness in order to further increase the speed.
The present invention has been made in view of the above circumstances, and it is possible to supply a toner capable of obtaining a high-quality image by suppressing step unevenness of a low-density image even during high-speed printing while having durability stability. To aim.

The present invention is a toner containing toner particles and an external additive, wherein the external additive contains an external additive A and an external additive B, and the number average particle diameter of the external additive A is 70 nm or more and 250 nm or more. And the zeta potential of the external additive B is -45.0 mV or more and -10.0 mV or less, the volume resistivity of the external additive A is TA, and the volume resistivity of the external additive B is TB. And TA was 5.0×10 ³ Ω·m or more and 9.0×10 ³ Ω·m or less, and the following formula 4.70≦TA/TB≦10.00
The present invention relates to a toner characterized by satisfying:

According to the present invention, it is possible to supply a toner having high durability and improved step unevenness of a low density image in high speed printing.

The present invention provides a toner containing toner particles and an external additive,
(1) The external additive contains an external additive A and an external additive B,
(2) The number average particle diameter of the external additive A is 70 nm or more and 250 nm or less,
(3) The zeta potential of the external additive B is -45.0 mV or more and -10.0 mV or less,
(4) When the volume resistivity of the external additive A is TA and the volume resistivity of the external additive B is TB, TA is 5.0×10 ³ Ωm or more and 9.0×10 ³ Ω. m or less, and the following formula 4.70≦TA/TB≦10.00
It is characterized by satisfying.

According to the studies by the present inventors, by using the toner of the present invention, it is possible to supply a toner having high durability and improved step unevenness of a low density image in high speed printing.

As described above, by adding an external additive having a large particle size to improve durability, uneven charging of the toner becomes large, and step unevenness of a low density image is a problem in further high speed printing. In order to improve this, a certain effect was observed by using an external additive having a low resistivity, but it was not sufficient in further high speed printing.

As a result of intensive investigations by the present inventors, the particle size of the external additive, the resistivity, the zeta potential, etc. can be obtained in order to obtain stable charging characteristics even in the situation where such minute changes in charge occur. It has been found that the characteristics of N must be designed in detail. The details are described below.

An external additive having a low resistivity has a fast charge decay. On the other hand, generally, a low-resistivity external additive also has a high dielectric constant and is excellent in rising of charging. On the contrary, an external additive having a high resistance has a slow decay of charging, but also has a slow rise of charging. Therefore, the high-resistivity external additive and the low-resistivity external additive cause a difference in the rate of charge generation and decay. Due to this difference in the rate of generation and decay of electric charges, an interaction called polarization occurs when the low resistance external additive and the high resistance external additive are brought close to each other. Occur. For example, when the electric charge of the low-resistivity external additive is decaying, the surface of the adjacent high-resistivity external additive is negatively charged and charged. This is because, in the electrophotographic process, when there is a portion where the sliding is weak due to uneven sliding of the sleeve, less charge is applied and a portion with a low concentration is formed. Attenuation of the electric charge is suppressed, and uneven charging of the toner is reduced, and uneven step can be prevented.

On the other hand, when a charge is applied to the low-resistivity external additive, a positive charge is applied to the surface of the adjacent high-resistance external additive by polarization. This is because in the electrophotographic process, in the situation where excessive friction is applied due to uneven sliding of the sleeve due to uneven rubbing of the sleeve, polarization prevents the high resistivity external additive from being excessively charged, resulting in high density. You can prevent it from coming out too much.

In order to exhibit the above effects, specifically, it is important that the toner contains toner particles and an external additive, and that the external additive contains the external additive A and the external additive B. Here, the external additive A represents a high resistance external additive, and the external additive B represents a low resistance external additive.

Regarding the external additive A, it is important that the number average particle diameter of the external additive A is 70 nm or more and 250 nm or less. If the particle size of the external additive A is less than 70 nm, desired durability cannot be obtained. If it is larger than 250 nm, it becomes difficult to adhere to the toner particles, which causes problems such as reduction in image density.

When TA is the volume resistivity of the external additive A and TB is the volume resistivity of the external additive B, TA is 5.0×10 ³ Ω·m or more and 9.0×10 ³ Ω·m. It is below, and it is important that 4.70≦TA/TB≦10.00. When TA is less than 5.0×10 ³ Ω·m, the charge loss is large and the chargeability is lowered, and the image density is lowered. If it is larger than 9.0×10 ³ Ω·m, charge-up is likely to occur and the image density is lowered.

TA/TB represents the ratio of the resistivities of the high resistance external additive and the low resistance external additive, and charge transfer due to polarization occurs in the above range. When TA/TB is less than 4.70, polarization does not occur and the effect of suppressing charging unevenness is not observed. When TA/TB is larger than 10.00, it means that TB is low, and the charge of the external additive B is excessively attenuated at the time of charging, so that the image density is lowered.

The external additive A may be any fine particles as long as it satisfies the above characteristics, but organic-inorganic composite particles are preferable. TA can be easily controlled by changing the ratio of the organic component and the inorganic component.

The organic-inorganic composite fine particles can be produced as described below, for example, according to the description of Examples in WO 2013/063291. The external additives A-1 to A-5 in the examples described below are also produced by the following production.

A 250 mL four-neck round bottom flask equipped with an overhead stir motor, condenser, and thermocouple was charged with the colloidal silica dispersion, distilled water, and methacryloxypropyl-trimethoxysilane. The temperature was raised to 65° C. and stirred at 120 rpm. Nitrogen gas was bubbled through the mixture for 30 minutes. After 3 hours, 2,2'-azobisisobutyronitrile radical initiator in which ethanol was dissolved was added to raise the temperature to 75°C. Radical polymerization was allowed to proceed for 5 hours, after which 1,1,1,3,3,3-hexamethylyldisilazane was added to this mixture. After reacting for 3 hours, the mixture was filtered through a 170-mesh sieve, and the dispersion was dried at 120° C. overnight. The organic-inorganic composite particles can be obtained by pulverizing with a rolling mill. The ratio of the organic component to the inorganic component on the surface of the organic-inorganic composite particles can be controlled by changing the input amounts of the colloidal silica dispersion and methacryloxypropyl-trimethoxysilane. For example, methacryloxypropyl - When the amount of silica ratio contained in trimethoxysilane / colloidal silica is defined as M _mps / M _Si, particle size when M _mps / M _Si decreases is small, the ratio of the inorganic components is increased .. Further, it is possible to control these by changing the particle size of the colloidal silica (colloidal silica) used. The particle size of the colloidal silica is preferably 10 nm or more and 30 nm or less from the viewpoint of the particle size and shape of the obtained organic-inorganic composite particles.

Regarding the external additive B, it is important that the zeta potential of the external additive B is -45.0 mV or more and -10.0 mV or less.

It is important that the zeta potential of the external additive B is within the above range, and in this range, the step unevenness due to polarization is significantly suppressed. If the zeta potential of the external additive B is less than -45.0 mV, the image density decreases due to charge-up, and if it is greater than -10.0 mV, the step unevenness suppressing effect due to polarization is not observed.

The particle size of the external additive B is preferably 10 nm or more and 80 nm or less. The polarization effect becomes large in this range.

In addition, TB is preferably 9.0×10 ² Ω·m or more and 1.5×10 ³ Ω·m or less. In this range, the image density and the step unevenness suppressing effect are well balanced.

The external additive B is preferably at least one selected from the group consisting of strontium titanate, barium titanate, calcium titanate, and titanium oxide. With these materials, TB can be controlled within a desired range.

Of these, the method for producing the strontium titanate fine particles is not particularly limited, but for example, the following method is used.

As a general method for producing fine particles of strontium titanate, there is a method of sintering after solid-phase reaction of titanium oxide and strontium carbonate. The known reaction adopted in this production method can be represented by the following formula.
TiO ₂ +SrCO ₃ →SrTiO ₃ +CO ₂

That is, a mixture containing titanium oxide and strontium carbonate is washed, dried, sintered, mechanically pulverized, and classified to be produced. At this time, the composite inorganic fine powder containing strontium titanate, strontium carbonate, and titanium oxide can be obtained by adjusting the raw materials and the firing conditions. The raw material strontium carbonate is not particularly limited as long as it has a SrCO ₃ composition, and any commercially available product can be used. Further, the titanium oxide as a raw material is not particularly limited as long as it is a substance having a TiO ₂ composition. Examples of the titanium oxide include metatitanic acid slurry (undried hydrous titanium oxide) obtained by the sulfuric acid method, titanium oxide powder, and the like. The sintering is preferably performed at a temperature of 500°C or higher and 1300°C or lower, and more preferably 650°C or higher and 1100°C or lower. When the firing temperature is 1300° C. or lower, secondary agglomeration due to sintering between particles is unlikely to occur, and the load in the pulverization process can be suppressed. Further, when the firing temperature is 600° C. or higher, unreacted components can be suppressed and stable production of strontium titanate fine particles becomes possible. The preferable firing time is 0.5 hours or more and 16 hours or less, and more preferably 1 hour or more and 5 hours or less. When the firing time is 16 hours or less, secondary agglomeration of the obtained strontium titanate particles is unlikely to occur, and when the firing time is 0.5 hours or more, unreacted components are suppressed and stable strontium titanate fine particles are obtained. It becomes possible to manufacture.

On the other hand, as a method for producing strontium titanate fine particles that does not undergo a sintering step, a dispersion of titania sol obtained by adjusting the pH of a hydrous titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate is added with strontium hydroxide. There is a method of synthesizing by adding and heating to the reaction temperature. When the pH of the hydrous titanium oxide slurry is 0.5 or more and 1.0 or less, a titania sol having a good crystallinity and particle size can be obtained. Further, for the purpose of removing the ions adsorbed on the titania sol particles, it is preferable to add an alkaline substance such as sodium hydroxide to the dispersion liquid of the titania sol. At this time, it is preferable that the pH of the slurry is not set to 7 or more so that sodium ions and the like are not adsorbed on the surface of the hydrous titanium oxide. The reaction temperature is preferably 60° C. or higher and 100° C. or lower, and the temperature rising rate is preferably 30° C./hour or lower to obtain a desired particle size distribution, and the reaction time is 3 hours or longer and 7 hours or shorter. Is preferred.

The external additive B is a particle having a partial structure a represented by CF ₃ —Si—O _3/2 on the surface of the particle, and the external additive measured by X-ray photoelectron spectroscopy (XPS). The existence ratio of the partial structure a on the surface of the agent B is preferably 0.110 or more and 0.220 or less. With such a structure, the zeta potential of the external additive B can be controlled within the above range.

The surface treatment of the external additive B can be performed by surface coating with a silane coupling agent in order to obtain the partial structure a. As the silane coupling agent, a fluoroalkyl silane coupling agent, an isocyanate silane coupling agent, or the like can be used. The treatment method may be a wet method in which a surface treatment agent to be treated is dissolved and dispersed in a solvent, the substrate of the external additive B is added to the solution, and the solvent is removed while stirring, or a coupling method is used. Examples include a dry method in which the agent, the fatty acid metal salt and the substrate of the external additive B are directly mixed and treated with stirring.

In order to control the existence ratio of the partial structure a, a method of performing treatment by combining with another silane coupling agent, and a method of performing treatment after performing surface coating with a hydrophobizing agent such as silicone oil can be mentioned. By mixing and stirring a plurality of types of silane coupling agents, bonding between the coupling agents proceeds, and the surface layer of the external additive B can be more easily treated in an island shape, which is a preferred method of treatment.

With respect to the added amounts of the external additive A and the external additive B, the content of the external additive A is 0.2 parts by mass or more and 5.0 parts by mass or less based on 100 parts by mass of the toner particles, The content of the additive B is preferably 0.02 times or more and 1.00 times or less the content of the external additive A. In this range, both the image density and the step unevenness suppressing effect are at a high level.

At this time, when the volume resistivity of the toner particles is TT, TT is 2.0×10 ³ Ω·m or more and 5.0×10 ³ Ω·m or less, and TT/TB is less than 4.70. Preferably. Although the interaction between the external additive A and the external additive B is the most dominant, the interaction between the surface of the toner particles and the external additive B may occur. At this time, when the amount is within the above range, an interaction due to polarization does not occur between the surface of the toner particles and the external additive B, and the effect of suppressing step unevenness becomes greater.

The binder resin used in the toner particles of the present invention will be described.

Examples of the binder resin include polyester resins, vinyl resins, epoxy resins, and polyurethane resins, but the binder resin is not particularly limited, and conventionally known resins can be used.

The toner of the present invention may further contain a magnetic substance or a colorant.

The following can be illustrated as a magnetic body. Iron oxides such as magnetite, hematite and ferrite, metals such as iron, cobalt and nickel or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, bismuth, calcium, manganese, titanium and tungsten. , Alloys of metals such as vanadium and mixtures thereof.

In order to control the volume resistivity of the toner particles, the addition amount is preferably 10 parts by mass or more and 100 parts by mass or less, and more preferably 30 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the binder resin.

Examples of the colorant used in the present invention are given below.

As the black colorant, for example, carbon black, grafted carbon, or a yellow/magenta/cyan colorant shown below toned in black can be used. Examples of the yellow colorant include compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Examples of cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. These colorants may be used alone or in combination, and may be used in the form of a solid solution.

The toner of the present invention may contain wax.

The wax used in the present invention includes the following. For example, low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymers, polyolefin wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax and other aliphatic hydrocarbon waxes; oxide polyethylene wax and other aliphatic hydrocarbon wax oxides. Or block copolymers thereof; vegetable waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax; animal waxes such as beeswax, lanolin and whale wax; mineral waxes such as ozokerite, ceresin and petrolactam. Waxes; waxes having an aliphatic ester as a main component such as montanic acid ester wax and castor wax; and deoxidized aliphatic ester such as deoxidized carnauba wax.

A charge control agent may be used in the toner of the present invention in order to stabilize its chargeability. As the charge control agent, an organic metal complex or a chelate compound in which an acid group or a hydroxyl group existing at the terminal of the binder resin used in the present invention and the central metal easily interact with each other is effective. Examples thereof include monoazo metal complex; acetylacetone metal complex; metal complex or metal salt of aromatic hydroxycarboxylic acid or aromatic dicarboxylic acid.

The method for producing the toner according to the present invention is not particularly limited, and known production methods such as a pulverization method, a suspension polymerization method, a dissolution suspension method, an emulsion aggregation method, and a dispersion polymerization method can be used.

For example, in order to prepare it by a pulverization method, i) a binder resin constituting the toner, magnetic iron oxide particles as a colorant, and optionally wax, and other additives are added by using a Henschel mixer, a ball mill, or the like. Mix thoroughly with a mixer,
ii) The resulting mixture was melt-kneaded using a heat kneader such as a twin-screw kneading extruder, a heating roll, a kneader, and an extruder to make the resins compatible with each other, and wax, magnetic iron oxide particles and Disperse or dissolve the metal-containing compound,
The toner particles according to the present invention can be obtained by iii) cooling and solidifying, pulverizing, and iv) classification.

Further, in order to control the shape and surface property of the toner, it is preferable to have a surface treatment step of allowing the toner to pass through a surface treatment device to which a mechanical impact force is continuously applied after pulverization or classification. By controlling the processing time of this surface treatment step, it is possible to control the surface shape of the toner and control the adhesive force of the toner.

Further, a desired external additive can be sufficiently mixed with a mixer such as a Henschel mixer to obtain the toner according to the present invention.

The following are mentioned as a mixer. Henschel mixer (manufactured by Nippon Coke Industry Co., Ltd.); Super mixer (manufactured by Kawata Co., Ltd.); Ribocon (manufactured by Okawara Seisakusho); Nauta mixer, turbulizer, cyclomix (manufactured by Hosokawa Micron); Spiral pin mixer (manufactured by Pacific Kiko) ); Ledige mixer (manufactured by Matsubo).

Examples of the kneader include the following. KRC Kneader (manufactured by Kurimoto Iron Works Co., Ltd.); Bus Co Kneader (manufactured by Buss Company); TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Japan Steel Works Co., Ltd.); PCM kneader (Ikegai Co., Ltd.) Iron Rolling Co., Ltd.); Three Roll Mill, Mixing Roll Mill, Kneader (Inoue Seisakusho); Kneedex (Mitsui Mining Co., Ltd.); MS Pressure Kneader, Nider Ruder (Moriyama Seisakusho); Banbury Mixer (Kobe Steel) Company).

Examples of the crusher include the following. Counter jet mill, micron jet, inomizer (made by Hosokawa Micron); IDS type mill, PJM jet crusher (made by Nippon Pneumatic Mfg. Co.); Cross jet mill (made by Kurimoto Iron Works Co., Ltd.); Ulmax (made by Nisso Engineering Co., Ltd.) ); SK Jet O Mill (manufactured by Seishin Enterprise Co., Ltd.); Kliptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turbo Engineering Co., Ltd.); Super rotor (manufactured by Nisshin Engineering Co., Ltd.).

Examples of the classifier include the following. Classel, Micron Classifier, Spedic Classifier (manufactured by Seishin Enterprise Co., Ltd.); Turbo Classifier (manufactured by Nisshin Engineering Co., Ltd.); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron); Elbow Jet (Japanese) Iron Mining Co., Ltd.), Dispersion Separator (Nihon Pneumatic Co., Ltd.); YM Micro Cut (Yasukawa Shoji Co., Ltd.).

Examples of the surface modification device include faculty (manufactured by Hosokawa Micron), mechanofusion (manufactured by Hosokawa Micron), novirta (manufactured by Hosokawa Micron), hybridizer (manufactured by Nara Machine Co., Ltd.), inomizer (manufactured by Hosokawa Micron), theta composer. (Made by Tokuju Seisakusho) and MechanoMill (made by Okada Seiko).

The sieving device used for sieving coarse particles includes the following. Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonator Sieve, Gyro Shifter (Dokuju Seisakusho Co., Ltd.); Vibrasonic System (Dalton Co., Ltd.); Soniclean (Shinto Kogyo Co., Ltd.); Turbo Screener (Turboe Industry Co., Ltd.); Micro shifter (Makino Sangyo Co., Ltd.); circular vibrating screen.

The toner of the present invention may contain an external additive other than the external additive A and the external additive B.

Another preferable external additive is a fine powder produced by vapor phase oxidation of a silicon halogen compound, which is so-called dry process silica or fumed silica. For example, the thermal decomposition oxidation reaction of silicon tetrachloride gas in oxyhydrogen flame is utilized, and the basic reaction formula is as follows.
SiCl ₄ +2H ₂ +O ₂ →SiO ₂ +4HCl

In this manufacturing process, it is possible to obtain a composite fine powder of silica and another metal oxide by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound, and silica also includes them. To do.

Examples of commercially available silica fine powder produced by vapor phase oxidation of a silicon halogen compound include the following. AEROSIL 130, 200, 300, 380, TT600, MOX170, MOX80, COK84 (above, Nippon Aerosil Co., Ltd.) Ca-O-SiLM-5, MS-7, MS-75, HS-5, EH-5 (above, CABOT Co. Company) Wacker HDK N 20, V15, N20E, T30, T40 (above, WACKER-CHEMIE GMBH company) D-C Fine Silica (Dow Corning Co., Ltd.), Francol (Fransil company). However, in the present invention, these can also be preferably used.

<Method for measuring volume resistivity of toner particles and external additives>
As the measurement sample, a sample obtained by press-molding a toner particle or an external additive into a disk shape having a diameter of 24.0 mm and a thickness of 5.0±1.0 mm using a tablet molding machine in an environment of 25° C. is used. .. The pressure during molding is maintained at 30 N for 10 minutes.

The measurement was performed at 1 MH at an applied voltage of 0.7 V using a dielectric measurement system (1260 type+1296 type Solartron).

<Method of measuring zeta potential of external additive B>
The zeta potential of the external additive B was measured using Zetasizer Nano-Zs (manufactured by Sysmex Corporation).

As a dispersion liquid, 0.1 g of the external additive B was added to 9.9 g of an aqueous solution of Triton X-100 (manufactured by Kishida Chemical Co., Ltd.), which was a nonionic surfactant, diluted to 5.0% by mass. Was added and dispersed by an ultrasonic disperser (manufactured by Nippon Rikagaku Kikai Co., Ltd.) for 5 minutes to prepare a dispersion liquid. This dispersion is put into a DTS1060C-Clear Disposable Zeta Cell attached to the above device with a dropper so that air bubbles do not enter. This cell was attached to a measuring instrument, and the zeta potential was measured at 25°C. This measurement was performed and the arithmetic mean value of three times was used as the zeta potential in the present invention.

<Method for quantifying external additive A, external additive B and other external additives>
In a toner in which a plurality of external additives are externally added to toner particles, when measuring the content of each external additive, the external additives are removed from the toner particles, and a plurality of external additives are isolated/ Need to be collected.

Specific methods include, for example, the following methods.
(1) 5 g of toner is put in a sample bottle, and 200 ml of methanol is added.
(2) Disperse the sample for 5 minutes with an ultrasonic cleaner to separate the external additive.
(3) The toner particles and the external additive are separated by suction filtration (10 μm membrane filter). Alternatively, in the case of a magnetic toner, a neodymium magnet may be applied to the bottom of the sample bottle to fix the magnetic toner particles to separate only the supernatant liquid.
(4) The above (2) and (3) are performed until a desired sample amount is obtained.

By the above operation, the externally added external additive is isolated from the toner particles. The collected aqueous solution is put into a centrifuge to separate and collect each external additive for each specific gravity. Then, the solvent is removed, the product is sufficiently dried with a vacuum dryer, and the mass is measured, whereby the content of each external additive can be obtained.

<Method of measuring number average particle diameter of external additive A, external additive B and other external additives>
The number average particle diameters of the organic-inorganic composite fine particles, strontium titanate and other external additives are measured by using a scanning electron microscope “S-4800” (trade name; manufactured by Hitachi Ltd.). Observing the toner to which the organic-inorganic composite fine particles, strontium titanate and other external additives were externally added, and in the field of view magnified up to 200,000 times, 100 external additives A, external additives B and The major axis of the primary particles of other external additives is measured to determine the number average particle diameter. The observation magnification is appropriately adjusted according to the sizes of the external additive A, the external additive B and the other external additives.

<Measurement method of the coverage of the inorganic fine particles on the surface of the organic-inorganic composite fine particles>
Organic-inorganic composite particles can be used as the external additive A in the present invention. At that time, the inorganic fine particle abundance of the organic-inorganic composite particles is measured by XPS (X-ray photoelectron spectroscopy analysis). When the inorganic fine particles present on the surface of the organic-inorganic composite fine particles are silica, silica-derived silicon (hereinafter, Si Calculated from atomic weight. XPS is an analysis method for detecting atoms in a region of several nm or less in the depth direction of the sample surface. Therefore, it is possible to detect the atoms on the surface of the organic-inorganic composite fine particles.

As the sample holder, a 75 mm square platen (equipped with a screw hole having a diameter of about 1 mm for fixing the sample) attached to the apparatus was used. Since the screw hole of the platen penetrates, the hole is closed with a resin or the like to form a recess for powder measurement having a depth of about 0.5 mm. The measurement sample was packed in the recess with a spatula or the like, and scraped off to prepare a sample.

The XPS apparatus and measurement conditions are as follows.

Equipment used: ULVAC-PHI Quantum 2000
Analysis method: Narrow analysis Measurement conditions:
X-ray source: Al-Kα
X-ray condition: 100μ25W15kV
Photoelectron uptake angle: 45°
PassEnergy: 58.70 eV
Measuring range: φ100μm

The measurement was performed under the above conditions.

The analysis method first corrects the peak derived from the C—C bond of the carbon 1s orbital to 285 eV. Then, the amount of Si derived from silica with respect to the total amount of constituent elements is calculated by using the relative sensitivity factor provided by ULVAC-PHI, from the peak area derived from the silicon 2p orbital where the peak top is detected at 100 eV or more and 105 eV or less. To do.

First, the organic-inorganic composite fine particles are measured. In addition, the particles of the inorganic component used when producing the organic-inorganic composite fine particles are measured by the same method. When the inorganic component is silica, the ratio of the amount of Si when the organic-inorganic composite fine particles are measured to the amount of Si when the silica particles are measured is the abundance of the inorganic fine particles on the surface of the organic-inorganic composite fine particles in the present invention. In this measurement, as the silica particles, the sol-gel silica particles (number average particle diameter 120 nm) described in the production example were used for the calculation.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

<Production Example of Toner Particle 1>
-Amorphous polyester resin: 100 parts by mass-Magnetic iron oxide particles: 60 parts by mass-Fischer Tropush wax (C105 manufactured by Sazol Co.): 2 parts by mass-Charge control agent (T-77 manufactured by Hodogaya Chemical Co., Ltd.): 2 parts by mass After pre-mixing the above materials with a Henschel mixer, a twin-screw extruder (trade name: PCM-30, manufactured by Ikegai Iron Works Co., Ltd.) was used so that the melt temperature at the discharge port was 150°C. The temperature was set and the mixture was melt-kneaded.

The obtained kneaded product was cooled, coarsely pulverized with a hammer mill, and then finely pulverized with a pulverizer (trade name: Turbomill T250, manufactured by Turbo Kogyo Co., Ltd.). The finely pulverized powder thus obtained was classified using a multi-division classifier utilizing the Coanda effect to obtain toner particles 1 having a weight average particle diameter (D4) of 7.2 μm.

<Production Example of Toner Particles 2 and 3>
Toner particles 2 and 3 were obtained in the same manner as the toner particle 1 except that the amounts of the amorphous polyester resin, magnetic iron oxide particles, Fischer-Tropsch wax, and charge control agent used were changed as shown in Table 1.

<Production Example of External Additives A-1 to A-5>
As the external additives A-1 to A-5 used in the examples, those prepared according to Example 1 of WO 2013/063291 were prepared. Table 2 shows the physical properties.

<Production Example of External Additive A-6>
The silicon oxide particles are produced by a sol-gel method, and 100 parts by mass of the obtained silicon oxide particles are surface-treated with 10 parts by mass of hexamethylsilazane to give an external additive A-6 having a number average particle size of 110 nm. Got Table 2 shows the physical properties.

<Production Example of External Additive B-1>
Step S101:
The metatitanic acid obtained by the sulfuric acid method was subjected to a deironing bleaching treatment, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, and a desulfurization treatment was performed. Then, the mixture was neutralized to a pH of 5.8 with hydrochloric acid and washed with water by filtration. Water was added to the washed cake to form a TiO ₂ slurry having a concentration of 1.85 mol/L, and then hydrochloric acid was added to adjust the pH to 1.0 to perform peptization treatment.

Step S102:
The desulfurized and peptized metatitanic acid was used as TiO ₂ and 1.88 mol was sampled and charged into a 3 L reaction vessel.

Step S103:
2.16 mol of an aqueous strontium chloride solution was added to the peptized metatitanic acid slurry, and S
The rO/TiO ₂ molar ratio was adjusted to 1.15.

Step S104:
The TiO ₂ concentration was adjusted to 1.039 mol/L.

Step S105:
Next, while stirring and mixing, the mixture was heated to 90° C., and then 10 mol/L sodium hydroxide aqueous solution 4
40 mL was added over 45 minutes.

Step S106:
The reaction was completed by continuing stirring at a temperature of 95° C. for 1 hour.

Step S107:
The reaction slurry was cooled to 50° C., hydrochloric acid was added until the pH reached 5.0, and stirring was continued for 20 minutes.

Step S108:
The obtained precipitate was washed by decantation, filtered and separated, and then dried in the atmosphere at 120° C. for 8 hours.

Step S109:
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron Corp.). The treatment was performed at a treatment temperature of 30° C. and a rotary treatment blade of 90 m/sec for 10 minutes.

Step S110:
Further, hydrochloric acid was added to the dried product until pH became 0.1, and stirring was continued for 1 hour. The obtained precipitate was washed by decantation.

Step S111:
The slurry containing the precipitate was adjusted to 40° C., and hydrochloric acid was added to adjust the pH to 2.5.

Step S112:
Next, 4.6% by mass of isobutyltrimethoxysilane and 4.6% by mass of trifluoropropyltrimethoxysilane with respect to the solid content were mixed by stirring for 1 hour and then added, and the mixture was kept stirring for 10 hours.

Step S113:
A 5 mol/L sodium hydroxide solution was added to adjust the pH to 6.5, and stirring was continued for 1 hour.

Step S114:
The cake obtained by filtration and washing was dried in the atmosphere at 120° C. for 8 hours to obtain an external additive B-1. Table 3 shows the physical properties.

<Production Example of External Additive B-2>
In step S103, 2.54 mol of an aqueous strontium chloride solution is added, and SrO is added.
/TiO ₂ molar ratio was set to 1.35, and in step S112, instead of "4.6 mass%" trifluoropropyltrimethoxysilane, "6.9 mass%" trifluoropropyltrimethoxysilane was used. An external additive B-2 was obtained in the same manner as in the production example of the external additive B-1 except that silane was used. Table 3 shows the physical properties.

<Production Example of External Additive B-3>
The processing time in step S109 was changed from “10 minutes” to “15 minutes”, and in step S112, “4.6% by mass of isobutyltrimethoxysilane and 4.6% by mass of trifluoro with respect to the solid content was added. Propyltrimethoxysilane was added with stirring and mixing for 1 hour and then maintained with stirring for 10 hours, instead of "4.4% by mass of isobutyltriethoxysilane and 4.0% by mass of trifluoropropyltrimethoxy based on solid content. An external additive B-3 was obtained in the same manner as in the production example of the external additive B-1 except that silane was added after stirring and mixing for 3 hours, and the mixture was stirred and held for 8 hours. Table 3 shows the physical properties.

<Production Example of External Additive B-4>
In step S104, an external additive B-4 was obtained in the same manner as in the production example of the external additive B-1 except that the TiO ₂ concentration was adjusted to 0.945 mol/L. Table 3 shows the physical properties.

<Production Example of External Additive B-5>
In step S104, an external additive B-5 was obtained in the same manner as in the production example of the external additive B-1 except that the TiO ₂ concentration was adjusted to 0.938 mol/L. Table 3 shows the physical properties.

<Production Example of External Additive B-6>
In Step S112, instead of “4.6% by mass of isobutyltrimethoxysilane and 4.6% by mass of trifluoropropyltrimethoxysilane with respect to the solid content is added after stirring and mixing for 1 hour”. In the same manner as in the production example of the external additive B-1, except that 10.0% by mass of isobutyltrimethoxysilane was added to the solid content and kept stirring for 5 hours. Got 6. Table 3 shows the physical properties.

<Production Example of External Additive B-7>
In Step S112, instead of “4.6% by mass of isobutyltrimethoxysilane and 4.6% by mass of trifluoropropyltrimethoxysilane with respect to the solid content is added after stirring and mixing for 1 hour”. External additive B-7 was obtained in the same manner as in the production example of external additive B-1 except that "nothing was added and the mixture was stirred and held for 1 hour". Table 3 shows the physical properties.

<Production Example of External Additive B-8>
A crushed product of synthetic rutile ore, which is a raw material, and coke were mixed, placed in a fluidized bed chlorination furnace heated to a temperature of about 1000° C., and exothermically reacted with chlorine gas supplied to obtain crude titanium tetrachloride .. Impurities were separated and purified from the obtained crude titanium tetrachloride to obtain a titanium tetrachloride aqueous solution. While maintaining this titanium tetrachloride aqueous solution at room temperature, sodium hydroxide aqueous solution was added to adjust the pH to 7.0 to precipitate colloidal titanium hydroxide, and subsequently aged at a temperature of 65° C. for 4 hours. Slurry titanium oxide mother particles having a rutile nucleus were used. Sulfuric acid was added to this slurry to adjust the pH to 3, then 5.5 mass% of isobutyltrimethoxysilane and 5.5 mass% of trifluoropropyltrimethoxysilane were added to the solid content, and the temperature was adjusted to 60 over 1 hour. The temperature was raised to °C. Then, filtration and washing were performed, and the obtained wet cake was heat-treated at a temperature of 120° C. for one day and pulverized to obtain an external additive B-8. Table 3 shows the physical properties.

<Production Example of External Additive B-9>
An aqueous solution of NaOH having a concentration of 0.92 N was kept at about 90° C., and an aqueous solution of TiCl ₄ (TiCl ₄ concentration 0.485 mol/l) heated and kept at 40° C., and undissolved components were removed in advance and the mixture was kept at about 95° C. BaCl ₂ /NaOH aqueous solution (BaCl ₂ concentration 0.265 mol/liter, NaOH concentration 2.73 mol/liter) was continuously supplied into the reaction vessel. After the temperature of the mixed aqueous solution was kept constant at about 90° C., 10.0 mass% of isobutyltrimethoxysilane was added to the solid content, and the mixture was stirred and held for 1 hour to produce particulate barium titanate. After aging, decantation was performed to separate the supernatant and the precipitate, and the solid reaction product was recovered by washing. The recovered solid reaction product was dried by heating at 100° C. in the atmosphere. Furthermore, it heated at 900 degreeC for 30 minutes, and obtained the external additive B-9. Table 3 shows the physical properties.

<Production Example of Toner 1>
Hydrophobic silica surface-treated with hexamethyldisilazane, wherein 1.0 parts by mass of the external additive A-1, 0.1 parts by mass of the external additive B-1, and 100.0 parts by mass of the toner particles 1 are used. 0.5 parts by mass of fine powder (number average particle diameter of primary particles: 10 nm) was added, and mixed with a Henschel mixer for 2 minutes at 3200 rpm to obtain toner 1. Table 4 shows the physical properties of Toner 1.

<Production Example of Toners 2 to 21>
The same procedure as in Toner 1 except that the toner particles used and the type and addition amount of the external additive A, the type and addition amount of the external additive B, and the addition amount of the hydrophobic silica fine powder are changed as shown in Table 3. , Toners 2 to 21 are obtained. Table 4 shows the physical properties of the obtained toners 2 to 21.

[Example 1]
The toner 1 was evaluated in high speed printing as follows. The evaluation results are shown in Table 5.

<Evaluation of toner durability>
An HP LaserJet Enterprise M609dn was used by modifying the process speed to 410 mm/sec.

400 g of Toner 1 was filled in a predetermined process cartridge. After being left in a high temperature and high humidity environment (32.5° C., 85% RH) for 24 hours, evaluation was performed.

Using the above device, a horizontal line pattern with a printing rate of 1% is set as 2 sheets/1 job, and the next job is started after the machine is temporarily stopped between jobs. An image drawing test was carried out. The image density on the 10000th sheet was measured, and at the same time, it was confirmed whether or not an image defect occurred. The image density was measured by using a Macbeth densitometer (manufactured by Macbeth Co.), which is a reflection densitometer, using an SPI filter to measure the reflection density of a solid black image of a circle of 5 mm.
A: 1.30 or more B: 1.20 or more and less than 1.30 C: 1.10 or more and less than 1.20 D: 1.00 or more and less than 1.10 E: less than 1.00

<Evaluation of halftone step unevenness of toner>
An HP LaserJet Enterprise M609dn was used by modifying the process speed to 410 mm/sec.

400 g of Toner 1 was filled in a predetermined process cartridge. The sample was left in a low temperature and low humidity environment (15.0° C., 10% RH) for 24 hours and then evaluated.

Using the above device, the horizontal line pattern with a print rate of 1% is set as 2 sheets/1 job, and the machine is set to stop once between jobs before the next job starts. After the image was printed, a halftone image with a toner loading of 0.20 mg/cm ² was output, and a SPID filter was used with a Macbeth densitometer (manufactured by Macbeth Co.) which is a reflection densitometer. The reflection density was measured every 3 cm in the longitudinal direction of the paper. The difference between the maximum value and the minimum value of the obtained density was used as an index of step unevenness.
A: Difference between maximum and minimum density is less than 0.04 B: Difference between maximum and minimum density is 0.04 to less than 0.07 C: Difference between maximum and minimum density is 0. 07 or more and less than 0.10 D: difference between maximum and minimum density values is 0.10 or more and less than 0.13 E: difference between maximum and minimum density values is 0.13 or more

<Evaluation of toner developability>
An HP LaserJet Enterprise M609dn was used by modifying the process speed to 410 mm/sec.

400 g of Toner 1 was filled in a predetermined process cartridge. After being left in a high temperature and high humidity environment (32.5° C., 85% RH) for 24 hours, evaluation was performed.

Using the above device, the horizontal line pattern with a print rate of 1% is set as 2 sheets/1 job, and the machine is set to stop once between jobs before the next job starts. An image drawing test was carried out. The image density on the 100th sheet was measured, and at the same time, it was confirmed whether or not an image defect occurred. The image density was measured by using a Macbeth densitometer (manufactured by Macbeth Co.), which is a reflection densitometer, using an SPI filter to measure the reflection density of a solid black image of a circle of 5 mm.
A: 1.40 or more B: 1.30 or more and less than 1.40 C: 1.20 or more and less than 1.30 D: 1.10 or more and less than 1.20 E: less than 1.10.

[Examples 2 to 17]
Toners 2 to 17 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5.

[Comparative Examples 1 to 4]
Toners 18 to 21 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5.

Claims (8)

A toner containing toner particles and an external additive, wherein the external additive contains an external additive A and an external additive B, and the number average particle diameter of the external additive A is 70 nm or more and 250 nm or less, When the zeta potential of the external additive B is -45.0 mV or more and -10.0 mV or less, the volume resistivity of the external additive A is TA, and the volume resistivity of the external additive B is TB, TA is 5.0×10 ³ Ω·m or more and 9.0×10 ³ Ω·m or less, and the following formula 4.70≦TA/TB≦10.00
Toner characterized by satisfying. When the volume resistivity of the toner particles is TT, TT is 2.0×10 ³ Ω·m or more and 5.0×10 ³ Ω·m or less, and TT/TB is less than 4.70. Item 1. The toner according to Item 1. The toner according to claim 1, wherein the particle diameter of the external additive B is 10 nm or more and 80 nm or less. The content of the external additive A is 0.2 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particles, and the content of the external additive B is less than the content of the external additive A. The toner according to any one of claims 1 to 3, which is 0.02 times or more and 1.00 times or less. The toner according to claim 1, wherein TB is 9.0×10 ² Ω·m or more and 1.5×10 ³ Ω·m or less. The toner according to any one of claims 1 to 5, wherein the external additive B is at least one selected from the group consisting of strontium titanate, barium titanate, calcium titanate, and titanium oxide. The external additive B is a particle having a partial structure a represented by the following formula (1) on the surface of the particle,
CF ₃ -Si-O _3/2 formula (1)
7. The presence ratio of the partial structure a on the surface of the external additive B measured by X-ray photoelectron spectroscopy (XPS) is 0.110 or more and 0.220 or less. The toner according to item. The toner according to any one of claims 1 to 7, wherein the external additive A is organic-inorganic composite particles.