JP2018141956A - toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner that, even when the toner with high circularity is used for a long term, is excellent in developability and prevents the occurrence of fogging and member contamination.SOLUTION: A toner includes toner particles and an external additive. The external additive contains strontium titanate particles; the average circularity of toner is 0.935 or more and 0.995 or less; the number average particle diameter of the primary particles of the strontium titanate particles is 10 nm or more and 60 nm or less; when the Bragg angle is θ, in an X-ray diffraction spectrum of CuKα obtained when 2θ is within a range of 10° or more and 90° or less, the strontium titanate particles have peaks within ranges of 39.700°±0.150° and 46.200°±0.150°, respectively; the ratio of an area Sb of the peak within a range of 46.200°±0.150° to an area Sa of the peak within a range of 39.700°±0.150° is 1.80 or more and 2.30 or less.SELECTED DRAWING: None

Description

  The present invention relates to a toner used in an image forming method such as electrophotography.

Electrophotographic image forming apparatuses are required to have higher speed, longer service life, energy saving, and downsizing. To meet these demands, toners must be improved in various performances. It has been. In particular, for toner, further improvement in quality stability is required from the viewpoint of extending the life.
In particular, in order to prolong the service life, it is important that the quality does not change greatly even after repeated use over a long period of time, and various toners and external additives have been proposed.
For example, in order to maintain good developability even after repeated use over a long period of time, a smooth toner having a high degree of circularity is often used. This is probably because toner with a high degree of circularity is likely to roll, so that the toner surface can be charged uniformly. On the other hand, toner with a high degree of circularity tends to be in a charge-up state where it is excessively charged. Therefore, as one means for controlling the chargeability of toner having a high degree of circularity, there has been a method of stabilizing the chargeability of the toner by using an external additive as a resistance adjusting agent.
As a resistance adjusting agent that satisfactorily adjusts charging of toner having a high degree of circularity, strontium titanate particles, which are medium resistance materials, have been used.
The shape of the strontium titanate particles used as the external additive is a hexahedral shape and has a flat surface in many cases. When the strontium titanate particles have a flat surface, the contact area with the toner particles is increased, so that charge transfer is easily performed between the toner particles and the strontium titanate particles. Therefore, even if the toner particles are in a charge-up state due to frictional charging, the toner particles can be uniformly charged by diffusing the electric charge. As a result, excellent developability was able to be exhibited from the beginning of the durability.
However, the conventional strontium titanate particles may move from the toner particles due to repeated rubbing in the developing machine in repeated use over a long period of time. Fluctuated, and there was a tendency that developability was liable to deteriorate. The transition refers to a phenomenon in which the external additive moves from the toner particles to another toner particle or another member. That is, it means a phenomenon in which the external additive does not stay on the toner particles.

Patent Document 1 proposes that the environmental characteristics and charging characteristics of the toner can be improved by externally adding strontium titanate particles with controlled SrO / TiO ₂ (molar ratio) to the toner particles. .
Patent Document 2 proposes that the suppression of image flow in a high-temperature and high-humidity environment can be improved by externally adding strontium titanate particles whose crystal structure and shape are controlled to toner particles.
Patent Document 3 proposes that the flowability and moisture resistance of the toner can be improved by externally adding strontium titanate particles having a controlled particle size distribution to the toner particles.

JP2015-137208A Japanese Patent No. 4944980 JP 2003-277054 A

According to the technique described in the above patent document, certain effects are confirmed with respect to the environmental characteristics, charging characteristics, and image flow suppression of the toner. However, there has been room for further study in the case of repeated use for a long time in combination with toner having a high degree of circularity.
The present invention provides a toner in which the conventional problems are solved.
That is, the present invention provides a toner that has excellent developability and can suppress the occurrence of fogging and member contamination even when a toner with a high degree of circularity is used repeatedly for a long period of time.

The present invention is a toner containing toner particles and an external additive,
The external additive contains strontium titanate particles,
The average circularity of the toner is 0.935 or more and 0.995 or less,
The strontium titanate particles are
The number average particle size of the primary particles is 10 nm or more and 60 nm or less,
The strontium titanate particles have 39.700 ° ± 0.150 ° and 46.200 ° in the X-ray diffraction spectrum of CuKα obtained when the Bragg angle is θ and 2θ ranges from 10 ° to 90 °. Each has a peak in the range of ± 0.150 °,
Sa is the peak area at 39.700 ° ± 0.150 °,
When the peak area at 46.200 ° ± 0.150 ° is Sb,
A toner having Sb / Sa of 1.80 or more and 2.30 or less.

  According to the present invention, it is possible to provide a toner that has excellent developability and can suppress the occurrence of fogging and member contamination even when a toner with a high degree of circularity is repeatedly used for a long period of time.

Transmission electron micrograph of strontium titanate particles 1 (drawing substitute photo)

In the present invention, the description of “XX or more and XX or less” or “XX to XX” representing a numerical range means a numerical range including a lower limit and an upper limit as endpoints unless otherwise specified.
As described above, use of strontium titanate particles is one of the means for controlling the chargeability of toner having a high degree of circularity.
By externally adding strontium titanate particles having a hexahedral shape, the contact area between the strontium titanate particles and the toner particles increases, so that the charge is diffused even when the toner particles are in a charge-up state due to frictional charging. The toner can be uniformly charged. As a result, it was possible to achieve excellent developability and suppression of fog from the beginning of repeated use.
However, in the case of conventional strontium titanate particles, the strontium titanate particles may migrate from the toner particles due to rubbing in the developing machine in repeated use over a long period of time. There was a tendency that developability and fogging deteriorated.

Therefore, the present inventors tried to reduce the particle size of the strontium titanate particles in order to suppress the migration of the strontium titanate particles from the toner particles.
It was thought that if the diameter was reduced, the transition could be suppressed even when repeatedly rubbed in the developing machine. Further, if the diameter is further reduced, it is easy to roll on the surface of the toner particles.
In fact, by reducing the particle size of the strontium titanate particles, the migration of the strontium titanate particles can be suppressed even when subjected to repeated rubbing in the developing machine for repeated use over a long period of time.
However, it was found that when strontium titanate particles having a small particle diameter were applied to a smooth toner having a high degree of circularity, the surface of the toner particles was likely to be damaged. In some cases, it was found that the toner particles were cracked. When toner particle cracking occurs, the toner charge distribution is affected.
In other words, when strontium titanate particles having a small particle diameter are applied to a smooth toner having a high degree of circularity, the charge distribution fluctuates due to cracking of the toner particles, the developability of the toner decreases, and fogging occurs. The occurrence was found to increase. It was also found that member contamination due to cracked toner particles tends to occur.
As a result of repeated studies, the present inventors have developed a small-sized strontium titanate particle having a specific profile in an X-ray diffraction spectrum as an external additive, so that development can be achieved even in repeated use over a long period of time. The present invention has been found to be excellent in performance and can suppress the occurrence of fogging and member contamination.

That is, the toner of the present invention is a toner containing toner particles and an external additive,
The external additive contains strontium titanate particles,
The average circularity of the toner is 0.935 or more and 0.995 or less,
The strontium titanate particles are
The number average particle size of the primary particles is 10 nm or more and 60 nm or less,
The strontium titanate particles have 39.700 ° ± 0.150 ° and 46.200 ° in the X-ray diffraction spectrum of CuKα obtained when the Bragg angle is θ and 2θ ranges from 10 ° to 90 °. Each has a peak in the range of ± 0.150 °,
Sa is the peak area at 39.700 ° ± 0.150 °,
When the peak area at 46.200 ° ± 0.150 ° is Sb,
Sb / Sa is 1.80 or more and 2.30 or less.

The strontium titanate particles are 39.700 ° ± 0.150 ° and 46.200 ° ± in the X-ray diffraction spectrum of CuKα obtained when 2θ is 10 ° or more and 90 ° or less when the Bragg angle is θ. Each has a peak in the range of 0.150 °.
Strontium titanate having a peak at this position has a perovskite structure belonging to a cubic system, and peaks in the ranges of 39.700 ° ± 0.150 ° and 46.200 ° ± 0.150 ° are Miller indices (111), respectively. And diffraction peaks derived from the (200) lattice plane.
In general, particles belonging to a cubic system easily adopt a hexahedral shape as the appearance shape of the particles, and the strontium titanate particles also have (100) and (200) planes corresponding to the hexahedral shape in the manufacturing process. grow up.
However, as a result of our study, it has been found that when strontium titanate particles having a (200) plane corresponding to the hexahedral shape and a (111) plane corresponding to the apex direction are used, good characteristics are exhibited.
As a result of detailed examination, when the peak area at 39.700 ° ± 0.150 ° is Sa and the peak area at 46.200 ° ± 0.150 ° is Sb, Sb / Sa is 1 It was found that a remarkable effect was exhibited when the ratio was from .80 to 2.30. The Sb / Sa is preferably 1.80 or more and 2.25 or less.

The number average particle diameter of primary particles of strontium titanate particles is 10 nm or more and 60 nm or less. The number average particle diameter is preferably 10 nm or more and 50 nm or less.
When the Sb / Sa and the number average particle diameter are in the above ranges, even when the toner having a high degree of circularity is used repeatedly for a long period of time, the migration of the strontium titanate particles from the toner particles and the cracking of the toner particles are suppressed. can do. As a result, the toner is excellent in developability, and the occurrence of fogging and member contamination is suppressed.
The number average particle size and Sb / Sa of the primary particles of the strontium titanate particles are controlled by adjusting the molar ratio of the raw materials of the strontium titanate particles and the manufacturing conditions such as dry mechanical treatment. be able to.

The Sr / Ti (molar ratio) of the strontium titanate particles is preferably 0.70 or more and 0.85 or less, and more preferably 0.75 or more and 0.83 or less.
When the ratio of Sr / Ti (molar ratio) is in the above range, the proportion of Ti that is close to negative chargeability is increased, so that the charge distribution is likely to be sharp and the uniformity of the halftone image is improved.
Sr / Ti (molar ratio) can be controlled by adjusting the molar ratio of the raw material of the strontium titanate particles and the production conditions.

The average circularity of the primary particles of the strontium titanate particles is preferably 0.700 or more and 0.920 or less, and more preferably 0.790 or more and 0.920 or less.
When the average circularity is in the above range, the strontium titanate particles are easily crushed on the toner particles, and the coverage with the strontium titanate particles is easily increased.
As a result, charging of the toner is likely to start from the beginning of repeated use, and an effect is easily obtained for developability and fog suppression at the beginning of repeated use. The average circularity of the primary particles of the strontium titanate particles can be controlled by adjusting the production conditions.

The strontium titanate particles preferably have a methanol concentration of 60% by volume or more and 95% by volume or less when the light transmittance at a wavelength of 780 nm is 50% in a wettability test with respect to a methanol / water mixed solvent. % To 95% by volume is more preferable.
When the methanol concentration is in the above range, the developability after standing in a high temperature and high humidity environment is easily maintained.
The wettability of the strontium titanate particles to the methanol / water mixed solvent can be controlled by adjusting the surface treatment conditions of the strontium titanate particles.

The coverage of the toner surface with strontium titanate particles, measured by an X-ray photoelectron spectrometer (ESCA), is preferably 5.0 area% or more and 20.0 area% or less, and 8.0 area% or more. It is more preferable that it is 20.0 area% or less.
When the coverage is in the above range, the toner is likely to be charged from the early stage of repeated use, and an effect can be easily obtained in terms of developability and fog suppression at the early stage of repeated use. The coverage can be controlled by adjusting the shape and amount of strontium titanate particles, the production conditions, and the properties of the toner particles.

The average circularity of the toner is 0.935 or more and 0.995 or less. The average circularity of the toner is preferably 0.940 or more and 0.990 or less.
When the average circularity of the toner is in the above range, developability can be improved and fogging can be suppressed. The average circularity of the toner can be controlled by adjusting the manufacturing conditions.

The glass transition temperature (Tg) of the toner is preferably 50 ° C. or higher and 70 ° C. or lower, and more preferably 52 ° C. or higher and 68 ° C. or lower.
When the glass transition temperature (Tg) is in the above range, the strontium titanate particles are easily dispersed on the toner particle surface. That is, since a dispersed state closer to primary particles can be formed, the coverage of strontium titanate particles can be increased. As a result, the developability can be further improved in repeated use over a long period of time, and the occurrence of fogging and member contamination can be suppressed at a higher level.
The glass transition temperature (Tg) can be controlled by adjusting the composition of the binder resin constituting the toner.

In order to produce the perovskite-type strontium titanate particles, it is preferable to use a normal pressure heating reaction method in which a reaction is performed at normal pressure instead of hydrothermal treatment using a pressurized container.
A mineral acid peptized product of a hydrolyzate of a titanium compound is used as the titanium oxide source, and a water-soluble acidic compound is used as the strontium source. And the method of making it react, adding alkaline aqueous solution to those liquid mixture at 60 degreeC or more, and then acid-treating can be illustrated.
Further, as a method for controlling the shape of the strontium titanate particles, there is also a method of performing a mechanical treatment by a dry method, and the value of the Sb / Sa can be controlled by this method.

Hereinafter, the atmospheric pressure heating reaction method will be described.
As the titanium oxide source, a mineral acid peptized product of a hydrolyzate of a titanium compound may be used.
Preferably, the metatitanic acid obtained by the sulfuric acid method and having a SO ₃ content of 1.0% by mass or less, more preferably 0.5% by mass or less is adjusted to pH 0.8 to 1.5 with hydrochloric acid. Use peptized. Thereby, strontium titanate fine particles having a good particle size distribution can be obtained.
On the other hand, as the strontium source, strontium nitrate, strontium chloride, or the like can be used. As the alkaline aqueous solution, a caustic alkali can be used, and among them, a sodium hydroxide aqueous solution is preferable.
In the production method, factors affecting the particle size of the obtained strontium titanate particles include the mixing ratio of the titanium oxide source and the strontium source, the titanium oxide source concentration at the initial stage of the reaction, the temperature when adding the alkaline aqueous solution, and the addition Speed and so on. These factors can be appropriately adjusted in order to obtain strontium titanate particles having a target particle size and particle size distribution. In addition, in order to prevent the production | generation of strontium carbonate in a reaction process, it is preferable to make it react in nitrogen gas atmosphere and to prevent mixing of a carbon dioxide gas.

The mixing ratio of the titanium oxide source and the strontium source at the time of reaction is preferably 0.90 or more and 1.40 or less, more preferably 1.05 or more and 1.20 or less, as Sr / Ti (molar ratio). .
Since the strontium source has high solubility in water, the titanium oxide source has low solubility in water. Therefore, when Sr / Ti (molar ratio) is less than 0.90, the reaction product is not only strontium titanate. Unreacted titanium oxide tends to remain.
The concentration of the titanium oxide source at the initial stage of the reaction is preferably 0.050 mol / L or more and 1.300 mol / L or less, more preferably 0.080 mol / L or more and 1.200 mol / L as TiO _2. It is as follows.
By increasing the concentration of the titanium oxide source at the initial stage of the reaction, the number average particle diameter of the primary particles of the strontium titanate particles can be reduced.

The higher the temperature at which the aqueous alkali solution is added, the better the crystallinity of the product is obtained. However, a pressure vessel such as an autoclave is necessary at 100 ° C. or higher, and practically in the range of 60 ° C. or higher and 100 ° C. or lower. Is appropriate.
In addition, as the addition rate of the aqueous alkali solution is decreased, strontium titanate particles having a larger particle size are obtained, and as the addition rate is increased, strontium titanate particles having a smaller particle size are obtained. The addition rate of the alkaline aqueous solution is preferably 0.001 equivalent / h or more and 1.2 equivalent / h or less, more preferably 0.002 equivalent / h or more and 1.1 equivalent / h or less with respect to the charged raw material. It is. These can be appropriately adjusted according to the particle diameter to be obtained.

Next, the acid treatment will be described. When the mixing ratio of the titanium oxide source and the strontium source exceeds 1.40 in Sr / Ti (molar ratio), the unreacted strontium source remaining after the completion of the reaction reacts with carbon dioxide in the air, and strontium carbonate Etc., and the particle size distribution tends to be wide. Further, when impurities such as strontium carbonate remain on the surface, it becomes difficult to uniformly coat the surface treatment agent due to the influence of the impurities during surface treatment for imparting hydrophobicity. Therefore, after adding the alkaline aqueous solution, acid treatment may be performed to remove the unreacted strontium source.
In the acid treatment, it is preferably adjusted to pH 2.5 or more and 7.0 or less using hydrochloric acid, and more preferably adjusted to pH 4.5 or more and 6.0 or less.
As the acid, in addition to hydrochloric acid, nitric acid, acetic acid and the like can be used for the acid treatment. However, when sulfuric acid is used, strontium sulfate having low water solubility is likely to be generated.

Next, shape control will be described. In order to obtain the shape of the strontium titanate particles, a dry mechanical treatment may be given as an example.
For example, a hybridizer (manufactured by Nara Machinery Co., Ltd.), Nobilta (manufactured by Hosokawa Micron Corporation), mechano-fusion (manufactured by Hosokawa Micron Corporation), Hiflex glal (manufactured by Earth Technica Co., Ltd.) or the like can be used. By treating strontium titanate particles with these apparatuses, Sb / Sa can be easily controlled to 1.80 or more and 2.30 or less.
When the shape of strontium titanate particles is controlled by mechanical treatment, fine powder of strontium titanate particles may be generated. In order to remove the fine powder, it is preferable to perform an acid treatment after the mechanical treatment. In the acid treatment, it is preferable to adjust the pH to 0.1 or more and 5.0 or less using hydrochloric acid. As the acid, in addition to hydrochloric acid, nitric acid, acetic acid and the like can be used for the acid treatment. The mechanical treatment for controlling the shape of the strontium titanate particles is preferably performed before the surface treatment of the strontium titanate particles.

Strontium titanate particles are used for hydrophobic control such as inorganic oxides such as SiO ₂ and Al ₂ O ₃ , titanium coupling agents, silane coupling agents, silicone oils, and fatty acid metal salts in order to adjust charging and improve environmental stability. Surface treatment with an agent is recommended.
As the silane coupling agent, a silane coupling agent into which a functional group such as an amino group or fluorine is introduced may be used.
Examples of the fatty acid metal salt include zinc stearate, sodium stearate, calcium stearate, zinc laurate, aluminum stearate, and magnesium stearate. The same effect can be obtained with stearic acid, which is a fatty acid.
Examples of the surface treatment method include a wet method in which a hydrophobizing agent is dissolved or dispersed in a solvent, strontium titanate particles are added therein, and the solvent is removed while stirring.
Alternatively, a dry method may be used in which the treatment agent and strontium titanate particles are directly mixed and treated with stirring.

  The content of strontium titanate particles is preferably 0.05 parts by mass or more and 5.0 parts by mass or less, and 0.1 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particles. It is more preferable.

The method for producing the toner particles is not particularly limited as long as the toner can be controlled so that the average circularity of the toner is 0.935 or more and 0.995 or less. For example, a method of 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 can be mentioned. Further, a pulverization method may be used, and toner particles obtained by the pulverization method may be formed into a heat sphere to adjust the average circularity to the above range.
Among these, the suspension polymerization method is preferable. The toner particles produced using the suspension polymerization method have high transferability because the individual particles are substantially spherical and the distribution of the charge amount is relatively uniform.
In the suspension polymerization method, a polymerizable monomer composition containing a polymerizable monomer capable of forming a binder resin, a colorant and a wax is dispersed in an aqueous medium, and the polymerizable monomer composition is dispersed. Then, toner particles are produced by polymerizing the polymerizable monomer in the particles.
The toner particles may be toner particles having a core and a shell layer present on the surface of the core. By adopting such a structure, it is possible to suppress charging failure due to the core oozing onto the surface of the toner particles.
The shell layer preferably contains at least one selected from the group consisting of a polyester resin, a styrene-acrylic copolymer, and a styrene-methacrylic copolymer, and more preferably contains a polyester resin.
The amount of the resin that forms the shell layer 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 10.10 parts by mass or less with respect to 100 parts by mass of the resin that forms the core. 0 parts by mass or less.

When a polyester resin is used for the shell layer, the externally added strontium titanate particles are easily loosened on the toner particle surface, and the strontium titanate particles are easily dispersed. As a result, developability is further improved in repeated use over a long period of time, and the occurrence of fogging and member contamination can be further suppressed.
It is preferable that the weight average molecular weight of this polyester resin is 5000 or more and 50000 or less. When the weight average molecular weight is in the above range, the dispersibility of the strontium titanate particles on the surface of the toner particles can be improved more easily.

Examples of the polymerizable monomer that can form the binder resin include vinyl-based polymerizable monomers. Specifically, the following can be exemplified.
Styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, styrene derivatives such as 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 Methacrylic polymerizable monomers such as n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate; methylene aliphatic monocarboxylic esters; And vinyl esters such as nyl, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl formate.

The toner particles may contain a charge control agent. As the charge control agent, one that controls toner particles to be negatively charged and one that controls toner particles to be positively charged are known, and one or two or more kinds are used depending on the type and use of the toner. be able to.
Examples of controlling toner particles to be negatively charged include the following.
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 Such as phenol derivatives. These can be used alone or in combination.
Among these, a metal complex or a metal salt of an aromatic hydroxycarboxylic acid capable of obtaining stable charging performance is preferable.
On the other hand, examples of toner particles that are positively charged include the following.
Modified products with nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and analogs thereof; onium salts such as phosphonium salts And these lake pigments; triphenylmethane dye and these lake pigments (as rake agents, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid, ferrocyanide) Compounds); metal salts of higher fatty acids. These can be used alone or in combination.
Of these, nigrosine compounds and quaternary ammonium salts are preferred.
Since the strontium titanate particles are positively charged, it is more preferable to use a charge control agent that controls the toner particles to be negatively charged because the electrostatic adhesion between the toner particles and the strontium titanate particles is increased.
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 or binder resin capable of generating the binder resin.

It is also a preferred aspect to use a charge control resin. When the toner particles contain a charge control resin, the negative chargeability of the toner particle surfaces is improved. As a result, the electrostatic adhesion to strontium titanate particles, which are positively charged, is increased, so that the strontium titanate particles are less likely to migrate from the toner particles. It becomes easy to suppress the occurrence of contamination.
As the charge control resin, a polymer having a sulfonic acid functional group is preferable. The polymer having a sulfonic acid functional group is a polymer having a sulfonic acid group, a sulfonic acid group, or a sulfonic acid ester group. Of these, a polymer having a sulfonic acid group is preferable.
Specifically, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 2-methacrylamide-2-methylpropane sulfonic acid, vinyl sulfonic acid, a homopolymer of monomers such as methacryl sulfonic acid, or Examples thereof include a copolymer of the monomer and another monomer. Moreover, what made the sulfonic acid group of this polymer into the sulfonate group, and what was esterified can also be used. The glass transition temperature (Tg) of the charge control resin is preferably 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 or binder resin capable of generating the binder resin. In addition, the charge control resin can further improve the charged state of the toner particles when used in combination with a water-soluble polymerization initiator.

The amount of carbon atoms present on the surface of the toner particles measured by the X-ray photoelectron spectrometer is A (atomic%), and the amount of sulfur atoms present on the surface of the toner particles measured by the X-ray photoelectron spectrometer is E. When (atomic%), E / A preferably satisfies the following formula (1), and more preferably satisfies the following formula (1) ′.
E / A can be adjusted, for example, by incorporating the charge control resin into toner particles.
3 × 10 ⁻⁴ ≦ E / A ≦ 50 × 10 ⁻⁴ (1)
5 × 10 ⁻⁴ ≦ E / A ≦ 30 × 10 ⁻⁴ (1) ′
By setting E / A within the above range, the electrostatic adhesion between the toner particles and the strontium titanate particles is further increased, and the strontium titanate particles are less likely to migrate from the toner particles. Moreover, since it is excellent also in the function which adjusts a resistance value, developability is improved more and it becomes easy to suppress generation | occurrence | production of a fog and member contamination.

The toner particles may contain a wax. Examples of the wax include the following.
Petroleum waxes and derivatives thereof such as paraffin wax, microcrystalline wax and petrolatum; montan wax and derivatives thereof; hydrocarbon waxes and derivatives thereof according to the Fischer-Tropsch process; polyolefin waxes and derivatives thereof such as polyethylene and polypropylene; carnauba waxes and Natural waxes such as candelilla wax and derivatives thereof; higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid; acid amide waxes; ester waxes.
Derivatives include oxides, block copolymers with vinyl monomers, and graft-modified products.
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 or binder resin capable of generating the binder resin. It is more preferable that it is 0.0 mass part or more and 10.0 mass parts or less.

The toner particles may contain a colorant.
Examples of the black colorant include carbon black, a magnetic material, and those that are toned in black using yellow, magenta, and cyan colorants described below.
Examples of 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.
Examples of the magenta colorant 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. And CI Pigment Bio Red 19.
Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and 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 alone or in combination, and further in a solid solution state.
The colorant may be selected from the viewpoints 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 or binder resin capable of generating the binder resin.

The toner particles can also be made into magnetic toner particles by containing a magnetic material as a colorant. Magnetic materials 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, Examples include alloys with metals such as tungsten and vanadium, and mixtures thereof.
The magnetic body is preferably a magnetic body whose surface is modified.
When a magnetic toner is prepared by a polymerization method, it is preferable that the toner is subjected to a 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 diameter of the magnetic material is preferably 2.0 μm or less, and 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, and 40 parts by mass or more and 150 parts by mass with respect to 100 parts by mass of the polymerizable monomer or binder resin capable of generating the binder resin. It is more preferable that the amount is not more than parts.

On the other hand, an example of a production method for producing toner particles by a pulverization method will be described below.
In the raw material mixing step, a predetermined amount of binder resin, colorant, wax and the like are mixed and mixed as materials constituting the toner particles.
Examples of the mixing apparatus include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, an FM mixer, a nauter mixer, and a mechano-hybrid (manufactured by Nihon Coke Kogyo Co., Ltd.).
Next, the mixed material is melt-kneaded to disperse the colorant, wax, and the like in the binder resin. In the melt-kneading step, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used. Due to the advantage of continuous production, single-screw or twin-screw extruders are the mainstream. For example, KTK type twin screw extruder (manufactured by Kobe Steel), TEM type twin screw extruder (manufactured by Toshiba Machine Co., Ltd.), PCM kneader (manufactured by Ikekai), twin screw extruder (manufactured by KC Corporation) , Co-kneader (manufactured by Buss Co., Ltd.), and kneedex (manufactured by Nippon Coke Industries Co., Ltd.). Furthermore, 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.

Next, the obtained cooling product is pulverized to a desired particle size in a pulverization step.
In the pulverization step, coarse pulverization is performed by a pulverizer such as a crusher, a hammer mill, or a feather mill. Then, it may be finely pulverized by a kryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), a super rotor (manufactured by Nissin Engineering Co., Ltd.), a turbo mill (manufactured by Freund Turbo Co., Ltd.) or an air jet type pulverizer.
After that, if necessary, such as inertial class elbow jet (manufactured by Nippon Steel & Mining Co., Ltd.), centrifugal classification type turboplex (manufactured by Hosokawa Micron), TSP separator (manufactured by Hosokawa Micron), Faculty (manufactured by Hosokawa Micron) The toner particles are obtained by classification using a classifier or a sieving machine.
Further, the toner particles may be made spherical. For example, after pulverization, spheronization is performed using a hybridization system (manufactured by Nara Machinery Co., Ltd.), a mechano-fusion system (manufactured by Hosokawa Micron Corporation), a faculty (manufactured by Hosokawa Micron Corporation), and Meteor Inbo MR Type (manufactured by Nippon Pneumatic Industrial Co., Ltd.). Good.

The toner can be obtained by mixing the toner particles with strontium titanate particles and, if necessary, other external additives. Examples of the mixer for mixing the external additive include FM mixer (manufactured by Nippon Coke Industries Co., Ltd.), super mixer (manufactured by Kawata Corp.), nobilta (manufactured by Hosokawa Micron Corp.), and hybridizer (manufactured by Nara Machinery Co., Ltd.). It is done.
The coarse particles may be sieved after mixing the external additive. The following are mentioned as a sieving apparatus used for that purpose.
Ultrasonic (manufactured by Sakae Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (Tokusu Kosakusha Co., Ltd.); Vibrasonic System (manufactured by Dalton Co.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); ); Micro shifter (manufactured by Hadano Sangyo Co., Ltd.).

The toner may contain other external additives other than strontium titanate particles. In particular, in order to improve the fluidity and chargeability of the toner, a fluidity improver may be added as an external additive.
As the fluidity improver, the following can be used.
Fluorine-based resin powders such as fine vinylidene fluoride powder and fine polytetrafluoroethylene powder; silica fine particles such as wet-process silica or dry-process silica, titanium oxide fine particles, alumina fine particles; the fine particles as silane compounds and titanium coupling agents Or hydrophobized fine particles surface-treated with a hydrophobizing agent such as silicone oil; oxides such as zinc oxide and tin oxide; barium titanate, calcium titanate, strontium zirconate and calcium zirconate Double oxides; carbonate compounds such as calcium carbonate and magnesium carbonate.
Of these, fine particles produced by vapor phase oxidation of a silicon halogen compound, and dry process silica fine particles called so-called dry process silica or fumed silica are preferred.
The dry process uses, for example, a thermal decomposition oxidation reaction in an oxyhydrogen flame of silicon tetrachloride gas, and the basic reaction formula is as follows.
SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl
In this production process, it is possible to obtain composite fine particles of silica and other metal oxides by using other metal halogen compounds such as aluminum chloride or titanium chloride together with silicon halogen compounds, and these are also included as silica fine particles. To do.
When the number average particle diameter of the primary particles is 5 nm or more and 30 nm or less, it is preferable that the fluidity improver has high chargeability and fluidity.
Furthermore, the silica fine particles are more preferably hydrophobized silica fine particles that have been surface-treated with the hydrophobizing agent.
The fluidity improver preferably has a specific surface area by nitrogen adsorption measured by BET method of 30 m ² / g or more and 300 m ² / g or less.
The 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.

A method for measuring various physical properties relating to the toner and other materials will be described below.
The physical properties of strontium titanate particles are measured using a toner as a sample.
When measuring the physical properties of strontium titanate particles or toner particles from a toner to which strontium titanate particles are externally added, the measurement may be performed by separating strontium titanate particles and other external additives from the toner.
The toner is ultrasonically dispersed in methanol to separate strontium titanate particles and other external additives, and left to stand for 24 hours. The toner particles can be isolated by separating and recovering the settled toner particles from the strontium titanate particles and other external additives dispersed in the supernatant and sufficiently drying them. In addition, strontium titanate particles can be isolated by treating the supernatant with centrifugation.

<Measurement of number average particle size of primary particles of strontium titanate particles>
The number average particle diameter of primary particles of strontium titanate particles is measured using a transmission electron microscope “JEM-2800” (JEOL Ltd.).
By observing the toner to which strontium titanate particles are externally added, the major axis of 100 primary particles of strontium titanate particles is randomly measured in the field of view enlarged up to 200,000 times to obtain the number average particle size. . The observation magnification may be appropriately adjusted according to the size of the strontium titanate particles.

<Measurement of diffraction peak of strontium titanate particles>
For the diffraction peak of the strontium titanate particles, a powder X-ray diffractometer “SmartLab” (manufactured by Rigaku Corporation, sample horizontal strong X-ray diffractometer) is used.
Further, the calculation of Sb / Sa from the obtained peak uses “PDXL2 (version 2.2.2.0)” of analysis software attached to the apparatus.
As a measurement sample, a toner or a sample obtained by isolating strontium titanate particles from a toner is used, and measurement is performed according to the following procedure. In the following examples, the produced strontium titanate particles are also measured.
(Sample preparation)
A measurement sample is measured after being uniformly placed in a 0.5 mm diameter Boro-Silicate capillary (manufactured by W. Muller).
(Measurement condition)
・ Tube: Cu
・ Optical system: CBO-E
-Sample stage: Capillary sample stage-Detector: D / tex Ultra250 detector-Voltage: 45 kV
・ Current: 200mA
・ Starting angle: 10 °
・ End angle: 90 °
・ Sampling width: 0.02 °
・ Speed measurement time set value: 10
・ IS: 1mm
・ RS1: 20mm
・ RS2: 20mm
・ Attenuator: Open
Capillary rotational speed setting value: 100
For other conditions, the initial setting value of the apparatus is used.
(analysis)
First, peak separation processing is performed on the obtained peak using software “PDXL2” attached to the apparatus. The peak separation is obtained by executing optimization using a “divided Voigt function” that can be selected by PDXL, and the obtained integrated intensity value is used.
This determines the 2θ value and the area of the diffraction peak top. Sb / Sa is calculated from the peak area of a predetermined 2θ value. At this time, if the calculation result of the peak separation and the actually measured spectrum are greatly deviated, a process such as manually setting a baseline is performed to adjust the calculation result and the actually measured spectrum so that they match.

<Measurement of Sr / Ti (molar ratio) of strontium titanate particles>
The Sr and Ti contents of the strontium titanate particles are measured using a wavelength dispersive X-ray fluorescence analyzer (Axios advanced, manufactured by PANalytical).
1 g of a sample is weighed on a powder measurement cup recommended by PANalytical, and a special film is pasted, and the elements from Na to U in strontium titanate particles are measured by the FP method under an atmospheric pressure He atmosphere.
At that time, assuming that all the detected elements are oxides, the total mass of them is 100%, and the content of SrO and TiO ₂ with respect to the total mass by software SpectraEvaluation (version 5.0 L) (% by mass) Is obtained as an oxide equivalent value.
Then, after calculating | requiring Sr / Ti (mass ratio) which excluded oxygen from the fixed_quantity | quantitative_assay result, it converts into Sr / Ti (molar ratio) from the atomic weight of each element.
A sample obtained by isolating strontium titanate particles from toner is used. Further, in the following examples, measurement is also performed on the produced strontium titanate particles.

<Measurement of average circularity of primary particles of strontium titanate particles>
The average circularity of the primary particles of the strontium titanate particles is measured using a transmission electron microscope “JEM-2800” (JEOL Ltd.).
The toner to which strontium titanate particles are externally added is observed and calculated as follows.
The observation magnification is appropriately adjusted according to the size of the strontium titanate particles.
Using the image processing software “Image-Pro Plus 5.1J” (Media Cybernetics), the circle equivalent diameter and the perimeter of the particles of 100 strontium titanate particles are measured randomly in a field of view up to 200,000 times magnification. Then, the average circularity is calculated. The equivalent circle diameter is the diameter of a circle having the same area as the projected area of the particles.
The circularity is calculated by the following formula, and the arithmetic average value is defined as the average circularity.
(Formula) Circularity = equivalent circle diameter × 3.14 / peripheral length of particle Note that the external additive is confirmed to be strontium titanate by STEM-EDS measurement.
The measurement conditions are as follows.
JEM2800 transmission electron microscope: acceleration voltage 200 kV
EDS detector: JED-2300T (JEOL, element area 100 mm ² )
EDS Analyzer: Noran System 7 (Thermo Fisher Scientific)
X-ray storage rate: 10000-15000 cps
Dead time: Adjust the electron dose so that it is 20-30%, and perform EDS analysis (integration count 100 times or measurement time 5 min).

<Measurement of hydrophobicity (volume%) of strontium titanate particles>
The degree of hydrophobicity (% by volume) of strontium titanate particles is measured by a powder wettability tester “WET-100P” (manufactured by Reska).
In a cylindrical glass container having a diameter of 5 cm and a thickness of 1.75 mm, a spindle type rotor having a length of 25 mm and a maximum barrel diameter of 8 mm coated with a fluororesin is placed.
In the cylindrical glass container, 70 mL of a hydrous methanol solution composed of 50% by volume of methanol and 50% by volume of water is placed. Thereafter, 0.5 g of strontium titanate particles isolated from the toner is added and set in a powder wettability tester.
Using a magnetic stirrer, methanol is added into the liquid at a rate of 0.8 mL / min through the powder wettability tester while stirring at a rate of 200 rpm.
The transmittance is measured with light having a wavelength of 780 nm, and the value expressed by the volume percentage of methanol (= (volume of methanol / volume of mixture) × 100) when the transmittance reaches 50% is defined as the degree of hydrophobicity. . Depending on the degree of hydrophobicity of the sample, the initial volume ratio of methanol to water is appropriately adjusted. Further, in the following examples, measurement is also performed on the produced strontium titanate particles.

<Measurement of coverage of toner surface with strontium titanate particles>
The coverage of the toner surface with strontium titanate particles (simply referred to as “coverage” in Table 3) is calculated from the following formula (2) by measuring the toner under the following conditions.
Measurement device: X-ray photoelectron spectrometer: Quantum 2000 (manufactured by ULVAC-PHI, Inc.)
・ X-ray source: Monochrome Al Kα
-Xray Setting: 100 μmφ (25 W (15 KV))
・ Photoelectron extraction angle: 45 degrees ・ Neutralization condition: Combined use of neutralizing gun and ion gun ・ Analysis area: 300 × 200 μm
・ Pass Energy: 58.70eV
・ Step size: 0.125eV
・ Analysis software: Maltipak (PHI)
Here, the peak of Ti 2p (BE 452-468 eV) is used for calculation of the quantitative value of Ti atoms. Let the quantitative value of the Ti element obtained here be Z1.
Subsequently, the elemental analysis of the strontium titanate particles alone is performed in the same manner as the above elemental analysis, and the quantitative value of the Ti element obtained here is set to Z2. The coverage of the toner surface with strontium titanate particles is calculated by the following formula (2).
Coverage ratio = Z1 / Z2 × 100 (2)

<Measurement of average circularity of toner>
The average circularity of the toner is measured by a flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex Corporation) under the measurement and analysis conditions during the calibration operation.
A specific measurement method is as follows.
First, about 20 mL of ion-exchanged water from which impure solids and the like are previously removed is placed in a glass container. In this, "Contaminone N" (nonionic surfactant, anionic surfactant, 10% by weight aqueous solution of neutral detergent for pH7 precision measuring instrument cleaning, made by organic builder, manufactured by Wako Pure Chemical Industries, Ltd. About 0.2 mL of a diluted solution obtained by diluting 3) with ion-exchanged water is added.
Further, about 0.02 g of a measurement sample is added, and a dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of a dispersion liquid may be 10 to 40 degreeC.
As the ultrasonic disperser, a desktop type ultrasonic cleaner disperser (for example, “VS-150” (manufactured by VervoCrea)) having an oscillation frequency of 50 kHz and an electric output of 150 W is used. Ion exchange water is put, and about 2 mL of the above-mentioned Contaminone N is added to this water tank.
For the measurement, a flow type particle image analyzer equipped with “LUCPLFLN” (20 × magnification, numerical aperture of 0.40) as an objective lens is used, and a particle sheath “PSE-900A” (manufactured by Sysmex Corporation) is used as the sheath liquid. use. The dispersion prepared in accordance with the above procedure is introduced into a flow type particle image analyzer, and 2000 toners are measured in the HPF measurement mode and in the total count mode.
Then, the binarization threshold at the time of particle analysis is set to 85%, the analysis particle diameter is limited to the equivalent circle diameter of 1.977 μm or more and less than 39.54 μm, and the average circularity of the toner is obtained.
In 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 ion-exchanged water before starting the measurement. Thereafter, it is preferable to perform focus adjustment every two hours from the start of measurement.
In the examples, a flow-type particle image analyzer which has been issued a calibration certificate issued by Sysmex Corporation, which has been calibrated by Sysmex Corporation, was used. The analysis particle diameter is measured under the measurement and analysis conditions when the calibration certificate is received, except that the equivalent circle diameter is limited to 1.977 μm or more and less than 39.54 μm.

<Measurement of Glass Transition Temperature (Tg) of Toner>
The glass transition temperature of the toner is measured in accordance with ASTM D3418-82 using a differential scanning calorimeter “Q1000” (manufactured by TA Instruments).
The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium.
Specifically, about 5 mg of a sample is precisely weighed, placed in an aluminum pan, and an empty aluminum pan is used as a reference, and the temperature is raised between a measurement temperature range of 30 ° C. and 200 ° C. Measurement is performed at a rate of 10 ° C./min.
In the measurement, the temperature is once raised to 200 ° C., subsequently lowered to 30 ° C. at a temperature lowering rate of 10 ° C./min, and then heated again at a temperature rising rate of 10 ° C./min.
In the DSC curve obtained in the second temperature raising process, the intersection of the DSC curve and the midpoint of the baseline before and after the specific heat change is taken as the glass transition temperature (Tg).

<Measurement of E / A on toner particle surface>
The ratio (E / A) of the amount of sulfur atoms (E (atomic%)) to the amount of carbon atoms (A (atomic%)) present on the toner particle surface is X-ray photoelectron spectrometer (ESCA) “1600S type”. (Physical Electronics Industries, Inc.) is used to analyze the composition of the toner particle surface and calculate based on the analysis result.
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 atom, Physical Electronics Industries, Inc. The surface atomic concentration (atomic%) is calculated using the relative sensitivity factor provided by the company, and is used as the amount of each atom.
The ranges of the measurement peak top of each atom used for measurement are carbon atoms: 283 to 293 eV and sulfur atoms: 166 to 172 eV.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not restrict | limited at all. In addition, all the parts of an Example and a comparative example are mass references | standards unless there is particular notice.

  Strontium titanate particles were produced as follows. Table 1 shows the physical properties of the strontium titanate particles 1-15.

<Example of production of strontium titanate particles 1>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.16 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.15, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. Obtained. A transmission electron micrograph of the strontium titanate particles 1 is shown in FIG.

<Example of production of strontium titanate particles 2>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. After adding 2.16 mol of the strontium chloride aqueous solution to the peptized metatitanic acid slurry so that the Sr / Ti (molar ratio) was 1.15, the TiO ₂ concentration was adjusted to 1.083 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. The resulting cake was dried in the atmosphere at 120 ° C. for 8 hours to obtain strontium titanate particles 2. Obtained.

<Example of production of strontium titanate particles 3>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.16 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.15, and then the TiO ₂ concentration was adjusted to 1.015 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. Obtained.

<Example of production of strontium titanate particles 4>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.16 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.15, and then the TiO ₂ concentration was adjusted to 0.988 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. Obtained.

<Example of production of strontium titanate particles 5>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.16 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.15, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 15 minutes.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. The resulting cake was dried in the atmosphere at 120 ° C. for 8 hours to obtain strontium titanate particles 5. Obtained.

<Example of production of strontium titanate particles 6>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.16 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.15, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 5 minutes.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. The resulting cake was dried in the atmosphere at 120 ° C. for 8 hours to obtain strontium titanate particles 6. Obtained.

<Example of production of strontium titanate particles 7>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.01 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.07, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. The resulting cake was dried in the atmosphere at 120 ° C. for 8 hours to obtain strontium titanate particles 7. Obtained.

<Example of production of strontium titanate particles 8>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.54 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.35, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. The resulting cake was dried in the atmosphere at 120 ° C. for 8 hours to obtain strontium titanate particles 8. Obtained.

<Example of production of strontium titanate particles 9>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.54 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.35, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 70 ° C., 4.0% by mass of sodium stearate with respect to the solid content was added, and stirring and holding were continued for 1 hour. 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. The resulting cake was dried in the atmosphere at 120 ° C. for 8 hours to obtain strontium titanate particles 9 Obtained.

<Example of production of strontium titanate particles 10>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.54 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.35, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, the dried product was treated 3 times at 6,000 rpm for 3 minutes using a hybridizer (manufactured by Nara Machinery Co., Ltd.).
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decantated and filtered and washed, and the resulting cake was dried in air at 120 ° C. for 8 hours to obtain strontium titanate particles 10.

<Example of production of strontium titanate particles 11>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. To the peptized metatitanic acid slurry, 2.16 mol of an aqueous strontium chloride solution was added so that the Sr / Ti (molar ratio) was 1.15, and then the TiO ₂ concentration was adjusted to 1.039 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. Obtained.

<Example of production of strontium titanate particles 12>
The metatitanic acid slurry obtained by hydrolyzing the titanyl sulfate aqueous solution was washed with an alkaline aqueous solution.
Next, hydrochloric acid was added to the metatitanic acid slurry to adjust the pH to 0.65 to obtain a titania sol dispersion.
NaOH was added to the titania sol dispersion, the pH of the dispersion was adjusted to 4.5, and washing was repeated until the electrical conductivity of the supernatant was 70 μS / cm.
A 0.97-fold molar amount of strontium hydroxide octahydrate was added to the metatitanic acid slurry, placed in a stainless steel reaction vessel, and purged with nitrogen gas.
Furthermore, distilled water was added to 0.5 mol / L in terms of TiO _2. The slurry was heated to 83 ° C. at 6.5 ° C./hour in a nitrogen atmosphere, and reacted for 6 hours after reaching 83 ° C. The obtained precipitate was decanted and washed, filtered and separated, and then dried in air at 120 ° C. for 8 hours to obtain strontium titanate particles 12.

<Example of production of strontium titanate particles 13>
The metatitanic acid obtained by the sulfuric acid method was deiron-bleached and bleached by adding an aqueous sodium hydroxide solution to pH 9.0, followed by neutralization to pH 5.8 with hydrochloric acid and washing with filtered water. Water was added to the washed cake to make a slurry of 1.85 mol / L as TiO ₂ , and hydrochloric acid was added to adjust the pH to 1.0, followed by peptization.
The desulfurized and peptized metatitanic acid was collected as TiO _{2 in an amount} of 1.88 mol and charged into a 3 L reaction vessel. After adding 2.16 mol of the strontium chloride aqueous solution to the peptized metatitanic acid slurry so that the Sr / Ti (molar ratio) was 1.15, the TiO ₂ concentration was adjusted to 0.960 mol / L.
Next, after heating to 90 ° C. with stirring and mixing, 440 mL of a 10 mol / L aqueous sodium hydroxide solution was added over 45 minutes, and then stirring was continued at 95 ° C. for 1 hour to complete the reaction.
The reaction slurry was cooled to 50 ° C., hydrochloric acid was added until pH 5.0, and stirring was continued for 20 minutes. The obtained precipitate was washed by decantation, filtered and separated, and dried in air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite apparatus (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was performed for 10 minutes at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec.
Further, hydrochloric acid was added to the dried product until pH 0.1, and stirring was continued for 1 hour. The resulting precipitate was decanted and washed.
The slurry containing the precipitate was adjusted to 40 ° C. and adjusted to pH 2.5 by adding hydrochloric acid, and then 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and the stirring was continued for 10 hours. . A 5 mol / L sodium hydroxide solution was added to adjust the pH to 6.5 and stirring was continued for 1 hour, followed by filtration and washing. Obtained.

<Example of production of strontium titanate particles 14>
Hydrous titanium oxide obtained by hydrolysis by adding ammonia water to titanium tetrachloride aqueous solution is washed with pure water, and 0.25% sulfuric acid is added to the hydrous titanium oxide slurry as SO _{3 with} respect to hydrous titanium oxide. did.
Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH to 0.65 to obtain a titania sol dispersion. NaOH was added to the titania sol dispersion, the pH of the dispersion was adjusted to 4.7, and washing was repeated until the electrical conductivity of the supernatant reached 50 μS / cm.
A 0.95-fold molar amount of strontium hydroxide octahydrate was added to the hydrous titanium oxide, and the mixture was placed in a stainless steel reaction vessel and purged with nitrogen gas. Furthermore, distilled water was added so as to be 0.6 mol / L in terms of SrTiO ₃ .
The slurry was heated to 65 ° C. at a rate of 10 ° C./hour in a nitrogen atmosphere, and reacted for 8 hours after reaching 65 ° C. After the reaction, the mixture was cooled to room temperature, the supernatant was removed, and washing was repeated with pure water.
Further, in a nitrogen atmosphere, the slurry is put in an aqueous solution in which 2% by mass of sodium stearate is dissolved with respect to the solid content of the slurry, and while stirring, an aqueous magnesium sulfate solution is dropped, and stearic acid is applied to the perovskite crystal surface. Magnesium was precipitated.
The slurry was repeatedly washed with pure water and then filtered with Nutsche, and the resulting cake was dried to obtain strontium titanate particles 14 that had been surface-treated with magnesium stearate.

<Production Example of Strontium Titanate Particle 15>
The hydrous titanium oxide slurry obtained by hydrolyzing the aqueous titanyl sulfate solution was washed with an alkaline aqueous solution. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH to 4.0 to obtain a titania sol dispersion. NaOH was added to the titania sol dispersion, the pH of the dispersion was adjusted to 8.0, and washing was repeated until the electrical conductivity of the supernatant reached 100 μS / cm.
A 1.02-fold molar amount of strontium hydroxide octahydrate was added to the hydrous titanium oxide, and the mixture was placed in a stainless steel reaction vessel and purged with nitrogen gas.
Further, distilled water was added so as to be 0.3 mol / L in terms of SrTiO ₃ . The slurry was heated to 90 ° C. at 30 ° C./hour in a nitrogen atmosphere, and reacted for 5 hours after reaching 90 ° C. After the reaction, the reaction solution was cooled to room temperature, and the supernatant was removed. Then, the washing was repeated with pure water, and then filtered with Nutsche. The obtained cake was dried to obtain strontium titanate particles 15.

<Production example of charge control resin 1>
In a pressurizable reaction vessel equipped with a reflux tube, a stirrer, a thermometer, a nitrogen introduction tube, a dropping device and a decompression device, 250 parts of methanol as a solvent, 150 parts of 2-butanone and 100 parts of 2-propanol, and styrene as a monomer 83 parts, 12 parts butyl acrylate and 5 parts 2-acrylamido-2-methylpropanesulfonic acid were added and heated to reflux temperature with stirring.
A solution obtained by diluting 0.45 part of t-butylperoxy-2-ethylhexanoate as a polymerization initiator with 20 parts of 2-butanone was added dropwise thereto over 30 minutes, and stirring was continued for 5 hours. -A solution obtained by diluting 0.28 part of butylperoxy-2-ethylhexanoate with 20 parts of 2-butanone was added dropwise over 30 minutes, and the mixture was further 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 equipped with a 150 mesh screen to obtain a charge control resin 1. The obtained polymer had a glass transition temperature (Tg) of about 70 ° C.

Toner particles were prepared as follows. Table 2 shows the physical properties of the obtained toner particles 1 to 9.
<Production Example of Toner Particle 1>
In a four-necked container, 710 parts of ion-exchanged water and 850 parts of a 0.1 mol / L Na ₃ PO ₄ aqueous solution were added. K. The mixture was kept at 60 ° C. while stirring at 12,000 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co.). To this, 68 parts of a 1.0 mol / L CaCl ₂ aqueous solution was gradually added to prepare an aqueous medium containing a dispersion stabilizer.
Styrene 124 parts n-butyl acrylate 36 parts Copper phthalocyanine pigment (Pigment Blue 15: 3) 13 parts Polyester resin 1 10 parts (terephthalic acid-propylene oxide modified bisphenol A (2 mole adduct) copolymer, acid Value: 10 mg KOH / g, glass transition temperature (Tg): 70 ° C., weight average molecular weight (Mw): 10500)
Charge control resin 1 2 parts Fischer-Tropsch wax (melting point: 78 ° C.) 15 parts The above materials are stirred for 3 hours using an attritor (manufactured by Nihon Coke Kogyo Co., Ltd.). The monomer mixture was prepared by dispersing.
20.0 parts of 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate as a polymerization initiator (50% toluene solution) is added to the monomer mixture, and a polymerizable monomer composition is obtained. Was prepared.
The polymerizable monomer composition was put into an aqueous medium and granulated for 5 minutes while maintaining the rotational speed of the stirrer at 10,000 rpm. Thereafter, the high-speed stirrer was changed to a propeller stirrer, the internal temperature was raised to 70 ° C., and the reaction was allowed to proceed for 6 hours with slow stirring.
Next, the temperature in the container was raised to 80 ° C. and maintained for 4 hours, and then cooled to obtain a slurry. Dilute hydrochloric acid was added to the container containing the slurry to remove the dispersion stabilizer. Further, the toner particles 1 were obtained by filtration, washing and drying.

<Production Example of Toner Particle 2>
In the production example of toner particles 1, polyester resin 1 is converted to polyester resin 2 (terephthalic acid-propylene oxide modified bisphenol A (2 mole adduct) copolymer, acid value: 13 mgKOH / g, glass transition temperature (Tg): 67 ° C. , Weight average molecular weight (Mw): 9800), granulation conditions after charging the polymerizable monomer composition into the aqueous dispersion medium, granulation for 8 minutes while maintaining the rotational speed of the stirrer at 7500 rpm Toner particles 2 were obtained in the same manner except that the change was made.

<Production Example of Toner Particle 3>
In the production example of toner particles 1, polyester resin 1 is converted to polyester resin 3 (terephthalic acid-propylene oxide modified bisphenol A (2 mole adduct) copolymer, acid value: 5 mgKOH / g, glass transition temperature (Tg): 71 ° C. The weight average molecular weight (Mw) is changed to 11800), and the granulation conditions after adding the polymerizable monomer composition into the aqueous medium are granulated for 5 minutes while maintaining the rotational speed of the stirrer at 12000 rpm. Toner particles 3 were obtained in the same manner except that the above was changed.

<Production Example of Toner Particle 4>
Toner particles 4 were obtained in the same manner as in the production example of toner particles 1 except that the addition amount of styrene was changed from 124 parts to 130 parts and the addition amount of n-butyl acrylate was changed from 36 parts to 30 parts.

<Production Example of Toner Particle 5>
Toner particles 5 were obtained in the same manner as in the production example of toner particles 1 except that the addition amount of styrene was changed from 124 parts to 115 parts and the addition amount of n-butyl acrylate was changed from 36 parts to 45 parts.

<Production Example of Toner Particle 6>
Toner particles 6 were obtained in the same manner as in the production example of toner particles 1 except that the addition amount of styrene was changed from 124 parts to 135 parts and the addition amount of n-butyl acrylate was changed from 36 parts to 25 parts.

<Production Example of Toner Particle 7>
Toner particles 7 were obtained in the same manner except that the addition amount of styrene was changed from 124 parts to 110 parts and the addition amount of n-butyl acrylate was changed from 36 parts to 50 parts in the production example of toner particles 1.

<Production Example of Toner Particle 8>
Toner particles 8 were obtained in the same manner as in the production example of toner particles 7 except that polyester resin 1 was not added.

<Production Example of Toner Particle 9>
Toner particles 9 were obtained in the same manner as in the production example of toner particles 7 except that the charge control resin 1 was not added.

<Production Example of Toner 1>
With respect to the obtained toner particles 1 (100 parts), strontium titanate particles 1 (1.5 parts) and fumed silica fine particles (BET: 200 m ^{2 /} g) (1.5 parts) are used. The particles were externally mixed by FM10C (manufactured by Nippon Coke Kogyo Co., Ltd.).
The external addition conditions were as follows: toner particle charge: 1.8 kg, rotation speed: 3600 rpm, external addition time: 5 minutes.
Thereafter, the mixture was sieved with a mesh having an opening of 200 μm to obtain toner 1.
The physical properties of Toner 1 are shown in Table 3. The average circularity, Tg, and E / A of the toner were the same as in Table 2. The physical properties of the strontium titanate particles 1 externally added to the toner were also the same as in Table 1.

<Example 1>
Using the obtained toner 1, the following evaluation was performed. The evaluation results are shown in Table 4.
<Evaluation machine>
An HP laser beam printer HP Color LaserJet Enterprise M651n was modified and evaluated to operate even when only one color process cartridge was installed. As evaluation paper, CS-680 sold by Canon Marketing Japan was used. The toner was filled in a predetermined process cartridge.

<Developability>
The evaluation of developability was performed in a low-temperature and low-humidity environment (temperature 10 ° C., relative humidity 14%) that is easily affected by chargeability. Further, in a low temperature and low humidity environment, the toner is not easily heated and plasticized through repeated use over a long period of time.
A mode in which a horizontal line pattern with a printing rate of 1% is assumed to be 2 sheets / job, assuming that a long-term repeated use test is performed, and the machine is temporarily stopped between jobs and the next job starts. Then, a total of 20000 image drawing tests were performed. The image density on the first and 20,000th sheets was measured.
The image density was measured by outputting a solid image of a 5 mm round and measuring the reflection density using an SPI filter with a Macbeth densitometer (manufactured by Macbeth) which is a reflection densitometer.
Larger values indicate better developability.

<Cover>
The fog was evaluated in a low-temperature, low-humidity environment that is easily affected by charging properties. Further, in a low temperature and low humidity environment, the toner is not easily heated and plasticized through repeated use over a long period of time.
After the first and 20000th images are output in the evaluation of developability, a solid white image is output, the white background portion reflection density worst value is Ds, and the reflection average density of the evaluation paper before image formation is Dr. , Dr-Ds was defined as the fogging value.
The reflection density meter (reflectometer model TC-6DS is used for the measurement of the white background reflection density.
An Amberlite filter was used as a filter.
The smaller the value, the better the cover level.

<Developability after standing>
In a high-temperature, high-humidity environment (temperature: 30 ° C, relative humidity: 80%), the horizontal line pattern with a printing rate of 1% is set to 2 sheets / job, and the next job starts after the machine stops once between jobs. In the mode set as described above, a total of 5000 image drawing tests were performed.
The image density at the 5000th sheet was measured. The reason for evaluating in a high temperature and high humidity environment is to evaluate under more severe conditions for maintaining the chargeability.
After outputting 5000 images, a 5 mm round solid image was output, and after leaving in a high temperature and high humidity environment (temperature 30 ° C., relative humidity 80%) for 3 days, a 5 mm round solid image was output.
The image density was measured by measuring the reflection density with a Macbeth densitometer (Macbeth Co., Ltd.), which is a reflection densitometer, using an SPI filter.
Compared to the reflection density of the solid image after outputting 5000 images, the lower the decrease in the reflection density of the solid image after standing for 3 days, the better the developability after leaving.

<Parts contamination>
When the developing blade is contaminated, an image defect may occur. Contamination of the developing blade was evaluated by transferring the cartridge to a high-temperature and high-humidity environment after the image was printed in a low-temperature and low-humidity environment that was severe in terms of toner cracking.
The reason for moving to a high-temperature and high-humidity environment is to easily cause development blade contamination due to toner cracking.
The cartridge which output 20000 sheets in the evaluation of the fog in the low temperature and low humidity environment was transferred to the high temperature and high humidity environment.
A test of 3000 sheets was performed in a mode in which the horizontal line pattern with a printing rate of 1% was set to 1 sheet / job and the machine was temporarily stopped between jobs and the next job started. did.
Subsequently, a halftone image having an image density of 0.6 in the Macbeth reflection densitometer described above with respect to the transfer paper conveyance direction was output so that an image defect caused by developing blade contamination could be easily identified. This image was visually observed, and the presence or absence of vertical stripes along the conveying direction caused by contamination of the developing blade was evaluated based on the following criteria.
A: No white stripe-like vertical line is seen on the image.
B: One or two white stripe-like vertical lines are slightly seen on the image.
C: 1-2 clear white stripe-like vertical lines are seen on the image.
D: Three or more clear white stripe-like vertical lines are seen on the image.

<Uniformity of halftone density>
The uniformity of the halftone density was evaluated in a low-temperature and low-humidity environment (temperature: 10 ° C., relative humidity: 14%) that is easily affected by charging properties.
In order to strictly observe the influence of the toner charge distribution, evaluation was performed on the first halftone image. Halftone image output with a reflection density of 0.60 was performed, the reflection density of the obtained image was measured at multiple points, and the density difference between the multiple points was determined to evaluate halftone density unevenness. The evaluation criteria are shown below.
A: Reflection density difference less than 0.05 B: Reflection density difference between 0.05 and less than 0.10 C: Reflection density difference between 0.10 and less than 0.15 D: Reflection density difference between 0.15 and more

<Production Examples of Toner 2-20 and Comparative Toners 1-5>
Toner 1 to toner 20 and comparative toner 1 to toner 1 were prepared in the same manner as in toner 1 except that the type and amount of toner particles and strontium titanate particles used were changed as shown in Table 3. 5 was obtained. Table 3 shows the physical properties of Toner 2 to 20 and Comparative Toner 1 to 5. In toners 2 to 20 and comparative toners 1 to 5, the average circularity, Tg, and E / A of the toner were the same as those of the toner particles in Table 2. The physical properties of the strontium titanate particles externally added to the toner were the same as in Table 1.

<Examples 2 to 20, Comparative Examples 1 to 5>
Evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Table 4.

Claims (10)

A toner containing toner particles and an external additive,
The external additive contains strontium titanate particles,
The average circularity of the toner is 0.935 or more and 0.995 or less,
The strontium titanate particles are
The number average particle size of the primary particles is 10 nm or more and 60 nm or less,
The strontium titanate particles have 39.700 ° ± 0.150 ° and 46.200 ° in the X-ray diffraction spectrum of CuKα obtained when the Bragg angle is θ and 2θ ranges from 10 ° to 90 °. Each has a peak in the range of ± 0.150 °,
Sa is the peak area at 39.700 ° ± 0.150 °,
When the peak area at 46.200 ° ± 0.150 ° is Sb,
A toner having Sb / Sa of 1.80 or more and 2.30 or less.   The toner according to claim 1, wherein the toner has a glass transition temperature of 50 ° C. or higher and 70 ° C. or lower.   The toner according to claim 1, wherein the strontium titanate particles have an Sr / Ti (molar ratio) of 0.70 or more and 0.85 or less.   The toner according to claim 1, wherein an average circularity of primary particles of the strontium titanate particles is 0.700 or more and 0.920 or less.   The strontium titanate particles have a methanol concentration of 60% by volume or more and 95% by volume or less when the light transmittance at a wavelength of 780 nm is 50% in a wettability test with respect to a methanol / water mixed solvent. The toner according to any one of 4.   The coverage with the strontium titanate particles on the surface of the toner measured by an X-ray photoelectron spectrometer is 5.0 area% or more and 20.0 area% or less, according to any one of claims 1 to 5. Toner.   The toner according to claim 1, wherein a content of the strontium titanate particles is 0.05 parts by mass or more and 5.0 parts by mass or less with respect to 100 parts by mass of the toner particles.   The toner according to claim 1, wherein the toner particles are toner particles having a core and a shell layer present on the surface of the core.   The toner according to claim 8, wherein the shell layer contains at least one selected from the group consisting of a polyester resin, a styrene-acrylic copolymer, and a styrene-methacrylic copolymer. The amount of carbon atoms present on the surface of the toner particles measured by an X-ray photoelectron spectrometer is A (atomic%),
When the amount of sulfur atoms present on the surface of the toner particles, measured by an X-ray photoelectron spectrometer, is E (atomic%),
The toner according to claim 1, wherein E / A satisfies the following formula (1).
3 × 10 ⁻⁴ ≦ E / A ≦ 50 × 10 ⁻⁴ (1)

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