JP6914862B2 - toner - Google Patents

Description

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

Electrophotographic image forming devices are required to have higher speed, longer life, energy saving, and smaller size, and in order to meet these demands, further improvement of various performances of toner is required. Has been done. In particular, toner is required to be further improved in quality stability from the viewpoint of extending the service life.
In particular, in order to extend the service life, it is important that the quality does not change significantly even after repeated use for 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 for a long period of time, a smooth toner having a high circularity is often used. It is considered that the toner surface having a high circularity can be uniformly charged because it rolls easily. On the other hand, toner with a high degree of circularity tends to be in a charge-up state in which it is overcharged. Therefore, as one of the means for controlling the chargeability of the toner having a high circularity, there is a method of stabilizing the chargeability of the toner by using an external additive as a resistance adjusting agent.
Strontium titanate particles, which are medium resistance materials, have been used as resistance adjusting agents for satisfactorily adjusting the charge of toner having a high degree of circularity.
The shape of the strontium titanate particles used as an external additive is a hexahedral shape, and many of them have a flat surface. When the strontium titanate particles have a flat surface, the contact area with the toner particles increases, so that the charge is easily transferred between the toner particles and the strontium titanate particles. Therefore, even if the toner particles are in a charge-up state due to triboelectric charging, the charge can be diffused to uniformly charge the toner particles. As a result, excellent developability could be exhibited from the initial stage of durability.
However, conventional strontium titanate particles may migrate from toner particles due to repeated rubbing in the developing machine during long-term repeated use, and the chargeability of the toner at the end of long-term repeated use. Fluctuated, and the developability tended to decrease. 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 that 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 having controlled _{SrO / TiO 2 (molar ratio) to the toner particles.} ..
Patent Document 2 proposes that by externally adding strontium titanate particles whose crystal structure and shape are controlled to toner particles, it is possible to improve the suppression of image flow in a high temperature and high humidity environment.
Patent Document 3 proposes that the fluidity 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.

JP-A-2015-137208 Japanese Patent No. 4944980 Japanese Unexamined Patent Publication No. 2003-277054

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

The present invention is a toner containing toner particles and an external additive.
The external agent contains strontium titanate particles and
The average circularity of the toner is 0.935 or more and 0.995 or less.
The strontium titanate particles are
The average particle size of the number of primary particles is 10 nm or more and 60 nm or less.
The strontium titanate particles are 39.700 ° ± 0.150 ° and 46.200 ° in the X-ray diffraction spectrum of CuKα obtained in the range where 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 °,
Let Sa be the area of the peak at 39.700 ° ± 0.150 °.
When the area of the peak 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 having excellent developability and capable of suppressing the occurrence of fog and member contamination even when a toner having a high circularity is repeatedly used for a long period of time.

Transmission electron micrograph of strontium titanate particle 1 (drawing substitute photograph)

In the present invention, the description of "○○ or more and XX or less" and "○○ to XX" indicating a numerical range means a numerical range including a lower limit and an upper limit which are end points, unless otherwise specified.
As described above, one of the means for controlling the chargeability of the toner having a high circularity is to use strontium titanate particles.
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 if the toner particles are in a charge-up state due to triboelectric charging. The toner can be charged uniformly. As a result, it was possible to achieve excellent developability and suppression of fog from the initial stage of repeated use.
However, with conventional strontium titanate particles, the strontium titanate particles may migrate from the toner particles due to rubbing in the developing machine during long-term repeated use, and the toner is charged at the end of long-term repeated use. The properties tended to fluctuate and the developability and fog tended to decrease.

Therefore, the present inventors have attempted to reduce the particle size of the strontium titanate particles in order to prevent the strontium titanate particles from migrating from the toner particles.
It was thought that if the diameter was reduced, the migration could be suppressed even if it was repeatedly rubbed in the developing machine. It was thought that if the diameter was further reduced, it would be easier to roll on the surface of the toner particles, which would be effective for uniform charging of the toner.
In fact, by reducing the particle size of the strontium titanate particles, the migration of the strontium titanate particles can be suppressed even if they are repeatedly rubbed in the developing machine during long-term repeated use.
However, it was found that when strontium titanate particles having a small particle size were applied to a smooth toner having a high circularity, the surface of the toner particles was easily scratched. In some cases, it was found that the toner particles were cracked. When the toner particles are cracked, it affects the charge distribution of the toner.
That is, when strontium titanate particles having a small particle size are applied to a smooth toner having a high circularity, the charge distribution fluctuates due to the cracking of the toner particles, the developability of the toner is lowered, and the fog is formed. The outbreak was found to increase. It was also found that member contamination due to cracked toner particles is likely to occur.
As a result of repeated studies, the present inventors have developed by using small particle size strontium titanate particles having a specific profile in the X-ray diffraction spectrum as an external additive even in repeated use for a long period of time. We have found that it is excellent in properties and can suppress the occurrence of fog and member contamination, and have arrived at the present invention.

That is, the toner of the present invention is a toner containing toner particles and an external additive.
The external agent contains strontium titanate particles and
The average circularity of the toner is 0.935 or more and 0.995 or less.
The strontium titanate particles are
The average particle size of the number of primary particles is 10 nm or more and 60 nm or less.
The strontium titanate particles are 39.700 ° ± 0.150 ° and 46.200 ° in the X-ray diffraction spectrum of CuKα obtained in the range where 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 °,
Let Sa be the area of the peak at 39.700 ° ± 0.150 °.
When the area of the peak at 46.200 ° ± 0.150 ° is Sb,
Sb / Sa is 1.80 or more and 2.30 or less.

Strontium titanate particles are 39.700 ° ± 0.150 ° and 46.200 ° ± in the X-ray diffraction spectrum of CuKα obtained in the range where 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, which has a peak at this position, adopts a perovskite structure belonging to the cubic system, and the peaks in the range of 39.700 ° ± 0.150 ° and 46.200 ° ± 0.150 ° are the Miller index (111), respectively. It is a diffraction peak derived from the lattice plane of (200).
Generally, particles belonging to the cubic system tend to take a hexahedral shape as the appearance shape of the particles, and strontium titanate particles also have (100) planes and (200) planes corresponding to the plane direction of the hexahedral shape in the manufacturing process. grow up.
However, as a result of our studies, it has been found that strontium titanate particles having a hexahedral shape having a (200) plane corresponding to the plane direction and a (111) plane corresponding to the apex direction exhibit good characteristics.
As a result of detailed examination, when the area of the peak at 39.700 ° ± 0.150 ° is Sa and the area of the peak at 46.200 ° ± 0.150 ° is Sb, Sb / Sa is 1. It was found that a remarkable effect was exhibited when the content was .80 or more and 2.30 or less. Further, the Sb / Sa is preferably 1.80 or more and 2.25 or less.

The number average particle size of the primary particles of strontium titanate particles is 10 nm or more and 60 nm or less. Moreover, 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 range, the migration of strontium titanate particles from the toner particles and the cracking of the toner particles are suppressed even if the toner having a high circularity is repeatedly used for a long period of time. can do. As a result, the toner has excellent developability, and fog and member contamination are suppressed.
The number average particle size of the primary particles of the strontium titanate particles and Sb / Sa are controlled by adjusting the molar ratio of the raw material 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 Sr / Ti (molar ratio) is in the above range, the proportion of Ti that is nearly negatively charged in terms of charge increases, so that the charge distribution tends 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 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 likely to be crushed on the toner particles, and the coverage with the strontium titanate particles is likely to increase.
As a result, the charge of the toner is likely to rise from the initial stage of repeated use, and the effect on the developability and the suppression of fog at the initial stage of repeated use is likely to be obtained. The average circularity of the primary particles of 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 transmittance of light having a wavelength of 780 nm is 50% in a wettability test with a mixed solvent of methanol / water, and 65 volumes by volume. More preferably, it is% or more and 95% by volume or less.
When the methanol concentration is in the above range, the developability after being left in a high temperature and high humidity environment is likely to be maintained.
The wettability of the strontium titanate particles to the methanol / water mixture solvent can be controlled by adjusting the surface treatment conditions of the strontium titanate particles.

The coverage of the surface of the toner 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, preferably 8.0 area% or more. It is more preferably 20.0 area% or less.
When the coverage is in the above range, the toner is likely to be charged from the initial stage of repeated use, and it is easy to obtain an effect on the developability and the suppression of fog at the initial stage of repeated use. The coverage can be controlled by adjusting the shape and amount of strontium titanate particles added, 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. Further, 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 within the above range, the developability can be improved and fog 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 likely to be dispersed on the surface of the toner particles. That is, since a dispersed state closer to the primary particles can be formed, the coverage of the strontium titanate particles can be increased. As a result, it is possible to further improve the developability and suppress the occurrence of fogging and member contamination at a higher level in repeated use for a long period of time.
The glass transition temperature (Tg) can be controlled by adjusting the composition of the binder resin constituting the toner or the like.

In order to produce perovskite-type strontium titanate particles, it is preferable to use a normal pressure heating reaction method in which the particles are reacted at normal pressure instead of hydrothermal treatment using a pressure vessel.
A mineral acid deflated product of a hydrolyzate of a titanium compound is used as a titanium oxide source, and a water-soluble acidic compound is used as a strontium source. Then, a method of reacting the mixed solution with an alkaline aqueous solution at 60 ° C. or higher while adding it, and then treating with an acid can be exemplified.
Further, as a method of controlling the shape of the strontium titanate particles, there is also a method of performing a dry mechanical treatment, and it is possible to control the value of Sb / Sa by this method.

Hereinafter, the atmospheric heating reaction method will be described.
As the titanium oxide source, it is preferable to use a mineral acid gelatinized product of a hydrolyzate of a titanium compound.
_{Preferably, metatitanic acid having an SO 3} content of 1.0% by mass or less, more preferably 0.5% by mass or less obtained by a sulfuric acid method is adjusted to a pH of 0.8 or more and 1.5% or less with hydrochloric acid. Use the one that has been defrosted. As a result, 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 and the like can be used. As the alkaline aqueous solution, caustic alkali can be used, but among them, the sodium hydroxide aqueous solution is preferable.
Factors that affect the particle size of the obtained strontium titanate particles in the production method include the mixing ratio of the titanium oxide source and the strontium source, the concentration of the titanium oxide source at the initial stage of the reaction, the temperature at which the alkaline aqueous solution is added, and the addition. Speed and so on. These factors can be appropriately adjusted to obtain strontium titanate particles having a desired particle size and particle size distribution. In addition, it is preferable to prevent the mixing of carbon dioxide gas by reacting in a nitrogen gas atmosphere in order to prevent the formation of strontium carbonate in the reaction process.

The mixing ratio of the titanium oxide source and the strontium source at the time of the reaction is preferably 0.90 or more and 1.40 or less, more preferably 1.05 or more and 1.20 or less in terms of Sr / Ti (molar ratio). ..
The strontium source has high solubility in water, whereas 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, and more preferably 0.080 mol / L or more and 1.200 mol / L or less 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 size of the primary particles of the strontium titanate particles can be reduced.

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

Subsequently, 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 reaction is completed reacts with carbon dioxide in the air to form strontium carbonate. Impurities such as are generated, and the particle size distribution tends to be wide. Further, if 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 when performing the surface treatment for imparting hydrophobicity. Therefore, after adding the alkaline aqueous solution, it is advisable to carry out acid treatment in order to remove the unreacted strontium source.
In the acid treatment, it is preferable to adjust the pH to 2.5 or more and 7.0 or less using hydrochloric acid, and more preferably to adjust the pH to 4.5 or more and 6.0 or less.
As the acid, nitric acid, acetic acid and the like can be used for the acid treatment in addition to hydrochloric acid. However, when sulfuric acid is used, strontium sulfate, which has 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 can be given as an example.
For example, a hybridizer (manufactured by Nara Machinery Co., Ltd.), Nobilta (manufactured by Hosokawa Micron Co., Ltd.), Mechanofusion (manufactured by Hosokawa Micron Co., Ltd.), Hiflex Gural (manufactured by EarthTechnica Co., Ltd.) and the like can be used. By treating the strontium titanate particles with these devices, it is easy to control Sb / Sa to 1.80 or more and 2.30 or less.
When controlling the shape of strontium titanate particles by mechanical treatment, fine powder of strontium titanate particles may be generated. In order to remove the fine powder, it is preferable to carry out 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, nitric acid, acetic acid and the like can be used for the acid treatment in addition to hydrochloric acid. The mechanical treatment for controlling the shape of the strontium titanate particles is preferably carried out before the surface treatment of the strontium titanate particles is performed.

_{Strontium titanate particles are hydrophobic such as inorganic oxides such as SiO 2} , Al ₂ O ₃ , titanium coupling agents, silane coupling agents, silicone oils, and fatty acid metal salts in order to adjust the charge and improve the environmental stability. Surface treatment with an agent is recommended.
As the silane coupling agent, a silane coupling agent in 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. Similar effects can be obtained with fatty acids such as stearic acid.
Examples of the surface treatment method include a wet method in which a hydrophobic agent is dissolved or dispersed in a solvent, strontium titanate particles are added thereto, and the solvent is removed while stirring.
Alternatively, a dry method may be used in which the treatment agent and the strontium titanate particles are directly mixed and treated while stirring.

The content of the 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. Is more preferable.

The method for producing the toner particles is not particularly limited as long as it 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 for directly producing toner particles 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, or the toner particles obtained by the pulverization method may be formed into a thermal sphere to adjust the average circularity within the above range.
Among them, the suspension polymerization method is preferable. The toner particles produced by the suspension polymerization method have high transferability because the individual particles are substantially spherical and the distribution of the amount of charge is relatively uniform.
In the suspension polymerization method, a polymerizable monomer composition containing a polymerizable monomer, a colorant, a wax, etc. that can produce a binder resin is dispersed in an aqueous medium to form a polymerizable monomer composition. Toner particles are produced by forming the particles of the above and polymerizing the polymerizable monomer in the particles.
The toner particles may be toner particles having a core and a shell layer existing on the surface of the core. By adopting this structure, it is possible to suppress poor charging due to the core exuding to the surface of the toner particles.
The shell layer preferably contains at least one selected from the group consisting of polyester resin, styrene-acrylic copolymer, and styrene-methacryl copolymer, and more preferably contains polyester resin.
The amount of resin forming the shell layer is preferably 0.01 part by mass or more and 20.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 10. It is 0 parts by mass or less.

When a polyester resin is used for the shell layer, the externally attached strontium titanate particles are easily loosened on the surface of the toner particles, and the strontium titanate particles are easily dispersed. As a result, after repeated use for a long period of time, the developability can be further improved, and the occurrence of fogging and member contamination can be further suppressed.
The weight average molecular weight of the polyester resin is preferably 5000 or more and 50,000 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 more easily improved.

Examples of the polymerizable monomer capable of producing a binder resin include a vinyl-based polymerizable monomer. Specifically, the following can be exemplified.
Butyl; styrene derivatives such as α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene; methylacrylate, ethylacrylate, n-propylacrylate, Acrylic polymerizable monomers such as iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate. , N-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate and other methacrylic polymerizable monomers; methylene aliphatic monocarboxylic acid esters; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, formic acid. Examples include vinyl esters such as vinyl.

The toner particles may contain a charge control agent. As the charge control agent, one that controls the toner particles to be negatively charged and one that controls the toner particles to be positively charged are known, and one or two or more kinds of various ones are used depending on the type and application of the toner. be able to.
Examples of those that control the toner particles to be negatively charged include the following.
Organic metal 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; bisphenol Such as phenol derivatives. These can be used alone or in combination of two or more.
Among these, a metal complex or a metal salt of an aromatic hydroxycarboxylic acid that can obtain stable charging performance is preferable.
On the other hand, examples of controlling the toner particles to be positively charged include the following.
Modified products with niglosin 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 salt. And these lake pigments; triphenylmethane dyes and their lake pigments (as lake agents, phosphotung acid, phosphomolybdic acid, phosphotungene molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanic acid, ferrocyanic acid. Compounds, etc.); Metal salts of higher fatty acids. These can be used alone or in combination of two or more.
Among these, niglosin compounds, quaternary ammonium salts and the like are preferable.
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 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer or the binder resin capable of producing the binder resin.

It is also a preferred embodiment to use a charge control resin. When the toner particles contain a charge control resin, the negative charge property on the surface of the toner particles is improved. As a result, the strontium titanate particles, which are positively charged, and the electrostatic adhesion force become high, so that the strontium titanate particles are less likely to migrate from the toner particles, and the developability is improved after repeated use for a long period of time. It becomes easier to control the occurrence of contamination.
As the charge control resin, a polymer having a sulfonic acid-based functional group is preferable. The polymer having a sulfonic acid-based functional group is a polymer having a sulfonic acid group, a sulfonic acid base or a sulfonic acid ester group. Of these, a polymer having a sulfonic acid group is preferable.
Specifically, a monomer homopolymer such as styrene sulfonic acid, 2-acrylamide-2-methylpropansulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, vinylsulfonic acid, and methacrylsulfonic acid, or Examples thereof include a copolymer of the monomer and another monomer. Further, those obtained by converting the sulfonic acid group of the polymer into a sulfonic acid base or esterifying the polymer 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 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the polymerizable monomer or the binder resin capable of producing the binder resin. Further, the charge control resin can be used in combination with a water-soluble polymerization initiator to further improve the charge state of the toner particles.

Let A (angstrom%) be the amount of carbon atoms present on the surface of the toner particles measured by the X-ray photoelectron spectrometer, and E be the amount of sulfur atoms present on the surface of the toner particles measured by the X-ray photoelectron spectrometer. When (atomic%) is set, the E / A preferably satisfies the following formula (1), and more preferably the following formula (1)'.
The E / A can be adjusted, for example, by including the charge control resin in the toner particles.
3 × 10 ^-4 ≦ E / A ≦ 50 × 10 ^-4 (1)
5 × 10 ^-4 ≤ E / A ≤ 30 × 10 ^-4 (1)'
By setting the E / A in the above range, the electrostatic adhesion between the toner particles and the strontium titanate particles becomes higher, and the strontium titanate particles are less likely to migrate from the toner particles. In addition, since it is also excellent in the function of adjusting the resistance value, the developability is further improved, and it becomes easier to suppress the occurrence of fog and member contamination.

The toner particles may contain wax. Examples of the wax include the following.
Petroleum waxes and derivatives such as paraffin wax, microcrystallin wax and petrolatum; Montan wax and derivatives thereof; hydrocarbon waxes and derivatives by Fishertropus method; polyolefin waxes and derivatives such as polyethylene and polypropylene; carnauba wax and derivatives thereof; Natural waxes and derivatives thereof such as candelilla waxes; higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid; acid amide waxes; ester waxes.
Examples of the derivative include oxides, block copolymers with vinyl-based 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 the binder resin capable of producing the binder resin. More preferably, it is 0.0 parts by mass or more and 10.0 parts by mass or less.

The toner particles may contain a colorant.
Examples of the black colorant include those colored black using carbon black, a magnetic material, and the following yellow, magenta, and cyan colorants.
Examples of the yellow colorant 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 can be mentioned.
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. Pigment Bio Red 19.
Examples of the cyan colorant include a copper phthalocyanine compound and its derivative, an anthraquinone compound, and a basic dye lake compound.
Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66.
The colorant can be used alone or mixed, and further in the form of a solid solution.
The colorant may be selected from the viewpoints of hue angle, saturation, lightness, 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 the binder resin capable of producing the binder resin.

The toner particles can also be made into magnetic toner particles by containing a magnetic substance 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 material is preferably a magnetic material whose surface is modified.
When the magnetic toner is prepared by a polymerization method, it is preferable that the magnetic toner is hydrophobized with a surface modifier which is a substance that does not inhibit polymerization. Examples of such a surface modifier include a silane coupling agent and a titanium coupling agent.
The number average particle size 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 material 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 the binder resin capable of producing the binder resin. More preferably, it is less than or equal to a part.

On the other hand, an example of a manufacturing method for manufacturing toner particles by the pulverization method will be described below.
In the raw material mixing step, as a material constituting the toner particles, a binder resin, a colorant, a wax, and the like are weighed in a predetermined amount, blended, and mixed.
Examples of the mixing device 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 Nippon Coke Industries, Ltd.).
Next, the mixed materials are melt-kneaded to disperse the colorant, wax, and the like in the binder resin. In the melt-kneading step, a batch-type kneader such as a pressure kneader or a Bambary mixer or a continuous-type kneader can be used. Single-screw or twin-screw extruders have become the mainstream because of their superiority in continuous production. 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 KTK). , Co-kneader (manufactured by Bus Co., Ltd.), and Kneedex (manufactured by Nippon Coke Industries Co., Ltd.). Further, the resin composition obtained by melt-kneading may be rolled with two rolls or the like and cooled with water or the like in the cooling step.

Then, the obtained cooled product is pulverized to a desired particle size in the pulverization step.
In the crushing step, coarse crushing is performed with a crusher such as a crusher, a hammer mill, or a feather mill. After that, it is advisable to pulverize with a cryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), a super rotor (manufactured by Nisshin Engineering Co., Ltd.), a turbo mill (manufactured by Freund Turbo Co., Ltd.), or an air jet pulverizer.
After that, if necessary, inertial classification type elbow jet (manufactured by Nittetsu Mining Co., Ltd.), centrifugal force classification type turboplex (manufactured by Hosokawa Micron Co., Ltd.), TSP separator (manufactured by Hosokawa Micron Co., Ltd.), faculty (manufactured by Hosokawa Micron Co., Ltd.), etc. Toner particles are obtained by classifying using a classifier or a sieve.
Further, the toner particles may be made spherical. For example, after crushing, spheroidization is performed using a hybridization system (manufactured by Nara Machinery Co., Ltd.), a mechanofusion system (manufactured by Hosokawa Micron Co., Ltd.), faculty (manufactured by Hosokawa Micron Co., Ltd.), and Meteole Invo MR Type (manufactured by Nippon Pneumatic Industries Co., Ltd.). It is good.

Toner can be obtained by mixing strontium titanate particles and, if necessary, other external additives with the toner particles. Examples of the mixer for mixing the external additive include FM mixer (manufactured by Nippon Coke Industries Co., Ltd.), super mixer (manufactured by Kawata Co., Ltd.), Nobilta (manufactured by Hosokawa Micron Co., Ltd.), and hybridizer (manufactured by Nara Machinery Co., Ltd.). Be done.
In addition, the coarse particles may be sifted after mixing the external additives. Examples of the sieving device used for that purpose include the following.
Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonator Sheave, Gyroshifter (manufactured by Tokuju Kosakusho); Vibrasonic System (manufactured by Dalton); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); ); Micro shifter (manufactured by Makino Sangyo Co., Ltd.).

The toner may contain an external additive other than the 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 resin powders such as vinylidene fluoride fine powder and polytetrafluoroethylene fine powder; silica fine particles such as wet manufacturing silica or dry manufacturing silica, titanium oxide fine particles, alumina fine particles; the fine particles are 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. Compound 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 silica fine particles, so-called dry silica or fumed silica, are preferable.
The dry production method utilizes, for example, a pyrolysis oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.
SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl
In this manufacturing process, it is also 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. do.
The fluidity improver is preferable when the number average particle diameter of the primary particles is 5 nm or more and 30 nm or less because it can have high chargeability and fluidity.
Further, the silica fine particles are more preferably hydrophobized silica fine particles surface-treated with the hydrophobizing agent.
The fluidity improver preferably has a specific surface area of 30 m ² / g or more and 300 m ² / g or less due to nitrogen adsorption measured by the BET method.
The content of the fluidity improver is preferably 0.01 parts by mass or more and 3.0 parts by mass or less in total with respect to 100 parts by mass of the toner particles.

Methods for measuring various physical properties of toner and other materials will be described below.
The physical properties of strontium titanate particles are measured using toner as a sample.
When measuring the physical properties of the strontium titanate particles and the toner particles from the toner to which the strontium titanate particles are externally attached, it is preferable to separate the 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 the mixture is allowed to stand for 24 hours. Toner particles can be isolated by separating the precipitated toner particles from the strontium titanate particles dispersed in the supernatant and other external additives, recovering the particles, and sufficiently drying the particles. In addition, strontium titanate particles can be isolated by treating the supernatant liquid by centrifugation.

<Measurement of number average particle size of primary particles of strontium titanate particles>
The number average particle size of the primary particles of strontium titanate particles is measured using a transmission electron microscope "JEM-2800" (JEOL Ltd.).
Observe the toner externally attached with strontium titanate particles, and randomly measure the major axis of 100 primary particles of strontium titanate particles in a field magnified up to 200,000 times to obtain the 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 Co., Ltd., 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 the analysis software attached to the above apparatus.
As the measurement sample, toner or strontium titanate particles isolated from the toner are used, and measurement is performed by the following procedure. In the following examples, the produced strontium titanate particles are also measured.
(Preparation of sample)
The 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 stand: Capillary sample stand ・ Detector: D / tex Ultra250 detector ・ Voltage: 45 kV
・ Current: 200mA
・ Starting angle: 10 °
・ End angle: 90 °
・ Sampling width: 0.02 °
・ Speed measurement time setting value: 10
・ IS: 1mm
・ RS1: 20mm
・ RS2: 20mm
・ Attenuator: Open
・ Capillary rotation speed setting value: 100
For other conditions, the default values of the device are used.
(analysis)
First, the obtained peak is subjected to peak separation processing using the software "PDXL2" attached to the apparatus. The peak separation is obtained by executing the optimization using the "divided Voigt function" that can be selected by PDXL, and the obtained value of the integrated intensity is used.
This determines the 2θ value of the diffraction peak top and its area. 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 significantly different from each other, the calculation result and the actually measured spectrum are adjusted so as to match by processing such as manually setting the baseline.

<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 fluorescent X-ray analyzer (Axios advanced, manufactured by PANalytical).
1 g of a sample is weighed on a special film for powder measurement recommended by PANalytical, and the elements from Na to U in strontium titanate particles are measured by the FP method under atmospheric pressure He atmosphere.
At that time, assuming that all the detected elements are oxides, and assuming that their total mass is 100%, the content (mass%) _{of SrO and TiO 2 with respect to the total mass by software SpectraEvolution (version 5.0L).} Is calculated as an oxide conversion value.
After that, Sr / Ti (mass ratio) obtained by removing oxygen from the quantification result is obtained, and then converted to Sr / Ti (molar ratio) from the atomic weight of each element.
As the sample, strontium titanate particles isolated from the toner are used. Further, in the following examples, the produced strontium titanate particles are also measured.

<Measurement of average circularity of primary particles of strontium titanate particles>
The average circularity of the primary particles of strontium titanate particles is measured using a transmission electron microscope "JEM-2800" (JEOL Ltd.).
Observe the toner externally attached with strontium titanate particles and calculate 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" (manufactured by Media Cybernetics), the circle-equivalent diameter of 100 strontium titanate particles and the circumference of the particles are randomly measured in a field magnified up to 200,000 times. 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 mean value is used as the average circularity.
(Formula) Circularity = equivalent circle diameter x 3.14 / perimeter of particles Confirmation that the external additive is strontium titanate is carried out by STEM-EDS measurement.
The measurement conditions are as follows.
JEM2800 type transmission electron microscope: Acceleration voltage 200 kV
EDS detector: JED-2300T (JEOL, element area 100 mm ² )
EDS Analyzer: Noran System7 (Thermo Fisher Scientific)
X-ray storage rate: 10000-15000 cps
Dead time: Adjust the electron dose so that it is 20 to 30%, and perform EDS analysis (integration number 100 times or measurement time 5 min).

<Measurement of hydrophobicity (volume%) of strontium titanate particles>
The degree of hydrophobization (volume%) of the strontium titanate particles is measured by a powder wettability tester "WET-100P" (manufactured by Reska).
A fluororesin-coated spindle-shaped rotor having a length of 25 mm and a maximum body diameter of 8 mm is placed in a cylindrical glass container having a diameter of 5 cm and a thickness of 1.75 mm.
70 mL of a hydrous methanol solution consisting of 50% by volume of methanol and 50% by volume of water is placed in the cylindrical glass container. Then, 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 to 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 represented by the volume percentage of methanol when the transmittance reaches 50% (= (volume of methanol / volume of mixture) × 100) is defined as the degree of hydrophobicity. .. The volume ratio of initial methanol to water is adjusted as appropriate according to the degree of hydrophobization of the sample. Further, in the following examples, the produced strontium titanate particles are also measured.

<Measurement of coverage with strontium titanate particles on the toner surface>
The coverage of the toner surface with strontium titanate particles (in Table 3, simply referred to as "coverage") is calculated from the following formula (2) by measuring the toner under the following conditions.
-Measuring device: X-ray photoelectron spectrometer: Quantum2000 (manufactured by ULVACPHI Co., Ltd.)
・ X-ray source: Monochrome Al Kα
-Xray Setting: 100 μmφ (25 W (15 KV))
・ Photoelectron extraction angle: 45 degrees ・ Neutralization condition: Combined use of neutralization gun and ion gun ・ Analysis area: 300 × 200 μm
-Pass Energy: 58.70 eV
-Step size: 0.125 eV
・ Analysis software: Maltipak (PHI)
Here, the peak of Ti 2p (BE 452-468eV) is used for the calculation of the quantitative value of the Ti atom. Let Z1 be the quantitative value of the Ti element obtained here.
Next, the elemental analysis of the strontium titanate particles alone is performed in the same manner as in the above elemental analysis, and the quantitative value of the Ti element obtained here is defined as Z2. The coverage of the toner surface with strontium titanate particles is calculated by the following formula (2).
Coverage = Z1 / Z2 x 100 (2)

<Measurement of average circularity of toner>
The average circularity of the toner is measured by the flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions at the time of calibration work.
The specific measurement method is as follows.
First, about 20 mL of ion-exchanged water from which impure solids and the like have been removed in advance is placed in a glass container. Among them, as a dispersant, "Contaminone N" (a 10% by mass aqueous solution of a neutral detergent for cleaning a precision measuring instrument with a pH of 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd. ) Is diluted about 3 times by mass with ion-exchanged water, and about 0.2 mL of the diluted solution is added.
Further, about 0.02 g of the measurement sample is added, and the dispersion treatment is performed for 2 minutes using an ultrasonic disperser to prepare a dispersion liquid for measurement. At that time, the dispersion is appropriately cooled so that the temperature of the dispersion is 10 ° C to 40 ° C.
As the ultrasonic disperser, a desktop ultrasonic cleaner disperser (for example, "VS-150" (manufactured by Vervocrea)) having an oscillation frequency of 50 kHz and an electrical output of 150 W is used, and a predetermined amount is contained in the water tank. Ion-exchanged water is added, and about 2 mL of the Contaminone N is added into the water tank.
For the measurement, a flow-type particle image analyzer equipped with "LUCPLFLN" (magnification 20 times, numerical aperture 0.40) was used as the objective lens, and the particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. use. The dispersion prepared according to the above procedure is introduced into a flow-type particle image analyzer, and 2000 toners are measured in the total count mode in the HPF measurement mode.
Then, the binarization threshold value at the time of particle analysis is set to 85%, the diameter of the analyzed particle is limited to 1.977 μm or more and less than 39.54 μm, and the average circularity of the toner is obtained.
In the measurement, automatic focus adjustment is performed using standard latex particles (for example, "RESAARCH AND TEST PARTICLES Latex Microsphere Suspensions 5100A" manufactured by Duke Scientific Co., Ltd. diluted with ion-exchanged water) before the start of the measurement. After that, it is preferable to perform focus adjustment every 2 hours from the start of measurement.
In the examples, a flow-type particle image analyzer that was calibrated by Sysmex and received a calibration certificate issued by Sysmex was used. The measurement is performed under the measurement and analysis conditions when the calibration certificate is obtained, except that the particle size to be analyzed is limited to the equivalent circle diameter of 1.977 μm or more and less than 39.54 μm.

<Measurement of toner glass transition temperature (Tg)>
The glass transition temperature of the toner is measured according to ASTM D3418-82 using a differential scanning calorimeter "Q1000" (manufactured by TA Instruments).
The melting points of indium and zinc are used for temperature correction of the device detector, and the heat of fusion of indium is used for the correction of calorific value.
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 within the measurement temperature range of 30 ° C. or higher and 200 ° C. or lower. The measurement is performed at a speed of 10 ° C./min.
In the measurement, the temperature is once raised to 200 ° C., then lowered to 30 ° C. at a temperature lowering rate of 10 ° C./min, and then again raised at a temperature raising rate of 10 ° C./min.
In the DSC curve obtained in the second heating process, the intersection of the midpoint of the baseline before and after the specific heat change and the DSC curve is defined as the glass transition temperature (Tg).

<Measurement of E / A on the surface of toner particles>
The ratio (E / A) of the amount of sulfur atoms (E (atomic%)) to the amount of carbon atoms (A (atomic%)) present on the surface of the toner particles is the X-ray photoelectron spectrometer (ESCA) "1600S type". (Physical Electronics Industries, Inc.) is used to analyze the composition of the surface of the toner particles, and the calculation is performed based on the analysis result.
The measurement conditions are an X-ray source MgKα (400W) and a spectral region of 800 μmφ.
From the measured peak intensity of each atom, Physical Electricals Industries, Inc. The surface atomic concentration (atomic%) is calculated using the relative sensitivity factor provided by the company and used as the amount of each atom.
The range of the measurement peak top of each atom used for the measurement is carbon atom: 283 to 293 eV and sulfur atom: 166 to 172 eV.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Unless otherwise specified, the number of copies of Examples and Comparative Examples are all based on mass.

The strontium titanate particles were prepared as follows. Table 1 shows the physical properties of the strontium titanate particles 1 to 15.

<Production example of strontium titanate particles 1>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 1. Obtained. A transmission electron micrograph of the strontium titanate particles 1 is shown in FIG.

<Production example of strontium titanate particles 2>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 1.15, and then 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 2. Obtained.

<Production example of strontium titanate particles 3>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 3. Obtained.

<Production example of strontium titanate particles 4>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 4. Obtained.

<Production example of strontium titanate particles 5>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out 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 the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 5. Obtained.

<Production example of strontium titanate particles 6>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out 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 the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 6. Obtained.

<Production example of strontium titanate particles 7>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. An aqueous solution of strontium chloride was added to the deflated metatitanic acid slurry in an amount of 2.01 mol 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 7. Obtained.

<Production example of strontium titanate particles 8>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. 2.54 mol of an aqueous solution of strontium chloride was added to the deflated metatitanic acid slurry so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 8. Obtained.

<Production example of strontium titanate particles 9>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. 2.54 mol of an aqueous solution of strontium chloride was added to the deflated metatitanic acid slurry so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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 was added to the solid content, and stirring and holding was continued for 1 hour. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 9. Obtained.

<Production example of strontium titanate particles 10>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. 2.54 mol of an aqueous solution of strontium chloride was added to the deflated metatitanic acid slurry so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, the dried product was treated three times for 3 minutes at 6,000 rpm using a hybridizer (manufactured by Nara Machinery Co., Ltd.).
Further, hydrochloric acid was added to the dried product until the pH reached 0.1, and stirring was continued for 1 hour. The obtained precipitate was decanted and washed, filtered and washed, and the obtained cake was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 10.

<Production example of strontium titanate particles 11>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 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 sodium hydroxide aqueous 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 the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 11. Obtained.

<Production example of strontium titanate particles 12>
The metatitanic acid slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an aqueous alkaline 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 became 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 replaced with nitrogen gas.
Further, distilled water was added so as to be 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 the reaction was carried out for 6 hours after reaching 83 ° C. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 12.

<Production example of strontium titanate particles 13>
After the metatitanic acid obtained by the sulfuric acid method was deironed and bleached, an aqueous sodium hydroxide solution was added to adjust the pH to 9.0, desulfurization was performed, and then neutralized to pH 5.8 with hydrochloric acid and washed with filtered water. Water was added to the washed cake to make _{a slurry of 1.85 mol / L as TiO 2} , and then hydrochloric acid was added to adjust the pH to 1.0 to perform a gelatinization treatment.
1.88 mol of desulfurized and deglued metatitanium acid _{was collected as TiO 2} and placed in a 3 L reaction vessel. To the deflated metatitanic acid slurry, 2.16 mol of an aqueous solution of strontium chloride was added so as to have an Sr / Ti (molar ratio) of 1.15, and then 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 sodium hydroxide aqueous 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 the pH reached 5.0, and stirring was continued for 20 minutes. The obtained precipitate was decanted and washed, filtered and separated, and then dried in the air at 120 ° C. for 8 hours.
Subsequently, 300 g of the dried product was put into a dry particle composite device (Nobilta NOB-130 manufactured by Hosokawa Micron). The treatment was carried out at a treatment temperature of 30 ° C. and a rotary treatment blade of 90 m / sec for 10 minutes.
Further, hydrochloric acid was added to the dried product until the pH reached 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., hydrochloric acid was added to adjust the pH to 2.5, 4.0% by mass of n-octyltriethoxysilane was added to the solid content, and stirring and holding were continued for 10 hours. .. After adding 5 mol / L sodium hydroxide solution to adjust the pH to 6.5 and continuing stirring for 1 hour, the cake obtained by filtration and washing was dried in the air at 120 ° C. for 8 hours to obtain strontium titanate particles 13. Obtained.

<Production example of strontium titanate particles 14>
The hydrous titanium oxide obtained by hydrolysis by adding ammonia water to an aqueous titanium tetrachloride solution was washed with pure water, added 0.25% of sulfuric acid as SO ₃ for the hydrous titanium oxide to a slurry of hydrous titanium oxide did.
Next, hydrochloric acid was added to the slurry of titanium hydroxide-containing titanium 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 became 50 μS / cm.
To titanium hydroxide-containing titanium, 0.95 times the molar amount of strontium hydroxide octahydrate was added and placed in a stainless steel reaction vessel, which was replaced with nitrogen gas. Further, 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 10 ° C./hour in a nitrogen atmosphere, and the reaction was carried out for 8 hours after reaching 65 ° C. After the reaction, the mixture was cooled to room temperature, the supernatant was removed, and then washing was repeated with pure water.
Further, under a nitrogen atmosphere, the above slurry was placed in an aqueous solution in which 2% by mass of sodium stearate was dissolved with respect to the solid content of the slurry, and an aqueous magnesium sulfate solution was added dropwise with stirring to add stearic acid to the surface of the perovskite-type crystal. Magnesium was precipitated.
The slurry was repeatedly washed with pure water and then filtered through Nutche, and the obtained cake was dried to obtain strontium titanate particles 14 surface-treated with magnesium stearate.

<Production example of strontium titanate particles 15>
The hydrous titanium slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an aqueous alkaline solution. Next, hydrochloric acid was added to the slurry of titanium hydroxide-containing titanium 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 became 100 μS / cm.
To titanium hydroxide-containing titanium, 1.02 times the molar amount of strontium hydroxide octahydrate was added, and the mixture was placed in a stainless steel reaction vessel and replaced 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 the reaction was carried out for 5 hours after reaching 90 ° C. After the reaction, the mixture was cooled to room temperature, the supernatant was removed, washing was repeated with pure water, and then filtration was performed with Nutche. The obtained cake was dried to obtain strontium titanate particles 15.

<Production example of charge control resin 1>
250 parts of methanol, 150 parts of 2-butanone and 100 parts of 2-propanol as a solvent, and styrene as a monomer in a pressurable reaction vessel equipped with a reflux tube, a stirrer, a thermometer, a nitrogen introduction tube, a dropping device and a depressurizing device. 83 parts, 12 parts of butyl acrylate and 5 parts of 2-acrylamide-2-methylpropanesulfonic acid were added and heated to the reflux temperature with stirring.
A solution obtained by diluting 0.45 parts of t-butylperoxy-2-ethylhexanoate, which is a polymerization initiator, with 20 parts of 2-butanone was added dropwise over 30 minutes, and stirring was continued for 5 hours. A solution obtained by diluting 0.28 parts of -butylperoxy-2-ethylhexanoate with 20 parts of 2-butanone was added dropwise over 30 minutes, and the mixture was further stirred for 5 hours to complete the polymerization.
The polymer obtained after distilling off the polymerization solvent under reduced pressure was roughly pulverized to 100 μm or less using a cutter mill equipped with a 150 mesh screen to obtain a charge control resin 1. The glass transition temperature (Tg) of the obtained polymer was about 70 ° C.

Toner particles were prepared as follows. Table 2 shows the physical characteristics of the obtained toner particles 1 to 9.
<Production example of toner particles 1>
710 parts of ion-exchanged water and _{850 parts of a 0.1 mol / L Na 3} PO ₄ aqueous solution were added to the four-mouthed container, and the high-speed agitator T.I. K. The temperature was maintained at 60 ° C. while stirring at 12,000 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). 68 parts of a 1.0 mol / L CaCl ₂ aqueous solution was gradually added thereto to prepare an aqueous medium containing a dispersion stabilizer.
-Styrene 124 parts-n-butyl acrylate 36 parts-Copper phthalocyanine pigment (Pigment Blue 15: 3) 13 parts-Polyester resin 110 parts (terephthalic acid-propylene oxide modified bisphenol A (2 molar adduct) copolymer, acid Value: 10 mgKOH / g, glass transition temperature (Tg): 70 ° C., weight average molecular weight (Mw): 10500)
-Charge control resin 1 2 parts-Fishertropsh wax (melting point: 78 ° C) 15 parts The above material was stirred for 3 hours using an attritor (manufactured by Nippon Coke Industries Co., Ltd.), and each component was put into a polymerizable monomer. It was dispersed to prepare a monomeric mixture.
To the monomer mixture, 20.0 parts (50% of toluene solution) of 1,1,3,3-tetramethylbutylperoxy2-ethylhexanoate, which is a polymerization initiator, is added to form a polymerizable monomer composition. Was prepared.
The polymerizable monomer composition was put into an aqueous medium, and granulated for 5 minutes while maintaining the rotation speed of the stirrer at 10000 rpm. Then, the high-speed stirrer was changed to a propeller-type stirrer, the internal temperature was raised to 70 ° C., and the reaction was carried out for 6 hours with slow stirring.
Next, the inside of the container was heated to a temperature of 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 filtering, washing and drying.

<Production example of toner particles 2>
In the production example of the toner particles 1, the polyester resin 1 is used as a polyester resin 2 (terephthalic acid-propylene oxide-modified bisphenol A (2 mol additive) copolymer, acid value: 13 mgKOH / g, glass transition temperature (Tg): 67 ° C.). , Weight average molecular weight (Mw): 9800), and the granulation conditions after the polymerizable monomer composition was put into the aqueous dispersion medium were granulated for 8 minutes while maintaining the rotation 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 particles 3>
In the production example of the toner particles 1, the polyester resin 1 is used as a polyester resin 3 (terephthalic acid-propylene oxide-modified bisphenol A (2 mol additive) copolymer, acid value: 5 mgKOH / g, glass transition temperature (Tg): 71 ° C.). , Weight average molecular weight (Mw): 11800), and the granulation conditions after putting the polymerizable monomer composition into the aqueous medium are granulated for 5 minutes while maintaining the rotation 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 particles 4>
In the production example of the toner particles 1, the toner particles 4 were obtained in the same manner except that the amount of styrene added was changed from 124 parts to 130 parts and the amount of n-butyl acrylate added was changed from 36 parts to 30 parts.

<Manufacturing example of toner particles 5>
In the production example of the toner particles 1, the toner particles 5 were obtained in the same manner except that the amount of styrene added was changed from 124 parts to 115 parts and the amount of n-butyl acrylate added was changed from 36 parts to 45 parts.

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

<Manufacturing example of toner particles 7>
In the production example of the toner particles 1, the toner particles 7 were obtained in the same manner except that the amount of styrene added was changed from 124 parts to 110 parts and the amount of n-butyl acrylate added was changed from 36 parts to 50 parts.

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

<Manufacturing example of toner particles 9>
In the production example of the toner particles 7, the toner particles 9 were obtained in the same manner except that the charge control resin 1 was not added.

<Manufacturing example of toner 1>
With respect to the obtained toner particles 1 (100 parts), the amount of strontium titanate particles 1 (1.5 parts) and fumed silica fine particles (BET: 200 m ^{2 /} g) (1.5 parts) , The particles were externally mixed by FM10C (manufactured by Nippon Coke Industries Co., Ltd.).
The external addition conditions were as follows: the amount of toner particles charged: 1.8 kg, the rotation speed: 3600 rpm, and the external addition time: 5 minutes.
Then, the toner 1 was obtained by sieving with a mesh having a mesh size of 200 μm.
The physical characteristics of the toner 1 are shown in Table 3. The average circularity, Tg, and E / A of the toner were the same as those in Table 2. Further, the physical characteristics of the strontium titanate particles 1 externally attached to the toner were the same as those in Table 1.

<Example 1>
The following evaluation was performed using the obtained toner 1. The evaluation results are shown in Table 4.
<Evaluation machine>
The HP Laser LaserJet Enterprise M651n, a laser beam printer manufactured by HP, was modified and evaluated so that it could be operated even when only one color process cartridge was installed. As the evaluation paper, CS-680 sold by Canon Marketing Japan was used. Toner was filled into a given process cartridge.

<Developability>
The developability was evaluated in a low temperature and low humidity environment (temperature 10 ° C., relative humidity 14%) which is easily affected by chargeability. Further, in a low temperature and low humidity environment, the toner does not easily rise in temperature and is difficult to be plasticized through repeated use for a long period of time, so that the condition is severe against cracking of the toner.
Assuming a long-term repeated use test, a mode in which the horizontal line pattern with a print rate of 1% is set as 2 sheets / job, and the machine is stopped between jobs and then the next job is started. Therefore, a total of 20000 image printing tests were carried out. The image densities of the first and 20,000th images were measured.
The image density was measured by outputting a solid image of a 5 mm circle and measuring the reflection density using a Macbeth densitometer (manufactured by Macbeth), which is a reflection densitometer, using an SPI filter.
The larger the value, the better the developability.

<Cover>
The fog was evaluated in a low temperature and low humidity environment that is easily affected by chargeability. Further, in a low temperature and low humidity environment, the toner does not easily rise in temperature and is difficult to be plasticized through repeated use for a long period of time, so that the condition is severe against toner cracking.
After outputting the first and 20,000 images in the evaluation of developability, a solid white image is output, the worst value of the reflection density on the white background is Ds, and the average reflection density of the evaluation paper before image formation is Dr. , Dr-Ds was used as the cover value.
A reflection densitometer (reflectometer model TC-6DS) is used to measure the reflection density on a white background.
(Made by Tokyo Denshoku Co., Ltd.) was used, and an amber light filter was used as the filter.
The smaller the value, the better the fog level.

<Developability after leaving>
In a high-temperature and high-humidity environment (temperature 30 ° C, relative humidity 80%), the horizontal line pattern with a printing rate of 1% is set as 2 sheets / job, and the next job starts after the machine stops temporarily between jobs. In the mode set as described above, a total of 5000 image drawing tests were carried out.
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 stricter conditions for maintaining chargeability.
After outputting 5000 images, a 5 mm round solid image was output, and after being left 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 using a Macbeth densitometer (manufactured by Macbeth), which is a reflection densitometer, using an SPI filter.
Compared with the reflection density of the solid image after the output of 5000 images, the smaller the decrease in the reflection density of the solid image after leaving for 3 days, the better the developability after leaving.

<Member pollution>
Image defects may occur when the developing blade is contaminated. Development blade contamination was evaluated by transferring the cartridge to a high temperature and high humidity environment after performing imaging in a low temperature and low humidity environment where toner cracking is severe.
The reason for moving to a high temperature and high humidity environment is to facilitate the occurrence of developing blade contamination due to toner cracking.
The cartridges that output 20000 sheets in the evaluation of the fog in the low temperature and low humidity environment were moved to the high temperature and high humidity environment.
A horizontal line pattern with a print rate of 1% is set as one sheet / job, and a printing test of 3000 sheets is performed in a mode set so that the machine stops once between jobs and then the next job starts. did.
Subsequently, a halftone image having an image density of 0.6 in the density of the Macbeth reflection densitometer described above was output with respect to the transport direction of the transfer paper so that the image defect caused by the contamination of the developing blade could be easily discriminated. This image was visually observed, and the presence or absence of vertical streaks along the transport direction generated by contamination of the developing blade was evaluated based on the following criteria.
A: No white streaky vertical lines can be seen on the image.
B: One or two white streaky vertical lines can be seen thinly on the image.
C: One or two clear white streaky vertical lines can be seen on the image.
D: Three or more clear white streaky vertical lines can be seen on the image.

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

<Manufacturing examples of toners 2 to 20 and comparative toners 1 to 5>
In the same manner as in the production example of toner 1, the toners 2 to 20 and the comparative toners 1 to 1 are the same as in the production example of toner 1, except that the types and addition amounts of the toner particles and strontium titanate particles used are changed from the production example of toner 1. I got 5. The physical characteristics of the toners 2 to 20 and the comparative toners 1 to 5 are shown in Table 3. In the toners 2 to 20 and the 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 characteristics of the strontium titanate particles externally attached to the toner were also the same as in Table 1.

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

Claims (11)

A toner containing toner particles and an external additive,
The external agent contains strontium titanate particles and
The average circularity of the toner is 0.935 or more and 0.995 or less.
The strontium titanate particles are
The average particle size of the number of primary particles is 10 nm or more and 60 nm or less.
The strontium titanate particles are 39.700 ° ± 0.150 ° and 46.200 ° in the X-ray diffraction spectrum of CuKα obtained in the range where 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 °,
Let Sa be the area of the peak at 39.700 ° ± 0.150 °.
When the area of the peak 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 glass transition temperature of the toner is 50 ° C. or higher and 70 ° C. or lower. The strontium titanate particles, Sr / Ti (molar ratio) is 0.70 to 0.85, toner according to claim 1 or 2. The average circularity of the primary particles of strontium titanate particles is 0.700 or more 0.920 or less, the toner according to any one of claims 1 to 3. The toner according to claim 4, wherein the average circularity of the primary particles of the strontium titanate particles is 0.790 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 transmittance of light having a wavelength of 780 nm is 50% in a wettability test with a mixed solvent of methanol / water. the toner according to any one of 5. Any of claims 1 to 6 , wherein the coverage of the surface of the toner by strontium titanate particles measured by an X-ray photoelectron spectrometer is 5.0 area% or more and 20.0 area% or less.
The toner according to item 1. The content of strontium titanate particles, the toner particles 100 parts by mass or less 5.0 parts by mass or more 0.05 part by mass, the toner according to any one of claims 1-7. The toner particles are toner particles having a core, a shell layer on the surface of the core, the toner according to any one of claims 1-8. The toner according to claim 9 , wherein the shell layer contains at least one selected from the group consisting of a polyester resin, a styrene-acrylic copolymer, and a styrene-methacryl copolymer. The amount of carbon atoms present on the surface of the toner particles measured by an X-ray photoelectron spectrometer is defined as A (angstrom%).
When the amount of sulfur atoms present on the surface of the toner particles measured by an X-ray photoelectron spectrometer is E (atomic%),
E / A satisfies the following formula (1),
3 × 10 ^-4 ≦ E / A ≦ 50 × 10 ^-4 (1)
The toner according to any one of claims 1 to 10.

Images