Silica particles

Abstract

A kind of silicon dioxide particle, it contains nitrogen element compound comprising molybdenum element, and the ratio Mo / Si of Net intensity of molybdenum element determined by fluorescent X-ray analysis and the Net intensity of silicon element is 0.035 or more and 0.35 or less.

Description

Technical Field

[0001] This invention relates to silicon dioxide particles. Background Technology

[0002] Silica particles are used as additives or main components in powder coatings, cosmetics, rubber, abrasives, etc., for example, to improve the strength of resins, improve the flowability of powders, and inhibit packing.

[0003] For example, Patent Document 1 discloses "a hydrophobic silica powder, wherein (1) the degree of hydrophobicity is 50% or more, (2) the extraction amount X of at least one compound selected from the group including quaternary ammonium ions, monoazo complexes and inorganic acid radicals extracted by a mixed solvent of methanol and methanesulfonic acid aqueous solution is 0.1% by mass or more, and (3) the extraction amount X and the extraction amount Y of the compound extracted by water satisfy the following formula (I) Y / X < 0.15".

[0004] Furthermore, Patent Document 2 discloses "a silica powder comprising a plurality of silica particles, wherein the silica particles are incorporating quaternary ammonium salts in a silica structure having "Si-O" bonds as repeating units."

[0005] Furthermore, Patent Document 3 discloses "an external charge control particle, which consists of a transport particle and a charge control agent adhering to the surface of the transport particle, wherein the transport particle is composed of hydrophobic spherical silica particles with an average particle size of 20 to 500 nm obtained by hydrophobizing the surface of hydrophilic spherical silica particles obtained by sol-gel method."

[0006] Furthermore, Patent Document 4 discloses "a silica microparticle, which is prepared by treating spherical hydrophobic silica microparticles with an average particle size of 0.01 to 5 μm with a compound selected from the group consisting of quaternary ammonium salt compounds, betaine compounds containing fluoroalkyl groups and silicone oils".

[0007] Furthermore, Patent Document 5 discloses "particles formed by treating silica particles with a hydrophobicity of 80% or more with an amphoteric surfactant and particles formed by treating silica particles with a hydrophobicity of 80% or more with a quaternary ammonium salt or a polymer having a quaternary ammonium group".

[0008] Patent Document 1: Japanese Patent Application Publication No. 2019-073418

[0009] Patent Document 2: Japanese Patent Application Publication No. 2017-039618

[0010] Patent Document 3: Japanese Patent Application Publication No. 2011-185998

[0011] Patent Document 4: Japanese Patent Application Publication No. 2001-194825

[0012] Patent Document 5: Japanese Patent Application Publication No. 09-166884 Summary of the Invention

[0013] The objective of this invention is to provide a silica particle that, compared to silica particles containing a nitrogen-containing compound including molybdenum, has a narrow charge distribution when charged, and exhibits excellent maintenance of this narrow charge distribution under both high-temperature and high-humidity and low-temperature and low-humidity environments.

[0014] The specific methods used to solve the above problems include the following approaches.

[0015] <1>

[0016] A type of silica particle containing a nitrogen-containing compound including molybdenum.

[0017] Furthermore, the ratio of the net intensity of molybdenum to the net intensity of silicon, as determined by fluorescence X-ray analysis, is greater than 0.035 and less than 0.35.

[0018] <2>

[0019] According to the silicon dioxide particles described in <1>, wherein,

[0020] The nitrogen-containing compound is selected from at least one of the group consisting of quaternary ammonium salts containing molybdenum and mixtures of quaternary ammonium salts and metal oxides containing molybdenum.

[0021] <3>

[0022] The silica particles described in <1> or <2> have an average particle size of 10 nm or more and 200 nm or less.

[0023] <4>

[0024] The silica particles according to any one of <1> to <3> have silica masterbatch and structure.

[0025] The structure, which covers at least a portion of the surface of the silica masterbatch, is composed of at least one reaction product selected from the group consisting of monofunctional silane coupling agents, difunctional silane coupling agents, and trifunctional silane coupling agents.

[0026] Furthermore, at least a portion of the micropores of the reaction product adsorbs nitrogen-containing compounds.

[0027] <5>

[0028] The silica particles according to any one of <1> to <4> have a hydrophobicity of 10% or more and 60% or less.

[0029] <6>

[0030] The silicon dioxide particles according to any one of <1> to <5>, wherein,

[0031] When the pore volumes (those with pore diameters greater than 1 nm and less than 50 nm, determined from the pore distribution curves obtained by nitrogen adsorption before and after calcination at 350℃) are denoted as A and B respectively, the ratio of B / A is greater than 1.2 and less than 5, and B is 0.2 cm. 3 / g or more and 3cm 3 / g or less.

[0032] <7>

[0033] The silicon dioxide particles according to any one of <1> to <6>, wherein,

[0034] Obtained through the cross-polarization / magic-angle rotation (CP / MAS) method 29 The ratio C / D of the integral value C of the signal observed in the range of chemical shift above -50 ppm and below -75 ppm to the integral value D of the signal observed in the range of chemical shift above -90 ppm and below -120 ppm is greater than 0.10 and less than 0.75.

[0035] <8>

[0036] The silicon dioxide particles according to any one of <1> to <7>, wherein,

[0037] The extraction yield X of the nitrogen-containing compound obtained using an ammonia / methanol mixed solution is 0.1% by mass or more.

[0038] The extraction amount X of the nitrogen-containing compound and the extraction amount Y of the nitrogen-containing compound extracted using water satisfy the formula: Y / X < 0.3.

[0039] <9>

[0040] The silica particles according to any one of <1> to <8> have an average sphericity of 0.60 or more and 0.96 or less.

[0041] <10>

[0042] The number-size distribution index of the silica particles according to any one of <1> to <9> is 1.1 or more and 2.0 or less.

[0043] Invention Effects

[0044] According to <1> or <2> of the present invention, silica particles can be provided that have a narrow charge distribution when charged, compared with silica particles containing nitrogen-containing compounds including molybdenum, where the ratio of the net intensity of molybdenum to the net intensity of silicon (Mo / Si) as determined by fluorescence X-ray analysis is less than 0.035 or greater than 0.35, and exhibit excellent maintenance of the narrow charge distribution under high temperature and high humidity conditions and low temperature and low humidity conditions.

[0045] According to <3> of the present invention, silica particles are provided that, compared with silica particles containing nitrogen-containing compounds including molybdenum, the ratio of the net intensity of molybdenum to the net intensity of silicon (Mo / Si) as determined by fluorescence X-ray analysis is less than 0.035 or more than 0.35, even if the number average particle size is more than 10 nm and less than 200 nm, the charge distribution when charged is narrow, and the maintenance of the narrow charge distribution under high temperature and high humidity environment and low temperature and low humidity environment is excellent.

[0046] According to <4> of the present invention, silica particles are provided that, compared with silica particles containing a nitrogen-containing compound containing molybdenum, have a molybdenum masterbatch and a structure having a molybdenum masterbatch and a structure having a molybdenum masterbatch covering at least a portion of the surface of the molybdenum masterbatch, being composed of at least one reaction product selected from the group consisting of a 1-functional silane coupling agent, a 2-functional silane coupling agent and a 3-functional silane coupling agent, and having a nitrogen-containing compound adsorbed in at least a portion of the pores of the reaction product, having a narrow charge distribution when charged, and having excellent maintenance of the narrow charge distribution under high temperature and high humidity and low temperature and low humidity environments.

[0047] According to <5> of the present invention, silica particles can be provided that have a narrow charge distribution when charged compared to those with a hydrophobicity of less than 10% or more than 60%, and excellent maintenance of the narrow charge distribution under high temperature and high humidity and low temperature and low humidity environments.

[0048] According to <6> of the present invention, silica particles can be provided such that, when silica particles heated in a temperature range of 300°C to 600°C are found to contain nitrogen-containing compounds, the pore volume (A and B, determined by the pore distribution curve obtained from nitrogen adsorption before and after calcination at 350°C) with a pore diameter of 1 nm or more and 50 nm or less, is set as A and B respectively, and B / A is less than 1.2 or B is less than 0.2 cm. 3Compared to the case of / g, the charge distribution is narrow when charged, and the maintenance of the narrow charge distribution is excellent under both high temperature and high humidity and low temperature and low humidity environments.

[0049] According to <7> of the present invention, silica particles obtained by the cross-polarization / magic angle rotation (CP / MAS) method can be provided, which are silica particles that, when heated in a temperature range of 300°C or higher and 600°C or lower, show the presence of nitrogen-containing compounds. 29 In Si solid-state nuclear magnetic resonance (NMR) spectra, the ratio C / D of the integral value C of the signal observed in the range of chemical shift above -50 ppm and below -75 ppm to the integral value D of the signal observed in the range of chemical shift above -90 ppm and below -120 ppm is less than 0.10 or greater than 0.75. The charged distribution is narrow when charged, and the maintenance of the narrow charged distribution under high temperature and high humidity and low temperature and low humidity environments is excellent.

[0050] According to <8> of the present invention, silica particles can be provided that have a narrow charge distribution when charged, compared with the case where the amount of nitrogen-containing compound extracted using an ammonia / methanol mixed solution is less than 0.1% by mass, or the amount of nitrogen-containing compound extracted using water and the amount of nitrogen-containing compound extracted using water do not satisfy the formula: Y / X < 0.3. Furthermore, the narrow charge distribution is well maintained under high temperature and high humidity conditions and low temperature and low humidity conditions.

[0051] According to the invention described in <9>, silica particles can be provided that, compared to silica particles containing a nitrogen-containing compound containing molybdenum, have a narrow charge distribution when charged, even with an average roundness of 0.60 or higher and 0.96 or lower, and exhibit excellent maintenance of the narrow charge distribution under both high temperature and high humidity and low temperature and low humidity environments.

[0052] According to <10> of the present invention, silica particles are provided that, compared with silica particles containing a nitrogen-containing compound containing molybdenum, the ratio of the net intensity of molybdenum to the net intensity of silicon (Mo / Si) as determined by fluorescence X-ray analysis is less than 0.035 or more than 0.35, even if the particle size distribution index is 1.1 or more and 2.0 or less, the charge distribution when charged is narrow, and the maintenance of the narrow charge distribution under high temperature and high humidity conditions and low temperature and low humidity conditions is excellent. Detailed Implementation

[0053] The embodiments of the present invention will be described below. These descriptions and examples illustrate the embodiments but do not limit the scope of the embodiments.

[0054] In the numerical ranges described in this specification, the upper or lower limit of a numerical range can be replaced with the upper or lower limit of other numerical ranges described in different stages. Furthermore, in the numerical ranges described in this invention, the upper or lower limit of the numerical range can also be replaced with the values ​​shown in the embodiments.

[0055] In this specification, each component may contain multiple corresponding substances.

[0056] In this specification, when referring to the amount of each component in the composition, if there are multiple substances in the composition corresponding to each component, unless otherwise specified, it refers to the total amount of the multiple substances present in the composition.

[0057] Silica Particles

[0058] The silica particles involved in this embodiment contain a nitrogen-containing compound containing molybdenum (hereinafter also simply referred to as "nitrogen-containing compound"), and the ratio of the net intensity of molybdenum to the net intensity of silicon (Mo / Si) as determined by fluorescence X-ray analysis is 0.035 or more and 0.35 or less.

[0059] The silica particles involved in this embodiment, due to the above-described structure, possess a narrow charge distribution when charged, and exhibit excellent maintenance of this narrow charge distribution under both high-temperature and high-humidity environments and low-temperature and low-humidity environments. The reason for this is speculated to be as follows.

[0060] Silica particles have a high negative charge and can sometimes become overcharged. This results in a wider charge distribution. This tendency to become overcharged and widen is particularly pronounced in high-temperature, high-humidity and low-temperature, low-humidity environments.

[0061] For example, in powder coating, powder coatings that are charged through contact charging, corona discharge, or other methods are sprayed onto the object to be coated, allowing them to adhere electrostatically. Then, the object is heated to form a coating film.

[0062] However, if silica particles with a wide charge distribution are used as additives in powder coatings, the charge distribution of the powder coating will be biased, and the amount of powder coating adhering to the coated object will be difficult to be uniform.

[0063] On the other hand, if nitrogen-containing compounds are adsorbed onto silica particles, excessive negative charging of the silica particles can be suppressed. Nitrogen-containing compounds are positively charged, and the silica particles adsorbed with nitrogen-containing compounds counteract excessive negative charging, thus suppressing excessive negative charging.

[0064] However, if only nitrogen-containing compounds are adsorbed onto silica particles, the charge distribution will broaden towards both negative and positive charges. Moreover, as mentioned above, especially in high-temperature and high-humidity environments (e.g., 30°C 90%RH) and low-temperature and low-humidity environments (e.g., 10°C 10%RH), in addition to the increased tendency for over-charging and the broadening of the charge distribution, the maintenance of the charge distribution will also decrease.

[0065] Therefore, a nitrogen-containing compound containing molybdenum is used as the nitrogen-containing compound, and the ratio of the net intensity of molybdenum to the net intensity of silicon (Mo / Si) of silica particles, as determined by fluorescence X-ray analysis, is set to be 0.035 or higher and 0.35 or lower.

[0066] If a nitrogen-containing compound containing molybdenum is used as the nitrogen-containing compound, the activity of nitrogen is increased. Even if the nitrogen-containing compound is present inside the pores rather than on the surface of the silica particles, the positive charge of nitrogen easily suppresses over-charging, especially in high-temperature and high-humidity environments and low-temperature and low-humidity environments. Furthermore, the interaction with the nitrogen-containing cations is also enhanced, thus reducing the likelihood of cation detachment and improving charge retention. In addition, the charge of the silica particles can be adjusted between positive and negative charge as needed, depending on the proportion of molybdenum present.

[0067] Furthermore, by incorporating a nitrogen-containing compound with molybdenum into silica particles in such a manner that the ratio of the net strength of molybdenum to the net strength of silicon (Mo / Si) is within the aforementioned range, the charge distribution is narrowed, and its retention is improved under both high-temperature and high-humidity environments and low-temperature and low-humidity environments.

[0068] Based on the above speculation, the silica particles involved in this embodiment are silica particles with a narrow charge distribution when charged, and excellent maintenance of the narrow charge distribution under high temperature and high humidity and low temperature and low humidity environments.

[0069] Furthermore, for example, if the silica particles involved in this embodiment are used as an additive for powder coatings, the charge of the powder coating is not easily deviated even in high temperature and high humidity environments and low temperature and low humidity environments, and its maintenance is also high, so as to achieve uniformity of the amount of powder coating on the coated object.

[0070] The silica particles involved in this embodiment preferably satisfy any one of the following methods (A) and (B).

[0071] • Method (A): When the pore volumes with pore diameters greater than 1 nm and less than 50 nm, obtained from the pore distribution curves of nitrogen adsorption before and after calcination at 350℃, are set as A and B respectively, B / A is greater than 1.2 and less than 5, and B is 0.2 cm. 3 / g or more and 3cm 3 / g or less.

[0072] Here, “the pore volume A with a pore diameter of more than 1 nm and less than 50 nm, obtained from the pore distribution curve of nitrogen adsorption method before calcination at 350℃” will also be referred to as “pore volume A before calcination at 350℃”.

[0073] On the other hand, "the pore volume B with a pore diameter of more than 1 nm and less than 50 nm, obtained from the pore distribution curve of nitrogen adsorption method after calcination at 350℃" is also called "pore volume B after calcination at 350℃".

[0074] • Method (B): Obtained via cross-polarization / magic angle rotation (CP / MAS) method 29 The ratio C / D of the integral value C of the signal observed in the range of chemical shift above -50 ppm and below -75 ppm in Si solid-state nuclear magnetic resonance (NMR) spectra (hereinafter also referred to as "Si-CP / MAS NMR spectra") to the integral value D of the signal observed in the range of chemical shift above -90 ppm and below -120 ppm is greater than 0.10 and less than 0.75.

[0075] The silica particles involved in methods (A) or (B) have a narrow charge distribution when charged due to the above-mentioned structure. The reason for this is speculated as follows.

[0076] As described above, if nitrogen-containing compounds are adsorbed onto silica particles, excessive negative charging of the silica particles can be suppressed. Since nitrogen-containing compounds are positively charged, the adsorbed silica particles counteract excessive negative charging, thus suppressing excessive negative charging.

[0077] However, nitrogen-containing compounds are positively charged, and if they are adsorbed onto the outermost surface of silica particles, the charge distribution will broaden towards both negative and positive charges. Therefore, nitrogen-containing compounds are preferably present in, for example, fine pores, rather than coating the surface of silica particles.

[0078] Therefore, in the silica particles involved in method (A), the pore volume A before calcination at 350°C and the pore volume B after calcination at 350°C are set as characteristics that form the above relationship.

[0079] The micropore volume B after calcination at 350℃ represents the micropore volume after the nitrogen-containing compounds, which were adsorbed on and partially blocked by silica particles, have volatilized during calcination. Therefore, if B / A is 1.2 or higher and 5 or lower, and B is 0.2 cm⁻¹... 3 / g or more and 3cm 3 A concentration of less than / g indicates that a sufficient amount of nitrogen-containing compound is adsorbed into at least a portion of the pores of the silica particles. Therefore, the narrowing of the charge distribution based on the nitrogen-containing compound is improved.

[0080] On the other hand, in the silica particles involved in method (B), the ratio C / D of the integral value C of the signal observed in the Si-CP / MAS NMR spectrum in the range of chemical shift above -50ppm and below -75ppm to the integral value D of the signal observed in the range of chemical shift above -90ppm and below -120ppm is set within the above range.

[0081] An integral value of a signal satisfying the above range indicates that at least a portion of the silica particle surface has formed a low-density structure composed of reaction products of a silane coupling agent (especially a trifunctional silane coupling agent) for the adsorption of a sufficient amount of nitrogen-containing compound (e.g., SiO2). 2 / 3 (CH3 layer). The structure formed by the reaction products of silane coupling agents (especially trifunctional silane coupling agents) is low-density and has a fine porous shape that facilitates the adsorption of nitrogen-containing compounds.

[0082] Therefore, the narrowing of the charge distribution based on nitrogen-containing compounds is improved.

[0083] Based on the above speculation, the charge distribution of silica particles involved in method (A) or (B) becomes narrower when charged.

[0084] The silica particles involved in this embodiment will be described in detail below.

[0085] (Ratio of Mo / Si to Net strength)

[0086] In the silica particles involved in this embodiment, the ratio of the net intensity of molybdenum to the net intensity of silicon (Mo / Si), as determined by fluorescence X-ray analysis, is 0.035 or more and 0.35 or less. However, from the viewpoint of narrowing the charge distribution and maintaining the charge distribution, it is preferable, for example, to be 0.07 or more and 0.32 or less, and more preferably 0.10 or more and 0.30 or less.

[0087] From the viewpoint of narrowing the charge distribution and maintaining the charge distribution, the net intensity of molybdenum is preferably, for example, 5 kcps or more and 75 kcps or less, 7 kcps or more and 50 kcps or less, 8 kcps or more and 55 kcps or less, or 10 kcps or more and 40 kcps or less.

[0088] The net strength of molybdenum and silicon was measured as follows.

[0089] Approximately 0.5g of silica particles were compressed using a compression molding machine under a load of 6t for 60 seconds to create a disc with a diameter of 50mm and a thickness of 2mm. This disc was used as a sample for qualitative and quantitative elemental analysis using a scanning fluorescence X-ray analysis device (XRF-1500, manufactured by SHIMADZU CORPORATION) under the following conditions to determine the Net intensities (unit: kilo counts per second, kcps) of molybdenum and silicon.

[0090] • Tube voltage: 40kV

[0091] Tube current: 90mA

[0092] • Measurement area (analytical diameter): 10mm φ

[0093] • Measurement time: 30 minutes

[0094] • For cathode: rhodium

[0095] (pore volume)

[0096] In the silica particles involved in this embodiment, the ratio of the pore volume B after calcination at 350°C to the pore volume A before calcination at 350°C, B / A, is 1.2 or more and 5 or less. However, from the viewpoint of narrowing the charge distribution, it is preferable, for example, to be 1.4 or more and 3 or less, and more preferably 1.4 or more and 2.5 or less.

[0097] The pore volume B after calcination at 350℃ is 0.2 cm³. 3 / g or more and 3cm 3 / g or less, but from the viewpoint of narrowing the charge distribution, for example, 0.3cm is preferred. 3 / g or more and 1.8cm 3 / g or less, preferably 0.6cm 3 / g or more and 1.5cm 3 / g or less.

[0098] Specifically, the calcination at 350℃ is carried out as follows.

[0099] In a nitrogen environment, the silica particles of the test subject were heated to 350°C at a heating rate of 10°C / min and held at 350°C for 3 hours. Then, they were cooled to room temperature (25°C) at a cooling rate of 10°C / min.

[0100] The pore volume was measured as follows.

[0101] First, the silica particles to be measured are cooled to liquid nitrogen temperature (-196°C), and nitrogen gas is introduced. The adsorption amount is determined using the constant volume method or gravimetric method. The pressure of the introduced nitrogen gas is slowly increased, and adsorption isotherms are constructed by plotting the amount of nitrogen adsorbed relative to each equilibrium pressure. Based on the adsorption isotherms, a pore diameter distribution curve is calculated using the BJH method, with frequency as the vertical axis and pore diameter as the horizontal axis.

[0102] Then, based on the obtained pore diameter distribution curve, the cumulative pore volume distribution with volume on the vertical axis and pore diameter on the horizontal axis is calculated. Based on the obtained cumulative pore volume distribution, the pore volume in the range of pore diameter above 1 nm and below 50 nm is accumulated and taken as "pore volume with pore diameter above 1 nm and below 50 nm".

[0103] (CP / MAS NMR spectrum)

[0104] The ratio C / D of the integral value C of the signal observed in the Si-CP / MAS NMR spectrum in the range of chemical shift above -50 ppm and below -75 ppm to the integral value D of the signal observed in the range of chemical shift above -90 ppm and below -120 ppm is 0.10 or more and 0.75 or less. However, from the viewpoint of narrowing the charge distribution, it is preferred, for example, to be 0.12 or more and 0.45 or less, and more preferably 0.15 or more and 0.40 or less.

[0105] From the viewpoint of narrowing the charge distribution, the signal ratio (C) of the signals observed in the range of chemical shifts above -50 ppm and below -75 ppm when the integral values ​​of all signals in the Si-CP / MAS NMR spectrum are set to 100% is preferably 5% or more, and more preferably 7% or more. Furthermore, the upper limit of the signal ratio C is, for example, 60% or less.

[0106] Si-CP / MAS NMR spectra were obtained by performing measurements based on nuclear magnetic resonance spectroscopy under the following conditions.

[0107] • Spectrometer: AVANCE300 (manufactured by Bruker)

[0108] • Resonant frequency: 59.6MHz

[0109] • Measurement nucleus: 29 Si

[0110] • Measurement method: CPMAS method (using Bruker's standard parc sequence cp.av)

[0111] Waiting time: 4 seconds

[0112] • Contact time: 8 milliseconds

[0113] • Total number of times: 2048

[0114] • Measurement temperature: room temperature (actual value 25℃)

[0115] • Observation center frequency: -3975.72Hz

[0116] MAS speed: 7.0mm-6kHz

[0117] • Reference material: hexamethylcyclotrisiloxane

[0118] (The composition of silicon dioxide particles)

[0119] The silica particles involved in this embodiment contain nitrogen-containing compounds.

[0120] Specifically, the silica particles involved in this embodiment can be exemplified by silica masterbatches and structures in which at least a portion of the surface of the silica masterbatch is coated with at least one reaction product (hereinafter also referred to as "reaction product of silane coupling agent") selected from the group consisting of monofunctional silane coupling agents, difunctional silane coupling agents, and trifunctional silane coupling agents. Furthermore, at least a portion of the reaction product is adsorbed with a nitrogen-containing compound. By forming this structure, the aforementioned pore volume characteristics and the aforementioned Si-CP / MASNMR spectral characteristics can be controlled. Furthermore, the degree of hydrophobicity and the amount of OH groups, described later, can also be controlled.

[0121] Furthermore, the silica particles involved in this embodiment may have a hydrophobic treatment structure on the surface of the structure.

[0122] -Silica masterbatch-

[0123] Silica masterbatch is a silica particle whose surface at least part is formed in the pores of the reaction product of the silane coupling agent, and at least part of it is adsorbed with a nitrogen-containing compound structure.

[0124] Examples of silica masterbatches include dry silica particles and wet silica particles.

[0125] Examples of dry silica particles include combustion silica (gas phase silica) obtained by burning silane compounds and detonation silica obtained by exploding and burning metallic silicon powder.

[0126] Examples of wet silica particles include wet silica particles obtained by the neutralization reaction of sodium silicate with inorganic acids (precipitated silica synthesized and condensed under alkaline conditions, and gel silica particles synthesized and condensed under acidic conditions), colloidal silica particles (silica sol particles) obtained by making acidic silicic acid alkaline and polymerizing it, and sol-gel silica particles obtained by the hydrolysis of organosilane compounds (e.g., alkoxysilanes).

[0127] Among these, from the viewpoint of narrowing the charge distribution, silica masterbatch, for example, sol-gel silica particles are preferred.

[0128] -Reaction products of silane coupling agents-

[0129] The adsorption structure formed by the reaction products of silane coupling agents (especially those of trifunctional silane coupling agents) is low-density and has a high affinity for nitrogen-containing compounds. Therefore, nitrogen-containing compounds are easily adsorbed deep into the pores, increasing the adsorption amount (i.e., content) of these compounds. By attaching positively charged nitrogen-containing compounds to the negatively charged silica surface, an effect of counteracting excessive negative charge is achieved. Furthermore, since the nitrogen-containing compounds adsorb within the low-density structure rather than on the outermost surface of the silica particles, it prevents the positive charge from becoming too strong and broadening the charge distribution. By only counteracting excessive negative charge, the narrowing of the charge distribution is further enhanced.

[0130] The reaction products of silane coupling agents can be exemplified by, for example, OR in the following general formula (TA). 2 The reaction products substituted with OH groups, OR 2 The reaction products obtained by the condensation of compounds with OH groups as substitutes, OR 2 The reaction products are obtained by polycondensation of compounds with OH-substituted groups and the SiOH groups of silica particles. Furthermore, the reaction products of silane coupling agents include these ORs. 2 The reaction products obtained by complete or partial substitution, or by complete or partial condensation polymerization.

[0131] Silane coupling agents are nitrogen-free compounds that do not contain nitrogen (N).

[0132] Specifically, silane coupling agents represented by the following general formula (TA) can be cited as examples.

[0133] General formula (TA): R 1n -Si(OR) 2 ) 4-n

[0134] In the general formula (TA), R 1 R represents a saturated or unsaturated aliphatic hydrocarbon group with 1 or more but less than 20 carbon atoms, or an aromatic hydrocarbon group with 6 or more but less than 20 carbon atoms. 2 Represents a halogen atom or an alkoxy group. Multiple Rs 2 They can be the same group or different groups. n represents an integer greater than 1 and less than 3.

[0135] R 1 The aliphatic hydrocarbon group can be any of straight-chain, branched, and cyclic, but is preferably straight-chain or branched. The aliphatic hydrocarbon group preferably has 1 or more and 20 or less carbon atoms, more preferably 1 or more and 18 or less carbon atoms, even more preferably 1 or more and 12 or less carbon atoms, and even more preferably 1 or more and 10 or less carbon atoms. The aliphatic hydrocarbon group can be any of saturated and unsaturated, but is preferably saturated aliphatic hydrocarbon groups, more preferably alkyl groups.

[0136] Examples of saturated aliphatic hydrocarbon groups include straight-chain alkyl groups (methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, hexadecyl, eicosyl, etc.), branched-chain alkyl groups (isopropyl, isobutyl, isopentyl, neopentyl, 2-ethylhexyl, tert-butyl, tert-pentyl, isopentadecanyl, etc.), and cyclic alkyl groups (cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, tricyclodecyl, norbornyl, adamantyl, etc.).

[0137] Examples of unsaturated aliphatic hydrocarbon groups include alkenyl (ethenyl, 1-propenyl, 2-propenyl, 2-butenyl, 1-butenyl, 1-hexenyl, 2-dodecenyl, pentenyl, etc.) and alkynyl (ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 3-hexynyl, 2-dodecynyl, etc.).

[0138] R 1 The aromatic hydrocarbon group represented is preferably composed of 6 or more and 20 or less carbon atoms, more preferably 6 or more and 18 or less carbon atoms, even more preferably 6 or more and 12 or less carbon atoms, and even more preferably 6 or more and 10 or less carbon atoms.

[0139] Examples of aromatic hydrocarbon groups include phenylene, biphenylene, terphenylene, naphthyl, and anthracene.

[0140] As R 2Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Chlorine, bromine, or iodine atoms are preferred as halogen atoms.

[0141] As R 2 The alkoxy group referred to can be alkoxy groups with 1 or more and 10 or fewer carbon atoms (for example, preferably 1 or more and 8 or fewer, more preferably 1 or more and 4 or fewer). Examples of alkoxy groups include methoxy, ethoxy, isopropoxy, tert-butoxy, n-butoxy, n-hexoxy, 2-ethylhexoxy, and 3,5,5-trimethylhexoxy. Alkoxy groups also include substituted alkoxy groups. Examples of substituents that can be substituted into an alkoxy group include halogen atoms, hydroxyl groups, amino groups, alkoxy groups, amide groups, and carbonyl groups.

[0142] n is preferably an integer of 1 or 2, more preferably 1.

[0143] The silane coupling agent represented by the general formula (TA), such as R, is preferred. 1 It is a saturated aliphatic hydrocarbon group with 1 or more carbon atoms and less than 20 carbon atoms, R 2 It is a trifunctional silane coupling agent with a halogen atom or alkoxy group and an n of 1.

[0144] Examples of trifunctional silane coupling agents include the following:

[0145] Vinyltrimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, hexyltrimethoxysilane, n-octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, vinyltriethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, butyltriethoxysilane, hexyltriethoxysilane, decyltriethoxysilane, dodecyltriethoxysilane, phenyltrimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, phenyltriethoxysilane, benzyltriethoxysilane, decyltrichlorosilane, phenyltrichlorosilane (the above are R...) 1 (Compounds consisting of unsubstituted aliphatic hydrocarbon groups or unsubstituted aromatic hydrocarbon groups).

[0146] 3-Glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane (the above are R...) 1 Compounds containing substituted aliphatic or aromatic hydrocarbon groups, etc.

[0147] 3-functional silane coupling agents can be used alone or in combination with two or more.

[0148] Among these, from the viewpoint of narrowing the charge distribution, alkyltrialkoxysilanes are preferred as trifunctional silane coupling agents, and more preferably R in the general formula (TA) 1 R represents an alkyl group having 1 or more and 20 or fewer carbon atoms (e.g., preferably 1 or more and 15 or fewer carbon atoms). 2 Alkyltrialkoxysilanes refer to alkyl groups with 1 or more but less than 2 carbon atoms.

[0149] From the viewpoint of narrowing the charge distribution and maintaining the charge distribution, the amount of the structure composed of the reaction product of the silane coupling agent attached relative to the silica particles is preferably 5.5% by mass or more and 30% by mass or less, more preferably 7% by mass or more and 22% by mass or less.

[0150] -Nitrogen-containing compounds-

[0151] Nitrogen-containing compounds are nitrogen-containing compounds that contain molybdenum, excluding ammonia and compounds that are in a gaseous state at temperatures above -200°C and below 25°C.

[0152] Specifically, from the viewpoint of narrowing the charge distribution and maintaining the charge distribution, nitrogen-containing compounds are preferably selected from at least one of the group consisting of quaternary ammonium salts containing molybdenum (especially quaternary ammonium salts containing molybdenum) and mixtures of quaternary ammonium salts and metal oxides containing molybdenum.

[0153] In particular, the molybdenum-containing salts of quaternary ammonium exhibit improved charge distribution maintenance due to the strong bonding between the molybdenum-containing anion (as anion) and the quaternary ammonium cation (as a cation).

[0154] Nitrogen-containing compounds are preferably adsorbed in at least a portion of the pores of the reaction product of the silane coupling agent.

[0155] Furthermore, a nitrogen-containing compound containing molybdenum can be used alone or in combination with two or more. Moreover, a nitrogen-containing compound containing molybdenum can be used in combination with a nitrogen-containing compound that does not contain Mo (selected from at least one of the group consisting of quaternary ammonium salts, primary amine compounds, secondary amine compounds, tertiary amine compounds, amide compounds, imine compounds, and nitrile compounds, preferably a quaternary ammonium salt).

[0156] Quaternary ammonium salts (quaternary ammonium salts that do not contain molybdenum) are not particularly restricted and can be used with any known quaternary ammonium salts.

[0157] From the viewpoint of narrowing the charge distribution, quaternary ammonium salts (quaternary ammonium salts that do not contain molybdenum) preferably include compounds represented by the general formula (AM). Furthermore, compounds represented by the general formula (AM) can be used alone or in combination of two or more.

[0158] [Chemical Formula 1]

[0159]

[0160] In the general formula (AM), R 1 R 2 R 3 and R 4 Each independently represents a hydrogen atom or an alkyl, aralkyl, or aryl group that may have substituents, X - This represents an anion. Wherein, R... 1 R 2 R 3 and R 4 At least one of them indicates that it may be an alkyl, aralkyl, or aryl group having a substituent. Furthermore, R 1 R 2 R 3 and R 4 Two or more of them can connect to form an aliphatic ring, an aromatic ring, or a heterocyclic ring.

[0161] As R 1 ~R 4 Examples of alkyl groups include straight-chain alkyl groups with 1 or more and 20 or fewer carbon atoms, and branched alkyl groups with 3 or more and 20 or fewer carbon atoms.

[0162] Examples of linear alkyl groups with 1 or more but less than 20 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecanyl, and n-hexadecyl.

[0163] Examples of branched alkyl groups with 3 or more but less than 20 carbon atoms include isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, neopentyl, tert-pentyl, isohexyl, sec-hexyl, tert-hexyl, isoheptyl, sec-heptyl, tert-heptyl, isooctyl, sec-octyl, tert-octyl, isononyl, sec-nonyl, tert-nonyl, isodel, sec-decyl, tert-decyl, etc.

[0164] In the above, as R 1 ~R 4 The alkyl group represented is preferably an alkyl group with 1 or more carbon atoms and less than 15, such as methyl, ethyl, butyl, tetradecyl, etc.

[0165] As R 1 ~R 4 The aralkyl group to be represented can be an aralkyl group with 7 or more but less than 30 carbon atoms.

[0166] Examples of aryl alkyl groups with 7 or more but less than 30 carbon atoms include benzyl, phenylethyl, phenylpropyl, 4-phenylbutyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, phenylnonyl, naphthylmethyl, naphthylethyl, anthraceneylmethyl, and phenyl-cyclopentylmethyl.

[0167] In the above, as R 1 ~R 4 The aralkyl group represented is preferably an aralkyl group with 7 or more carbon atoms and 15 or fewer, such as benzyl, phenylethyl, phenylpropyl, or 4-phenylbutyl.

[0168] As R 1 ~R 4 Examples of aryl groups that can be represented include those with 6 or more but less than 20 carbon atoms.

[0169] Examples of aryl groups with 6 to 20 carbon atoms include phenyl, pyridyl, and naphthyl.

[0170] In the above, as R 1 ~R 4 The aryl group represented is preferably an aryl group with 6 or more but less than 10 carbon atoms, such as phenyl.

[0171] As X - The anions represented can be organic anions or inorganic anions.

[0172] Examples of organic anions include polyfluoroalkyl sulfonate ions, polyfluoroalkyl carboxylate ions, tetraphenylborate ions, aromatic carboxylate ions, and aromatic sulfonate ions (such as 1-naphthol-4-sulfonate ions).

[0173] As inorganic anions, OH- can be cited as an example. - F - Fe(CN)6 3- Cl - ,Br - NO2 - NO3 - CO3 2- PO4 3- SO4 2- wait.

[0174] In the general formula (AM), R 1 R 2 R 3 and R 4 Two or more elements can be connected to form a loop. As R... 1 R 2 R 3 and R 4Examples of rings formed by the interconnection of two or more carbon atoms include alicyclic rings with 2 or more but less than 20 carbon atoms, and heterocyclic amines with 2 or more but less than 20 carbon atoms.

[0175] In compounds represented by the general formula (AM), R 1 R 2 R 3 and R 4 Each can have substituents independently. Examples of substituents include nitrile, carbonyl, ether, amide, siloxane, silyl, and silanealkoxy groups.

[0176] R 1 R 2 R 3 and R 4 For example, it is preferable that each of the following is independently represented: alkyl group with 1 or more carbon atoms and 16 or less, aralkyl group with 7 or more carbon atoms and 10 or less, or aryl group with 6 or more carbon atoms and 20 or less.

[0177] Among these, from the viewpoint of narrowing the charge distribution, compounds represented by the general formula (AM) are preferably those with a total number of carbon atoms of 18 or more and 35 or less, more preferably 20 or more and 32 or less.

[0178] The following shows X in compounds represented by the general formula (AM). - Examples of structures other than those described herein are provided, but this embodiment is not limited to them.

[0179] [Chemical Formula 2]

[0180]

[0181] From the viewpoint of narrowing the charge distribution, quaternary ammonium salts containing molybdenum are preferably represented by the general formula (AM) and X - molybdate ion (MoO4) is represented as an anion. 2- Mo2O7 2- Mo3O 10 2- Mo4O 13 2- Mo7O 24 2- Mo8O 26 4- Compounds containing molybdenum (e.g., molybdenum). Specifically, examples of quaternary ammonium salts containing molybdenum include [N...]. + (CH)3(C 14 C 29 )2]4Mo8O 28 4- 、[N + (C4H9)2(C6H6)2]2Mo2O72- 、[N + (CH3)2(CH2C6H6)(CH2) 17 CH3]2MoO4 2- 、[N + (CH3)2(CH2C6H6)(CH2) 15 CH3]2MoO4 2- wait.

[0182] Examples of metal oxides containing molybdenum include molybdenum oxides (molybdenum trioxide, molybdenum dioxide, Mo9O). 26 Alkali metal molybdates (lithium molybdate, sodium molybdate, potassium molybdate, etc.), alkaline earth metal molybdates (magnesium molybdate, calcium molybdate, etc.), and other complex oxides (Bi₂O₃·2MoO₃, γ-Ce₂Mo₃O₃). 13 wait).

[0183] -Detection and content of nitrogen-containing compounds-

[0184] When the silica particles involved in this embodiment are heated in a temperature range of 300°C or higher and 600°C or lower, nitrogen-containing compounds are detected. Specifically, for example, as follows.

[0185] In the detection of nitrogen-containing compounds, a fall-type pyrolysis gas chromatography-mass spectrometry (GC-MS) system using a furnace with He as the carrier gas is employed, for example. Nitrogen-containing compounds can be detected at thermal decomposition temperatures above 300°C and below 600°C under an inert gas atmosphere. Specifically, by introducing 0.1 mg to 10 mg of silica particles into the GC-MS system, the presence or absence of nitrogen-containing compounds can be confirmed based on the MS spectrum of the detected peaks. Examples of components generated from the thermal decomposition of silica particles containing nitrogen-containing compounds include amines or aromatic nitrogen compounds of order 1 to 3 represented by the following general formula (N).

[0186] In the following general formula (N), R N1 ~R N3 Each independently represents a hydrogen atom or an alkyl, aralkyl, or aryl group that may have substituents, R N1 ~R N3 The meaning of R in the general formula (AM) 1 R 2 and R 3 same.

[0187] For example, when the nitrogen-containing compound is a quaternary ammonium salt, a portion of the side chain is released through thermal decomposition at 600°C, and it is detected as a tertiary amine.

[0188] [Chemical Formula 3]

[0189]

[0190] From the viewpoint of narrowing the charge distribution, the content of nitrogen-containing compounds relative to silicon dioxide particles, expressed in N atoms, is preferably 0.008% by mass or more and 0.45% by mass or less, more preferably 0.015% by mass or more and 0.20% by mass or less, and even more preferably 0.018% by mass or more and 0.10% by mass or less.

[0191] The content of nitrogen-containing compounds, calculated using N atoms, was determined as follows.

[0192] The presence of nitrogen was determined using an oxygen-nitrogen analyzer (e.g., EMGA-920 manufactured by HORIBA, Ltd.) with a cumulative time of 45 seconds, as a ratio of N to Si. Additionally, as a sample pretreatment, impurities such as ammonia were removed from the silica particles by drying them in a vacuum dryer at 100°C for 24 hours.

[0193] -Extraction rate of nitrogen-containing compounds-

[0194] The extraction amount X of nitrogen-containing compounds extracted using an ammonia / methanol mixed solution is, for example, 0.1% by mass or more, and the extraction amount X of nitrogen-containing compounds and the extraction amount Y of nitrogen-containing compounds extracted using water preferably satisfy the formula: Y / X < 0.3.

[0195] In other words, nitrogen-containing compounds are difficult to dissolve in water, meaning they are unlikely to absorb moisture from the air.

[0196] In silica particles containing nitrogen-containing compounds, if the nitrogen-containing compounds adsorb moisture, the charge distribution becomes wider, and the nitrogen-containing compounds easily detach from the silica particles.

[0197] However, even if moisture is present in the air (even under high humidity), silica particles containing nitrogen-containing compounds that are difficult to adsorb moisture from the air do not easily broaden their charge distribution, and the nitrogen-containing compounds are not easily detached, thus maintaining a narrow charge distribution.

[0198] The extraction amount X of nitrogen-containing compounds is preferably 50% by mass, for example. However, due to surface tension, the solution has difficulty penetrating into the pores, and some of the nitrogen-containing compounds will not dissolve and remain. Therefore, the upper limit of the extraction amount X of nitrogen-containing compounds is, for example, 95% by mass or less.

[0199] The ratio of the amount of nitrogen-containing compound extracted, X, to the amount of nitrogen-containing compound extracted, "Y / X", is preferably less than 0.3, for example. However, the lower limit of "Y / X" is ideally 0, but since there is a measurement error range of about ±1% for X and Y, it is, for example, 0.01 or more.

[0200] Here, the extraction amounts X and Y of nitrogen-containing compounds were determined as follows.

[0201] First, the silica particles to be measured are analyzed using a thermogravimetric-mass spectrometry (TG-MS) instrument (e.g., a gas chromatograph-mass spectrometer manufactured by NETZSCH Japan K.K.) at a constant temperature of 400°C. The cumulative mass fraction of compounds in which hydrocarbons with at least one carbon atom are covalently bonded to nitrogen elements relative to the silica particles is measured and set as W1.

[0202] On the other hand, 1 part by mass of the silica particles of the target substance was added to 30 parts by mass of an ammonia / methanol solution (manufactured by Sigma-Aldrich, ammonia / methanol mass ratio = 1 / 5.2) at a liquid temperature of 25°C. After ultrasonic treatment for 30 minutes, the silica powder and extract were separated. The separated silica particles were dried in a vacuum dryer at 100°C for 24 hours, and the mass fraction of compounds with at least one carbon atom covalently bonded to a nitrogen atom relative to the silica particles was determined using a thermogravimetric-mass spectrometry (TGA) system at a constant temperature of 400°C. This fraction was designated as W2.

[0203] Then, the amount of nitrogen-containing compound X extracted is calculated using the following formula.

[0204] Equation: X = W1 - W2

[0205] Furthermore, 1 part by mass of silica particles of the target substance was added to 30 parts by mass of water at a liquid temperature of 25°C, and after ultrasonic treatment for 30 minutes, the silica particles and extract were separated. The separated silica particles were dried in a vacuum dryer at 100°C for 24 hours, and the mass fraction of compounds with at least 1 carbon atom covalently bonded to nitrogen atoms relative to silica particles was determined using a thermogravimetric-mass spectrometry (TGA) system at a constant temperature of 400°C. This fraction was designated as W3.

[0206] Then, the extraction amount Y of nitrogen-containing compounds is calculated using the following formula.

[0207] Equation: Y = W1 - W3

[0208] (Hydrophobic treatment structure)

[0209] The hydrophobicated structure is a structure that has reacted with a hydrophobic treatment agent.

[0210] Organosilicon compounds can be used as hydrophobic treatment agents, for example.

[0211] Examples of organosilicon compounds include:

[0212] Alkoxysilane compounds or halosilane compounds having lower alkyl groups, such as methyltrimethoxysilane, dimethyldimethoxysilane, trimethylchlorosilane, and trimethylmethoxysilane; vinyltrimethoxysilane compounds having vinyl groups, such as vinyltriethoxysilane;

[0213] Alkoxysilane compounds with epoxy groups, such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane.

[0214] Alkoxysilane compounds containing a styrene group, such as p-styrenetrimethoxysilane and p-styrenetriethoxysilane;

[0215] N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane and other alkoxysilane compounds containing aminoalkyl groups;

[0216] Alkoxysilane compounds containing isocyanate alkyl groups, such as 3-isocyanate propyltrimethoxysilane and 3-isocyanate propyltriethoxysilane;

[0217] Hexamethyldisilazane, tetramethyldisilazane, and other silazane compounds.

[0218] (Properties of silica particles)

[0219] -Hydrophobicity-

[0220] From the viewpoint of narrowing the charge distribution, the degree of hydrophobicity of the silica particles involved in this embodiment is preferably 10% or more and 60% or less, more preferably 20% or more and 55% or less, and even more preferably 28% or more and 53% or less.

[0221] If the hydrophobicity of silica particles is below 10%, the coating amount of the structure is low due to the reaction of the silane coupling agent, and the content of nitrogen-containing compounds is reduced. Therefore, the charge distribution tends to broaden.

[0222] On the other hand, if the hydrophobicity of silica particles exceeds 60%, the density of the structure increases due to the reaction of the silane coupling agent, resulting in fewer pores and a decrease in the content of nitrogen-containing compounds. Therefore, the charge distribution tends to broaden.

[0223] The degree of hydrophobicity of silica particles was determined as follows.

[0224] Add 0.2% by mass of silica particles (as the sample) to 50 ml of ion-exchanged water. While stirring with a magnetic stirrer, add methanol dropwise from a burette. Calculate the mass fraction of methanol in the methanol-water mixture at the endpoint of total sample precipitation as the degree of hydrophobicity.

[0225] -Number average particle size and number-particle size distribution index-

[0226] The average particle size of the silica particles involved in this embodiment is preferably 10 nm or more and 200 nm or less, more preferably 10 nm or more and 80 nm or less, and even more preferably 10 nm or more and 60 nm or less.

[0227] If the average particle size of the silica particles is within the above range, the specific surface area is large, and over-charging is likely to occur. However, even if the average particle size of the silica particles involved in this embodiment is within the above range, the charge distribution can be narrowed.

[0228] The number and particle size distribution index of silica particles involved in this embodiment is preferably 1.1 or more and 2.0 or less, and more preferably 1.15 or more and 1.6 or less.

[0229] If the number and particle size distribution of silica particles involved in this embodiment are within the above range, then there will be fewer coarse powders with a tendency to increase charge and fewer micro powders with a tendency to decrease charge, making it easier to achieve a narrower charge distribution.

[0230] Here, the number average particle size and number particle size distribution of silica particles are determined as follows.

[0231] Silica particles were observed using a scanning electron microscope (SEM) at 40,000x magnification. The images of the observed silica particles were analyzed using WinRoof image processing and analysis software (manufactured by MITANI CORPORATION) to determine the equivalent circle diameter of at least 200 particles. Then, regarding the number of each particle, the cumulative distribution was plotted from the small diameter side to determine the number-average particle size, which represents the 50% cumulative particle size from the small diameter side.

[0232] Furthermore, the square root of the value obtained by dividing the cumulative particle size D84 (84% from the smallest diameter side) by the cumulative particle size D16 (16% from the smallest diameter side) is defined as the "Number Size Distribution Index" (GSD). That is, Number Size Distribution Index (GSD) = (D84 / D16) 0.5 .

[0233] -Roundness-

[0234] The average roundness of the silica particles involved in this embodiment is preferably 0.60 or more and 0.96 or less, more preferably 0.70 or more and 0.92 or less, and even more preferably 0.75 or more and 0.90 or less.

[0235] If the average sphericity of the silica particles is within the above range, the specific surface area is large, and over-charging is likely to occur. However, even if the average sphericity of the silica particles involved in this embodiment is within the above range, the charge distribution can be narrowed.

[0236] Here, the sphericity of the silica particles is measured as follows.

[0237] Silica particles were observed at 40,000x magnification using a scanning electron microscope (SEM). The images of the observed silica particles were analyzed using WinRoof image processing and analysis software (manufactured by MITANI CORPORATION). The roundness of at least 200 particles was determined, and the arithmetic mean was calculated to determine the average roundness.

[0238] In addition, roundness can be calculated using the following formula.

[0239] Roundness = Equivalent circle diameter / circumference = [2 × (Aπ)] 1 / 2 ] / PM

[0240] In the above formula, A represents the projected area, and PM represents the perimeter.

[0241] -Volume resistivity-

[0242] The volume resistivity (i.e., the volume resistivity before calcination at 350°C) of the silica particles involved in this embodiment is preferably, for example, 1.0 × 10⁻⁶. 7 Ωcm or more and 1.0×10 11.5 Below Ωcm, more preferably 1.0×10 8 Ωcm or more and 1.0×10 11 Below Ωcm.

[0243] If the volume resistivity of the silicon dioxide particles involved in this embodiment is within the above range, the content of nitrogen-containing compounds is high, making it less prone to excessive charging and easier to achieve a narrowing of the charge distribution.

[0244] In the silica particles involved in this embodiment, when the volume resistivity of the silica particles before and after calcination at 350°C is set as Ra and Rb respectively, Ra / Rb is preferably 0.01 or more and 0.8 or less, and more preferably 0.015 or more and 0.6 or less.

[0245] If Ra / Rb is within the above range, the content of nitrogen-containing compounds is high, making it less likely for excessive charging to occur and easier to achieve a narrowing of the charge distribution.

[0246] Calcination at 350℃ shall be carried out as described above.

[0247] On the other hand, the volume resistivity was measured as follows. Furthermore, the measurement environment was set at a temperature of 20°C and a humidity of 50%RH.

[0248] With a 20cm configuration 2 The surface of the circular clamp of the electrode plate is covered with silica particles, the object of measurement, to form a silica particle layer with a thickness of approximately 1 mm to 3 mm. A 20 cm layer of the same material is then placed on top of this layer. 2 Electrode plates were used to add a layer of silica particles. To eliminate voids between the silica particles, a pressure of 0.4 MPa was applied to the electrode plates placed on the silica particle layer, and the thickness (cm) of the silica particle layer was measured. Two electrodes above and below the silica particle layer were connected to an impedance analyzer (manufactured by Solartron Analytical). The impedance was measured at 10... -3 Hz and above and 10 6 Measurements were taken at frequencies below Hz, resulting in the Nyquist plot. Assuming the existence of three resistive components—volume resistance, particle interface resistance, and electrode contact resistance—and plotting them in an equivalent circuit, the volume resistance R was calculated.

[0249] The formula for calculating the volume resistivity (Ω·cm) of silica particles is shown below.

[0250] Formula: ρ = R / L

[0251] In the formula, ρ is the volume resistivity of silicon dioxide particles (Ω·cm), R is the bulk resistance (Ω), and L is the thickness of the silicon dioxide particle layer (cm).

[0252] (OH base amount)

[0253] In the silica particles involved in this embodiment, the amount of OH radicals, as measured by the Sears method, is preferably 0.2 OH radicals / nm. 2 Above and 5.5 per nm 2 From the viewpoint of narrowing the charge distribution, 0.2 charges / nm is preferred. 2 More than 4 per nm 2Below, 0.2 per nm is further preferred. 2 More than 3 per nm 2 the following.

[0254] The amount of OH groups determined using the Sears method can be adjusted within the above range by fully forming the structure composed of the reaction products of the silane coupling agent into the silica masterbatch.

[0255] By reducing the amount of OH groups that hinder the adsorption of nitrogen-containing compounds to the aforementioned range, the nitrogen-containing compounds can easily penetrate deep into the pores of the silica particles (e.g., the pores of the adsorption layer described later). Then, hydrophobic interactions act on the nitrogen-containing compounds, thereby strengthening their adhesion to the silica particles. Therefore, the amount of nitrogen-containing compounds adsorbed increases. Furthermore, the nitrogen-containing compounds become less prone to detachment. Thus, the narrowing of the charge distribution based on the nitrogen-containing compounds is improved, and the maintenance of this narrow charge distribution is also enhanced.

[0256] Furthermore, by reducing the amount of OH radicals to the above range, the environmental dependence of the charge properties is reduced, and it is easy to achieve a narrowing of the charge distribution based on nitrogen-containing compounds in any environment (especially in low-temperature and low-humidity environments where excessive negative charging is likely to occur).

[0257] The OH radical content was determined using the Sears method. Details are as follows.

[0258] 1.5 g of silica particles were added to a mixture of 50 g of pure water and 50 g of ethanol, and the mixture was stirred for 2 minutes using an ultrasonic homogenizer to prepare a dispersion. While stirring at 25°C, 1.0 g of 0.1 mol / L hydrochloric acid aqueous solution was added dropwise to obtain the test solution. The obtained test solution was placed in an automatic titration apparatus, and potentiometric titration with 0.01 mol / L sodium hydroxide aqueous solution was performed to prepare the differential curve of the titration. The titration amount at the inflection point where the differential value of the titration curve becomes the largest at 1.8 or higher was defined as E.

[0259] The surface silanol group density ρ (numbers / nm) of silica particles was calculated using the following formula. 2 ).

[0260] Formula: ρ = ((0.01×E-0.1)×NA / 1000) / (M×S) BET ×10 18 )

[0261] The symbols in the formula are detailed below.

[0262] E: The titration amount of 0.01 mol / L sodium hydroxide aqueous solution becomes the largest at the inflection point where the differential value of the titration curve becomes 1.8 or higher.

[0263] NA: Avogadro's constant

[0264] M: Quantity of silica particles (1.5g)

[0265] S BET Specific surface area of ​​silica particles (m²) 2 / g)

[0266] The specific surface area of ​​silica particles was determined using the BET-type nitrogen adsorption three-point method. The equilibrium relative pressure was set to 0.3.

[0267] Methods for manufacturing silica particles

[0268] An example of the method for manufacturing silica particles according to this embodiment includes the following steps:

[0269] The first step involves forming a structure composed of the reaction product of a silane coupling agent on at least a portion of the surface of the silica masterbatch; and

[0270] The second step involves adsorbing a nitrogen-containing compound into at least a portion of the pores of the reaction product of the silane coupling agent.

[0271] The method for manufacturing silica particles according to this embodiment may include a third step after or during the second step, in which a silica masterbatch having the following structure is hydrophobically treated, wherein the structure covers at least a portion of the surface of the silica masterbatch, is composed of the reaction product of a silane coupling agent, and at least a portion of the pores of the reaction product of the silane coupling agent is adsorbed with a nitrogen-containing compound.

[0272] The following is a detailed description of the steps involved in the method for manufacturing silica particles according to this embodiment.

[0273] [Preparation Process]

[0274] First, the process for preparing silica masterbatch will be explained.

[0275] As a preparatory step, examples include:

[0276] (i) The process of mixing a solvent containing alcohol and silica masterbatch to prepare a silica masterbatch suspension;

[0277] (ii) The process of granulating silica masterbatch by sol-gel method to obtain silica masterbatch suspension, etc.

[0278] Examples of silica masterbatches used in (i) include sol-gel silica particles (silica particles obtained by the sol-gel method), aqueous colloidal silica particles, alcoholic silica particles, fumed silica particles obtained by the gas phase method, and molten silica particles.

[0279] The solvent containing the alcohol used in (i) can be a solvent containing only the alcohol or a mixture of the alcohol and other solvents. Examples of alcohols include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, and butanol. Examples of other solvents include water; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; cellosols such as methyl cellosol, ethyl cellosol, butyl cellosol, and acetic acid cellosol; and ethers such as dioxane and tetrahydrofuran. In the case of a mixed solvent, the proportion of alcohol is preferably 80% by mass or more, and more preferably 85% by mass or more.

[0280] Step (1-a) is preferably a step of granulating silica masterbatch by sol-gel method to obtain silica masterbatch suspension.

[0281] More specifically, step (1-a) is preferably a sol-gel method including the following steps: an alkaline catalyst solution preparation step, preparing an alkaline catalyst solution containing an alkaline catalyst in a solvent containing an alcohol; and a silica masterbatch generation step, supplying a tetraalkoxysilane and an alkaline catalyst to the alkaline catalyst solution to generate silica masterbatch.

[0282] The alkaline catalyst solution preparation process is preferably, for example, the process of preparing a solvent containing an alcohol and mixing the solvent with an alkaline catalyst to obtain an alkaline catalyst solution.

[0283] The solvent containing the alcohol can be a solvent containing only the alcohol or a mixture of the alcohol and other solvents. Examples of alcohols include lower alcohols such as methanol, ethanol, n-propanol, isopropanol, and butanol. Examples of other solvents include water; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; cellosols such as methyl cellosol, ethyl cellosol, butyl cellosol, and acetic acid cellosol; and ethers such as dioxane and tetrahydrofuran. In the case of a mixed solvent, the proportion of alcohol is preferably 80% by mass or more, and more preferably 85% by mass or more.

[0284] Alkaline catalysts are catalysts used to promote the reactions (hydrolysis and condensation reactions) of tetraalkoxysilanes. Examples of alkaline catalysts include ammonia, urea, and monoamines, with ammonia being particularly preferred.

[0285] The concentration of the alkaline catalyst in the alkaline catalyst solution is preferably 0.5 mol / L or more and 1.5 mol / L or less, more preferably 0.6 mol / L or more and 1.2 mol / L or less, and even more preferably 0.65 mol / L or more and 1.1 mol / L or less.

[0286] The process of generating silica masterbatch involves supplying tetraalkoxysilane and an alkaline catalyst to an alkaline catalyst solution to allow the tetraalkoxysilane to react (hydrolysis and condensation) in the alkaline catalyst solution to generate silica masterbatch.

[0287] In the silica masterbatch production process, after the initial supply of tetraalkoxysilane, nuclear particles are generated through the reaction of tetraalkoxysilane (nuclear particle generation stage), and after the growth of these nuclear particles (nuclear particle growth stage), silica masterbatch is generated.

[0288] Examples of tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. From the viewpoint of controllability of the reaction rate or uniformity of the shape of the generated silica masterbatch, tetramethoxysilane or tetraethoxysilane is preferred.

[0289] Examples of alkaline catalysts supplied to the alkaline catalyst solution include ammonia, urea, monoamines, and quaternary ammonium salts, with ammonia being particularly preferred. The alkaline catalyst supplied together with the tetraalkoxysilane can be of the same type as the alkaline catalyst pre-contained in the alkaline catalyst solution, or it can be of a different type, but the same type is preferred.

[0290] The supply of tetraalkoxysilane and alkaline catalyst to the alkaline catalyst solution can be either continuous or intermittent.

[0291] In the silica masterbatch production process, the temperature of the alkaline catalyst solution (the temperature at which it is supplied) is preferably 5°C or higher and 50°C or lower, more preferably 15°C or higher and 45°C or lower.

[0292] [First Process]

[0293] In the first step, a structure composed of the reaction products of the silane coupling agent is formed.

[0294] Specifically, in the first step, for example, a silane coupling agent is added to the silica masterbatch suspension, causing the silane coupling agent to react with the surface of the silica masterbatch to form a structure composed of the reaction products of the silane coupling agent. The silane coupling agent forms the structure composed of the reaction products of the silane coupling agent through the reaction of its functional groups with each other and with the OH groups on the surface of the silica particles.

[0295] The reaction of the silane coupling agent is carried out by adding the silane coupling agent to the silica masterbatch suspension and then heating the suspension while stirring it.

[0296] Specifically, for example, the suspension is heated to above 40°C and below 70°C, a silane coupling agent is added, and then the mixture is stirred. The stirring time is preferably above 10 minutes and below 24 hours, more preferably above 60 minutes and below 420 minutes, and even more preferably above 80 minutes and below 300 minutes.

[0297] [Second Process]

[0298] In the second step, a nitrogen-containing compound is adsorbed into at least a portion of the pores of the reaction product of the silane coupling agent.

[0299] Specifically, in the second step, firstly, a nitrogen-containing compound is added to, for example, a silica masterbatch suspension, and stirring is performed, for example, at a temperature range of above 20°C and below 50°C. As a result, the nitrogen-containing compound is adsorbed onto at least a portion of the pores of the reaction product of the silane coupling agent.

[0300] In the second step, for example, an alcoholic solution containing a nitrogen-containing compound can be added to the silica particle suspension.

[0301] The alcohol may be of the same type as the alcohol contained in the silica masterbatch suspension, or it may be of a different type, but more preferably the same type.

[0302] In an alcoholic liquid containing a nitrogen-containing compound, the concentration of the nitrogen-containing compound is preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 6% by mass or less.

[0303] [Third Process]

[0304] In the third step, after or during the second step, the silica masterbatch having a structure in which at least a portion of the pores of the reaction product of the silane coupling agent is adsorbed with nitrogen-containing compounds is subjected to a hydrophobic treatment.

[0305] Specifically, in the third step, for example, after adding a nitrogen-containing compound to a silica masterbatch suspension in which the structure is formed, a hydrophobic treatment agent is added.

[0306] The hydrophobic treatment agent forms a hydrophobic layer by reacting the functional groups of the hydrophobic treatment agent with each other and with the OH groups of the silica masterbatch.

[0307] The reaction of the hydrophobic treatment agent is carried out by adding the silane coupling agent to the silica masterbatch suspension and then heating the suspension while stirring it.

[0308] Specifically, for example, the suspension is heated to above 40°C and below 70°C, a hydrophobic treatment agent is added, and then the mixture is stirred. The stirring time is preferably 10 minutes or more and 24 hours or less, more preferably 20 minutes or more and 120 minutes or less, and even more preferably 20 minutes or more and 90 minutes or less.

[0309] [Drying Process]

[0310] In the method for manufacturing silica particles according to this embodiment, it is preferable to perform a drying step to remove the solvent from the suspension after performing the second or third step. Alternatively, the drying step may also be performed in the second or third step.

[0311] Drying methods include, for example, thermal drying, spray drying, and supercritical drying.

[0312] Spray drying can be performed using conventionally known methods employing commercially available spray dryers (such as rotary disc dryers or nozzle dryers). For example, it is performed by spraying a liquid onto a hot air stream at a rate of 0.2 liters / hour or more and 1 liter / hour or less. In this case, the temperature of the hot air is preferably, for example, within the range of an inlet temperature of 70°C or more and 400°C or less, and an outlet temperature of 40°C or more and 120°C or less. If the inlet temperature is below 70°C, the drying of the solid components contained in the dispersion becomes insufficient. Furthermore, if the temperature exceeds 400°C, the particle shape will deform during spray drying. And, if the outlet temperature is below 40°C, the solid components are poorly dried and will adhere to the inside of the apparatus. A more preferred inlet temperature is, for example, within the range of 100°C or more and 300°C or less.

[0313] The concentration of silica particles in the silica particle suspension during spray drying is preferably in the range of 10% by mass or more and 30% by mass or less, based on the solid content.

[0314] In supercritical drying, the surface tension between particles is largely neutralized by utilizing supercritical fluids to remove the solvent, and the primary particles contained in the suspension are dried in a state of suppressed aggregation. Therefore, silica particles with high particle size uniformity are readily obtained.

[0315] Examples of substances that can be used as supercritical fluids include carbon dioxide, water, methanol, ethanol, and acetone. From the viewpoint of processing efficiency and suppressing the generation of coarse particles, the solvent removal process is preferably a process that uses supercritical carbon dioxide, for example.

[0316] Specifically, supercritical drying is carried out, for example, through the following operations.

[0317] A suspension is contained in a closed reactor. Liquefied carbon dioxide is then introduced, the reactor is heated, and a high-pressure pump is used to pressurize the reactor, causing the carbon dioxide to become supercritical. Liquefied carbon dioxide is then introduced into the closed reactor, while supercritical carbon dioxide flows out, thus allowing supercritical carbon dioxide to flow into the suspension within the closed reactor. During this flow, the solvent dissolves in the supercritical carbon dioxide, and is removed along with the supercritical carbon dioxide flowing out of the closed reactor.

[0318] The temperature and pressure inside the aforementioned closed reactor are set to the temperature and pressure required for carbon dioxide to reach a supercritical state. The critical point of carbon dioxide is 31.1℃ / 7.38MPa, for example, set at a temperature above 40℃ and below 200℃ / a pressure above 10MPa and below 30MPa.

[0319] The flow rate of the supercritical fluid in supercritical drying is preferably 80 mL / s or more and 240 mL / s or less.

[0320] The obtained silica particles are preferably decomposed, pulverized, or screened as needed to remove coarse particles or agglomerates. Decomposition and pulverization are carried out, for example, using dry pulverizing devices such as jet mills, vibratory mills, ball mills, and needle mills. Screening is carried out, for example, using vibrating screens and air-powered screens.

[0321] Example

[0322] The embodiments of the present invention will be described in detail below using examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "%" refers to a mass reference.

[0323] Manufacturing of Silica Particles

[0324] [Examples 1, 3-33, 35; Reference Examples 1-9]

[0325] The suspensions containing silica particles in each example were prepared as shown below.

[0326] -Preparation of alkaline catalyst solution-

[0327] A base catalyst solution was obtained by adding methanol, ion-exchanged water, and ammonia (NH4OH) in the amounts and concentrations shown in Table 1 to a glass reaction vessel equipped with a metal stirring rod, a drip nozzle, and a thermometer, and stirring the mixture.

[0328] Granulation of silica masterbatch via sol-gel method-

[0329] The temperature of the alkaline catalyst solution was adjusted to 40°C, and nitrogen replacement was performed on the alkaline catalyst solution. Then, while stirring the alkaline catalyst solution, 124 parts by mass of tetramethoxysilane (TMOS) and ammonia water (NH4OH) with a catalyst concentration of 7.9% were added dropwise to obtain a silica masterbatch suspension.

[0330] -Addition of silane coupling agent-

[0331] The silica masterbatch suspension was heated to 40°C, and silane coupling agents of the types and amounts shown in Table 1 were added to the suspension while stirring. Stirring was then continued for 120 minutes to allow the silane coupling agents to react, thereby forming an adsorption structure.

[0332] -Addition of nitrogen-containing compounds-

[0333] An alcoholic solution was prepared by diluting the nitrogen-containing compounds shown in Table 1 with butanol.

[0334] Next, an alcohol solution prepared by diluting the nitrogen-containing compound with butanol was added to the suspension. At this point, the alcohol solution was added in such a manner that the amount of the nitrogen-containing compound relative to 100 parts by mass of the solid content of the silica masterbatch suspension was as shown in Table 1. Then, the mixture was stirred at 30°C for 100 minutes to obtain a suspension containing the nitrogen-containing compound.

[0335] -dry-

[0336] Next, 300 parts by mass of the suspension were placed in a reaction vessel, and CO2 was introduced while stirring. The temperature and pressure in the reaction vessel were then increased to the levels shown in Table 1. While maintaining the temperature and pressure, CO2 was introduced and discharged at a flow rate of 5 L / min. Then, the solvent was removed over a period of 120 minutes, yielding silica particles for each example.

[0337] [Example 2]

[0338] Using a small spray dryer B-290 (manufactured by Nihon BUCHI. KK), the cylinder was set to the temperature and pressure shown in Table 1, and spray drying was carried out under the condition of feeding silica particle suspension at a feed rate of 0.2 L / h. Otherwise, silica particles were obtained in the same manner as in Example 1.

[0339] [Example 33]

[0340] After adding a nitrogen-containing compound, hexamethyldisilazane (HMDS) at a mass of 30% relative to the solid content of the silica masterbatch was added, and the surface of the silica masterbatch was hydrophobically treated by stirring at 65°C for 3 hours. Otherwise, silica particles were obtained in the same manner as in Example 1.

[0341] [Example 34]

[0342] As a silica masterbatch, 30g of dry silica AEROSIL130 (manufactured by NIPPON AEROSIL CO.,LTD.) was dispersed in 300g of methanol to obtain a silica masterbatch suspension. Otherwise, silica particles were obtained in the same manner as in Example 1.

[0343] [Compare Examples 1, 2, and 3]

[0344] The amounts of silane coupling agent and nitrogen-containing compound added were set as shown in Table 1. Otherwise, silica particles were obtained in the same manner as in Example 1.

[0345] [evaluate]

[0346] (Various characteristics)

[0347] The following properties of the obtained silica particles were determined according to the methods described above.

[0348] • Net intensity of molybdenum (labeled "Mo" in the table)

[0349] • The ratio of net strength of molybdenum to net strength of silicon (labeled as "Mo / Si" in the table)

[0350] • Number-average particle size (labeled as "particle size" in the table)

[0351] • Number granularity distribution index (marked as "GSD" in the table)

[0352] • Average roundness (marked as "roundness" in the table)

[0353] • The pore volume A with a pore diameter of 1 nm or more and less than 50 nm is obtained from the pore distribution curve of nitrogen adsorption method before calcination at 350℃ (marked as “pore volume A before calcination at 350℃” in the table).

[0354] • The pore volume B, calculated based on the pore distribution curve obtained by nitrogen adsorption after calcination at 350℃, is the pore volume B with a pore diameter greater than 1 nm and less than 50 nm (marked as "pore volume B after calcination at 350℃" in the table).

[0355] • Volume resistivity Ra before calcination at 350℃ (marked as "Volume resistivity Ra before calcination" in the table)

[0356] • Volume resistivity Rb after calcination at 350℃ (marked as "volume resistivity Rb after calcination" in the table)

[0357] • OH radical content determined using the Sears method (labeled as "OH radical content" in the table)

[0358] • The proportion of the integrated values ​​C of signals observed in the range above -50 ppm and below -75 ppm in the Si-CP / MAS NMR spectrum when the integral value of all signals is set to 100% (labeled as "Si-CP / MAS Area Ratio C" in the table).

[0359] The ratio C / D of the integral value C of the signal observed in the Si-CP / MAS NMR spectrum in the range of chemical shift above -50 ppm and below -75 ppm to the integral value D of the signal observed in the range of chemical shift above -90 ppm and below -120 ppm (labeled as "Si-CP / MAS ratio C / D" in the table).

[0360] Hydrophobicity

[0361] (Environmental dependence of charge carrying capacity in low humidity and charge carrying capacity in high humidity / static capacitance)

[0362] The environmental dependence of electrostatic capacitance was evaluated by measuring the low-humidity and high-humidity charge of silica particles in each example. Additionally, A through B are acceptable in the standard.

[0363] The evaluation method is as follows.

[0364] Five g of silica particles (2% by mass of the prepared silica particles added to the surface of MA1010 manufactured by NIPPON SHOKUBAI CO.,LTD.) and 50 g of KNI106GSM manufactured by JFE Chemical Corporation were mixed. The mixed sample shown on the left was stirred for 5 minutes in a 10°C, 10%RH chamber using a TURBLER shaker, and the result obtained by measuring the charge using a TB200 manufactured by TOSHIBA CORPORATION was designated as FC. The result obtained by stirring for 5 minutes in a 30°C, 90%RH chamber using a TURBLER shaker and measuring the charge using a TB200 manufactured by TOSHIBA CORPORATION was designated as FA. The ratio FA / FC was used for evaluation.

[0365] A (◎): FA / FC is 0.8 or higher and less than 1.1

[0366] B(〇): FA / FC is greater than 0.65 and less than 0.8

[0367] C (△): FA / FC is greater than 0.5 and less than 0.65

[0368] D (×): FA / FC less than 0.5

[0369] (Charge distribution under low temperature and low humidity environment)

[0370] The charge distribution of silica particles in each example under low temperature and low humidity conditions (10°C and 10%RH) was evaluated as follows.

[0371] A mixture of 5 g of silica particles (2% by mass of the prepared silica particles added to the surface of MA1010 manufactured by NIPPON SHOKUBAI CO.,LTD.) and 50 g of KNI106GSM manufactured by JFE Chemical Corporation was prepared. The mixed sample described on the left was stirred for 5 minutes in a 10°C, 10%RH chamber using a TURBLER shaker and evaluated by CSG (charge spectrograph method) image analysis. The charge distribution was defined as [Q(80) - Q(20)] / Q(50), which is the difference between the cumulative charge Q(20) and the cumulative charge Q(80) of the charge distribution, divided by the cumulative charge Q(50), i.e., [Q(80) - Q(20)] / Q(50). The evaluation criteria are as follows.

[0372] A(◎): [Q(80)-Q(20)] / Q(50) value is less than 0.7

[0373] B(○): [Q(80)-Q(20)] / Q(50) value is less than 0.8 and greater than 0.7.

[0374] C(△): [Q(80)-Q(20)] / Q(50) value is less than 1.0 and greater than 0.8

[0375] D(×): [Q(80)-Q(20)] / Q(50) has a value of 1.0 or higher.

[0376] (Maintenance of narrow band distribution under high temperature and high humidity environment)

[0377] The maintenance of the narrow bandgap distribution of the silica particles in each example under high temperature and high humidity conditions (30°C and 90%RH) was evaluated as follows.

[0378] A mixture of 5 g of silica particles (2% by mass of the prepared silica particles added to the surface of MA1010 manufactured by NIPPON SHOKUBAI CO.,LTD.) and 50 g of KNI106GSM manufactured by JFE Chemical Corporation was prepared. The mixed sample described on the left was stirred for 100 min in a 30°C, 90%RH chamber using a TURBLER shaker and evaluated by CSG (charge spectrograph method) image analysis. The charge distribution was defined as [Q(80) - Q(20)] / Q(50), which is the difference between the cumulative charge Q(20) and the cumulative charge Q(80) of the charge distribution, divided by the cumulative charge Q(50), i.e., [Q(80) - Q(20)] / Q(50). The evaluation criteria are as follows.

[0379] A(◎): [Q(80)-Q(20)] / Q(50) value is less than 0.75

[0380] B(○): [Q(80)-Q(20)] / Q(50) value is less than 0.85 and greater than 0.75

[0381] C(△): [Q(80)-Q(20)] / Q(50) value is less than 1.0 and greater than 0.85

[0382] D(×): [Q(80)-Q(20)] / Q(50) has a value of 1.0 or higher.

[0383] (Maintenance of narrow bandgap distribution under low temperature and low humidity environment)

[0384] Regarding the maintenance of the narrow bandgap distribution of the silica particles in each example under low temperature and low humidity conditions (10℃ 10%RH), the evaluation was conducted under low temperature and low humidity conditions (10℃ 10%RH). Otherwise, the maintenance of the narrow bandgap distribution was evaluated in the same manner as under high temperature and high humidity conditions (30℃ 90%RH).

[0385] The evaluation results are shown in Table 1.

[0386] In addition, the details of the abbreviations in Table 1 are as follows.

[0387] MTMS: Methyltrimethoxysilane

[0388] DTMS: n-Dodecyltrimethoxysilane

[0389] ·TP-415: [N + (CH)3(C 14 C 29 )2]4Mo8O 28 4-(Manufactured by Hodogaya Chemical Co., Ltd., N,N-Dimethyl-N-tetradecyl-1-tetradecanaminium, hexa-μ-oxotetra-μ3-oxodi-μ5-oxotetradecaoxooctamolybdate (4-) (4:1)) (Extraction yield X = 61-89% by mass using ammonia / methanol mixture, and the ratio of extraction yield X to extraction yield Y using water X / Y = 0.03-0.26)

[0390] • Dimethylstearylammonium chloride (extraction yield X = 75% by mass when extracted with ammonia / methanol mixed solution, and the ratio of extraction yield X to extraction yield Y when extracted with water is X / Y = 0.28)

[0391] • Tributylamine (extraction yield X = 65% by mass using ammonia / methanol mixed solution, and the ratio of extraction yield X to extraction yield Y using water is X / Y = 0.29)

[0392] • Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (extraction yield X = 76% by mass using ammonia / methanol mixed solution, ratio of extraction yield X to extraction yield Y using water X / Y = 0.25)

[0393] Quotanium-80 (Extraction yield X = 80% by mass using ammonia / methanol mixed solution, ratio of extraction yield X to extraction yield Y using water X / Y = 0.09)

[0394] • Bis(dibutyldibenzylammonium)molybdic acid (extraction yield X = 65% by mass using ammonia / methanol mixed solution, ratio of extraction yield X to extraction yield Y using water X / Y = 0.15)

[0395] • Phenethylamine (extraction yield X = 55% by mass using ammonia / methanol mixed solution, the ratio of extraction yield X to extraction yield Y using water is X / Y = 0.28)

[0396] ·4-(2-Octylamino)diphenylamine (extraction yield X = 78% by mass using ammonia / methanol mixed solution, ratio of extraction yield X to extraction yield Y using water X / Y = 0.14)

[0397] • N-Benzyl-N-methylethanolamine (extraction yield X = 58% by mass using ammonia / methanol mixed solution, ratio of extraction yield X to extraction yield Y using water X / Y = 0.27)

[0398] ·2,3-Bis(2,6-diisopropylphenylimino)butane (extraction yield X = 81% by mass using ammonia / methanol mixed solution, ratio of extraction yield X to extraction yield Y using water X / Y = 0.11)

[0399] ·3-Indoleacetonitrile (extraction yield X = 80% by mass using ammonia / methanol mixed solution, and the ratio of extraction yield X to extraction yield Y using water is X / Y = 0.12)

[0400] • Hexadecyltrimethylammonium bromide (extraction yield X = 18% by mass using ammonia / methanol mixed solution, ratio of extraction yield X to extraction yield Y using water X / Y = 5.28)

[0401] [Table 1-1]

[0402]

[0403] [Table 1-2]

[0404]

[0405] [Table 1-3]

[0406]

[0407] Based on the above results, it can be seen that, compared with the silica particles of the comparative example, the silica particles of the embodiment have a narrow charge distribution when charged, and the maintenance of the narrow charge distribution is excellent.

[0408] The embodiments of the present invention described above are provided for illustrative purposes. Furthermore, these embodiments do not encompass the entirety of the invention, nor do they limit the invention to the disclosed methods. It will be apparent to those skilled in the art that various modifications and variations will be readily understood. These embodiments were chosen and described to most readily explain the principles and applications of the invention. Thus, those skilled in the art can understand the invention through various modifications that are assumed to be optimized for specific uses of various embodiments. The scope of the invention is defined by the foregoing claims and their equivalents.

Claims

1. A type of silica particle, comprising: Silica masterbatch; Structure; and Nitrogen-containing compounds containing molybdenum, Furthermore, the ratio of the net intensity of molybdenum to the net intensity of silicon, as determined by fluorescence X-ray analysis, is greater than 0.035 and less than 0.

35. The structure, which covers at least a portion of the surface of the silica masterbatch, is composed of at least one reaction product selected from the group consisting of monofunctional silane coupling agents, difunctional silane coupling agents, and trifunctional silane coupling agents, and the nitrogen-containing compound is adsorbed in at least a portion of the pores of the reaction product. The amount of the structure attached relative to the silica particles is 5.5% by mass or more and 30% by mass or less, and The nitrogen-containing compound is selected from at least one of the group consisting of quaternary ammonium salts containing molybdenum and mixtures of quaternary ammonium salts and metal oxides containing molybdenum.

2. The silica particles according to claim 1, wherein the average particle size is 10 nm or more and 200 nm or less.

3. The silica particles according to claim 1 or 2, wherein the degree of hydrophobicity is 10% or more and 60% or less.

4. The silica particles according to claim 1 or 2, wherein, When the pore volumes (those with pore diameters greater than 1 nm and less than 50 nm, determined from the pore distribution curves obtained by nitrogen adsorption before and after calcination at 350℃) are denoted as A and B respectively, the ratio of B / A is greater than 1.2 and less than 5, and B is 0.2 cm. 3 / g or more and 3cm 3 / g or less.

5. The silica particles according to claim 1 or 2, wherein, Obtained through cross-polarization / magic angle rotation method 29 The ratio C / D of the integral value C of the signal observed in the Si solid-state nuclear magnetic resonance spectrum in the range of chemical shift above -50 ppm and below -75 ppm to the integral value D of the signal observed in the range of chemical shift above -90 ppm and below -120 ppm is above 0.10 and below 0.

75.

6. The silica particles according to claim 1 or 2, wherein, The extraction yield X of the nitrogen-containing compound obtained using an ammonia / methanol mixed solution is 0.1% by mass or more. The extraction amount X of the nitrogen-containing compound and the extraction amount Y of the nitrogen-containing compound extracted using water satisfy the formula: Y / X < 0.

3.

7. The silica particles according to claim 1 or 2, wherein the average sphericity is 0.60 or more and 0.96 or less.

8. The silica particles according to claim 1 or 2, wherein the number-to-particle-size distribution index is 1.1 or higher and 2.0 or lower.

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