JP2009120416A - Particle and method for producing particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide particles which use silica as a base material, is excellent in hydrophobicity and suppressed in cohesive force, and has high dispersibility. <P>SOLUTION: The particles are each composed of silica having at least two kinds of -OR groups (wherein, R is a group selected from an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group) on its surface and an organopolysiloxane covering the silica. Preferable R-group of the -OR group in each particle is one or more kinds selected from a 4-18C chain-like alkyl group, cyclic alkyl group, aralkyl group and hydroxy alkyl group, and a 1-3C chain-like alkyl group. The particles are produced by preparing silica having at least two kinds of -OR groups on its surface and covering the silica with an organopolysiloxane. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to particles excellent in hydrophobicity and dispersibility, which are suitable for use as an external additive for toners and have silica as a core material.

  Silica particles are used as fillers for semiconductor encapsulating resins and as external additives for toners for equipment such as copiers and printers. For example, when silica particles are used as an external additive for toner, improving the fluidity, fixability, and cleaning properties of the toner is an effect of using silica particles.

  In Patent Documents 1 to 3, silica particles produced by a dry method such as a flame method or silica particles produced by a wet method such as an alkoxide method are used as silica particles for an external additive of a toner. A surface treated with a mixture of silane and silicone oil is disclosed. Among such silica particles, silica particles treated with alkoxysilane have a problem of low hydrophobicity. On the other hand, silica particles treated with silicone oil are excellent in hydrophobicity. The excellent hydrophobicity of the silica particles is another characteristic required for the external additive for toner.

Incidentally, as described above, silica particles are required to improve the fluidity of the toner. However, the silica particles are cohesive. Fluidity may not be improved. Therefore, it is desired to realize silica particles with reduced cohesive force, that is, silica particles with high dispersibility.
JP 2004-145325 A JP-A-2005-15251 Japanese Patent No. 2886037

  In view of the above circumstances, an object of the present invention is to provide particles based on silica, which are excellent in hydrophobicity, have low cohesive force, and have high dispersibility.

  As a result of intensive studies on particles in which silica is coated with an organopolysiloxane, the present inventor has a cohesive force more than particles having no organic group when only one predetermined organic group is present on the surface of the silica. On the other hand, when two or more kinds of predetermined organic groups are present on the silica surface, the knowledge that the cohesive force is lower than that of particles having no organic group is obtained, and the hydrophobicity and dispersibility according to the present invention are obtained. Led to the completion of high particles.

  That is, the particles according to the present invention are selected from two or more kinds of —OR groups (R is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group. It is characterized in that it has a silica having a surface thereof and an organopolysiloxane covering the silica.

  The R group of the -OR group is one or more selected from a chain alkyl group having 4 to 18 carbon atoms, a cyclic alkyl group, an aralkyl group, and a hydroxyalkyl group, and a chain structure having 1 to 3 carbon atoms. Combinations with alkyl groups are preferred. The amount of each —OR group in the silica is preferably 1% by mass or more and 15% by mass or less.

  The silica may be further surface-treated with a silylating agent. The particles according to the present invention subjected to the treatment have excellent hydrophobicity even when the amount of organopolysiloxane is small.

The average particle diameter of the silica is preferably 0.01 μm or more and 2 μm or less, and the coefficient of variation of the average particle diameter of silica is preferably 10% or less. Here, the “average particle diameter of silica” is an average value obtained by observing particles at about 10,000 magnifications using a scanning electron microscope (SEM) and randomly measuring the diameter of primary particles of silica. is there. The “coefficient of variation in the particle diameter of silica” is a value obtained by applying the average particle diameter of silica and the standard deviation of the primary particle diameter of silica to the following equation.
Variation coefficient of silica particle diameter (%) = standard deviation of primary particle diameter / average particle diameter × 100

  In the particles according to the present invention, (high dispersion particle diameter) / (silica average particle diameter) is preferably 5.0 or less, and the coefficient of variation of the high dispersion particle diameter is preferably 30% or less. Here, the “highly dispersed particle size” is obtained by stirring a mixed liquid of 2 parts by mass of particles according to the present invention and 100 parts by mass of methanol for 20 minutes and treating the dispersion obtained by treating with an ultrasonic disperser for 10 minutes or more. It is an arithmetic average value of a volume-based particle size distribution used as a sample solution and obtained using a laser diffraction / scattering particle size distribution measuring apparatus. The “variation coefficient of the highly dispersed particle size” uses the standard deviation (σ) of the volume-based particle size distribution and the highly dispersed particle size (arithmetic average value (D) of the volume-based particle size distribution) obtained by the above measurement. The value obtained by calculating σ / D × 100.

  The method for producing particles according to the present invention is selected from two or more -OR groups (R is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group. And a step of coating the silica with an organopolysiloxane. In the coating of the organopolysiloxane, the organopolysiloxane is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of silica.

  The particles according to the present invention are excellent in hydrophobicity and dispersibility since silica having a surface on which two or more kinds of predetermined organic groups are present is coated with an organopolysiloxane.

(particle)
The particle | grains which concern on this invention are particles which consist of a silica and the organopolysiloxane which coat | covers the said silica.

  The shape of the particles of the present invention is preferably substantially spherical. The ratio of the longest diameter to the shortest diameter of the particles is preferably 0.90 or more, preferably 0.92 or more, more preferably 0.95 or more, and still more preferably 0.98 or more.

  The average particle size of the particles according to the present invention means the average particle size of primary particles. The average particle diameter is not particularly limited, but the lower limit is preferably 0.01 μm, preferably 0.02 μm, the upper limit is 5 μm, preferably 2 μm, and more preferably 1 μm. Preferably, the thickness is 0.5 μm. The average particle diameter of the particles is an average value when the particles according to the present invention are observed at a magnification of about 10,000 using a scanning electron microscope (SEM) and the diameters of the primary particles are randomly measured. .

The coefficient of variation in the primary particle size of the particles of the present invention is not particularly limited, but may be desired to be a small coefficient of variation. The coefficient of variation is preferably 30% or less, preferably 20% or less, more preferably less than 15%, and even more preferably 10% or less. The coefficient of variation in the particle size of the particles of the present invention is a value obtained by applying the average particle size of the particles and the standard deviation of the particle size of the particles to the following equation (1).
Formula (1): Variation coefficient (%) of the particles of the present invention = standard deviation of particle diameter / average particle diameter × 100

  The lower limit of the highly dispersed particle diameter of the particles is preferably 0.01 μm, and may be 0.03 μm. On the other hand, the upper limit is that the particle diameter is too large, which means that many particles are aggregated. Therefore, it is preferably 10 μm, preferably 4 μm, more preferably 2 μm, and 1 μm. Is most preferred. As described above, the “highly dispersed particle diameter” of the particles according to the present invention is the volume obtained by using a laser diffraction / scattering particle size distribution measuring device for a mixture of stirred and ultrasonically dispersed particles and methanol. It is the arithmetic mean value of the standard particle size distribution.

The coefficient of variation of the highly dispersed particle size may be desired to be a small coefficient of variation. This coefficient of variation is preferably 30% or less. The coefficient of variation of the highly dispersed particle diameter is a value obtained by applying the above highly dispersed particle diameter and the standard deviation of the highly dispersed particle diameter to the following equation (2).
Formula (2): Coefficient of variation of high dispersion particle diameter (%) = standard deviation of high dispersion particle diameter / high dispersion particle diameter × 100

The particle diameter ratio (3) calculated by the following formula (3) using the value of the average particle diameter of silica described later and the highly dispersed particle diameter of the particles according to the present invention is preferably 5.0 or less, It is preferable that it is 1.5 or less. On the other hand, the lower limit of the particle size ratio (3) is preferably 0.8, and may be 1.0.
Formula (3): Particle size ratio (3) = (Highly dispersed particle size) / (Average particle size of silica)

Using the values of the average particle size and the highly dispersed particle size of the particles according to the present invention, the particle size ratio (4) calculated by the following formula (4) is preferably 5.0 or less, and 2.0 Or less, more preferably 1.5 or less, and even more preferably 1.3 or less.
Formula (4): Particle size ratio (4) = (Highly dispersed particle size) / (Average particle size of particles according to the present invention)

  The low dispersion particle diameter of the particles is an arithmetic average value of the volume-based particle size distribution obtained by using a laser diffraction / scattering particle size distribution measuring device for the mixed solution of the stirred particles and methanol. That is, the method for obtaining the low dispersion particle size is different from the method for obtaining the high dispersion particle size only in that the mixed liquid of particles and methanol is not subjected to ultrasonic treatment. The lower limit of the low dispersion particle diameter is preferably 0.01 μm, and the upper limit is preferably 10 μm. Most preferred is a low dispersion particle size that matches the high dispersion particle size.

The particle diameter ratio (5) calculated by the following formula (5) is preferably 15.0 or less, using the values of the average particle diameter of the silica described later and the low dispersion particle diameter of the particles according to the present invention. It is preferably 10.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less. On the other hand, the lower limit of the particle size ratio (5) is preferably 0.8, and may be 1.0.
Formula (5): Particle size ratio (5) = (Low dispersion particle size) / (Average particle size of silica)

  If the degree of hydrophobicity of the particles is too low, the particles tend to aggregate. Therefore, the degree of hydrophobicity is preferably 60 or more, preferably 65 or more, more preferably 68 or more, and still more preferably 70 or more. This degree of hydrophobicity is a measure of the hydrophobicity of the particles. The value of the degree of hydrophobicity is determined by gradually introducing methanol into the water after the particles float on the surface of 50 cc of water until the particles sink. That is, the percentage of methanol introduced in the total volume of water and methanol introduced is the degree of hydrophobicity.

  The charge amount of the particles is preferably 10 μC / g, preferably 20 μC / g, more preferably 50 μC / g, and even more preferably 100 μC / g as the lower limit of the absolute value. That is, the lower limit of the charge amount in the case of positive charge is preferably +10 μC / g, preferably +20 μC / g, more preferably +50 μC / g, further preferably +100 μC / g, and negative charge. In this case, the upper limit of the charge amount is preferably −10 μC / g, preferably −20 μC / g, more preferably −50 μC / g, and further preferably −100 μC / g. The charge amount is a value obtained by measuring the mixture of the particles of the present invention and carrier particles with a blow-off charge amount measuring device.

  In the particles of the present invention, metal elements such as sodium, potassium, lithium, calcium, magnesium, aluminum, iron, and chromium; and halogen elements such as chlorine and fluorine are impurities. This impurity causes the toner charge amount to become unstable when the particles of the present invention are used as an external additive for the toner. Therefore, the content of each element is preferably 5 ppm or less. The content of the element is determined by a method defined in JIS. For example, the contents of sodium, potassium, and lithium are determined by atomic absorption analysis according to JIS K 0121, and the contents of calcium, magnesium, aluminum, iron, and chromium are determined by ICP emission spectroscopy according to JIS K 0116. It is calculated | required by analysis and about chlorine and a fluorine, it calculates | requires by the analysis by the ion chromatograph according to JISK0127.

silica:
Silica is mainly composed of a three-dimensional network of siloxane bonds, and two or more kinds of —OR groups exist on this surface. Dispersibility deteriorates when there is only one -OR group present in the silica, but in the particles of the present invention, two or more -OR groups are present on the surface of the silica that is the core of the particles. Therefore, dispersibility is improved. “The —OR group is present” on the surface of the silica means that the —OR group is bonded to the Si element of the silica, and / or the compound (eg, alcohol) having the —OR group is adsorbed to the silica surface. Means that It is particularly preferred that the —OR group is bonded to the Si element of the silica.

  The R group of the -OR group is a group selected from an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group.

  When the —OR group is bonded to the Si element of silica and the R group is an alkyl group which may have a substituent, the structure of the R group is linear, branched, cyclic, etc. There is no particular limitation. Specific examples of the R group include chain alkyl such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, pentyl group, 2-ethylhexyl group, lauryl group, stearyl group, and oleyl group. A cyclic alkyl group such as cyclohexyl group; 2-hydroxyethyl group, 3-hydroxypropyl group, 2-hydroxypropyl group, 4-hydroxybutyl group, 3-hydroxybutyl group, 5-hydroxypentyl group, 6-hydroxyhexyl Group, 7-hydroxyheptyl group, 8-hydroxyoctyl group, 9-hydroxynonyl group, 10-hydroxydecyl group, 2,2-dimethyl-3-hydroxypropyl group, 2-hydroxycyclopentyl group, 2-hydroxycyclohexyl group, 4-hydroxycyclohexyl group, 2,3-dihydroxy group Hydroxyalkyl groups such as pill groups and pentahydroxyhexyl groups; phenylalkyl groups such as benzyl groups, phenethyl groups, α-methylphenethyl groups, diphenylmethyl groups, triphenylmethyl groups, 1,2-diphenyl-2-hydroxyethyl groups Or an aralkyl group;

  When the —OR group is bonded to the Si element of silica and the R group is an alkenyl group which may have a substituent, the structure of the R group is linear, branched, cyclic, etc. There is no particular limitation. Specific examples of the R group include chain alkenyl groups such as vinyl group, allyl group, propenyl group, isopropenyl group, 2-methyl-1-propenyl group, 2-methylallyl group, 2-butenyl group, and linolyl group; And a chain alkenyl group substituted with an aromatic ring such as a styryl group and a cinnamyl group.

  When the —OR group is bonded to the Si element of silica and the R group is an aryl group, a specific example of the R group includes a phenyl group.

  When the —OR group is bonded to the Si element of silica, one or more selected from a chain alkyl group having 4 to 18 carbon atoms, a cyclic alkyl group, an aralkyl group, and a hydroxyalkyl group; A chain alkyl group having 1 to 3 carbon atoms is particularly preferably an R group in the -OR group.

  When the compound having —OR group is adsorbed on the silica surface and the R group is an alkyl group which may have a substituent, the structure of the compound is linear, branched, cyclic, etc. There is no particular limitation. Examples of the compound include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-methyl-1-propyl alcohol, 2-methyl-2-propyl alcohol, 1-butyl alcohol, and 2-butyl alcohol. Monovalent saturated aliphatic alcohols such as pentyl alcohol, 2-ethylhexyl alcohol, lauryl alcohol, stearyl alcohol; monovalent saturated alicyclic alcohols such as cyclohexanol; ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1, , 10-decanediol, 2,2-di Saturated aliphatic glycols such as methyl-1,3-propanediol, 2,3-dimethyl-2,3-butanediol; cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4 -Saturated alicyclic glycol such as diol; glycerin; sugar alcohol such as inositol, sorbitol, mannitol, xylitol; aralkyl alcohol such as benzyl alcohol, phenethyl alcohol, 1-phenyl-2-propanol, diphenylmethanol, triphenylmethanol; hydro; And saturated aliphatic glycols substituted with an aromatic ring such as benzoin and benzpinacol.

  Even when a compound having an —OR group is adsorbed on the silica surface and the R group is an alkenyl group which may have a substituent, the structure of the compound is linear, branched, cyclic, etc. There is no particular limitation. Examples of the compound having an alkenyl group as the R group include vinyl alcohol, allyl alcohol, isopropenyl alcohol, 2-methyl-1-propenyl alcohol, 2-methylallyl alcohol, 2-butenyl alcohol, oleyl alcohol, and linolyl alcohol. Unsaturated fatty alcohol; unsaturated aliphatic alcohol substituted with an aromatic ring such as styryl alcohol and cinnamyl alcohol; and the like.

  When the compound having an —OR group is adsorbed on the silica surface and the R group is an aryl group, examples of the compound include phenol.

  When a compound having an —OR group is adsorbed on the silica surface, a compound having a chain alkyl group having 4 to 18 carbon atoms as an R group, a compound having a cyclic alkyl group as an R group, and an aralkyl group as an R group And a combination of one or more compounds selected from a compound having a hydroxyalkyl group as an R group and a compound having a chain alkyl group having 1 to 3 carbon atoms as an R group is preferable.

  A preferable combination of compounds when a compound having an -OR group is adsorbed on the silica surface is a combination of two or more kinds of alcohols represented by H-OR.

  Presence of —OR group in silica can be confirmed by a simultaneous carbon / hydrogen / nitrogen determination apparatus CHN coder and infrared spectroscopic analysis apparatus. The presence of the —OR group means that silica is contained in carbon, and this carbon content can be quantified by a carbon / hydrogen / nitrogen simultaneous determination apparatus CHN coder. Further, the type of —OR group can be identified by an infrared spectroscopic analyzer.

  Further, the content of —OR group in silica can be quantified by the following method. First, 1 g of silica and 50 ml of 0.05 N NaOH aqueous solution are mixed, and then stirred at room temperature for 10 hours to prepare a suspension. The suspension is centrifuged, and the supernatant of the solution is collected. . Next, the supernatant is analyzed by a gas chromatograph according to JIS K 0114, and the alcohol content is determined as the —OR group content.

  If the lower limit of the amount of each —OR group in silica is too small, good particle dispersibility may not be realized, so that the amount of —OR group is 1.0% by mass in 100% by mass of silica present on the surface. It is preferably 2.0% by mass, more preferably 3.0% by mass, and even more preferably 4.0% by mass. On the other hand, the upper limit amount of each —OR group is not particularly limited, but may be 15.0% by mass, preferably 12.5% by mass, more preferably 10.0% by mass, and 8.0. More preferably, it is mass%.

  The upper limit of the total amount of —OR groups in silica is preferably 30.0% by mass in 100% by mass of silica in which —OR groups are present on the surface, and is preferably 25.0% by mass, and 20.0% by mass. Is more preferable, and 16.0% by mass is even more preferable. On the other hand, the lower limit of the total amount of —OR groups is preferably 2.0% by mass, preferably 4.0% by mass, more preferably 6.0% by mass, and 8.0% by mass. And more preferred.

  The shape of the silica is preferably a true sphere or a substantially sphere.

  The average particle diameter of the silica is not particularly limited, but the lower limit is preferably 0.01 μm, preferably 0.02 μm, the upper limit is preferably 5 μm, is preferably 2 μm, and is 1 μm. More preferably, it is still more preferable in it being 0.5 micrometer. As described above, the average particle diameter is an average value of values obtained by randomly measuring the diameter of the primary particle diameter of silica observed by SEM.

  The coefficient of variation of the silica particle diameter is not particularly limited, but is preferably 30% or less, preferably 20% or less, more preferably less than 15%, and still more preferably 10% or less. The coefficient of variation is, as described above, 100% of the standard deviation of the silica particle diameter with respect to the average particle diameter of the primary particles of silica.

The moisture absorption rate of silica is not particularly limited, but may be 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less. The moisture absorption rate here is calculated as follows. First, the mass (about 5 g) of silica before the moisture absorption test is accurately measured, and this mass is defined as W ₁ . Next, the silica is spread thinly on a watch glass having a diameter of 10 cm, and the watch glass is left in an environment of 30 ° C. and 90% RH (relative humidity) for one day. The mass W ₂ of the silica particles after standing is measured. And a moisture absorption rate is computed by following Formula (6).
Formula (6): Moisture absorption rate (mass%) of silica = (W ₂ −W ₁ ) / W ₁ × 100

  The silica surface before being coated with the organopolysiloxane may be treated with a silylating agent. If the amount of the organopolysiloxane covering the silica is small, the hydrophobization degree of the particles cannot be maintained high without the treatment of the silylating agent having a three-dimensional surface modification group. In this case, a certain degree of silanol groups on the silica surface is capped, so that a high degree of hydrophobicity of the particles can be maintained.

  One or more known silylating agents capable of silylating hydrogen in a hydroxyl group or the like can be used as silylating agents for treating silica.

The silylating agent in the present invention is preferably a silicon compound (a) represented by the following general formula (a). Silazane compounds are also preferred as silylating agents in the present invention.
R ¹ _m SiR ² _(4-m) (a)
In the general formula (a), R ¹ represents one or more groups selected from an alkyl group (for example, an aralkyl group), an aryl group, and an alkenyl group, which may have a substituent, An alkyl group is preferred, and a methyl group is particularly preferred. R ² represents one or more groups selected from a hydroxyl group, an alkoxy group, an acyloxy group, a halogen atom, and a hydrogen atom, and an alkoxy group or a hydrogen atom is particularly preferable. m represents an integer of 1 to 3, and m = 3 is preferable.

  Specific examples of the silicon compound (a) represented by the general formula (a) include methyltrimethoxysilane, methyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3- Mercaptopropyltrimethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3- Trialkoxysilanes such as acryloxypropyltrimethoxysilane and vinyltrimethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxy Dialkoxysilanes such as silane, 3-chloropropylmethyldimethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane; trimethylmethoxysilane, trimethylethoxysilane Monoalkoxysilanes such as: methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, methyldiphenylchlorosilane and other chlorosilicon compounds; dimethylsilanediol, diphenylsilanediol, trimethylsilanol and other silanol compounds; etc. Is mentioned. Among these silicon compounds (a), monoalkoxysilane is preferable, and trimethylmethoxysilane is particularly preferable.

  Examples of the silazane compound include hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyldisilazane, hexaphenyldisilazane, divinyl. Examples thereof include tetramethyldisilazane and dimethyltetravinyldisilazane.

  The amount of the silylating agent in the silica treated with the silylating agent should be appropriately set according to the target dispersibility and the degree of hydrophobicity, but the total amount of silica and silylating agent is 100% by mass. In general, it is preferably 1 to 30% by mass, preferably 5 to 25% by mass, and more preferably 7 to 22% by mass.

Organopolysiloxane:
The organopolysiloxane is a molecule having a polysiloxane skeleton, and is a polymer in which an organic group such as a hydrocarbon group is bonded to the Si atom of the skeleton. The molecular structure of the organopolysiloxane is not particularly limited, and includes linear, branched, cyclic, lattice, and cage shapes. When the molecular structure of the organopolysiloxane is an acyclic structure, the terminal Si atom of this molecule is usually selected from a hydrocarbon group, an alkoxy group, a hydroxyl group, a hydrogen atom, and a halogen which may have a substituent. One or more groups to be bonded are bonded. The organopolysiloxane in the particles according to the present invention increases the degree of hydrophobicity and dispersibility of the particles by combining with two or more -OR groups on the silica surface.

The average composition formula of the organopolysiloxane preferred in the present invention is represented by the following general formula (b).
R ³ _a R ⁴ _b R ⁵ _c SiO _{d / 2} (b)
In the general formula (b), R ³ , R ⁴ and R ⁵ are groups bonded to Si atoms of the polysiloxane skeleton, and the number of carbon atoms is not particularly limited. R ³ is one or more groups selected from hydrocarbon groups, and is preferably one or more groups selected from alkyl groups, aryl groups, aralkyl groups, and alkenyl groups. R ⁴ is one or more groups selected from an alkoxy group, a hydroxyl group, a hydrogen atom, and a halogen atom, and preferably a hydrogen atom is selected. R ⁵ is a group in which some or all of the hydrogen atoms in the hydrocarbon group are substituted for other than hydrogen, and the group substituted with hydrogen is a primary amino group, a secondary amino group, a tertiary amino group, One or more groups selected from a quaternary ammonio group, an epoxy group, a glycidyl group, a mercapto group, a carboxyl group, a hydroxyl group, an alkoxy group, and a —SR ⁶ group (R ⁶ represents a hydrogen atom or an organic group) It is. And 0 <a ≦ 3, 0 ≦ b <3, 0 ≦ c <3, 0 <d <4, a + b + c + d = 4, preferably 0.5 ≦ a + b + c <3.5, more preferably 0.8 ≦ a + b + c <3.2.

  When the viscosity of the organopolysiloxane is too high, it is difficult to handle and the amount of the solvent used for dilution increases. Therefore, the viscosity of the organopolysiloxane is preferably a kinematic viscosity at 25 ° C. of 1000 cSt or less.

Depending on the intended use of the particles of the present invention, the type of organopolysiloxane is selected. For example, when selecting from the organopolysiloxane represented by the composition of the above formula (b), in order to make the particles of the present invention negatively charged, R ³ is an alkyl group (particularly a methyl group), R ⁴ Is preferably a hydrogen atom and R ⁵ having a substituent other than an amino group or an organopolysiloxane where c = 0. In order to make the particles of the present invention positively charged, it is preferable to select an organopolysiloxane in which R ⁵ has an amino group as a substituent.

  As the organopolysiloxane, a commercially available silicone oil can be used. For example, dimethyl silicone oil, methyl phenyl silicone oil, methyl hydrogen silicone oil, polyether modified silicone oil, aralkyl modified silicone oil, fluoroalkyl modified silicone oil, long chain alkyl modified silicone oil, higher fatty acid ester modified silicone oil, higher fatty acid Examples include amide-modified silicone oil, polyether / long-chain alkyl / aralkyl-modified silicone oil, long-chain alkyl / aralkyl-modified silicone oil, phenyl-modified silicone oil, and polyether / methoxy-modified silicone oil.

  In the particles of the present invention, the lower limit amount of the organopolysiloxane with respect to 100 parts by mass of silica is preferably 1 part by mass capable of coating silica, preferably 5 parts by mass, more preferably 10 parts by mass, and still more preferably 12.5 parts by mass. . On the other hand, even if the upper limit is too much, the dispersibility and the degree of hydrophobicity are not affected, so 30 parts by mass is preferable, 25 parts by mass is preferable, and 20 parts by mass is more preferable.

(Method for producing particles)
The particles according to the present invention are produced by coating organopolysiloxane on silica having two or more —OR groups on the surface.

Silica production method:
The silica in the particles of the present invention can be produced by various production methods. In the present specification, examples of suitable silica production modes include first to third silica production modes having a condensation step, a concentration step, and a drying step as described later. The first production form is a form for producing silica having two or more -OR groups in the condensation step, and the second production form is to increase the types of -OR groups (alkoxy groups) possessed by silica in the concentration step. It is a form and a 3rd manufacture form is a form which increases the kind of -OR group (alkoxy group) which a silica has in a drying process. The first to third silica production forms all form a three-dimensional network of siloxane bonds by hydrolytic condensation of a silicon compound.

  In the first production mode, as described later, the —OR group present on the silica surface can be controlled by the type of silicon compound (c), the type of solvent, and a combination thereof. When it is desired to obtain silica having two or more —OR groups in the condensation step, for example, a form in which two or more silicon compounds (c) having an alkoxy group are used; a silicon compound (c) having an alkoxy group, A form of condensation in an alcohol having an alkoxy group different from the alkoxy group of the silicon compound (c); a silicon compound (c) having or not having an alkoxy group is condensed in a solvent containing two or more alcohols A form; and a combination of these forms; and the like are preferable.

  In the second production form and the third production form, the silica prepared in the condensation step in these production forms may have less than two types of —OR groups, but the —OR group of the silica in the concentration step or the drying step. The number can be increased. That is, in the second production form and the third production form, only one kind of silicon compound (c) may be used in these condensation steps.

  In the second production form, when the silica obtained in the condensation step has an —OR group, one or more alcohols having an —OR group different from the —OR group and silica coexist in the concentration step. Thus, two or more —OR groups of silica can be provided. On the other hand, when the silica obtained in the condensation step does not have an —OR group, two or more kinds of alcohol and silica are allowed to coexist in the concentration step, so that the —OR group possessed by the silica becomes two or more types. be able to. As described later, the —OR group of the alcohol coexisting with silica in the second production form is transesterified with a silanol group on the silica surface or a part or all of the —OR group on the same surface. In order to perform this exchange efficiently, it is preferable that the conditions in the concentration step in which alcohol coexists are the heating conditions.

  In the third production mode, when the silica after the concentration step has an -OR group, one or more alcohols having an -OR group different from the -OR group and silica are allowed to coexist in the drying step. In addition, two or more —OR groups of silica can be used. On the other hand, when the silica obtained in the concentration step does not have an —OR group, two or more kinds of alcohol and silica are allowed to coexist in the drying step, so that the —OR group that the silica has becomes two or more types. be able to. As described later, the —OR group of the alcohol coexisting with silica in the third production form is transesterified with a silanol group on the silica surface or a part or all of the —OR group on the same surface. In order to perform this exchange efficiently, it is preferable to set the conditions in the drying step in which alcohol is present as heating conditions.

  Below, the manufacturing form of the 1st thru | or 3rd silica is explained in full detail. In addition, for example, a method in which silica having —OR group or silica having no —OR group obtained by a method other than condensation of silicon compound (c) is dispersed in alcohol and heated; Silica having two or more kinds of —OR groups obtained by a method such as a method of drying silica having —OR groups or a silica having no —OR groups obtained by a method other than condensation; Although the method according to the first to third silica production modes described in detail below has a large amount of -OR groups, the coating of the organopolysiloxane and / or the treatment with the silylating agent is made uniform. This is preferable because the excellent dispersibility of silica desired to be obtained can be realized.

  The production form of the first silica includes a condensation step of hydrolyzing and condensing the following silicon compound (c), a concentration step of concentrating a dispersion of the hydrolysis condensate (silica) obtained in the condensation step and a solvent, and A drying step for drying the hydrolyzed condensate after the concentration is provided. Silica obtained through the drying step is silylated in the silylation step as necessary.

From the viewpoint of easy availability and low cost, one or more silicon compounds (c) represented by the following general formula (c) are used in the condensation step.
R ⁷ _n SiR ⁸ _(4-n) (c)
In the general formula (c), R ⁷ represents an alkyl group (for example, alkyl group, hydroxyalkyl group, aralkyl group) which may have a substituent, an aryl group, and an alkenyl which may have a substituent. It represents one or more groups selected from the group, and preferably an alkyl group having 1 to 10 carbon atoms is selected. R ⁸ represents one or more groups selected from a hydroxyl group, an alkoxy group, and an acyloxy group. n represents an integer of 0 to 3.

  In order to easily control the particle diameter of silica, it is preferable to use a silicon compound (c) having an n number of 0 and / or 1. At this time, other silicon compound (c) may be used in combination, but the amount of silicon compound (c) having n number 0 and silicon compound (c) having n number 1 in all silicon compounds (c) It is suitable that it is 80 mass% or more. Further, when the silicon compound (c) having n number of 0 and the silicon compound (c) having n number of 1 are used in combination, the silicon compound (c) having 0 number of n is converted into the silicon compound (c) having 1 n number. It is preferred that the amount be greater than

  Examples of the silicon compound (c) include tetrafunctional silicon compounds such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and dimethoxydiethoxysilane (wherein n in the above general formula (c) is n). Compound which is 0); methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, benzyltrimethoxysilane Naphthyltrimethoxysilane, methyltriacetoxysilane, (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, 3- (meth) acrylo Trifunctional silicon compounds such as cyclopropyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane (compounds in which n in the above general formula (c) is 1); dimethyldimethoxysilane, dimethyldiethoxysilane, Bifunctional silicon compounds such as diphenyldimethoxysilane, diphenyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, diacetoxydimethylsilane, diphenylsilanediol (the above general formula ( c) a compound in which n is 2); monofunctional silicon compounds such as trimethylmethoxysilane, trimethylethoxysilane, and trimethylsilanol (compounds in which n in the general formula (c) is 3). It is preferable to select at least one of tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane. In addition, if two or more types of silicon compounds (c) are appropriately selected (for example, selection of tetramethoxysilane and tetraethoxysilane), silica having two or more types of —OR groups can be prepared.

  In the condensation step, hydrolytic condensation of the silicon compound (c) is performed in a solvent. The concentration of the silicon compound (c) contained in this solvent is preferably 0.05 mol / L or more, and preferably 1.2 mol / L or less.

  As a solvent used for the hydrolysis condensation, a mixed solvent of water and one or more organic solvents is used. Here, it is preferable to use an organic solvent in which the silicon compound (c) and water are dissolved, and the catalyst described later is dissolved if necessary; or an organic solvent in which micelles of water and the catalyst are uniformly dispersed. Examples of such an organic solvent include alcohols such as methanol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, pentyl alcohol, ethylene glycol, propylene glycol, and 1,4-butanediol; acetone, methyl ethyl ketone Ketones such as ethyl acetate, paraffins such as isooctane and cyclohexane, ethers such as dioxane and diethyl ether, and aromatic hydrocarbons such as benzene and toluene. Among the organic solvents given as examples, it is preferable to select an alcohol, and methanol, ethanol, or propanol that can be present on the silica surface in a large amount by using a methoxy group, an ethoxy group, or a propoxy group as an -OR group is selected. It is more preferable. In addition, (1) when the silicon compound (c) having an alkoxy group is not selected, two or more alcohols are used as an organic solvent in this step in order to allow two or more types of alkoxy groups to exist on the surface of silica. (2) Although an organic solvent that is incompatible with water and the catalyst can be used, in this case, a surfactant is added to the solvent to uniformly disperse the water and the catalyst. Good.

  Adjusting the water concentration in the solvent may affect the shape and particle size of the silica to be prepared and the dissolved state of the silicon compound (c) in the solvent. The concentration of water in the solvent is usually 0.1 mol / L or more and 50 mol / L or less, and preferably 2 mol / L or more and 25 mol / L or less.

  If necessary, a catalyst for hydrolysis of the silicon compound (c) is used. The catalyst used at this time is ammonia; an ammonia generator such as urea that can generate ammonia by heating; an aliphatic such as methylamine, ethylamine, propylamine, n-butylamine, dimethylamine, dibutylamine, trimethylamine, and tributylamine. Basics such as amines; cycloaliphatic amines such as cyclohexylamine; aromatic amines such as benzylamine; quaternary ammonium hydroxides such as tetramethylammonium hydroxide; alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine; A catalyst may be used, and among these, ammonia, an aliphatic amine, an aromatic amine, and an alkanolamine that can easily control the particle diameter of silica are preferable. Further, from the viewpoint of easily reducing the catalyst residual amount in the obtained silica, ammonia having a low boiling point and an aliphatic amine having 1 to 4 carbon atoms are preferable, and ammonia excellent in promoting hydrolysis condensation is particularly preferable.

  Similar to the water concentration in the solvent, adjusting the catalyst concentration may affect the shape and particle size of the silica prepared and the dissolved state of the silicon compound (c) in the solvent. The catalyst concentration in the solvent usually exceeds 0 mol / L and is preferably 10 mol / L or less, and preferably 0.8 mol / L or more and 9.4 mol / L or less.

  When the condensation of the silicon compound (c) is performed, the silicon compound (c) is added to the solvent. The addition mode at this time is not particularly limited, and various methods can be employed. For example, (1) a method of adding the silicon compound (c) to the solvent in a lump and stirring, (2) a method of adding the silicon compound (c) to the solvent in several portions while stirring the solvent, (3) A method of continuously adding the silicon compound (c) while stirring the solvent, (4) an organic solvent containing the silicon compound (c) is prepared in advance, and the organic solvent is added to the above (1) to ( It is a method of adding by any method of 3).

  In addition, water and a catalyst to be used are also added to an organic solvent or a solvent (consisting of water and an organic solvent). The addition mode at this time is also not particularly limited, and various methods can be employed. For example, there are a method of adding all at once, a method of adding in several times, and a method of adding continuously.

  The temperature at which the hydrolysis condensation reaction of the silicon compound (c) is caused is preferably 0 ° C. or higher, preferably 10 ° C. or higher, and more preferably 20 ° C. or higher. Moreover, this temperature is good in it being 100 degrees C or less, it is preferable in it being 70 degrees C or less, and it is more preferable in it being 50 degrees C or less. If the temperature is 0 ° C. or higher, the hydrolytic condensation of the silicon compound (c) proceeds rapidly, and if it is 100 ° C. or lower, the condensation is easily controlled.

  The reaction time for the hydrolysis condensation is preferably 30 minutes or longer, preferably 1 hour or longer, and more preferably 2 hours or longer. Further, this time is preferably 100 hours or less, preferably 20 hours or less, and more preferably 10 hours or less. If the reaction time is 30 minutes or longer, the hydrolytic condensation of the silicon compound (c) proceeds sufficiently, and if it is 100 hours or shorter, the energy required for the heat treatment can be kept low.

  In order to cause hydrolytic condensation of the silicon compound (c) in the condensation step, the above-mentioned concentration, reaction temperature, and reaction time are preferred. The concentration of the silicon compound (c) is 0.05 mol / L or more and 1.2 mol / L or less, the concentration of water is 2 mol / L or more and 25 mol / L or less, and the concentration of the catalyst is 0.8 mol / L. As described above, if the reaction temperature is 20 ° C. or more and 50 ° C. or less and the reaction time is 2 hours or more and 10 hours or less, the dispersion in which silica having a uniform particle size is dispersed in a solvent. A liquid can be prepared.

  In addition, if it is necessary to remove the coarse silica and the aggregate of the silica in the obtained dispersion, it can be removed with a filter. If a filter having an opening larger than the average particle diameter of silica by 1 μm or more is used, coarse silica or the like can be removed. The filter may be a mesh having voids.

  In the concentration step subsequent to the condensation step, the solvent of the dispersion in which the silica obtained in the condensation step is dispersed is evaporated to concentrate the dispersion.

  In order to evaporate the solvent, a known evaporating means can be employed and is not particularly limited. For example, the dispersion may be charged into an evaporation kettle and the kettle is heated to evaporate the solvent in the dispersion. If the solvent can be evaporated, the pressure and temperature during the evaporation should be set appropriately. The pressure may be normal pressure, and the temperature will be determined according to the boiling point of the solvent.

  In the drying step, the solvent that could not be completely evaporated in the concentration step is evaporated. Here, the solvent is evaporated until a single silica is obtained.

  As a drying method for evaporating the solvent, it is preferable to select a method that can suppress aggregation, fusion, or adhesion between silicas. Examples of methods that can suppress this aggregation and the like include an airflow drying method and a spray drying method.

  When the airflow drying method is employed as the drying method, the crushing of the silica agglomerates is promoted by collision with the airflow and / or the inner wall of the drying device. Therefore, the amount of dried silica aggregates can be reduced. Either a direct heating method or an indirect heating method may be selected as a method of heating the dispersion by this airflow drying method. If the direct heating method is used, the solvent of the dispersion liquid can be evaporated by bringing the hot air generated by a hot air generator or the like into contact with the concentrated dispersion liquid. Crushing can be promoted. In the case of the indirect heating method, the solvent of the dispersion can be evaporated by heating the concentrated dispersion through the heat conducting material, and is circulated in the air stream introduced from the outside or inside. The air flow can promote dispersion of the dispersion and crushing of the silica aggregates.

  When the spray drying method is employed as the drying method, the dispersion of the dispersion and the crushing of the silica aggregates can be promoted by spraying the concentrated dispersion. In order to suppress silica agglomeration due to evaporation of the solvent of the dispersion, the spray drying method instantaneously heats the solvent of the dispersion to a high temperature, and maintains a low pressure in the drying system. A vacuum instantaneous drying method in which evacuation is performed to evaporate the solvent is preferable. Further, in order to sufficiently disintegrate the silica agglomerate, a tube composed of a straight portion where the solvent is evaporated and a bent portion is provided, and the tube is evacuated from the outlet side (the bent portion side) of the tube. An apparatus capable of supplying the dispersion liquid from the inlet side (straight portion side) of the tube is used. If such an apparatus is used, even if silica agglomeration due to solvent evaporation occurs, the agglomerate is crushed by collision of the silica agglomerate with the wall of the bent portion.

  Depending on the selected drying method, the silica obtained after evaporating the solvent may be agglomerated. In this case, you may perform the crushing process of the said aggregate separately.

  Through the above steps, silica can be obtained. As described above, silica is treated in the silylation step as necessary. In this silylation step, the silica surface is treated with the silylating agent described above.

  In the silylation step, the silylating agent may be sprayed onto the silica while stirring the silica in a known mixer such as a Henschel mixer. During the spraying, silica is placed in an atmosphere such as nitrogen. After spraying the silylating agent, the silica is heated. The heating temperature is preferably 100 ° C. or higher and 250 ° C. or lower, preferably 120 ° C. or higher and 230 ° C. or lower, more preferably 150 ° C. or higher and 200 ° C. or lower. The heating time is preferably 1 hour or more and 10 hours or less, preferably 2 hours or more and 8 hours or less, more preferably 3 hours or more and 6 hours or less.

  Next, the production form of the second silica will be described. The production form of the second silica is different from the first production form of silica only in the concentration step. The concentration process is as follows. In this concentration step, together with the transesterification described later, the alcohol charged in the reaction kettle and the solvent of the dispersion are evaporated to concentrate the dispersion.

  In the concentration step in the second production mode, an alcohol which is a kind of a compound having an —OR group is charged into an evaporating pot for concentrating the dispersion. The charged alcohol is involved in the transesterification reaction with the hydroxyl group and / or —OR group on the surface of the silica particles. That is, (1) the R group of the alcohol is replaced with a hydrogen atom in the hydroxyl group on the silica surface and / or a part of the R group in the -OR group on the surface, or (2) the -OR group of the alcohol, The hydroxyl group on the silica surface and / or a part of the —OR group on the same surface is substituted. Even if there is no such exchange, the alcohol charged in the evaporation pot may be adsorbed on the silica surface. Accordingly, one technical feature of the second production mode is that another —OR group can be present on the surface of silica where only one —OR group is present, depending on the alcohol selected.

  Monovalent aliphatic alcohol, monovalent saturated alicyclic alcohol, saturated aliphatic glycol, saturated alicyclic glycol, glycerin, sugar alcohol, aralkyl alcohol, saturated aliphatic glycol substituted with an aromatic ring, unsaturated aliphatic One or more alcohols selected from alcohols, unsaturated aliphatic alcohols substituted with aromatic rings, aryl alcohols, and the like can be used as alcohols in this concentration step without any particular limitation. However, when an alcohol is used as the organic solvent used in the condensation step, it is preferable to use an alcohol different from the alcohol related to the organic solvent so that two or more -OR groups are present on the silica surface. is there. For example, when methanol is used as the organic solvent in the condensation step, 1-butanol or benzyl alcohol is used.

  An example of the alcohol charged in the evaporation pot in the concentration step is as follows. Monovalent saturated aliphatic alcohols include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-methyl-1-propyl alcohol, 2-methyl-2-propyl alcohol, 1-butyl alcohol, 2 -Butyl alcohol, pentyl alcohol, 2-ethylhexyl alcohol, lauryl alcohol, stearyl alcohol; as monovalent saturated alicyclic alcohol, cyclohexanol; as saturated aliphatic glycol, ethylene glycol, propylene glycol, 1,3-propane Diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol 2,2-dimethyl- , 3-propanediol, 2,3-dimethyl-2,3-butanediol; saturated alicyclic glycols include cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4- Diol; Inositol, sorbitol, mannitol, xylitol as sugar alcohol; Benzyl alcohol, phenethyl alcohol, 1-phenyl-2-propanol, diphenylmethanol, triphenylmethanol; saturated aliphatic substituted with aromatic ring Examples of glycols include hydrobenzoin and benzpinacol; and examples of unsaturated aliphatic alcohols include vinyl alcohol, allyl alcohol, isopropenyl alcohol, 2-methyl-1-propenyl alcohol, 2-methylallyl alcohol, 2 The unsaturated aliphatic alcohol substituted with an aromatic ring, styryl alcohol, cinnamyl alcohol; butenyl alcohol, oleyl alcohol, linoleyl alcohol and the aryl alcohol, phenol; a.

  The method of charging the dispersion liquid and alcohol into the evaporation kettle is not particularly limited, and the dispersion liquid may be charged by any method. For example, (1) a method in which all of the alcohol and the dispersion are charged into the reaction kettle, (2) a method in which the alcohol is previously charged in the evaporation kettle, and then the dispersion is gradually introduced into the reaction kettle. And a method of gradually introducing alcohol into the reaction kettle after charging into the evaporating kettle.

  The reaction temperature and time are appropriately set according to the transesterification rate and the degree of alcohol evaporation. As a general tendency, the higher the reaction temperature, the more the transesterification reaction proceeds. Moreover, transesterification progresses, so that reaction time is long. The reaction temperature is adjusted by heating, and this temperature is preferably 50 ° C. or higher and 250 ° C. or lower, preferably 70 ° C. or higher and 230 ° C. or lower, more preferably 100 ° C. or higher and 200 ° C. or lower. On the other hand, the reaction time is generally from 1 hour to 10 hours, preferably from 2 hours to 8 hours, more preferably from 3 hours to 6 hours.

  Next, a production form of the third silica will be described. The third production form differs from the first production form in that alcohol is added to the concentrated dispersion (addition amount is appropriately determined) between the concentration step and the drying step. In the drying step, (1) the R group of the -OR group (alkoxy group) in the alcohol added to the dispersion, the hydrogen atom in the hydroxyl group on the silica surface and / or a part of the R group in the -OR group on the same surface, Or (2) the —OR group of the alcohol added to the dispersion and the hydroxyl group on the silica surface and / or a part of the —OR group on the same surface are substituted. Even if there is no such exchange, the alcohol added to the dispersion may be adsorbed on the silica surface. Accordingly, one technical feature of the third production mode is that, like the method for producing silica of the second production mode, another —OR group is formed on the surface of silica where only one —OR group is present, depending on the alcohol selected. Can also exist.

  The alcohol used in the third production form is not particularly limited. In other words, monovalent saturated alicyclic alcohol, saturated aliphatic glycol, saturated alicyclic glycol, glycerin, sugar alcohol, aralkyl alcohol, saturated aliphatic glycol substituted with aromatic ring, unsaturated aliphatic alcohol, aromatic ring One or more alcohols selected from substituted unsaturated aliphatic alcohols, aryl alcohols and the like can be used without any particular limitation. However, when an alcohol is used as the organic solvent used in the condensation step, it is preferable to use an alcohol different from the alcohol related to the organic solvent so that two or more -OR groups are present on the silica surface. is there. For example, when methanol is used as the organic solvent in the condensation step, 1-butanol or benzyl alcohol is used.

  Examples of alcohols that can be used in the third production mode are as follows. Monovalent saturated aliphatic alcohols include methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, 2-methyl-1-propyl alcohol, 2-methyl-2-propyl alcohol, 1-butyl alcohol, 2 -Butyl alcohol, pentyl alcohol, 2-ethylhexyl alcohol, lauryl alcohol, stearyl alcohol; as monovalent saturated alicyclic alcohol, cyclohexanol; as saturated aliphatic glycol, ethylene glycol, propylene glycol, 1,3-propane Diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol 2,2-dimethyl- , 3-propanediol, 2,3-dimethyl-2,3-butanediol; saturated alicyclic glycols include cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1,4- Diol; Inositol, sorbitol, mannitol, xylitol as sugar alcohol; Benzyl alcohol, phenethyl alcohol, 1-phenyl-2-propanol, diphenylmethanol, triphenylmethanol; saturated aliphatic substituted with aromatic ring Examples of glycols include hydrobenzoin and benzpinacol; and examples of unsaturated aliphatic alcohols include vinyl alcohol, allyl alcohol, isopropenyl alcohol, 2-methyl-1-propenyl alcohol, 2-methylallyl alcohol, 2 The unsaturated aliphatic alcohol substituted with an aromatic ring, styryl alcohol, cinnamyl alcohol; butenyl alcohol, oleyl alcohol, linoleyl alcohol and the aryl alcohol, phenol; a.

Organopolysiloxane coating:
The particles of the present invention can be obtained by coating the surface of the prepared silica with an organopolysiloxane.

  It is preferred to coat the organopolysiloxane on the silica using a known mixing device. That is, it is preferable to heat the silica after spraying the organopolysiloxane toward the silica while stirring the silica in the apparatus. When spraying, the inside of the apparatus for stirring the silica is preferably in an inert gas atmosphere such as nitrogen.

  As an apparatus for stirring silica, an apparatus capable of performing heating after spraying is preferable in order to suppress aggregation, fusion, and adhesion between the particles of the present invention. As such an apparatus, for example, there is a Henschel mixer (“FM / J type” manufactured by Mitsui Mining Co., Ltd.) equipped with a heating jacket.

  When spraying the organopolysiloxane, the organopolysiloxane may be sprayed directly onto the silica particles, but since many organopolysiloxanes have high viscosity, a solvent such as isopropyl alcohol is mixed with the organopolysiloxane. It is efficient to spray the one whose viscosity is lowered.

  After the spraying, the silica after the organopolysiloxane is sprayed is heated in order to increase the adhesion of the organopolysiloxane to the silica. The heating temperature at this time is preferably 100 ° C. or more and 300 ° C. or less, and preferably 150 ° C. or more and 200 ° C. or less. The heating time is preferably 10 minutes or longer, preferably 30 minutes or longer, and more preferably 1 hour or longer. In addition, in order to perform uniform heating of particles during heating, the above stirring is usually performed continuously. This is because the evaporation of the solvent mixed with the organopolysiloxane can be accelerated and the temperature of each silica can be made uniform.

  The particles of the present invention are obtained by coating with an organopolysiloxane. The particles may be aggregates. In that case, if necessary, the aggregate is crushed using a pulverizer (pulverizer) such as a jet mill or a ball mill. Since the agglomeration force in the aggregate of particles according to the present invention is weak, sufficient crushing of the aggregate can be easily performed. If it is necessary to perform classification of the particles according to the present invention together with crushing, for example, a jet pulverization classifier (“IDS-2 type” manufactured by Nippon Pneumatic) may be used.

(Use of particles)
The particles of the present invention can be applied to a wide range of applications that require silica particles. When used as an external additive that enhances the fluidity of the toner, the dispersibility of the particles is good, so that the fluidity of the toner can be improved.

  When the particles of the present invention are used as an external additive for toner, the toner usually has a colorant and a binder resin. As the colorant, dyes and pigments such as carbon black, cyan color, magenta color, yellow color and extender pigments can be used. Examples of the binder resin include styrenes such as styrene, chlorostyrene, and vinyl styrene; monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; Of α-methylene aliphatic monocarboxylic acid such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Ester; Vinyl ether such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; Homopolymer or copolymer of vinyl ketone such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropyl ketone, etc. Kill.

  Further, the toner may contain a magnetic substance such as ferrite, an electrification control agent, a conductivity regulator, an extender pigment, a reinforcing filler such as a fibrous substance, an antioxidant, and a release agent. .

  When the particles of the present invention are used as an external additive for toner, the amount of the particles used is appropriately set depending on the type of toner. When the toner is non-magnetic, the use amount of the particles of the present invention is less than 0.1 parts by mass with respect to 100 parts by mass of the toner. It is preferable that it is 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass. Further, when the toner is a magnetic toner containing a magnetic material, the use amount of the present invention is preferably set with respect to 100 parts by mass of the toner excluding the magnetic material.

  A known mixing means can be applied to mix the toner and the particles of the present invention. Examples of the apparatus used for the means include a Henschel mixer, a Nauter mixer, a ball mill, a V-type mixer, a turbula mixer, and a paint shaker.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.

  In each example and comparative example, the amount of —OR group, average particle size, coefficient of variation of particle size, hydrophobicity, charge amount, low dispersion particle size, high dispersion particle size, and content of impurity elements are as follows. Calculated.

(-OR group amount on silica surface)
1 g of sample silica and 50 ml of 0.05 N NaOH aqueous solution were mixed and then stirred at room temperature for 10 hours to obtain a suspension. This suspension was centrifuged at 1 × 10 ⁵ G or more for 60 minutes, and the supernatant of this solution was collected. The alkoxy group in the supernatant was quantitatively analyzed using a gas chromatograph equipped with a flame ionization detector, and the —OR group amount (alkoxy group amount) present on the surface of 1 g of sample silica was calculated from the result.

(Average particle size of primary particles, coefficient of variation)
Using SEM (Hitachi, Ltd. scanning electron microscope “S-3500N”), we randomly photographed five sample observation images at about 10,000 magnifications to confirm about 50 to 100 sample silica. The diameter of the primary particle of the sample that can be confirmed from the photographed image was randomly measured. From this measurement value, the average particle size was calculated. In addition, the average particle diameter and the standard deviation of the particle diameter were applied to the following equation to obtain the coefficient of variation of the particle diameter.
Variation coefficient of particle diameter (%) = standard deviation of primary particle diameter / average particle diameter × 100

(Hydrophobicity)
50 cc of water was put into a 200 cc glass beaker with a stirrer placed at the bottom, and 0.2 g of sample particles were placed on the water surface, and then the stirrer was gently rotated. Thereafter, the tip of the burette was inserted into the water in the beaker, and methanol was gradually introduced into the water from this burette. This introduction was performed until it was visually confirmed that the water surface particles had completely sunk. Then, the degree of hydrophobicity was determined based on the following formula.

(Charge amount)
A mixture of 1 part by mass of sample particles and 100 parts by mass of iron powder having an average particle diameter of 100 μm as carrier particles was pulverized in an agate bowl for 5 minutes. The blowoff charge amount of 2 mg of this pulverized product was measured using a charge amount measuring device (“TB200” manufactured by Kyocera Chemical Co.). The measurement conditions here were such that the number of wire meshes was 500 mesh, the blow pressure was 0.06 kg, and the blow time was 30 seconds.

(Low dispersion particle size)
A mixed solution of 2 parts by mass of sample particles and 100 parts by mass of methanol was stirred for 20 minutes. About the dispersion liquid obtained by this stirring, it measured using the laser diffraction / scattering type particle size distribution measuring apparatus (LA-920 by Horiba, Ltd.). The arithmetic average value of the obtained volume-based particle size distribution was defined as the low dispersion particle size.

(Highly dispersed particle size)
The dispersion prepared in the same manner as the calculation of the low dispersion particle diameter was treated with an ultrasonic disperser for 10 minutes or more to highly disperse the sample particles in the dispersion. Thereafter, the arithmetic average value of the volume-based particle size distribution obtained using a laser diffraction / scattering particle size distribution measuring apparatus (LA-920 manufactured by Horiba, Ltd.) was used as the high dispersion particle size.

(Impurity content)
Each content of Na, K, Li, F, and Cl in the sample particles was measured. The content of each element of Na, K, and Li was analyzed by atomic absorption analysis of JIS K 0121. The content of each element of F and Cl was analyzed by an ion chromatograph of JIS K 0127.

Example 1
The particles of Example 1 were prepared according to the following condensation step, concentration step, drying step, coating step, and crushing / classifying step.

Condensation process:
A 50 L reactor equipped with a stirrer, a dropping device and a thermometer was charged with 17.6 kg of methanol and 3.55 kg of 25% by mass ammonia water, and the liquid temperature in the reactor was adjusted to 40 ± 0.5 ° C. The mixture was stirred for 5 hours. At this time, 11.2 kg of tetramethoxysilane and 2.65 kg of water were dropped into the reactor over 3 hours from the start of stirring. By the above operation, particulate silica was generated by hydrolytic condensation of tetramethoxysilane, and a liquid in which silica was dispersed in methanol was prepared. A small amount of silica was collected from this dispersion, dried, and based on SEM observation, the average particle diameter of silica and the coefficient of variation of the particle diameter were calculated (see Table 1 below for calculated values).

Concentration process:
Using an evaporator having a 30 L capacity evaporator equipped with a stirrer, a dripping port, a thermometer, and a heating medium heating function, and a condenser that condenses the vapor from the evaporator, the above condensation is performed in the following procedure. The dispersion obtained in the process was concentrated. First, 18 kg of n-butanol was charged in an evaporation kettle with an internal pressure of normal pressure, and the temperature of the heating medium was maintained at 120 ° C. while stirring the butanol, and the total amount of the dispersion was taken from the dripping port of the evaporating kettle over 4 hours. Was sent into the evaporation kettle. Next, after distilling methanol, water and ammonia in the evaporation kettle, the heating medium temperature was set to 160 ° C., the total distillate from the evaporation kettle was 35.3 kg, and the solid content concentration in the dispersion was When it became 25 mass%, cooling of the heat medium was started.

Drying process:
The concentrated dispersion liquid was air-dried using a spray drying apparatus (“CRUX system 8B type” manufactured by Hosokawa Micron Corporation) to obtain dry silica particles. The drying apparatus used is a stainless steel pipe having an inner diameter of 8 mm and a length of 8 m covered with a jacket to which heated steam is supplied, a supply pump for supplying the dispersion liquid concentrated at one end of the steel pipe, and other steel pipes. A powder collecting chamber connected to the end and provided with a bag filter for separating the dispersion medium vapor of silica and dispersion liquid and capable of reducing the internal pressure. In the steel pipe of this drying apparatus, the dispersion liquid is indirectly heated to evaporate the dispersion medium, and the dispersion of the dispersion liquid in the steel pipe is condensed by the air flow generated by reducing the pressure of the powder collection chamber in the steel pipe. Silica crushing is promoted. Silica that has passed through the steel pipe is collected by a bag filter, and the other dispersion medium vapor is condensed after passing through the bag filter and discharged outside the drying apparatus. In this example using this drying apparatus, the dispersion was dried under the following conditions: the operating pressure was 50 torr, the heating tube jacket temperature was 170 ° C., and the powder collection chamber temperature was 150 ° C. The total amount of the concentrated dispersion was 17.7 kg. Dried. About the obtained silica, the -OR group on the surface was quantified (refer to Table 1 below for the quantified value).

Coating process:
Methyl hydrogen silicone oil (hereinafter sometimes referred to as “MHSC”) which is an organopolysiloxane on the surface of dried silica in a 20 L Henschel mixer (FM20J type manufactured by Mitsui Mining Co., Ltd.) equipped with a heating jacket Was coated. The Henschel mixer used here is a container charged with silica or the like, a rotating stirring blade for stirring the inside of the container, and a deposit for scraping off the deposit on the inner wall around the inner wall of the container. A removal plate. The procedure for coating MHSC on the silica surface was as follows. First, 4 kg of silica is put into a room temperature container of a Henschel mixer, and 0.6 kg of MHSC (“KF-99” manufactured by Shin-Etsu Silicone) and 0.2 kg of isopropyl alcohol are continuously blown at 1 L / min. And sprayed onto the silica over 15 minutes. The rotating direction of the rotating stirring blades of the Henschel mixer was opposite to the rotating direction of the deposit removing plate. Next, after gradually raising the temperature of the silica to 140 ° C. after 1 hour, the temperature was maintained for 1 hour. Thereafter, the silica coated with MHSC was naturally cooled to room temperature, and then the silica was taken out of the Henschel mixer.

Crushing and classification process:
The silica coated with MHSC was pulverized and classified using a counter jet pulverizer (“Type: 100” manufactured by Hosokawa Micron Corporation, pulverization pressure: 6 g / cm ³ ). Obtained.

(Example 2)
The particles of this example were obtained by a method that differs only in the coating step in Example 1. The details of the coating process of this example are as follows. First, 4 kg of silica was charged into a normal temperature vessel of a Henschel mixer into which nitrogen gas was continuously blown at 1 L / min, and hexamethyldisilazane (hereinafter referred to as “HMDS”) manufactured by Shin-Etsu Silicone Co., Ltd., which is a silylating agent. 0.2 kg) was sprayed for 15 minutes. Thereafter, the temperature of silica was increased to 150 ° C. over 1 hour, and the temperature was maintained for 3 hours, and then the temperature in silica was cooled to 40 ° C. Next, after spraying a mixture of 0.2 kg of MHSC and 0.1 kg of isopropyl alcohol over 15 minutes toward silica, the temperature of silica is gradually raised to 140 ° C. after 1 hour, and the temperature is adjusted. Hold for 1 hour. Thereafter, the silica coated with MHSC was naturally cooled to room temperature, and then the particles were taken out of the Henschel mixer.

(Example 3)
Except for the different condensation steps, the particles of this example were obtained in the same manner as in Example 1. A reactor was charged with 11.75 kg of methanol and 3.40 kg of 28% by mass aqueous ammonia, and while adjusting the liquid temperature in the reactor to 25 ± 0.5 ° C. and stirring, 2.7 kg of tetramethoxysilane was added. It was added dropwise over 60 minutes. Next, after stirring was continued for 1 hour, 1.25 kg of 28 mass% aqueous ammonia was added all at once to the reactor, and then stirred for another hour. Thereafter, a mixed solution of 11.4 kg of tetramethoxysilane and 0.6 kg of methyltrimethoxysilane (hereinafter sometimes referred to as “MTMS”) was dropped into the reactor over 240 minutes. For MTMS, “KBM-13” manufactured by Shin-Etsu Silicone Co., Ltd. was used. Simultaneously with the dropwise addition of the mixed liquid such as tetramethoxysilane, a mixed liquid of 1.1 kg of 28 mass% aqueous ammonia solution and 0.5 kg of water was also dropped. After the dropwise addition, stirring was performed for 2 hours to obtain a dispersion of silica particles.

Example 4
The concentration step is performed as follows, and the particles of the present example are obtained in the same manner as in Example 1 except that the dispersion after the concentration step is added and stirred with alcohol, and the treatment target in the drying step is used. It was.

  In the concentration step in this example, first, a part (20 kg) of the dispersion was charged into the evaporation kettle, and the temperature of the heating medium was set to 120 ° C. while stirring the dispersion to evaporate methanol, water, and ammonia. . Next, after feeding the remainder of the dispersion into the evaporation kettle over 3 hours, when the total distillate from the evaporation kettle is 17.3 kg and the solid content concentration in the dispersion is 25% by mass, Cooling of the heating medium was started.

  In the addition of alcohol between the concentration step and the drying step, 3.5 kg of n-butanol was added and stirred.

(Example 5)
Particles of this example were obtained in the same manner as in Example 4 except that benzyl alcohol was used instead of n-butanol in the addition and stirring of the alcohol to the dispersion after the concentration step.

(Example 6)
The particles of Example 6 were obtained in the same manner as in Example 1 except that the steps from the condensation step to the coating step were as follows.

  First, in the condensation step, 24.75 kg of ethanol and 9.62 kg of 28% by mass ammonia water were charged into the reactor, and stirred for 5 hours while adjusting the liquid temperature in the reactor to 40 ± 0.5 ° C. At this time, 4.69 kg of tetraethoxysilane was dropped into the reactor over 1 hour from the start of stirring. By the above operation, particulate silica was generated by hydrolysis condensation of tetraethoxysilane, and a liquid in which silica was dispersed in ethanol was prepared.

  In the subsequent concentration step, a part (20 kg) of the dispersion was charged into the evaporation kettle, and the temperature of the heating medium was set to 120 ° C. while stirring the dispersion to evaporate ethanol, water, and ammonia. Next, after feeding the remainder of the dispersion into the evaporation kettle over 3 hours, when the total distillate from the evaporation kettle reached 33.6 kg and the solid content concentration in the dispersion reached 25% by mass, Cooling of the heating medium was started.

  To the dispersion obtained in the concentration step, 1.08 kg of octanol was added and stirred. This solution was dried in the same drying step as in Example 1. In the coating step, the silica obtained in the drying step was coated with organopolysiloxane. This coating step was the same as the coating step of Example 1 except that the amount of MHSC used was 0.15 kg and the amount of isopropyl alcohol used was 0.5 kg.

(Comparative Example 1)
The particles of this comparative example were obtained in the same manner as in Example 1 except that the coating step was omitted and the concentration step was as follows.

  In the concentration step of this comparative example, first, a part (20 kg) of the dispersion was charged into the evaporation kettle, and the temperature of the heating medium was set to 120 ° C. while stirring this dispersion to evaporate methanol, water, and ammonia. . Next, after feeding the remainder of the dispersion into the evaporation kettle over 3 hours, when the total distillate from the evaporation kettle is 17.3 kg and the solid content concentration in the dispersion is 25% by mass, Cooling of the heating medium was started.

(Comparative Example 2)
A dispersion is prepared in the same manner as in the condensation step of Example 1, this dispersion is treated in the same manner as in the concentration step in Comparative Example 1, and the concentrated dispersion is treated in the same manner as in the drying step in Example 1. Dried. The dried particulate silica was put into a crucible and fired at 900 ° C. The silica after the baking treatment was subjected to the same treatment as the coating step and the crushing / classifying step in Example 1 to obtain particles of this comparative example.

(Comparative Example 3)
Particles of this comparative example were obtained in the same manner as in Example 1 except that the concentration step was as follows. In the concentration step in this comparative example, first, a part (20 kg) of the dispersion was charged into the evaporation kettle, and the heat medium temperature was set to 120 ° C. while stirring the dispersion, thereby evaporating methanol, water, and ammonia. . Next, after feeding the remainder of the dispersion into the evaporation kettle over 3 hours, when the total distillate from the evaporation kettle is 17.3 kg and the solid content concentration in the dispersion is 25% by mass, Cooling of the heating medium was started.

(Comparative Example 4)
The commercially available fused silica particles were treated in the same manner as in the coating step and crushing / classifying step in Example 1 to obtain particles of this comparative example.

  The following Table 1 shows the —OR group amount of silica before coating with MHSC, the average particle size, and the coefficient of variation of the particle size, the degree of hydrophobicity, the charge amount, and the low dispersion particle size of the particles according to Examples and Comparative Examples. , High dispersion particle size, and impurity content.

The following can be confirmed from Table 1.
(1) The particles of Comparative Example 1 that were not coated with MHSC had a degree of hydrophobicity of zero, but the particles of Examples that were coated with MHSC all had a high degree of hydrophobicity.
(2) From the comparison of the low and high dispersion particle sizes of Examples 1 and 3-6 and Comparative Example 2 that differ only in the presence or absence of the -OR group, the particles of Examples 1 and 3-6 are more than the particles of Comparative Example 2 Dispersibility was excellent (the high dispersion particle size of Examples 3 and 6 was larger than that of the comparative example because the average particle size of the silica itself before MHSC coating was large).
(3) The reason why the dispersibility of the particles of Examples 1 to 6 in (2) was excellent was that two types of —OR groups on the silica surface existed. This can be confirmed from the fact that the low and high dispersion particle diameters of the particles of Comparative Example 3 having one kind of —OR group were larger than those of Comparative Example 2 unlike Examples 1-6.

Claims (10)

Two or more kinds of —OR groups (R represents a group selected from an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group) on the surface. Having silica,
Particles comprising an organopolysiloxane that coats the silica.   The R group of the -OR group is one or two or more selected from a chain alkyl group having 4 to 18 carbon atoms, a cyclic alkyl group, an aralkyl group, and a hydroxyalkyl group, and a chain structure having 1 to 3 carbon atoms. The particle according to claim 1, which is an alkyl group.   The particle according to claim 1 or 2, wherein the amount of each -OR group in the silica is 1.0 mass% or more and 15.0 mass% or less.   The particle according to any one of claims 1 to 3, wherein the silica is further surface-treated with a silylating agent.   The particle according to any one of claims 1 to 4, wherein an average particle diameter of the silica is 0.01 µm or more and 2 µm or less.   The particle according to claim 5, wherein a variation coefficient of the particle diameter of the silica is 10% or less.   The particle according to claim 1, wherein (highly dispersed particle diameter) / (silica average particle diameter) is 5.0 or less.   The particle according to any one of claims 1 to 7, wherein a coefficient of variation of the highly dispersed particle diameter is 30% or less. Two or more kinds of —OR groups (R represents a group selected from an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an aryl group) on the surface. Preparing a silica having,
And a step of coating the silica with an organopolysiloxane.   The method for producing particles according to claim 9, wherein in the coating of the organopolysiloxane, the organopolysiloxane is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of silica.