JP5341357B2 - Hollow silicone fine particles with controlled particle size and porosity distribution and method for producing the same - Google Patents

Description

  The present invention relates to hollow silicone fine particles having a controlled volume average particle size and porosity distribution and a method for producing the same.

  As a method for producing silica particles having a hollow structure, for example, an oil-in-water-in-oil (O / W / O type) emulsion is prepared using an aqueous solution containing an inorganic compound such as silicate, and an inorganic acid or the like is added thereto. A method of mixing and changing an inorganic compound into a water-insoluble precipitate (Patent Document 1), or a method of covering a core made of a material other than silica with silica and removing the core without destroying the silica shell (Patent Document 2) Patent Document 3) is known. However, these methods have a problem that only hollow silica particles having a wide particle size distribution and a large average particle size can be produced, and a problem that productivity is poor because of a long reaction time and many processes.

The present inventors previously proposed a method for producing hollow silicone fine particles obtained by removing core particles from core-shell particles obtained by coating core particles composed of organic polymer particles and / or organic solvents with silicone compounds. (Patent Document 4). However, even in such hollow silicone particles, in order to obtain higher quality particles, a technique for controlling the particle diameter and porosity more precisely is required.
JP-A 63-258642 Special Table 2000-500113 JP 2001-233611 A International Publication No. 2007/099814

  As the particle size becomes smaller, the allowable range of variation becomes smaller, making it more difficult to control the particle size and porosity. An object of the present invention is to provide hollow silicone-based fine particles in which the particle size and the porosity distribution of the particles are precisely controlled, and a method for producing the same.

  As a result of intensive studies in view of the above problems, the inventors of the present invention are hollow silicone fine particles having a layer made of a specific silicone compound in the outer shell portion and having at least one cavity inside, The present inventors have completed the present invention by finding hollow silicone fine particles having a feature in the diameter and the porosity distribution of the particles and a production method thereof.

That is, in the present invention, SiO _4/2 unit, RSiO _3/2 unit (wherein R represents a monovalent organic group having 1 to 24 carbon atoms), R ₂ SiO _2/2 unit (formula Wherein R is the same as described above), and R ₃ SiO _1/2 units (wherein R is the same as described above), and the ratio of RSiO _3/2 units is 50 mol%. A layer made of a silicone compound having the above (however, the total of SiO _4/2 units, RSiO _3/2 units, R ₂ SiO _2/2 units, R ₃ SiO _1/2 units is 100 mol%) , Hollow silicone fine particles having at least one cavity inside, the volume average particle diameter of the hollow silicone fine particles being less than 0.5 μm, and having a porosity that is more than ± 10% different from the average porosity Hollow silicone, characterized in that the proportion of fine particles is less than 30% of the total particles Relates to fine particles.

Furthermore, it is related with the manufacturing method of the said hollow silicone type microparticles | fine-particles which consists of following process (I)-process (III).
(I) Step of producing organic polymer particles (A) having a weight average molecular weight of less than 10,000 and a volume average particle size of less than 0.5 μm (II) SiO _4/2 units, RSiO in the presence of the organic polymer particles (A) _3/2 units (wherein R represents a monovalent organic group having 1 to 24 carbon atoms), R ₂ SiO _2/2 units (wherein R is as defined above), and R ₃ SiO _1/2 Units (wherein R is the same as above), and the proportion of RSiO _3/2 units is 50 mol% or more (however, SiO _4/2 units, RSiO _3/2 units, R ₂ SiO _2/2 units, R ₃ Step (III) for producing core-shell particles (C) by polymerizing the silicone-based compound (B) that is a total of SiO _1/2 units of 100 mol% (III) Organic polymer particles in the core-shell particles (C) Step of removing (A) A preferred embodiment is that the variation of the particle diameter of the organic polymer particles (A) Characterized in that (CV value) is less than 40%, related to the manufacturing process.

A preferred embodiment relates to the above production method, wherein the step (II) satisfies at least one of the following conditions.
The amount of the acid catalyst is 3 parts by weight or more, the continuous addition time of the silicone compound (B) is within 20 minutes, and the reaction temperature is 60 ° C. or more.

  The production method of the present invention provides hollow silicone fine particles whose particle diameter and porosity distribution are precisely controlled. The hollow silicone fine particles of the present invention are precisely controlled in particle size and porosity distribution, so that, for example, they are excellent in transparency and antireflection performance in the optical field, and in the flatness and dielectric properties of thin films in the electronic material field. It is excellent.

The present invention comprises SiO _4/2 units, RSiO _3/2 units, R ₂ SiO _2/2 units, and R ₃ SiO _1/2 units in the outer shell, and the proportion of RSiO _3/2 units is 50 mol% or more. A layer made of a silicone compound, having at least one cavity inside, the volume average particle diameter of the hollow silicone fine particles is less than 0.5 μm, and a difference of ± 10% or more from the average porosity Hollow silicone fine particles characterized in that the proportion of fine particles having a certain porosity is less than 30% of the total particles. Such a hollow silicone fine particle is an organic polymer characterized by having a weight average molecular weight of less than 10,000, a volume average particle size of less than 0.5 μm, and a particle size variation coefficient (CV value) of less than 40% as core particles. Using particles (A), in the presence of the organic polymer particles (A), SiO _4/2 units 0-50 mol%, RSiO _3/2 units (wherein R is the same as above) 50-100 mol %, R ₂ SiO _2/2 units (wherein R is the same as above) 0 to 50 mol%, and R ₃ SiO _1/2 units (wherein R is the same as above) 0 to 50 mol% By polymerizing the silicone compound (B) (however, the total of SiO _4/2 units, RSiO _3/2 units, R ₂ SiO _2/2 units, R ₃ SiO _1/2 units is 100 mol%) After producing the core-shell particles (C), the organic polymer particles in the core-shell particles (C) It can manufacture by removing (A).

  The organic polymer particles (A) used in the production method of the present invention are characterized by having a weight average molecular weight of less than 10,000 and a volume average particle diameter of less than 0.5 μm. The composition is not limited. For example, it may be a soft polymer represented by polybutyl acrylate, polybutadiene, butyl acrylate-butadiene copolymer, or the like, such as butyl acrylate-styrene copolymer, butyl acrylate. -Hard polymers such as acrylonitrile copolymer, butyl acrylate-styrene-acrylonitrile copolymer, and styrene-acrylonitrile copolymer can be used without any problem. Among these, a soft polymer is preferable from the viewpoint of removability in a later step.

  Further, a polymer using 50% by weight or more of butyl acrylate is preferable. Among them, polybutyl acrylate, butyl acrylate-butadiene copolymer butyl acrylate-styrene copolymer, butyl acrylate-acrylonitrile copolymer are preferable. A butyl acrylate-styrene-acrylonitrile copolymer is preferred. Polymers using 80% by weight or more of polybutyl acrylate are more preferable, and among these polymers, those exemplified above are more preferable. Of these polymers, polybutyl acrylate is most preferred.

  The production method of the organic polymer particles (A) of the present invention is not particularly limited, and known methods such as an emulsion polymerization method, a microsuspension polymerization method, a miniemulsion polymerization method, and an aqueous dispersion polymerization method can be used. Among these, it is particularly preferable to produce the emulsion by an emulsion polymerization method from the viewpoint of easy control of the particle diameter and suitability for industrial production.

  A radical polymerization initiator may be used for the polymerization of the organic polymer particles (A). Specific examples of the radical polymerization initiator include organic peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, t-butyl peroxyisopropyl carbonate, paramentane hydroperoxide, and persulfuric acid. Examples thereof include inorganic peroxides such as potassium and ammonium persulfate, and azo compounds such as 2,2′-azobisisobutyronitrile and 2,2′-azobis-2,4-dimethylvaleronitrile. For example, ferrous sulfate-sodium formaldehydesulfoxylate-ethylenediaminetetraacetic acid 2Na salt, ferrous sulfate-glucose-sodium pyrophosphate, ferrous sulfate-sodium pyrophosphate-sodium phosphate When the redox system is used, the polymerization can be completed efficiently even at a low polymerization temperature.

  The organic polymer particle (A) of the present invention is preferably a non-crosslinked polymer in consideration of the removal of the organic polymer performed in a later stage with an organic solvent. A lower molecular weight is preferred. Specifically, the weight average molecular weight is preferably less than 10,000, and more preferably less than 7000. In order to reduce the weight average molecular weight of the organic polymer particles (A), for example, use a suitable combination of various means such as use of a chain transfer agent, setting to a high polymerization temperature, and use of a large amount of initiator. Can do. As the chain transfer agent, t-dodecyl mercaptan is preferable. The amount of the chain transfer agent used is preferably 1 to 30 parts by weight per 100 parts by weight of the monomer.

  The lower limit of the weight average molecular weight of the organic polymer particles (A) is not particularly limited, but is about 500 from the viewpoint of the difficulty of synthesis. In addition, a weight average molecular weight can be measured by the analysis (polystyrene conversion) by gel permeation chromatography (GPC), for example.

  From the viewpoint that the hollow silicone-based particles have a uniform porosity, it is preferable that the particle size distribution of the organic polymer particles (A) is narrow. Specifically, the variation coefficient (CV value) of the particle diameter of the organic polymer particles (A) is preferably less than 40%, and more preferably less than 30%. When the particle diameter is distributed, a relatively large amount of the silicone compound (B) is coated on the small particles compared to the large particles, resulting in variation in the porosity of the final hollow silicone fine particles. A seed polymerization method can also be used to narrow the particle size distribution. The seed polymerization method is a polymerization method in which seed particles are charged and then a monomer as a growth component is added to perform polymerization to grow seed particles greatly. In addition, the volume average particle diameter of the organic polymer particles (A) and the core-shell particles (C) in a latex state can be obtained from a light scattering method or observation with an electron microscope. The volume average particle size and the particle size distribution can be measured, for example, by using MICROTRAC UPA manufactured by LEED & NORTHRU INSTRUMENTS.

  In the present invention, the particle diameter of the organic polymer particles (A) needs to be smaller than the particle diameter of the finally obtained hollow silicone fine particles.

  Generally, the larger the amount of emulsifier used during emulsion polymerization, the smaller the average particle size of the polymer obtained. However, if the amount of the emulsifier is too large, new particles having a small particle size may be generated during the polymerization, and the CV value of the particle size may increase. Therefore, in order to bring the particle size and particle size distribution of the organic polymer particles (A) of the present invention into the necessary ranges, the amount of emulsifier used is when the average particle size is 0.5 to 0.1 μm. Is preferably 2 parts by weight or less per 100 parts by weight of the organic polymer particles. When the average particle diameter is less than 0.1 μm, the amount is preferably 4 parts or less per 100 parts by weight of the organic polymer particles.

  In order to facilitate the removal of the organic polymer particles (A) in the subsequent steps, the organic polymer particles (A) used in the present invention are toluene, benzene, xylene, You may contain the organic solvent which does not melt | dissolve in water, such as n-hexane. The amount of the organic solvent used is preferably 0 to 99% by weight, more preferably 0 to 50% by weight, in 100% by weight of the organic polymer particles (A). If the amount of the organic solvent used is too large, it may be difficult to control the particle size distribution.

The silicone-based compound (B) serving as a covering portion in the core-shell particle (C) of the present invention comprises SiO _4/2 units, RSiO _3/2 units, R ₂ SiO _2/2 units, and R ₃ SiO _1/2 units. 1 unit selected from the group consisting of 2 units or more, and RSiO in 100 mol% in total of SiO _4/2 unit, RSiO _3/2 unit, R ₂ SiO _2/2 unit, and R ₃ SiO _1/2 unit The ratio of _3/2 units is 50 mol% or more.

  R in the formula is a monovalent organic group having 1 to 24 carbon atoms. Specific examples include methyl groups, ethyl groups, propyl groups, n-butyl groups, t-butyl groups, cyclohexyl groups and other alkyl groups; phenyl groups, benzyl groups, naphthyl groups and other aromatic groups; vinyl groups, allyl groups. Alkenyl groups such as γ-methacryloxypropyl group, γ-acryloxypropyl group, γ-mercaptopropyl group, γ-aminopropyl group, γ-glycidoxypropyl group, γ-isocyanatopropyl group, chloromethyl group, chloro And a group containing a hetero atom such as a propyl group, a trifluoromethyl group, and a pentafluoroethyl group. Of these, from the viewpoint that the obtained hollow silicone fine particles are excellent in affinity with organic solvents and resins, among them, an alkyl group having 1 to 4 carbon atoms, an aromatic group having 6 to 24 carbon atoms, vinyl, and the like. Group, an organic group having γ- (meth) acryloxypropyl group or SH group is preferable, methyl group, ethyl group, phenyl group, vinyl group, γ-methacryloxypropyl group, γ-acryloxypropyl group, γ-mercapto A propyl group is more preferred. A plurality of R may be the same or different. For example, an organic group having a small amount of vinyl group, γ- (meth) acryloxypropyl group or SH group for R, and a large amount of alkyl group or aromatic group may be selected.

Examples of the raw material of the SiO _4/2 unit include one or more selected from the group consisting of silicon tetrachloride, tetraalkoxysilane, water glass, and metal silicate. Specific examples of the tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and condensates thereof.

Examples of raw materials for RSiO _3/2 units include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, phenyltrimethoxysilane, and phenyltriethoxy. Examples thereof include silane, phenyltripropoxysilane, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

Examples of the raw material for the R ₂ SiO _2/2 unit include dimethyldimethoxysilane, diphenyldimethoxysilane, methylphenyldimethoxysilane, dimethyldiethoxysilane, diphenyldiethoxysilane, methylphenyldiethoxysilane, diethyldimethoxysilane, and ethylphenyldimethoxy. Silane, diethyldiethoxysilane, ethylphenyldiethoxysilane, etc., hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), In addition to cyclic compounds such as trimethyltriphenylcyclotrisiloxane, linear or branched organosiloxanes, γ-mercaptopropylmethyldimethoxysilane, γ- Taku Lilo propyl methyl dimethoxy silane, vinyl methyl dimethoxy silane and the like.

Examples of the raw material for the R ₃ SiO _1/2 unit include trimethylmethoxysilane, triphenylmethoxysilane, trimethylethoxysilane, dimethylphenylethoxysilane, methyldiphenylethoxysilane, triphenylethoxysilane, triethylmethoxysilane, triethylethoxysilane, and the like. Can be given.
These can be used suitably by combining 1 type or 2 types or more. In addition, the silicone type compound obtained by condensing alkoxysilanes may contain an unreacted alkoxy group and a hydroxyl group depending on the reaction rate. If necessary, the amount of remaining alkoxy groups and hydroxyl groups may be reduced by reacting with a silane coupling agent or the like, or another functional group may be introduced.

In the present invention, a small amount of R ₂ SiO _2/2 unit can be mixed when the hollow silicone fine particles are desired to have flexibility. The ratio of R ₂ SiO _2/2 units in the silicone compound (B) in the core-shell particles (C) is 50 mol% or less. It is preferably 20 mol% or less, and more preferably 10 mol% or less. If the ratio of R ₂ SiO _2/2 units exceeds 50 mol%, the final hollow silicone fine particles may become too soft and a problem may arise in shape retention. The lower limit of the ratio of R ₂ SiO _2/2 units in the silicone compound (B) is 0 mol%.

The ratio of RSiO _3/2 units in the silicone compound (B) in the production method of the present invention is 50 mol% or more, that is, 50 to 100 mol%. From the viewpoint of the stability of the particle size distribution of the core-shell particles, it is preferably 75 to 100 mol%, more preferably 85 to 100 mol%.

The proportion of SiO _4/2 units is 0 to 50 mol%, and from the viewpoint of shape retention of the hollow silicone fine particles, it is preferably 0 to 10 mol%. When the proportion of SiO _4/2 units exceeds 50 mol%, when hollow silicone fine particles are used as a coated substrate, the compatibility with the film-forming matrix decreases and the fine particles aggregate in the coated film. The transparency of the substrate may be greatly reduced.

The proportion of R ₃ SiO _1/2 units is 0 to 50 mol%. From the viewpoint of shape retention of the hollow silicone fine particles, 0 to 10 mol% is preferable.

  In the present invention, by optimizing the use amount and use ratio of the organic polymer particles (A) and the silicone compound (B), the particle size, particle size distribution, shell layer thickness, Size, porosity, etc. can be controlled. The weight ratio between the organic polymer particles (A) and the silicone compound (B) is not necessarily limited, but is preferably 2/98 to 95/5, and more preferably 4/96 to 55 /. 45 is more preferred. If the ratio is less than 2/98, the porosity of the final hollow silicone fine particles may be too low. On the other hand, if the ratio is greater than 95/5, the strength of the hollow silicone fine particles may be insufficient and may break during processing.

  The core-shell particles (C) of the present invention and the finally obtained hollow silicone fine particles have a volume average particle size of less than 0.5 μm. The volume average particle diameter is preferably less than 0.1 μm in optical applications and electronic materials applications where importance is placed on transparency and thin film formation. The lower limit of the volume average particle diameter is usually 0.001 μm or more.

  The porosity distribution of the finally obtained hollow silicone fine particles is greatly influenced by the particle size distribution of the core-shell particles (C), and the particle size distribution of the core-shell particles (C) is the particle size distribution of the organic polymer particles (A). It is greatly affected. By strictly controlling the particle size distribution of the organic polymer particles (A) as described above, the porosity distribution of the hollow silicone fine particles can be controlled.

  In order to measure the porosity distribution of hollow silicone fine particles, at least 30 particles are observed with a TEM to measure the outer diameter and inner diameter of the particles, and the porosity (the ratio of the volume of the internal cavity portion in the volume of the particles) ) Is averaged. Next, the ratio of the number of fine particles having a difference of ± 10% or more from the average porosity to the total number is obtained. It is essential that the proportion of fine particles having a porosity different by ± 10% or more from the average porosity is less than 30% of the total particles, preferably less than 25%, more preferably less than 20%. preferable.

In the present invention, for example, the emulsifier, the raw material of the SiO _4/2 unit, the raw material of the RSiO _3/2 unit, and the R ₂ SiO for water of 5 to 120 ° C. containing the organic polymer particles (A) and the acid catalyst. _The core-shell particles (C) coated with the silicone compound (B) can be obtained by adding an emulsion obtained by emulsifying a mixture of _2/2 units of raw material and water with a line mixer or homogenizer all at once or continuously. it can. The emulsified liquid may be added all at once or continuously. Although it takes a long time, it is preferable to employ continuous addition if importance is attached to the stability of the latex particles and the particle size distribution. If the acid catalyst is added before the addition of the emulsion and continuous addition is performed under conditions where hydrolysis and condensation proceed immediately, the core-shell particles grow large over time, and a narrow particle size distribution, as in normal seed polymerization. Can be obtained. When continuous addition for a relatively short time of 1 hour is performed, both relatively good productivity and a narrow particle size distribution can be achieved.

  Depending on the condensation reaction conditions of the above-mentioned silicone compound, the silicone compound is formed not in the surface of the organic polymer particles (A) but in part. Since the internally generated silicone compound lowers the porosity of the hollow silicone fine particles, the generation of the silicone compound inside must be prevented. This internal formation is presumed to be related to the rate of penetration / swelling / condensation reaction of the silicone compound into the organic polymer particles. Therefore, it is preferable to advance the condensation reaction before the penetration and swelling sufficiently proceed. Specifically, it is preferable to satisfy at least one of the following conditions (i) to (iii). (I) The amount of the acid catalyst per 100 parts by weight of the total amount of the organic polymer particles (A) and the silicone compound (B) is 3 parts by weight or more, and (ii) the continuous addition time of the silicone compound (B) is 20 minutes. (Iii) The reaction temperature is 60 ° C. or higher. When the amount of the acid catalyst is less than 3 parts by weight, the condensation reaction is slowed and the silicone compound tends to be easily generated inside the polymer particles. Even if the reaction temperature is lowered, the condensation reaction is slowed, and the silicone compound tends to be easily generated inside the polymer particles. It is presumed that if the addition time of the silicone compound is increased, the silicone compound sufficiently permeates and swells, making it difficult to form a coating layer on the surface of the organic polymer particles.

  As the emulsifier that can be used in the present invention, an anionic emulsifier and a nonionic emulsifier can be suitably used. Specific examples of the anionic emulsifier include sodium alkylbenzene sulfonate, sodium lauryl sulfonate, potassium oleate and the like, and sodium dodecylbenzene sulfonate is particularly preferably used. Specific examples of nonionic emulsifiers include polyoxyethylene nonylphenyl ether and polyoxyethylene lauryl ether.

  Examples of the acid catalyst that can be used in the present invention include sulfonic acids such as aliphatic sulfonic acid, aliphatic substituted benzenesulfonic acid, and aliphatic substituted naphthalenesulfonic acid, and mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid. Among these, aliphatic substituted benzenesulfonic acid is preferable and n-dodecylbenzenesulfonic acid is particularly preferable from the viewpoint of excellent emulsion stability of the organosiloxane.

  In the present invention, examples of the method for removing the organic polymer particles (A) from the core-shell particles (C) include a method using an organic solvent and a method using combustion. The organic solvent used to remove the organic polymer particles (A) in the core-shell particles (C) is a silicone compound (B) that dissolves the core organic polymer particles (A) and becomes a shell. Those which do not dissolve are preferred. Specific examples include toluene, benzene, xylene, n-hexane, acetone and the like.

  In the present invention, after removing the core, the silicone fine particles can be washed with an organic solvent. Specific examples of the organic solvent that can be used for washing include methanol and n-hexane.

  The hollow silicone fine particles of the present invention can be used for applications where general silicone fine particles are used, and also as a material having characteristics derived from a hollow structure (for example, low refractive index, low dielectric constant, low specific gravity, etc.) Or include pigments, dyes, fragrances, medicines, magnetic nanoparticles, etc. inside as high-functional materials, or use them as nanoparticles, transparent materials, etc. by utilizing the small particle size, Utilizing the fact that the particle size and porosity are uniform, it can be used as a filler or carrier. Specific examples of applications include anti-reflective coatings widely used in electrical products such as displays, optical products such as lenses, and building materials; inks used in general paints, electronic paper, polymerized toner, displays, etc .; plastics , Rubber, paint fillers; chromatographic fillers; semiconductors, multi-layer wiring for electrical circuits such as integrated circuits; wire grid polarizers used in liquid crystal displays and projectors; displays and lighting Organic EL diffusion plate materials used as semiconductors; semiconductor applications such as semiconductor nanoparticles, three-dimensional photonic crystals, electrophotographic photoreceptors, transfer belts, fixing belts; new cancer treatments using magnetic nanoparticles, drug delivery systems Medical applications such as colloidal gold and its modifications, transdermal absorption preparations, release control agents; solvents Use in hygiene materials such as pigment modifiers, moisture permeation control cloth materials, lightweight coated paper and paperboard, antibacterial, breathable and sustained release porous films; nanofiltration membranes, high-performance air filters, internal denseness Separation membrane applications such as anisotropic membranes with layers; titanium oxide environmental purification agents; cosmetics, light control materials, adsorbing materials, sound insulation materials, heat insulating materials, spacers, lightening agents, abrasives, lightening materials, Examples include shock buffering applications, vibration isolation applications, vibration suppression applications, and the like.

  The present invention will be specifically described based on examples, but the present invention is not limited thereto. Measurements and tests in the following examples and comparative examples were performed as follows.

[Volume average particle diameter and coefficient of variation of particle diameter (CV value)]
Organic polymer particles or core-shell particles were measured in a latex state. The volume average particle size (μm) and CV value (%) were measured by a light scattering method using MICROTRAC UPA manufactured by LEED & NORTHRUUP INSTRUMENTS as a measuring device.

[Weight average molecular weight of organic polymer]
The weight average molecular weight of the organic polymer was determined by conversion from a GPC measurement data using a calibration curve prepared with a polystyrene standard sample.

[Presence / absence of silicone compound in core particles]
The latex of the core-shell particles in a latex state was dissolved and cured in an epoxy resin, dyed with ruthenium, and observed by TEM. The presence or absence of a silicone compound in the core particles was determined. As an example, the TEM observation result of Example 5 is shown in FIG. 1, and the TEM observation result of Comparative Example 4 is shown in FIG.

[Variation in porosity of hollow silicone particles]
Silicone fine particles washed with a solvent were dispersed in isopropyl alcohol (IPA) to obtain a dispersion having a particle concentration of 5% by weight. The dispersion was mixed with a 5% by weight solution of the acrylic resin for film formation to form a coating film. This coating film was dyed with ruthenium and observed by TEM. The porosity was calculated by measuring the outer and inner diameters of the particles, and the difference between the porosity and the average porosity of each particle was determined. The case where the proportion of fine particles having a porosity different by ± 10% or more from the average porosity exceeds 50% of the total particles, C is 50-30%, and A is less than 30%. As an example, the TEM observation result of Example 5 is shown in FIG. 3, and the TEM observation result of Comparative Example 3 is shown in FIG.

(Example 1, Comparative Examples 1, 3, 5-6)
In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 400 parts by weight of water (total amount of water including various dilution water) and sodium dodecylbenzenesulfonate (SDBS) ) After 6 parts by weight (solid content) was taken and mixed, the temperature was raised to 50 ° C., and after the liquid temperature reached 50 ° C., nitrogen substitution was performed. Thereafter, a mixed solution of 10 parts by weight of butyl acrylate, 3 parts by weight of t-dodecyl mercaptan, and 0.01 parts by weight of paramentane hydroperoxide was added. After 30 minutes, add 0.002 parts by weight of ferrous sulfate (FeSO ₄ .7H ₂ O), 0.005 parts by weight of ethylenediaminetetraacetic acid 2Na salt, and 0.2 parts by weight of sodium formaldehydesulfoxylate. The polymerization was further continued for 1 hour.

  Thereafter, a mixed solution of 90 parts by weight of butyl acrylate, 27 parts by weight of t-dodecyl mercaptan, and 0.1 parts by weight of paramentane hydroperoxide was continuously added over 3 hours. Post-polymerization was carried out for 2 hours to obtain an organic polymer (P-1) latex. The volume average particle diameter of this organic polymer was 0.04 μm, the weight average molecular weight was 6000, and the CV value of the particle diameter was 50%.

  In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 500 parts by weight of water (total amount of water including various dilution waters), dodecylbenzenesulfonic acid (DBSA) The amounts shown in Table 1 and organic polymer (P-1) shown in Table 1 were charged. The pH at this time was 1.8. The temperature was raised to the temperature shown in Table 1, and nitrogen substitution was performed. Thereafter, a mixture of methyltrimethoxysilane (MTMS) shown in Table 1, the same amount of water as MTMS, and 0.5% by weight of MTMS corresponding to 0.5% by weight of sodium dodecylbenzenesulfonate (SDBS) was stirred with a homogenizer at 7000 rpm for 5 minutes. The obtained emulsion was added at the additional time shown in Table 1.

  In addition, the whole amount was added within 5 minutes in the batch addition, and the whole amount was added at a constant rate over 30 minutes in the continuous addition. After completion of the addition, stirring was continued for 5 hours, followed by cooling to 25 ° C. and allowing to stand for 20 hours to obtain latex-like core-shell particles. Table 1 shows the volume average particle diameter of the core-shell particles and the results of confirming the presence or absence of the silicone compound in the core particles.

  Subsequently, 50 parts by weight of acetone was first added to 100 parts by weight of latex-like core-shell particles and stirred for 5 minutes, and then 150 parts by weight of the remaining organic solvent was added and stirred for 25 minutes. After standing for 3 hours, it separated into a coagulated particle layer and a transparent supernatant layer. The solidified particle layer was isolated using a filter paper, and dispersed in 300 parts by weight of a mixed solvent of 70% by weight of methanol and 30% by weight of n-hexane. When this dispersion is allowed to stand for 3 hours, it is separated into a coagulated particle layer and a transparent supernatant layer. The coagulated particle layer was isolated using filter paper. Isopropyl alcohol was added to 5 g of the isolated hollow silicone fine particles to prepare a dispersion. Table 1 shows the results of determining the variation in the porosity of the hollow silicone fine particles.

  In Example 1, hollow particles with little variation in porosity were obtained. In Comparative Example 1 in which the organic polymer (P-1) was not used, non-hollow particles were obtained. In Comparative Example 3 in which the addition time of the silicone compound emulsion was increased, the variation in the void ratio of the hollow particles was large. In Comparative Example 5 in which the reaction temperature was lower than that in Comparative Example 3, and in Comparative Example 6 in which the addition time of the emulsion was made longer than that in Comparative Example 3, the variation in porosity was further larger than that in Comparative Example 3.

(Examples 2-3)
In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 300 parts by weight of water (total amount of water including various dilution waters), ferrous sulfate (FeSO ₄ 7H ₂ O) 0.002 part by weight, ethylenediaminetetraacetic acid 2Na salt 0.005 part by weight, sodium formaldehydesulfoxylate 0.2 part by weight and sodium dodecylbenzenesulfonate (SDBS) 12 parts by weight (solid Minutes), and the mixture was heated to 50 ° C. After the liquid temperature reached 50 ° C., nitrogen substitution was performed. Thereafter, a mixed solution of 100 parts by weight of butyl acrylate, 30 parts by weight of t-dodecyl mercaptan, and 0.1 parts by weight of paramentane hydroperoxide was continuously added over 3 hours. Furthermore, it was made to superpose | polymerize for 1 hour and the preliminary particle (S-1) was obtained.

In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 400 parts by weight of water (total amount of water including various dilution waters), ferrous sulfate (FeSO ₄ 7H ₂ O) 0.0016 part by weight, ethylenediaminetetraacetic acid 2Na salt 0.004 part by weight, 0.16 part by weight formaldehyde sulfoxylate sodium and preliminary particles (S-1) (solid content) After mixing, the temperature was raised to 50 ° C., and after the liquid temperature reached 50 ° C., nitrogen substitution was performed. Thereafter, a mixed solution of 80 parts by weight of butyl acrylate, 24 parts by weight of t-dodecyl mercaptan, and 0.08 parts by weight of paramentane hydroperoxide was continuously added over 3 hours. Polymerization was further performed for 1 hour to obtain an organic polymer (P-2). The volume average particle diameter of this organic polymer was 0.04 μm, the weight average molecular weight was 5000, and the CV value of the particle diameter was 25%.

  In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 500 parts by weight of water (total amount of water including various dilution waters), dodecylbenzenesulfonic acid (DBSA) The amounts shown in Table 1 and organic polymer (P-2) shown in Table 1 were charged. The pH at this time was 1.8. The temperature was raised to the temperature shown in Table 1, and nitrogen substitution was performed. Thereafter, a mixture of methyltrimethoxysilane (MTMS) shown in Table 1, the same amount of MTMS as water, and 0.5 wt% MTMS equivalent of sodium dodecylbenzenesulfonate (SDBS) was stirred with a homogenizer at 7000 rpm for 5 minutes. The obtained emulsion was added at the additional time shown in Table 1. Table 1 shows the volume average particle diameter of the core-shell particles and the results of confirming the presence or absence of the silicone compound in the core particles. Silicone fine particles were obtained in the same manner as in Example 1, and the evaluation results are shown in Table 1. Hollow particles with little variation in porosity were obtained.

Example 4
In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 300 parts by weight of water (total amount of water including various dilution waters), ferrous sulfate (FeSO ₄ 7H ₂ O) 0.002 part by weight, ethylenediaminetetraacetic acid 2Na salt 0.005 part by weight, sodium formaldehydesulfoxylate 0.2 part by weight and sodium dodecylbenzenesulfonate (SDBS) 12 parts by weight (solid Minutes), and the mixture was heated to 50 ° C. After the liquid temperature reached 50 ° C., nitrogen substitution was performed. Thereafter, a mixed solution of 100 parts by weight of butyl acrylate, 30 parts by weight of t-dodecyl mercaptan, and 0.1 parts by weight of paramentane hydroperoxide was continuously added over 3 hours. The polymer was further polymerized for 1 hour to obtain organic polymer (P-3) preliminary particles. The volume average particle diameter of this organic polymer was 0.02 μm, the weight average molecular weight was 5000, and the CV value of the particle diameter was 25%.

In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 500 parts by weight of water (total amount of water including various dilution waters), dodecylbenzenesulfonic acid (DBSA) The amounts shown in Table 1 and organic polymer (P-3) shown in Table 1 were charged. The pH at this time was 1.8. The temperature was raised to the temperature shown in Table 1, and nitrogen substitution was performed. Thereafter, a mixture of methyltrimethoxysilane (MTMS) shown in Table 1, the same amount of MTMS as water, and 0.5 wt% MTMS equivalent of sodium dodecylbenzenesulfonate (SDBS) was stirred with a homogenizer at 7000 rpm for 5 minutes. The obtained emulsion was added at the additional time shown in Table 1. Table 1 shows the volume average particle diameter of the core-shell particles and the results of confirming the presence or absence of the silicone compound in the core particles. Silicone fine particles were obtained in the same manner as in Example 1, and the evaluation results are shown in Table 1. Hollow particles with little variation in porosity were obtained.

(Example 5, Comparative Example 4)
In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 400 parts by weight of water (total amount of water including various dilution water) and sodium dodecylbenzenesulfonate (SDBS) ) After taking 1 part by weight (solid content) and mixing, the temperature was raised to 50 ° C., and after the liquid temperature reached 50 ° C., nitrogen substitution was performed. Thereafter, a mixed solution of 10 parts by weight of butyl acrylate, 3 parts by weight of t-dodecyl mercaptan, and 0.01 parts by weight of paramentane hydroperoxide was added. After 30 minutes, 0.002 parts by weight of ferrous sulfate (FeSO4 · 7H2O), 0.005 parts by weight of ethylenediaminetetraacetic acid · 2Na salt, and 0.2 parts by weight of sodium formaldehydesulfoxylate were added for another hour. Polymerized. Thereafter, a mixed solution of 90 parts by weight of butyl acrylate, 27 parts by weight of t-dodecyl mercaptan, and 0.1 parts by weight of paramentane hydroperoxide was continuously added over 3 hours. Post-polymerization was performed for 2 hours to obtain an organic polymer latex (P-4). The latex had a volume average particle size of 0.13 μm, a weight average molecular weight of 5000, and a particle size CV value of 25%.

In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 500 parts by weight of water (total amount of water including various dilution waters), dodecylbenzenesulfonic acid (DBSA) The amounts shown in Table 1 and the organic polymer (P-4) shown in Table 1 were charged. The pH at this time was 1.8. The temperature was raised to the temperature shown in Table 1, and nitrogen substitution was performed. Thereafter, a mixture of methyltrimethoxysilane (MTMS) shown in Table 1, the same amount of MTMS as water, and 0.5 wt% MTMS equivalent of sodium dodecylbenzenesulfonate (SDBS) was stirred with a homogenizer at 7000 rpm for 5 minutes. The obtained emulsion was added at the additional time shown in Table 1. Table 1 shows the volume average particle diameter of the core-shell particles and the results of confirming the presence or absence of the silicone compound in the core particles. Silicone fine particles were obtained in the same manner as in Example 1, and the evaluation results are shown in Table 1.
In Example 5, hollow particles with little variation in porosity were obtained, whereas in Comparative Example 4 in which the amount of the acid catalyst was reduced and the addition time of the silicone compound emulsion was increased, the variation in porosity was large.

(Comparative Example 2)
In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 400 parts by weight of water (total amount of water including various dilution water) and sodium dodecylbenzenesulfonate (SDBS) ) After 12 parts by weight (solid content) was taken and mixed, the temperature was raised to 50 ° C., and after the liquid temperature reached 50 ° C., nitrogen substitution was performed. Thereafter, a mixed solution of 10 parts by weight of butyl acrylate, 3 parts by weight of t-dodecyl mercaptan, and 0.01 parts by weight of paramentane hydroperoxide was added. After 30 minutes, 0.002 parts by weight of ferrous sulfate (FeSO4 · 7H2O), 0.005 parts by weight of ethylenediaminetetraacetic acid · 2Na salt, and 0.2 parts by weight of sodium formaldehydesulfoxylate were added for another hour. Polymerized. Thereafter, a mixed solution of 90 parts by weight of butyl acrylate, 27 parts by weight of t-dodecyl mercaptan, and 0.1 parts by weight of paramentane hydroperoxide was continuously added over 3 hours. Post-polymerization was performed for 2 hours to obtain an organic polymer latex (P-5). The latex had a volume average particle size of 0.02 μm, a weight average molecular weight of 5000, and a CV value of the particle size of 65%.

In a 5-neck flask equipped with a stirrer, reflux condenser, nitrogen inlet, monomer addition port, thermometer, 500 parts by weight of water (total amount of water including various dilution waters), dodecylbenzenesulfonic acid (DBSA) The amounts shown in Table 1 and the organic polymer (P-5) shown in Table 1 were charged. The pH at this time was 1.8. The temperature was raised to the temperature shown in Table 1, and nitrogen substitution was performed. Thereafter, a mixture of methyltrimethoxysilane (MTMS) shown in Table 1, the same amount of MTMS as water, and 0.5 wt% MTMS equivalent of sodium dodecylbenzenesulfonate (SDBS) was stirred with a homogenizer at 7000 rpm for 5 minutes. The obtained emulsion was added at the additional time shown in Table 1. Table 1 shows the volume average particle diameter of the core-shell particles and the results of confirming the presence or absence of the silicone compound in the core particles. Silicone fine particles were obtained in the same manner as in Example 1, and the evaluation results are shown in Table 1.
Since organic polymer particles having a small average particle size and a wide particle size distribution were used, the obtained hollow particles had a large variation in porosity.

It is a TEM photograph of the core-shell particle which does not have a silicone type compound in a core part. 4 is a TEM photograph of core-shell particles in which a silicone compound is partially present in a core part. It is a TEM photograph which shows that the porosity of the hollow silicone type microparticles | fine-particles in a film is comparatively uniform. It is a TEM photograph which shows that the porosity of the hollow silicone type microparticles | fine-particles in a film is not uniform.

Claims (3)

SiO _4/2 unit, RSiO _3/2 unit (wherein R represents a monovalent organic group having 1 to 24 carbon atoms), R ₂ SiO _2/2 unit (wherein R is And R ₃ SiO _1/2 units (wherein R is the same as above), and the proportion of RSiO _3/2 units is 50 mol% or more (however, SiO _{4 / 2} unit, RSiO _3/2 unit, R ₂ SiO _2/2 unit, R ₃ SiO _1/2 unit is 100 mol%), and has at least 1 inside. Hollow silicone fine particles having two cavities, the proportion of the fine particles having a volume average particle diameter of less than 0.5 μm and having a porosity that is more than ± 10% different from the average porosity. Less than 30% of the particles The hollow silicone particles and symptoms. The following steps (I) to (III) :
(I) Step of producing organic polymer particles (A) having a weight average molecular weight of less than 10,000 and a volume average particle diameter of less than 0.5 μm (II) SiO _4/2 units in the presence of the organic polymer particles (A), RSiO _3/2 units (wherein R represents a monovalent organic group having 1 to 24 carbon atoms), R ₂ SiO _2/2 units (wherein R is the same as above), and R ₃ SiO _1/2 Units (wherein R is the same as above), and the ratio of RSiO _3/2 units is 50 mol% or more (however, SiO _4/2 units, RSiO _3/2 units, R ₂ SiO _2/2 units, R ₃ Step (III) for producing core-shell particles (C) by polymerizing silicone compound (B) that is a total of SiO _1/2 units of 100 mol% (III) Organic polymer particles in core-shell particles (C) Step of removing (A)
Consists of
The step (II) has the following conditions:
Variation coefficient (CV value) of particle diameter of organic polymer particles (A) is less than 50%
3 parts by weight or more of acid catalyst
Continuous addition time of silicone compound (B) within 20 minutes
Reaction temperature is 60 ° C or higher
The method for producing hollow silicone fine particles according to claim 1, wherein at least three of them are satisfied. The production method according to claim 2, wherein the organic polymer particles (A) have a coefficient of variation (CV value) of particle diameter of less than 40%.