JP2010167410A - Method for manufacturing hollow particulate, hollow particulate obtained by this method and its dispersion, and antireflection film using the hollow particulate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing hollow particulates, which is efficient owing to a continuous flow system using a circulation type reactor and by which the hollow particulates can be stably manufactured without causing variation resulting from reaction amount change produced by a batch system. <P>SOLUTION: The method for manufacturing the hollow particulates includes a process for producing the particulates, in which emulsion obtained by dispersing a dispersion phase containing a polymerizable monomer and a core forming medium in a continuous phase is circulated in the passage of a circulation system reactor and in this circulation process, the polymerizable monomer is polymerized and the polymer of the polymerizable monomer constituting an outer shell incorporates the core forming medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing hollow fine particles using a flow-type reaction apparatus, hollow fine particles obtained thereby and a dispersion thereof, and an antireflection film using the hollow fine particles.

  In recent years, by reducing the size of the particles to nanometer size, it was possible to draw out characteristics that could not be expressed with conventional micrometer size particles or smaller molecules or atomic units. Attempts to apply. Nanostructured material technology that forms part of such nanotechnology is broadly divided into top-down technology and bottom-up technology. In recent years, attention has been focused on the latter bottom-up technology. For example, a structure is precisely constructed from atoms and molecules to form nanometer-size particles controlled to the desired characteristics. Research and development is underway.

  Then, attempts have been made to make hollow particles further hollowed out inside the nanoparticles produced by this bottom-up technology. For example, an example in which hollow fine particles of several tens of nanometers are prepared as silica-based fine particles is disclosed (see Patent Document 1). It is said that the silica fine particles can be contained in the coating and used as an antireflection film material.

  By the way, there is a microcapsule as a granular material having a hollow structure. Although the size of the microcapsule is large, it is not limited to the specific inorganic material as described above, and a capsule having an outer shell can be constituted by a wide variety of organic compounds. As an example of producing a microcapsule using a microchannel, it is disclosed that a microcapsule is obtained by a polymerization reaction of an isocyanate compound, an acrylate compound, or the like (see Patent Documents 2 to 5). Patent Documents 4 and 5 say that nanometer-sized capsules can also be produced, but none is specifically shown by Examples. In addition, from the capsule manufacturing principle disclosed here, the diameter of the capsule obtained is almost the same as the channel diameter of the microreactor, so it is difficult to make particles that are significantly smaller than the channel diameter. Nanometer-sized hollow fine particles in which the outer shell of the particles is made of an epoxy compound have been disclosed as being produced in a stirring tank without using a flow reactor (see Patent Document 6).

JP 2001-233611 A JP 2002-282678 A JP 2002-282679 A JP 2007-90306 A JP 2007-533798 A JP 2007-70484 A

  If the hollow fine particles are composed of a polymer such as an organic compound and can be stably manufactured while miniaturizing them to the nanometer size as required, a special interaction due to the interaction between the size effect of the particles and the effect of the hollow structure It is thought that it is possible to draw out the characteristics and make use of it in many applications. Specifically, it exhibits excellent performance in various items such as heat insulation, rigidity, light weight, optical characteristics, specificity as a reaction field in the internal space, etc., and is expected to be applied as a functional material in a wide range of fields Is done.

  The present invention is efficient by a continuous flow system using a flow-type reaction apparatus, and is a hollow that enables stable production without causing variations due to a change in the reaction amount that occurs by a batch system. It aims at providing the manufacturing method of microparticles | fine-particles. In addition, if necessary, the method for producing hollow microparticles, in which the microparticle size can be reduced to a nanometer size and various functions and properties can be imparted by using an organic compound as the outer shell constituent material, thereby It is an object of the present invention to provide a hollow fine particle to be obtained, a dispersion thereof, and an antireflection film using the hollow fine particle.

The above object has been achieved by the following means.
(1) An emulsified liquid in which a dispersed phase containing a polymerizable monomer and a core-forming medium is dispersed in a continuous phase is circulated through a flow path of a flow reactor, and the polymerizable monomer is polymerized in this flow process. A method for producing hollow fine particles, comprising: a step of producing fine particles in which the polymer of the polymerizable monomer constituting the outer shell encloses the core forming medium.
(2) The method for producing hollow fine particles according to (1), wherein the core forming medium in the outer shell is vaporized or vaporized and released.
(3) The method for producing hollow fine particles according to (1) or (2), wherein the fine particles have a volume average diameter (MV) of 100 nm or less.
(4) The method for producing hollow microparticles according to any one of (1) to (3), wherein the core-forming medium has a boiling point of 50 to 150 ° C. at 760 mmHg.
(5) The hollow microparticle according to any one of (1) to (4), wherein the core forming medium is a saturated hydrocarbon solvent or a solvent having a fluorine content of 50% by mass or more. Production method.
(6) The method for producing hollow fine particles according to any one of (1) to (5), wherein the dispersed phase of the emulsion further contains at least one radical polymerization initiator.
(7) The hollow according to any one of (1) to (6), wherein the dispersed phase of the emulsion further contains at least one kind of saturated hydrocarbon compound oil or fluorine compound oil. A method for producing fine particles.
(8) The method for producing hollow fine particles according to (6) or (7), wherein the radical polymerization initiator is a photo radical polymerization initiator.
(9) The method for producing hollow fine particles according to (8), wherein the photo radical polymerization initiator is a compound that absorbs ultraviolet rays of 300 to 400 nm to generate radicals.
(10) The method for producing hollow fine particles according to any one of (1) to (9), wherein the polymerizable monomer is a fluorine-containing monomer.
(11) The method for producing hollow microparticles according to any one of (1) to (10), wherein the emulsion is prepared by a microemulsion method.
(12) The volume average diameter (MV) of the emulsified particles forming the dispersed phase in the emulsion is 100 nm or less, and the hollow fine particles according to any one of (1) to (11) Production method.
(13) The hollow microparticle according to any one of (1) to (12), wherein the flow type reaction apparatus is irradiated with light by a light irradiation means, and the polymerizable monomer is polymerized by photo radical polymerization. Manufacturing method.
(14) Any one of (1) to (13), wherein the flow-type reaction apparatus has a flow path having an equivalent diameter of 1 mm or less, and an emulsion of the polymerizable monomer is introduced into the flow path. The manufacturing method of the hollow microparticle of description to term.
(15) The volume average particle size (MV) of the hollow fine particles is 10 to 60 nm, and the volume average particle size (MV) / number average particle size (MN) is 1.2 to 2.0. The method for producing hollow fine particles according to any one of (1) to (14).
(16) An average value of a ratio of a particle outer shell diameter to a particle inner pore diameter ([particle inner pore diameter] / [particle outer shell diameter]) of the hollow fine particles is 0.3 to 0.7. (1) The manufacturing method of the hollow microparticle of any one of (15).
(17) The method for producing hollow microparticles according to any one of (1) to (16), which is obtained as an aqueous dispersion containing the hollow microparticles.
(18) The method for producing hollow microparticles according to (17), wherein the aqueous dispersion is concentrated with an ultrafiltration membrane, and the concentrated liquid is dried under reduced pressure.
(19) The hollow fine particles obtained by the production method according to any one of (1) to (18), having a volume average diameter (MV) of 100 nm or less and having a hollow structure with a space inside.
(20) The haze value (haze value) of a hollow microparticle dispersed in a binder compound, coated on a glass substrate, and measured by an integrating sphere photoelectric photometry in a thin film having a thickness of 2 μm obtained through a drying step. ) Is 0.5% or less, The hollow fine particles as described in (19).
(21) Hollow fine particles are dispersed in a mixture of a fluorine-based monomer and a photopolymerization initiator and applied to a glass substrate, and a 100 μm-thick cured thin film obtained through the photopolymerization step is peeled off from the glass plate, and Abbe's refraction The hollow fine particles according to (19) or (20), wherein the refractive index when the refractive index at 25 ° C. is measured by a meter is 1.45 or less.
(22) An aqueous dispersion containing the hollow fine particles according to any one of (19) to (21) and an aqueous medium.
(23) An antireflection film having the hollow fine particles according to any one of (19) to (21).

According to the production method of the present invention, it is efficient by a continuous flow method using a flow-type reaction apparatus, and does not cause variations in quality and the like due to a change in reaction amount caused by a batch method, and stably. Hollow fine particles can be produced. Further, if necessary, the fine particle diameter can be reduced to a nanometer size, and various functions and characteristics can be imparted by using an organic compound as the outer shell constituent material.
Further, the hollow fine particles of the present invention can be applied to a wide range of fields and uses as having various functions and properties by enriching the types of substances used in combination with the fine particles using organic compounds as outer shell constituent materials. can do. Furthermore, the antireflection film of the present invention achieves low reflectivity, high hardness, and high scratch resistance, and can be made into a high-performance film according to required characteristics by combining the hollow fine particles or film components.

The present invention will be described in detail below.
In the method for producing hollow fine particles of the present invention, an emulsified liquid containing a polymerizable monomer and a core-forming medium having a boiling point of 50 to 150 ° C./760 mmHg or less in the dispersed phase is circulated through the flow path of the flow reactor. In this distribution process, the polymerizable monomer is polymerized.

<Emulsion>
The emulsion used as a raw material in the production method of the present invention is composed of a dispersed phase and a continuous phase (emulsion liquid medium) existing around the dispersed phase, and in this dispersed phase, at least one kind of polymerizable monomer and at least one A core forming medium having a boiling point of 50 to 150 ° C./760 mmHg or less. In the present invention, emulsification refers to the formation of a stable dispersion system by dispersing fine particles in a liquid (continuous phase).
It is preferable that the dispersed phase of the emulsion further contains at least one radical polymerization initiator. Moreover, you may contain saturated hydrocarbon compound oil or fluorine compound oil as a nonionic surfactant or a stabilizer of an emulsion. An embodiment for preparing a desired emulsion by mixing these emulsion components is not particularly limited. For example, a dispersed phase component solution forming the above dispersed phase and a continuous phase component solution forming the continuous phase are mixed. Can be prepared. As the continuous phase component solution, an aqueous medium alone or an aqueous medium containing a dispersion stabilizer such as a surfactant can be used. The method for preparing the emulsion at this time is not particularly limited, but it is preferably prepared by a microemulsion method, a phase inversion emulsification method or a D phase emulsification method described later, and more preferably prepared by a microemulsion method.

  Examples of the polymerizable monomer include addition polymerizable monomers (such as radical polymerizable monomers, cationic polymerizable monomers, and anionic polymerizable monomers), polycondensable monomers, polyaddition monomers, addition condensation monomers, or ring-opening polymerizable monomers. However, it is preferably an addition polymerizable monomer, more preferably a radical polymerizable monomer. Examples of the radical polymerizable monomer include (meth) acrylate-based, vinyl-based, and styrene-based monomers, and (meth) acrylate-based monomers having a high radical polymerization rate are particularly preferable. These polymerizable monomers may be those having only one polymerizable group in the molecule, or those having two or more polymerizable groups in the molecule (crosslinkability). It is important for the polymerizable monomer to be hydrophobic in order to obtain a stable emulsion, and the preferred range of the molecular weight is 200 to 1000, particularly preferably 250 to 700. In consideration of using excellent optical characteristics as a precision optical material such as an antireflection film, it is preferable to use a fluorine-containing monomer as the polymerizable monomer.

  Specific examples of (meth) acrylate monomers include ethyl acrylate, isooctyl acrylate, isononyl acrylate, isobornyl acrylate, isobutyl acrylate, cyclohexyl acrylate, lauryl acrylate, dicyclopentanyl acrylate, diacrylate acrylate Cyclopentenyl, dicyclopentenyloxyethyl acrylate, stearyl acrylate, methyl methacrylate, butyl methacrylate, tridecyl methacrylate, lauryl tridecyl methacrylate, stearyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate , T-butyl methacrylate, cetyl methacrylate-stearyl methacrylate, isodecyl methacrylate, isobornyl methacrylate, dicyclopentanyl methacrylate, Lauryl tacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dimethylol dicyclopentane diacrylate, trimethylolpropane triacrylate, ethylene dimethacrylate Glycol, 1,3-butylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonane dimethacrylate Examples include diol, 1,10-decanediol dimethacrylate, and trimethylolpropane trimethacrylate.

  The fluorine-based (meth) acrylate monomer is important in terms of fluorine content (the total amount of fluorine atoms in the molecular weight), and is preferably an acrylate or methacrylate-based monomer having a fluorine content of 20% by mass or more, and particularly preferably 35% by mass or more. Or a methacrylate monomer. Specifically, particularly preferable ones are 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol (fluorine content: 30.2% by mass), diacrylic acid Acid (1,2,3,3,4,4,5,5,6,6-decafluoro-1,2-cyclohexane) dimethanol (44.0% by mass), methacrylic acid 1H-1- (tri Fluoromethyl) trifluoroethyl (48.3% by mass), 2,2,3,3,4,4,4-heptafluorobutyl methacrylate (49.6% by mass), 1H, 1H, 5H methacrylate -Octafluoropentyl (50.6% by mass) or methacrylic acid 1H, 1H, 11H-perfluoroundecyl (63.3% by mass). The amount of the polymerizable monomer contained in the dispersed phase of the emulsion is not particularly limited, but is preferably 30 to 90% by mass. One or a plurality of polymerizable monomers may be used simultaneously.

  The core-forming medium is preferably a solvent having a boiling point of 50 to 150 ° C./760 mmHg, preferably volatile in the air at normal temperature and normal pressure (28 ° C., 1 atm), and is a gas at normal temperature. Liquids under pressure are also preferred. An example of the liquid that is liquid under normal temperature and which is preferably used in the production method of the present invention is carbon dioxide. Preferably, it is a liquid under normal temperature and normal pressure, and a solvent composed of a saturated hydrocarbon compound or a solvent composed of a compound having a fluorine content of 50% by mass or more. Particularly preferred is a solvent of 80 to 100 ° C./760 mmHg. By setting it to the above lower limit value or more, the obtained hollow fine particles can easily have a uniform particle size, and can have higher transparency. It can be set as a favorable emulsion by setting it as the said upper limit or less. In addition, even if the particle size and transparency are slightly reduced outside the above preferred range of the boiling point, they may be applied to some applications, or the components such as the polymerizable monomer and the conditions for vaporizing the core forming medium are appropriately determined. It is also possible to adjust the particle size and transparency by setting. Speaking of a specific solvent, a saturated hydrocarbon solvent having 5 to 10 carbon atoms or a solvent having 5 to 10 carbon atoms and a fluorine content of 50% by mass or more, more preferably 5 to 8 carbon atoms. A saturated hydrocarbon solvent or a solvent composed of a compound having 5 to 8 carbon atoms and a fluorine content of 50% by mass or more, specifically, cyclohexane, n-heptane, n-octane, 1H-perfluoroheptane (Fluorine content 77.0% by mass), perfluorooctane (77.0% by mass), Galvain (Galden [trade name]) or H-Galden (H-Galden [trade name]) of Solvay Solexis (50 mass% or more of the same), and the like. Among them, n-heptane, 1H-perfluoroheptane, H-Galdens and the like are preferable. The content of the core forming medium in the dispersed phase of the emulsion is not particularly limited, but is preferably 10 to 70% by mass, more preferably 20 to 40% by mass. One or more core forming media may be used at the same time.

The radical polymerization initiator is not particularly limited, but is preferably a photoradical polymerization initiator, and more preferably the photoradical polymerization initiator is a compound that absorbs 300 to 400 nm ultraviolet rays to generate radicals. As radical polymerization initiators, aromatic ketones, onium salt compounds, organic peroxides, thio compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, as disclosed in JP-A-2006-85049, Examples thereof include azinium compounds, metallocene compounds, active ester compounds, and compounds having a carbon halogen bond, among which aromatic ketones, ketoxime esters, or active esters are preferable. Particularly preferred are aromatic ketones. Specific examples of radical polymerization initiators for aromatic ketones include 2,2-dimethoxy-1,2-diphenylethane-1-one (IRGACURE 651 [trade name]), 1-hydroxy-cyclohexyl-phenyl-ketone. (IRGACURE 184 [trade name]), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (DAROCUR 1173 [trade name]), 1-hydroxy-cyclohexyl-phenyl-ketone + benzophenone (IRGACURE 500 [ Product name]), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one (IRGACURE)
2959 [trade name]), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (IRGACURE 907 [trade name]), 2-benzyl-2-dimethylamino-1 -(4-morpholinophenyl) -butanone-1 (IRGACURE 369 [trade name]), 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) Phenyl] -1-butanone (IRGACURE 379 [trade name]), bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (IRGACURE 819 [trade name]), or 2,4,6-trimethylbenzoyl- And diphenyl-phosphine oxide (IRGACURE TPO [trade name]). The content of the radical polymerization initiator in the dispersed phase of the emulsion is not particularly limited, but is preferably 0.1 to 5% by mass, particularly preferably 0.5 to 3% by mass. One or a plurality of polymerization initiators may be used simultaneously.

  The surfactant is not particularly limited, and examples thereof include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. Among them, when included in a dispersed phase, a nonionic surfactant is used. Preferably, a fluorosurfactant is particularly preferable. The surfactant is not limited to one type, and the above surfactants may be mixed and used, or the surfactant contained in the dispersed phase and the continuous phase may be different. Specific examples of preferable nonionic surfactants include, for example, a bridging surfactant (such as Briji 97 [trade name]) of US ICI, which is a saturated hydrocarbon group-substituted polyethylene alcohol surfactant, and a perfluoro group. Zonyl surfactants (Donyl FSO, Zonyl FSO-100, Zonyl FSN-100 [trade name], etc.) of DuPont, which are substituted polyethylene alcohols, or Novec surfactants of 3M having perfluorobutanesulfonic acid groups (Novec FC-4430, Novec FC-4432 [product name], etc.). The content of the surfactant in the emulsion is not particularly limited, but is preferably 0.5 to 5% by mass in the case of an ionic surfactant, and 1 to 20% in the case of a nonionic surfactant. % Is preferred. One or more surfactants may be used at the same time.

  The aqueous medium means water or a solution in which an organic solvent and / or an acid or a base is dissolved in water. Distilled water is preferable, and nonionic water is particularly preferable. Although content of the aqueous medium in an emulsion is not specifically limited, It is preferable that it is 50-90 mass%.

  The emulsion stabilizer is preferably a saturated hydrocarbon compound oil or a fluorine compound oil. This oil preferably has a boiling point of 300 ° C./760 mmHg or more, and is liquid paraffin, squalene, and fomblin Y, which is a perfluoro oil of Solvay Solxis, or fomblin Z ( Fomblin Z) and the like. Among them, LVAC 06/6, LVAC 14/6, HVAC 40/11 or HVAC 140/13 in Fomblin Ys, or Z-DOL in Fomblin Zs (2000, 2500) , 4000), Z-DOL TX, Z TETRADL or AM (2001, 3001), etc. (all are trade names). When using an emulsion stabilizer, the content of the emulsion stabilizer contained in the dispersed phase of the emulsion is not particularly limited, but is preferably 10 to 80% by mass with respect to the polymerization monomer.

  In the present invention, it is preferable to use a miniemulsion method, a microemulsion method, a D-phase emulsification method, a phase inversion emulsification method, or the like as an emulsion preparation method. These methods will be described below.

<Mini emulsion method>
The mini-emulsion method is a method of obtaining a stable emulsion by applying strong shearing force such as ultrasonic waves to the monomer dispersion system, subdividing the monomer oil droplets to 100 nm or less, and suppressing Ostwald ripening with the aid of hydrophobes. The conversion of each monomer oil droplet in the emulsion into polymer particles is called miniemulsion polymerization (see Prog. Polym. Sci., 27, 689-757 (2002)).

<Microemulsion method>
Microemulsions have two meanings. That is, when it means a thermodynamically stable isotropic one-component phase consisting of at least three components: an oily component, an aqueous component and a surfactant (in the narrow sense, a microemulsion), and usually thermodynamically unstable In the emulsion system, the particle system is small, so that it has a transparent or translucent appearance (broadly defined microemulsion). A method of synthesizing polymer particles by radical polymerization of such a microemulsion is called microemulsion polymerization.

  Whether the synthesized microemulsion is narrow or broad, whether a component diagram of the microemulsion belongs to a thermodynamically stable solubilization region when creating a phase diagram showing the relationship between the ratio of components used and temperature, etc. It depends on whether it belongs to a thermodynamically unstable region (two-phase region). A narrowly defined microemulsion using a solubilized region of a nonionic surfactant is very useful in that many oils can be stably solubilized with a small amount of surfactant. However, on the other hand, since the temperature range of the solubilized region is very narrow, it is difficult to take advantage of this advantage over a wide temperature range. For this reason, studies have been made to improve the temperature dependence by using a system in which an ionic surfactant having a low temperature dependence of the hydrophilic-lipophilic balance and a cosurfactant are combined. On the other hand, if the above-mentioned microemulsions in the broad sense that are thermodynamically unstable can be made sufficiently stable in practice, they can be used in a much wider temperature range than microemulsions in the narrow sense. There is sex. If a system that is relatively stable against changes in composition can be obtained, microemulsions in a broad sense are interesting from a practical viewpoint. From this point of view, research was made in the 1980s, and even in the thermodynamically unstable two-phase region below the solubilization limit temperature of the nonionic surfactant-oil-water system, surfactants and oils can be selected. It became possible to prepare a long-time stable microemulsion (see Yukagaku, Vol. 37, No. 11 (1988), p. 48-53). In the present invention, a method for preparing a microemulsion which is stable in this thermodynamically unstable region, that is, in a broad sense, is called a “two-phase region microemulsion method” (sometimes called a solubilization conversion method). The method of polymerizing it to synthesize polymer particles will be referred to as “two-phase region microemulsion polymerization”.

<D phase emulsification>
The D phase emulsification method means that instead of generating the D phase by controlling the temperature, the HLB of the nonionic surfactant is adjusted by adding a water-soluble polyhydric alcohol to form the D phase, and the oil phase is dispersed in this. This is a method for obtaining a fine emulsion (see, for example, Journal of Chemical Society of Japan, 1983, (10), pages 1399 to 1404). In the D phase emulsification method, for example, a D phase is first generated with an EO type nonionic surfactant and a polyhydric alcohol aqueous solution such as 1,3 butanediol, and the oil phase is added with stirring. When the oil phase is added beyond the limit of solubilization in the isotropic D phase, the system becomes cloudy and an O / D emulsion is formed, but the oil formation ratio is a predetermined concentration (for example, 70% by mass). The O / D emulsion becomes transparent gel. In order to obtain a fine emulsion, it is necessary to make the interfacial tension sufficiently low, but by making the continuous phase D phase, the interfacial tension with oil droplets can be continuously changed. As an appropriate range in which a stable gel emulsion is formed, an interfacial tension of 0.5 to 2.0 dyn / cm is preferable. When the composition approaches the critical point, the interfacial tension further decreases. Under such conditions, although fine droplets are generated, the coalescence speed is high, and the system immediately separates into two phases, an oil phase and a D phase. Therefore, a fine emulsion may not be obtained.

  Further, the D phase emulsification method will be described in detail, but the present invention is not construed as being limited thereto. For example, when the basic component of the emulsion is a surfactant / oil / water, polyhydric alcohol is preferably used as the fourth component in the D-phase emulsification, thereby forming a fine O / W emulsion. it can. In a specific D-phase emulsification process, an O / D gel emulsion is formed by first starting with a surfactant isotropic solution containing water and a polyhydric alcohol, and then dispersing the oil phase in this surfactant solution. Can be made. Next, it can be set as an O / W emulsion by adding a water phase to this gel emulsion. At this time, it is prepared from two steps, and (A) a colorless and transparent solution containing predetermined components can be obtained as (B) a colorless and transparent gel by adding oil thereto. (C) Water can be added to the gel obtained in (B) to form an emulsion. By passing this transparent gel state (B), an emulsion having a fine dispersed phase can be formed.

<Phase inversion emulsification method>
For phase inversion emulsification, prepare an emulsion of the opposite type to the target type and perform phase inversion when the critical point is reached by operations such as increasing the concentration of dispersoids, heating or cooling the temperature. A method for preparing a mold emulsion. For example, in order to obtain an O / W type emulsion, first, an oil phase mixture such as a raw material, a solvent, an emulsifier, particularly a polymer surfactant is prepared, and water is gradually added to the target type. This is a method of phase inversion to the target O / W type through an emulsion of the opposite type (W / O), and a good emulsion is formed. In this case, the stability of the emulsion is governed by the ratio of water to oil, the type and amount of emulsifier, the stirring method, the viscosity, the order of addition, etc., and in general, the viscosity increases as water is added and near the phase inversion point. Increases rapidly, and sufficient agitation is required near the phase inversion. Since a large amount of water is required, it is not suitable for the preparation of a thick emulsion. Further, when a W / O emulsion is prepared at a temperature higher than the phase inversion temperature and cooled to the phase inversion temperature or lower while stirring, phase inversion is performed to obtain the target O / W emulsion. In this case, since water is not added, a thick emulsion can be obtained, but stability becomes a problem when the phase inversion temperature is high.

  In the phase inversion emulsification method in the present invention, a continuous phase having no compatibility with a dispersed phase in which a core substance (gas, liquid, solid) that can be a core-forming medium is dispersed (or dissolved). It is preferable to add gradually. For example, when the dispersed phase is an organic phase (O phase) and the continuous phase is an aqueous phase (W phase), a W / O dispersion is initially formed, but with the addition amount of the W phase (O / W) / After passing through the O dispersion system, the phase inversion eventually becomes an O / W dispersion system, and when the dispersed phase is an aqueous phase (W phase) and the continuous phase is an organic phase (O phase), the phase is reversed. If, for example, a suspension polymerization method or a submerged drying method is carried out after the occurrence of this, hollow fine particles can be formed.

The following is mentioned as a preferable treatment in the formation of hollow fine particles by such a phase inversion emulsification method.
(1) The interface energy between the core material-dispersed shell material solution (dispersed phase) and the continuous aqueous phase is reduced as much as possible, and emulsified with low mechanical energy. Thereby, the detachment of the core substance is suppressed and a high content can be achieved.
(2) For (1), an appropriate surfactant is added, and an amphiphilic solvent that dissolves in the dispersed phase and the continuous phase is added. Interfacial energy is remarkably reduced by mass transfer between both phases of the solvent, and emulsion formation can be achieved in a state close to natural emulsification.
(3) By adjusting the addition speed of the continuous phase and the stirring speed at this time, the droplet diameter of the continuous phase can be arbitrarily changed and made uniform at the same time. Since the oil phase to be microcapsules is dispersed in the continuous phase droplets, the final particle size and uniformity of the microcapsules can be adjusted.

  A particularly preferable emulsification method in the present invention is a microemulsion method, and in particular, a broad sense microemulsion method in a thermodynamically unstable two-phase region is preferable.

<Pressurization>
In the production method of the present invention, the polymerization reaction of the polymerizable compound contained in the emulsion may be carried out in the flow path of the flow reaction apparatus under conditions where the inside of the flow path is pressurized. The flow type reaction apparatus and its flow path will be described in detail later, but pressurization in the flow path can be used when the emulsified liquid or the medium has a boiling point or higher. Alternatively, pressurization means such as a pressurization pump may be connected to the flow path in combination with or without combination with this pressurization by heating. Although the pressure in the flow path at the time of the said pressurization is not specifically limited, For example, it is preferable to set it as 0.5-50 MPa, and it is more preferable to set it as 1-10 MPa. When pressurizing by heating in the flow path as described above, this heating temperature, for example, 20 to 150 ° C is preferable, and 25 to 100 ° C is more preferable.

  Thus, according to the manufacturing method by the flow reaction apparatus of the present invention, the reaction can be performed by pressurizing to a predetermined pressure, and an effect peculiar to the pressurization reaction can be brought out. In addition, when performing the pressure reaction, it is possible to apply reaction conditions and reaction forms that are difficult if a device that requires a complicated and strong structure to maintain a sealed state such as an autoclave is used. That is, for example, it is difficult to autoclave to perform a photopolymerization reaction, but according to the present invention, a transparent substrate is applied to one side or both sides of a flow reactor as described later, without requiring a complicated mechanism or labor. A simple and efficient reaction can be realized. In addition, in an autoclave, it is not easy to even stir the inside of the reaction tank and it is difficult to obtain a uniform reaction state. However, according to the production method of the present invention, a uniform reaction field is created using a fine flow path. For example, if the laminar flow conditions are used, it is possible to realize a high diffusibility that cannot be achieved by a normal stirring operation.

<Supercritical fluid>
In the production method of the present invention, a material in a supercritical state such as carbon dioxide can be used as the core forming medium. In addition to the polymerization reaction in the flow path described above, the preparation of the liquid A and the mixing thereof with the liquid B are preferably performed under pressure.

  Supercritical fluids are generally high pressure, which can be advantageous in fine particle synthesis. Under high pressure, a reaction accompanied by a decrease in activation volume is advantageous, which is preferable because, for example, an effect of increasing the reaction rate or moving the equilibrium can be expected by simple thermal decomposition. In the production of fine particles by polymerization of an emulsion, it is preferable to prevent aggregation of the produced particles. Fine particles synthesized in the liquid phase may form a gas-liquid interface in the voids between the particles during the drying process, and may agglomerate tightly due to capillary force. On the other hand, utilizing the fact that the supercritical fluid is indistinguishable between the gas phase and the liquid phase and there is no gas-liquid interface, the liquid phase is generated after synthesizing fine particles in the supercritical fluid. By taking out the particles while controlling the temperature and pressure so as to avoid the conditions, aggregation of the particles can be prevented. In the production method of the present invention, when supercritical carbon dioxide is used as the core-forming medium, hollow fine particles can be produced simply by returning to normal pressure after polymerization. For example, it is not necessary to use a special volatile organic solvent. Environmental compatibility can be realized.

<Polymerization reaction>
In the production method of the present invention, the polymerization method of the polymerizable compound is not particularly limited, and for example, it can be performed by a heat polymerization method or a photopolymerization method. Among these, as described above, the photopolymerization method, which was difficult with conventional autoclaves, is preferable in that it can be suitably applied.

<In situ polymerization method>
In the production method of the present invention, it is preferable to polymerize a polymerizable compound by an in situ polymerization method. This in situ polymerization method is distinguished from the interfacial polymerization method in that the polymerizable compound serving as a reactant is supplied only from one of the inside and the outside. The polymer (polymer) formed by the polymerization becomes insoluble in the core material and the dispersion medium, and as a result, a capsule including the core (core) including the core forming medium is encapsulated. In this case, it is preferable to determine the reactant composition and the physical properties of the dispersion medium so that the polymer precipitates (deposits) only around the core material (interface with the dispersion medium).

<Removal of core forming medium>
In the production method of the present invention, as one embodiment thereof, the hollow core particles are obtained by evaporating the core-forming medium inside the fine particles after undergoing the polymerization step of the emulsion, and the boiling point of the core-forming medium in consideration of the efficiency of the vaporization. Is preferably 150 ° C./760 mmHg or less. Removal of the core-forming medium by vaporization can be performed under reduced pressure in the case of a solvent having a relatively high boiling point. At this time, if sudden pressure reduction may break the hollow fine particles, it is preferable to adjust the pressure appropriately. When a solvent having a low boiling point, such as supercritical carbon dioxide, is the core forming medium, the core forming medium inside the microparticles is vaporized or released by releasing the microparticles under pressurized conditions. Can do. At that time, if necessary, the pressure may be gradually returned to atmospheric pressure so as to prevent the hollow fine particles from being destroyed by rapidly returning to atmospheric pressure. In the embodiment in which the core-forming medium is vaporized and released, the polymer that normally forms the outer shell has sufficient confidentiality, but the gas molecules have fine pores that can pass sufficiently, through which the core-forming medium is provided. Can be removed. When the fine particle dispersion is dissolved in THF to form a uniform solution, purification can be performed using gel filtration (GPC). This method is preferable in preparing hollow fine particles because the inner-pore core-forming medium can be replaced with THF, which is a low-boiling solvent, simultaneously with purification.

<Fine particles>
In the production method of the present invention, the polymer obtained by the polymerization reaction constitutes the outer shell, and fine particles enclosing the core forming medium are generated therein. The particle size of the fine particles obtained at this time (in the present invention, the particle size means the particle diameter) is preferably such that the volume average particle size (Mv) measured by the dynamic light scattering method is 100 nm or less. More preferably, it is -70 nm, and it is especially preferable that it is 15-60 nm. As a method for measuring the particle size of the particles, a microscope method, a dynamic light scattering method, an electric resistance method, or the like can be used. Unless otherwise specified, the particle diameter in the present invention is a value measured by a dynamic light scattering method (device is Nanotrack UPA-EX150 [trade name] manufactured by Nikkiso Co., Ltd.) at a dispersion concentration of 0.2% by mass. . In the present invention, the hollow fine particles may have a single-layer structure or a two-layer structure. In addition, the polymer component constituting the outer shell may be one kind or two or more kinds, and there may be a state in which a substance other than the polymer constituting the outer shell is present in the inner pore space. The average molecular weight of the polymer forming the fine particles is 10,000 to 500,000, preferably 20,000 to 300,000, particularly preferably 50,000 to 200,000.

  In consideration of obtaining such micronized nanometer-sized hollow fine particles, the volume average particle size (MV) of the emulsified particles (liquid particles forming a dispersed phase) in the emulsion is 150 nm or less. It is preferably 12 to 80 nm, more preferably 20 to 70 nm. In the present invention, the particle diameter of the emulsified particles in the emulsified liquid is determined by a dynamic light scattering method unless otherwise specified (the instrument is Nanotrack UPA-EX150 [trade name] manufactured by Nikkiso Co., Ltd.). The measured value at.

  For the monodispersity of the fine particles, a value (MV / MN) obtained by dividing the volume average particle size (MV), which is an index thereof, by the number average particle size (MN), and the value is 1.1 to 3.0. It is preferable that it is 1.2 to 2.0.

  In the hollow fine particles obtained by the production method of the present invention, the ratio between the particle outer shell diameter dg (see FIG. 2) and the particle internal pore diameter dn (hereinafter sometimes referred to as “internal porosity”), that is, [particle internal pore diameter] ] Is divided by [particle outer shell diameter], and this average value is preferably 0.2 to 0.9, more preferably 0.3 to 0.7. In the present invention, the method for obtaining the internal porosity is as follows. The obtained hollow fine particles were measured with a transmission electron microscope (manufactured by JEOL Ltd., “JEM-1200EXII”), and the outer shell diameter and the inner pore diameter of 500 arbitrary particles were observed. (Dg) and the pore size (dn) in the particle, and dn / dg was the inside porosity.

  Further, in the TG-DTA measurement, it is possible to confirm the presence of the solvent to be included due to the temperature rise rate dependency. When heat is transferred from the outside to the particles, it takes time to transfer the heat into the produced polymer. However, when the rate of temperature rise is high, the solvent contained is released at once due to the temperature difference. Therefore, an endothermic peak is observed in the DTA measurement. On the other hand, when the rate of temperature rise is slow, the temperature is uniformly heated, so that the solvent contained therein is gradually released, and therefore no endothermic peak is observed in the DTA measurement. And there is a difference in DTA behavior. Also in the TG measurement, weight loss is observed in two steps in the former. Furthermore, since the solvent to be included exists in a constrained space, when the NMR measurement is performed, the solvent included is observed to deviate from the normal chemical shift, and the amount ratio generated from the charge ratio and the polymerization conversion rate of the monomer is calculated. It is also possible to calculate the average inclusion solvent amount.

  The hollow fine particles obtained by the production method of the present invention are obtained by dispersing this in a binder compound (preferably a polyvinyl alcohol-based binder or a terminal alcohol-based perfluoropolymer binder), spin-coating it on a glass substrate, and then drying it. In a thin film having a thickness of 2 μm, the haze value (haze value) when measured by an integrating sphere photoelectric photometry is preferably 0.5% or less, and preferably 0.01 to 0.40. More preferred. Here, the haze value (haze value) (Th) is a value obtained by dividing the scattered light transmittance (Td) of the thin film piece by the total light transmittance (Tt) and multiplying by 100, and the unit is expressed in%. . That is, Th (%) = Td / Tt × 100. A smaller value means less haze, ie, more transparency.

  The hollow fine particles obtained by the production method of the present invention are preferably made of a fluorine monomer polymer as the outer shell constituting material. More preferably, it is a crosslinkable fluorine monomer, specifically 1,8-bis (acryloyloxy) -2,2,3,3,4,4,5,5,6,6,7,7-dodeca. Fluorooctane, dimethacrylic acid 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol, diacrylic acid (1,2,3,3,4,4,5,5 , 6,6-decafluoro-1,2-cyclohexane) dimethanol and the like. The hollow fine particles whose outer shell is composed of a polymer of the fluorine-based monomer are dispersed in a mixture of this and a radical photopolymerization initiator (for example, 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184)) and applied to a glass substrate. When a 100 μm-thick thin film obtained through a polymerization process by ultraviolet irradiation is peeled off from a glass plate and measured for a refractive index at 25 ° C. with an Abbe refractometer (manufactured by Atago Co., Ltd.), the refractive index is 1 .45 or less is preferable, and 1.25 to 1.40 is more preferable.

  The refractive index of the hollow fine particles can also be measured by extrapolation. That is, a THF solution in which dipentaerythritol hexaacrylate (binder, abbreviated as DPHA) and IRGACURE 184 (photoinitiator) are dissolved in a GPC-purified hollow fine particle THF solution having a weight percentage ratio of DPHA to hollow fine particles of 50, 40 After mixing and concentrating to 30%, coating and drying on a quartz substrate, photopolymerization is performed, and film pressure measurement and refractive index measurement of the obtained film are reflection spectral film pressure gauge FE-3000 [trade name] manufactured by ATAGO. The refractive index of 100% hollow fine particles can be calculated from the extrapolation. At that time, the refractive index of the hollow fine particles is preferably 1.45 or less, and more preferably 1.25 to 1.40.

<Reactor>

In the present invention, it is preferable to perform polymerization in a flow process in a process under laminar flow or in a transient state located between laminar flow and turbulent flow. Laminar flow and turbulent flow are described by being distinguished by Reynolds number (Re) as follows.
Re <2300 laminar flow
Re> 4000 Turbulence 4000 ≧ Re ≧ 2300 Transient state (transition region)

  The reaction by the microreactor as described above has advantages different from the batch method using a tank or the like. That is, in the chemical reaction between the liquid phases, the reaction generally occurs when molecules meet at the interface of the reaction solution. Therefore, when the reaction is performed in a microspace (microchannel), the area of the interface becomes relatively large, The reaction efficiency increases significantly. In addition, as described above, the diffusion time of the molecule itself is proportional to the square of the distance. This means that as the scale is reduced, the reaction proceeds more easily by the diffusion of molecules in the circulation region without active mixing of the reaction solution. Also, in the micro space, since the scale is small, the flow is dominated by laminar flow, and the solutions are in a laminar flow state and are diffused and mixed with each other.

  By using the microreactor having the above-described features, it is possible to precisely control the reaction time and temperature between solutions as compared with the conventional batch system using a large volume tank or the like as a reaction field. In the case of the batch method, the reaction proceeds at the reaction contact surface at the initial stage of mixing, particularly between solutions with a high reaction rate, and the primary product generated by the reaction between the solutions continues to be reacted in the vessel. Therefore, there is a possibility that the product becomes non-uniform or agglomeration or precipitation occurs in the mixing container. On the other hand, according to the microreactor, the solution continuously circulates with almost no stagnation in the mixing container. Therefore, while the primary product generated by the reaction between the solutions stays in the mixing container, it continues. It is possible to suppress the reaction, and it is possible to take out a pure primary product that has been difficult to remove in the past.

  In addition, when a small amount of chemical substances produced by an experimental production facility is manufactured (scaled up) in a large amount by a large-scale production facility, a large-scale batch method is conventionally used. It took a great deal of labor and time to obtain reproducibility at the production facility, but this reproducibility can be achieved by parallelizing production lines using microrear coolers according to the required production volume. The labor and time for obtaining the potential can be greatly reduced. The microreactor can be produced by a normal method, for example, refer to paragraphs [0035] to [0040] of JP-A-2005-307154.

  The equivalent diameter of the flow path in the apparatus used in the production method of the present invention is preferably 10 mm or less, more preferably 1 mm or less, further preferably 10 μm to 1 mm, and more preferably 20 to 500 μm. Particularly preferred. The length of the channel is not particularly limited, but is preferably 1 mm or more and 10 m or less, more preferably 5 mm or more and 10 m or less, and particularly preferably 10 mm or more and 5 m or less. Regarding microreactors, there have been reports on devices aimed at improving reaction efficiency. For example, Japanese Patent Application Laid-Open Nos. 2003-210960, 2003-210963, and 2003-210959 describe micromixers, and these microdevices can also be used.

  In order to introduce and circulate a predetermined liquid into the flow path, it is preferable to use a liquid flow driving means, and more preferably to use a fluid control means. In particular, since the behavior of the fluid in the microchannel has a property different from that of the macroscale, it is preferable to employ a control method suitable for the microscale. The liquid drive system is classified into a continuous flow system and a droplet (liquid plug) system when classified into forms, and an electrical drive system and a pressure drive system when classified into drive forces. For further details on these methods, reference can be made to paragraphs [0041] to [0046] of JP-A-2005-307154, for example.

  In the production method of the present invention, the speed (flow rate) of the fluid flowing through the flow path is preferably 0.002 ml to 5000 ml / min, more preferably 0.003 ml to 500 ml / min, and 0.01 ml to It is more preferable to set it as 250 ml / min, and it is especially preferable to set it as 0.1 ml-100 ml / min.

  In the production method of the present invention, by obtaining hollow fine particles in a flow-type reaction apparatus, fine particles having a uniform particle size that cannot be obtained by forming particles in a flask are obtained. Further, if this flow reactor is numbered up (in parallel), it is possible to produce a large amount of fine particles and a dispersion thereof with high reproducibility.

  1 of FIG. 1 is an exploded perspective view schematically showing an example of a manufacturing apparatus of a preferred embodiment used in the manufacturing method of the present invention, and an enlarged partial sectional view taken along the line AA in the circle of FIG. Show. In the manufacturing apparatus of the present embodiment, the emulsion is supplied from the inlet 11. The reaction channel 3 can be irradiated with ultraviolet rays 14 by the light irradiation means 13 to allow the polymerization reaction to proceed. And the solution containing the product obtained by the polymerization reaction can be taken out from the collection port 12.

  In the microreactor 10 of this embodiment, the substrate 2 on which the flow path is formed and the substrate 1 on the light source side are bonded together. A method generally used as a method of pasting is a method in which a base tool (made of plastic or metal) for fixing a microreactor is produced and put between them and uniformly fastened with a bolt or the like. In the present embodiment, the substrate 2 has a mirror-finished surface, but it may be light transmissive or light opaque. The substrate 1 is made of a light transmissive material having a mirror-finished surface. The flow path 3 preferably has an equivalent diameter of 1 mm or less, but is produced by a microfabrication technique (such as a micro machining method, a micro electric discharge machining method, or a LIGA machining method). The flow path 3 is particularly preferably an equivalent diameter of 100 to 500 μm. Furthermore, the microreactor of the present embodiment can be heated and cooled. For example, the microreactor can be heated and cooled by being immersed in a warm bath or a refrigerant, heated or cooled by an external heating / cooling means such as a Peltier element, or a chiller. It may be heated and cooled by an external circulation heat exchange type apparatus. A method using a Peltier element is preferable. The temperature control range can be used without any problem as long as it is at or above the dew point, but humidity adjustment is necessary at or below the dew point. There is no limitation on the minimum temperature as long as the medium to be fed can maintain the viscosity that can be fed. Alternatively, a pressure relief valve can be installed at the outlet to pressurize the inside of the flow path. According to the microreactor of the present embodiment, there is an advantage that the photopolymerization reaction under the heating / cooling / pressurizing conditions can be realized without requiring complicated means as described above.

  FIG. 2 is a process explanatory diagram showing each process of forming hollow microparticles using the microreactor as described above as one embodiment of the production method of the present invention. In this embodiment, an emulsion prepared with a core forming medium, a polymerizable monomer, a radical photopolymerization initiator, a surfactant, water and the like is introduced into the microchannel 3 from the inlet 21. This introduction may be under pressure or under no pressure. The emulsified liquid introduced into the microchannel forms dispersed phase emulsified particles 24 dispersed in a continuous phase (water or the like) 22, and the emulsified particles comprise a core-forming medium, a polymerizable monomer, a photo radical initiator, and a surface activity. Formed with an agent. In FIG. 2, the surfactant 23 is schematically shown so as to surround the emulsified particles. In this embodiment, the emulsified liquid is prepared and then introduced into the flow path. However, each component may be introduced into the flow path simultaneously or sequentially to emulsify in the flow path.

  The emulsified liquid sent to the microchannel 3 which is a reaction channel is irradiated with ultraviolet rays 14 here. When the polymerizable monomer is polymerized in the polymerization step, an outer shell 25 made of this polymer is formed. The fine particles 26 mainly contain a core forming medium. Next, the fine particles 26 are exposed to a removal process (heating, decompression, heating / decompression treatment, etc.) of the core forming medium contained therein to become hollow fine particles 27 having internal pores 27a therein.

  In this embodiment, when a medium that forms a gas at room temperature, such as supercritical carbon dioxide, is used as the core forming medium, the polymer particles are merely released into the atmosphere to form hollow fine particles. It is preferable to return to atmospheric pressure.

  The radical photopolymerization initiator used in the present invention is preferably one that absorbs ultraviolet rays having a wavelength of 300 to 400 nm and generates radicals. At this time, the irradiation light 14 is within the range. As a light source serving as a means for generating ultraviolet rays in this range, a high-pressure mercury lamp (centered at 365 nm, 254 nm to 436 nm), Nd: YAG laser (355 nm), YAG laser excited OPO laser (300 to 400 nm), or ultraviolet light Light emitting diodes (UV-LEDs, commercially available at 285, 290, 310, 340 and 365 nm) can be used. In particular, the use of the UV-LED is extremely useful for reducing the size of the entire apparatus and reducing the photon cost, and can easily obtain light with higher monochromaticity than a lamp light source.

<Aqueous dispersion>
When hollow microparticles are taken out from the aqueous dispersion obtained by the production method of the present invention and used, the method is not particularly limited, but it is concentrated with a normal ultrafiltration membrane, and this concentrated solution is dried under reduced pressure. Is preferred. The concentration of the hollow fine particles in the aqueous dispersion is not particularly limited, but is preferably 10 to 70% by mass, for example, when prepared through the above production process. Moreover, when an aqueous dispersion melt | dissolves in THF as mentioned above, it can also refine | purify using gel filtration (GPC). However, since the concentration of the obtained THF solution is dilute, it is necessary to concentrate to the coating viscosity after mixing with the organic binder. For example, the solid content concentration of the organic binder and the hollow fine particles is desirably 10 to 50% by mass. If it is in this range, application is possible by adjusting the viscosity.

<Antireflection film, etc.>
The hollow fine particles obtained by the production method of the present invention and the aqueous dispersion containing the fine particles can be applied to a wide range of uses. For example, they can be used as an optical thin film as a film material, applied to a photographic photosensitive material, It can be used as a coating material for equipment. Especially, it can use as precision optical materials, such as an anti-reflective film, using the outstanding optical characteristic.

When the hollow fine particles of the present invention are used as an antireflection film material, the embodiment is not particularly limited, but the antireflection film can be produced by a general production method, and the structure thereof is the same as that of a normal antireflection film. Can be configured.
By the way, as a hollow fine particle capable of realizing a low refractive index of an antireflection film such as a liquid crystal display, a commercially available hollow silica having a refractive index (n) of 1.445 to a hollow ratio of 30% or more is used (n). Some are 1.3 or less. However, such hollow silica may not have a sufficient sealing property of the outer shell, and the voids are not completely closed, and the strength and antifouling property may be insufficient. Moreover, since hollow silica is an inorganic material, the affinity with a binder made of an organic compound tends to be insufficient.
On the other hand, according to the hollow fine particles of the present invention, the coating film can be made to have a refractive index as described above. The affinity with an organic compound or the like used as a medium (binder) can be improved. Furthermore, the polymer compound forming the outer shell is composed of a desired organic compound, and this polymer compound is further modified / modified to produce an optical thin film or the like as highly functional fine particles that have been difficult in the past. Has the advantage of being able to.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is limited to this and is not interpreted.
(Preparation Example 1)
<Preparation of emulsion>
In a flask equipped with a stirrer, 2.9 g of n-heptane (bp = 98 ° C.), 6.1 g of ethylene glycol dimethacrylate, 1.0 g of liquid paraffin (Kanto Chemical), 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184 [ Product name]) 0.2 g was added and stirred. Into that, 10.0 g of Brij97 [trade name] (Sigma Aldrich) was added, and then 80 g of distilled water was added. The mixture was heated to 95 ° C. with stirring, stirred at that temperature for 30 minutes, then cooled with ice and cooled to room temperature or lower. The reaction solution became cloudy when heated, but when cooled, it became an almost clear blue-white solution (emulsion). When the particle size is measured by a dynamic light scattering method (using Nanotrac UPA-EX150 [trade name] manufactured by Nikkiso Co., Ltd.), the average volume particle size (MV) is 12.6 nm and the monodispersity (MV / MN) is 1. .24.

<Polymerization reaction>
The above-described emulsified liquid was converted into the reaction apparatus 10 having the micro-channel shown in FIG. 1 (the channel 3 had a channel width of 500 μm, a channel depth of 200 μm, and a channel length of 50 cm. The substrate 1 was Pyrex. (Registered trademark) made of glass was used, and the substrate 2 was made of aluminum.) The solution was fed from the introduction port 11 with a syringe pump. The liquid feeding speed was 0.1 ml / min. As the light source 13, a handy cure HLR100T-2 [trade name] manufactured by Sen Special Light Source Co., Ltd. (uses a high-pressure mercury lamp. Maximum UV irradiation intensity is about 190 mW / cm ² (3.5 cm from the lamp tip)), Irradiation was about 3 cm away from the glass surface. The reactor 10 was cooled using a Peltier device and kept at 20 ° C. If the time that stays in the flow path is the irradiation time (= reaction time), the irradiation time is 74 seconds.

  The reaction solution discharged from the collection port 12 is received by the flask, and the sample obtained in the first 10 minutes is discarded as the first distillation, and then sent and reacted for 100 minutes and collected in the flask. 10 ml of 1> was obtained. When the particle diameter of the fine particles in the obtained <Sample 1> was measured by Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd., the volume average diameter (MV) was 16.5 nm and the monodispersity (MV / MN) was 1. 21.

(Preparation Examples 2 to 10)
The emulsion and samples 2 to 10 were prepared in the same manner as in Preparation Example 1 except that the polymerizable monomer, core-forming medium, oil, photoradical polymerization initiator, and surfactant were changed to the amounts shown in Table 1 and the amounts used. A polymer particle liquid was synthesized. The volume average particle diameter and monodispersity of the obtained sample are shown in Table 1.

(Preparation Example c1)
<Sample c1> was produced in exactly the same manner except that the core forming medium of Preparation Example 1 was replaced with decane having a high boiling point (bp = 189 to 191 ° C.) in the same amount. In the operation of preparing the emulsion, the emulsion was low in stability and separated into two phases when left as it was. In the polymerization operation, polymerization occurred in a state of two-phase separation, and particles were not formed.
(Preparation Example c2)
An emulsion is prepared in the same manner as in Preparation Example 1, and the emulsion is used as a flask-type photoreaction apparatus (reaction vessel VG100 [trade name] (capacity: about 100 ml) manufactured by Global Top Chemical Co., Ltd.), light source : High pressure mercury lamp HL100CH-4 [product name], lamp jacket: JW-1Q.G [product name], power source: HB100P-1 [product name]), and polymerization is almost completed for about 10 minutes (microchannel) The photopolymerization reaction was carried out with stirring. This was designated as comparative sample c2. The results are shown in Table 1.

(Preparation Examples c3 to c5)
An emulsion was prepared in the same manner as in Preparation Example 5, Preparation Example 8, and Preparation Example 10, and a photopolymerization reaction was performed in the same manner as in Preparation Example c2. These were designated as comparative samples c3 to c5. The results are shown in Table 1.

  As can be seen from the results in Table 1, it can be seen that in the case of a sample reacted with an emulsified liquid containing a specific material in the distribution process, polymer fine particles having a particle diameter of 100 nm or less are obtained.

Example 1
(1) Preparation of Hollow Fine Particles Samples 1 to 10 of the present invention and comparative samples c2 to c5 shown in Table 1 were prepared by ultrafiltration membrane (UHP-62K [trade name] manufactured by Advantech Toyo Co., Ltd., molecular weight cut off 50,000). ), Then concentrate as much as possible, freeze-dry the concentrated solution, and then gradually raise the degree of vacuum from room temperature to heating (50 ° C. or lower) and remove the core-forming medium by vacuum drying to remove hollow fine particles Samples 101 to 110 of the present invention and comparative samples c02 to c05 were obtained. Part of the obtained sample was made into 1 wt% aqueous dispersion, and volume average particle size (MV) and monodispersion of hollow fine particles by dynamic light scattering method (using Nanotrac UPA-EX150 [trade name] manufactured by Nikkiso Co., Ltd.) The degree (MV / MN) was measured. The results are shown in Table 2.

(2) Average value of particle pore diameter (dn) / particle outer shell diameter (dg) The hollow microparticles of Samples 101 to 110 and Samples c02 to c05 of the present invention were measured using a transmission electron microscope (manufactured by JEOL Ltd., “JEM- 1200EXII "[trade name]), the average value of the internal porosity (particle internal pore diameter / particle outer shell diameter) of the hollow fine particles was measured by the method described above. The results are shown in Table 2.

(3) Haze value measurement of thin film piece Using the hollow dispersion samples 101 to 110 of the present invention and the aqueous dispersions of samples c02 to c05, thin film pieces were prepared through the following operations 1 to 4.
1. The concentration of the hollow fine particle aqueous dispersion is adjusted to 5% by mass using distilled water (dispersion A).
2. Polyvinyl alcohol (Kuraray Poval PVA205 [trade name]) is added to the dispersion A in a weight ratio of 10% and sufficiently stirred (dispersion B).
3. Dispersion B is coated on a transparent glass with a bar coater so as to have a film thickness of 2 ± 0.2 μm.
Dry at 4.50 ° C. for 3 hours.

  The haze value (haze value) of the produced thin film piece was measured using an integrating sphere photoelectric photometer (NDH2000 [trade name] manufactured by Nippon Denshoku Industries Co., Ltd.). The results are shown in Table 2.

(4) Refractive index measurement of cured film 20 g of each of the hollow fine particles of Samples 101 to 110 and Samples c02 to c05 of the present invention and dimethacrylic acid 2,2,3,3,4,4,5,5,6, A liquid polymerizable composition was prepared by mixing 100 g of 6-decafluoroheptane and 5 g of 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184 [trade name]). Each composition was coated on a glass plate with a bar coater and polymerized with an ultraviolet irradiation device to obtain cured products having a film thickness of 100 μm (film samples 101 to 110 and comparative film samples c02 to c05). The cured product was peeled from the glass plate, and the refractive index at 25 ° C. was measured with an Abbe refractometer (manufactured by Atago Co., Ltd.). The results are shown in Table 2.

  From the results shown in Table 2, the thin film piece samples 101 to 110 produced from the hollow fine particle samples 1 to 10 of the present invention show a smaller haze value than that of the comparative samples c01 to c05, and the difference in transparency is also visually. It was clear. Moreover, it turns out that the refractive index of the cured film samples 1-10 of this invention is smaller than the thing of a comparative example.

(Example 2) Production of antireflection film <Preparation of curable resin composition>
30 g of each of the hollow microparticles of Samples 101 to 110 of the present invention and Comparative Samples c02 to c05 were dissolved in 70 g of methyl ethyl ketone to prepare a 30% by mass solution, and then filtered through a polytetrafluoroethylene filter having a pore size of 0.25 μm. Then, 5 g of radical photopolymerization initiator Irgacure 907 (manufactured by Ciba SC) was added thereto to prepare a curable resin composition.

(Creation of antireflection film)
About the adjusted curable resin composition, an antireflection film was coated on a transparent support by the following operation to produce an antireflection film.

(Preparation of titanium dioxide dispersion)
Titanium dioxide fine particles having a core / shell structure (TTO-55B [trade name], shell material: 9% by mass of the whole alumina particles, trade name, manufactured by Ishihara Sangyo Co., Ltd.), 30 g of poly (1H, 1H, 5H-octafluoro Pentyl acrylate (4.5 g), commercially available cationic monomer (DMAEA, trade name, manufactured by Kojin Co., Ltd.) (0.3 g) and cyclohexanone (65.2 g) are dispersed by a sand grinder mill to disperse titanium dioxide having a weight average diameter of 53 nm. A product was prepared.

(Preparation of coating solution for medium refractive index layer)
18.08 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA (trade name), manufactured by Nippon Kayaku Co., Ltd.) and a photopolymerization initiator (IRGACURE) were added to 49.60 g of the titanium dioxide dispersion. 907 [trade name], Ciba Specialty Chemicals Co., Ltd. 0.920 g, photosensitizer (Kayacure DETX, trade name, Nippon Kayaku Co., Ltd.) 0.307 g, methyl ethyl ketone 230.0 g And 500 g of cyclohexanone was added and stirred. The solution was filtered through a polypropylene filter having a pore diameter of 0.4 μm to prepare a coating solution for forming a middle refractive index layer.

(Preparation of coating solution for high refractive index layer)
To 110.0 g of the titanium dioxide dispersion, 6.29 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA (trade name), manufactured by Nippon Kayaku Co., Ltd.), a photopolymerization initiator (IRGACURE) 907 [trade name], 0.520 g of Ciba Specialty Chemicals Co., Ltd., 0.173 g of photosensitizer (Kayacure DETX, trade name, Nippon Kayaku Co., Ltd.), 230.0 g of methyl ethyl ketone And 460.0g of cyclohexanone was added and stirred. A coating solution for forming a high refractive index layer was prepared by filtering through a polypropylene filter having a pore diameter of 0.4 μm.

(Preparation of coating solution for hard coat layer)
125 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA (trade name), Nippon Kayaku Co., Ltd.) and urethane acrylate oligomer (UV-6300B (trade name), Nippon Synthetic Chemical Industry Co., Ltd. 125 g) was dissolved in 439 g of industrially modified ethanol. In the obtained solution, 7.5 g of a photopolymerization initiator (IRGACURE 907 [trade name], manufactured by Ciba Specialty Chemicals Co., Ltd.) and a photosensitizer (Kayacure-DETX (trade name), Nippon Kayaku Co., Ltd. )) A solution of 5.0 g in 49 g of methyl ethyl ketone was added. The mixture was stirred and then filtered through a 1 micron mesh filter to prepare a coating solution for forming a hard coat layer.

(Coating each layer)
The above-mentioned coating liquid for hard coat layer was applied on a triacetyl cellulose film (TD80U (trade name), manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm as the transparent support 2 using a bar coater. After drying at 90 ° C., the coating layer was cured by irradiating with ultraviolet rays to form a hard coat layer 3 having a thickness of 6 μm.
On the hard coat layer 3, the medium refractive index layer coating solution was applied using a bar coater. After drying at 60 ° C., the coating layer was cured by irradiating with ultraviolet rays to form a medium refractive index layer 7 (refractive index 1.70, film thickness 70 nm, TTB-55B, 21% by volume).
On the middle refractive index layer 7, the coating liquid for high refractive index layer was applied using a bar coater. After drying at 60 ° C., the coating layer was cured by irradiating with ultraviolet rays to form a high refractive index layer 8 (refractive index 1.95, film thickness 75 nm).
On the high refractive index layer 8, the curable resin compositions prepared from the hollow microparticles of the above-described samples 101 to 110 and samples c02 to c05 of the present invention were applied using a bar coater and dried at 90 ° C. After that, ultraviolet rays were irradiated in a nitrogen atmosphere, further heated at 120 ° C. for 10 minutes, and then allowed to cool to room temperature to form a low refractive index layer 5 (film thickness 85 nm), and an antireflection film (S101 to 110, Sc02 to c05) were prepared. The results are shown in Table 3.

(Evaluation methods)
(1) Evaluation of average reflectance Using a spectrophotometer (manufactured by JASCO Corporation), a spectral reflectance at an incident angle of 5 ° was measured in a wavelength region of 380 to 780 nm. The mirror surface average reflectance of 450-650 nm was used for the result.
(2) Pencil Hardness Evaluation After the antireflection film was conditioned at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, pencil hardness evaluation described in JIS K 5400 was performed.
(3) Evaluation of scratch resistance After the film surface was rubbed 10 times under a load of 1000 g / cm ² using steel wool # 0000, the scratching level was confirmed. The determination was in accordance with the following criteria.
Not at all ： ○
Small scratches: △
Scratch is remarkable: ×

表３に示す結果より、本発明の中空微粒子試料１〜１０を用いた反射防止フィルムＳ１０１〜Ｓ１１０は、比較例のものを用いたフィルムＳｃ０２〜Ｓｃ０５に比べて、平均反射率が低く、高い鉛筆硬度及び耐擦傷性を示すことが分かる。

From the results shown in Table 3, the antireflection films S101 to S110 using the hollow fine particle samples 1 to 10 of the present invention have a lower average reflectance and a higher pencil than the films Sc02 to Sc05 using the comparative examples. It can be seen that it exhibits hardness and scratch resistance.

(Preparation Examples 21 to 30)
<Preparation of emulsion>
The emulsion was prepared in the same manner as in Preparation Example 1 except that the polymerizable monomer, core-forming medium, oil, photoradical polymerization initiator, and surfactant were changed to the types and amounts used shown in Table 4. Adjusted to be <sample 21> to <sample 30>. Table 4 shows the volume average particle diameter and monodispersity of the obtained sample.

<Polymerization reaction using UV-LED>
1 is used as a reaction apparatus 10 having a micro-channel shown in FIG. 1 (the channel 3 has a channel width of 500 μm, a height of 200 μm, and a channel length of 50 cm. The substrate 1 is made of Pyrex (registered trademark) glass. The substrate 2 was made of aluminum, and the substrate 2 was fed from the inlet 11 with a syringe pump. The liquid feeding speed was the liquid flow rate shown in Table 4. The light source 13 is a UV-LED irradiation device ZUV-C30H [trade name] (365-nm UV-LED) manufactured by OMRON Corporation, and the head unit ZUV-H30M [trade name] is a lens unit XUV-L3H [trade name] (spot). Install the diameter 3 mm □), the lens surface is fixed away 11mm from the channel upper surface (catalog of Work Distance 11mm to the same), the output shown in Table 4 (%) (maximum irradiation intensity 6000mW / cm ² nominal) Irradiated. In addition, it measured with the Ushio electric company make and a UV integrated light meter UIT-250 [brand name] which attached the 365nm sensor before irradiation, and irradiation intensity correction was performed. Since the decrease in irradiation intensity per hour was maintained at -5% or less by the method of forcibly cooling the head part, temperature attenuation correction was not performed.
The irradiation pattern is controlled by the head output (%) shown in Table 4 with the heads installed at four positions (flow path lengths of 17 cm, 28 cm, 39 cm, and 50 cm) on the flow path 3 in FIG. did. The irradiation time (= reaction time) was calculated from the irradiation area (3 mm □) and the liquid feeding flow rate. The UV integrated irradiation intensity (mJ / cm ² ) is a calculated value obtained by multiplying the irradiation intensity (mW / cm ² ) of each head by the output (%) and the irradiation time (sec). Since the glass thickness is constant, the intensity attenuation due to the change in irradiation intensity can be corrected by Lambert-Beer law, but no strict attenuation correction was performed. The reactor 10 was maintained at a temperature of 16 ° C. by a temperature control method in which the Peltier element was feedback controlled by a model FC-2410 [trade name] manufactured by Sensor Control.

  The reaction solution discharged from the collection port 12 is received in the flask, the first 4 mL of the sample obtained is discarded as the first fraction, and then sent to and reacted to a volume of 10 ml <Sample 21> to <Sample 30 > Polymerized particle liquid was collected in a flask. The particle diameters of the fine particles in each of the obtained samples were measured with Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd., and the volume average particle diameter and monodispersity of the obtained samples are shown in Table 4.

  As can be seen from the results in Table 4, polymer fine particles having a particle diameter of 100 nm or less are obtained even in the case of a sample obtained by polymerization using a emulsion using a specific material and a UV-LED as a light source in the distribution process. I know you give it.

(Example 3)
(1) Preparation of hollow fine particles Samples 21 to 30 of the present invention shown in Table 4 were dissolved in THF, and only the polymerization portion was isolated by preparative GPC. An example of GPC sorting in the case of the sample 21 is shown in FIG.

(2) Confirmation of inclusion solvent by TG-DTA
In the TG-DTA measurement of Samples 21 to 30 of the present invention shown in Table 4, two endothermic peaks are observed in DTA by the temperature rise rate measurement, which seems to be due to the release of the inclusion solvent. Thereby, the formation of hollow fine particles can be confirmed. When the monomer used is a fluorine-based monomer, the change due to the DTA measurement is small, and a two-step peak method based on the weight reduction in the TG measurement is strongly observed.

(4) Refractive index measurement of hollow fine particles The hollow fine particle portion of the sample 21 of the present invention shown in Table 4 was fractionated by GPC to obtain a THF solution of hollow fine particles (0.10 g hollow fine particles / 100 g THF).
Further, 0.10 g of dipentaerythritol hexaacrylate (DPHA), 0.012 g of IRGACURE 184 (photoinitiator), and 39.90 g of THF were weighed and uniformly dissolved to prepare a stock solution of THF.
The THF solution of hollow fine particles (0.10 g hollow fine particles / 100 g THF) and the stock solution were weighed so that the weight percentage ratio of the hollow fine particles was 50, 40, 30%, and after mixing, they were concentrated until immediately before sample precipitation. This solution was applied on a quartz substrate (25 mm × 25 mm × 1.0 mm) with a spin coater under conditions of 500 rpm × 5 seconds and then 1000 rpm × 20 seconds, then dried at 100 ° C. for 60 seconds, and then 40 mW / cm ^2. The sample was irradiated with UV light for 60 seconds to obtain a hollow fine particle thin film-coated sample T121 (three different concentrations) of the present invention.
Next, the hollow fine particle thin film coated samples T122 to T130 of the present invention were prepared in the same manner except that the sample to be GPC sorted was replaced with the samples 22 to 30 from the sample 21 (three different sample concentrations). In the case of 100% hollow fine particles in each sample by extrapolation, the film pressure measurement and refractive index measurement of the obtained three types of thin films of each sample were measured using a reflection spectral film pressure gauge FE-3000 [trade name] manufactured by ATAGO. The refractive index was calculated and the results are shown in Table 5.

表５に示す結果より、本発明の中空微粒子試料を用いた膜試料は屈折率が低く、反射防止フィルム等に好適に用いられることが分かる。

From the results shown in Table 5, it can be seen that the film sample using the hollow fine particle sample of the present invention has a low refractive index and is suitably used for an antireflection film or the like.

It is a disassembled perspective view which shows typically preferable embodiment of the flow-type reaction apparatus used for the manufacturing method of this invention. It is process explanatory drawing which shows each process notionally as one embodiment in the manufacturing method of this invention. It is explanatory drawing of preparative refinement | purification of the hollow fine particle part by GPC.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Substrate 3 Reaction flow path 11 Raw material introduction port 12 Product collection port 13 Light irradiation means (ultraviolet lamp, UV-LED, etc.)
14 Light (ultraviolet light)
21 Channel inlet 22 Emulsified liquid medium (continuous phase)
23 Dispersed 24 Emulsified particles (dispersed phase)
25 Outer shell 26 Core-forming medium-containing fine particles 27 Hollow fine particles 27a Internal pores

Claims (23)

  An emulsified liquid in which a dispersed phase containing a polymerizable monomer and a core-forming medium is dispersed in a continuous phase is circulated through a flow path of a flow reactor, and the polymerizable monomer is polymerized in this flow process to form an outer shell. A process for producing hollow microparticles, wherein the polymer of the polymerizable monomer that constitutes the polymer has a step of generating microparticles enclosing the core-forming medium.   The method for producing hollow microparticles according to claim 1, wherein the core forming medium in the outer shell is vaporized or vaporized and released.   The method for producing hollow fine particles according to claim 1 or 2, wherein the fine particles have a volume average diameter (MV) of 100 nm or less.   The method for producing hollow microparticles according to any one of claims 1 to 3, wherein the core-forming medium has a boiling point of 50 to 150 ° C at 760 mmHg.   The method for producing hollow fine particles according to any one of claims 1 to 4, wherein the core forming medium is a saturated hydrocarbon solvent or a solvent having a fluorine content of 50% by mass or more.   The method for producing hollow fine particles according to any one of claims 1 to 5, wherein the dispersed phase of the emulsion further contains at least one radical polymerization initiator.   The method for producing hollow fine particles according to any one of claims 1 to 6, wherein the dispersed phase of the emulsion further contains at least one kind of saturated hydrocarbon compound oil or fluorine compound oil.   The method for producing hollow fine particles according to claim 6 or 7, wherein the radical polymerization initiator is a photo radical polymerization initiator.   9. The method for producing hollow fine particles according to claim 8, wherein the photo radical polymerization initiator is a compound that absorbs ultraviolet rays of 300 to 400 nm to generate radicals.   The method for producing hollow fine particles according to any one of claims 1 to 9, wherein the polymerizable monomer is a fluorine-containing monomer.   The method for producing hollow fine particles according to any one of claims 1 to 10, wherein the emulsion is prepared by a microemulsion method.   The method for producing hollow fine particles according to any one of claims 1 to 11, wherein the volume average diameter (MV) of the emulsified particles forming the dispersed phase in the emulsion is 100 nm or less.   The method for producing hollow fine particles according to any one of claims 1 to 12, wherein the flow type reaction apparatus is irradiated with light by a light irradiation means, and the polymerizable monomer is polymerized by photo radical polymerization.   The hollow according to any one of claims 1 to 13, wherein the flow reactor has a flow path having an equivalent diameter of 1 mm or less, and an emulsion of the polymerizable monomer is introduced into the flow path. A method for producing fine particles.   The volume average particle size (MV) of the hollow fine particles is 10 to 60 nm, and the volume average particle size (MV) / number average particle size (MN) is 1.2 to 2.0. The method for producing hollow fine particles according to any one of 1 to 14.   The average value of the ratio of the particle outer shell diameter to the particle inner pore diameter of the hollow fine particles ([particle inner pore diameter] / [particle outer shell diameter]) is 0.3 to 0.7. The method for producing hollow fine particles according to any one of -15.   The method for producing hollow fine particles according to any one of claims 1 to 16, which is obtained as an aqueous dispersion containing the hollow fine particles.   The method for producing hollow microparticles according to claim 17, wherein the aqueous dispersion is concentrated with an ultrafiltration membrane, and the concentrate is dried under reduced pressure.   The hollow microparticles obtained by the production method according to any one of claims 1 to 18, having a volume average diameter (MV) of 100 nm or less and having a hollow structure in which a space is held inside.   In a thin film having a thickness of 2 μm obtained by dispersing hollow fine particles in a binder compound and applying to a glass substrate, the haze value (haze value) when measured by an integrating sphere photoelectric photometry is 0. The hollow microparticle according to claim 19, wherein the content is 5% or less.   Hollow fine particles are dispersed in a mixture of a fluorinated monomer and a photopolymerization initiator, applied to a glass substrate, a cured thin film having a thickness of 100 μm obtained through the photopolymerization step is peeled off from the glass plate, and an Abbe refractometer is used. The hollow fine particles according to claim 19 or 20, wherein the refractive index when measured at 25 ° C is 1.45 or less.   An aqueous dispersion containing the hollow fine particles according to any one of claims 19 to 21 and an aqueous medium.   The antireflection film which has a hollow microparticle of any one of Claims 19-21.

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