JP2016033101A - Method for producing metal oxide hollow particles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing metal oxide hollow particles having a volume 50% average particle size of 10 nm or more and 50 nm or less.SOLUTION: The method for producing metal oxide hollow particles having a volume 50% average particle size of 10 nm or more and 50 nm or less is provided that comprises : a step (1) of obtaining a mixture containing water and/or an organic solvent which dissolves a part or all of water, water-insoluble polymer particles (X) having a volume 50% average particle size of 5 nm or more and 30 nm or less, and a cationic surfactant (Z), a weight ratio of (X):(Z) being 10:1 to 1:10; a step (2) of obtaining organic-inorganic composite particles by mixing the above mixture and a metal oxide precursor and carrying out a sol-gel reaction of the metal oxide precursor; and a step (3) of removing the water-insoluble polymer particles (X) from the organic-inorganic composite particles.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for producing metal oxide hollow particles.

  In recent years, metal oxide hollow materials such as hollow silica have been newly applied to optical materials, low dielectric constant materials, heat insulating materials, pharmaceuticals (DDS: drug delivery systems), molecular probes, catalysts, adsorbing materials, sensors, paints, inks, etc. It is expected as a possible material. In general, as a method for producing a metal oxide hollow material, there are a method using a hard template such as calcium carbonate and polymer beads, a method using a soft template such as an emulsion and vesicle, etc., but in such a method, the particle size is small ( It is difficult to obtain a hollow material having a narrow particle size distribution. Patent Document 1 and Patent Document 2 disclose a method of obtaining hollow silica by coating the surface of calcium carbonate with silica and then dissolving and removing the calcium carbonate. However, the hollow silica obtained by this method has a large particle size distribution of 45 to 90 nm and is a cubic particle reflecting the crystal form of calcium carbonate. Patent Document 3 discloses a method for producing hollow particles using water-insoluble polymer particles.

JP 2005-263550 A JP 2008-2222459 A JP 2014-009261 A

However, in order to form a silica layer by the method described in Patent Document 3, a hydrothermal reaction step using an autoclave is required, and specific equipment is required, which is not suitable for mass production.
Therefore, development of a method for efficiently producing metal oxide hollow particles having a volume 50% average particle diameter of 10 nm to 50 nm is desired. However, no satisfactory production method has been developed yet.

  This invention is made | formed in view of the above subjects, and provides the manufacturing method of the metal oxide hollow particle whose volume 50% average particle diameter is 10 nm or more and 50 nm or less.

  That is, the present invention can be described below.

[1] including water and / or an organic solvent that dissolves a part or all of water, water-insoluble polymer particles (X) having a volume 50% average particle diameter of 5 nm to 30 nm, and a cationic surfactant (Z) (1) obtaining a mixture having a weight ratio (X) :( Z) of 10: 1 to 1:10;
Mixing the mixture and the metal oxide precursor, and performing a sol-gel reaction of the metal oxide precursor to obtain organic-inorganic composite particles;
A method for producing metal oxide hollow particles, comprising a step (3) of removing the water-insoluble polymer particles (X) from the organic-inorganic composite particles, wherein the 50% volume average particle diameter is 10 nm or more and 50 nm or less.

[2] The method for producing metal oxide hollow particles according to [1], wherein the mixture of the step (1) further contains an acidic catalyst.

[3] In the step (2), the mixture and the metal oxide precursor are mixed, the mixture is subjected to ultrasonic treatment, and then a sol-gel reaction of the metal oxide precursor is performed to form organic-inorganic composite particles. The method for producing metal oxide hollow particles according to [1] or [2], wherein

[4] The water-insoluble polymer particles are particles composed of a terminal branched polyolefin copolymer represented by the following general formula (1) and having a number average molecular weight of 2.5 × 10 ⁴ or less. ] Or the manufacturing method of the metal oxide hollow particle as described in [2].
(In the formula, A represents a polyolefin chain. R ¹ and R ² represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. X ¹ and X ² are the same. Or, differently, it represents a group containing a linear or branched polyalkylene glycol group.)

[5] X ¹ and X ^{2 of the} terminal branched polyolefin copolymer represented by the general formula (1) are the same or different, and the general formula (2)
(In the formula, E represents an oxygen atom or a sulfur atom, X ³ represents a polyalkylene glycol group,
Or general formula (3)
(In the formula, R ³ represents an m + 1 valent hydrocarbon group. G is the same or different and is represented by —OX ⁴ , —NX ⁵ X ⁶ (X ^{4 to} X ⁶ represent a polyalkylene glycol group). M represents the number of bonds between R ³ and G, and represents an integer of 1 to 10). )
Or general formula (4)
(Wherein X ⁷ and X ⁸ are the same or different and each represents a polyalkylene glycol group or a group represented by the above general formula (3)). A method for producing metal oxide hollow particles.

[6] The method for producing metal oxide hollow particles according to [4] or [5], wherein the terminally branched polyolefin copolymer is represented by the following general formula (1a) or (1b): .
(In the formula, R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. R ⁶ and R ⁷ represent a hydrogen atom or a methyl group, At least one of them is a hydrogen atom, R ⁸ and R ⁹ represent a hydrogen atom or a methyl group, and at least one of them is a hydrogen atom, l + m represents an integer of 2 to 450, n is 20 Represents an integer of 300 or more.)
(In the formula, R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. R ⁶ and R ⁷ represent a hydrogen atom or a methyl group, At least one of them is a hydrogen atom, R ⁸ and R ⁹ represent a hydrogen atom or a methyl group, at least one of them is a hydrogen atom, R ¹⁰ and R ¹¹ represent a hydrogen atom or a methyl group, (At least one of them is a hydrogen atom. L + m + o represents an integer of 3 to 450, and n represents an integer of 20 to 300.)

[7] The method for producing metal oxide hollow particles according to any one of [1] to [6], wherein the cationic surfactant (Z) is a tetraalkyl quaternary ammonium salt type surfactant.

[8] The method for producing metal oxide hollow particles according to [7], wherein the tetraalkyl quaternary ammonium salt type surfactant is cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (CTAC).

In the method for producing metal oxide hollow particles of the present invention, an organic-inorganic composite can be prepared under relatively mild reaction conditions by using a cationic surfactant.
Since the metal oxide hollow particles obtained by the present invention have a small average particle diameter, they can be used for various applications and can effectively exhibit desired characteristics. For example, the metal oxide hollow particles of the present invention can be easily dispersed uniformly in a binder resin, and a highly transparent resin composition can be provided.
Furthermore, the metal oxide hollow particles obtained by the present invention are excellent in adsorbability of liquid molecules such as water and organic solvents, and gas molecules such as water vapor, methane, oxygen and nitrogen, and encapsulate a desired substance in the internal pores. Holding and further sustained release are possible. Further, since air is provided inside the particles, it can also contribute to characteristics such as weight reduction, heat insulation, low refractive index, and low dielectric constant. Moreover, since it has such characteristics, it can be used for various purposes.

It is a schematic cross section which shows the core-shell type organic inorganic composite particle which concerns on embodiment. It is a schematic cross section which shows the hollow particle which concerns on embodiment. 2 is a TEM image of hollow particles obtained in Example 1. FIG. 3 is a TEM image of hollow particles obtained in Example 2. 2 is a TEM image of hollow particles obtained in Comparative Example 1.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

The method for producing the metal oxide hollow particles of the present embodiment,
Water and / or an organic solvent that dissolves part or all of water, water-insoluble polymer particles (X) having a 50% volume average particle size of 5 nm to 30 nm and a cationic surfactant (Z), in a weight ratio (X): Step (1) for obtaining a mixture in which (Z) is 10: 1 to 1:10;
Mixing the mixture and the metal oxide precursor, and performing a sol-gel reaction of the metal oxide precursor to obtain organic-inorganic composite particles;
A method for producing metal oxide hollow particles having a volume 50% average particle diameter of 10 nm or more and 50 nm or less, comprising the step (3) of removing the water-insoluble polymer particles (X) from the organic-inorganic composite particles.

<Hollow metal oxide particles>
The metal oxide hollow particles of the present embodiment are so-called monodispersed particles having a substantially uniform size and high dispersibility.
FIG. 2 is a diagram schematically showing a cross section of the hollow particle according to the present embodiment.
As shown in FIG. 2, the metal oxide hollow particles have substantially uniform pores therein. The 50% volume average particle diameter (outer diameter) of the metal oxide hollow particles of the present embodiment is from 10 nm to 50 nm, preferably from 20 nm to 40 nm.
Further, the inner diameter of the metal oxide hollow particles of the present embodiment varies depending on the outer diameter, but is, for example, 5 nm or more and 30 nm or less, preferably 10 nm or more and 25 nm or less.
When the outer diameter and inner diameter of the metal oxide hollow particles are within this range, the light scattering of the particles is small, and the metal oxide hollow particles can be used in various applications, and desired characteristics can be effectively expressed. For example, when used as a resin composition to be described later, a resin composition that can be uniformly dispersed in a binder resin and has high transparency can be obtained.

  In addition, the ratio of the volume 90% average particle diameter to the volume 50% average particle diameter (D90 / D50) of the metal oxide hollow particles of the present embodiment is preferably 1.5 or less, more preferably 1.0. It is 1.4 or less. Within this range, the particle size distribution is narrow and the number of coarse particles is small, so that the handleability is excellent and desired characteristics can be effectively expressed. For example, when used as a resin composition described later, it is preferable in terms of uniform dispersibility in the binder resin and transparency of the resulting resin.

Further, the metal oxide hollow particles of the present embodiment have a hollow inside, and the BET specific surface area is, for example, 300 m ² / g or more, preferably 400 m ² / g or more. Further, from the viewpoint that the thermal conductivity is preferably free from anisotropy due to the shape, it is preferable to have a spherical shape and uniform mesopores.
This BET specific surface area can be measured, for example, by a nitrogen adsorption method.
The outer diameter of the metal oxide hollow particles can be confirmed with a particle size distribution meter (DLS) by dynamic light scattering of a sample dispersed in water. The inner diameter can be observed from a TEM image photograph.
In this embodiment, the metal means not only a typical metal but also a semimetal such as Si.

As the metal oxide of this embodiment, silicon (Si), aluminum (Al), zinc (Zn), zirconium (Zr), indium (In), tin (Sn), titanium (Ti), lead (Pb), A metal oxide selected from hafnium (Hf), cobalt (Co), lithium (Li), barium (Ba), iron (Fe), and manganese (Mn) is preferable, and the refractive index and thermal conductivity of the substance itself are metals. From the viewpoint of being relatively low among oxides, silicon oxide (silica) is particularly preferable.
The metal oxide may be a complex oxide containing a plurality of metals.

<Method for producing metal oxide hollow particles>
The method for producing metal oxide hollow particles of the present embodiment includes the following step (1), step (2), and step (3).
Step (1): Water and / or an organic solvent that dissolves part or all of water, water-insoluble polymer particles (X) having a volume 50% average particle diameter of 5 nm to 30 nm, and a cationic surfactant (Z) And a weight ratio (X) :( Z) of 10: 1 to 1:10 is obtained.
Step (2): A step of mixing the mixture obtained in Step (1) and a metal oxide precursor, and performing a sol-gel reaction of the metal oxide precursor to obtain organic-inorganic composite particles.
Step (3): A step of removing the water-insoluble polymer particles (X) from the organic-inorganic composite particles obtained in the step (2).

In this embodiment, it is necessary to perform a sol-gel reaction of the metal oxide precursor in the presence of water-insoluble polymer particles and a cationic surfactant. By adding the acidic catalyst (V) to the mixture in addition to the water-insoluble polymer particles and the cationic surfactant, the sol-gel reaction proceeds quickly, and further the metal oxide precursor is included so as to enclose the water-insoluble polymer particles. Since the body forms a three-dimensionally dense gel, organic-inorganic composite particles can be suitably obtained. Further, the progress of the sol-gel reaction can be accelerated by ultrasonic treatment.
Hereinafter, each process is demonstrated in order.

[Process (1)]
In the step (1), specifically, the water-insoluble polymer particles (X) (hereinafter referred to as “component (X)” where appropriate), water and / or an organic solvent (Y) ) (Hereinafter referred to as “component (Y)” as appropriate), cationic surfactant (Z) (hereinafter referred to as “component (Z)” as appropriate), and acidic catalyst (V) as required (hereinafter referred to as “ Component (V) ") is mixed to prepare a mixture.
In step (1), an aqueous dispersion of water-insoluble polymer particles (X) described later, an organic solvent (Y) and a cationic surfactant (Z) that dissolves water and / or a part or all of water, as necessary Accordingly, it is preferable to obtain a mixture by mixing the acidic catalyst (V).

The water-insoluble polymer particles (X) will be described in detail.
The water-insoluble polymer particles preferably have a 50% volume average particle diameter of 5 nm to 30 nm. By using the metal oxide hollow particles obtained from such water-insoluble polymer particles, a highly heat-insulating and transparent film and coating film can be realized. The 50% volume average particle size can be measured using a particle size distribution meter (DLS).

  As the water-insoluble polymer particles (X) used in the present embodiment, polyolefin-based water-insoluble polymer particles are preferably used because they easily form water-insoluble polymer particles having an outer diameter of 30 nm or less. More preferable are terminal branched polyolefin copolymer particles represented by the following general formula (1).

(In the formula, A represents a polyolefin chain. R ¹ and R ² are a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom, and X ¹ and X ² are the same. Or, differently, it represents a group containing a linear or branched polyalkylene glycol group.)

The number average molecular weight of the terminal branched polyolefin copolymer particles represented by the general formula (1) is 2.5 × 10 ⁴ or less, preferably 1.5 × 10 ⁴ or less, more preferably 4.0 × 10 ^3. It is as follows. Moreover, it is preferably 5.5 × 10 ² or more, more preferably 8 × 10 ² or more. The number average molecular weight is the number average molecular weight of the polyolefin chain represented by A, the number average molecular weight of the group containing a polyalkylene glycol group represented by X ¹ and X ² , and R ¹ , R ² and C ₂ H min. It is expressed as the sum of molecular weights.

  When the number average molecular weight of the terminal branched polyolefin copolymer particles is in the above range, the stability of the particles in the dispersion when the terminal branched polyolefin copolymer particles are used as a dispersoid, water and / or water The dispersibility in an organic solvent that dissolves a part or all of the above tends to be good, and the dispersion is easy to prepare, which is preferable.

  The polyolefin chain which is A in the general formula (1) is obtained by polymerizing an olefin having 2 to 20 carbon atoms. Examples of the olefin having 2 to 20 carbon atoms include α-olefins such as ethylene, propylene, 1-butene and 1-hexene. In this embodiment, the homopolymer or copolymer of these olefins may be sufficient, and the thing copolymerized with other polymerizable unsaturated compounds in the range which does not impair a characteristic may be sufficient. Among these olefins, ethylene, propylene, and 1-butene are particularly preferable.

  In general formula (1), the number average molecular weight of the polyolefin chain represented by A measured by GPC (gel permeation chromatography) is 400 to 8000, preferably 500 to 4000, more preferably 500 to 2000. It is. Here, the number average molecular weight is a value in terms of polystyrene.

  When the number average molecular weight of the polyolefin chain represented by A is in the above range, the polyolefin portion has high crystallinity, the dispersion tends to be stable, and the melt viscosity is low and the preparation of the dispersion is easy. This is preferable.

  The ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by GPC of the polyolefin chain represented by A in the general formula (1), that is, the molecular weight distribution (Mw / Mn) is not particularly limited. However, it is usually 1.0 to several tens, more preferably 4.0 or less, and still more preferably 3.0 or less.

  When the molecular weight distribution (Mw / Mn) of the polyolefin chain represented by A in the general formula (1) is in the above range, it is preferable from the viewpoint of the shape of the particles in the dispersion and the uniformity of the particle diameter.

The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the polyolefin chain represented by A by GPC are, for example, under the following conditions using GPC-150 manufactured by Millipore It can be measured.
Separation column: TSK GNH HT (column size: diameter 7.5 mm, length: 300 mm)
Column temperature: 140 ° C
Mobile phase: Orthodichlorobenzene (Wako Pure Chemical Industries, Ltd.)
Antioxidant: Butylhydroxytoluene (manufactured by Takeda Pharmaceutical Company Limited) 0.025% by mass
Movement speed: 1.0 ml / min Sample concentration: 0.1% by mass
Sample injection volume: 500 microliters Detector: Differential refractometer

  The molecular weight of the polyolefin chain represented by A can be measured by measuring the molecular weight of a polyolefin having an unsaturated group at one end and subtracting the molecular weight corresponding to the end.

R ¹ and R ² are each a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms, which is a substituent bonded to a double bond of the polyolefin constituting A, preferably a hydrogen atom or 1 to 18 carbon atoms. It is an alkyl group. As the alkyl group, a methyl group, an ethyl group, and a propyl group are preferable.

In the general formula (1), X ¹ and X ² are the same or different and each represents a group containing a polyalkylene glycol group having a linear or branched number average molecular weight of 50 to 10,000. The branching mode of the branched polyalkylene glycol group includes branching via a polyvalent carbon-valent hydrogen group or a nitrogen atom. For example, branching by a hydrocarbon group bonded to two or more nitrogen atoms, oxygen atoms or sulfur atoms in addition to the main skeleton, branching by a nitrogen atom bonded to two alkylene groups in addition to the main skeleton, and the like can be given.

  It is preferable that the number average molecular weight of the group containing a polyalkylene glycol group is in the above range since the dispersibility of the dispersion tends to be good and the melt viscosity is low and the preparation of the dispersion is easy.

A terminal branched polyolefin system in which X ¹ and X ^{2 in} the general formula (1) have the above-described structure, so that a 50% volume average particle size is 5 nm or more and 30 nm or less without using a surfactant. Polymer particles comprising a copolymer are obtained.

In the general formula (1), preferred examples of X ¹ and X ² are the same or different from each other, and the general formula (2),

(In the formula, E represents an oxygen atom or a sulfur atom, X ³ represents a polyalkylene glycol group, or a general formula (3)

(Wherein R ³ represents an m + 1 valent hydrocarbon group, G is the same or different, and is represented by —OX ⁴ , —NX ⁵ X ⁶ (X ^{4 to} X ⁶ represent a polyalkylene glycol group). M represents the number of bonds between R ³ and G, and represents an integer of 1 to 10.). )
Or general formula (4)

(Wherein X ⁷ and X ⁸ are the same or different and represent a polyalkylene glycol group or a group represented by the above general formula (3)).

In the general formula (3), the group represented by R ³ is an m + 1 valent hydrocarbon group having 1 to 20 carbon atoms. m is an integer of 1 to 10, an integer of 1 to 6 is preferable, and an integer of 1 to 2 is particularly preferable.

As a preferable example of the general formula (1), a terminal branched polyolefin copolymer in which ^one of X ¹ and X ² is a group represented by the general formula (4) in the general formula (1). Can be mentioned. More preferable examples include terminal branched polyolefin copolymers in which ^one of X ¹ and X ² is represented by the general formula (4) and the other is a group represented by the general formula (2). It is done.

As another preferable example of the general formula (1), ^one of X ¹ and X ^{2 in} the general formula (1) is a group represented by the general formula (2), and more preferably X ¹ and X ^2. And a terminal branched polyolefin copolymer in which both are groups represented by the general formula (2).

  As a more preferred structure of the general formula (4), the general formula (5)

(Wherein X ⁹ and X ¹⁰ are the same or different and represent a polyalkylene glycol group, and Q ¹ and Q ² are the same or different and each represents a divalent hydrocarbon group). is there.

The divalent hydrocarbon group represented by Q ¹ and Q ² in the general formula (5) is preferably a divalent alkylene group, and more preferably an alkylene group having 2 to 20 carbon atoms. The alkylene group having 2 to 20 carbon atoms may or may not have a substituent, for example, ethylene group, methylethylene group, ethylethylene group, dimethylethylene group, phenylethylene group, chloromethylethylene group, bromo Examples thereof include a methylethylene group, a methoxymethylethylene group, an aryloxymethylethylene group, a propylene group, a trimethylene group, a tetramethylene group, a hexamethylene group, and a cyclohexylene group. A preferable alkylene group is a hydrocarbon-based alkylene group, particularly preferably an ethylene group or a methylethylene group, and still more preferably an ethylene group. Q ¹ and Q ² may be one kind of alkylene group, or two or more kinds of alkylene groups may be mixed.

As a more preferable structure of X ¹ and X ² represented by the general formula (1), the general formula (6)

(Wherein X ¹¹ represents a polyalkylene glycol group).

The polyalkylene glycol group represented by X ^{3 to} X ¹¹ is a group obtained by addition polymerization of alkylene oxide. Examples of the alkylene oxide constituting the polyalkylene glycol group represented by X ^{3 to} X ¹¹ include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, cyclohexene oxide, epichlorohydrin, epibromohydrin, methyl glycidyl ether, allyl A glycidyl ether etc. are mentioned. Of these, propylene oxide, ethylene oxide, butylene oxide, and styrene oxide are preferable. More preferred are propylene oxide and ethylene oxide, and particularly preferred is ethylene oxide. The polyalkylene glycol group represented by X ^{3 to} X ¹¹ may be a group obtained by homopolymerization of these alkylene oxides or a group obtained by copolymerization of two or more kinds. Examples of preferred polyalkylene glycol groups are polyethylene glycol groups, polypropylene glycol groups, or groups obtained by copolymerization of polyethylene oxide and polypropylene oxide, and particularly preferred groups are polyethylene glycol groups.

When X ¹ and X ² in the general formula (1) have the above structure, water and / or a part or all of the water when the terminally branched polyolefin copolymer particles of this embodiment are used as a dispersoid are dissolved. This is preferable because dispersibility in an organic solvent is improved.

  As the terminal branched polyolefin copolymer particles that can be used in the present embodiment, it is preferable to use a polymer represented by the following general formula (1a) or (1b).

(In the formula, R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. The alkyl group is preferably an alkyl group having 1 to 9 carbon atoms. R ⁶ and R ⁷ each represents a hydrogen atom or a methyl group, and at least one of them is a hydrogen atom, and R ⁸ and R ⁹ represent a hydrogen atom or a methyl group. And at least one of them is a hydrogen atom.
l + m represents an integer of 2 to 450, preferably 5 to 200.
n represents an integer of 20 to 300, preferably 25 to 200. )

(In the formula, R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. The alkyl group is preferably an alkyl group having 1 to 9 carbon atoms. Further, an alkyl group having 1 to 3 carbon atoms is more preferable.
R ⁶ and R ⁷ represent a hydrogen atom or a methyl group, and at least one of them is a hydrogen atom. R ⁸ and R ⁹ represent a hydrogen atom or a methyl group, and at least one of them is a hydrogen atom. R ¹⁰ and R ¹¹ represent a hydrogen atom or a methyl group, and at least one of them is a hydrogen atom.
l + m + o represents an integer of 3 to 450, preferably 5 to 200.
n represents an integer of 20 to 300, preferably 25 to 200. )

  As the polymer represented by the general formula (1b), it is more preferable to use a polymer represented by the following general formula (1c).

(In the formula, l + m + o and n are the same as those in the general formula (1b).)
The number of ethylene units (n) in the polyethylene chain was calculated by dividing the number average molecular weight (Mn) of the polyolefin chain represented by A in the general formula (1) by the molecular weight of the ethylene unit. The total number of ethylene glycol units (l + m or l + m + o) of the polyethylene glycol chain is such that the weight ratio of the polymer raw material to the ethylene oxide used during the polyethylene glycol group addition reaction is the number average molecular weight of the polymer raw material and the polyethylene glycol group (Mn ) And the ratio can be calculated.

N, l + m or l + m + o can also be measured by ¹ H-NMR. For example, in the terminal branched polyolefin copolymer (T) and dispersion particles containing the same used in the examples, the terminal methyl group of the polyolefin chain represented by A in the general formula (1) (shift value: 0) .88 ppm) when the integral value is 3 protons, the integral value of the methylene group (shift value: 1.06-1.50 ppm) of the polyolefin chain represented by A and the alkylene group of polyethylene glycol (PEG) ( (Shift value: 3.33-3.72 ppm) can be calculated from the integrated value.

  Specifically, since the molecular weight of the methyl group is 15, the molecular weight of the methylene group is 14, and the molecular weight of the ethylene oxide group is 44, the number average of the polyolefin chain and alkylene group represented by A from each integrated value. Molecular weight can be calculated. By dividing the number average molecular weight of the polyolefin chain represented by A thus obtained by the molecular weight of the ethylene unit and dividing the number average molecular weight of the alkylene group by the molecular weight of the ethylene glycol unit, the ethylene glycol of the PEG chain The total number of units (l + m or l + m + o) can be calculated.

When the polyolefin chain represented by A is composed of an ethylene-propylene copolymer, n and n are obtained by using both the propylene content that can be measured by IR, ¹³ C-NMR, and the integral value in ¹ H-NMR. l + m or l + m + o can be calculated. ^{In 1} H-NMR, a method using an internal standard is also effective.

  The terminally branched polyolefin copolymer particles can be produced, for example, by the method described in WO2010 / 103856.

  The polymer particles of this embodiment comprising such a terminally branched polyolefin copolymer have a structure in which the polyolefin chain portion represented by A in the general formula (1) is oriented in the inward direction. It is a rigid particle with chain part having crystallinity.

  The terminal branched polyolefin copolymer particles of the present embodiment can be dispersed in a liquid such as a solvent again even after the particles are taken out by drying the dispersion because the polyolefin chain portion has crystallinity. The terminal branched polyolefin copolymer particles of the present embodiment are rigid particles in which the melting point of the polyolefin chain portion contained in the particles is preferably 80 ° C. or higher, more preferably 90 ° C. or higher.

When the melting point of the polyolefin chain portion is at or above the above temperature, it becomes a rigid particle having good crystallinity, and even when heated at a higher temperature, the particle collapse is suppressed.
For this reason, in the manufacturing process and use scene in various applications described later, since the collapse of the particles is suppressed, the characteristics of the terminally branched polyolefin copolymer particles of the present embodiment are not lost, Product quality is more stable.

  Even if the terminal branched polyolefin copolymer particles of the present embodiment are dispersed in a solvent or the like, the particle diameter is constant regardless of the dilution concentration. That is, since it has redispersibility and a uniform dispersed particle size, it is different from micelle particles dispersed in a liquid.

[Water-insoluble polymer particle dispersion]
The dispersion of the present embodiment contains the water-insoluble polymer particles, preferably the terminally branched polyolefin copolymer particles, in the dispersoid, and the dispersoid dissolves water and / or a part or all of the water. Dispersed as particles in an organic solvent.

In the present embodiment, the dispersion liquid in which the water-insoluble polymer particles are dispersed is, for example,
(1) A dispersion containing the polymer particles, obtained when producing the water-insoluble polymer particles,
(2) A dispersion obtained by dispersing or dissolving other dispersoids or additives in the dispersion containing the polymer particles obtained when producing the water-insoluble polymer particles,
(3) A dispersion obtained by dispersing water-insoluble polymer particles in water or an organic solvent having an affinity for water and dispersing or dissolving other dispersoids or additives,
Any of these are included.

  The content ratio of the water-insoluble polymer particles in the dispersion of the present embodiment is preferably 0.1 to 50% by mass, more preferably 1 to 40% by mass, and more preferably 1 to 40% by mass when the total dispersion is 100% by mass. Preferably it is 1-20 mass%.

  It is preferable that the content ratio of the water-insoluble polymer particles is in the above range because the practicality of the dispersion liquid is good, the viscosity can be kept appropriate, and handling becomes easy.

  Moreover, the 50% volume average particle diameter of the particles in the dispersion liquid of the present embodiment is preferably 5 nm or more and 30 nm or less.

The 50% volume average particle diameter of the particles can be controlled by changing the molecular weight of the water-insoluble polymer, the ratio of hydrophilic groups to lipophilic groups, the degree of branching, and the like.
For example, it can be adjusted by changing the structure of the polyolefin portion and the structure of the terminal branch portion of the terminal branched polyolefin copolymer.
In addition, the 50% volume average particle diameter in the present embodiment refers to the diameter of a particle when the total volume is 100% when the total volume is 100%, and is a dynamic light scattering particle size distribution measuring device or a microtrack. It can be measured using a particle size distribution measuring device.
The shape can be observed with a transmission electron microscope (TEM) after negative staining with, for example, phosphotungstic acid.

  The dispersion in the present embodiment is obtained by dispersing water-insoluble polymer particles in water and / or an organic solvent that dissolves part or all of water.

  Dispersion in this embodiment can be performed by a method of physically dispersing water-insoluble polymer particles in water and / or an organic solvent that dissolves part or all of water by mechanical shearing force.

  The dispersion method is not particularly limited, but various dispersion methods can be used. Specifically, after mixing water-insoluble polymer particles with water and / or an organic solvent that dissolves part or all of water, the mixture is melted to obtain a high-pressure homogenizer, high-pressure homomixer, extrusion kneader, autoclave, etc. And the like, a method of spraying and pulverizing at a high pressure, a method of spraying from pores, and the like. The water-insoluble polymer particles are dissolved in a solvent other than water in advance, and then mixed with water and / or an organic solvent that dissolves part or all of the water, and dispersed by a high-pressure homogenizer, a high-pressure homomixer, or the like. A method is also possible. At this time, the solvent used for dissolving the water-insoluble polymer particles is not particularly limited as long as the water-insoluble polymer particles are dissolved, and examples thereof include toluene, cyclohexane and an organic solvent having an affinity for water. When it is not preferable that an organic solvent other than water is mixed in the dispersion, it can be removed by an operation such as distillation.

  More specifically, for example, in an autoclave equipped with a stirrer capable of applying a shearing force, the water-insoluble polymer particles are in a molten state and are not easily deteriorated by heating. In the case of the terminal branched polyolefin copolymer particles, a dispersion can be obtained by heating and stirring while applying a shearing force at a temperature of 100 ° C. or higher, preferably 120 to 200 ° C.

The time required for dispersion varies depending on the dispersion temperature and other dispersion conditions, but is about 1 to 300 minutes.
The above stirring time is preferable because the dispersion can be sufficiently performed and the water-insoluble polymer particles are hardly deteriorated. After the reaction, it is preferable to maintain a state in which shearing force is applied until the temperature in the dispersion becomes 100 ° C. or lower, preferably 60 ° C. or lower.

  In manufacturing the dispersion liquid used in the present embodiment, a filtration step may be provided in the process for the purpose of removing foreign substances and the like. In such a case, for example, a stainless steel filter (wire diameter 0.035 mm, plain weave) of about 300 mesh may be installed and pressure filtration (air pressure 0.2 MPa) may be performed.

  The water in the above method is not particularly limited, and distilled water, ion exchange water, city water, industrial water, and the like can be used, but it is preferable to use distilled water or ion exchange water.

  In addition, the organic solvent having an affinity for water in the above method is not particularly limited as long as the dispersoid such as water-insoluble polymer particles and surfactant can be dispersed. For example, ethylene glycol, tetraethylene glycol, isopropyl Alcohol, acetone, acetonitrile, methanol, ethanol, dimethyl sulfoxide, dimethylformamide, dimethylimidazolidinone and the like can be mentioned. When mixing of the organic solvent into the dispersion is not preferred, the organic solvent can be removed by distillation or the like after preparing a dispersion containing the dispersoid.

[Organic solvent (Y) for dissolving water and / or part or all of water]
The component (Y) in this embodiment is added for the purpose of further hydrolyzing the metal oxide precursor (W) (hereinafter referred to as “component (W)” as appropriate).

  Component (Y) includes a solvent used when an aqueous dispersion is obtained using a water-insoluble polymer, the aqueous dispersion, a metal alkoxide and / or a partial hydrolysis condensate thereof, and a sol-gel reaction described later. The solvent used when mixing the component (Z) of the catalyst for use and the solvent used when mixing the metal oxide precursor (W) described later are included.

  The water is not particularly limited, and distilled water, ion exchange water, city water, industrial water, and the like can be used, but it is preferable to use distilled water or ion exchange water.

  The organic solvent that dissolves part or all of water is not particularly limited as long as it is an organic solvent having an affinity for water and can disperse the water-insoluble polymer. For example, methanol, ethanol, propyl alcohol , Isopropyl alcohol, acetone, acetonitrile, dimethyl sulfoxide, dimethylformamide, dimethylimidazolidinone, ethylene glycol, tetraethylene glycol, dimethylacetamide, N-methyl-2-pyrrolidone, tetrahydrofuran, dioxane, methyl ethyl ketone, cyclohexanone, cyclopentanone, 2 -Methoxyethanol (methyl cellosolve), 2-ethoxyethanol (ethyl cellosolve), ethyl acetate, etc. are mentioned. Among these, methanol, ethanol, propyl alcohol, isopropyl alcohol, acetonitrile, dimethyl sulfoxide, dimethylformamide, acetone, tetrahydrofuran, and dioxane are preferable because of their high affinity with water. When these organic solvents are contained in the mixture, the particle diameter and shape can be controlled when the metal oxide precursor is condensed, and it can be approximated to spherical fine particles of uniform size. Further, as component (W) described later, tetraethoxysilane (TEOS) and tetramethoxysilane (TMOS) are preferable, and therefore alcohols such as ethanol and methanol are particularly preferable.

[Cationic surfactant (Z)]
In step (1) of the present embodiment, a cationic surfactant (Z) is added.
Examples of the cationic surfactant (Z) include simple amine salts, modified amine salts, tetraalkyl quaternary ammonium salts, modified tetraalkyl quaternary ammonium salts, trialkyl benzyl quaternary ammonium salts, modified trialkyl. Examples include benzyl quaternary ammonium salts, alkyl / pyridinium salts, modified alkyl / pyridinium salts, alkyl / quinolinium salts, alkyl / phosphonium salts, and alkyl / sulfonium salts. Tetraalkyl quaternary ammonium salt type surfactants are particularly preferred, and more preferred are cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (CTAC).

  Tetraalkyl quaternary ammonium salt type surfactant attracts anionized metal oxide precursors (silanol anions, etc.) described later, and assists in the formation of a metal oxide layer structure on the surface of water-insoluble polymer particles. However, the core-shell structure of the water-insoluble polymer (core) -metal oxide (shell) can be formed under mild conditions, which is useful for forming metal oxide hollow particles.

In the step (1) of the present embodiment, the amount of the cationic surfactant (Z) used is a weight ratio (X) of the water-insoluble polymer particles (X) to the cationic surfactant (Z): (Z ) In the range of 10: 1 to 1:10, more preferably in the range of 8: 1 to 1: 8.
By adjusting to this range, organic-inorganic composite particles can be efficiently prepared in the subsequent step (2).

[Acid catalyst (V)]
In the mixed composition used in the present embodiment, an acidic catalyst is used as necessary in terms of controlling the condensation rate of the metal oxide precursor and forming spherical metal oxide hollow particles. Specific examples include inorganic and organic acids such as hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, succinic acid, tartaric acid, and toluenesulfonic acid. From the viewpoint of reactivity, it is preferable to use an acid catalyst such as hydrochloric acid or nitric acid, which allows the reaction to proceed relatively gently.

When adding the acidic catalyst (V), it can be added while confirming the pH of the mixture. As pH of this mixture, it is preferable to adjust to the range of 1-5, and it is more preferable to adjust to the range of 2-4.
By adjusting to such a pH range, the condensation rate of the metal oxide precursor can be effectively controlled.

[Other ingredients]
In the step (1) of the present embodiment, it is essential to include the cationic surfactant (Z) in the mixture, but other additives may be mixed as long as the object of the present invention is not impaired. it can.

[Process (2)]
In the step (2), the metal oxide precursor (W) is mixed in the mixture obtained in the step (1) and a sol-gel reaction is performed to obtain organic-inorganic composite particles.

[Metal oxide precursor (W)]
Examples of the metal oxide precursor include metal alkoxide and / or a partial hydrolysis condensate thereof, metal halide, metal acetate, metal nitrate, metal sulfate and the like.

The metal alkoxide in this embodiment refers to what is represented by the following formula (12).
(R ¹² ) x ₁ M (OR ¹³ ) y ₁ (12)

In the formula, R ¹² represents a hydrogen atom, an alkyl group (such as a methyl group, an ethyl group, or a propyl group), an aryl group (such as a phenyl group or a tolyl group), or a carbon-carbon double bond-containing organic group (an acryloyl group or a methacryloyl group). And vinyl groups), halogen-containing groups (halogenated alkyl groups such as chloropropyl group and fluoromethyl group), and the like. R ¹³ represents a lower alkyl group having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms. x ₁ and y ₁ represent an integer where x ₁ + y ₁ = 4 and x ₁ is 2 or less. M includes Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi, rare earth metals, and the like can be mentioned. A metal (alkoxide) that becomes a colorless metal oxide by a sol-gel reaction such as Zn, Zr, In, Sn, Ti, Pb, and Hf is preferable. Among these, silicon (Si), aluminum (Al), zirconium (Zr), titanium (Ti) and the like are preferably used, and these may be used in combination. Among these, silicon compounds are relatively inexpensive and easy to obtain, and the reaction proceeds slowly, so that the industrial utility value is high. Further, the metal alkoxide and / or the hydrolysis condensate thereof may be a compound that becomes a metal oxide described later by performing a sol-gel reaction by adding water and a catalyst.

  Specific examples include tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetrapropoxysilane, tetraisopropoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyl Trimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane , Vinyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, p-styryltrimethoxysilane 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3- Examples include alkoxysilanes such as acryloxypropyltriethoxysilane, 3-chloropropyltriethoxysilane, trifluoromethyltrimethoxysilane and trifluoromethyltriethoxysilane, and alkoxyaluminum, alkoxyzirconium and alkoxytitanium corresponding to these.

Furthermore, in addition to these metal alkoxides, metal alkoxides having various functional groups at R ¹² as shown in the following 1) to 4) can also be used.
1) 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxy Silane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, 3-aminopropyldimethylethoxysilane, 2- (2-aminoethylthioethyl) triethoxysilane P-aminophenyltrimethoxysilane, N-phenyl-3-aminopropylmethyldimethoxysilane, N-phenyl-3-aminopropylmethyldiethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl- 3-amino Compound having amino group and alkoxysilyl group such as propyltriethoxysilane 2) 3-glycidoxypropylpropyldimethoxysilane, 3-glycidoxypropylpropyldiethoxysilane, 3-glycidoxypropylmethyldiethoxysilane Compounds having glycidyl group and alkoxysilyl group such as 3) Compounds having thiol group and alkoxysilyl group such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane 4) 3-ureidopropyltrimethoxysilane Compounds having a ureido group and an alkoxysilyl group such as

  In the present embodiment, as the metal alkoxide, in the above formula (12), M is alkoxysilane in which silicon (Si) is M, alkoxyzirconium in which M is zirconium (Zr), alkoxyaluminum in which M is aluminum (Al), and Alkoxy titanium where M is titanium (Ti) is preferred.

The partially hydrolyzed condensate of metal alkoxide is a compound obtained by polycondensation of one or more metal alkoxides partially hydrolyzed using an acidic catalyst (V). It is a partially hydrolyzed polycondensation compound of alkoxide.
In this embodiment, the partial hydrolysis condensate of metal alkoxide is preferably an alkoxysilane condensate, an alkoxyzirconium condensate, an alkoxyaluminum condensate, or an alkoxytitanium condensate.

As a metal halide in this embodiment, what is represented by following formula (13) can be used.
(R ¹⁴ ) x ₂ MZy ₂ (13)

In the formula, R ¹⁴ represents a hydrogen atom, an alkyl group (such as a methyl group, an ethyl group, or a propyl group), an alkoxy group (such as a methoxy group, an ethoxy group, a propoxy group, or a butoxy group), an aryl group (such as a phenyl group or a tolyl group). ), A carbon-carbon double bond-containing organic group (acryloyl group, methacryloyl group, vinyl group and the like), a halogen-containing group (halogenated alkyl group such as chloropropyl group and fluoromethyl group) and the like. Z represents F, Cl, Br, or I. x ₂ and y ₂ represent an integer where x ₂ + y ₂ ≦ 4 and x ₂ is 2 or less. M includes Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Nb, Zr, Mo, Examples include Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi, rare earth metals, and the like that can be used for a wide range of applications such as optical materials. Therefore, a metal (alkoxide) that becomes a colorless metal oxide by a sol-gel reaction such as Si, Al, Zn, Zr, In, Sn, Ti, Pb, and Hf is preferable. Among these, silicon (Si), aluminum (Al), zirconium (Zr), titanium (Ti) and the like are preferably used, and these may be used in combination.

  Specific examples include tetrachloro-dimethyldisilane, chloropropyldichloromethylsilane, chloromethyl (dichloro) methylsilane, di-tert-butyldichlorosilane, dibutyldichlorosilane, dichloro (methyl) -n-octylsilane, dichloro (methyl). ) Phenylsilane, dichlorocyclohexylmethylsilane, dichlorodiethylsilane, dichlorodihexylsilane, dichlorodiisopropylsilane, dichlorodimethylsilane, dichlorodiphenylsilane, dichloroethylsilane, dichlorohexylmethylsilane, dichloromethylsilane, dichloromethylvinylsilane, tetrachlorosilane, 1 , 2-bis (trichlorosilyl) ethane, 3-chloropropyltrichlorosilane, allyltrichlorosilane, butyltrichlorosila , Cyclohexyltrichlorosilane, ethyltrichlorosilane, hexachlorodisilane, phenyltrichlorosilane, texyltrichlorosilane, trichloro (methyl) silane, trichloro (propyl) silane, trichlorohexylsilane, trichlorosilane, trichlorovinylsilane, their corresponding fluorosilanes, Bromosilanes, iodosilanes, and the corresponding aluminum halides, zirconium halides, titanium halides, cobalt halides, lithium halides, barium halides, iron halides, manganese halides and hydrates thereof Can be mentioned.

  In this embodiment, examples of the metal acetate include cobalt acetate, cobalt acetoacetate, lithium acetate, lithium acetoacetate, iron acetate, iron acetoacetate, manganese acetate, manganese acetoacetate, and hydrates thereof. Examples of the metal nitrate include cobalt nitrate, lithium nitrate, iron nitrate, manganese nitrate, and hydrates thereof. Examples of the metal sulfate include titanium sulfate, zirconium sulfate, indium sulfate, zinc sulfate, selenium sulfate, antimony sulfate, tin sulfate, yttrium sulfate, and hydrates thereof.

  As the component (W), a metal alkoxide and / or a partially hydrolyzed condensate thereof is preferable in the application of the present embodiment. As the metal alkoxide, an alkoxysilane is more preferable, and tetraethoxysilane (TEOS) is particularly easy to handle. ), Tetramethoxysilane (TMOS) is particularly preferred.

[Mixing ratio of component (X) to component (W)]
The mixing ratio of the water-insoluble polymer particles (X) and the metal oxide precursor (W) is not particularly limited, but is preferably 1:10 to 10: 1 by weight. When there are many components (X), since the abundance ratio of a metal oxide falls, control of a hollow structure becomes difficult, and since a wall becomes thin, mechanical strength falls. When the amount of the component (W) is large, the ratio of the presence of pores is low, so that the surface area and the porosity are small and the performance as a hollow cannot be expected. The organic solvent (Y) that dissolves water and / or a part or all of water is preferably 30 parts by weight or more and 100000 parts by weight or less, more preferably 50 parts by weight or less with respect to 100 parts by weight of the metal oxide precursor (W). It is 50000 parts by weight or less. If the proportion of the component (Y) is low, the particles tend to aggregate, and if it is large, it is not preferable from the viewpoint of production efficiency. In addition, the ratio of water and the solvent in the component (Y) is not particularly limited, but the ratio of water is preferably 10 to 100%. When there is little water, the sol-gel reaction rate of a metal oxide precursor condensate will fall remarkably. As described above, the mixing ratio of the water-insoluble polymer particles (X) and the cationic surfactant (Z) is 10: 1 to 1:10 by weight, preferably 8: 1 to 1: 8. By adjusting to this range, the metal oxide precursor can be attracted moderately, and the metal oxide layer structure can be effectively formed on the surface of the water-insoluble polymer particles. It is inferred that a core-shell structure can be formed from (core) -metal oxide (shell).

  The acidic catalyst (V) is preferably 10 parts by weight or more and 1000 parts by weight or less with respect to 100 parts by weight of the metal oxide precursor (W). By controlling the ratio of the component (V) within this range, the sol-gel reaction can be performed smoothly without excessively increasing the particle size of the organic-inorganic composite particles.

Note that the sol-gel reaction rate of the metal oxide precursor condensate can be accelerated by physical treatment such as ultrasonic (US) treatment. In that case, component (V) is not essential. The mechanism by which ultrasonic waves promote the sol-gel reaction is not necessarily clear, but it seems that cavitation (cavitation phenomenon) generated by ultrasonic waves is involved. In addition, the preferable frequency range of an ultrasonic wave is 20-10,000 kHz.
A preferable irradiation time is preferably 10 minutes or more, more preferably 15 minutes or more.

  A preferable reaction temperature for the sol-gel reaction of the component (W) is, for example, 1 ° C. or more and 200 ° C. or less, preferably 10 ° C. or more and 150 ° C. or less, more preferably 20 ° C. or more and 100 ° C. or less. By setting the reaction temperature within this range, it is possible to ensure an appropriate reaction rate and lead to organic-inorganic composite particles without causing variations in particle diameter and shape. The reaction time is preferably from 10 minutes to 72 hours, more preferably from 1 hour to 24 hours, from the viewpoint of yield and production efficiency. Although the sol-gel reaction of the component (W) proceeds under atmospheric pressure, it may be performed under high pressure using an autoclave or the like.

Organic-inorganic composite particles are formed by the progress of the sol-gel reaction of the metal oxide precursor condensate. FIG. 1 is a schematic cross-sectional view showing organic-inorganic composite particles having a core-shell structure according to an embodiment.
The obtained organic-inorganic composite particles are taken out from the reaction solution by a method such as centrifugation or concentration by ultrafiltration. In order to complete the sol-gel reaction, the extracted organic-inorganic composite particles are washed and removed with a sol-gel reaction catalyst and water with an organic solvent, and then sufficiently dried. Incidentally, the sol - The state in which the gel reaction is complete, is a state where all ideally formed a bond M-O-M, part alkoxyl group (M-OR 2), the ^M-OH groups Although it remains, it includes a state in which it has shifted to a solid (gel) state.

[Step (3)]
In step (3), the water-insoluble polymer particles are removed from the organic-inorganic composite particles to prepare metal oxide hollow particles.

Methods for removing water-insoluble polymer particles include decomposition and removal by firing, VUV light (vacuum ultraviolet light), far-infrared radiation, microwave, plasma irradiation and removal, solvent and water extraction. The method of removing is mentioned. When decomposing and removing by firing, a preferable temperature is 200 ° C to 1000 ° C, more preferably 300 ° C to 700 ° C. If the calcination temperature is too low, the water-insoluble polymer particles are not removed, while if it is too high, the pores may collapse due to being close to the melting point of the metal oxide. Firing may be performed at a constant temperature, or may be gradually raised from room temperature. The firing time can be changed according to the temperature, but it is preferably performed in the range of 1 hour to 24 hours. Firing may be performed in air or in an inert gas such as nitrogen or argon. Moreover, you may carry out under reduced pressure or in a vacuum. In the case of removing by decomposition by irradiation with VUV light, a VUV lamp, an excimer laser, or an excimer lamp can be used. May be used in combination with oxidation action of ozone (O ₃₎ generated at the time of irradiating the VUV light in air. As the microwave, any frequency of 2.45 GHz or 28 GHz may be used. The output of the microwave is not particularly limited, and a condition for removing the water-insoluble polymer particles is selected.

  When extraction is performed using a solvent or water, for example, ethylene glycol, tetraethylene glycol, isopropyl alcohol, acetone, acetonitrile, methanol, ethanol, cyclohexane, dimethyl sulfoxide, dimethylformamide, dimethylimidazolidinone, xylene, toluene , Chloroform, dichloromethane and the like can be used. The extraction operation may be performed under heating. Further, ultrasonic (US) treatment may be used in combination. In addition, after performing extraction operation, in order to remove the water | moisture content and solvent which remain | survive in a pore, it is preferable to heat-process under reduced pressure.

  In order to improve dispersion stability in a solvent and water, the metal oxide hollow particles may coexist with an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant, and the like.

  Metal oxide hollow particles are organic materials represented by silane coupling agents, in order to improve dispersion stability in solvents and water, or to improve compatibility with binder resins and improve mechanical strength and water resistance. You may surface-treat with a silicon compound (surface treatment agent).

  The surface treatment may be carried out by a known method. Examples of the silane coupling agent include methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane. , Vinyltrichlorosilane, vinyltriacetoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltris (2-methoxyethoxy) silane, 3-chloropropyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, 2- (3,4-epoxy Chlohexyl) ethyltrimethoxysilane, 5,6-epoxyhexyltriethoxysilane, 3-ethyl-3- [3- (triethoxysilyl) propoxymethyl] oxetane, N-phenyl-γ-aminopropyltrimethoxysilane, hexamethyl Disilazane and the like are preferably used. Particularly when the polymerizable monomer is a cationic polysynthetic monomer, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldiethoxysilane, which is a silane coupling agent having a cationic polymerizable functional group, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 5,6-epoxyhexyltriethoxysilane, 3-ethyl-3- [3- (triethoxysilyl) propoxymethyl] oxetane and the like are desirable. The silane coupling agent can be used alone or in combination of two or more.

[Method for evaluating metal oxide hollow particles]
The particle size and particle size distribution of the metal oxide hollow particles obtained in this embodiment are determined by measuring the volume distribution of the particle size of particles dispersed in water using a dynamic light scattering method (particle size distribution meter / Nanotrack WAVE). be able to.
The inner diameter of the metal oxide hollow particles can be determined by TEM observation, and can be obtained as an average value of the actually measured inner diameters by arbitrarily extracting 50 particles from the TEM image.
The specific surface area of the metal oxide hollow particles can be measured by a nitrogen adsorption method, and specifically, can be measured using a surface area measuring apparatus BELSORP-max manufactured by Nippon Bell Co., Ltd.

<Resin composition>
The metal oxide hollow particles of the present embodiment can be used as they are for various applications described later, and can also be used as a resin composition containing metal oxide hollow particles and a binder resin. Hereinafter, the resin composition will be described.

<Binder resin>
In the present embodiment, the binder resin refers to a resin that can bond metal oxide hollow particles or can be a medium for uniformly dispersing metal oxide hollow particles.
There is no restriction | limiting in particular in binder resin which can be used by this embodiment. Examples thereof include a thermosetting resin that is cured by heating, a photocurable resin that is cured by irradiation with light such as ultraviolet rays, a thermoplastic resin, and a water-soluble resin. Of these, polyolefin-based, poly (meth) acrylic acid ester-based, polystyrene-based, polyurethane-based, polyvinyl alcohol-based, and polyvinyl acetal-based resins having film-forming properties are preferable.

  Examples of the thermosetting resin and the photocurable resin include epoxy resins, unsaturated polyester resins, phenol resins, urea / melamine resins, polyurethane resins, silicone resins, diallyl phthalate resins, thermosetting polyimide resins, and the like.

  Examples of the epoxy resin include various epoxy resins such as glycidyl ether type, glycidyl ester type, glycidyl amine type, cycloaliphatic type, novolak type, naphthalene type, dicyclopentadiene type such as bisphenol A type epoxy resin. Unsaturated polyester resins include orthophthalic acid, isophthalic acid, terephthalic acid, alicyclic unsaturated acid, fatty saturated acid, bisphenol, halogenated acid, and halogenated bisphenol. A polyester resin is mentioned. Examples of the phenolic resin include phenolic resins such as a resol type and a novolac type.

  Thermoplastic resins include polyolefin resin, polyvinyl chloride resin, vinylidene chloride resin, polystyrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, styrene block copolymer resin, methacrylic resin, polyvinyl Alcohol resin (PVA), polyvinyl acetal resin (PVB), polyacetal resin, polyamide resin, polycarbonate resin, modified polyphenylene ether resin, thermoplastic polyester resin, fluororesin, polyphenylene sulfide resin, polysulfone resin, amorphous arylate resin, polyetherimide Resin, polyethersulfone resin, polyetherketone resin, liquid crystal polymer resin, polyamideimide resin, thermoplastic polyimide resin, syndiopolis Ren resin and the like.

  Polyolefin resins include polyethylene resin, polypropylene resin, α-olefin copolymer resin, polybutene-1 resin, polymethylpentene resin, cyclic olefin polymer resin, ethylene / vinyl acetate copolymer resin, ethylene / methacrylic acid copolymer. Examples thereof include resins and ionomers.

  Examples of the polyamide resin include nylon 6, nylon 66, nylon 11, nylon 12, and the like.

  Examples of the thermoplastic polyester resin include polyethylene terephthalate resin, polybutylene terephthalate resin, polybutylene succinate resin, and polylactic acid resin.

  Fluororesin includes polytetrafluoroethylene resin, perfluoroalkoxyalkane resin, perfluoroethylene propene copolymer resin, ethylene / tetrafluoroethylene copolymer resin, polyvinylidene fluoride resin, polychlorotrifluoroethylene resin, ethylene / chlorotrifluoroethylene Examples thereof include a copolymer resin, a tetrafluoroethylene / perfluorodioxole copolymer resin, and a polyvinyl fluoride resin.

  Examples of the water-soluble resin include polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG), and derivatives thereof.

  Polyolefin, poly (meth) acrylate, polystyrene, and polyurethane resins having film-forming properties are polymer particles having a particle diameter of 10 to 300 μm, and are transparent after heating at room temperature or 100 ° C. or less. What forms a thick coating film is preferable.

  Among the above binder resins, from the viewpoint of dispersibility and versatility of the metal oxide hollow particles, an epoxy resin, a phenol resin, a polyimide resin, a polyolefin resin, a water-soluble resin, and a resin having the above-described film-forming properties are preferable. . Binder resin can be used individually by 1 type or in mixture of 2 or more types.

The weight average molecular weight of the binder resin is preferably 200 to 100,000, and more preferably 500 to 80,000.
In light of the performance of heat insulation, the content of the binder resin is preferably 30 to 95% by weight, more preferably 40 to 90% by weight, and the content of the metal oxide hollow particles of the present embodiment is 70 to 5% by weight. % Is preferable, and 60 to 10% by weight is more preferable.

The method for dispersing the metal oxide hollow particles in the binder resin is not particularly limited, and known methods can be applied. For example, the following dispersion methods can be used.
Note that a binder resin and a dispersion medium such as an organic solvent and water may be mixed to form an emulsion.

(1) Binder resin (or emulsion thereof) and metal oxide hollow particles are melt-kneaded with a kneader in the presence of a solvent and / or dispersant as necessary, and metal oxide hollow particles (weight reduction) are made in the binder resin. A method of obtaining a master batch in which a filler is dispersed.
As the kneader, a bead mill mixer, a three-roll mill mixer, a homogenizer mixer, a lab plast mill mixer, or the like can be used.
(2) Metal oxide hollow particles dispersed in water are wet-treated by adding a treatment agent, and then solvent-substituted metal oxide hollow particle organosol is added to and mixed with a binder resin (or emulsion thereof). how to.
Examples of the treating agent include organic silicon compounds (surface treating agents) typified by the above-mentioned silane coupling agents, anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants.

<Film, paint film>
A film or a coating film can be obtained from the resin composition of the present embodiment. The thermal conductivity of this film or coating film is preferably 0.1 W / mK or less, more preferably 0.05 W / mK or less. Thereby, the heat insulation efficiency can be improved. Further, the HAZE value when the thickness of the film or coating film when dried is 10 μm is preferably 10% or less, more preferably 5% or less. Thereby, a highly transparent film or coating film is obtained.

The method for creating the film or coating film is not particularly limited, and a known method can be used. For example, the film or coating film is formed as follows.
A coating containing metal oxide hollow particles is coated on a glass substrate by adjusting the thickness using a bar coater. After drying in an oven at a temperature of 50 to 100 ° C. for 1 to 24 hours, the formed film is peeled off from the glass substrate to obtain a metal oxide hollow particle-containing film or coating film.

  The thermal conductivity of the film or coating film of this embodiment can be measured by a laser flash method. Moreover, the HAZE value of the film or coating film of this embodiment can be measured by NDH4000 made by Nippon Denshoku Industries Co., Ltd., when the thickness of the film or coating film when dried is 10 μm. The refractive index of the film can be measured by an Abbe refractometer, and the refractive index of a thin coating film can be measured by an ellipsometer.

<Application>
The metal oxide hollow particles of the present embodiment can be used for pharmaceuticals (DDS: drug delivery system), molecular probes, catalysts, adsorbing materials, sensors, paints, inks and the like.
The resin composition containing the metal oxide hollow particles of the present embodiment can be used for a low dielectric constant material such as a printed circuit board, a special paint or ink containing functional molecules, and the like.
The film or coating film obtained from the resin composition of the present embodiment can be used for heat insulating materials such as window glass heat insulating films or heat insulating paints for automobiles, houses, buildings, etc., antireflection films such as displays and touch panels.

  As mentioned above, although embodiment of this invention was described, these are illustrations of this invention and can employ | adopt various structures other than the above.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to these examples.

(Synthesis example of terminal branched polyolefin copolymer)
Number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) were measured by GPC using the method described in the text. The melting point (Tm) was measured by using DSC (differential scanning calorimetry), and the peak top temperature obtained by measurement was adopted. In addition, although melting | fusing point of a polyalkylene glycol part is also confirmed by measurement conditions, here, unless there is particular notice, it refers to melting | fusing point of a polyolefin part. ¹ H-NMR was measured at 120 ° C. after completely dissolving the polymer in deuterated 1,1,2,2-tetrachloroethane serving as a lock solvent and a solvent in a measurement sample tube. . The chemical shift was determined by setting the peak of deuterated 1,1,2,2-tetrachloroethane to 5.92 ppm and determining the chemical shift value of other peaks. As for the particle diameter of the particles in the dispersion, a 50% volume average particle diameter was measured with Microtrac UPA (manufactured by HONEYWELL). The shape of the particles in the dispersion was observed by diluting the sample 200 to 500 times, negatively staining with phosphotungstic acid, and then using a transmission electron microscope (TEM / H-7650 manufactured by Hitachi, Ltd.) under the condition of 100 kV. I did it.

(Synthesis Example of Terminal Branched Polyolefin Copolymer (T))
A terminal epoxy group-containing ethylene polymer (E) was synthesized according to the following procedure (for example, see Synthesis Example 2 of JP-A-2006-131870).
A stainless steel autoclave with an internal volume of 2000 ml sufficiently purged with nitrogen was charged with 1000 ml of heptane at room temperature, and the temperature was raised to 150 ° C. Subsequently, 30 kg / cm ² G was pressurized with ethylene in the autoclave to maintain the temperature. A hexane solution (1.00 mmol / ml in terms of aluminum atom) of MMAO (manufactured by Tosoh Finechem) was injected with 0.5 ml (0.5 mmol), and then a toluene solution (0.0002 mmol) of a compound represented by the following general formula (14) / Ml) 0.5 ml (0.0001 mmol) was injected to initiate the polymerization. After carrying out the polymerization at 150 ° C. for 30 minutes in an ethylene gas atmosphere, the polymerization was stopped by press-fitting a small amount of methanol. The obtained polymer solution was added to 3 liters of methanol containing a small amount of hydrochloric acid to precipitate a polymer. After washing with methanol, it was dried under reduced pressure at 80 ° C. for 10 hours to obtain a single-end double bond-containing ethylene polymer (P).

In a 500 ml separable flask, 100 g of the ethylene polymer (P) containing one end double bond (Mn850, vinyl group 108 mmol), 300 g of toluene, 0.85 g (2.6 mmol) of Na ₂ WO ₄ , CH ₃ (nC ₈ H ₁₇ ) ₃ NHSO ₄ (0.60 g, 1.3 mmol) and phosphoric acid (0.11 g, 1.3 mmol) were charged, and the mixture was heated to reflux with stirring for 30 minutes to completely melt the polymer. After the internal temperature was set to 90 ° C., 37 g (326 mmol) of 30% hydrogen peroxide solution was added dropwise over 3 hours, and the mixture was stirred at an internal temperature of 90 to 92 ° C. for 3 hours. Thereafter, 34.4 g (54.4 mmol) of a 25% aqueous sodium thiosulfate solution was added while maintaining the temperature at 90 ° C., and the mixture was stirred for 30 minutes. The peroxide in the reaction system was completely decomposed with the peroxide test paper. It was confirmed. Subsequently, 200 g of dioxane was added at an internal temperature of 90 ° C. to crystallize the product, and the solid was collected by filtration and washed with dioxane. The obtained solid was stirred in a 50% aqueous methanol solution at room temperature, and the solid was collected by filtration and washed with methanol. Further, the solid was stirred in 400 g of methanol, collected by filtration and washed with methanol. By drying under reduced pressure of room temperature and 1-2 hPa, 96.3 g of white solid of terminal epoxy group-containing ethylene polymer (E) was obtained (yield 99%, polyolefin conversion rate 100%).
The obtained terminal epoxy group-containing ethylene polymer (E) was Mw = 2058, Mn = 1118, Mw / Mn = 1.84 (GPC) (terminal epoxy group content: 90 mol%).
¹ H-NMR: δ (C ₂ D ₂ Cl ₄ ) 0.88 (t, 3H, J = 6.92 Hz), 1.18-1.66 (m), 2.38 (dd, 1H, J = 2.64, 5.28 Hz), 2.66 (dd, 1H,) J = 4.29, 5.28 Hz), 2.80-2.87 (m, 1H)
Melting point (Tm) 121 ° C

A 1000 mL flask was charged with 84 parts by weight of a terminal epoxy group-containing ethylene polymer (E), 39.4 parts by weight of diethanolamine, and 150 parts by weight of toluene, and stirred at 150 ° C. for 4 hours. Thereafter, acetone was added while cooling to precipitate the reaction product, and the solid was collected by filtration. The obtained solid was stirred and washed once with an aqueous acetone solution and further three times with acetone, and then the solid was collected by filtration. Thereafter, the polymer (I) (Mn = 1223, A: group formed by polymerization of ethylene (Mn = 1075) in the following general formula (9) (Mn = 1075), R ¹ = R ² by drying under reduced pressure at room temperature. = Hydrogen atom, ^one of Y ¹ and Y ² is a hydroxyl group, and the other is a bis (2-hydroxyethyl) amino group.
¹ H-NMR: δ (C ₂ D ₂ Cl ₄ ) 0.88 (t, 3H, J = 6.6 Hz), 0.95-1.92 (m), 2.38-2.85 (m, 6H), 3.54-3.71 (m, 5H)
Melting point (Tm) 121 ° C

  A 500 mL flask equipped with a nitrogen introduction tube, a thermometer, a cooling tube, and a stirrer is charged with 20.0 parts by weight of polymer (I) and 100 parts by weight of toluene and heated in an oil bath at 125 ° C. while stirring to obtain a solid. Was completely dissolved. After cooling to 90 ° C., 0.323 parts by weight of 85% KOH previously dissolved in 5.0 parts by weight of water was added to the flask and mixed for 2 hours under reflux conditions. Thereafter, water and toluene were distilled off while gradually raising the temperature in the flask to 120 ° C. Further, while supplying a slight amount of nitrogen to the flask, the pressure in the flask was reduced, and the internal temperature was raised to 150 ° C. and maintained for 4 hours to further distill off water and toluene in the flask. After cooling to room temperature, the solidified solid in the flask was crushed and taken out.

A stainless steel 1.5 L pressure reactor equipped with a heating device, a stirring device, a thermometer, a pressure gauge, and a safety valve was charged with 18.0 parts by weight of the obtained solid and 200 parts by weight of dehydrated toluene. After substituting with nitrogen, the temperature was raised to 130 ° C. with stirring. After 30 minutes, 9.0 parts by weight of ethylene oxide was added, and the mixture was further maintained at 130 ° C. for 5 hours, and then cooled to room temperature to obtain a reaction product. The solvent is removed from the obtained reaction product by drying, and a terminal branched polyolefin copolymer (T-33) (Mn = 1835, in general formula (1), A: a group formed by polymerization of ethylene (Mn = 1075)).
Moreover, the terminal branched polyolefin copolymer (T-50) is changed by changing the addition amount of ethylene oxide in the preparation method of the above-mentioned terminal branched polyolefin copolymer (T-33) to 18.0 parts by weight. (Mn = 2446, A in the general formula (1): a group formed by polymerization of ethylene (Mn = 1075)) was obtained.
In both T-33 and T-50, R ¹ = R ² = hydrogen atom, ^one of X ¹ and X ² is a group represented by general formula (6) (X ¹¹ = polyethylene glycol group), and the other is represented by general formula (5 ) (Q ¹ = Q ² = ethylene group, X ⁹ = X ¹⁰ = polyethylene glycol group).
¹ H-NMR: δ (C ₂ D ₂ Cl ₄ ) 0.88 (3H, t, J = 6.8 Hz), 1.06-1.50 (m), 2.80-3.20 (m) 3.33-3.72 (m)
Melting point (Tm; T-33) -16 ° C. (polyethylene glycol), 116 ° C.
Melting point (Tm; T-50) -16 ° C. (polyethylene glycol), 116 ° C.

<Preparation Example of Terminal Branched Polyolefin Copolymer Particle Aqueous Dispersion>
(Preparation of 20% by weight terminal branched polyolefin copolymer (T) aqueous dispersion)
10 parts by weight of the terminally branched polyolefin copolymer (T-33) obtained in the above synthesis example and 40 parts by weight of distilled water of the solvent (C) were charged into a 100 ml autoclave at 140 ° C. and a speed of 800 rpm. After stirring for 30 minutes, the mixture was cooled to room temperature while maintaining stirring. As a result of measuring the particle diameter of the obtained dispersion system with a dynamic light scattering nanotrack particle size analyzer “Microtrack UPA-EX150 (manufactured by Nikkiso Co., Ltd.)”, the 50% volume average particle diameter was 0.018 μm. (Volume 10% average particle diameter 0.014 μm, volume 90% average particle diameter 0.022 μm). The particle diameter measured from the transmission electron microscope observation result of the obtained dispersion was 0.015-0.030 μm. Also, an aqueous dispersion of the terminal branched polyolefin copolymer (T-50) obtained in the above synthesis example was prepared in the same manner as T-33. As a result of measuring the particle diameter of the obtained dispersion under the same conditions as described above, the 50% volume average particle diameter was 0.017 μm (volume 10% average particle diameter 0.013 μm, volume 90% average particle diameter). 0.024 μm). The particle diameter measured from the transmission electron microscope observation result of the obtained dispersion was 0.015-0.030 μm.

Example 1
0.42 ml of an aqueous dispersion of a terminal branched polyolefin copolymer (T-33) prepared to 15% by weight and 0.015 g of cetyltrimethylammonium bromide (CTAB) were previously dispersed in 60 ml of water and mixed with stirring for 30 minutes. . Hydrochloric acid was gradually added as an acid catalyst to adjust the pH of the solution to about 2.3. Subsequently, 1.5 g of tetraethoxysilane (TEOS) was added. The temperature of the mixture was raised to 80 ° C. and stirred for 3 hours. Thereafter, it was stored in an oven at 80 ° C. for 24 hours. The obtained liquid was centrifuged, and the obtained solid was washed with water and ethanol three times and sufficiently dried in an oven. The obtained powder was baked using an electric furnace at 600 ° C. for 4 hours, and the terminal branched olefin copolymer particles were removed to obtain the desired silica hollow particles.
From the measurement by DLS, silica hollow particles having a volume 50% average particle diameter of 20 nm, D90 / D50 of 1.33, and pores having an average diameter of 18 nm inside are obtained from TEM observation (FIG. 3). I understood. When the pore structure was examined by the nitrogen adsorption method, it was found that the BET specific surface area was 432 m ² / g and the porosity was 1.2 cm ³ / g.

(Example 2)
0.42 ml of an aqueous dispersion of a terminal branched polyolefin copolymer (T-33) prepared to 15% by weight and 0.015 g of cetyltrimethylammonium bromide (CTAB) were previously dispersed in 20 ml of water and mixed with stirring for 30 minutes. . Subsequently, 1.5 g of tetraethoxysilane (TEOS) was added. Subsequently, the mixed solution was subjected to ultrasonic treatment (US) for 15 minutes under the condition of 37 kHz using an ultrasonic processing device Elmasonic S120. Thereafter, it was stored in an oven at 40 ° C. for 24 hours. The obtained liquid was subjected to ultrafiltration, and the obtained solid was washed with water and ethanol three times and sufficiently dried in an oven. The obtained powder was baked using an electric furnace at 600 ° C. for 4 hours, and the terminal branched olefin copolymer particles were removed to obtain the desired silica hollow particles.
From the measurement by DLS, silica hollow particles having a volume 50% average particle diameter of 20 nm, D90 / D50 of 1.38, and pores having an average diameter of 18 nm inside are obtained from TEM observation (FIG. 4). I understood. When the pore structure was examined by the nitrogen adsorption method, it was found that the BET specific surface area was 404 m ² / g and the porosity was 0.8 cm ³ / g.

(Example 3)
0.68 ml of an aqueous dispersion of a terminal branched polyolefin copolymer (T-50) prepared to 15% by weight and 0.015 g of cetyltrimethylammonium bromide (CTAB) were previously dispersed in 20 ml of water and mixed with stirring for 30 minutes. . Hydrochloric acid was gradually added as an acid catalyst to adjust the pH of the solution to about 2.3. Subsequently, 0.78 g of tetraethoxysilane (TEOS) was added. The temperature of the mixture was raised to 80 ° C. and stirred for 3 hours. Thereafter, it was stored in an oven at 80 ° C. for 24 hours. The obtained liquid was centrifuged, and the obtained solid was washed with water and ethanol three times and sufficiently dried in an oven. The obtained powder was baked using an electric furnace at 600 ° C. for 4 hours, and the terminal branched olefin copolymer particles were removed to obtain the desired silica hollow particles.

Example 4
0.42 ml of an aqueous dispersion of a terminal branched polyolefin copolymer (T-50) prepared to 15% by weight and 0.015 g of cetyltrimethylammonium bromide (CTAB) were previously dispersed in 20 ml of water and mixed with stirring for 30 minutes. . Subsequently, 1.5 g of tetraethoxysilane (TEOS) was added. Subsequently, the mixed solution was subjected to ultrasonic treatment (US) for 15 minutes under the condition of 37 kHz using an ultrasonic processing device Elmasonic S120. Thereafter, it was stored in an oven at 40 ° C. for 24 hours. The obtained liquid was subjected to ultrafiltration, and the obtained solid was washed with water and ethanol three times and sufficiently dried in an oven. The obtained powder was baked using an electric furnace at 600 ° C. for 4 hours, and the terminal branched olefin copolymer particles were removed to obtain the desired silica hollow particles.

(Comparative Example 1)
Silica hollow particles were obtained in the same manner as in Example 1 except that cetyltrimethylammonium bromide (CTAB) was not added. From TEM observation (FIG. 5), many particles having no hollow structure were observed.

According to the production method of the present invention, organic-inorganic composite particles having a controlled particle size can be prepared under relatively mild conditions, whereby a metal having a small average particle size and a narrow particle size distribution. Oxide hollow particles can be obtained.
Since the metal oxide hollow particles obtained in this way are excellent in transparency even when mixed with a resin, they can be applied to optical materials, low dielectric constant materials, and heat insulating materials. Drug delivery systems), molecular probes, catalysts, adsorbent materials, sensors, paints, inks, etc.

Claims (8)

Water and / or an organic solvent that dissolves part or all of water, water-insoluble polymer particles (X) having a 50% volume average particle size of 5 nm to 30 nm and a cationic surfactant (Z), in a weight ratio (X): Step (1) for obtaining a mixture in which (Z) is 10: 1 to 1:10;
Mixing the mixture and the metal oxide precursor, and performing a sol-gel reaction of the metal oxide precursor to obtain organic-inorganic composite particles;
A method for producing metal oxide hollow particles, comprising a step (3) of removing the water-insoluble polymer particles (X) from the organic-inorganic composite particles, wherein the 50% volume average particle diameter is 10 nm or more and 50 nm or less.   The method for producing metal oxide hollow particles according to claim 1, wherein the mixture of the step (1) further contains an acidic catalyst.   Step (2) is a step of mixing the mixture and the metal oxide precursor, subjecting the mixture to ultrasonic treatment, and then performing a sol-gel reaction of the metal oxide precursor to obtain organic-inorganic composite particles. The method for producing metal oxide hollow particles according to claim 1, wherein The water-insoluble polymer particles are particles composed of a terminal branched polyolefin copolymer represented by the following general formula (1) and having a number average molecular weight of 2.5 × 10 ⁴ or less. The manufacturing method of the metal oxide hollow particle as described in any one of.
(In the formula, A represents a polyolefin chain. R ¹ and R ² represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. X ¹ and X ² are the same. Or, differently, it represents a group containing a linear or branched polyalkylene glycol group.) X ¹ and X ^{2 of the} terminally branched polyolefin-based copolymer represented by the general formula (1) are the same or different, and the general formula (2)
(In the formula, E represents an oxygen atom or a sulfur atom, and X ³ represents a polyalkylene glycol group or a general formula (3)
(In the formula, R ³ represents an m + 1 valent hydrocarbon group. G is the same or different and is represented by —OX ⁴ , —NX ⁵ X ⁶ (X ^{4 to} X ⁶ represent a polyalkylene glycol group). M represents the number of bonds between R ³ and G, and represents an integer of 1 to 10). )
Or general formula (4)
(Wherein X ⁷ and X ⁸ are the same or different and represent a polyalkylene glycol group or a group represented by the general formula (3)). A method for producing metal oxide hollow particles. The method for producing metal oxide hollow particles according to claim 4 or 5, wherein the terminally branched polyolefin-based copolymer is represented by the following general formula (1a) or general formula (1b).
(In the formula, R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. R ⁶ and R ⁷ represent a hydrogen atom or a methyl group, At least one of them is a hydrogen atom, R ⁸ and R ⁹ represent a hydrogen atom or a methyl group, and at least one of them is a hydrogen atom, l + m represents an integer of 2 to 450, n is 20 Represents an integer of 300 or more.)
(In the formula, R ⁴ and R ⁵ represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and at least one of them is a hydrogen atom. R ⁶ and R ⁷ represent a hydrogen atom or a methyl group, At least one of them is a hydrogen atom, R ⁸ and R ⁹ represent a hydrogen atom or a methyl group, at least one of them is a hydrogen atom, R ¹⁰ and R ¹¹ represent a hydrogen atom or a methyl group, (At least one of them is a hydrogen atom. L + m + o represents an integer of 3 to 450, and n represents an integer of 20 to 300.)   The method for producing metal oxide hollow particles according to any one of claims 1 to 6, wherein the cationic surfactant (Z) is a tetraalkyl quaternary ammonium salt type surfactant.   The method for producing metal oxide hollow particles according to claim 7, wherein the tetraalkyl quaternary ammonium salt type surfactant is cetyltrimethylammonium bromide (CTAB) or cetyltrimethylammonium chloride (CTAC).