JP2015048299A - METHOD FOR PRODUCING MESOPOROUS SILICA AND METHOD FOR PRODUCING Si-CONTAINING AQUEOUS DISPERSION - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a Si-containing aqueous dispersion which can suppress dissolution of a substrate comprising a resin such as triacetyl cellulose and the like, and from which homogeneous mesoporous silica can be produced; and to provide a method for producing mesoporous silica using the Si-containing aqueous dispersion.SOLUTION: A method for producing mesoporous silica comprises: a first step of obtaining a Si-containing aqueous dispersion by adding a Si-containing compound having a structure represented by Si-O into an aqueous dispersion of a block copolymer (Z) containing a polymer block (S), which contains a structural unit derived from an aromatic vinyl compound and having a sulfonic acid group, and an amorphous polymer block (T) containing a structural unit derived from an unsaturated aliphatic hydrocarbon as constituent components; a second step of obtaining a solid by removing water from the Si-containing aqueous dispersion obtained; and a third step of removing the block copolymer (Z) from the solid.

Description

  The present invention relates to a method for producing mesoporous silica and a method for producing a Si-containing aqueous dispersion. Specifically, the present invention can be used for the production of mesoporous silica useful for an antireflection film for a liquid crystal display element, etc., a method for producing a Si-containing aqueous dispersion, and a mesoporous silica using the Si-containing aqueous dispersion. It relates to a manufacturing method.

  Porous silica having pores with a pore diameter of 2 to 50 nm is called mesoporous silica, and its use for applications such as an antireflection film has been studied in recent years.

As a means for obtaining mesoporous silica, a precursor selected from alkoxysilane and / or a partially hydrolyzed condensate thereof in the presence of particles composed of a terminal branched copolymer having a number average molecular weight of 2.5 × 10 ⁴ or less is used. After obtaining an organic-inorganic composite by carrying out a sol-gel reaction in the presence of an acid catalyst, the organic-inorganic composite is calcined, irradiated with energy rays (vacuum ultraviolet light, far-infrared light, microwave, plasma, etc.), solvent It is known that mesoporous silica having an average pore diameter of 5 to 30 nm can be obtained by removing the terminal branched copolymer by a method such as washing (see Patent Document 1). In this method, the dispersion of the acid catalyst used for the sol-gel reaction becomes non-uniform, and the homogeneity of the obtained mesoporous silica sometimes decreases.

  Further, a silica precursor aqueous solution prepared by dissolving alkoxysilane in an acidic aqueous solution contains a structural unit derived from an aromatic vinyl compound, a polymer block (S) having a sulfonic acid group, and unsaturated aliphatic carbonization. A fluid composition obtained by mixing an organic solvent solution of a block copolymer (Z) containing an amorphous polymer block (T) containing a structural unit derived from hydrogen as a constituent, It is known that mesoporous silica having a thickness of about 25 nm can be obtained by applying to sinter and baking (see Non-Patent Document 1). In this method, the substrate may be dissolved by the organic solvent in the fluid composition. For example, when manufacturing an antireflection film for a liquid crystal display element, it is considered desirable to use a base material usually made of a resin such as triacetyl cellulose, but the base material made of the resin is made of the fluid composition. In some cases, the desired antireflection film may not be obtained due to dissolution or swelling by application.

International Publication No. 2010-103856

Journal of Material Chemistry (J. Mater. Chem.), Vol. 22, p. 20008 (2012)

  Accordingly, an object of the present invention is to provide a method for producing an Si-containing aqueous dispersion that can suppress swelling and dissolution of a substrate even when applied to a substrate made of a resin and that can produce homogeneous mesoporous silica, and the Si-containing water. An object of the present invention is to provide a method for producing mesoporous silica using a dispersion.

In order to achieve the above object, the present invention provides:
[1] A polymer block (S) containing a structural unit derived from an aromatic vinyl compound and having a sulfonic acid group and an amorphous polymer block containing a structural unit derived from an unsaturated aliphatic hydrocarbon ( In an aqueous dispersion (hereinafter referred to as “polymer aqueous dispersion”) of a block copolymer (Z) having T) as a constituent component (hereinafter simply referred to as “block copolymer (Z)”), A first step of adding a Si-containing compound having a structure represented by Si—O (hereinafter simply referred to as “Si-containing compound”) to obtain a Si-containing aqueous dispersion;
A method for producing mesoporous silica, comprising: a second step of removing water from the obtained Si-containing aqueous dispersion to obtain a solid content; and a third step of removing the block copolymer (Z) from the solid content;
[2] The method for producing mesoporous silica according to the above [1], wherein in the first step, the addition amount of the Si-containing compound is in the range of 0.3 to 20 times by mass of the block copolymer (Z);
[3] The method for producing mesoporous silica according to [1] or [2] above, wherein in the third step, the solid content is irradiated with vacuum ultraviolet light; and [4] The polymer aqueous dispersion is represented by Si—O. A method for producing a Si-containing aqueous dispersion in which a Si-containing compound having a structure is added.

  According to the method for producing mesoporous silica of the present invention using the Si-containing aqueous dispersion obtained by the method of the present invention, the dissolution and swelling of the substrate can be suppressed even when applied to the substrate made of a resin, and homogeneous. New mesoporous silica can be produced.

2 is a cross-sectional SEM image of mesoporous silica obtained in Example 1. FIG.

Hereinafter, the form for inventing is demonstrated along each process in the manufacturing method of mesoporous silica.
[First step]
Hereinafter, the first step will be described. In addition, in the manufacturing method of Si containing water dispersion liquid of this invention, Si containing water dispersion liquid is obtained by the same method as this 1st process.
In the first step, a Si-containing compound is added to the polymer aqueous dispersion.
In this specification, “Si-containing aqueous dispersion” means a liquid in which micelles formed by the block copolymer (Z) are dispersed in an aqueous solution containing a compound containing Si atoms. Such a compound containing Si atoms is a Si-containing compound and / or a reaction product thereof used in the production method of the present invention.

(Polymer aqueous dispersion)
The polymer aqueous dispersion used in the method for producing an Si-containing aqueous dispersion of the present invention is a liquid in which the block copolymer (Z) is dispersed in a dispersion medium mainly composed of water. The water content in the polymer aqueous dispersion is preferably in the range of 85 to 99.5% by mass, and more preferably in the range of 93 to 99% by mass.

  The content of the block copolymer (Z) in the polymer aqueous dispersion is preferably in the range of 0.5 to 15% by mass, and more preferably in the range of 1 to 7% by mass.

  The average dispersed particle size of the block copolymer (Z) in the polymer aqueous dispersion is preferably in the range of 1 to 300 nm, more preferably in the range of 2 to 100 nm, and still more preferably in the range of 5 to 50 nm.

  As a method for preparing such a polymer aqueous dispersion, for example, water is added to the organic solvent solution of the block copolymer (Z) and the mixture is vigorously stirred, and then the organic solvent is removed (transfer emulsification method). Is mentioned.

(Block copolymer (Z))
The block copolymer (Z) used in the present invention contains a polymer unit (S) containing a structural unit derived from an aromatic vinyl compound and having a sulfonic acid group (hereinafter referred to as “polymer block (S)”). ) And an amorphous polymer block (T) containing a structural unit derived from an unsaturated aliphatic hydrocarbon (hereinafter referred to as “polymer block (T)”). The block copolymer (Z) contains a structural unit derived from an aromatic vinyl compound and has no sulfonic acid group (hereinafter referred to as “polymer block (S ₀ )”), It is obtained by introducing a sulfonic acid group into a polymer block (S ₀ ) of a block copolymer (hereinafter referred to as “block copolymer (Z ₀ )”) comprising a combined block (T) as a constituent component. . The aromatic ring included in the aromatic vinyl compound is preferably a carbocyclic aromatic ring such as a benzene ring, a naphthalene ring, an anthracene ring, or a pyrene ring.

Examples of the aromatic vinyl compound that can form the polymer block (S ₀ ) include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, 2,4-dimethylstyrene, 2, Examples include 5-dimethylstyrene, 3,5-dimethylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, vinylbiphenyl, vinylterphenyl, vinylnaphthalene, vinylanthracene, and 4-phenoxystyrene.

  Of the hydrogen atoms on the vinyl group of the aromatic vinyl compound, the hydrogen atom bonded to the α-position carbon (α-carbon) of the aromatic ring may be substituted with another substituent. Examples of the substituent include linear or branched alkyl groups having 1 to 4 carbon atoms (methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert -Butyl group), halogenated alkyl groups having 1 to 4 carbon atoms (chloromethyl group, 2-chloroethyl group, 3-chloroethyl group etc.), aryl groups (phenyl group etc.), and aromatic having such substituents Examples of the vinyl compound include α-methylstyrene, α-methyl-4-methylstyrene, α-methyl-4-ethylstyrene, 1,1-diphenylethylene, and the like.

It is preferable that the aromatic ring of the aromatic vinyl compound constituting the polymer block (S ₀ ) does not have a substituent that inhibits introduction (sulfonated) of a sulfonic acid group. For example, when hydrogen (especially hydrogen at the 4-position) on the aromatic ring of styrene is substituted with an alkyl group (particularly an alkyl group having 3 or more carbon atoms) or the like, sulfonation may be difficult. The above hydrogen is preferably not substituted or substituted with a substituent that can itself be sulfonated, such as an aryl group. From the viewpoint of easiness of sulfonation, styrene, α-methylstyrene, 4 -Methyl styrene, 4-ethyl styrene and vinyl biphenyl are preferred. These aromatic vinyl compounds may be used alone or in combination of two or more. The content of the structural unit derived from the above aromatic vinyl compound is preferably 90% by mass or more, more preferably 95% by mass or more of the polymer block (S ₀ ).

The polymer block (S ₀ ) may contain a structural unit derived from another compound other than the aromatic vinyl compound as long as the effects of the present invention are not impaired. Examples of such other compounds include ethylene, propylene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 1-heptene, 2-heptene, 1-octene, Alkene having 2 to 8 carbon atoms such as 2-octene; butadiene, 1,3-pentadiene, isoprene, 1,3-hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl C4-C8 conjugated dienes such as 1,3-butadiene and 1,3-heptadiene; (meth) acrylic acid such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate Esters: Vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate; methyl vinyl ether, isobutyl Vinyl ethers such as vinyl ether; include polymerizable compounds such as. These other compounds may be used individually by 1 type, or may use 2 or more types together. The content of structural units derived from the other compounds described above is preferably 10% by mass or less, more preferably 5% by mass or less, based on the polymer block (S ₀ ).

The polymer block (S ₀ ) can be produced by polymerizing the above-described aromatic vinyl compound and other compounds as optional components as monomers. When the structural unit contained in the polymer block (S ₀ ) is derived from two or more types of monomers, the polymer is usually subjected to polymerization as a monomer mixture obtained by mixing the two or more types of monomers. The block (S ₀ ) is manufactured.

The number average molecular weight per polymer block (S ₀ ) is preferably in the range of 1,000 to 50,000, more preferably in the range of 3,000 to 40,000, and in the range of 5,000 to 25,000. Is more preferable. When the number average molecular weight is in the range of 1,000 to 50,000, the stability of the micelle formed by the block copolymer (Z) in the Si-containing aqueous dispersion is increased, and the homogeneity of the obtained mesoporous silica is increased. From the viewpoint of increasing
In addition, in this specification, a number average molecular weight means the number average molecular weight of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  The polymer block (T) that is a constituent component of the block copolymer (Z) is an amorphous polymer block containing a structural unit derived from an unsaturated aliphatic hydrocarbon. Here, “amorphous” can be confirmed by measuring the dynamic viscoelasticity of the block copolymer (Z) and confirming that there is no change in the storage elastic modulus derived from the crystalline olefin polymer.

  The unsaturated aliphatic hydrocarbon capable of forming the polymer block (T) is preferably a chain unsaturated aliphatic hydrocarbon having a polymerizable carbon-carbon double bond, such as ethylene, propylene, 1-butene, 2- Alkenes having 2 to 8 carbon atoms such as butene, isobutene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, 1-heptene, 2-heptene, 1-octene, 2-octene; butadiene, 1, 3 -C4-C4 such as pentadiene, isoprene, 1,3-hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-heptadiene 8 conjugated dienes; and the like. When the unsaturated aliphatic hydrocarbon has a plurality of polymerizable carbon-carbon double bonds, any of them may be used for polymerization, for example, when the unsaturated aliphatic hydrocarbon is a conjugated diene. These may be 1,2-bonds or 1,4-bonds, or a mixture thereof. These unsaturated aliphatic hydrocarbons may be used alone or in combination of two or more. The content of the structural unit derived from the unsaturated aliphatic hydrocarbon described above is preferably 90% by mass or more, and more preferably 95% by mass or more of the polymer block (T).

  The polymer block (T) may contain a structural unit derived from another compound other than the unsaturated aliphatic hydrocarbon as long as the effects of the present invention are not impaired. Examples of such other compounds include aromatic vinyl compounds such as styrene and vinyl naphthalene; halogen-containing vinyl compounds such as vinyl chloride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl pivalate; methyl vinyl ether, isobutyl And polymerizable compounds such as vinyl ethers such as vinyl ethers. These other compounds may be used individually by 1 type, or may use 2 or more types together. The structural unit derived from the other compound described above is preferably 10% by mass or less, more preferably 5% by mass or less, based on the polymer block (T).

  The polymer block (T) can be produced by polymerizing the above unsaturated aliphatic hydrocarbon and other compounds as optional components as monomers. When the structural unit contained in the polymer block (T) is derived from two or more types of monomers, the polymer block is usually subjected to polymerization as a monomer mixture obtained by mixing the two or more types of monomers. (T) is manufactured.

When the unsaturated aliphatic hydrocarbon that forms the polymer block (T) has a plurality of carbon-carbon double bonds, the carbon-carbon double bonds usually remain after polymerization. In this case, a polymer block (T) obtained by converting a part or all of the remaining carbon-carbon double bond to a saturated bond by a known hydrogenation reaction may be used. The hydrogenation rate of the carbon-carbon double bond can be calculated by ¹ H-NMR measurement. The hydrogenation rate of the carbon-carbon double bond in the hydrogenated hydrophobic polymer block is preferably 50 mol% or more, more preferably 80 mol% or more, and further preferably 95% or more.

  The number average molecular weight per polymer block (T) is preferably in the range of 3,000 to 150,000, more preferably in the range of 20,000 to 10,000, and in the range of 30,000 to 78,000. Further preferred.

  The block copolymer (Z) has at least one polymer block (S) and one polymer block (T). In the case of having a plurality of polymer blocks (S), their structures (type of monomer constituting, degree of polymerization, introduction ratio of sulfonic acid group, etc.) may be the same or different from each other. . Moreover, when it has two or more polymer blocks (T), those structures (a kind of monomer to comprise, a polymerization degree, etc.) may mutually be the same, or may differ.

  As an example of the arrangement of the polymer block (S) and the polymer block (T) in the block copolymer (Z), an S-T type diblock copolymer (S and T are the polymer block (S), A polymer block (T), the same applies hereinafter), an STS type triblock copolymer, a TST type triblock copolymer, and the like. These block copolymers may be used alone or in combination of two or more.

  The mass ratio of the total amount of the polymer block (S) and the total amount of the polymer block (T) (total mass of the polymer block (S): total mass of the polymer block (T)) is 10:90 to The ratio is preferably 50:50, and more preferably 20:80 to 40:60 from the viewpoint of production stability.

The production method of the block copolymer (Z ₀ ) can be appropriately selected from a radical polymerization method, an anionic polymerization method, a cationic polymerization method, a coordination polymerization method, and the like depending on the type and molecular weight of the constituent monomers. Industrially, a radical polymerization method, an anionic polymerization method or a cationic polymerization method is preferable. In particular, a so-called living polymerization method is preferable from the viewpoint of molecular weight and molecular weight distribution, and specifically, a living radical polymerization method, a living anion polymerization method, and a living cation polymerization method are preferable.

As a specific example of the method for producing the block copolymer (Z ₀ ), the polymer block (S ₀ ) is formed from an aromatic vinyl compound such as styrene, α-methyl styrene, t-butyl styrene, and the like. A method of producing a block copolymer (Z ₀ ) in which (T) is formed from a conjugated diene by living anion polymerization, and a polymer block (S ₀ ) such as styrene, α-methylstyrene, t-butylstyrene, etc. A method for producing a block copolymer (Z ₀ ) formed from an aromatic vinyl compound and having a hydrophobic polymer block (T) formed from isobutene by living cationic polymerization is described below.

A block copolymer in which a polymer block (S ₀ ) is formed from an aromatic vinyl compound such as styrene, α-methylstyrene, or t-butylstyrene, and a hydrophobic polymer block (T) is formed from a conjugated diene ( As a method for producing Z ₀ ) by living anionic polymerization,
(I) In the presence of an anionic polymerization initiator in a nonpolar solvent such as cyclohexane, an aromatic vinyl compound, a conjugated diene, and an aromatic vinyl compound are successively polymerized at 20 to 100 ° C. to form an S ₀ -TS ₀ type block A method of obtaining a copolymer (Z ₀ );
(II) After an aromatic vinyl compound and a conjugated diene are sequentially polymerized at 20 to 100 ° C. using an anionic polymerization initiator in a nonpolar solvent such as cyclohexane, a coupling agent such as phenyl benzoate is added. A method of obtaining a S ₀ -T-S ₀ type block copolymer (Z ₀ );
(III) In a nonpolar solvent such as cyclohexane, in the presence of an organic lithium compound as an anionic polymerization initiator, in the presence of a polar compound having a concentration of 0.1 to 10% by mass, at −30 to 30 ° C., 5 to 50% by mass. After polymerizing an aromatic vinyl compound such as α-methylstyrene and polymerizing a conjugated diene to the resulting living polymer, a coupling agent such as phenyl benzoate is added to form an S ₀ -TS ₀ type block A method of obtaining a copolymer (Z ₀ );
(IV) In the presence of an anionic polymerization initiator in a nonpolar solvent such as cyclohexane, at 20 to 100 ° C., t-butylstyrene, styrene, and conjugated diene are sequentially added one or more times in a desired order, and three or more types are added. A method of obtaining a block copolymer (Z ₀ ) comprising polymer blocks of
Etc.

Also, a block copolymer in which the polymer block (S ₀ ) is formed from an aromatic vinyl compound such as styrene, α-methylstyrene, t-butylstyrene, and the hydrophobic polymer block (T) is formed from isobutene. As a method for producing (Z ₀ ) by living cationic polymerization, isobutene is cationically polymerized in the presence of a Lewis acid in a halogenated hydrocarbon / hydrocarbon mixed solvent at −78 ° C. using a bifunctional halogenated initiator. Then, the aromatic vinyl compound is polymerized to obtain a S ₀ -T-S ₀ type block copolymer (Z ₀ ) (Macromolecular Chemie Macromolecular Symposium (Macromol. Chem., Macromol. Symp.)) 32, No. 119 (1990)).

The number average molecular weight of the block copolymer (Z ₀ ) is usually preferably from 5,000 to 200,000, more preferably from 30,000 to 150,000, still more preferably from 50,000 to 100,000.

There is no particular limitation on the method for producing the block copolymer (Z) block copolymer (Z ₀₎ and sulfonated, method for reacting the block copolymer (Z ₀₎ with known sulfonating agent is used . At this time, a solution or suspension of the block copolymer (Z ₀ ) may be prepared using an organic solvent and then reacted with a sulfonating agent.

  As the sulfonating agent, sulfuric acid; a mixed system of sulfuric acid and an aliphatic acid anhydride; a chlorosulfonic acid; a mixed system of chlorosulfonic acid and trimethylsilyl chloride; a sulfur trioxide; a mixed system of sulfur trioxide and triethyl phosphate; Examples thereof include sulfone oxides of aromatic compounds such as 2,4,6-trimethylbenzenesulfonic acid.

  Examples of the organic solvent that can be used in the sulfonation include halogenated hydrocarbons such as methylene chloride, linear aliphatic hydrocarbons such as hexane, and cyclic aliphatic hydrocarbons such as cyclohexane. These may be used alone or in combination of two or more.

(Si-containing compound)
The Si-containing compound used in the first step has a structure represented by Si—O. Such Si-containing compounds include alkoxysilanes, silanols, polysiloxanes and the like.

  When these Si-containing compounds are added to the polymer aqueous dispersion, they are usually dissolved in the polymer aqueous dispersion while undergoing hydrolysis and / or condensation polymerization. For example, when alkoxysilane is used as the Si-containing compound, the alkoxysilane is initially separated from the polymer aqueous dispersion, but if mixing is continued, the sol having the sulfonic acid group of the block copolymer (Z) as an acid catalyst. The gel reaction proceeds, and the alkoxysilane is dissolved in the polymer aqueous dispersion while undergoing hydrolysis and condensation polymerization.

  Examples of the alkoxysilane that can be used as the Si-containing compound include alkoxysilanes represented by the following general formula (1).

SiY _(4-n) (OR) _n (1)
(In the formula, R represents an alkyl group, Y represents a hydrogen atom, a halogen atom, a hydroxyl group or a hydrocarbon group, and n represents an integer of 1 or more and 4 or less.)

  The alkyl group represented by R in the general formula (1) may be linear or branched, is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group or an ethyl group.

  Examples of the hydrocarbon group represented by Y in the general formula (1) include an alkyl group having 1 to 10 carbon atoms such as a methyl group; an alkenyl group having 2 to 10 carbon atoms such as an allyl group; a phenyl group and 1 to 6 carbon atoms. An aryl group such as a phenyl group (for example, a methylphenyl group, a dimethylphenyl group, a trimethylphenyl group, an ethylphenyl group, a diethylphenyl group, or a propylphenyl group) in which at least one hydrogen atom is substituted with an alkyl group of An aralkyl group such as a benzyl group; Moreover, as a halogen atom which Y represents, a fluorine atom, a chlorine atom, a bromine atom, etc. are mentioned. Y is preferably a hydrocarbon group, particularly preferably an alkyl group having 1 to 10 carbon atoms.

  When n in the general formula (1) is 2 to 4, n (OR) s may be the same or different, but are preferably the same. n is preferably 3 or 4. When (4-n) is 2 or more, the plurality of Y may be the same or different.

  Among the alkoxysilanes represented by the general formula (1), tetramethoxysilane, tetraethoxysilane, and triethoxymethylsilane are preferable. Such alkoxysilane may be used individually by 1 type, or may use 2 or more types together.

  Examples of the silanol that can be used as the Si-containing compound include those having a structure in which the above alkoxysilane is hydrolyzed.

  Examples of the polysiloxane that can be used as the Si-containing compound include those having a structure in which the above-mentioned silanol is polycondensed. In the present specification, “polysiloxane” is a concept including a low polymerization degree oligomer of silanol and a high polymerization degree silica.

  The addition amount of the Si-containing compound is preferably in the range of 0.3 to 20 times the mass of the block copolymer (Z) from the viewpoint of enhancing the uniformity of the pore diameter and pore period of the obtained mesoporous silica. .

  From the viewpoint of promptly forming the Si-containing aqueous dispersion, the Si-containing compound is preferably stirred together with the polymer aqueous dispersion. Over time, the Si-containing compound forms a polysiloxane, but if the degree of polymerization is too high, the polysiloxane may precipitate, so the temperature at which the Si-containing compound is added and stirred is preferably in the range of -20 to 80 ° C. The range of 10-40 degreeC is more preferable.

(Optional component)
In the first step, a polar organic solvent may be used. Such polar organic solvents are preferably water-soluble, specifically ethers such as tetrahydrofuran; ketones such as acetone and cyclohexanone; methanol, ethanol, n-propanol, 2-propanol, 2-methyl-1-propanol and the like. Alcohol, and methanol, ethanol, n-propanol, and 2-propanol are more preferable. The above-mentioned polar organic solvents may be used alone or in combination of two or more. The method for adding the polar organic solvent is not particularly limited, and may be added together with the preparation of the polymer aqueous dispersion, may be added together with the Si-containing compound, or may be added after the addition of the Si-containing compound. . By using such a polar solvent, the reaction rate of the Si-containing compound in the polymer aqueous dispersion can be controlled, and the removal of water when producing mesoporous silica from the obtained Si-containing aqueous dispersion can be promoted. The amount of the polar organic solvent used is usually preferably 0.05 to 1 times by mass of the amount of water used, more preferably 0.1 to 0.5 times by mass. By making the usage-amount of a polar organic solvent 1 mass times or less of the quantity of the water to be used, the dispersion stability of the block copolymer (Z) in Si containing water dispersion liquid becomes favorable.

[Second step]
Hereinafter, the second step will be described.
In the second step, the solid content is obtained by removing water from the Si-containing aqueous dispersion. The removal of water is preferably performed until the water content is 20% by mass or less, and preferably 10% by mass or less, from the viewpoint of suppressing the fluidity of the obtained solid content. Such moisture content can be calculated from the amount of water used and the mass that decreases in the second step.

  Such a second step is usually preferably performed in an air atmosphere. The method for removing water is not particularly limited, and examples thereof include a method for evaporating water from the surface of a thin film obtained by applying a Si-containing aqueous dispersion on the surface of a substrate or the like. In this case, the thickness of the thin film is preferably in the range of 100 nm to 1 μm immediately after the Si-containing aqueous dispersion is applied. Examples of the method for applying the Si-containing aqueous dispersion include a method using a bar coater, a roll coater, a gravure coater, a dip coating method, a spin coating method, and a spray coating method. From the viewpoint of the smoothness of the resulting thin film, the temperature at which the Si-containing aqueous dispersion is applied is preferably in the range of 10 to 80 ° C, more preferably in the range of 15 to 40 ° C. The thickness of the thin film after removing water by such a method is usually preferably in the range of 80 to 900 nm.

  In removing water, a known heater such as a hot plate, a hot air dryer, an electric furnace, a vacuum dryer, or an infrared heater may be used. The set temperature when using these heaters is preferably in the range of 20 to 200 ° C. If it is lower than 20 ° C., water tends to remain in the obtained solid content, and if it exceeds 200 ° C., the uniformity of the pore period of the obtained mesoporous silica tends to be reduced, and the pore diameter tends to be reduced. Moreover, the time which uses a heater has the preferable range of 1 minute-5 hours, and the range of 5 minutes-1 hour is more preferable.

[Third step]
Hereinafter, the third step will be described.
In the third step, the block copolymer (Z) is removed from the solid content obtained in the second step. As a result, mesoporous silica having pores with a uniform pore diameter can be produced.

  Examples of the method for removing the block copolymer (Z) include methods such as firing, irradiation with energy rays (vacuum ultraviolet light, far infrared rays, microwaves, plasma, etc.), solvent washing, and the like. Vacuum ultraviolet light irradiation is preferable, and from the viewpoint of forming mesoporous silica on a resin substrate, a method of irradiating vacuum ultraviolet light is more preferable. In this specification, vacuum ultraviolet light refers to light having a central emission wavelength at a wavelength of 200 nm or less. Examples of such a lamp that emits vacuum ultraviolet light include an argon excimer lamp (center emission wavelength: 126 nm), a krypton excimer lamp (center emission wavelength: 146 nm), and a xenon excimer lamp (center emission wavelength: 172 nm).

  When removing the block copolymer (Z) by firing, it can be carried out using a known firing apparatus such as an electric furnace, a tubular furnace, or a flash lamp heating. Such calcination needs to be performed in the presence of oxygen from the viewpoint of removing the block copolymer (Z), and is preferably performed in the air. In the firing, the temperature is usually raised to the firing temperature, held for a certain time, and the temperature is lowered. The temperature rising rate is preferably in the range of 1 to 50 ° C./min. By raising the temperature of the Si-containing aqueous dispersion at an appropriate rate of temperature rise, the second step and the third step can be performed continuously. The firing temperature is preferably in the range of 300 to 1000 ° C, more preferably in the range of 400 to 700 ° C. The firing time is preferably in the range of 30 minutes to 12 hours. The cooling rate is preferably 1 to 50 ° C./min. When the temperature decreasing rate is 50 ° C./min or less, cracking of mesoporous silica can be suppressed during the temperature decreasing.

In the step of removing the block copolymer (Z), when irradiation with vacuum ultraviolet light is performed, it is preferably performed in a temperature range of 0 to 100 ° C. from the viewpoint of productivity. When the temperature is lower than 0 ° C., the removal rate of the block copolymer (Z) tends to decrease. When the temperature exceeds 100 ° C., cracks may occur on the surface of the obtained mesoporous silica.
Further, from the viewpoint of suppressing absorption of vacuum ultraviolet light by oxygen, the oxygen concentration during irradiation is preferably 10% or less, and more preferably 6% or less.
Although there is no restriction | limiting in particular in the irradiation amount of a vacuum ultraviolet light, When irradiating on the base material which consists of resin, such as a triacetyl cellulose, from a viewpoint of suppressing deterioration of a board | substrate, 10-150 mW / cm < ² > is irradiated as illumination intensity of a lamp. The time is preferably 10 to 3000 s and the irradiation amount is preferably 100 to 30000 mJ / cm ² .

  Hereinafter, the present invention will be described using examples and comparative examples, but the present invention is not limited to such examples. First, the measurement method and measurement conditions used are shown.

1. Measurement conditions for number average molecular weight of block copolymer (Z ₀ -1) by GPC GPC system: HLC-8220GPC manufactured by Tosoh Corporation
Column: TSK guard Column Super MP-M;
TSK gel G3000H;
TSKgel Super Multipore HZ-M;
Were connected in series.
RI detector: HLC-8220GPC
Column oven temperature: 40 ° C
Eluent: Tetrahydrofuran Standard sample: Conversion was performed using a calibration curve of standard polystyrene.

2. Measurement conditions of ¹ H-NMR NMR system: JNM-ECX400 manufactured by JEOL
Solvent: Deuterated chloroform Standard peak: Tetramethylsilane

3. Storage modulus measurement method A 20% by weight toluene / isopropyl alcohol (mass ratio 5/5) solution of the block copolymer (Z-1) obtained in Synthesis Example 2 was prepared, and a release-treated PET film [Mitsubishi Resin Co., Ltd., MRV (trade name)] with a thickness of about 350 μm, dried in a hot air dryer at 100 ° C. for 4 minutes, and then peeled off from the release-treated PET film at 25 ° C. A polymer film having a thickness of 30 μm was obtained. Using the wide-range dynamic viscoelasticity measuring device (“DVE-V4FT Rheospectr” manufactured by Rheology Co., Ltd.), the polymer film was heated at a rate of temperature increase of 3 ° C./min in a tensile mode (frequency: 11 Hz), − The temperature was raised from 80 ° C. to 250 ° C., and the storage elastic modulus (E ′), loss elastic modulus (E ″), and loss tangent (tan δ) were measured.

4). Method for Measuring Average Dispersion Particle Size in Polymer Water Dispersion Using a dynamic light scattering method particle size measuring device (“FPAR-1000” manufactured by Otsuka Electronics Co., Ltd.), the average of the polymer in the polymer water dispersion The dispersed particle size was measured.

5. Method for measuring the thickness of mesoporous silica The thickness of the mesoporous silica film obtained in Examples 1 to 3 was measured using a stylus-type step gauge (DEKTAK-150 manufactured by ULVAC) with an operation length of 1000 μm and a measurement time of 30 μm. Second, the indentation strength was set to 5 mg, and the measurement was performed.
The thickness of the membranous mesoporous silica obtained in Example 4 was measured from a cross-sectional SEM image.

6). Method for Measuring Average Pore Diameter of Mesoporous Silica Ten pores were extracted from the cross-sectional SEM image of the obtained mesoporous silica, and the average pore diameter was measured by measuring the length in the direction parallel to the substrate.

7). Evaluation of homogeneity of pores of mesoporous silica From the cross-sectional SEM image of the obtained mesoporous silica, the distance between adjacent pores (inter-pore distance) in 10 arbitrarily extracted pores was measured, Average distance was calculated. It was judged that the homogeneity was high when the distance between all the measured pores was between 0.5 and 1.5 times the average distance.

Synthesis Example 1 Synthesis of Block Copolymer (Z ₀ -1) Consisting of Poly α-Methylstyrene and Hydrogenated Polybutadiene A pressure-resistant vessel equipped with a stirrer was sufficiently purged with nitrogen and then sufficiently dehydrated α -172 g, 258.1 g, 28.8 g and 5.9 g of methylstyrene, cyclohexane, n-hexane and tetrahydrofuran were added, respectively. Subsequently, 17.5 ml of sec-butyllithium (1.3 M, cyclohexane solution) was added, polymerized at −10 ° C. for 5 hours, then 27 g of butadiene was added, and after stirring for 30 minutes, 1,703 g of cyclohexane was added, 303 g of butadiene was added, and the polymerization was continued for another 2 hours while raising the temperature to 60 ° C. Thereafter, 27.0 ml of α, α′-dichloro-p-xylene (0.3 M, toluene solution) was added, and the mixture was stirred at 60 ° C. for 1 hour to carry out a coupling reaction. Poly (α-methylstyrene) -polybutadiene- A poly (α-methylstyrene) type copolymer (hereinafter abbreviated as mSEBmS) was synthesized. The number average molecular weight (GPC measurement, polystyrene conversion) of the obtained mSEBmS is 74,000, the 1,2-bond amount determined from ¹ H-NMR measurement is 43.9%, and the content of α-methylstyrene unit Was 28 mass%. Further, it was found by composition analysis by ¹ H-NMR spectrum measurement that α-methylstyrene was not substantially copolymerized in the polybutadiene block.
A cyclohexane solution of synthesized mSEBmS was prepared and charged into a pressure-resistant vessel that had been sufficiently purged with nitrogen. Then, a hydrogenation reaction was performed at 80 ° C. for 5 hours in a hydrogen atmosphere using a Ni / Al Ziegler hydrogenation catalyst. S _0- consisting of α-methylstyrene block (polymer block (S ₀ ))-hydrogenated polybutadiene block (polymer block (T))-α-methylstyrene block (polymer block (S ₀ )) A T-S ₀ type triblock copolymer (hereinafter referred to as a block copolymer (Z ₀ -1)) was obtained. The resulting block copolymer hydrogenation rate of _(Z 0 -1) was calculated by ¹ H-NMR spectrum measurement, it was 99.6%.

[Synthesis Example 2] Synthesis of Block Copolymer (Z-1) 100 g of the block copolymer (Z ₀ -1) obtained in Synthesis Example 1 was vacuumed for 1 hour in a glass reaction vessel equipped with a stirrer. After drying and then purging with nitrogen, 1000 ml of methylene chloride was added and stirred at 35 ° C. for 2 hours to dissolve. After dissolution, a sulfating reagent obtained by reacting 21.0 ml of acetic anhydride and 9.34 ml of sulfuric acid at 0 ° C. in 41.8 ml of methylene chloride was gradually added dropwise over 20 minutes. After stirring at 25 ° C. for 7 hours, the polymer solution was poured into 2 L of distilled water while stirring to coagulate and precipitate the polymer. The precipitated solid was washed with distilled water at 90 ° C. for 30 minutes and then filtered. This washing and filtration operation was repeated until there was no change in the pH of the washing water, and the polymer collected by filtration at the end was vacuum dried to obtain a block copolymer (Z) (hereinafter referred to as block copolymer (Z- 1)). The sulfonation rate of the benzene ring of the α-methylstyrene unit in the obtained block copolymer (Z-1) was 50 mol% from ¹ H-NMR analysis. Moreover, based on the fact that there was no change in storage elastic modulus at 80 to 100 ° C. derived from the crystallized olefin polymer, the polymer block (T) was judged to be amorphous.

[Production Example 1]
30 g of the block copolymer (Z-1) synthesized in Synthesis Example 2 was dissolved in 270 g of a mixed solvent of tetrahydrofuran / isobutyl alcohol = mass ratio 50/50, then 300 g of methanol was added, and 1800 g of water was added several times. While adding in portions, the organic solvent was removed together with water by an evaporator to prepare 1200 g of a polymer aqueous dispersion having a content of the block copolymer (Z-1) of 2.5% by mass. The average dispersed particle diameter of the block copolymer (Z-1) in the obtained polymer aqueous dispersion was 32 nm.

[Production Example 2]
Except having changed the removal amount of an organic solvent and water, it carried out similarly to manufacture example 1, and prepared 1580 g of polymer water dispersion liquids whose content of a block copolymer (Z-1) is 1.9 mass%. The average dispersed particle diameter of the block copolymer (Z-1) in the obtained polymer aqueous dispersion was 32 nm.

[Production Example 3]
Except having changed the removal amount of an organic solvent and water, it carried out similarly to manufacture example 1, and prepared the polymer aqueous dispersion 811g whose content of a block copolymer (Z-1) is 3.7 mass%. The average dispersed particle diameter of the block copolymer (Z-1) in the obtained polymer aqueous dispersion was 32 nm.

[Example 1]
(1) Production of Si-containing aqueous dispersion After stirring 4.2 g of the polymer aqueous dispersion obtained in Production Example 1 at 25 ° C. in an air atmosphere using a magnetic stirrer, 1 g of n-propanol was added. And stirred further. Next, 0.42 g of tetraethoxysilane (manufactured by Aldrich) (equivalent to 4 times the mass of the block copolymer (Z-1)) is added, and stirring is further continued for 1 hour at 25 ° C. Obtained.
(2) Production of mesoporous silica This Si-containing aqueous dispersion was formed on a glass substrate by using a spin coater (ASC-4000W manufactured by Actes Co., Ltd.) under the atmosphere and setting the rotation speed to 1500 rpm and the rotation time to 60 seconds. Filmed. The film thickness after film formation measured using a stylus profilometer was 111 nm. The obtained film was heated to 600 ° C. at a heating rate of 30 ° C./min in an air atmosphere using an electric furnace (Yamato Scientific high temperature electric furnace FJ31), held for 1 hour, and then cooled to room temperature. As a result, a mesoporous silica film having a thickness of 90 nm was obtained. A cross-sectional SEM image of the obtained mesoporous silica is shown in FIG. It was judged that the mesoporous silica obtained from the cross-sectional SEM image had high homogeneity. The average pore diameter was 15 nm.

[Example 2]
(1) Production of Si-containing aqueous dispersion The amount of tetraethoxysilane used was changed to 4.2 g of the polymer aqueous dispersion obtained in Production Example 2 instead of the polymer aqueous dispersion obtained in Production Example 1. A Si-containing aqueous dispersion was obtained in the same manner as in Example (1) except that the amount was 0.71 g (corresponding to 9 times the mass of the block copolymer (Z-1)).
(2) Production of mesoporous silica Using this Si-containing aqueous dispersion, a mesoporous silica film having a thickness of 99 nm was obtained in the same manner as in Example 1 (2). The thickness of the film after the Si-containing aqueous dispersion was formed with a spin coater was 116 nm. Moreover, when the cross-sectional SEM image of the obtained mesoporous silica was observed, the homogeneity was high and the average pore diameter was 15 nm.

[Example 3]
(1) Manufacture of Si-containing aqueous dispersion In place of the polymer aqueous dispersion obtained in Production Example 1, 3.5 g of the polymer aqueous dispersion obtained in Production Example 3 was used, and the amount of n-propanol used was In the same manner as in Example (1) except that the amount was 0.9 g and the amount of tetraethoxysilane used was 0.31 g (equivalent to 2.3 times the mass of the block copolymer (Z-1)), Si A containing aqueous dispersion was obtained.
(2) Production of mesoporous silica Using this Si-containing aqueous dispersion, a mesoporous silica film having a thickness of 133 nm was obtained in the same manner as in Example 1 (2). The thickness of the film after the Si-containing aqueous dispersion was formed with a spin coater was 164 nm. Moreover, when the cross-sectional SEM image of the obtained mesoporous silica was observed, the homogeneity was high and the average pore diameter was 15 nm.

[Example 4]
A triacetyl cellulose film was prepared by setting the Si-containing aqueous dispersion prepared in the same manner as in Example 1 to 2000 rpm at a rotation speed of 60 seconds using a spin coater (ASC-4000W manufactured by Actes Co., Ltd.) in the atmosphere. A film was formed on (thickness 80 μm). Using an excimer UV irradiator (MEIR-M-1-200-HK, manufactured by MDI Excimer), the distance between the lamp substrates is set to 2 mm, the oxygen concentration is 1%, the substrate heating is 80 ° C., and the central emission wavelength is 172 nm. The block copolymer (Z-1) is removed by irradiating the vacuum ultraviolet light with a lamp illuminance of 40 mW / cm ² , an irradiation time of 180 s, and an irradiation amount of 7200 mJ / cm ^2, thereby forming a mesoporous film having a thickness of 150 nm. Silica was obtained. From the cross-sectional SEM image of the obtained mesoporous silica, it was judged that the homogeneity of the mesoporous silica obtained was high. The average pore diameter was 15 nm.

  The Si-containing aqueous dispersion obtained by the method of the present invention is useful for the method for producing mesoporous silica of the present invention, and this method for producing mesoporous silica is useful for forming mesoporous silica on a resin substrate. It is. An application for forming mesoporous silica on a resin substrate includes an antireflection film for a liquid crystal display element.

1. 1. Mesoporous silica Substrate 3. pore

Claims (4)

A polymer block (S) containing a structural unit derived from an aromatic vinyl compound and having a sulfonic acid group and an amorphous polymer block (T) containing a structural unit derived from an unsaturated aliphatic hydrocarbon A first step of obtaining a Si-containing aqueous dispersion by adding a Si-containing compound having a structure represented by Si-O to the aqueous dispersion of the block copolymer (Z) as a constituent component;
A mesoporous silica comprising: a second step of removing water from the obtained Si-containing aqueous dispersion to obtain a solid content; and a third step of removing the block copolymer (Z) from the solid content. Production method.   2. The mesoporous silica according to claim 1, wherein in the first step, the amount of the Si-containing compound having a structure represented by Si—O is in the range of 0.3 to 20 times by mass of the block copolymer (Z). Manufacturing method.   3. The method for producing mesoporous silica according to claim 1, wherein in the third step, the solid content is irradiated with vacuum ultraviolet light. 4.   A polymer block (S) containing a structural unit derived from an aromatic vinyl compound and having a sulfonic acid group and an amorphous polymer block (T) containing a structural unit derived from an unsaturated aliphatic hydrocarbon A method for producing an Si-containing aqueous dispersion, comprising adding an Si-containing compound having a structure represented by Si-O to an aqueous dispersion of a block copolymer (Z) as a constituent component.