JP5370241B2 - Method for producing porous silica - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silica porous material which has a low refractive index and excellent wear resistance and is stable to water, and to provide a method for producing a laminate for optical applications using the same. <P>SOLUTION: The method for producing the silica porous material from a silica-based composition includes forming the composition into a film having a film thickness of 0.05-0.5 &mu;m, then heating the film at 100-200&deg;C, and further heating the film at 300-700&deg;C, wherein the composition contains components (A)-(E) as below. In the composition, the molar ratio of water to the all silicon atoms derived from alkoxysilanes is 10-50. The component (A) is (a) and/or (b) as below. (a): at least one kind selected from the group of tetraalkoxysilanes comprising at least tetraalkoxysilanes, their hydrolyzates and their partial condensates and at least one kind selected from the group of other alkoxysilanes comprising alkoxysilanes except the tetraalkoxysilanes, their hydrolyzates, and their partial condensates. (b): a partial condensate of at least one kind selected from the group of the tetraalkoxysilanes and of at least one kind selected from the group of the other alkoxysilanes. The component (B): water, the component (C): an organic solvent, the component (D): a catalyst, and the component (E): an organic polymer. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for producing a porous silica material.

Various techniques of porous silica films as low refractive index materials have been reported.
As a method for producing a porous silica film, Patent Document 1 discloses a method for obtaining a low refractive index (silica aerogel) by supercritical drying of a silica film with liquefied carbon dioxide gas. This method can provide a very low refractive index.
In Patent Documents 2 to 6, a specific organic substance is allowed to coexist in the sol-gel reaction of alkoxysilane to form a silica / organic substance-hybrid, and then the organic substance is removed, so that it is uniform and regular. A method for obtaining a porous silica material having various pores is disclosed.

JP 2001-202827 A JP 2001-226171 A JP 2003-64307 A JP 2003-142476 A JP 2004-143029 A JP 2005-503664 A

However, the technique described in Patent Document 1 has a problem that the mechanical strength of the film is extremely weak and the water resistance is poor.
Moreover, the composition for forming a porous silica material obtained by the techniques described in Patent Documents 2 to 6 has a short pot life and it is difficult to stably obtain the porous silica material. In addition, as described in Patent Documents 2 to 6, many of the conventional methods have been developed as low dielectric constant materials, and chemical mechanical polishing for forming a copper dual damascene wiring structure in a semiconductor process ( The problem was insufficient mechanical strength against CMP. For this reason, the stability of the film | membrane with respect to the water characteristic of a silica material was missing. Therefore, the low refractive index material according to the prior art has an important problem that it is difficult to maintain a low refractive index for optical applications.

Moreover, in the composition for forming a porous silica material described in Patent Document 2 and Patent Document 6, since the amount of water relative to alkoxysilane is small, it is difficult to control the sol-gel reaction, the pot life is short, and the surface of the membrane is extremely hydrophobic. A porous silica material having the following is obtained. For this reason, it is difficult to produce a uniform film with poor water resistance, and the film surface is expected to be rough.
On the other hand, in the composition for forming a porous silica material described in Patent Document 3 and Patent Document 5, the molecular weight of the organic material to be used is low, and it is difficult to maintain a high porosity of the obtained porous silica material. It is expected that a porous silica material cannot be stably produced.

  In order to solve the above problems, the low refractive index porous silica material needs to have high strength, high wear resistance, and water resistance, and is thinner when used in optical applications. This may increase the transmittance, and a method for reducing the film thickness has been demanded. Therefore, the present invention was devised in view of the above problems, and a porous silica material having a low refractive index, excellent wear resistance, and stable against water, and an optical use laminate using the silica porous material. An object is to provide a manufacturing method.

As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by producing a porous silica under specific conditions, and the present invention has been achieved.
That is, this invention is a manufacturing method which manufactures a silica porous body from a silica type composition, Comprising: This composition contains the following (A)-(E), and originates in all the alkoxysilanes in this composition a is the ratio of water to silicon atoms (mol / mol) is 12 to 20, the composition formed into a film in a film thickness of 0.05 to 0.5 [mu] m, 100 ° C. under an air atmosphere to 200 DEG ° C. And then heating at 300 ° C. to 700 ° C. in an air atmosphere , followed by a method for producing a porous silica material.
(A): (a) and / or (b) below
(A) At least one selected from the group of tetraalkoxysilanes consisting of at least tetraalkoxysilanes, hydrolysates and partial condensates thereof, and alkoxysilanes other than tetraalkoxysilanes, hydrolysates and partial condensates thereof At least one selected from other alkoxysilanes (b) at least one selected from the tetraalkoxysilanes and at least one partial condensate selected from other alkoxysilanes (B): water (C): two or more the organic solvent (D): catalyst (E): organic polymer

  According to the present invention, a porous silica material having a low refractive index, excellent wear resistance, and stable against water can be provided.

It is a schematic sectional drawing which shows an example of the use (solar cell) of the optical use laminated body of this invention.

Hereinafter, the present invention will be described in detail with reference to embodiments, examples, etc., but the present invention is not limited to the following embodiments, examples, etc., and may be arbitrarily selected without departing from the gist of the present invention. You can change it to
[1. Composition]
The production method of the present invention is a method for producing a porous silica membrane using a silica-based precursor composition (also referred to herein as a silica-based composition or a composition of the present invention).

The compositions of the present invention comprises the following (A) ~ (E), ratio of water to silicon atoms derived from the entire alkoxysilanes (mol / mol) is 12 to 20.

(A): (a) and / or (b) below
(A) at least one selected from a tetraalkoxysilane group consisting of at least tetraalkoxysilanes, a hydrolyzate thereof and a partial condensate thereof (hereinafter referred to as “tetraalkoxysilane group” as appropriate), and alkoxysilanes other than tetraalkoxysilanes At least one selected from the group (hereinafter referred to as “other alkoxysilanes” as appropriate) and other alkoxysilane groups consisting of hydrolysates and partial condensates thereof (hereinafter referred to as “other alkoxysilanes group” as appropriate) (b) ) At least one partial condensate selected from the tetraalkoxysilane group and at least one partial condensate selected from other alkoxysilane groups (hereinafter referred to as “specific partial condensate” as appropriate).
(B): Water (C): Two or more organic solvents (D): Catalyst (E): More preferably than an organic polymer, the composition satisfies the following (1) and (2).

(1) The ratio of silicon atoms derived from tetraalkoxysilanes to silicon atoms derived from all alkoxysilanes is 0.3 (mol / mol) to 0.7 (mol / mol).
(2) 80% by weight or more in the organic solvent is a solvent having a boiling point of 55 ° C to 140 ° C.

[1-1. Alkoxysilanes]
The composition of the present invention contains at least one or both of the following first and second compounds (group) as alkoxysilanes.
[First Compound (Group)]
At least one selected from the group of tetraalkoxysilanes (ie, a group consisting of tetraalkoxysilanes, hydrolysates and partial condensates thereof), and another group of alkoxysilanes (ie, other alkoxysilanes, hydrolysates thereof, and A combination with at least one selected from the group consisting of partial condensates.

[Second compound (group)]
A specific partial condensate (that is, a partial condensate of at least one selected from the tetraalkoxysilane group and at least one selected from another alkoxysilane group).
[1-1-1. Tetraalkoxysilane group]
There is no restriction | limiting in the kind of tetraalkoxysilane. Examples of suitable ones include tetramethoxysilane, tetraethoxysilane, tetra (n-propoxy) silane, tetraisopropoxysilane, tetra (n-butoxy) silane and the like. Examples of the tetraalkoxysilane group include hydrolysates and partial condensates (such as oligomers) of the above tetraalkoxysilanes.

Among them, from the viewpoint of stability and productivity of the composition of the present invention, tetramethoxysilane and tetraethoxysilane and oligomers thereof are preferable, and tetraethoxysilane is more preferable.
However, since tetraalkoxysilanes tend to undergo hydrolysis and partial condensation over time, even when only tetraalkoxysilanes are prepared, the hydrolysates and partial condensates of tetraalkoxysilanes are usually tetraalkoxysilanes. Often co-exists with other species. In addition, the compound which belongs to the tetraalkoxysilane group may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

[1-1-2. Other alkoxysilane groups]
As the other alkoxysilanes, any alkoxysilane that does not belong to the above-described tetraalkoxysilanes can be used. Examples of suitable ones include trialkoxysilanes such as trimethoxysilane, triethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane Dialkoxysilanes such as diphenyldimethoxysilane and diphenyldiethoxysilane; bis (trimethoxysilyl) methane, bis (triethoxysilyl) methane, 1,2-bis (trimethoxysilyl) ethane, 1,2-bis ( 2 organic residues such as triethoxysilyl) ethane, 1,4-bis (trimethoxysilyl) benzene, 1,4-bis (triethoxysilyl) benzene, 1,3,5-tris (trimethoxysilyl) benzene One or more trialkoxysilyl groups Bonded; 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-acryloyl And those having an alkyl group substituted with a silicon atom, such as loxypropyltrimethoxysilane and 3-carboxypropyltrimethoxysilane, having a reactive functional group. Examples of other alkoxysilane groups include hydrolysates and partial condensates (such as oligomers) of the other alkoxysilanes.

Of these, monoalkylalkoxysilanes and dialkylalkoxysilanes having an aromatic hydrocarbon group or an aliphatic hydrocarbon group are preferred. Specific examples include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethylsilane.
However, since other alkoxysilanes tend to undergo hydrolysis and partial condensation over time, even when only other alkoxysilanes are prepared, other alkoxysilane hydrolysates and partial condensates are usually other. Often coexists with other alkoxysilanes.
In addition, the compound which belongs to other alkoxysilanes may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

[1-1-3. Partially Condensed Products of Tetraalkoxysilanes and Other Alkoxysilanes]
Any specific condensate may be used as long as it is a partial condensate obtained by partial condensation of at least one selected from the above-described tetraalkoxysilane group and at least one selected from another alkoxysilane group. When a suitable example is given, the partial condensate which the thing illustrated as a suitable example of tetraalkoxysilane and the thing illustrated as a suitable example of another alkoxysilane will be mentioned.
In addition, the specific partial condensate may use only 1 type and may use 2 or more types together by arbitrary combinations and a ratio. Furthermore, although the specific partial condensate may be used only as the specific partial condensate, it may be used in combination with one or both of the tetraalkoxysilanes and other alkoxysilanes described above.

[1-1-4. Preferred combination]
Among the combinations of tetraalkoxysilanes and other tetraalkoxysilanes described above, particularly preferred combinations include tetraethoxysilane as tetraalkoxysilanes and aromatic hydrocarbon groups or aliphatic groups as other alkoxysilanes. The combination with the monoalkyl alkoxysilane or dialkyl alkoxysilane which has a hydrocarbon group is mentioned. According to this combination, a silica porous body having a homogeneity and durability can be obtained.

[1-1-5. Ratio of alkoxysilanes]
In the composition of the present invention, the alkoxysilanes described above satisfy the following conditions. That is, the ratio of silicon atoms derived from tetraalkoxysilanes to silicon atoms derived from all alkoxysilanes is usually 0.3 (mol / mol) or more, preferably 0.35 (mol / mol) or more, more preferably 0. .4 (mol / mol) or more, and usually 0.7 (mol / mol) or less, preferably 0.65 (mol / mol) or less, more preferably 0.6 (mol / mol) or less. . When the ratio is too small, the hydrophobicity of the resulting silica porous body becomes high, but the mechanical strength of the porous silica body is extremely weak due to the decrease in —O—Si—O— bonds, In addition, the water resistance may be lowered. On the other hand, when the said ratio is too large, the residual silanol group in a silica porous body will increase, and water resistance may fall too.

  Here, the silicon atoms derived from all alkoxysilanes refer to the total number of silicon atoms contained in the tetraalkoxysilane group, other alkoxysilane groups and the specific partial condensate contained in the composition of the present invention. Moreover, the silicon atom derived from tetraalkoxysilane corresponds to the number of silicon atoms contained in the tetraalkoxysilane group contained in the composition of the present invention and the tetraalkoxysilane group among silicon atoms contained in the specific partial condensate. And the total number of silicon atoms belonging to the partial structure. Accordingly, even if the composition of the present invention is contained, the silicon atom contained in the compound is not involved in the calculation of the ratio.

In addition, the ratio of the silicon atom derived from tetraalkoxysilane to the silicon atom derived from all the alkoxysilanes can be measured by Si-NMR. The silicon atom-containing compound is preferably contained in the composition in an amount of usually 0.05% by weight or more, preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and further preferably 1% by weight or more. In addition, it is preferably contained in an amount of usually 70% by weight or less, preferably 50% by weight or less, more preferably 40% by weight or less, still more preferably 20% by weight or less. If it is less than 0.05% by weight, the film forming property such as film thickness unevenness may be lowered, and if it exceeds 70% by weight, the stability of the composition may be lowered. In addition, although a silicon atom containing compound is a compound containing a silicon atom, specifically, the above-mentioned tetraalkoxysilanes, tetraalkoxysilane groups, other alkoxysilanes, other alkoxysilane groups, specific parts A condensate is mentioned.
Further, from the viewpoint of the production process of the porous silica, the solid content concentration containing the silicon atom-containing compound and the organic polymer described below is usually 0.1% by weight or more, preferably 0.5% by weight or more. More preferably, it is 1% by weight or more. Further, it is usually preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 35% by weight or less.

[1-2. water]
The composition of the present invention contains water. The purity of the water used is preferably higher. Usually, water subjected to either or both of ion exchange and distillation may be used. However, when the porous silica material of the present invention is used in an application field that particularly dislikes minute impurities such as the optical application laminate of the present invention, since a porous silica material with higher purity is desirable, distilled water is further ionized. It is preferable to use exchanged ultrapure water. Specifically, for example, water that has passed through a filter having a pore size of 0.01 μm to 0.5 μm may be used.

The content of water in the silica-based composition is such that the ratio of water to silicon atoms derived from all alkoxysilanes is within a range of 10 to 50 (mol / mol). Usually, it is 10 (mol / mol) or more, preferably 11 (mol / mol) or more, more preferably 12 (mol / mol) or more. Moreover, it shall be 30 (mol / mol) or less and 20 (mol / mol) or less. If the ratio of water to silicon atoms derived from all alkoxysilanes is smaller than the above range, it is difficult to control the sol-gel reaction, the pot life is short, the film is formed in a non-homogeneous state, and the surface is rough. Therefore, the wear resistance may be inferior.
On the other hand, if it is larger than the previous range, the sol-gel reaction is difficult to proceed, so that the reaction takes time, and a porous silica body having a more hydrophilic surface can be obtained, so that the water resistance may be lowered.
Therefore, controlling water within the above range is an essential condition for improving wear resistance and water resistance.
The amount of water can be calculated by the Karl Fischer method (coulometric titration method).

[1-3. Organic solvent]
The composition of the present invention contains an organic solvent. There is no restriction | limiting in the kind of this organic solvent, unless the effect of this invention is impaired. Among these, as the organic solvent, it is preferable to use one or more organic silanes having the ability to mix the alkoxysilanes and water described above. Examples of suitable organic solvents include C1-C4 monohydric alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, Alcohols such as polyhydric alcohols such as dihydric alcohols having 1 to 4 carbon atoms, glycerin and pentaerythritol; diethylene glycol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, 2-ethoxyethanol, propylene glycol monomethyl ether, propylene glycol methyl ether acetate Ethers or esterified products of the above alcohols; ketones such as acetone and methyl ethyl ketone; formamide, N-methylformamide, N-ethylformamide, N, N-dimethylphenol Muamide, N, N-diethylformamide, N-methylacetamide, N-ethylacetamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methylpyrrolidone, N-formylmorpholine, N-acetylmorpholine, N- Amides such as formylpiperidine, N-acetylpiperidine, N-formylpyrrolidine, N-acetylpyrrolidine, N, N′-diformylpiperazine, N, N′-diformylpiperazine, N, N′-diacetylpiperazine; Examples include lactones such as butyrolactone; ureas such as tetramethylurea and N, N′-dimethylimidazolidine; dimethyl sulfoxide and the like. Among these, alcohols are preferable and monohydric alcohols are more preferable for the contained alkoxysilanes to perform hydrolysis under more stable conditions.

In addition, only 1 type may be used for an organic solvent and it may use 2 or more types together by arbitrary combinations and a ratio. Among them, in the silica porous body of the present invention, in order to more reliably obtain a porous structure having a low refractive index and excellent water resistance, two or more kinds of organic solvents are used in combination, and the mixture is used as the organic solvent. It is preferable to do.
In addition, from the viewpoint of the film formability of the composition, it is possible to mix a small amount of etherified product or esterified product having a high boiling point.

  However, in order to form the composition of the present invention into a film-like shape and heat-treat to form a homogeneous silica porous body, a certain amount of solvent is used during the heat treatment (pre-baking) in the first step. The removal of water and the removal of water are preferably performed simultaneously. Therefore, it is preferable to use an organic solvent in which the organic solvent in the composition of the present invention volatilizes at the same time as the moisture present near or inside the surface.

  Therefore, the composition of the present invention contains an organic solvent having a predetermined range of boiling point as the organic solvent in a predetermined high ratio. Specifically, the following conditions are satisfied. That is, an organic solvent having a boiling point of usually 55 ° C. or higher, preferably 60 ° C. or higher, more preferably 65 ° C. or higher, and usually 140 ° C. or lower, preferably 135 ° C. or lower, more preferably 130 ° C. or lower. At least one kind of “boiling point solvent” is used, and the ratio of the predetermined boiling point solvent in the total organic solvent is usually 80% by weight or more, preferably 83% by weight or more, more preferably 85% by weight or more. The upper limit of the ratio is 100% by weight. If the boiling point is too low, the composition of the present invention is cured with insufficient sol-gel reaction, and the porous silica of the present invention may be extremely inferior in water resistance.

  On the other hand, if the boiling point is too high, the sol-gel reaction proceeds locally, so that the porous silica of the present invention becomes heterogeneous, which may lead to a decrease in surface properties and a decrease in water resistance. Furthermore, when the ratio of the predetermined boiling point solvent is low, the above advantages may not be obtained. From this point of view, examples of the predetermined boiling point solvent include ethanol, 1-propanol, t-butanol, 2-propanol, 1-butanol, 1-pentanol, and ethyl acetate. Therefore, it is preferable to use at least one selected from these as the organic solvent.

  Moreover, the usage-amount of the whole organic solvent is arbitrary unless the effect of this invention is impaired remarkably. However, with respect to the silicon atoms derived from all alkoxysilanes, usually 0.01 mol / mol or more, particularly 0.1 mol / mol or more, particularly 1 mol / mol or more is preferable, and usually 100 mol / mol or less, particularly 70 mol / mol. It is preferably not more than mol, particularly not more than 20 mol / mol. If the amount of the organic solvent used is too small, the surface property of the porous silica material may be lowered, and if it is too large, the film quality is affected by the surface energy of the substrate when the porous silica material is formed as a film on the substrate. May be easier.

[1-4. catalyst]
The composition of the present invention contains a catalyst. As the catalyst, a substance that promotes the hydrolysis and dehydration condensation reaction of the above-mentioned alkoxysilanes can be arbitrarily used.
Examples include acids such as hydrochloric acid, nitric acid, sulfuric acid, formic acid, acetic acid, oxalic acid and maleic acid; amines such as ammonia, butylamine, dibutylamine and triethylamine; bases such as pyridine; acetylacetone complexes of aluminum, etc. Lewis acids; and the like.
Moreover, a metal chelate compound is also mentioned as an example of a catalyst. Examples of the metal species of the metal chelate compound include titanium, aluminum, zirconium, tin, and antimony. Specific examples of the metal chelate compound include the following.

  That is, examples of the aluminum complex include di-ethoxy mono (acetylacetonato) aluminum, di-n-propoxy mono (acetylacetonato) aluminum, di-isopropoxy mono (acetylacetonato) aluminum, di- n-butoxy mono (acetylacetonato) aluminum, di-sec-butoxy mono (acetylacetonato) aluminum, di-tert-butoxy mono (acetylacetonato) aluminum, monoethoxy bis (acetylacetonato) aluminum Mono-n-propoxy bis (acetylacetonato) aluminum, monoisopropoxy bis (acetylacetonato) aluminum, mono-n-butoxy bis (acetylacetonato) aluminum, mono-sec Butoxy bis (acetylacetonato) aluminum, mono-tert-butoxy bis (acetylacetonato) aluminum, tris (acetylacetonato) aluminum, diethoxy mono (ethylacetoacetate) aluminum, di-n-propoxy mono ( Ethyl acetoacetate) aluminum, diisopropoxy mono (ethyl acetoacetate) aluminum, di-n-butoxy mono (ethyl acetoacetate) aluminum, di-sec-butoxy mono (ethyl acetoacetate) aluminum, di-tert- Butoxy mono (ethyl acetoacetate) aluminum, monoethoxy bis (ethyl acetoacetate) aluminum, mono-n-propoxy bis (ethyl acetoacetate) aluminum Monoisopropoxy bis (ethyl acetoacetate) aluminum, mono-n-butoxy bis (ethyl acetoacetate) aluminum, mono-sec-butoxy bis (ethyl acetoacetate) aluminum, mono-tert-butoxy bis (ethyl acetoacetate) Examples include aluminum chelate compounds such as acetate) aluminum and tris (ethylacetoacetate) aluminum.

  Titanium complexes include triethoxy mono (acetylacetonato) titanium, tri-n-propoxy mono (acetylacetonato) titanium, triisopropoxy mono (acetylacetonato) titanium, tri-n-butoxy mono (acetyl). Acetonato) titanium, tri-sec-butoxy mono (acetylacetonato) titanium, tri-tert-butoxy mono (acetylacetonato) titanium, diethoxy bis (acetylacetonato) titanium, di-n-propoxy bis (Acetylacetonato) titanium, diisopropoxy bis (acetylacetonato) titanium, di-n-butoxy bis (acetylacetonato) titanium, di-sec-butoxy bis (acetylacetonato) titanium, di-tert -Butoxy bis (ace Ruacetonate) titanium, monoethoxy tris (acetylacetonato) titanium, mono-n-propoxy tris (acetylacetonato) titanium, monoisopropoxy tris (acetylacetonato) titanium, mono-n-butoxy tris (acetyl) Acetonato) titanium, mono-sec-butoxy-tris (acetylacetonato) titanium, mono-tert-butoxy-tris (acetylacetonato) titanium, tetrakis (acetylacetonato) titanium, triethoxy mono (ethylacetoacetate) titanium , Tri-n-propoxy mono (ethyl acetoacetate) titanium, triisopropoxy mono (ethyl acetoacetate) titanium, tri-n-butoxy mono (ethyl acetoacetate) titanium, tri-sec-butyl Xy mono (ethyl acetoacetate) titanium, tri-tert-butoxy mono (ethyl acetoacetate) titanium, diethoxy bis (ethyl acetoacetate) titanium, di-n-propoxy bis (ethyl acetoacetate) titanium, diiso Propoxy bis (ethyl acetoacetate) titanium, di-n-butoxy bis (ethyl acetoacetate) titanium, di-sec-butoxy bis (ethyl acetoacetate) titanium, di-tert-butoxy bis (ethyl acetoacetate) Titanium, monoethoxy tris (ethyl acetoacetate) titanium, mono-n-propoxy tris (ethyl acetoacetate) titanium, monoisopropoxy tris (ethyl acetoacetate) titanium, mono-n-butoxy tris (ethyl acetoacetate) Acetate) titanium, mono-sec-butoxy tris (ethyl acetoacetate) titanium, mono-tert-butoxy tris (ethyl acetoacetate) titanium, tetrakis (ethyl acetoacetate) titanium, mono (acetylacetonate) tris (ethyl aceto) Acetate) titanium, bis (acetylacetonato) bis (ethylacetoacetate) titanium, tris (acetylacetonato) mono (ethylacetoacetate) titanium and the like.

Among those described above, acids or metal chelate compounds are preferable and acids are more preferable in order to more easily control the hydrolysis and dehydration condensation reaction of alkoxysilanes.
In addition, a catalyst may use only 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

The amount of the catalyst used is arbitrary as long as the effects of the present invention are not significantly impaired. However, it is usually 0.001 mol times or more, especially 0.003 mol times or more, particularly preferably 0.005 mol times or more, and usually 0.8 mol times or less, especially 0.5 mol times or less, especially with respect to alkoxysilanes. Is preferably 0.1 mol times or less. If the amount of the catalyst used is too small, the hydrolysis reaction will not proceed moderately, and active groups such as silanol groups are likely to remain in the porous silica material after production, which may reduce the water resistance of the porous silica material. If the amount is too large, it becomes difficult to control the reaction, and the catalyst concentration is further increased during production, so that the surface property of the porous silica material may be lowered.
From the viewpoint of film forming property, the pH of the composition is usually less than 7, but preferably 5.5 or less, more preferably 4.5 or less, further preferably 3 or less, particularly preferably 2 or less. is there. By making it in this range, the surface modification of the substrate can be simultaneously performed at the time of film formation, and the film forming property tends to be further improved.

[1-5. Organic polymer]
The composition of the present invention contains an organic polymer. Examples of the organic polymer include polyethylene glycol (hereinafter appropriately referred to as “PEG”), polypropylene glycol, polyisobutylene glycol polyethylene glycol, polyethylene glycol alkyl ether, polyvinyl acetate, polyvinyl alcohol, polyvinyl acetal, polyvinyl pyrrolidone, poly (2-ethyl-2- Oxazoline), carboxymethylcellulose, hydroxyethylcellulose, polyacrylic acid, polymethacrylic acid, acrylic acid maleic acid copolymer, polyacrylic acid salt and the like.

A particularly preferable organic polymer is an organic polymer having an ethylene oxide moiety. Of these, nonionic polymers are particularly preferred. By having an ethylene oxide moiety, the organic polymer according to the present invention is stable against a hydrolyzate or condensate of alkoxysilanes formed during the sol-gel reaction of alkoxysilanes.
At this time, the content of the ethylene oxide moiety in the organic polymer according to the present invention is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 20% by weight or more, preferably 23% by weight or more, more preferably 25%. It is usually not more than 100% by weight, preferably not more than 90% by weight, more preferably not more than 85% by weight. When the content of the ethylene oxide moiety falls within the above range, the organic polymer is more stable than the hydrolyzate or condensate of alkoxysilanes formed during the sol-gel reaction of alkoxysilanes. be able to.

  Moreover, as long as it has an ethylene oxide part, the main chain skeleton structure is not particularly limited. Specific examples of the main chain skeleton structure include polyether, polyester, polyurethane, polyolefin, polycarbonate, polydiene, polyvinyl ether, polystyrene, and derivatives thereof. Among these, a polymer containing a polyether as a constituent component is preferable. Specific examples thereof include polyethylene glycol, polypropylene glycol, polyisobutylene glycol and the like. Among these, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock polymer and / or polyethylene glycol are particularly preferable.

In addition, the organic polymer concerning this invention may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The weight average molecular weight is preferably 4,300 or more, more preferably 5,000 or more, and particularly preferably 6,000 or less. If the weight average molecular weight of the polymer is too small, it is difficult to maintain the porosity of the resulting silica porous body high, and it may not be possible to stably produce a low refractive index silica porous body. is there. The upper limit of the weight average molecular weight is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 100,000 or less, preferably 70,000 or less, more preferably 40,000 or less. If the weight average molecular weight is too large, a homogeneous silica porous body cannot be produced, and the water resistance of the silica porous body may be lowered.

  Moreover, the usage-amount of the organic polymer which concerns on this invention is arbitrary unless the effect of this invention is impaired remarkably. However, the ratio of the organic polymer according to the present invention to silicon atoms derived from all alkoxysilanes is usually 0.001 (mol / mol) or more, preferably 0.002 (mol / mol) or more, more preferably 0.003. (Mol / mol) or more, usually 0.05 (mol / mol) or less, preferably 0.04 (mol / mol) or less, more preferably 0.03 (mol / mol) or less. If the ratio is too small, the porous silica of the present invention cannot form a sufficient porous structure, and there is a possibility that a low refractive index effective for optical applications cannot be realized. On the other hand, when the said ratio is too large, when the silica porous body of this invention is shape | molded, the organic polymer which concerns on this invention will precipitate excessively on the surface, and there exists a possibility of roughening the surface.

  Furthermore, it is preferable that the organic polymer which concerns on this invention does not contain a cation from a viewpoint of reducing the impurity at the time of applying as an optical use. Moreover, even if it contains a cation, the amount of the cation is preferably small. Specifically, the amount of the cation in the organic polymer according to the present invention is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 1% by weight or less. When the cation component remains, there is a possibility that the function of the base material is lowered and the porous silica of the present invention may be colored.

[1-6. Others]
As long as it is possible to produce the porous silica of the present invention, the composition of the present invention contains components other than the above-mentioned alkoxysilanes, water, organic solvent, catalyst and the organic polymer according to the present invention. May be. Moreover, the said component may use only 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[1-7. advantage]
The composition of the present invention can produce the porous silica of the present invention having a low refractive index and excellent wear resistance and water resistance. A specific method for producing the porous silica of the present invention from the composition of the present invention will be described later.
In addition, since the composition of the present invention has a long pot life and is stable, it can produce a silica porous body film that is more stable and uniform than conventional techniques.
Furthermore, in the composition of this invention, the refractive index of the porous silica excellent in water resistance can be kept in a desired range.

[2. Method for producing silica porous body]
The method for producing the porous silica of the present invention is not limited, but usually, the above-described composition of the present invention is formed into a desired shape such as a film and cured by heating to form the porous silica of the present invention. Manufacturing. Hereinafter, this production method (hereinafter referred to as “the production method of the present invention” as appropriate) will be described in detail.
In the production method of the present invention, the composition of the present invention is prepared, formed into a film, and then heated to produce the porous silica of the present invention. Moreover, in the manufacturing method of this invention, you may perform other operation as needed. For example, aging may be performed during or after the preparation of the composition of the present invention, and the silica porous body of the present invention after curing may be cooled and post-treated.

[2-1. Formulation process]
In the blending step, the components of the composition of the present invention are mixed to prepare the composition of the present invention. At this time, there is no limitation on the order of mixing the components. In addition, each component may be mixed all at once, or may be mixed continuously or intermittently in two or more times.

  However, in order to control the sol-gel reaction, which has heretofore been difficult to control, and to more industrially prepare the composition of the present invention, it is preferable to mix in the following manner. That is, alkoxysilanes, water, a catalyst and a solvent are mixed, and the mixture is aged to hydrolyze and dehydrate and condense alkoxysilanes to some extent. And the organic polymer which concerns on this invention is mixed with the mixture, and the composition of this invention is prepared. Thereby, the affinity of alkoxysilanes and organic polymer can be maintained under sol-gel reaction conditions. The aging may be performed after mixing the mixture and the organic polymer according to the present invention.

  During the ripening, heating is preferably performed in order to advance hydrolysis / dehydration condensation reaction of alkoxysilanes. The heating condition is not particularly limited as long as it does not exceed the boiling point of the solvent to be used, but it is usually 40 ° C. or higher, preferably 50 ° C. or higher, and particularly preferably 60 ° C. or higher. If the heating temperature is too low, the reaction time becomes extremely long, and the productivity may decrease. On the other hand, the upper limit of the heating temperature is preferably 100 ° C. or less, and more preferably 95 ° C. or less. If it exceeds 100 ° C., the water in the composition of the present invention will boil, and the decomposition / dehydration condensation reaction may not be controlled.

  The aging time is not limited, but is usually 10 minutes or more, preferably 20 minutes or more, more preferably 30 minutes or more, and usually 10 hours or less, preferably 8 hours or less, more preferably 5 hours or less. If the aging time is too short, it may be difficult to proceed with the aging reaction uniformly.If the aging time is too long, the volatilization of the solvent cannot be ignored, the composition ratio changes, and the stability of the composition is lowered. There is a possibility that the water resistance of the porous silica material is lowered.

Furthermore, although there is no restriction | limiting in the pressure conditions at the time of ageing | curing | ripening, Usually, it matures by a normal pressure. When the pressure changes, the boiling point of the solvent also changes, and the aging solvent volatilizes (evaporates), so that the composition ratio changes, resulting in a low stability of the composition, and a porous silica material having high water resistance. May not be obtained.
Further, it is preferable that the composition of the present invention is further mixed with an organic solvent and diluted after the aging and before the film forming step. Thereby, the sol-gel reaction rate in the composition of this invention can be reduced, and it becomes possible to maintain the pot life of the composition of this invention long.

[2-2. Membrane formation process]
After the blending process, a film forming process for forming the prepared composition of the present invention into a film is performed. In the film forming step, the composition of the present invention is usually formed on the surface of a predetermined substrate to form a film of the composition of the present invention.
There is no limitation on the method of film formation. For example, a casting method in which the composition of the present invention is spread on a substrate using a bar coater, applicator, doctor blade, etc .; the substrate is immersed in the composition of the present invention. Examples of the dip coating method include a spin coating method, a capillary coating method, a die coating method, and a spray coating method. Among these methods, a casting method, a die coating method, a spray coating method, and a spin coating method are preferably employed because the composition of the present invention can be uniformly applied. Among these, spin coating, dip coating, and spray coating are particularly preferable for forming a homogeneous film.

  The film thickness is usually controlled in the range of 0.05 μm to 0.5 μm, preferably 0.10 μm to 0.3 μm, more preferably 0.10 μm to 0.2 μm. Here, the film thickness is controlled within this range, and it is possible to form a film having good adhesion to the substrate and excellent wear resistance. Moreover, when it is outside this range, it tends to be worn because it is inferior in adhesion to the substrate, and it tends to be inferior in durability because of its low strength as a film.

As one of the methods for controlling the film thickness, it can be controlled by changing the amount of the organic solvent added for dilution after aging of the composition of the present invention.
When the composition of the present invention is formed into a film by the casting method, the casting speed is not limited, but is usually 0.1 m / min or more, preferably 0.5 m / min or more, more preferably 1 m / min or more, Usually, it is 1000 m / min or less, preferably 700 m / min or less, more preferably 500 m / min or less. If the casting speed is too slow, the film thickness may be uneven, and if it is too fast, it may be difficult to control the wettability with the substrate.

  In the dip coating method, the substrate may be dipped in the coating solution and pulled up at an arbitrary speed. The pulling speed at this time is not limited, but is usually 0.01 mm / second or more, preferably 0.05 mm / second or more, more preferably 0.1 mm / second or more, and usually 50 mm / second or less, preferably 30 mm / second. Second or less, more preferably 20 mm / second or less. If the pulling speed is too slow or too fast, the film thickness may be uneven. On the other hand, although there is no restriction | limiting in the speed | rate which immerses a base material in a coating liquid, Usually, it is preferable to immerse a base material in a coating liquid at a speed | rate comparable as a raising speed. Further, the immersion may be continued for an appropriate time from when the substrate is immersed in the coating solution until it is pulled up. There is no limitation on the duration of this immersion, but it is usually 1 second or more, preferably 3 seconds or more, more preferably 5 seconds or more, and usually 48 hours or less, preferably 24 hours or less, more preferably 12 hours or less. is there. If this time is too short, the adhesion to the substrate may be low, and if it is too long, a film may be formed during the immersion and the smoothness may be low.

  Further, when the composition of the present invention is formed by spin coating, the rotational speed is usually 10 revolutions / minute or more, preferably 50 revolutions / minute or more, more preferably 100 revolutions / minute or more, and usually 100,000 revolutions. / Min or less, preferably 50000 revolutions / minute or less, more preferably 10,000 revolutions / minute or less. If the rotational speed is too slow, the film thickness may be uneven. If the rotational speed is too fast, the vaporization of the solvent tends to proceed and the reaction such as hydrolysis of alkoxysilanes does not proceed sufficiently and the water resistance may be low.

Further, within the preferable range of the number of rotations, the film thickness can be reduced by increasing the number of rotations, the film thickness can be increased by decreasing the number of rotations, and the film thickness can be adjusted.
Further, when the composition of the present invention is applied and formed by the spray coating method, the method of the spray nozzle is not particularly limited, but may be selected in consideration of the advantages of each spray nozzle. Typical examples include a two-fluid spray nozzle (two-fluid atomization method), an ultrasonic spray nozzle (ultrasonic atomization method), a rotary spray nozzle (rotary atomization method), and the like. An ultrasonic spray nozzle and a rotary spray nozzle are preferable in that the atomization of the composition and the conveyance of the atomized particles to the substrate by the gas flow can be controlled independently. From the viewpoint of maintaining the liquidity of the composition, two fluids are preferable. A spray nozzle is preferred.

Furthermore, the air velocity of the gas flow used for transporting the atomized particles is preferably adjusted as appropriate depending on the composition used, but is usually 5 m / sec or less, preferably 4 m / sec or less, more preferably 3 m / sec or less. is there. If the air velocity is too high, the membrane can become inhomogeneous. The gas used is not particularly limited, but an inert gas such as nitrogen is preferable.
The distance between the spray nozzle and the substrate is preferably adjusted as appropriate according to the substrate size, but is usually 5 cm or more, preferably 10 cm or more, more preferably 15 cm or more. Moreover, it is 100 cm or less normally, Preferably it is 80 cm or less, More preferably, it is 50 cm or less. If this range is exceeded, film thickness unevenness may occur.

However, in the film-forming step of the production method of the present invention, the relative humidity is usually 20% or more, preferably 25% or more, more preferably 30% or more, and usually 85% or less, preferably 80% or less, more preferably Film formation is performed in an environment of 75% or less. By setting the relative humidity in the film forming step within the above range, a film having high surface smoothness can be obtained.
There is no restriction | limiting in the atmosphere in a film-forming process. For example, the film may be formed in an air atmosphere, or the film may be formed in an inert atmosphere such as argon.

  Although there is no restriction | limiting in the temperature at the time of performing a film-forming process, Usually 0 degreeC or more, Preferably it is 10 degreeC or more, More preferably, it is 20 degreeC or more, Usually, 100 degreeC or less, Preferably it is 80 degreeC or less, More preferably, it is 70 degreeC. Hereinafter, it is more preferably 60 ° C. or less, particularly preferably 50 ° C. or less, particularly preferably 40 ° C. or less. If the temperature at the time of film formation is too low, the solvent is difficult to evaporate and the surface smoothness of the film may be reduced. If it is too high, the curing of alkoxysilanes may proceed rapidly and the film distortion may increase. .

  Although there is no restriction | limiting in the pressure at the time of performing a film-forming process, Usually, 0.05 Mpa or more, Preferably it is 0.08 Mpa or more, More preferably, it is 0.1 Mpa or more, Usually, 0.3 Mpa or less, Preferably it is 0.2 Mpa or less, More preferably, it is 0.15 MPa or less. If the pressure is too low, the solvent tends to evaporate and the leveling effect after film formation cannot be obtained, and the smoothness of the film may be reduced. If it is too high, the solvent is less likely to evaporate and the surface property of the film may be reduced. There is sex.

By the way, in the dip coating method, the spin coating method, and the spray coating method, there is a difference in drying speed, and a slight difference may occur in the stable structure of the film immediately after film formation. This can be adjusted by changing the atmosphere during film formation. In addition, the slight difference in the stable structure of the film can be dealt with by surface treatment of the substrate.
Prior to the film formation of the composition of the present invention on the substrate, the substrate is subjected to a surface treatment from the viewpoint of the wettability of the composition of the present invention and the adhesion of the formed silica porous body. You may keep it. Examples of such surface treatment include silane coupling treatment, corona treatment, UV ozone treatment and the like. Moreover, only 1 type may be performed for a surface treatment and you may perform it combining 2 or more types arbitrarily.
The film forming step may be performed once, but may be performed in two or more steps. For example, if the film forming step is performed twice or more via a heating step described later, it is possible to form a porous silica body having a laminated structure. This is useful, for example, when it is desired to stack layers having different refractive indexes.

[2-3. Heating process]
After the film forming step, a heating step of heating the film of the composition of the present invention is performed. It is also a feature of the present invention that the heating process is divided into two stages and detailed temperature control is performed for each process. By dividing the heating process into two, a more homogeneous film can be formed and the wear resistance is improved. Furthermore, the line can be stopped during production, which can contribute to the improvement of productivity. By the heating process, the organic solvent and / or water in the composition of the present invention is dried and removed, and the film is cured, whereby the porous silica of the present invention is formed. In the present invention, detailed temperature control is performed for each process in two stages. In the first heating process (pre-baking), the organic solvent and / or water in the composition is dried in the temperature range shown below. Although there is no particular limitation as long as it is removed, the removal ratio is usually 50% or more, preferably 70% or more, more preferably with respect to each amount of the organic solvent and water before the first heating step (pre-baking). Is 90% or more, particularly preferably 100%. That is, after the organic solvent and / or water is dried and removed in the first heating step (pre-baking), the second heating step (main baking, curing) is performed.

  The method of the heat treatment is not particularly limited, but as an example, an in-furnace bake method in which a substrate is placed in a heating furnace (baking furnace) to heat the film of the composition of the present invention, on a plate (hot plate) A hot plate system in which a substrate is mounted and the film of the composition of the present invention is heated through the plate. A heater is disposed on the upper surface side and / or lower surface side of the substrate, and electromagnetic waves (for example, infrared rays) are irradiated from the heater. And a method of heating the film of the composition of the present invention. In addition, as for an industrial system, it is preferable to prepare the said apparatus, such as an independent furnace, plate, heater corresponding to a 1st heating process and a 2nd heating process.

  In the first heating step (pre-baking), the temperature is usually preferably 100 ° C. or higher and 200 ° C. or lower. More preferably, it is 140 degreeC or more, More preferably, it is 150 degreeC or more, Preferably it is 180 degreeC or less, More preferably, it is 170 degreeC or less. If the heating temperature is too low, the solvent cannot be removed, the film has fluidity, and an unstable and homogeneous film cannot be formed. In addition, since the surface is sticky, it cannot be placed in the middle of production, and there is a possibility that dust or the like may adhere, which is inferior in production. On the other hand, if the temperature is too high, the curing of the film starts, so the advantage of pre-baking is impaired.

  In a 2nd heating process (this baking, hardening), 300 degreeC or more and 700 degrees C or less are preferable normally. Preferably it is 320 degreeC or more, More preferably, it is 350 degreeC or more, Preferably it is 500 degrees C or less, More preferably, it is 450 degrees C or less. If the heating temperature is too low, the refractive index of the resulting film (that is, the silica porous body of the present invention) may not be lowered or may be colored. On the other hand, if the heating temperature is too high, the adhesion between the substrate and the porous silica of the present invention may be lowered. In the heating step, the heating may be performed continuously at the heating temperature, but the heating may be performed intermittently.

  In both the first heating step (pre-baking) and the second heating step (main baking, curing), the heating rate is arbitrary as long as the effect of the present invention is not significantly impaired. The temperature is preferably raised at 10 ° C./min or more, usually 500 ° C./min or less, preferably 300 ° C./min or less. If the rate of temperature increase is too slow, the film may become dense, resulting in increased film strain and low water resistance, and if the rate of temperature increase is too high, the film strain may be increased and water resistance may be decreased. .

  The heating time in the first heating step (pre-baking) is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 30 seconds or longer, preferably 1 minute or longer, more preferably 2 minutes or longer, and usually 5 Time or less, preferably 2 hours or less, more preferably 1 hour or less. If the heating time is too short, the solvent cannot be removed sufficiently, the film has fluidity, and the surface may be deformed until the second heating step, or dust may adhere and a uniform film may not be formed. .

  The time for heating in the second heating step (main baking, curing) is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 30 seconds or longer, preferably 1 minute or longer, more preferably 2 minutes or longer, Usually, 5 hours or less, preferably 2 hours or less, more preferably 1 hour or less. If the heating time is too short, there is a possibility that the organic polymer cannot be removed sufficiently. If the heating time is too long, the reaction of the alkoxysilane proceeds and the adhesion to the substrate may be lowered.

Although the pressure at the time of performing the heating in the first heating step and the second heating step is arbitrary as long as the effects of the present invention are not significantly impaired, a reduced pressure environment is preferable. This is because the vaporization of the solvent proceeds more than the reaction of alkoxysilane, which may result in a film having low water resistance. From this viewpoint, in the heating step, the pressure is usually 0.2 MPa or less, preferably 0.15 MPa or less, more preferably 0.1 MPa or less. On the other hand, the lower limit of the pressure is not limited, but is usually 10 ⁻⁴ MPa or more, preferably 10 ⁻³ MPa or more, more preferably 10 ⁻² MPa or more. If the pressure is too low, the vaporization of the solvent proceeds more than the reaction of alkoxysilane, which may result in a film with low water resistance.

The atmosphere during heating is arbitrary as long as the effects of the present invention are not significantly impaired. Among them, an environment in which drying unevenness is unlikely to occur is preferable. Among these, it is preferable to perform heating in an air atmosphere. It is also possible to perform an inert gas treatment and dry in an inert atmosphere.
As described above, by performing the heat treatment, the film of the composition of the present invention can be cured to obtain the porous silica of the present invention. Moreover, since the said film | membrane is normally formed in the base-material surface, according to the manufacturing method of this invention, it is also possible to manufacture the optical laminated body of this invention.

[2-4. Cooling process]
You may perform a cooling process after a heating process as needed. In the cooling step, the porous silica of the present invention that has become high temperature in the heating step is cooled. At this time, the cooling rate is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1 ° C./min or more, preferably 0.5 ° C./min or more, more preferably 0.8 ° C./min or more, More preferably, it is 1 ° C./min or more, usually 100 ° C./min or less, preferably 50 ° C./min or less, more preferably 30 ° C./min or less, still more preferably 20 ° C./min or less. If the cooling rate is too slow, the production cost may increase. If it is too fast, the film quality is expected to deteriorate due to the difference in linear expansion between adjacent films.
The atmosphere in the cooling step is arbitrary as long as the effects of the present invention are not significantly impaired, and may be, for example, a vacuum environment or an inert gas environment. Furthermore, although there is no restriction | limiting in temperature and humidity, normally it cools at normal temperature and normal humidity.

[2-5. Post-processing process]
After the heating step, a post-processing step may be performed as necessary. Although there is no restriction | limiting in the specific operation performed by a post-processing process, For example, the surface of the silica porous body of this invention was excellent in functionality by processing the obtained silica porous body with a silylating agent. Can be a thing. Specifically, by treating with a silylating agent, hydrophobicity is imparted to the porous silica of the present invention, and the pores can be prevented from being contaminated by impurities such as alkaline water.

  Examples of the silylating agent include trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethylethoxysilane, methyldiethoxysilane, dimethylvinylmethoxysilane, and dimethyl. Alkoxysilanes such as vinylethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane; trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, methyldichlorosilane, dimethylchlorosolane, dimethylvinylchlorosilane , Methyl vinyl dichlorosilane, methyl chloro disilane, triphenyl chloro silane, methyl diphenyl chloro Chlorosilanes such as silane and diphenyldichlorosilane; Silazanes such as hexamethyldisilazane, N, N′-bis (trimethylsilyl) urea, N-trimethylsilylacetamide, dimethyltrimethylsilylamine, diethyltriethylsilylamine, trimethylsilylimidazole; 3,3-trifluoropropyl) trimethoxysilane, (3,3,3-trifluoropropyl) triethoxysilane, pentafluorophenyltrimethoxysilane, pentafluorophenyltriethoxysilane, etc. Alkoxysilanes having a group; and the like.

  In addition, a silylating agent may use only 1 type and may use 2 or more types together by arbitrary combinations and a ratio. Specific operations of silylation include, for example, applying a silylating agent to the porous silica, immersing the porous silica in the silylating agent, or placing the porous silica in the vapor of the silylating agent. It can be done by exposing.

Further, as another example of the post-treatment, the silica porous body of the present invention is aged under humid conditions, whereby unreacted silanol present in the porous structure can be reduced. It is also possible to further improve the water resistance of the silica porous body.
[2-6. Others]
In the production method of the present invention, unless the effects of the present invention are significantly impaired, an arbitrary process may be performed at any stage before, during, or after each process described above.

[2-7. advantage]
According to the production method of the present invention, the porous silica of the present invention having a low refractive index and excellent wear resistance and water resistance can be produced. Moreover, according to the manufacturing method of this invention, the composition and optical use laminated body of this invention can also be manufactured. That is, according to the production method of the present invention, it is possible to provide a porous silica material, an optical use laminate and a composition that can stably maintain the optical performance of a low refractive index, and an optical use laminate using the same. . In particular, since the porous silica that can be produced is excellent in wear resistance and water resistance, it can be suitably used for applications premised on outdoor use.

[3. Silica porous body]
[3-1. Porous structure]
The porous silica of the present invention is a porous body having a porous structure mainly composed of silica having a large number of pores. The hole is usually a connecting hole in which a tunnel or an independent hole is connected, but there is no particular limitation on the detailed structure of the hole. However, as the structure of the holes, continuous holes are preferable, and such continuous holes can be confirmed by an electron microscope.

  The term “mainly composed of silica” means that, in the silicon oxide composition, the ratio of silicon to all positive elements including silicon is usually 50 mol% or more, preferably 70 mol% or more, more preferably 80 mol% or more, particularly preferably. Means 90 mol% or more. If the silicon content is less than the lower limit, the surface roughness of the porous silica material may become extremely large, and the mechanical strength may also decrease. Moreover, a silica porous body with better surface smoothness is formed, so that the content rate of silicon is high. The upper limit is ideally 100 mol%.

Since the porous silica of the present invention has a low refractive index and the refractive index can be controlled within a desired range, it can be applied as, for example, a low reflection material and an antireflection material. That is, the silica porous body of the present invention can provide an optimum refractive index as a low reflection layer for any substrate such as resin and glass.
When using a porous silica as a low reflection layer, the porous silica is preferably provided on a substrate having a certain size or more. That is, 0.1 m ² or more is preferable, 0.25 m ² or more is more preferable, and 1 m ² or more is more preferable. If it is smaller than this size, the low reflection effect may not be sufficiently exhibited.

Moreover, since the porous silica of the present invention is excellent in smoothness, it is expected to be applied as, for example, a light extraction material in an electroluminescence element.
Furthermore, since the porous silica of the present invention is resistant to wear and stable to water, it can be used for applications presumed to be used outdoors. Can be applied. In this case, the silica porous body of the present invention is suitable for use as a low reflective layer for solar cells. This low reflection layer for solar cells is usually formed on the outermost surface of the solar cell and functions as a light capturing film. That is, the low reflective layer for solar cells functions to efficiently take in the light incident on the solar cells and increase the luminous efficiency of the solar cells.

[3-2 Refractive index]
The porous silica of the present invention has a refractive index of 1.3 or less. Among these, 1.28 or less is preferable, 1.27 or less is more preferable, and 1.25 or less is particularly preferable. More preferably, it is 1.23 or less. If the refractive index is too large, the strain in the porous silica of the present invention becomes large and may be weak against external force. On the other hand, the lower limit of the refractive index is not particularly limited, but is usually 1.05 or more, preferably 1.08 or more. If the refractive index is too small, the mechanical strength of the porous silica of the present invention may be significantly reduced.

The refractive index means a value at a wavelength of 400 nm to 700 nm measured by an optical technique such as a spectroscopic ellipsometer method, reflectance measurement, reflection spectroscopic spectrum measurement or prism coupler, and preferably measured by a spectroscopic ellipsometer. Say. When measuring with a spectroscopic ellipsometer, the refractive index can be estimated by fitting the measured value with a Cauchy model.
Further, in the case of a porous silica material provided on a base material having a large center line average roughness, the refractive index can be estimated also by reflectance spectrum measurement, and the measurement region is preferably 10 μm or less. .

[3-3. water resistant]
In the porous silica material of the present invention, the difference in refractive index at a wavelength of 550 nm before being immersed in water and after being immersed in water for 24 hours is 0.15 or less (condition (2)). Among these, 0.1 or less is more preferable, 0.05 or less is more preferable, and 0.03 or less is particularly preferable. Thereby, the silica porous body of the present invention is excellent in water resistance and can obtain a stable refractive index performance even in optical applications. Further, when the refractive index difference is larger than the upper limit value, water is constrained inside the porous structure of the silica porous body, and at the same time, the condensation reaction of silanol groups proceeds inside the silica porous body by the above treatment. Probability is high. In this case, there is a possibility that the porous silica was already in an unstable state before the treatment.

  Further, the lower limit value of the refractive index difference is preferably 0.001 or more, more preferably 0.002 or more, and further preferably 0.004 or more. When the refractive index difference is smaller than the lower limit, the porous silica of the present invention has a hydrophobic property in terms of affinity with water. At this time, there is a possibility that water is restrained inside the porous silica due to the capillary phenomenon in the porous structure. In this case, the constrained water becomes extremely difficult to escape, and the refractive index performance of the porous silica material may not be maintained. This is important for applications that are intended for outdoor use.

  In addition, the said refractive index difference can be measured in the following ways. That is, after the refractive index n1 at a wavelength of 550 nm of the porous silica material of the present invention is measured in advance, the porous silica material is subjected to normal temperature and normal humidity (temperature 18 ° C. to 28 ° C., humidity 20% to 80% RH). Soak in water under conditions, remove after 24 hours and dry. Hereinafter, this treatment is appropriately referred to as “water immersion treatment”. In addition, drying is not performed by heating at 100 ° C. or higher, but by air drying. Thereafter, the refractive index n2 of the porous silica is measured again at a wavelength of 550 nm. The absolute value Δn = | n2−n1 | of the refractive index difference at this time is the refractive index difference.

  In addition to the water immersion treatment, the water resistance can be evaluated by “high temperature and high humidity treatment” described below. That is, after the refractive index n1 at a wavelength of 550 nm of the porous silica material of the present invention is measured in advance, the porous silica material is allowed to stand at a temperature of 85 ° C. and a humidity of 85% RH, and taken out after 500 hours. Then, the refractive index n3 at a wavelength of 550 nm of this porous silica material is measured again. The absolute value Δn ′ = | n3−n1 | of the refractive index difference at this time is the refractive index difference. The refractive index difference is preferably 0.001 or more, more preferably 0.003 or more, further preferably 0.005 or more, and particularly preferably 0.008 or more. Moreover, 0.15 or less is preferable, 0.12 or less is more preferable, 0.1 or less is still more preferable, 0.08 or less is especially preferable.

[3-4. Measurement of film thickness]
The film thickness may be measured using a P-15 type contact surface roughness meter manufactured by KLA-Tencor, Inc., and the measurement conditions may be stylus force (contact pressure) 0.2 mg and scan speed 10 μm / second. It can also be evaluated by a spectroscopic ellipsometer, a reflection spectroscopic method, and a prism coupler.

[4. Optical use laminate]
The optical use laminated body of this invention is comprised including a base material and the silica porous body of this invention provided on the said base material. Moreover, the optical use laminated body of this invention may be equipped with members other than a base material and a silica porous body as needed. [4-1. Base material]
Any substrate can be used depending on the application. Among these, it is preferable to use a transparent substrate made of a general-purpose material.

  Examples of base materials include silicate glass, high silicate glass, alkali silicate glass, lead alkali glass, soda lime glass, potash lime glass, barium glass and other silicate glasses, borosilicate glass, alumina silicate glass, phosphoric acid Glass such as salt glass and tempered glass thereof; acrylic resin such as polymethyl methacrylate and cross-linked acrylate; aromatic polycarbonate resin such as bisphenol A polycarbonate; polyester resin such as polyethylene terephthalate; amorphous polyolefin resin such as polycycloolefin , Epoxy resins, styrene resins such as polystyrene, polysulfone resins such as polyethersulfone, synthetic resins such as polyetherimide resin, fluorine-containing resins such as ETFE, PFA, PCTFE, ECTFE, PVDF, PVF, etc. And the like. These can be used alone or in any combination of two or more.

Among these, from the viewpoint of dimensional stability, glass, aromatic polycarbonate resin, polyetherimide resin, polyester resin, polysulfone resin, fluorine-containing resin, and amorphous polyolefin resin are preferable. From the viewpoint of price, soda lime glass and aromatic polycarbonate are preferable. A resin and an amorphous polyolefin resin are preferred. Furthermore, it is also preferable to use tempered glass or aromatic polycarbonate resin from the viewpoint of impact resistance.
For example, when a solar cell cover glass is used as the light-transmitting substrate, the silica-based porous film functions as an antireflection film on the surface of the light-transmitting substrate and realizes an improvement in output. Since the porous silica film obtained by the production method of the present invention is excellent in durability, it is suitable for such applications. In addition, when using a solar cell cover glass used for a solar cell capable of photoelectric conversion even in the near-infrared light such as a single crystal solar cell and a polycrystalline solar cell, it is contained in a normal soda-lime glass. The divalent iron ions absorb in the near-infrared region, and therefore it is preferable to increase the light transmittance by reducing the iron ion content. More preferably, it is used as a material.
Moreover, when using fluorine-containing resin as a resin cover film, it is preferable to form into a film after performing the surface treatment of resin.

The dimensions of the substrate are arbitrary. However, when a plate-like substrate is used as the base material, the thickness of the substrate is preferably 0.1 mm or more and more preferably 0.2 mm or more from the viewpoint of mechanical strength and gas barrier properties. The thickness is preferably 80 mm or less, more preferably 50 mm or less, and particularly preferably 30 mm or less, from the viewpoints of weight reduction and light transmittance.
The center line average roughness of the substrate is also arbitrary. However, from the viewpoint of the film formability of the laminated silica porous body, the center line average roughness is preferably 10 nm or less, more preferably 8 nm or less, still more preferably 5 nm or less, and particularly preferably 3 nm or less.

  On the other hand, when imparting antiglare properties and concealing properties, the center line average roughness of the substrate is not limited to the above, and the surface of the substrate preferably has irregularities. Such irregularities may be provided on one side or both sides of the substrate, but are preferably provided on the surface on which the porous silica material is laminated. Specifically, the center line average roughness is usually 0.1 μm or more, preferably 0.2 μm or more, more preferably 0.4 μm or more, and usually 15 μm or less, preferably 10 μm or less. The maximum height Rmax of the surface roughness is usually 0.1 μm or more, preferably 0.3 μm or more, more preferably 0.5 μm or more, particularly preferably 0.8 μm or more, usually 100 μm or less, preferably 80 μm or less. More preferably, it is 50 μm or less, more preferably 30 μm or less, and particularly preferably 10 μm or less. Optical use that is excellent in low reflection characteristics and anti-glare property by providing the porous silica of the present invention on the base material in the range of the centerline average roughness and the maximum height Rmax of the surface roughness. A laminate can be provided. Below or above this range, the low reflection effect may be impaired and the appearance may become opaque. Moreover, the average interval Sm of the irregularities on the surface of the substrate is usually 0.01 mm or more, preferably 0.03 mm or more, and can be usually 30 mm or less, preferably 15 mm or less. The centerline average roughness, the maximum height Rmax of the surface roughness, and the average interval Sm of the irregularities are general-purpose surface roughness meters according to JIS-B0601: 1994 (for example, Surfcom 570A manufactured by Tokyo Seimitsu Co., Ltd.) Measured by

[4-2. Silica porous body of laminated body for optical use]
In the optical use laminate, the above-mentioned porous silica material of the present invention is used.
Moreover, although the silica porous body of this invention is provided on a base material directly or through another layer, the silica porous body of this invention will be normally provided in film form. The film thickness is usually preferably 0.05 μm or more and 0.5 μm or less, preferably 0.05 μm or more, more preferably 0.1 μm or more. The upper limit is 0.25 μm or less, preferably 0.2 μm or less. If the film thickness is too thin, the influence of the interface between the porous silica material of the present invention and another member (for example, the interface between the adhered base material and the porous silica material) may cause distortion and surface properties in the porous silica material. The film quality and water resistance of the optical application laminate of the present invention may be reduced. If the film thickness is too large, the strain in the porous silica material is extremely increased, the film formability may be lowered, and the wear resistance may not be sufficiently exhibited. By making the silica porous body of the present invention have the above-mentioned preferable film thickness, the optical application laminate of the present invention is provided with optical performance and stability of performance effective as a member constituting an optical application member. Can do.
Moreover, the surface roughness of the silica porous body in the optical application laminate may be affected by the surface roughness of the substrate. When the substrate surface is uneven, the surface roughness of the porous silica material in the optical application laminate is approximately the same as the surface roughness of the substrate described above.

[4-3. Other parts]
The optical application laminate of the present invention may be provided with other members as necessary. For example, it is good also as what has an electrode in the surface on the opposite side to the surface in which the silica porous body of the base material was formed.
By using an optical laminate having electrodes on the surface opposite to the surface on which the porous silica material of the substrate is formed, it is suitable as a member of an optical device such as a display or a solar cell. Moreover, an electrode can be provided in a board | substrate directly or through another layer. Examples of the electrode include aluminum, tin, magnesium, gold, silver, copper, nickel, palladium, platinum, or an alloy containing these, indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide, and zinc oxide. Among them, indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide, zinc oxide, or a main composition thereof is preferable from the viewpoint of transparency. These are one kind alone, or two or more kinds are arbitrarily selected. Can be used in any combination and ratio. The film thickness is usually 10 nm or more, preferably 40 nm or more, more preferably 80 nm or more, and further preferably 100 nm or more. Moreover, it is 500 nm or less normally, Preferably it is 400 nm or less, More preferably, it is 300 nm or less, More preferably, it is 200 nm or less. If the thickness is less than 10 nm, defects tend to be formed in the film, and if it exceeds 500 nm, the transparency may be impaired.

Here, an example in which the optical application laminate of the present invention is configured as a solar cell is shown in FIG. For example, when the optical use laminate of the present invention is configured as a solar cell, the silica porous body 6 and the base material 5 are usually used for coating on the light receiving surface side that takes in the light energy of the solar cell.
Further, the solar cell is usually configured such that a pair of electrodes 1 and 3 are provided, and the semiconductor layer 2 is positioned between the electrodes 1 and 3.

There may also be an intermediate layer 4 between the substrate 5 and the electrode 3. Furthermore, a heat ray blocking layer, an ultraviolet degradation preventing layer, a hydrophilic layer, an antifouling layer, an antifogging layer, a moisture proof layer, an adhesive layer, a hard layer, a conductive layer, a reflective layer, an antiglare layer, a diffusion layer, etc. (not shown) May be combined with
Here, the solar cell is an element or device that can convert light energy into electric power by utilizing the photovoltaic effect, and examples thereof include a single crystal silicon solar cell, a polycrystalline silicon solar cell, and amorphous silicon. Silicon solar cells such as solar cells, CIS solar cells, CIGS solar cells, compound solar cells such as GaAs solar cells, dye-sensitized solar cells, organic thin film solar cells, multi-junction solar cells, HIT solar cells However, it is not particularly limited to these.

The semiconductor layer is a layer containing a semiconductor material. In a solar cell, electric energy is usually generated in a semiconductor layer by taking in light, and functions as a battery by taking out the electric energy.
At this time, there is no limitation on the type of semiconductor used for the semiconductor layer. Moreover, only 1 type may be used for a semiconductor and it may use 2 or more types together by arbitrary combinations and a ratio. Further, the semiconductor layer may contain other materials as long as the function as a solar cell is not significantly impaired.

Moreover, the semiconductor layer may be composed of only a single film or may be composed of two or more films. As a specific type, the semiconductor layer in the solar cell may be any of a bulk heterojunction type, a stacked type (hetero pn junction type), a Schottky type, a hybrid type, and the like.
The thickness of the semiconductor layer is not particularly limited, but is usually 5 nm or more, preferably 10 nm or more, and usually 10 μm or less, preferably 5 μm or less.

On the other hand, the electrode can be formed of any material having conductivity. The electrode is for taking out electric energy generated in the semiconductor layer. However, it is preferable that at least one of the pair of electrodes is transparent in accordance with the type of the semiconductor layer (that is, the light absorbed by the semiconductor layer for generating power by the solar cell is transmitted).
Examples of transparent electrode materials include oxides such as ITO and indium zinc oxide (IZO); and metal thin films. In addition, the material of an electrode may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Furthermore, two or more electrodes may be laminated, and characteristics (electric characteristics, wetting characteristics, etc.) due to surface treatment may be improved.
However, when the optical application laminate of the present invention is configured as a solar cell, the total light transmittance of C light from the porous silica to the semiconductor layer is preferably 80% or more, and 83% or more. More preferably, it is more preferably 86% or more, and particularly preferably 90% or more. This is because the higher the light transmittance, the more efficiently the solar cell can generate power. The total light transmittance is ideally 100%, but is usually 99% or less in consideration of partial reflection on the surface of the optical use laminate. Since the porous silica of the present invention has a low refractive index and is excellent in abrasion resistance and water resistance, it is possible to exhibit performance very suitable for a solar cell in this way.

  When the optical application laminate of the present invention is configured as a solar cell, the total C light transmittance of the porous silica material and the base material is preferably 80% or more, and more preferably 83% or more. Is more preferably 86% or more, and particularly preferably 90% or more. This is because the higher the light transmittance, the more efficiently the solar cell can generate power. The total light transmittance is ideally 100%, but is usually 99% or less in consideration of partial reflection on the surface of the optical use laminate. Since the porous silica of the present invention has a low refractive index and is excellent in water resistance, it is possible to exhibit performance very suitable for a solar cell in this way.

In addition, even if it is a case where the optical use laminated body of this invention is used for optical uses other than a solar cell, it is preferable that the light transmittance of a silica porous body is high normally. Thereby, the optical use laminate of the present invention can be provided with optical performance and stability of performance effective as a member constituting the optical use member.
Moreover, the optical use laminated body of this invention is suitable also for an electroluminescent (EL) element in the point which is excellent in abrasion resistance and water resistance, and has a smooth surface.

  The electroluminescent element of the present invention may be any one as long as it has the porous film of the present invention, two electrodes, and an electroluminescent layer between the electrodes, and is usually (i) an electrode (cathode), (ii) electro It is possible to adopt a configuration in which the luminescence layer, (iii) the electrode (anode), (iv) the porous film of the present invention, and (v) the light transmitting body are arranged in this order. As long as the order of (i)-(v) is maintained, you may have another layer between each layer. For example, a light scattering layer and / or a high refractive index layer may be inserted between (iii) the electrode (anode) and (iv) the porous film of the present invention.

  (I) The material used as the cathode is preferably a metal having a low work function. In particular, it is made of aluminum, tin, magnesium, indium, calcium, gold, silver, copper, nickel, chromium, palladium, platinum, magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy, or the like. In particular, it is preferable to form with aluminum. The thickness of the cathode is usually 10 nm or more, preferably 30 nm or more, more preferably 50 nm or more. Moreover, it is 1000 nm or less normally, Preferably it is 500 nm or less, More preferably, it is 300 nm or less.

(Ii) The electroluminescent layer is formed by a material that exhibits a light emission phenomenon when an electric field is applied. The material includes activated zinc oxide ZnS: X (where X is Mn, Tb , Cu, an activation element of Sm, _{etc.), CaS:. Eu, SrS} : Ce, SrGa 2 S 4: Ce, CaGa 2 S 4: Ce, CaS: Pb, BaAl 2 S 4: conventionally used, such as Eu Inorganic EL materials, 8-hydroxyquinoline aluminum complexes, aromatic amines, low molecular weight organic EL materials such as anthracene single crystals, poly (p-phenylene vinylene), poly [2-methoxy-5- Conjugated polymer organic EL materials such as (2-ethylhexyloxy) -1,4-phenylenevinylene], poly (3-alkylthiophene), and polyvinylcarbazole Etc., can be used organic EL materials are conventionally used. The thickness of the electroluminescence layer is usually 10 nm or more, preferably 30 nm or more, more preferably 50 nm or more, and usually 1000 nm or less, preferably 500 nm or less, more preferably 200 nm or less. The electroluminescent layer can be formed by a vacuum film forming process such as vapor deposition or sputtering, or a coating process using xylene, toluene, cyclohexylbenzene or the like as a solvent.

(Iii) As an anode, indium oxide mixed with tin (usually called ITO), zinc oxide mixed with aluminum (usually called AZO), zinc oxide mixed with indium (commonly called IZO) A complex oxide thin film is preferably used. In particular, ITO is preferable.
The anode can be a transparent electrode layer that is transparent to visible light. When the anode is formed as a transparent electrode layer, the higher the light transmittance in the visible light wavelength region, the better. In this case, the lower limit is usually 50% or more, preferably 60% or more, more preferably 70% or more. The upper limit is usually 99% or less. In addition, the electrical resistance of the anode is preferably as small as the surface resistance value, and is usually 1Ω / □ (ohm per square; □ = 1 cm ² ) or more, usually 100Ω / □ or less, preferably 70Ω / □ or less, more preferably 50Ω. / □ or less.

Further, the thickness when the anode is a transparent electrode is not particularly limited as long as it satisfies the light transmittance and the surface resistance described above, but is usually 0.01 μm or more, and from the viewpoint of conductivity. Preferably it is 0.03 micrometer or more, More preferably, it is 0.05 micrometer or more. The upper limit is usually 10 μm or less, preferably 1 μm or less, more preferably 0.5 μm or less from the viewpoint of light transmittance.
Moreover, you may equip the optical use laminated body of this invention with another optical function layer and a protective film, for example. Other optical functional layers can be appropriately selected depending on the application to be used. Further, these layers may be provided with only one layer, or may be provided with an arbitrary combination of two or more layers.

[4-4. advantage]
Since the optical use laminated body of this invention is equipped with the silica porous body of this invention, its refractive index is low and it is excellent in water resistance. For this reason, the silica porous body of the present invention can be suitably used as, for example, a low reflection layer, an antireflection layer, a light extraction layer in an electroluminescence element, and the like. In particular, since it can be used for applications presumed to be used outdoors by utilizing its excellent wear resistance and water resistance, it is particularly suitable for use as a low reflection layer of a solar cell.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
[Example 1]
[Composition of composition]
1.70 g of tetraethoxysilane, 1.73 g of methyltriethoxysilane, 0.58 g of ethanol (boiling point 78.3 ° C.), 1.39 g of water, and 3.25 g of 0.3% by weight hydrochloric acid aqueous solution were mixed. The mixture (A) was prepared by stirring in a water bath at 30 ° C. for 30 minutes and further at room temperature for 30 minutes.

  Next, 1.54 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock polymer (PLURONIC P123 manufactured by BASF (weight average molecular weight 5,650, the proportion of ethylene oxide moiety is 30% by weight); hereinafter referred to as “P123” as appropriate) The mixture (A) was added to a mixture (B) mixed with 0.8 g of ethanol, and stirred at room temperature for 60 minutes to prepare a mixture (C).

  30 g of 1-butanol (boiling point 117.3 ° C.) as a diluting solvent was mixed with this mixture (C) and stirred at room temperature for 30 minutes to obtain a composition. In this composition, the ratio of water to silicon atoms derived from all alkoxysilanes (tetraethoxysilane and methyltriethoxysilane) is 14.40 (mol / mol).

[Production of porous silica]
The obtained composition was filtered through a 0.45 μm filter, and a 75 mm square glass substrate (centerline average roughness = 0.01 μm, maximum height of surface roughness Rmax = 0.13 μm), 2 ml was dropped. And the thin film was produced by rotating 1000 rotation 2 minutes with a Mikasa spin coater. The relative humidity at this time was 45%.

Next, the thin film was placed on a hot plate set at 150 ° C. and heated in an air atmosphere for 2 minutes. Then, it put on the hotplate set to 450 degreeC, and obtained the porous silica body with a favorable external appearance by heating for 2 minutes by an atmospheric condition. (Refractive index / film thickness measurement)
Measure with a spectroscopic ellipsometer and analyze with Cauchy model. As a result, the obtained porous silica had a refractive index of 1.17 at a wavelength of 550 nm and a film thickness of 0.146 μm.
〔productivity〕
After the first heating step, the production line is stopped and whether or not storage is possible is used as an index of productivity. Whether storage is possible or not is determined by whether or not dust is easily attached.
After the first heating step, Bencott M-3 (Ozu Sangyo Co., Ltd.) was placed on the coated surface instead of garbage, and stored at room temperature for one day. Then, Bencott M-3 was removed, and the state of the coated surface was confirmed.
If there is a trace of Bencott, ×. If it does not remain, it was marked as “Good”.
[Abrasion resistance 1]
Using a reciprocating abrasion tester (manufactured by Suga Test Instruments), Bencot M-3 (Ozu Sangyo Co., Ltd.) was pressed against the sample surface as abrasive paper, and the surface condition of the film after a 50 reciprocation test with a load of 200 g was observed with a microscope. confirmed.
When the whole film peeled after the test, it was marked as x, and when the film remained, it was marked as ◯.
[Abrasion resistance 2]
Cheese cloth was pressed against the sample surface as abrasive paper, and the surface state of the film after a load of 500 g and 3 reciprocation tests was confirmed.
When the whole film peeled after the test, it was marked as x, and when the film remained, it was marked as ◯.

[Example 2]
Except that 50.0 g of 1-butanol as a diluting solvent was added, the same operation as in Example 1 was performed to produce a porous silica, and each evaluation was performed. The results are shown in Table 1.

[Comparative Example 1]
Except that 11.0 g of 1-butanol as a diluting solvent was added, the same operation as in Example 1 was performed to produce a porous silica, and each evaluation was performed. The results are shown in Table 1.

[Comparative Example 2]
A porous silica material was produced in the same manner as in Example 1 except that the heating temperature in the first heating step was 40 ° C. The surface was sticky and the adhesion to the glass substrate was insufficient.
[Comparative Example 3]
In the mixture (A), water was not added, the hydrochloric acid aqueous solution was changed to 1.63 g of a 0.6% by weight hydrochloric acid aqueous solution, and 1-butanol as a dilution solvent at the time of preparing the mixture (C) was changed to 21.8 g. The same operations as in Example 1 were performed to produce a porous silica, and each evaluation was performed. The results are shown in Table 1.
[Comparative Example 4]
In the mixture (A), 20 g of water and 80.87 g of 1-butanol as a dilution solvent at the time of preparation of the mixture (C) were added in the same manner as in Example 1 to produce a porous silica, Evaluation was performed. The results are shown in Table 1.
The results of the above examples and comparative examples are shown below.

  The present invention can be used in any industrial field, and can be used, for example, in any optical application. Among them, according to the present invention, it is possible to improve wear resistance and water resistance as compared with the prior art, and therefore it is suitable for use in outdoor applications such as solar cells.

1, 3 electrodes
2 Semiconductor layer
4 middle class
5 Transparent substrate
6 Porous material

Claims (3)

A method for producing a porous silica material from a silica-based composition, wherein the composition comprises the following (A) to (E), and water for silicon atoms derived from all alkoxysilanes in the composition: After the ratio (mol / mol) is 12 or more and 20 or less, the composition is formed into a film having a film thickness of 0.05 to 0.5 μm, and heated at 100 ° C. to 200 ° C. in an air atmosphere. A method for producing a porous silica material comprising heating at 300 ° C. to 700 ° C. in an air atmosphere .

(A): (a) and / or (b) below
(A) At least one selected from the group of tetraalkoxysilanes consisting of at least tetraalkoxysilanes, hydrolysates and partial condensates thereof, and alkoxysilanes other than tetraalkoxysilanes, hydrolysates and partial condensates thereof At least one selected from other alkoxysilanes (b) at least one selected from the tetraalkoxysilanes and at least one partial condensate selected from other alkoxysilanes (B): water (C): two or more the organic solvent (D): catalyst (E): organic polymer   The method for producing a porous silica material according to claim 1, wherein the refractive index of the porous silica material is 1.3 or less. The method for producing a porous silica material according to claim 1 or 2, wherein the porous silica material is a low reflective layer for solar cells.

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