WO2016010080A1

WO2016010080A1 - Antifouling article, method for producing same, antifouling layer-forming composition and cover glass for solar cells

Info

Publication number: WO2016010080A1
Application number: PCT/JP2015/070296
Authority: WO
Inventors: 雄一 ▲桑▼原; 修二種田; 阿部　啓介
Original assignee: 旭硝子株式会社
Priority date: 2014-07-18
Filing date: 2015-07-15
Publication date: 2016-01-21
Also published as: JP2017154899A

Abstract

Provided are: an antifouling article having an antifouling layer that has more excellent antifouling properties; and a method for producing this antifouling article. The present invention is an antifouling article which comprises a base and an antifouling layer that is arranged on the base and has a plurality of projections on the surface, said projections containing an aggregate of particles and a binder. With respect to projections (T) each having a height of 90% or more based on a projection having the maximum height from the base surface among the projections, the average peak-to-peak distance between adjacent projections (T) is 100-1,000 nm. The ratio of the total area covered by the particles with respect to the area of the base on which the antifouling layer is arranged is 12-100%.

Description

Antifouling article, method for producing the same, antifouling layer forming composition, and cover glass for solar cell

The present invention relates to an antifouling article, a production method thereof, an antifouling layer forming composition, and a cover glass for a solar cell.

Various techniques have so far been proposed for forming a hydrophilic antifouling layer on the surface of a plate-like substrate such as tile or plate glass.

For example, Patent Document 1 discloses a hydrophilic surface in which silica fine particles are bonded with a siliceous binder, the surface of which is a fine rough surface with protruding silica fine particles, and a large number of bent fine pores communicating from the surface to the inside. A structure having a fine porous antifouling layer on the outer surface of a substrate has been proposed.

JP 2004-174498 A

∙ Antifouling articles provided with a super-water-repellent coating may not have a sufficient antifouling effect when used in an environment with little rainwater such as deserts. Moreover, according to the knowledge of the present inventors, the fine porous antifouling layer described in Patent Document 1 does not have sufficient antifouling properties.

The present invention solves the conventional problems as described above, and provides an antifouling article excellent in antifouling property, a method for producing the same, and an antifouling layer forming composition.
In addition, the present invention provides a cover glass that is excellent in antifouling property even in an environment with little rainwater.

The present invention comprises the following.
The present invention has a substrate and an antifouling layer disposed on the substrate and having a plurality of protrusions including particle aggregates and a binder on the surface, and the maximum height from the substrate surface in the protrusions. With respect to the protrusion T having a height of 90% or more on the basis of the protrusion having a thickness, the average distance between the apexes of the adjacent protrusions T is 100 to 1,000 nm, and the antifouling layer is disposed. Further, the present invention relates to an antifouling article in which the ratio of the total covered area of the particles to the area of the substrate is 12 to 100%.
The present invention is an antifouling article comprising a substrate and an antifouling layer disposed on the substrate, wherein the antifouling layer comprises an aggregate of particles and a binder, and the surface of the antifouling layer Has a plurality of protrusions, and the antifouling layer is sprinkled with JIS test powder and allowed to stand for 10 seconds, tilted 135 ° with respect to the horizontal surface, and twice from a height of 3 cm to a speed of 10 cm / second. The present invention relates to an antifouling article having a value obtained by dropping the powder in contact with the ground and measuring the haze value 10 times and subtracting the haze value before the test from the average value within 1.0.
The present invention is a cover glass for a solar cell having an antifouling layer on a surface thereof, the antifouling layer comprising an aggregate of particles and a binder, and the surface of the antifouling layer having a plurality of protrusions. The antifouling layer is sprinkled with JIS test powder and allowed to stand for 10 seconds, tilted 135 ° with respect to the horizontal plane, and brought into contact with the ground twice at a speed of 3 cm from a height of 3 cm. A solar cell cover glass in which the value obtained by dropping the powder and measuring the haze value 10 times and subtracting the haze value before the test from the average value is within 1.0.
The present invention includes a pearl necklace-like silica having an average primary particle diameter of 5 to 300 nm and a silica precursor, and the volume ratio of the pearl necklace-like silica and the silica precursor in terms of silica is 7/93. The present invention relates to an antifouling layer-forming composition that is ˜95 / 5.
The present invention includes a particle that can form a protrusion and a binder precursor on a substrate, and the volume ratio of the particle that can form the protrusion and the binder precursor in terms of metal oxide is 7/93. A step of forming an antifouling layer forming composition layer by applying an antifouling layer forming composition of ~ 95/5, and heat-treating the antifouling layer forming composition layer to form an antifouling layer And a process for producing an antifouling article.
The present invention includes a pearl necklace-like silica having an average primary particle diameter of 5 to 300 nm and a silica precursor on a substrate, and the volume ratio of the pearl necklace-like silica and the silica precursor in terms of silica is The antifouling layer forming composition of 7/93 to 95/5 is applied to form an antifouling layer forming composition layer, and the antifouling layer forming composition layer is heated to obtain an antifouling layer. The present invention relates to a method for producing an antifouling article comprising a step of forming a layer.

According to the present invention, an antifouling article superior in antifouling property, a production method thereof, and an antifouling layer forming composition can be provided.

It is a figure which shows an example of the antifouling article based on this invention. 2 is a scanning electron micrograph of the surface of an antifouling article obtained in Example 1. FIG. 2 is a scanning electron micrograph of the cross section of the antifouling article obtained in Example 1. FIG.

In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . A numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Furthermore, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.
“Pearl necklace-like silica” is a pearl necklace in which a plurality of spherical silica particles are connected and secondary-agglomerated to form a long and slender silica particle, that is, a plurality of decorative pearls connected in a rosary shape. In addition, it refers to a shape in which a plurality of particles of silica are connected, and the connection method may be linear or branched. In this specification, in particular, in a two-dimensional image obtained by an electron microscope, a circular figure caused by a spherical portion has a roundness of 70% or more, and the total area of the inscribed circles of each circular figure is a secondary particle. A particle that occupies 70% or more of the total projected area and in which the inscribed circles of the circular figures do not overlap each other is called a chain particle. Here, the roundness is represented by the ratio of the radius of the inscribed circle to the radius of the circumscribed circle of the target figure outline, and is 100% for a perfect circle. Further, in this specification, “pearl necklace-like particles” are obtained by replacing silica in the above-mentioned “pearl necklace-like silica” with other various particles.
In this specification, the primary particle diameter of the particle is a particle diameter determined by observation with a scanning electron microscope. The secondary particle diameter is a particle diameter measured by a dynamic light scattering method.

[Anti-fouling article]
An antifouling article according to the present invention has a base and an antifouling layer disposed on the base and having a plurality of protrusions containing particle aggregates and a binder on the surface. With respect to a protrusion T having a height of 90% or more on the basis of the protrusion having the maximum height from the body surface (hereinafter also simply referred to as “projection T”), the distance between the apexes of adjacent protrusions T Is 100 to 1,000 nm, and the ratio of the total covered area by the particles to the area of the substrate on which the antifouling layer is disposed is 12 to 100%.
FIG. 1 is a diagram showing an example of an antifouling article according to the present invention. In FIG. 1, an antifouling article 1 has a base 2 and an antifouling layer 6 disposed on the base 2 and having a plurality of protrusions 5 including aggregates of particles 3 and a binder 4 on the surface.
In the present specification, the “projection including an aggregate of particles and a binder” is also simply referred to as “projection”.

(Substrate)
The substrate is not particularly limited, and examples thereof include glass, plastic, metal, ceramics, and combinations thereof (for example, composite materials, laminated materials, etc.), and a light transmissive substrate made of glass or plastic is preferable. When the substrate is glass, it may be subjected to a tempering treatment (for example, a physical tempering treatment or a chemical tempering treatment). May be. The shape of the substrate is not particularly limited, and examples thereof include a flat plate shape, a shape having a curvature on the entire surface or a part thereof, and the like. The thickness of the substrate is not particularly limited and can be appropriately selected depending on the use of the antifouling article. The thickness of the substrate is preferably 1 to 10 mm.
The substrate may be a cover glass. Examples of the cover glass include a cover glass for protecting a mirror or a lens used in a solar cell cover glass or concentrating solar thermal power generation or concentrating solar power generation.

(Anti-fouling layer)
The antifouling layer is the following first antifouling layer or second antifouling layer. In the following description, when the first antifouling layer and the second antifouling layer are not particularly distinguished and described as “antifouling layer”, the first antifouling layer and the second antifouling layer are used. It includes both dirty layers.
The first antifouling layer is disposed on the substrate and has a plurality of protrusions including a particle aggregate and a binder on the surface, and the protrusion has the maximum height from the substrate surface as a reference. As for the protrusion T having a height of 90% or more, the average value of the distance between the apexes of the adjacent protrusions T is 100 to 1,000 nm, and the area relative to the area of the substrate on which the antifouling layer is disposed. The ratio of the total covered area by the particles is 12 to 100%.

The first antifouling layer has a plurality of protrusions including aggregates of the particles and a binder protruding from the surface of the antifouling layer, and other regions (for example, convexes including non-aggregated particles and a binder). It is preferable that irregularities are formed on the surface thereof. In that case, since the protrusion is an aggregate of particle aggregates and a binder that are present unevenly on the surface of the substrate, more appropriate unevenness is formed compared to the unevenness formed by the particles alone, There exists a tendency for antifouling property to improve more. Since the dirt adhering to the antifouling article comes into contact with the projections present on the surface of the antifouling layer, the dirt comes into contact with the protrusions in the present invention. Therefore, in the antifouling layer, the contact area in contact with the dirt can be further reduced, and an antifouling layer having better antifouling properties can be obtained. On the other hand, when the distance between vertices described later is 100 nm or more, even when the dirt is oil dirt, adsorption due to capillary action can be suppressed. As a result, it is difficult for oil stains to adhere, and even if it adheres, it can be easily removed by washing with water.

The shape of the protrusion is not particularly limited, and examples thereof include a substantially quadrangular pyramid, a substantially triangular pyramid, and a substantially cone. When the region from the apex of the protrusion to the height of 50% is approximated to a partial spherical surface, the radius of curvature of the partial spherical surface is not particularly limited, but is preferably 5 nm or more, more preferably 5 nm to 15 nm. The height of the protrusion is not particularly limited, but is preferably 10 nm or more, and more preferably 30 to 200 nm. The height of the protrusion is the height from the base surface to the apex of the protrusion, and can be measured using a scanning electron microscope.

The size of the bottom surface of the protrusion is not particularly limited, but is preferably 10 to 700 nm, and more preferably 30 to 200 nm. The average value of the angle between the bottom surface of the protrusion (ie, the surface parallel to the substrate) and the side surface is not particularly limited, but is preferably 10 to 90 °, more preferably 20 to 70 °. If the angle between the bottom surface and the side surface of the protrusion is 10 ° or more, a steeper protrusion is obtained. Here, the size of the bottom surface of the protrusion is defined as the diameter of a circle in which the bottom shape of the protrusion is inscribed. The bottom size of the protrusion can be measured using a scanning electron microscope.

In the antifouling layer, with respect to the protrusion T having a height of 90% or more with reference to the protrusion having the maximum height from the substrate surface, the average value of the distances between the apexes of adjacent protrusions T (Hereinafter also simply referred to as “distance between vertices”) is 100 to 1,000 nm, preferably 100 to 800 nm, and more preferably 100 to 500 nm. The distance between the vertices of 100 to 1,000 nm means that the unevenness formed by the protrusions T is large on the surface of the antifouling layer. Further, since the protrusion T includes two or more particles (that is, an aggregate of particles) and a binder, the protrusion T has a large protrusion compared to the surface roughness of the antifouling layer formed by the protrusions including the single particle and the binder. This means that a partial structure is formed. The distance between vertices can be measured with a scanning electron microscope. Specifically, the distance between the vertices is a protrusion having a maximum height among protrusions existing in a predetermined region in a direction parallel to the surface of the substrate having the antifouling layer, from a cross-sectional photograph of the antifouling article. Select a body, select a protrusion T having a height of 90% or more, measure the distance between vertices of adjacent protrusions T (that is, the distance between the vertices), and calculate the average value. Can be obtained. Preferably, the distance between vertices can be measured by a measurement method of “distance between vertices” described later in the embodiment.

The ratio of the total covered area of the aggregate of particles to the area of the substrate on which the antifouling layer is disposed (hereinafter also referred to as “convex coverage”) is preferably 12 to 100%. When the convex portion coverage is 12% or more, a sufficient antifouling property can be obtained because the presence ratio of the aggregates of particles and the protrusions containing the binder that can come into contact with dirt in the antifouling layer is large. The convex portion coverage is preferably 15 to 100%, more preferably 20 to 100%, and particularly preferably 50 to 100%. The convex portion coverage can be measured with a scanning electron microscope. Specifically, it can be measured by a measuring method of “convex portion coverage” which will be described later in Examples.

The number of protrusions in the antifouling layer is not particularly limited, but is preferably 30 to 100 / μm ^{2, and} more preferably 50 to 100 / μm ² . The number of protrusions can be measured, for example, by observing the film surface obliquely with a scanning electron microscope.
The second antifouling layer is sprinkled with JIS test powder and allowed to stand for 10 seconds, tilted 135 ° with respect to the horizontal plane, and brought into contact with the ground twice at a rate of 10 cm / second from a height of 3 cm. And measuring the haze value 10 times, the value obtained by subtracting the haze value before the test from the average value is within 1.0.
More preferably, the second antifouling layer is the first antifouling layer. That is, the second antifouling layer can be obtained by the same configuration as the first antifouling layer described above.

The arithmetic average roughness (hereinafter also referred to as “Ra”) of the antifouling layer is not particularly limited, but is preferably 5 to 30 nm, more preferably 6 to 25 nm, and particularly preferably 7 to 20 nm. When Ra is 5 nm or more, the contact between the portion having a smaller film thickness than the apex of the convex portion including single particles and the binder and dirt is suppressed, and more excellent antifouling property is obtained. If it is 30 nm or less, it is excellent in abrasion resistance strength. Ra can be measured with a scanning probe microscope.

<Particle>
The aggregate particles constituting the protrusion of the present invention are not particularly limited as long as they can form an aggregate together with a binder described later and can form a protrusion on the surface of the antifouling layer. Examples of the particles include inorganic particles and organic particles, and inorganic particles are preferable. Examples of the inorganic particles include metal oxide particles such as silica, titania, alumina, and zirconia. As the particles, silica particles are preferable. If the particles are silica particles, light scattering is suppressed and the color of the substrate is not impaired. In particular, when the substrate is glass, the particles are preferably silica particles.
The particles may be used alone or in combination of two or more.
When the particles are a combination of two or more, the silica content is preferably 50% by mass or more, and more preferably 75% by mass or more.

The shape of the particles is not particularly limited, but a pearl necklace shape or a chain shape is preferable. As the particles, pearl necklace-like silica is particularly preferable. If the particles are pearl necklace-like silica, when the antifouling layer is formed, protrusions capable of forming more appropriate irregularities are easily formed, and the antifouling property tends to be improved.

In the case of pearl necklace-like particles, the average primary particle diameter of the particles is not particularly limited, but is preferably 5 to 300 nm, more preferably 10 to 100 nm, further preferably 10 to 50 nm, and particularly preferably 10 to 30 nm. When the average particle diameter of the particles is 5 nm or more, it becomes easy to form protrusions and the antifouling property tends to be improved. Moreover, if the average particle diameter of particle | grains is 300 nm or less, a haze value can be made small.

In the case of pearl necklace-like particles, the secondary particle diameter of the particles is preferably 40 to 200 nm, more preferably 50 to 100 nm, and particularly preferably 60 to 90 nm.

In addition, when using a pearl necklace-like particle | grain, you may use together the chain particle with few spherical parts compared with a pearl necklace-like particle within the range which does not impair the effect of this invention. Moreover, you may use a spherical particle together within the range which does not impair the effect of this invention.

The chain particles have, for example, an average primary particle diameter d of 10 to 100 nm, an average length (L) of 60 to 500 nm, and a ratio of the average length to the average primary particle diameter of 3 to 20 nm (L / and chain particles having d).
Examples of the spherical particles include spherical particles having an average primary particle diameter d of 1 to 1000 nm.

Examples of commercially available pearl necklace-like silica particles include ST-PS-S, ST-PS-SO, ST-PS-M, and ST-PS-MO (all of which are pearl necklace-like silica sols manufactured by Nissan Chemical Industries, Ltd.). It is done.
Commercially available chain silica particles include ST-OUP and ST-U (both are chain silica sols manufactured by Nissan Chemical Industries, Ltd.).
Examples of commercially available spherical silica particles include IPA-ST, IPA-STL, and IPA-STZL (all of which are isopropyl alcohol-dispersed silica sols manufactured by Nissan Chemical Industries, Ltd.).

<Binder>
A binder is not specifically limited, For example, an inorganic binder is mentioned. The binder is preferably a hydrophilic inorganic binder because the antifouling property is increased. Examples of the hydrophilic inorganic binder include metal oxides such as silica, alumina, titania, zirconia, tantalum oxide, and tin oxide. The binder is more preferably a silica binder in terms of ease of handling. The silica binder is preferably a hydrolyzate of a silane compound having a hydrolyzable group or a hydrolyzate of silicic acid, and preferably has a low alkali component content. Examples of the silica binder having a low alkali content include a hydrolyzate of an alkoxysilane compound or a hydrolyzate of demineralized silicic acid obtained by removing a part of an alkali metal from an alkali metal salt of silicic acid. Note that these hydrolysates may have an unreacted silanol group (Si—OH) group.

When the binder is a mixture of two or more binders, the silica content is preferably 50% by mass or more, and more preferably 75% by mass or more.
As the binder, a cured product of a binder precursor described later is used.

In the antifouling layer, the volume ratio (particle / binder) of particles capable of forming protrusions (for example, pearl necklace particles, chain particles) to the binder is preferably 7/93 to 95/5. If the volume ratio of the particles to the binder is 7/93 or more, an antifouling layer having an average distance between the apexes of appropriate protrusions can be formed on the substrate surface, and thus the antifouling property tends to be further improved. If it is 95/5 or less, the adhesion between the substrate and the antifouling layer tends to be sufficient.

<Additional ingredients>
The antifouling layer can contain further components as long as the effects of the present invention are not impaired. Further components include surfactants, antifoaming agents, leveling agents, ultraviolet absorbers, viscosity modifiers, antioxidants, fungicides, pigments and the like. The content of the further components is preferably 5% by mass or less, and more preferably 1% by mass or less in the antifouling layer.

<Film thickness>
The thickness of the antifouling layer is not particularly limited, but is preferably 20 to 350 nm, more preferably 30 to 300 nm, and particularly preferably 50 to 300 nm. If the film thickness of the antifouling layer is 20 nm or more, the antifouling property tends to be exhibited sufficiently, and if it is 350 nm or less, the mechanical strength is excellent and the economy is excellent. Here, the film thickness is 10 in descending order from the protrusion having the maximum height in the range of 1.5 μm in the direction parallel to the surface having the antifouling layer of the substrate from the film cross-sectional image obtained by an electron microscope or the like. This is a value obtained by extracting 10 points up to the first protrusion and averaging the heights of the protrusions at the 10 points.

<Anti-fouling property>
This antifouling article has excellent antifouling properties against various stains. As dirt, inorganic dirt such as dust remaining in the atmosphere, alkali wall residue from the concrete wall (water dry spots), water stains, burns on the glass itself, smoke in the atmosphere, automobile exhaust gas, tobacco Organic stains such as smoke and oil. The antifouling article has a better antifouling effect against dust and oil stains. The antifouling property of the antifouling article can be evaluated by, for example, a change in haze value measured by a “dirt adhesion test” (that is, a dry powder sprinkling test) in Examples described later. The change in haze value of the antifouling article is preferably 5% or less, more preferably 2% or less, and particularly preferably 1% or less, when measured by a “dirt adhesion test” in Examples described later. When the change in haze value exceeds 5%, practical antifouling properties cannot be exhibited. The haze value can be measured using a commercially available haze measuring device.

(Anti-fouling layer forming composition)
The antifouling layer forming composition includes particles capable of forming protrusions and a binder precursor.

<Particles that can form protrusions>
As particles capable of forming protrusions, pearl necklace-like silica having an average primary particle diameter of 5 to 300 nm is preferable. When a composition for forming an antifouling layer containing spherical silica particles is applied to the surface of the substrate, the particles are likely to be laminated relatively uniformly, so that the resulting coating does not have irregularities sufficient to exhibit antifouling properties. .

<Binder precursor>
The binder precursor is a component that forms a binder by heat treatment, solvent removal treatment, photocuring treatment, or the like. Examples of the binder precursor include inorganic binder precursors, and examples include a metal oxide precursor such as a silica precursor, an alumina precursor, a titania precursor, a zirconia precursor, a tantalum oxide precursor, and a tin oxide precursor. Examples of the silica precursor include a silane compound having a hydrolyzable group and silicic acid. Examples of the binder precursor other than the silica precursor include a metal compound having a hydrolyzable group. The metal oxide precursor is a component that forms a metal oxide by a hydrolysis reaction. A silica precursor is preferable as the binder precursor. When the antifouling layer-forming composition contains a silica precursor, the adhesion between the antifouling layer to be formed and the substrate can be further improved.
One type of binder precursor may be used alone, or two or more types may be used in combination.

Examples of the silica precursor include silicic acid and a silane compound having a hydrolyzable group. As the silica precursor, one having a low alkali metal content is preferable because it improves the adhesion between the antifouling layer to be formed and the substrate. For example, a part of the alkali metal is removed from the alkali metal salt of silicic acid described later. Desalted silicic acid or alkoxysilane compounds or partially hydrolyzed condensates thereof are preferred.

Examples of silicic acid include orthosilicic acid, metasilicic acid, and metadisilicic acid, with metasilicic acid being preferred. The silicic acid is preferably demineralized silicic acid obtained by removing at least part of the alkali metal from the alkali metal salt of silicic acid (hereinafter also simply referred to as “demineralized silicic acid”). Desalted silicic acid is preferably obtained by a method of reducing alkali metal ions from an aqueous solution of an alkali metal salt of silicic acid using a cation exchange resin. The amount of the alkali metal ion of the desalted silicic acid is not particularly limited, but the alkali metal ion is preferably 0.001 to 1 part by mass, and 0.001 to 0.2 part by mass with respect to 100 parts by mass of silicic acid. More preferred is 0.001 to 0.15 parts by mass. The alkali metal ion concentration of silicic acid can be measured by ICP emission analysis.

The cation exchange resin is not particularly limited, a strongly acidic cation exchange resin (RSO 3 _H type), weakly acidic cation exchange resin (RCOOH type) and the like, a strongly acidic cation exchange resin is a reaction rate This is preferable. The amount of alkali metal ions to be reduced can be adjusted by controlling the amount of cation exchange resin used, the contact time, the contact method, and the like.

Examples of the alkali metal salt of silicate include sodium silicate, lithium silicate, and potassium silicate. Sodium silicate and / or lithium silicate are preferable, and sodium silicate is particularly preferable.

As an aqueous solution of sodium silicate, one having a SiO ₂ / Na ₂ O molar ratio of about 0.5 to 4 is commercially available. An aqueous solution of sodium silicate having a large SiO ₂ / Na ₂ O molar ratio is preferable because alkali metal ions can be easily removed, and an SiO ₂ / Na ₂ O molar ratio of 3 or more is particularly preferable.

As the aqueous solution of lithium silicate, materials having different composition ratios of SiO ₂ / Li ₂ O are known, and materials having a small content ratio of Li ₂ O are preferable because alkali metal ions can be easily removed. Commercially available lithium silicates include those having a SiO ₂ / Li ₂ O molar ratio of 3.5 / 1.0, 4.5 / 1.0, and 7.5 / 1.0. is there. As the aqueous solution of lithium silicate, one having a large SiO ₂ / Li ₂ O molar ratio is preferable because alkali metal ions can be easily removed, and one having a SiO ₂ / Li ₂ O molar ratio of 7 or more is particularly preferable.

A silane compound having a hydrolyzable group is a compound having 1 to 4 hydrolyzable groups bonded to a silicon atom in one molecule. Examples of the hydrolyzable group include an alkoxy group, an isocyanato group, an acyloxy group, an aminoxy group, and a halogen group, and an alkoxy group is preferable. Therefore, an alkoxysilane compound is preferable as the silane compound having a hydrolyzable group. Further, the alkoxysilane compound may be a condensate in which at least some of the molecules are hydrolyzed and condensed (hereinafter also referred to as “partially hydrolyzed condensate of alkoxysilane compound”).

The alkoxysilane compound is a compound having 1 to 4 alkoxy groups bonded to a silicon atom in one molecule.

Examples of the alkoxysilane compound include compounds represented by the following general formula (I).

(R ¹ O) _p SiR ² _(4-p) (I)
In the formula, each R ¹ independently represents an alkyl group having 1 to 4 carbon atoms, R ² independently represents an optionally substituted alkyl group having 1 to 10 carbon atoms, p represents a number from 1 to 4. When a plurality of R ¹ or R ² are present, they may be the same as or different from each other.

R ¹ is an alkyl group having 1 to 4 carbon atoms, and examples thereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and t-butyl, and methyl and ethyl are preferable. The alkyl group having 1 to 10 carbon atoms in R ² is linear or branched, and examples thereof include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, hexyl, decyl and the like. R ² is preferably an alkyl group having 1 to 6 carbon atoms. The substituent in R ² is not particularly limited, but epoxy group, glycidoxy group, methacryloyloxy group, acryloyloxy group, isocyanato group, hydroxy group, amino group, phenylamino group, alkylamino group, aminoalkylamino group, ureido Group, mercapto group and the like. The “alkyl group having 1 to 10 carbon atoms” in R ² means that the alkyl group portion excluding the substituent has 1 to 10 carbon atoms.

Examples of the alkoxysilane compound include tetraalkoxysilane compounds having an alkoxy group bonded to four silicon atoms in one molecule such as tetramethoxysilane and tetraethoxysilane; 3-glycidoxypropyltrimethoxysilane, 3-glycidoxy Propyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-isocyanatopropyltrimethoxy Silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyl 1 to 3 alkoxy groups bonded to silicon atoms in one molecule such as pyrmethyldimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, and 3-mercaptopropyltrimethoxysilane The alkoxysilane compound which has is mentioned. As the alkoxysilane compound, a tetraalkoxysilane compound is preferable.

<Volume ratio>
In the antifouling layer forming composition, the volume ratio of the particles capable of forming protrusions to the binder precursor (particles capable of forming protrusions / binder precursor) is 7/93 to 95/5. The volume ratio between the particles capable of forming the protrusions and the binder precursor is in terms of metal oxide. In a preferred embodiment, when the antifouling layer-forming composition contains pearl necklace-like silica having an average primary particle diameter of 5 to 300 nm and a silica precursor, the pearl necklace-like silica and the silica precursor are converted into silica. The volume ratio (pearl necklace-like silica / silica precursor) is 7/93 to 95/5. The silica precursor is preferably desalted silicic acid or a hydrolyzate of alkoxysilane.
In the antifouling layer forming composition, if the volume ratio in terms of metal oxide of the particles capable of forming protrusions and the binder precursor is less than 7/93, the particles are not sufficiently present on the substrate, and If the stain resistance is inferior and exceeds 95/5, an antifouling layer having sufficient adhesion between the antifouling layer and the substrate cannot be obtained. In addition, when an antifouling layer forming composition contains the partial hydrolysis-condensation product of an alkoxysilane compound, content of the partial hydrolysis-condensation product of an alkoxysilane compound is a conversion amount of a silica.

<Water and acid catalyst>
The antifouling layer forming composition may contain water and an acid catalyst under the condition that a hydrolysis condensate of the binder precursor is obtained.

The antifouling layer forming composition may contain water. When the antifouling layer-forming composition contains water, hydrolysis condensation reaction proceeds. The amount of water is preferably 10 to 500 parts by weight and more preferably 50 to 300 parts by weight with respect to 100 parts by weight of the binder precursor. Here, the amount of the binder precursor is an amount in terms of metal oxide.

The antifouling layer forming composition may contain an acid catalyst. When the antifouling layer-forming composition contains an acid catalyst, it becomes possible to adjust the reaction rate of hydrolysis condensation of the binder precursor. Examples of the acid catalyst include hydrochloric acid, nitric acid, sulfuric acid and the like. The amount of the acid catalyst is preferably 0.1 to 5.0 parts by mass, more preferably 0.2 to 3.5 parts by mass with respect to 100 parts by mass of the binder precursor. Here, the amount of the binder precursor is an amount in terms of metal oxide.

<Solvent>
The antifouling layer forming composition may contain a solvent. There exists a tendency for workability | operativity to improve because an antifouling layer forming composition contains a solvent. The solvent is not particularly limited as long as the dispersibility of the particles capable of forming the protrusions and the binder precursor is good and the reactivity with these components is low. Solvents include alcohols (methanol, ethanol, 2-propanol, etc.), esters (acetic ester (butyl acetate), etc.), ethers (diethylene glycol dimethyl ether, etc.), ketones (methyl ethyl ketone, etc.), water (ion exchange water, etc.), etc. Esters and alcohols are preferred, and alcohols are more preferred. The solvent may be a single type or a combination of two or more types. In addition, at least one of the particles capable of forming the protrusions and the binder precursor may be used alone or as a mixture of two or more and a solvent. In this case, the solvent contained in the mixture may be used as the solvent in the antifouling layer-forming composition, or another solvent may be added to form the antifouling layer-forming composition.

The content of the solvent is not particularly limited, but is preferably 1,000 to 100,000 parts by weight, and 2,000 to 50,000 parts by weight with respect to a total of 100 parts by weight of the particles capable of forming protrusions and the binder precursor. Part is more preferred. If the content of the solvent is 1,000 parts by mass or more with respect to 100 parts by mass in total of the particles capable of forming the protrusions and the binder precursor, hydrolysis and condensation reaction can be prevented from proceeding rapidly. If it is 1,000 parts by mass or less, the hydrolysis and condensation reaction proceed more. Here, the quantity of the particle | grains and binder precursor which can form a protrusion is an amount of metal oxide conversion.

<Additional ingredients>
The antifouling layer-forming composition can contain further components within a range not impairing the effects of the present invention. Examples of such components include surfactants, antifoaming agents, leveling agents, ultraviolet absorbers, viscosity modifiers, antioxidants, fungicides, and pigments.

The content of the further component in the antifouling layer forming composition is not particularly limited, but is preferably 0.02 to 1 part by mass with respect to 100 parts by mass in total of the particles capable of forming the protrusion and the binder precursor, The amount is more preferably 0.02 to 0.5 parts by mass, and particularly preferably 0.02 to 0.3 parts by mass. Here, the amount of the binder precursor is an amount in terms of metal oxide.

[Method for producing antifouling article]
The method for producing an antifouling article comprises, on a substrate, a particle capable of forming a protrusion and a binder precursor, and a volume ratio in terms of metal oxide of the particle capable of forming the protrusion and the binder precursor. However, the antifouling layer forming composition of 7/93 to 95/5 is applied to form the antifouling layer forming composition layer, and the antifouling layer forming composition layer is heat-treated, Forming a dirty layer.
In a more preferred embodiment of the method for producing an antifouling article, a pearl necklace-like silica having an average primary particle size of 5 to 300 nm and a silica precursor are included on a substrate, the pearl necklace-like silica and the silica precursor. The antifouling layer forming composition having a volume ratio in terms of silica of 7/93 to 95/5 to form an antifouling layer forming composition layer, and the antifouling layer forming composition Heating the physical layer to form an antifouling layer.
The application (that is, application) of the antifouling layer-forming composition can be performed by a wet coating method. The wet coating method is not particularly limited, and examples thereof include spin coating, dip coating, spray coating, flow coating, curtain flow coating, die coating, and squeegee coating, and spin coating is preferable. The antifouling layer forming composition is preferably applied to at least a part of the surface of the substrate and applied to the entire surface of at least one main surface of the substrate. The thickness of the antifouling layer-forming composition layer is not particularly limited as long as it is an amount that provides a desired antifouling layer.

The application amount of the antifouling layer-forming composition applied on the substrate is not particularly limited as long as it is an amount that provides the above-mentioned antifouling layer thickness, and the solid content is 1.6 to 1,600 g / m ² . It is preferably 8.0 to 800 g / m ² . In the present invention, the content of the component in terms of solid content refers to the mass of the residue excluding volatile components such as water.

The antifouling layer forming composition layer formed by applying the antifouling layer forming composition on the substrate is heat-treated to form the antifouling layer. The binder precursor may react with the particles by heat treatment. When the antifouling layer forming composition contains pearl necklace-like silica and a silica precursor, the silica precursor reacts to obtain a binder. When the silica precursor is silicic acid and an alkoxysilane compound, the silicic acid and the alkoxysilane compound are hydrolyzed and condensed to obtain silica that is a hydrolyzate of the silicic acid and the alkoxysilane compound. In some cases, at least part of the silicic acid and the alkoxysilane compound is hydrolytically condensed with silanol groups present on the surface of the pearl necklace-like silica particles.

The heat treatment of the antifouling layer forming composition layer can be performed by any heating means such as an electric furnace, a gas furnace, an infrared heating furnace set to a predetermined temperature. The heat treatment temperature is preferably 20 to 700 ° C, more preferably 80 to 500 ° C, and particularly preferably 100 to 400 ° C. When the heat treatment temperature is 20 ° C. or higher, the adhesion between the substrate and the antifouling layer is further improved, and when it is 700 ° C. or lower, deterioration of the substrate due to heat is suppressed, and the productivity is excellent. The heat treatment time varies depending on the heat treatment temperature, but heat treatment for 1 to 180 minutes is preferable, more preferably 5 to 120 minutes, and particularly preferably 10 to 60 minutes. When the heat treatment time is 1 minute or more, the adhesion between the substrate and the antifouling layer is further improved, and when it is 180 minutes or less, deterioration of the base material due to heat is suppressed and the productivity is excellent.

[cover glass]
The antifouling article is, for example, a cover glass. The cover glass is, for example, a cover glass of a solar cell, a condenser lens, or a condenser mirror. A condensing lens or a condensing mirror is used for a concentrating solar power generation device or a concentrating solar power generation device, for example.
The cover glass of the present invention is sprinkled with JIS test powder, left still for 10 seconds, tilted 135 ° with respect to the horizontal surface, and brought into contact with the ground twice at a rate of 10 cm / second from a height of 3 cm. Drop and measure the haze value 10 times, and the value obtained by subtracting the haze value before the test from the average value is within 1.0. This cover glass is preferable because it exhibits high antifouling performance even when installed in an environment with little rainwater.
[Other uses]
Applications of this antifouling article include cover glass, window glass (for example, window glass for transportation equipment such as automobiles, railways, ships, airplanes), walls (for example, partitions, road walls, etc.), refrigerated showcases. , Mirrors (for example, vanity mirrors, bathroom mirrors, etc.), optical equipment, tiles, toilet bowls, bathtubs, bathroom walls, vanity tables, curtain walls, aluminum sashes, faucets, building boards, lenses, A condensing mirror is mentioned.
This antifouling article is particularly suitable for outdoor use in areas with little rain, such as deserts.

Hereinafter, examples of the present invention will be further described, but the present invention is not limited to these examples. Examples 1 to 3 and 16 described below are examples, and examples 4 to 15 and 17 are comparative examples.

[Example 1]
(Preparation of binder precursor (1) (desalted sodium silicate solution))
While stirring 237.5 g of distilled water, sodium silicate No. 4 (manufactured by Nippon Chemical Industry Co., Ltd., (SiO ₂ : 24.0% by mass, Na ₂ O: 7.0% by mass. SiO ₂ / Na ₂ 62.5 g of a molar ratio of O: 3.5 / 1) and 180 g of cation exchange resin (manufactured by Mitsubishi Chemical Corporation, Diaion SK1BH) were added in this order, and the mixture was stirred for 10 minutes or more and then positively filtered by suction filtration. The ion exchange resin was separated, and a binder precursor (1), which is a silicon oxide precursor, was obtained as a desalted sodium silicate solution having a solid content concentration in terms of silica of 5% by mass.

(Preparation of antifouling layer forming composition)
A pearl necklace-like silica in which spherical particles of 10 to 18 nm selected as particles capable of forming protrusions are bonded to a length of 80 to 120 nm while stirring 6.58 g of 2-propanol (manufactured by Junsei Kagaku) 1.19 g of a dispersion liquid (manufactured by Nissan Chemical Co., Ltd., Snowtex PS-SO, average primary particle diameter 15 nm, average secondary particle diameter 88 nm) and 2.18 g of the binder precursor (1) were added in this order, Antifouling layer-forming composition having a silica-converted solid content of 2.95% by mass, and a silica-converted solid content volume ratio of particles (pearl necklace-like silica) and binder precursor (desalted sodium silicate liquid) of 60/40. A product (A1) was prepared.

(Manufacture of antifouling products)
A soda lime glass plate (made by Asahi Glass, product number FL3.5, length 100 mm, width 100 mm, thickness 3.5 mm) selected as a substrate and set at a room temperature is set on a spin coater, and an antifouling layer forming composition ( 2.0 g of A1) was dropped on the surface of a soda lime glass plate, spin-coated, then heat-treated at 300 ° C. for 30 minutes, and the antifouling layer forming composition layer was baked to form an antifouling layer. A product was manufactured. Scanning electron micrographs of the surface and cross section of the antifouling article obtained in Example 1 are shown in FIGS. 2 and 3, respectively.

[Examples 2 to 5]
Antifouling layer forming compositions A2 to A5 were prepared in the same manner as in Example 1 except that the volume ratio of particles to binder precursor (particle / binder precursor) was changed to the amount shown in Table 1. Subsequently, an antifouling article was produced in the same manner as in Example 1 using the antifouling layer forming compositions A2 to A5.

[Examples 6 to 10]
The pearl necklace-like silica dispersion was changed to a spherical silica dispersion having an average primary particle diameter of 11 nm (manufactured by Nissan Chemical Co., Snowtex OS), and the volume ratio of the particles to the binder precursor was changed to the amount shown in Table 1. Except for the above, antifouling layer-forming compositions A6 to A10 were prepared in the same manner as in Example 1. Next, an antifouling article was produced in the same manner as in Example 1 using the antifouling layer forming compositions A6 to A10.

[Examples 11 to 15]
The pearl necklace-like silica dispersion was changed to a spherical silica dispersion (Nissan Chemical Co., Snowtex O-40) with an average primary particle size of 30 nm, and the volume ratio of the particles to the binder precursor was changed to the amount shown in Table 1. Except that, antifouling layer forming compositions A11 to A15 were prepared in the same manner as in Example 1. Subsequently, an antifouling article was produced in the same manner as in Example 1 using the antifouling layer forming compositions A11 to A15.

[Example 16]
(Preparation of binder precursor (2) (solution of partially hydrolyzed condensate of alkoxysilane compound))
While stirring 16.45 g of 2-propanol (manufactured by Junsei Kagaku Co., Ltd.), 1.18 g of methyl silicate polymer (manufactured by Tama Chemical Industry Co., Ltd., M silicate 51, solid content 51% in terms of silica, methanol solvent), 2.26 g of distilled water and a 10% by mass nitric acid aqueous solution (manufactured by Kanto Chemical Co., Inc.) were added in this order, and the mixture was stirred at 25 ° C. for 60 minutes to obtain an alkoxysilane compound having a silica-converted solid content concentration of 3% by mass. A binder precursor (2), which is a silicon oxide precursor, was obtained as a solution of the partially hydrolyzed condensate.

(Preparation of antifouling layer forming composition)
An antifouling layer-forming composition A16 was prepared in the same manner as in Example 1 except that the binder precursor (1) was changed to the binder precursor (2).

(Manufacture of antifouling products)
An antifouling article was produced in the same manner as in Example 1 using the antifouling layer forming composition A16.

[Example 17]
The glass plate not coated with the antifouling composition and having no antifouling layer was evaluated as it was.

[Evaluation of antifouling products]
The evaluation of the antifouling article in each example was performed as follows.

(Average primary particle size of particles)
From the image obtained by observing the surface of the antifouling layer from above with a scanning electron microscope (manufactured by Hitachi, Ltd., model: S-4800) with respect to the surface having the antifouling layer of the antifouling article, 100 particles were extracted for the purpose, and the average value of the diameter of each particle was defined as the average primary particle size of the particles.

(Surface roughness (Ra))
It measured using the scanning probe microscope (SII nanotechnology company make, type SPA400).
<Microscope setting conditions>
The cantilever was measured with SI-DF40 (with rear surface AL), 256 XY data, and scanning area of 10 μm × 10 μm.

(Vertex distance)
The cross section of the antifouling article is observed with a scanning electron microscope (manufactured by Hitachi, Ltd., model: S-4800), and the obtained image is randomly selected in a direction parallel to the surface of the glass plate having the antifouling layer. In the range of 1.5 μm extracted, the projection having the highest height from the surface of the glass plate is used as a reference, and the projection having a height of 90% or more of the height is between apexes of adjacent projections. All the distances were measured, and the average value was calculated.

(Convex coverage)
The surface of the antifouling layer is observed from above with the scanning electron microscope (manufactured by Hitachi, Ltd., model: S-4800) with respect to the main surface of the substrate. From the obtained image, image conversion software (image J) is used. The area ratio of the part to which the particles adhered in the range of 1 μm × 1 μm extracted at random was calculated.

(Stain adhesion test)
The antifouling article was cut into 5 cm × 5 cm, and the initial haze value was measured. Thereafter, 0.5 g of JIS Z 8901 standard test powder 1 (silica sand) 0.5 g was sprinkled evenly on the antifouling article using a tea strainer. After standing for 10 seconds, the antifouling article is tilted 135 ° with respect to the horizontal plane, and the edge of the substrate is brought into contact with the ground twice at a speed of 10 cm / second from a height of 3 cm, the powder is dropped, and the haze value is again measured Was measured. This was repeated 10 times, and the value obtained by subtracting the initial haze value from the average value of the 8th, 9th and 10th haze values was defined as a change in haze value (ΔHaze) after the dry sanding test.

<Measurement conditions of haze value>
The haze of the translucent member was measured with a C light source using a haze measuring device (Bic Gardner, model name: haze guard plus).

In Table 1, the particles indicated by the symbols described in the particle column are as follows.
PS-SO: Snowtex PS-SO (manufactured by Nissan Chemical Co., Ltd.)
OS: Snowtex OS (manufactured by Nissan Chemical Co., Ltd.)
O-40: Snowtex O-40 (manufactured by Nissan Chemical Co., Ltd.)

As shown in Table 1, it can be seen that the antifouling articles of Examples 1 to 3 and Example 16 are excellent in antifouling properties from the results of the dry sanding test. On the other hand, Example 17 having no antifouling layer did not have sufficient antifouling properties. The antifouling article of Example 5 in which the proportion of the area where particles are present on the surface of the antifouling layer was less than 7% did not have sufficient antifouling properties. The antifouling articles of Examples 6 to 15 in which the distance between the vertices of the antifouling layer was less than 100 nm were not sufficiently antifouling.

The antifouling article of the present invention is superior in antifouling properties as compared with conventional antifouling articles. The antifouling article of the present invention includes window glass (for example, window glass for transportation equipment such as automobiles, railways, ships, airplanes), cover glass for solar cells, walls (for example, partitions, road walls, etc.), refrigerated showcases. , Mirrors (for example, vanity mirrors, bathroom mirrors, etc.), optical equipment, tiles, toilet bowls, bathtubs, bathroom walls, vanity tables, curtain walls, aluminum sashes, faucets, building boards, lenses, etc. Can be used for
It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2014-147454 filed on July 18, 2014 are incorporated herein by reference. .

1: antifouling article, 2: substrate, 3: particles, 4: binder, 5: protrusion, 6: antifouling layer

Claims

A base, and an antifouling layer disposed on the base and having a plurality of protrusions containing aggregates of particles and a binder on the surface,
With respect to the protrusion T having a height of 90% or more with reference to the protrusion having the maximum height from the substrate surface, the average value of the distances between the apexes of the adjacent protrusions T is 100 to 1. , 000 nm,
The antifouling article, wherein the ratio of the total covered area of the particles to the area of the substrate on which the antifouling layer is disposed is 12 to 100%.
An antifouling article comprising a substrate and an antifouling layer disposed on the substrate,
The antifouling layer comprises an aggregate of particles and a binder,
The surface of the antifouling layer has a plurality of protrusions,
The antifouling layer is sprinkled with JIS test powder and allowed to stand for 10 seconds, tilted 135 ° with respect to the horizontal plane, and brought into contact with the ground twice at a speed of 10 cm / second from a height of 3 cm to drop the powder. The antifouling article having a value obtained by repeating the measurement of the haze value 10 times and subtracting the haze value before the test from the average value is within 1.0.
The antifouling article according to claim 1 or 2, wherein the surface Ra of the antifouling layer is 5 to 30 nm.
The antifouling article according to any one of claims 1 to 3, wherein the average primary particle diameter of the particles is 5 to 300 nm.
The antifouling article according to any one of claims 1 to 4, wherein the particles are pearl necklace particles or chain particles.
The antifouling article according to any one of claims 1 to 5, wherein the particles are pearl necklace-like silica.
The antifouling article according to any one of claims 1 to 6, wherein a volume ratio of the particles to the binder is 7/93 to 95/5.
A cover glass for a solar cell having an antifouling layer on the surface, the antifouling layer comprising an aggregate of particles and a binder, and the surface of the antifouling layer has a plurality of protrusions, The antifouling layer is sprinkled with JIS test powder and allowed to stand for 10 seconds, tilted 135 ° with respect to the horizontal plane, and brought into contact with the ground twice at a speed of 10 cm / second from a height of 3 cm to drop the powder. Measure the haze value 10 times and the solar glass cover glass has a value obtained by subtracting the haze value before the test from the average value within 1.0.
A pearl necklace-like silica having an average primary particle diameter of 5 to 300 nm and a silica precursor are included, and a volume ratio of the pearl necklace-like silica and the silica precursor in terms of silica is 7/93 to 95/5. An antifouling layer forming composition.
The antifouling layer forming composition according to claim 9, wherein the silica precursor is a desalted silicic acid or a hydrolyzate of alkoxysilane.
A volume ratio in terms of metal oxide between the particles capable of forming protrusions and a binder precursor on a substrate and the particles capable of forming protrusions and the binder precursor is 7/93 to 95/5. Applying the antifouling layer forming composition, and forming an antifouling layer forming composition layer,
Heat-treating the antifouling layer forming composition layer to form an antifouling layer;
A method for producing an antifouling article comprising
A pearl necklace-like silica having an average primary particle diameter of 5 to 300 nm and a silica precursor are included on a substrate, and the volume ratio of the pearl necklace-like silica and the silica precursor in terms of silica is 7/93. Applying the antifouling layer-forming composition of ~ 95/5 to form an antifouling layer-forming composition layer;
Heat-treating the antifouling layer forming composition layer to form an antifouling layer;
A method for producing an antifouling article comprising
The antifouling property according to claim 12, wherein the silica precursor is demineralized silicic acid and / or an alkoxysilane compound or a partially hydrolyzed condensate thereof obtained by removing a part of an alkali metal from an alkali metal salt of silicic acid. Article manufacturing method.