JP2015049319A - Article having transparent base material and antifouling-antireflection film and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an article having a transparent base material and an antifouling-antireflection film with an improved antifouling property while maintaining an antireflection performance of a silica-based porous film, and a manufacturing method thereof.SOLUTION: An article includes a transparent base material and an antifouling-antireflection film disposed on the transparent base material. The antifouling-antireflection film includes a silica-based porous film and an antifouling layer, from the transparent base material side in this order. The silica-based porous film includes a hollow fine particle and a silica-based matrix. A mass ratio of SiOconversion solid contents of the hollow fine particle and the silica-based matrix (ratio of hollow fine particle/silica-based matrix) is 30/70-65/35. The antifouling layer includes a plurality of nano sheets made of a low refraction material whose refraction index is 1.4-1.65. The average film thickness of the antifouling layer is 0.4-15 nm.

Description

  The present invention relates to an article comprising a transparent substrate and an antifouling antireflection film and a method for producing the same.

Articles having an antireflection film on the surface of a transparent substrate such as a glass plate are used as cover members for solar cells, various displays and their front plates, various window glasses, touch panel cover members, and the like.
The antireflection film is disposed on the outermost layer of the article because of its function. For this reason, the antireflection film is required to have antifouling properties (that dirt is difficult to adhere and can be easily removed even if it adheres).

One example of an antireflection film used for a transparent substrate such as a glass plate is a silica-based porous film (for example, Patent Document 1). Since the silica-based porous film has pores in a matrix containing silica as a main component, the refractive index is lower than that in the case where there are no pores.
However, since the silica-based porous film has many fine open holes and irregularities on the surface, dirt such as oil dirt and resin is likely to adhere, and the attached dirt is difficult to remove.
For example, in the manufacturing process of the solar cell, a step of bonding the cover member and the solar cell with a sealing material is performed. When a silica-based porous film is used as the antireflection film, there is a problem that EVA, which is a sealing material, penetrates into the silica-based porous film in the manufacturing process and the antireflection performance is lowered. Moreover, the soaked EVA is difficult to remove from the silica-based porous membrane, and even after the removal, the portion of the silica-based porous membrane soaked with EVA has a different color from the other portions and looks good. There are also problems such as bad.

As a countermeasure against the problems in the above manufacturing process and the like, a method of applying a fluorine-based coating agent to the surface of a silica-based porous film has been proposed (for example, Patent Document 2). That is, in this method, the antifouling property against oil stains and EVA can be improved by applying a fluorine-based coating agent.
However, depending on the coating agent, there is a concern that the antireflection performance may be deteriorated by immersing in the silica-based porous film during coating.

Special table 2010-509175 JP-A-5-330856

  The present invention has been made in view of the above circumstances, and an article comprising a transparent base material and an antifouling antireflection film, which has improved antifouling properties while maintaining the antireflection performance of the silica-based porous film, and its An object is to provide a manufacturing method.

The present invention has the following aspects.
[1] A transparent substrate and an antifouling antireflection film provided on the transparent substrate,
The antifouling antireflection film has a silica-based porous film and an antifouling layer in order from the transparent substrate side,
The silica-based porous membrane includes hollow fine particles and a silica-based matrix, and the mass ratio (hollow fine particle / silica-based matrix ratio) of the hollow fine particles and the silica-based matrix in terms of SiO ₂ solid content is 30/70 to 65. / 35,
The antifouling layer comprises a plurality of nanosheets made of a low refractive material having a refractive index of 1.4 to 1.65, and the average film thickness of the antifouling layer is 0.4 to 15 nm.
[2] The article according to [1], wherein the hollow fine particles have an average primary particle diameter of 5 to 150 nm.
[3] The ratio of the average film thickness of the antifouling layer and the silica-based porous film (average film thickness of the antifouling layer / average total film thickness of the silica-based porous film) is 0.0013 to 0.5. [1] or [2].
[4] The article according to any one of [1] to [3], wherein the nanosheet is derived from an inorganic layered compound selected from a layered polysilicate and a clay mineral.
[5] The article according to any one of [1] to [4], wherein the transparent substrate has an undercoat layer on the antifouling antireflection film side.
[6] A method for producing an article, comprising a transparent base material and an antifouling antireflection film provided on the transparent base material,
A silica-based porous film-forming coating composition containing a dispersion medium, hollow microparticles, and a silica-based matrix precursor is applied onto the transparent substrate, and calcined or dried, whereby the hollow microparticles and the silica-based matrix SiO _2. A step of forming a silica-based porous film having a mass ratio of converted solids (hollow fine particles / silica-based matrix ratio) of 30/70 to 65/35;
On the surface of the porous silica film, a coating composition for forming an antifouling layer containing a plurality of nanosheets made of a low refractive material having a refractive index of 1.4 to 1.65 and a dispersion medium for the nanosheets is applied. Drying and forming an antifouling layer having an average film thickness after drying of 0.4 to 15 nm;
A method for producing an article, comprising:
[7] The method for producing an article according to [6], wherein the drying temperature in the step of forming the antifouling layer is 300 ° C. or lower.

  ADVANTAGE OF THE INVENTION According to this invention, the article | item provided with the transparent base material and antifouling antireflection film which improved antifouling property, maintaining the antireflection performance of a silica type porous membrane, and its manufacturing method can be provided.

It is a schematic sectional drawing which shows one Embodiment of the articles | goods of this invention. It is a schematic sectional drawing which shows other embodiment of the articles | goods of this invention. 4 is an electron micrograph of a cross section of an article obtained in Example 3.

<One Embodiment of the Present Invention>
FIG. 1 shows a schematic cross-sectional view of an embodiment of the article of the present invention.
The article 1 of the present embodiment includes a transparent substrate 10 and an antifouling antireflection film 20 formed on the surface of the transparent substrate 10.

(Transparent substrate 10)
Examples of the shape of the transparent substrate 10 include a plate and a film.
Examples of the material of the transparent substrate 10 include glass and resin.
Examples of the glass include soda lime glass, borosilicate glass, aluminosilicate glass, and alkali-free glass.
Examples of the resin include polyethylene terephthalate, polycarbonate, triacetyl cellulose, polymethyl methacrylate, and the like.

As the transparent substrate 10, a glass plate is preferable.
The glass plate may be a smooth glass plate formed by a float method or the like, or may be a template glass having irregularities on the surface. Further, not only flat glass but also glass having a curved surface shape may be used.
The thickness of the glass plate is not particularly limited, and glass having a thickness of 10 mm or less can be used. The thinner the thickness, the lower the light absorption, which is preferable for the purpose of improving the transmittance.

When a glass plate is soda lime glass, what has the following composition is preferable.
In mass percentage display based on oxide,
SiO _2: 65~75%,
Al ₂ O _3: 0~10%,
CaO: 5 to 15%,
MgO: 0 to 15%,
Na ₂ O: 10~20%,
K ₂ O: 0 to 3%,
Li ₂ O: 0 to 5%,
Fe ₂ O ₃ : 0 to 3%,
TiO _2: 0~5%,
CeO ₂ : 0 to 3%,
BaO: 0 to 5%,
SrO: 0 to 5%,
B ₂ O _3: 0~15%,
ZnO: 0 to 5%,
ZrO ₂ : 0 to 5%,
SnO ₂ : 0 to 3%,
SO ₃ : 0 to 0.5%.

When a glass plate is an alkali free glass, what has the following composition is preferable.
In mass percentage display based on oxide,
SiO _2: 39~70%,
Al ₂ O ₃ : 3 to 25%,
B ₂ O _3: 1~30%,
MgO: 0 to 10%,
CaO: 0 to 17%,
SrO: 0 to 20%,
BaO: 0 to 30%.

When the glass plate is a mixed alkali glass, those having the following composition are preferred.
In mass percentage display based on oxide,
SiO _2: 50~75%,
Al ₂ O _3: 0~15%,
MgO + CaO + SrO + BaO + ZnO: 6 to 24%,
_{Na 2 O + K 2 O:} 6~24%, including.

  When used as a cover glass for a solar cell, the glass plate is preferably a satin-patterned template glass with an uneven surface. As the template glass, soda lime glass (white plate glass) having a lower iron component ratio (high transparency) than soda lime glass (blue plate glass) used for ordinary window glass or the like is preferable.

  The glass plate may be tempered in advance. The strengthening treatment includes physical strengthening in which the glass plate is air-cooled after being exposed to a high temperature, or an alkali with a small atomic diameter present on the outermost surface of the glass substrate by immersing the glass plate in a molten salt containing an alkali metal. Examples include chemical strengthening that replaces a metal (ion) with an alkali metal (ion) having a large atomic diameter present in a molten salt. By the strengthening treatment, the strength of the glass is improved, and for example, it is possible to reduce the plate thickness while maintaining the strength.

(Anti-fouling antireflection film 20)
The antifouling antireflection film 20 includes a silica-based porous film 21 and an antifouling layer 24 in order from the transparent substrate 10 side.

{Silica porous film 21}
The silica-based porous membrane 21 includes hollow fine particles 22 and a silica-based matrix 23, and a mass ratio (hollow fine particles / silica-based matrix ratio) of the hollow fine particles 22 and the silica-based matrix 23 is 30/70 to 65/35. It is.
Further, the antifouling layer 24 side of the silica-based porous membrane 21 has gentle irregularities corresponding to the shape of the hollow fine particles 22 closest to the antifouling layer 24.

  The surface side of the silica-based porous membrane 21 preferably has few open holes, and more preferably has no open holes. If there are few or no open holes, the synergistic effect with the antifouling layer 24 can greatly suppress the occurrence of defects due to, for example, the penetration of EVA in the solar cell manufacturing process.

Hollow fine particles 22:
Since the hollow fine particles 22 have cavities inside, the refractive index is lower than that of the solid fine particles. Therefore, the silica-based porous film 21 filled with the hollow fine particles 22 has a sufficiently low refractive index, and as a result, has a low reflectance.

Examples of the hollow fine particles 22 include those having a metal oxide outer shell and a hollow inside the outer shell. From the viewpoint of relatively low refractive index and excellent chemical stability, hollow SiO ₂ fine particles are preferable.

  The average primary particle diameter of the hollow fine particles 22 is preferably 5 to 150 nm, and more preferably 50 to 100 nm. If the average primary particle diameter of the hollow fine particles 22 is 5 nm or more, the reflectance of the silica-based porous film 21 is sufficiently low. If the average primary particle diameter of the hollow fine particles 22 is 150 nm or less, the irregularities on the outermost surface of the silica-based porous membrane 21 are reduced, the antifouling property is improved, and the hollow fine particles 22 are densely packed and have a refractive index. Is sufficiently low.

The average primary particle diameter of the hollow fine particles 22 is obtained as follows.
The hollow fine particles 22 are observed with a scanning electron microscope (hereinafter referred to as SEM) or a transmission electron microscope (hereinafter referred to as TEM), and 100 hollow fine particles 22 are randomly selected and each hollow fine particle 22 is selected. The particle diameters of 100 hollow fine particles 22 are averaged to determine the particle diameter.

  The variation coefficient of the average primary particle diameter of the hollow fine particles 22 is preferably 0.5 or less, and more preferably 0.3 or less. If the coefficient of variation is 0.5 or less, that is, if the particle size distribution is sufficiently narrow and the particle diameters of the hollow fine particles 22 are uniform, the hollow fine particles 22 are easily packed closely, and the voids between the hollow fine particles 22 are reduced. it can. Further, the variation in the gap between the hollow fine particles 22 is reduced, and the silica-based matrix 23 easily enters the gap between the hollow fine particles 22. Moreover, the unevenness | corrugation of the outermost surface of the silica type porous membrane 21 becomes small, and antifouling property improves.

The coefficient of variation of the average primary particle diameter of the hollow fine particles 22 is obtained as follows.
The hollow fine particles 22 are observed by SEM or TEM, 100 hollow fine particles 22 are randomly selected, the particle diameter of each hollow fine particle 22 is measured, the standard deviation of the particle size distribution and the average primary particle diameter are obtained, and the fluctuation The coefficient (standard deviation / average primary particle size) is determined.

  The sphericity of the hollow fine particles 22 is preferably 0.8 or more, and more preferably 0.9 or more. If the sphericity of the hollow fine particles 22 is 0.8 or more, that is, close to a true sphere, the hollow fine particles 22 are easily packed densely, and the voids between the hollow fine particles 22 can be reduced. Further, the variation in the gap between the hollow fine particles 22 is reduced, and the silica-based matrix 23 easily enters the gap between the hollow fine particles 22. Moreover, the unevenness | corrugation of the outermost surface of the silica type porous membrane 21 becomes small, and antifouling property improves.

The sphericity of the hollow fine particles 22 is obtained as follows.
The hollow fine particles 22 are observed with an SEM or a TEM, 100 hollow fine particles 22 are randomly selected, the major axis and minor axis of each hollow fine particle 22 are measured, and the sphericity (minor axis / major axis) is obtained. The sphericity of the hollow fine particles 22 is averaged.

Silica-based matrix 23:
The silica matrix 23 is a matrix for filling the voids between the hollow fine particles 22. The silica matrix 23 covers the antifouling layer 24 side of the hollow fine particles 22 so that the hollow fine particles 22 on the antifouling layer 24 side of the silica porous membrane 21 do not directly contact the antifouling layer 24. May be.

  “Silica-based matrix” refers to a matrix mainly composed of silica. If the matrix is mainly composed of silica, the refractive index (reflectance) of the silica-based porous film 21 tends to be low. In addition, chemical stability, adhesion to the transparent substrate 10 such as a glass plate, wear resistance, and the like are improved.

That the matrix is mainly composed of silica means that the proportion of silica is 90% by mass or more of the matrix (100% by mass).
As a matrix, what consists essentially of silica is preferable. The phrase “consisting essentially of silica” means that it is composed only of silica excluding inevitable impurities.

  The matrix may contain a small amount of components other than silica. The components include Li, B, C, N, F, Na, Mg, Al, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, and Sr. , Y, Zr, Nb, Ru, Pd, Ag, In, Sn, Hf, Ta, W, Pt, Au, Bi and compounds such as one or more ions and oxides selected from lanthanoid elements .

  The silica-based matrix 23 includes, for example, a dispersion medium, the hollow fine particles 22 dispersed in the dispersion medium, and a matrix precursor dissolved or dispersed in the dispersion medium, as will be described later in the “Product 10 Production Method”. A coating composition for forming an antifouling antireflection film containing a body is applied and baked. As the matrix precursor, for example, a hydrolyzate of alkoxysilane is used.

Mass ratio of hollow fine particles 22 and silica-based matrix 23:
The mass ratio (hollow particle / silica matrix ratio) of the hollow fine particles 22 and the silica-based matrix 23 in terms of SiO ₂ is 30/70 to 65/35. From the viewpoint of improving the antifouling property, the hollow fine particle / silica matrix ratio is preferably 50/50 to 60/40.
As described above, the silica-based matrix 23 is substantially made of silica, but may contain inevitable impurities. In the present specification, the mass of SiO ₂ converted solid content of the silica-based matrix means the mass of only silica excluding the inevitable impurities.
If the hollow fine particle / silica matrix ratio is equal to or higher than the lower limit value, the hollow fine particles 22 are likely to be densely packed in the silica porous film 21, so that the refractive index is lowered and the reflectance is kept sufficiently low. Can do. On the other hand, if it is less than or equal to the above upper limit value, the silica matrix 23 is sufficiently filled between the hollow fine particles 22, and voids are hardly formed between the hollow fine particles 22, so that the antifouling property is improved.

Other fine particles:
The silica-based porous membrane 21 may contain other fine particles in addition to the hollow fine particles 22.
Examples of the other fine particles include metal oxide fine particles, metal fine particles, pigment-based fine particles, and resin fine particles. The shape of the other fine particles may be, for example, a hollow structure or a solid structure.

As the material of the metal oxide fine particles, Al ₂ O ₃ , SiO ₂ , SnO ₂ , TiO ₂ , ZrO ₂ , ZnO, CeO ₂ , Sb-containing SnO _X (ATO), Sn-containing In ₂ O ₃ (ITO), RuO ₂ etc. are mentioned.
Examples of the material of the metal fine particles include metals (Ag, Ru, etc.), alloys (AgPd, RuAu, etc.) and the like.
Examples of the pigment-based fine particles include inorganic pigments (titanium black, carbon black, etc.) and organic pigments.
Examples of the resin fine particle material include polystyrene and melanin resin.

Examples of the shape of the other fine particles include a spherical shape, an elliptical shape, a needle shape, a plate shape, a rod shape, a cone shape, a columnar shape, a cube shape, a rectangular shape, a diamond shape, a star shape, and an indefinite shape. The other fine particles may be present in a state where each fine particle is independent, each fine particle may be linked in a chain, or each fine particle may be aggregated.
Other fine particles may be used alone or in combination of two or more.

The amount of the other fine particles is preferably such that the effect of the present invention is not impaired. Specifically, when the hollow fine particles 22 are 100 parts by mass, 200 parts by mass or less is preferable, and 100 parts by mass or less is more preferable.
The average primary particle diameter of other fine particles, the coefficient of variation of the average primary particle diameter, and the sphericity are preferably the same as those of the hollow fine particles 22.

Other optional ingredients:
The silica-based porous membrane 21 may contain other optional components such as terpene derivatives and additives in addition to the hollow fine particles 22, the silica-based matrix 23, and other fine particles.
The terpene derivatives, additives, and the like will be described in detail in “Other optional components” in “Product 10 production method” described later.

Average total film thickness of the silica-based porous film 21:
30-300 nm is preferable and, as for the average total film thickness of the silica type porous membrane 21, 40-200 nm is more preferable. If the average total film thickness of the silica type porous membrane 21 is 30 nm or more, light interference will occur and antireflection performance will be expressed. If the average total film thickness of the silica-based porous film 21 is 300 nm or less, the film can be formed without generating cracks.
The average total film thickness of the silica-based porous film 21 is measured by a reflection spectral film thickness meter.
The reflectance of the silica-based porous film 21 is the lowest value (so-called bottom reflectance) within a wavelength range of 300 to 1200 nm, preferably 2.6% or less, and more preferably 1.0% or less.

{Anti-fouling layer 24}
The antifouling layer 24 contains a plurality of nanosheets. The nanosheet is made of a low refractive material having a refractive index of 1.4 to 1.65.
The refractive index of the low refractive material is 1.4 to 1.65, preferably 1.4 to 1.6.
The refractive index of the low refractive material constituting the nanosheet is a value obtained by calculating from the reflectance obtained by spectral reflectance measurement.

Nanosheet:
The low refractive material having a refractive index of 1.4 to 1.65 may be any material having a refractive index within the above range, and can be appropriately selected from known nanosheets. Here, the nanosheet is a planar substance obtained by peeling off the inorganic layered compound.
The nanosheet made of the low refractive index material is preferably derived from an inorganic layered compound selected from layered polysilicate (refractive index 1.45) and clay mineral (refractive index 1.56 to 1.58). The nanosheet derived from the inorganic layered compound has a lower hydrophobicity than the fluorine-based coating agent, and has a relatively low water repellency on the surface of the antifouling layer formed. Therefore, if the article 1 includes the antifouling layer 24 including the nanosheet derived from the inorganic stratiform compound, it is likely to be generated by a fluorine-based coating agent when installed outdoors, and the dirt does not flow down uniformly due to rainwater or the like. It is difficult to cause problems such as remaining rainwater and traces of running water. Moreover, it becomes easy to maintain a favorable external appearance over a long period of time.
The inorganic layered compound has a structure in which a plurality of nanosheets are laminated, and natural products and synthetic products are commercially available. A nanosheet can be obtained by peeling off the layer constituting the inorganic layered compound.
In the present invention, the clay mineral means one having an octahedral structure such as AlO _{6 in the} crystal structure, and the layered polysilicate is different from the clay mineral in that it does not have the octahedral structure.

Examples of the layered polysilicate include kanemite, macatite, magadiite, kenyanite, octosilicate and the like.
The composition of the layered polysilicate can be represented by the following composition formula (1). Examples of the alkali metal atom in M include Na, K, and Li.
M ₂ O · xSiO ₂ · yH ₂ O (1) [wherein, M is an alkali metal atom, x is an integer of 2 to 40, and y is an integer of 1 to 20. ]

  Examples of the clay mineral include smectite, vermiculite, layered double hydroxide (LDH) and the like. Examples of the smectite include 2-octahedron type (saponite, hectorite, etc.) and 3-octahedron type (montmorillonite, beidellite, etc.).

The composition of 2-octahedral smectite can be expressed by the following composition formula (2) (including interlayer cations). The composition of 3-octahedron smectite can be expressed by the following composition formula (3) (including interlayer cations).
(M ¹ , M ² ) _0.3 (M ³ , M ⁴ ) ₃ (Si, Al) ₄ O ₁₀ (F, OH) ₂ .4H ₂ O (2)
(M ¹ , M ² ) _0.3 (M ³ , M ⁴ ) ₂ (Si, Al) ₄ O ₁₀ (F, OH) ₂ .4H ₂ O (3)
In the formula, M ^{1 to} M ⁴ are each independently an alkali metal atom, an alkaline earth metal atom, or a transition metal atom. Examples of the alkali metal atom are the same as described above. Examples of the alkaline earth metal include Mg and Ca. Examples of transition metal atoms include Fe and Al.

The composition of vermiculite can be expressed by the following composition formula (4).
(Mg, Fe, Al) ₃ (Al, Si) ₄ O ₁₀ (OH) ₂ .4H ₂ O (4)

The composition of LDH can be expressed by the following composition formula (5) (including interlayer anions).
[M ⁵ _1-p M ⁶ _p (OH) ₂ ] · [A _{p / n} · qH ₂ O] (5)
In the formula, M ⁵ is a divalent metal ion (Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , Ni ²⁺ etc.), M ⁶ is a trivalent metal ion (Al ³⁺ , Fe ³⁺ , Cr ³⁺ etc.), A is an n-valent anion, and n is an integer of 1 to 3. Examples of A include Cl ⁻ , NO ³⁻ , CO ₃ ^{2− and the} like.

  Of the above, the inorganic layered compound is preferably a clay mineral, and particularly preferably smectite. In the layered polysilicate, hydroxyl groups are exposed on the layer surface, whereas in the clay mineral, the hydroxyl groups are not exposed on the layer surface. For this reason, compared with the nanosheet obtained from the layered polysilicate, the nanosheet obtained from the clay mineral has weak adhesion to the silica-based porous membrane 21, and the antifouling layer 24 is easily washed away by exposure outdoors. As the antifouling layer 24 disappears with time, the low reflection characteristics of the silica-based porous film 21 are sufficiently developed.

As the nanosheet material, titanium oxides such as Ti _0.91 O ₂ and Ti _1.73 Li _0.27 O ₂ , manganese oxides such as MnO ₂ , oxidations such as Nb ₆ O ₁₇ and Nb ₃ O _8, etc. Transition metal oxides such as niobium and tungsten oxides such as WO ₃ ; transition metal chalcogenides such as MoS ₂ ; layered perovskites such as Ca ₂ Nb ₃ O ₁₀ and La ₂ Nb ₂ O ₇ However, these materials have low transparency or are transparent but have a high refractive index. Therefore, when a nanosheet derived from these materials is used for the antifouling layer, the antireflection performance is lowered, which is not preferable.

  The average thickness of the nanosheet is preferably 0.4 to 15 nm, and more preferably 0.4 to 10 nm. If the average thickness of the nanosheet is 0.4 nm or more, the structure of the individual nanosheets is not easily destroyed, and the durability of the antifouling layer 24 is increased. If the average thickness of the nanosheet is 15 nm or less, it is easy to form a thin antifouling layer 24, for example, an antifouling layer 24 having an average thickness of 15 nm or less.

Area of the nanosheet is preferably 100 nm ² or more, more preferably 200 nm ² or more, more preferably 400 nm ² or more. If the area of the nanosheet is 100 nm ² or more, when the antifouling layer forming coating composition described later is applied to form the antifouling layer 24, the nanosheet is less likely to enter the silica-based porous film 21, and the silica-based The surface of the porous membrane is successfully coated with the nanosheet. The upper limit of the area of nanosheets is not particularly limited, dispersibility in an antifouling layer forming coating composition, in view of easy availability and the like, preferably 1000000Nm ² or less, 250000Nm ² or less being more preferred.

In view of these, examples of the nanosheet, preferably has an average mean area of thickness and 100～1000000Nm ² of 0.4～15Nm, mean average thickness and 200～1000000Nm ² of 0.4~10nm Those having an area are more preferable, and those having an average thickness of 0.4 to 10 nm and an average area of 200 to 250,000 nm ² are more preferable.

As a nanosheet, you may contain the nanosheet surface-modified with processing agents, such as surfactant. By containing the surface-modified nanosheet, the attached dirt can be easily peeled off, and sufficient antifouling property can be obtained with a small amount.
Surfactants include alkyl carboxylic acid salts such as sodium octoate, potassium octoate, sodium decanoate, potassium decanoate, sodium laurate, potassium laurate, sodium stearate, potassium stearate, sodium hexanesulfonate, hexane Alkyl sulfonates such as potassium sulfonate, sodium octane sulfonate, potassium octane sulfonate, sodium decane sulfonate, potassium decane sulfonate, sodium dodecane sulfonate, potassium dodecane sulfonate, sodium lauryl sulfate, potassium lauryl sulfate, myristyl sulfate Sulfate esters such as sodium and potassium myristyl sulfate, phosphate esters such as sodium lauryl phosphate and sodium tripolyphosphate, tetramethylammonium Mubromide, tetramethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, octyltrimethylammonium chloride, octyltrimethylammonium bromide, decyltrimethylammonium chloride, decyltrimethylammonium bromide, triethanolamine chloride, triethanolamine bromide, tripropanolamine Non-ionic such as quaternary alkyl ammonium such as chloride, tripropanolamine bromide, polyoxyethylene alkyl ammonium chloride, polyoxyethylene alkyl ammonium bromide, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, cetanol, oleyl alcohol, etc. Surface activity Agent, and the like.
Treatment agents other than surfactants include trimethylsilyl chloride, triethylsilyl chloride, t-butyldimethylsilane, tri-i-propylsilyl chloride, chloromethyltrimethylsilane, triethylsilane, butyldimethylsilane, trimethylvinylsilane, allyltrimethylsilane, Examples of the silylating agent include hexamethyldisilazane.
In addition, when peeling a nanosheet from an inorganic layered compound, this peeling may be performed in water containing a surfactant. The nanosheet dispersion liquid thus obtained contains nanosheets surface-modified with a surfactant.
The nanosheet contained in the antifouling layer 24 may be one type or two or more types.

binder:
The antifouling layer 24 may contain a binder in addition to the nanosheet. By including a binder, the adhesion between the plurality of nanosheets, the denseness of the antifouling layer 24, the removability of the antifouling layer 24 during outdoor exposure, and the like can be enhanced.
Although it does not specifically limit as a binder, The thing melt | dissolved in the dispersion medium used for the coating composition for antifouling layer formation (overcoat liquid) mentioned later is preferable. Since the dispersion medium of the coating composition for forming an antifouling layer often contains water, the binder itself or its precursor is preferably water-soluble, for example, a hydrolyzate of a hydrolyzable silane compound. (Silane hydrolysis sol), condensates thereof, water-soluble polymers and the like. A water-soluble polymer is more preferable as the binder. Since the water-soluble polymer is easily deteriorated by ultraviolet rays, wind and rain, etc. when exposed outdoors, it has an effect of improving the removal property of the antifouling layer 24.

The hydrolyzable silane compound is represented by, for example, SiX _m Y _4-m (m is an integer of 2 to 4, X is a hydrolyzable group, and Y is a non-hydrolyzable group). Compounds. The hydrolyzate of the hydrolyzable silane compound has a structure in which the Si—X group of SiX _m Y _4-m becomes Si—OH by hydrolysis, and Si—OH can be bonded to the nanosheet surface. The hydrolyzate can bind nanosheets by having two or more Si—OH. Moreover, hydrolyzate may condense and form a condensate.

m is preferably 3 or 4.
The hydrolyzable group of X is a group that can convert a Si—X group into a Si—OH group by hydrolysis. Examples of the hydrolyzable group include a halogen atom (for example, a chlorine atom), an alkoxy group, an acyloxy group, an aminoxy group, an amide group, a ketoximate group, a hydroxyl group, an epoxy group, a glycidyl group, and an isocyanate group, and an alkoxy group is particularly preferable. .
The non-hydrolyzable group of Y is a functional group whose structure does not change under conditions where the Si—X group becomes a Si—OH group by hydrolysis. The non-hydrolyzable group is not particularly limited, and may be a known group as a non-hydrolyzable group in a silane coupling agent or the like.

Specific examples of hydrolyzable silane compounds include tetraalkoxysilane (tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, etc.), alkoxysilane having an alkyl group (methyltrimethoxysilane, methyltriethoxysilane, Ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, etc.), alkoxysilanes having aryl groups (phenyltrimethoxysilane, phenyltriethoxysilane, etc.) , Alkoxysilane having a perfluoropolyether group (perfluoropolyether triethoxysilane, etc.), alkoxysilane having a perfluoroalkyl group (perfluoro Tiltriethoxysilane, etc.), alkoxysilanes having vinyl groups (vinyltrimethoxysilane, vinyltriethoxysilane, etc.), alkoxysilanes having epoxy groups (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.), alkoxysilanes having an acryloyloxy group (3-acryloyloxypropyltrimethoxysilane, etc.), etc. Is mentioned.
Among the above, when making the antifouling layer 24 hydrophilic, tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane are preferable. In the case of making the antifouling layer 24 water-repellent, an alkoxysilane having an alkyl group or an alkoxysilane having a perfluoroalkyl group is preferable.

Hydrolysis of the hydrolyzable silane compound is carried out by using an amount of water that can hydrolyze all hydrolyzable groups of the hydrolyzable silane compound (for example, in the case of tetraalkoxysilane, four times or more moles of water of tetraalkoxysilane) and catalyst. Perform using acid or alkali. Examples of the acid include inorganic acids (HNO ₃ , H ₂ SO ₄ , HCl, etc.) and organic acids (formic acid, oxalic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, etc.). Examples of the alkali include ammonia, sodium hydroxide, potassium hydroxide and the like. The catalyst is preferably an acid from the viewpoint of long-term storage. Moreover, as a catalyst, what does not disturb dispersion | distribution of a nanosheet is preferable.

Examples of the water-soluble polymer include polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, polyethylene imine, polydiallyl dimethyl ammonium chloride, sodium polyacrylate, polyacrylamide, polylactic acid, sodium polystyrene sulfonate, sodium polyvinyl sulfate, carboxy Vinyl polymer, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, guar gum, cationized guar gum, carrageenan, sodium alginate, corn starch, xanthan gum, sodium chondroitin sulfate, sodium hyaluronate, starch, modified starch, glue, gelatin, gum arabic, sodium alginate, pectin Etc.
The molecular weight of the water-soluble polymer is preferably 1000 to 100,000. When the molecular weight is less than 1000, the water-soluble polymer is likely to enter the inside of the silica-based porous film 21 and the transmittance is likely to be lowered. When the molecular weight is larger than 100,000, it becomes difficult to dissolve in a solvent, and nanosheets and aggregates are generated in the paint, which may reduce the stability of the paint.

Other ingredients:
The antifouling layer 24 may contain other components other than the nanosheet and the binder as needed, as long as the effects of the present invention are not impaired. Examples of the other components include surfactants that do not modify the surface of the nanosheet, silica fine particles, and titania fine particles. In the case of containing titania fine particles, it is expected that the attached dirt is decomposed by the photocatalytic effect.

Average film thickness of the antifouling layer 24:
The average film thickness of the antifouling layer 24 is 0.4 to 15 nm, preferably 1 to 10 nm. Sufficient antifouling property is acquired as the average film thickness of the antifouling layer 24 is 0.4 nm or more. When the thickness is 15 nm or less, the antifouling layer 24 has little influence on the antireflection performance of the silica-based porous film 21, and a decrease in the maximum transmittance due to the provision of the antifouling layer 24 can be suppressed.
The method for measuring the average film thickness of the antifouling layer 24 is as shown in the examples described later.
The antifouling layer 24 does not necessarily have to cover the entire surface of the silica-based porous film 21, but from the viewpoint of antifouling properties, the entire surface of the silica-based porous film 21 is covered. preferable.

Ratio of average film thickness of antifouling layer 24 and silica-based porous film 21:
The ratio of the average film thickness of the antifouling layer 24 and the silica-based porous film 21 (the average film thickness of the antifouling layer / the average total film thickness of the silica-based porous film) is in the range of 0.0013 to 0.5. Is more preferable, and 0.005-0.25 is more preferable.
If “the average film thickness of the antifouling layer / the average total film thickness of the silica-based porous film” is not less than the above lower limit value, sufficient antifouling performance can be ensured. On the other hand, if it is not more than the above upper limit value, sufficient antireflection performance can be ensured. That is, when the ratio of the average film thickness of the antifouling layer and the silica-based porous film is within the above range, the antifouling property and the antireflection performance can be sufficiently achieved.

By providing the antifouling layer 24 on the surface of the silica-based porous film 21, the antifouling property can be improved without reducing the antireflection performance.
Since the nanosheet is made of a low refractive material and the entire antifouling layer is thin, it is denser than the silica-based porous film, but hardly affects the antireflection performance of the entire antifouling antireflection film 20.
The antifouling layer 24 is formed by applying a coating composition for forming an antifouling layer in which a plurality of nanosheets are dispersed in a liquid medium to the surface of the silica-based porous film 21 and drying it. At that time, the plurality of nanosheets are deposited on the surface of the silica-based porous film 21. Therefore, the antifouling layer 24 formed by depositing a plurality of nanosheets is denser and has higher surface smoothness than the silica-based porous film 21, so that dirt does not easily enter. Therefore, it is difficult for dirt to adhere.
The silica-based porous membrane 21 of the present invention can sufficiently suppress the invasion of dirt such as EVA even if only the silica-based porous membrane 21 is set by setting fewer voids between the hollow fine particles 22 and open holes on the surface side. In the present invention, by further forming the antifouling layer 24, entry of dirt such as EVA can be further suppressed, and even if dirt adheres to the surface, a part of the nanosheet is peeled off together with the dirt, so that a trace of dirt is left. The effect that it is hard to remain is also acquired.

(Method for manufacturing article 1)
The article 1 is obtained by applying a silica-based porous film-forming coating composition containing a dispersion medium, hollow fine particles, and a silica-based matrix precursor onto a transparent substrate 10 and firing or drying the silica-based porous film. Forming a step (hereinafter referred to as “first step”);
A process for applying an antifouling layer-forming coating composition on the surface of the silica-based porous film and drying to form an antifouling layer (hereinafter referred to as “second process”). .

{First step}
The first step is to apply a silica-based porous film-forming coating composition containing a dispersion medium, hollow fine particles, and a silica-based matrix precursor onto the transparent substrate 10, and then calcinate or dry the silica-based porous film. This is a step of forming a film. As a result, a film in which hollow fine particles are dispersed in a matrix made of a calcined product (SiO ₂ ) of a hydrolyzate of alkoxysilane is formed.

Silica-based porous film-forming coating composition:
The coating composition for forming a silica-based porous film contains a dispersion medium, hollow fine particles 22 and a silica-based matrix precursor, and contains other fine particles and other additives as necessary.
The description of the hollow fine particles 22 and other fine particles is the same as described above.

Dispersion medium:
The dispersion medium is a liquid that disperses the hollow fine particles. The dispersion medium may be a solvent that dissolves the silica-based matrix precursor.
In the case where the silica-based matrix precursor is a hydrolyzate of alkoxysilane, water is required for hydrolysis, and therefore, the dispersion medium preferably contains at least water.
Water and other liquids may be used in combination. Examples of the other liquid include alcohols (methanol, ethanol, isopropanol, butanol, diacetone alcohol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ethers (tetrahydrofuran, 1,4-dioxane, etc.). ), Cellosolves (methyl cellosolve, ethyl cellosolve, etc.), esters (methyl acetate, ethyl acetate, etc.), glycol ethers (ethylene glycol monoalkyl ether, etc.), nitrogen-containing compounds (N, N-dimethylacetamide, N, N -Dimethylformamide, N-methylpyrrolidone, etc.), sulfur-containing compounds (dimethylsulfoxide, etc.) and the like.
Among the other liquids, as the solvent for the silica-based matrix precursor, alcohols are preferable, and methanol and ethanol are particularly preferable.

Silica-based matrix precursor:
As the silica-based matrix precursor, a hydrolyzate of alkoxysilane is preferable.
Examples of alkoxysilane include tetraalkoxysilane (tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, etc.), alkoxysilane having a perfluoropolyether group (perfluoropolyether triethoxysilane, etc.), perfluoroalkyl. Group-containing alkoxysilane (perfluoroethyltriethoxysilane, etc.), vinyl group-containing alkoxysilane (vinyltrimethoxysilane, vinyltriethoxysilane, etc.), epoxy group-containing alkoxysilane (2- (3,4-epoxycyclohexyl), etc. ) Ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.) Alkoxysilanes (3-acryloyloxy propyl trimethoxysilane and the like) or the like having a Riroiruokishi group.
Hydrolysis of the alkoxysilane can be carried out in the same manner as the hydrolysis of the hydrolyzable silane compound. As the catalyst used at the time of hydrolysis, a catalyst that does not hinder the dispersion of the hollow fine particles is preferable.

Mixing ratio of the hollow fine particles 22 and the silica-based matrix precursor:
The hollow fine particles 22 and the silica-based matrix precursor included in the silica-based porous film-forming coating composition are a mass ratio of the solid content of the hollow fine particles 22 and the silica-based matrix 23 in terms of SiO _{2 in} the silica-based porous film. It mix | blends so that (hollow microparticles / silica-type matrix ratio) may be set to 30 / 70-65 / 35. From the viewpoint of improving the antifouling property, the hollow fine particle / silica matrix ratio is preferably 50/50 to 60/40.
If the hollow fine particle / silica matrix ratio is equal to or higher than the lower limit value, the hollow fine particles 22 are likely to be densely packed in the silica porous film 21, so that the refractive index is lowered and the reflectance is kept sufficiently low. Can do. On the other hand, if it is less than or equal to the above upper limit value, the silica matrix 23 is sufficiently filled between the hollow fine particles 22, and voids are hardly formed between the hollow fine particles 22, so that the antifouling property is improved.

Other optional ingredients:
The silica-based porous film-forming coating composition may contain a terpene derivative, an additive, or the like, if necessary.
The terpene means a hydrocarbon having a composition of (C ₅ H ₈ ) _n (where n is an integer of 1 or more) having isoprene (C ₅ H ₈ ) as a structural unit. The terpene derivative means terpenes having a functional group derived from terpene. Terpene derivatives include those with different degrees of unsaturation. Although some terpene derivatives function as a dispersion medium, those having “a hydrocarbon having a composition of (C ₅ H ₈ ) _n having isoprene as a structural unit” fall under the category of terpene derivatives. Shall not apply.
The terpene derivative is preferably a terpene derivative having a hydroxyl group and / or a carbonyl group in the molecule from the viewpoint of the antireflection effect of the silica-based porous film 21, and the hydroxyl group, aldehyde group (—CHO), keto group ( -C (= O)-), an ester bond (-C (= O) O-), a terpene derivative having one or more selected from the group consisting of a carboxy group (-COOH) is more preferred, a hydroxyl group in the molecule, A terpene derivative having one or more selected from the group consisting of an aldehyde group and a keto group is more preferable.

Terpene derivatives include terpene alcohol (α-terpineol, terpinene 4-ol, L-menthol, (±) citronellol, myrtenol, nerol, borneol, farnesol, phytol, etc.), terpene aldehyde (citral, β-cyclocitral, perila). Aldehydes), terpene ketones ((±) camphor, β-ionone, etc.), terpene carboxylic acids (citronellic acid, abietic acid, etc.), terpene esters (terpinyl acetate, menthyl acetate, etc.) and the like. In particular, terpene alcohol is preferable.
A terpene derivative may be used individually by 1 type, and may use 2 or more types together.

Examples of other additives include a surfactant for improving leveling properties, a metal compound for improving durability of the silica-based porous membrane 21, and the like.
Examples of the surfactant include silicone oil and acrylic.
As the metal compound, a zirconium chelate compound, a titanium chelate compound, an aluminum chelate compound and the like are preferable. Examples of the zirconium chelate compound include zirconium tetraacetylacetonate and zirconium tributoxy systemate.

The viscosity of the silica-based porous film-forming coating composition is preferably 1.0 to 10.0 mPa · s, and more preferably 2.0 to 5.0 mPa · s. When the viscosity of the silica-based porous film-forming coating composition is 1.0 mPa · s or more, it is easy to control the film thickness of the silica-based porous film-forming coating composition applied on the transparent substrate 10. If the viscosity of the coating composition for forming a silica-based porous film is 10.0 mPa · s or less, drying or baking time and coating time are shortened.
The viscosity of the coating composition for forming a silica-based porous film is measured with a B-type viscometer.

1-9 mass% is preferable and, as for the solid content concentration of the coating composition for silica type porous membrane formation, 2-6 mass% is more preferable. If the solid content concentration is 1% by mass or more, the thickness of the coating film of the silica-based porous film-forming coating composition applied on the transparent substrate 10 can be reduced, and the finally obtained silica-based porous material It is easy to make the film 21 uniform. If solid content concentration is 9 mass% or less, it will be easy to make the film thickness of the coating film of the silica type porous film forming coating composition apply | coated on the transparent base material 10 uniform.
The solid content of the coating composition for forming a silica-based porous film refers to the hollow fine particles 22 and the silica-based matrix precursor (however, the solid content of the silica-based matrix precursor is the SiO ₂ equivalent amount of alkoxysilane). Mean total.

  The coating composition for forming a silica-based porous film is obtained by, for example, mixing a hollow fine particle dispersion, a silica-based matrix precursor solution, and an additional dispersion medium, a terpene derivative, and other additives as necessary. Prepared.

The silica-based porous film-forming coating composition described above includes a dispersion medium, hollow fine particles, and a silica-based matrix precursor, and therefore, a silica-based porous film having an antireflection effect can be obtained at low cost, and It can be formed even at relatively low temperatures.
Furthermore, when the silica-based porous film-forming coating composition contains a terpene derivative, voids are formed around the hollow fine particles 22 and the antireflection effect is increased. However, the content of the terpene derivative is controlled to such an extent that troubles due to the penetration of EVA or the like into the voids formed around the hollow fine particles 22 do not occur.

Application method:
As a method for applying the coating composition for forming a silica-based porous film, known wet coating methods (spin coating method, spray coating method, dip coating method, die coating method, curtain coating method, screen coating method, ink jet method, flow coating method) Method, gravure coating method, bar coating method, flexo coating method, slit coating method, roll coating method, etc.).
Among these, rolls can be used for a wide transparent substrate 10, the transport speed of the transparent substrate 10 can be made relatively fast, and the amount of the silica-based porous film forming coating composition required is relatively small. The coating method is preferable, and the antifouling antireflection film 20 having a uniform film thickness can be formed, and it is easy to form the antifouling antireflection film 20 having any film thickness that can be optically designed (excellent in film thickness controllability). From the viewpoint, the reverse roll coating method is more preferable.
The coating temperature (atmosphere) is preferably room temperature to 80 ° C, more preferably room temperature to 60 ° C.

Drying or baking:
Firing may be performed after the coating composition for forming a silica-based porous film is applied. The transparent substrate 10 is heated to a firing temperature in advance, and a silica-based porous film is formed on the surface of the transparent substrate 10. A coating composition for coating may be applied.
The firing temperature is preferably 30 ° C. or higher, and may be appropriately determined according to the material of the transparent substrate 10, the hollow fine particles 22, or the silica-based matrix precursor. In order to rapidly convert the hydrolyzate of alkoxysilane into a fired product, it may be fired at 80 ° C. or higher, preferably 100 ° C. or higher, and more preferably 200 to 700 ° C. When the firing temperature is 100 ° C. or higher, the fired product is densified and durability is improved.
When the transparent base material 10 is glass, it can also serve as the baking process at the time of forming the silica type porous membrane 21, and the physical strengthening process of glass. In the physical strengthening step, the glass is heated to near the softening temperature. In this case, the firing temperature is set to about 600 to 700 ° C. In general, the firing temperature is preferably equal to or lower than the thermal deformation temperature of the transparent substrate 10. The lower limit of the firing temperature is determined according to the formulation of the silica-based porous film-forming coating composition.
Since the polymerization proceeds to some extent even in natural drying, it is theoretically possible to set the drying or calcination temperature to a temperature setting near room temperature if there is no restriction on time.

In addition, the above 1st process can also be performed by another method.
For example, a method in which a low refractive index layer in which hollow fine particles are bonded with a first binder is first formed, and a second binder is filled in a space between the hollow fine particles of the low refractive index layer.
According to this method, since the gap between the hollow fine particles is filled with the second binder, the bond between the hollow fine particles is reinforced and the wear resistance is improved. Moreover, antifouling property can also be provided by including a fluorine-containing compound or a silicone compound in the second binder.

In addition, the process of forming the silica-based porous film 21 is the following two processes:
Applying a first coating composition containing hollow fine particles 22 and a dispersion medium and not containing a silica-based matrix on the transparent substrate 10 and drying to form a hollow fine particle layer;
A silica-based matrix and a second coating composition containing a solvent or a dispersion medium and not containing hollow fine particles 22 are applied to the hollow fine particle layer, impregnated in the hollow fine particle layer, and baked or dried to obtain silica. The method performed by the process of forming a system porous membrane is also mentioned.
According to this method, since the surface side of the silica-based porous film 21 is sufficiently covered with the silica-based matrix, the unevenness on the surface side of the silica-based porous film 21 is reduced, and wear resistance and antifouling properties are further improved. Can be made.

{Second step}
In the second step, the antifouling layer-forming coating composition containing a plurality of nanosheets and a dispersion medium of the nanosheets on the surface of the silica-based porous film 21 formed on the surface of the transparent substrate 10 in the first step. An object (hereinafter also referred to as “overcoat liquid”) is applied and dried to form the antifouling layer 24. Thereby, the article 1 is obtained.
The overcoat liquid contains a plurality of nanosheets and a dispersion medium for the nanosheets.

Nanosheet:
The description of the nanosheet is the same as described above.
As the nanosheet, a layered product of a layered compound such as a commercially available layered polysilicate or layered clay mineral may be used, or one manufactured by a known manufacturing method may be used.
The nanosheet can be obtained, for example, by peeling off a layer constituting the natural or synthetic inorganic layered compound by a conventional method. For example, a nanosheet dispersion liquid in which nanosheets are dispersed in water can be obtained by adding an inorganic layered compound to water to swell and stirring. Moreover, as an inorganic layered compound, in order to improve the dispersibility to a solvent, you may use what processed the surface and the interlayer previously with surfactant etc.
The nanosheet dispersion liquid can be used as it is as an overcoat liquid or for the preparation of an overcoat liquid. For example, an overcoat liquid can be prepared by mixing a nanosheet dispersion and a solution of an optional component (such as a binder or a precursor thereof). Moreover, you may collect | recover nanosheets from a nanosheet dispersion liquid, and use it for preparation of an overcoat liquid.

  In the overcoat liquid, the content of the nanosheet is not particularly limited as long as the overcoat liquid can be applied, but is 0.05 to 0.50 mass% with respect to the total amount of the overcoat liquid (100 mass%). Is preferable, and 0.10 to 0.35 mass% is more preferable. If the content of the nanosheet is 0.05% by mass or more, an arbitrary component dissolved in the overcoat liquid is less likely to penetrate into the silica-based porous film 21 when the overcoat liquid is applied. If the content of the nanosheet is 0.50% by mass or less, the coating property of the overcoat liquid is good, the thin antifouling layer 24 can be formed, and the uniformity of the film thickness of the antifouling layer 24 formed is also good. It is.

Dispersion medium:
The dispersion medium is a liquid that disperses the nanosheet. When a binder is blended in the overcoat liquid, the dispersion medium is preferably a solvent that dissolves the binder. The dispersion medium may be a single liquid or a mixed liquid obtained by mixing two or more liquids.
As the dispersion medium, water is preferably used. You may use water and an organic solvent together as needed. As the dispersion medium, an organic solvent may be used alone.
Examples of the organic solvent include alcohols (methanol, ethanol, isopropanol, butanol, diacetone alcohol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ethers (tetrahydrofuran, 1,4-dioxane, etc.), Cellosolves (methyl cellosolve, ethyl cellosolve, etc.), esters (methyl acetate, ethyl acetate, etc.), glycol ethers (ethylene glycol monoalkyl ether, etc.), nitrogen-containing compounds (N, N-dimethylacetamide, N, N-dimethyl) Formamide, N-methylpyrrolidone, etc.), sulfur-containing compounds (dimethyl sulfoxide, etc.) and the like. Among these, alcohols are preferable and methanol and ethanol are particularly preferable in terms of solvent drying property, water compatibility, and surface tension.
When the dispersion medium contains water, the content of water in the overcoat liquid is preferably 60% by mass or less, and more preferably 50% by mass or less with respect to the total mass of the overcoat liquid. When the content of water in the overcoat liquid is more than 60% by mass, the solvent is not sufficiently dried in the drying step after coating, and the appearance of the coating film is liable to occur.

Binder or its precursor:
When a layer containing a binder is formed as the antifouling layer 24, a binder or a precursor thereof is blended in the overcoat liquid. For example, when the binder is a condensate of a hydrolyzate of a hydrolyzable silane compound, a binder precursor is blended in the overcoat liquid. The binder precursor may be a hydrolyzate of a hydrolyzable silane compound or a hydrolyzable silane compound that is a precursor thereof.
The description of the binder and its precursor is the same as described above.

When the overcoat liquid contains a binder, the content is such that the mass ratio of the nanosheet content to the total amount of the nanosheet and the binder or its precursor (nanosheet / (nanosheet + binder)) is 0.25 or more. Is preferred. The value of nanosheet / (nanosheet + binder) is more preferably 0.375 or more, and particularly preferably 0.50 or more. When the nanosheet / (nanosheet + binder) is 0.25 or more, the decrease in the antireflection performance of the silica-based porous film 21 due to the penetration of the binder is suppressed, and the maximum transmittance by providing the antifouling layer 24 is reduced. The decrease can be sufficiently suppressed. 80-100 mass% is preferable with respect to the total mass of the solid content in an overcoat liquid, and, as for the total amount of a nanosheet and a binder or its precursor, 90-100 mass% is more preferable.
When the binder is a hydrolyzate of a hydrolyzable silane compound, the content of the binder or its precursor is in terms of SiO ₂ solids.

  When the binder or the precursor thereof is included, the overcoat liquid is prepared by, for example, mixing the nanosheet dispersion and a solution of the binder or the precursor thereof.

Other ingredients:
You may mix | blend other components other than a nanosheet, a binder, and its precursor with an overcoat liquid as needed.
As the other component, a surfactant is preferable.
The compounding amount of the surfactant is preferably such that the mass ratio of the surfactant content to the nanosheet content (surfactant / nanosheet) is 1.5 or less. When the surfactant / nanosheet exceeds 1.5, the transmittance tends to decrease due to the penetration of the surfactant component into the porous silica membrane.

  The solid content concentration in the overcoat liquid is preferably 0.05 to 0.5% by mass, and more preferably 0.1 to 0.4% by mass. If the solid content concentration in the overcoat liquid is less than 0.05% by mass, the antifouling property tends to be insufficient. On the other hand, when it exceeds 0.5 mass%, the antifouling layer 24 becomes too thick and the transmittance tends to be insufficient.

Application method:
As a method for applying the overcoat liquid, known wet coat methods (spin coat method, spray coat method, dip coat method, die coat method, curtain coat method, screen coat method, ink jet method, flow coat method, gravure coat method, bar (Coating method, flexo coating method, slit coating method, roll coating method, sponge roll coating method, squeegee coating method, etc.) can be used.
The coating temperature (atmosphere) is preferably room temperature to 80 ° C, more preferably 35 to 60 ° C.

Dry:
After application, the antifouling layer 24 is formed by drying or the like.
When the overcoat liquid contains only the nanosheet as a solid content, that is, when it does not contain any optional component other than the nanosheet (binder or precursor thereof, surfactant, etc.), drying after coating only needs to be able to remove the dispersion medium. The drying conditions are not particularly limited, but preferably satisfy the following drying conditions 1.
Drying condition 1: It is performed at a drying temperature of 300 ° C. or lower (more preferably 250 ° C. or lower, more preferably 200 ° C. or lower). If it is 300 degrees C or less, it can prevent that a nanosheet, a silica type porous membrane, and nanosheets sinter strongly, EVA peelability becomes favorable, and the removability of the pollution protection layer 24 at the time of outdoor exposure Is not sacrificed.
The lower limit of the drying temperature is not particularly limited, but the substrate temperature is preferably 60 ° C. or higher, and more preferably 80 ° C. or higher. If it is 60 degreeC or more, a dispersion medium will fully be removed.

When the overcoat liquid contains a binder or a precursor thereof, drying after coating is preferably performed at a temperature that satisfies the above-described drying condition 1 and does not exceed the thermal decomposition temperature of the binder. When heated to a temperature equal to or higher than the thermal decomposition temperature, the binder in the antifouling layer 24 is pyrolyzed and the effect of containing the binder (for example, improved adhesion between the nanosheets in the antifouling layer 24, the denseness of the antifouling layer 24) Property improvement) may be impaired.
The lower limit of the drying temperature is not particularly limited, but the substrate temperature is preferably 60 ° C. or higher and more preferably 80 ° C. If it is 60 degreeC or more, a dispersion medium will fully be removed.

When the overcoat liquid contains an organic substance other than the binder and its precursor, for example, a surfactant, etc., drying after coating is performed at a temperature that satisfies the above-mentioned drying condition 1 and does not exceed the thermal decomposition temperature of the organic substance. It is preferable to perform drying. When heated to a temperature equal to or higher than the thermal decomposition temperature, the organic substance may be thermally decomposed and the effects of inclusion may be impaired.
The lower limit of the drying temperature is not particularly limited, but the substrate temperature is preferably 60 ° C. or higher and more preferably 80 ° C. If it is 60 degreeC or more, a dispersion medium will fully be removed.
The thermal decomposition temperature of the organic substance can be measured by differential thermal-thermogravimetric simultaneous measurement (TG-DTA).

(Operational effects of this embodiment)
In the present embodiment, the reflection of the silica-based porous film 21 is provided by including the transparent base material 10 and the antifouling antireflection film 20 having the predetermined silica-based porous film 21 and the antifouling layer 24 described above. It is possible to provide an article and a manufacturing method having high antifouling properties while maintaining the prevention performance.

<Other Embodiments of the Present Invention>
The transparent substrate may have a functional layer on the antifouling antireflection film side.
A schematic cross-sectional view when the present invention has a functional layer is shown in FIG.
The article 2 is the same as the article 1 except that the transparent substrate 30 has a substrate layer 31 and a functional layer 32.
The base material layer 31 can be the same as the transparent base material 10 of the article 1.
Examples of the functional layer 32 include an undercoat layer, an adhesion improving layer, and a protective layer.
Examples of the undercoat layer include those having a function as an alkali barrier layer or a wide band low refractive index layer. As the undercoat layer, a layer formed by applying an undercoat coating composition containing a hydrolyzate of alkoxysilane (silane hydrolysis sol) on the base material layer 31 is preferable. The undercoat layer may contain fine particles containing silica or the like as a component.
After the undercoat coating composition is applied to the base material layer 31, the undercoat layer may be baked in advance before applying the silica-based porous film-forming coating composition. A coating composition for forming a film may be applied. When this invention is provided with an undercoat layer, the temperature at the time of apply | coating the coating composition for silica type porous membrane formation has preferable room temperature-80 degreeC, and baking temperature has preferable 30-700 degreeC. The thickness of the undercoat layer is preferably 10 to 500 nm.

  While the present invention has been described with reference to the exemplary embodiments, the present invention is not limited to the above-described embodiments. Each configuration in the above embodiment, a combination thereof, and the like are examples, and the addition, omission, replacement, and other modifications of the configuration can be made without departing from the spirit of the present invention.

<Evaluation method>
(Average primary particle size of fine particles)
The fine particle dispersion was diluted to 0.1% by mass with ethanol, and then applied onto the collodion film and dried to prepare a sample.
The sample was observed using TEM (Hitachi Ltd., H-9000). 100 fine particles were randomly selected from the TEM image, the particle diameter of each fine particle was measured, and the average value was taken as the average primary particle diameter of the fine particles.

(Average film thickness of silica-based porous film)
At the stage where the silica-based porous film is formed on the transparent substrate before applying the silica-based porous film-forming coating composition, a black vinyl tape is attached to the silica-based porous film on the transparent substrate. Affixed to the opposite surface. Then, it measured about the light of wavelength 380nm -780nm using the spectrophotometer (The Otsuka Electronics company make, instantaneous multiphotometry system MCPD-3000). The incident angle of light was 5 °.
From the bottom reflectance R _min and the refractive index ns of the transparent substrate, the refractive index n of the silica-based porous film was calculated by the following formula (6).
R _min = (n−ns) ² / (n + ns) ² (6)
From the refractive index n of the silica-based porous film and the wavelength λ (nm) at the bottom reflectance _Rmin , the average film thickness d (nm) of the silica-based porous film was calculated by the following formula (7).
n × d = λ / 4 (7)

(Average film thickness of antifouling layer)
The average film thickness e (nm) of the antifouling layer was calculated as follows.
The reflectance is measured before and after application of the coating composition for forming the antifouling layer, and the refractive index and film thickness of each layer fitting the curve to the actual measurement value are calculated by simulation, and the refractive index and film thickness of the antifouling layer are calculated. Asked.

(Antireflection performance)
Using a spectrophotometer (manufactured by JASCO Corporation, V670), the light transmittance of an article or the like at a wavelength of 400 nm to 1100 nm was measured.
The transmittance difference Td (%) was calculated by the following formula (8), and the antireflection performance was evaluated.
Transmittance difference = transmittance of article−transmittance of only transparent substrate (8)

(Resin peel strength test)
A 0.8 mm thick ethylene-vinyl acetate copolymer resin (EVA) film was cut into a width of 5 mm and a length of 80 mm, and placed on the surface of the antifouling layer side of the article obtained in each example, at 160 ° C. for 30 minutes. The EVA film was adhered to the article by holding it in a drying oven. The article to which the EVA film is adhered is taken out of the drying furnace, and after the temperature of the transparent substrate is lowered to room temperature, the force necessary for peeling off the EVA film adhered to the antifouling layer using a spring balance (hereinafter referred to as “peeling”). Force ”(unit: g / 5 mm) was measured.
It shows that an EVA film is easy to peel, that is, it is excellent in antifouling property, so that peeling force is small.

(Resin peeling test, brightness difference / color difference test)
Except for changing the width of the EVA film to 25 mm, the EVA film was adhered to the article in the same procedure as the resin peel strength test.
After the EVA film was peeled off by hand, the EVA adhesion trace was evaluated by visual observation based on the following evaluation criteria.
5: Trace is not visible 4: Trace is hardly visible 3: Trace is slightly visible but acceptable 2: Trace is slightly conspicuous 1: Trace is clearly conspicuous Also, lightness difference / color difference meter (CR-200 manufactured by Konica Minolta) Was used to measure the lightness difference (ΔY) and color difference (ΔExy) before and after EVA attachment.

<Production example>
(Preparation of silica-based matrix solution)
While stirring 77.6 g of denatured ethanol (manufactured by Japan Alcohol Sales Co., Ltd., Solmix AP-11, a mixed solvent mainly composed of ethanol, the same applies hereinafter), 11.9 g of ion-exchanged water and 61% by mass of nitric acid were added thereto. A mixed solution with 0.1 g was added and stirred for 5 minutes. To this was added 10.4 g of tetraethoxysilane (TEOS) (solid content concentration of SiO ₂ : 29% by mass), and the mixture was stirred at room temperature for 30 minutes to obtain a silica system having a solid content concentration of SiO ₂ of 3.0% by mass. A matrix solution was prepared.
Incidentally, SiO ₂ in terms of solid concentration is a solid content concentration when all Si of tetraethoxysilane was converted to SiO _2.

(Hollow SiO ₂ fine particle dispersion)
As the hollow SiO ₂ fine particle dispersion, Suriria 4110 manufactured by JGC Catalysts & Chemicals was used. The terms of SiO ₂ solid content of 20.5 wt%, average primary particle diameter of 60 nm.

(Linear SiO ₂ fine particle dispersion)
As a chain-like SiO ₂ fine particle dispersion, Snowtex OUP manufactured by Nissan Chemical Industries, Ltd. was used. The terms of SiO ₂ solid content of 15.5 wt%, average primary particle diameter of: 10 to 20 nm, average agglomerated particle size is 40 to 100 nm.

(Preparation of silica-based porous film-forming coating compositions (A) to (D))
While stirring the solvent at the mass shown in Table 1, the matrix and fine particles were added to obtain silica-based porous membrane coating compositions (A) to (D). The solid content concentration in terms of SiO ₂ was set to 3.0% by mass.

(Adjustment of antifouling layer forming coating composition (E) (F))
The nanosheet ("Lucentite SWN" manufactured by Coop Chemical Co., Ltd.) was added while stirring the solvent at the mass shown in Table 2, and the mixture was further stirred for 24 hours to obtain an antifouling layer-forming coating composition (E) (F). .

(Example 1)
Template glass (Solite, low iron soda lime glass (white plate glass), size: 400 mm × 400 mm, thickness: 3.2 mm) was used as a transparent substrate.
The surface of the template glass was polished with an aqueous cerium oxide dispersion, and the cerium oxide was washed away with water, rinsed with ion-exchanged water, and dried.

{First step}
The template glass is preheated in a preheating furnace (ISUZU, VTR-115), and the glass surface temperature is kept at 30 ° C., and the reverse roll coater (Sanwa Seiki Co., Ltd.) is coated on the template glass. The silica-based porous film coating composition was applied by a roll.
The coating conditions were a substrate conveyance speed of 8.5 m / min, a gap between the coating roll and the conveyor belt: 2.9 mm, and an indentation thickness between the coating roll and the doctor roll: 0.6 mm.
As the coating roll, a rubber lining roll lined with rubber (ethylene propylene diene rubber) having a surface hardness (JIS-A) of 30 was used.
As the doctor roll, a metal roll having lattice-like grooves formed on the surface thereof was used.
Then, it was baked at 500 ° C. for 30 minutes in the atmosphere.

{Second step}
The baked article is kept warm so that the glass surface temperature is 45 ° C., and the antifouling layer-forming coating composition (E) is applied using a PU roller (manufactured by AC Chemical Co., Ltd.) and dried at room temperature. An article having an antifouling antireflection film formed on the material was obtained.
Table 3 shows the types of the coating composition for the silica-based porous film and the coating composition for forming the antifouling layer, and the film thicknesses of the silica-based porous film and the antifouling layer.
Moreover, the scanning electron microscope image of the cross section of the article obtained in Example 3 is shown in FIG.

(Examples 2-9 and Comparative Examples 1-4)
Example 1 except that the types of the coating composition for the silica-based porous film and the coating composition for forming the antifouling layer and the thicknesses of the silica-based porous film and the antifouling layer were changed as shown in Table 3. Thus, an article in which an antifouling antireflection film was formed on the transparent substrates of Examples 2 to 9 and Comparative Examples 1 to 4 was obtained.
Evaluation results of the light transmittance of the antifouling antireflection film, the resin peel strength test, the resin peel trace test, and the brightness difference / color difference test of the articles obtained in Examples 1 to 9 and Comparative Examples 1 to 4 Table 3 shows.

As shown in Table 3, it can be seen that the articles obtained in Examples 1 to 9 have a high transmittance difference of 2.4% or more and have sufficient antireflection properties. In addition, the articles obtained in Examples 1 to 9 have a resin peel strength of 780 g / 5 mm or less, a resin peel mark of 3 or more, a lightness difference (ΔY) of 0.2 or less, and a color difference (ΔExy). ) Was 0.002 or less. These results indicate that the articles obtained in Examples 1 to 9 have sufficiently high light transmittance and excellent antifouling properties. In particular, in Examples 1 to 4 using the silica-based porous forming coating composition having a hollow fine particle / silica-based matrix ratio of 50/50, all the resin peeling marks were 5.
On the other hand, the articles obtained in Comparative Examples 1 and 2 using the silica-based porous coating composition having a hollow fine particle / silica-based matrix ratio higher than 60/40 had sufficient transmittance difference and resin peel strength. However, the resin peeling marks were conspicuous, and a brightness difference and a color difference also occurred.
In addition, the article obtained in Comparative Example 3 using chain fine particles, ie, solid fine particles, had a sufficient difference in transmittance, but had high resin peel strength and marked resin peel marks. In addition, the brightness difference and the color difference were remarkably generated.
In addition, the article obtained in Comparative Example 4 that did not have an antifouling layer had high resin peel strength and noticeable resin peel marks. In addition, brightness differences and color differences also occurred.

  According to the scanning electron microscope image of FIG. 3, it can be seen that an antifouling layer is formed on the article obtained in Example 3. It is presumed that the antifouling property of this article is good due to the formation of the antifouling layer on the silica-based porous membrane.

  Articles of the present invention include transparent parts for vehicles (headlight covers, side mirrors, front transparent boards, side transparent boards, rear transparent boards, etc.), transparent parts for vehicles (instrument panel surfaces, etc.), meters, architectural windows, Show windows, displays (notebook computers, monitors, LCDs, PDPs, ELDs, CRTs, PDAs, etc.), LCD color filters, touch panel substrates, pickup lenses, optical lenses, eyeglass lenses, camera components, video components, CCD cover substrates , Optical fiber end face, projector parts, copying machine parts, transparent substrate for solar cell, mobile phone window, backlight unit parts (for example, light guide plate, cold cathode tube, etc.), backlight unit parts, liquid crystal brightness enhancement film (for example, prism, Transflective film, etc.), LCD brightness enhancement film , Organic EL light-emitting element parts, inorganic EL light-emitting element parts, phosphor light-emitting element parts, optical filters, end faces of optical parts, illumination lamps, covers for lighting fixtures, amplified laser light sources, antireflection films, polarizing films, agricultural films, etc. Useful as.

DESCRIPTION OF SYMBOLS 1, 2 Goods 10,30 Transparent base material 20 Antifouling anti-reflective film 21 Silica type porous film 22 Hollow fine particle 23 Silica type matrix 24 Antifouling layer 31 Base material layer 32 Functional layer

Claims (7)

A transparent base material, and an antifouling antireflection film provided on the transparent base material,
The antifouling antireflection film has a silica-based porous film and an antifouling layer in order from the transparent substrate side,
The silica-based porous membrane includes hollow fine particles and a silica-based matrix, and the mass ratio (hollow fine particle / silica-based matrix ratio) of the hollow fine particles and the silica-based matrix in terms of SiO ₂ solid content is 30/70 to 65. / 35,
The antifouling layer comprises a plurality of nanosheets made of a low refractive material having a refractive index of 1.4 to 1.65, and the average film thickness of the antifouling layer is 0.4 to 15 nm.   The article according to claim 1, wherein an average primary particle diameter of the hollow fine particles is 5 to 150 nm.   The ratio of the average film thickness of the antifouling layer and the silica-based porous film (average film thickness of the antifouling layer / average total film thickness of the silica-based porous film) is 0.0013 to 0.5. The article according to 1 or 2.   The article according to any one of claims 1 to 3, wherein the nanosheet is derived from an inorganic layered compound selected from layered polysilicates and clay minerals.   The article according to any one of claims 1 to 4, wherein the transparent substrate has an undercoat layer on the antifouling antireflection film side. A method for producing an article, comprising: a transparent base material; and an antifouling antireflection film provided on the transparent base material,
A silica-based porous film-forming coating composition containing a dispersion medium, hollow microparticles, and a silica-based matrix precursor is applied onto the transparent substrate, and calcined or dried, whereby the hollow microparticles and the silica-based matrix SiO _2. A step of forming a silica-based porous film having a mass ratio of converted solids (hollow fine particles / silica-based matrix ratio) of 30/70 to 65/35;
On the surface of the porous silica film, a coating composition for forming an antifouling layer containing a plurality of nanosheets made of a low refractive material having a refractive index of 1.4 to 1.65 and a dispersion medium for the nanosheets is applied. Drying and forming an antifouling layer having an average film thickness after drying of 0.4 to 15 nm;
A method for producing an article, comprising:   The method for producing an article according to claim 6, wherein the drying temperature in the step of forming the antifouling layer is 300 ° C or lower.