JP6347214B2 - Glass substrate and device using the same - Google Patents

Description

  The present invention relates to a glass substrate used for solar cells and displays.

  A liquid crystal display is used as a display device of an information terminal such as a personal computer, a mobile phone, or a television. In general, a liquid crystal display has a structure in which liquid crystal is sealed between a pair of substrates on which transparent electrodes are formed. As this substrate, a glass substrate formed of soda lime glass or non-alkali glass is used.

In the case of a thin film compound solar cell, the solar cell has a structure in which an electrode layer, a photoelectric conversion layer, a buffer layer, and the like are formed on a glass substrate serving as a base material. In the case of a single crystal or polycrystalline silicon solar cell, the silicon semiconductor is sandwiched between glass substrates via a resin or the like.
Also, these solar cells usually use a cover glass substrate to protect the elements that are the main part of the solar cell. For example, in a thin film compound solar cell, a resin such as ethylene vinyl acetate is applied on such an element, and a cover glass substrate is attached thereon.

  Basic characteristics required for glass substrates widely used for these applications include high flatness and no deterioration, deterioration, or distortion even when exposed to high temperatures. Further, the glass substrate is required not to be deteriorated, warped, peeled off or cracked even when used for a long period of time while being exposed to sunlight or moisture in the atmosphere.

  For example, Patent Document 1 discloses a glass substrate for a solar cell having a novel composition so as to be suitable for manufacturing a glass substrate by an overflow downdraw method in order to provide a glass substrate having excellent flatness.

  Further, Patent Document 2 includes a titanium oxide that can suppress degradation of components caused by diffusion of alkali metal atoms and the like into the device even when low-cost soda lime glass is used. A solar cell substrate having an insulator layer is disclosed.

Japanese Unexamined Patent Application Publication No. 2008-282363 Japanese Unexamined Patent Publication No. 6-163955

  In the glass substrate in which high functionality is required as described above, further improvement in whitening is required as a new problem.

  Whitening is a phenomenon in which an originally transparent glass substrate constituting a white cell is whitened when the solar cell and the display are used. Whitening of a glass substrate occurs when components such as impurities contained in the glass substrate are deposited on the surface of the glass substrate during use, and the glass surface is deteriorated to form fine irregularities, thereby causing light scattering. It is understood to be. Such whitening reduces the light transmittance of the glass substrate, resulting in problems such as a decrease in light conversion efficiency of the solar cell and a decrease in visibility of the display.

  Therefore, a glass substrate that suppresses whitening and has improved reliability is demanded. In particular, whitening of solar cell substrates and outdoor displays is accelerated in high-temperature and high-humidity environments, but whitening is not accelerated even in such high-temperature and high-humidity environments. There is a need for a highly reliable glass substrate.

The present invention has been made based on the above knowledge and examination results.
That is, an object of the present invention is to provide a glass substrate that is excellent in light resistance and moisture resistance, has suppressed whitening, and has improved reliability, and a solar cell and a display obtained using the glass substrate.

  As a result of intensive studies in view of the above problems, the present inventors hydrolyzed a specific metal alkoxide in an organic solvent in the presence of a metal salt on the surface as a glass substrate used for the forefront of various devices. -It discovered that the glass substrate which has the protective film formed from the composition obtained by condensing and adding a precipitation inhibitor further has high reliability which suppressed whitening.

The present invention is based on the above findings and has the following gist.
(1) A glass substrate having a glass substrate and a protective film formed on the surface of the glass substrate,
The protective film contains a metal alkoxide represented by the following formula (I) and / or (II) (including a partial condensate of a metal alkoxide) in the presence of a metal salt represented by the following formula (III). A glass substrate used for the forefront of a device, which is formed from a composition obtained by hydrolysis / condensation in a solvent and further adding a precipitation inhibitor.
M ¹ (OR ¹ ) _n (I)
(M ¹ is at least one selected from the group consisting of silicon, titanium, tantalum, zirconium, boron, aluminum, magnesium, tin and zinc. R ¹ represents an alkyl group having 1 to 5 carbon atoms. N is M. Represents the valence of ^1. )
R ² _l M ² (OR ³ ) _4-1 (II)
(M ² represents silicon. R ² is substituted with a hydrogen atom or at least one selected from the group consisting of a halogen atom, a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a phenyl group, and a cyclohexyl group. And a C1-C20 hydrocarbon group which may have a hetero atom or a halogen atom, a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a phenyl group or a cyclohexyl group. R ³ represents an alkyl group having 1 to 5 carbon atoms, and l represents an integer of 1 to 3.
M ³ (X) _m (III)
(M ³ represents a metal. X represents chlorine, nitric acid, sulfuric acid, acetic acid, succinic acid, sulfamic acid, sulfonic acid, acetoacetic acid, acetylacetonate, or a basic salt thereof. M represents the valence of M ^3. .)

(2) R ² in the formula (II) is substituted with a hydrogen atom or at least one selected from the group consisting of a halogen atom, a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a phenyl group, and a cyclohexyl group. The glass substrate as described in said (1) which is a C1-C20 hydrocarbon group which may be made and may have a hetero atom.
(3) The glass substrate according to (1) or (2), wherein the metal alkoxide contains silicon alkoxide or is all silicon alkoxide.
(4) The glass substrate according to (1) or (2), wherein the metal alkoxide contains titanium alkoxide.
(5) The glass substrate according to (1), (2) or (4), wherein the metal alkoxide is a mixture of silicon alkoxide and titanium alkoxide.
(6) The glass substrate according to (1), wherein the metal alkoxides are all titanium alkoxides.

  (7) The above precipitation inhibitor is at least one selected from the group consisting of N-methyl-pyrrolidone, ethylene glycol, dimethylformamide, dimethylacetamide, diethylene glycol, propylene glycol, hexylene glycol and derivatives thereof ( The glass substrate according to any one of 1) to (6).

(8) The above (1) to (1), wherein the molar ratio of the total metal atoms (M ¹ + M ² ) of the metal alkoxide and the metal atoms (M ³ ) of the metal salt contained in the composition satisfies the following formula: The glass substrate according to any one of 7).
0.01 ≦ M ³ / (M ¹ + M ² ) ≦ 0.7

(9) The metal salt includes metal nitrate, metal sulfate, metal acetate, metal chloride, metal oxalate, metal sulfamate, metal sulfonate, metal acetoacetate, metal acetylacetonate and their basicity. The glass substrate according to any one of (1) to (8), which is at least one selected from the group consisting of salts.
(10) In the above (1) to (9), M ^{3 in the} formula (III) is at least one selected from the group consisting of aluminum, indium, zinc, zirconium, bismuth, lanthanum, tantalum, yttrium and cerium. The glass substrate in any one.

(11) The glass substrate according to any one of (4) to (6), wherein the organic solvent contains an alkylene glycol or a monoether derivative thereof.
(12) A glass substrate for a solar cell using the glass substrate according to any one of (1) to (11).
(13) A glass substrate for display using the glass substrate according to any one of (1) to (11).
(14) A solar cell using the glass substrate according to (12).
(15) A display using the glass substrate according to (13).

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the glass substrate which suppressed whitening and improved reliability and can provide a highly reliable solar cell and display by using this glass substrate.

It is typical sectional drawing which shows the 1st example of the board | substrate for solar cells of this invention. It is typical sectional drawing which shows the 2nd example of the board | substrate for solar cells of this invention.

As a glass substrate for a solar cell, a glass substrate with improved reliability and reduced whitening is required. In the present invention, a light-transmitting glass substrate is used for the configuration of the solar cell substrate, and an insulating protective film is disposed on the surface of the glass substrate.
That is, the glass substrate of the present invention has an insulating protective film for suppressing whitening on the surface of the glass substrate.

  The protective film covering the surface of the glass substrate of the present invention is formed using a composition obtained by hydrolyzing and condensing a metal alkoxide in an organic solvent in the presence of a metal salt and further adding a precipitation inhibitor. It is a cured film and an insulating film having a dense structure with a low porosity. By having a protective film having such a dense film structure on the surface of the glass substrate, the glass substrate of the present invention can suppress whitening even when used in solar cells. In particular, even if the glass substrate of the present invention is exposed to a high-temperature and high-humidity environment, acceleration of whitening can be suppressed.

<Protective film>
Below, each component which comprises the composition used in order to form the protective film of this invention is demonstrated.
The protective film of the present invention is formed as a cured film by applying the above composition to the surface of a substrate such as glass and baking it.
In addition, the composition for forming the protective film which covers the surface of the glass substrate of this invention may be called the composition of this invention, or a composition (it is also called coating composition).

(Metal alkoxide of formula (I))
The metal alkoxide that can be used for forming the composition is represented by the following formula (I). Here, the metal alkoxide includes a partial condensate of the metal alkoxide.
M ¹ (OR ¹ ) _n (I)
(M ¹ represents a metal, R ¹ represents an alkyl group having 1 to 5 carbon atoms, and n represents a valence of M _1. )

M ¹ is at least one selected from the group consisting of silicon, titanium, tantalum, zirconium, boron, aluminum, magnesium, tin, and zinc.
1 to 3 carbon atoms in the alkyl group R ¹ is preferred. The n alkyl groups may be a kind of alkyl group or a different alkyl group, but from the viewpoint of easy availability, a kind of alkyl group is preferable. n is preferably an integer of 4 to 8.

As the metal alkoxide, silicon alkoxide, titanium alkoxide and the like are preferable, and silicon alkoxide is particularly preferable.
For the formation of the composition, it is preferable to use a metal alkoxide containing a titanium alkoxide.

All of the metal alkoxides used in the composition can be silicon alkoxides.
In addition, all of the metal alkoxides used in the composition can be titanium alkoxides.

  Furthermore, the metal alkoxide used in the composition preferably includes a mixture of silicon alkoxide and titanium alkoxide.

  As the silicon alkoxide, one or a mixture of two or more compounds represented by the following formula (IV) (the partial condensate is preferably a pentamer or less) can be used. Furthermore, all the metal alkoxides can be one or a mixture of two or more compounds represented by the following formula (IV) (partial condensates are preferably pentamers or less).

Si (OR ') ₄ (IV)
(R ′ represents an alkyl group having 1 to 5 carbon atoms.)
R ′ has the same meaning as R ¹ in formula (I), and R ′ may be the same or different. From the viewpoint of synthesis, R ′ is preferably the same from the viewpoint of availability.

  Moreover, the 1 type, or 2 or more types of mixture of the compound shown by following formula (V) can be used as a titanium alkoxide. Furthermore, all the metal alkoxides can be titanium alkoxides which are one or a mixture of two or more compounds represented by the following formula (IV).

Further, the metal alkoxide is one or a mixture of two or more of the compounds represented by the above formula (IV) (partial condensate is preferably a pentamer or less) and 1 of the compounds represented by the following formula (V). It is also possible to use a mixture with a titanium alkoxide which is a seed or a mixture of two or more.
Ti (OR ″) ₄ (V)
(R ″ represents an alkyl group having 1 to 5 carbon atoms.)
R ″ has the same meaning as R ¹ in formula (I), and R ″ may be the same or different. From the viewpoint of synthesis, R ″ is preferably the same from the viewpoint of availability.

(Metal alkoxide of formula (II))
Another metal alkoxide that can be used for forming the composition includes a compound represented by the following formula (II).
R ² _l M ² (OR ³ ) _4-1 (II)
(M ² represents silicon. R ² is selected from the group consisting of a hydrogen atom or a halogen atom (preferably a fluorine atom), a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a phenyl group, and a cyclohexyl group. A hydrocarbon group having 1 to 20 carbon atoms which may be substituted with at least one kind and which may have a hetero atom, or a halogen atom, vinyl group, methacryloxy group, acryloxy group, styryl group, phenyl group Or a cyclohexyl group, R ³ represents an alkyl group having 1 to 5 carbon atoms, and l represents an integer of 1 to 3).
Here, the metal alkoxide includes a partial condensate of the metal alkoxide.

l represents an integer of 1 to 3. The number of carbon atoms of R ^2, 1 to 20 are preferred.
Further, the hydrocarbon may be branched or linear, but is preferably linear.
Further, the plurality of hydrocarbon groups may be one type of hydrocarbon group or different types of hydrocarbon groups, but from the viewpoint of synthesis, one type of hydrocarbon group is preferable. R ³ preferably has 1 to 5 carbon atoms.
Further, the plurality of alkyl groups may be one type of alkyl group or different types of alkyl groups, but one type of alkyl group is preferable from the viewpoint of easy availability in the synthesis. .

  Although the specific example of the alkoxysilane represented by a formula (II) is given, it is not limited to these. For example, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxy Silane, acryloxyethyltrimethoxysilane, acryloxyethyltriethoxysilane, styrylethyltrimethoxysilane, styrylethyltriethoxysilane, 3- (N-styrylmethyl-2-aminoethylamino) propyltrimethoxysilane, p-styryl Trimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, trifluoropropyltrimethoxysilane, chloropropyltriethoxysilane, bromopropyltri Tokishishiran, dimethyl diethoxy silane, dimethyl dimethoxy silane, diethyl diethoxy silane, diethyl dimethoxy silane, diphenyl dimethoxy silane, diphenyl diethoxy silane trimethyl silane, trimethyl methoxy silane, and the like.

As the metal alkoxide (II) having a hydrocarbon group having a hetero atom, metal alkoxides having the following functional groups can be used as long as the effects of the present invention are not impaired. Examples of functional groups include amino groups, glycidoxy groups, mercapto groups, isocyanate groups, and ureido groups.
Examples of the metal alkoxide (II) having the functional group include 3- (2-aminoethylaminopropyl) trimethoxysilane, 3- (2-aminoethylaminopropyl) triethoxysilane, 2-aminoethylaminomethyltrimethyl. Methoxysilane, 2- (2-aminoethylthioethyl) triethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxy Silane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-mercaptopro Examples include pyrtrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyldimethylethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, and γ-ureidopropyltripropoxysilane.

  The content of the metal alkoxide (II) having a hydrophilic group such as the functional group is preferably 30 mol% or less, more preferably 25 mol% or less, based on the total amount of the metal alkoxide used (100 mol%).

(Metal salt of formula (III))
Next, as the metal salt used in the composition, one or more of the compounds represented by the following formula (III) can be used.

As the metal salt, a metal salt represented by the formula (III) is used.
M ³ (X) _m (III)
(M ³ represents a metal, and X represents chlorine, nitric acid, sulfuric acid, acetic acid, succinic acid, sulfamic acid, sulfonic acid, acetoacetic acid, acetylacetonate, or a basic salt thereof. M represents the valence of M ^3. .)

  Of the compounds represented by the formula (III), metal nitrates, metal chloride salts, metal oxalates and basic salts thereof are particularly preferable.

Examples of M ³ include aluminum, indium, zinc, zirconium, bismuth, lanthanum, tantalum, yttrium, and cerium. Among these, aluminum, indium, or cerium is preferable from the viewpoint of availability and storage stability of the prepared composition, and aluminum is particularly preferable.

(Organic solvent)
Examples of the organic solvent used in the present invention include alcohols such as methanol, ethanol, propanol and butanol, esters such as ethyl acetate, glycols such as ethylene glycol and ether derivatives thereof, ester derivatives and ethers such as diethyl ether. , Ketones such as acetone, methyl ethyl ketone and cyclohexanone, and aromatic hydrocarbons such as benzene and toluene. These can be used alone or in combination.

  From the viewpoint of stabilizing the metal alkoxide component comprising a metal such as titanium, tantalum, zirconium, boron, aluminum, magnesium, tin, zinc, etc. to improve the storage stability of the coating composition liquid, alkylene glycols or monoethers thereof It is desirable to include derivatives. Examples of such alkylene glycols or monoether derivatives thereof include ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol, and their monomethyl-, monoethyl-, monopropyl-, monobutyl- or monophenyl ethers. .

These alkylene glycols or monoether derivatives thereof have a molar ratio of less than 1 with respect to a metal alkoxide composed of a metal such as titanium, tantalum, zirconium, boron, aluminum, magnesium, tin, and zinc. The stability is less effective, and the storage stability of the coating composition is deteriorated. On the other hand, it is not a problem to use a large amount of alkylene glycols or monoether derivatives thereof. For example, all the organic solvents used in the coating composition may be the above-described alkylene glycols or monoether derivatives thereof.
As for the usage-amount of alkylene glycol or its monoether derivative, 1 or more are preferable by molar ratio with respect to a metal alkoxide.

  When titanium alkoxide is contained as a metal alkoxide component in the composition, examples of alkylene glycols or monoether derivatives thereof contained in the organic solvent include ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol, and monomethyl thereof. , Monoethyl, monopropyl, monobutyl or monophenyl ether.

When the molar ratio of the alkylene glycol or the monoether derivative thereof contained in the organic solvent is less than 1 with respect to the titanium alkoxide, the effect of improving the stability of the titanium alkoxide is small, and the storage stability of the composition is deteriorated. . On the other hand, it is not a problem to use a large amount of alkylene glycols or monoether derivatives thereof. For example, all of the organic solvent may be the above-described alkylene glycol or a monoether derivative thereof.
However, when the composition does not contain titanium alkoxide, it is not particularly necessary to contain the above-described alkylene glycol and / or monoether derivative thereof in the organic solvent.

(Precipitating agent)
The precipitation inhibitor contained in the composition of the present invention has the effect of preventing the metal salt from depositing in the coating film when the coating film of the composition is formed on the glass substrate and the protective film is formed. Have.
Examples of the precipitation inhibitor include N-methyl-pyrrolidone, dimethylformamide, dimethylacetamide, ethylene glycol, diethylene glycol, propylene glycol, hexylene glycol, and derivatives thereof. These may be used alone or in combination. can do. Of these, hexylene glycol and the like having good coating properties are preferred.

  The precipitation inhibitor is used in a ratio of (precipitation inhibitor) / (metal oxide) ≧ 1 (weight ratio) by converting the metal of the metal salt into a metal oxide. When this ratio (weight ratio) is less than 1, the effect of preventing precipitation of the metal salt at the time of forming the coating film is reduced. On the other hand, the use of a large amount of a precipitation inhibitor has no effect on the composition. The use ratio is preferably 1 or more by weight.

  The precipitation inhibitor may be added when a metal alkoxide, particularly silicon alkoxide, titanium alkoxide, or silicon alkoxide and titanium alkoxide undergo hydrolysis / condensation reaction in the presence of a metal salt. -It may be added after completion of the condensation reaction.

(Composition)
Content of each said main component contained in a composition is metal alkoxide (I) and / or metal alkoxide (II) 2.5 to 40 weight%, Preferably it is 2.5 to 19 weight%. The metal salt (II) is 0.5 to 45% by weight, preferably 0.5 to 35% by weight, and the organic solvent is 35 to 95% by weight, preferably 45 to 92.5% by weight. It is.

The content ratio of the metal alkoxide and the metal salt in the composition of the present invention is the molar ratio between the total metal atoms (M ¹ + M ² ) of the metal alkoxide contained in the composition and the metal atoms (M ³ ) of the metal salt. It is preferable that the ratio satisfies the relationship of 0.01 ≦ M ³ / (M ¹ + M ² ) ≦ 0.7. If this molar ratio is less than 0.01, the mechanical strength of the resulting protective film is not sufficient, which is not preferable. On the other hand, when the molar ratio exceeds 0.7, the adhesion of the protective film to the glass substrate is lowered.
Furthermore, when a coating film of a composition exceeding the above content ratio is baked at a low temperature of 450 ° C. or lower to form a protective film on a glass substrate, the chemical resistance of the protective film obtained may be reduced. It is not preferable.
The content ratio of the metal alkoxide and the metal salt is preferably 95/5 to 50/50.
The composition of the present invention is used as a coating composition for coating on a glass substrate or the like after containing other components shown below.

In the present invention, other components such as inorganic fine particles, metalloxane oligomers, metalloxane polymers, leveling agents, surfactants and the like are contained in the composition as long as the effects of the present invention are not impaired. May be.
As the inorganic fine particles, fine particles such as silica fine particles, alumina fine particles, titania fine particles, and magnesium fluoride fine particles are preferable, and those in a colloidal solution state are particularly preferable. This colloidal solution may be a dispersion of inorganic fine particles in a dispersion medium, or a commercially available colloidal solution. In the present invention, by containing inorganic fine particles, it is possible to adjust the surface shape and refractive index of the formed cured film and to provide other functions.
The inorganic fine particles preferably have an average particle size of 0.001 to 0.2 μm, more preferably 0.001 to 0.1 μm. When the average particle diameter of the inorganic fine particles exceeds 0.2 μm, the transparency of the cured film formed using the prepared coating liquid may be lowered.

Examples of the dispersion medium for the inorganic fine particles include water and organic solvents. As a colloid solution, it is preferable that pH or pKa is adjusted to 1-10 from a viewpoint of stability of an electrode protective film formation agent. More preferably, it is 2-7.
Examples of the organic solvent used for the dispersion medium of the colloidal solution include alcohols such as methanol, propanol, butanol, ethylene glycol, propylene glycol, butanediol, pentanediol, hexylene glycol, diethylene glycol, dipropylene glycol, and ethylene glycol monopropyl ether; Ketones such as methyl ethyl ketone and methyl isobutyl ketone; aromatic hydrocarbons such as toluene and xylene; amides such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; esters such as ethyl acetate, butyl acetate and γ-butyrolactone; Examples include ethers such as tetrahydrofuran and 1,4-dioxane. Among these, alcohols and ketones are preferable. These organic solvents can be used alone or in admixture of two or more as a dispersion medium.

About solid content concentration in the composition of this invention, when converting the metal alkoxide and metal salt mentioned above as a metal oxide, it is preferable that it is the range of 0.5-20 weight% as solid content, and is 0.0. 5-12 weight% is more preferable. When the solid content concentration exceeds 20% by weight, the storage stability of the composition is deteriorated and it is difficult to control the thickness of the protective film to be formed. On the other hand, when the solid content concentration is 0.5% by weight or less, the thickness of the protective film to be obtained becomes thin, and it is necessary to form a coating film many times in order to obtain a predetermined film thickness. It becomes complicated.
The composition for forming a protective film covering the surface of the glass substrate of the present invention is obtained by hydrolyzing and condensing a specific metal alkoxide in an organic solvent in the presence of a metal salt, and further adding a precipitation inhibitor. It is done.

(Method for producing composition)
The composition of the present invention is obtained by hydrolyzing and condensing the above-described metal alkoxide in an organic solvent in the presence of the above-described metal salt. That is, the composition of the present invention is obtained using water.

  When the metal alkoxide is silicon alkoxide, titanium alkoxide, or a mixture of silicon alkoxide and titanium alkoxide, the amount of water used for hydrolysis thereof is silicon alkoxide, titanium alkoxide, or silicon alkoxide and titanium alkoxide. It is preferable to make it more than 2-24 in molar ratio conversion with respect to the total number of moles of this mixture, and 2-20 are more preferable. When the molar ratio ((amount of water (mole)) / (total number of moles of silicon alkoxide, etc.)) is 2 or less, hydrolysis of the above alkoxide becomes insufficient, resulting in reduced film formability. This is not preferable because the strength of the protective film obtained is lowered.

Even when other metal alkoxides are used, the same conditions as described above are preferable for the amount of water added.
Further, when the coexisting metal salt is a hydrate salt, the moisture content of the metal salt needs to be taken into consideration with respect to the amount of water used for the hydrolysis because the moisture content is involved in the reaction.

  When only the titanium alkoxide is used as the metal alkoxide for the composition of the present invention, the resulting composition has the property that the viscosity gradually increases during storage at room temperature. It is a slight increase in viscosity, and there is no concern that it will be a major problem in practical use. However, if it is necessary to precisely control the thickness of the protective film to be formed, carefully adjust the temperature at the time of storage of the composition. Management is required. Such an increase in the viscosity of the composition becomes more pronounced as the composition ratio of the titanium alkoxide contained increases. This is presumably because titanium alkoxide has a higher hydrolysis rate and faster condensation reaction than silicon alkoxide and the like.

  In the case of obtaining a composition using a metal alkoxide containing a titanium alkoxide, the following production methods (1) and (2) are effective for further reducing the viscosity increase.

  (1) When hydrolyzing titanium alkoxide in the presence of a metal salt, after sufficiently mixing alkylene glycol or its monoether derivative and titanium alkoxide in advance, if necessary, mixed with silicon alkoxide, Hydrolysis and condensation reaction in the presence.

  (2) A silicon alkoxide is preliminarily hydrolyzed in the presence of a metal salt, and then mixed with a titanium alkoxide solution mixed with an alkylene glycol or a monoether derivative thereof to perform a hydrolysis / condensation reaction to obtain a composition. .

  The production method (1) is effective because when titanium alkoxide is mixed with alkylene glycols or monoether derivatives thereof, heat is generated, so that there is a gap between the alkoxy group of titanium alkoxide and alkylene glycols or monoether derivatives thereof. This is thought to be because the transesterification occurs in order to stabilize the hydrolysis / condensation reaction.

  The reason why the production method (2) is effective is considered to be as follows. That is, the hydrolysis reaction of silicon alkoxide is performed at a high rate, but the subsequent condensation reaction is slower than titanium alkoxide. Therefore, when titanium alkoxide is added quickly after finishing the hydrolysis reaction, the silanol group of the hydrolyzed silicon alkoxide and the titanium alkoxide react uniformly. Thereby, it is thought that the hydrolyzed silicon alkoxide stabilizes the condensation reactivity of titanium alkoxide.

The method of mixing silicon alkoxide hydrolyzed in advance and titanium alkoxide is a known method. However, when alkylene glycols or monoether derivatives thereof are not contained in the organic solvent used in the reaction, the resulting composition may not exhibit excellent storage stability.
The method shown in (2) is also useful when obtaining the composition of the present invention from a metal alkoxide other than titanium alkoxide having a high hydrolysis rate and silicon alkoxide.

<Protective film>
The glass substrate of the present invention has a glass substrate and a protective film formed on the surface of the glass substrate. The protective film can be formed using the composition of the present invention described above.
That is, the protective film contains a metal oxide of a metal alkoxide represented by the above formula (I) and / or formula (II). Preferably, it contains silicon oxide. Moreover, it preferably contains a titanium oxide.
Further, the protective film contains a metal component in the metal salt represented by the above formula (III). For example, when aluminum nitrate or the like is used as a preferable metal salt, the protective film contains aluminum derived from aluminum nitrate. The protective film on the glass substrate having such a composition has a dense film structure.

The protective film can be formed on the surface of the glass substrate by using a composition of the present invention and applying a known coating method or the like.
First, the protective film is formed by coating the composition of the present invention on a glass substrate to form a coating film. As the coating method, for example, a dip coating method, a spin coating method, a spray coating method, a brush coating method, a roll transfer method, a screen printing method, an ink jet method, a flexographic printing method and the like can be used.

Then, after heating at the temperature of 50-100 degreeC and drying a coating film, 100 degreeC or more, Preferably it is 100-600 degreeC, More preferably, it is 300-500 degreeC for 0.5 to 2 hours, Preferably it is 0.00. Bake for 5 to 1 hour. In the formation of the protective film using the composition of the present invention, the firing temperature can be low-temperature firing at 100 to 500 ° C. Even with such low-temperature firing, the composition of the present invention can provide a protective film having a dense film structure.
These heat treatments can be performed using an apparatus such as an oven furnace or a hot plate.
In addition, the heating at a temperature of 50 to 100 ° C. for drying the coating film can be omitted.

  When the composition contains titanium alkoxide as the metal alkoxide, the coating film of the composition is irradiated with ultraviolet rays (UV) before being baked at 100 ° C. or higher after being dried by heating at a temperature of 50 to 100 ° C. It is also possible to irradiate. By irradiating UV, the protective film obtained can have a denser film structure.

  As described above, a dense cured film using the composition of the present invention is formed on the glass substrate, and using the cured film as a protective film, the glass substrate and the protective film formed on the surface of the glass substrate, A glass substrate of the present invention having the following is obtained. These glass substrates are used as solar cell substrates or display substrates.

<Substrates for solar cells>
FIG. 1 is a schematic cross-sectional view showing a first example of the solar cell substrate of the present invention.
The solar cell substrate 1 includes a glass substrate 2 and protective films 3 and 3 ′ disposed on both surfaces of the glass substrate 2. The protective films 3 and 3 ′ are protective films formed directly on the surface of the glass substrate 2 using the above-described composition. By having such a configuration, the solar cell substrate 1 of the first example of the present invention has excellent transparency and suppresses whitening.

  In addition, it is preferable that the protective film 3 and protective film 3 'arrange | positioned on the surface of the both sides of the glass substrate 2 have the same composition, and substantially the same thickness.

FIG. 2 is a schematic cross-sectional view showing a second example of the solar cell substrate of the present invention.
The solar cell substrate 11 includes a glass substrate 12 similar to the glass substrate 2 of the first example described above, and a protective film 13 disposed on one surface of the glass substrate 12. The protective film 13 is a protective film formed directly on the surface of the glass substrate 12 using the composition of the present invention described above. By having such a configuration, the solar cell substrate 11 of the second example of the present invention is excellent in transparency and whitening is suppressed.

  The shape of the glass substrates 2 and 12 used for the solar cell substrates 1 and 11 of the present invention is, for example, a plate shape.

Examples of the glass substrates 2 and 12 include soda lime glass, borate glass, aluminosilicate glass, quartz glass, and the like from the classification by composition. Moreover, from the classification based on the alkali component, non-alkali glass and low alkali glass can be mentioned. The content of alkali metal components (for example, Na ₂ O, K ₂ O, Li ₂ O, etc.) of the glass substrates 2 and 12 is preferably 15% by weight or less, more preferably 10% by weight or less.

  The plate | board thickness of the glass substrates 2 and 12 is 0.1-3.0 mm, 0.1-2.0 mm is preferable, 0.1-1.5 mm is more preferable, 0.1-0.7 mm is still more preferable 0.1 to 0.5 mm is particularly preferable. As the plate thickness of the glass substrates 2 and 12 decreases, the glass substrates 2 and 12 can be reduced in weight, and the solar cell can be reduced in weight.

The glass substrates 2 and 12 can be formed according to a known method. For example, the glass substrates 2 and 12 are melted at a temperature of 1400 to 1600 ° C. at a temperature of 1400 to 1600 ° C., a mixture containing a main raw material such as silica and alumina, an antifoaming agent such as mirabilite and antimony oxide, and a reducing agent such as carbon. After forming into a thin plate shape, it is produced by cooling.
Examples of the thin plate forming method for the glass substrates 2 and 12 include a slot down draw method, a fusion method, and a float method. The glass substrates 2 and 12 formed into a plate shape by these methods may be chemically polished with a solvent such as hydrofluoric acid, if necessary, in order to reduce the thickness or improve the smoothness.

As the glass substrates 2 and 12, commercially available ones may be used as they are, or a commercially available glass substrate may be polished to have a desired thickness.
Examples of commercially available glass substrates include “7059”, “1737”, “EAGLE 2000” manufactured by Corning, “AN100” manufactured by Asahi Glass, “NA-35” manufactured by NH Techno Glass, and “OA-” manufactured by Nippon Electric Glass. 10 "and the like.

  The thickness of the protective layers 3, 3 'and 13 of the solar cell substrates 1 and 11 of the present invention is preferably 10 to 1000 nm, and more preferably 80 to 120 nm. The solar cell substrate 11 has the protective films 3, 3 ′, and 13 having such a thickness on the glass substrates 2 and 12, thereby suppressing whitening.

  Moreover, the transmittance | permeability in wavelength 550nm of the board | substrates 1 and 11 for solar cells of this invention becomes like this. Preferably it is 85% or more, More preferably, it is 90% or more. By having such a transmittance | permeability, the board | substrates 1 and 11 for solar cells of this invention can comprise the solar cell of the outstanding light conversion efficiency.

  The solar cell substrates 1 and 11 of the present invention having the above-described structure are applied to solar cells having various structures configured using a glass substrate, and the glass substrate is substituted to provide the solar cell of the present invention. can do.

For example, the solar cell substrates 1 and 11 of the present invention have the same structure as the solar cell disclosed in Patent Document 2 and the photovoltaic element disclosed in Japanese Unexamined Patent Publication No. 2012-134544. It can be used for the construction of solar cells.
Furthermore, the solar cell substrates 1 and 11 of the present invention are not limited to the solar cells disclosed in Patent Document 2 and Japanese Patent Application Laid-Open No. 2012-134544, but are solar cells configured using a glass substrate. It can be used as a glass substrate, and a highly reliable solar cell can be provided.

  Hereinafter, the present invention will be described in detail, but the present invention is not construed as being limited to these examples.

[Abbreviation of compound]
Abbreviations of the compounds used below are as follows.
TEOS: Tetraethoxysilane AN: Aluminum nitrate hexahydrate MPMS: Methacryloxypropyltrimethoxysilane TIPT: Tetraisopropoxytitanium MeOH: Methanol PGME: Propylene glycol monomethyl ether HG: Hexylene glycol EG: Ethylene glycol BCS: Ethylene glycol Monobutyl ether

[Measurement method of residual alkoxysilane monomer]
Residual alkoxysilane monomer remaining in the reaction solution formed in Examples and the like was measured by gas chromatography (hereinafter referred to as GC).
The GC measurement was performed under the following conditions using Shimadzu GC-14B manufactured by Shimadzu Corporation.
Column: Capillary column CBP1-W25-100 (length 25 mm, diameter 0.53 mm, wall thickness 1 μm)
Column temperature: The temperature was raised from a starting temperature of 50 ° C. at 15 ° C./minute to reach an ultimate temperature of 290 ° C. (holding time: 3 minutes).
Sample injection volume: 1 μL, injection temperature: 240 ° C., detector temperature: 290 ° C., carrier gas: nitrogen (flow rate 30 mL / min), detection method: FID method.

<Example 1>
To a four-necked reaction flask equipped with a reflux tube, MeOH (49.17 g) as a solvent (C1) and TEOS (11.25 g) as an alkoxysilane (A1) were added and stirred. Next, a mixture of MeOH (16.39 g) as the solvent (C2), aluminum nitrate hexahydrate (20.27 g) as the aluminum salt (B1), and water (2.92 g) was added dropwise and stirred for 30 minutes. After stirring, the mixture was refluxed for 3 hours and allowed to cool to room temperature to prepare a solution. When this solution was measured by GC according to the measurement method described above, no alkoxysilane monomer was detected.

This solution (50 g) was mixed with HG (10 g), BCS (10 g), and PGME (30 g) to obtain a coating composition. Table 1 summarizes each component of the alkoxysilane (A1), aluminum salt (B1), water, and solvent (C1 and C2) used for the preparation of the coating composition together with the amount of addition.
In addition, "-" description in the component column in Table 1 indicates that the component was not used.

<Examples 2 to 5>
In the same manner as in Example 1, coating compositions of Examples 2 to 5 having the compositions shown in Table 1 were obtained.

<Example 6>
<A1 liquid>
In the flask, 12.7 g of AN and 3.0 g of water were added and stirred to dissolve AN. EG13.1g, HG37.5g, BCS35.7g, and MPMS37.0g were put there and it stirred under room temperature for 30 minutes.
<A2 liquid>
4.7 g of TIPT and 56.3 g of HG were put in the flask, and stirred at room temperature for 30 minutes.
<A1 liquid> and <A2 liquid> were mixed and stirred at room temperature for 30 minutes to prepare a solution to obtain a coating composition.

<Comparative Example 1>
A coating composition of a comparative example having the composition shown in Table 1 was obtained in the same manner as in Example 1 except that HNO ₃ was used as an acid without using an aluminum salt as in Examples 1 to 5, and HNO ₃ was used as the acid. It was.

<Example 7>
Using the coating compositions of Examples 1 to 5 and Comparative Example 1, a coating film was formed on the substrate, heat-cured, and a protective film was formed on the substrate. In addition, about each formed protective film, what was obtained using the coating composition of Example 1 is called the protective film of Example 1 for convenience. Similarly, protective films obtained using the coating compositions of Examples 2 to 5 and Comparative Example 1 are referred to as protective films of Examples 2 to 5 and Comparative Example 1 for convenience.
The methods for forming protective films of Examples 1 to 5 and Comparative Example 1, and the evaluation methods and results of the substrates on which the protective films were formed are shown below.

[Protective film forming method]
Using a dip coater, each of the coating compositions of Examples 1 to 5 and Comparative Example 1 was applied to both surfaces of 0.7 mm thick soda lime glass to form a coating film, respectively. Then, after drying at 80 ° C. for 3 minutes in a clean oven, heating was performed at 300 ° C. for 30 minutes in the clean oven to cure each coating film. On each substrate, Examples 1 to 5 having a thickness of 100 nm And the protective film of the comparative example 1 was formed.

[Film evaluation: HAZE value after high temperature and high humidity test]
Using each of the substrates on which the protective films of Examples 1 to 5 and Comparative Example 1 were formed, the HAZE value (haze value) was measured.
As Comparative Example 2, a HAZE measurement was performed using a substrate (only soda lime glass) on which no protective film was formed.
The measurement results are shown in Table 2 as “Pre-test HAZE” for Examples 1 to 5 and Comparative Examples 1 and 2.

Next, each substrate on which protective films of Examples 1 to 5 and Comparative Example 1 were formed, and a substrate on which no protective film was formed (only soda lime glass) as Comparative Example 2, were used. A high-temperature and high-humidity test for 1000 hours was performed using a small environmental tester (SH-221) manufactured under the conditions of a temperature of 85 ° C. and a humidity of 85% RH. Then, the HAZE measurement of each board | substrate after a high temperature, high humidity test was performed.
The measurement results are shown in Table 2 as “post-test HAZE” for Examples 1 to 5 and Comparative Examples 1 and 2.

[HAZE measurement]
The HAZE value was measured using a spectroscopic haze meter (TC-1800H) manufactured by Tokyo Denshoku.

  As shown in Table 2, in the substrate of Comparative Example 2, the HAZE value was 0.0 in the initial state before the high-temperature and high-humidity test, but the high-temperature and high-humidity test increased the HAZE value to 8.8. It was found that significant whitening occurred.

On the other hand, in the substrates of Examples 1 to 5, it was found that even after the high temperature and high humidity test was performed, the HAZE value remained at 0.0 and no whitening occurred as before the test.
Compared with this, in the board | substrate of the comparative example 1, after implementing a high temperature high humidity test, HAZE value will be 1.9, and it shows a higher HAZE value than the case of the board | substrate of Examples 1-5, and whitening arises. I found out.

  The composition used for forming the protective film of the glass substrate of the present invention can provide a highly weather-resistant glass substrate by applying to the glass substrate, and can provide a solar cell, a liquid crystal display device, and an electroluminescence display element. It is useful as a substrate for a semiconductor device such as a thin film semiconductor device such as a thin film transistor for a liquid crystal display device or a thin film organic electroluminescence display element, or as a substrate for forming an electrode of a thin film type lithium battery.

  It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2013-016730 filed on January 31, 2013 are cited herein as disclosure of the specification of the present invention. Incorporated.

1, 11 Solar cell substrate 2, 12 Glass substrate 3, 3 ', 13 Protective film

Claims (15)

A glass substrate having a glass substrate and a protective film formed on the surface of the glass substrate,
The protective film contains a metal alkoxide represented by the following formulas (I) and (II) (including a partial condensate of a metal alkoxide) in an organic solvent in the presence of a metal salt represented by the following formula (III). A glass substrate used for the forefront of a device, wherein the glass substrate is formed by using a composition obtained by hydrolysis / condensation and adding a precipitation inhibitor.
M ¹ (OR ¹ ) _n (I)
^{(M 1} is .R ¹ representing the silicon or titanium emission represents the valence of .n is ^{M 1} represents an alkyl group having 1 to 5 carbon atoms.)
R ² _l M ² (OR ³ ) _4-1 (II)
(M ² represents silicon. R ² is substituted with a hydrogen atom or at least one selected from the group consisting of a halogen atom, a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a phenyl group, and a cyclohexyl group. And a C1-C20 hydrocarbon group which may have a hetero atom or a halogen atom, a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a phenyl group or a cyclohexyl group. R ³ represents an alkyl group having 1 to 5 carbon atoms, and l represents an integer of 1 to 3.
M ³ (X) _m (III)
(M ³ represents a metal. X represents chlorine, nitric acid, sulfuric acid, acetic acid, succinic acid, sulfamic acid, sulfonic acid, acetoacetic acid, acetylacetonate, or a basic salt thereof. M represents the valence of M ^3. .)

R ² in the formula (II) is substituted with a hydrogen atom or at least one selected from the group consisting of a halogen atom, a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a phenyl group, and a cyclohexyl group. The glass substrate according to claim 1, which is a hydrocarbon group having 1 to 20 carbon atoms which may have a hetero atom.   The glass substrate according to claim 1 or 2, wherein the metal alkoxide contains silicon alkoxide or is all silicon alkoxide.   The glass substrate according to claim 1, wherein the metal alkoxide contains titanium alkoxide.   The glass substrate according to claim 1, 2, or 4, wherein the metal alkoxide is a mixture of silicon alkoxide and titanium alkoxide.   The glass substrate according to claim 1, wherein all of the metal alkoxides are titanium alkoxides.   7. The precipitation inhibitor is at least one selected from the group consisting of N-methyl-pyrrolidone, ethylene glycol, dimethylformamide, dimethylacetamide, diethylene glycol, propylene glycol, hexylene glycol and derivatives thereof. The glass substrate of any one of these. The molar ratio of the total (M ¹ + M ² ) of metal atoms of the metal alkoxide and the metal atom (M ³ ) of the metal salt contained in the composition satisfies the following formula: The glass substrate according to item.
0.01 ≦ M ³ / (M ¹ + M ² ≦ 0.7   The metal salt is composed of metal nitrate, metal sulfate, metal acetate, metal chloride, metal oxalate, metal sulfamate, metal sulfonate, metal acetoacetate, metal acetylacetonate, and their basic salts. It is at least 1 sort (s) selected from the group, The glass substrate of any one of Claims 1-8. The M ^{3 in the} formula (III) is at least one selected from the group consisting of aluminum, indium, zinc, zirconium, bismuth, lanthanum, tantalum, yttrium, and cerium. Glass substrate.   The glass substrate according to any one of claims 4 to 6, wherein the organic solvent contains an alkylene glycol or a monoether derivative thereof.   The glass substrate for solar cells using the glass substrate of any one of Claims 1-11.   The glass substrate for a display using the glass substrate of any one of Claims 1-11.   A solar cell using the glass substrate according to claim 12.   A display using the glass substrate according to claim 13.

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