WO2022132080A1 - Anti-reflective silica based temperable coating solution - Google Patents

Anti-reflective silica based temperable coating solution Download PDF

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Publication number
WO2022132080A1
WO2022132080A1 PCT/TR2021/051008 TR2021051008W WO2022132080A1 WO 2022132080 A1 WO2022132080 A1 WO 2022132080A1 TR 2021051008 W TR2021051008 W TR 2021051008W WO 2022132080 A1 WO2022132080 A1 WO 2022132080A1
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Prior art keywords
weight
coating solution
coating
acid
mtes
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PCT/TR2021/051008
Other languages
French (fr)
Inventor
Refika BUDAKOGLU
Osman Burak OKAN
Gizem Aydin SOBACI
Ipek Nuran GILIK
Mehmet CUM
Hasan DEVECI
Original Assignee
Turkiye Sise Ve Cam Fabrikalari Anonim Sirketi
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Publication of WO2022132080A1 publication Critical patent/WO2022132080A1/en

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/22—Surface treatment of glass, not in the form of fibres or filaments, by coating with other inorganic material
    • C03C17/23—Oxides
    • C03C17/25—Oxides by deposition from the liquid phase
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2217/00—Coatings on glass
    • C03C2217/20—Materials for coating a single layer on glass
    • C03C2217/21—Oxides
    • C03C2217/213—SiO2
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2217/00—Coatings on glass
    • C03C2217/70—Properties of coatings
    • C03C2217/73—Anti-reflective coatings with specific characteristics
    • C03C2217/732—Anti-reflective coatings with specific characteristics made of a single layer
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2218/00—Methods for coating glass
    • C03C2218/10—Deposition methods
    • C03C2218/11—Deposition methods from solutions or suspensions
    • C03C2218/113—Deposition methods from solutions or suspensions by sol-gel processes

Definitions

  • the invention relates to a silica-based coating solution for off-line anti reflective applications and a process for its preparation.
  • the invention relates in particular to a silica-based temperable coating solution prepared by the sol-gel coating technique for use in photovoltaic (FV) glass panels, solar panel cover glasses, automotive glass, and showcase glasses, and a process for preparing the same.
  • a silica-based temperable coating solution prepared by the sol-gel coating technique for use in photovoltaic (FV) glass panels, solar panel cover glasses, automotive glass, and showcase glasses, and a process for preparing the same.
  • Coating is generally defined as the application of coating material to the surface by chemical or physical processes and the formation of a continuous or discontinuous film after drying.
  • PV panel systems convert solar rays to electrical energy with layers that perform various functions.
  • a basic PV system consists of photovoltaic cell, protective cover, aluminum case, and back main carrier layers. These layers reduce efficiency by reflecting rays from the sun in proportion to refractive indices.
  • Protective covers used to protect cells from external factors in the design of photovoltaic panels can be made of polymer or tempered glass. The higher the transmission of the panel glass, the greater the efficiency.
  • Single-layer antireflective coatings are widely used in photovoltaic panel glasses and are important in terms of increasing efficiency.
  • Reflection which is a natural physical event, is defined as the return of a part of the beam sent to the interface of the two media to the environment where it is sent to continue to spread.
  • Antireflective in other words, antireflective (AR) coatings are examples of coatings intended to alter optical properties.
  • Antireflective coatings which are produced from a single or multi-layer, nano/micro-structures, or a combination of both are designed to suppress reflection.
  • single-layer antireflective coatings applied to the surface of the glass create two surfaces as glass-coating and coatingair, where incoming light will be reflected.
  • the theoretical thickness of the coating between these two surfaces should be one fourth (A ⁇ 4) of the wavelength of the incident light.
  • a layer of coated film should be formed on the glass surface which has optical thickness (d.n C oati ng ) of one-quarter of the incoming light at wavelength and the refractive index of the coating should be greater than the refractive index of the air and smaller than the refractive index of the glass.
  • the sunlight absorbing layer is delivered with less loss and more benefit is provided from solar energy thanks to the increased transmission obtained in antireflective coatings.
  • EP1 181256B1 discloses a tempered safety glass having a scratch-resistant, porous SiO 2 antireflective layer and a method for producing it.
  • a standard glass is coated with colloidal dispersion, the coated glass is dried, and the organic components are heated to at least 630°C for removal and tempering of the glass in this method.
  • the said colloidal dispersion is obtained by hydrolytic condensation of certain silane compounds in the presence of a colloidally dissolved polymer in the medium.
  • the porous SiO 2 antireflective coating exhibits excellent adhesion and prevents or minimizes unwanted reflections. In addition, the resulting coating increases the transmission of electromagnetic radiation.
  • the safety glass disclosed herein is used, for example, in the coating of solar panels and photovoltaic cells.
  • Antireflective coatings consist of at least two different alkoxysilane materials in a base catalyzed reaction.
  • the coating layers are divided into two as non-porous and porous, while the porous coatings are again divided into two as open and closed pores according to the pore structure.
  • a substance in the form of gas or liquid entering the surface cavity can proceed within the coating without interruption of the connection path in coatings with an open pore structure. It is easier to obtain and chemically control these coatings even though the strength of these coatings is low.
  • the surface chemicals need to be modified to control the moisture effect. It is possible to prevent the disadvantages of porous coatings by modifying the coating film. Closed porous structures are generally obtained by producing hollow nanoparticles by methods such as synthesis and incorporating these particles into the coating. Closed pore structure is difficult to obtain and is less affected by moisture and similar environmental effects. Even though the corrosive resistance of single layer antireflective coatings with closed pore structure is high, due to the high production cost, the need for alternative coating solutions with equivalent performance, less costly, and easy to prepare continues .
  • Sol-gel coatings can be made using various application methods such as dip, spray, spin, and roll coating techniques.
  • the movable glass substrate is immersed and removed at a fixed speed into the stationary solution in the dip-coating method.
  • the dip coating technique is an off-line application technique and brings extra costs, especially in mass production conditions.
  • With the roll coating technique even though homogeneous coatings cannot be obtained as much as the coatings produced by the dip coating technique, optical performance of sufficient quality is provided especially when it comes to patterned glasses used in solar panels which has become widespread in recent years.
  • High acid solutions suitable for the dip coating method are at risk of rapid corrosion of the roll system and equipment if used in the roll coating system. Therefore, strong acid-free coating solutions are needed for roll coating systems.
  • the present invention relates to a silica-based temperable coating solution for use with the sol-gel coating technique for antireflective coating applications that meets the abovementioned requirements, eliminates all the disadvantages, and brings some additional advantages.
  • the primary object of the invention is to provide a temperable anti reflective coating free of nanoparticles for use in off-line antireflective applications.
  • Another object of the invention is to provide an antireflective coating that is resistant to atmospheric and corrosive conditions and has high mechanical resistance for use in off-line antireflective applications.
  • Another object of the invention is to provide an antireflective coating solution with a hybrid (organic-inorganic) structure obtained by chemically modifying silica-based solutions for use in off-line antireflective applications.
  • Another object of the invention is to provide a hybrid antireflective coating solution that is suitable for the sol-gel roll coating technique and provides single-layer and porous coating to a single surface. Large glass panels can be easily coated unilaterally in the method of coating with rolls.
  • Another object of the invention is to provide an antireflective coating to be used in photovoltaic (FV) glass panel production, solar panel cover glass coating applications, and window glass coatings in the solar energy sector.
  • PV photovoltaic
  • An object of the invention is to provide an antireflective coating solution having equivalent performance to that used in the present art, eliminating the need to use a pore agent or pore provider material compared to coating solutions.
  • Another object of the invention is to provide an antireflective coated glass product with increased corrosion resistance.
  • the present invention provides a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications, in order to realize all the objects mentioned above and to emerge from the detailed description below.
  • the said coating solution comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore; and MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2.
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • the present invention also provides a process for preparing a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications to realize all the objects mentioned above and which will emerge from the detailed description below.
  • the said process comprises the steps of:
  • step (ii) mixing by adding tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and methyltriethoxysilane (MTES) as another source of silica and pore to said solvent, wherein MTES/TEOS mole ratio is about 1 ,2 or less than 1 ,2; and mixing by adding catalyst to the mixture obtained in step (iii).
  • TEOS tetraethylorthosilicate
  • MTES methyltriethoxysilane
  • the present invention also provides the use of a composition
  • a composition comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore as a sol-gel coating solution.
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • the present invention also provides a method for coating a glass article with an antireflective thin film for off-line antireflective applications to realize all the objects mentioned above and which will emerge from the detailed description below.
  • the said method comprises the steps of:
  • a silica-based temperable coating solution comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore, wherein the MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2;
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • the present invention also provides a glass article having an antireflective thin film coating to achieve all the objects mentioned above and to be revealed in the detailed description below.
  • the thin film coating is obtained by coating the glass surface with a coating solution comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore.
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • Figure 1 is a view of the spectral analysis graph of the coated and uncoated glass substrate according to the invention.
  • Figure 2 is a cross-sectional view of the coated glass according to the invention with FEG- SEM.
  • Figure 3 is the TEM sectional views of the coated glass according to the invention.
  • Figure 4 is the TEM surface views of coated glass according to the invention.
  • the present invention provides a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications.
  • the coating solution of the invention comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore and MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2.
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • TEOS TEOS
  • MTES methyl triethoxysilane
  • the hybrid (organic-inorganic) coatings of the invention are temperable.
  • the invention advantageously provides a coating solution comprising branched silane and having AR properties under tempered conditions.
  • the hybrid (organic-inorganic) coatings subject to the invention can be prepared in a short time and easily. There is no need for synthesis studies for the need to make a pore agent or pore.
  • the coating solution subject to the invention provides a coating solution to be used in photovoltaic (FV) glass panel production, solar panel cover glass coating applications and showcase glass coatings, preferably in the solar energy sector with the sol-gel coating method.
  • PV photovoltaic
  • TEOS tetraethylorthosilicate
  • MTES methyltriethoxysilane
  • MTES should be used in proportions that can give the optimum coating thickness since the coating thickness changes as the amount of MTES increases. It has been found that MTES/TEOS mole ratios, which vary with the increasing MTES ratio, have effects on the final properties of the coatings. The average particle size and polymerization rate also increase with the increase in the MTES mole ratio. The increased MTES mole ratio also increases the hydrophobic properties of the coating films.
  • the MTES/TEOS mole ratio in the coating solution of the invention is 1 ,2 or less than 1 ,2.
  • MTES/TEOS mole ratio in the coating solution is approximately 1 ,2.
  • the optimum coating thickness of 100 nm and the lowest refractive index are obtained when the MTES/TEOS mole ratio is 1 ,2. Coating becomes difficult, and the density and surface roughness of the coatings increase when the MTES/TEOS mole ratio exceeds 1 ,2. Increased MTES mole ratio may also cause opacification. It was observed that the transmission values of the coatings made with the solution of MTES/TEOS mole ratio higher than 1 ,2 decreased in the repeated coatings after the solution waited while the transmission values for the coated samples increased with the MTES ratio 1 day after the coating solution was prepared. A synergistic increase in transmission was obtained when the solution with a MTES/TEOS mole ratio of 1 ,2 was coated at the end of the 4 th week.
  • the coating solution of the invention comprises a solvent mixture containing propylene glycol monomethyl ether acetate, ethanol, and 2- propanol in predetermined amounts as solvents.
  • the said mixture provides controlled evaporation in the coating solution.
  • the said solvent mixture contains about 3-5% by weight of propylene glycol monomethyl ether acetate, about 12-15% by weight of ethanol and about 85% by weight of 2-propanoL
  • the ratio by weight of the solvent mixture in the total coating solution is preferably about 70-80%.
  • Catalysts divided into two groups as acid and base are used in the sol-gel method.
  • At least one organic acid is used to accelerate the hydrolysis of alkoxysilane in the coating solution of the invention.
  • Preferred organic acids include acetic acid, glacialacetic acid, formic acid, ascorbic acid, citric acid. The most preferred organic acid is acetic acid.
  • At least one inorganic acid is used together with the organic acid as the catalyst in a preferred application of the invention.
  • Preferred inorganic acids include nitric acid, hydrochloric acid, and hydrochloric acid.
  • the most preferred inorganic acid is nitric acid.
  • the coating solution contains nitric acid together with acetic acid as the catalyst.
  • the ratio by weight of acetic acid in the coating solution is preferably 1-3% and the ratio by weight of nitric acid in the coating solution is 0, 0-0,1%.
  • the coating solution of the invention may also contain about 2-4% by weight of distilled water.
  • the coating solution contains 8-10% by weight tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica, 8-10% by weight methyltriethoxysilane (MTES) as another source of silica and pore; 1-3% by weight glacial acetic acid as a catalyst and 0, 0-0,1% by weight nitric acid; 2-5% by weight propylene glycol monomethyl ether acetate as a solvent, 9-15% by weight ethanol and 60-70% by weight of 2- propanol; and 2-4% by weight distilled water.
  • Table 1 The formulation of a coating solution according to the invention is provided in Table 1 .
  • Antireflective coatings can be designed as single or multilayered in order to obtain the desired thickness and refractive index values. Formulas and mathematical calculations used when designing layers vary by the number of layers.
  • a single-layer coating layer produces two reflective surfaces due to its thickness. Some of the beam coming to the first surface is reflected while some can pass through and be reflected from the second surface, and the passing beam can diffuse or be reflected again on the rear surface. In fact, the beam reflected from the lower surface and the beam reflected from the upper surface are on the same side of the film. When the phase differences are 180°, a balance is formed between them and an advantage is provided for the antireflective glasses.
  • a film to be antireflective (AR) There are two basic requirements for a film to be antireflective (AR). The first of these, the two light beams coming out of the film, should be 180° phase from low to high index environment. The second is that the optical thickness of the film should be a single integer at the multiple of the quarter wavelength. It is only possible to obtain such a refractive index with existing materials by porous structures. Pores in various shapes and methods can be created in the thin film layer to lower the refractive index when designing the coating. The transmission is increased by using the refractive index of the cavity in this way. A porous antireflective coating with a low refractive index can significantly increase the transmission of the glass, but cannot guarantee the same level of performance as any type of glass. Porous coatings are again divided into two as open and closed pores.
  • a substance in the form of gas or liquid entering the surface cavity can proceed within the coating without interruption of the connection path in coatings with an open pore structure. It is easier to obtain and chemically control these coatings even though the strength of these coatings is low.
  • the surface chemicals need to be modified to control the moisture effect. Closed porous structures are generally obtained by producing hollow nanoparticles by methods such as synthesis and incorporating these particles into the coating. Closed pore structure is difficult to obtain and is less affected by moisture and similar environmental effects. Production flexibility is also less and costly with different production methods.
  • the properties of the coating film layer vary according to the shape, size, quantity, and distribution of the pores as well as being affected by the open or closed porosity. The disadvantages of porous coatings are eliminated by modifying the coating film/layer with the present invention.
  • the present invention provides a process for preparing a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications.
  • the said process comprises the following process steps:
  • TEOS tetraethylorthosilicate
  • MTES methyltriethoxysilane
  • MTES/TEOS mole ratio in the coating solution is approximately 1 ,2.
  • the coating solution of the invention comprises a solvent mixture containing propylene glycol monomethyl ether acetate, ethanol, and 2- propanol in predetermined amounts as solvents.
  • the solvent components are mixed to prepare the main solvent mixture in the said process for the preparation of the coating solution.
  • Ethanol is added to propylene glycol monomethyl ether acetate and mixed for an average of 5 minutes, then 2-propanol is added and mixed for 5 minutes for this purpose.
  • TEOS, MTES, and water are added to the obtained solvent mixture and an average of 5 minutes of mixing is performed in each addition.
  • an organic acid preferably glacial acetic acid
  • an organic acid preferably nitric acid
  • the reaction is preferably carried out at room temperature.
  • the present invention provides for the use of a composition
  • a composition comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore as a sol-gel coating solution.
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • the present invention provides a method for coating a glass article with an antireflective thin film for off-line antireflective applications.
  • the said method includes the following process steps.
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • MTES/TEOS mole ratio in the coating solution is approximately 1 ,2.
  • the coating process is preferably carried out using the sol-gel roll coating technique in the said method.
  • Thin film coatings can be obtained from the gas phase by physical and chemical vapor deposition methods, while they can also be produced from the solution phase by electrochemical deposition or sol-gel method.
  • the sol-gel method stands out with its advantageous features such as obtaining products at low temperatures and high purity, control of particle properties, chemical modification of initiating materials, control of hydrolysis and condensation steps, final product design, and obtaining products of high optical quality among all these methods.
  • the method of coating with sol-gel is also a method that allows the production of films with inorganic and hybrid coating materials.
  • the coating film is produced by heat treatment and the liquid phase deposition method can be any of the screening, dr.
  • the low viscosity coating liquid is left as a thin film layer on the substrate material while the material to be coated passes between two cylindrical rolls that move on the belt and rotate at high speeds. Roll speed, belt speed, distance between the rolls, and the amount of solution supplied to the rolls are among the coating parameters. It has been found that the coating solution subject to the invention exhibits improved features especially in photovoltaic (FV) glass panel production, solar panel cover glass coating applications, and window glass coatings in the solar energy sector using the sol-gel roller coating method.
  • the sol-gel roll coating method is one of the most suitable and fast coating methods for single surface coatings. In addition, this method can be added to the continuation of the line.
  • the coating process is carried out as a single layer on a single surface.
  • the invention provides a glass article having an antireflective thin film coating.
  • the thin film coating is obtained by coating the glass surface with a coating solution comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore, wherein the mole ratio of MTES/TEOS in the coating solution is equal to or less than about 1 ,2.
  • TEOS tetraethylorthosilicate
  • MTES methyl triethoxysilane
  • the coating process is carried out using the solgel roll coating technique.
  • the coating process is carried out as a single layer on a single surface.
  • the glass surface in the 60 e C washing system was cleaned of dirt such as oil, dust, glass dust before coating the glass surface. It was dried and made ready for coating after rinsing.
  • Example 2 Preparation of Coating Solution Suitable for the Invention Methyl triethoxysilane (Dynasylan® MTES) was used in combination with tetraethylorthosilicate (Dynasylan® A) in the coating solution.
  • the solution was prepared in 100 grams of samples.
  • the MTES/TEOS mole ratio in the solution was adjusted to be 1 ,2.
  • the solvent mixture containing propylene glycol monomethyl ether acetate (PMA, Micro Technique 99,9%), 12% ethanol (EtOH, SigmaAldrich 96%), and 85% propanol (IPA, SigmaAldrich 99,8%) was used in the solution formulation at a rate of 77-80% by weight.
  • Distilled water in the rate of 2, 7-3,0% by weight was used as water/alkoxy (R) ratio 2, and 3,0% acetic acid (GAA, Merck 100%) and 0.08% nitric acid (HNO3, Merck 65%) were used as catalysts for each solution.
  • GAA acetic acid
  • HNO3, Merck 65% nitric acid
  • the coating solution of the invention was initially added to a container without the solvent mixture components waiting step and mixed for 5 minutes to be homogeneous in itself. Then, TEOS, MTES, distilled water, acetic acid and nitric acid were added, respectively. A mixing duration of 5 minutes was applied after each addition and a mixing duration of 1 hour was applied to obtain the final solution after all the additions.
  • the glasses were coated as a single film layer with the sol-gel roll coating technique with the coating solution subject to the invention. It was exposed to tempering at 680 e -700 e C for 3 minutes after curing at 100 e C after coating.
  • Figure 1 shows the spectral analysis graph of the coated and uncoated glass substrate according to the invention.
  • Figure 2 shows a sectional view of the general coating film with FEG-SEM.
  • Sectional examination of the coated glass obtained in Figure 3a with conventional bright field (BF) and high-angle annular dark-field (HAADF) imaging techniques in Figure 3b was performed by TEM analysis. Very low electron dose STEM images were obtained to avoid any beam changes due to the coating and the lower glass under scanning. No apparent pore was observed in the coating. Dark vertical lines on the HAADF-STEM image are traces caused by FIB etching. The surface of the coated glass obtained in Figure 4a was examined by TEM analysis with conventional bright field (BF) and high-angle annular dark-field (HAADF) imaging techniques in Figure 4b.
  • BF bright field
  • HAADF high-angle annular dark-field

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Abstract

The invention relates to a silica-based temperable coating solution for use in off-line antireflective applications, in particular for photovoltaic (FV) glass panels, solar panel cover glasses, automotive glass and showcase glasses to be applied with the sol-gel coating technique.

Description

ANTI-REFLECTIVE SILICA BASED TEMPERABLE COATING SOLUTION
TECHNICAL FIELD
The invention relates to a silica-based coating solution for off-line anti reflective applications and a process for its preparation.
The invention relates in particular to a silica-based temperable coating solution prepared by the sol-gel coating technique for use in photovoltaic (FV) glass panels, solar panel cover glasses, automotive glass, and showcase glasses, and a process for preparing the same.
KNOWN STATE OF THE ART
Surface coatings are made by various methods to improve glass by decor (ornament), optical, thermal, electrical, mechanical, and chemical properties. Today, surface coatings can usually be applied online during glass production or off-line after production. Coating is generally defined as the application of coating material to the surface by chemical or physical processes and the formation of a continuous or discontinuous film after drying.
Photovoltaic (FV) panel systems convert solar rays to electrical energy with layers that perform various functions. A basic PV system consists of photovoltaic cell, protective cover, aluminum case, and back main carrier layers. These layers reduce efficiency by reflecting rays from the sun in proportion to refractive indices. Protective covers used to protect cells from external factors in the design of photovoltaic panels can be made of polymer or tempered glass. The higher the transmission of the panel glass, the greater the efficiency. Single-layer antireflective coatings are widely used in photovoltaic panel glasses and are important in terms of increasing efficiency.
Reflection, which is a natural physical event, is defined as the return of a part of the beam sent to the interface of the two media to the environment where it is sent to continue to spread. Antireflective, in other words, antireflective (AR) coatings are examples of coatings intended to alter optical properties. Antireflective coatings, which are produced from a single or multi-layer, nano/micro-structures, or a combination of both are designed to suppress reflection. In order to increase the transmission of the glass, single-layer antireflective coatings applied to the surface of the glass create two surfaces as glass-coating and coatingair, where incoming light will be reflected. The theoretical thickness of the coating between these two surfaces should be one fourth (A\4) of the wavelength of the incident light. In other words, in order to obtain an antireflective coating, a layer of coated film should be formed on the glass surface which has optical thickness (d.nCoating) of one-quarter of the incoming light at wavelength and the refractive index of the coating should be greater than the refractive index of the air and smaller than the refractive index of the glass. The sunlight absorbing layer is delivered with less loss and more benefit is provided from solar energy thanks to the increased transmission obtained in antireflective coatings.
EP1 181256B1 discloses a tempered safety glass having a scratch-resistant, porous SiO2 antireflective layer and a method for producing it. A standard glass is coated with colloidal dispersion, the coated glass is dried, and the organic components are heated to at least 630°C for removal and tempering of the glass in this method. The said colloidal dispersion is obtained by hydrolytic condensation of certain silane compounds in the presence of a colloidally dissolved polymer in the medium. The porous SiO2 antireflective coating exhibits excellent adhesion and prevents or minimizes unwanted reflections. In addition, the resulting coating increases the transmission of electromagnetic radiation. The safety glass disclosed herein is used, for example, in the coating of solar panels and photovoltaic cells.
The patent numbered US8557877B2 discloses antireflective coatings and coating solutions, optically transparent elements, and improved procedures for preparing AR coatings and coating solutions. Antireflective coatings consist of at least two different alkoxysilane materials in a base catalyzed reaction.
The coating layers are divided into two as non-porous and porous, while the porous coatings are again divided into two as open and closed pores according to the pore structure. A substance in the form of gas or liquid entering the surface cavity can proceed within the coating without interruption of the connection path in coatings with an open pore structure. It is easier to obtain and chemically control these coatings even though the strength of these coatings is low. The surface chemicals need to be modified to control the moisture effect. It is possible to prevent the disadvantages of porous coatings by modifying the coating film. Closed porous structures are generally obtained by producing hollow nanoparticles by methods such as synthesis and incorporating these particles into the coating. Closed pore structure is difficult to obtain and is less affected by moisture and similar environmental effects. Even though the corrosive resistance of single layer antireflective coatings with closed pore structure is high, due to the high production cost, the need for alternative coating solutions with equivalent performance, less costly, and easy to prepare continues .
Various physical and chemical deposition methods are used in the production of thin film coatings. The most commonly used method in the production of antireflective coatings in PV sector is sol-gel method. Since, reactions take place at room temperature with the sol-gel method, heat is not needed and thermal decomposition of chemicals is minimized, porous or nanocrystalline materials can be produced. Hydrolysis and condensation rates can be controlled, pore size, distribution, and control over pore wall chemistry can be achieved, and porosity and mechanical strength control can be achieved by controlling aging and drying conditions with chemical modification.
Sol-gel coatings can be made using various application methods such as dip, spray, spin, and roll coating techniques. The movable glass substrate is immersed and removed at a fixed speed into the stationary solution in the dip-coating method. The dip coating technique is an off-line application technique and brings extra costs, especially in mass production conditions. With the roll coating technique, even though homogeneous coatings cannot be obtained as much as the coatings produced by the dip coating technique, optical performance of sufficient quality is provided especially when it comes to patterned glasses used in solar panels which has become widespread in recent years. High acid solutions suitable for the dip coating method are at risk of rapid corrosion of the roll system and equipment if used in the roll coating system. Therefore, strong acid-free coating solutions are needed for roll coating systems.
In addition, there is a need for coating solutions that do not cause corrosion in the known state of the art and that can provide cavity/pore creation with porosity agent or core-shell in all AR coatings.
In conclusion, it was deemed necessary to make an improvement in the relevant technical field due to the negativities described above and the inadequacy of the existing solutions on the subject.
BRIEF DESCRIPTION OF THE INVENTION
The present invention relates to a silica-based temperable coating solution for use with the sol-gel coating technique for antireflective coating applications that meets the abovementioned requirements, eliminates all the disadvantages, and brings some additional advantages.
The primary object of the invention is to provide a temperable anti reflective coating free of nanoparticles for use in off-line antireflective applications.
Another object of the invention is to provide an antireflective coating that is resistant to atmospheric and corrosive conditions and has high mechanical resistance for use in off-line antireflective applications.
Another object of the invention is to provide an antireflective coating solution with a hybrid (organic-inorganic) structure obtained by chemically modifying silica-based solutions for use in off-line antireflective applications.
Another object of the invention is to provide a hybrid antireflective coating solution that is suitable for the sol-gel roll coating technique and provides single-layer and porous coating to a single surface. Large glass panels can be easily coated unilaterally in the method of coating with rolls.
Another object of the invention is to provide an antireflective coating to be used in photovoltaic (FV) glass panel production, solar panel cover glass coating applications, and window glass coatings in the solar energy sector.
An object of the invention is to provide an antireflective coating solution having equivalent performance to that used in the present art, eliminating the need to use a pore agent or pore provider material compared to coating solutions.
Another object of the invention is to provide an antireflective coated glass product with increased corrosion resistance. The durability of products such as photovoltaic glass panels, which are used for a long time especially in very corrosive conditions, is increased in this way.
The present invention provides a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications, in order to realize all the objects mentioned above and to emerge from the detailed description below. The said coating solution comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore; and MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2.
The present invention also provides a process for preparing a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications to realize all the objects mentioned above and which will emerge from the detailed description below. The said process comprises the steps of:
(i) supplying a solvent;
(ii) mixing by adding tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and methyltriethoxysilane (MTES) as another source of silica and pore to said solvent, wherein MTES/TEOS mole ratio is about 1 ,2 or less than 1 ,2; and mixing by adding catalyst to the mixture obtained in step (iii).
In order to realize all the objects mentioned above and to emerge from the detailed description below, the present invention also provides the use of a composition comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore as a sol-gel coating solution. MTES/TEOS mole ratio in the said coating solution is less than or equal to about 1 ,2.
The present invention also provides a method for coating a glass article with an antireflective thin film for off-line antireflective applications to realize all the objects mentioned above and which will emerge from the detailed description below. The said method comprises the steps of:
(a) supplying a silica-based temperable coating solution, wherein the said coating solution comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore, wherein the MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2;
(b) supplying a glass product; and
(c) coating the said glass product with the said coating solution.
The present invention also provides a glass article having an antireflective thin film coating to achieve all the objects mentioned above and to be revealed in the detailed description below. The thin film coating is obtained by coating the glass surface with a coating solution comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore. MTES/TEOS mole ratio in the coating solution is approximately less than or equal to 1 ,2.
The structural and characteristic features and all the advantages of the invention will be understood more clearly by means of the figures and the detailed description with reference to these figures given below and therefore, the evaluation should be made by taking these figures and the detailed description into consideration.
FIGURES
Figure 1 is a view of the spectral analysis graph of the coated and uncoated glass substrate according to the invention.
Figure 2 is a cross-sectional view of the coated glass according to the invention with FEG- SEM.
Figure 3 is the TEM sectional views of the coated glass according to the invention.
Figure 4 is the TEM surface views of coated glass according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the coating solution and the coating solution of the invention are explained only for a better understanding of the subject and without any limiting effect in this detailed description.
The present invention provides a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications. The coating solution of the invention comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore and MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2.
There are coating solutions with antireflective properties by using TEOS starting material and TEOS modified with different components including pore agent in the state of the art. Although the corrosion resistance of single layer antireflective coatings with closed pore structure is high, production costs are high. The main parameters effective in the sol-gel reaction are the precursors pH/catalyst, H20/alkoxy mol ratio and thermal conditions. Tetraethylorthosilicate (TEOS) and methyl triethoxysilane (MTES) are used in the present invention at a certain mole ratio as precursors. An increase in the TEOS concentration leads to an increase in the viscosity of the coating solution and also in the concentration of the polymer without significant changes in its size or shape. It has been found that there is a surprising improvement in the mechanical properties of the coatings such as hardness, wear, and scratch strength when MTES and TEOS are used together with the present invention and the MTES/TEOS mole ratio is approximately equal to or less than 1 ,2. In addition, it was found that the increase in MTES in the coating solution composition increased the strength of the coating films by giving them elastic properties.
The hybrid (organic-inorganic) coatings of the invention are temperable. The invention advantageously provides a coating solution comprising branched silane and having AR properties under tempered conditions.
The hybrid (organic-inorganic) coatings subject to the invention can be prepared in a short time and easily. There is no need for synthesis studies for the need to make a pore agent or pore. The coating solution subject to the invention provides a coating solution to be used in photovoltaic (FV) glass panel production, solar panel cover glass coating applications and showcase glass coatings, preferably in the solar energy sector with the sol-gel coating method.
A hybrid structure was obtained using tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) as initiators in the coating solution. TEOS in the solution forms the skeletal structure in the antireflective thin film. MTES should be used in proportions that can give the optimum coating thickness since the coating thickness changes as the amount of MTES increases. It has been found that MTES/TEOS mole ratios, which vary with the increasing MTES ratio, have effects on the final properties of the coatings. The average particle size and polymerization rate also increase with the increase in the MTES mole ratio. The increased MTES mole ratio also increases the hydrophobic properties of the coating films. The MTES/TEOS mole ratio in the coating solution of the invention is 1 ,2 or less than 1 ,2.
In a preferred embodiment of the invention, MTES/TEOS mole ratio in the coating solution is approximately 1 ,2. The optimum coating thickness of 100 nm and the lowest refractive index are obtained when the MTES/TEOS mole ratio is 1 ,2. Coating becomes difficult, and the density and surface roughness of the coatings increase when the MTES/TEOS mole ratio exceeds 1 ,2. Increased MTES mole ratio may also cause opacification. It was observed that the transmission values of the coatings made with the solution of MTES/TEOS mole ratio higher than 1 ,2 decreased in the repeated coatings after the solution waited while the transmission values for the coated samples increased with the MTES ratio 1 day after the coating solution was prepared. A synergistic increase in transmission was obtained when the solution with a MTES/TEOS mole ratio of 1 ,2 was coated at the end of the 4th week.
In a preferred embodiment of the invention, the coating solution of the invention comprises a solvent mixture containing propylene glycol monomethyl ether acetate, ethanol, and 2- propanol in predetermined amounts as solvents. The said mixture provides controlled evaporation in the coating solution. In a preferred embodiment of the invention, the said solvent mixture contains about 3-5% by weight of propylene glycol monomethyl ether acetate, about 12-15% by weight of ethanol and about 85% by weight of 2-propanoL The ratio by weight of the solvent mixture in the total coating solution is preferably about 70-80%.
Catalysts divided into two groups as acid and base are used in the sol-gel method. At least one organic acid is used to accelerate the hydrolysis of alkoxysilane in the coating solution of the invention. Preferred organic acids include acetic acid, glacialacetic acid, formic acid, ascorbic acid, citric acid. The most preferred organic acid is acetic acid.
At least one inorganic acid is used together with the organic acid as the catalyst in a preferred application of the invention. Preferred inorganic acids include nitric acid, hydrochloric acid, and hydrochloric acid. The most preferred inorganic acid is nitric acid. In a more preferred embodiment of the invention, the coating solution contains nitric acid together with acetic acid as the catalyst. The ratio by weight of acetic acid in the coating solution is preferably 1-3% and the ratio by weight of nitric acid in the coating solution is 0, 0-0,1%.
The coating solution of the invention may also contain about 2-4% by weight of distilled water.
In the most preferred embodiment of the invention, the coating solution contains 8-10% by weight tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica, 8-10% by weight methyltriethoxysilane (MTES) as another source of silica and pore; 1-3% by weight glacial acetic acid as a catalyst and 0, 0-0,1% by weight nitric acid; 2-5% by weight propylene glycol monomethyl ether acetate as a solvent, 9-15% by weight ethanol and 60-70% by weight of 2- propanol; and 2-4% by weight distilled water. The formulation of a coating solution according to the invention is provided in Table 1 .
Table 1 Formulation of a coating solution according to the invention
Figure imgf000010_0001
Antireflective coatings can be designed as single or multilayered in order to obtain the desired thickness and refractive index values. Formulas and mathematical calculations used when designing layers vary by the number of layers. A single-layer coating layer produces two reflective surfaces due to its thickness. Some of the beam coming to the first surface is reflected while some can pass through and be reflected from the second surface, and the passing beam can diffuse or be reflected again on the rear surface. In fact, the beam reflected from the lower surface and the beam reflected from the upper surface are on the same side of the film. When the phase differences are 180°, a balance is formed between them and an advantage is provided for the antireflective glasses.
There are two basic requirements for a film to be antireflective (AR). The first of these, the two light beams coming out of the film, should be 180° phase from low to high index environment. The second is that the optical thickness of the film should be a single integer at the multiple of the quarter wavelength. It is only possible to obtain such a refractive index with existing materials by porous structures. Pores in various shapes and methods can be created in the thin film layer to lower the refractive index when designing the coating. The transmission is increased by using the refractive index of the cavity in this way. A porous antireflective coating with a low refractive index can significantly increase the transmission of the glass, but cannot guarantee the same level of performance as any type of glass. Porous coatings are again divided into two as open and closed pores. A substance in the form of gas or liquid entering the surface cavity can proceed within the coating without interruption of the connection path in coatings with an open pore structure. It is easier to obtain and chemically control these coatings even though the strength of these coatings is low. The surface chemicals need to be modified to control the moisture effect. Closed porous structures are generally obtained by producing hollow nanoparticles by methods such as synthesis and incorporating these particles into the coating. Closed pore structure is difficult to obtain and is less affected by moisture and similar environmental effects. Production flexibility is also less and costly with different production methods. The properties of the coating film layer vary according to the shape, size, quantity, and distribution of the pores as well as being affected by the open or closed porosity. The disadvantages of porous coatings are eliminated by modifying the coating film/layer with the present invention.
The present invention provides a process for preparing a silica-based temperable coating solution for use with the sol-gel coating technique for off-line antireflective coating applications. The said process comprises the following process steps:
(i) supplying a solvent;
(ii) mixing by adding tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and methyltriethoxysilane (MTES) as another source of silica and pore to the said solvent mixture, wherein MTES/TEOS mole ratio is about 1 ,2 or less than 1 ,2; and
(iii) mixing by adding catalyst to the mixture obtained in step (ii).
In a preferred embodiment of the invention, MTES/TEOS mole ratio in the coating solution is approximately 1 ,2.
In a preferred embodiment of the invention, the coating solution of the invention comprises a solvent mixture containing propylene glycol monomethyl ether acetate, ethanol, and 2- propanol in predetermined amounts as solvents. Firstly, the solvent components are mixed to prepare the main solvent mixture in the said process for the preparation of the coating solution. Ethanol is added to propylene glycol monomethyl ether acetate and mixed for an average of 5 minutes, then 2-propanol is added and mixed for 5 minutes for this purpose. TEOS, MTES, and water are added to the obtained solvent mixture and an average of 5 minutes of mixing is performed in each addition. Then, an organic acid, preferably glacial acetic acid, is added to the mixture as a catalyst and the solution is mixed for a further 5 minutes for homogeneous distribution and finally an organic acid, preferably nitric acid, is added and the solution is mixed for 1 hour to obtain homogeneity. The reaction is preferably carried out at room temperature.
The present invention provides for the use of a composition comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore as a sol-gel coating solution. MTES/TEOS mole ratio in the coating solution is less than or equal to 1 ,2 in the said use.
The present invention provides a method for coating a glass article with an antireflective thin film for off-line antireflective applications. The said method includes the following process steps.
• preparing a silica-based temperable coating solution, wherein the said coating solution comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore, wherein MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2;
• supplying a glass product; and
• coating the said glass product with the said coating solution.
In a preferred embodiment of the invention, MTES/TEOS mole ratio in the coating solution is approximately 1 ,2.
The coating process is preferably carried out using the sol-gel roll coating technique in the said method. Thin film coatings can be obtained from the gas phase by physical and chemical vapor deposition methods, while they can also be produced from the solution phase by electrochemical deposition or sol-gel method. The sol-gel method stands out with its advantageous features such as obtaining products at low temperatures and high purity, control of particle properties, chemical modification of initiating materials, control of hydrolysis and condensation steps, final product design, and obtaining products of high optical quality among all these methods. The method of coating with sol-gel is also a method that allows the production of films with inorganic and hybrid coating materials. The coating film is produced by heat treatment and the liquid phase deposition method can be any of the screening, dr. blade, spraying, rotating, rolling or dip coating methods after the deposition of the liquid phase on the sub-material. Larger materials can be easily coated even though there is more solution consumption in the method of coating with rolls compared to other methods. The low viscosity coating liquid is left as a thin film layer on the substrate material while the material to be coated passes between two cylindrical rolls that move on the belt and rotate at high speeds. Roll speed, belt speed, distance between the rolls, and the amount of solution supplied to the rolls are among the coating parameters. It has been found that the coating solution subject to the invention exhibits improved features especially in photovoltaic (FV) glass panel production, solar panel cover glass coating applications, and window glass coatings in the solar energy sector using the sol-gel roller coating method. The sol-gel roll coating method is one of the most suitable and fast coating methods for single surface coatings. In addition, this method can be added to the continuation of the line.
In a preferred embodiment of the invention, the coating process is carried out as a single layer on a single surface.
The invention provides a glass article having an antireflective thin film coating. The thin film coating is obtained by coating the glass surface with a coating solution comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore, wherein the mole ratio of MTES/TEOS in the coating solution is equal to or less than about 1 ,2.
In a preferred embodiment of the invention, the coating process is carried out using the solgel roll coating technique.
In another preferred embodiment of the invention, the coating process is carried out as a single layer on a single surface.
Examples
Example 1 - Supply and Preparation of Glass Substrate
The glass surface in the 60eC washing system was cleaned of dirt such as oil, dust, glass dust before coating the glass surface. It was dried and made ready for coating after rinsing.
Example 2 - Preparation of Coating Solution Suitable for the Invention Methyl triethoxysilane (Dynasylan® MTES) was used in combination with tetraethylorthosilicate (Dynasylan® A) in the coating solution. The solution was prepared in 100 grams of samples. The MTES/TEOS mole ratio in the solution was adjusted to be 1 ,2. The solvent mixture containing propylene glycol monomethyl ether acetate (PMA, Micro Technique 99,9%), 12% ethanol (EtOH, SigmaAldrich 96%), and 85% propanol (IPA, SigmaAldrich 99,8%) was used in the solution formulation at a rate of 77-80% by weight. Distilled water in the rate of 2, 7-3,0% by weight was used as water/alkoxy (R) ratio 2, and 3,0% acetic acid (GAA, Merck 100%) and 0.08% nitric acid (HNO3, Merck 65%) were used as catalysts for each solution.
The coating solution of the invention was initially added to a container without the solvent mixture components waiting step and mixed for 5 minutes to be homogeneous in itself. Then, TEOS, MTES, distilled water, acetic acid and nitric acid were added, respectively. A mixing duration of 5 minutes was applied after each addition and a mixing duration of 1 hour was applied to obtain the final solution after all the additions.
Example 3 - Coating Process
The glasses were coated as a single film layer with the sol-gel roll coating technique with the coating solution subject to the invention. It was exposed to tempering at 680e-700eC for 3 minutes after curing at 100eC after coating.
Conclusion
Figure 1 shows the spectral analysis graph of the coated and uncoated glass substrate according to the invention.
Figure 2 shows a sectional view of the general coating film with FEG-SEM.
Sectional examination of the coated glass obtained in Figure 3a with conventional bright field (BF) and high-angle annular dark-field (HAADF) imaging techniques in Figure 3b was performed by TEM analysis. Very low electron dose STEM images were obtained to avoid any beam changes due to the coating and the lower glass under scanning. No apparent pore was observed in the coating. Dark vertical lines on the HAADF-STEM image are traces caused by FIB etching. The surface of the coated glass obtained in Figure 4a was examined by TEM analysis with conventional bright field (BF) and high-angle annular dark-field (HAADF) imaging techniques in Figure 4b.
No pore structure was found when both the cross-sectional and surface images of the samples were examined. The maximum pore size that can be observed with this characterization method is 2-3 nm. This can be explained by the presence of cavity structures at the molecular level, since no pore is observed at the nanoscale.

Claims

1. A silica-based temperable coating solution for applying with the sol-gel coating technique for off-line antireflective coating applications, characterized in that it comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore, wherein MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2.
2. A coating solution according to claim 1 , characterized in that MTES/TEOS mole ratio in the coating solution is approximately equal to 1 ,2.
3. A coating solution according to any of the preceding claims, comprising a solvent mixture containing propylene glycol monomethyl ether acetate, ethanol, and 2- propanol in predetermined amounts as solvents.
4. A coating solution according to claim 3, wherein the said solvent mixture comprises about 3-5% by weight of propylene glycol monomethyl ether acetate, about 12-15% by weight of ethanol and about 70-80% by weight of 2-propanoL
5. A coating solution according to any of the preceding claims, comprising about 77- 80% by weight of the solvent mixture.
6. A coating solution according to any of the preceding claims, comprising at least one organic acid selected from acetic acid, glacial acetic acid, formic acid, ascorbic acid, citric acid, and at least one inorganic acid selected from nitric acid, hydrochloric acid, and hydrofluoric acid as catalyst.
7. A coating solution according to claim 6, wherein said organic acid is acetic acid and said inorganic acid is nitric acid.
8. A coating solution according to claim 7, wherein the ratio by weight of said acetic acid is 1 -3% and the ratio by weight of said nitric acid is 0,0-0, 1%.
9. A coating solution according to any of the preceding claims, comprising about 2-4% by weight of distilled water.
10. A coating solution according to any of the preceding claims, comprising about 8-10% by weight of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica; about 8- 10% by weight of methyl triethoxysilane (MTES) as another source of silica and pore; about 1 -3% by weight of glacial acetic acid and about 0,0-0, 1% by weight of nitric acid as catalyst; about 2-5% by weight of propylene glycol monomethyl ether acetate as a solvent, about 9-15% by weight of ethanol and about 60-70% by weight of 2- propanol; and about 2-4% by weight of distilled water.
11. A process for preparing a silica-based temperable coating solution for applying with the sol-gel coating technique for off-line anti reflective coating applications, characterized in that it comprises the following process steps;
(i) supplying a solvent;
(ii) mixing by adding tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and methyltriethoxysilane (MTES) as another source of silica and pore to said solvent, wherein MTES/TEOS mole ratio is about 1 ,2 or less than 1 ,2; and
(iii) mixing by adding catalyst to the mixture obtained in step (ii).
12. A process according to claim 11 , wherein MTES/TEOS mole ratio in the coating solution is approximately equal to 1 ,2.
13. A process according to claims 11 or 12, wherein said solvent comprises a solvent mixture containing propylene glycol monomethyl ether acetate, ethanol, and 2- propanol in predetermined amounts.
14. A process according to claim 13, wherein the said solvent mixture comprises about 2- 5% by weight of propylene glycol monomethyl ether acetate, about 12-15% by weight of ethanol and about 70-80% by weight of 2-propanoL
15. A process according to any of claims 11 to 14, wherein said coating solution comprises about 77-80% by weight of the solvent mixture.
16. A process according to any of claims 11 to 15, wherein said catalyst comprises at least one organic acid selected from acetic acid, glacial acetic acid, formic acid, ascorbic acid, citric acid, and at least one inorganic acid selected from nitric acid, hydrochloric acid, and hydrofluoric acid.
17. A process according to claim 16, wherein said catalyst is acetic acid and said inorganic acid is nitric acid.
18. A process according to claim 17, wherein the ratio by weight of said acetic acid is 1 - 3% and the ratio by weight of said nitric acid is 0-0,1%.
19. A process according to any of claims 11 to 18, wherein said coating solution comprises about 2-4% by weight of distilled water.
20. A process according to any of claims 11 to 18, wherein the said coating solution comprises about 8-10% by weight of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica; about 8-10% by weight of methyl triethoxysilane (MTES) as another source of silica and pore; about 1-3% by weight of glacial acetic acid and about 0,0-0, 1% by weight of nitric acid as catalyst; about 2-3% by weight of propylene glycol monomethyl ether acetate as a solvent, about 9-15% by weight of ethanol and about 60-70% by weight of 2-propanol; and about 2-4% by weight of distilled water.
21. A use of a composition comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another source of silica and pore as a sol-gel coating solution, characterized in that MTES/TEOS mole ratio in said coating solution is approximately equal to or less than 1 ,2.
22. A method for coating a glass article with an antireflective thin film for off-line antireflective applications, characterized in that it comprises the following process steps;
(a) preparing a silica-based temperable coating solution, wherein the said coating solution comprises a predetermined amount of tetraethylorthosilicate (TEOS) as a hydrolyzable silica source and a predetermined amount of methyl triethoxysilane (MTES) as another silica and pore source, wherein MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2;
(b) supplying a glass product; and
(c) coating the said glass product with the said coating solution.
23. A method according to claim 22, wherein MTES/TEOS mole ratio in the coating solution is approximately equal to 1 ,2.
17
24. A method according to claims 22 or 23, wherein said coating solution comprises a solvent mixture containing propylene glycol monomethyl ether acetate, ethanol, and 2-propanol in predetermined amounts as solvents.
25. A method according to claim 24, wherein the said solvent mixture comprises about 3- 5% by weight of propylene glycol monomethyl ether acetate, about 12-15% by weight of ethanol and about 70-80% by weight of 2-propanol.
26. A method according to any of claims 22 to 25, wherein said coating solution comprises about 77-80% by weight of the solvent mixture.
27. A method according to any of claims 22 to 26, wherein said coating solution comprises at least one organic acid selected from acetic acid, glacial acetic acid, formic acid, ascorbic acid, citric acid, and at least one organic acid selected from nitric acid, hydrochloric acid, and hydrofluoric acid as catalysts.
28. A method according to claim 27, wherein said organic acid is acetic acid and said inorganic acid is nitric acid.
29. A method according to claim 28, wherein the ratio by weight of said acetic acid is 1- 3% and the ratio by weight of said nitric acid is 0,0-0, 1%.
30. A method according to any of claims 22 to 29, wherein said coating solution comprises about 2, 0-4,0% by weight of distilled water.
31. A method according to any of claims 22 to 30, wherein the said coating solution comprises about 8-10% by weight of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica; about 8-10% by weight of methyl triethoxysilane (MTES) as another source of silica and pore; about 1-3% by weight of glacial acetic acid and about 0,0-0, 1% by weight of nitric acid as catalyst; about 2-5% by weight of propylene glycol monomethyl ether acetate as a solvent, about 9-15% by weight of ethanol and about 60-70% by weight of 2-propanol; and about 2-4% by weight of distilled water.
32. A method according to any of claims 22 to 31 , wherein said coating process is carried out by using the sol-gel roll coating technique.
18 A method according to any of claims 22 to 32, wherein said coating process is carried out as a single layer on a single surface. A glass article having an antireflective thin film coating, characterized in that the said thin film coating is obtained by coating the glass surface with a coating solution comprising a predetermined amount of tetraethylorthosilicate (TEOS) as a source of hydrolyzable silica and a predetermined amount of methyl triethoxysilane (MTES), as another source of silica and pore, wherein MTES/TEOS mole ratio in the coating solution is approximately equal to or less than 1 ,2. A glass article according to claim 34, wherein the coating process is carried out using the sol-gel roll coating technique. A glass article according to claim 33 or 35, wherein said coating process is carried out as a single layer on a single surface. A glass article according to any of claims 33 to 36, wherein it is a showcase glass, automotive glass, photovoltaic (FV) glass panel or solar panel cover glass.
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PCT/TR2021/051008 2020-12-01 2021-10-04 Anti-reflective silica based temperable coating solution WO2022132080A1 (en)

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EP1074526A2 (en) * 1999-08-06 2001-02-07 Centro De Investigaciones Energeticas Medioambientales Y Tecnologicas (C.I.E.M.A.T.) Method for the formation of an anti-reflective and leveling film on glass/TCO substrates
EP2808040A1 (en) * 2012-01-25 2014-12-03 Universitat Jaume I De Castellón Osteoinductive coatings for dental implants
WO2015040253A1 (en) * 2013-09-23 2015-03-26 Abengoa Solar New Technologies , S,A. Method for preparing a dielectric barrier layer of silicon oxide (siox) and a layer prepared in this manner
US20170121538A1 (en) * 2015-11-02 2017-05-04 Metashield, Llc Nanosilica based compositions, structures and apparatus incorporating same and related methods

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EP1074526A2 (en) * 1999-08-06 2001-02-07 Centro De Investigaciones Energeticas Medioambientales Y Tecnologicas (C.I.E.M.A.T.) Method for the formation of an anti-reflective and leveling film on glass/TCO substrates
EP2808040A1 (en) * 2012-01-25 2014-12-03 Universitat Jaume I De Castellón Osteoinductive coatings for dental implants
WO2015040253A1 (en) * 2013-09-23 2015-03-26 Abengoa Solar New Technologies , S,A. Method for preparing a dielectric barrier layer of silicon oxide (siox) and a layer prepared in this manner
US20170121538A1 (en) * 2015-11-02 2017-05-04 Metashield, Llc Nanosilica based compositions, structures and apparatus incorporating same and related methods

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