TWI648221B - Modified silica microparticle and method producing the same, coating solution for sorming thin film, substrate with thin film and photoelectronic cell - Google Patents

Abstract

In order to realize a functional film having high weather resistance, a film is formed using a coating liquid containing cerium oxide fine particles having an oligomer of a tetrafunctional organic sulfonium compound bonded to the surface. Here, the oligomer is in a form having a molecular weight of 1,000 to 10,000 and a monomer bond. The cerium oxide fine particles having an oligomer of a tetrafunctional organic cerium compound bonded to the surface thereof have high acid resistance, and the film containing the fine particles is dense and has high weather resistance. Further, a tetrafunctional organic ruthenium compound is used for the binder component of the coating liquid. The organic ruthenium compound constituting the oligomer and the organic ruthenium compound of the binder component may be the same compound or different compounds. In particular, an antireflection film can be produced by using fine particles having a low refractive index such as cerium oxide hollow fine particles.

Description

Modified cerium oxide microparticles, a method for producing the same, a coating liquid for film formation, a substrate with a film, and a photovoltaic cell

The present invention relates to a film provided on the surface of a substrate, a coating liquid for forming the film, and modified metal oxide fine particles contained in the coating liquid. The modified metal oxide fine particles of the present invention are in the form of a polymer in which an organic ruthenium compound is bonded to the surface of the metal oxide fine particles. In particular, there is a technique for forming an antireflection film by using cerium oxide hollow fine particles as metal oxide fine particles.

Since the past, various types of functional films have been provided on the substrate for the purpose. In order to visualize its function, functional thin films mostly contain metal oxide fine particles. For example, in order to prevent reflection on the surface of a transparent substrate such as glass, a plastic sheet, or a plastic lens, an anti-reflection film is provided on the surface of the substrate. As the antireflection film, a film composed of a binder containing cerium oxide hollow fine particles is used. That is, when the antireflection film is formed, low refractive index fine particles such as cerium oxide hollow fine particles are used as the metal oxide fine particles. child. Such an antireflection film is formed by applying a coating liquid containing cerium oxide hollow fine particles to the surface of a substrate. In addition, in order to improve the water resistance and water repellency of the antireflection film while maintaining the antireflection performance, the organic ruthenium compound having a hydrophobic group is oxidized in order to maintain the antireflection performance.矽 Hollow particles are surface treated.

Japanese Patent Publication No. 2003-298087 (Patent Document 2) discloses that a light-receiving surface of a solar cell unit is provided with a partial hydrolyzate containing hollow cerium oxide microparticles and a tetrafunctional hydrolyzable organic decane as an antireflection film. Coating film to reduce the loss of light due to surface reflection.

As described above, the antireflection film is often formed on the surface of the substrate. Therefore, for the antireflection film, not only antireflection properties but also scratch resistance, scratch resistance, water repellency, and the like are required. However, the antireflection film described in Patent Document 1 cannot obtain sufficient weather resistance. In particular, the solar cell system is installed outside the house, so it must withstand rain or wind, sand dust or temperature changes. Therefore, the antireflection film used in the solar cell unit requires high weather resistance. However, the antireflection film of Patent Document 1 cannot obtain sufficient weather resistance and cannot satisfy the reliability standard. This is not limited to the antireflection film, but is a common problem of a functional film containing metal oxide fine particles. That is, a film having a metal oxide fine particle form is present in the binder, and the weather resistance of the film is more reduced than the weather resistance of the binder monomer due to the presence of the metal oxide fine particles.

In order to improve the weather resistance of the functional film, the inventors of the present invention considered that it is necessary to make the film more dense. Then, it has been found that the metal oxide fine particles surface-treated with the oligomer of the tetrafunctional organic cerium compound have high acid resistance, and the film containing the metal oxide fine particles becomes denser than the conventional thin film.

Here, the modified metal oxide fine particles of the present invention are metal oxide fine particles in which an oligomer of a tetrafunctional organic germanium compound is bonded to the surface. The oligomer is a form in which a monomer of a tetrafunctional organic hydrazine compound is bonded, and the average molecular weight of the oligomer is in the range of 1,000 to 10,000. Here, the tetrafunctional organic sulfonium compound is represented by SiX ₄ (exclusive, X-based alkoxy group having 1 to 4 carbon atoms, hydroxyl group, halogen, hydrogen).

Further, the method for producing a modified metal oxide fine particle includes a step of preparing a fine particle dispersion containing metal oxide fine particles; and a step of preparing an oligomer dispersion by oligomerizing a tetrafunctional organic germanium compound in an acid atmosphere And a step of modifying the oligomer of the tetrafunctional organic sulfonium compound by removing the acid from the oligomer dispersion, adding the fine particle dispersion, and stirring the surface of the metal oxide fine particles. The oligomer is produced by bonding a monomer of a tetrafunctional organic hydrazine compound, and it can carry out in an acid environment. On the other hand, in order to bond the oligomer to the surface of the metal oxide fine particles, the acid can be removed to have a pH in the range of 5 to 7.

The coating liquid for film formation can be produced using the modified metal oxide fine particles. That is, the coating liquid according to the present invention is a surface-modified metal oxide fine particle in which an oligomer containing a tetrafunctional organic cerium compound is bonded to the surface of the metal oxide fine particle, and a binder component. Oligomer system The form in which the monomer of the tetrafunctional organic hydrazine compound is bonded has an average molecular weight of from 1,000 to 10,000. A 4-functional organic hydrazine compound is also suitable for the binder component. In this case, the organic ruthenium compound forming the oligomer (hereinafter, referred to as the first organic ruthenium compound) and the organic ruthenium compound (hereinafter referred to as the second organic ruthenium compound) contained in the binder component may be the same compound or different. compound of. The functional film formed by using such a coating liquid improves the weather resistance and reliability without impairing its function.

An antireflection film can be produced by using cerium oxide hollow fine particles as metal oxide fine particles. That is, the modified cerium oxide hollow fine particles in which the oligomer of the tetrafunctional organic cerium compound is bonded to the surface of the cerium oxide hollow fine particles are produced. The coating liquid for forming an antireflection film is composed of the modified cerium oxide hollow fine particles and the binder component. The oligomer is a form in which a monomer of a tetrafunctional organic hydrazine compound is bonded, and an average molecular weight of the oligomer is in the range of 1,000 to 10,000. The binder component is a tetrafunctional organic cerium compound (second organic cerium compound) which may be a different compound or the same compound as the 4-functional organic cerium compound (first organic cerium compound) forming the oligomer. By forming a film using such a coating liquid, an antireflection film having high weather resistance and high reliability can be realized.

Similarly, a hard coat film suitable for a front panel or the like of a display device can be realized by using cerium oxide fine particles as metal oxide fine particles.

The modified metal oxide fine particles on the surface of the metal oxide fine particles are modified by using an oligomer of a tetrafunctional organic germanium compound. The functional film can improve the weather resistance without impairing the functional properties of the functional film.

The present invention is based on the use of cerium oxide microparticles in metal oxide microparticles to achieve a functional film. The modified cerium oxide microparticles according to the present invention are composed of an oligomer having a tetrafunctional organic quinone compound bonded to the surface of the cerium oxide microparticles, and the average molecular weight of the oligomer is in the range of 1,000 to 10,000. Here, the oligomer is a form in which a monomer of a tetrafunctional organic hydrazine compound is bonded. The modified cerium oxide microparticles have high acid resistance, and the functional film containing the microparticles is excellent in weather resistance. Particularly preferred is an oligomer in which the monomer is in the form of a linear bond. Here, the tetrafunctional organic sulfonium compound is represented by SiX ₄ . However, X is any one of alkoxy groups having 1 to 4 carbon atoms, a hydroxyl group, a halogen, and hydrogen. Specifically, as the organic ruthenium compound, a tetrafunctional hydrolyzable organodecane can be exemplified. Compared with the tetrafunctional organic ruthenium compound, the bonding ability of the trifunctional or bifunctional organic ruthenium compound and the binder constituting the film is low, so that sufficient film hardness (pencil hardness, scratch resistance) cannot be obtained. Therefore, the organic ruthenium compound forming the oligomer is suitably a 4-functional one.

Next, a method of producing the modified cerium oxide microparticles will be described. First, a fine particle dispersion containing cerium oxide fine particles is produced. Further, a monomer solution containing a tetrafunctional organic hydrazine compound monomer is stirred under an acidic environment. Thereby, the monomer becomes an oligomer having an average molecular weight of 1,000 to 10,000, thereby producing an oligomer solution. Organic deuteration by making the monomer solution acidic The single system of the compound is linearly bonded to form an oligomer. It is particularly desirable that the pH of the monomer solution is from 0.5 to 3.0. The stronger the acidity, the larger the molecular weight of the oligomer becomes. Further, the temperature at the time of stirring is preferably from 20 to 100 ° C, and the time is preferably from 24 hours to 30 minutes. Since the molecular weight changes depending on the temperature and time, the stirring conditions can be appropriately set. Assuming that the monomer solution is stirred under an alkaline environment, the monomers are sterically bonded without becoming an oligomeric form desired in the present invention.

Next, the acid is removed from the oligomer solution, and the fine particle dispersion is added and stirred. Thereby, an oligomer of a tetrafunctional organic sulfonium compound is bonded to the surface of the cerium oxide microparticles to prepare the modified cerium oxide microparticles of the present invention. In order to bond the cerium oxide microparticles to the oligomer, it is necessary to remove the acid so that the pH of the oligomer dispersion is in the range of 5 to 7.

The removal of the acid may be carried out before the oligomer is bonded to the cerium oxide microparticles, and the acid may be removed from the solution to which the microparticle dispersion and the oligomer solution are added. In this case, the acid is removed by adding a mixed solution of the fine particle dispersion and the oligomer solution, and the surface of the cerium oxide microparticles is bonded with an oligomer of a tetrafunctional organic hydrazine compound. At this time, the acid is removed in such a manner that the pH of the mixed solution becomes in the range of 4 to 7.

Next, a coating liquid using the modified cerium oxide microparticles of the present invention will be described. According to the coating liquid of the present invention, a solution of the modified cerium oxide microparticles and a binder component is added to a solvent. To this solution, a trace amount of an acid (inorganic acid or organic acid) as a catalyst is added. The oligomer of the modified cerium oxide microparticle-based tetrafunctional organic cerium compound is bonded to the surface of the cerium oxide microparticles, and the average molecular weight of the oligomer is from 1,000 to 10,000. form The tetrafunctional organofluorene compound of the oligomer may, for example, be tetramethoxydecane, tetraethoxydecane, tetraisopropoxydecane, tetrabutoxydecane or tetrachlorodecane.

On the other hand, a tetrafunctional organic ruthenium compound is also used in the binder component. In order to improve the pencil hardness and the scratch resistance of the film formed from the coating liquid, a tetrafunctional organic ruthenium compound is suitably used for the binder component. In order to facilitate dispersion and bonding in the binder component, the oligomer is suitably formed by the formation of a tetrafunctional organic oxime. Here, the tetrafunctional organofluorene compound used in the oligomeric tetrafunctional organic hydrazine compound and the binder component may be a different compound or the same compound. Further, not only a tetrafunctional organic ruthenium compound but also a trifunctional organic ruthenium compound may be added to the binder component. By adding a trifunctional organic sulfonium compound having a fluorine group (for example, trifluoropropyltrimethoxydecane, etc.), the scratch resistance, antifouling property, and water repellency of the film are improved. Thus, a trifunctional organic ruthenium compound can be added to impart additional function to the film. The functional group held by the trifunctional organic hydrazine compound can be appropriately selected depending on the function to be attached. However, the presence of a trifunctional organic ruthenium compound leads to a decrease in bonding property, and it is not appropriate to add a large amount of a trifunctional organic ruthenium compound. The ratio of the tetrafunctional organic cerium compound to the trifunctional organic cerium compound is preferably 99.5:0.5 to 90:10 in terms of molar ratio. When the trifunctional organic cerium compound is less than 99.5:0.5, it becomes difficult to obtain the target additional function, When the temperature is 90:10, the hardness of the obtained coating film becomes insufficient.

The trifunctional organic hydrazine compound can be exemplified by vinyl trimethoxy decane, 3-epoxypropyloxypropyl trimethoxy decane, p-styryl trimethoxy decane, 3-methyl propylene methoxy propyl trimethyl Oxydecane, 3- Aminopropyltrimethoxydecane, 3-isocyanatepropyltriethoxydecane, 3-mercaptopropyltriethoxydecane, phenyltriethoxydecane, and the like.

A coating liquid containing the modified cerium oxide microparticles is applied to the surface of the substrate to be cured, whereby a functional film having high weather resistance can be formed. The coating method may, for example, be a dip coating method, a spray coating method, a spin coating method, a roll coating method, a bar coating method, a slit coating printing method, a gravure printing method, a micro gravure printing method, or the like. The coating method is selected depending on the application site and the desired film thickness. The type of the solvent or the solid content concentration of the coating liquid is appropriately adjusted in accordance with the coating method. After coating, drying and firing treatment are performed to form a functional film on the substrate. The functional film contains cerium oxide microparticles having an oligomer bonded to the surface, that is, modified cerium oxide microparticles. As described above, the oligomer is preferably a form in which a monomer of a tetrafunctional organic hydrazine compound is linearly bonded, and an average molecular weight thereof is in the range of 1,000 to 10,000. The functional film preferably contains 20 to 95% by mass of the modified cerium oxide microparticles.

The functional film applicable to the technology can be a high processing film, a low dielectric film, and a heat break. A heat shielding film, an antireflection film, a reflective film, a transparent conductive film, a hard coat film, or the like. Further, in the antireflection film, cerium oxide hollow fine particles in the cerium oxide microparticles can be used. Here, the cerium oxide hollow fine particle sub-shell has fine particles inside the outer shell, and the void ratio (the proportion of the hollow of the particles) is 10% by volume or more and 80% by volume or less. Usually, the cavity is filled with gas. Further, the void ratio can be measured by observing the outer diameter of the particle and the cavity portion from the image photographed by the TEM. In the present invention, the average particle diameter of the cerium oxide hollow fine particles is suitably from 10 to 300 nm. Further, the cerium oxide hollow fine particles may contain a compound other than cerium oxide as an impurity, for example, Al ₂ O ₃ or Na ₂ O. In the present invention, those containing 95% by weight or more of the cerium oxide component are cerium oxide hollow fine particles.

Hereinafter, an antireflection film using cerium oxide hollow fine particles (hereinafter simply referred to as hollow fine particles) will be described in detail. The hollow fine particles have characteristics such as light weight, low refractive index, low dielectric constant, high heat-breaking property, and good workability as compared with solid fine particles, and are fine particles suitable for forming an anti-reflection film. In particular, the antireflection film of the modified hollow microparticles in which the oligomer of the tetrafunctional organic sulfonium compound is bonded to the surface of the hollow microparticles has high weather resistance. The oligomer preferably has an organic germanium compound monomer to form a linear bond, and has an average molecular weight of suitably from 1,000 to 10,000. The modified fine particles thus have high acid resistance, and the film system containing the modified hollow fine particles becomes dense. At this time, the surface of the hollow fine particles is bonded with an oligomer of 3 to 90% by weight based on the weight of the hollow fine particles. When used as an antireflection film, the film thickness is preferably from 80 to 120 nm or from 180 to 220 nm. When the detachment is outside the range, sufficient anti-reflection effect cannot be obtained.

Next, a coating liquid containing modified hollow fine particles will be described. The coating liquid for forming an antireflection film is a solution in which the modified hollow fine particles and the binder component are added to a solvent. A trace amount of acid is added to the solution as a catalyst. The modified hollow microparticles are hollow microparticles bonded to the surface of the oligomer of the tetrafunctional organic germanium compound, and the average molecular weight of the oligomer is in the range of 1,000 to 10,000. The binder component is a tetrafunctional organic ruthenium compound.

At this time, the solid content concentration of the coating liquid is preferably from 0.5 to 10%. When it is 0.5% or less, it is not only easy to cause an appearance of the antireflection film, but also difficult to make The film thickness is uniform, the productivity is low, and it becomes non-useful. When it is 10% or more, it is difficult to obtain a film having a desired film thickness, and the coating film is likely to be cracked.

The solid fraction of the coating liquid modifies the total sum of the hollow fine particles and the binder component. The solid content ratio of the modified hollow microparticles to the binder component is suitably from 95:5 to 20:80. When the ratio of the hollow fine particles is larger than 95:5, the hardness of the obtained film is weak, and when 20:80 hours is used, when the antireflection film is used, the refractive index of the obtained film is insufficient, and desired antireflection performance cannot be obtained.

The above anti-reflection film can be applied to a photovoltaic cell. In other words, the coating liquid for forming an antireflection film is applied onto a transparent substrate, and drying treatment and firing treatment are performed. The transparent substrate is placed on the light incident surface side of the photovoltaic cell. As the transparent substrate, a protective substrate for a photovoltaic cell can be used, and an electrode and a photoelectric conversion element can be formed on the other surface of the transparent substrate, and a substrate constituting the photovoltaic cell can be used.

Hereinafter, an embodiment of the antireflection film will be described in detail.

(Example 1)

In the present embodiment, the modified hollow fine particles, the method for producing the same, the coating liquid, and the antireflection film will be described in order. The modified hollow fine particles of this example are composed of an oligomer of tetraethoxysilane which is bonded to the surface of the hollow fine particles, and the average molecular weight of the oligomer is 1,500.

Hereinafter, a method of producing the modified hollow fine particles will be described in detail.

[Manufacturing procedure of hollow microparticles]

First, hollow fine particles are produced. To 10 g of cerium oxide sol (manufactured by Nippon Chemical Co., Ltd.: CATALOID SI-550, average particle diameter: 5 nm, SiO ₂ concentration: 20% by mass), 390 g of pure water was added, and the mixture was heated to 80 °C. The solution was kept at 80 ° C, and 8500 g of a sodium citrate aqueous solution having a concentration of SiO ₂ of 1.5% by mass and 8500 g of an aqueous sodium aluminate solution having a concentration of 0.5% by mass of Al ₂ O _{3 were} added to the solution for 24 hours. Thereby, an aqueous dispersion of the composite oxide fine particles (1) was produced. At this time, the average particle diameter of the composite oxide fine particles (1) was measured by a laser scattering method to be 40 nm.

In the aqueous dispersion of the composite oxide fine particles (1), 27,000 g of a sodium citrate aqueous solution having a concentration of SiO ₂ of 1.5% by mass and an alumina acid having a concentration of 0.5% by mass of Al ₂ O _{3 were} added over 50 hours. 9000 g of a sodium aqueous solution was used to prepare an aqueous dispersion of the composite oxide fine particles (2). At this time, the composite scattering fine particle diameter of the composite oxide fine particles (2) was 60 nm. The pH was 12.5 and the solids concentration was 1.2%. An ultrafiltration membrane was added to the aqueous dispersion of the composite oxide fine particles (2) while using an ultrafiltration membrane, and the mixture was washed until the pH was 10.0, and then concentrated until the solid content concentration was 13% by mass. As a result, an aqueous dispersion of the composite oxide fine particles (3) was obtained. At this time, the laser oxide average particle diameter of the composite oxide fine particles (3) was 59 nm.

Hollow fine particles are produced from the aqueous dispersion of the composite oxide fine particles (3). 1125 g of pure water was added to 500 g of the aqueous dispersion of the composite oxide fine particles (3) having a solid content concentration of 13% by mass. Further, concentrated hydrochloric acid (concentration: 35.5 mass%) was added dropwise to adjust the pH to 1.0. Next, while adding 10L of hydrochloric acid aqueous solution of pH2 and 5L of pure water, it is separated by ultrafiltration membrane. Wash and dissolve the aluminum salt. Thereby, an aqueous dispersion of the hollow fine particles (1) was obtained. The aqueous dispersion had a solid content concentration of 20% by mass and a pH of 3.

Further, aqueous ammonia was added to the aqueous dispersion of the hollow fine particles (1) so that the pH became 12.0. Next, the aqueous dispersion was stirred at 200 ° C for 45 hours, and the temperature was lowered to 25 ° C. Then, 400 g of a cation exchange resin (manufactured by Mitsubishi Chemical Corporation: DIAION SK1BH) was added and stirred for 3 hours. Then, the cation exchange resin was separated and adjusted to 25 °C. Then, 200 g of an anion exchange resin (manufactured by Mitsubishi Chemical Corporation: DIAION SA20A) was added, and the mixture was stirred at 25 ° C for 3 hours. Then, the anion exchange resin was separated to obtain an aqueous dispersion of hollow fine particles (2) having a solid concentration of 20% by mass.

Next, an ultrafiltration membrane was used, and the solvent of the aqueous dispersion was replaced with ethanol to obtain an alcohol dispersion of hollow fine particles (2) having a solid content concentration of 20% by mass.

[Production Step of Surface Modification Oligomer Solution]

Next, an oligomer solution for modifying the surface of the hollow fine particles (2) was produced. A solution of 240 g of pure water and 32 g of 61% by mass of nitric acid was added to 1478 g of ethanol to adjust to 25 °C. Next, 250 g of tetraethoxy decane (ETHYLSILICATE-40, manufactured by Tama Chemical Co., Ltd.) as a tetrafunctional organic ruthenium compound was slowly added to the solution, and the mixture was stirred at 50 ° C for 60 minutes. Thereby, the monomers of tetraethoxydecane are condensed by hydrolysis to form an oligomer. At this time, the single system is linearly bonded. The pH of the solution at this time was 1.9.

After the solution was brought to 25 ° C, 50 g of an amphoteric ion exchange resin (manufactured by Rohm and Haas Company: DUOLITE UP-7000) was added. After the solution was stirred for 1 hour, the ion exchange resin was separated. The acid of the solution is removed by ion exchange. Thus, an oligomer solution for surface modification was obtained. at this time, The pH of the oligomer solution was 5.5, and the average molecular weight of the oligomer measured by GPC was about 1,500. Further, when the solvent of the oligomer solution was evaporated at 1000 ° C, the concentration of the solid residue was 5% by mass.

[Steps for making modified hollow microparticles]

500 g of the oligomer solution for surface modification having a solid content of 5 mass% was prepared, and 500 g of an alcohol dispersion liquid of 20% by mass of the hollow fine particles (2) was added thereto, and the mixture was stirred at 50 ° C for 19 hours. At this time, the acid must be removed from the oligomer solution to adjust the pH to a range of 5 to 7. Therefore, prior to this step, it is desirable to carry out an acid removal treatment, for example, ion exchange. Thus, an oligomer of tetraethoxysilane is bonded to the surface of the hollow fine particles to obtain an alcohol dispersion of the modified hollow fine particles. At this time, the weight ratio (Wor/Wpa) of the solid content (Wor) of the oligomer to the solid content (Wpa) of the hollow fine particles is 5 to 100%, and the oligomer solution for hollow surface modification and the hollow are mixed. An alcohol dispersion of the microparticles (2). Even if it is mixed in such a ratio, it does not mean that all the oligomers are bonded to the hollow fine particles in this step, but the hollow fine particles are bonded to the oligomer corresponding to the weight of the hollow fine particles by 3 to 90% by weight. . Here, the hollow microparticles are mixed in such a manner that the solid content of the oligomer relative to the solid content of the hollow microparticles is 25% (500 g*5%) / (500 g * 20%) = 1/4 = 25%) Alcohol dispersion and oligomer solution.

By such a production method, modified hollow fine particles of an oligomer having a tetrafunctional organic sulfonium compound bonded to the surface of the hollow fine particles are obtained.

The acid resistance of the modified hollow microparticles can be evaluated in the following manner. Diluting the alcohol dispersion of the modified hollow microparticles with ethanol, adjusting the modification The concentration of the hollow fine particles was 0.3% by mass. 0.16 g of 6.1% by mass of nitric acid was added to 100 g of the 0.3% by mass alcohol dispersion, and the mixture was stirred at 25° C. for 1 minute, and the average particle diameter after the measurement and after 3 hours. After 1 minute, it was 65 nm, and after 3 hours, it was 66 nm. When the acid resistance of the modified hollow fine particles is high, the average particle diameter does not change with time. When the average molecular weight of the oligomer bonded to the hollow fine particles is from 1,000 to 10,000, the modified hollow fine particles have high acid resistance. The film containing such modified hollow microparticles is dense and has high weather resistance.

Next, a coating liquid for forming an antireflection film containing the modified hollow fine particles was produced.

[Production Step of Coating Liquid]

The coating liquid is produced by adding the alcohol dispersion of the modified hollow fine particles to a binder solution. First, the solvent of the binder solution is prepared. To 104.4 g of the reformed alcohol, 59.9 g of pure water and 0.99 g of 61% nitric acid were added and stirred at 25 ° C for 15 minutes. Next, 34.8 g of tetraethoxy decane (manufactured by Tama Chemical Co., Ltd.: ES-28) as a binder component was added to the solvent over 1 minute. It was stirred at 30 ° C for 3 hours. It was then cooled to 20 °C. Thereby a binder solution is obtained. Here, solmix AP-11 (manufactured by Nippon Alcohol Co., Ltd.) was used for the modified alcohol. Next, 74.7 g of an alcohol dispersion of 20% by mass of the modified hollow fine particles was added to 200.0 g of the binder solution. At this time, 549.4 g of a modified alcohol was also added as a solvent of the coating liquid. The solution thus obtained was stirred at 25 ° C for 3 hours to obtain a coating liquid for an antireflection film.

[Steps for making anti-reflection film]

Next, an antireflection film was produced from the coating liquid. The coating liquid was applied to a glass substrate by a bar coating method (#4) (FL glass manufactured by Binxin Co., Ltd.) (thickness 3 mm, refractive index 1.51, haze 0.1%, total light transmittance 92.0%). After drying at 80 ° C for 2 minutes, it was heated at 500 ° C for 30 minutes. The coating liquid is hardened into a low refractive index layer and functions as an antireflection film. Thus, an antireflection film was formed on the glass substrate. At this time, the average thickness of the antireflection film was 100 nm.

[Evaluation of anti-reflection film]

The performance of the antireflection film thus produced was evaluated. The refractive index, reflectance, haze, transmittance, scratch resistance, and contact angle were measured as initial characteristics. The refractive index was measured using a reflection spectroscopic film thickness meter (manufactured by Otsuka Electronics Co., Ltd.: FE-3000), and the transmittance and haze were measured using a haze meter (manufactured by SUGA Testing Co., Ltd.), and the reflectance was measured by spectrophotometry. The meter (manufactured by JASCO Corporation: Ubest-55) was measured. The measurement results were a refractive index of 1.33, a reflectance of 0.6%, a haze of 0.1%, and a transmittance of 95.4%. The reliability test (thermal cycle test, high temperature and high humidity test) was further carried out, and the reflectance, haze, transmittance, and scratch resistance after the test were measured. The thermal cycle test was carried out in a state where the antireflection film was allowed to stand, and was subjected to an environment of -20 ° C for 3 hours, followed by an environment of 80 ° C for 3 hours as 1 cycle, and repeated for 120 cycles. The high-temperature and high-humidity test was carried out by allowing the anti-reflection film to stand still and exposed to an environment of 85 ° C humidity of 85% for 1000 hours. After performing the above reliability test, the scratch resistance, total light transmittance, haze, and reflectance of the antireflection film were measured. The evaluation of the scratch resistance was carried out in the following manner. The film was slid 10 times under a load of 2 kg/cm ² , and the surface of the film was visually observed and evaluated by the following criteria.

No rib-like scars were confirmed: ◎

A small amount of rib-like scars were confirmed: ○

A large number of scars were confirmed to the ribs: △

The facial system is cut off as a whole: ×

[Evaluation of sample]

The coating liquid was prepared by changing the production conditions of the modified hollow fine particles, and the performance of the antireflection film obtained from the coating liquid was evaluated. Table 1 shows the results of this evaluation.

The sample 1 in the table corresponds to Example 1. Here, the binder of the coating was a tetraethoxy decane of a tetrafunctional organic hydrazine compound, and the weight ratio of the modified hollow microparticles to the tetraethoxy decane of the binder was set to 60:40. Using this coating material, an antireflection film having a thickness of 100 nm was formed on a glass substrate.

Sample 2 was lower in pH, higher temperature, and longer than the oligomerization conditions of Sample 1, and the average molecular weight of the oligomer was larger than that of Sample 1. Sample 3 differs from Sample 2 in that the oligomer is composed of tetramethoxynonane. The average molecular weight of the oligomer of the sample 3 was larger than that of the sample 2. The modified hollow fine particles used in the sample 4 are obtained by mixing a dispersion of hollow fine particles and an oligomer, and then removing the acid to bond the oligomer to the hollow fine particles. The sample 5 was different from the sample 1 in that the solid content (i.e., the solid content ratio) of the oligomer relative to the solid content of the hollow fine particles was increased to 70%. Conversely, sample 6 reduced the solid component ratio by 10%. Since the amount of the oligomer was small, the same performance as the other samples could not be obtained, but the deterioration was small after the reliability test.

Comparative Sample 1 used a coating film of hollow fine particles whose surface was not bonded with an organic cerium compound. The hollow fine particles used herein were added to 100 g of an alcohol dispersion of the hollow fine particles (2) diluted with ethanol to 0.3% by mass, and 0.16 g of 6.1% by mass of nitric acid was added thereto, followed by stirring at 25 ° C for 1 minute. At this time, the particle diameter of the hollow fine particles was 89 nm, but the particle diameter after 3 hours was 5097 nm. The film formed by the coating liquid containing such hollow fine particles had low initial scratch resistance and deteriorated reflectance and haze after the reliability test.

In Comparative Sample 2, a coating film of hollow fine particles in which a monomer of an organic ruthenium compound was bonded to the surface was used. It is known from reliability tests that its performance is degraded. The hollow microparticles used herein are produced in the following manner. 34.7 g of tetraethoxy decane was added to 500 g of the alcohol dispersion liquid of the hollow fine particles (2) of the above-mentioned 20 mass%, and the mixture was aged at 50 ° C for 19 hours to prepare an alcohol dispersion liquid of hollow fine particles (3). To 100 g of the alcohol dispersion liquid of the hollow fine particles (3) of 0.3% by mass obtained by diluting with ethanol, 0.16 g of 6.1% by mass of nitric acid was added, and the mixture was stirred at 25 ° C for 1 minute. The hollow fine particles thus obtained had a particle diameter of 75 nm, and the particle diameter after 3 hours was 351 nm. When hollow fine particles having a large particle size were used for the film, the reliability of the film was found to be low.

The antireflection film in which the average molecular weight of the oligomers bonded in the hollow crystal microparticles of the sample 3 was increased to 12,000 was compared. In order to increase the average molecular weight, the oligomerization conditions were set to a high temperature compared with the sample 1. The pH is also adjusted over a long period of time. According to the reliability test, the deterioration was small, but the scratch resistance was low from the initial stage.

Next, the performance of the antireflection film obtained from the coating liquid was evaluated when the trifunctional organic ruthenium compound was added to the binder component of the coating liquid without changing the production conditions of the modified hollow fine particles. Specifically, the amount of addition of the trifunctional organic sulfonium compound and the amount ratio of the hollow fine particles to the binder component are changed to prepare a coating liquid. An antireflection film having a thickness of 100 nm was formed on the glass substrate using the coating liquid. The evaluation results are shown in Table 2.

The hollow microparticles of the samples 7 to 10 were the same as the sample 1, and the oligomer of tetraethoxynonane was bonded to the surface, thereby modifying the surface. That is, the modified hollow fine particle system was produced in the same manner as the sample 1. On the other hand, the comparative sample 4 is a hollow fine particle in which a tetraethoxysilane monomer is bonded to the surface of the hollow fine particle. The coating liquid used for the preparation of each sample contains tetraethoxy decane which is a tetrafunctional organic hydrazine compound and trifluoropropyl trimethoxy decane which belongs to a trifunctional organic hydrazine compound as a binder component, as described in the table. The mixing ratio is mixed. The weight ratio of the binder component to the hollow fine particles was also mixed in the ratios in the table. The coating liquid forming the sample 7 was a binder component in which 99:1 was mixed with tetraethoxysilane and trifluoropropyltrimethoxydecane, and the binder component and the hollow fine particles were contained in a ratio of 60:40. The sample 8 was different from the sample 7 in that the tetraethoxy decane and the trifluoropropyltrimethoxy decane were mixed at 95:5. The sample 9 was different from the sample 7 in that the binder component and the hollow fine particles were contained in a ratio of 80:20. The sample 10 was different from the sample 7 in that the binder component and the hollow fine particles were contained in a ratio of 30:70. In the sample 9, since the amount of the binder was small, the initial scratch resistance was low, but there was almost no change after the reliability test. Comparative sample 4 showed good initial performance, but its performance was reduced after the reliability test.

(Example 2)

Here, the case where the antireflection film of Example 1 is applied to a photovoltaic cell will be described. The photovoltaic cell is provided with an antireflection film on the light incident side of the photoelectric conversion layer in such a manner as to efficiently transmit light to the photoelectric conversion layer.

[Photocell]

The photovoltaic cell of the embodiment has a transparent surface formed with a transparent electrode The substrate is provided with an electrolyte as a photoelectric conversion layer between the opposite substrates on which the counter electrode is formed. A metal oxide semiconductor film that adsorbs a light sensitizing material is formed on the surface of the transparent electrode.

The surface on one side of the transparent substrate forms a transparent electrode, and the surface on the other side is provided with an anti-reflection film. The antireflection film is formed to be located outside the photovoltaic cell. That is, the anti-reflection film is provided on the outermost surface (outermost surface) of the photovoltaic cell. When the substrate is disposed outside the photovoltaic cell, an antireflection film may be disposed on the outermost surface of the substrate. Alternatively, an anti-reflection film may be provided on both sides of the substrate.

It is preferable that the transparent substrate and the transparent electrode have a high visible light transmittance, specifically, 50% or more, and particularly preferably 90% or more. When the visible light transmittance is less than 50%, the photoelectric conversion efficiency becomes low. The resistance values of the transparent electrode and the counter electrode are preferably 100 Ω/cm 2 or less, respectively. When the resistance value of the electrode is high, the photoelectric conversion efficiency becomes low.

As the transparent substrate, a transparent and insulating substrate such as a glass substrate or an organic polymer substrate such as PET can be used. In addition, as long as the counter substrate has strength to withstand use, a conductive substrate such as metal titanium, metal aluminum, metal copper, or metal nickel may be used in addition to an insulating substrate such as a glass substrate or an organic polymer substrate such as PET.

As the transparent electrode, tin oxide, tin oxide doped with Sb, F or P, and an electrode material such as indium oxide doped with at least one of Sn and F may be used. Such a transparent electrode can be formed by a method such as thermal decomposition or CVD.

In addition, the opposite electrode system formed on the opposite substrate is used. A material that has the ability to reduce catalyst. Such an electrode material can be directly applied to a counter substrate, plated, or vapor-deposited to form a counter electrode. Alternatively, the electrode material used for the transparent electrode may be formed on the opposite substrate as a conductive layer by thermal decomposition or CVD, and the electrode material having the reducing catalyst capability may be disposed on the conductive layer by plating or evaporation. As a counter electrode.

The metal oxide semiconductor film may contain at least one metal oxide selected from the group consisting of titanium oxide, cerium oxide, zirconium oxide, cerium oxide, tungsten oxide, cerium oxide, zinc oxide, tin oxide, and indium oxide. The film thickness of the metal oxide semiconductor film is preferably in the range of 0.1 to 50 μm. Further, the metal oxide semiconductor film can be formed on the counter electrode of the counter substrate.

Here, the metal oxide-based spherical particles preferably have an average particle diameter in the range of 1 to 600 nm. Further, the particle diameter of the spherical particles can be measured by a laser Doppler particle size measuring machine (manufactured by Nikkiso Co., Ltd.: Microtrac). When the average particle diameter of the spherical particles is less than 1 nm, the formed metal oxide semiconductor film is liable to be cracked, and it is difficult to form a thick film having no cracks by a small number of times, and further, the pore diameter and fineness of the metal oxide semiconductor film are small. The pore volume is reduced, and the amount of adsorption of the light-sensitizing material is also reduced. Further, when the average particle diameter of the spherical particles exceeds 600 nm, the strength of the metal oxide semiconductor film is insufficient.

Such spherical particles are preferably crystalline titanium oxide. In particular, at least one selected from the group consisting of anatase-type titanium oxide, brookite-type titanium oxide, and rutile-type titanium oxide is preferable. The crystalline titanium oxide has a high energy gap and a high dielectric constant, and has higher adsorption capacity than other metal oxide particles, and has stability and stability. Excellent properties such as safety and easy film formation.

Claims (15)

An improved cerium oxide microparticle comprising an oxidized cerium microparticle and an oligomer of a tetrafunctional organic cerium compound bonded to a surface of the cerium oxide microparticle, wherein the oligomer is a monomeric bond of the tetrafunctional organogermanium compound In the form of a linear form, the average molecular weight of the aforementioned oligomer is in the range of 1,000 to 10,000. The modified cerium oxide microparticles according to claim 1, wherein the cerium oxide microparticles are cerium oxide hollow microparticles. The modified cerium oxide microparticles according to claim 2, wherein the weight of the oligomer bonded to the surface of the cerium oxide hollow microparticles is 3 to 90% by weight of the cerium oxide hollow microparticles. The modified cerium oxide microparticles according to any one of claims 1 to 3, wherein the organogermanium compound is represented by SiX ₄ , and the X-based alkoxy group having 1 to 4 carbon atoms, a hydroxyl group, Halogen, hydrogen. The modified cerium oxide microparticles according to claim 4, wherein the organogermanium compound is a tetrafunctional hydrolyzable organodecane. A method for producing modified cerium oxide microparticles, comprising the steps of: preparing a cerium oxide dispersion containing cerium oxide microparticles; and preparing a oligomer solution for oligomerizing a tetrafunctional organic cerium compound in an acid environment; Removing the acid from the aforementioned oligomer solution to adjust the pH of the oligomer solution a modification step of adding the foregoing cerium oxide dispersion and stirring to bond the oligomer of the above-mentioned tetrafunctional organic cerium compound to the surface of the cerium oxide microparticles in the range of 5 to 7, wherein the average molecular weight of the oligomer is A range of 1000 to 10,000. The method for producing modified cerium oxide microparticles according to claim 6, wherein the modifying step is a step of agitating the acid from the solution in which the cerium oxide dispersion and the oligomer solution are added. The method for producing modified cerium oxide microparticles according to claim 7, wherein in the modifying step, the pH of the solution is in the range of 4 to 7 by removing the acid. The method for producing modified cerium oxide microparticles according to any one of claims 6 to 8, wherein the cerium oxide microparticles are cerium oxide hollow fine particles. A coating liquid for forming a thin film comprising a coating liquid of modified cerium oxide fine particles and a binder component obtained by bonding an oligomer of a tetrafunctional first organic cerium compound to a surface of cerium oxide fine particles, the oligomer The monomer of the first organic ruthenium compound is bonded in a linear form, the average molecular weight of the oligomer is in the range of 1,000 to 10,000, and the binder component contains a tetrafunctional second organic ruthenium compound. The coating liquid for film formation according to claim 10, wherein the cerium oxide microparticles are cerium oxide hollow fine particles. The coating liquid for film formation according to claim 10, wherein the binder component further contains a trifunctional organic ruthenium compound. A film-attached substrate is provided with a film formed on the surface of the coating liquid according to any one of claims 10 to 12. The film-attached substrate according to claim 13, wherein the film has a thickness of any one of 80 to 120 nm or 180 to 220 nm. A photovoltaic cell comprising a transparent substrate having a film formed by the coating liquid according to any one of claims 10 to 12, wherein the film functions as an antireflection film.