JP5766251B2 - Method for producing a coating for forming a transparent film - Google Patents

Description

  The present invention relates to a substrate with a transparent coating excellent in antireflection performance, strength, scratch resistance, and the like, and a coating material for forming the transparent coating.

  Conventionally, in order to prevent reflection of the surface of a substrate such as glass, plastic sheet, plastic lens, etc., it is known to form an antireflection film on the surface, for example, by coating method, vapor deposition method, CVD method, etc. A coating of a low refractive index substance such as fluororesin or magnesium fluoride is formed on the surface of a glass or plastic substrate, or a coating liquid containing low refractive index fine particles such as silica fine particles is applied to the surface of the substrate. A method for forming an antireflection coating is known (for example, see JP-A-7-133105). At this time, in order to improve the antireflection performance, it is also known to form a high refractive index film containing fine particles of high refractive index under the antireflection coating.

  The applicant of the present invention disclosed in Japanese Patent Application Laid-Open No. 2001-23611 (Patent Document 1) is a method for producing silica-based fine particles having cavities therein and the resulting silica-based fine particles have a low refractive index and are formed using the silica-based fine particles. It is disclosed that the transparent film has a low refractive index and excellent antireflection performance.

  Furthermore, Japanese Patent Application Laid-Open No. 2002-79616 (Patent Document 2) discloses that when such a transparent coating is formed and used on the entire surface of a display device, the antireflection performance is excellent and the display performance is improved.

JP 2001-23611 A JP 2002-79616 A

  However, the silica-based fine particles disclosed in Patent Document 1 have a wide particle size distribution, and if the particle size is small, the ratio of the shell is high, and the ratio of the internal cavities is low. When the particle size is large, the ratio of the shell is decreased and the ratio of the internal cavity is increased, so that the refractive index is decreased, but the particle strength tends to be decreased.

For this reason, a transparent film using silica-based fine particles having a small average particle diameter may not have a sufficiently low refractive index and may have insufficient antireflection performance.
On the other hand, a transparent coating using silica-based fine particles having a large average particle size has a low refractive index and excellent antireflection performance, but the surface smoothness is lowered, and the strength and scratch resistance of the transparent coating are not sufficient. was there.

  In addition, the materials disclosed in Patent Documents 1 and 2 are a mixture of particles having a small particle size and particles having a large average particle size because of a wide particle size distribution. It was not satisfactory in terms of scratch resistance.

  Under such circumstances, as a result of intensive studies to solve the above problems, silica-based hollow fine particles not only have an average particle diameter in a specific range, but also have a small particle diameter variation coefficient (CV value). In order to complete the present invention, it is found that any of the above problems can be solved, an antireflection performance is excellent, a film surface is smooth, and a substrate with a transparent film excellent in scratch resistance is obtained. It came.

[1] A silica coating layer is formed on a composite oxide core fine particle having an average particle diameter of 19 to 70 nm composed of silica and an inorganic oxide other than silica so as to have a thickness of 1 to 10 nm. When removing the oxide and producing silica-based hollow particles having an average particle diameter (Dn) in the range of 20 to 80 nm and a refractive index in the range of 1.10 to 1.40, the following (1) to ( The particle diameter variation coefficient of the silica-based hollow fine particles is adjusted to be in the range of 1 to 50% by combining the methods of 6),
Next, a method for producing a coating material for forming a transparent film, comprising mixing the obtained silica-based hollow fine particles, a matrix-forming component, and a polar solvent;
(1) When composite oxide fine particles composed of silica and inorganic oxides other than silica are used as nuclei, use nuclei particles having a CV value of 100% or less of nuclei. (2) Core particles obtained by adding a silica source and an alumina source. (3) When a silica coating layer is formed, addition of a silica source is performed at a silica coating rate of 0.1 to 10 nm / hour. (4) After particle growth or silica coating layer formation, ripening is performed in a solid content concentration of 1 to 30% by weight, a temperature of 30 to 100 ° C., and a time of 1 to 12 hours. (5) Aggregation by irradiation with ultrasonic waves (6) Aggregated particles and coarse particles that are difficult to disperse are removed with a capsule filter.

[2] The concentration of the silica-based hollow fine particles in the paint is in the range of 0.1 to 32% by weight as the solid content, and the total solid content concentration including the matrix forming component is in the range of 0.5 to 40% by weight. [1] The method for producing a coating material for forming a transparent film according to [1].
[3] A transparent film comprising silica-based hollow fine particles and a matrix component is formed on a substrate by applying the transparent film-forming paint obtained by the method described in [1] or [2]. The manufacturing method of the base material with a transparent film characterized by these.
[4] The method for producing a substrate with a transparent coating according to [3], wherein the content of the silica-based hollow fine particles in the transparent coating is in the range of 20 to 80% by weight.
[5] The substrate with a transparent coating according to [3] or [4], wherein the thickness of the transparent coating is in the range of 30 nm to 300 nm and the refractive index is in the range of 1.25 to 1.50. .

  According to the present invention, the adhesion between the substrate and the transparent coating is high, and the upper surface of the transparent coating is smooth with small irregularities. For this reason, it is possible to form a transparent film having excellent strength and scratch resistance, low refractive index and excellent antireflection performance.

Hereinafter, first, the present invention will be specifically described.
[Base material with transparent coating]
The substrate with a transparent coating according to the present invention is formed by forming a transparent coating composed of silica-based hollow fine particles and a matrix component on the substrate.

As the base material , a conventionally known base material can be used. In addition to glass, cellulose base materials such as triacetyl cellulose film (TAC), diacetyl cellulose film, acetate butyrate cellulose film, polyethylene terephthalate (PET) ), Polyester base materials such as polyethylene naphthalate, polyolefin base materials such as polyethylene film, polypropylene film and cyclic polyolefin film, polyamide base materials such as nylon-6, nylon-66, polyacrylic film, polyurethane film , Polycarbonate film, polyether film, polyethersulfone film, polystyrene film, polymethylpentene film, polyetherketone film, acrylonitrile film, etc. And the like.
In addition, a coated substrate in which another coating such as a hard coat film is formed on such a substrate can also be used.

Silica-based hollow fine particles Silica-based hollow fine particles used in the present invention have an average particle diameter (Dn) of 20 to 80 nm, preferably 30 to 75 nm. The hollow fine particles are composed of a shell layer and an inner core portion, the shell layer is made of silica, and the inner core portion is filled with a liquid (such as a solvent or an aqueous silicic acid solution) or a gas.

  Since the shell cannot be made thinner than a certain thickness, if the average particle size is small, the proportion of cavities inside the particles will be small and the refractive index of the particles will be high. For this reason, a transparent film having a sufficiently low refractive index may not be obtained. When the average particle diameter is too large, the strength of the transparent film is insufficient due to the large particles, and the smoothness of the surface of the transparent film is lowered, and the scratch resistance may be insufficient.

The silica-based hollow fine particles preferably have a particle diameter variation coefficient (CV value) of 1 to 50%, more preferably 2 to 30%.
Those having a small particle size variation coefficient (CV value) are difficult to obtain and vary depending on the particle size, but even if obtained, the silica-based hollow microparticles are too uniform and cannot be packed densely so that they are transparent. In some cases, the strength of the coating film decreases or a transparent coating film having a sufficiently low refractive index cannot be obtained. Even if the particle diameter variation coefficient (CV value) is too large, the difference in the particle diameter of the silica-based hollow fine particles is so large that it cannot be densely packed, so that the strength of the transparent film is reduced or a transparent film having a sufficiently low refractive index is obtained. It may not be possible.

  The refractive index of the silica-based hollow fine particles is preferably in the range of 1.10 to 1.40, more preferably 1.10 to 1.35. It is difficult to make the refractive index of the silica-based hollow fine particles smaller than this range, and when the refractive index of the silica-based hollow fine particles is larger than this range, there is substantially no change from the silica fine particles, so that a transparent coating can be obtained. Has a high refractive index, resulting in insufficient antireflection performance.

  The thickness of the shell layer of the silica-based hollow fine particles varies depending on the particle diameter, but is usually in the range of 1 to 20 nm, preferably 2 to 15 nm. In the present invention, the ratio of the thickness of the shell layer to the average particle diameter (thickness / average particle diameter) is preferably 0.025 to 0.25. With such a thickness and ratio of the shell layer, the refractive index can be adjusted to the above range, and the strength of the particles themselves can be increased.

  The refractive index of the hollow fine particles can be adjusted by adjusting the ratio of the thickness of the shell layer to the average particle diameter (thickness / average particle diameter), and the refractive index increases as the ratio increases. If the ratio is reduced, the refractive index can be reduced.

The average particle diameter and the shell layer thickness of the silica-based hollow fine particles used in the present invention are obtained as an average value obtained by taking an electron micrograph and measuring the particle diameter of 100 arbitrary particles.
The refractive index of the silica-based hollow fine particles used in the present invention is measured by the following method.

(1) A dispersion of silica-based hollow fine particles is taken in an evaporator and the dispersion medium is evaporated.
(2) This is dried at 120 ° C. to obtain a powder.
(3) A standard refraction liquid having a known refractive index is dropped on a glass plate of a few drops, and the above powder is mixed therewith.
(4) The operation of (3) is performed with various standard refractive liquids, and the refractive index of the standard refractive liquid when the mixed liquid becomes transparent is set as the refractive index of the silica-based hollow fine particles.
The particle diameter variation coefficient (CV value) of the silica-based hollow fine particles used in the present invention is calculated by the following formula.
CV (%) = [particle diameter standard deviation (σ) / average particle diameter (D _n )] × 100

D _j : Particle size of individual particles The content of silica-based hollow fine particles in the transparent coating is preferably in the range of 20 to 80% by weight, more preferably 30 to 65% by weight. When the content of silica-based hollow fine particles in the transparent film is less than 20% by weight, a transparent film having a sufficiently low refractive index may not be obtained, and the content of silica-based hollow fine particles in the transparent film is 80% by weight. On the other hand, since the content of the matrix component described later is too small, the strength and scratch resistance of the transparent film may be insufficient.

The silica-based hollow microparticles for use in the process present invention of the silica-based hollow particles, the average particle diameter is not particularly limited if the range in which the refractive index and particle size variation coefficient described above, JP-2001-23 3 611 JP Silica-based hollow fine particles obtained in accordance with the method for producing silica-based fine particles disclosed in JP-A-2004-203683 and the like can be used.

  For example, a composite oxide fine particle composed of silica and an inorganic oxide other than silica is used as a core, and after forming the silica coating layer (1) as necessary, the inorganic oxide other than silica is removed, and further if necessary In this case, the silica-based hollow fine particles used in the present invention have an average particle diameter in the range of about 19 to 70 nm. The silica coating layer is formed on the core particles so that the total thickness of the silica coating layer (1) and the silica coating layer (2) is about 1 to 10 nm. The diameter variation coefficient is adjusted to be in the range of 1 to 50%. As a method for adjusting the particle diameter variation coefficient, for example, the following methods (1) to (6) may be combined in the main steps of the method for producing silica-based hollow fine particles described above.

  (1) When a composite oxide fine particle comprising silica and an inorganic oxide other than silica is used as a nucleus, a nucleus particle having a nucleus CV value of 100% or less, preferably 50% or less is used. The so-called seed method using seed particles is preferably used for the preparation of the core particles at this time, and it is preferable that the seed particles are slowly grown as far as possible.

  (2) Also when carrying out the particle growth of the core particles, it is preferable to slowly add the silica source and the alumina source as much as possible. The particle growth rate at this time varies depending on the particle diameter of the core particle, but is generally in the range of 0.1 to 10 nm / hour, more preferably 0.2 to 5 nm / hour, and particularly 0.2 to 3 nm / hour. Is preferred.

  (3) When forming the silica coating layer, it is preferable to slowly add the silica source as much as possible. The silica coating speed at this time varies depending on the particle diameter of the core particle, but is generally in the range of 0.1 to 10 nm / hour, more preferably 0.2 to 5 nm / hour, and particularly 0.2 to 3 nm / hour. Is preferred.

  (4) In the above production method, aging is preferably performed at least after grain growth or after formation of the silica coating layer (maturation may be performed at both time points). The aging at this time is preferably carried out in a range of solid content concentration of 1 to 30% by weight, temperature of 30 to 100 ° C., and time of 1 to 12 hours.

  (5) In each of the above steps, it is preferable to prevent aggregation or achieve high dispersion by irradiating ultrasonic waves. Specifically, ultrasonic waves may be irradiated after each of the steps (1) to (4), and it is particularly desirable that the ultrasonic waves be irradiated after the steps (1) and (2).

(6) When there are aggregated particles and coarse particles that are difficult to disperse, it is preferable to remove them with a capsule filter or the like.
The silica-based hollow fine particles used in the present invention are preferably surface-treated with an organosilicon compound represented by the following formula (1) and a hydrolyzate thereof.

_{R n -SiX 4-n (1} )
(In the formula, R is an unsubstituted or substituted hydrocarbon group having 1 to 10 carbon atoms, and may be the same or different from each other. X: an alkoxy group having 1 to 4 carbon atoms or a silanol group) , Halogen, hydrogen, n: an integer of 0 to 3)

  Examples of the organosilicon compound represented by the formula (1) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane. , Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (βmethoxyethoxy) silane, 3,3,3- Trifluoropropyltrimethoxysilane, methyl-3,3,3-trifluoropropyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxymethyltrimethoxy Silane, γ-glycidoxymethyltriexisilane, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxy Silane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ- (β-glycidoxyethoxy) propyltrimethoxysilane, γ- (meth) acrylooxymethyltrimethoxysilane, γ- (meth) acrylooxymethyltriethoxysilane, γ- (meth) acrylooxyethyltrimethoxysilane, γ- (meth) acryloxyethyltriethoxysilane, γ- (meth) acrylooxypropyltrimethoxy Silane, γ- (meth) acrylooxypropyltrimethoxysilane, γ- (meth) a Acryloxypropyltriethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, butyltrimethoxysilane, isobutyltriethoxysilane, hexyltriethoxysilaoctyltriethoxysilane, decyltriethoxysilane, butyltriethoxysilane, isobutyl Triethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltriethoxysilane, 3-ureidoisopropylpropyltriethoxysilane, perfluorooctylethyltrimethoxysilane, perfluorooctylethyltriethoxysilane, perfluorooctylethyltriiso Propoxysilane, trifluoropropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β ( Minoechiru) .gamma.-aminopropyltrimethoxysilane, N- phenyl--γ- aminopropyltrimethoxysilane, .gamma.-mercaptopropyltrimethoxysilane, trimethylsilanol, methyl trichlorosilane and the like.

  When the surface treatment is performed with such an organosilicon compound, it can be uniformly dispersed in the matrix and densely filled, and a transparent film excellent in film strength and scratch resistance can be obtained.

Surface treatment of silica-based hollow fine particles is performed by adding a predetermined amount of the above-mentioned organosilicon compound to an alcohol dispersion of fine particles, adding water thereto, and adding an acid or alkali as a hydrolysis catalyst as necessary to hydrolyze the organosilicon compound. To do. The weight ratio of the silica-based hollow fine particles and the organosilicon compound of this time (solid organosilicon compound component (weight of _{R n -SiX (4-n)} / 2) as weight / silica based hollow fine particles) is silica Although it varies depending on the average particle diameter of the hollow fine particles, it is usually 0.3 or less, preferably 0.005 to 0.3, and more preferably 0.01 to 0.2.

  If the weight ratio is small, the surface treatment is not substantially changed. In some cases, the affinity with a matrix-forming component described later is low, and the dispersibility and stability in the paint become insufficient. In some cases, the fine particles may aggregate, a dense transparent film may not be obtained, and adhesion to the substrate, film strength, scratch resistance, etc. may be insufficient.

  Even if the weight ratio is too large, the dispersibility in the paint is not further improved, the refractive index of the silica-based hollow fine particles is increased, and a transparent film having a desired low refractive index may not be obtained. The antireflection performance may be insufficient.

As the matrix component , a silicone (sol-gel) matrix component, an organic resin matrix component, or the like is used.

As the silicone matrix component, a hydrolyzed polycondensate (cured product) of an organosilicon compound represented by the above formula (1) is preferably used.
Examples of the organic resin-based matrix component include known thermosetting resins, thermoplastic resins, and electron beam curable resins as coating resins.

  Examples of such resins include conventionally used thermoplastic resins such as polyester resins, polycarbonate resins, polyamide resins, polyphenylene oxide resins, thermoplastic acrylic resins, vinyl chloride resins, fluororesins, vinyl acetate resins, and silicone rubbers. , Urethane resin, melamine resin, silicon resin, butyral resin, reactive silicone resin, phenol resin, epoxy resin, unsaturated polyester resin, thermosetting acrylic resin, UV curable acrylic resin, etc., UV curable type An acrylic resin etc. are mentioned. Further, it may be a copolymer or modified body of two or more of these resins. These resins may be emulsion resins, water-soluble resins, and hydrophilic resins. Further, in the case of a thermosetting resin, it may be an ultraviolet curable type or an electron beam curable type, and in the case of a thermosetting resin, a curing catalyst may be included. In the case of a thermosetting resin or an electron beam curable resin, the matrix component is a cured product (polymer).

The film thickness of the transparent coating film is not particularly limited, but is usually in the range of 30 nm to 300 nm, preferably 70 to 200 nm. When the film thickness is within this range, a transparent film having sufficient antireflection performance and high strength can be formed.

  If the film thickness is thin, the optical film thickness deviates from the Fresnel principle, and sufficient antireflection performance may not be obtained. If the film thickness is too thick, cracks may occur in the film or the strength of the film may decrease, and the film may be too thick and the antireflection performance may be insufficient.

  The refractive index of the transparent film is appropriately selected according to the purpose, but is preferably in the range of 1.20 to 1.50, more preferably 1.20 to 1.46. The refractive index can be adjusted by adjusting the amount of silica-based hollow particles and the refractive index. However, even if the refractive index is increased beyond the above range, the antireflection performance is not good depending on the refractive index of the substrate or the refractive index of other films formed below the transparent coating formed as necessary. May be sufficient. The refractive index of the transparent film of the present invention is measured with an ellipsometer (manufactured by ULVAC, EMS-1).

  The method for forming such a substrate with a transparent film is not particularly limited, and specifically, a transparent film-forming paint according to the present invention described later is applied to the substrate by a known method, It can be formed by drying and curing by an ordinary method such as ultraviolet irradiation or heat treatment.

[Transparent coating paint]
The transparent film-forming paint according to the present invention is characterized by comprising the silica-based hollow fine particles, a matrix-forming component, and a polar solvent.

Silica-based hollow fine particles As the silica-based hollow fine particles used in the present invention, the same silica-based hollow fine particles as described above are used. The concentration of the silica-based hollow fine particles in the coating for forming a transparent film is not particularly limited as long as the fluidity of the coating is not impaired, but is 0.1 to 32% by weight, more preferably 0.5 to 25% by weight as a solid content. % Is preferable.

  If the concentration of silica-based hollow fine particles in the coating for forming a transparent film is too low, depending on the ratio, the content of silica-based hollow fine particles in the transparent film is small, and a transparent film having a sufficiently low refractive index cannot be obtained. In some cases, it may be necessary to apply and dry multiple times. If the concentration of the silica-based hollow fine particles in the coating for forming a transparent film is too high, the content of the matrix-forming component described later decreases and the strength of the transparent film may be insufficient.

Matrix-forming component As the matrix-forming component, a silicone-based (sol-gel) matrix-forming component, an organic resin-based matrix-forming component, or the like is used. As the silicone-based matrix-forming component, the same organosilicon compounds as in the above formula (1), their hydrolysates, and hydrolyzed polycondensates (before curing) are preferably used.

  Examples of the organic resin matrix forming component include known thermosetting resins, thermoplastic resins, electron beam curable resins, and the like as coating resins. Specifically, it is as exemplified in the matrix component described above. In the case of a thermosetting resin, a curing catalyst, a photosensitizer, or the like may be included. In the case of such a resin, a resin precursor (that is, a monomer, oligomer, or prepolymer) is usually used. .

  The matrix-forming component is preferably in the range of 20 to 80% by weight, more preferably 35 to 70% by weight when the total amount of the silica-based hollow fine particles and the matrix-forming component is 100% by weight.

Polar solvent The polar solvent used in the present invention is not particularly limited as long as it can dissolve or disperse the matrix-forming component, and the polymerization initiator used as necessary, and can uniformly disperse the silica-based hollow fine particles. Can be used.

  Specifically, alcohols such as water, methanol, ethanol, propanol, 2-propanol (IPA), butanol, diacetone alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, hexylene glycol, isopropyl glycol; acetic acid Esters such as methyl ester, ethyl acetate, butyl acetate; ethers such as diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether Acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetone Ketones such as acetate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, toluene, cyclohexanone, isophorone and the like.

  Among them, alcohols such as methanol, ethanol, propanol and 2-propanol (IPA) can uniformly disperse the surface-treated silica-based hollow fine particles, and the solvent having a carbonyl group can be obtained by treating the surface-treated silica-based hollow fine particles. Since it can disperse | distribute uniformly and the stability of a coating material is good and can form the transparent film excellent in uniformity, adhesiveness with a base material, intensity | strength, etc. with reproducibility, it can use it conveniently.

  The total solid concentration including the silica-based hollow fine particles and the matrix-forming component in the coating for forming a transparent film is preferably in the range of 0.5 to 40% by weight, more preferably 1 to 30% by weight.

  If the solid content concentration is low, the film thickness of the transparent coating becomes thin, and sufficient antireflection performance may not be obtained. If the solid content concentration is too high, the viscosity of the paint will increase and the stability of the paint will decrease or the applicability will decrease, resulting in insufficient uniformity of the transparent film, adhesion to the substrate, strength, etc. It may become.

A conventionally well-known method can be employ | adopted as a method of forming a transparent film using the coating material for transparent film formation which concerns on this invention.
Specifically, the transparent film-forming paint is applied to the substrate by a known method such as dipping, spraying, spinner, roll coating, bar coating, slit coater printing, gravure printing, or micro gravure printing. A transparent film can be formed by applying, drying, and curing by conventional methods such as ultraviolet irradiation, heat treatment, etc.In the present invention, roll coating, slit coater printing, gravure printing, and micro gravure printing are used. Recommended.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Example 1]
Preparation of silica -based hollow fine particles (P-1) Silica-alumina sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: USBB-120, average particle size 25 nm, CV value 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, solid 3900 g of pure water was added to 100 g of Al ₂ O ₃ content (27% by weight) and heated to 98 ° C. While maintaining this temperature, 730 g of an aqueous sodium silicate solution having a concentration of 1.5% by weight as SiO ₂ and Al were added. 730 g of a sodium aluminate aqueous solution having a concentration of 0.5% by weight as ₂ O ₃ was added in 5 hours to obtain a SiO ₂ .Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 30 nm.

Subsequently, in order to form a silica coating layer containing alumina, 7,530 g of a sodium silicate aqueous solution having a concentration of 1.5% by weight as SiO ₂ and a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ , 510 g was added in 5 hours to obtain a dispersion of composite oxide fine particles (1) (secondary particles). At this time, the pH of the reaction solution was 12.2.

Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by weight, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a composite oxide fine particle (1) dispersion. At this time, the average particle size was 50 nm , the change in the average particle size of the particles was 2.5 nm / hour , and the CV value was 29%.
Here, “increase in the average particle size of the particles” refers to “average particle size of the secondary particles of the composite oxide in the step (c)” to “average particle size of the composite oxide fine particles prepared in the step (a)”. Is added to obtain “secondary particles of composite oxide of step (c)” from “fine particles of composite oxide prepared in step (a)”. It is calculated by dividing by “total”. (The same applies to the following examples and comparative examples.)

  To 500 g of the dispersion of composite oxide fine particles (1), 1,125 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles (P-1-1) having a solid concentration of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (P-1-1), 500 g of pure water, 1,750 g of ethanol and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate (SiO ₂ concentration of 28 wt%) was added to 140g for 5 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. Using 200 g of ion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SK1B), it was washed by ion exchange at 80 ° C. for 3 hours to obtain silica-based fine particles (P-1-2) having a solid content concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, again, the silica-based fine particle (P-1-2) dispersion was hydrothermally treated at 150 ° C. for 11 hours, cooled to room temperature, and 400 g of a cation exchange resin (manufactured by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (P-1-3) having a solid concentration of 20% by weight.

Next, an alcohol dispersion of silica-based fine particles (P-1) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane.
3 g of methacryl silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (P-1) having a solid content concentration of 20% by weight, and heat treatment is performed at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (P-1) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based hollow fine particles (P-1).

Manufacture of coating material for forming transparent film (1) Silica-based hollow fine particles (P-1) in an alcohol dispersion diluted with ethanol to a solid content concentration of 5% by weight and acrylic resin (Hitaroid 1007, Hitachi Chemical Co., Ltd.) 3) and 47 g of a 1/1 (weight ratio) mixed solvent of isopropanol and n-butanol were thoroughly mixed to prepare a transparent film-forming paint (1).

Production of substrate with transparent film (1) Transparent film-forming paint (1) is applied to a PET film by a bar coater method and dried at 80 ° C. for 1 minute to form a transparent film having a transparent film thickness of about 100 nm. A base material (1) was obtained. Table 2 shows the total light transmittance, haze, reflectance of light having a wavelength of 550 nm, refractive index of the coating, adhesion, pencil hardness, and scratch resistance of the substrate with transparent coating (1). The total light transmittance and haze were measured with a haze meter (manufactured by Suga Test Instruments Co., Ltd.), and the reflectance was measured with a spectrophotometer (JASCO Corporation, Ubest-55). Moreover, the refractive index of the film was measured with an ellipsometer (manufactured by ULVAC, EMS-1). The uncoated PET film had a total light transmittance of 90.7%, a haze of 2.0%, and a reflectance of light having a wavelength of 550 nm of 7.0%.

Pencil hardness Pencil hardness was measured with a pencil hardness tester in accordance with JIS K 5400. That is, a pencil was set at an angle of 45 degrees with respect to the transparent coating surface, and a predetermined load was applied and pulled at a constant speed, and the presence or absence of scratches was observed.

Adhesive transparent film-coated substrate (A-1) on the surface of the substrate (A-1) with 11 parallel scratches at intervals of 1 mm in length and width to make 100 squares, cellophane tape is adhered to this, then cellophane tape is attached Adhesion was evaluated by classifying the number of cells remaining without peeling off when the film was peeled into the following three stages. The results are shown in the table.
Number of remaining squares more than 90: ◎
Number of remaining squares: 85-89: ○
Number of remaining squares: 84 or less: △

Measurement of Scratch Resistance Using # 0000 steel wool, sliding 50 times at a load of 500 g / cm ² , visually observing the surface of the film and evaluating according to the following criteria, the results are shown in Table 1.

Evaluation criteria:
No streak injury is found: ◎
Slight flaws are observed: ○
Many streak wounds are found: △
The surface has been cut entirely: ×

[Example 2]
Preparation of silica -based hollow fine particles (P-2) Silica-alumina sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, 3900 g of pure water was added to 100 g of Al ₂ O ₃ content (solid content 27 wt%) and heated to 98 ° C., and while maintaining this temperature, 730 g of a sodium silicate aqueous solution having a concentration of 1.5 wt% as SiO ₂ 730 g of a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ was added in 2 hours to obtain a SiO ₂ · Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 31 nm.

Subsequently, in order to form a silica coating layer containing alumina, 7,530 g of a sodium silicate aqueous solution having a concentration of 1.5% by weight as SiO ₂ and a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ , 510 g was added in 2 hours to obtain a dispersion of composite oxide fine particles (2) (secondary particles). At this time, the pH of the reaction solution was 12.2.

Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by weight, filtration was performed with a capsule filter having an opening of 1 μm to obtain a composite oxide fine particle (2) dispersion. At this time, the average particle size was 53 nm , the increase in the average particle size of the particles was 7 nm / hour , and the CV value was 45%.

  To 500 g of the composite oxide fine particle (2) dispersion, 1,125 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles (P-2-1) having a solid content of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (P-2-1), 500 g of pure water, 1,750 g of ethanol, and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate (SiO ₂ concentration of 28 wt%) was added to 140g for 5 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. 200 g of ion exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based fine particles (P-2-2) having a solid content concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, again, the silica-based fine particle (P-2-2) dispersion was hydrothermally treated at 150 ° C. for 11 hours, then cooled to room temperature, and 400 g of a cation exchange resin (manufactured by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was ion-exchanged at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (P-2-3) having a solid content concentration of 20% by weight.

Then, an alcohol dispersion of silica-based fine particles (P-2) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane.
3 g of a methacrylsilane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (P- 2 ) having a solid content concentration of 20% by weight, and heat treatment is performed at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (P-2) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based hollow fine particles (P-2).

Production of transparent film-forming paint (2) In Example 1, except that 50 g of a silica-based hollow fine particle (P-2) alcohol dispersion was diluted with ethanol to a solid content concentration of 5% by weight was used. Transparent coating coating
(2) was prepared.

Production of transparent film-coated substrate (2) In Example 1, except that the transparent film-forming paint (2) was used, a transparent film-coated substrate (2) having a film thickness of about 100 nm was obtained. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness and scratch resistance of the substrate (2) with a transparent coating.

[Example 3]
Preparation of silica -based hollow fine particles (P-3) Silica-alumina sol (Catalyst Chemical Industries, Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, 3900 g of pure water was added to 100 g of Al ₂ O ₃ content (solid content 27 wt%) and heated to 98 ° C., and while maintaining this temperature, 730 g of a sodium silicate aqueous solution having a concentration of 1.5 wt% as SiO ₂ 730 g of a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ was added in 10 hours to obtain a SiO ₂ · Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 31 nm.

Subsequently, in order to form a silica coating layer containing alumina, 7,530 g of a sodium silicate aqueous solution having a concentration of 1.5% by weight as SiO ₂ and a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ , 510 g was added in 10 hours to obtain a dispersion of composite oxide fine particles (3) (secondary particles). At this time, the pH of the reaction solution was 12.2.

Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by weight, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a composite oxide fine particle (3) dispersion. At this time, the average particle size was 53 nm , the increase in the average particle size of the particles was 1.4 nm / hour , and the CV value was 23%.

  To 500 g of the composite oxide fine particle (3) dispersion, 1,125 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles (P-3-1) having a solid content of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (P-3-1), 500 g of pure water, 1,750 g of ethanol, and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate (SiO ₂ concentration of 28 wt%) was added to 140g for 5 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. Using 200 g of ion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SK1B), it was washed by ion exchange at 80 ° C. for 3 hours to obtain silica-based fine particles (P-3-2) having a solid concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, the silica-based fine particle (P-3-2) dispersion was again hydrothermally treated at 150 ° C. for 11 hours, cooled to room temperature, and 400 g of cation exchange resin (Made by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (P-3-3) having a solid content concentration of 20% by weight.

Then, an alcohol dispersion of silica-based fine particles (P-3) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane. 3 g of methacryl silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (P-3) having a solid content concentration of 20% by weight, followed by heat treatment at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (P-3) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based fine particles (P-3).

Production of Transparent Film Forming Paint (3) In Example 1, except that 50 g of a silica-based hollow fine particle (P-3) alcohol dispersion was diluted with ethanol to a solid concentration of 5% by weight. Thus, a transparent film-forming paint (3) was prepared.

Production of transparent film-coated substrate (3) In Example 1, except that the transparent film-forming paint (3) was used, a transparent film-coated substrate (3) having a film thickness of about 100 nm was obtained. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness and scratch resistance of the substrate with transparent coating (3).

[Example 4]
Preparation of silica -based hollow fine particles (P-4) Silica / alumina sol (manufactured by Catalytic Chemical Industry Co., Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, 3900 g of pure water was added to 100 g of Al ₂ O ₃ content (solid content 27 wt%) and heated to 98 ° C., and while maintaining this temperature, an aqueous sodium silicate solution having a concentration of 1.5 wt% as SiO ₂ , 000 g and 7,000 g of a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ were added over 5 hours to obtain a SiO ₂ · Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 50 nm.

Subsequently, in order to form a silica coating layer containing alumina, 16,740 g of a sodium silicate aqueous solution having a concentration of 1.5% by weight as SiO ₂ and a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ , 580 g was added in 5 hours to obtain a dispersion of composite oxide fine particles (4) (secondary particles). At this time, the pH of the reaction solution was 12.2.

Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by weight, filtration was performed with a capsule filter having an opening of 1 μm to obtain a composite oxide fine particle (4) dispersion. At this time, the average particle diameter was 70 nm , and the increase in the average particle diameter of the particles was 4.5 nm / hour , and the CV value was 27%.

  To 500 g of the dispersion of composite oxide fine particles (4), 1,125 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5% by weight) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles (P-4-1) having a solid content concentration of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (P-4-1), 500 g of pure water, 1,750 g of ethanol and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate was added to (SiO ₂ concentration of 28 wt%) 117 g in 5 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. 200 g of ion exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based fine particles (P-4-2) having a solid concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, again, the silica-based fine particle (P-4-2) dispersion was hydrothermally treated at 150 ° C. for 11 hours, then cooled to room temperature, and 400 g of cation exchange resin (manufactured by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (P-4-3) having a solid concentration of 20% by weight.

Then, an alcohol dispersion of silica-based fine particles (P-4) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane.
3 g of methacrylsilane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (P-4) having a solid content concentration of 20% by weight, and heat treatment is performed at 50 ° C. A solid content concentration of 20% by weight was obtained by substituting the solvent with ethanol again using an ultrafiltration membrane.
An alcohol dispersion of silica-based hollow fine particles (P-4) was prepared.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based fine particles (P-4).

Production of transparent film-forming coating material (4) In Example 1, except that 50 g of a dispersion of silica-based hollow fine particles (P-4) diluted with ethanol to a solid concentration of 5% by weight was used. Thus, a transparent film-forming paint (4) was prepared.

Production of transparent film-coated substrate (4) In Example 1, except that the transparent film-forming paint (4) was used, a transparent film-coated substrate (4) having a film thickness of about 100 nm was obtained. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness, and scratch resistance of the substrate (4) with a transparent coating.

[Example 5]
Preparation of silica -based hollow fine particles (P-5) Silica / alumina sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, in the solid content of Al ₂ O ₃ 27 wt%) was added to deionized water 3900g was warmed to 98 ° C. to 100 g, while maintaining this temperature, in order to form a silica coating layer containing alumina, as SiO ₂ and a concentration of 0.5% by weight of an aqueous sodium aluminate solution 700g of the concentration of 1.5 wt% aqueous solution of sodium silicate 2,090g and Al ₂ O ₃ was added at 10 hours, SiO ₂ · Al ₂ O ₃ composite oxide A dispersion of fine particles (5) (secondary particles) was obtained. At this time, the pH of the reaction solution was 12.2.

Subsequently, after washing with an ultrafiltration membrane to obtain a solid content concentration of 13% by weight, the mixture was filtered with a capsule filter having an opening of 1 μm to obtain a composite oxide fine particle (5) dispersion. At this time, the average particle diameter was 33 nm , the increase in the average particle diameter of the particles was 0.8 nm / hour , and the CV value was 29%.

  1,500 g of pure water was added to 500 g of the dispersion of the composite oxide fine particles (5), and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles (P-5-1) having a solid content of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (P-5-1), 500 g of pure water, 1,750 g of ethanol and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate was added to (SiO ₂ concentration of 28 wt%) 55 g in 5 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. 200 g of ion exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based fine particles (P-5-2) having a solid concentration of 20% by weight. An aqueous dispersion was obtained.

Then, again, after the silica-based particles (P- 5 -2) dispersion was heat-treated for 11 hours water at 0.99 ° C., cooled to room temperature, a cation exchange resin (Mitsubishi Chemical Co., Ltd.: Diaion SK1B) 400 g Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (P-5-3) having a solid content concentration of 20% by weight.

Next, an alcohol dispersion of silica-based fine particles (P-5) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane. 3 g of methacryl silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (P-5) with a solid content concentration of 20% by weight, and heat treatment is performed at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (P-5) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based hollow fine particles (P-5).

Production of transparent film-forming paint (5) In Example 1, except that 50 g of a silica-based hollow fine particle (P-5) alcohol dispersion was diluted to 5% by weight with ethanol to obtain a solid content of 5% by weight. Thus, a transparent film-forming paint (5) was prepared.

Production of transparent film-coated substrate (5) In Example 1, except that the transparent film-forming paint (5) was used, a transparent film-coated substrate (5) having a film thickness of about 100 nm was obtained. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness and scratch resistance of the substrate (5) with a transparent coating.

[Example 6]
Production of transparent film-forming coating material (6) 40 g of a dispersion of silica-based hollow fine particles (P-1) prepared in the same manner as in Example 1, diluted with ethanol to a solid content concentration of 5% by weight, and acrylic 4 g of resin (Hitaroid 1007, manufactured by Hitachi Chemical Co., Ltd.) and 56 g of a 1/1 (weight ratio) mixed solvent of isopropanol and n-butanol were sufficiently mixed to prepare a transparent film forming paint (6).

Production of transparent film-coated substrate (6) In Example 1, except that the transparent film-forming paint (6) was used, a transparent film-coated substrate (6) having a transparent film thickness of about 100 nm was obtained. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness and scratch resistance of the substrate (6) with a transparent coating.

[Example 7]
Production of transparent film-forming coating material (7) 60 g of a dispersion obtained by diluting an alcohol dispersion of silica-based hollow fine particles (P-1) prepared in the same manner as in Example 1 with ethanol to a solid content concentration of 5% by weight, and acrylic 2 g of resin (Hitaroid 1007, manufactured by Hitachi Chemical Co., Ltd.) and 38 g of a 1/1 (weight ratio) mixed solvent of isopropanol and n-butanol were sufficiently mixed to prepare a transparent film forming paint (7).

Production of transparent film-coated substrate (7) In Example 1, except that the transparent film-forming paint (7) was used, a transparent film-coated substrate (7) having a film thickness of about 100 nm was obtained. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness, and scratch resistance of the substrate with transparent film (7).

[Comparative Example 1]
Preparation of silica -based hollow fine particles (RP-1) Silica / alumina sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, 3900 g of pure water was added to 100 g of Al ₂ O ₃ content (solid content 27 wt%) and heated to 98 ° C., and while maintaining this temperature, 730 g of a sodium silicate aqueous solution having a concentration of 1.5 wt% as SiO ₂ 730 g of a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ was added in 0.5 hour to obtain a SiO ₂ · Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 30 nm.

Subsequently, in order to form a silica coating layer containing alumina, 7,530 g of a sodium silicate aqueous solution having a concentration of 1.5% by weight as SiO ₂ and a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ , 510 g was added in 0.5 hours to obtain a dispersion of composite oxide fine particles ( 8 ) (secondary particles). At this time, the pH of the reaction solution was 12.2.

Subsequently, it was washed with an ultrafiltration membrane to obtain a composite oxide fine particle ( 8 ) dispersion liquid having a solid content concentration of 13% by weight. At this time, the average particle size was 50 nm , the increase in the average particle size of the particles was 25 nm / hour , and the CV value was 65%.
Next, 1,125 g of pure water was added to 500 g of the dispersion of the composite oxide fine particles (1) having a solid concentration of 13 wt% by washing with an ultrafiltration membrane, and concentrated hydrochloric acid (concentration 35.5 wt%). Was dropped to pH 1.0, and dealumination was performed. Next, an aqueous dispersion of silica-based fine particles (RP-1-1) having a solid content concentration of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (RP-1-1), 500 g of pure water, 1,750 g of ethanol, and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate (SiO ₂ concentration of 28 wt%) was added to 140g for 5 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. 200 g of ion exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based fine particles (RP-1-2) having a solid concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, again, the silica-based fine particle (RP-1-2) dispersion was hydrothermally treated at 150 ° C. for 11 hours, cooled to room temperature, and 400 g of a cation exchange resin (manufactured by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was ion-exchanged at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (RP-1-3) having a solid concentration of 20% by weight.

Next, an alcohol dispersion of silica-based fine particles (RP-1) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane.
3 g of methacrylsilane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (RP-1) with a solid content concentration of 20% by weight, and heat treatment is performed at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (RP-1) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based hollow fine particles (RP-1).

Production of transparent coating film forming paint (R1) In Example 1, except that 50 g of a dispersion of silica-based hollow fine particles (RP-1) in which the alcohol dispersion was diluted with ethanol to a solid content concentration of 5% by weight was used. Thus, a transparent film-forming paint (R1) was prepared.

Production of transparent film-coated substrate (R1) In Example 1, except that the transparent film-forming paint (R1) was used, a transparent film-coated substrate (R1) having a film thickness of about 100 nm was obtained. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness, and scratch resistance of the substrate with transparent coating (R1).

[Comparative Example 2]
Preparation of silica -based hollow fine particles (RP-2) Silica / alumina sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, 3900 g of pure water was added to 100 g of Al ₂ O ₃ content (solid content 27 wt%) and heated to 98 ° C., and while maintaining this temperature, an aqueous solution of sodium silicate having a concentration of 1.5 wt% as SiO ₂ A dispersion of SiO ₂ · Al ₂ O ₃ composite oxide fine particles (RP2) (secondary particles) by adding 090 g and 700 g of 0.5% by weight sodium aluminate aqueous solution as Al ₂ O ₃ in 1 hour. Got. At this time, the pH of the reaction solution was 12.2.

Subsequently, it was washed with an ultrafiltration membrane to obtain a composite oxide fine particle ( 9 ) dispersion having a solid concentration of 13% by weight. At this time, the average particle diameter was 33 nm , the increase in the average particle diameter of the particles was 8 nm / hour , and the CV value was 58%.
To 500 g of the composite oxide fine particle ( 9 ) dispersion, 1,125 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles ( RP-2-1 ) having a solid content concentration of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (RP-2-1), 500 g of pure water, 1,750 g of ethanol and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate (SiO ₂ concentration of 28% by weight) 55 g was added in 2 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. 200 g of ion exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based fine particles ( RP-2-2 ) having a solid content concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, again, the silica-based fine particle (RP-2-2) dispersion was hydrothermally treated at 150 ° C. for 11 hours, cooled to room temperature, and 400 g of a cation exchange resin (manufactured by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was ion-exchanged at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (RP-2-3) having a solid content concentration of 20% by weight.

Next, an alcohol dispersion of silica-based fine particles (RP-2) having a solid concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane. 3 g of methacrylsilane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (RP-2) having a solid content concentration of 20% by weight, and heat treatment is performed at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (RP-2) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based hollow fine particles (RP-2).

Production of transparent film-forming paint (R2) In Example 1, except that 50 g of a dispersion of silica-based hollow fine particles (RP-2) in which the alcohol dispersion was diluted with ethanol to a solid content concentration of 5% by weight was used. Thus, a transparent film-forming paint (R2) was prepared.

Production of transparent film-coated substrate (R2) In Example 1, a transparent film-coated substrate (R2) having a transparent film thickness of about 100 nm was obtained in the same manner except that the transparent film-forming paint (R2) was used. It was. Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness, and scratch resistance of the substrate with transparent coating (R2).

[Comparative Example 3]
Preparation of silica -based hollow fine particles (RP-3) Silica / alumina sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, 3900 g of pure water was added to 100 g of Al ₂ O ₃ content (solid content 27 wt%) and heated to 98 ° C., and while maintaining this temperature, an aqueous sodium silicate solution having a concentration of 1.5 wt% as SiO ₂ , 000 g and 7,000 g of a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ were added in 0.5 hours to obtain a SiO ₂ · Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 50 nm.

Subsequently, in order to form a silica coating layer containing alumina, 16,740 g of a sodium silicate aqueous solution having a concentration of 1.5% by weight as SiO ₂ and a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ , 580 g was added in 0.5 hour to obtain a dispersion of composite oxide fine particles ( 10 ) (secondary particles). At this time, the pH of the reaction solution was 12.2.

Subsequently, it was washed with an ultrafiltration membrane to obtain a composite oxide fine particle (4) dispersion having a solid concentration of 13% by weight. At this time, the average particle diameter was 70 nm , the increase in the average particle diameter of the particles was 45 nm / hour , and the CV value was 63%.
To 500 g of the composite oxide fine particle ( 10 ) dispersion, 1,125 g of pure water was added, and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles (RP-3-1) having a solid content concentration of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (RP-3-1), 500 g of pure water, 1,750 g of ethanol, and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate was added to (SiO ₂ concentration of 28 wt%) 117 g in 5 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. 200 g of ion exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based fine particles (RP-3-2) having a solid concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, again, the silica-based fine particle (RP-3-2) dispersion was hydrothermally treated at 150 ° C. for 11 hours, cooled to room temperature, and 400 g of a cation exchange resin (manufactured by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (RP-3-3) having a solid concentration of 20% by weight.

Next, an alcohol dispersion of silica-based fine particles (RP-3) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane.
3 g of a methacryl silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (RP-3) having a solid content concentration of 20% by weight, followed by heat treatment at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (RP-3) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based hollow fine particles (RP-3).

Production of transparent coating film forming paint (R3) In Example 1, except that 50 g of a dispersion of silica-based hollow fine particles (RP-3) in an alcohol dispersion diluted to 5% by weight with ethanol was used. Thus, a transparent film-forming paint (R3) was prepared.

Production of transparent film-coated substrate (R3) In Example 1, a transparent film-coated substrate (R3) having a film thickness of about 100 nm was obtained in the same manner except that the transparent film-forming paint (R3) was used. It was. The total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness and scratch resistance of the substrate with transparent coating (R3) are shown in the table.

[Comparative Example 4]
Preparation of silica -based hollow fine particles (RP-4) Silica / alumina sol (manufactured by Catalyst Kasei Kogyo Co., Ltd .: USBB-120, average particle size 25 nm, CV value: 25%, SiO ₂ · Al ₂ O ₃ concentration 20% by weight, 390 g of pure water was added to 10 g of Al ₂ O ₃ content (solid content 27 wt%) and heated to 98 ° C., and while maintaining this temperature, an aqueous solution of sodium silicate having a concentration of 1.5 wt% as SiO ₂ 180 g and 3,180 g of an aqueous sodium aluminate solution having a concentration of 0.5% by weight as Al ₂ O ₃ were added over 10 hours to obtain a SiO ₂ · Al ₂ O ₃ primary particle dispersion. The pH of the reaction solution at this time was 12.0. Moreover, the average particle diameter was 80 nm.

Next, in order to form a silica coating layer containing alumina, 3,750 g of a sodium silicate aqueous solution having a concentration of 1.5% by weight as SiO ₂ and a sodium aluminate aqueous solution having a concentration of 0.5% by weight as Al ₂ O ₃ , 250 g was added in 10 hours to obtain a dispersion of composite oxide fine particles ( 11 ) (secondary particles). At this time, the pH of the reaction solution was 12.2.

Subsequently, after washing with an ultrafiltration membrane to a solid content concentration of 13% by weight, the mixture was filtered through a capsule filter having an opening of 1 μm to obtain a composite oxide fine particle (4) dispersion. At this time, the average particle size was 100 nm , the increase in the average particle size of the particles was 3.8 nm / hour , and the CV value was 27%.

1,500 g of pure water was added to 500 g of the dispersion of the composite oxide fine particles ( 11 ), and concentrated hydrochloric acid (concentration 35.5 wt%) was added dropwise to adjust the pH to 1.0, followed by dealumination. Next, an aqueous dispersion of silica-based fine particles (RP-4-1) having a solid content concentration of 20% by weight by separating and washing the aluminum salt dissolved in the ultrafiltration membrane while adding 10 L of hydrochloric acid aqueous solution of pH 3 and 5 L of pure water. Got.

Next, a mixture of 150 g of an aqueous dispersion of silica-based fine particles (RP-4-1), 500 g of pure water, 1,750 g of ethanol and 626 g of ammonia water having a concentration of 28% by weight was heated to 35 ° C. silicate (SiO ₂ concentration of 28% by weight) 76 g was added in 3 hours, further washed with an ultrafiltration membrane while adding pure water 5L, an aqueous dispersion having a solid concentration of 20 wt% of shea silica-based fine particles Obtained.

Next, aqueous ammonia is added to this silica-based fine particle dispersion to adjust the pH of the dispersion to 10.5, and then aged at 200 ° C. for 11 hours, then cooled to room temperature, and a cation exchange resin (Mitsubishi). Chemical Co., Ltd. (Diaion SK1B) 400 g was used for ion exchange for 3 hours, then anion exchange resin (Mitsubishi Chemical Co., Ltd .: Diaion SA20A) 200 g was used for ion exchange for 3 hours. 200 g of ion exchange resin (Mitsubishi Chemical Corporation: Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain silica-based fine particles (RP-4-2) having a solid concentration of 20% by weight. An aqueous dispersion was obtained.

  Next, the silica-based fine particle (RP-4-2) dispersion was again hydrothermally treated at 150 ° C. for 11 hours, cooled to room temperature, and 400 g of cation exchange resin (Made by Mitsubishi Chemical Corporation: Diaion SK1B). Ion exchange for 3 hours, followed by ion exchange for 3 hours using 200 g of anion exchange resin (Mitsubishi Chemical Corporation: Diaion SA20A), and further cation exchange resin (Mitsubishi Chemical Corporation: 200 g of Diaion SK1B) was used for ion exchange at 80 ° C. for 3 hours for washing to obtain an aqueous dispersion of silica-based fine particles (RP-4-3) having a solid concentration of 20% by weight.

Next, an alcohol dispersion of silica-based fine particles (RP-4) having a solid concentration of 20% by weight was prepared by replacing the solvent with ethanol using an ultrafiltration membrane.
3 g of methacryl silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-503) is added to 100 g of an alcohol dispersion of silica-based fine particles (RP-4) having a solid content concentration of 20% by weight, and heat treatment is performed at 50 ° C. Then, an alcohol dispersion of silica-based hollow fine particles (RP-4) having a solid content concentration of 20% by weight was prepared by replacing the solvent with ethanol again using an ultrafiltration membrane.
Table 1 shows the average particle diameter, CV value, and refractive index of the silica-based hollow fine particles (RP-4).

Production of transparent film-forming paint (R4) In Example 1, except that 50 g of a dispersion of silica-based hollow fine particles (RP-4) in which the alcohol dispersion was diluted with ethanol to a solid content concentration of 5% by weight was used. Thus, a transparent film-forming paint (R4) was prepared.

Production of transparent film-coated substrate (R4) In Example 1, a transparent film-coated substrate (R4) having a transparent film thickness of 100 nm was obtained except that the transparent film-forming paint (R4) was used. . Table 1 shows the total light transmittance, haze, reflectance, refractive index, adhesion, pencil hardness, and scratch resistance of the substrate with transparent coating (R4).

Claims (5)

  (A) a step of preparing composite oxide fine particles comprising silica and an inorganic oxide other than silica, having an average particle diameter of 19 to 70 nm and a CV value of 100% or less;
  (B) adding a silica source and an alumina source to the composite oxide fine particles, and growing the composite oxide fine particles to produce a composite oxide primary particle dispersion;
  (C) In the composite oxide primary particle dispersion, SiO higher than that in the step (b). ₂ / Al ₂ O _Three A step of adding a silica source and an alumina source in a ratio to form a silica coating layer containing alumina on the primary particles of the composite oxide to produce a secondary particle dispersion of the composite oxide;
  (D) filtering the composite oxide secondary particle dispersion with a capsule filter having an opening of 1 μm;
  (E) removing alumina from the composite oxide particles obtained in the step (d);
  (F) adding ethyl silicate to the dispersion containing the silica-based particles obtained in the step (e);
  (G) hydrolyzing the dispersion containing the silica-based particles obtained in the step (f) to produce a dispersion of silica-based hollow fine particles;
  (H) a step of replacing the dispersion of the silica-based hollow fine particles with an alcohol,
  (I) adding a silane coupling agent to the alcohol dispersion of silica-based hollow fine particles obtained in step (h), and surface-treating the silica-based hollow fine particles;
  (J) Silica-based hollow fine particles obtained in the step (i) having a particle size variation coefficient of 1 to 50%, an average particle size (Dn) of 20 to 80 nm, and a refractive index of 1.10 to 1.40; A step of mixing a matrix-forming component and a polar solvent to produce a transparent film-forming paint,
  When the average particle size of the composite oxide fine particles prepared in the step (a) is compared with the average particle size of the secondary particles of the composite oxide obtained in the step (c), the increase in the average particle size is 0. The method for producing a coating material for forming a transparent film, wherein the silica source and the alumina source are added in the step (b) and the step (c) so as to be in a range of 1 to 10 nm / hour. The thickness of the silica-coated layer of the silica-based hollow particles in the coating is a 1 to 10 nm, the concentration of the silica-based hollow particles is in the range of 0.1 to 32% by weight solids, including the matrix-forming component The method for producing a coating material for forming a transparent film according to claim 1, wherein the total solid content concentration is in the range of 0.5 to 40% by weight.   A transparent film comprising a base material and the transparent film-forming paint obtained by the method according to claim 1 or 2 applied thereto to form a transparent film comprising silica-based hollow fine particles and a matrix component. A method for producing a substrate.   The method for producing a substrate with a transparent coating according to claim 3, wherein the content of the silica-based hollow fine particles in the transparent coating is in the range of 20 to 80% by weight.   The method for producing a substrate with a transparent coating according to claim 3 or 4, wherein the thickness of the transparent coating is in the range of 30 nm to 300 nm and the refractive index is in the range of 1.25 to 1.50. .