Metal oxide particle dispersion, coating liquid, and method of manufacturing film-coated substrate

Abstract

To provide a metal oxide particle dispersion capable of enhancing scratch resistance of films.SOLUTION: A dispersion of the present invention comprises metal oxide particles having a photo-curable functional group, a photopolymerization initiator, and an organic solvent, where the mole number of the photopolymerization initiator attached to a metal oxide particle is 1.5×10-26 mol / nm2 or greater per unit surface area of the metal oxide particle.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dispersion of metal oxide particles.

[0002] In displays of televisions, smartphones, car navigation systems, etc., as well as in glasses, lenses, etc., coating solutions obtained by mixing a dispersion of metal oxide particles with an organic binder are used to form functional films. In films containing metal oxide particles, an interface exists between the metal oxide particles and the organic binder, so the metal oxide particles are easily detached from the film due to external forces such as friction, and good scratch resistance cannot be obtained. In order to improve the scratch resistance of the film, it is known to provide photocurable functional groups on the surface of the metal oxide particles to bond the metal oxide particles to the organic binder (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-137097 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the scratch resistance of a film is improved by bonding metal oxide particles and an organic binder via a photocurable functional group. In recent years, with the increase in touch panel displays, physical contact with the display surface has increased, and therefore films with high scratch resistance are required. [Means for solving the problem]

[0005] The present inventors have found that the scratch resistance of a film can be improved by previously attaching a photopolymerization initiator to metal oxide particles in a dispersion. In a coating solution prepared using this dispersion, a large amount of photopolymerization initiator is attached to the metal oxide particles. Since polymerization is initiated from the photopolymerization initiator during curing by ultraviolet irradiation, the photopolymerization initiator attached to the surface of the metal oxide particles is more likely to contribute to bonding between the metal oxide particles and the organic binder. Specifically, the present invention provides a coating solution comprising metal oxide particles having photocurable functional groups, a photopolymerization initiator, and an organic solvent, wherein the number of moles of photopolymerization initiator attached to the metal oxide particles per unit surface area of ​​the metal oxide particles is 1.5 × 10 -26 mol / nm 2 The above dispersion liquid. DETAILED DESCRIPTION OF THE INVENTION

[0006] The present invention relates to a dispersion liquid containing metal oxide particles having photocurable functional groups, a photopolymerization initiator, and an organic solvent, in which a specific amount of the photopolymerization initiator is attached to the metal oxide particles in advance. At this time, the number of moles of the photopolymerization initiator attached to the metal oxide particles and the surface area (nm 2 ) and the ratio (hereinafter referred to as unit adhesion amount) is 1.5 × 10 -26 mol / nm 2 That's all. By using such a dispersion in a coating liquid (containing an organic binder with photocurable functional groups), it is possible to increase the amount of photopolymerization initiator attached to the metal oxide particles. When a film is formed using this coating liquid, the functional groups start to react with the photopolymerization initiator as the starting point. Therefore, the closer the photopolymerization initiator is to the metal oxide particles, the easier it is for the metal oxide particles to bond to the organic binder. In other words, metal oxide particles with a photopolymerization initiator attached are more likely to bond to the organic binder than metal oxide particles without a photopolymerization initiator attached. Here, the greater the amount of photopolymerization initiator attached to the metal oxide particles, the greater the number of bonds between the metal oxide particles and the organic binder in the film, and the higher the scratch resistance of the film. Therefore, the unit adhesion amount is 7 x 10 -26 mol / nm 2 More than 10 x 10 is preferable. -26 mol / nm 2The above is more preferable. In a reaction initiated by a photopolymerization initiator present near the organic binder (i.e., a photopolymerization initiator separated from the metal oxide particles), the organic binders tend to bond together. As the bonding of the organic binders progresses, the molecular weight of the organic binder increases. Therefore, the organic binder becomes less mobile and less likely to bond with the metal oxide particles.

[0007] The photopolymerization initiator preferably contains phosphorus (P). Since P is thought to adsorb to OH groups on the surface of metal oxide particles, the photopolymerization initiator easily adheres to the metal oxide particles. As the P-containing photopolymerization initiator, a phosphine oxide-based photopolymerization initiator (hereinafter referred to as phosphine oxide) is more preferred. Phosphine oxide has a structure represented by the following formula (A).

[0008] R3P=O······Eq. (A) R is a hydrocarbon group. The hydrocarbon group has, for example, 1 to 15 carbon atoms. R may be the same or different. Examples of R include a phenyl group and a derivative of a phenyl group such as a trimethylbenzoyl group. When R is a phenyl group (or a derivative thereof), phosphine oxide is likely to be adsorbed to metal oxide particles. This is thought to be due to the electron-donating properties of the phenyl group (or a derivative thereof). Furthermore, it is preferable that at least one of the three R is a phenyl group, and it is more preferable that two of the three R are phenyl groups. A phenyl group is likely to increase the scratch resistance of the film.

[0009] The functional group is preferably at least one selected from an acrylate group, a methacrylate group, a vinyl group, and an epoxy group. These functional groups facilitate dispersing the metal oxide particles in a solvent. Acrylate groups and methacrylate groups are more preferred because they facilitate bonding between the metal oxide particles and the organic binder.

[0010] By bonding or adsorbing a surface treatment agent having functional groups to metal oxide particles, functional groups can be provided on the surface of the metal oxide particles. Examples of surface treatment agents include coupling agents. Coupling agents can bond metal oxide particles to organic binders, acting as a bond between the metal oxide particles and the organic binder. For example, in the case of a coupling agent having an alkoxy group and a functional group, the alkoxy group reacts with the OH group on the surface of the metal oxide particles, and the functional group bonds with the organic binder. Examples of coupling agents include silane coupling agents, aluminate coupling agents, titanate coupling agents, and zirconate coupling agents. Silane coupling agents are particularly preferred. Silane coupling agents are easy to uniformly modify the surface of metal oxide particles.

[0011] The greater the amount of functional groups possessed by the metal oxide particles, the greater the bonding between the metal oxide particles and the organic binder, resulting in a film with higher scratch resistance. The greater the amount of surface treatment agent in the dispersion, the greater the amount of functional groups possessed by the metal oxide particles. Therefore, the content of the surface treatment agent in the dispersion is preferably 5 parts by mass or more per 100 parts by mass of metal oxide particles. On the other hand, the less surface treatment agent in the dispersion, the higher the proportion of metal oxide particles in the film, making it easier to impart the functionality of the metal oxide particles to the film. Therefore, the content of the surface treatment agent is preferably 30 parts by mass or less per 100 parts by mass of metal oxide particles.

[0012] When the dispersion contains a surface treatment agent, the surface treatment agent that is not bound or adsorbed to the surface of the metal oxide particles in the dispersion (unbound surface treatment agent) is dispersed in the organic solvent in the dispersion. The smaller the amount of surface treatment agent dispersed in the organic solvent, the greater the film shrinkage upon curing, resulting in a denser film. On the other hand, the amount of surface treatment agent bound or adsorbed to the surface of the metal oxide particles (hereinafter collectively referred to as "bound") (hereinafter referred to as the "amount of binding functional groups") is preferably 0.1 wt% or more, more preferably 0.5 wt% or more, and even more preferably 1.5 wt% or more. The more surface treatment agent is bound, the greater the bonding between the metal oxide particles and the organic binder, resulting in higher scratch resistance of the film. On the other hand, the amount of binding functional groups is preferably 10 wt% or less, more preferably 5 wt% or less. The smaller the amount of surface treatment agent in the film, the easier it is to impart the functionality of the metal oxide particles to the film.

[0013] The metal oxide particles may contain elements such as Si, Al, As, B, Bi, Cd, Co, Fe, Ga, Ge, In, Nb, Pb, Sb, Sn, Ti, V, Zn, and Zr, or oxides of these elements.

[0014] Metal oxide particles with an average particle size of 120 nm or less are less likely to settle, making them easier to disperse in a solvent and more likely to disperse uniformly in a film. Metal oxide particles with an average particle size of 100 nm or less are less likely to scatter light, reducing the haze of the film. On the other hand, metal oxide particles with an average particle size of 5 nm or more are less likely to aggregate, making them easier to disperse in a solvent. Here, the average particle size of metal oxide particles is measured using a transmission electron microscope (TEM).

[0015] The type of metal oxide particles can be selected depending on the function desired to be imparted to the film. For example, when metal oxide particles having a lower refractive index than the organic binder (hereinafter referred to as low refractive index particles) are used, a film having a low refractive index (low refractive index film) can be formed. When metal oxide particles having a higher refractive index than the organic binder (hereinafter referred to as high refractive index particles) are used, a film having a high refractive index (high refractive index film) can be formed. When solid particles are used as the metal oxide particles, a film having high hardness and scratch resistance (hard coat) can be formed. When conductive metal oxide particles are used, a conductive film can be formed.

[0016] Solid or hollow particles can be used as metal oxide particles. Hollow particles are particles that have voids inside. The number of voids may be one or more. Because hollow particles have voids inside, the refractive index of the film can be lowered. The lower the refractive index of the hollow particles, the lower the refractive index of the film. The refractive index of hollow particles is preferably 1.38 or less, more preferably 1.34 or less, and even more preferably 1.3 or less. On the other hand, it is difficult to obtain hollow particles with a refractive index less than 1.08. When solid particles are used as low refractive index particles, the hardness of the film increases.

[0017] The higher the porosity of hollow particles (the proportion of voids in a hollow particle), the lower the refractive index of the hollow particles. The porosity of hollow particles is 30% or more. On the other hand, the porosity of solid particles is less than 30%. When the porosity of hollow particles is 60% or less, the hollow particles are strong and therefore less likely to crack. If hollow particles crack, it is difficult to achieve the effect of lowering the refractive index.

[0018] Examples of the shape of the metal oxide particles and voids include spherical, ellipsoidal (rugby ball), cocoon-like, confetti-like, chain-like, dice-like, etc. Spherical particles are easily dispersed uniformly in a coating liquid or film.

[0019] When there is one void, the hollow particle has an outer shell and a void inside it. When the void inside the shell has a shape that follows the particle's outer shape (i.e., the void is similar to the shape of the hollow particle), the shell thickness is uniform. When stress is applied to a shell of uniform thickness, the outer shell of the hollow particle is less likely to crack. In this case, the thicker the outer shell, the less likely the hollow particle is to crack. Therefore, the average thickness of the outer shell is preferably 0.5 nm or more, more preferably 1 nm or more. On the other hand, the thinner the average thickness of the outer shell, the higher the proportion of voids. Therefore, the average thickness of the outer shell is preferably 20 nm or less, more preferably 15 nm or less. When there is one void, the hollow particle's strength is increased by making the shape of the hollow particle spherical. Here, the average thickness of the outer shell is measured by TEM.

[0020] Although there is no lower limit to the average particle size of hollow particles, it is difficult to obtain hollow particles less than 20 nm. Furthermore, the larger the average particle size of hollow particles, the higher the porosity of the hollow particles. Therefore, the average particle size of hollow particles is preferably 20 nm or more, more preferably 55 nm or more, and even more preferably 65 nm or more. Here, the average particle size of hollow particles is measured by TEM.

[0021] Furthermore, the low-refractive-index particles preferably contain silicon oxide (silica). This reduces the refractive index and costs. Since components other than silica may be added to such low-refractive-index particles during the manufacturing process, they may contain components other than silica. For example, they may contain elements such as Al, Sn, Sb, Ti, Zr, Zn, Cu, Fe, and In, or oxides of these elements. The higher the silica content of the low-refractive-index particles, the lower the refractive index of the low-refractive-index particles. Furthermore, the hardness of the film increases. The silica content of the low-refractive-index particles is preferably 98% by weight or more, more preferably 99% by weight or more, and even more preferably 99.5 parts by weight or more, calculated as SiO2. The silica content of the low-refractive-index particles is preferably 100% by weight or more. The silica content of the low-refractive-index particles can be determined by measuring the remaining components after calcining the solid content of the dispersion at 1000°C using an ICP inductively coupled plasma optical emission spectroscopy mass spectrometer (ICP-OES). Note that when the low-refractive-index particles are solid particles, the hardness of the film increases even more.

[0022] The high-refractive-index particles are preferably solid particles. The fewer voids there are in the high-refractive-index particles, the higher the refractive index of the high-refractive-index particles. The high-refractive-index particles preferably contain oxides of Ti, Zr, Nb, Sn, and Zn. The content of these oxides in the high-refractive-index particles is preferably 40% by weight or more, more preferably 45% by weight or more, and even more preferably 50% by weight or more. The weights of these oxides are the concentrations converted into TiO2, ZrO, Nb2O5, SnO2, and ZnO, respectively.

[0023] The organic solvent may be any solvent capable of dispersing metal oxide particles, such as alcohol, ether, ester, or ketone.

[0024] Metal oxide particles with a high unit coating weight can also be dispersed in hydrophobic organic solvents, such as hexane, benzene, toluene, xylene, chloroform, methyl acetate, and ethyl acetate.

[0025] The higher the solids concentration of the dispersion, the smaller the volume per particle number, and therefore the lower the transportation costs. Therefore, from the viewpoint of reducing transportation costs, the solids concentration of the dispersion is preferably 5% by weight or more, more preferably 10% by weight or more. After transportation, the metal oxide particle dispersion is mixed with an organic binder to form a coating liquid. By transporting the dispersion in a high concentration state, transportation costs can be reduced. When preparing a coating liquid after transporting the dispersion in a high concentration state, the coating liquid can be diluted to the desired concentration by further mixing a solvent. On the other hand, the lower the solids concentration of the dispersion, the easier it is to transport and handle. Therefore, the solids concentration is preferably 60% by weight or less, more preferably 50% by weight or less.

[0026] The higher the proportion of metal oxide particles in the solid content of the dispersion, the easier it is to impart the characteristics of metal oxide particles to the film. Therefore, the content of metal oxide particles in the solid content is preferably 75 wt% or more, more preferably 80 wt% or more, and even more preferably 85 wt% or more. This content is even more preferably 90 wt% or more.

[0027] The metal oxide particles can be prepared, for example, by the method described in JP 2012-30489 A.

[0028] The coating liquid will be described below. The coating liquid contains metal oxide particles having a photocurable functional group, an organic binder having a photocurable functional group, a photopolymerization initiator, and an organic solvent. Here, the unit deposition amount is 1.0 × 10 -25 mol / nm 2 This value is 1.3×10 -25 mol / nm 2 More than 1.5 × 10 is preferable. -25 mol / nm 2The above is more preferable. The above-mentioned forms and characteristics can be applied to the metal oxide particles, photopolymerization initiator, organic solvent, and functional group contained in the coating liquid.

[0029] The greater the amount of photopolymerization initiator in the solid content of the coating solution, the greater the amount of photopolymerization initiator that adheres to the metal oxide particles. Therefore, the number of moles of photopolymerization initiator relative to the weight of metal oxide particles in the solid content is 0.8 × 10 -5 mol / g or more is preferable, and 1.0×10 -5 mol / g or more is more preferable, and 2.5×10 -5 mol / g or more is more preferable. On the other hand, the less the photopolymerization initiator in the solid content, the more metal oxide particles can be contained in the solid content. The more metal oxide particles there are in the film, the easier it is to impart the functionality of the metal oxide particles to the film. Therefore, the number of moles of photopolymerization initiator relative to the weight of metal oxide particles in the solid content is 1.0 × 10 -4 mol / g or less is preferable, and 5.0×10 -5 mol / g or less is more preferable.

[0030] Furthermore, if the amount of photopolymerization initiator in the solid content of the coating liquid is large, the number of reaction initiation sites increases during curing, making the film more likely to harden. Therefore, the content of photopolymerization initiator in the solid content of the coating liquid is preferably 1% by weight or more. On the other hand, if this content is small, it is easier to impart the functionality of metal oxide particles to the film. Therefore, this content is preferably 10% by weight or less.

[0031] The organic binder will be described below. The number of functional groups of the organic binder is preferably two or more. An organic binder with two or more functional groups bonds to both metal oxide particles and other organic binders, improving the scratch resistance of the film. The number of functional groups of the organic binder is more preferably three or more. An organic binder with three or more functional groups bonds three-dimensionally to metal oxide particles and other organic binders more than an organic binder with two or fewer functional groups, improving the hardness and scratch resistance of the film. The higher the number of functional groups of the organic binder, the higher the hardness and scratch resistance of the film. Therefore, the number of functional groups of the organic binder is preferably six or more.

[0032] When the organic binder has six or more functional groups, the coating liquid preferably contains a second organic binder having two to three functional groups. Here, the organic binder having six or more functional groups is referred to as the first organic binder. The second organic binder reduces the interaction between the metal oxide particles and the first organic binder in the coating liquid, thereby lowering the viscosity of the coating liquid.

[0033] On the other hand, the smaller the number of functional groups in the organic binder, the lower the viscosity of the coating liquid and the easier it is for the organic binder to bond to the metal oxide particles. Therefore, the number of functional groups in the organic binder is preferably 8 or less.

[0034] The greater the number of functional groups per unit molecular weight, the greater the film shrinkage and therefore the higher the film hardness. The molecular weight of the first organic binder is preferably 1,000 or less, and more preferably 800 or less.

[0035] The more organic binder there is in the solid content, the more the smoothness of the film surface improves. Therefore, the organic binder content in the solid content is preferably 30% by weight or more. On the other hand, the lower the organic binder content, the more metal oxide particles can be contained in the solid content. Therefore, the organic binder content is preferably 90% by weight or less, more preferably 60% by weight or less, and even more preferably 55% by weight or less.

[0036] The coating liquid preferably contains a leveling agent. The leveling agent reduces the dynamic friction coefficient of the film surface and improves the scratch resistance of the film. The leveling agent content in the solid content is preferably 0.5 wt % or more. On the other hand, the lower the leveling agent content, the more metal oxide particles and organic binders can be increased in the solid content. Therefore, the leveling agent content is preferably 6 wt % or less.

[0037] The more metal oxide particles there are in the solid content, the easier it is to impart the functionality of the metal oxide particles to the film. Therefore, the metal oxide particle content in the solid content is preferably 10% by weight or more, more preferably 30% by weight or more, and even more preferably 40% by weight. On the other hand, it is preferable to use a coating liquid with a metal oxide particle content of 90% by weight or less. The metal oxide particle content of the coating liquid is more preferably 80% by weight or less. The fewer metal oxide particles there are, the easier it is to fix the metal oxide particles to the film.

[0038] The organic solvent may be any organic solvent capable of dispersing metal oxide particles. Examples of the organic solvent include alcohols, glycols, ethers, esters, and ketones. It is preferable to contain two or more of these, and more preferably three or more. By containing solvents with different skeletons, film formation becomes easier.

[0039] The higher the solids concentration of the coating solution, the less solvent needs to be transported, and therefore the lower the transportation costs. Therefore, from the viewpoint of reducing transportation costs, the solids concentration is preferably 0.5% by weight or more, and more preferably 1% by weight or more. On the other hand, the lower the solids concentration, the lower the viscosity of the coating solution, making transportation and handling easier. Therefore, the solids concentration is preferably 50% by weight or less.

[0040] The solid content of the coating solution is adjusted according to the desired film thickness. For example, an antireflection film having a low refractive index film thickness of 50 to 150 nm theoretically has the highest antireflection performance. By using a coating solution having a solid content of 5% by weight or less, a thin film having a thickness of 50 to 150 nm can be formed. The average particle size of the low refractive index particles is preferably smaller than the thickness of the low refractive index film. Such low refractive index particles are unlikely to be exposed from the surface of the low refractive index film, thereby increasing the scratch resistance of the film. Therefore, the average particle size of the low refractive index particles is preferably 150 nm or less.

[0041] The thicker the film, the higher the hardness of the film. The higher the solids concentration of the coating solution, the thicker the film. Therefore, from the viewpoint of increasing the hardness of the film, the solids concentration is preferably 30% by weight or more, and more preferably 40% by weight or more.

[0042] A method for producing a coating liquid is described below. First, a dispersion liquid of metal oxide particles is prepared. A photopolymerization initiator is attached to the metal oxide particles. This prepares a dispersion liquid of metal oxide particles with the photopolymerization initiator attached (hereinafter, initiator-attached particles). The coating liquid is prepared by mixing the dispersion liquid of initiator-attached particles with an organic binder. By attaching the photopolymerization initiator to the metal oxide particles before mixing with the organic binder, the amount of photopolymerization initiator attached to the metal oxide particles in the coating liquid is increased.

[0043] After adding a photopolymerization initiator to a dispersion of metal oxide particles, it is preferable to adhere the photopolymerization initiator to the metal oxide particles by, for example, holding the dispersion for a long period of time. The holding time for the dispersion is preferably 5 hours or more, more preferably 10 hours or more. Furthermore, if the temperature of the dispersion is -10 to 80°C, costs will be low.

[0044] The more metal oxide particles there are in the solid content of the dispersion of initiator-attached particles, the more easily the photopolymerization initiator adheres to the metal oxide particles. Therefore, the content of metal oxide particles in the solid content of the dispersion of initiator-attached particles is preferably 75 wt% or more, more preferably 80 wt% or more, and even more preferably 85 wt% or more. This metal oxide particle content is even more preferably 90 wt% or more.

[0045] Furthermore, the lower the weight ratio of the weight of the photopolymerization initiator added to the weight of the metal oxide particles in the dispersion (weight of photopolymerization initiator / weight of metal oxide particles), the easier it is to impart the functionality of the metal oxide particles to the film. Therefore, this weight ratio is preferably 15 or less, and more preferably 13 or less. On the other hand, the more photopolymerization initiator is added, the easier it is for the photopolymerization initiator to come into contact with the metal oxide particles, and the more photopolymerization initiator is likely to adhere to the metal oxide particles. Therefore, this weight ratio is preferably 2 or more, more preferably 5 or more, and even more preferably 6.5 or more.

[0046] Unit adhesion amount is 1.5 x 10 -26 mol / nm 2It is preferable to attach the photopolymerization initiator to the metal oxide particles so that the unit attachment amount is 7×10 -26 mol / nm 2 More than 10 x 10 is preferable. -26 mol / nm 2 The above is more preferable.

[0047] The characteristics and forms of the organic binder described above can be applied to the organic binder.

[0048] A film-coated substrate can be produced by forming a film on a substrate using the coating liquid described above. Specifically, the coating liquid is applied to the substrate, and then the coating liquid is dried and cured to obtain a film-coated substrate. Examples of coating methods include spin coating, bar coating, gravure coating, and slit coating.

[0049] The substrate to be used can be selected depending on the application. For optical applications, a transparent substrate is preferable. Examples of substrates include glass, plastic films, substrates with hard coat films, and substrates with high refractive index films. Examples of plastic films include polyethylene terephthalate (PET), triacetyl cellulose (TAC), acrylic, polycarbonate, and cycloolefin polymer. Forming a low refractive index film on a high refractive index film can improve the anti-reflection performance of the film-coated substrate. When the high refractive index film and the low refractive index film are thin (for example, their thicknesses are in the range of 50 to 150 nm), forming a hard coat (HC) film on the underside of these films can increase the hardness and scratch resistance of the film-coated substrate. Hereinafter, paints for forming HC films will be referred to as HC paints.

[0050] Drying refers to the removal of the solvent by volatilization. The higher the drying temperature, the shorter the drying time. Furthermore, the solvent is less likely to remain in the film, resulting in a dense film. Therefore, a drying temperature of 60°C or higher is preferable. On the other hand, if the drying temperature is 120°C or lower, the substrate is less likely to deform. Furthermore, it is easy to handle industrially. A drying temperature of 100°C or lower is more preferable, and 90°C or lower is even more preferable. By curing the coating liquid after drying, production efficiency is improved. In the curing process, the dried coating liquid is irradiated with ultraviolet light. By using ultraviolet light with an irradiation wavelength identical to the absorption wavelength of the photopolymerization initiator, the functional groups are more likely to react. The irradiation dose is 200 to 600 mJ / cm 2 , illumination intensity is 100~2000mW / cm 2 This strength is preferable. The scratch resistance of the film is high. Irradiating the film with ultraviolet light in an N2 atmosphere further increases the scratch resistance of the film.

[0051] Examples of the present invention will be specifically described below.

[0052] [Example 1] <Step of Preparing Metal Oxide Particles> First, metal oxide particles were prepared as follows. An aqueous dispersion of metal oxide particles with a solids concentration of 20% by mass (aqueous dispersion of silica-based particles (P-5-2)) was obtained using a method similar to that described in Example 7 of JP 2012-30489 A, "Preparation of Silica-Based Hollow Microparticles (P-5)." A methanol dispersion of metal oxide particles with a solids concentration of 20% by mass was prepared by replacing the solvent of this aqueous dispersion with methanol using an ultrafiltration membrane. 0.4 g of 28% by mass aqueous ammonia and 4.0 g of pure water were added to 200 g of this methanol dispersion, followed by stirring at 25°C for 0.5 hours. 4 g of γ-methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) as a surface treatment agent (10 parts by mass per 100 parts by mass of silica particles) was added to the methanol dispersion, and the methanol dispersion was stirred at 50°C for 6 hours to surface-treat the hollow particles. Using an evaporator, the solvent of the methanol dispersion was replaced with methyl isobutyl ketone (MIBK) to prepare an MIBK dispersion of metal oxide particles (i.e., a dispersion of metal oxide particles) with a solid content concentration of 20 wt %.

[0053] <Attachment process> A mixture was obtained by mixing 30.00 g of the metal oxide particle dispersion with 0.33 g of a photopolymerization initiator (Omnirad (registered trademark) TPO H manufactured by IGM RESINS BV [having the structure of formula (A), where two of the three Rs are phenyl groups and one is trimethylbenzoyl group]). The mixture was stirred at 25°C for 20 hours or more to attach the photopolymerization initiator to the metal oxide particles. In other words, a dispersion of initiator-attached particles was prepared. The photopolymerization initiator accounted for 5.2 wt% of the solid content of this dispersion.

[0054] The dispersion of initiator-adhered particles was measured using the following methods (1) to (3). Table 1 also shows the measurement results of other examples and comparative examples.

[0055] (1) Average particle size, specific surface area, and unit adhesion amount The dispersion of initiator-attached particles was diluted to 0.01% by mass with methanol and then dried on a collodion film in a copper cell for an electron microscope. Next, this was photographed at a specified magnification (100,000 to 1,000,000 times) using a field emission transmission electron microscope (HF5000, manufactured by Hitachi High-Technologies Corporation). 300 particles were randomly selected from the obtained photographic projection (TEM photograph), and the area of ​​the metal oxide particles was determined by image processing of these particles. The circle equivalent diameter was calculated from this area. The average value of the circle equivalent diameter was taken as the average particle diameter (D) of the metal oxide particles. This average particle diameter (D) was substituted into formula (*1) to determine the specific surface area (SA [nm 2 / g) was calculated.

[0056] SA=6000 / (SG×D) (※1) SG is the density of metal oxide particles (g / nm 3 ) indicates the mass fraction (SG). SG is calculated as follows: First, the weight concentration of each component (hereinafter referred to as the constituent components) that makes up the metal oxide particles (the weight concentrations of component A, component B, component C, etc. are designated as A mass%, B mass%, C mass%, etc., respectively) is measured and calculated using composition analysis (ICP-OES) described below. Next, SG is calculated using the following formula (*2).

[0057] SG=((A weight% / ρ A )+(B weight% / ρ B )+(C weight% / ρ C )+···) -1 ...Formula (*2) Note that ρ in the formula A , ρ B , ρ CThe symbols indicate the density of each component (Component A, Component B, Component C...). For example, 2.2 for silica, 3.9 for alumina, 3.7 for arsenic(III) oxide, 1.9 for boron oxide, 8.9 for bismuth(III) oxide, 8.2 for cadmium oxide, 6.1 for cobalt(II) oxide, 5.2 for iron(III) oxide, 5.9 for gallium(III) oxide, 4.2 for germanium(II) oxide, 7.2 for indium oxide, 4.5 for niobium(V) oxide, 9.5 for lead(II) oxide, 5.2 for antimony(V) oxide, 6.9 for tin oxide, 3.0 for titania (anatase), 4.3 for titania (rutile), 5.8 for vanadium(II) oxide, 5.6 for zinc oxide, and 6.0 for zirconia (unit: g / nm 3 ).

[0058] The SG of metal oxide particles with internal voids is calculated using the following formula (*3). The density of the voids is 0 g / nm 3 was used.

[0059] SG = (Volume fraction of shell part × Density of shell part) + (Volume fraction of void part × Density of void part) = (Volume fraction of shell part × Equation (※2)) Equation (※3) Here, the volume fraction of the shell = (volume of the shell / volume of the metal oxide particle). The shell is the part of the metal oxide particle other than the voids (i.e., volume of the metal oxide particle = volume of the shell + volume of the voids). The density of the shell can be measured and calculated in the same way as the SG of metal oxide particles without voids. In other words, the density of the shell can be calculated using formula (*2).

[0060] The volume of the metal oxide particles (4 / 3πr 3 ) and the volume of the void (4 / 3πr v 3 ) was calculated as follows: The area of ​​the metal oxide particle (4πr 2 ) and the area of ​​the gap (4πr v 2 ) to calculate the equivalent circle diameter (half of the equivalent circle diameter is the radius [r and r vThe volume of the metal oxide particles and the volume of the voids were calculated from the circle-equivalent diameter. 300 particles were randomly selected from the photographic projection (TEM photograph), and the area of ​​the metal oxide particles and the area of ​​the voids were calculated by image processing of these particles, and the circle-equivalent diameter was calculated from these areas. The boundary between the voids and the shell was determined from the contrast difference in the TEM photograph.

[0061] Specific surface area (SA [nm 2 / g) into the formula (※4) to obtain the unit adhesion amount (CIA [mol / nm 2 ) was calculated.

[0062] CIA=CP / SA formula (※4) CP indicates the amount (mol / g) of photopolymerization initiator attached per 1 g of metal oxide particles. CP was determined by the following composition analysis (ICP-OES).

[0063] (Composition analysis ICP-OES) First, the initiator-adhered particle dispersion was centrifuged using a small ultracentrifuge (Hitachi Koki Co., Ltd., CS150GXL) at 10°C and 1,370,000 rpm (1,000,000 G) to separate the precipitate (containing the metal oxide particles and the photoinitiator attached to them) and the supernatant (containing the photoinitiator not adsorbed to the metal oxide particles). The supernatant was then removed by decantation. Next, the main solvent (MIBK) of the dispersion was added to the precipitate in an amount equal to or greater than the supernatant, and the added main solvent was then removed by decantation. The addition of the main solvent and decantation were repeated three or more times to remove the photoinitiator not adsorbed to the metal oxide particle surface, resulting in a separated product. The separated product was then dried at 200°C for three hours to remove the remaining solvent and produce a solid. The weight concentration of the constituent components in the solid content (metal oxide particles) and the amount of phosphorus in the metal oxide were measured using an ICP-OES (Shimadzu Corporation, ICPS-8100). CP was calculated by converting 1 mol of phosphorus to 1 mol of photopolymerization initiator.

[0064] (2) Dispersibility in hydrophobic solvents The dispersion of initiator-attached particles was diluted 20 times with the main solvent (MIBK), and 1.0 g was weighed out. 0.5 g of toluene was added to this to prepare a measurement sample. The measurement sample was filled into a quartz cell with an optical path length of 1 mm, and the liquid haze was measured using a haze meter (NDH-5000, manufactured by Nippon Denshoku Industries Co., Ltd.). The amount of toluene added was increased by 0.5 g increments until the liquid haze reached 15% or more, and the same measurement was repeated. The amount of toluene added (toluene added amount) at which the liquid haze reached 15% or more was determined. Note that the larger the amount of toluene added, the better the dispersibility in hydrophobic solvents.

[0065] (3) Measurement of the amount of bonding functional groups The surface treatment agent suspended in the initiator-attached particle dispersion was removed by ultrafiltration using 1 kg of methanol. The solid content at 200°C (C 200℃ ) and 1000℃ solid concentration (C 1000℃ ) was substituted into the following formula (*5) to calculate the amount of bonding functional groups. The metal oxide particle content in the solid content was calculated using the following formula (*6).

[0066] Amount of binding functional group=(C 200℃ -C 1000℃ ) / (C 1000℃ )...expression (*5) Metal oxide particle content in solids = C 1000℃ / C 200℃ ...Formula (*6)

[0067] (C 200℃ (measurement of 3 g of the dispersion liquid from which the floating surface treatment agent had been removed was weighed into a heat-resistant container and dried at 200°C for 3 hours to obtain a 200°C solid. The 200°C solid was cooled to room temperature in a desiccator and then weighed. The weight of the 200°C solid was divided by the weight (3 g) before drying to obtain C 200℃ was calculated.

[0068] (C 1000℃ (measurement of The dispersion liquid from which the floating surface treatment agent had been removed was weighed out in an amount of 3 g and placed in a heat-resistant container. The liquid was dried at 1000°C for 1 hour to obtain a 1000°C solid. The 1000°C solid was cooled to room temperature in a desiccator, and then weighed. The weight of the 1000°C solid was divided by the weight of the dispersion liquid (3 g) to obtain the C 1000℃ was calculated.

[0069] <Painting process> A coating solution (LR paint) was prepared by mixing a dispersion of initiator-attached particles with an organic binder. That is, 8.18 g of a dispersion of initiator-attached particles, 1.07 g of a multifunctional acrylate monomer (Kyoeisha Chemical Co., Ltd. Light Acrylate DPE-6A) as a first organic binder, 0.12 g of a bifunctional acrylate monomer (Tomoe Engineering Co., Ltd. SR-238F) as a second organic binder, 0.05 g of reactive silicone oil for water repellent materials (Shin-Etsu Chemical Co., Ltd. KF-2012) as a surface conditioner, 0.37 g of silicone-modified polyurethane acrylate (Mitsubishi Chemical Corporation Shikoh (registered trademark) UT-4314, solids concentration 30% by mass), and organic solvents [isopropyl alcohol (IPA) 64.72 g, methyl isobutyl ketone (MIBK) 9.50 g, isopropyl glycol (I-PG) 16.00 g] were mixed to prepare a coating liquid (LR paint) with a solids concentration of 3% by mass. The preparation conditions of the coating liquid are shown in Table 2 together with other examples and comparative examples.

[0070] In the above (1) and (2), a coating liquid was used instead of the dispersion liquid of initiator-attached particles, and a mixed solvent (IPA:MIBK:I-PG=68:16:16 [weight ratio]) was used instead of MIBK as the main solvent, and similar measurements and calculations were carried out. The measurement and calculation results of other examples and comparative examples are also shown in Table 3. In addition, the above (C 200℃ Measurement of (C 1000℃ In the measurement of C, the "coating liquid" was used instead of the "dispersion liquid from which the floating surface treatment agent was removed." 200℃ and C 1000℃ was calculated. C 200℃ is the solid content concentration of the coating solution, which was 3% by weight in all Examples and Comparative Examples. 200℃ and C 1000℃was substituted into the following formulas (*7) and (*8) to determine the content of metal oxide particles in the solid content of the coating liquid and the content of organic binder in the solid content of the coating liquid, respectively.

[0071] Content of metal oxide particles in the solid content of the coating solution = C 1000℃ / C 200℃ ...Formula (*7) The content of organic binder in the solid content of the coating liquid = (C 200℃ -C 1000℃ ) / C 200℃ ...Formula (*8)

[0072] Next, an HC paint was prepared as follows: 2.00 g of DPE-6A, 1.00 g of an acrylic silicone leveling agent (NSH-8430HF manufactured by Kusumoto Chemicals Co., Ltd.), 2.10 g of a photopolymerization initiator (Omnirad 184 manufactured by IGM Resins BV), 10.00 g of acetone, and 44.90 g of propylene glycol monomethyl ether were mixed to prepare a coating solution (HC paint) with a solids concentration of 42.0 mass%.

[0073] Using the coating liquid and the HC paint, a film-coated substrate was formed as follows.

[0074] <Creating a film-coated substrate> The HC paint was applied to a TAC film (FT TD80UL, manufactured by Fujifilm Corporation, thickness 80 μm) using a bar coater (#10). The HC paint was then dried at 80°C for 120 seconds. 2 The dried HC coating was irradiated with ultraviolet light (curing the dried HC coating) to form an HC film. The coating liquid was then applied onto the HC coating using a bar coater (#4). The coating liquid was dried at 80°C for 120 seconds to form an LR film. In an N2 atmosphere, a Heraeus UV lamp (using an H bulb) was used to apply 400 mJ / cm2. 2The dried LR film was irradiated with ultraviolet light (curing the dried LR film) to produce a film-coated substrate. The thickness of the HC film at this time was approximately 5 μm, and the thickness of the cured LR film was approximately 100 nm. The thickness of the HC film was measured using a linear gauge sensor (GS-8313, manufactured by Ono Sokki Co., Ltd.), and the thickness of the LR film was calculated by simulation from the spectral reflectance obtained using a microscopic film thickness meter (OPTM-F1, manufactured by Otsuka Electronics Co., Ltd.).

[0075] <Evaluation of film-coated substrate> The film-coated substrate was measured by the following methods (4) to (6). Table 3 also shows the measurement results of other examples and comparative examples.

[0076] (4) Appearance The surface of the film-coated substrate was visually observed and evaluated according to the following criteria.

[0077] Evaluation criteria; Almost no defects in appearance such as whitening, streaks, unevenness, or bleeding out are observed on the surface: ○ Poor appearance such as whitening, streaks, unevenness, and bleeding out was clearly observed on the surface: ×

[0078] (5)Reflectance The back side of the film-coated substrate was painted black to prepare a measurement sample. The spectral reflectance of the measurement sample was measured using a microfilm thickness meter (OPTM-F1, manufactured by Otsuka Electronics Co., Ltd.). For the spectral reflectance curve with wavelengths of 400 to 800 nm, the lowest spectral reflectance value near a wavelength of 550 nm (520 to 580 nm) was used as the reflectance of the film-coated substrate for a downwardly convex spectrum, and the highest spectral reflectance value near a wavelength of 650 nm (620 to 680 nm) was used for an upwardly convex spectrum.

[0079] (6) Scratch resistance Using a Gakushin-type friction fastness tester (AB-301 manufactured by Tester Sangyo Co., Ltd.), #0000 steel wool was placed in contact with the film surface and slid 10 times under a load of 20 levels (150 gf / cm 2 , 200gf / cm 2 , 300gf / cm 2 ...[From 200g it is 100gf / cm2 increments) 2000gf / cm 2 This procedure was carried out at a load of 300 gf / cm2 (up to 6 scratches). At each stage, this procedure was carried out using a different film-coated substrate. 2 If there are six or more scratches, the strength is 200gf / cm 2 ) was defined as the maximum load (scratch resistance) at which six or more scratches did not appear on the film.

[0080] Furthermore, the ratio of scratch resistance (scratch resistance ratio) to the case where the unit adhesion amount was 0 (the <adhesion step> was not performed) was determined as follows. For each example, a coating liquid was prepared without the <adhesion step>, and a film-coated substrate was produced using this coating liquid in the same manner as in the examples. However, when preparing the coating liquid without the <adhesion step>, a photopolymerization initiator was added in the <paint-making step> so that the composition of the coating liquid without the <adhesion step> was the same as the composition of the coating liquid prepared in the corresponding example. The scratch resistance of this film-coated substrate was evaluated in the same manner as in the examples. The value (scratch resistance ratio) was calculated by dividing the scratch resistance of the corresponding example by this scratch resistance.

[0081] [Example 2] This example is the same as Example 1, except for the following differences: In the mixing step, the amount of photopolymerization initiator mixed was 0.19 g; in the adhering step, the photopolymerization initiator accounted for 3.1 wt % of the solid content of the dispersion of initiator-adhered particles obtained; and in the coating step, the amount of the dispersion of initiator-adhered particles mixed was 8.14 g, and the amount of Omnirad (registered trademark) TPO H mixed was 0.04 g.

[0082] [Example 3] This example is the same as Example 1, except for the following differences: In the mixing step, the amount of photopolymerization initiator mixed was 0.62 g; in the adhering step, the photopolymerization initiator accounted for 9.4 wt % of the solid content of the dispersion of initiator-adhered particles obtained; and in the coating step, the amount of initiator-adhered particle dispersion mixed was 8.27 g.

[0083] [Example 4] This example is similar to Example 1, except for the following differences: In the step of preparing metal oxide particles, an MIBK dispersion of metal oxide particles with a solids concentration of 20 wt% was prepared by the same method as in the "step of preparing hollow particles" described in Example 5 of Japanese Patent Application No. 2022-041308. This MIBK dispersion was used as the dispersion of metal oxide particles in the adhesion step.

[0084] [Example 5] This example is the same as Example 1, except for the following differences: In the adhesion step, Omnirad 819 (BAPO) manufactured by IGM RESINS BV (having the structure of formula (A), one phenyl group and two triethylbenzoyl groups among the three Rs) was used as the photopolymerization initiator; in the paint-making step, 90.22 g of MIBK was mixed as the organic solvent.

[0085] [Example 6] This example is similar to Example 1, except for the following differences: A PGME dispersion of metal oxide particles with a solid content of 20 wt% was prepared by the same method as in "Preparation of first surface-treated particles" and "Preparation of second surface-treated particles" described in Example 1 of Japanese Patent Application No. 2023-059611. This PGME dispersion was used as the dispersion of metal oxide particles in the adhesion step.

[0086] [Example 7] This example is similar to Example 1, except for the following differences. Specifically, in the adhesion step, an MIBK dispersion of metal oxide particles prepared by the following method was used as the metal oxide particle dispersion. A methanol dispersion of metal oxide particles with a solids concentration of 20% by mass was prepared by replacing the solvent of an aqueous dispersion of metal oxide particles (Cataloid® SI-80P, manufactured by JGC Catalysts and Chemicals, average particle size approximately 100 nm) with methanol using an ultrafiltration membrane. 0.4 g of 28% by mass aqueous ammonia and 4.0 g of pure water were added to 200 g of this methanol dispersion, followed by stirring at 25°C for 0.5 hours. 4 g of γ-methacryloxypropyltrimethoxysilane (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) as a surface treatment agent (10 parts by mass per 100 parts by mass of silica particles) was added to the methanol dispersion, and the methanol dispersion was stirred at 50°C for 6 hours, thereby surface-treating the metal oxide particles. The solvent of the methanol dispersion was replaced with methyl isobutyl ketone (MIBK) using an evaporator to prepare an MIBK dispersion of metal oxide particles with a solid content concentration of 20 wt %.

[0087] [Comparative Example 1] This comparative example differs from Example 1 in the following respects: In the coating process, 0.09 g of Omnirad TPO-H was mixed as a photopolymerization initiator together with the dispersion of initiator-attached particles and the organic binder.

[0088] Comparative Example 2 This comparative example differs from Example 2 in the following respects: In the adhesion process, the amount of photopolymerization initiator mixed was 0.06; the photopolymerization initiator accounted for 1.0 wt% of the solid content of the dispersion of initiator-attached particles; 8.11 g of this dispersion of initiator-attached particles was used in the paint-making process; and 0.07 g of Omnirad TPO H was mixed as the photopolymerization initiator in the paint-making process.

[0089] Comparative Example 3 This comparative example differs from Example 2 in the following respects. Specifically, an IPA dispersion of metal oxide particles prepared by the following method was used as the metal oxide particle dispersion in the adhesion step. An aqueous dispersion of metal oxide particles with a solids concentration of 20% by mass (aqueous dispersion of silica-based fine particles (P-5-2)) was obtained by a method similar to the "Preparation of Silica-Based Hollow Fine Particles (P-5)" described in Example 7 of JP 2012-30489 A. The solvent of this aqueous dispersion was replaced with methanol using an ultrafiltration membrane, thereby preparing a methanol dispersion of metal oxide particles with a solids concentration of 20% by mass. 0.4 g of 28% by mass aqueous ammonia and 4.0 g of pure water were added to 200 g of this methanol dispersion, and the mixture was stirred at 25°C for 0.5 hours. The metal oxide particles were surface-treated by adding 4 g (10 parts by mass per 100 parts by mass of silica particles) of tetraethoxysilane (Tama Chemicals Co., Ltd., ethyl orthosilicate ES28) as a surface treatment agent to the methanol dispersion, and then stirring the methanol dispersion for 6 hours at 50° C. Using an evaporator, the solvent of the methanol dispersion was replaced with IPA, preparing an IPA dispersion of metal oxide particles with a solids concentration of 20 wt%.

[0090] [Table 1]

[0091] [Table 2]

[0092] [Table 3]

Claims

1. The composition includes metal oxide particles having a photocurable functional group, a photopolymerization initiator, and an organic solvent, The number of moles of the photopolymerization initiator attached to the metal oxide particles is 1.5×10 relative to the unit surface area of ​​the metal oxide particles. －２６ mol / nm ２ That's all. Dispersion of metal oxide particles.

2. 2. The dispersion of claim 1, wherein the photoinitiator has a structure of formula *. R 3 P=O ・・・Formula* where R is a hydrocarbon group and R may be the same or different.

3. The composition includes metal oxide particles having a photocurable functional group, an organic binder having a photocurable functional group, a photopolymerization initiator, and an organic solvent, The number of moles of the photopolymerization initiator attached to the metal oxide particles is 1.0 × 10 per unit surface area of ​​the metal oxide particles. －２５ mol / nm ２ The above-described coating solution for forming a film.

4. The solid content of the coating solution is 0.5 to 20% by weight, the content of the metal oxide particles in the solid content of the coating liquid is 10 to 80 wt %; the content of the organic binder in the solid content of the coating liquid is 30 to 90 wt %; 4. The coating liquid according to claim 3, wherein the content of the photopolymerization initiator in the solid content of the coating liquid is 1 to 10% by weight.

5. preparing a dispersion of metal oxide particles; attaching a photopolymerization initiator to the metal oxide particles; and mixing the dispersion with an organic binder.

6. 1.5 × 10 per unit surface area of ​​the metal oxide particles －２６ mol / nm ２ 6. The method for producing a coating liquid according to claim 5, wherein the photopolymerization initiator is attached.

7. A method for producing a film-coated substrate, comprising applying the coating liquid according to claim 3 onto a substrate.

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