Dispersion liquid, dispersion liquid set, low refractive index layer, optical member, and optical device

Abstract

Provided is a dispersion liquid with which a low refractive index layer can be produced that achieves both a low refractive index and a low haze value.　The dispersion liquid, in which silica gel particles are dispersed in a dispersion medium, is characterized in that the silica gel particles have a D50 particle diameter of less than 130 nm, a pore diameter of less than 15 nm, and a specific surface area of at least 500 m2 / g.

Description

Dispersion, dispersion set, low refractive index layer, optical component, and optical device

[0001] This disclosure relates to dispersions, dispersion sets, low refractive index layers, optical components, and optical devices.

[0002] In optical devices, for example, an air layer with a low refractive index is used as a total reflection layer. Specifically, for example, in an image display device, each optical film component (e.g., a light guide plate and its adjacent functional layer) is laminated with an air layer in between. However, if each component is separated by an air layer, the image display device may become larger, and problems such as component bending may occur.

[0003] Therefore, it has been proposed to use a low refractive index layer instead of an air layer (Patent Documents 1 and 2).

[0004] Patent No. 6606518 Patent No. 6599699

[0005] In low-refractive-index layers, a higher porosity tends to result in a lower refractive index (i.e., closer to the refractive index of air). On the other hand, a high porosity tends to result in a higher haze value (i.e., lower transparency) in low-refractive-index layers. Therefore, achieving both a low refractive index and a low haze value simultaneously is difficult in low-refractive-index layers.

[0006] Therefore, the present disclosure aims to provide a dispersion capable of producing a low refractive index layer that achieves both a low refractive index and a low haze value, as well as a dispersion set using the same, a low refractive index layer, an optical component, and an optical device.

[0007] To achieve the above objective, the dispersion of the present disclosure is a dispersion in which silica gel particles are dispersed in a dispersion medium, wherein the silica gel particles have a D50 particle size of less than 130 nm, a pore diameter of less than 15 nm, and a specific surface area of ​​500 m². ２ It is characterized by being 1 / g or more.

[0008] The dispersion set of the present disclosure is characterized by comprising the dispersion of the present disclosure and a catalyst-containing liquid containing a catalyst for chemically binding the particles of the dispersion.

[0009] The low refractive index layer of the present disclosure is characterized by being obtained by coating and drying the dispersion of the present disclosure.

[0010] The optical component of this disclosure is characterized by including a low refractive index layer of this disclosure.

[0011] The optical apparatus of this disclosure is characterized by including an optical component of this disclosure.

[0012] According to this disclosure, it is possible to provide a dispersion capable of producing a low refractive index layer that achieves both a low refractive index and a low haze value, as well as a dispersion set using the same, a low refractive index layer, an optical component, and an optical device.

[0013] Next, we will provide a more detailed explanation of this disclosure with examples. However, this disclosure is not limited in any way by the following explanation.

[0014] In this disclosure, the "dispersion medium" does not necessarily have to dissolve the gel or its pulverized material, particles, etc. For example, the gel or its pulverized material, etc. may be dispersed or precipitated in the dispersion medium. For example, an organic solvent may be used as the dispersion medium in the dispersion liquid of this disclosure.

[0015] In this disclosure, unless otherwise specified, "mass%" and "weight%" may be interpreted as interchangeable, and "parts of mass" and "parts of weight" may be interpreted as interchangeable.

[0016] Furthermore, in this disclosure, "on top of" or "on the surface" may refer to a state of direct contact with the top of or on the surface, or it may refer to a state of contact with other layers, etc.

[0017] [1. Dispersion] As described above, the dispersion of the present disclosure is a dispersion in which silica gel particles are dispersed in a dispersion medium, wherein the silica gel particles have a D50 particle size of less than 130 nm, a pore diameter of less than 15 nm, and a specific surface area of ​​500 m². ２ It is characterized by being 1 / g or more.

[0018] [1-1. Silica Gel Particles] As described above, in the dispersion of the present disclosure, the silica gel particles (hereinafter sometimes simply referred to as "particles") have a D50 particle size of less than 130 nm, a pore diameter of less than 15 nm, and a specific surface area of ​​500 m². ２It is 1 / g or more.

[0019] As mentioned above, in low refractive index layers, a higher porosity tends to result in a lower refractive index, but also a higher haze value. For this reason, it is difficult to achieve both a low refractive index and a low haze value in a low refractive index layer. The inventors have conducted extensive research to solve this problem and have arrived at the present disclosure based on the following findings (1) to (4). (1) The voids between particles forming the low refractive index layer are the cause of the increase in haze. (2) Therefore, by minimizing the voids between particles forming the low refractive index layer and maximizing the voids within the particles, it is possible to suppress the increase in haze while maintaining a high porosity in the low refractive index layer. In this way, it becomes possible to achieve both a low refractive index and a low haze value in the low refractive index layer. (3) In order to minimize the voids between particles forming the low refractive index layer, the particle size should be made as small as possible. That is, the particle size in the dispersion of the present disclosure should be made as small as possible. (4) In order to maximize the number of voids within the particles that form the low refractive index layer, the pore diameter of the particles should be made as small as possible, and the specific surface area of ​​the particles should be made as large as possible. That is, the pore diameter of the particles in the dispersion of the present disclosure should be made as small as possible, and the specific surface area of ​​the particles should be made as large as possible.

[0020] In the dispersion of this disclosure, in order to make the pore size of the particles as small as possible, the silica gel, which is the raw material for the particles, can be crushed to the smallest possible size to form the particles. The crushing method for this purpose is not particularly limited, but for example, it is as described in [1-2. Method for producing the dispersion] below. In this disclosure, the D50 particle size of the particles is less than 130 nm as described above, and may be, for example, 120 nm or less, 100 nm or less, 70 nm or less, or 40 nm or less. The lower limit of the D50 particle size of the particles is not particularly limited, but may be, for example, 1 nm or more, 5 nm or more, 10 nm or more, 30 nm or more, or 50 nm or more. The D50 particle size of the particles may be, for example, 1 nm or more and less than 130 nm, 30 to 100 nm, or 50 to 80 nm.

[0021] In the present disclosure, the particle size can be measured by, for example, a laser diffraction particle size analyzer or a dynamic light scattering particle size analyzer (DLS). However, from the target particle size, in the present disclosure, it is preferable to measure with a dynamic light scattering particle size analyzer (DLS) because a more accurate value can be calculated. By measuring the particle size distribution by these measurement methods, the particle size D50 of the particles can be calculated. D50 is a value also called the median diameter and is the particle diameter at the median of the particle distribution, corresponding to an integrated frequency of 50%.

[0022] In the dispersion liquid of the present disclosure, in order to make the pore diameter of the particles as small as possible and the specific surface area of the particles as large as possible, for example, when producing (synthesizing) silica gel, which is the raw material of the particles, a catalyst with a small molecular volume may be used. The catalyst will be described in detail later.

[0023] In the dispersion liquid of the present disclosure, the pore diameter of the particles is less than 15 nm as described above, and may be, for example, 14 nm or less, 13 nm or less, 12 nm or less, 10 nm or less, 5 nm or less, or 1 nm or less. The lower limit value of the pore diameter of the particles is not particularly limited, and may be, for example, 0.01 nm or more, 0.1 nm or more, 1 nm or more, 5 nm or more, or 8 nm or more. The pore diameter of the particles may be, for example, 0.01 nm or more and less than 15 nm, 0.1 to 14 nm, 1 to 12 nm, 1 to 10 nm, or 1 to 8 nm. In the present disclosure, the pore diameter of the particles can be measured by the following measurement method.

[0024] (Measurement method of particle pore diameter) Regarding the pore diameter of the particles, for 2 g of the dried product of the above dispersion liquid, evaluation analysis is performed by measuring the gas adsorption amount using a specific surface area / pore distribution measuring device (manufactured by MicrotracBEL Corporation, trade name BELSORP-miniX). The dried product of the above dispersion liquid is not particularly limited as long as the solvent in the gel is completely dried (removed). However, in the examples described later, after drying at 80 °C for 24 hours under 0.02 MPa or less, the dried product obtained by drying at 150 °C for 1 hour or more before measurement is used. The pore diameter of the particles is measured three times using the above dried product as a sample, and the average value of the three measurement values is taken as the pore diameter of the particles.

[0025] In the dispersion of the present disclosure, the specific surface area of the particles is, as described above, 500 m ２ / g or more. For example, it may be 550 m ２ / g or more, 600 m ２ / g or more, m ２ / g or more, or 650 m ２ / g or more. The upper limit value of the specific surface area of the particles is not particularly limited. For example, it may be 5000 m ２ / g or less, 2000 m ２ / g or less, 1000 m ２ / g or less, 900 m ２ / g or less, or 800 m ２ / g or less. The specific surface area of the particles may be, for example, 500 to 5000 m ２ / g, 500 to 2000 m ２ / g, 550 to 1000 m ２ / g, 550 to 1000 m ２ / g, or 600 to 1000 m ２ / g. In the present disclosure, the specific surface area of the particles can be measured by the following measurement method.

[0026] (Measurement method of specific surface area of particles) For the specific surface area of particles, evaluation analysis is performed by measuring the gas adsorption amount using a specific surface area / pore distribution measuring device (manufactured by MicrotracBEL Corporation, trade name BELSORP-miniX) for 2 g of the dried product of the above dispersion. The dried product of the above dispersion is not particularly limited as long as the solvent in the gel is completely dried (removed). In the examples described later, a dried product obtained by drying at 8℃ for 24 hours at 0.02 MPa or less and then drying at 150℃ for 1 hour or more before measurement was used. The specific surface area of the particles was measured 3 times using the above dried product as a sample, and the average value of the 3 measurement values was taken as the specific surface area of the particles.

[0027] In the dispersion of this disclosure, the particles are, for example, condensates of raw materials containing alkoxysilane. The alkoxysilane may be a saturated alkoxysilane or an unsaturated alkoxysilane having UV-polymerizable unsaturated groups. The saturated alkoxysilane may be a monomer, an oligomer, or a combination thereof. Specific examples of saturated alkoxysilane monomers include methyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, diethoxydimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, and combinations thereof. As saturated alkoxysilane oligomers, condensate polymers of the above monomers are preferred. Saturated alkoxysilane oligomers are obtained by hydrolysis polymerization of monomers. The alkoxysilane is preferably an alkoxysilane having three or fewer functional groups (saturated bond functional groups). The unsaturated alkoxysilane may be a monomer, an oligomer, or a combination thereof. An unsaturated alkoxysilane monomer has an organic group having at least one double or triple bond and an alkoxyl group.

[0028] In the dispersion of this disclosure, the particles may be, for example, particles of a silsesquioxane condensate, which is a condensate of a raw material containing a trifunctional organosilicon compound. The following description will mainly focus on the case where the particles are particles of a silsesquioxane condensate, which is a condensate of a raw material containing a trifunctional organosilicon compound, but the particles in the dispersion of this disclosure are not limited to this.

[0029] The particles may be, for example, a condensate of a raw material consisting only of a trifunctional organosilicon compound, or a condensate of a raw material containing a trifunctional organosilicon compound and other monomers. The content of the trifunctional organosilicon compound in the raw material (monomer) may be, for example, 0.1 mol% or more, 10 mol% or more, 30 mol% or more, 50 mol% or more, or 90 mol% or more, for example, 100 mol% or less, 99 mol% or less, 90 mol% or less, 70 mol% or less, or 50 mol% or less, for example, 0.1 to 100 mol%, 1 to 99 mol%, 10 to 90 mol%, or 30 to 70 mol%.

[0030] The raw material (monomer) of the particles may, for example, include an organosilicon compound represented by the following formula (1). In this case, the raw material may or may not include other components. Since the organosilicon compound of the following formula (1) has hydroxyl groups, hydrogen bonding or intermolecular force bonding is possible, for example, through each hydroxyl group.

[0031]

[0032] In formula (1), for example, X is 2, 3, or 4, provided that at least a portion of the raw materials represented by formula (1) is a trifunctional organosilicon compound in which X is 3, and R １ R is a linear or branched alkyl group. １ The number of carbon atoms is, for example, 1 to 6, 1 to 4, or 1 to 2. Examples of the linear alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and so on, and examples of the branched alkyl group include an isopropyl group, an isobutyl group, and so on. X is, for example, 3 or 4.

[0033] Among the organosilicon compounds represented by formula (1) above, the trifunctional organosilicon compound in which X is 3 can be represented by the following formula (1'). In the following formula (1'), R １ R is the same as in formula (1) above, and is, for example, a methyl group. １When X is a methyl group, the organosilicon compound is tris(hydroxy)methylsilane. When X is 3, the organosilicon compound is, for example, a trifunctional silane having three functional groups.

[0034]

[0035] Furthermore, a specific example of a silicon compound represented by formula (1) is a compound in which X is 4. In this case, the silicon compound is, for example, a tetrafunctional silane having four functional groups.

[0036] The silicon compound may be, for example, a precursor that forms the silicon compound of formula (1) by hydrolysis. The precursor can be, for example, any compound that can produce the silicon compound by hydrolysis, and a specific example is the compound represented by the following formula (2).

[0037] In formula (2) above, for example, X is 2, 3, or 4, and R １ and R ２ Each of these is a linear or branched alkyl group, and R １ and R ２ They may be the same or different, R １ In the case where X is 2, they may be the same or different, and R ２ They may be the same or different from each other.

[0038] The aforementioned X and R １ For example, X and R in equation (1) described later. １ It is the same as R. ２ For example, R in equation (1) described later. １ The example above can be used as a reference.

[0039] A specific example of a silicon compound represented by formula (2) is the compound represented by the following formula (2') where X is 3. In the following formula (2'), R １ and R ２ These are the same as in equation (2) above. R １ and R ２When is a methyl group, the silicon compound is trimethoxy(methyl)silane (hereinafter also referred to as "MTMS"). The compound represented by formula (1') can be obtained by hydrolyzing the compound represented by the following formula (2').

[0040] If the silicon compound is a precursor represented by formula (2), the method for producing the particles contained in the dispersion of the present disclosure may include, for example, a step of hydrolyzing the precursor.

[0041] The particles in the dispersion of this disclosure (e.g., particles of silsesquioxane condensates) can be produced, for example, as a sol particle liquid in which particles are dispersed in a dispersion medium. The method for producing the sol particle liquid is not particularly limited, but for example, it can be produced by pulverizing silica gel in a dispersion medium. The method for producing the silica gel is also not particularly limited, but for example, it can be produced by a method similar to the method for producing a silicon compound gel described in International Publication No. 2019 / 065999 or International Publication No. 2019 / 065803. The temperature during the production of the silica gel in this disclosure is not particularly limited, but is preferably 50°C or less, or less than 50°C, and may be, for example, 40°C or less. When producing (synthesizing) the silica gel, which is the raw material for the particles, as described above, it is preferable to use a catalyst with a small molecular volume in order to make the pore size of the particles as small as possible and to make the specific surface area of ​​the particles as large as possible. The catalyst is, for example, a catalyst for polymerizing the raw material (monomer) of the silica gel to form the silica gel. The catalyst has a molecular volume of, for example, 150 cm³ in dimethyl sulfoxide (DMSO). ３ / moL or less, 140cm ３ It may be less than or equal to / mol. The molecular volume of the catalyst in dimethyl sulfoxide is not particularly limited in its lower limit, but for example, 100 cm³. ３ / moL or more, 110cm ３ / mol or more, or 120cm ３ It may be greater than or equal to / mol. The molecular volume of the catalyst in dimethyl sulfoxide is, for example, 100 to 150 cm³. ３ / mol, or 110-140cm３ The amount may be / mol. The catalyst may be, for example, a base catalyst. The base catalyst is not particularly limited, but examples include inorganic bases such as amines, sodium hydroxide, and potassium hydroxide, and organic bases such as diazabicycloundecene (DBU) and 1,5,7-triazabicyclo[4.4.0]deca-5-ene (TBD). Examples of the amine include alkylamines. Examples of the catalyst alkylamines are shown in Table 1 below.

[0042]

[0043] The method for pulverizing the silica gel in the dispersion medium is not particularly limited, but for example, the method described in Japanese Patent No. 7182358 may be used. The type of dispersion medium in the sol particle liquid is also not particularly limited, but for example, it may be the same as the dispersion medium for the sol particle liquid described in International Publication No. 2019 / 065999 or International Publication No. 2019 / 065803. Furthermore, the sol particle liquid can also be manufactured, for example, by the method described in "Reference Example 1" of the embodiments of this application described later.

[0044] [1-2. Method for Producing the Dispersion] The method for producing the dispersion of this disclosure is not particularly limited, but for example, it can be produced as follows.

[0045] First, a sol particle solution is prepared in which particles of silsesquioxane condensate are dispersed in a dispersion medium. The sol particle solution can be prepared, for example, by the method described above. The concentration of particles of silsesquioxane condensate in the sol particle solution at this stage is not particularly limited, but may be, for example, 0.5% by weight or more, 1.0% by weight or more, or 2.0% by weight or more, or for example, 3.5% by weight or less.

[0046] Next, a "first grinding step" is performed to grind the particles in the sol particle liquid (a liquid in which the particles are dispersed in the dispersion medium). The grinding method in the first grinding step is not particularly limited, but for example, the method described in Japanese Patent No. 7182358 may be used. Among these, high-pressure medialess grinding is preferred. The pressure in the first grinding step is not particularly limited, but for example, it may be 30 MPa or more, 50 MPa or more, or for example, 350 MPa or less, 300 MPa or less. The particle size D50 of the silsesquioxane condensate particles after the first grinding step is not particularly limited, but may be, for example, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, or 50 nm or more, or for example, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, or 150 nm or less, or for example, 25 to 350 nm, 30 to 300 nm, 35 to 250 nm, 40 to 200 nm, or 50 to 150 nm.

[0047] Next, a "concentration step" is performed to concentrate the sol particle liquid after the first grinding step. The concentration method in the concentration step is not particularly limited, and may be, for example, heating or pressurizing, but pressurizing is preferred. More specifically, for example, the concentration may be increased to a predetermined concentration by pressurizing using a filter, or the dispersion medium may be partially removed by heating or the like and concentrated to a predetermined concentration. The filter is also not particularly limited, but examples include rotary ceramic membrane filters and cross-flow filters. An example of a rotary ceramic membrane filter is the product name "Mitsubishi Dynafilter (DyF)" manufactured by Mitsubishi Chemical Machinery Co., Ltd. The concentration of silsesquioxane condensate particles in the sol particle liquid after the concentration step is not particularly limited, but may be, for example, 3.6% by weight or more, 4.0% by weight or more, or for example, 40% by weight or less, 30% by weight or less, 20% by weight or less, 18% by weight or less, or 15% by weight or less.

[0048] Next, a "second grinding step" is performed to further grind the particles in the sol particle liquid after the concentration step. At this time, at least one of the following conditions is met: the viscosity of the liquid after the second grinding step is greater than the viscosity of the liquid after the first grinding step, or the concentration of the particles in the liquid after the second grinding step is greater than the concentration of the particles in the liquid after the first grinding step. The grinding method in the second grinding step is not particularly limited, but for example, the method described in Japanese Patent Publication No. 7182358 may be used. Among these, high-pressure medialess grinding is preferred. The pressure in the second grinding step is not particularly limited, but for example, it may be 30 MPa or more, 50 MPa or more, or for example, 350 MPa or less, 300 MPa or less. The particle size D50 of the silsesquioxane condensate particles after the second grinding step is less than 130 nm, satisfying the conditions for the dispersion liquid of this disclosure. The numerical range of the particle size D50 may be more specifically as described above.

[0049] Furthermore, a "liquid concentration adjustment step" is performed in which a dispersion medium is added to the sol particle liquid after the second grinding step to adjust the liquid concentration, thereby producing the dispersion liquid of the present disclosure. At this time, the viscosity of the dispersion liquid is not particularly limited, but may be set to 1 mPa·s or more and less than 5000 mPa·s. In order to ensure the thickness of the low refractive index layer, it is preferable that the viscosity of the dispersion liquid is not too low. In order to prevent large variations in the thickness of the low refractive index layer (making it impossible to achieve uniformity of in-plane film thickness) or cracks from occurring in the low refractive index layer during drying, which would prevent the formation of the low refractive index layer itself, it is preferable that the viscosity of the dispersion liquid is not too high. The lower limit of the viscosity of the dispersion liquid of the present disclosure may be, for example, 10 mPa·s or more, 16 mPa·s or more, 18 mPa·s or more, or 20 mPa·s or more, and may be, for example, 5000 mPa·s or less, 4000 mPa·s or less, 3500 mPa·s or less, or 3000 mPa·s or less. Furthermore, at this time, the concentration of silsesquioxane condensate particles in the dispersion is set to 3.5% by weight or more, which is within the range of this disclosure. If the concentration of silsesquioxane condensate particles in the dispersion is too low, exceeding the range of this disclosure, it becomes impossible to secure the film thickness of the low refractive index layer. In addition, in order to prevent large variations in the film thickness of the low refractive index layer (making it impossible to achieve uniformity of in-plane film thickness) or the occurrence of cracks in the low refractive index layer during drying, which prevents the formation of the low refractive index layer itself, it is preferable that the concentration of silsesquioxane condensate particles in the dispersion is not too high. The concentration of the silsesquioxane condensate particles in the dispersion of the present disclosure may be, for example, 3.6% by weight or more, 4.0% by weight or more, 4.5% by weight or more, 5.0% by weight or more, or 5.5% by weight or more, for example, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, or 20% by weight or less, for example, 3.6 to 40% by weight, 4.0 to 35% by weight, 4.5 to 30% by weight, 5.0 to 25% by weight, or 5.5 to 20% by weight.The concentration of the solid component in the sol particle liquid after the concentration step is not particularly limited, but may be, for example, 3.6% by weight or more, 3.8% by weight or more, 4.0% by weight or more, 4.1% by weight or more, or 4.2% by weight or more, or for example, 39% by weight or less, 38% by weight or less, 37% by weight or less, 36% by weight or less, or 35% by weight or less, or for example, 3.6 to 39% by weight, 3.8 to 38% by weight, 4.0 to 37% by weight, 4.1 to 36% by weight, or 4.2 to 35% by weight. At this time, a crosslinking aid (also called a crosslinking agent), a catalyst, etc., may be added along with the dispersion medium to promote crosslinking between the particles of the silsesquioxane condensate for use in producing a low refractive index layer. The crosslinking is not particularly limited, but for example, the particles of the silsesquioxane condensate may be bonded together by covalent bonds directly or via the crosslinking aid. The crosslinking aid is not particularly limited, but may be, for example, a substance having multiple functional groups that can form covalent bonds with the particles of the silsesquioxane condensate. Specifically, examples of the crosslinking aid include bis(trimethoxysilyl)alkylene. Examples of bis(trimethoxysilyl)alkylene include bis(trimethoxysilyl)hexane. Other examples of the crosslinking aid are not particularly limited, but are, for example, as described in Japanese Patent Publication No. 7182358. The concentration of the crosslinking aid in the dispersion of this disclosure is not particularly limited, but is, for example, as described in Japanese Patent Publication No. 7182358. The catalyst is not particularly limited, and may be, for example, a photoactive catalyst or a thermally active catalyst, or an acid catalyst or a base catalyst. In addition to or instead of the catalyst, a catalyst generating substance (catalyst generating agent) may be used. For example, in addition to or instead of the photoactive catalyst, a substance that generates a catalyst by light (photocatalyst generator) may be used, or in addition to or instead of the thermally activated catalyst, a substance that generates a catalyst by heat (thermal catalyst generator) may be used. The photocatalyst generator is not particularly limited, but examples include a photobase generator (a substance that generates a basic catalyst by light irradiation), a photoacid generator (a substance that generates an acidic catalyst by light irradiation), and so on, with photobase generators being preferred.Examples of the aforementioned photobase generators include 9-anthrylmethyl N,N-diethylcarbamate (trade name WPBG-018), (E)-1-[3-(2-hydroxyphenyl)-2-propenoyl]piperidine (trade name WPBG-027), 1-(anthraquinon-2-yl)ethyl imidazolecarboxylate (trade name WPBG-140), 2-nitrophenylmethyl 4-methacryloyloxypiperidine-1-carboxylate (trade name WPBG-165), and 1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidium Examples include 2-(3-benzoylphenyl)propionate (trade name WPBG-266), 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium n-butyltriphenyl borate (trade name WPBG-300), and 1,5,7-triazabicyclo[4.4.0]deca-5-ene 2-(9-oxoxanthene-2-yl)propionic acid (Tokyo Chemical Industries, Ltd.), and compounds containing 4-piperidine methanol (trade name HDPD-PB100: manufactured by Heraeus). Note that all trade names containing "WPBG" are trade names of Wako Pure Chemical Industries, Ltd. Examples of photoacid generators include aromatic sulfonium salts (trade name SP-170: ADEKA), triarylsulfonium salts (trade name CPI101A: Sunapro), and aromatic iodonium salts (trade name Irgacure250: Ciba Japan). The concentration of the catalyst or catalyst generator in the dispersion of this disclosure is not particularly limited, but is, for example, as described in Japanese Patent Publication No. 7182358.

[0050] The dispersion of the present disclosure can be manufactured in the manner described above. However, the method for manufacturing the dispersion of the present disclosure is not limited thereto, and any manufacturing method is acceptable as long as it satisfies the conditions of the dispersion of the present disclosure. For example, the method for manufacturing the dispersion of the present disclosure may or may not include steps other than the "first grinding step," "concentration step," and "second grinding step." For example, the liquid concentration adjustment step may or may not be performed as needed, and the grinding step is not limited to the two steps of the first grinding step and the second grinding step, but may consist of three or more steps.

[0051] Furthermore, the method for producing the dispersion of the present disclosure may be such that, for example, the pressure during the first grinding step and the pressure during the second grinding step are the same, and all of the following relational expressions (1) to (3) are satisfied. This has the effect of suppressing light scattering caused by particle size when light is guided to the ultra-low refractory layer. Particle size D50 after the concentration step > Particle size D50 after the first grinding (1) Particle size D50 after the concentration step > Particle size D50 after the second grinding (2) Particle size D50 after the first grinding ≥ Particle size D50 after the second grinding (3)

[0052] [2. Low refractive index layer and method for manufacturing the same] The low refractive index layer of the present disclosure is characterized by being obtained by coating the dispersion of the present disclosure and drying it, as described above. The layer obtained by coating the dispersion of the present disclosure and drying it may be subjected to, for example, heating or light irradiation. By heating or light irradiation, for example, the particles of the silsesquioxane condensate can be crosslinked together directly or via the crosslinking aid, thereby increasing the strength.

[0053] The low refractive index layer of this disclosure may be manufactured, for example, by coating the dispersion of this disclosure onto a substrate such as a film and drying it. The film may be, for example, a resin film. Generally, materials with relatively small thickness are called "films" and those with relatively large thickness are called "sheets" to distinguish them, but in this disclosure, there is no particular distinction between "films" and "sheets". The substrate is not particularly limited, and preferably, but is not limited to, thermoplastic resin substrates, glass substrates, inorganic substrates represented by silicon, plastics molded from thermosetting resins, semiconductor devices, carbon fiber materials represented by carbon nanotubes, etc.

[0054] The method for manufacturing the low refractive index layer of this disclosure is not particularly limited and may be manufactured, for example, in a manner similar to that described in International Publication No. 2019 / 065999 or International Publication No. 2019 / 065803.

[0055] The low refractive index layer of this disclosure may be, for example, a void layer having voids. Alternatively, the low refractive index layer of this disclosure may be, for example, a porous material in which microporous particles are chemically bonded to each other.

[0056] The low refractive index layer of this disclosure may have a thickness of, for example, 500 nm or more, 700 nm or more, 800 nm or more, 1000 nm or more, or 2000 nm or more, or for example, 10000 nm or less, 8000 nm or less, 5000 nm or less, 4000 nm or less, or 3000 nm or less, or for example, 500 to 10000 nm, 700 to 8000 nm, 800 to 5000 nm, 1000 to 4000 nm, or 2000 to 3000 nm. The low refractive index layer of the present disclosure may have a porosity of, for example, 30 volume% or more, 35 volume% or more, 40 volume% or more, 45 volume% or more, or 50 volume% or more, for example, 90 volume% or less, 80 volume% or less, 70 volume% or less, or 60 volume% or less, for example, 30 to 90 volume%, 35 to 80 volume%, 40 to 70 volume%, or 50 to 60 volume%. The low refractive index layer of the present disclosure may have a refractive index of, for example, 1.05 or more, 1.10 or more, or 1.13 or more, for example, 1.35 or less, 1.30 or less, or 1.25 or less, for example, 1.05 to 1.35, 1.10 to 1.30, or 1.13 to 1.25.

[0057] In the low refractive index layer of this disclosure, the porosity can be measured by the following method.

[0058] (Method for measuring porosity) If the layer to be measured is a single layer containing only voids, the ratio (volume ratio) of the constituent material to air in the layer can be calculated using a standard method (for example, by measuring weight and volume to calculate density), and thus the porosity (volume %) can be calculated. Furthermore, since there is a correlation between refractive index and porosity, the porosity can also be calculated from the refractive index value of the layer, for example. Specifically, for example, the porosity can be calculated from the refractive index value measured with an ellipsometer using the Lorentz-Lorentz formula.

[0059] In this disclosure, the refractive index of the low refractive index layer is the refractive index value at a wavelength of 550 nm, measured and calculated by the method described below.

[0060] (Method for measuring refractive index) After forming a low refractive index layer on a glass light guide plate, a prism coupler (Metricon, product name "Model 2010 / M") is used to introduce laser light (λ = 407 nm) from the glass light guide plate side, and the refractive index at 407 nm is calculated from the measured total reflection angle. Furthermore, the measured refractive index at 407 nm is converted to the refractive index at 550 nm from the wavelength dispersion of the low refractive index layer alone, which is calculated separately using an ellipsometer (J.A. Wollam), and this converted value is taken as the refractive index of the low refractive index layer.

[0061] In this disclosure, the haze of the low refractive index layer shall be a value measured and calculated by the following method.

[0062] (Method for measuring haze) A 100 mm x 100 mm laminate (void layer / glass substrate) is used as the evaluation sample. The sample is placed in a spectroscopic haze meter (manufactured by Nippon Denshoku Industries Co., Ltd.: SH7000) and the haze is measured. The haze value is calculated using the following formula: Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] × 100 (%)

[0063] The low refractive index layer of this disclosure preferably has a thickness variation of, for example, 20% or less, 18% or less, 16% or less, 15% or less, or 10% or less, and the lower limit is not particularly limited, but may be, for example, 0 or a value greater than 0. The thickness variation refers to the in-plane film thickness variation of the low refractive index layer when a low refractive index layer of 1.25 or less is formed by spin coating on a light guide plate with a diameter or short side of 20 cm or less made of glass or resin with a surface roughness Rz of 50 nm or less of the dispersion of this disclosure. In this disclosure, the in-plane film thickness variation of the low refractive index layer is an index obtained by comparing the standard deviation of the measured values ​​of the film thickness at five points in the plane with the average film thickness.

[0064] [3. Optical members and optical devices] The optical members of the present disclosure are characterized by including the low refractive index layer of the present disclosure as described above. The optical members of the present disclosure may include or may not include components other than the low refractive index layer of the present disclosure.

[0065] The optical component of this disclosure may be, for example, a laminate in which a low refractive index layer of this disclosure is laminated on a substrate. The substrate is not particularly limited, but may be as described above.

[0066] The optical component of this disclosure may be, for example, a light guide plate with a low refractive index layer, wherein the low refractive index layer of this disclosure is laminated on a light guide plate. In this case, other layers such as adhesive layers may exist between the light guide plate and the low refractive index layer of this disclosure, but it is preferable that the low refractive index layer of this disclosure is laminated directly on the light guide plate without any other layers in between. In this case, for example, the low refractive index layer of this disclosure can be manufactured by coating the light guide plate with the dispersion of this disclosure and drying it using the method described above.

[0067] The optical components of this disclosure are not limited to light guide plates, but may also include, for example, polarizing plates, phase difference films, reflective polarizers, brightness-enhancing films, diffusion films, dye-containing layers, or layers or films having transparent and opaque optical functions.

[0068] The optical device (optical apparatus) of this disclosure is not particularly limited, but may be, for example, an image display device or a lighting device. Examples of image display devices include liquid crystal displays, organic EL (Electroluminescence) displays, micro-LED (Light Emitting Diode) displays, and AR (Augmented Reality) glasses. Examples of lighting devices include organic EL lighting.

[0069] Next, embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments.

[0070] In the following reference examples, examples, and comparative examples, the number of parts (relative amount used) of each substance is in parts by mass (parts by weight) unless otherwise specified. In the following reference examples, examples, and comparative examples, the adhesive used is the adhesive (adhesive composition) described later. In the following reference examples, examples, and comparative examples, "adhesive layer" corresponds to "adhesive bonding layer." That is, in the following reference examples, examples, and comparative examples, "adhesive layer" and "adhesive bonding layer" are synonymous unless otherwise specified.

[0071] <Method for measuring refractive index> The refractive index was measured using the refractive index evaluation method described above.

[0072] <Method for measuring particle size> The particle size D50 of the silsesquioxane condensate was measured by the method described above. As mentioned above, D50 is also called the median diameter and is the particle size of the median of the particle distribution, corresponding to a cumulative frequency of 50%.

[0073] <Method for measuring particle pore size> The pore size of the silsesquioxane condensate particles was measured by the method described above.

[0074] <Method for measuring the specific surface area of ​​particles> The specific surface area of ​​the silsesquioxane condensate particles was measured by the method described above.

[0075] [Reference Example 1: Production of Gel Grinding Solution for Low Refractive Index Layer Formation] A gel grinding solution (sol particle liquid) for low refractive index layer formation was produced as follows.

[0076] (1) Gelation of silicon compounds Mixture A was prepared by dissolving 9.5 kg of methyltrimethoxysilane (MTMS), a precursor of silicon compounds, in 22 kg of dimethyl sulfoxide (DMSO). 5 kg of 0.01 mol / L aqueous oxalic acid solution was added to mixture A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS and produce mixture B containing tris(hydroxy)methylsilane.

[0077] 77 kg of DMSO was mixed with 7.2 kg of alkylamine and 2 kg of pure water. Then, the above mixture B was added and stirred at room temperature for 15 minutes to gel tris(hydroxy)methylsilane, obtaining mixture C containing a gel-like silicon compound.

[0078] (2) Aging process The mixed liquid C containing the gel-like silicon compound prepared as described above was poured into a 30 cm x 30 cm x 5 cm stainless steel container and incubated at 40°C for 20 hours to perform the aging process.

[0079] (3) Grinding Process Next, isobutyl alcohol, which is the substitution solvent, was poured onto the gel synthesized in the stainless steel container. Then, the cutting blade of a cutting jig was slowly inserted into the gel from above, and the gel was cut into a rectangular parallelepiped measuring 1.5 cm × 2 cm × 5 cm. The cut gel was transferred to another container, and while being careful not to disturb the shape of the gel, isobutyl alcohol was added in an amount four times the volume of the gel. After standing for 6 hours, solvent exchange was performed four times. The gel (gel-like silicon compound) was ground using a continuous emulsification dispersion machine (Milder MDN304, manufactured by Taiheiyo Kiko Co., Ltd.) to obtain a coarse grinding liquid. Further grinding was performed using a high-pressure medialess grinding machine (Starburst HJP-25005, manufactured by Sugino Machine Co., Ltd.) under a pressure of 150 MPa. In this way, an isobutyl alcohol dispersion (gel grinding material-containing liquid) in which nanometer-sized particles (the pulverized gel) were dispersed was obtained.

[0080] [Example 1] To 20 g of the gel pulverized material-containing liquid (nanoparticle liquid) obtained in Reference Example 1, 0.96 g of a 5.0 mass% ethanol solution of a photobase generator (Fujifilm Wako Pure Chemical Industries, Ltd.: product name WPBG266) and 0.036 g of a 5% ethanol solution of bis(trimethoxysilyl)hexane were added in a ratio to obtain the dispersion liquid (gel dispersion coating liquid) of the present disclosure. Although not performed in this example, each of the above-mentioned additives may be neutralized and hydrolyzed with oxalic acid beforehand. Next, the obtained gel dispersion coating liquid was applied to an alkali-free glass substrate, dried at 100°C for 2 min, and further irradiated with UV light to produce the low refractive index layer of the present disclosure. This obtained the glass substrate with a low refractive index layer. Coating (film formation), drying, and UV irradiation were carried out under the following conditions. Film formation method: Spin coater; Rotation speed: 800 rpm; Rotation time: 10 seconds; Drying: Allowed to stand for 1 min in an atmospheric environment, then dried for 2 min on a 100°C hot plate. UV irradiation: 300-420 mJ / cm² ２ , wavelength 365nm

[0081] [Comparative Example 1] As a gelling formulation for the silicon compound, 3.8 kg of 28% by weight ammonia and 2 kg of pure water were added to 77 kg of DMSO, and then the mixture B from Reference Example 1 was added. The mixture was stirred at room temperature for 15 minutes to gel tris(hydroxy)methylsilane, and a mixture C containing a gel-like silicon compound was obtained. The rest of the procedure was the same as in Reference Example 1 and Example 1 to produce the dispersion and the low refractive index layer of the present disclosure.

[0082] The optical properties of the low refractive index layers of each example and comparative example manufactured as described above were evaluated using the method described above. The evaluation results are summarized in Table 2 below. In Table 2 below, "refractive index" represents the refractive index of the low refractive index layer manufactured in the above example and comparative example. "Haze" represents the haze of the low refractive index layer manufactured in the above example and comparative example. "D50 particle size" represents the D50 particle size of the silica gel particles in the dispersion of the present disclosure manufactured in the above example or the dispersion manufactured in the above comparative example. "Pore diameter" represents the pore diameter of the silica gel particles in the dispersion of the present disclosure manufactured in the above example or the dispersion manufactured in the above comparative example. "Specific surface area" represents the specific surface area of ​​the silica gel particles in the dispersion of the present disclosure manufactured in the above example or the dispersion manufactured in the above comparative example.

[0083]

[0084] As shown in Table 2 above, in the dispersions of the examples in which the D50 particle size, pore size, and specific surface area of ​​the silica gel particles met the requirements of this disclosure, it was possible to produce a low refractive index layer that achieved both a low refractive index and a low haze value. In contrast, in the dispersions of the comparative examples in which the D50 particle size, pore size, and specific surface area of ​​the silica gel particles did not meet the requirements of this disclosure, the refractive index and haze value of the low refractive index layer were higher than those of the examples.

[0085] This disclosure may also be presented, for example, as shown in the following appendix. However, the following appendix is ​​illustrative, and this disclosure is not limited to these forms.

[0086] (Note 1) A dispersion liquid in which silica gel particles are dispersed in a dispersion medium, wherein the silica gel particles have a D50 particle size of less than 130 nm, a pore diameter of less than 15 nm, and a specific surface area of ​​500 m².２ A dispersion characterized by having a concentration of 1 / g or more. (Note 2) The dispersion according to Note 1, wherein the silica gel particles are a condensate of a raw material containing alkoxysilane. (Note 3) The dispersion according to Note 2, wherein the silica gel particles are a condensate of a raw material containing alkoxysilane having three or fewer functional groups. (Note 4) The dispersion according to any one of Notes 1 to 3, wherein the silica gel particles are pulverized silica gel. (Note 5) A dispersion set characterized by comprising the dispersion according to any one of Notes 1 to 4 and a catalyst-containing liquid containing a catalyst for chemically bonding the particles of the dispersion. (Note 6) The dispersion set according to Note 5, further comprising a crosslinking aid-containing liquid containing a crosslinking aid for indirectly bonding the silica gel particles together. (Note 7) A low refractive index layer characterized by being obtained by coating and drying the dispersion according to any one of Notes 1 to 4. (Note 8) An optical component characterized by comprising the low refractive index layer according to Note 7. (Note 9) An optical device characterized by comprising the optical component according to Note 8.

[0087] As described above, this disclosure provides a dispersion capable of producing a low refractive index layer that achieves both a low refractive index and a low haze value, as well as a dispersion set using the same, a low refractive index layer, an optical component, and an optical device. The applications of this disclosure are not particularly limited. For example, the optical device of this disclosure is not particularly limited and includes image display devices, lighting devices, etc. Examples of image display devices include liquid crystal displays, organic EL displays, micro-LED displays, AR glasses, etc. Examples of lighting devices include organic EL lighting, etc.

[0088] This application claims priority based on Japanese Patent Application No. 2025-008666, filed on 21 January 2025, and incorporates all of its disclosures herein.

Claims

1. A dispersion liquid in which silica gel particles are dispersed in a dispersion medium, wherein the silica gel particles have a D50 particle size of less than 130 nm, a pore diameter of less than 15 nm, and a specific surface area of ​​500 m². ２ A dispersion characterized by having a concentration of 1 / g or more.

2. The dispersion according to claim 1, wherein the silica gel particles are a condensate of raw materials containing alkoxysilane.

3. The dispersion according to claim 2, wherein the silica gel particles are a condensate of a raw material containing an alkoxysilane having three or fewer functional groups.

4. The dispersion according to any one of claims 1 to 3, wherein the silica gel particles are pulverized silica gel.

5. A dispersion set comprising a dispersion according to any one of claims 1 to 4, and a catalyst-containing liquid containing a catalyst for chemically binding the particles of the dispersion.

6. The dispersion set according to claim 5, further comprising a crosslinking aid-containing liquid containing a crosslinking aid for indirectly binding the silica gel particles together.

7. A low refractive index layer characterized by being obtained by coating and drying the dispersion liquid according to any one of claims 1 to 4.

8. An optical member characterized by comprising the low refractive index layer described in claim 7.

9. An optical device characterized by including the optical member described in claim 8.

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