Void layer, method for producing void layer, layered body, optical member, and optical device

Abstract

Provided is a void layer having a low refractive index and excellent mechanical strength.　A void layer (11) according to the present disclosure is a layer in which ground pieces of a gel-like silicon compound are chemically bonded. The gel-like silicon compound is obtained by condensing or partially condensing a silane compound. The silane compound contains a monofunctional to trifunctional silane compound and a tetrafunctional silane compound. The refractive index of the void layer (11) is 1.30 or less.

Description

Void layer, method for manufacturing void layer, laminate, optical member, and optical device

[0001] The present disclosure relates to a gap layer, a method for manufacturing a gap layer, a laminate, an optical member, and an optical device.

[0002] In optical devices, for example, it has been proposed to use a low refractive index layer as a total reflection layer. For example, Patent Document 1 discloses a laminate in which a layer having a lower refractive index than the light guide plate is inserted between the light guide plate and the reflector. As the low refractive index layer, for example, a void layer having voids is used in order to make the refractive index as low as possible to that of air.

[0003] Japanese Patent Application Publication No. 10-62626

[0004] As mentioned above, a gap layer is a layer having voids. Generally, the refractive index of a gap layer tends to be lower as the porosity of the gap layer increases. On the other hand, when the porosity of a gap layer is increased, the mechanical strength of the gap layer tends to be lower. In other words, there is a trade-off between the refractive index of a gap layer and the mechanical strength of the gap layer. Therefore, it is desirable to realize a gap layer that has high mechanical strength even if it has a low refractive index.

[0005] Therefore, an object of the present disclosure is to provide a gap layer that has a low refractive index and excellent mechanical strength, a method for manufacturing a gap layer, a laminate, an optical member, and an optical device.

[0006] In order to achieve the above object, the porous layer of the present disclosure is a porous layer in which pulverized gel silicon compounds are chemically bonded, the gel silicon compounds are compounds in which silane compounds are condensed or partially condensed, the silane compounds include mono- to tri-functional silane compounds and tetra-functional silane compounds, and the refractive index of the porous layer is 1.30 or less.

[0007] The void layer of the present disclosure is a void layer in which pulverized gel silicon compound is chemically bonded in the presence of an additive, the gel silicon compound is a compound obtained by condensing or partially condensing a silane compound, the additives include at least one of a crosslinking reaction accelerator and its precursor, and a crosslinking auxiliary, the total content of the crosslinking reaction accelerator and its precursor is 1.5 mol% or more relative to the total substance amount of the silane compound, the total content of the crosslinking auxiliary is 2.0 mol% or more, and the refractive index of the void layer is 1.30 or less.

[0008] The method for manufacturing a porous layer of the present disclosure includes a gel silica synthesis step, a gel crushing step, and a bonding step, wherein the gel silica synthesis step includes a step of synthesizing a gel silicon compound by condensing or partially condensing a silane compound, and the silane compound includes a mono- to tri-functional silane compound and a tetrafunctional silane compound, the gel crushing step includes a step of crushing the gel silicon compound to obtain a crushed product, and the bonding step includes a step of chemically bonding the crushed product.

[0009] The method for manufacturing a void layer of the present disclosure includes a gel silica synthesis step, a gel crushing step, and a bonding step, wherein the gel silica synthesis step includes a step of synthesizing a gel silicon compound by condensing or partially condensing a silane compound, the gel crushing step includes a step of crushing the gel silicon compound to obtain a crushed product, and the bonding step includes a step of chemically bonding the crushed product in the presence of additives, and the additives include at least one of a crosslinking reaction accelerator and a precursor thereof, and a crosslinking auxiliary.

[0010] The laminate of the present disclosure includes the porous layer of the present disclosure and an adhesive layer, and the adhesive layer is directly laminated on one or both sides of the porous layer.

[0011] The optical member of the present disclosure includes the air gap layer of the present disclosure or the laminate of the present disclosure.

[0012] The optical device of the present disclosure includes the optical member of the present disclosure.

[0013] According to the present disclosure, it is possible to provide a gap layer having a low refractive index and excellent mechanical strength, a method for manufacturing a gap layer, a laminate, an optical member, and an optical device.

[0014] Figures 1(a) and (b) are cross-sectional views illustrating the configuration of a laminate of the present disclosure. Figures 2(a) and (b) are cross-sectional views illustrating another example of the configuration of a laminate of the present disclosure. Figures 3(a) and (b) are cross-sectional views illustrating yet another example of the configuration of a laminate of the present disclosure. Figure 4 is a graph showing the relationship between peel strength and refractive index.

[0015] Next, the present disclosure will be described in more detail using examples, but the present disclosure is not limited to the following description.

[0016] In the present disclosure, the term "adhesive layer" refers to a layer formed of at least one of a pressure-sensitive adhesive and an adhesive. In the present disclosure, unless otherwise specified, the term "adhesive layer" may refer to a "pressure-sensitive adhesive layer" formed of a pressure-sensitive adhesive, an "adhesive layer" formed of an adhesive, or a layer containing both a pressure-sensitive adhesive and an adhesive. Furthermore, in the present disclosure, pressure-sensitive adhesives and adhesives may be collectively referred to as "adhesive adhesives." Generally, a material with relatively weak adhesive or bonding strength (e.g., a material that allows for re-detachment from an adherend) is referred to as a "pressure-sensitive adhesive," while a material with relatively strong adhesive or bonding strength (e.g., a material that is impossible or extremely difficult to re-detach from an adherend) is referred to as an "adhesive." In the present disclosure, there is no clear distinction between a pressure-sensitive adhesive and an adhesive. Furthermore, in the present disclosure, there is no clear distinction between "adhesive strength" and "adhesive strength."

[0017] In the present disclosure, "on" or "on the surface" may refer to a state of being in direct contact with the surface or a state of being interposed between another layer or the like.

[0018] In the present disclosure, "interlayer" refers to any part between one layer and another layer, including the one layer and the other layer. That is, for example, when referring to the interlayer between one layer and another layer, it may refer to any part of the one layer, any part of the other layer, or any part of another layer between the one layer and the other layer. It may also refer to the boundary part between any two of the one layer, the other layer, and the other layer.

[0019] [1. Void Layer, Laminate] As described above, the void layer of the present disclosure is a void layer in which a pulverized gel silicon compound is chemically bonded, the gel silicon compound being a compound formed by condensation or partial condensation of a silane compound, the silane compound including a mono- to tri-functional silane compound and a tetrafunctional silane compound, and the refractive index of the void layer is 1.30 or less. In another embodiment, the void layer of the present disclosure is a void layer in which a pulverized gel silicon compound is chemically bonded in the presence of an additive, the gel silicon compound being a compound formed by condensation or partial condensation of a silane compound, the additives including at least one of a crosslinking accelerator and its precursor, and a crosslinking auxiliary, the total content of the crosslinking accelerator and its precursor being 1.5 mol% or more, the total content of the crosslinking auxiliary being 2.0 mol% or more, and the refractive index of the void layer being 1.30 or less, relative to the total substance amount of the silane compound. The use of the porous layer of the present disclosure is not particularly limited, but it can be used, for example, in the laminate of the present disclosure described above.

[0020] Furthermore, as described above, the laminate of the present disclosure includes the void layer of the present disclosure and an adhesive layer. The adhesive layer is directly laminated on one or both sides of the void layer. In the present disclosure, the adhesive layer being "directly laminated" on the void layer may mean, for example, that the adhesive layer is in direct contact with the void layer, or that the adhesive layer is laminated on the void layer via the intermediate layer.

[0021] The cross-sectional view of Figure 1(a) shows an example of the configuration of a laminate of the present disclosure. As shown in the figure, this laminate 10 has a tacky adhesive layer 12 directly laminated on one side of a void layer 11. Here, the void layer 11 is a void layer to which pulverized gel silicon compounds are chemically bonded. The gel silicon compounds are compounds in which silane compounds are condensed or partially condensed. The silane compounds include mono- to tri-functional silane compounds and tetra-functional silane compounds, and the content ratio of the tetra-functional silane compounds to the amount of the mono- to tri-functional silane compounds is 1 to 25 mol%. The refractive index of the void layer 11 is 1.30 or less.

[0022] 1(b) shows another example of the configuration of the laminate of the present disclosure. As shown in the figure, this laminate 10a has adhesive layers 12 directly laminated on both sides of a porous layer 11.

[0023] Furthermore, as described above, the laminate of the present disclosure may have an intermediate layer between the void layer and the adhesive layer, and the intermediate layer may be a layer formed by combining the void layer and the adhesive layer. FIG. 2 shows an example of such a laminate of the present disclosure. As shown in FIG. 2( a), the laminate 10b has an adhesive layer 12 directly laminated on one side of the void layer 11. This laminate 10b is the same as the laminate 10 of FIG. 1( a), except that an intermediate layer 13 is present between the void layer 11 and the adhesive layer 12. The intermediate layer 13 is a layer formed by combining the void layer 11 and the adhesive layer 12. As shown in FIG. 2( b), the laminate 10c has adhesive layers 12 directly laminated on both sides of the void layer 11. This laminate 10c is the same as the laminate 10a of FIG. 1( b), except that an intermediate layer 13 is present between the void layer 11 and each adhesive layer 12. The intermediate layer 13 is a layer formed by combining the void layer 11 and the adhesive layer 12, as in FIG. 2(a).

[0024] Furthermore, the laminate of the present disclosure may or may not include other components besides the void layer, the adhesive layer, and the intermediate layer. The other components are not particularly limited, and may be, for example, a substrate. The substrate is also not particularly limited, and may be, for example, a film (e.g., a resin film), a glass plate, or the like, as described below. Figure 3 shows an example of such a laminate of the present disclosure. The laminate 10d of Figure 3(a) is the same as the laminate 10b of Figure 2(a) except that, as shown, a substrate 14 is provided in direct contact with the surface of the void layer 11 opposite the adhesive layer 12, and with the surface of the adhesive layer 12 opposite the void layer 11. The laminate 10e of Figure 3(b) is the same as the laminate 10c of Figure 3(b) except that, as shown, a substrate 14 is provided in direct contact with the surface of each of the adhesive layers 12 on both sides opposite the void layer 11. In Figures 3(a) and 3(b), a substrate 14 is provided on both sides of the laminate. However, the present disclosure is not limited thereto, and for example, the substrate 14 may be provided on only one side. Also, in FIGS. 3( a) and 3(b), the substrate 14 is provided so as to be in direct contact with the void layer 11 or the adhesive layer 12. However, the present disclosure is not limited thereto, and for example, other components may be present between the substrate 14 and the void layer 11 or the adhesive layer 12. The other components are not particularly limited, and may be, for example, an optical functional layer. The optical functional layer is also not particularly limited, and may be, for example, an optical functional layer used in a general optical film, such as a microlens film, a prism film, a diffusion film, a polarizing reflective film, a polarizing film, a retardation film, or a high refractive index layer.

[0025] As described above, the void layer of the present disclosure is a void layer in which pulverized gel silicon compound particles are chemically bonded. By using the pulverized gel silicon compound, the three-dimensional structure of the gel silicon compound is destroyed, and a new three-dimensional structure different from the gel silicon compound is formed. In this way, the void layer becomes a layer in which a new pore structure (new void structure) that cannot be obtained in a layer formed from the gel silicon compound is formed, thereby forming a nanoscale void layer with high porosity. Furthermore, when the void layer is, for example, a gel silicon compound, the pulverized particles are chemically bonded together while adjusting the number of siloxane bond functional groups of the gel silicon compound. Here, "gel silicon compound" refers to a polymeric porous material containing siloxane bonds, including, for example, a porous material containing silsesquioxane as a structural unit. Furthermore, after a new three-dimensional structure is formed as a precursor of the void layer, the void layer is chemically bonded (e.g., cross-linked) in a bonding step, so that, for example, when the void layer is a functional porous body, the void layer has a structure with voids but can maintain sufficient strength and flexibility. Therefore, according to the present disclosure, the void layer can be easily and simply applied to various objects.

[0026] In the void layer of the present disclosure, the form in which the pulverized materials are chemically bonded (form of chemical bond) is not particularly limited, and specific examples of the chemical bond include, for example, a covalent bond, an ionic bond, a metallic bond, etc. For example, the pulverized materials may be cross-linked (cross-linked) together by a covalent bond. Furthermore, the form of chemical bond (for example, the above-mentioned cross-linking) between the pulverized materials may be, for example, a form in which the pulverized materials are directly bonded together, or a form in which the pulverized materials are indirectly bonded together via other substances such as a cross-linking aid, a linker, or a spacer. The method for chemically bonding the pulverized materials is as described below in the method for manufacturing a void layer.

[0027] The crosslinked bond is, for example, a siloxane bond. Examples of siloxane bonds include the T2 bond, T3 bond, and T4 bond shown below. When the gel silicon compound has a siloxane bond, it may have, for example, any one type of bond, any two types of bonds, or all three types of bonds. The higher the ratio of T2 and T3 among the siloxane bonds, the more flexible the gel will be and the inherent properties of the gel can be expected, but the film strength will be weaker. On the other hand, if the ratio of T4 among the siloxane bonds is high, the film strength will be easily achieved, but the void size will be small and the flexibility will be weaker. For this reason, it is preferable to change the ratios of T2, T3, and T4 depending on the application, for example.

[0028]

[0029] When the void layer of the present disclosure has the siloxane bond, the ratio of T2, T3, and T4, when expressed relatively with T2 set to "1," is, for example, T2:T3:T4=1:[1-100]:[0-50], 1:[1-80]:[1-40], or 1:[5-60]:[1-30].

[0030] In the porous layer of the present disclosure, the gel silicon compound is a compound in which a silane compound is condensed or partially condensed, as described above. The condensation can be, for example, dehydration condensation. The partially condensed state refers to a state in which, for example, some of the condensable functional groups (e.g., alkoxy groups) contained in the silane compound are condensed, while the remaining functional groups are not condensed and remain as condensable functional groups. In other words, for example, some of the silane compounds are siloxane-bonded, while the remaining silane compounds are unbonded. The proportion of unbonded silane compounds is, for example, less than 50%, 30% or less, or 15% or less.

[0031] As described above, the silane compound in the air gap layer of the present disclosure includes a mono- to tri-functional silane compound and a tetrafunctional silane compound. For example, the silane compound may include at least one silane compound selected from the mono- to tri-functional silane compounds, and may further include a tetrafunctional silane compound. Examples of the mono- to tri-functional silane compound include mono- to tri-functional alkoxysilanes. Examples of the tetrafunctional silane compound include tetrafunctional alkoxysilanes. Examples of the monofunctional silane compound include trimethylmethoxysilane (TMMS), trimethylethoxysilane (TMES), trimethylpropoxysilane (TMPS), etc. Examples of the bifunctional silane compound include dimethyldimethoxysilane (DDMS), dimethyldiethoxysilane (DDES), dimethyldipropoxysilane (DDPS), etc. Examples of the trifunctional silane compounds include methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), methyltripropoxysilane (MTPS), 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, etc. Examples of the tetrafunctional silane compounds include tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetrapropoxysilane (TPOS), etc.

[0032] In the porous layer of the present disclosure, the content ratio of the tetrafunctional silane compound relative to the amount of the mono- to trifunctional silane compound is, for example, 1 to 25 mol%. The lower limit of the content ratio is, for example, 2 mol% or more, 3 mol% or more, or 3.5 mol% or more, and the upper limit is, for example, 20 mol% or less, 15 mol% or less, or 10 mol% or less, and the range is, for example, 2 to 20 mol%, 3 to 15 mol%, 3.5 to 15 mol%, or 3.5 to 10 mol%. Note that, from the viewpoint of ease of pulverization in the gel pulverization step, it is preferable that the content ratio is not too high. Furthermore, from the viewpoint of improving the strength of the low refractive index layer, it is preferable that the content ratio is not too low.

[0033] The void layer of the present disclosure is, for example, a void layer in which pulverized gel silicon compound particles are chemically bonded in the presence of an additive. The additive may contain, for example, at least one of a crosslinking reaction accelerator and a precursor thereof. The crosslinking reaction accelerator may be, for example, an acidic substance or a basic substance. The crosslinking reaction accelerator may also be, for example, a catalyst that accelerates chemical bonding (crosslinking) between pulverized gel silicon compound particles. Furthermore, the precursor of the crosslinking reaction accelerator may also be, for example, a substance (crosslinking accelerator generator) that generates the crosslinking reaction accelerator by light or heat.

[0034] The chemical reaction that chemically bonds the gel silicon compounds together preferably utilizes the dehydration condensation reaction of residual silanol groups contained in silica sol molecules. By promoting the reaction between the hydroxyl groups of the silanol groups with the crosslinking reaction accelerator, continuous film formation that hardens the void structure in a short time is possible. Examples of the crosslinking reaction accelerator include photoactive catalysts and thermally active catalysts. The photoactive catalyst can chemically bond (e.g., crosslink) the gel silicon compounds together without heating, for example, in the bonding step described below. This reduces shrinkage of the pulverized material to be bonded during the bonding step, thereby maintaining a higher void ratio. For example, a substance that generates a catalyst when exposed to light (a photocatalyst generator) may be used in addition to or instead of the photoactive catalyst, or a substance that generates a catalyst when exposed to heat (a thermal catalyst generator) may be used in addition to or instead of the thermally active catalyst. The photocatalyst generator is not particularly limited, but examples thereof include a photobase generator (a substance that generates a basic catalyst upon light irradiation) and a photoacid generator (a substance that generates an acidic catalyst upon light irradiation), and a photobase generator is preferred.Examples of the photobase generator 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 of suitable photoacid generators include 2-(3-benzoylphenyl)propionate (trade name WPBG-266), 1,2-dicyclohexyl-4,4,5,5-tetramethylbiguanidium n-butyltriphenylborate (trade name WPBG-300), and 2-(9-oxoxanthen-2-yl)propionic acid 1,5,7-triazabicyclo[4.4.0]dec-5-ene (Tokyo Chemical Industry Co., Ltd.), and a compound containing 4-piperidinemethanol (trade name HDPD-PB100, manufactured by Heraeus Chemical). All of the product names containing "WPBG" are trade names of Wako Pure Chemical Industries, Ltd. Examples of suitable photoacid generators include aromatic sulfonium salts (trade name SP-170, manufactured by ADEKA), triarylsulfonium salts (trade name CPI101A, manufactured by San-Apro), and aromatic iodonium salts (trade name Irgacure 250, manufactured by Ciba Japan). Furthermore, the crosslinking reaction accelerator that chemically bonds the pulverized gel silicon compound particles together is not limited to the photoactive catalyst and the photocatalyst generator, but may be, for example, a thermally active catalyst or a thermal catalyst generator such as urea. Examples of the crosslinking reaction accelerator that chemically bonds the pulverized gel silicon compound particles together include base catalysts such as potassium hydroxide, sodium hydroxide, and ammonium hydroxide, and acid catalysts such as hydrochloric acid, acetic acid, and oxalic acid. Among these, base catalysts are preferred.The crosslinking reaction accelerator and its precursor can be used, for example, by adding at least one of the crosslinking reaction accelerator and its precursor to a sol particle liquid (e.g., a suspension) containing the pulverized material (gel-like silicon compound) immediately before coating, or by using a mixed liquid in which the crosslinking reaction accelerator and at least one of its precursors are mixed in a solvent. The mixed liquid may be, for example, a coating liquid in which the crosslinking reaction accelerator and at least one of its precursors are directly added to the sol particle liquid, a solution in which the crosslinking reaction accelerator and at least one of its precursors are dissolved in a solvent, or a dispersion in which the crosslinking reaction accelerator and at least one of its precursors are dispersed in a solvent. The solvent is not particularly limited, and examples include water, buffer solutions, etc. The amount of the crosslinking reaction accelerator and its precursor added is not particularly limited, but is, for example, 0.01 to 20 wt %, 0.05 to 10 wt %, or 0.1 to 5 wt % relative to the weight of the gel-like silicon compound.

[0035] The lower limit of the total content of the crosslinking reaction accelerator and its precursor relative to the total substance amount of the mono- to tri-functional silane compound and the tetrafunctional silane compound is, for example, 1 mol % or more, 1.5 mol % or more, 2 mol % or more, or 2.5 mol % or more, and the upper limit is, for example, 5 mol % or less, 4 mol % or less, 3.5 mol % or less, or 3 mol % or less.

[0036] In addition, in the void layer of the present disclosure, when the silane compound does not include the tetrafunctional silane compound, the lower limit of the total content ratio of the crosslinking reaction accelerator and its precursor relative to the total amount of substance of the silane compound is, for example, 1.5 mol% or more, 2 mol% or more, or 2.5 mol% or more, and the upper limit is, for example, 5 mol% or less, 4 mol% or less, 3.5 mol% or less, or 3 mol% or less.

[0037] Furthermore, the additive may contain, for example, a cross-linking auxiliary. The cross-linking auxiliary can be said to be a medium for indirectly bonding the pulverized gel silicon compound particles together through, for example, a chemical bond between the pulverized gel silicon compound particles and the cross-linking auxiliary. The cross-linking auxiliary penetrates between the pulverized particles, and the pulverized particles and the cross-linking auxiliary interact or bond with each other, making it possible to bond the pulverized particles that are somewhat distant from each other, and thus making it possible to efficiently increase strength.

[0038] The crosslinking aid is preferably a multi-crosslinked silane monomer, which specifically has, for example, two or more and three or less alkoxysilyl groups, the chain length between the alkoxysilyl groups may be from one to ten carbon atoms, and may also contain elements other than carbon. Examples of the crosslinking auxiliary include bis(trimethoxysilyl)ethane, bis(triethoxysilyl)ethane, bis(trimethoxysilyl)methane, bis(triethoxysilyl)methane, bis(triethoxysilyl)propane, bis(trimethoxysilyl)propane, bis(triethoxysilyl)butane, bis(trimethoxysilyl)butane, bis(triethoxysilyl)pentane, bis(trimethoxysilyl)pentane, bis(triethoxysilyl)hexane, bis(trimethoxysilyl)hexane, bis(trimethoxysilyl)-N-butyl-N-propyl-ethane-1,2-diamine, tris-(3-trimethoxysilylpropyl)isocyanurate, and tris-(3-triethoxysilylpropyl)isocyanurate. The amount of the crosslinking aid to be added is not particularly limited, but is, for example, 0.01 to 20% by weight, 0.05 to 15% by weight, or 0.1 to 10% by weight relative to the weight of the gel silicon compound.

[0039] The lower limit of the total content of the crosslinking auxiliary relative to the total substance amount of the mono- to tri-functional silane compound and the tetrafunctional silane compound is, for example, 1 mol % or more, 2 mol % or more, 2.5 mol % or more, or 3 mol % or more, and the upper limit is, for example, 6 mol % or less, 5.5 mol % or less, 5 mol % or less, 4.5 mol % or less, or 3.5 mol % or less.

[0040] In addition, in the void layer of the present disclosure, when the silane compound does not include the tetrafunctional silane compound, the lower limit of the total content ratio of the crosslinking auxiliary relative to the total amount of substance of the silane compound is, for example, 2 mol% or more, or 2.5 mol% or more, and the upper limit is, for example, 6 mol% or less, 5 mol% or less, 4 mol% or less, 3.5 mol% or less, or 3 mol% or less.

[0041] The void layer of the present disclosure has, for example, a pore structure. The void size of the pores in the void layer refers to the diameter of the major axis of the void (pore) out of the diameter of the major axis and the diameter of the minor axis. The pore size is, for example, 5 nm to 200 nm. The void size is, for example, 5 nm or more, 10 nm or more, or 20 nm or more, with an upper limit of, for example, 200 nm or less, 150 nm or less, 100 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less, and the range is, for example, 5 nm to 200 nm, or 10 nm to 100 nm. The preferred void size is determined depending on the application of the void structure, and therefore, for example, it is necessary to adjust the void size to the desired size depending on the purpose. The void size can be evaluated, for example, by the following method.

[0042] (Cross-sectional SEM observation of void layer) In the present disclosure, the morphology of the void layer can be observed and analyzed using a scanning electron microscope (SEM). Specifically, for example, the void layer is subjected to FIB processing (acceleration voltage: 30 kV) under cooling, and a cross-sectional electron image can be obtained from the obtained cross-sectional sample at an observation magnification of 100,000 times using an FIB-SEM (manufactured by FEI: product name Helios NanoLab 600, acceleration voltage: 1 kV).

[0043] (Evaluation of pore size) In the present disclosure, the pore size can be quantified by the BET test method. Specifically, 0.1 g of the sample (the pore layer) is placed in the capillary of a pore distribution / specific surface area measuring device (BELLSORP MINI, a product name of Microtrack Bell), and then dried under reduced pressure at room temperature for 24 hours to remove gas from the pore structure. Nitrogen gas is then adsorbed onto the sample, and a BET plot, a BJH plot, and an adsorption isotherm are plotted to determine the pore distribution. This allows the pore size to be evaluated.

[0044] The void layer of the present disclosure may have, for example, a pore structure (porous structure) as described above, and may be, for example, an open-cell structure in which the pore structure is continuous. The open-cell structure means, for example, that the pore structure in the void layer is connected three-dimensionally, and the internal voids of the pore structure are continuous. When a porous body has an open-cell structure, it is possible to increase the porosity in the bulk, but an open-cell structure cannot be formed when closed-cell particles such as hollow silica are used. In contrast, the void layer has a three-dimensional dendritic structure, and the dendritic particles settle and deposit in the coating film (a coating film of a sol containing the pulverized porous gel). Furthermore, it is more preferable that the void layer form a monolithic structure in which the open-cell structure has a distribution of multiple pores. The monolithic structure refers to, for example, a structure in which nano-sized voids exist, and a hierarchical structure in which the nano-voids exist as an open-cell structure. When forming the monolithic structure, for example, it is possible to achieve both membrane strength with fine pores and high porosity with coarse open-cell pores. To form such a monolithic structure, for example, it is important to first control the pore distribution of the pore structure to be generated in the porous gel prior to pulverization into the pulverized material. Furthermore, for example, when pulverizing the porous gel, the particle size distribution of the pulverized material can be controlled to a desired size, thereby forming the monolithic structure.

[0045] In the air gap layer of the present disclosure, the haze indicating transparency is not particularly limited, and the lower limit is, for example, 0.1% or more, 0.2% or more, or 0.3% or more, and the upper limit is, for example, 10% or less, 5% or less, or 3% or less, and the range is, for example, 0.1 to 10%, 0.2 to 5%, or 0.3 to 3%.

[0046] The haze can be measured, for example, by the following method.

[0047] (Evaluation of Haze) The porous layer (porous layer of the present disclosure) is cut to a size of 50 mm x 50 mm, and the cut piece is set in a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.) to measure the haze. The haze value is calculated using the following formula: Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] x 100 (%)

[0048] The refractive index of a medium is generally defined as the ratio of the propagation speed of the wavefront of light in a vacuum to the propagation speed within the medium. In this disclosure, the refractive index refers to the refractive index measured at a wavelength of 550 nm unless otherwise specified. The method for measuring the refractive index is not particularly limited, and can be measured, for example, by the following method.

[0049] As described above, the refractive index of the air-gap layer of the present disclosure is 1.30 or less. The upper limit of the refractive index of the air-gap layer is, for example, 1.30 or less, less than 1.30, 1.26 or less, 1.25 or less, less than 1.25, 1.24 or less, 1.23 or less, or 1.22 or less, and the lower limit is, for example, 1.05 or more, 1.10 or more, 1.15 or more, 1.16 or more, 1.17 or more, 1.18 or more, or 1.19 or more, and the range is, for example, 1.05 or more to less than 1.30, 1.05 or more to less than 1.30, 1.10 or more to less than 1.25, 1.15 or more to less than 1.25, or 1.19 or more to less than 1.25. The method for measuring the refractive index of the air-gap layer is not particularly limited, and can be measured, for example, by the following method.

[0050] The porosity of the void layer has a lower limit of, for example, 30 vol% or more, or 50 vol% or more, and an upper limit of, for example, 90 vol% or less, 75 vol% or less, or 60 vol% or less, and the range is, for example, 30 to 90 vol%, 50 to 75 vol%, or 50 to 60 vol%.

[0051] (Evaluation of the refractive index of the void layer) After forming a void layer (void layer of the present disclosure) on an acrylic film, cut it to a size of 50 mm x 50 mm and attach it to the surface of a glass plate (thickness: 3 mm) with an adhesive layer. The center of the back surface of the glass plate (diameter: approximately 20 mm) is painted with black ink to prepare a sample that does not reflect light from the back surface of the glass plate. The sample is placed in an ellipsometer (manufactured by J.A. Woollam Japan: VASE), and the refractive index is measured at a wavelength of 550 nm and an incident angle of 50 to 80 degrees, and the average value is taken as the refractive index.

[0052] After a heat and humidity durability test in which the film is maintained at a temperature of 85°C and a humidity of 85% RH for 500 hours, the residual void ratio of the porous layer is, for example, 10% by volume or more, 20% by volume or more, 30% by volume or more, 40% by volume or more, 50% by volume or more, 60% by volume or more, 70% by volume or more, 80% by volume or more, 85% by volume or more, or more than 85% by volume. The method for measuring the refractive index of the porous layer is not particularly limited, and can be measured, for example, by the following method.

[0053] (Evaluation of void remaining rate of porous layer) The produced laminate is placed in an oven at a temperature of 85°C and a humidity of 85% RH, and a heat and humidity durability test is performed for 500 hours. After the heat and humidity durability test, the degree of filling of the voids in the porous layer is confirmed using an SEM, and the void remaining rate can be calculated.

[0054] The thickness of the air gap layer of the present disclosure is not particularly limited, and the lower limit is, for example, 0.05 μm or more, or 0.1 μm or more, and the upper limit is, for example, 1000 μm or less, 100 μm or less, 10 μm or less, 5 μm or less, or 2 μm or less, and the range is, for example, 0.05 to 1000 μm, or 0.1 to 100 μm.

[0055] The form of the porous layer of the present disclosure is not particularly limited, and may be, for example, a film shape or a block shape.

[0056] The method for producing the void layer of the present disclosure is not particularly limited, and the void layer can be produced, for example, by the method for producing a void layer described below or the method described in WO 2019 / 065999 or WO 2019 / 065803, the disclosures of which are incorporated herein by reference.

[0057] In the present disclosure, the adhesive layer is not particularly limited. In the present disclosure, the adhesive or pressure-sensitive adhesive forming the adhesive layer is not particularly limited, and for example, a general adhesive or pressure-sensitive adhesive can be used. Examples of the adhesive or pressure-sensitive adhesive include polymer adhesives such as acrylic, vinyl alcohol, silicone, polyester, polyurethane, and polyether adhesives, and rubber adhesives. Other examples include adhesives composed of water-soluble crosslinkers for vinyl alcohol polymers such as glutaraldehyde, melamine, and oxalic acid. These adhesives and pressure-sensitive adhesives may be used alone or in combination (e.g., mixed, laminated, etc.). The thickness of the adhesive layer is not particularly limited, and may be, for example, 0.1 to 100 μm, 5 to 50 μm, 10 to 30 μm, or 12 to 25 μm.

[0058] In the adhesive layer of the laminate of the present disclosure, the nanoindentation hardness is, for example, 0.5 MPa or more. The lower limit of the nanoindentation hardness may be, for example, 0.55 MPa or more, 0.6 MPa or more, or 0.65 MPa or more, and the upper limit may be, for example, 2.0 MPa or less, 1.5 MPa or less, 1.3 MPa or less, or 1.1 MPa or less. The method for measuring the nanoindentation hardness is not particularly limited, and it can be measured, for example, by the following method.

[0059] (Evaluation of Nanoindentation Hardness) A measurement sample is cut into a size of approximately 1 cm square and fixed to a predetermined support, and the nanoindentation hardness of the adhesive layer in the laminate of the present disclosure is measured under the following conditions. The nanoindentation hardness can be measured by a nanoindentation method. - Analysis device: Triboindenter manufactured by Hysitron Inc. - Indenter used: Conical (spherical: diameter 20 μm) - Measurement method: Single indentation measurement - Measurement temperature: Room temperature - Indentation depth: 2000 nm

[0060] The nanoindentation hardness is calculated from the maximum load (Pmax) and the contact projected area (A) obtained by the measurement using the following formula: Nanoindentation hardness = Pmax / A

[0061] The nanoindentation hardness may be measured on either the surface of the adhesive layer or the cross section of the adhesive layer.

[0062] In the laminate of the present disclosure, the interlayer peel strength between the void layer and the adhesive layer, measured using a tensile tester at a tensile speed of 0.3 m / min, is, for example, 3 N / 25 mm or more. The lower limit of the peel strength may be, for example, 3.5 N / 25 mm or more, 4.0 N / 25 mm or more, or 5.0 N / 25 mm or more. Since the mechanical strength between layers of the laminate of the present disclosure improves as the peel strength increases, the upper limit of the peel strength is not particularly limited, but is, for example, 20 N / 25 mm or less, 15 N / 25 mm or less, or 10 N / 25 mm or less. The peel strength is, for example, the peel strength measured due to cohesive failure of the void layer. The method for measuring the peel strength is not particularly limited, and can be measured, for example, by the following method.

[0063] (Evaluation of Interlayer Peel Strength) A resin film substrate having a void layer (void layer of the present disclosure) and a tacky adhesive layer (tacky adhesive layer in the laminate of the present disclosure) formed thereon was prepared, and an acrylic adhesive layer (thickness 20 μm) was bonded to the side of the resin film substrate opposite the void layer. The bonded sample was cut into 50 mm x 25 mm to prepare an adhesive tape piece. Next, the tacky adhesive layer (thickness 10 μm) on the void layer side was bonded to a PET film (T100: manufactured by Mitsubishi Plastics Film Co., Ltd.) cut into a 25 mm x 100 mm strip, and the acrylic adhesive layer on the resin film substrate side was laminated and fixed to glass. The sample thus prepared was chucked in a tensile tester (manufactured by Shimadzu Corporation, product name: Autograph (registered trademark) AG-Xplus) so that the chuck distance was 100 mm, and then a 180° peel test was performed at a tensile speed of 0.3 m / min. A 50 mm peel test is carried out N=3 times, and the average test force is taken as the peel strength between the layers.

[0064] The refractive index of the void layer of the present disclosure measured in the state of the laminate is, for example, 1.30 or less. The upper limit of the refractive index of the void layer measured in the state of the laminate is, for example, 1.30 or less, less than 1.30, 1.26 or less, 1.25 or less, less than 1.25, 1.24 or less, 1.23 or less, or 1.22 or less, and the lower limit is, for example, 1.05 or more, 1.10 or more, 1.15 or more, 1.16 or more, 1.17 or more, 1.18 or more, or 1.19 or more, and the range is, for example, 1.05 or more to 1.30 or less, 1.05 or more to 1.30 or less, 1.10 or more to 1.25 or less, 1.15 or more to 1.25 or less, or 1.19 or more to 1.25 or less. The method for measuring the refractive index of the void layer of the present disclosure measured in the state of the laminate is not particularly limited, and can be measured, for example, by the following method.

[0065] (Evaluation of refractive index of void layer measured in laminate state) A prism of a prism coupler (manufactured by Metricon) is closely attached to the substrate surface side of a laminate (glass / adhesive layer / void layer / acrylic substrate) in which an adhesive layer is provided on an adhesive layer, and the total reflection critical angle is measured using a laser. The refractive index can be calculated from the measured critical angle value.

[0066] The laminate of the present disclosure may satisfy the following condition (1), for example, when the refractive index is X and the peel strength is Y. Figure 4 shows a graph illustrating the relationship between peel strength and refractive index under condition (1). In Figure 4, the horizontal axis represents the refractive index, and the vertical axis represents the peel strength (N / 25 mm). Condition (1): Y≧80X−93.8

[0067] Furthermore, the laminate of the present disclosure may satisfy the following condition (2), where X is the refractive index and Y is the peel strength. Figure 4 shows a graph illustrating the relationship between the peel strength and the refractive index under condition (1). Condition (2): Y≧100X−117

[0068] When the condition (1) or the condition (2) is satisfied, for example, a laminate having a low refractive index and high peel strength (i.e., excellent mechanical strength) can be obtained. In order to satisfy the condition (1) and the condition (2), the types, content ratios, etc. of the tetrafunctional silane compound and the additives may be appropriately adjusted, although not particularly limited thereto.

[0069] In the present disclosure, the intermediate layer is not particularly limited, but may be, for example, a layer formed by merging a part of the void layer with a part of the adhesive layer, as described above. The thickness of the intermediate layer is not particularly limited, but may be, for example, 1 to 1500 nm, 5 to 1000 nm, 10 to 800 nm, or 20 to 500 nm.

[0070] The form of the laminate of the present disclosure is not particularly limited, but is usually in the form of a film.

[0071] The laminate of the present disclosure is, for example, a roll body. Furthermore, the laminate of the present disclosure may, for example, further include a resin film, as described above, and the void layer may be formed on the long resin film. In this case, another long film may be laminated on the laminate of the present disclosure, or another long resin film (for example, an interleaf paper, a release film, a surface protective film, etc.) may be laminated on the laminate of the present disclosure including the resin film and the void layer, and then wound into a roll body.

[0072] The method for producing the laminate of the present disclosure is not particularly limited, and the laminate can be produced, for example, by the production method of the present disclosure shown below. Furthermore, unless otherwise specified, the method for producing the optical laminate of the present disclosure that does not include a resin film can be performed in the same manner as the production method of the laminate of the present disclosure, except that no resin film is used.

[0073] [2. Method for producing void layer and laminate] The method for producing the void layer and laminate of the present disclosure is not particularly limited, and can be, for example, the production method described below. However, the following description is an example and does not limit the present disclosure in any way.

[0074] A method for producing a laminate including a void layer according to the present disclosure includes, for example, a void layer forming step of forming the void layer, and an adhesive layer forming step of forming the adhesive layer on the void layer. The method for producing a laminate may further include an intermediate layer forming step of reacting the void layer with the adhesive layer to form the intermediate layer.

[0075] As described above, the void layer forming process (the void layer manufacturing method of the present disclosure) includes a gel silica synthesis process, a gel crushing process, and a bonding process. The void layer forming process (the void layer manufacturing method of the present disclosure) may or may not include other processes in addition to the gel silica synthesis process, the gel crushing process, and the bonding process. The other processes are not particularly limited, and examples thereof include a coating process and a drying process, which will be described later.

[0076] The gel silica synthesis step includes a step of synthesizing a gel silicon compound by condensing or partially condensing the silane compound. The gel silica synthesis step may include, for example, a step of gelling a massive porous body in a solvent to form a gel. In this case, for example, the gel gelled in the gel silica synthesis step is used in the first grinding stage (for example, the first grinding stage) of multiple grinding stages described below.

[0077] The method for producing the void layer includes, for example, an aging step of aging the gel in a solvent, and in this case, for example, the gel after the aging step is used in the first crushing step (for example, the first crushing step) of the multiple crushing steps.

[0078] The gel-crushing step includes a step of crushing the gel silicon compound to obtain a crushed product. The gel-crushing step may be performed in one step, but is preferably performed in multiple crushing steps. The number of crushing steps is not particularly limited, and may be, for example, two steps, or three or more steps.

[0079] The volume average particle diameter of the gel after the first pulverization step may be, for example, 0.5 to 100 μm, 1 to 100 μm, 1 to 50 μm, 2 to 20 μm, or 3 to 10 μm. The volume average particle diameter of the gel after the second pulverization step may be, for example, 10 to 1000 nm, 100 to 500 nm, or 200 to 300 nm. The volume average particle diameter indicates the particle size variation of the pulverized material in the liquid containing the gel (gel-containing liquid). The volume average particle diameter can be measured, for example, using a particle size distribution evaluation device such as a dynamic light scattering method or a laser diffraction method, or an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0080] In the method for producing a porous layer according to the present disclosure, for example, after the gel silica synthesis step, the solvent substitution step is performed in which the solvent is substituted with another solvent, and in this case, the gel in the other solvent is used in the first crushing step (e.g., the first crushing step) of the multiple crushing steps.

[0081] In at least one of the multiple grinding stages (e.g., at least one of the first grinding stage and the second grinding stage) of the method for manufacturing a porous layer according to the present disclosure, the grinding of the porous body is controlled, for example, while measuring the shear viscosity of the liquid.

[0082] At least one of the multiple pulverization steps (for example, at least one of the first pulverization step and the second pulverization step) in the method for producing a porous layer according to the present disclosure is carried out by, for example, high-pressure media-less pulverization.

[0083] In the manufacturing method of the porous layer of the present disclosure, the gel pulverized material-containing liquid obtained by the process including the gel pulverization process may be simply referred to as "gel pulverized material-containing liquid" hereinafter.

[0084] The gel pulverized material-containing liquid can form a porous layer as a functional porous body by, for example, forming a coating film and chemically bonding the pulverized material in the coating film through a bonding process. The gel pulverized material-containing liquid can provide the porous layer to various objects. Therefore, the gel pulverized material-containing liquid and its manufacturing method are useful, for example, in manufacturing the porous layer.

[0085] The liquid containing the pulverized gel has, for example, extremely excellent uniformity, and therefore, when the porous layer is used for applications such as optical components, the appearance of the optical components can be improved.

[0086] The gel powder-containing liquid may be, for example, a gel powder-containing liquid that is coated onto a substrate (coating process) and then dried (drying process) to obtain a layer having a high porosity (porous layer).

[0087] In the coating step, the coating method of the gel pulverized material-containing liquid is not particularly limited, and a general coating method can be used. Examples of the coating method include slot die coating, reverse gravure coating, microgravure coating, dip coating, spin coating, brush coating, roll coating, flexographic printing, wire bar coating, spray coating, extrusion coating, curtain coating, and reverse coating. Among these, from the viewpoints of productivity and smoothness of the coating film, extrusion coating, curtain coating, roll coating, and microgravure coating are preferred. The coating amount of the gel pulverized material-containing liquid is not particularly limited, and can be appropriately set, for example, so that the thickness of the void layer is appropriate. The thickness of the void layer is not particularly limited, and is, for example, as described above.

[0088] In the drying step, the gel pulverized product-containing liquid is dried (i.e., the dispersion medium contained in the gel pulverized product-containing liquid is removed), forming a coated film (a precursor of the void layer) after drying. The drying temperature in the drying step is, for example, 50 to 250 ° C, 60 to 150 ° C, or 70 to 130 ° C, and the drying time is, for example, 0.1 to 30 minutes, 0.2 to 10 minutes, or 0.3 to 3 minutes. Regarding the drying temperature and time, lower and shorter drying temperatures are preferable, for example, in relation to continuous productivity and the development of high porosity. If the conditions are too strict, for example, in the case where the substrate is a resin film, the substrate may expand in the drying oven as the temperature approaches the glass transition temperature of the substrate, and defects such as cracks may occur in the formed void structure immediately after coating. On the other hand, if the conditions are too lenient, for example, in roll-to-roll processing, residual solvent may be contained when the film leaves the drying oven, which may cause appearance defects such as scratches when rubbed against the roll in the next process.

[0089] The drying method may be, for example, natural drying, heat drying, or reduced pressure drying. The drying method is not particularly limited, and for example, a general heating means can be used. Examples of the heating means include a hot air blower, a heating roll, and a far-infrared heater. Among these, heat drying is preferably used when industrial continuous production is assumed.

[0090] The bonding step includes chemically bonding the pulverized material. The bonding step can be performed, for example, by irradiating or heating the coating film containing a catalyst or catalyst generator previously added to the gel pulverized material-containing liquid, or by spraying the catalyst onto the coating film and then irradiating or heating it, or by irradiating or heating it while spraying the catalyst or catalyst generator. The catalyst may be, for example, the crosslinking reaction accelerator or a strength improver that improves the strength of the void layer, or the crosslinking accelerator may also serve as the strength improver.

[0091] The integrated light amount of the light irradiation is not particularly limited, but is, for example, 200 to 800 mJ / cm in terms of @360 nm. ２, 250-600mJ / cm ２ , or 300 to 400 mJ / cm ２ From the viewpoint of preventing the effect from being insufficient due to insufficient irradiation amount resulting in insufficient decomposition of the catalyst generator due to light absorption, it is set to 200 mJ / cm ２ Furthermore, from the viewpoint of preventing damage to the substrate under the air gap layer and the occurrence of thermal wrinkles, an integrated light amount of 800 mJ / cm or more is preferable. ２ The following cumulative light intensity is recommended.

[0092] The heating temperature and heating time during the heating are not particularly limited, and the conditions of the heat treatment are not particularly limited. The heating temperature is, for example, 50 to 250°C, 60 to 150°C, or 70 to 130°C, and the heating time is, for example, 0.1 to 30 minutes, 0.2 to 10 minutes, or 0.3 to 3 minutes. Alternatively, as described above, the step of drying the coated pulverized gel-containing liquid may also serve as a step of carrying out a chemical reaction in the presence of the catalyst. That is, in the step of drying the coated pulverized gel-containing liquid (e.g., a suspension), the pulverized gel particles may be chemically bonded together by a chemical reaction in the presence of the catalyst. In this case, the coated film may be further heated after the drying step to further firmly bond the pulverized gel particles (microporous particles). Furthermore, it is speculated that the chemical reaction in the presence of the catalyst may also occur in the step of preparing the microporous particle-containing liquid (e.g., a suspension) and the step of applying the microporous particle-containing liquid. However, this assumption does not limit the present disclosure in any way.

[0093] The adhesive layer forming step may include, for example, an adhesive coating liquid applying step of applying the adhesive coating liquid to a substrate and a heat drying step of heating and drying the substrate coated with the adhesive coating liquid. For example, the adhesive layer may be formed on the void layer by laminating the adhesive layer side of an adhesive tape or the like having the adhesive layer laminated on a substrate onto the void layer. In this case, the substrate such as the adhesive tape may be left attached as is or may be peeled off from the adhesive layer. In particular, peeling off the substrate to form a substrate-free (substrate-less) laminate can significantly reduce the thickness and suppress an increase in the thickness of a device or the like. In the present disclosure, the adhesive layer can be produced, for example, using the adhesive coating liquid as described above.

[0094] The adhesive layer forming step can be performed, for example, as follows. First, the adhesive coating liquid is produced by a mixing step of mixing all components of the adhesive coating liquid. The adhesive coating liquid may contain, for example, a (meth)acrylic polymer, and may or may not further contain a crosslinking agent (e.g., an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent). The adhesive coating liquid may contain, for example, the (meth)acrylic polymer, a monomer having one or two reactive double bonds per molecule, a crosslinking agent, and an organic peroxide. In this case, if the adhesive coating liquid contains other components, the other components may also be mixed together. For example, the polymerization solvent used in producing the (meth)acrylic polymer may be mixed directly as a component of the adhesive coating liquid without removing it. The method for producing the adhesive coating liquid may, but need not, include other steps other than the mixing step. Alternatively, the method may simply involve mixing all components of the adhesive coating liquid in the mixing step.

[0095] Next, the adhesive coating liquid is applied to a substrate (adhesive coating liquid application step). The substrate is not particularly limited and may be, for example, a substrate such as a film. Examples of suitable substrates include, but are not limited to, substrates made of thermoplastic resins, glass substrates, inorganic substrates such as silicon, plastics molded from thermosetting resins, semiconductor elements, and carbon fiber materials such as carbon nanotubes. Examples of the substrate include, but are not limited to, films and plates. Examples of thermoplastic resins include polyethylene terephthalate (PET), acrylic, cellulose acetate propionate (CAP), cycloolefin polymer (COP), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polyethylene (PE), and polypropylene (PP). In the adhesive coating liquid application step, the thickness of the adhesive coating liquid is not particularly limited and may be adjusted appropriately so that the adhesive layer has a predetermined thickness after drying. The thickness of the adhesive layer after drying is also not particularly limited and may be, for example, as described below.

[0096] Next, the substrate coated with the adhesive coating liquid is heated and dried (heat-drying step). In this heat-drying step, the heat-drying temperature is not particularly limited, but may be, for example, 50°C or higher, 80°C or higher, 100°C or higher, or 155°C or higher, and may be, for example, 200°C or lower, 180°C or lower, or 160°C or lower. The heat-drying time is not particularly limited, but may be, for example, 0.5 minutes or higher, 1 minute or higher, or 3 minutes or higher, and may be, for example, 60 minutes or lower, 30 minutes or lower, 20 minutes or lower, or 10 minutes or lower. In this heat-drying step, for example, a crosslinking reaction and graft polymerization occur between the (meth)acrylic polymer and the crosslinking agent. This reduces the amount of semi-high molecular weight polymer present in the adhesive coating liquid, as described above, making it difficult for the adhesive layer to penetrate into the recesses of the first optical sheet. In this manner, the adhesive layer used in the laminate of the present disclosure can be produced.

[0097] Next, as described above, the adhesive layer and the void layer are bonded together (lamination step). This method is not particularly limited, but for example, as described above, the adhesive layer may be formed on the void layer by bonding the adhesive layer side of an adhesive tape, etc., in which the adhesive layer of the present disclosure is laminated on a substrate, onto the void layer. In this manner, the laminate of the present disclosure can be produced.

[0098] The thickness of the adhesive layer is not particularly limited, but is, for example, 0.1 to 100 μm, 5 to 50 μm, 10 to 30 μm, or 12 to 25 μm.

[0099] In the method for producing a laminate according to the present disclosure, for example, a heating step may be further performed after the laminating step, in which the adhesive layer and the void layer are heated. Hereinafter, this heating step may be referred to as an "aging step." In the heating step (aging step), the heating temperature is not particularly limited, but may be, for example, 40°C or higher, 45°C or higher, or 50°C or higher, and may be, for example, 80°C or lower, 70°C or lower, 60°C or lower, or 55°C or lower. The heating time is not particularly limited, but may be, for example, 1 minute or longer, 10 minutes or longer, 60 minutes or longer, or 1800 minutes or longer, and may be, for example, 3000 minutes or shorter, 2800 minutes or shorter, 2500 minutes or shorter, or 2000 minutes or shorter. In this aging step, for example, the intermediate layer is formed by the union of the void layer and the adhesive layer. Then, for example, the intermediate layer acts as a stopper, and a decrease in porosity due to the voids in the void layer being filled with the adhesive can be suppressed. The fusion of the void layer and the adhesive layer may be such that the adhesive layer is embedded in the voids of the void layer and chemically bonded to it, or such that the adhesive layer is embedded in the voids of the void layer.

[0100] The adhesive layer can protect the void layer from physical damage (particularly scratches). The adhesive layer is preferably, but not particularly limited to, one that has excellent pressure resistance so that the void layer is not crushed even in a void layer-containing adhesive sheet that does not have a substrate (substrate-less).

[0101] The laminate of the present disclosure thus obtained may be further laminated with another film (layer) to form a laminate structure including the void layer (porous structure), as described above. In this case, each component of the laminate structure may be laminated via, for example, the adhesive layer (pressure-sensitive adhesive or adhesive).

[0102] The lamination of the components may be carried out by continuous processing (so-called roll-to-roll processing, etc.) using a long film, for example, because this is efficient. When the substrate is a molded product, element, or the like, the components may be laminated after batch processing.

[0103] [3. Optical Member] As described above, the optical member of the present disclosure includes the void layer of the present disclosure or the laminate of the present disclosure. The optical member of the present disclosure is characterized by including the void layer of the present disclosure or the laminate of the present disclosure, and other configurations are not limited in any way. The optical member of the present disclosure may further include other layers in addition to the void layer or the laminate, for example. The optical member of the present disclosure is, for example, in a roll form.

[0104] [4. Optical Device] As described above, the optical device of the present disclosure includes the optical member of the present disclosure. The optical device of the present disclosure is not particularly limited, and may be, for example, an image display device or a lighting device. Examples of the image display device include a liquid crystal display, an organic electroluminescence (EL) display, and a micro LED (light-emitting diode) display. Examples of the lighting device include an organic EL light.

[0105] Next, examples of the present disclosure will be described, but the present disclosure is not limited to the following examples.

[0106] 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, a pressure-sensitive adhesive (pressure-sensitive adhesive composition) described below was used as the pressure-sensitive adhesive. In the following Reference Examples, Examples, and Comparative Examples, the term "pressure-sensitive adhesive layer" corresponds to the term "pressure-sensitive adhesive layer." That is, in the following Reference Examples, Examples, and Comparative Examples, the terms "pressure-sensitive adhesive layer" and "pressure-sensitive adhesive layer" have the same meaning unless otherwise specified.

[0107] In addition, in the following reference examples, examples, and comparative examples, the nanoindentation hardness, the refractive index of the void layer measured in the laminate state (refractive index (laminate)), and the refractive index when only the void layer is measured (refractive index (void layer)), peel strength, and void remaining rate were each measured by the methods described in the embodiments.

[0108] In the adhesive layers in the following Reference Examples, Examples, and Comparative Examples, it is presumed that the polymer (acrylic polymer) is crosslinked by the crosslinking agent when the applied adhesive is heated and dried, thereby forming a crosslinked structure, but the crosslinked structure has not been confirmed.

[0109] Reference Example 1: Formation of adhesive layer (adhesive 1) The adhesive layer of this reference example (Reference Example 1) was formed by the following procedures (1) to (3).

[0110] (1) Preparation of Acrylic Polymer Solution Into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 90.7 parts of butyl acrylate, 6 parts of N-acryloylmorpholine, 3 parts of acrylic acid, 0.3 parts of 2-hydroxybutyl acrylate, and 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator were placed together with 100 g of ethyl acetate. Next, nitrogen gas was introduced into the contents of the four-neck flask while gently stirring to replace the atmosphere with nitrogen. Thereafter, the liquid temperature in the four-neck flask was maintained at around 55°C, and a polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution.

[0111] (2) Preparation of Acrylic Pressure-Sensitive Adhesive Composition An acrylic pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive solution) was prepared by blending 0.2 parts of an isocyanate crosslinking agent (trade name "Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd., an adduct of trimethylolpropane and tolylene diisocyanate), 0.3 parts of benzoyl peroxide (trade name "Niper BMT" manufactured by Nippon Oil & Fats Corporation), and 0.1 parts of γ-glycidoxypropylmethoxysilane (trade name "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.) with 100 parts of the solid content of the acrylic polymer solution obtained in (1) above.

[0112] (3) Formation of Tacky-Adhesive Layer The acrylic pressure-sensitive adhesive composition obtained in (2) above was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Film Corporation, thickness: 38 μm) so that the thickness of the pressure-sensitive adhesive layer after drying would be 10 μm, and the applied coating was dried at 150° C. for 3 minutes to form a pressure-sensitive adhesive layer (tacky-adhesive layer) called Pressure-sensitive Adhesive 1.

[0113] Reference Example 2: Formation of adhesive layer (adhesive 2) The adhesive layer of this reference example (reference example 2) was formed by the following procedures (1) to (3).

[0114] (1) Preparation of (meth)acrylic polymer (A1) solution A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 79.5 parts of butyl acrylate, 15 parts of N-acryloylmorpholine, 5 parts of acrylic acid, and 0.5 parts of 4-hydroxybutyl acrylate. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 70 parts of ethyl acetate were charged to 100 parts of the monomer mixture. Nitrogen gas was introduced with gentle stirring to replace the atmosphere. The temperature in the flask was maintained at around 55°C, and a polymerization reaction was carried out for 2 hours to prepare a solution of (meth)acrylic polymer (A1) with a weight average molecular weight (Mw) of 3,000,000 and an Mw / Mn ratio of 2.5.

[0115] (2) Preparation of (meth)acrylic pressure-sensitive adhesive composition 0.2 parts of an isocyanate crosslinking agent (trade name "Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd., an adduct of trimethylolpropane and tolylene diisocyanate) and 0.2 parts of an epoxy crosslinking agent 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (trade name "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Inc.) were blended with 100 parts of the solid content of the obtained solution of the (meth)acrylic polymer (A1) to prepare a solution of an acrylic pressure-sensitive adhesive composition.

[0116] (3) Formation of Pressure-Sensitive Adhesive Layer Next, the solution of the acrylic pressure-sensitive adhesive composition was applied to one surface of a polyethylene terephthalate film (separator film: MRF38, manufactured by Mitsubishi Chemical Polyester Film Corporation) that had been treated with a silicone release agent, so that the thickness of the pressure-sensitive adhesive layer after drying would be 10 μm, and the coating was dried at 155° C. for 1 minute, thereby forming Pressure-Sensitive Adhesive 2, which was a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer), on the surface of the separator film.

[0117] Reference Example 3: Formation of adhesive layer (adhesive 3) The adhesive layer of this reference example (Reference Example 3) was formed by the following procedures (1) to (3).

[0118] (1) Preparation of acrylic polymer solution Into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 99 parts of butyl acrylate, 1 part of 4-hydroxybutyl acrylate, and 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator were placed together with 100 parts of ethyl acetate. Next, nitrogen gas was introduced into the contents of the four-neck flask while gently stirring to replace the atmosphere with nitrogen. Thereafter, the liquid temperature in the four-neck flask was maintained at around 55°C, and a polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution.

[0119] (2) Preparation of Acrylic Pressure-Sensitive Adhesive Composition A solution of an acrylic pressure-sensitive adhesive composition was prepared by blending 0.1 parts of an isocyanate crosslinking agent (Takenate D110N, product name, manufactured by Mitsui Takeda Chemicals, Inc., trimethylolpropane xylylene diisocyanate), 0.1 parts of benzoyl peroxide (Niper BMT, product name, manufactured by Nippon Oil & Fats Corporation), and 0.2 parts of γ-glycidoxypropyl methoxysilane (KBM-403, product name, manufactured by Shin-Etsu Chemical Co., Ltd.) with 100 parts of the solid content of the acrylic polymer solution obtained in (1) above.

[0120] (3) Formation of Tacky-Adhesive Layer The solution of the acrylic pressure-sensitive adhesive composition obtained in (2) above was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Corporation, product name "MRF38") that had been treated with a silicone-based release agent, and dried at 150°C for 3 minutes to form a pressure-sensitive adhesive layer (tacky-adhesive layer) 3 having a thickness of 20 µm on the surface of the separator film.

[0121] [Examples 1 to 8, Comparative Examples 1 to 3: Production of Laminates Containing Void Layers] Laminates containing void layers in Examples 1 to 8 and Comparative Examples 1 to 3 were produced by the following method.

[0122] (Example 1) (1) Gelation of Silicon Compound (Gel Silica Synthesis Step) 1.90 g of methyltrimethoxysilane (MTMS), a precursor of a silicon compound, and 0.1 g of tetraethoxysilane (TEOS) were dissolved in 4.4 g of dimethyl sulfoxide (DMSO) to prepare a mixed solution A. 1.0 g of a 0.01 mol / L aqueous oxalic acid solution was added to the mixed solution A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS, producing a mixed solution B containing tris(hydroxy)methylsilane and tetra(hydroxy)silane. 0.38 g of 28 wt% aqueous ammonia and 0.2 g of pure water were added to 5.5 g of DMSO, and then the mixed solution B was further added and stirred at room temperature for 15 minutes to gel the tris(hydroxy)methylsilane and tetra(hydroxy)silane, thereby obtaining a mixed solution C containing a gel silicon compound.

[0123] (2) Aging Treatment The mixed solution C containing the gel silicon compound prepared as above was incubated at 40° C. for 20 hours to carry out an aging treatment.

[0124] (3) Pulverization Treatment (Gel Pulverization Step) Next, the gel-like silicon compound aged as described above was crushed into granules of several mm to several cm in size using a spatula. Next, 40 g of isopropyl alcohol (IPA) was added to the mixed solution C, and after light stirring, the mixture was left to stand at room temperature for 6 hours, and the solvent and catalyst in the gel were decanted. The same decantation treatment was performed three times to replace the solvent, and mixed solution D was obtained. Next, the gel-like silicon compound in mixed solution D was subjected to a pulverization treatment (high-pressure media-less pulverization). The pulverization treatment (high-pressure media-less pulverization) was performed using a homogenizer (manufactured by SMT Corporation, trade name "UH-50"), and 1.85 g of the gel-like compound and 1.15 g of IPA in mixed solution D were weighed into a 5 cc screw bottle, and then pulverized for 2 minutes under conditions of 50 W and 20 kHz.

[0125] This grinding process pulverized the gel-like silicon compound in the mixed solution D, and the mixed solution D became a pulverized sol solution E. The volume average particle diameter, which indicates the particle size variation of the pulverized material contained in sol solution E, was confirmed using a dynamic light scattering Nanotrac particle size analyzer (manufactured by Nikkiso Co., Ltd., UPA-EX150 model), and was found to be 0.50 to 0.70 μm. Furthermore, to 0.75 g of sol solution E, 0.124 g of a 1.5 wt % MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd., product name: WPBG266), which is a precursor of the crosslinking reaction accelerator, and 0.036 g of a 5% MEK solution of a crosslinking auxiliary (bis(trimethoxysilyl)hexane) were added in a ratio of 0.036 g to obtain a coating liquid for forming a low refractive index layer.

[0126] The coating liquid for forming a low refractive index layer was applied to an acrylic substrate and dried to form a void layer with a film thickness of approximately 850 nm (void ratio: 59% by volume). The coating was performed using a wire bar, and the drying temperature and drying time were 100°C and 2 minutes, respectively. Next, UV irradiation (300 mJ) was performed from the void layer surface to bond the pulverized gel compound together (bonding process). It is presumed that the bonding between the pulverized gel compound particles in the bonding process includes at least one of a crosslinking bond (covalent bond) in which the pulverized particles are directly bonded without the aid of a crosslinking auxiliary, and a crosslinking bond (covalent bond) via the aid of the crosslinking auxiliary. Then, a 10 μm thick adhesive 1 was attached to the void layer surface and aged at 50°C for 30 hours to produce the void layer of this example. Furthermore, the laminate of this example was produced using the produced void layer.

[0127] Example 2 A voided layer of this example was produced by the same procedure as in Example 1, except that the amounts of the photobase generator and crosslinking aid added in Example 1 were changed to 0.186 g of a 1.5 wt % MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd., product name: WPBG266) and 0.054 g of a 5% MEK solution of a crosslinking aid (1,6-bis(trimethoxysilyl)hexane) per 0.75 g of sol solution E. In addition, the produced voided layer was used to produce a laminate of this example.

[0128] Example 3 A void layer of this example was produced by the same procedure as in Example 1, except that the amount of tetraethoxysilane (TEOS) added in Example 1 was changed to 0.2 g. The void layer thus produced was used to produce a laminate of this example.

[0129] Example 4 A void layer of this example was produced by the same procedure as in Example 2, except that the amount of tetraethoxysilane (TEOS) added in Example 1 was changed to 0.2 g. The void layer thus produced was used to produce a laminate of this example.

[0130] (Example 5) A void layer of this example was produced by the same procedure as in Example 1, except that adhesive 2 was used instead of adhesive 1 used in Example 1. In addition, a laminate of this example was produced using the produced void layer.

[0131] Example 6 A void layer of this example was produced by the same procedure as in Example 1, except that the amount of tetraethoxysilane (TEOS) added in Example 1 was changed to 0.3 g. The void layer thus produced was used to produce a laminate of this example.

[0132] Example 7 A void layer of this example was produced by the same procedure as in Example 1, except that the amount of tetraethoxysilane (TEOS) added in Example 1 was changed to 0.4 g. The void layer thus produced was used to produce a laminate of this example.

[0133] Example 8 The same operation as in Example 1 was carried out to produce a voided layer of this example, except that the amount of tetraethoxysilane (TEOS) added in Example 1 was changed to 0.2 g, and the amounts of the photobase generator and bis-crosslinking accelerator added were changed to 0.062 g of a 1.5 wt % MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd., product name: WPBG266) and 0.018 g of a 5% MEK solution of a bis-crosslinking accelerator ((trimethoxysilyl)hexane), relative to 0.75 g of sol solution E. The voided layer thus produced was then used to produce a laminate of this example.

[0134] Comparative Example 1 A gap layer of this comparative example was produced in the same manner as in Example 9, except that tetraethoxysilane (TEOS) was not added. The produced gap layer was used to produce a laminate of this comparative example.

[0135] (Comparative Example 2) A void layer of this comparative example was produced by the same procedure as in Comparative Example 1, except that adhesive 2 was used instead of adhesive 1 used in Comparative Example 1. In addition, the produced void layer was used to produce a laminate of this example.

[0136] (Comparative Example 3) A void layer of this comparative example was produced by the same procedure as in Comparative Example 1, except that adhesive 3 was used instead of adhesive 1 used in Comparative Example 1. In addition, a laminate of this comparative example was produced using the produced void layer.

[0137]

[0138] As shown in Table 1, the laminates including the porous layer of the Examples had good interlayer peel strengths of 3 N / 25 mm or more, whereas the laminates of the Comparative Examples all had interlayer peel strengths of less than 3 N / 25 mm.

[0139] 4 shows a graph illustrating the relationship between peel strength and refractive index for Examples and Comparative Examples in which the nanoindentation hardness when formed into a laminate is 0.5 MPa or more. In FIG. 4, the formula "Y = 136.4x - 159.92" is a linear function obtained by averaging the two points of Examples 1 and 2, in which a tetrafunctional silane compound was blended at 3.5 mol% relative to the trifunctional silane compound, and only the amounts of the substance that generates the crosslinking auxiliary and crosslinking reaction accelerator were changed. The formula "Y = 141.37x - 165.06" is a linear function obtained by averaging the three points of Examples 3, 4, and 8, in which a tetrafunctional silane compound was blended at 6.9 mol% relative to the trifunctional silane compound, and only the amounts of the substance that generates the crosslinking auxiliary and crosslinking reaction accelerator were changed.

[0140] As shown in Figure 4, in all Examples, the peel strength between the void layer and the adhesive layer was 3 N / 25 mm or more. Furthermore, the void layers of all Examples satisfied the condition (1) (Y ≥ 80X - 93.8) described in the embodiment. Furthermore, it was found that the void layers of the Examples, which contain a tetrafunctional silane compound as a silane compound, have higher peel strength than void layers having the same refractive index but not containing a tetrafunctional silane compound. In other words, the condition (2) (Y ≥ 100X - 117) described in the embodiment was satisfied. Furthermore, by increasing the content of the crosslinking auxiliary and the crosslinking reaction accelerator (precursor of the crosslinking reaction accelerator), the peel strength was further improved.

[0141] The present disclosure can be described, for example, as in the following supplementary notes: However, the supplementary notes below are examples, and the present disclosure is not limited to these forms.

[0142] (Appendix 1) A porous layer, wherein the porous layer is a porous layer in which pulverized gel silicon compound is chemically bonded, the gel silicon compound is a compound obtained by condensation or partial condensation of a silane compound, the silane compound contains a mono- to tri-functional silane compound and a tetra-functional silane compound, and the refractive index of the porous layer is 1.30 or less. (Appendix 2) The porous layer according to Appendix 1, wherein a content ratio of the tetra-functional silane compound to the amount of substance of the mono- to tri-functional silane compound is 1 to 25 mol %. (Appendix 3) The porous layer according to Appendix 1 or 2, wherein the porous layer is a porous layer in which pulverized gel silicon compound is chemically bonded in the presence of an additive, the additive contains at least one of a crosslinking reaction accelerator and a precursor thereof, and the precursor is a substance that generates the crosslinking reaction accelerator by light or heat. (Appendix 4) The porous layer according to Appendix 3, wherein the crosslinking reaction accelerator is an acidic substance or a basic substance. (Appendix 5) The porous layer according to Appendix 3 or 4, wherein the total content of the crosslinking reaction accelerator and its precursor is 1 mol % or more relative to the total substance amount of the mono- to tri-functional silane compound and the tetrafunctional silane compound. (Appendix 6) The porous layer according to any one of Appendixes 1 to 5, wherein the porous layer is a porous layer in which a pulverized product of the gel-like silicon compound is chemically bonded in the presence of an additive, and wherein the additive contains a crosslinking auxiliary. (Appendix 7) The porous layer according to Appendix 6, wherein the total content of the crosslinking auxiliary is 1 mol % or more relative to the total substance amount of the mono- to tri-functional silane compound and the tetrafunctional silane compound. (Appendix 8) A void layer, wherein the void layer is a void layer in which pulverized gel silicon compound is chemically bonded in the presence of an additive, the gel silicon compound is a compound obtained by condensing or partially condensing a silane compound, the additives include at least one of a crosslinking reaction accelerator and a precursor thereof, and a crosslinking auxiliary, the total content ratio of the crosslinking reaction accelerator and its precursor is 1.5 mol % or more relative to the total substance amount of the silane compound, and the total content ratio of the crosslinking auxiliary is 2.0 mol % or more, and the refractive index of the void layer is 1.30 or less.(Appendix 9) A method for manufacturing a porous layer, comprising a gel silica synthesis step, a gel-crushing step, and a bonding step, wherein the gel silica synthesis step comprises a step of synthesizing a gel silicon compound by condensing or partially condensing a silane compound, the silane compound comprising a mono- to tri-functional silane compound and a tetrafunctional silane compound, the gel-crushing step comprises a step of crushing the gel silicon compound to obtain a crushed product, and the bonding step comprises a step of chemically bonding the crushed product. (Appendix 10) A method for manufacturing a porous layer, comprising a gel silica synthesis step, a gel-crushing step, and a bonding step, wherein the gel silica synthesis step comprises a step of synthesizing a gel silicon compound by condensing or partially condensing a silane compound, the gel-crushing step comprises a step of crushing the gel silicon compound to obtain a crushed product, and the bonding step comprises a step of chemically bonding the crushed product in the presence of an additive, and the additives include at least one of a crosslinking reaction accelerator and a precursor thereof, and a crosslinking auxiliary. (Appendix 11) A laminate comprising the void layer according to any one of Appendices 1 to 8 and an adhesive layer, wherein the adhesive layer is directly laminated on one or both sides of the void layer. (Appendix 12) An optical member comprising the void layer according to any one of Appendices 1 to 8. (Appendix 13) An optical member comprising the laminate according to Appendices 11. (Appendix 14) An optical device comprising the optical member according to Appendices 12. (Appendix 15) The optical device according to Appendices 14, which is an image display device or an illumination device. (Appendix 16) An optical device comprising the optical member according to Appendices 13. (Appendix 17) The optical device according to Appendices 16, which is an image display device or an illumination device.

[0143] As described above, the present disclosure can provide a void layer having a low refractive index and excellent mechanical strength, a method for manufacturing a void layer, a laminate, an optical member, and an optical device. The applications of the present disclosure are not particularly limited. For example, the optical device of the present disclosure is not particularly limited, and examples thereof include image display devices and lighting devices. Examples of the image display devices include liquid crystal displays, organic EL displays, and micro LED displays. Examples of the lighting devices include organic EL lighting. Furthermore, the applications of the laminate of the present disclosure are not limited to the optical members and optical devices of the present disclosure, and are arbitrary, and the laminate can be used for a wide range of applications.

[0144] This application claims priority based on Japanese Patent Application No. 2023-107487, filed on June 29, 2023, the disclosure of which is incorporated herein in its entirety by reference.

[0145] 10, 10a, 10b, 10c, 10d, 10e laminate 11 void layer 12 adhesive layer 13 intermediate layer 14 base material

Claims

1. A porous layer, wherein the porous layer is a porous layer in which pulverized gel silicon compound is chemically bonded, the gel silicon compound is a compound in which a silane compound is condensed or partially condensed, the silane compound includes a mono- to tri-functional silane compound and a tetra-functional silane compound, and the refractive index of the porous layer is 1.30 or less.

2. The air gap layer according to claim 1, wherein the content ratio of said tetrafunctional silane compound to the amount of said mono-, di- or trifunctional silane compound is 1 to 25 mol %.

3. The porous layer according to claim 1, wherein the porous layer is a porous layer in which pulverized material of the gel-like silicon compound is chemically bonded in the presence of an additive, and the additive contains at least one of a crosslinking reaction accelerator and a precursor thereof, and the precursor is a substance that generates the crosslinking reaction accelerator by the application of light or heat.

4. The air gap layer according to claim 3, wherein the crosslinking reaction accelerator is an acidic or basic substance.

5. The air gap layer according to claim 3, wherein the total content of the crosslinking reaction accelerator and its precursor is 1 mol % or more relative to the total amount of the mono- to tri-functional silane compound and the tetrafunctional silane compound.

6. The porous layer according to claim 1, wherein the porous layer is a porous layer in which the pulverized gel silicon compound is chemically bonded in the presence of an additive, and the additive contains a crosslinking auxiliary.

7. The air gap layer according to claim 6, wherein the total content of said crosslinking auxiliary is 1 mol % or more based on the total amount of said mono- to tri-functional silane compound and said tetrafunctional silane compound.

8. A porous layer, wherein the porous layer is a porous layer in which pulverized material of a gel-like silicon compound is chemically bonded in the presence of an additive, the gel-like silicon compound is a compound obtained by condensing or partially condensing a silane compound, and the additives include at least one of a crosslinking reaction accelerator and a precursor thereof, and a crosslinking auxiliary, the total content of the crosslinking reaction accelerator and its precursor being 1.5 mol % or more relative to the total substance amount of the silane compound, and the total content of the crosslinking auxiliary being 2.0 mol % or more, and the refractive index of the porous layer being 1.30 or less.

9. A method for manufacturing a porous layer, comprising: a gel silica synthesis step, a gel crushing step, and a bonding step, wherein the gel silica synthesis step includes a step of synthesizing a gel silicon compound by condensing or partially condensing a silane compound, the silane compound including a mono- to tri-functional silane compound and a tetrafunctional silane compound, the gel crushing step includes a step of crushing the gel silicon compound to obtain a crushed product, and the bonding step includes a step of chemically bonding the crushed product.

10. A method for producing a void layer, comprising: a gel silica synthesis step, a gel crushing step, and a bonding step, wherein the gel silica synthesis step comprises a step of synthesizing a gel silicon compound by condensing or partially condensing a silane compound, the gel crushing step comprises a step of crushing the gel silicon compound to obtain a crushed product, and the bonding step comprises a step of chemically bonding the crushed product in the presence of an additive, and the additives include at least one of a crosslinking reaction accelerator and a precursor thereof, and a crosslinking auxiliary.

11. A laminate comprising the air gap layer according to any one of claims 1 to 8 and an adhesive layer, the adhesive layer being directly laminated on one or both sides of the air gap layer.

12. An optical member comprising the air gap layer according to any one of claims 1 to 8.

13. An optical member comprising the laminate according to claim 11.

14. An optical device comprising the optical member according to claim 12.

15. The optical device according to claim 14, which is an image display device or an illumination device.

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