Laminates, optical components, and optical devices

Abstract

To provide a laminate that achieves tacky strength or adhesive strength, while achieving less penetration of a tackiness agent or an adhesive agent into voids of a void layer.SOLUTION: A laminate of the invention includes a void layer and a tacky adhesion layer. The tacky adhesion layer is directly laminated on one face or both faces of the void layer. The tacky adhesion layer is made of a tacky adhesive agent containing a (meth) acrylic polymer and an oligomer-type silane coupling agent. The content of the oligomer-type silane coupling agent is 1 pt.mass or less relative to 100 pts.mass of the (meth) acrylic polymer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminate, an optical member, and an optical device.

Background Art

[0002] In an optical device, for example, an air layer having a low refractive index is used as a total reflection layer. Specifically, for example, each optical film member (e.g., a light guide plate and a reflector) in a liquid crystal device is laminated via an air layer. However, when each member is separated by an air layer, particularly when the member is large, there is a risk of problems such as deflection of the member. Further, due to the trend of thinning of the device, integration of each member is desired. For this reason, each member is integrated with an adhesive without passing through an air layer (for example, Patent Document 1). However, when the air layer that plays the role of total reflection disappears, there is a risk that optical characteristics such as light leakage will deteriorate.

[0003] Therefore, it has been proposed to use a low refractive index layer instead of an air layer. For example, Patent Document 2 describes a structure in which a layer having a lower refractive index than a 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 close to that of air as possible.

[0004] Furthermore, an integral configuration with an adhesive layer has also been proposed in order to introduce a void layer into the device (Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0006] The void layer is used, for example, by laminating it with other layers via an adhesive layer. However, when the void layer and the adhesive layer are laminated, the adhesive or bonding agent constituting the adhesive layer may penetrate into the voids of the void layer, filling the voids and potentially reducing the porosity of the void layer and increasing its refractive index. The higher the porosity of the void layer, the easier it is for the adhesive or bonding agent to penetrate. Furthermore, in high-temperature environments, the molecular motion of the adhesive or bonding agent (reduction in elastic modulus) makes it easier for the adhesive or bonding agent to penetrate the voids. In high-humidity environments, the water absorption of the adhesive or bonding agent makes it easier for the adhesive or bonding agent to penetrate the voids.

[0007] To suppress or prevent the penetration of the adhesive into the void, it is preferable to use an adhesive with a high modulus of elasticity (hardness) as much as possible. However, if the adhesive has a high modulus of elasticity (hardness), there is a risk that the adhesive strength or bonding strength will decrease. Conversely, if the adhesive has a low modulus of elasticity (softness), it is easier to obtain high adhesive strength or bonding strength, but there is a risk that the adhesive will penetrate into the void more easily.

[0008] Therefore, the present invention aims to provide laminates, optical components, and optical devices that achieve both adhesive strength and resistance to penetration of adhesives into the voids of the void layer. [Means for solving the problem]

[0009] To achieve the above objective, the laminate of the present invention is It includes a void layer and an adhesive layer, The adhesive layer is directly laminated on one or both sides of the void layer. The adhesive layer is formed by an adhesive containing a (meth)acrylic polymer and an oligomer-type silane coupling agent. The oligomer-type silane coupling agent is characterized in that the content is 1 part by mass or less per 100 parts by mass of the (meth)acrylic polymer.

[0010] The optical component of the present invention is characterized by including the laminate of the present invention.

[0011] The optical device of the present invention is characterized by including the optical component of the present invention. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide laminates, optical members, and optical devices that achieve both adhesive strength and resistance to penetration of adhesives into the voids of the void layer. [Brief explanation of the drawing]

[0013] [Figure 1] Figures 1(a) and 1(b) are cross-sectional views illustrating the structure of the laminate according to the present invention. [Figure 2] Figures 2(a) and (b) are cross-sectional views showing another example of the configuration of the laminate according to the present invention. [Figure 3] Figures 3(a) and (b) are cross-sectional views showing yet another example of the configuration of the laminate of the present invention. [Modes for carrying out the invention]

[0014] Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited in any way by the following description.

[0015] The laminate of the present invention may, for example, contain an epoxy group in the oligomer-type silane coupling agent.

[0016] The laminate of the present invention may, for example, have a weight-average molecular weight (Mw) of the (meth)acrylic polymer of 1.5 million to 4 million.

[0017] In the laminate of the present invention, for example, the weight average molecular weight (Mw) of the oligomeric silane coupling agent may be 300 or more.

[0018] In the laminate of the present invention, for example, the adhesive layer is formed of an adhesive containing the (meth)acrylic polymer and a crosslinking agent, and the adhesive may have a gel fraction exceeding 85%.

[0019] In the laminate of the present invention, for example, the (meth)acrylic polymer may contain 1 to 30% by mass of a nitrogen-containing monomer as a monomer unit. In the present invention, unless otherwise specified, "mass%" and "weight%" may be read interchangeably, and "parts by mass" and "parts by weight" may be read interchangeably.

[0020] In the laminate of the present invention, for example, before and after a heat durability test of holding at a temperature of 65°C and a relative humidity of 95% for 1000 hours, the increase amount of the refractive index of the void layer satisfies the following formula (1), and the initial refractive index before the heat durability test satisfies the following formula (2). n - n0 ≦ 0.015 (1) n0 < 1.2 > In the formula (1), n is the refractive index of the void layer after the heat durability test. In the formula (2), n0 is the refractive index of the void layer before the heat durability test.

[0021] In the laminate of the present invention, for example, an intermediate layer may exist between the void layer and the adhesive layer, and the intermediate layer may be a layer formed by the unification of the void layer and the adhesive layer.

[0022] In the laminate of the present invention, for example, the thickness of the intermediate layer may be 10 to 100 nm.

[0023] In the present invention, "adhesive layer" refers to a layer formed by at least one of an adhesive and a bonding agent. In the present invention, unless otherwise specified, the "adhesive layer" may be an "adhesive layer" formed by an adhesive, an "adhesive layer" formed by a bonding agent, or a layer containing both an adhesive and a bonding agent. In the present invention, adhesives and bonding agents are sometimes collectively referred to as "adhesive bonding agents." Generally, agents with relatively weak adhesive strength or bonding strength (for example, agents that allow for re-peeling of the bonded object) are called "adhesives," and agents with relatively strong adhesive strength or bonding strength (for example, agents that make re-peeling of the bonded object impossible or extremely difficult) are sometimes called "bonding agents" to distinguish them. In the present invention, there is no clear distinction between adhesives and bonding agents. Also, in the present invention, there is no clear distinction between "adhesive strength" and "bonding strength."

[0024] Furthermore, in the present invention, "on top of" or "on the surface" may refer to a state of direct contact with the top of or on the surface, or it may refer to a state of contact with another layer or the like.

[0025] The laminate of the present invention may, for example, be a (meth)acrylic polymer having a weight-average molecular weight of 2 million to 3.5 million, obtained by polymerizing 3 to 20% by mass of heterocyclic acrylic monomer (heterocyclic acrylate), 0.5 to 5% by mass of (meth)acrylic acid, 0.05 to 2% by mass of hydroxyalkyl (meth)acrylate, and 83 to 96.45% by mass of alkyl (meth)acrylate as monomer components.

[0026] In the laminate of the present invention, for example, in the adhesive layer, the nitrogen-containing monomer may be a monomer having one or two reactive double bonds per molecule. The monomer having one or two reactive double bonds per molecule may be, for example, a heterocyclic acrylic monomer (heterocyclic acrylate).

[0027] In the laminate of the present invention, the gel fraction of the adhesive forming the adhesive layer may be, for example, 85% by mass or more, or as described above, it may exceed 85% by mass, for example, 90% by mass or more, 91% by mass or more, or 93% by mass or more, for example, 100% by mass or less, 99% by mass or less, or 98% by mass or less.

[0028] In the laminate of the present invention, the initial refractive index of the void layer before the heat durability test (hereinafter sometimes referred to as "initial refractive index") may be less than 1.23, as described above, for example, 1.22 or less, less than 1.22, 1.21 or less, or less than 1.21.

[0029] In the laminate of the present invention, the increase in refractive index of the void layer before and after a heat durability test held at a temperature of 65°C and a relative humidity of 95% for 1000 hours may be, as described above, for example, 0.015 or less, or for example, less than 0.015, 0.01 or less, or less than 0.01. The lower limit of the increase in refractive index is not particularly limited, but may be, for example, 0 or more, or a value greater than 0.

[0030] The laminate of the present invention may, for example, have a porosity of 35 volume% or more in the void layer.

[0031] In the laminate of the present invention, for example, the void layer may be a porous material in which microporous particles are chemically bonded to each other.

[0032] In the laminate of the present invention, the adhesive layer may be a layer formed by a method including, for example, a preparation step of preparing an adhesive coating liquid containing a (meth)acrylic polymer, a coating step of applying the adhesive coating liquid to a substrate, and a heating and drying step of heating and drying the substrate to which the adhesive coating liquid has been applied. In the laminate of the present invention, for example, an adhesive layer may be formed from an adhesive coating liquid having a specific composition and integrated with the void layer. This makes it possible to suppress significant penetration of the adhesive layer into the void layer, for example, especially under long-term heating durability tests. The adhesive coating liquid may further contain, for example, a crosslinking agent, or other components as described later.

[0033] In the laminate of the present invention, the reason (mechanism) for achieving both adhesive strength and resistance to penetration of the adhesive into the voids can be considered as follows, for example. For example, by forming an adhesive layer using a specific adhesive, both adhesive strength and resistance to penetration of the adhesive into the voids can be achieved. More specifically, for example, by forming an adhesive layer using a specific (meth)acrylic polymer as described above and a crosslinking agent as needed, an intermediate layer is formed by the merging of a part of the void layer and a part of the adhesive layer. Furthermore, by using a specific (meth)acrylic polymer as described above, the intermediate layer does not spread excessively even under conditions such as the heat durability test. Moreover, the intermediate layer acts as a stopper, suppressing the reduction in porosity due to the voids in the void layer being filled with adhesive. Even if the molecular motion of the adhesive increases under heating, if the elastic modulus of the adhesive is high, the intermediate layer formed from the adhesive and the high void layer tends to act as a strong and dense stopper, suppressing the penetration of the adhesive into the high void layer. However, these mechanisms are merely illustrative and do not limit the present invention in any way.

[0034] Furthermore, the adhesive coating liquid contains monomers having one or two reactive double bonds per molecule, which allows it to undergo a crosslinking reaction with crosslinking agents such as isocyanate-based crosslinking agents or epoxy-based crosslinking agents upon heating. During this crosslinking reaction, the presence of monomers having one or two reactive double bonds per molecule and organic peroxides, which act as hydrogen abstraction initiators, is thought to enable high-density crosslinking of semi-high molecular weight polymer components with a molecular weight of 10,000 or less contained in the adhesive coating liquid, thereby suppressing the penetration of components from the adhesive coating liquid into the void layer to an even higher level. In other words, semi-high molecular weight polymer components with a molecular weight of 10,000 or less tend to penetrate into the voids of the void layer due to their small molecular size, but the crosslinking reaction increases their molecular size, which is thought to suppress their penetration into the voids of the void layer. Furthermore, it is hypothesized that the presence of monomers having one or two reactive double bonds per molecule during the crosslinking reaction enables graft reactions with the (meth)acrylic polymer backbone and high-density crosslinking starting from the graft chain, thereby reducing the amount of semi-molecular-weight polymer that can become a sol component. However, these mechanisms are illustrative and do not limit the present invention in any way.

[0035] In the adhesive coating liquid for forming an adhesive layer in the laminate of the present invention, the nitrogen-containing monomer preferably has a small number of functional groups (number of reactive double bonds in one molecule) in order to efficiently crosslink the main chains in the graft reaction. For example, as described above, it is preferable that the number of reactive double bonds in one molecule is one or two.

[0036] Furthermore, when manufacturing (meth)acrylic polymers, even if monomers having one or two reactive double bonds are mixed in, it is difficult to reduce the amount of semi-high molecular weight polymers (which have a small molecular weight and easily penetrate into the voids of the void layer) as described above. However, according to the present invention, by using a viscous adhesive coating liquid in which monomers having one or two reactive double bonds are later mixed with (meth)acrylic polymers and then undergoing a crosslinking reaction, for example, the graft reaction described above occurs, and the amount of semi-high molecular weight polymers can be reduced.

[0037] In the present invention, "(meth)acrylic" means at least one of acrylic and methacrylic. For example, "(meth)acrylic acid" means at least one of acrylic acid and methacrylic acid. "(meth)acrylic acid ester" means at least one of acrylic acid ester and methacrylic acid ester. "(meth)methyl acrylate" means at least one of methyl acrylate and methyl methacrylate.

[0038] In the present invention, "(meth)acrylic polymer" refers to a polymer having a structure obtained by polymerizing a component that includes, for example, at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, monomer having an acryloyl group, and monomer having a methacryloyl group. The component may or may not contain substances other than at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, monomer having an acryloyl group, and monomer having a methacryloyl group.

[0039] In the present invention, "acrylic monomer" refers to a monomer that includes at least one selected from the group consisting of, for example, acrylic acid, acrylic acid esters, and monomers having an acryloyl group.

[0040] In the present invention, "isocyanate-based crosslinking agent" refers to a crosslinking agent having an isocyanate group (isocyanato group) in its molecule. In the present invention, the number of isocyanate groups (isocyanato groups) in one molecule of the isocyanate-based crosslinking agent is not particularly limited, but is preferably two or more, for example, it may be two, three or four, and the upper limit is not particularly limited, but is for example 10 or less.

[0041] In the present invention, "epoxy crosslinking agent" refers to, for example, a crosslinking agent having epoxy groups in its molecule. In the present invention, the number of epoxy groups in one molecule of the epoxy crosslinking agent is not particularly limited, but is preferably two or more, for example, two, three or four, and the upper limit is not particularly limited, but is for example 10 or less.

[0042] [1. Laminates, optical components, and optical devices] As described above, the laminate of the present invention comprises a void layer and an adhesive layer, wherein the adhesive layer is directly laminated on one or both sides of the void layer. In the present invention, "directly laminated" of the adhesive layer to the void layer means, for example, that the adhesive layer is in direct contact with the void layer, or that the adhesive layer is laminated to the void layer via the intermediate layer.

[0043] Figure 1(a) shows a cross-sectional view illustrating an example of the configuration of the laminate according to the present invention. As shown, in this laminate 10, the adhesive layer 12 is directly laminated to one side of the void layer 11. Figure 1(b) shows another example of the configuration of the laminate according to the present invention. As shown, in this laminate 10a, the adhesive layer 12 is directly laminated to both sides of the void layer 11.

[0044] Furthermore, as described above, the laminate of the present invention may have an intermediate layer between the void layer and the adhesive layer, and the intermediate layer may be a layer formed by the union of the void layer and the adhesive layer. Figure 2 shows an example of such a laminate of the present invention. As shown in the figure, the laminate 10b in Figure 2(a) has the adhesive layer 12 directly laminated on one side of the void layer 11. This laminate 10b is the same as the laminate 10 in Figure 1(a), except that an intermediate layer 13 exists between the void layer 11 and the adhesive layer 12. The intermediate layer 13 is a layer formed by the union of the void layer 11 and the adhesive layer 12. As shown in the figure, the laminate 10c in Figure 2(b) has the adhesive layer 12 directly laminated on both sides of the void layer 11. This laminate 10c is the same as the laminate 10a in Figure 1(b), except that an intermediate layer 13 exists between the void layer 11 and each adhesive layer 12. The intermediate layer 13 is a layer formed by the fusion of the void layer 11 and the adhesive layer 12, similar to the layer shown in Figure 2(a).

[0045] Furthermore, the laminate of the present invention may or may not include other components other than the void layer, the adhesive layer, and the intermediate layer. The other components are not particularly limited, but may be, for example, a substrate. The substrate is also not particularly limited, but may be, for example, a film (e.g., a resin film), a glass plate, etc., as will be described later. Figure 3 shows an example of such a laminate of the present invention. The laminate 10d in Figure 3(a) is the same as the laminate 10b in Figure 2(a), except that, as shown in the figure, the substrate 14 is provided in direct contact on the surface of the void layer 11 opposite to the adhesive layer 12, and on the surface of the adhesive layer 12 opposite to the void layer 11. The laminate 10e in Figure 3(b) is the same as the laminate 10c in Figure 3(b), except that, as shown in the figure, the substrate 14 is provided in direct contact on the surfaces of the adhesive layers 12 on both sides opposite to the void layer 11. In Figures 3(a) and 3(b), the substrate 14 is provided on both sides of the laminate. However, the present invention is not limited thereto, and for example, the base material 14 may be provided on only one side. Also, in Figures 3(a) and 3(b), the base material 14 is provided so as to be in direct contact with the void layer 11 or the adhesive layer 12. However, the present invention is not limited thereto, and for example, other components may be present between the base material 14 and the void layer 11 or the adhesive layer 12. The other components are not particularly limited, but for example, they may be an optical functional layer. The optical functional layer is also not particularly limited, and for example, it may be an optical functional layer used in general optical films, such as a microlens film, prism film, diffusion film, polarizing reflective film, polarizing film, phase difference film, high refractive index layer, etc.

[0046] The laminate of the present invention may, for example, have a light transmittance of 80% or more for a laminate of the adhesive layer and the void layer, or for a laminate of the adhesive layer, the intermediate layer and the void layer. Also, for example, the haze of the laminate may be 3% or less. The light transmittance may be, for example, 82% or more, 84% or more, 86% or more, or 88% or more, and there is no particular upper limit, but ideally it is 100%, and may be, for example, 95% or less, 92% or less, 91% or less, or 90% or less. The haze of the laminate can be measured, for example, in the same way as the haze of the void layer described later. The light transmittance is the transmittance of light with a wavelength of 550 nm, and can be measured, for example, by the following measurement method.

[0047] (Method for measuring light transmittance) Using a spectrophotometer U-4100 (product name of Hitachi, Ltd.), the laminate is used as the sample to be measured. The total light transmittance (light transmittance) of the sample is then measured, with the total light transmittance of air set to 100%. The value of the total light transmittance (light transmittance) is defined as the measurement taken at a wavelength of 550 nm.

[0048] The laminate of the present invention may have, for example, an adhesive strength or bonding strength of the adhesive layer of the adhesive layer of, for example, 0.7 N / 25 mm or more, 0.8 N / 25 mm or more, 1.0 N / 25 mm or more, or 1.5 N / 25 mm or more, or 50 N / 25 mm or less, 30 N / 25 mm or less, 10 N / 25 mm or less, 5 N / 25 mm or less, or 3 N / 25 mm or less. From the viewpoint of the risk of peeling during handling when the laminate is bonded to other layers, it is preferable that the adhesive strength or bonding strength of the adhesive layer is not too low. Also, from the viewpoint of rework when re-bonding, it is preferable that the adhesive strength or bonding strength of the adhesive layer is not too high. The adhesive strength or bonding strength of the adhesive layer can be measured, for example, as follows.

[0049] (Method for measuring adhesive strength or bonding strength) A sample of the laminated film of the present invention (a laminate of the present invention formed on a resin film substrate) is taken in the form of a 50 mm x 140 mm strip, and the sample is fixed to a stainless steel plate with double-sided tape. An acrylic adhesive layer (20 μm thick) is laminated to a PET film (T100: manufactured by Mitsubishi Plastics Film Co., Ltd.), and a piece of adhesive tape cut to 25 mm x 100 mm is attached to the side of the laminated film of the present invention opposite to the resin film, and the PET film is laminated. Next, the sample is chucked into an Autograph tensile tester (manufactured by Shimadzu Corporation: AG-Xplus) with a chuck distance of 100 mm, and a tensile test is performed at a tensile speed of 0.3 m / min. The average test force obtained from the 50 mm peel test is defined as the adhesive peel strength, i.e., the adhesive force. The bonding force can also be measured using the same measurement method. In the present invention, there is no clear distinction between "adhesion force" and "bonding force".

[0050] The laminate of the present invention may be formed on a substrate such as a film. The film may be, for example, a resin film. Generally, materials with relatively small thickness are called "films" and those with relatively large thickness are called "sheets" to distinguish them, but in the present invention, there is no particular distinction between "films" and "sheets".

[0051] The substrate is not particularly limited, and preferably, but is not limited to, a thermoplastic resin substrate, a glass substrate, an inorganic substrate such as silicon, a plastic molded from a thermosetting resin, a semiconductor or other element, a carbon fiber material such as carbon nanotubes, etc. The form of the substrate may be, for example, a film, a plate, etc. The thermoplastic resin may be, for example, polyethylene terephthalate (PET), acrylic, cellulose acetate propionate (CAP), cycloolefin polymer (COP), triacetylcellulose (TAC), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP), etc.

[0052] The optical component of the present invention is not particularly limited, but may be, for example, an optical film including the laminate of the present invention.

[0053] The optical device of the present invention is not particularly limited, but may be, for example, an image display device or an illumination device. Examples of image display devices include liquid crystal displays, organic EL (Electro Luminescence) displays, and micro-LED (Light Emitting Diode) displays. Examples of illumination devices include organic EL lighting.

[0054] [2.Void layer] The void layer in the laminate of the present invention (hereinafter sometimes referred to as "the void layer of the present invention") will be described below with examples. However, the void layer of the present invention is not limited to these examples.

[0055] The void layer of the present invention may, for example, have a porosity of 35 volume% or more and a peak pore diameter of 50 nm or less. However, this is illustrative, and the void layer of the present invention is not limited thereto.

[0056] The porosity may be, for example, 35 volume% or more, 38 volume% or more, or 40 volume% or more, and may be 90 volume% or less, 80 volume% or less, or 75 volume% or less. The void layer of the present invention may be, for example, a high void layer with a porosity of 60 volume% or more.

[0057] The aforementioned porosity can be measured, for example, by the following measurement method.

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

[0059] The void layer of the present invention can be manufactured, for example, by chemical bonding of gel pulverized material (microporous particles), as described later. In this case, for convenience, the voids in the void layer can be divided into three types as follows: (1) to (3). (1) The voids present in the raw material gel itself (within the particles) (2) The voids in the gel pulverized material units (3) Voids between the pulverized material caused by the accumulation of the pulverized gel

[0060] The voids in (2) above are voids formed during grinding, separate from those in (1), that can be formed within each block when each group of particles generated by grinding the gel is considered as a single block, regardless of the size, dimensions, etc., of the gel pulverized material (microporous particles). Furthermore, the voids in (3) above are voids that occur during grinding (e.g., medialess grinding) due to the uneven size, dimensions, etc., of the gel pulverized material (microporous particles). The void layer of the present invention has, for example, voids in (1) to (3) above, thereby having an appropriate porosity and peak pore diameter.

[0061] Furthermore, the peak pore diameter may be, for example, 5 nm or more, 10 nm or more, or 20 nm or more, or 50 nm or less, 40 nm or less, or 30 nm or less. In the void layer, if the peak pore diameter is too large when the porosity is high, light is scattered and the layer becomes opaque. Also, in the present invention, the lower limit of the peak pore diameter of the void layer is not particularly limited, but if the peak pore diameter is too small, it becomes difficult to increase the porosity, so it is preferable that the peak pore diameter is not too small. In the present invention, the peak pore diameter can be measured, for example, by the following method.

[0062] (Method for measuring peak pore size) Using a pore distribution / specific surface area analyzer (BELLSORP MINI / product name of Microtrac Bell), the peak pore diameter is calculated from the results obtained by calculating BJH plots and BET plots due to nitrogen adsorption, as well as isothermal adsorption curves.

[0063] Furthermore, the thickness of the void layer of the present invention is not particularly limited, but may be, for example, 100 nm or more, 200 nm or more, or 300 nm or more, or it may be 10,000 nm or less, 5,000 nm or less, or 2,000 nm or less.

[0064] In the present invention, the void layer is formed by using pulverized porous gel, for example, as described later, which destroys the three-dimensional structure of the porous gel and creates a new three-dimensional structure different from that of the porous gel. Thus, the void layer of the present invention has a new pore structure (new void structure) that cannot be obtained from a layer formed from the porous gel, making it possible to form a nanoscale void layer with a high porosity. Furthermore, in the present invention, for example, if the void layer is a silicone porous material, the pulverized materials are chemically bonded together while adjusting, for example, the number of siloxane bond functional groups in the silicon compound gel. Here, "silicone porous material" refers to a polymer porous material containing siloxane bonds, and includes, for example, a porous material containing silsesquioxane as a constituent unit. In addition, since a new three-dimensional structure is formed as a precursor to the void layer and then chemically bonded (e.g., crosslinked) in the bonding process, the void layer of the present invention, for example, if the void layer is a functional porous material, has a void structure but can maintain sufficient strength and flexibility. Therefore, according to the present invention, a void layer can be easily and simply applied to various objects.

[0065] The void layer of the present invention, for example, contains pulverized porous gel, as described later, and the pulverized material is chemically bonded to itself. In the void layer of the present invention, the form of the chemical bond between the pulverized material is not particularly limited, and specific examples of the chemical bond include, for example, cross-linking. The method for chemically bonding the pulverized material is as described in detail in the method for manufacturing the void layer described above.

[0066] The aforementioned crosslinking bond is, for example, a siloxane bond. Examples of siloxane bonds include the T2 bond, T3 bond, and T4 bond shown below. When the porous silicone material of the present invention has siloxane bonds, 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 material becomes and the more the gel's inherent properties can be expected, but the film strength becomes weaker. On the other hand, if the ratio of T4 among the siloxane bonds is high, film strength is easily achieved, but the void size becomes smaller and the flexibility becomes brittle. For this reason, it is preferable to change the ratio of T2, T3, and T4 depending on the application, for example.

[0067] [ka]

[0068] When the void layer of the present invention has the siloxane bond, the ratios of T2, T3, and T4 are, for example, expressed relatively with T2 as "1", T2:T3:T4 = 1:[1~100]:[0~50], 1:[1~80]:[1~40], and 1:[5~60]:[1~30].

[0069] Furthermore, it is preferable that the void layer of the present invention contains silicon atoms bonded together by siloxane bonds. Specifically, the proportion of unbonded silicon atoms (i.e., residual silanols) among the total silicon atoms contained in the porous silicone material is, for example, less than 50%, 30% or less, or 15% or less.

[0070] The void layer of the present invention has, for example, a pore structure. In the present invention, the void size of the pore refers to the diameter of the major axis of the void (pore) among the diameter of the major axis and the diameter of the minor axis. The void size is, for example, 5 nm to 50 nm. The lower limit of the void size is, for example, 5 nm or more, 10 nm or more, or 20 nm or more, and the upper limit is, for example, 50 nm or less, 40 nm or less, or 30 nm or less, and the range is, for example, 5 nm to 50 nm or 10 nm to 40 nm. The preferred void size is determined according to the application in which the void structure is used, so for example, it is necessary to adjust it to the desired void size according to the purpose. The void size can be evaluated by, for example, the following method.

[0071] (Cross-sectional SEM observation of the void layer) In this invention, the morphology of the void layer can be observed and analyzed using a scanning electron microscope (SEM). Specifically, for example, the void layer can be processed using FIB under cooling (acceleration voltage: 30kV), and a cross-sectional electron image can be obtained from the resulting cross-sectional sample using a FIB-SEM (FEI Corporation: product name Helios NanoLab600, acceleration voltage: 1kV) at an observation magnification of 100,000x.

[0072] (Evaluation of void size) In the present invention, the void size can be quantified by the BET test method. Specifically, 0.1 g of the sample (void layer of the present invention) is placed in the capillary of a pore distribution / specific surface area measuring device (BELLSORP MINI / product name of Microtrac Bell), and then dried under reduced pressure at room temperature for 24 hours to degas the gas within the void structure. Then, nitrogen gas is adsorbed onto the sample to create BET plots, BJH plots, and adsorption isotherms, and the pore distribution is determined. This allows the void size to be evaluated.

[0073] The void layer of the present invention may, for example, have a porous structure as described above, or it may be a continuous cell structure in which the porous structure is continuous. The continuous cell structure means, for example, that the porous structure is connected three-dimensionally in the void layer, and can also be said to be a state in which the internal voids of the porous structure are continuous. When a porous body has a continuous cell structure, it is possible to increase the porosity in the bulk, but when using closed-cell particles such as hollow silica, a continuous cell structure cannot be formed. In contrast, the void layer of the present invention has a three-dimensional dendritic structure in the sol particles (pulverized porous gel that forms the sol), so the dendritic particles settle and accumulate in the coating film (a coating film of sol containing the pulverized porous gel), making it possible to easily form a continuous cell structure. Furthermore, it is preferable that the void layer of the present invention forms a monolithic structure in which the continuous cell structure has a plurality of pore distributions. The monolithic structure refers to, for example, a hierarchical structure in which a structure with nano-sized fine voids exists and a continuous cell structure in which these nano-voids are aggregated. When forming the aforementioned monolithic structure, for example, it is possible to achieve both film strength and high porosity by providing fine voids while simultaneously providing high porosity with coarse interconnected voids. To form such monolithic structures, for example, it is important to first control the pore distribution of the void structure generated in the porous gel before it is ground into the pulverized material. Furthermore, for example, when grinding the porous gel, the monolithic structure can be formed by controlling the particle size distribution of the pulverized material to a desired size.

[0074] In the void layer of the present invention, the haze exhibiting transparency is not particularly limited, with a lower limit of, for example, 0.1% or more, 0.2% or more, or 0.3% or more, and an upper limit of, for example, 10% or less, 5% or less, or 3% or less, and a range of, for example, 0.1 to 10%, 0.2 to 5%, or 0.3 to 3%.

[0075] The aforementioned haze can be measured, for example, by the following method.

[0076] (Hayes's evaluation) The void layer (the void layer of the present invention) is cut to a size of 50 mm x 50 mm and set in a haze meter (HM-150, manufactured by Murakami Color Technology Research Institute Co., Ltd.) to measure the haze. The haze value is calculated using the following formula. Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] × 100 (%)

[0077] 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. The refractive index of the void layer of the present invention is not particularly limited, and its upper limit is, for example, 1.3 or less, less than 1.3, 1.25 or less, 1.2 or less, and 1.15 or less, and its lower limit is, for example, 1.05 or more, 1.06 or more, and 1.07 or more, and its range is, for example, 1.05 or more and 1.3 or less, 1.05 or more and less than 1.3, 1.05 or more and 1.25 or less, 1.06 or more and less than 1.2, and 1.07 or more and 1.15 or less.

[0078] In this invention, unless otherwise specified, the refractive index refers to the refractive index measured at a wavelength of 550 nm. Furthermore, the method for measuring the refractive index is not particularly limited and can be measured, for example, by the following method.

[0079] (Evaluation of refractive index) A laminated sample is prepared by bonding an adhesive to a void layer. A prism from a prism coupler (manufactured by Merritricon) is placed in close contact with the substrate side of the sample, and the critical angle of total internal reflection is measured using a laser. The refractive index is calculated from the value of that critical angle.

[0080] The thickness of the void layer in the present invention is not particularly limited, with a lower limit of, for example, 0.05 μm or more and 0.1 μm or more, and an upper limit of, for example, 1000 μm or less and 100 μm or less, and a range of, for example, 0.05 to 1000 μm and 0.1 to 100 μm.

[0081] The form of the void layer in the present invention is not particularly limited and may be, for example, a film shape or a block shape.

[0082] The method for producing the void layer of the present invention is not particularly limited, but it can be produced, for example, by the method described in International Publication No. 2019 / 065999 and International Publication No. 2019 / 065803. The descriptions in said publications are incorporated herein by reference.

[0083] [3. Adhesive coating liquid] In the laminate of the present invention, the adhesive layer can be formed, for example, using an adhesive coating liquid as described above. In the present invention, "tack" and "adhesive" are not necessarily clearly distinguishable, as will be described later. In the present invention, when referring to "adhesive," unless otherwise specified, it includes both "tack" and "adhesive." The adhesive coating liquid may be, for example, an adhesive coating liquid containing the (meth)acrylic polymer, or, for example, an adhesive coating liquid containing the oligomer-type silane coupling agent, or, for example, an adhesive coating liquid further containing a crosslinking agent (e.g., an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent), or, for example, a monomer having one or two reactive double bonds in one molecule and an organic peroxide. The adhesive coating liquid is not particularly limited, but examples are given below.

[0084] The adhesive coating liquid may be, for example, a (meth)acrylic polymer in which the (meth)acrylic polymer contains, for example, 3 to 20% by mass of a heterocyclic acrylic monomer, 0.5 to 5% by mass of (meth)acrylic acid having polymerizable functional groups, 0.05 to 2% by mass of hydroxyalkyl (meth)acrylate, and 83 to 96.45% by mass of alkyl (meth)acrylate as monomer components, and this (meth)acrylic polymer may be used as the base polymer.

[0085] As heterocyclic acrylic monomers, those having polymerizable functional groups and heterocyclic rings can be used without particular limitation. Examples of polymerizable functional groups include (meth)acryloyl groups and vinyl ether groups. Among these, (meth)acryloyl groups are preferred. Examples of heterocyclic rings include morpholine rings, piperidine rings, pyrrolidine rings, and piperazine rings. Examples of heterocyclic acrylic monomers include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. Among these, N-acryloylmorpholine is preferred. Heterocyclic acrylic monomers can improve the heat resistance and moisture resistance durability when the adhesive layer (adhesive layer) is made thinner. In the following, N-acryloylmorpholine may be referred to as "ACMO".

[0086] Furthermore, heterocyclic acrylic monomers are preferred because they can improve the adhesion of the adhesive layer (adhesive layer) to the optical film. They are particularly preferred because they improve adhesion to cyclic polyolefins such as norbornene-based resins, and are suitable when cyclic polyolefins are used as the optical film.

[0087] The heterocyclic acrylic monomer is used, for example, in a proportion of 3 to 20% by mass relative to the total amount of monomer components forming the (meth)acrylic polymer. The proportion of heterocyclic acrylic monomer may be, for example, 4 to 19% by mass or 6 to 18% by mass. From the viewpoint of heat resistance and moisture resistance when the adhesive layer is thinned, it is preferable that the proportion of heterocyclic acrylic monomer is not less than the above range. Furthermore, from the viewpoint of moisture resistance when the layer is thinned, it is preferable that the proportion of heterocyclic acrylic monomer is not more than the above range. Furthermore, from the viewpoint of improving the bonding properties of the adhesive layer, it is preferable that the proportion of heterocyclic acrylic monomer is not more than the above range. Furthermore, from the viewpoint of adhesive strength, it is preferable that the proportion of heterocyclic acrylic monomer is not more than the above range.

[0088] Acrylic acid is particularly preferred as the (meth)acrylic acid.

[0089] (Meth)acrylic acid is used, for example, in a proportion of 0.5 to 5% by mass relative to the total amount of monomer components forming the (meth)acrylic polymer. The proportion of (meth)acrylic acid may be, for example, 1 to 4.5% by mass or 1.5 to 4% by mass. From the viewpoint of heat resistance when the adhesive layer (adhesive layer) is thinned, it is preferable that the proportion of (meth)acrylic acid is not less than the above range. Furthermore, from the viewpoint of heat resistance and moisture resistance when the layer is thinned, it is preferable that the proportion of (meth)acrylic acid is not more than the above range. Furthermore, from the viewpoint of adhesive strength, it is preferable that the proportion of (meth)acrylic acid is not more than the above range.

[0090] As hydroxyalkyl (meth)acrylates, for example, those having polymerizable functional groups and hydroxyl groups can be used without particular limitation. Suitable hydroxyalkyl (meth)acrylates include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate.

[0091] Hydroxyalkyl (meth)acrylate is used, for example, in a proportion of 0.05 to 2% by mass relative to the total amount of monomer components forming the (meth)acrylic polymer. The proportion of hydroxyalkyl (meth)acrylate may be, for example, 0.075 to 1.5% by mass or 0.1 to 1% by mass. From the viewpoint of heat resistance when the adhesive layer (adhesive layer) is thinned, it is preferable that the proportion of hydroxyalkyl (meth)acrylate is not less than the above range. Furthermore, from the viewpoint of heat resistance and moisture resistance when the layer is thinned, it is preferable that the proportion of hydroxyalkyl (meth)acrylate is not more than the above range. Furthermore, from the viewpoint of adhesive strength, it is preferable that the proportion of hydroxyalkyl (meth)acrylate is not more than the above range.

[0092] As for the alkyl(meth)acrylate, for example, the average number of carbon atoms in the alkyl group of the alkyl(meth)acrylate may be about 1 to 12. Note that (meth)acrylate refers to acrylate and / or methacrylate, and the (meth) in this invention has the same meaning. Specific examples of alkyl(meth)acrylates include methyl(meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, isooctyl(meth)acrylate, isononyl(meth)acrylate, lauryl(meth)acrylate, etc., and these can be used alone or in combination. Among these, alkyl(meth)acrylates with 1 to 9 carbon atoms in the alkyl group are preferred.

[0093] Alkyl (meth)acrylates are used, for example, in a proportion of 83 to 96.45% by mass relative to the total amount of monomer components forming the (meth)acrylic polymer. Alkyl (meth)acrylates are typically the remainder of the mixture other than the heterocyclic acrylic monomer, (meth)acrylic acid, and hydroxyalkyl (meth)acrylate.

[0094] As monomer components forming the (meth)acrylic polymer, for example, in addition to the monomers mentioned above, any other monomers can be used in an amount of 10% or less of the total amount of monomers, as long as they do not impair the objectives of the present invention.

[0095] Examples of the aforementioned optional monomers include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acrylamidepropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate. Nitrogen-containing vinyl monomers are also mentioned. For example, maleimide, N-cyclohexylmaleimide, N-phenylmaleimide; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylolpropane(meth)acrylamide, and other (N-substituted)amide monomers; aminoethyl(meth)acrylate, aminopropyl(meth)acrylate, N,N(meth)acrylate Examples include alkylaminoalkyl monomers of (meth)acrylate such as dimethylaminoethyl (meth)acrylate, t-butylaminoethyl (meth)acrylate, and 3-(3-pyridyl)propyl (meth)acrylate; alkoxyalkyl monomers of (meth)acrylate such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; and succinimide monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide.

[0096] Furthermore, vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinyl carboxylic acid amides, styrene, α-methylstyrene, and N-vinylcaprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; and acrylic acid ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate can also be used.

[0097] Furthermore, other copolymerizable monomers besides those mentioned above include silane monomers containing silicon atoms. Examples of silane monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

[0098] As described above, the (meth)acrylic polymer used in the adhesive layer of the laminate of the present invention may have a weight-average molecular weight (Mw) of, for example, 1.5 million to 4 million. The weight-average molecular weight may also be, for example, 1.8 million to 3.8 million, or 2 million to 3.5 million or 2.2 million to 3.3 million. From the viewpoint of heat resistance and moisture resistance when the adhesive layer is thinned, it is preferable that the weight-average molecular weight is not smaller than the above range. Furthermore, from the viewpoint of durability when thinned, and of bonding properties and adhesive strength, it is preferable that the weight-average molecular weight is not larger than the above range. In the present invention, the weight-average molecular weight refers to a value calculated on a polystyrene basis, for example, by GPC (gel permeation chromatography).

[0099] The method for producing such (meth)acrylic polymers is not particularly limited, and known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations can be appropriately selected. Furthermore, the resulting (meth)acrylic polymer may be a random copolymer, block copolymer, graft copolymer, or any other type.

[0100] In solution polymerization, for example, ethyl acetate and toluene are used as polymerization solvents. A specific example of solution polymerization involves adding a polymerization initiator under a stream of an inert gas such as nitrogen, and carrying out the reaction under conditions of approximately 50-70°C for 1-30 hours.

[0101] The polymerization initiators, chain transfer agents, and emulsifiers used in radical polymerization are not particularly limited and can be selected and used as appropriate. The weight-average molecular weight of the (meth)acrylic polymer can be controlled by the amount of polymerization initiator and chain transfer agent used and the reaction conditions, and the amount used is adjusted as appropriate depending on the type of agent.

[0102] Examples of polymerization initiators include azo-based initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (manufactured by Wako Pure Chemical Industries, Ltd., VA-057), as well as persulfates such as potassium persulfate and ammonium persulfate, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, and di-sec-butylperoxy Examples of peroxide initiators include, but are not limited to, dicarbonates, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, di(4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butyl peroxyisobutyrate, 1,1-di(t-hexyl peroxy)cyclohexane, t-butyl hydroperoxide, and hydrogen peroxide; as well as redox initiators combining peroxides with reducing agents, such as combinations of persulfates and sodium bisulfite, and combinations of peroxides and sodium ascorbate.

[0103] The polymerization initiator may be used alone or in a mixture of two or more. The total content of the polymerization initiator may be, for example, about 0.005 to 1 part by mass or about 0.02 to 0.5 parts by mass per 100 parts by mass of monomer.

[0104] Furthermore, when producing the (meth)acrylic polymer of the aforementioned weight-average molecular weight using, for example, 2,2'-azobisisobutyronitrile as a polymerization initiator, the amount of polymerization initiator used may be, for example, about 0.06 to 0.2 parts by mass or about 0.08 to 0.175 parts by mass per 100 parts by mass of the total amount of monomer components.

[0105] Examples of chain transfer agents include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agents may be used individually or in combination of two or more. The total content of the chain transfer agents is, for example, about 0.1 parts by mass or less per 100 parts by mass of the total amount of monomer components.

[0106] Furthermore, examples of emulsifiers used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, ammonium polyoxyethylene alkyl ether sulfate, and sodium polyoxyethylene alkylphenyl ether sulfate, and nonionic emulsifiers such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene-polyoxypropylene block polymers. These emulsifiers may be used individually or in combination of two or more.

[0107] Furthermore, as reactive emulsifiers, those incorporating radical polymerizable functional groups such as propenyl groups and allyl ether groups include, specifically, Aqualon HS-10, HS-20, KH-10, BC-05, BC-10, BC-20 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and Adekarya Soap SE10N (manufactured by Asahi Denka Kogyo Co., Ltd.). Reactive emulsifiers are incorporated into the polymer chain after polymerization, which improves water resistance and is therefore preferable. The amount of emulsifier used is 0.3 to 5 parts by mass, more preferably 0.5 to 1 part by mass, per 100 parts by mass of the total amount of monomer components, due to polymerization stability and mechanical stability.

[0108] The content of the (meth)acrylic polymer in the adhesive coating liquid is not particularly limited, but may be, for example, 3% by mass or more, or 5% by mass or more, based on the total mass of the adhesive coating liquid, or may be, for example, 30% by mass or less, 20% by mass or less, or 10% by mass or less.

[0109] Furthermore, the adhesive coating liquid may or may not contain, for example, a monomer having one or two reactive double bonds per molecule. The monomer having one or two reactive double bonds per molecule is not particularly limited, but from the viewpoint of the reaction rate of the graft reaction, acrylic monomers, vinyl monomers, methacrylic monomers, and allyl monomers are preferred, and acrylic monomers are more preferred. The acrylic monomer is not particularly limited, but for example, it may be the same as the monomer exemplified as the monomer component of the acrylic polymer. In the monomer having one or two reactive double bonds per molecule, the structure of the side chain is not particularly limited, but heterocyclic monomers are preferred because they can simultaneously achieve high elastic modulus within an appropriate range and a reduction in the amount of semipolymer.

[0110] If the adhesive coating liquid contains monomers having one or two reactive double bonds in one molecule, the content thereof is not particularly limited, but may be, for example, 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, relative to the total mass of the (meth)acrylic polymer in the adhesive coating liquid, or for example, 30% by mass or less, 20% by mass or less, or 10% by mass or less.

[0111] The weight-average molecular weight (Mw) of the oligomer-type silane coupling agent may be 300 or more, as described above. The laminate of the present invention, by including the oligomer-type silane coupling agent in the adhesive coating liquid, can improve the durability of the adhesive layer formed from the adhesive coating liquid, and in particular, it has excellent durability in humid environments and can maintain high durability even after being left for a long period of time. Here, in the present invention, the adhesive coating liquid may be, for example, an adhesive (adhesive composition). The adhesive layer may be, for example, an adhesive layer formed from an adhesive (adhesive composition). Here, "oligomer-type" refers to a polymer of monomers of about 2 or more (degree of polymerization) or less than 100 (degree of polymerization), and the weight-average molecular weight of the oligomer-type silane coupling agent is preferably about 300 to 30000. In the present invention, the degree of polymerization of the oligomer-type silane coupling agent is not particularly limited.

[0112] The oligomeric silane coupling agent may be, for example, a silane coupling agent having two or more alkoxysilyl groups in its molecule. Specifically, examples include X-41-1053, X-41-1059A, and X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd. These coupling agents are preferred because they are less volatile and have multiple alkoxysilyl groups, which is effective in improving durability.

[0113] The number of alkoxysilyl groups in the oligomeric silane coupling agent is not particularly limited, but it is preferable to have two or more in the molecule. Furthermore, the amount of alkoxy groups in the oligomeric silane coupling agent is preferably, for example, 10 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 20 to 40% by mass. The type of alkoxy group is not limited, but examples include alkoxy groups having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, butoxy, pentyloxy, and hexyloxy. Among these, methoxy and ethoxy are preferred, and methoxy is more preferred. It is also preferable to contain both methoxy and ethoxy in one molecule.

[0114] As mentioned above, the oligomeric silane coupling agent may contain epoxy groups. The epoxy equivalent of the oligomeric silane coupling agent is preferably 1000 g / mol or less, more preferably 500 g / mol or less, and even more preferably 300 g / mol or less. The lower limit of the epoxy equivalent is not particularly limited, but is preferably 200 g / mol or more.

[0115] The oligomer-type silane coupling agent preferably contains epoxy groups, but may also contain acid anhydride groups. By using an oligomer-type silane coupling agent containing acid anhydride groups, the change in refractive index after the heat durability test can be reduced compared to when no silane coupling agent is used, and the adhesion between the adhesive layer and the low refractive index layer after the heat durability test can be improved.

[0116] The oligomeric silane coupling agent may be used alone or in a mixture of two or more types. The total content of the oligomeric silane coupling agent is, as described above, 1 part by mass or less per 100 parts by mass of the (meth)acrylic polymer, but preferably, for example, 0.2 parts by mass or less. By keeping the content within the above range, the increase in the initial refractive index can be suppressed, and the change in refractive index after the heat endurance test can be reduced.

[0117] Furthermore, the adhesive coating liquid (e.g., adhesive composition) used in the present invention may also contain silane coupling agents other than the oligomer-type silane coupling agent. Examples of other coupling agents include amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatetopropyltriethoxysilane.

[0118] Silane coupling agents other than the oligomer-type silane coupling agent mentioned above can be added insofar as they do not impair the effects of the present invention, and the amount added is not particularly limited.

[0119] Furthermore, the adhesive coating liquid may contain, for example, a crosslinking agent as described above. The crosslinking agent is not particularly limited, but examples include isocyanate-based crosslinking agents and epoxy-based crosslinking agents. The isocyanate-based crosslinking agent is not particularly limited, but examples include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate. The epoxy crosslinking agent is not particularly limited, but examples include bisphenol A-epichlorohydrin type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl erythritol, diglycerol polyglycidyl ether, 1,3′-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N′,N′-tetraglycidyl-m-xylenediamine.

[0120] More specifically, the isocyanate-based crosslinking agents include, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate, and trimethylolpropane / tolylene diisocyanate trimer adducts (Japanese Examples include isocyanate adducts such as Coronate L (manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., product name Coronate HL), and isocyanurate derivative of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., product name Coronate HX), as well as polyether polyisocyanates, polyester polyisocyanates, and adducts of these with various polyols, and polyfunctionalized polyisocyanates with isocyanurate bonds, biuret bonds, allophanate bonds, etc.

[0121] More specifically, examples of the epoxy crosslinking agents include "Tetrad C" and "Tetrad X" manufactured by Mitsubishi Gas Chemical Company, and "S-610" manufactured by Synasia.

[0122] The crosslinking agents (e.g., isocyanate-based crosslinking agents, epoxy-based crosslinking agents) may be used alone or in mixtures of two or more types. The total content may be, for example, 0.02 to 2 parts by mass, 0.04 to 1.5 parts by mass, or 0.05 to 1 part by mass of the crosslinking agent per 100 parts by mass of the (meth)acrylic polymer. The content of the isocyanate-based crosslinking agent is preferably 0.02 parts by mass or more from the viewpoint of cohesive force, while it is preferably 2 parts by mass or less from the viewpoint of suppressing or preventing a decrease in adhesive strength due to excessive crosslinking. The content of the epoxy-based crosslinking agent is preferably 0.01 parts by mass or more from the viewpoint of void retention rate, while it is preferably 0.5 parts by mass or less from the viewpoint of peel durability.

[0123] In the aforementioned adhesive coating liquid, the crosslinking agent may consist solely of, for example, an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent, or it may contain or not contain other crosslinking agents other than isocyanate-based crosslinking agents or epoxy-based crosslinking agents. Examples of other crosslinking agents include organic crosslinking agents and polyfunctional metal chelates. Examples of organic crosslinking agents include epoxy-based crosslinking agents and imine-based crosslinking agents. As organic crosslinking agents, isocyanate-based crosslinking agents and epoxy-based crosslinking agents are preferred. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, etc. Examples of atoms in organic compounds that form covalent or coordinate bonds include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

[0124] Furthermore, the adhesive coating liquid may or may not contain, for example, an organic peroxide. The organic peroxide is not particularly limited, but examples include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di(t-hexylperoxy)cyclohexane, t-butylhydroperoxide, etc., and one type may be used or multiple types may be used in combination.

[0125] If the adhesive coating liquid contains the organic peroxide, its content is not particularly limited, but may be, for example, 0.02% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, or 2.5% by mass or more, relative to the total mass of the (meth)acrylic polymer in the adhesive coating liquid, or for example, 20% by mass or less, 10% by mass or less, 8% by mass or less, or 6% by mass or less.

[0126] The adhesive coating liquid may further contain a solvent, etc. The solvent is not particularly limited, but for example, the polymerization solvent used in the solution polymerization in the production of the (meth)acrylic polymer may be used as is.

[0127] Furthermore, the adhesive coating liquid may optionally contain tackifiers, plasticizers, fillers consisting of glass fibers, glass beads, metal powders, and other inorganic powders, as well as pigments, colorants, antioxidants, UV absorbers, silane coupling agents, and various other additives as appropriate, without departing from the objectives of the present invention. It may also be an adhesive layer (adhesive layer) containing fine particles that exhibits light diffusion properties.

[0128] Using the adhesive coating liquid, the adhesive layer in the laminate of the present invention can be formed, for example, by the method described later. The adhesive layer may have a weight-average molecular weight of 30,000 to 600,000 in the sol portion of the adhesive layer, as measured by, for example, gel permeation chromatography. Alternatively, as measured by gel permeation chromatography, the content of low molecular weight components with a molecular weight of 10,000 or less in the sol portion of the adhesive layer may be 20% by weight (mass%) or less. By setting the weight-average molecular weight of the sol portion or the content of low molecular weight components with a molecular weight of 10,000 or less in the sol portion to the specified range, the adhesive becomes less likely to penetrate into the voids of the void layer. The weight-average molecular weight of the sol portion may be, for example, 50,000 or more, for example, 550,000 or less or 500,000 or less, for example, 50,000 to 550,000 or 60,000 to 500,000. Furthermore, the content (percentage) of components with a molecular weight of 10,000 or less in the sol may be, for example, 20% by mass or less as described above, or 15% by mass or 10% by mass or less, relative to the total amount of the sol (100% by mass). The lower limit of the content (percentage) of components with a molecular weight of 10,000 or less in the sol is not particularly limited, but may be, for example, 0% by mass or more or a value greater than 0% by mass, or for example, 3% by mass or more. The content (percentage) of components with a molecular weight of 10,000 or less in the sol may be, for example, 3 to 15% by mass or 3 to 10% by mass.

[0129] [4. Method for manufacturing laminates] The method for manufacturing the laminate of the present invention is not particularly limited, but can be carried out by, for example, the manufacturing method described below. However, the following description is illustrative and does not limit the present invention in any way. The void layer of the present invention is not particularly limited, but can be as described above, for example. The method for manufacturing the void layer of the present invention is also not particularly limited, as described above, and can be manufactured by, for example, the method described in International Publication No. 2019 / 065999 and International Publication No. 2019 / 065803.

[0130] The method for manufacturing the laminate of the present invention may include, for example, an adhesive layer manufacturing step for manufacturing the adhesive layer, and a bonding step for bonding the adhesive layer to the void layer. The method for manufacturing the adhesive layer may include, for example, an adhesive coating step for applying the adhesive coating liquid to a substrate, and a heating and drying step for heating and drying the substrate to which the adhesive coating liquid has been applied. For example, the adhesive layer may be formed on the void layer of the present invention by bonding the adhesive layer side of an adhesive tape or the like, on which the adhesive layer of the present invention is laminated on a substrate, onto the void layer of the present invention. In this case, the substrate such as the adhesive tape may be left bonded as is, or it may be peeled off from the adhesive layer. In particular, by peeling off the substrate to make a void layer-containing adhesive sheet without a substrate (substrate-less), the thickness can be significantly reduced, and the increase in thickness of devices, etc., can be suppressed. In the present invention, "adhesive" and "adhesive layer" refer to, for example, an agent or layer that is intended to allow the adherend to be re-peeled off. In the present invention, "adhesive" and "adhesive layer" refer to, for example, an agent or layer that does not assume the adhesion of the adherend to be re-peeled off. However, in the present invention, "adhesive" and "tack agent" are not necessarily clearly distinguishable, and "tack layer" and "adhesive layer" are not necessarily clearly distinguishable. In the present invention, the tack-adhesive layer can be manufactured, for example, using the tack-adhesive coating liquid as described above.

[0131] The adhesive layer manufacturing process can be carried out, for example, as follows. First, the adhesive coating liquid is manufactured by a mixing step in which all the components of the adhesive coating liquid are mixed. The adhesive coating liquid may, for example, contain the (meth)acrylic polymer as described above, and may also contain, for example, a crosslinking agent (e.g., an isocyanate crosslinking agent, an epoxy crosslinking agent). The adhesive coating liquid may contain, for example, the (meth)acrylic polymer, a monomer having one or two reactive double bonds in one molecule, and an organic peroxide. In this case, if the adhesive coating liquid contains other components, these other components may also be mixed together. For example, the polymerization solvent used during the production of the (meth)acrylic polymer may be mixed as is as a component of the adhesive coating liquid without being removed. Furthermore, the method for manufacturing the adhesive coating liquid may include other steps besides the mixing step, but may not include them, and may simply involve mixing all the components of the adhesive coating liquid by the mixing step.

[0132] Next, the adhesive coating liquid is applied to the substrate (adhesive coating liquid application step). The substrate is not particularly limited and may be, for example, a film. The substrate can preferably be, but is not limited to, a thermoplastic resin substrate, a glass substrate, an inorganic substrate represented by silicon, a plastic molded from a thermosetting resin, a semiconductor or other element, or a carbon fiber material represented by carbon nanotubes. The form of the substrate can be, for example, a film or a plate. Examples of thermoplastic resins include polyethylene terephthalate (PET), acrylic, cellulose acetate propionate (CAP), cycloolefin polymer (COP), triacetylcellulose (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, but can be appropriately adjusted, for example, so that the thickness of the adhesive layer after drying is a predetermined thickness. The thickness of the adhesive layer after drying is also not particularly limited, but can be, for example, as described below.

[0133] Next, the substrate to which the adhesive coating liquid has been applied is heated and dried (heat drying step). In this heat drying step, the heating 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, or for example, 200°C or lower, 180°C or lower, or 160°C or lower. The heating and 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, or 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. As a result, for example, as described above, the amount of semi-polymer present in the adhesive coating liquid decreases, and the adhesive layer becomes less likely to penetrate into the voids of the void layer. In this way, the adhesive layer used in the laminate of the present invention can be manufactured.

[0134] Next, the adhesive layer is bonded to the void layer (bonding step). This method is not particularly limited, but for example, as described above, the adhesive layer side of an adhesive tape or the like, in which the adhesive layer of the present invention is laminated on a substrate, may be bonded to the void layer of the present invention, thereby forming the adhesive layer on the void layer of the present invention. In this way, the laminate of the present invention can be manufactured.

[0135] In the method for manufacturing the laminate of the present invention, for example, a heating step may be performed after the bonding step to heat the adhesive layer and the void layer. Hereinafter, this heating step may be referred to as the "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, or 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 more, 10 minutes or more, 60 minutes or more, or 1800 minutes or more, or for example, 3000 minutes or less, 2800 minutes or less, 2500 minutes or less, or 2000 minutes or less. In this aging step, for example, the intermediate layer is formed by the coalescence of the void layer and the adhesive layer. As described above, for example, the intermediate layer acts as a stopper, suppressing the reduction in porosity due to the voids in the void layer being filled with adhesive. Furthermore, the union 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, or the adhesive layer is embedded in the voids of the void layer.

[0136] The adhesive layer can protect the void layer from physical damage (especially scratches). Furthermore, the adhesive layer, even as a void layer-containing adhesive sheet without a substrate (substrate-less), is preferably made of a material with excellent pressure resistance to prevent the void layer from collapsing, but is not particularly limited. The thickness of the adhesive layer is also 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.

[0137] The laminate obtained in this manner may, for example, be further laminated with other films (layers) as described above to form a laminated structure including the void layer (porous structure). In this case, in the laminated structure, each component may be laminated via, for example, the adhesive layer (tack or adhesive).

[0138] The lamination of the aforementioned components may be carried out by, for example, a continuous process using a long film (so-called Roll to Roll, etc.) for efficiency, or, if the substrate is a molded product or element, it may be laminated after batch processing.

[0139] The following describes a method for forming the laminate of the present invention on a substrate (resin film), with respect to the continuous processing step, using the laminate 10d in Figure 3(a) as an example. Note that the film formation methods described below are merely examples and are not limited to these.

[0140] The substrate may be the resin film described above. In this case, the void layer of the present invention can be obtained by forming the void layer on the substrate. Alternatively, the void layer of the present invention can also be obtained by forming the void layer on the substrate and then laminating the void layer onto the resin film described above in the explanation of the void layer of the present invention.

[0141] The manufacturing method for the laminate 10d in Figure 3(a) is, for example, to first form a void layer 11 on a substrate 14, then form an adhesive layer 12 on the void layer 11, and then form an intermediate layer 13 by the fusion of the void layer 11 and the adhesive layer 12. More specifically, this manufacturing method includes, for example, a coating step (1) to form a coating film by coating a sol particle liquid of pulverized gel-like compound onto a substrate (resin film) 14, a drying step (2) to dry the sol particle liquid and form a dried coating film, a chemical treatment step (e.g., a crosslinking step) (3) to form a void layer 11 by chemically treating the coating film (e.g., a crosslinking step), a bonding step (4) to bond the adhesive layer 12 onto the void layer 20, and an intermediate layer formation step (5) to form an intermediate layer 13 by reacting the void layer 11 with the adhesive layer 12. The method for producing the sol particle liquid of pulverized gel-like compound is not particularly limited. The sol particle liquid can be specifically manufactured, for example, by the method described in International Publication No. 2019 / 065999 or International Publication No. 2019 / 065803. Alternatively, the sol particle liquid can also be manufactured, for example, by the method described in "Reference Example 1" of the embodiments of this application, which will be described later. Although not shown in the figures, the method for manufacturing the laminate of the present invention also includes, as described above, a viscous adhesive layer manufacturing step for manufacturing the viscous adhesive layer by the method for manufacturing the viscous adhesive layer of the present invention, and a bonding step for bonding the viscous adhesive layer to the void layer. The method for manufacturing the viscous adhesive layer of the present invention also includes, as described above, a viscous adhesive coating step for applying the viscous adhesive coating liquid to a substrate, and a heating and drying step for heating and drying the substrate to which the viscous adhesive coating liquid has been applied. The chemical treatment step (crosslinking step) (3) corresponds to the "void layer formation step" for forming the void layer in the laminate of the present invention. The intermediate layer formation step (5) corresponds to the heating step (aging step) described above. The intermediate layer formation step (5) (hereinafter sometimes referred to as the "aging step") may also serve as a step to improve the strength of the void layer 11 (a crosslinking reaction step that causes a crosslinking reaction inside the void layer 11), in which case, after the intermediate layer formation step (5), the void layer 11 changes into a void layer 11 with further improved strength. However, the present invention is not limited thereto, and for example, the void layer 11 does not have to change after the intermediate layer formation step (5).Furthermore, as mentioned above, the lamination step (4) may be the lamination of an adhesive tape having an adhesive layer on a substrate. In Figure 1, the substrate to which the adhesive coating liquid has been applied (to which the adhesive layer has been formed) is not shown, but for example, it may be peeled off and removed from the adhesive layer 12, or it may be left on the adhesive layer 12. By the above steps (1) to (5), a laminated film (laminated body) can be manufactured in which the void layer 11, the intermediate layer 13, and the adhesive layer 12 are laminated on the resin film 14 in the above order, as shown in Figure 3(a). However, the intermediate layer formation step (5) may be omitted, and the laminate of the present invention manufactured may not contain an intermediate layer. Furthermore, the method for manufacturing the laminate of the present invention may include or not include steps other than those described above as appropriate. Also, for example, as shown in the laminated film (laminated body) 10d in Figure 3(a), another film 14 may be laminated on top of the adhesive layer 12. Furthermore, although the laminated film (laminated body) 10d in Figure 3(a) has the adhesive layer 12 provided on only one side of the void layer 11, the adhesive layer 12 may also be provided on both sides of the void layer 11, for example, as in the laminated body 10e in Figure 3(b).

[0142] In the coating step (1) described above, the method of coating the sol particle liquid is not particularly limited, and a general coating method can be used. Examples of such coating methods include the slot die method, reverse gravure coating method, microgravure method (microgravure coating method), dip method (dip coating method), spin coating method, brush coating method, roll coating method, flexographic printing method, wire bar coating method, spray coating method, extrusion coating method, curtain coating method, reverse coating method, etc. Among these, the extrusion coating method, curtain coating method, roll coating method, microgravure coating method, etc. are preferred from the viewpoint of productivity and smoothness of the coating film. The amount of sol particle liquid to be coated is not particularly limited, and can be set as appropriate, for example, so that the thickness of the void layer 11 is appropriate. The thickness of the void layer 11 is not particularly limited, for example, as described above.

[0143] In the drying step (2) described above, the sol particle liquid is dried (i.e., the dispersion medium contained in the sol particle liquid is removed) to form the dried coating film (precursor of the void layer). The conditions for the drying treatment are not particularly limited and are as described above.

[0144] Furthermore, in the chemical treatment step (3), the dried coating film containing the catalyst or catalyst generator (e.g., photoactive catalyst, photocatalyst generator, thermally activated catalyst, or thermal catalyst generator) added before coating is irradiated with light or heated to chemically bond (for example, crosslink) the pulverized material within the dried coating film, thereby forming a void layer 11. The light irradiation or heating conditions in the chemical treatment step (3) are not particularly limited and are as described above.

[0145] On the other hand, although not shown in the figures, the adhesive layer of the present invention is manufactured separately by the adhesive layer manufacturing process described above. The adhesive layer manufacturing process (method for manufacturing the adhesive layer of the present invention) is, for example, as described above.

[0146] Furthermore, a bonding step (4) and an intermediate layer forming step (5) are performed. As described above, the intermediate layer forming step (5) is a heating step in which the adhesive layer 12 and the void layer 11 are heated after the bonding step (4). For example, if the adhesive is an adhesive composition containing a polymer (e.g., a (meth)acrylic polymer) and a crosslinking agent, the polymer may be crosslinked by the crosslinking agent in the heating step. The heating step may also serve as a drying step for the adhesive. Alternatively, the heating step may also serve as the intermediate layer forming step (5). The temperature of the heating step is not particularly limited, but is for example 70-160°C, 80-155°C, or 90-150°C. The duration of the heating step is not particularly limited, but is for example 1-10 minutes, 1-7 minutes, or 2-5 minutes. [Examples]

[0147] Next, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments.

[0148] In the following reference examples, examples, and comparative examples, the number of parts (relative amount used) of each substance is in parts by mass (parts by weight) unless otherwise specified. In the following reference examples, examples, and comparative examples, the adhesive used is the adhesive (adhesive composition) described later. In the following reference examples, examples, and comparative examples, "adhesive layer" corresponds to "adhesive bonding layer." That is, in the following reference examples, examples, and comparative examples, "adhesive layer" and "adhesive bonding layer" are synonymous unless otherwise specified.

[0149] Furthermore, in the following reference examples, examples, and comparative examples, the weight-average molecular weight (Mw) of the (meth)acrylic polymer, the gel fraction of the adhesive layer, the thickness of each layer, and the refractive index were measured using the measurement methods described below.

[0150] <Method for measuring the molecular weight of (meth)acrylic polymers> The weight-average molecular weight (Mw) of (meth)acrylic polymers was calculated from the molecular weight distribution curves measured by gel permeation chromatography (GPC). ·Analyzer: Waters, Alliance • Columns: Tosoh Corporation, G7000HXL + GMHXL + GMHXL • Column size: 7.8mmφ x 30cm each, total 90cm Column temperature: 40°C ·Flow rate: 0.8mL / min ·Injection volume: 100μL ·Eluent: THF (acid added) • Detector: Differential refractometer (RI) • Standard sample: Polystyrene

[0151] <Method for measuring the gel fraction of the adhesive layer> Sample 1 was obtained by scraping approximately 0.1 g of the optical adhesive layer formed on the peel-off surface of a separator film within one minute of preparation. Sample 1 was wrapped in a 0.2 μm diameter Teflon® film (product name "NTF1122", manufactured by Nitto Denko Corporation) and tied with kite string, which was designated as Sample 2. The weight of Sample 2 before being subjected to the following test was measured and designated as Weight A. Weight A is the total weight of Sample 1 (adhesive layer), the Teflon® film, and the kite string. The total weight of the Teflon® film and the kite string was designated as Weight B. Next, Sample 2 was placed in a 50 ml container filled with ethyl acetate and left to stand at 23°C for one week. After that, Sample 2 was removed from the container and dried in a dryer at 130°C for two hours to remove the ethyl acetate, and then the weight of Sample 2 was measured. The weight of Sample 2 after being subjected to the above test was measured and designated as Weight C. Then, the gel fraction was calculated using the following formula. Gel fraction (mass%) = (CB) / (AB) × 100

[0152] <Method for measuring thickness> The thickness of the adhesive layer was measured at five points using a dial gauge, and the average value was used. The thickness of the intermediate layer was defined as the portion with different contrast thicknesses between the adhesive layer and the low refractive index layer in the SEM image, and its thickness was measured at the average value of two points on the SEM image. <Method for measuring refractive index> The refractive index was measured using the refractive index evaluation method described above.

[0153] In the following reference examples, examples, and comparative examples, it is presumed that the adhesive layer formed by the heat drying of the coated adhesive caused the polymer (acrylic polymer) to be crosslinked by the crosslinking agent, thus forming a crosslinked structure; however, the crosslinked structure has not been confirmed.

[0154] [Reference Example 1: Manufacturing of coating liquid for void layer formation] First, a gel having a porous structure (silicone porous material) was produced by performing a gelation (step (1) below) and maturation (step (2) below) of a silicon compound. Subsequently, the following steps were performed: (3) morphology control step, (4) solvent replacement step, and (5) gel pulverization step to obtain a coating liquid for forming a void layer (liquid containing pulverized gel). In this reference example, as described below, the morphology control step (3) below was performed as a separate step from step (1) below. However, the present invention is not limited thereto, and for example, the morphology control step (3) below may be performed within step (1) below.

[0155] (1) Gelation of silicon compounds 9.5 kg of MTMS, a precursor of silicon compounds, was dissolved in 22 kg of DMSO. 5 kg of a 0.01 mol / L aqueous solution of oxalic acid was added to the mixture, and the mixture was stirred at room temperature for 120 minutes to hydrolyze the MTMS and produce tris(hydroxy)methylsilane.

[0156] To 55 kg of DMSO, 3.8 kg of 28% aqueous ammonia and 2 kg of pure water were added. Then, the hydrolyzed mixture was added and the mixture was stirred at room temperature for 60 minutes. After stirring for 60 minutes, the mixture was poured into a stainless steel container measuring 30 cm in length, 30 cm in width, and 5 cm in height, and allowed to stand at room temperature to gel tris(hydroxy)methylsilane, thereby obtaining a gel-like silicon compound.

[0157] (2) Aging process The gel-like silicon compound obtained by the aforementioned gelation treatment was incubated at 40°C for 20 hours to mature it, thereby obtaining the rectangular-shaped gel mass. Since the amount of DMSO (a high-boiling point solvent with a boiling point of 130°C or higher) used in the raw materials was approximately 83% by mass of the total raw materials, it was clear that this gel contained 50% or more by mass of a high-boiling point solvent with a boiling point of 130°C or higher. Furthermore, since the amount of MTMS (a monomer that forms the gel) used in the raw materials was approximately 8% by mass of the total raw materials, it was clear that the content of a solvent with a boiling point below 130°C (in this case, methanol) generated by the hydrolysis of the monomer (MTMS) that forms the gel was 20% or less by mass.

[0158] (3) Morphological control process Water, which is the substitution solvent, was poured onto the gel synthesized in the 30cm × 30cm × 5cm stainless steel container by the above steps (1) and (2). Next, the cutting blade of the cutting jig was slowly inserted into the gel from above in the stainless steel container, and the gel was cut into a rectangular parallelepiped measuring 1.5cm × 2cm × 5cm.

[0159] (4) Solvent replacement step Next, the solvent replacement process was carried out as described in (4-1) to (4-3) below.

[0160] (4-1) After the "(3) Morphological Control Step" described above, the gel-like silicon compound was immersed in water eight times its weight and slowly stirred for 1 hour so that only the water was circulating. After 1 hour, the water was replaced with the same amount of water and stirred for another 3 hours. After that, the water was replaced again and then heated at 60°C for 3 hours while slowly stirring.

[0161] (4-2) After (4-1), the water was replaced with isopropyl alcohol in an amount four times the weight of the gel-like silicon compound, and the mixture was heated at 60°C for 6 hours while stirring.

[0162] (4-3) After (4-2), the isopropyl alcohol was replaced with the same weight of isobutyl alcohol, and the mixture was heated at 60°C for 6 hours to replace the solvent contained in the gel-like silicon compound with isobutyl alcohol. In this manner, the gel for producing void layers of the present invention was produced.

[0163] (5) Gel grinding process The gel (gel-like silicon compound) after the solvent replacement step (4) was subjected to a two-stage grinding process: a first stage using continuous emulsification dispersion (Milder MDN304, manufactured by Taiheiyo Kiko Co., Ltd.) and a second stage using high-pressure medialess grinding (Starburst HJP-25005, manufactured by Sugino Machine Co., Ltd.). For this grinding process, 26.6 kg of isobutyl alcohol was added to 43.4 kg of the gel containing the solvent-substituted gel-like silicon compound, weighed, and then the first grinding stage was performed using circulating grinding for 20 minutes, followed by the second grinding stage at a grinding pressure of 100 MPa. In this way, an isobutyl alcohol dispersion (gel-like material-containing liquid) in which nanometer-sized particles (the pulverized gel) were dispersed was obtained. Furthermore, 224 g of a 1.5% solution of WPBG-266 (trade name, manufactured by Wako) methyl isobutyl ketone was added to 3 kg of the gel pulverized liquid, followed by 67.2 g of a 5% solution of bis(trimethoxylyl)ethane (manufactured by TCI) methyl isobutyl ketone. Then, 31.8 g of N,N-dimethylformamide was added and mixed to obtain a coating solution.

[0164] As described above, the coating liquid for forming a void layer (containing pulverized gel) for this reference example (Reference Example 1) was manufactured. Furthermore, the peak pore size of the pulverized gel (microporous particles) in the coating liquid for forming a void layer (containing pulverized gel) was measured using the method described above and was found to be 12 nm.

[0165] [Reference Example 2: Formation of an adhesive layer] The adhesive layer of this reference example (Reference Example 2) was formed by following the steps (1) to (2) below.

[0166] (1) Preparation of (meth)acrylic polymers (Preparation of (meth)acrylic polymer (A1)) A monomer mixture containing 79.5 parts butyl acrylate, 15 parts N-acryloylmorpholine, 5 parts acrylic acid, and 0.5 parts 4-hydroxybutyl acrylate was charged into a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser. Furthermore, 0.1 parts 2,2'-azobisisobutyronitrile was added to 100 parts of the monomer mixture as a polymerization initiator along with 70 parts ethyl acetate. After introducing nitrogen gas and purging the flask with nitrogen while gently stirring, the polymerization reaction was carried out for 2 hours while maintaining the temperature of the liquid in the flask at around 55°C to prepare a solution of (meth)acrylic polymer (A1) with a weight-average molecular weight (Mw) of 3.4 million and Mw / Mn = 2.5.

[0167] (Preparation of (meth)acrylic polymer (A2)) In the preparation of (meth)acrylic polymer (A1), the starting monomer composition was 79.5 parts butyl acrylate, 7.5 parts N-acryloylmorpholine, 5 parts acrylic acid, and 0.5 parts 4-hydroxybutyl acrylate, with a polymerization reaction time of 8 hours. The rest of the preparation was carried out in the same manner to prepare a solution of (meth)acrylic polymer (A2) with a weight-average molecular weight (Mw) of 2.9 million and Mw / Mn = 4.2.

[0168] (2) (Preparation of adhesive composition) An acrylic adhesive composition was prepared by blending 0.2 parts of an oligomer-type silane coupling agent (product name "X-41-1056" manufactured by Shin-Etsu Silicone Co., Ltd.), 0.2 parts of an isocyanate crosslinking agent (product name "Coronate L" manufactured by Nippon Polyurethane Industries Co., Ltd., an adduct of trimethylolpropane tolyleneisocyanate), 0.1 parts of an epoxy crosslinking agent (product name "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Ltd.), and 0.2 parts of benzoyl peroxide (product name "Nipper BMT" manufactured by Nippon Oil & Fats Co., Ltd.) with 100 parts of the solid content of (meth)acrylic polymer (A1).

[0169] (3) (Formation of adhesive layer) Next, the acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone release agent, such that the thickness of the adhesive layer after drying was 10 μm. The film was then dried at 155°C for 1 minute to form an adhesive layer (adhesive layer) on the surface of the separator film.

[0170] [Example 1] (Manufacturing of laminates) The high porosity layer-forming coating liquid prepared in Reference Example 1 was applied to an acrylic substrate and dried to form a void layer with a thickness of approximately 850 nm (voidity 59 vol%). Next, UV irradiation (300 mJ) was performed from the void layer surface. Subsequently, the 10 μm thick adhesive layer obtained in Reference Example 2 was bonded to the void layer surface, and aging was performed at 60°C for 20 hours to produce the laminate of this embodiment.

[0171] [Examples 2-4 and Comparative Examples 1-3] The laminates of Examples 2-4 and Comparative Examples 1-3 were manufactured as follows.

[0172] In Example 3 and Comparative Example 3, as shown in Table 1 below, (meth)acrylic polymer (A2) was used instead of (meth)acrylic polymer (A1) in the preparation of the adhesive composition shown in Reference Example 2.

[0173] In Example 4, the oligomer-type silane coupling agent "X-24-9591F" (product name of Shin-Etsu Silicone Co., Ltd.) was used instead of the oligomer-type silane coupling agent "X-41-1056". In Comparative Example 1, as shown in Table 1 below, a monomer-type silane coupling agent (product name "KBM-403" manufactured by Shin-Etsu Silicone Co., Ltd.) was used instead of the oligomer-type silane coupling agent, based on the composition of the adhesive composition shown in Reference Example 2. In Comparative Example 2, the oligomer-type silane coupling agent was not used.

[0174] Furthermore, in Examples 2-4 and Comparative Examples 1-3, the amounts of silane coupling agent, crosslinking agent, and peroxide used were as shown in Table 1 below. Except for appropriately changing the type of (meth)acrylic polymer and silane coupling agent, and the amounts of peroxide and crosslinking agent used, the acrylic adhesive compositions used in the production of the laminates of Examples 2-4 and Comparative Examples 1-3 were prepared in the same manner as in Example 1. Furthermore, using the acrylic adhesive composition solutions, adhesive layers were prepared in the same manner as in Example 1 to produce the laminates of Examples 2-4 and Comparative Examples 1-3.

[0175] [Heat resistance test] Furthermore, the laminates of this embodiment and comparative example, manufactured as described above, were placed in an oven at a temperature of 65°C and a relative humidity of 95% for a 1000-hour heat durability test. The rate of change in refractive index was calculated from the refractive index before and after the heat durability test using formula (1). In addition, the delamination of the intermediate layer and the adherend after the heat durability test (hereinafter sometimes referred to as "delamination durability") was visually confirmed. These results are shown in Table 1.

[0176] The evaluation criteria for the initial refractive index in Table 1 are as follows: ◎: 1.20 or less ○: Greater than 1.20 and less than or equal to 1.21 △: Greater than 1.21 and less than 1.23 ×: 1.23 or higher

[0177] The evaluation criteria for refractive index (change) after the heat resistance test in Table 1 are as follows: ◎: 0.005 or less ○: Greater than 0.005 and less than or equal to 0.01 △: Greater than 0.01 and less than or equal to 0.015 ×: Exceeds 0.015

[0178] The meanings of the abbreviations shown in Table 1 below are as follows. Isocyanate: Adduct of trimethylolpropane tolylene diisocyanate (product name "Coronate L" manufactured by Tosoh Corporation) Epoxy: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (product name "Tetrad C" manufactured by Mitsubishi Gas Chemical Company) Peroxide: Benzoyl peroxide (product name "Nipper BMT" manufactured by Nippon Oil & Fats Co., Ltd.)

[0179] [Table 1]

[0180] As shown in Table 1 above, Examples 1 to 4, which used an oligomer-type silane coupling agent and had an amount of silane coupling agent of 1 part by mass or less, exhibited low initial refractive index, low refractive index (change) after the heat durability test, and excellent peel resistance. In other words, the laminates of Examples 1 to 4 had low initial refractive index and excellent heat durability because the adhesive did not easily penetrate the voids in the void layer, and these effects were achieved simultaneously with strong adhesion between the adhesive layer and the low refractive index layer. In contrast, when a monomer-type silane coupling agent was used (Comparative Example 1), when the amount of oligomer-type silane coupling agent added exceeded 1 part by mass (Comparative Example 3), or when no silane coupling agent was used (Comparative Example 2), the adhesive easily penetrated the voids in the void layer, resulting in poor initial refractive index, poor heat durability, or poor adhesion between the adhesive layer and the low refractive index layer. Furthermore, when the oligomeric silane coupling agent had an acid anhydride substituent, both the heat resistance and the adhesion between the adhesive layer and the low refractive index layer were better compared to Comparative Example 2, in which no silane coupling agent was used. [Industrial applicability]

[0181] As described above, the present invention provides laminates, optical members, and optical devices that achieve both adhesive strength and resistance to penetration of adhesives into the voids of the void layer. The applications of the present invention are not particularly limited. For example, the optical device of the present invention is not particularly limited and includes image display devices, lighting devices, etc. Examples of image display devices include liquid crystal displays, organic EL displays, micro-LED displays, etc. Examples of lighting devices include organic EL lighting, etc. According to the laminate of the present invention, for example, adhesives do not easily penetrate into the voids of the void layer even under high temperature and high humidity conditions, making it particularly suitable for use under high-durability conditions such as in automotive applications. Furthermore, the applications of the laminate of the present invention are not limited to the optical members and optical devices of the present invention and are arbitrary, and can be used in a wide range of applications. [Explanation of symbols]

[0182] 10, 10a, 10b, 10c, 10d, 10e laminate 11 Porous layer 12 Adhesive layer 13. Middle Class 14 Base material

Claims

1. It includes a void layer and an adhesive layer, The adhesive layer is directly laminated on one or both sides of the void layer. The adhesive layer is formed from an adhesive comprising a (meth)acrylic polymer, an oligomer-type silane coupling agent, and a crosslinking agent. The (meth)acrylic polymer contains 1 to 30% by mass of nitrogen-containing monomers as monomer units. A laminate characterized in that the content of the oligomer-type silane coupling agent is 1 part by mass or less per 100 parts by mass of the (meth)acrylic polymer.

2. The laminate according to claim 1, characterized in that the oligomeric silane coupling agent contains an epoxy group.

3. The laminate according to claim 1 or 2, wherein the weight-average molecular weight (Mw) of the (meth)acrylic polymer is 1.5 million to 4 million.

4. The laminate according to any one of claims 1 to 3, wherein the weight-average molecular weight (Mw) of the oligomer-type silane coupling agent is 300 or more.

5. The laminate according to any one of claims 1 to 4, wherein the adhesive has a gel fraction of more than 85%.

6. The laminate according to any one of claims 1 to 5, wherein the nitrogen-containing monomer is a heterocyclic acrylic monomer.

7. The laminate according to any one of claims 1 to 6, characterized in that, before and after a heat durability test in which the temperature is maintained at 65°C and relative humidity at 95% for 1000 hours, the increase in the refractive index of the void layer satisfies the following formula (1), and the initial refractive index before the heat durability test satisfies the following formula (2). n-n ０ ≦0.015 (1) n ０ <1.23 (2) In the above formula (1), n ​​is the refractive index of the void layer after the heat endurance test. In the above formula (2), n ０ This is the refractive index of the void layer before the heat resistance test.

8. An intermediate layer exists between the aforementioned void layer and the aforementioned adhesive layer. The claim states that the intermediate layer is a layer formed by the union of the void layer and the adhesive layer. A laminate as described in any one of items 1 to 7.

9. The laminate according to claim 8, wherein the thickness of the intermediate layer is 10 to 100 nm.

10. An optical member characterized by comprising a laminate according to any one of claims 1 to 9.

11. An optical device characterized by including the optical member described in claim 10.

Images