Thin films, optical components, and optical devices.

Abstract

The invention relates to a thin sheet (10) comprising a porous layer (11), and a pressure-sensitive adhesive / bonding layer (12) directly layered on one or both surfaces of the porous layer. The pressure-sensitive adhesive / bonding layer comprises a polymer (met)acrylic and an organic silyl group-containing compound. The rate of increase of the refractive index of the porous layer before and after a thermal resistance test involving holding the sheet at a temperature of 65°C and a relative humidity of 95% for 500 hours satisfies the following formula (1): (|n − n0| / n0) × 100 < 3.0 (1). In formula (1), n ​​is the refractive index of the porous layer after the thermal resistance test, and n0 is the refractive index of the porous layer before the thermal resistance test.

Description

Laminate, optical member, and optical device

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

[0002] In optical devices, for example, an air layer with a low refractive index is used as a total reflection layer. Specifically, for example, in a liquid crystal device, optical film components (e.g., a light guide plate and a reflector) are stacked with an air layer between them. However, if the components are separated by an air layer, problems such as component deflection may occur, especially when the components are large. Furthermore, due to the trend toward thinner devices, integration of the components is desired. Therefore, components are integrated with adhesives without an air layer (e.g., Patent Document 1). However, if the air layer that performs the role of total reflection is lost, optical properties such as light leakage may be degraded.

[0003] Therefore, it has been proposed to use a low refractive index layer instead of the air layer. For example, Patent Document 2 describes a structure in which a layer having a lower refractive index than the light guide plate is inserted between the light guide plate and the reflector. As the low refractive index layer, for example, an air gap layer having voids is used in order to make the refractive index as low as possible to that of air.

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

[0005] JP 2012-156082 A JP 10-62626 A JP 2014-46518 A

[0006] The void layer is used by laminating it with another layer, for example, via a tacky adhesive layer. However, when the void layer and the tacky adhesive layer are laminated together, the adhesive or the adhesive constituting the tacky adhesive layer may penetrate into the voids of the void layer and fill the voids, thereby reducing the porosity of the void layer and increasing the refractive index. The higher the porosity of the void layer, the easier it is for the adhesive or the adhesive to penetrate. Furthermore, in a high-temperature environment, the molecular motion (decreased modulus) of the adhesive or the adhesive makes it easier for the adhesive or the adhesive to penetrate into the voids. In a high-humidity environment, the adhesive or the adhesive absorbs water, making it easier for the adhesive or the adhesive to penetrate into the voids.

[0007] In order to suppress or prevent the pressure-sensitive adhesive or adhesive from penetrating into the voids, it is advisable to use a pressure-sensitive adhesive or adhesive with as high a modulus of elasticity (hardness) as possible. However, if the pressure-sensitive adhesive or adhesive has a high modulus of elasticity (hardness), the adhesive strength or bonding strength may be reduced. Conversely, if the pressure-sensitive adhesive or adhesive has a low modulus of elasticity (softness), high adhesive strength or bonding strength may be easily obtained, but the pressure-sensitive adhesive or adhesive may be more likely to penetrate into the voids.

[0008] Therefore, an object of the present disclosure is to provide a laminate, an optical member, and an optical device that combines adhesive strength or bonding strength with the resistance to penetration of a pressure-sensitive adhesive or adhesive into the voids in the void layer.

[0009] In order to achieve the above object, the laminate of the present disclosure comprises a void layer and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer being directly laminated on one or both sides of the void layer, the pressure-sensitive adhesive layer being formed from a pressure-sensitive adhesive containing a (meth)acrylic polymer and an organosilyl group-containing compound, the organosilyl group of the organosilyl group-containing compound may or may not contain a carbon-silicon bond, and is characterized in that the rate of increase in the refractive index of the void layer before and after a heat durability test in which the layer is maintained at a temperature of 65°C and a relative humidity of 95% for 500 hours satisfies the following mathematical formula (1): (|n - n ０ | / n ０)×100<3.0 (1) In the formula (1), n ​​is the refractive index of the porous layer after the heat durability test, and n ０ is the refractive index of the air gap layer before the heat durability test.

[0010] The optical member of the present disclosure is characterized by including the laminate of the present disclosure.

[0011] The optical device of the present disclosure is characterized by including the optical member of the present disclosure.

[0012] According to the present disclosure, it is possible to provide a laminate, an optical member, and an optical device that combines adhesive strength or bonding strength with the resistance to penetration of a pressure-sensitive adhesive or adhesive into the voids in the void layer.

[0013] 1(a) and 1(b) are cross-sectional views illustrating the configuration of a laminate according to the present disclosure. 2(a) and 2(b) are cross-sectional views illustrating another example of the configuration of a laminate according to the present disclosure. 3(a) and 3(b) are cross-sectional views illustrating yet another example of the configuration of a laminate according to the present disclosure.

[0014] Next, the present disclosure will be described in more detail using examples, but the present disclosure is not limited to the following description.

[0015] In the laminate of the present disclosure, for example, the content of the organosilyl group-containing compound may be 5.0 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic polymer.

[0016] In the laminate of the present disclosure, for example, the organic silyl group-containing compound may be a compound containing an alkoxysilyl group.

[0017] In the laminate of the present disclosure, for example, the (meth)acrylic polymer may have a weight average molecular weight (Mw) of 1.5 million to 4 million.

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

[0019] In the laminate of the present disclosure, for example, the (meth)acrylic polymer may contain 1 to 30 mass % of a nitrogen-containing monomer as a monomer unit. Note that, in the present disclosure, 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 disclosure, for example, the nitrogen-containing monomer may be a heterocycle-containing acrylic monomer.

[0021] In the laminate of the present disclosure, for example, the (meth)acrylic polymer may contain 0.5 to 20 mass % of acrylic acid as a monomer unit.

[0022] In the laminate of the present disclosure, for example, the void layer may not contain an organic fluorine compound. By not including an organic fluorine compound in the void layer, it is possible to provide an environmentally friendly laminate, optical member, and optical device including a void layer. Note that the void layer "does not contain" an organic fluorine compound means that an analysis of the void layer does not detect any organic fluorine compound, and the presence of an organic fluorine compound in the void layer cannot be proven.

[0023] In the laminate of the present disclosure, for example, an intermediate layer may be present between the void layer and the adhesive layer, and the intermediate layer may be a layer formed by combining the void layer and the adhesive layer.

[0024] In the laminate of the present disclosure, for example, the intermediate layer may have a thickness of 10 to 100 nm.

[0025] In the present disclosure, the term "adhesive layer" refers to a layer formed of at least one of a pressure-sensitive adhesive and an adhesive. In the present disclosure, unless otherwise specified, the term "adhesive layer" may refer to a "pressure-sensitive adhesive layer" formed of a pressure-sensitive adhesive, an "adhesive layer" formed of an adhesive, or a layer containing both a pressure-sensitive adhesive and an adhesive. Furthermore, in the present disclosure, pressure-sensitive adhesives and adhesives may be collectively referred to as "adhesive adhesives." Generally, a material with relatively weak adhesive or bonding strength (e.g., a material that allows for re-detachment from an adherend) is referred to as a "pressure-sensitive adhesive," while a material with relatively strong adhesive or bonding strength (e.g., a material that is impossible or extremely difficult to re-detach from an adherend) is referred to as an "adhesive." In the present disclosure, there is no clear distinction between a pressure-sensitive adhesive and an adhesive. Furthermore, in the present disclosure, there is no clear distinction between "adhesive strength" and "adhesive strength."

[0026] In addition, in the present disclosure, "on" or "on the surface" may refer to a state of being in direct contact with the surface or a state of being via another layer or the like.

[0027] In the laminate of the present disclosure, for example, the (meth)acrylic polymer may be a (meth)acrylic polymer having a weight average molecular weight of 2,000,000 to 3,500,000 obtained by polymerizing, as monomer components, 3 to 20% by mass of a heterocycle-containing acrylic monomer (heterocycle-containing acrylate), 0.5 to 5% by mass of (meth)acrylic acid, 0.05 to 2% by mass of a hydroxyalkyl (meth)acrylate, and 83 to 96.45% by mass of an alkyl (meth)acrylate.

[0028] In the laminate of the present disclosure, 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 heterocycle-containing acrylic monomer (heterocycle-containing acrylate).

[0029] In the laminate of the present disclosure, the gel fraction of the adhesive forming the adhesive layer may be, for example, 85% by mass or more, or may exceed 85% by mass, and may be, for example, 90% by mass or more, 91% by mass or more, or 93% by mass or more, or may be, for example, 100% by mass or less, 99% by mass or less, or 98% by mass or less.

[0030] In the laminate of the present disclosure, the initial refractive index of the porous layer before the heat durability test (hereinafter sometimes referred to as "initial refractive index") may be, for example, 1.30 or less or less than 1.30, or may be, for example, 1.25 or less, less than 1.25, 1.20 or less, or less than 1.20. The lower limit of the initial refractive index may be, for example, 1.05 or more, 1.06 or more, 1.07 or more, or 1.08 or more.

[0031] In the laminate of the present disclosure, the refractive index of the porous layer after the heat durability test may be, for example, 1.50 or less or less than 1.50, and may be, for example, 1.40 or less, less than 1.40, 1.30 or less, or less than 1.30. The lower limit of the refractive index of the porous layer after the heat durability test may be, for example, 1.05 or more, 1.06 or more, 1.07 or more, or 1.08 or more.

[0032] In the laminate of the present disclosure, before and after a heat durability test in which the laminate is maintained at a temperature of 65°C and a relative humidity of 95% for 500 hours, |n-n ０ The change in refractive index of the air gap layer represented by | may be less than 0.04, for example. ０ The change in refractive index of the air gap layer represented by | may be, for example, 0.03 or less, less than 0.03, 0.02 or less, or less than 0.02. ０ The lower limit of the change in refractive index of the air gap layer represented by | is not particularly limited, but may be, for example, 0 or more, or may be a value exceeding 0. ０ is the refractive index (initial refractive index) of the air gap layer before the heat durability test, as in the above formula (1), and n is the refractive index of the air gap layer after the heat durability test, as in the above formula (1).

[0033] In the laminate of the present disclosure, the (|nn-n ０ | / n ０ The increase rate (%) of the refractive index of the porous layer, expressed as (|nn-n)×100, is less than 3.0% as shown in the above formula (1). ０ | / n ０ The increase rate of the refractive index of the air gap layer, expressed as (|n-n)×100, may be, for example, 2.0% or less, less than 2.0%, 1.0% or less, or less than 1.0%. ０ | / n ０ The lower limit of the rate of increase in the refractive index of the porous layer, expressed as (x)×100, is not particularly limited, but may be, for example, 0 or more, or may be a value exceeding 0.

[0034] In the laminate of the present disclosure, for example, the porosity of the porous layer may be 35% by volume or more.

[0035] In the laminate of the present disclosure, for example, the porous layer may be a porous body in which microporous particles are chemically bonded to one another.

[0036] In the laminate of the present disclosure, the adhesive layer may be a layer formed by a method including, for example, a pressure-sensitive adhesive coating liquid preparation step of preparing a pressure-sensitive adhesive coating liquid containing a (meth)acrylic polymer and an organosilyl group-containing compound, a pressure-sensitive adhesive coating liquid application step of applying the pressure-sensitive adhesive coating liquid to a substrate, and a heat-drying step of heating and drying the substrate coated with the pressure-sensitive adhesive coating liquid. In the laminate of the present disclosure, for example, the pressure-sensitive adhesive layer may be formed from a pressure-sensitive adhesive coating liquid having a specific composition and integrated with a void layer. This can suppress significant penetration of the pressure-sensitive adhesive layer into the void layer, especially during long-term heat durability tests. The pressure-sensitive adhesive coating liquid may further contain, for example, a crosslinking agent, or may contain other components as described below.

[0037] The reason (mechanism) why the laminate of the present disclosure can achieve both adhesive strength or bond strength and low penetration of the adhesive or adhesive into voids is thought to be, for example, as follows. For example, by forming an adhesive layer using a specific adhesive, both adhesive strength or bond strength and low penetration of the adhesive or adhesive into voids can be achieved. More specifically, for example, by forming an adhesive layer using the above-mentioned specific (meth)acrylic polymer and, if necessary, a crosslinking agent, an intermediate layer is formed by coalescence of a portion of the void layer and a portion of the adhesive layer. Furthermore, by using the above-mentioned specific (meth)acrylic polymer, the intermediate layer does not expand excessively even under conditions such as the heat durability test. Furthermore, the intermediate layer acts as a stopper, preventing a decrease in porosity due to the voids in the void layer being filled with the adhesive. Even if the molecular motion of the adhesive increases under heat, if the adhesive has a high elastic modulus, the intermediate layer formed from the adhesive and the high void layer easily becomes a strong and dense stopper, thereby preventing the adhesive from penetrating into the high void layer. However, these mechanisms are merely examples and do not limit the present disclosure in any way.

[0038] Furthermore, by including a monomer having one or two reactive double bonds per molecule, the adhesive coating liquid can undergo a crosslinking reaction with a crosslinking agent, such as an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent, upon heating. During the crosslinking reaction, the coexistence of the monomer having one or two reactive double bonds per molecule and an organic peroxide, which serves as a hydrogen abstraction initiator, is thought to cause high-density crosslinking of semi-high molecular weight polymer components having a molecular weight of 10,000 or less contained in the adhesive coating liquid, thereby enabling even higher levels of inhibition of component penetration from the adhesive coating liquid into the void layer. That is, semi-high molecular weight polymer components having a molecular weight of 10,000 or less easily penetrate into the voids of the void layer due to their small molecular size, but the crosslinking reaction increases their molecular size, thereby inhibiting penetration into the voids of the void layer. Furthermore, it is presumed that the coexistence of a monomer having one or two reactive double bonds in one molecule during the crosslinking reaction enables a graft reaction with the (meth)acrylic polymer main chain and high-density crosslinking starting from the graft chain, thereby reducing the amount of semi-high molecular weight polymer that can become a sol component. However, these mechanisms are also examples and do not limit the present disclosure in any way.

[0039] In the adhesive coating liquid for forming the adhesive layer in the laminate of the present disclosure, the nitrogen-containing monomer preferably has a small number of functional groups (the number of reactive double bonds in one molecule) in order to efficiently crosslink main chains in a graft reaction, and for example, as described above, the number of reactive double bonds in one molecule is preferably one or two.

[0040]

[0013] Even if a monomer having one or two reactive double bonds is mixed during the production of a (meth)acrylic polymer, it is difficult to reduce the amount of the semi-high molecular weight polymer (which has a small molecular weight and easily penetrates into the voids of the void layer) as described above. However, according to the present disclosure, by using a pressure-sensitive adhesive coating liquid in which a monomer having one or two reactive double bonds is subsequently mixed with a (meth)acrylic polymer and then subjected to a crosslinking reaction, for example, a graft reaction as described above occurs, thereby making it possible to reduce the amount of the semi-high molecular weight polymer.

[0041] In the present disclosure, "(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. "Methyl (meth)acrylate" means at least one of methyl acrylate and methyl methacrylate.

[0042] In the present disclosure, the term "(meth)acrylic polymer" refers to a polymer having a structure obtained by polymerizing a component containing at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, monomers having an acryloyl group, and monomers having a methacryloyl group. The component may or may not contain a substance other than at least one selected from the group consisting of acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, monomers having an acryloyl group, and monomers having a methacryloyl group, as appropriate.

[0043] In the present disclosure, the term "acrylic monomer" refers to, for example, a monomer including at least one selected from the group consisting of acrylic acid, acrylic esters, and monomers having an acryloyl group.

[0044] In the present disclosure, the term "isocyanate-based crosslinking agent" refers to, for example, a crosslinking agent having an isocyanate group (isocyanato group) in the molecule. In the present disclosure, the number of isocyanate groups (isocyanato groups) in one molecule of the isocyanate-based crosslinking agent is not particularly limited, but is preferably 2 or more, and may be, for example, 2, 3, or 4. The upper limit is not particularly limited, but is, for example, 10 or less.

[0045] In the present disclosure, the term "epoxy-based crosslinking agent" refers to, for example, a crosslinking agent having an epoxy group in the molecule. In the present disclosure, the number of epoxy groups in one molecule of the epoxy-based crosslinking agent is not particularly limited, but is preferably 2 or more, and may be, for example, 2, 3, or 4. The upper limit is not particularly limited, but is, for example, 10 or less.

[0046] [1. Laminate, Optical Member, and Optical Device] As described above, the laminate of the present disclosure includes a void layer and an adhesive layer, and the adhesive layer is directly laminated on one or both sides of the void layer. In the present disclosure, the expression "directly laminated" of the adhesive layer on the void layer means, for example, that the adhesive layer may be in direct contact with the void layer, or that the adhesive layer may be laminated on the void layer via the intermediate layer.

[0047] The cross-sectional view of Fig. 1(a) shows an example of the configuration of a laminate of the present disclosure. As shown in the figure, this laminate 10 has a tacky adhesive layer 12 directly laminated on one side of a void layer 11. Moreover, the cross-sectional view of Fig. 1(b) shows another example of the configuration of a laminate of the present disclosure. As shown in the figure, this laminate 10a has a tacky adhesive layer 12 directly laminated on both sides of a void layer 11.

[0048] Furthermore, as described above, the laminate of the present disclosure may have an intermediate layer between the void layer and the adhesive layer, and the intermediate layer may be a layer formed by combining the void layer and the adhesive layer. FIG. 2 shows an example of such a laminate of the present disclosure. As shown in FIG. 2( a), the laminate 10b has an adhesive layer 12 directly laminated on one side of the void layer 11. This laminate 10b is the same as the laminate 10 of FIG. 1( a), except that an intermediate layer 13 is present between the void layer 11 and the adhesive layer 12. The intermediate layer 13 is a layer formed by combining the void layer 11 and the adhesive layer 12. As shown in FIG. 2( b), the laminate 10c has adhesive layers 12 directly laminated on both sides of the void layer 11. This laminate 10c is the same as the laminate 10a of FIG. 1( b), except that an intermediate layer 13 is present between the void layer 11 and each adhesive layer 12. The intermediate layer 13 is a layer formed by combining the void layer 11 and the adhesive layer 12, as in FIG. 2(a).

[0049] Furthermore, the laminate of the present disclosure may or may not include other components besides the void layer, the adhesive layer, and the intermediate layer. The other components are not particularly limited, and may be, for example, a substrate. The substrate is also not particularly limited, and may be, for example, a film (e.g., a resin film), a glass plate, or the like, as described below. Figure 3 shows an example of such a laminate of the present disclosure. The laminate 10d of Figure 3(a) is the same as the laminate 10b of Figure 2(a) except that, as shown, a substrate 14 is provided in direct contact with the surface of the void layer 11 opposite the adhesive layer 12, and with the surface of the adhesive layer 12 opposite the void layer 11. The laminate 10e of Figure 3(b) is the same as the laminate 10c of Figure 2(b) except that, as shown, a substrate 14 is provided in direct contact with the surface of each of the adhesive layers 12 on both sides opposite the void layer 11. In Figures 3(a) and 3(b), a substrate 14 is provided on both sides of the laminate. However, the present disclosure is not limited thereto, and for example, the substrate 14 may be provided on only one side. Also, in FIGS. 3( a) and 3(b), the substrate 14 is provided so as to be in direct contact with the void layer 11 or the adhesive layer 12. However, the present disclosure is not limited thereto, and for example, other components may be present between the substrate 14 and the void layer 11 or the adhesive layer 12. The other components are not particularly limited, and may be, for example, an optical functional layer. The optical functional layer is also not particularly limited, and may be, for example, an optical functional layer used in a general optical film, such as a microlens film, a prism film, a diffusion film, a polarizing reflective film, a polarizing film, a retardation film, or a high refractive index layer.

[0050] The laminate of the present disclosure may have a light transmittance of 80% or more for the laminate of the adhesive layer and the void layer, or for the laminate of the adhesive layer, the intermediate layer, and the void layer. The haze of the laminate may be 3% or less, for example. The light transmittance may be, for example, 82% or more, 84% or more, 86% or more, or 88% or more. The upper limit is not particularly limited, but is ideally 100%, and may be, for example, 95% or less, 92% or less, 91% or less, or 90% or less. The haze of the laminate may be measured, for example, by the same method as the haze measurement of the void layer described below. The light transmittance is the transmittance of light at a wavelength of 550 nm, and can be measured, for example, by the following measurement method.

[0051] (Method for Measuring Light Transmittance) Using a spectrophotometer U-4100 (trade name of Hitachi, Ltd.), the laminate is used as a sample to be measured. The total light transmittance (light transmittance) of the sample is measured when the total light transmittance of air is taken as 100%. The total light transmittance (light transmittance) value is the value measured at a wavelength of 550 nm.

[0052] In the laminate of the present disclosure, for example, the adhesive strength or bond strength of the adhesive layer may be, 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 attached to another layer, it is preferable that the adhesive strength or bond strength of the adhesive layer is not too low. Furthermore, from the viewpoint of rework when reattaching, it is preferable that the adhesive strength or bond strength of the adhesive layer is not too high. The adhesive strength or bond strength of the adhesive layer can be measured, for example, as follows.

[0053] (Method for Measuring Adhesive Strength or Adhesion Strength) A laminate film of the present disclosure (a laminate of the present disclosure formed on a resin film substrate) is sampled 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 (thickness 20 μm) is attached 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 laminate film of the present disclosure opposite the resin film, thereby laminating it with the PET film. Next, the sample is chucked in an autograph tensile tester (manufactured by Shimadzu Corporation: AG-Xplus) so that the chuck distance is 100 mm, and a tensile test is performed at a tensile speed of 0.3 m / min. The average test force after a 50 mm peel test is taken as the adhesive peel strength, i.e., adhesive strength. Adhesion strength can also be measured using the same measurement method. In the present disclosure, there is no clear distinction between "adhesive strength" and "adhesive strength."

[0054] The laminate of the present disclosure may be formed on a substrate such as a film. The film may be, for example, a resin film. Generally, a relatively thin film is called a "film" and a relatively thick film is called a "sheet," but in the present disclosure, there is no particular distinction between the "film" and the "sheet."

[0055] The substrate is not particularly limited, and examples thereof include, but are not limited to, substrates made of thermoplastic resins, glass substrates, inorganic substrates such as silicon, plastics molded from thermosetting resins, semiconductor elements, and carbon fiber materials such as carbon nanotubes. Examples of the substrate include films and plates. Examples of the thermoplastic resin include polyethylene terephthalate (PET), acrylic, cellulose acetate propionate (CAP), cycloolefin polymer (COP), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polyethylene (PE), and polypropylene (PP).

[0056] The optical member of the present disclosure is not particularly limited, and may be, for example, an optical film including the laminate of the present disclosure.

[0057] The optical device of the present disclosure is not particularly limited, and may be, for example, an image display device or a lighting device. Examples of image display devices include liquid crystal displays, organic electroluminescence (EL) displays, and micro-LED (light-emitting diode) displays. Examples of lighting devices include organic EL lighting.

[0058] [2. Void Layer] The void layer in the laminate of the present disclosure (hereinafter, sometimes referred to as the "void layer of the present disclosure") will be described below using examples. However, the void layer of the present disclosure is not limited thereto.

[0059] The porous layer of the present disclosure may have a porosity of 35% by volume or more and a peak pore size of 50 nm or less, for example, although this is merely an example and the porous layer of the present disclosure is not limited thereto.

[0060] The porosity may be, for example, 35% by volume or more, 38% by volume or more, or 40% by volume or more, or 90% by volume or less, 80% by volume or less, or 75% by volume or less. The porous layer of the present disclosure may be, for example, a highly porous layer having a porosity of 60% by volume or more.

[0061] The porosity can be measured, for example, by the following measurement method.

[0062] (Method of measuring porosity) If the layer to be measured for porosity is a single layer containing only voids, the ratio (volume ratio) of the constituent material of the layer to air can be calculated by a standard method (for example, measuring the weight and volume to calculate the density), and thus the porosity (volume %) can be calculated. In addition, since there is a correlation between the refractive index and the porosity, for example, the porosity can also be calculated from the refractive index value of the layer. Specifically, for example, the porosity is calculated from the refractive index value measured with an ellipsometer using the Lorentz-Lorenz's formula.

[0063] The porous layer of the present disclosure can be produced, for example, by chemically bonding pulverized gel particles (microporous particles), as described below. In this case, the voids in the porous layer can be conveniently divided into the following three types (1) to (3): (1) voids in the raw gel itself (inside the particles); (2) voids in the pulverized gel particles; and (3) voids between the pulverized gel particles due to their accumulation.

[0064] The voids (2) are voids formed during pulverization, separate from the voids (1), which may be formed within each block when each particle group produced by pulverizing the gel is considered as a single block, regardless of the size, dimensions, etc., of the pulverized gel (microporous particles). The voids (3) are voids that arise during pulverization (e.g., media-less pulverization) due to the uneven size, dimensions, etc., of the pulverized gel (microporous particles). The void layer of the present disclosure has, for example, the voids (1) to (3), and thereby has an appropriate porosity and peak pore diameter.

[0065] 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. If the peak pore diameter is too large in a porous layer when the porosity is high, light will be scattered and the layer will become opaque. In the present disclosure, the lower limit of the peak pore diameter of the porous layer is not particularly limited, but if the peak pore diameter is too small, it will be difficult to increase the porosity, so it is preferable that the peak pore diameter is not too small. In the present disclosure, the peak pore diameter can be measured, for example, by the following method.

[0066] (Method for measuring peak pore diameter) A pore distribution / specific surface area measuring device (BELLSORP MINI / trade name of MicrotrackBell Co., Ltd.) is used to calculate the peak pore diameter from the results of calculating the BJH plot and BET plot by nitrogen adsorption and the isothermal adsorption curve.

[0067] Furthermore, the thickness of the air gap layer of the present disclosure is not particularly limited, but may be, for example, 100 nm or more, 200 nm or more, or 300 nm or more, or 10,000 nm or less, 5,000 nm or less, or 2,000 nm or less.

[0068] For example, as described below, the porous layer of the present disclosure uses a pulverized porous gel, which destroys the three-dimensional structure of the porous gel and forms a new three-dimensional structure different from the porous gel. Thus, the void layer of the present disclosure forms a layer with a new pore structure (new void structure) that cannot be obtained in a layer formed from the porous gel, thereby forming a nanoscale void layer with a high porosity. Furthermore, when the void layer of the present disclosure is a silicone porous body, for example, the pulverized materials are chemically bonded together while adjusting the number of siloxane bond functional groups in the silicon compound gel. Here, "silicone porous body" refers to a polymeric porous body containing siloxane bonds, including, for example, a porous body containing silsesquioxane as a structural unit. Furthermore, since a new three-dimensional structure is formed as a precursor of the void layer, the void layer is chemically bonded (e.g., cross-linked) in a bonding step, and therefore, when the void layer is a functional porous body, the void layer of the present disclosure has a void structure but can maintain sufficient strength and flexibility. Therefore, according to the present disclosure, the void layer can be easily and simply applied to various objects.

[0069] The void layer of the present disclosure contains, for example, pulverized porous gel, and the pulverized particles are chemically bonded together, as described below. In the void layer of the present disclosure, the form of chemical bonding (chemical bonding) between the pulverized particles is not particularly limited, and specific examples of the chemical bonding include cross-linking. Note that the method for chemically bonding the pulverized particles together is, for example, as described in detail in the method for manufacturing the void layer described above.

[0070] The crosslinked bond is, for example, a siloxane bond. Examples of the siloxane bond include the T2 bond, T3 bond, and T4 bond shown below. When the silicone porous body of the present disclosure has a siloxane bond, it may have, for example, any one type of bond, any two types of bonds, or all three types of bonds. The higher the ratio of T2 and T3 among the siloxane bonds, the more flexible the gel will be and the inherent properties of the gel can be expected, but the film strength will be weaker. On the other hand, if the ratio of T4 among the siloxane bonds is high, the film strength will be easily achieved, but the pore size will be small and the flexibility will be weaker. For this reason, it is preferable to change the ratios of T2, T3, and T4 depending on the application, for example.

[0071]

[0072] When the void layer of the present disclosure has the siloxane bond, the ratio of T2, T3, and T4, when expressed relatively with T2 set to "1," is, for example, T2:T3:T4=1:[1-100]:[0-50], 1:[1-80]:[1-40], or 1:[5-60]:[1-30].

[0073] In addition, the porous layer of the present disclosure preferably contains silicon atoms that are siloxane-bonded. Specifically, the proportion of unbonded silicon atoms (i.e., residual silanols) among all silicon atoms contained in the porous silicone body is, for example, less than 50%, 30% or less, or 15% or less.

[0074] Furthermore, as described above, the void layer of the present disclosure may be, for example, substantially free of a fluorine compound. By making the void layer substantially free of a fluorine compound, for example, penetration of a pressure-sensitive adhesive or adhesive into the voids of the void layer is further suppressed, and as a result, an increase in the refractive index after the heat durability test is further suppressed.

[0075] The void layer of the present disclosure has, for example, a pore structure. In the present disclosure, the void size of the pores refers to the diameter of the major axis of the voids (pores) out of the diameter of the major axis and the diameter of the minor axis. The pore size is, for example, 5 nm to 50 nm. The void size has a lower limit of, for example, 5 nm or more, 10 nm or more, or 20 nm or more, and an upper limit of, 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 depending on the application of the void structure, and therefore, it is necessary to adjust the void size to the desired size depending on, for example, the purpose. The void size can be evaluated, for example, by the following method.

[0076] (Cross-sectional SEM observation of the void layer) In the present disclosure, the morphology of the void layer can be observed and analyzed using a scanning electron microscope (SEM). Specifically, for example, the void layer is subjected to FIB processing (acceleration voltage: 30 kV) under cooling, and a cross-sectional electron image can be obtained from the obtained cross-sectional sample using an FIB-SEM (manufactured by FEI: product name Helios NanoLab 600, acceleration voltage: 1 kV) at an observation magnification of 100,000 times.

[0077] (Evaluation of pore size) In the present disclosure, the pore size can be quantified by the BET test method. Specifically, 0.1 g of a sample (porous layer of the present disclosure) is placed into the capillary of a pore distribution / specific surface area measuring device (BELLSORP MINI / trade name of Microtrack Bell Co.), and then dried under reduced pressure at room temperature for 24 hours to degas the gas in the pore structure. Then, nitrogen gas is adsorbed onto the sample, and a BET plot, a BJH plot, and an adsorption isotherm are plotted to determine the pore distribution. This allows the pore size to be evaluated.

[0078] The void layer of the present disclosure may have, for example, a pore structure (porous structure) as described above, and may be, for example, an open-cell structure in which the pore structure is continuous. The open-cell structure means, for example, that the pore structure in the void layer is connected three-dimensionally, and the internal voids of the pore structure are continuous. When a porous body has an open-cell structure, it is possible to increase the porosity in the bulk, but when closed-cell particles such as hollow silica are used, an open-cell structure cannot be formed. In contrast, the void layer of the present disclosure has a three-dimensional dendritic structure in which the sol particles (pulverized porous gel forming the sol) have a three-dimensional dendritic structure, and the dendritic particles settle and deposit in the coating film (coated film of the sol containing the pulverized porous gel), thereby easily forming an open-cell structure. Furthermore, the void layer of the present disclosure preferably has a monolithic structure in which the open-cell structure has a plurality of pore distributions. The monolith structure refers to, for example, a structure in which nano-sized fine voids exist, and a hierarchical structure in which the nano-voids exist as an open-cell structure. When forming the monolith structure, for example, it is possible to achieve both membrane strength with fine voids and high porosity with coarse open-cell voids. To form such a monolith structure, for example, it is important to first control the pore distribution of the pore structure to be generated in the porous gel prior to pulverization into the pulverized material. Furthermore, for example, when pulverizing the porous gel, the particle size distribution of the pulverized material can be controlled to a desired size, thereby forming the monolith structure.

[0079] In the air gap layer of the present disclosure, the haze indicating transparency is not particularly limited, and the lower limit is, for example, 0.1% or more, 0.2% or more, or 0.3% or more, and the upper limit is, for example, 10% or less, 5% or less, or 3% or less, and the range is, for example, 0.1 to 10%, 0.2 to 5%, or 0.3 to 3%.

[0080] The haze can be measured, for example, by the following method.

[0081] (Evaluation of Haze) The porous layer (porous layer of the present disclosure) is cut to a size of 50 mm x 50 mm, and the cut piece is set in a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.) to measure the haze. The haze value is calculated using the following formula: Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] x 100 (%)

[0082] The refractive index of the medium is generally defined as the ratio between the propagation speed of the wavefront of light in a vacuum and the propagation speed in the medium. The refractive index of the air-gap layer of the present disclosure 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, or 1.15 or less, and its lower limit is, for example, 1.05 or more, 1.06 or more, or 1.07 or more, and its range is, for example, 1.05 or more and 1.3 or less, 1.05 or more and 1.3 or less, 1.05 or more and 1.25 or less, 1.06 or more and 1.2 or less, or 1.07 or more and 1.15 or less.

[0083] In the present disclosure, unless otherwise specified, the refractive index refers to a refractive index measured at a wavelength of 550 nm. The method for measuring the refractive index is not particularly limited, and can be measured, for example, by the following method.

[0084] (Evaluation of refractive index) A laminate sample is prepared by laminating an adhesive onto the void layer. A prism of a prism coupler (manufactured by Meritricon) is attached to the substrate side of the sample, and the total reflection critical angle is measured using a laser. The refractive index is calculated from the critical angle.

[0085] The thickness of the air gap layer of the present disclosure is not particularly limited, and the lower limit is, for example, 0.05 μm or more, 0.1 μm or more, and the upper limit is, for example, 1000 μm or less, 100 μm or less, and the range is, for example, 0.05 to 1000 μm, 0.1 to 100 μm.

[0086] The form of the porous layer of the present disclosure is not particularly limited, and may be, for example, a film shape or a block shape.

[0087] The method for producing the porous layer of the present disclosure is not particularly limited, but can be, for example, the method described in WO 2019 / 065999 and WO 2019 / 065803, the disclosures of which are incorporated herein by reference.

[0088] [3. Pressure-sensitive adhesive coating liquid] In the laminate of the present disclosure, the pressure-sensitive adhesive layer can be formed, for example, using a pressure-sensitive adhesive coating liquid, as described above. In the present disclosure, the terms "pressure-sensitive adhesive" and "adhesive" are not necessarily clearly distinguishable, as will be described later. In the present disclosure, the term "pressure-sensitive adhesive" includes both "pressure-sensitive adhesive" and "adhesive" unless otherwise specified. The pressure-sensitive adhesive coating liquid may be, for example, a pressure-sensitive adhesive coating liquid containing the (meth)acrylic polymer, or may be, for example, a pressure-sensitive adhesive coating liquid containing the organic silyl group-containing compound, or may further contain, for example, a crosslinking agent (e.g., an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent), or may further contain, for example, a monomer having one or two reactive double bonds per molecule and an organic peroxide. The pressure-sensitive adhesive coating liquid is not particularly limited, but examples are as shown below.

[0089] The pressure-sensitive adhesive coating liquid may be, for example, a (meth)acrylic polymer containing, as monomer components, 3 to 20% by mass of a heterocycle-containing acrylic monomer, a (meth)acrylic polymer having a polymerizable functional group, 0.5 to 5% by mass of (meth)acrylic acid, 0.05 to 2% by mass of a hydroxyalkyl (meth)acrylate, and 83 to 96.45% by mass of an alkyl (meth)acrylate, and this (meth)acrylic polymer may be used as a base polymer.

[0090] As the heterocycle-containing acrylic monomer, for example, one having a polymerizable functional group and a heterocycle can be used without particular limitation. Examples of the polymerizable functional group include a (meth)acryloyl group and a vinyl ether group. Among these, a (meth)acryloyl group is preferred. Examples of the heterocycle include a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring. Examples of the heterocycle-containing acrylic monomer include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine. Among these, N-acryloylmorpholine is preferred. The heterocycle-containing acrylic monomer can improve both the heat resistance and the moisture resistance of the pressure-sensitive adhesive layer (adhesive layer) when the layer is thinned. Hereinafter, N-acryloylmorpholine may be referred to as "ACMO."

[0091] In addition, the heterocycle-containing acrylic monomer is preferred in that it can improve the adhesive strength of the pressure-sensitive adhesive layer (tacky-adhesive layer) to the optical film, particularly in that it improves the adhesive strength to a cyclic polyolefin such as a norbornene-based resin, and is suitable when a cyclic polyolefin is used as the optical film.

[0092] The heterocycle-containing 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 the heterocycle-containing acrylic monomer may be, for example, 4 to 19% by mass or 6 to 18% by mass. The proportion of the heterocycle-containing acrylic monomer is preferably not less than the above-mentioned range from the viewpoint of heat resistance and moisture resistance when the pressure-sensitive adhesive layer (adhesive layer) is thinned. Furthermore, the proportion of the heterocycle-containing acrylic monomer is preferably not more than the above-mentioned range from the viewpoint of moisture resistance when the pressure-sensitive adhesive layer (adhesive layer) is thinned. Furthermore, the proportion of the heterocycle-containing acrylic monomer is preferably not more than the above-mentioned range from the viewpoint of improving the adhesion of the pressure-sensitive adhesive layer (adhesive layer). Furthermore, the proportion of the heterocycle-containing acrylic monomer is preferably not more than the above-mentioned range from the viewpoint of adhesive strength.

[0093] As the (meth)acrylic acid, acrylic acid is particularly preferred.

[0094] (Meth)acrylic acid is used, for example, in a proportion of 0.5 to 20% 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, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, or 3% by mass or more, and may be, for example, 20% by mass or less, 15% by mass or less, 13% by mass or less, or 10% by mass or less. The proportion of (meth)acrylic acid is preferably not less than the above-mentioned range from the viewpoint of heat resistance when the pressure-sensitive adhesive layer (adhesive layer) is thinned. Furthermore, the proportion of (meth)acrylic acid is preferably not more than the above-mentioned range from the viewpoint of heat resistance and moisture resistance when the pressure-sensitive adhesive layer (adhesive layer) is thinned. Furthermore, the proportion of (meth)acrylic acid is preferably not more than the above-mentioned range from the viewpoint of adhesive strength.

[0095] The hydroxyalkyl (meth)acrylate may be, for example, one having a polymerizable functional group and a hydroxyl group, and is not particularly limited. Suitable examples of the hydroxyalkyl (meth)acrylate include 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.

[0096] The hydroxyalkyl (meth)acrylate is used, for example, in a proportion of 0.05 to 2 mass% relative to the total amount of monomer components forming the (meth)acrylic polymer. The proportion of the hydroxyalkyl (meth)acrylate may be, for example, 0.075 to 1.5 mass% or 0.1 to 1 mass%. From the viewpoint of heat resistance when the pressure-sensitive adhesive layer (adhesive layer) is thinned, the proportion of the hydroxyalkyl (meth)acrylate is preferably not less than the above-mentioned range. Furthermore, from the viewpoint of heat resistance and moisture resistance when the pressure-sensitive adhesive layer (adhesive layer) is thinned, the proportion of the hydroxyalkyl (meth)acrylate is preferably not more than the above-mentioned range. Furthermore, from the viewpoint of adhesive strength, the proportion of the hydroxyalkyl (meth)acrylate is preferably not more than the above-mentioned range.

[0097] The alkyl (meth)acrylate may have, for example, an average carbon number of about 1 to 12 in the alkyl group of the alkyl (meth)acrylate. (Meth)acrylate refers to acrylate and / or methacrylate, and (meth) in the present disclosure has the same meaning. Specific examples of alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, and lauryl (meth)acrylate, which can be used alone or in combination. Among these, alkyl (meth)acrylates in which the alkyl group has 1 to 9 carbon atoms are preferred.

[0098] The alkyl (meth)acrylate is used in an amount of, for example, 83 to 96.45 mass % based on the total amount of the monomer components forming the (meth)acrylic polymer. The alkyl (meth)acrylate is usually the remainder other than the heterocycle-containing acrylic monomer, (meth)acrylic acid, and hydroxyalkyl (meth)acrylate.

[0099] As the monomer component for forming the (meth)acrylic polymer, for example, in addition to the above-mentioned monomers, any other monomers can be used in an amount of 10% or less of the total amount of monomers, as long as the object of the present disclosure is not impaired.

[0100] Examples of the optional monomer 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 styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid; and phosphoric acid group-containing monomers such as 2-hydroxyethylacryloylphosphate. Examples of nitrogen-containing vinyl monomers include maleimide, N-cyclohexylmaleimide, and 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, and N-methylolpropane(meth)acrylamide (N-substituted) amide monomers; aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, and (meth) Examples include alkylaminoalkyl (meth)acrylate monomers such as N,N-dimethylaminoethyl acrylate, t-butylaminoethyl (meth)acrylate, and 3-(3-pyridyl)propyl (meth)acrylate; alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; and succinimide monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide.

[0101] Furthermore, vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic 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 ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate can also be used.

[0102] Further, copolymerizable monomers other than those mentioned above include silicon atom-containing silane monomers, etc. 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.

[0103] As described above, the (meth)acrylic polymer used in the adhesive layer in the laminate of the present disclosure may have a weight-average molecular weight (Mw) of, for example, 1.5 million to 4 million. The weight-average molecular weight may be, for example, 1.8 million to 3.8 million, for example, 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 pressure-sensitive adhesive layer (adhesive layer) is thinned, the weight-average molecular weight is preferably not smaller than the above range. Furthermore, from the viewpoint of durability, lamination ability, and adhesive strength when the pressure-sensitive adhesive layer is thinned, the weight-average molecular weight is preferably not larger than the above range. In the present disclosure, the weight-average molecular weight refers to a value measured, for example, by GPC (gel permeation chromatography) and calculated in polystyrene equivalent.

[0104] The method for producing such a (meth)acrylic polymer is not particularly limited, and can be appropriately selected from known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, various radical polymerizations, etc. The obtained (meth)acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, etc.

[0105] In the solution polymerization, for example, ethyl acetate, toluene, etc. are used as a polymerization solvent. In a specific example of solution polymerization, the reaction is carried out under reaction conditions of adding a polymerization initiator under a stream of an inert gas such as nitrogen, at about 50 to 70°C, for example, for about 1 to 30 hours.

[0106] The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization are not particularly limited and can be appropriately selected and used. The weight-average molecular weight of the (meth)acrylic polymer can be controlled by the amounts of the polymerization initiator and chain transfer agent used and the reaction conditions, and the amounts used are appropriately adjusted depending on the types of these.

[0107] Examples of the polymerization initiator include azo 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 (VA-057, manufactured by Wako Pure Chemical Industries, Ltd.); persulfates such as potassium persulfate and ammonium persulfate; di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxy Examples of the initiator include, but are not limited to, peroxide initiators such as dicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butyl peroxyisobutyrate, 1,1-di(t-hexylperoxy)cyclohexane, t-butyl hydroperoxide, and hydrogen peroxide; and redox initiators that combine a peroxide with a reducing agent, such as a combination of a persulfate and sodium hydrogen sulfite, or a combination of a peroxide and sodium ascorbate.

[0108] The polymerization initiators may be used alone or in combination of two or more. The total content of the polymerization initiators 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 the monomer.

[0109] In addition, when a (meth)acrylic polymer having the above weight average molecular weight is produced using, for example, 2,2′-azobisisobutyronitrile as a polymerization initiator, the amount of the 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 relative to 100 parts by mass of the total amount of the monomer components.

[0110] 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 alone or in combination of two or more. The total amount 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 the monomer components.

[0111] Furthermore, examples of emulsifiers used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether ammonium sulfate, and polyoxyethylene alkyl phenyl ether sodium sulfate, and nonionic emulsifiers such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, and polyoxyethylene-polyoxypropylene block polymers. These emulsifiers may be used alone or in combination of two or more.

[0112] Furthermore, as reactive emulsifiers, emulsifiers into which a radically polymerizable functional group such as a propenyl group or an allyl ether group has been introduced include, for example, Aqualon HS-10, HS-20, KH-10, BC-05, BC-10, and BC-20 (all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and Adeka Reasoap SE10N (manufactured by Asahi Denka Kogyo Co., Ltd.). Reactive emulsifiers are preferred because they are incorporated into the polymer chain after polymerization, improving water resistance. The amount of emulsifier used is 0.3 to 5 parts by mass, and more preferably 0.5 to 1 part by mass, based on 100 parts by mass of the total amount of monomer components, in terms of polymerization stability and mechanical stability.

[0113]

[0044] The content of the (meth)acrylic polymer in the pressure-sensitive adhesive coating liquid is not particularly limited, and may be, for example, 3% by mass or more, or 5% by mass or more, and may be, for example, 30% by mass or less, 20% by mass or less, or 10% by mass or less, relative to the total mass of the pressure-sensitive adhesive coating liquid.

[0114] Furthermore, the pressure-sensitive 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 grafting 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 may be, for example, the same as the monomers exemplified as the monomer components 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 heterocycle-containing monomers are preferred because they can simultaneously achieve a high elastic modulus within an appropriate range and a reduced amount of semi-high molecular weight polymer.

[0115]

[0044] When the pressure-sensitive adhesive coating liquid contains the monomer having one or two reactive double bonds in one molecule, the content thereof is not particularly limited, and may be, for example, 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more, and may be, for example, 30% by mass or less, 20% by mass or less, or 10% by mass or less, relative to the total mass of the (meth)acrylic polymer in the pressure-sensitive adhesive coating liquid.

[0116] In the laminate of the present disclosure, the adhesive layer is formed from an adhesive containing a (meth)acrylic polymer and an organic silyl group-containing compound, as described above. As described above, the organic silyl group of the organic silyl group-containing compound contained in the adhesive layer may or may not contain a carbon-silicon bond. That is, the organic silyl group of the organic silyl group-containing compound contained in the adhesive layer may or may not contain a carbon-silicon bond. Examples of organic silyl groups in the organic silyl group-containing compound are shown in the following chemical formulas (1) to (4). In the following chemical formulas (1) to (4), R １ , R ２ and R ３are each, for example, a linear or branched alkyl group, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, etc., and may be the same or different. The organic silyl group in the organic silyl group-containing compound is not limited to the following chemical formulas (1) to (4) and may be any.

[0117]

[0118] In the laminate of the present disclosure, by including an organosilyl group-containing compound in the adhesive coating liquid, the durability of the adhesive layer formed from the adhesive coating liquid can be improved, and the adhesive layer can be particularly excellent in durability under humid environments and can maintain high durability even after being left for a long period of time. Here, in the present disclosure, the adhesive coating liquid may be, for example, a pressure-sensitive adhesive (pressure-sensitive adhesive composition). The adhesive layer may be, for example, a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive (pressure-sensitive adhesive composition). In the present disclosure, the weight-average molecular weight of the organosilyl group-containing compound may be, for example, 50 or more, 70 or more, 100 or more, or 150 or more, and may be, for example, 30,000 or less, 20,000 or less, 10,000 or less, or 5,000 or less.

[0119] The organic silyl group-containing compound may be, for example, a silane coupling agent, for example, a silane coupling agent having two or more alkoxysilyl groups in the molecule. Specific examples of the organic silyl group-containing compound having two or more alkoxysilyl groups in the molecule 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-isocyanatepropyltriethoxysilane. These coupling agents are preferred because they are less likely to volatilize and have multiple alkoxysilyl groups, making them effective in improving durability. Examples of such coupling agents include KBM-802, X41-1056, and KR-470, trade names of Shin-Etsu Chemical Co., Ltd.

[0120] The organic silyl group-containing compound may or may not contain an alkoxysilyl group. The alkoxysilyl group is not particularly limited, but examples include groups represented by any of the chemical formulas (2) to (4). The number of alkoxysilyl groups in the organic silyl group-containing compound is not particularly limited, but preferably two or more per molecule. Furthermore, the amount of alkoxy groups in the organic silyl group-containing compound is preferably, for example, 10 to 60 mass%, more preferably 20 to 50 mass%, and even more preferably 20 to 40 mass% in the organic silyl group-containing compound. 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, with methoxy being more preferred. It is also preferable for one molecule to contain both methoxy and ethoxy.

[0121] The organic silyl group-containing compound may contain, for example, an epoxy group or an acid anhydride group.

[0122] The organic silyl group-containing compound may be used alone or in a mixture of two or more. As described above, the total content of the organic silyl group-containing compound is 5.0 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer, but may be, for example, 4.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, or 1.0 parts by mass or less, and may be, for example, 0.01 parts by mass or more, 0.02 parts by mass or more, 0.03 parts by mass or more, 0.05 parts by mass or more, or 0.1 parts by mass or more. By setting the content within the above range, the increase in the initial refractive index can be suppressed, and further, the change in refractive index after the heat durability test can be reduced.

[0123] The presence of an organosilyl group-containing compound in the adhesive layer of the laminate of the present disclosure can be confirmed, for example, by TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry). Specifically, by measuring the adhesive layer of the laminate of the present disclosure by TOF-SIMS, it can be confirmed whether or not the adhesive layer contains a specific functional group (e.g., a trimethoxysiloxy group, a triethoxysiloxy group, a dimethoxymethylsilyl group, etc.), thereby confirming whether or not the adhesive layer contains an organosilyl group-containing compound. TOF-SIMS measurement can be performed, for example, under the following measurement conditions.

[0124] [Sample Preparation and Measurement Method] The adhesive layer of the laminate of the present disclosure is attached to a substrate made of an ITO (indium tin oxide) vapor-deposited glass plate, and after autoclaving (50°C, 5 atm x 15 min), the adhesive layer is peeled off from the substrate. TOF-SIMS measurement is performed on the substrate surface after peeling. [Apparatus and Measurement Conditions] TOF SIMS apparatus: ION TO TOF SIMS5 (product name of Hitachi High-Tech Corporation) Irradiated primary ions: Bi ３ ２＋Primary ion acceleration voltage: 25 kV Measurement area: 200 μm square *A neutralizing gun for charge correction is used for measuring alkali-free glass.

[0125] The organic silyl group-containing compound may or may not contain, for example, a monomeric silane coupling agent, but preferably contains a monomeric silane coupling agent. In the present disclosure, when the adhesive layer contains a monomeric silane coupling agent, the initial refractive index of the void layer can be lowered compared to when, for example, an oligomeric silane coupling agent is used instead of the monomeric silane coupling agent.

[0126] The monomeric silane coupling agent is not particularly limited, but examples thereof include amino group-containing silane coupling agents such as the above-mentioned 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-isocyanatepropyltriethoxysilane.

[0127] The organic silyl group-containing compound may or may not contain a silane coupling agent other than the monomeric silane coupling agent. Examples of the silane coupling agent other than the monomeric silane coupling agent include an oligomeric silane coupling agent.

[0128] The weight-average molecular weight (Mw) of the oligomeric silane coupling agent may be, for example, 300 or more. By including an oligomeric silane coupling agent in the adhesive coating liquid, the laminate of the present invention can improve the durability of the adhesive layer formed from the adhesive coating liquid, particularly providing excellent durability in a humidified environment and maintaining high durability even after long-term storage. In the present invention, the adhesive coating liquid may be, for example, a pressure-sensitive adhesive (adhesive composition). The adhesive layer may be, for example, a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive (adhesive composition). Here, the term "oligomeric" refers to a polymer of a monomer having a dimer (degree of polymerization) of 2 or more and less than 100 (degree of polymerization). The weight-average molecular weight of the oligomeric silane coupling agent is preferably about 300 to 30,000. In the present invention, the degree of polymerization of the oligomeric silane coupling agent is not particularly limited.

[0129] The oligomeric silane coupling agent may be, for example, a silane coupling agent having two or more alkoxysilyl groups in the molecule. Specific 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 likely to volatilize and have multiple alkoxysilyl groups, making them effective in improving durability.

[0130] The number of alkoxysilyl groups in the oligomeric silane coupling agent is not particularly limited, but preferably two or more per molecule. The amount of alkoxy groups in the oligomeric silane coupling agent is preferably, for example, 10 to 60 mass%, more preferably 20 to 50 mass%, and even more preferably 20 to 40 mass% in the silane coupling agent. 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, with methoxy being more preferred. It is also preferable for one molecule to contain both methoxy and ethoxy.

[0131] As mentioned above, the oligomeric silane coupling agent may contain an epoxy group. The epoxy equivalent of the oligomeric silane coupling agent is, for example, preferably 1000 g / mol or less, more preferably 500 g / mol or less, and 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.

[0132] The oligomeric silane coupling agent preferably contains an epoxy group, but may also contain an acid anhydride group. By using an oligomeric silane coupling agent containing an acid anhydride group, the change in refractive index after the heat durability test can be reduced compared to when no silane coupling agent is used, and the adhesive strength between the adhesive layer and the low refractive index layer after the heat durability test can be improved.

[0133] The oligomeric silane coupling agent may be used alone or in combination of two or more. The total content of the oligomeric silane coupling agent may be, for example, 1 part by mass or less, preferably 0.2 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer. By setting the content within the above range, it is possible to suppress an increase in the initial refractive index and further reduce the amount of change in the refractive index after the heat durability test.

[0134] Furthermore, the pressure-sensitive adhesive coating liquid may contain, for example, a crosslinking agent, as described above. The crosslinking agent is not particularly limited, but examples thereof include isocyanate-based crosslinking agents and epoxy-based crosslinking agents. The isocyanate-based crosslinking agent is not particularly limited, but examples thereof 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 thereof 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-xylylenediamine.

[0135] More specifically, examples of the isocyanate-based crosslinking agent include 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, trimethylolpropane / tolylene diisocyanate trimer adduct (Japan), Examples of suitable polyisocyanates include isocyanate adducts such as a trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L), a trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate HL), and an isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate HX); polyether polyisocyanates; polyester polyisocyanates; and adducts of these with various polyols; and polyisocyanates multifunctionalized with isocyanurate bonds, biuret bonds, allophanate bonds, etc.

[0136] More specific examples of the epoxy-based crosslinking agent include "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Inc., "Tetrad X" manufactured by Mitsubishi Gas Chemical Company, Inc., and "S-610" manufactured by Synasia.

[0137] The crosslinking agents (e.g., isocyanate-based crosslinking agents, epoxy-based crosslinking agents) may be used alone or in combination of two or more. The total content of the crosslinking agent 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 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 strength, while 2 parts by mass or less is preferred 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 residual rate, while 0.5 parts by mass or less is preferred from the viewpoint of peel durability.

[0138] In the pressure-sensitive adhesive coating liquid, the crosslinking agent may consist solely of an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent, or may further contain other crosslinking agents besides the isocyanate-based crosslinking agent or the epoxy-based crosslinking agent. Examples of the 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. Preferred organic crosslinking agents are isocyanate-based crosslinking agents and epoxy-based crosslinking agents. Polyfunctional metal chelates are those in which a polyvalent metal atom 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, and Ti. The atom in the organic compound that forms a covalent bond or a coordinate bond may be an oxygen atom, and the organic compound may be an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, a ketone compound, or the like.

[0139] The adhesive coating liquid may or may not contain, for example, an organic peroxide. The organic peroxide is not particularly limited, but examples thereof 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-butyl hydroperoxide, and the like. One type of organic peroxide may be used alone, or two or more types may be used in combination.

[0140]

[0044] When the pressure-sensitive adhesive coating liquid contains the organic peroxide, the content thereof is not particularly limited, and 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 pressure-sensitive adhesive coating liquid, and may be, for example, 20% by mass or less, 10% by mass or less, 8% by mass or less, or 6% by mass or less.

[0141] The pressure-sensitive adhesive coating liquid may further contain a solvent, etc. The solvent is not particularly limited, and for example, the polymerization solvent used in the solution polymerization in producing the (meth)acrylic polymer may be used as is.

[0142] Furthermore, the pressure-sensitive adhesive coating liquid may contain, as necessary, tackifiers, plasticizers, fillers such as glass fibers, glass beads, metal powders, and other inorganic powders, pigments, colorants, fillers, antioxidants, ultraviolet absorbers, silane coupling agents, etc., and various other additives may also be used appropriately within the scope of the object of the present disclosure. Furthermore, the pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) may contain fine particles and exhibit light diffusing properties.

[0143] The adhesive layer of the laminate of the present disclosure can be formed using the adhesive coating liquid, for example, by the method described below. The adhesive layer may have a weight-average molecular weight of 30,000 to 600,000 for the sol component of the adhesive layer, as measured by gel permeation chromatography. Furthermore, the content of low-molecular-weight components having a molecular weight of 10,000 or less in the sol component of the adhesive layer may be 20% by weight (mass%) or less for the molecular weight of the adhesive layer, as measured by gel permeation chromatography. By setting the weight-average molecular weight of the sol component or the content of low-molecular-weight components having a molecular weight of 10,000 or less in the sol component within the specified range, the adhesive is further less likely to penetrate into the voids in the void layer. The weight-average molecular weight of the sol component may be, for example, 50,000 or more, or may be, for example, 550,000 or less or 500,000 or less, or may be, for example, 50,000 to 550,000 or 60,000 to 500,000. Furthermore, the content (proportion) of components having a molecular weight of 10,000 or less in the sol content may be, for example, 20% by mass or less, as described above, or, for example, 15% by mass or less, or 10% by mass or less, relative to the total amount (100% by mass) of the sol content. The lower limit of the content (proportion) of components having a molecular weight of 10,000 or less in the sol content is not particularly limited, but may be, for example, 0% by mass or more or greater than 0% by mass, and may be, for example, 3% by mass or more. The content (proportion) of components having a molecular weight of 10,000 or less in the sol content may be, for example, 3 to 15% by mass or 3 to 10% by mass.

[0144] [4. Manufacturing method of laminate] The manufacturing method of the laminate of the present disclosure is not particularly limited, and can be performed, for example, by the manufacturing method described below. However, the following description is an example and does not limit the present disclosure in any way. The void layer of the present disclosure is not particularly limited, and is, for example, as described above. Furthermore, as described above, the manufacturing method of the void layer of the present disclosure is also not particularly limited, and can be manufactured, for example, by the methods described in WO 2019 / 065999 and WO 2019 / 065803.

[0145] The method for producing a laminate of the present disclosure may include, for example, a pressure-sensitive adhesive layer production step of producing the pressure-sensitive adhesive layer and a lamination step of bonding the pressure-sensitive adhesive layer to the void layer. The method for producing the pressure-sensitive adhesive layer may include, for example, a pressure-sensitive adhesive coating liquid application step of applying the pressure-sensitive adhesive coating liquid to a substrate and a heat-drying step of heating and drying the substrate coated with the pressure-sensitive adhesive coating liquid. For example, the pressure-sensitive adhesive layer may be formed on the void layer of the present disclosure by laminating the pressure-sensitive adhesive layer side of a pressure-sensitive adhesive tape or the like having the pressure-sensitive adhesive layer of the present disclosure laminated on a substrate onto the void layer of the present disclosure. In this case, the substrate of the pressure-sensitive adhesive tape or the like may be left attached as is or may be peeled off from the pressure-sensitive adhesive layer. In particular, peeling off the substrate to produce a void layer-containing pressure-sensitive adhesive sheet that does not have a substrate (substrate-less) can significantly reduce the thickness and suppress an increase in the thickness of a device or the like. In the present disclosure, the terms "pressure-sensitive adhesive" and "pressure-sensitive adhesive layer" refer to, for example, an agent or layer intended to be removably attached to an adherend. In the present disclosure, the terms "adhesive" and "adhesive layer" refer to, for example, an agent or layer that is not intended to be removably attached to an adherend. However, in the present disclosure, a "pressure-sensitive adhesive" and an "adhesive" are not necessarily clearly distinguishable from each other, and a "pressure-sensitive adhesive layer" and an "adhesive layer" are not necessarily clearly distinguishable from each other. In the present disclosure, the pressure-sensitive adhesive layer can be produced, for example, using the pressure-sensitive adhesive coating liquid as described above.

[0146] The adhesive layer production step can be performed, for example, as follows. First, the adhesive coating liquid is produced by a mixing step of mixing all components of the adhesive coating liquid. The adhesive coating liquid may, for example, contain the (meth)acrylic polymer as described above, and may further contain, for example, a crosslinking agent (e.g., an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent). The adhesive coating liquid may, for example, contain the (meth)acrylic polymer, a monomer having one or two reactive double bonds per molecule, and an organic peroxide. In this case, if the adhesive coating liquid contains other components, the other components may also be mixed together. For example, the polymerization solvent used in producing the (meth)acrylic polymer may be mixed directly as a component of the adhesive coating liquid without removing it. The production method of the adhesive coating liquid may, but need not, include other steps other than the mixing step, and may simply involve mixing all components of the adhesive coating liquid in the mixing step.

[0147] Next, the adhesive coating liquid is applied to a substrate (adhesive coating liquid application step). The substrate is not particularly limited and may be, for example, a substrate such as a film. Examples of suitable substrates include, but are not limited to, substrates made of thermoplastic resins, glass substrates, inorganic substrates such as silicon, plastics molded from thermosetting resins, semiconductor elements, and carbon fiber materials such as carbon nanotubes. Examples of the substrate include, but are not limited to, films and plates. Examples of thermoplastic resins include polyethylene terephthalate (PET), acrylic, cellulose acetate propionate (CAP), cycloolefin polymer (COP), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polyethylene (PE), and polypropylene (PP). In the adhesive coating liquid application step, the thickness of the adhesive coating liquid is not particularly limited and may be adjusted appropriately so that the adhesive layer has a predetermined thickness after drying. The thickness of the adhesive layer after drying is also not particularly limited and may be, for example, as described below.

[0148] Next, the substrate coated with the adhesive coating liquid is heated and dried (heat drying step). In this heat drying step, the heat drying temperature is not particularly limited, but may be, for example, 50°C or higher, 80°C or higher, 100°C or higher, or 155°C or higher, and may be, for example, 200°C or lower, 180°C or lower, or 160°C or lower. The heat drying time is not particularly limited, but may be, for example, 0.5 minutes or higher, 1 minute or higher, or 3 minutes or higher, and may be, for example, 60 minutes or lower, 30 minutes or lower, 20 minutes or lower, or 10 minutes or lower. In this heat drying step, for example, a crosslinking reaction and graft polymerization occur between the (meth)acrylic polymer and the crosslinking agent. This reduces the amount of semi-high molecular weight polymer present in the adhesive coating liquid, as described above, making it difficult for the adhesive layer to penetrate into the voids of the void layer. In this manner, the adhesive layer used in the laminate of the present disclosure can be produced.

[0149] Next, the adhesive layer is bonded to the void layer (lamination 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 disclosure is laminated on a substrate may be bonded to the void layer of the present disclosure, thereby forming the adhesive layer on the void layer of the present disclosure. In this manner, the laminate of the present disclosure can be produced.

[0150] In the method for producing a laminate according to the present disclosure, for example, a heating step may be further performed after the laminating step, in which the adhesive layer and the void layer are heated. Hereinafter, this heating step may be referred to as an "aging step." In the heating step (aging step), the heating temperature is not particularly limited, but may be, for example, 40°C or higher, 45°C or higher, or 50°C or higher, and may be, for example, 80°C or lower, 70°C or lower, 60°C or lower, or 55°C or lower. The heating time is not particularly limited, but may be, for example, 1 minute or longer, 10 minutes or longer, 60 minutes or longer, or 1800 minutes or longer, and may be, for example, 3000 minutes or shorter, 2800 minutes or shorter, 2500 minutes or shorter, or 2000 minutes or shorter. In this aging step, for example, the intermediate layer is formed by the union of the void layer and the adhesive layer. As described above, the intermediate layer acts as a stopper, thereby suppressing a decrease in porosity due to the voids in the void layer being filled with the adhesive. The fusion of the void layer and the adhesive layer may be such that the adhesive layer is embedded in the voids of the void layer and chemically bonded to it, or such that the adhesive layer is embedded in the voids of the void layer.

[0151] The adhesive layer can protect the void layer from physical damage (particularly scratches). The adhesive layer is preferably, but not particularly limited to, one with excellent pressure resistance so that the void layer does not collapse even in a void-layer-containing adhesive sheet that does not have a substrate (substrate-less). The thickness of the adhesive layer is not particularly limited, but is, for example, 0.1 to 100 μm, 5 to 50 μm, 10 to 30 μm, or 12 to 25 μm.

[0152] The laminate of the present disclosure thus obtained may be further laminated with another film (layer) to form a laminate structure including the void layer (porous structure), as described above. In this case, in the laminate structure, each component may be laminated via, for example, the adhesive layer (adhesive or pressure-sensitive adhesive).

[0153] The lamination of the components may be carried out by continuous processing (so-called roll-to-roll processing, etc.) using a long film, for example, because this is more efficient. When the substrate is a molded product, element, or the like, the components may be laminated by batch processing.

[0154] Hereinafter, a method for forming the laminate of the present disclosure on a substrate (resin film) will be described with respect to a continuous processing step, taking the laminate 10d shown in Fig. 3(a) as an example. Note that the film-forming method described below is merely an example and is not limited thereto.

[0155] The substrate may be the resin film described above. In this case, the void layer of the present disclosure can be obtained by forming the void layer on the substrate. Alternatively, the void layer of the present disclosure can be obtained by forming the void layer on the substrate and then laminating the void layer on the resin film described above in the description of the void layer of the present disclosure.

[0156] 3( a), a method for producing the laminate 10d includes, for example, first forming a void layer 11 on a substrate 14, then forming a tacky-adhesive layer 12 on the void layer 11, and then combining the void layer 11 and the tacky-adhesive layer 12 to form an intermediate layer 13. More specifically, this production method includes, for example, a coating step (1) of coating a sol particle liquid of a pulverized gel compound onto a substrate (resin film) 14 to form a coating film, a drying step (2) of drying the sol particle liquid to form a dried coating film, a chemical treatment step (e.g., a crosslinking step) (3) of chemically treating the coating film (e.g., a crosslinking treatment) to form the void layer 11, a lamination step (4) of laminating the tacky-adhesive layer 12 onto the void layer 11, and an intermediate layer formation step (5) of reacting the void layer 11 with the tacky-adhesive layer 12 to form the intermediate layer 13. The method for producing the sol particle liquid of the pulverized gel compound is not particularly limited. Specifically, the sol particle liquid can be produced by the method described in, for example, WO 2019 / 065999 or WO 2019 / 065803. The sol particle liquid can also be produced by the method described in "Reference Example 1" of the Examples of the present application, which will be described later. Although not shown, the method for producing a laminate of the present disclosure also includes a pressure-sensitive adhesive layer production step of producing the pressure-sensitive adhesive layer by the pressure-sensitive adhesive layer production method of the present disclosure, and a lamination step of bonding the pressure-sensitive adhesive layer to the void layer, as described above. The method for producing a pressure-sensitive adhesive layer of the present disclosure also includes a pressure-sensitive adhesive coating liquid application step of applying the pressure-sensitive adhesive coating liquid to a substrate, and a heat-drying step of heat-drying the substrate coated with the pressure-sensitive adhesive coating liquid. The chemical treatment step (crosslinking step) (3) corresponds to the "void layer formation step" of forming a void layer in the laminate of the present disclosure. The intermediate layer formation step (5) corresponds to the heating step (aging step) described above. The intermediate layer forming step (5) (hereinafter sometimes referred to as the "aging step") may also serve as, for example, a step of improving the strength of the void layer 11 (a cross-linking reaction step of causing a cross-linking reaction inside the void layer 11), in which case the void layer 11 changes into a void layer 11 with further improved strength after the intermediate layer forming step (5). However, the present disclosure is not limited to this, and for example, the void layer 11 does not need to change after the intermediate layer forming step (5).Furthermore, as described above, the laminating step (4) may be laminating an adhesive tape having an adhesive layer on a substrate. In FIG. 3( a), the substrate 14 to which the adhesive coating liquid has been applied (i.e., the adhesive layer 12 formed thereon) may be, for example, peeled and removed from the adhesive layer 12, or may be left as is on the adhesive layer 12. By performing the above steps (1) to (5), a laminate film (laminate) can be produced, as shown in FIG. 3( a), in which the void layer 11, the intermediate layer 13, and the adhesive layer 12 are laminated in the above order on the resin film 14. However, the intermediate layer forming step (5) may be omitted, and the laminate produced according to the present disclosure may not include an intermediate layer. Furthermore, the method for producing a laminate according to the present disclosure may or may not include other steps as appropriate. For example, as in the laminate film (laminate) 10d shown in FIG. 3( a), another sheet 14 may be laminated on the adhesive layer 12. Furthermore, the laminated film (laminate) 10d in Figure 3(a) has the adhesive layer 12 provided on only one side of the void layer 11, but the adhesive layer 12 may be provided on both sides of the void layer 11, for example, as in the laminate 10e in Figure 3(b).

[0157] In the coating step (1), the coating method of the sol particle liquid is not particularly limited, and a general coating method can be used. Examples of the coating method include a slot die method, a reverse gravure coating method, a microgravure method (microgravure coating method), a dip method (dip coating method), a spin coating method, a brush coating method, a roll coating method, a flexographic printing method, a wire bar coating method, a spray coating method, an extrusion coating method, a curtain coating method, and a reverse coating method. Among these, from the viewpoints of productivity, smoothness of the coating film, and the like, an extrusion coating method, a curtain coating method, a roll coating method, a microgravure coating method, and the like are preferred. The coating amount of the sol particle liquid is not particularly limited, and can be appropriately set, for example, so that the thickness of the void layer 11 is appropriate. The thickness of the void layer 11 is not particularly limited, and is, for example, as described above.

[0158] In the drying step (2), 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 (a precursor of the void layer). The conditions for the drying treatment are not particularly limited and are as described above.

[0159] Furthermore, in the chemical treatment step (3), the dried coating film containing the catalyst or catalyst generator (e.g., a photoactive catalyst, a photocatalyst generator, a thermally active catalyst, or a thermal catalyst generator) added before coating is irradiated with light or heated to chemically bond (e.g., crosslink) the pulverized materials in the dried coating film to each other, 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.

[0160] On the other hand, although not shown, the adhesive layer of the present disclosure is separately produced by the adhesive layer production step. The adhesive layer production step (the adhesive layer production method of the present disclosure) is, for example, as described above.

[0161] Further, a laminating 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 laminating step (4). For example, when the adhesive is a pressure-sensitive 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 step of drying the adhesive. Furthermore, for example, the heating step may also serve as the intermediate layer forming step (5). The temperature in the heating step is not particularly limited, but is, for example, 70 to 160°C, 80 to 155°C, or 90 to 150°C. The time for the heating step is not particularly limited, but is, for example, 1 to 10 minutes, 1 to 7 minutes, or 2 to 5 minutes.

[0162] Next, examples of the present disclosure will be described, but the present disclosure is not limited to the following examples.

[0163] In the following Reference Examples, Examples, and Comparative Examples, the number of parts (relative amount used) of each substance is in parts by mass (parts by weight) unless otherwise specified. In the following Reference Examples, Examples, and Comparative Examples, a pressure-sensitive adhesive (pressure-sensitive adhesive composition) described below was used as the pressure-sensitive adhesive. In the following Reference Examples, Examples, and Comparative Examples, the term "pressure-sensitive adhesive layer" corresponds to the term "pressure-sensitive adhesive layer." That is, in the following Reference Examples, Examples, and Comparative Examples, the terms "pressure-sensitive adhesive layer" and "pressure-sensitive adhesive layer" have the same meaning unless otherwise specified.

[0164] 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 by the following measurement methods.

[0165] <Method for measuring molecular weight of (meth)acrylic polymer> The weight average molecular weight (Mw) of the (meth)acrylic polymer was calculated from a molecular weight distribution curve measured by gel permeation chromatography (GPC). Analytical device: Waters, Alliance Column: Tosoh Corporation, G7000HXL + GMHXL + GMHXL Column size: each 7.8 mmφ × 30 cm, total 90 cm Column temperature: 40°C Flow rate: 0.8 mL / min Injection volume: 100 μL Eluent: THF (acid added) Detector: differential refractometer (RI) Standard sample: polystyrene

[0166] <Method for Measuring the Gel Fraction of the Pressure-Sensitive Adhesive Layer> Approximately 0.1 g of the optical pressure-sensitive adhesive layer formed on the release-treated surface of a separator film within 1 minute of preparation was scraped off and designated Sample 1. Sample 1 was wrapped in a 0.2 μm-diameter Teflon® film (trade name "NTF1122", manufactured by Nitto Denko Corporation) and tied with kite string. This was designated Sample 2. The weight of Sample 2 before the following test was measured and designated Weight A. Weight A is the total weight of Sample 1 (pressure-sensitive adhesive layer), the Teflon® film, and the kite string. The total weight of the Teflon® film and the kite string was designated Weight B. Next, Sample 2 was placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23° C. for 1 week. Sample 2 was then removed from the container and dried in a dryer at 130° C. for 2 hours to remove the ethyl acetate, after which the weight of Sample 2 was measured. The weight of Sample 2 after the test was measured and designated as weight C. The gel fraction was calculated using the following formula: Gel fraction (mass%)=(C−B) / (A−B)×100

[0167] <Method of measuring thickness> The thickness of the pressure-sensitive adhesive layer was measured at five points on the pressure-sensitive adhesive layer using a dial gauge and the average value was taken as the thickness. The thickness of the intermediate layer was determined as the average value of the thicknesses read at two points on the SEM image, where the intermediate layer was defined as a thickness portion with different contrast between the pressure-sensitive adhesive layer and the low refractive index layer.

[0168] <Method for Measuring Refractive Index> The refractive index was measured by the above-described method for evaluating the refractive index.

[0169] In the adhesive layers in the following Reference Examples, Examples, and Comparative Examples, it is presumed that the polymer (acrylic polymer) is crosslinked by the crosslinking agent when the applied adhesive is heated and dried, thereby forming a crosslinked structure, but the crosslinked structure has not been confirmed.

[0170] Reference Example 1: Production of void layer-forming coating liquid First, a gel (porous silicone body) having a porous structure was produced by gelling a silicon compound (step (1) below) and aging (step (2) below). The following steps (3) morphology control, (4) solvent substitution, and (5) gel crushing were then carried out to obtain a void layer-forming coating liquid (liquid containing gel crushed material). In this reference example, the following step (3) morphology control was carried out as a separate step from the following step (1), as described below. However, the present disclosure is not limited thereto, and for example, the following step (3) morphology control may be carried out during the following step (1).

[0171] (1) Gelation of silicon compound 9.5 kg of MTMS, a precursor of the silicon compound, was dissolved in 22 kg of DMSO. 5 kg of 0.01 mol / L oxalic acid solution was added to the mixture, and the mixture was stirred at room temperature for 120 minutes to hydrolyze MTMS and produce tris(hydroxy)methylsilane.

[0172] To 55 kg of DMSO, 3.8 kg of 28% aqueous ammonia and 2 kg of pure water were added, and the hydrolyzed mixture was further added and 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 silicon compound.

[0173] (2) Aging process The gel-like silicon compound obtained by the gelation treatment was incubated at 40°C for 20 hours to perform an aging treatment, thereby obtaining the rectangular shaped block of gel. Since the amount of DMSO (a high-boiling solvent with a boiling point of 130°C or higher) used in the raw material was approximately 83% by mass of the total raw material, it was clear that this gel contained 50% by mass or more of a high-boiling solvent with a boiling point of 130°C or higher. Furthermore, since the amount of MTMS (a monomer that is a constituent unit of the gel) used in the raw material was approximately 8% by mass of the total raw material, it was clear that the content of a solvent (methanol in this case) with a boiling point of less than 130°C generated by hydrolysis of the monomer (MTMS), a constituent unit of the gel, was 20% by mass or less.

[0174] (3) Morphology Control Step: Water, a substitution solvent, was poured onto the gel synthesized in the 30 cm × 30 cm × 5 cm stainless steel vessel in steps (1) and (2). Next, a cutting blade of a cutting tool was slowly inserted into the gel from above in the stainless steel vessel, and the gel was cut into a rectangular parallelepiped with a size of 1.5 cm × 2 cm × 5 cm.

[0175] (4) Solvent Substitution Step Next, the solvent substitution step was carried out as follows (4-1) to (4-3).

[0176] (4-1) After the "(3) morphology control step", the gel silicon compound was immersed in water with a weight 8 times that of the gel silicon compound, and slowly stirred for 1 hour so that only the water was convected. After 1 hour, the water was replaced with the same amount of water, and the mixture was further stirred for 3 hours. After that, the water was replaced again, and the mixture was heated at 60°C for 3 hours with slow stirring.

[0177] (4-2) After (4-1), the water was replaced with isopropyl alcohol in an amount four times the weight of the gel silicon compound, and the mixture was heated at 60° C. for 6 hours while stirring.

[0178] (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 in the gel silicon compound with isobutyl alcohol. In this way, the gel for producing a void layer according to the present disclosure was produced.

[0179] (5) Gel Crushing Step The gel (gel silicon compound) after the (4) solvent replacement step was subjected to two stages of continuous emulsification dispersion (manufactured by Pacific Machinery Co., Ltd., Milder MDN304 type) in the first crushing stage, and high-pressure medialess crushing (manufactured by Sugino Machine Co., Ltd., Starburst HJP-25005 type) in the second crushing stage. In this crushing process, 26.6 kg of isobutyl alcohol was added to 43.4 kg of gel containing the solvent-substituted gel silicon compound, and then weighed. The first crushing stage was circulated for 20 minutes, and the second crushing stage was crushed at a crushing pressure of 100 MPa. In this way, an isobutyl alcohol dispersion (gel crushed product-containing liquid) in which nanometer-sized particles (crushed product of the gel) were dispersed was obtained. Furthermore, 224 g of a 1.5% solution of WPBG-266 (trade name, manufactured by Wako) in methyl isobutyl ketone was added to 3 kg of the gel powder-containing liquid, and then 67.2 g of a 5% solution of bis(trimethoxysilyl)ethane (manufactured by TCI) in methyl isobutyl ketone was added, and then 31.8 g of N,N-dimethylformamide was added and mixed to obtain a coating liquid.

[0180] In this manner, a void-layer-forming coating liquid (gel pulverized material-containing liquid) of this Reference Example (Reference Example 1) was produced. The peak pore diameter of the pulverized gel (microporous particles) in the void-layer-forming coating liquid (gel pulverized material-containing liquid) was measured by the method described above and was found to be 12 nm.

[0181] Reference Example 2: Formation of adhesive layer The adhesive layer of this reference example (Reference Example 2) was formed by the following procedures (1) and (2).

[0182] (1) Preparation of (meth)acrylic polymer (Preparation of (meth)acrylic polymer (A1)) A four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with a monomer mixture containing 79.5 parts of butyl acrylate, 15 parts of N-acryloylmorpholine, 5 parts of acrylic acid, and 0.5 parts of 4-hydroxybutyl acrylate. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 70 parts of ethyl acetate were charged to 100 parts of the monomer mixture. Nitrogen gas was introduced with gentle stirring to replace the atmosphere with nitrogen, and the temperature in the flask was maintained at around 55°C to carry out a polymerization reaction for 2 hours to prepare a solution of (meth)acrylic polymer (A1) having a weight average molecular weight (Mw) of 3,400,000 and an Mw / Mn of 2.5.

[0183] (Preparation of (meth)acrylic polymer (A2)) In (Preparation of (meth)acrylic polymer (A1)), the monomer composition charged was 79.5 parts of butyl acrylate, 7.5 parts of N-acryloylmorpholine, 5 parts of acrylic acid, and 0.5 parts of 4-hydroxybutyl acrylate, and the polymerization reaction time was 8 hours. The other conditions were the same as in (Preparation of (meth)acrylic polymer (A1)), so that a solution of a (meth)acrylic polymer (A2) having a weight average molecular weight (Mw) of 2,900,000 and Mw / Mn=4.2 was prepared.

[0184] (2) (Preparation of Pressure-Sensitive Adhesive Composition) 0.5 parts of an organic silyl group-containing compound (trade name "KBM-802" manufactured by Shin-Etsu Chemical Co., Ltd.), 0.2 parts of an isocyanate crosslinking agent (trade name "Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd., an adduct of trimethylolpropane and tolylene diisocyanate), 0.1 parts of an epoxy crosslinking agent (trade name "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Inc.), and 0.2 parts of benzoyl peroxide (trade name "Niper BMT" manufactured by NOF Corporation) were blended relative to 100 parts of the solid content of the (meth)acrylic polymer (A1) or (A2) to prepare an acrylic pressure-sensitive adhesive composition.

[0185] (3) (Formation of Pressure-Sensitive Adhesive Layer) Next, the acrylic pressure-sensitive adhesive composition was applied to one surface of a polyethylene terephthalate film (separator film: MRF38, manufactured by Mitsubishi Chemical Polyester Film Corporation) that had been treated with a silicone-based release agent, so that the thickness of the pressure-sensitive adhesive layer after drying would be 10 μm, and the applied film was dried at 155° C. for 1 minute, thereby forming a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) on the surface of the separator film.

[0186] Reference Example 3: Modification reaction of nanoparticles with fluoroalkyl groups 0.27 g of IPA (isopropyl alcohol) was added to 0.06 g of 0.1 N (0.1 mol / L) aqueous HCl solution and then stirred to obtain a uniform solution. 10 g of MIBK-ST (Nissan Chemical's trade name: MIBK [methyl isobutyl ketone] dispersion of Si nanoparticles) was added to the solution, and 0.7 g of trimethoxy(1H,1H,2H,2H-nonafluorohexyl)silane was further added. The mixture thus obtained was heated and stirred at 60 ° C. for 1 hour to perform a modification reaction of the Si nanoparticles, and a fluoroalkyl group-modified dispersion of the Si nanoparticles (modified nanoparticle dispersion) was obtained.

[0187] [Example 1] (Production of laminate) 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 (void ratio 59% by volume) with a film thickness of about 850 nm. Next, UV irradiation (300 mJ) was performed from the void layer surface. Thereafter, a 10 μm thick pressure-sensitive adhesive layer (in this example, (meth)acrylic polymer (A1) was used) 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 example.

[0188] [Examples 2 to 21 and Comparative Examples 1 and 2] Laminates of Examples 2 to 21 and Comparative Examples 1 and 2 were produced as follows.

[0189] Solutions of the acrylic pressure-sensitive adhesive composition used in the production of the laminates of Examples 2 to 21 and Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that for Examples 2 to 21 and Comparative Examples 1 and 2, the type of (meth)acrylic polymer was as shown in Table 1 below, the type and added amount (parts by mass) of the organosilyl group-containing compound was as shown in Table 1 below, the added amount (parts by mass) of the crosslinking agent was as shown in Tables 1 and 2 below, and in Examples 13 to 16, 0.06 g of the modified nanoparticle dispersion obtained in Reference Example 3 was added to 3 g of the void layer-forming coating liquid prepared in Reference Example 1. Furthermore, using the solutions of the acrylic pressure-sensitive adhesive composition, adhesive layers were prepared in the same manner as in Example 1, and the laminates of Examples 2 to 21 and Comparative Examples 1 and 2 were produced. In Tables 1 and 2 below, all of the organosilyl group-containing compounds were manufactured by Shin-Etsu Chemical Co., Ltd., and the "type" of the organosilyl group-containing compound is the trade name of Shin-Etsu Chemical Co., Ltd.

[0190] [Heat durability test] Furthermore, the laminates of the present example and comparative example produced as described above were placed in an oven at a temperature of 65°C and a relative humidity of 95%, and a heat durability test was performed for 500 hours. From the refractive index before and after the heat durability test, the rate of change in refractive index was calculated using the above-mentioned formula (1).

[0191] The evaluation criteria for the rate of change in refractive index after the heat durability test in Tables 1 and 2 are as follows: The rate of change in refractive index (%) after the heat durability test in Tables 1 and 2 is calculated by (|n - n ０ | / n ０ ) × 100. ◎: Less than 2.0% ○: 2.0% or more but less than 3.0% ×: 3.0% or more

[0192] The evaluation criteria for the refractive index (amount of change) after the heat durability test in Tables 1 and 2 are as follows: The refractive index (amount of change) after the heat durability test is |n-n ０ | is the numerical value calculated by ０is the refractive index (initial refractive index) of the porous layer before the heat durability test, as in the above-mentioned formula (1), and n is the refractive index of the porous layer after the heat durability test, as in the above-mentioned formula (1). ◎: Less than 0.03 ○: 0.03 or more and less than 0.04 ×: 0.04 or more

[0193] The meanings of the abbreviations shown in Table 1 are as follows. The numbers in Table 1 indicate the amount (parts by mass) of each component added. [(Meth)acrylic polymer] "A1" or "A2" indicates whether the (meth)acrylic polymer A1 or A2 described in Reference Example 2 was used in the formed adhesive layer. The method for forming the adhesive layer was as described in Reference Example 2. [Organic silyl group-containing compound] Type: indicates the type of organic silyl group-containing compound used in each Example and Comparative Example, and is a trade name of Shin-Etsu Chemical Co., Ltd. as described above. Monomer / oligomer: indicates whether the organic silyl group-containing compound used in each Example and Comparative Example is a monomeric silane coupling agent or an oligomeric silane coupling agent. Functional group: indicates the type of functional group possessed by the organic silyl group-containing compound used in each Example and Comparative Example. Methoxy or ethoxy: Indicates whether the organic silyl group-containing compound used in each Example and Comparative Example has a methoxy group or an ethoxy group, or whether it has a silanol group in the form in which the group is hydrolyzed. [Crosslinking agent] Isocyanate: Adduct of trimethylolpropane and tolylene diisocyanate (trade name "Coronate L" manufactured by Tosoh Corporation) Epoxy: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (trade name "Tetrad C" manufactured by Mitsubishi Gas Chemical Company, Inc.) Peroxide: Benzoyl peroxide (trade name "Niper BMT" manufactured by NOF Corporation)

[0194]

[0195]

[0196] As shown in Table 1, Examples 1 to 21, which used an organic silyl group-containing compound, had a low initial refractive index, a low refractive index (change) after the heat durability test, and excellent peel durability. That is, the laminates of Examples 1 to 21 had a low initial refractive index and excellent heat durability because the adhesive did not easily penetrate into the voids in the void layer, and these effects were compatible with strong adhesion between the adhesive layer and the low refractive index layer. In contrast, when the amount of organic silyl group-containing compound added exceeded 5.0 parts by mass (Comparative Example 1), or when no organic silyl group-containing compound was used (Comparative Example 2), the adhesive easily penetrated into the voids in the void layer, resulting in poor initial refractive index, heat durability, and adhesion between the adhesive layer and the low refractive index layer. More specifically, Comparative Example 1 had a poor initial refractive index, and Comparative Example 2 had a good initial refractive index but poor heat durability. In Examples 1 to 21 and Comparative Examples 1 and 2, the void layer did not contain a fluorine compound because no fluorine compound was used in forming the void layer. Furthermore, the organic silyl group-containing compounds used in Examples 1 to 21 had a mercapto group, an epoxy group, an alicyclic epoxy group, an isocyanate group (isocyanato group), an amino group, an acrylic group, a styryl group, a vinyl group, an isocyanurate group, an acetoacetyl group, a silane group, or a carboxylic acid group (carboxy group) as a functional group, as shown in Table 1, and the above-mentioned effects were achieved with any of the functional groups.

[0197] The present disclosure can be described, for example, as in the following supplementary notes: However, the supplementary notes below are examples, and the present disclosure is not limited to these forms.

[0198] (Appendix 1) A laminate comprising a porous layer and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is directly laminated on one or both sides of the porous layer, wherein the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive containing a (meth)acrylic polymer and an organosilyl group-containing compound, and the organosilyl group of the organosilyl group-containing compound may or may not contain a carbon-silicon bond, and wherein the rate of increase in the refractive index of the porous layer before and after a heat durability test in which the laminate is maintained at a temperature of 65°C and a relative humidity of 95% for 500 hours satisfies the following mathematical formula (1): (|n-n ０ | / n０ )×100<3.0 (1) In the formula (1), n ​​is the refractive index of the porous layer after the heat durability test, and n ０ is the refractive index of the porous layer before the heat durability test. (Appendix 2) The laminate according to Appendix 1, wherein the content of the organosilyl group-containing compound is 5.0 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer. (Appendix 3) The laminate according to Appendix 1 or 2, wherein the organosilyl group-containing compound is a compound containing an alkoxysilyl group. (Appendix 4) The laminate according to any one of Appendixes 1 to 3, wherein the (meth)acrylic polymer has a weight average molecular weight (Mw) of 1,500,000 to 4,000,000. (Appendix 5) The laminate according to any one of Appendixes 1 to 4, wherein the adhesive layer is formed from an adhesive containing the (meth)acrylic polymer and a crosslinking agent, and the adhesive has a gel fraction of more than 85%. (Appendix 6) The laminate according to any one of Appendixes 1 to 5, wherein the (meth)acrylic polymer contains 1 to 30 mass% of a nitrogen-containing monomer as a monomer unit. (Appendix 7) The laminate according to Appendices 6, wherein the nitrogen-containing monomer is a heterocycle-containing acrylic monomer. (Appendix 8) The laminate according to any one of Appendices 1 to 7, wherein the (meth)acrylic polymer contains 0.5 to 20 mass% of acrylic acid as a monomer unit. (Appendix 9) The laminate according to any one of Appendices 1 to 8, wherein the void layer does not contain an organic fluorine compound. (Appendix 10) The laminate according to any one of Appendices 1 to 9, wherein an intermediate layer is present between the void layer and the adhesive layer, and the intermediate layer is a layer formed by combining the void layer and the adhesive layer. (Appendix 11) The laminate according to Appendices 10, wherein the intermediate layer has a thickness of 10 to 100 nm. (Appendix 12) An optical member comprising the laminate according to any one of Appendices 1 to 11. (Appendix 13) An optical device comprising the optical member according to Appendices 12.

[0199] As described above, the present disclosure can provide a laminate, optical member, and optical device that combines adhesive strength or adhesion with resistance to penetration of a pressure-sensitive adhesive or adhesive into the voids in the void layer. The applications of the present disclosure are not particularly limited. For example, the optical device of the present disclosure is not particularly limited, and examples thereof include image display devices and lighting devices. Examples of the image display devices include liquid crystal displays, organic EL displays, and micro LED displays. Examples of the lighting devices include organic EL lighting. The laminate of the present disclosure is particularly suitable for use under high-durability conditions, such as in-vehicle applications, because the pressure-sensitive adhesive or adhesive is less likely to penetrate into the voids in the void layer, even under high temperatures and high humidity. Furthermore, the applications of the laminate of the present disclosure are not limited to the optical members and optical devices of the present disclosure, and are arbitrary, and the laminate can be used in a wide range of applications.

[0200] This application claims priority based on Japanese Patent Application No. 2023-163763, filed on September 26, 2023, the disclosure of which is incorporated herein in its entirety by reference.

[0201] 10, 10a, 10b, 10c, 10d, 10e laminate 11 void layer 12 adhesive layer 13 intermediate layer 14 base material

Claims

1. A laminate comprising a void layer and a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer being directly laminated on one or both sides of the void layer, the pressure-sensitive adhesive layer being formed from a pressure-sensitive adhesive containing a (meth)acrylic polymer and an organosilyl group-containing compound, the organosilyl group of the organosilyl group-containing compound may or may not contain a carbon-silicon bond, and the increase rate of the refractive index of the void layer before and after a heat durability test in which the laminate is maintained at a temperature of 65°C and a relative humidity of 95% for 500 hours satisfies the following mathematical formula (1). (|n-n ０ | / n ０ In the above formula (1), n ​​is the refractive index of the air gap layer after the heat durability test, and n ０ is the refractive index of the air gap layer before the heat durability test.

2. The laminate according to claim 1, wherein the content of said organic silyl group-containing compound is 5.0 parts by mass or less per 100 parts by mass of said (meth)acrylic polymer.

3. The laminate according to claim 1, wherein the organic silyl group-containing compound is a compound containing an alkoxysilyl group.

4. The laminate according to claim 1, wherein the (meth)acrylic polymer has a weight average molecular weight (Mw) of 1.5 million to 4 million.

5. The laminate according to claim 1, wherein the adhesive layer is formed from an adhesive containing the (meth)acrylic polymer and a crosslinking agent, and the adhesive has a gel fraction of more than 85%.

6. The laminate according to claim 1, wherein the (meth)acrylic polymer contains, as monomer units, 1 to 30% by weight of a nitrogen-containing monomer.

7. The laminate according to claim 6, wherein said nitrogen-containing monomer is a heterocycle-containing acrylic monomer.

8. The laminate according to claim 1, wherein the (meth)acrylic polymer contains 0.5 to 20% by weight of acrylic acid as a monomer unit.

9. The laminate according to claim 1, wherein the air gap layer does not contain an organic fluorine compound.

10. The laminate according to claim 1, wherein an intermediate layer is present between said void layer and said adhesive layer, said intermediate layer being a layer formed by combining said void layer and said adhesive layer.

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

12. An optical member comprising a laminate according to any one of claims 1 to 11.

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

Images