JP2023152803A - Optical laminate, method for manufacturing optical laminate, optical member, and method for manufacturing optical member - Google Patents

Abstract

To provide an optical laminate which can be thinned and can maintain excellent optical performance, a method for manufacturing an optical laminate, an optical member, and a method for manufacturing an optical member.SOLUTION: An optical laminate includes: a transparent resin layer having thickness of 20 μm or less; a porous layer which is provided directly on one surface in a thickness direction of the transparent resin layer and has a refractive index of 1.25 or less; an adhesive layer which is provided directly on a surface opposite to the transparent resin layer in the porous layer; and an adhesive layer which is provided directly on a surface opposite to the porous layer in the transparent resin layer. Peeling force when the transparent resin layer is peeled from the porous layer is 1 N/25 mm or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical laminate, a method for manufacturing an optical laminate, an optical member, and a method for manufacturing an optical member.

It is known that an optical laminate including a low refractive index layer having a lower refractive index than the optical film is placed between two optical films to arbitrarily control the optical properties of an optical product containing the optical laminate. . Such an optical laminate may include, for example, a base material and a variable refractive index extraction layer provided on the base material, and the variable refractive index extraction layer may selectively contain a first substance having a relatively small refractive index. An optical laminate is proposed that includes a first region printed on the first material and a second region formed by overcoating the first material with a second material having a relatively high refractive index. (For example, see Patent Document 1). In the optical laminate described in Patent Document 1, adhesive layers are formed on both sides in the thickness direction, and the adhesive layer is attached to each optical film. In recent years, the uses of optical products have been diversifying, and it is desired that optical products be made smaller and, by extension, optical laminates included in the optical products be made thinner. However, the optical laminate described in Patent Document 1 includes a base material that supports the variable refractive index extraction layer, and it is difficult to reduce the thickness of the optical laminate. Making the base material thinner or peeling and removing the base material from the variable refractive index extraction layer is considered, but making the base material thinner is difficult from the viewpoint of manufacturing stability of optical laminates, and it is difficult to make the base material thinner. Peeling the material may damage the variable index extraction layer. Furthermore, if the base material is peeled off and an adhesive layer is directly provided on the variable refractive index extraction layer, there is a problem that the optical performance of the variable refractive index extraction layer cannot be maintained sufficiently.

International Publication No. 2014/031726

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to provide an optical laminate that can be made thinner and maintain excellent optical performance, and a method for manufacturing the optical laminate. , an optical member, and a method for manufacturing the optical member.

[1] The optical laminate according to the embodiment of the present invention includes a transparent resin layer having a thickness of 20 μm or less; and a porous layer provided directly on one surface in the thickness direction of the transparent resin layer and having a refractive index of 1.25 or less. an adhesive layer provided directly on the surface of the porous layer opposite to the transparent resin layer; and an adhesive layer provided directly on the surface of the transparent resin layer opposite to the porous layer. There is. In this embodiment, the peeling force when peeling the transparent resin layer from the porous layer is 1 N/25 mm or more.
[2] In the optical laminate according to [1] above, the arithmetic mean roughness Ra of the contact surface of the porous layer with the transparent resin layer may be 300 nm or less.
[3] In the optical laminate described in [1] or [2] above, the resin material constituting the transparent resin layer may have a polar group.
[4] In the optical laminate according to any one of [1] to [3] above, the transparent resin layer has a barrier function that suppresses the components constituting the adhesive layer from permeating into the porous layer. may have.
[5] In the optical laminate according to any one of [1] to [4] above, the porosity of the transparent resin layer may be smaller than the porosity of the porous layer.
[6] In the optical laminate according to any one of [1] to [5] above, the adhesive layer is made of an adhesive having a storage modulus of 1.0 x 10 ⁵ (Pa) or more at 23°C. may be configured.
[7] In the optical laminate according to any one of [1] to [6] above, a color shift value Δxy when light is guided through the transparent resin layer may be 0.1 or less. .
[8] The optical laminate according to any one of [1] to [7] above may have a scattering value of less than 50 when light is guided through the transparent resin layer.
[9] An optical member according to another aspect of the present invention includes the optical laminate according to any one of [1] to [8] above, and a conductor located on the opposite side of the transparent resin layer with respect to the adhesive layer. A light member.
[10] A method for producing an optical laminate according to still another aspect of the present invention includes the steps of: forming a transparent resin layer having a thickness of 20 μm or less on a base material; a surface of the transparent resin layer opposite to the base material; a step of forming a porous layer having a refractive index of 1.25 or less; a step of forming an adhesive layer on the surface of the porous layer opposite to the transparent resin layer; The method includes a step of peeling off the layer; and a step of forming an adhesive layer on the surface of the transparent resin layer opposite to the porous layer.
[11] In the method for producing an optical laminate according to [10] above, the peeling force when peeling the base material from the transparent resin layer is the peeling force when peeling the transparent resin layer from the porous layer. It may be smaller than the force.
[12] In the method for producing an optical laminate according to [10] or [11] above, in the step of forming a transparent resin layer on the base material, the solution in which the resin material of the transparent resin layer is dissolved is After coating on a substrate to form a coating film, the coating film may be dried to form the transparent resin layer.
[13] A method for manufacturing an optical member according to yet another aspect of the present invention includes the steps of preparing an optical laminate by the method for manufacturing an optical laminate according to any one of [10] to [12] above; and providing a light guide member on the side opposite to the transparent resin layer with respect to the adhesive layer.

According to the embodiments of the present invention, it is possible to realize an optical laminate and an optical member that can be made thinner and maintain excellent optical performance.

FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of an optical product including the optical laminate of FIG. FIGS. 3(a) to 3(e) are schematic cross-sectional views for explaining a method for manufacturing an optical laminate according to one embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of an optical member including the optical laminate shown in FIG.

Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments. First, the overall structure of the optical laminate will be outlined, and then the constituent elements of the optical laminate will be specifically explained.

A. Overall configuration of optical laminate FIG. 1 is a schematic cross-sectional view of an optical laminate according to one embodiment of the present invention. The illustrated optical laminate 100 includes a transparent resin layer 1 having a thickness of 20 μm or less; a porous layer 2 provided directly on one surface in the thickness direction of the transparent resin layer 1 and having a refractive index of 1.25 or less. ; a first adhesive layer 3 provided directly on the surface of the porous layer 2 opposite to the transparent resin layer 1; an adhesive layer 4 provided directly on the surface of the transparent resin layer 1 opposite to the porous layer 2; It is equipped with That is, the optical laminate 100 has a double-sided adhesive structure including the adhesive layer 4, the transparent resin layer 1, the porous layer 2, and the adhesive layer 3 in this order. In the optical laminate 100, the peeling force when peeling the transparent resin layer 1 from the porous layer 2 is 1 N/25 mm or more, preferably 1.5 N/25 mm or more. Peeling force is measured, for example, by the method below.
A laminated film of a transparent resin layer (to be peeled) and a porous layer is sampled in the form of a 50 mm x 140 mm strip, and the sample (more specifically, the transparent resin layer) is fixed to a glass plate with double-sided tape. An acrylic adhesive layer (thickness 20 μm) was laminated to a PET film (T100: manufactured by Mitsubishi Plastic Film Co., Ltd.), and a piece of adhesive tape cut into 25 mm x 100 mm was laminated to the porous layer side of the laminated film. Laminate with PET film. Next, the sample was chucked in an autograph tensile tester (AG-Xplus, manufactured by Shimadzu Corporation) so that the distance between the chucks was 100 mm, and then the sample was chucking at a peeling angle of 180° and a tensile speed of 0.3 m/min. Perform a tensile test. The average test force of the 50 mm peel test is defined as the adhesive peel strength, that is, the adhesive force. Furthermore, adhesive strength can also be measured using the same measuring method. In the present invention, there is no clear distinction between "adhesive strength" and "adhesive strength".
The upper limit of the peeling force when peeling the transparent resin layer 1 from the porous layer 2 is not particularly limited, but is typically 10 N/25 mm or less.
In such a configuration, the transparent resin layer is disposed between the porous layer and the adhesive layer, and the thickness of the transparent resin layer is 20 μm or less, so that the optical laminate can be made thinner, and The refractive index of the porous layer can be maintained below the above upper limit. Moreover, since the peeling force when peeling the transparent resin layer from the porous layer is equal to or higher than the above lower limit, peeling of the transparent resin layer from the porous layer can be suppressed even if the transparent resin layer is made thinner. Therefore, the excellent optical performance of the optical laminate can be sufficiently maintained. The thickness of the transparent resin layer 1 is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 4 μm or less, and typically 0.1 μm or more.
Furthermore, since the porous layer is provided directly on the transparent resin layer, the optical laminate can be When light is guided in a direction perpendicular to the thickness direction, even if the light reaches the interface between the transparent resin layer and the porous layer, it can be suppressed from scattering toward the porous layer, and the brightness loss due to light guidance can be sufficiently reduced. can be suppressed.

Porous layer 2 typically has voids inside. The refractive index of the porous layer 2 is preferably less than 1.20, more preferably 1.19 or less, even more preferably 1.18 or less, and typically 1.10 or more. The refractive index refers to a refractive index measured at a wavelength of 550 nm, unless otherwise specified.
The arithmetic mean roughness Ra of the contact surface of the porous layer 2 with the transparent resin layer 1 is, for example, 300 nm or less, preferably 200 nm or less, and more preferably 100 nm or less. The arithmetic mean roughness Ra of the contact surface of the porous layer with the transparent resin layer can be measured by, for example, an AFM (atomic force microscope). If the arithmetic mean roughness Ra is below the above upper limit, light scattering that occurs when light enters the porous layer from the transparent resin layer side is suppressed, and the total reflection function of light by the porous layer becomes efficient. Can perform well.

In one embodiment, the resin material constituting the transparent resin layer 1 has a polar group. Examples of polar groups include hydroxyl group (-OH), amino group (-NH ₂ ), carboxy group (-COOH), ether group, secondary amino group, carbonyl group, urethane bond, amide group, and ester group. , but not limited to these. It is sufficient that the resin material constituting the transparent resin layer 1 has a functional group in the resin composition that has a biased charge distribution in molecules or chemical bonds. The resin material constituting the transparent resin layer may have one type of polar group, or may have two or more types of polar groups. When the resin material constituting the transparent resin layer has a polar group, the adhesion of the transparent resin layer to the porous layer can be further improved.

In one embodiment, the transparent resin layer 1 is a barrier layer 1a having a barrier function of suppressing the components constituting the adhesive layer 4 from permeating into the porous layer 2. Therefore, an increase in the refractive index of the porous layer can be stably suppressed. The adhesive layer 4 may be an adhesive layer or an adhesive layer.

In one embodiment, the porosity of the transparent resin layer 1 is smaller than the porosity of the porous layer 2. According to such a configuration, it is possible to sufficiently ensure the barrier performance of the transparent resin layer 1, and it is possible to stably suppress the pressure-sensitive adhesive or adhesive forming the adhesive layer from entering the voids of the porous layer.
The porosity of the transparent resin layer 1 is, for example, 15% by volume or less, preferably 10% by volume or less.
The porosity of the porous layer 2 is, for example, more than 10 vol%, preferably 20 vol% or more, more preferably 30 vol% or more, even more preferably 35 vol% or more, and, for example, 60 vol% or less, preferably The content is 55% by volume or less, more preferably 50% by volume or less, even more preferably 45% by volume or less. When the porosity is within such a range, the refractive index of the porous layer can be set within an appropriate range, and a predetermined mechanical strength can be ensured. The porosity is a value calculated from the refractive index value measured with an ellipsometer using Lorentz-Lorenz's formula.

In one embodiment, the adhesive layer 3 is made of an adhesive whose storage modulus at 23° C. is 1.0×10 ⁵ (Pa) or more. The storage modulus of the adhesive constituting the adhesive layer 3 at 23° C. is preferably 1.1×10 ⁵ (Pa) or more, more preferably 1.2×10 ⁵ (Pa) or more. When the storage elastic modulus of the adhesive is at least the above-mentioned lower limit, it is possible to suppress the adhesive constituting the adhesive layer from entering the voids of the porous layer. Therefore, an increase in the refractive index of the porous layer can be suppressed more stably. The storage modulus was determined in accordance with the method described in JIS K 7244-1 "Plastics - Test method for dynamic mechanical properties" at a temperature increase rate of 5°C in the range of -50°C to 150°C at a frequency of 1 Hz. It is determined by reading the value at 23°C when measured in /min. The upper limit of the storage modulus at 23° C. of the adhesive constituting the adhesive layer 3 is typically 100×10 ⁵ (Pa) or less.

The transparent resin layer, porous layer, adhesive layer, and adhesive layer will be specifically explained below.

B. Transparent Resin Layer The transparent resin layer 1 can transmit light. The total light transmittance of the transparent resin layer 1 is, for example, 70% to 100%, preferably 80% to 99%. If the total light transmittance of the transparent resin layer is within the above range, excellent transparency can be achieved as a whole of the optical laminate. As a result, adverse effects on the use of the optical laminate can be suppressed.

The refractive index of the transparent resin layer 1 is typically larger than the refractive index of the porous layer 2. The refractive index of the transparent resin layer 1 exceeds 1.25, preferably 1.4 or more, and typically 1.9 or less.

The transparent resin layer 1 may have any suitable configuration as long as it can transmit light. Examples of resin materials constituting the transparent resin layer 1 include polyvinyl alcohol (PVA); (meth)acrylic resins such as polymethyl methacrylate (PMMA); polyvinyl acetal resins; polycarbonate resins, polyarylate resins, and polyurethane resins. Thermoplastic resin materials having polar groups; examples include heat- or UV-curable resin materials such as acrylic hard coat resin materials, epoxy hard coat resin materials, and silicone hard coat resin materials. Note that (meth)acrylic refers to acrylic and/or methacrylic. The resin materials constituting the transparent resin layer may be used alone or in combination. Further, the resin material may have a resin composition alone, or may have other substances added thereto in order to change the physical properties of the transparent resin layer. Specifically, a boric acid compound or a silane compound may be added to introduce a crosslinked structure into PVA.

As described above, the resin material preferably has a polar group. Among the resin materials, preferred are PVA and polyvinyl acetal having a hydroxyl group as a polar group, and (meth)acrylic resin having a carboxyl group as a polar group. The proportion of polar groups in the transparent resin layer is, for example, 1 mol% to 95 mol%, preferably 5 mol% to 90 mol%.

The transparent resin layer 1 may be composed of one layer, or may be composed of two or more layers. In one embodiment, the transparent resin layer 1 is composed of one layer. In this case, the thickness of the transparent resin layer 1 can be easily adjusted to be below the above upper limit.

C. Porous Layer The porous layer 2 is provided directly on one surface of the transparent resin layer 1 in the thickness direction, and is in contact with the transparent resin layer 1 . The total light transmittance of the porous layer 2 is, for example, 85% to 99%, preferably 87% to 98%, and more preferably 89% to 97%. The haze of the porous layer 2 is, for example, less than 5%, preferably less than 3%. On the other hand, the haze is, for example, 0.1% or more, preferably 0.2% or more. By providing such a porous layer at a predetermined position, excellent transparency can be achieved as a whole of the optical laminate. Haze can be measured, for example, by the following method.
The void layer (porous layer) is cut into a size of 50 mm x 50 mm, and the haze is measured by setting it in a haze meter (HM-150, manufactured by Murakami Color Research Institute). The haze value is calculated using the following formula.
Haze (%) = [diffuse transmittance (%) / total light transmittance (%)] × 100 (%)

The thickness of the porous layer 2 is, for example, 30 nm to 5 μm, preferably 200 nm to 4 μm, more preferably 400 nm to 3 μm, and even more preferably 600 nm to 2 μm. If the thickness of the porous layer is within this range, the porous layer can effectively exhibit a total reflection function for light in the visible to infrared region.

Any suitable structure may be adopted for the porous layer 2 as long as it has the above-mentioned desired characteristics. The porous layer may preferably be formed by coating or printing. As the material constituting the porous layer, for example, materials described in WO 2004/113966, JP 2013-254183, and JP 2012-189802 can be adopted. A typical example is a silicon compound. Examples of silicon compounds include silica-based compounds; hydrolyzable silanes, and their partial hydrolysates and dehydrated condensates; silicon compounds containing silanol groups; The activated silica obtained can be mentioned. Also included are organic polymers; polymerizable monomers (eg, (meth)acrylic monomers and styrene monomers); and curable resins (eg, (meth)acrylic resins, fluorine-containing resins, and urethane resins). These materials may be used alone or in combination. The porous layer can be formed by coating or printing a solution or dispersion of such a material.

The size of the voids (pores) in the porous layer refers to the diameter of the major axis of the major axis and the diameter of the minor axis of the voids (pores). The size of the voids (pores) is, for example, 2 nm to 500 nm. The size of the voids (pores) is, for example, 2 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and still more preferably 20 nm or more. On the other hand, the size of the voids (pores) is, for example, 500 nm or less, preferably 200 nm or less, and more preferably 100 nm or less. The size range of the voids (pores) is, for example, 2 nm to 500 nm, preferably 5 nm to 500 nm, more preferably 10 nm to 200 nm, and even more preferably 20 nm to 100 nm. The size of the voids (pores) can be adjusted to a desired size depending on the purpose and use.

The size of voids (pores) can be quantified by the BET test method. Specifically, 0.1 g of the sample (formed void layer) was put into the capillary of a specific surface area measurement device (manufactured by Micromeritics: ASAP2020), and then dried under reduced pressure at room temperature for 24 hours to remove the voids. To evacuate gases within the structure. Then, by adsorbing nitrogen gas onto the sample, an adsorption isotherm is drawn and the pore distribution is determined. This allows the void size to be evaluated.

Examples of the porous layer having voids inside include a porous layer and/or a porous layer having at least a portion of an air layer. The porous layer typically includes airgel and/or particles (eg, hollow particulates and/or porous particles). The porous layer may preferably be a nanoporous layer (specifically, a porous layer in which 90% or more of the micropores have a diameter in the range of 10 −1 nm to 103 nm).

Any suitable particles may be employed as the particles. The particles typically consist of a silica-based compound. Examples of the shape of the particles include spherical, plate-like, needle-like, string-like, and grape-like shapes. String-like particles include, for example, particles in which a plurality of particles having a spherical, plate-like, or needle-like shape are connected in a beaded manner, short fiber-like particles (for example, particles described in Japanese Patent Application Laid-open No. 2001-188104) short fibrous particles), and combinations thereof. The string-shaped particles may be linear or branched. Examples of grape cluster-shaped particles include particles in which a plurality of spherical, plate-shaped, and needle-shaped particles are aggregated to form a cluster of grapes. The shape of the particles can be confirmed, for example, by observing with a transmission electron microscope.

An example of a specific configuration of the porous layer will be described below. The porous layer of this embodiment is composed of one or more types of structural units that form a fine pore structure, and the structural units are chemically bonded to each other through catalytic action. Examples of the shape of the structural unit include particulate, fibrous, rod-like, and plate-like shapes. A structural unit may have only one shape or a combination of two or more shapes. In the following, a case will be mainly described in which the porous layer is a void layer of a porous body in which the microporous particles are chemically bonded to each other.

Such a void layer can be formed, for example, by chemically bonding microporous particles (porous particles) to each other in the void layer forming step. Note that in the embodiments of the present invention, the shape of the "particles" (for example, the above-mentioned microporous particles) is not particularly limited, and may be, for example, spherical or other shapes. Further, in an embodiment of the present invention, the microporous particles may be, for example, sol-gel beads, nanoparticles (hollow nanosilica/nanoballoon particles), nanofibers, or the like. Microporous particles typically include inorganic materials. Specific examples of inorganic substances include silicon (Si), magnesium (Mg), aluminum (Al), titanium (Ti), zinc (Zn), and zirconium (Zr). These may be used alone or in combination of two or more. In one embodiment, the microporous particles are, for example, microporous particles (porous particles) of a silicon compound, and the porous body is, for example, a silicone porous body. The microporous particles of the silicon compound include, for example, pulverized gel-like silica compounds. Further, as another form of the porous layer and/or the porous layer having at least a part of the air layer, for example, the layer is made of a fibrous material such as nanofibers, and the fibrous material is entangled to form voids. There is a void layer that forms the The method for manufacturing such a void layer is not particularly limited, and is similar to the method for producing the void layer of a porous body in which microporous particles are chemically bonded to each other. Still other forms include a void layer formed using hollow nanoparticles or nanoclay, a void layer formed using hollow nanoballoons, or magnesium fluoride. The void layer may be a void layer made of a single constituent material, or may be a void layer made of a plurality of constituent materials. The void layer may be configured with a single above-mentioned form, or may be formed with a plurality of the above-mentioned forms.

In this embodiment, the porous structure of the porous body may be, for example, an open cell structure with continuous pore structure. The open-cell structure means, for example, in the above silicone porous body, that the pore structure is three-dimensionally connected, and can also be said to be a state in which the internal voids of the pore structure are continuous. When the porous body has an open cell structure, it is possible to increase the porosity. However, when using closed-cell particles (particles each having a pore structure) such as hollow silica, an open-cell structure cannot be formed. On the other hand, when using, for example, silica sol particles (pulverized gel-like silicon compound that forms a sol), the particles have a three-dimensional dendritic structure, so the coating film (including the pulverized gel-like silicon compound) is used. By settling and depositing the dendritic particles in the sol coating film, it is possible to easily form an open cell structure. The porous layer more preferably has a monolith structure in which the open cell structure includes a plurality of pore distributions. The monolith structure means, for example, a hierarchical structure including a structure in which nano-sized fine voids exist and an open cell structure in which the nano-sized voids are assembled. When forming a monolith structure, for example, fine voids provide membrane strength while coarse open voids provide high porosity, making it possible to achieve both membrane strength and high porosity. Such a monolithic structure can be preferably formed by controlling the pore distribution of the resulting pore structure in the gel (gel-like silicon compound) prior to grinding into silica sol particles. Further, for example, when a gel-like silicon compound is pulverized, a monolith structure can be formed by controlling the particle size distribution of silica sol particles after pulverization to a desired size.

The porous layer includes, for example, a pulverized gel-like compound as described above, and the pulverized materials are chemically bonded to each other. The form of chemical bonding (chemical bonding) between the pulverized materials in the porous layer is not particularly limited, and examples thereof include crosslinking, covalent bonding, and hydrogen bonding.

The volume average particle size of the pulverized material in the porous layer is, for example, 0.05 μm or more, preferably 0.10 μm or more, and more preferably 0.11 μm or more. On the other hand, the volume average particle diameter is, for example, 1.00 μm or less, preferably 0.90 μm or less, and more preferably 0.50 μm or less. The range of the volume average particle diameter is, for example, 0.05 μm to 1.00 μm, preferably 0.10 μm to 0.90 μm, and more preferably 0.11 μm to 0.55 μm. The particle size distribution can be measured using, for example, a particle size distribution evaluation device such as a dynamic light scattering method or a laser diffraction method, or an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Note that the volume average particle diameter is an index of the variation in particle size of the pulverized material.

The type of gel compound is not particularly limited. Examples of gel-like compounds include gel-like silicon compounds.

Further, in the porous layer (void layer), for example, it is preferable that the silicon atoms contained therein are bonded with siloxane. As a specific example, the proportion of unbonded silicon atoms (that is, residual silanol) among all silicon atoms contained in the void layer is, for example, less than 50%, preferably 30% or less, and more preferably 15%. It is as follows.

D. Adhesive layer (first adhesive layer)
Although the adhesive layer 3 will be described in detail later, it is provided to attach the optical laminate 100 to an optical film. The adhesive layer 3 is located on the opposite side of the transparent resin layer 1 with respect to the porous layer 2, and is in contact with the porous layer 2.
The refractive index of the adhesive layer 3 is typically larger than the refractive index of the porous layer 2. The refractive index of the adhesive layer 3 exceeds 1.25, preferably 1.4 or more, and typically 1.7 or less.

As the adhesive constituting the adhesive layer 3, any appropriate adhesive may be used as long as it has the above characteristics. A typical example of the adhesive is an acrylic adhesive (acrylic adhesive composition). Acrylic pressure-sensitive adhesive compositions typically contain a (meth)acrylic polymer as a main component (base polymer). The (meth)acrylic polymer may be contained in the adhesive composition in a proportion of, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, based on the solid content of the adhesive composition. The (meth)acrylic polymer contains alkyl (meth)acrylate as a main component as a monomer unit. Note that (meth)acrylate refers to acrylate and/or methacrylate. Examples of the alkyl group of the alkyl (meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. The average number of carbon atoms in the alkyl group is preferably 3 to 9. In addition to alkyl (meth)acrylates, monomers constituting (meth)acrylic polymers include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocycle-containing (meth)acrylates. Examples include comonomers such as acrylates. The comonomer is preferably a hydroxyl group-containing monomer and/or a heterocycle-containing (meth)acrylate, more preferably N-acryloylmorpholine. The acrylic pressure-sensitive adhesive composition may preferably contain a silane coupling agent and/or a crosslinking agent. Examples of the silane coupling agent include epoxy group-containing silane coupling agents. Examples of the crosslinking agent include isocyanate crosslinking agents and peroxide crosslinking agents. Details of such an adhesive layer or an acrylic adhesive composition are described in, for example, Japanese Patent No. 4140736, and the description of this patent publication is incorporated herein by reference.

The thickness of the adhesive layer 3 is, for example, 3 μm to 30 μm, preferably 5 μm to 10 μm. If the thickness of the adhesive layer is within this range, the optical laminate can be made thinner while having sufficient adhesion.

E. Adhesive Layer In one embodiment, the adhesive layer 4 is provided to attach the optical laminate 100 to an optical film, as will be described in detail later. The adhesive layer 4 may be provided to attach the optical laminate 100 to a light guide member (typically a light guide plate). The adhesive layer 4 is located on the side opposite to the porous layer 2 with respect to the transparent resin layer 1 and is in contact with the transparent resin layer 1. Since the adhesive layer 4 is not in contact with the porous layer 2, its configuration is not particularly limited, and any suitable configuration can be adopted. As described above, the adhesive layer 4 may be an adhesive layer or an adhesive layer. When the adhesive layer 4 is an adhesive layer, the adhesive layer 3 is referred to as a first adhesive layer 3, and the adhesive layer 4 is referred to as a second adhesive layer 4a.
Examples of the adhesive constituting the second adhesive layer 4a include (meth)acrylic adhesives. The thickness of the second adhesive layer 4a is, for example, 5 μm or more and 200 μm or less, preferably 100 μm or less.
Examples of the adhesive constituting the adhesive layer include a thermosetting adhesive and an ultraviolet curable adhesive. The thickness of the adhesive layer is, for example, 0.1 μm or more and 100 μm or less.

F. Method for manufacturing an optical laminate Next, a method for manufacturing an optical laminate according to one embodiment will be described.
FIGS. 3(a) to 3(e) are schematic cross-sectional views for explaining a method for manufacturing an optical laminate according to one embodiment of the present invention.
A method for manufacturing an optical laminate according to one embodiment includes the steps of forming a transparent resin layer 1 having a thickness of 20 μm or less on a base material 5; a step of forming a porous layer 2 having a ratio of 1.25 or less; a step of forming an adhesive layer 3 on the surface of the porous layer 2 opposite to the transparent resin layer 1; The process includes a step of peeling off the resin layer 1; and a step of forming an adhesive layer 4 on the surface of the transparent resin layer 1 opposite to the porous layer 2.

In this method, as shown in FIG. 3(a), first, the transparent resin layer 1 is formed on the base material 5 by any appropriate method. The structure of the base material 5 is not particularly limited as long as it can support the transparent resin layer 1 and the porous layer 2 so that the formation of the porous layer 2 can be performed stably. Any suitable resin film may be employed as the base material 5. Specific examples of materials that are the main components of the resin film include cellulose resins such as triacetylcellulose (TAC); polyesters such as polyethylene terephthalate (PET); polyvinyl alcohols; polycarbonates; polyamides; polyimides; Examples include polyethersulfone type; polysulfone type; polystyrene type; polynorbornene type; polyolefin type; (meth)acrylic type; and acetate type. Further, thermosetting resins or ultraviolet curable resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone resins may also be mentioned.
The thickness of the base material 5 is, for example, more than 5 μm, preferably 10 μm or more, and, for example, 100 μm or less.

In one embodiment, a resin solution (coating liquid) in which the above resin material is dissolved in a solvent is applied onto the base material 5 to form a coating film, and then the coating film is dried to form a transparent resin. Form layer 1. In this case, the transparent resin layer 1 is a coating film. When the transparent resin layer is a coating film, the smoothness of the surface of the transparent resin layer can be improved. Therefore, in the manufactured optical laminate, it is possible to suppress the occurrence of false irregularities at the interface between the porous layer and the transparent resin layer, and to prevent scattering at the interface between the porous layer and the transparent resin layer when guiding light. can be stably suppressed.
Any suitable solvent that can dissolve the resin material may be selected as the solvent. Examples of the solvent include water; alcohols; ketones; esters; ethers; and aromatic hydrocarbons such as toluene, preferably water.
The concentration of the resin material in the resin solution is, for example, 1% by mass or more and 90% by mass or less.
The viscosity of the resin solution at 25° C. is, for example, 10 mPa·s or more, preferably 50 mPa·s or more, and is, for example, 3 Pa·s or less, preferably 1 Pa·s or less. If the viscosity of the resin solution is within the above range, it can be smoothly coated onto the substrate.
Note that the transparent resin layer can also be formed on the base material by attaching a separately prepared transparent resin layer to the base material.

Next, as shown in FIG. 3(b), the porous layer 2 is formed on the surface of the transparent resin layer 1 opposite to the base material 5 by any appropriate method. That is, the porous layer 2 is formed on the transparent resin layer 1 while the transparent resin layer 1 is supported by the base material 5 . Therefore, the porous layer 2 can be formed stably.

In one embodiment, the step typically includes a precursor forming step of forming a void structure, which is a precursor of a porous layer (void layer), on the transparent resin layer, and a step of forming the void structure after the precursor forming step. It includes a crosslinking reaction step of causing a crosslinking reaction inside the precursor. The process includes a step of preparing a containing liquid containing microporous particles (hereinafter sometimes referred to as "microporous particle containing liquid" or simply "containing liquid"), and a drying process of drying the containing liquid. The method further includes a step of forming a precursor by chemically bonding microporous particles in the dried body to each other in the precursor forming step. The containing liquid is not particularly limited, and is, for example, a suspension containing microporous particles. In the following, a case will be mainly described in which the microporous particles are a pulverized product of a gel-like compound, and the void layer is a porous body (preferably a silicone porous body) containing the pulverized product of the gel-like compound. However, the porous layer can be similarly formed even when the microporous particles are other than the pulverized gel-like compound.

According to the above method, for example, a porous layer (void layer) having a very low refractive index is formed. The reason is presumed to be as follows, for example. However, this assumption does not limit the method of forming the porous layer.

Since the above-mentioned pulverized product is obtained by pulverizing a gel-like silicon compound, the three-dimensional structure of the gel-like silicon compound before pulverization is in a state where it is dispersed into a three-dimensional basic structure. Furthermore, in the above method, a precursor of a porous structure based on a three-dimensional basic structure is formed by coating or printing a crushed product of a gel-like silicon compound on a transparent resin layer. That is, according to the above method, a new porous structure (three-dimensional basic structure) different from the three-dimensional structure of the gel-like silicon compound is formed by coating the crushed material. Therefore, the finally obtained void layer can have a low refractive index that functions to the same degree as, for example, an air layer. Furthermore, in the above method, the three-dimensional basic structure is fixed because the crushed materials are chemically bonded to each other. Therefore, the finally obtained void layer can maintain sufficient strength and flexibility despite having a structure having voids. Details of the specific structure and formation method of the porous layer are described in, for example, International Publication No. 2019/151073. The description of the publication is incorporated herein by reference.

In one embodiment, this step is carried out by applying the above-described microporous particle-containing liquid to the entire surface of the transparent resin layer 1 opposite to the base material 5, and then drying the coating film. The microporous particle-containing liquid preferably does not dissolve the resin material constituting the transparent resin layer. Therefore, it is possible to stably suppress the resin material constituting the transparent resin layer from entering the voids of the porous layer.
In addition, when a liquid containing microporous particles is applied to a transparent resin layer and the coating film is dried to form a porous layer, it is possible to stably prevent pseudo-irregularities from occurring at the interface between the porous layer and the transparent resin layer. Can be suppressed.

Next, as shown in FIG. 3(c), an adhesive layer 3 is formed on the surface of the porous layer 2 opposite to the transparent resin layer 1 by any suitable method. In one embodiment, the adhesive constituting the adhesive layer 3 is applied to a resin film and dried to form the adhesive layer 3 on the resin film, and then the adhesive layer 3 is formed from the resin film into a porous layer. Transfer to 2.

Next, as shown in FIG. 3(d), the base material 5 is peeled off from the transparent resin layer 1. The peeling force when peeling the base material 5 from the transparent resin layer 1 (hereinafter sometimes referred to as base material peeling force) is the peeling force when peeling the transparent resin layer 1 from the porous layer 2 (hereinafter sometimes referred to as base material peeling force). (sometimes referred to as transparent resin layer peeling force). The difference between the transparent resin layer peeling force and the base material peeling force is, for example, 0.1 N/25 mm or more, preferably 0.5 N/25 mm or more, and more preferably 1.0 N/25 mm or more. When the base material peeling force is smaller than the transparent resin layer peeling force, when the base material is peeled from the transparent resin layer, it is possible to suppress the transparent resin layer from peeling off from the porous layer as the base material is peeled off.
The peeling force when peeling the base material 5 from the transparent resin layer 1 is preferably less than 1 N/25 mm, more preferably 0.5 N/25 mm or less.
Note that when the transparent resin layer has a laminated structure of two or more layers, a part of the transparent resin layer may be peeled off together with the base material as long as at least one layer is in close contact with the porous layer.

Next, as shown in FIG. 3(e), an adhesive layer 4 is formed on the surface of the transparent resin layer 1 opposite to the porous layer 2 by any appropriate method. In one embodiment, after forming the adhesive layer 4 on the resin film by applying the pressure-sensitive adhesive or adhesive constituting the adhesive layer 4 to the resin film and drying it, the adhesive layer 4 is transferred from the resin film to the transparent resin layer 1. Transfer to. Alternatively, the second adhesive layer can be formed by applying an adhesive to the transparent resin layer and drying it.

Through the above steps, an optical laminate having a configuration of adhesive layer/porous layer/transparent resin layer/adhesive layer is manufactured.

The color shift value Δxy when light is guided through the transparent resin layer 1 included in the optical laminate is, for example, 0.1 or less, preferably 0.08 or less, and more preferably 0.05 or less. The color shift value Δxy can be measured using a spectroradiometer, for example. If the color shift value Δxy is equal to or less than the above upper limit, it is possible to suppress a change in the color of the emitted light from the light incident side in the longitudinal direction.

The scattering value (hereinafter referred to as light guide scattering value) when light is guided through the transparent resin layer 1 of the optical laminate is, for example, less than 50, preferably less than 30, and more preferably 25 or less. be. The light guide scattering value can be calculated, for example, by guiding light with the optical laminate bonded to the light guide member using an adhesive layer and measuring the emitted light from a predetermined position with a spectroradiometer. If the light guide scattering value is within such a range, brightness loss can be sufficiently suppressed when light is guided using the optical laminate. Therefore, the optical laminate can be suitably applied to applications where tolerance standards regarding brightness loss are strict. The smaller the light guide scattering value is, the more preferable it is. The lower limit of the guided scattering value is typically 0, such as 1, or 5, for example.

G. Usage form of optical laminate An optical laminate according to an embodiment of the present invention is typically applicable to an optical product 200 including a plurality of optical films, and can be introduced between adjacent optical films. In one embodiment, as shown in FIG. 2, the optical laminate 100 is attached to the first optical film 10 by the adhesive layer 4 and attached to the second optical film 11 by the adhesive layer 3. ing. Thereby, the optical laminate 100 is interposed between the first optical film 10 and the second optical film 11. Therefore, desired optical characteristics can be imparted to the optical product 200 while reducing the size of the optical product 200.

As shown in FIG. 4, in one embodiment, the optical laminate is applied to an optical member (more specifically, a light guide device) including a light guide member (typically a light guide plate) into which light enters. It is possible. In the illustrated example, the optical member 201 is an optical laminate with a light guide member, and includes the optical laminate 100 and the light guide member 13 . The light guide member 13 is located on the opposite side of the transparent resin layer 1 with respect to the adhesive layer 4 . The light guide member 13 is typically capable of propagating the light incident from the light source 12 (typically an LED) in a predetermined direction (the left-right direction in FIG. 4). According to such a configuration, when light is incident on the light guide member and guided, even if the light reaches the interface between the transparent resin layer and the porous layer, scattering toward the porous layer side is suppressed. Therefore, brightness loss due to light guiding can be sufficiently suppressed.
The light guide member 13 is bonded directly or indirectly to the adhesive layer 4 side of the optical laminate 100. In the illustrated example, the light guide member 13 is directly attached to the adhesive layer 4 side of the optical laminate 100. In other words, the optical laminate 100 is directly attached to the light guide member 13 by the adhesive layer 4. There is. The light guide member 13 may be indirectly bonded to the adhesive layer 4 side of the optical laminate 100. In other words, the optical laminate 100 is located between the optical laminate 100 and the light guide member 13. It may be attached to another transparent member. Although not shown, an optical film may be attached to the adhesive layer 3.
The method for manufacturing such an optical member 201 includes a step of preparing an optical laminate by the above-described method for manufacturing an optical laminate; and a step of providing a light guide member 13 on the side opposite to the transparent resin layer 1 with respect to the adhesive layer 4. Contains and; In the step of providing the light guide member 13, the optical laminate 100 may be directly attached to the light guide member 13 using the adhesive layer 4, or another transparent member may be arranged between the optical laminate 100 and the light guide member 13. Alternatively, the optical laminate 100 may be indirectly attached to the light guide member 13 via the adhesive layer 4 and other transparent members.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. The method for measuring each characteristic is as follows. Furthermore, unless otherwise specified, "%" and "parts" in the examples are based on mass.

(1) Refractive index Before pasting the adhesive layer onto the porous layer, the porous layer was formed and then cut into a size of 25 mm x 50 mm. pasted on the surface. The center part (about 20 mm in diameter) of the back surface of the glass plate was filled in with black marker to prepare a sample that did not reflect on the back surface of the glass plate. The sample was set in an ellipsometer (manufactured by J.A. Woollam Japan: VASE), and the refractive index was measured at a wavelength of 550 nm and an incident angle of 50 to 80 degrees.
On the other hand, to measure the refractive index in a structure with an adhesive, after the adhesive layer is pasted on the formed porous layer, a prism coupler (manufactured by Metricon) is used to inject a laser (λ = 407 nm), calculate the refractive index at 407 nm from the measured value of the total reflection angle, and convert the refractive index at 550 nm from the wavelength dispersion of the refractive index separately calculated using an ellipsometer (manufactured by J.A. Woollam). did.

(2) Optical Durability The optical laminates obtained in each Example and each Comparative Example were placed in an oven at 65° C. and 95% RH (relative humidity), and a 1000-hour heating and humidification durability test was conducted. The degree of increase in refractive index from the initial stage after the heating and humidification durability test was measured, and a laminate with an increase width of 0.05 or less was rated as ○, and a laminate with an increase width of more than 0.05 was rated as ×. The results are shown in Table 1.

(3) Measurement of color shift value After bonding the optical laminate obtained in each example and each comparative example to a glass plate that plays a role of light guide, light enters the end face of the glass plate from the LED and guides the optical laminate. The x value and y value of the light emitted from the diffuser plate bonded to the center of the optical laminate (glass plate with optical laminate) was measured using a radiance meter. The amount of color shift (Δxy value) is the x value and y value when light is guided to the glass plate with the optical laminate (x _A , y _A ), and the x value when light is guided only to the glass plate. It was calculated as the maximum value of the following formula: {( _{x A −x B} ) ² +(y _A −y _B ) ² } ^1/2 , and the y value was (x B , y _B ). The results are shown in Table 1.

(4) Measurement of light guide scattering value After the optical laminate obtained in each example and each comparative example was bonded to a glass plate with a second adhesive layer, light was incident on the end face of the glass plate from the LED, The light emitted from the diffuser plate bonded to the center of the light guide laminate (glass plate with optical laminate) was measured using a radiance meter. Then, the L value was calculated as a light guide scattering value. The results are shown in Table 1.

[Production Example 1] Preparation of coating solution for forming a porous layer (1) Gelation of silicon compound 0.0 g of methyltrimethoxysilane (MTMS), a precursor of a silicon compound, was added to 2.2 g of dimethyl sulfoxide (DMSO). Mixed liquid A was prepared by dissolving .95g. Add 0.5 g of 0.01 mol/L oxalic acid aqueous solution to this mixed solution A, and stir at room temperature (23°C) for 30 minutes to hydrolyze MTMS, resulting in a mixture containing tris(hydroxy)methylsilane. Liquid B was produced.
After adding 0.38 g of 28% by mass ammonia water and 0.2 g of pure water to 5.5 g of DMSO, further add the above mixture B and stir at room temperature (23 ° C.) for 15 minutes. Then, tris(hydroxy)methylsilane was gelated to obtain a mixed solution C containing a gelled silicon compound.
(2) Aging Treatment The mixture C containing the gelled silicon compound prepared as described above was incubated as it was at 40° C. for 20 hours to perform an aging treatment.
(3) Grinding Process Next, the gel-like silicon compound that had been aged as described above was ground into granules with a size of several mm to several cm using a spatula. Next, 40 g of isobutyl alcohol (IBA) was added to the mixture C, and after stirring gently, the mixture was allowed to stand at room temperature for 6 hours, and the solvent and catalyst in the gel were decanted. By performing the same decantation treatment three times, the solvent was replaced and a mixed solution D was obtained. Next, the gelled silicon compound in the mixture D was pulverized (high-pressure medialess pulverization). The pulverization process (high-pressure media-less pulverization) uses a homogenizer (manufactured by SMT Co., Ltd., trade name "UH-50"), and 1.85 g of the gel-like compound in mixture D and IBA are placed in a 5 cc screw bottle. After weighing 15 g, it was pulverized for 2 minutes at 50 W and 20 kHz.
By this pulverization treatment, the gel-like silicon compound in the mixed liquid D was pulverized, so that the mixed liquid D became a sol liquid E of the pulverized product. When the volume average particle size, which indicates the particle size variation of the pulverized material contained in the sol liquid E, was confirmed using a dynamic light scattering nanotrack particle size analyzer (manufactured by Nikkiso Co., Ltd., model UPA-EX150), it was found to be 0.10 μm to 0. It was .30 μm. Furthermore, to 0.75 g of sol solution E, 0.062 g of a 1.5% by mass MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd.: trade name WPBG266) was added to 0.062 g of a bis(trimethoxysilyl ) A 5% MEK solution in hexane was added at a ratio of 0.036 g to obtain a coating solution for forming a porous layer.

[Production Example 2] Preparation of the first adhesive layer In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser, 90.7 parts of butyl acrylate, 6 parts of N-acryloylmorpholine, and acrylic acid were placed. 3 parts, 0.3 parts of 2-hydroxybutyl acrylate, and 0.1 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator were charged together with 100 g of ethyl acetate, and nitrogen gas was introduced while stirring gently. After replacing the flask with nitrogen, the temperature of the liquid in the flask was maintained at around 55° C., and a polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. Per 100 parts of the solid content of the obtained acrylic polymer solution, 0.2 parts of isocyanate crosslinking agent (Coronate L manufactured by Nippon Polyurethane Industries, an adduct of tolylene diisocyanate of trimethylolpropane), benzoyl peroxide (Japan An acrylic adhesive solution containing 0.3 part of Niper BMT (manufactured by Yushi Co., Ltd.) and 0.2 part of γ-glycidoxypropylmethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.: KBM-403) was prepared. Next, the above acrylic adhesive solution was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., thickness: 38 μm) so that the thickness of the first adhesive layer after drying was It was applied to a thickness of 10 μm and dried at 150° C. for 3 minutes to form a first adhesive layer. The storage modulus of the obtained adhesive was 1.3×10 ⁵ (Pa).

[Production Example 3] Preparation of second adhesive layer In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser, 99 parts of butyl acrylate, 1 part of 4-hydroxybutyl acrylate, and a polymerization initiator were placed. 0.1 part of 2,2'-azobisisobutyronitrile was charged together with 100 parts of ethyl acetate, and nitrogen gas was introduced while stirring gently to replace nitrogen, and the temperature of the liquid in the flask was brought to around 55°C. The polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. Per 100 parts of the solid content of the obtained acrylic polymer solution, 0.1 part of isocyanate crosslinking agent (Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Takeda Chemical Co., Ltd.), benzoyl peroxide (manufactured by NOF Corporation), A solution of an acrylic adhesive composition was prepared by blending 0.1 part of Niper BMT) and 0.2 part of γ-glycidoxypropylmethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.). Next, a solution of the above acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (separator film: manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) treated with a silicone release agent, and heated at 150°C for 3 minutes. After drying, a second adhesive layer having a thickness of 12 μm was formed on the surface of the separator film. The storage modulus of the obtained adhesive was 8.2×10 ⁴ (Pa).

[Example 1]
After coating a polyvinyl alcohol (PVA) aqueous solution on the base material (PET resin film), the coating film was dried. As a result, a PVA layer as a transparent resin layer was formed on the base material. The thickness of the PVA layer was 3 μm.
Next, the coating solution for forming a porous layer of Production Example 1 was uniformly applied to the surface of the PVA layer opposite to the base material, and then the coating film was dried. This formed a porous layer on the PVA layer. The refractive index of the porous layer was 1.19. The thickness of the porous layer was 0.9 μm.
Next, the first adhesive layer obtained in Production Example 2 was attached to the porous layer.
Next, the PET base material was peeled from the PVA layer at a peel angle of 180° and a peel rate of 300 mm/min. The peeling force at this time was measured using an autograph tensile tester. The results are shown in Table 1.
Next, the second adhesive layer obtained in Production Example 3 was attached to the surface of the PVA layer opposite to the porous layer.
Through the above steps, an optical laminate having the structure of first adhesive layer/porous layer/transparent resin layer/second adhesive layer was obtained.

[Example 2]
An optical laminate was obtained in the same manner as in Example 1, except that a polymethyl methacrylate (PMMA) aqueous solution was used in place of the PVA aqueous solution and a PMMA layer as a transparent resin layer was formed on the base material.

[Example 3]
An optical laminate was obtained in the same manner as in Example 1, except that an ethanol solution of polyvinyl acetal resin was used instead of the PVA aqueous solution to form a polyvinyl acetal resin layer as a transparent resin layer on the base material.

[Comparative example 1]
After the coating solution for forming a porous layer of Production Example 1 was uniformly applied onto a base material (acrylic resin film) having a thickness of 30 μm, the coating film was dried. This formed a porous layer on the base material. Next, the first adhesive layer obtained in Production Example 2 was attached to the porous layer. Next, the second adhesive layer obtained in Production Example 3 was attached to the surface of the base material opposite to the porous layer.
Through the above steps, an optical laminate having the structure of first adhesive layer/porous layer/substrate/second adhesive layer was obtained.

[Comparative example 2]
The coating solution for forming a porous layer of Production Example 1 was uniformly applied onto a 100 μm thick base material (cycloolefin (COP) film; ZF16; manufactured by Nippon Zeon Co., Ltd.), and then the coating film was dried. This formed a porous layer on the base material. Next, the first adhesive layer obtained in Production Example 2 was attached to the porous layer. Next, the base material was peeled off from the porous layer, and the second adhesive layer obtained in Production Example 3 was attached to the peeled surface.
Through the above steps, an optical laminate having the structure of first adhesive layer/porous layer/second adhesive layer was obtained.

[Comparative example 3]
Example 1 except that a cycloolefin resin layer as a transparent resin layer was formed on the base material using a limonene solution of cycloolefin resin (COP; Zeonex K26R; manufactured by Nippon Zeon Co., Ltd.) instead of the PVA aqueous solution. An optical laminate was obtained in the same manner as above.

As is clear from Table 1, according to the examples of the present invention, by providing a transparent resin layer with a thickness of 20 μm or less between the porous layer and the adhesive layer, it is possible to reduce the thickness of the optical laminate. It can be seen that it is possible to achieve excellent optical durability. Furthermore, when the optical laminate of the example is attached to a light guide member (glass plate) with a second adhesive layer and light is guided, the light guide scattering value can be suppressed and the brightness loss can be significantly suppressed. I understand.

The optical laminate according to the embodiment of the present invention can be used for various optical products, and can be particularly suitably used for optical products including a plurality of optical films.

1 Transparent resin layer 1a Barrier layer 2 Porous layer 3 Adhesive layer 4 Adhesive layer 100 Optical laminate 200 Optical product 201 Optical member

Claims (13)

a transparent resin layer having a thickness of 20 μm or less;
a porous layer that is provided directly on one side in the thickness direction of the transparent resin layer and has a refractive index of 1.25 or less;
an adhesive layer provided directly on the surface of the porous layer opposite to the transparent resin layer;
an adhesive layer provided directly on the surface of the transparent resin layer opposite to the porous layer;
An optical laminate, wherein a peeling force when peeling the transparent resin layer from the porous layer is 1N/25mm or more. The optical laminate according to claim 1, wherein the arithmetic mean roughness Ra of the contact surface of the porous layer with the transparent resin layer is 300 nm or less. The optical laminate according to claim 1, wherein the resin material constituting the transparent resin layer has a polar group. 2. The optical laminate according to claim 1, wherein the transparent resin layer has a barrier function that prevents components constituting the adhesive layer from permeating into the porous layer. The optical laminate according to claim 4, wherein the transparent resin layer has a smaller porosity than the porous layer. The optical laminate according to claim 1, wherein the adhesive layer is made of an adhesive having a storage modulus of 1.0×10 ⁵ (Pa) or more at 23° C. The optical laminate according to claim 1, wherein a color shift value Δxy when light is guided through the transparent resin layer is 0.1 or less. The optical laminate according to claim 1, wherein a scattering value when light is guided through the transparent resin layer is less than 50. The optical laminate according to any one of claims 1 to 8,
An optical member comprising: a light guide member located on the opposite side of the transparent resin layer with respect to the adhesive layer. forming a transparent resin layer having a thickness of 20 μm or less on the base material;
forming a porous layer having a refractive index of 1.25 or less on the surface of the transparent resin layer opposite to the base material;
forming an adhesive layer on the surface of the porous layer opposite to the transparent resin layer;
Peeling the base material from the transparent resin layer;
A method for manufacturing an optical laminate, the method comprising: forming an adhesive layer on a surface of the transparent resin layer opposite to the porous layer. The method for manufacturing an optical laminate according to claim 10, wherein a peeling force when peeling the base material from the transparent resin layer is smaller than a peeling force when peeling the transparent resin layer from the porous layer. In the step of forming a transparent resin layer on the substrate, a solution in which the resin material of the transparent resin layer is dissolved is applied onto the substrate to form a coating film, and then the coating film is dried, The method for manufacturing an optical laminate according to claim 10, wherein the transparent resin layer is formed. preparing an optical laminate by the method for producing an optical laminate according to any one of claims 10 to 12;
providing a light guide member on the side opposite to the transparent resin layer with respect to the adhesive layer;
A method for manufacturing an optical member.

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