Optical member, and backlight unit and image display device using the same

Abstract

Provided is an optical member that can maintain excellent properties of a low-refractive layer and that has reduced display quality caused by abrasion or scratches due to vibration. The optical member of the present invention has a light guide plate having an end surface on which light from a light source is incident and an exit surface from which the light after incidence is emitted, and a reflection plate that is attached to the side of the light guide plate opposite the exit surface via a double-coated adhesive film, wherein the double-coated adhesive film has, in order from the light guide plate side, a first adhesive layer, a low-refractive layer, and a second adhesive layer, and a surface treatment layer is formed on the side of the reflection plate opposite the double-coated adhesive film.

Description

Technical Field

[0001] This invention relates to optical components, as well as backlight units and image display devices using the optical components. Background Technology

[0002] In optical devices that use light guide plates to guide light (e.g., image display devices, lighting devices), techniques are known of laminating the light guide plate with peripheral optical components (e.g., reflectors, diffusers, prisms, light-guiding films) through a low-refractive-index layer. According to such techniques, higher light utilization efficiency has been reported compared to simply using adhesives for lamination, by using a low-refractive-index layer. In automotive and / or entertainment applications (e.g., video game consoles, pinball machines, etc.), the use of low-refractive-index layers for the integration of such optical components is also desirable. However, in automotive and / or entertainment applications, the integration of optical components (e.g., light guide plate and reflector) can lead to concerns about reduced display quality due to wear or scratches between the optical components and / or between the optical components and the housing caused by vibrations during use.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 10-62626 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] The present invention was made to solve the above-mentioned existing problems, and its main objective is to provide an optical component that can maintain the excellent properties of a low refractive index layer and suppress the reduction in display quality caused by wear or scratches due to vibration.

[0008] Problem Solving Methods

[0009] The optical component of the embodiments of the present invention has:

[0010] A light guide plate having an incident end face from a light source and an exit face for escaping the incident light; and

[0011] A reflector, which is bonded to the side of the light guide plate opposite to the emitting surface, through a double-sided adhesive film.

[0012] The double-sided adhesive film has a first adhesive layer, a low refractive index layer and a second adhesive layer in sequence from the light guide plate side. In the optical component, a surface treatment layer is formed on the side of the reflector opposite to the double-sided adhesive film.

[0013] In one embodiment, the coefficient of dynamic friction of the surface treatment layer is 1.0 or less.

[0014] In one embodiment, the surface treatment layer is a hard coating with a pencil hardness of H or higher. In another embodiment, the surface treatment layer further has an outermost layer containing fluorine on the surface of the hard coating opposite to the reflector.

[0015] According to another aspect of the present invention, a backlight unit is provided, the backlight unit having: the aforementioned optical components and a light source, the light source being configured to face the aforementioned end face of the aforementioned light guide plate.

[0016] According to another aspect of the present invention, an image display device is provided, the image display device having: the backlight unit described above, and an image display panel disposed on the emission surface side of the light guide plate described above.

[0017] The effects of the invention

[0018] According to the present invention, in an optical component formed by integrating a light guide plate and a reflector plate via a double-sided adhesive film containing a low refractive index layer, by providing a given surface treatment layer on the surface of the reflector plate, it is possible to achieve an optical component that maintains the excellent properties of the low refractive index layer and suppresses the reduction in display quality caused by wear or scratches due to vibration. Attached Figure Description

[0019] Figure 1 This is a cross-sectional schematic diagram of an optical component according to one embodiment of the present invention.

[0020] Symbol Explanation

[0021] 10 Light guide plates

[0022] 20 Double-sided adhesive film

[0023] 21 First adhesive layer

[0024] 22 Low-refractive-index layer

[0025] 23 Second adhesive layer

[0026] 24 Substrate

[0027] 30 Reflector

[0028] 40 Surface treatment layer

[0029] 100 Optical Components Detailed Implementation

[0030] The embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0031] A. Overall Composition of Optical Components

[0032] Figure 1 This is a cross-sectional schematic diagram of an optical component according to one embodiment of the present invention. The optical component 100 shown in the figure includes a light guide plate 10 and a reflector 30 bonded to the light guide plate 10 via a double-sided adhesive film 20. The double-sided adhesive film 20 has, sequentially from the light guide plate 10 side, a first adhesive layer 21, a low-refractive-index layer 22, and a second adhesive layer 23. In practical use, a substrate 24 is disposed between the low-refractive-index layer 22 and the second adhesive layer 23. More specifically, the low-refractive-index layer 22 can be formed on the surface of the substrate 24, and the first adhesive layer 21 and the second adhesive layer 23 can be disposed on both sides of the laminate of the substrate 24 and the low-refractive-index layer 22. In the optical component 100, a surface treatment layer 40 is formed on the side of the reflector 30 opposite to the double-sided adhesive film 20.

[0033] The light guide plate 10 has an end face 10a from which light from the light source is incident and an exit face 10b from which the incident light exits. That is, typically, the light guide plate 10 is a side-lighting type where light enters from the end face 10a. More specifically, the light guide plate 10 causes light incident from the light source to the end face 10a to be internally reflected, etc., while simultaneously guiding the light to the end side opposite to the end face 10a. During this light guiding process, the light is slowly emitted from the exit face 10b. Typically, an emission pattern is provided on the exit face 10b. For example, an uneven shape can be used for the emission pattern. Furthermore, typically, a light-guiding pattern is provided on the side of the light guide plate opposite to the emission surface. For example, a white dot can be used for the light-guiding pattern. Any suitable light guide plate can be used as the light guide plate. As the material constituting the light guide plate, any suitable material can be used as long as it can efficiently guide the light irradiated from the light source. Materials used to make up the light guide plate include, for example, acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resin, polyethylene terephthalate (PET) resin, styrene resin, and glass.

[0034] As a reflector, any suitable reflector can be used. For example, the reflector can be a specular reflector or a diffuse reflector. Specific examples of reflectors include resin sheets with high reflectivity (e.g., acrylic sheets), thin metal sheets or foils such as aluminum or stainless steel, vapor-deposited sheets with aluminum, silver, etc., deposited on a substrate such as a polyester resin film, laminates of a substrate such as a polyester resin film and metal foils such as aluminum, and resin films with cavities (pores) formed inside.

[0035] The double-sided adhesive film and surface treatment layer constituting the optical components will be described in detail below. For the light guide plate and reflector, a structure known in the industry can be used, therefore, descriptions other than those described above are omitted.

[0036] B. Double-sided adhesive film

[0037] B-1. Overview of Double-Sided Adhesive Film

[0038] As described in section A above, the double-sided adhesive film comprises a first adhesive layer 21, a low-refractive-index layer 22, a substrate 24 used in actual application, and a second adhesive layer 23 from the light guide plate 10 side. The porosity of the low-refractive-index layer 22 is, for example, 40% by volume or more. The storage modulus of the first adhesive layer at 23°C is, for example, 1.0 × 10⁻⁶. 5 (Pa)~1.0×10 7 (Pa), the storage modulus of the second adhesive layer at 23°C is, for example, 1.0 × 10⁻⁶. 5 (Pa) and below. By increasing the storage modulus of the first adhesive layer adjacent to the low-refractive-index layer as described above, adhesive ingress into the voids of the low-refractive-index layer can be prevented. Therefore, the refractive index of the low-refractive-index layer can be maintained at a low level, thereby preserving its effect. Furthermore, by reducing the storage modulus of the second adhesive layer, which is another adhesive layer, as described above, damage to the low-refractive-index layer caused by vibration can be suppressed. The effect of suppressing damage to the low-refractive-index layer caused by vibration is particularly significant when the optical component is used in automotive and / or recreational applications.

[0039] In one embodiment, the ratio of the thickness of the low-refractive-index layer to the total thickness of the adhesive layer present in the double-sided adhesive film is, for example, 0.10% to 5.00%, preferably 0.11% to 4.50%, and more preferably 0.12% to 4.00%. If the thickness ratio is within such a range, damage to the low-refractive-index layer caused by vibration can be suppressed more effectively. More specifically, in automotive and / or recreational applications, where significant vibrations exist not only longitudinally but also laterally, damage to the low-refractive-index layer due to lateral strength differences is particularly well suppressed.

[0040] B-2. Substrate

[0041] Typically, the substrate can be composed of a film or sheet of resin (preferably a transparent resin). Representative examples of such resins include thermoplastic resins and reactive resins (e.g., ionizing radiation-curing resins). Specific examples of thermoplastic resins include: polymethyl methacrylate (PMMA), (meth)acrylic resins such as polyacrylonitrile, polycarbonate (PC) resins, polyester resins such as PET, cellulose resins such as cellulose triacetate (TAC), cyclic polyolefin resins, and styrene resins. Specific examples of ionizing radiation-curing resins include epoxy acrylate resins and urethane acrylate resins. These resins can be used alone or in combination of two or more.

[0042] The thickness of the substrate is, for example, 10 μm to 100 μm, preferably 10 μm to 50 μm.

[0043] The refractive index of the substrate is preferably 1.47 or higher, more preferably 1.47 to 1.60, and even more preferably 1.47 to 1.55. If it is within such a range, the light can be introduced into the image display unit without adversely affecting the light emitted from the light guide plate.

[0044] B-3. ​​Low Refractive Index Layer

[0045] Typically, the low-refractive-index layer has internal voids. The porosity of the low-refractive-index layer, as described above, is 40% by volume or more, typically 50% by volume or more, preferably 70% by volume or more, and more preferably 80% by volume or more. On the other hand, the porosity is, for example, 90% by volume or less, preferably 85% by volume or less. By keeping the porosity within the above range, the refractive index of the low-refractive-index layer can be made to reach an appropriate range. The porosity is a value obtained by calculating the porosity using the Lorentz-Lorenz formula based on the refractive index value measured using an ellipsometry.

[0046] The refractive index of the low-refractive-index layer is preferably 1.30 or less, more preferably 1.20 or less, and even more preferably 1.15 or less. The lower limit of the refractive index can be, for example, 1.01. Within such a range, very good light utilization efficiency can be achieved in the laminated structure of the light guide plate and peripheral components obtained via an optical laminate with adhesive layers on both sides. Unless otherwise specified, the refractive index refers to the refractive index measured at a wavelength of 550 nm. The refractive index is a value measured by the method described in [Manufacturing Example 4] of the following embodiments.

[0047] The low-refractive-index layer can be constructed using any suitable configuration as long as it possesses the desired porosity and refractive index. The low-refractive-index layer is preferably formed by coating or printing. Materials constituting the low-refractive-index layer can be, for example, those described in International Patent Publication No. 2004 / 113966, Japanese Patent Application Publication No. 2013-254183, and Japanese Patent Application Publication No. 2012-189802. Specifically, examples include: silica compounds; hydrolyzable silanes, their partially hydrolysates and dehydration condensates; organic polymers; silicon compounds containing silanol groups; active silica obtained by contacting silicates with acids or ion-exchange resins; polymerizable monomers (e.g., (meth)acrylic acid monomers and styrene monomers); curable resins (e.g., (meth)acrylic acid resins, fluorinated resins, and urethane resins); and combinations thereof. The low-refractive-index layer can be formed by coating or printing a solution or dispersion of such materials.

[0048] The size of the voids (pores) in the low refractive index layer refers to the diameter of the major axis of the void (pore) and the diameter of the minor axis. The size of the void (pore) is, for example, 2 nm to 500 nm. The size of the void (pore) is, for example, 2 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more. On the other hand, the size of the void (pore) is, for example, 500 nm or less, preferably 200 nm or less, and even more preferably 100 nm or less. The range of the void (pore) size 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 void (pore) can be adjusted to the desired size according to the purpose and application. The size of the void (pore) can be quantified by the BET test method.

[0049] The size of the pores can be quantified using the BET test method. Specifically, 0.1 g of the sample (the formed pore layer) is placed in the capillary of a surface area measuring device (McMerrittek: ASAP2020), and then subjected to reduced pressure drying at room temperature for 24 hours to degas the gas within the pore structure. Then, by adsorbing nitrogen onto the sample and plotting adsorption isotherms, the pore distribution can be determined. The pore size can then be evaluated.

[0050] The haze of the low-refractive-index layer 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. The range of haze is, for example, 0.1% or more and less than 5%, preferably 0.2% or more and less than 3%. The haze can be measured, for example, by the method described below. It should be noted that haze is an indicator of the transparency of the low-refractive-index layer.

[0051] The void layer (low refractive index layer) was cut into 50mm × 50mm pieces and placed in a haze meter (Murakami Color Technology Research Institute Co., Ltd.: HM-150) to measure the haze. The haze value was calculated using the following formula.

[0052] Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] × 100 (%)

[0053] As a low-refractive-index layer with internal voids, examples include low-refractive-index layers having at least a porous layer and / or an air layer. The porous layer typically comprises aerogels, and / or particles (e.g., hollow microparticles and / or porous particles). The low-refractive-index layer can preferably be a nanoporous layer (specifically, more than 90% of the micropores have a diameter of 10...). -1 nm~10 3 Porous layers in the nm range).

[0054] As the aforementioned particles, any suitable particles can be used. The particles are typically formed from silica-based compounds. Examples of particle shapes include spherical, plate-like, needle-like, rope-like, and grape-like shapes. Examples of rope-like particles include: multiple particles having spherical, plate-like, or needle-like shapes linked together to form a beaded structure; short fibrous particles (e.g., the short fibrous particles described in Japanese Patent Application Publication No. 2001-188104); and combinations thereof. Rope-like particles can be linear or branched. Examples of grape-like particles include: multiple spherical, plate-like, and needle-like particles aggregated to form grape-like clusters. The shape of the particles can be confirmed by observation using, for example, a transmission electron microscope.

[0055] The thickness of the low-refractive-index layer is preferably 0.2 μm to 5 μm, more preferably 0.3 μm to 3 μm. When the thickness of the low-refractive-index layer is within this range, the anti-breakage effect of the present invention becomes significant. Furthermore, the aforementioned desired thickness ratio can be easily achieved.

[0056] As described above, the low-refractive-index layer can typically be formed by coating or printing. In this configuration, the low-refractive-index layer can be continuously applied roll-to-roll. The low-refractive-index layer can be formed over the entire surface of the substrate or in a given pattern. When the low-refractive-index layer is formed in a given pattern, coating is performed, for example, using a mask with the given pattern. Printing can be performed in any suitable manner. Specifically, printing methods can be either formatted printing methods such as gravure printing, offset printing, or aniline printing, or formatless printing methods such as inkjet printing, laser printing, or electrostatic printing.

[0057] The following describes an example of the specific structure of the low-refractive-index layer. The low-refractive-index layer of this embodiment includes one or more structural units that form a fine porous structure, and these structural units are chemically bonded together by a catalytic reaction. Examples of shapes for the structural units include particle-like, fibrous, rod-like, and plate-like shapes. The structural units may have only one shape, or they may combine two or more shapes. The following description focuses primarily on the case where the low-refractive-index layer is a porous layer of the aforementioned microporous particles chemically bonded together.

[0058] Such a porous layer can be formed by chemically bonding microporous particles together during the porous layer formation process. It should be noted that in embodiments of the present invention, the shape of the "particles" (e.g., the aforementioned microporous particles) is not particularly limited; for example, they can be spherical or other shapes. Furthermore, in embodiments of the present invention, the aforementioned microporous particles can be, for example, sol-gel bead-like particles, nanoparticles (hollow nano-silica / nano-hollow sphere particles), nanofibers, etc. Microporous particles typically include inorganic materials. Specific examples of inorganic materials include: silicon (Si), magnesium (Mg), aluminum (Al), titanium (Ti), zinc (Zn), and zirconium (Zr). They can be used alone or in combination of two or more. In one embodiment, the aforementioned microporous particles are, for example, microporous particles of a silicon compound, and the aforementioned porous body is, for example, an organosilicon porous body. The aforementioned silicon compound microporous particles, for example, comprise pulverized gel-like silica compounds. Furthermore, other forms of low-refractive-index layers having at least a porous layer and / or an air layer include, for example, porous layers formed from fibrous materials such as nanofibers, where the fibrous materials are intertwined to form voids and thus form a layer. The method for manufacturing such porous layers is not particularly limited, for example, the same applies to porous layers of porous bodies where the microporous particles are chemically bonded together. In addition, other forms include porous layers using hollow nanoparticles, nanoclay, hollow nanospheres, and magnesium fluoride. Porous layers can be formed from a single constituent material or from multiple constituent materials. Porous layers can be composed of a single form or contain multiple forms described above.

[0059] In this embodiment, the porous structure of the porous body can be, for example, a bubble-like structure formed by continuous pore structures. A bubble-like structure, for example in the aforementioned organosilicon porous body, refers to a state where the pore structures are three-dimensionally connected, or a state where the internal voids of the pore structure are continuous. By giving the porous body a bubble-like structure, the porosity can be increased. However, when using individual bubble particles (particles each having their own pore structure) such as hollow silica, a bubble-like structure cannot be formed. On the other hand, when using, for example, silica gel particles (a pulverized gel-like silicon compound forming a sol), since these particles have a three-dimensional dendritic structure, these dendritic particles will settle and deposit in the coating film (a coating film containing a sol of pulverized gel-like silicon compounds), thereby easily forming a bubble-like structure. A low-refractive-index layer is more preferably an integral structure with a bubble-like structure comprising a variety of fine pore distributions. An integral structure refers to a hierarchical structure, which includes, for example, a structure containing nanoscale micropores and a bubble-like structure formed by the aggregation of such nanoscale micropores. In the case of forming a monolithic structure, for example, fine pores can be used to impart membrane strength, and large interconnected pores can be used to impart high porosity, thereby achieving a balance between membrane strength and high porosity. Such a monolithic structure is preferably formed by controlling the pore distribution of the generated void structure within the gel (gel-like silicon compound) in the pre-powdering stage. Alternatively, for example, a monolithic structure can be formed by controlling the particle size distribution of the pulverized silicon particles to a desired size during the pulverization of the gel-like silicon compound.

[0060] The low-refractive-index layer, for example as described above, contains fragments of a gel-like compound, and these fragments are chemically bonded together. The form of the chemical bonding (chemical bonds) between the fragments in the low-refractive-index layer is not particularly limited, and examples include cross-linking bonds, covalent bonds, and hydrogen bonds.

[0061] There are no particular restrictions on the gel morphology of gel-like compounds. "Gel" generally refers to a solidified state in which the solute, due to interactions, loses its independent mobility and aggregates. Gel-like compounds can be, for example, wet gels or dry gels. It should be noted that, generally speaking, a wet gel refers to a gel containing a dispersion medium in which the solute adopts a uniform structure, while a dry gel refers to a gel in which the solvent has been removed and the solute adopts a porous, mesh-like structure.

[0062] Examples of gel-like compounds include gels formed by gelling monomeric compounds. Specifically, examples of gel-like silicon compounds include gels formed by the bonding of monomeric silicon compounds; as specific examples, gels in which the monomeric silicon compounds form covalent bonds, hydrogen bonds, or intermolecular forces. Examples of covalent bonds include, for instance, bonds based on dehydration condensation.

[0063] The volume average particle size of the pulverized material in the low refractive index layer is, for example, 0.10 μm or more, preferably 0.20 μm or more, and more preferably 0.40 μm or more. On the other hand, the volume average particle size is, for example, 2.00 μm or less, preferably 1.50 μm or less, and more preferably 1.00 μm or less. The range of the volume average particle size is, for example, 0.10 μm to 2.00 μm, preferably 0.20 μm to 1.50 μm, and more preferably 0.40 μm to 1.00 μm. The particle size distribution can be measured by particle size distribution evaluation devices such as dynamic light scattering and laser diffraction, and electron microscopes such as scanning electron microscope (SEM) and transmission electron microscope (TEM). It should be noted that the volume average particle size is an indicator of the deviation of the particle size of the pulverized material.

[0064] There are no particular limitations on the types of gel-like compounds. Examples of gel-like compounds include gel-like silicon compounds. The following explanation uses gel-like silicon compounds as an example, but it is not limited to this.

[0065] The aforementioned crosslinking bonds are, for example, siloxane bonds. Examples of siloxane bonds include, for instance, T2, T3, and T4 bonds, as shown below. When siloxane bonds are present in the void layer (low refractive index layer), any one type of bond, any two types, or all three types can be present. A higher ratio of T2 and T3 in the siloxane bonds results in greater flexibility and the expected properties of the gel. Conversely, a higher ratio of T4 makes it easier to exhibit film strength. Therefore, it is preferable to vary the ratio of T2, T3, and T4 according to the purpose, application, and desired properties.

[0066] [Chemical Formula 1]

[0067]

[0068] Furthermore, in the low-refractive-index layer (void layer), for example, the silicon atoms contained therein preferably form siloxane bonds. As a specific example, the proportion of unbonded silicon atoms (i.e., residual silanols) among all the silicon atoms contained in the void layer is, for example, less than 50%, preferably less than 30%, and more preferably less than 15%.

[0069] When the gel-like compound is a gel-like silicon compound, there are no particular limitations on the monomeric silicon compound. Examples of monomeric silicon compounds include compounds represented by the following formula (1). When the gel-like silicon compound is a gelled product of monomeric silicon compounds forming hydrogen bonds or intermolecular forces, as described above, the monomers of formula (1) may form hydrogen bonds, for example, through their respective hydroxyl groups.

[0070] [Chemical Formula 2]

[0071]

[0072] In equation (1), X is, for example, 2, 3, or 4, preferably 3 or 4. R 1 For example, it can be a straight-chain or branched alkyl group. R 1 The number of carbon atoms is, for example, 1 to 6, preferably 1 to 4, and more preferably 1 to 2. Examples of straight-chain alkyl groups include methyl, ethyl, propyl, butyl, pentyl, and hexyl, while examples of branched alkyl groups include isopropyl and isobutyl.

[0073] As a specific example of a silicon compound represented by formula (1), one can cite, for example, a compound represented by the following formula (1') where X is 3. In the following formula (1'), R 1 The same applies as in equation (1), for example, to methyl. In R 1 When X is methyl, the silicon compound is trihydroxymethylsilane. When X is 3, the silicon compound is, for example, a trifunctional silane having 3 functional groups.

[0074] [Chemical Formula 3]

[0075]

[0076] As another specific example of a silicon compound represented by formula (1), a compound in which X is 4 can be cited. In this case, the silicon compound is, for example, a tetrafunctional silane having four functional groups.

[0077] The monomeric silicon compound can also be, for example, a hydrolysate of a silicon compound precursor. As a silicon compound precursor, any of those that can be hydrolyzed to generate a silicon compound is acceptable; as a specific example, compounds represented by the following formula (2) can be listed.

[0078] [Chemical Formula 4]

[0079]

[0080] In equation (2) above, X is, for example, 2, 3 or 4.

[0081] R 1 and R 2 Each is independently a straight-chain or branched alkyl group.

[0082] R 1 and R 2 They can be the same or different.

[0083] When X is 2, R 1 They can be the same or different.

[0084] R 2 They can be the same or different.

[0085] X and R 1 For example, X and R in equation (1) 1 Same. R 2 For example, R in equation (1) can be used. 1 Examples.

[0086] Specific examples of silicon compound precursors represented by formula (2) include, for example, the compounds shown in formula (2') below where X is 3. In formula (2') below, R 1 and R 2 The situation is the same as in equation (2). In R... 1 and R 2 In the case of methyl, the silicon compound precursor is trimethoxy(methyl)silane (hereinafter also referred to as "MTMS").

[0087] [Chemical Formula 5]

[0088]

[0089] For example, considering excellent low refractive index properties, the monomeric silicon compound is preferably a trifunctional silane. Furthermore, considering excellent strength (e.g., scratch resistance), the monomeric silicon compound is preferably a tetrafunctional silane. Only one type of monomeric silicon compound may be used, or two or more may be used in combination. For example, the monomeric silicon compound may contain only a trifunctional silane, only a tetrafunctional silane, or both trifunctional and tetrafunctional silanes, or further may contain other silicon compounds. When using two or more silicon compounds as the monomeric silicon compound, their ratio is not particularly limited and can be appropriately set.

[0090] The following is an example of a method for forming such a low-refractive-index layer.

[0091] Typically, the method includes: a precursor forming step of forming a void structure on a resin film as a precursor of a low refractive index layer (void layer); and a crosslinking reaction step of initiating a crosslinking reaction within the precursor after the precursor forming step. The method further includes: a containing liquid preparation 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 step of drying the containing liquid, wherein in the precursor forming step, the microporous particles in the dried body are chemically bonded to each other to form the precursor. The containing liquid is not particularly limited, and may be, for example, a suspension containing microporous particles. It should be noted that the following description mainly pertains to the case where the microporous particles are pulverized gel-like compounds and the void layer contains pulverized gel-like compounds (preferably an organosilicon porous body). It should be noted that the low refractive index layer can also be formed similarly when the microporous particles are not pulverized gel-like compounds.

[0092] Using the method described above, a low-refractive-index layer (porosity layer) with, for example, a very low refractive index can be formed. The reasons for this can be inferred, for example, as follows. However, this inference does not limit the method for forming the low-refractive-index layer.

[0093] The aforementioned pulverized material is formed by pulverizing a gel-like silicon compound. Therefore, the three-dimensional structure of the gel-like silicon compound before pulverization is dispersed within a three-dimensional basic structure. Furthermore, in the above method, by coating the pulverized gel-like silicon compound onto a resin film, a precursor for a porous structure based on the three-dimensional basic structure can be formed. That is, according to the above method, a new porous structure (three-dimensional basic structure) based on the pulverized material, different from the three-dimensional structure of the gel-like silicon compound, can be formed. Therefore, in the final porous layer, for example, a low refractive index that functions to the same extent as an air layer can be achieved. Moreover, in the above method, chemical bonds are formed between the pulverized materials, thus immobilizing the three-dimensional basic structure. Therefore, although the final porous layer is a porous structure, it can maintain sufficient strength and flexibility.

[0094] Furthermore, in the above-described method, the precursor formation step and the crosslinking reaction step can be performed as separate steps. Moreover, it is preferable to perform the crosslinking reaction step in multiple steps. By performing the crosslinking reaction step in multiple steps, for example, compared to performing it in a single step, the strength of the precursor can be further improved, thereby obtaining a low-refractive-index layer that balances high porosity and strength. The mechanism is not yet clear, but it can be speculated, for example, as follows: That is, as described above, when the film strength is increased simultaneously with the formation of the porous layer using a catalyst, there is a problem that although the film strength is increased, the porosity decreases due to the catalytic reaction. This can be attributed, for example, to the fact that, by using a catalyst to induce a crosslinking reaction between microporous particles, the number of crosslinks (chemical bonds) between the microporous particles increases, thereby strengthening the bonds, but the entire porous layer condenses, resulting in a decrease in porosity. In contrast, it can be argued that by performing the precursor formation process and the crosslinking reaction process as separate processes, and by carrying out the crosslinking reaction process in multiple steps, the number of crosslinks (chemical bonds) can be increased (e.g., with almost no overall coagulation) without causing, for example, any change in the overall morphology of the precursor. However, these are only examples of inferred mechanisms and do not limit the methods for forming low-refractive-index layers.

[0095] In the precursor formation process, for example, particles of a certain shape are stacked to form a precursor with a porous layer. At this point in time, the strength of the precursor is very weak. Then, for example, through a photo- or thermally active catalytic reaction, a product capable of chemically bonding the microporous particles to each other is produced (e.g., a strong base catalyst generated by a photo-alkali-producing agent, etc.) (the first stage of the crosslinking reaction process). It can be considered that, in order to carry out the reaction more efficiently and in a shorter time, further heating and aging (the second stage of the crosslinking reaction process) will further enable the chemical bonding (crosslinking reaction) of the microporous particles to proceed, thereby increasing the strength. It can be considered that, for example, the microporous particles are microporous particles of silicon compounds (e.g., pulverized gel-like silica compounds), and in the presence of residual silanol groups (Si-OH groups) in the precursor, the residual silanol groups will form chemical bonds to each other through the crosslinking reaction. However, this description is only an example and does not limit the method of forming the low refractive index layer.

[0096] The above method includes a liquid-containing step of preparing a liquid containing microporous particles. In the case where the microporous particles are a pulverized gel-like compound, the pulverized material is obtained, for example, by pulverizing the gel-like compound. By pulverizing the gel-like compound, as described above, the three-dimensional structure of the gel-like compound is disrupted and dispersed in a three-dimensional basic structure. An example of the preparation of the pulverized material is described below.

[0097] Gel formation of monomeric compounds can be achieved, for example, by forming hydrogen bonds or intermolecular forces between the monomeric compounds. Examples of monomeric compounds include silicon compounds represented by formula (1) above. Since silicon compounds of formula (1) have hydroxyl groups, the monomers of formula (1) can form hydrogen bonds or intermolecular forces with each other via, for example, their respective hydroxyl groups.

[0098] Alternatively, the silicon compound can be a hydrolysate of the silicon compound precursor mentioned above, for example, it can be generated by hydrolyzing the silicon compound precursor represented by formula (2) above.

[0099] There are no particular limitations on the method of hydrolysis of the monomeric compound precursor; for example, it can be carried out through a chemical reaction in the presence of a catalyst. Examples of catalysts include acids such as oxalic acid and acetic acid. The hydrolysis reaction can be carried out as follows: for example, an aqueous solution of oxalic acid is slowly added dropwise to a mixture (e.g., a suspension) of a silicon compound and dimethyl sulfoxide at room temperature, and after mixing, the mixture is stirred for approximately 30 minutes. When hydrolyzing the silicon compound precursor, for example, by completely hydrolyzing the alkoxy groups of the silicon compound precursor, subsequent gelation / curing / heating / immobilization after void structure formation can be carried out more efficiently.

[0100] The gelation of monomeric compounds can be carried out, for example, by a dehydration condensation reaction between monomers. The dehydration condensation reaction is preferably carried out in the presence of a catalyst, such as acid catalysts like hydrochloric acid, oxalic acid, and sulfuric acid, or base catalysts like ammonia, potassium hydroxide, sodium hydroxide, and ammonium hydroxide. A base catalyst is preferred as the dehydration condensation catalyst. There is no particular limitation on the amount of catalyst added relative to the monomeric compound in the dehydration condensation reaction. For example, relative to 1 mole of the monomeric compound, 0.1 to 10 moles of catalyst are preferably added, more preferably 0.05 to 7 moles, and even more preferably 0.1 to 5 moles.

[0101] The gelation of the monomer compound is preferably carried out in a solvent. There are no particular limitations on the ratio of the monomer compound to the solvent. Examples of solvents include: dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc), dimethylformamide (DMF), γ-butyrolactone (GBL), acetonitrile (MeCN), ethylene glycol ethyl ether (EGEE), etc. Solvents can be used alone or in combination of two or more. Hereinafter, the solvent used in gelation will also be referred to as "gelation solvent".

[0102] There are no particular limitations on the gelation conditions. For solvents containing monomeric compounds, the treatment temperature is, for example, 20°C to 30°C, preferably 22°C to 28°C, more preferably 24°C to 26°C. The treatment time is, for example, 1 minute to 60 minutes, preferably 5 minutes to 40 minutes, more preferably 10 minutes to 30 minutes. In the case of a dehydration condensation reaction, the treatment conditions are not particularly limited, and the above examples can be used. By performing gelation, for example, siloxane bonds can be grown to form primary silica particles, and by further reaction, the primary particles can be linked together in a beaded manner to generate a three-dimensional gel structure.

[0103] Preferably, the gel-like compound obtained by gelation is subjected to a aging treatment after the gelation reaction. This aging treatment allows, for example, the primary particles of the gel with a three-dimensional structure obtained by gelation to further grow, increasing the particle size. Consequently, the contact state at the necks of the particles changes from point contact to surface contact (increasing the contact area). For the gel after aging treatment, for example, the strength of the gel itself increases, resulting in improved strength of the pulverized three-dimensional basic structure. Therefore, for example, in the drying process after coating the pulverized material, the shrinkage of the pore size of the void structure formed by the accumulation of the three-dimensional basic structure due to solvent evaporation during the drying process can be suppressed.

[0104] The curing process can be performed, for example, by incubating the gel-like compound at a given temperature for a given time. The curing temperature is, for example, 30°C or higher, preferably 35°C or higher, more preferably 40°C or higher. On the other hand, the curing temperature is, for example, 80°C or lower, preferably 75°C or lower, more preferably 70°C or lower. The range of the curing temperature is, for example, 30°C to 80°C, preferably 35°C to 75°C, more preferably 40°C to 70°C. The curing time is, for example, 5 hours or higher, preferably 10 hours or higher, more preferably 15 hours or higher. On the other hand, the curing time is, for example, 50 hours or lower, preferably 40 hours or lower, more preferably 30 hours or lower. The range of the curing time is, for example, 5 hours to 50 hours, preferably 10 hours to 40 hours, more preferably 15 hours to 30 hours. It should be noted that the curing conditions can be optimized, for example, to increase the size of the primary silica particles and the contact area of ​​the neck. Furthermore, the boiling point of the solvent used is preferably considered. For example, if the curing temperature is too high, the solvent will evaporate excessively, which may lead to adverse conditions such as closure of the pores in the three-dimensional porous structure due to the concentration of the coating solution (gel). On the other hand, if the curing temperature is too low, not only will the effects of curing not be fully obtained, but it will also lead to an increase in the temperature deviation over time in the mass production process, which may result in a low refractive index layer with poor properties.

[0105] The aging treatment can use the same solvent as, for example, the gelation treatment. Specifically, it is preferable to directly perform the aging treatment on the reactants after gelation (i.e., the solvent containing the gel-like compound). The molar number of residual silanol groups contained in the gel (gel-like compound, such as a gel-like silicon compound) after the aging treatment following gelation is, for example, 50% or less, preferably 40% or less, more preferably 30% or less. On the other hand, the molar number of residual silanol groups is, for example, 1% or more, preferably 3% or more, more preferably 5% or more. The range of the molar number of residual silanol groups is, for example, 1% to 50%, preferably 3% to 40%, more preferably 5% to 30%. For the purpose of improving the hardness of the gel, for example, a lower molar number of residual silanol groups is preferred. If the molar number of silanol groups is too high, the porous structure may not be maintained until, for example, the precursor of the organosilicon porous body crosslinks. On the other hand, if the molar number of silanol groups is too low, for example, in the process of preparing microporous particles containing liquid (e.g., suspension) and / or subsequent processes, it may be impossible to crosslink the pulverized gel-like compound, thus failing to impart sufficient film strength. It should be noted that the molar number of residual silanol groups refers to, for example, the proportion of residual silanol groups when the molar number of alkoxy groups in the raw material (e.g., monomeric compound precursor) is set to 100. It should also be noted that the above are examples of silanol groups; for example, when the silicon compound of the monomer is modified with various reactive functional groups, the same considerations and conditions can be applied to each functional group.

[0106] After gelling the monomer compound in a gelling solvent, the resulting gel-like compound is pulverized. Pulverization can be performed directly on the gel-like compound in the gelling solvent, or the gelling solvent can be replaced with another solvent, and the gel-like compound in that other solvent can be pulverized. Furthermore, if, for example, the catalyst and solvent used in the gelling reaction remain after the aging process, causing a decrease in the liquid's gelation time (potential life) and drying efficiency during the drying process, it is preferable to replace it with another solvent. Hereinafter, the aforementioned other solvent will also be referred to as the "pulverizing solvent."

[0107] There are no particular limitations on the solvent used for pulverization; for example, organic solvents can be used. Examples of organic solvents include those with a boiling point of 130°C or lower, preferably 100°C or lower, and more preferably 85°C or lower. Specific examples include isopropanol (IPA), ethanol, methanol, butanol, propylene glycol monomethyl ether (PGME), methyl cellosolve, acetone, dimethylformamide (DMF), and isobutanol. The pulverization solvent can be used alone or in combination of two or more.

[0108] There are no particular limitations on the combination of the gelling solvent and the pulverizing solvent; examples include combinations of DMSO and IPA, DMSO and ethanol, DMSO and methanol, DMSO and butanol, and DMSO and isobutanol. By replacing the gelling solvent with the pulverizing solvent in this way, for example in the coating film formation described later, a more uniform coating film can be formed.

[0109] There are no particular limitations on the method for pulverizing gel-like compounds. Pulverization can be performed using, for example, ultrasonic homogenizers, high-speed rotary homogenizers, or other pulverizing devices that utilize cavitation phenomena. While media-based pulverizing devices such as ball mills physically destroy the porous structure of the gel during pulverization, cavitation-based pulverizing devices such as homogenizers, being media-free, utilize high-speed shearing forces to peel away the relatively weakly bonded silica particle interfaces already encapsulated within the three-dimensional structure of the gel. As a result, the resulting three-dimensional gel structure can maintain, for example, a porous structure with a certain range of particle size distribution, thereby enabling the recombination of porous structures resulting from deposition during coating / drying. There are no particular limitations on the pulverization conditions; for example, conditions that allow for pulverization by instantaneously imparting high-speed flow without causing solvent evaporation are preferred. For example, pulverization is preferably performed in a manner that produces pulverized material with the particle size deviations (e.g., volume average particle size or particle size distribution) as described above. If the amount of work done, such as grinding time / intensity, is insufficient, coarse particles may remain, which not only prevents the formation of dense pores but also increases appearance defects, making it impossible to obtain high quality. On the other hand, if the amount of work done is excessive, for example, the particles may become finer than the desired particle size distribution, and the void size formed after coating / drying becomes fine, making it impossible to obtain the desired porosity.

[0110] As described above, a liquid (e.g., a suspension) containing microporous particles (a pulverized gel-like compound) can be manufactured. Furthermore, by adding a catalyst that chemically bonds the microporous particles together after the liquid containing the microporous particles is produced, or during the manufacturing process, a liquid containing both microporous particles and a catalyst can be produced. The catalyst can be, for example, a catalyst that promotes cross-linking between the microporous particles. As a chemical reaction that chemically bonds the microporous particles together, the dehydration condensation reaction of residual silanol groups contained in the silica gel molecules is preferably utilized. By utilizing a catalyst to promote the reaction of the hydroxyl groups of the silanol groups, continuous film formation that solidifies the porous structure can be carried out in a short time. Examples of catalysts include, for example, photoactivated catalysts and thermally activated catalysts. According to a photoactivated catalyst, for example, in the precursor formation process, the microporous particles can be chemically bonded together (e.g., forming cross-linking bonds) without heating. Therefore, for example, shrinkage of the precursor as a whole is less likely to occur in the precursor formation process, thus maintaining a higher porosity. Additionally, a substance that generates a catalyst (catalyst generator) can be used in addition to or in place of a catalyst. For example, a substance that generates a catalyst by light (photocatalyst generator) can be used in addition to or in place of a photoactivated catalyst, or a substance that generates a catalyst by heat (thermal catalyst generator) can be used in addition to or in place of a thermally activated catalyst. Examples of photocatalyst generators include: photoalkali-generating agents (substances that generate alkaline catalysts by light irradiation), photoacid-generating agents (substances that generate acid catalysts by light irradiation), etc., with photoalkali-generating agents being preferred.Examples of photoalkali-producing agents include: 9-anthrylmethyl N,N-diethylcarbamate (trade name WPBG-018), (E)-1-[3-(2-hydroxyphenyl)-2-propenoyl]piperidine (trade name WPBG-027), 1-(anthraquinone-2-yl)ethylimidazolecarboxylate (trade name WPBG-140), and 2-nitrophenylmethyl-4-methylpropene. Acyloxypiperidine-1-carboxylic acid ester (trade name WPBG-165), 1,2-diisopropyl-3-[bis(dimethylamino)methylene]guanidine salt of 2-(3-benzoylphenyl)propionic acid (trade name WPBG-266), 1,2-dicyclohexyl-4,4,5,5-tetramethyl diguanidine salt of n-butyltriphenylboronic acid (trade name WPBG-300), and 1,5,7-triazabicyclo[4.4.0]dec-5-ene of 2-(9-oxoxazan-2-yl)propionic acid (Tokyo Chemical Industry Co., Ltd.), and compounds containing 4-piperidinemethanol (trade name HDPD-PB100: manufactured by Heraeus Co., Ltd.), etc. It should be noted that the above-mentioned trade names containing "WPBG" are all trade names of Wako Pure Chemical Industries Co., Ltd. Examples of photoacid-generating agents include: aromatic sulfonium salts (trade name SP-170: ADEKA Co., Ltd.), triaryl sulfonium salts (trade name CPI101A: San-Apro Co., Ltd.), and aromatic iodine. Salt (trade name Irgacure 250: Ciba Japan Co., Ltd.), etc. Furthermore, the catalyst that chemically bonds the microporous particles together is not limited to photoactivated catalysts and photocatalyst generators; it can also be, for example, a thermally activated catalyst or a thermal catalyst generator such as urea. Examples of catalysts that chemically bond the microporous particles together include: alkaline catalysts such as potassium hydroxide, sodium hydroxide, and ammonium hydroxide; acid catalysts such as hydrochloric acid, acetic acid, and oxalic acid. Among these, alkaline catalysts are preferred. The catalyst or catalyst generator that chemically bonds the microporous particles together can be added to a sol-particle liquid (e.g., a suspension) containing pulverized material (microporous particles) just before coating, or it can be used in the form of a mixture of the catalyst or catalyst generator in a solvent. The mixture can be, for example, a coating solution obtained by directly adding and dissolving the sol-particle liquid, a solution obtained by dissolving the catalyst or catalyst generator in a solvent, or a dispersion obtained by dispersing the catalyst or catalyst generator in a solvent. There are no particular limitations on the solvent; examples include, for instance, water and buffer solutions.

[0111] Additionally, for example, a crosslinking aid can be further added to the gel-containing liquid to indirectly bind the pulverized gel particles together. This crosslinking aid enters between the particles (the pulverized particles), and by causing the particles to interact or bind with the crosslinking aid, even particles that are slightly separated in distance can bind together, thereby efficiently increasing strength. As the crosslinking aid, a multi-crosslinked silane monomer is preferred. Specifically, the multi-crosslinked silane monomer may, for example, have two or more but three or fewer alkoxysilyl groups, the chain length between the alkoxysilyl groups may be one or more but less than 10 carbon atoms, and may also contain elements other than carbon. Examples of crosslinking aids include: bis(trimethoxysilyl)ethane, bis(triethoxysilyl)ethane, bis(trimethoxysilyl)methane, bis(triethoxysilyl)methane, bis(triethoxysilyl)propane, bis(trimethoxysilyl)propane, bis(triethoxysilyl)butane, bis(trimethoxysilyl)butane, bis(triethoxysilyl)pentane, bis(trimethoxysilyl)pentane, bis(triethoxysilyl)hexane, bis(trimethoxysilyl)hexane, bis(trimethoxysilyl)-N-n-butyl-N-propyl-1,2-ethylenediamine, tris(3-trimethoxysilylpropyl)isocyanurate, tris(3-triethoxysilylpropyl)isocyanurate, etc. There is no particular limitation on the amount of the crosslinking aid added, for example, it is 0.01 to 20% by weight, 0.05 to 15% by weight, or 0.1 to 10% by weight relative to the weight of the pulverized silicon compound.

[0112] Next, a liquid containing microporous particles (e.g., a suspension) is coated onto the substrate (coating process). Coating can be performed using various methods described later, and is not limited to these. A coating film containing microporous particles and a catalyst can be formed by directly coating the liquid containing microporous particles (e.g., pulverized gel-like silica compounds) onto the substrate. The coating film can also be referred to as a coating layer. By forming the coating film, for example, the pulverized material whose three-dimensional structure has been disrupted settles / deposits, thereby constructing a new three-dimensional structure. It should be noted that, for example, the liquid containing microporous particles may not contain a catalyst that chemically bonds the microporous particles together. For example, as described later, a precursor formation process can be performed after spraying the coating film with a catalyst that chemically bonds the microporous particles together, or while spraying. However, the liquid containing microporous particles may also contain a catalyst that chemically bonds the microporous particles together, and the microporous particles are chemically bonded together by the action of the catalyst contained in the coating film to form a precursor of a porous body.

[0113] The solvents mentioned above (hereinafter also referred to as "coating solvents") are not particularly limited, and organic solvents can be used for example. Examples of organic solvents include those with a boiling point below 150°C. Specific examples include IPA, ethanol, methanol, n-butanol, 2-butanol, isobutanol, pentanol, etc. Additionally, the same solvents used for pulverizing can be used. In cases where the method for forming a low-refractive-index layer includes a step of pulverizing a gel-like compound, the pulverizing solvent containing the pulverized gel-like compound can be used directly in the coating film formation step, for example.

[0114] In the coating process, for example, it is preferable to apply a sol-like pulverized material dispersed in a solvent (hereinafter also referred to as "sol particle liquid") onto a substrate. For the sol particle liquid, by performing the aforementioned chemical crosslinking, for example, after applying it to the substrate and allowing it to dry, a continuous film with a porous layer having a certain level of film strength can be achieved. It should be noted that, in the embodiments of the present invention, "sol" refers to a state in which silica gel particles with a nano-three-dimensional structure retaining a portion of the porous structure are dispersed in a solvent, thus exhibiting fluidity, by pulverizing the three-dimensional structure of the gel.

[0115] There is no particular limitation on the concentration of the pulverized material in the coating solvent, for example, it is 0.3% (v / v) to 50% (v / v), preferably 0.5% (v / v) to 30% (v / v), and more preferably 1.0% (v / v) to 10% (v / v). If the concentration of the pulverized material is too high, for example, the fluidity of the sol-particle liquid will be significantly reduced, which may cause agglomerates / coating streaks during coating. If the concentration of the pulverized material is too low, for example, not only will the drying of the solvent in the sol-particle liquid take a considerable amount of time, but the residual solvent after drying will also increase, which may lead to a decrease in porosity.

[0116] There are no particular limitations on the physical properties of the sol. The shear viscosity of the sol is, for example, 100 cPa·s or less, preferably 10 cPa·s or less, and more preferably 1 cPa·s or less, at a shear rate of 1000 1 / s. If the shear viscosity is too high, adverse effects such as coating streaks or reduced transfer rate of gravure coating may occur. Conversely, if the shear viscosity is too low, it may be impossible to increase the wet coating thickness during application, and the desired thickness may not be obtained after drying.

[0117] There are no particular limitations on the amount of pulverized material applied to the substrate; for example, it can be appropriately set according to the desired thickness of the porous silicone body (ultimately a low-refractive-index layer). As a specific example, when forming a porous silicone body with a thickness of 0.1 μm to 1000 μm, the average amount of pulverized material applied to the substrate is approximately [amount missing] per m [unit missing]. 2The substrate area is, for example, 0.01 μg to 60,000 μg, preferably 0.1 μg to 5,000 μg, and more preferably 1 μg to 50 μg. The preferred coating amount of the sol-particle liquid is related to factors such as the concentration of the liquid and the coating method, and therefore cannot be uniquely defined. However, considering productivity, it is preferable to apply a thin layer whenever possible. If the coating amount is too high, the possibility of the solvent being dried in a drying oven before evaporation increases. As a result, the nano-sized sol-particles may settle / deposit in the solvent, and the solvent may dry before the formation of a porous structure, which may hinder the formation of pores and lead to a significant reduction in porosity. On the other hand, if the coating amount is too thin, the risk of coating pinholes may increase due to variations in the unevenness / hydrophobicity of the substrate.

[0118] Furthermore, the method for forming a low-refractive-index layer includes, for example, a precursor forming step of forming a void structure on a substrate as a precursor to a void layer (low-refractive-index layer), as described above. The precursor forming step is not particularly limited; for example, the precursor (void structure) can be formed by a drying step of drying a coating film made by drying a liquid containing microporous particles. Through the drying process in the drying step, not only the solvent in the coating film (the solvent contained in the sol-particle liquid) can be removed, but also the sol particles can be precipitated / deposited to form a void structure. The drying temperature is, for example, 50°C to 250°C, preferably 60°C to 150°C, more preferably 70°C to 130°C. The drying time is, for example, 0.1 minutes to 30 minutes, preferably 0.2 minutes to 10 minutes, more preferably 0.3 minutes to 3 minutes. Regarding the drying temperature and time, for example, a lower temperature and shorter time are preferred in terms of exhibiting continuous productivity and high porosity. When conditions are too stringent, such as when coating a resin film, the resin film may stretch in the drying oven due to proximity to its glass transition temperature, or cracks may form in the resulting void structure immediately after coating. On the other hand, when conditions are too lenient, for example, residual solvent may remain at the time of removal from the drying oven, potentially causing scratches or other cosmetic defects when rubbed against rollers in subsequent processes.

[0119] Drying can be achieved through natural drying, heated drying, or reduced pressure drying. Heated drying is preferred for continuous industrial production. There are no particular limitations on the heating method; conventional heating mechanisms can be used. Examples of heating mechanisms include hot air blowers, heated rollers, and far-infrared heaters. Regarding the solvent used, solvents with low surface tension are preferred to suppress the shrinkage stress caused by solvent evaporation during drying and the resulting cracking of the porous layer (organosilicon porous body). Examples of solvents include lower alcohols such as isopropanol (IPA), hexane, and perfluorohexane. Furthermore, small amounts of perfluorinated or organosilicon surfactants can be added to the aforementioned IPA to reduce surface tension.

[0120] Furthermore, the method for forming the low refractive index layer, as described above, includes a crosslinking reaction step that occurs within the precursor after the precursor formation step. In this crosslinking reaction step, an alkaline substance is generated by light or heating, and the crosslinking reaction step consists of multiple stages. In the first stage of the crosslinking reaction step, microporous particles form chemical bonds with each other, for example, through the action of a catalyst (alkaline substance). Thus, for example, the three-dimensional structure of the fragments in the coating film (precursor) is immobilized. When immobilization is performed using conventional sintering, for example, by performing high-temperature treatment above 200°C, dehydration condensation of silanol groups and formation of siloxane bonds are induced. In this formation method, by reacting various additives that catalyze the aforementioned dehydration condensation reaction, for example, a porous structure can be continuously formed and immobilized at a relatively low drying temperature of around 100°C and a short processing time of less than a few minutes without causing damage to the substrate (resin film).

[0121] There are no particular limitations on the methods of chemical bonding; for example, they can be appropriately determined based on the type of gel-like silicon compound. Specifically, chemical bonding can occur through, for example, cross-linking between pulverized materials. Alternatively, when inorganic particles such as titanium dioxide are added to the pulverized materials, it is also possible to chemically cross-link the inorganic particles with the pulverized materials. Furthermore, this includes cases where biocatalysts such as enzymes are loaded, or cases where sites different from the catalyst's active sites are chemically cross-linked with the pulverized materials. Therefore, for methods of forming low-refractive-index layers, it is possible to consider not only applications such as porous layers formed by sol particles (organosilicon porous bodies), but also applications such as organic-inorganic hybrid porous layers and host-guest porous layers.

[0122] There is no particular limitation on at which stage of the method for forming the low-refractive-index layer the chemical reaction in the presence of the aforementioned catalyst takes place. For example, it may take place in at least one stage of the aforementioned multi-stage crosslinking reaction process. For example, in the method for forming the low-refractive-index layer, the drying process may also be combined with the precursor formation process as described above. Alternatively, for example, a multi-stage crosslinking reaction process may be carried out after the drying process, and in at least one stage, the microporous particles may form chemical bonds with each other through the action of a catalyst. For example, if the catalyst is a photoactivated catalyst as described above, the microporous particles may be chemically bonded together to form a porous precursor by light irradiation during the crosslinking reaction process. Alternatively, if the catalyst is a thermally activated catalyst, the microporous particles may be chemically bonded together to form a porous precursor by heating during the crosslinking reaction process.

[0123] The aforementioned chemical reaction can be carried out, for example, by irradiating or heating a coating film containing a catalyst pre-added to a sol-particle liquid (e.g., a suspension), or by irradiating or heating the coating film after spraying the catalyst, or by simultaneously spraying the catalyst and irradiating or heating it. The cumulative light intensity during irradiation is not particularly limited, but is, for example, 200 mJ / cm² converted to a wavelength of 360 nm. 2 ~800mJ / cm 2 The preferred value is 250 mJ / cm. 2 ~600mJ / cm 2 More preferably 300 mJ / cm 2 ~400mJ / cm 2 From the viewpoint of preventing insufficient irradiation, the inability of catalyst-based light absorption decomposition, and thus insufficient effectiveness, 200 mJ / cm² is preferred. 2 The above is the cumulative light intensity. Furthermore, from the viewpoint of preventing thermal wrinkling caused by damage to the substrate beneath the void layer, 800 mJ / cm is preferred. 2The following cumulative light intensity. There are no particular limitations on the heat treatment conditions. The heating temperature is, for example, 50°C to 250°C, preferably 60°C to 150°C, more preferably 70°C to 130°C. The heating time is, for example, 0.1 minutes to 30 minutes, preferably 0.2 minutes to 10 minutes, more preferably 0.3 minutes to 3 minutes. Alternatively, the process of drying the coated sol-particle liquid (e.g., suspension) as described above can also be a process of carrying out a chemical reaction in the presence of a catalyst. That is, in the process of drying the coated sol-particle liquid (e.g., suspension), the pulverized material (microporous particles) can be chemically bonded together through a chemical reaction in the presence of a catalyst. In this case, the pulverized material (microporous particles) can be further bonded together more firmly by further heating the coating film after the drying process. Furthermore, it is conceivable that the chemical reaction in the presence of a catalyst may sometimes occur in the process of preparing the microporous particle containing liquid (e.g., suspension) and the process of coating the microporous particle containing liquid. However, this conjecture does not limit the method of forming the low refractive index layer. Furthermore, regarding the solvent used, for example, to suppress the generation of shrinkage stress accompanying solvent evaporation during drying and the resulting cracking of the void layer, a solvent with low surface tension is preferred. Examples include lower alcohols such as isopropanol (IPA), hexane, and perfluorohexane.

[0124] In methods for forming low-refractive-index layers, by dividing the crosslinking reaction process into multiple stages, for example, compared to a single-stage crosslinking reaction process, the strength of the void layer (low-refractive-index layer) can be further improved. Hereinafter, the processes following the second stage of the crosslinking reaction process are sometimes referred to as "aging processes." In the aging process, for example, by heating the precursor, the crosslinking reaction can be further promoted within the precursor. The phenomena and mechanisms occurring in the crosslinking reaction process are not yet fully understood, but are, for example, as described above. For example, in the aging process, by setting the heating temperature to a low level, the crosslinking reaction can occur while suppressing precursor shrinkage, thereby increasing strength and achieving a balance between high porosity and strength. The temperature in the aging process is, for example, 40°C to 70°C, preferably 45°C to 65°C, more preferably 50°C to 60°C. The duration of the aging process is, for example, 10 hours to 30 hours, preferably 13 hours to 25 hours, more preferably 15 hours to 20 hours.

[0125] The low-refractive-index layer formed as described above has excellent strength, and therefore can be made into a rolled porous body, which has advantages such as good manufacturing efficiency and ease of handling.

[0126] The low-refractive-index layer (porosity layer) thus formed can be further laminated with other films (layers) to create a laminated structure containing a porous structure. In this case, the constituent elements of the laminated structure can be laminated, for example, via adhesives or bonding agents. For example, from an efficiency perspective, the lamination of the constituent elements can be carried out using continuous processing of long strip films (so-called roll-to-roll, etc.), and when the substrate is a molded object / component, it can also be laminated on a batch-processed substrate.

[0127] The specific composition and formation method of the low-refractive-index layer are described in detail in, for example, International Publication No. 2019 / 151073. The contents of that publication are incorporated herein by reference.

[0128] B-4. First Adhesive Layer

[0129] The first adhesive layer has a hardness such that the adhesive constituting the first adhesive layer will not penetrate into the voids of the low refractive index layer under normal conditions. As described above, the storage modulus of the first adhesive layer at 23°C is 1.0 × 10⁻⁶. 5 (Pa)~1.0×10 7 (Pa), for example, 1.1 × 10 5 (Pa) or above, 1.2×10 5 (Pa) or above, 1.3×10 5 (Pa) or above, 1.4×10 5 (Pa) or above, 1.5×10 5 (Pa) or above, 1.6×10 5 (Pa) or above, 1.7×10 5 (Pa) or above, 1.8×10 5 (Pa) or above, 1.9×10 5 (Pa) or above or 2.0×10 5 (Pa) or higher, and 1.0 × 10 7 (Pa) below, 5.0×10 6 (Pa) or less, 1.0×10 6 (Pa) or below or 5.0×10 5 (Pa) or less, preferably 1.3 × 10 5 (Pa)~1.0×10 6 (Pa), more preferably 1.5 × 10 5 (Pa)~5.0×10 5(Pa). The storage modulus is determined as follows: based on the method described in JIS K7244-1 "Plastics - Test method for dynamic mechanical properties", the measurement is performed at a frequency of 1 Hz in the range of -50℃ to 150℃ at a heating rate of 5℃ / min, and the value at 23℃ is read.

[0130] As the adhesive constituting the first adhesive layer, any suitable adhesive can be used as long as it has the properties described above. Acrylic adhesives (acrylic adhesive compositions) are representative examples of adhesives. Acrylic adhesive compositions typically contain a (meth)acrylate polymer as the main component (base polymer). In the solid component of the adhesive composition, the (meth)acrylate polymer may, for example, be contained in the adhesive composition at a proportion of 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more. The (meth)acrylate polymer contains an alkyl (meth)acrylate as a monomer unit as the main component. It should be noted that (meth)acrylate refers to acrylates and / or methacrylates. As the alkyl group of the (meth)acrylate, examples 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. As monomers constituting the (meth)acrylate polymer, in addition to alkyl (meth)acrylate, examples include carboxyl-containing monomers, hydroxyl-containing monomers, amide-containing monomers, aromatic ring (meth)acrylates, heterocyclic (meth)acrylates, and other comonomers. The comonomer is preferably a hydroxyl-containing monomer and / or a heterocyclic (meth)acrylate, more preferably N-acryloylmorpholine. The acrylic adhesive composition may preferably contain a silane coupling agent and / or a crosslinking agent. Examples of silane coupling agents include, for example, epoxy-containing silane coupling agents. Examples of crosslinking agents include, for example, isocyanate crosslinking agents and peroxide crosslinking agents. Details of such adhesive layers or acrylic adhesive compositions are described, for example, in Japanese Patent No. 4140736, which is incorporated herein by reference.

[0131] The thickness of the first adhesive layer is preferably 3 μm to 30 μm, more preferably 5 μm to 10 μm. If the thickness of the first adhesive layer is within this range, it has the advantages of sufficient adhesion and minimal impact of the adhesive layer thickness relative to the overall thickness. Furthermore, the desired thickness ratio described above can be easily achieved.

[0132] B-5. Second Adhesive Layer

[0133] The second adhesive layer is applied to devices such as vehicles that experience continuous vibration during use, and is formed of an adhesive that has the flexibility to absorb the transmission of such vibrations and suppress damage to the low-refractive-index layer. As described above, the storage modulus of the second adhesive layer at 23°C is, for example, 1.0 × 10⁻⁶. 5 (Pa) or less, for example, 1.0 × 10 5 (Pa) below, 9.5×10 4 (Pa) or less, 9.0×10 4 (Pa) below, 8.5×10 4 (Pa) below, 8.0×10 4 (Pa) below, 7.5×10 4 (Pa) or below, or 7.0×10 4 (Pa) or less, and 1.0 × 10 3 (Pa) or above, 5.0×10 3 (Pa) or above, 1.0×10 4 (Pa) or above, or 5.0 × 10 4 (Pa) or higher, preferably 5.0 × 10 Pa. 3 (Pa)~9.0×10 4 (Pa) or less, more preferably 1.0 × 10 4 (Pa)~8.5×10 4 (Pa).

[0134] As the adhesive constituting the second adhesive layer, any suitable adhesive can be used as long as it has the properties described above. Acrylic adhesives (acrylic adhesive compositions) are representative examples of adhesives. Acrylic adhesive compositions are as described in section B-4 above. However, the adhesive constituting the second adhesive layer preferably does not contain heterocyclic (meth)acrylates as comonomers. Furthermore, the weight-average molecular weight (Mw) of the base polymer in the adhesive composition is preferably 2,000,000 or less, more preferably 5,000 to 1,600,000. Details of the second adhesive layer or the acrylic adhesive composition constituting the second adhesive layer are described, for example, in Japanese Patent Application Publication No. 2016-190996, the contents of which are incorporated herein by reference.

[0135] The thickness of the second adhesive layer is preferably 5 μm to 300 μm, more preferably 10 μm to 200 μm. If the thickness of the second adhesive layer is within this range, it can mitigate impact and reduce damage to the low-refractive-index layer, especially during lateral vibration, and can reduce strain within the structure generated during image display device assembly. As a result, it can reduce brightness unevenness during image display. Furthermore, the aforementioned desired thickness ratio can be easily achieved.

[0136] C. Surface treatment layer

[0137] The coefficient of kinetic friction of the surface treatment layer is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.5 or less. A lower coefficient of kinetic friction is preferred, with a lower limit of, for example, 0.1. If the coefficient of kinetic friction is within such a range, it is possible to suppress the degradation of display quality caused by wear or scratches between the light guide plate and the reflector plate, and / or between the light guide plate and the housing, due to vibrations of the optical components during use. That is, by providing the surface treatment layer as the outermost layer, the optical components can slide easily, thereby significantly suppressing wear or scratches during vibrations (between the light guide plate and the reflector plate, and / or between the light guide plate and the housing). As a result, it is possible to suppress the degradation of display quality (essentially the display quality of the image display device). Furthermore, the synergistic effect of providing such a surface treatment layer and setting the storage modulus of the second adhesive layer to a given range can suppress damage to the low-refractive-index layer caused by vibration. It should be noted that the coefficient of kinetic friction can be measured based on the "Test Method for Coefficient of Friction" in JIS K 7125.

[0138] The surface treatment layer can be of any suitable configuration as long as it can be formed on the surface of the reflector and has the kinetic friction coefficient described above. In one embodiment, the surface treatment layer can be a hard coating. The hard coating preferably has a pencil hardness of H or higher, more preferably 2H or higher, and even more preferably 3H or higher. On the other hand, the pencil hardness of the hard coating is preferably 6H or lower, more preferably 5H or lower. If the pencil hardness of the hard coating is within such a range, it is possible to suppress the reduction in display quality caused by wear or scratches due to vibration, and to suppress the breakage of the low refractive index layer. The pencil hardness can be determined based on the "Pencil Hardness Test" of JIS K 5400.

[0139] The thickness of the hard coating is preferably 1 μm to 30 μm, more preferably 2 μm to 20 μm, and even more preferably 3 μm to 15 μm. If the thickness of the hard coating is within this range, wear or scratches can be suppressed more effectively. Furthermore, interference fringes can be suppressed while maintaining the hardness of a pencil as described above.

[0140] The hard coating can be made of any suitable material as long as it meets the characteristics described above. The hard coating is, for example, a cured layer of a thermosetting resin or an ionizing radiation (e.g., visible light, ultraviolet light) curable resin. Examples of such curable resins include: urethane (meth)acrylates, polyester (meth)acrylates, epoxy (meth)acrylates, silicone resins such as siloxanes, unsaturated polyesters, and epoxy resins.

[0141] Details of the hard coating are described in, for example, Japanese Patent Application Publication No. 2011-237789. The contents of that publication are incorporated herein by reference.

[0142] In one embodiment, the surface treatment layer may have an outermost layer containing fluorine on the surface of the hard coating opposite to the reflector. Forming such an outermost layer can further reduce the coefficient of dynamic friction of the surface treatment layer. The outermost layer can be formed, for example, by coating a solution containing a fluorinated resin (e.g., polytetrafluoroethylene) and then drying, solidifying, or sintering it. The thickness of the outermost layer is preferably 0.5 μm to 20.0 μm.

[0143] D. Backlight unit

[0144] The optical components described in items A through C above can be applied to backlight units (especially edge-lit backlight units). Therefore, embodiments of the present invention also include such backlight units. The backlight unit includes: the optical components described in items A through C above, and a light source. The light source can be, for example, an LED light source or an organic EL light source. The light source is configured to... Figure 1 The end face 10a of the light guide plate 10 is opposite to each other.

[0145] E. Image display device

[0146] The backlight unit described in item D above can be applied to image display devices (e.g., liquid crystal displays, etc.). Therefore, embodiments of the present invention also include such image display devices. The image display device includes: the backlight unit described in item D above, and an image display panel disposed on the emission surface side of a light guide plate.

[0147] Example

[0148] The present invention will now be specifically described through examples, but the invention is not limited to these examples. It should be noted that the methods for measuring each characteristic are as described below. Furthermore, unless otherwise specified, "%" and "parts" in the examples refer to weight.

[0149] [Manufacturing Example 1] Preparation of Coating Solution for Forming Low Refractive Index Layers

[0150] (1) Gel formation of silicon compounds

[0151] Mixture A was prepared by dissolving 0.95 g of methyltrimethoxysilane (MTMS), a precursor of silicon compounds, in 2.2 g of dimethyl sulfoxide (DMSO). 0.5 g of a 0.01 mol / L aqueous solution of oxalic acid was added to mixture A, and the mixture was stirred at room temperature for 30 minutes, thereby hydrolyzing MTMS to produce mixture B containing trihydroxymethylsilane.

[0152] After adding 0.38 g of 28% ammonia and 0.2 g of pure water to 5.5 g of DMSO, the above mixture B was further added, and the mixture was stirred at room temperature for 15 minutes to gel the trihydroxymethylsilane, thereby obtaining a mixture C containing a gel-like silicon compound.

[0153] (2) Aging treatment

[0154] The mixture C containing the gel-like silicon compound prepared as described above was directly incubated at 40°C for 20 hours to perform a curing treatment.

[0155] (3) Crushing process

[0156] Next, the gel-like silicon compound, after being cured as described above, was broken into particles ranging from several mm to several cm in size using a scraper. Then, 40 g of isopropanol (IPA) was added to mixture C, and after gentle stirring, it was allowed to stand at room temperature for 6 hours to allow the solvent and catalyst in the gel to be decanted. Solvent replacement was achieved by performing the same decantation process three times, yielding mixture D. Next, the gel-like silicon compound in mixture D was subjected to a high-pressure, medium-free grinding process. The grinding process (high-pressure, medium-free grinding) was performed using a homogenizer (SMT Corporation, trade name "UH-50"). 1.85 g of the gel-like compound and 1.15 g of IPA from mixture D were weighed into a 5 cc screw-top bottle, and then ground for 2 minutes at 50 W and 20 kHz.

[0157] Through this pulverization process, the gel-like silicon compound in the above-mentioned mixture D is pulverized, thereby forming a sol solution of pulverized material in mixture D'. The volume average particle size, representing the particle size deviation, of the pulverized material contained in mixture D' was confirmed using a dynamic light scattering nano-trajectory particle size analyzer (manufactured by Nikkiso Corporation, UPA-EX150 type), and the result was 0.50 to 0.70. Furthermore, relative to 0.75 g of this sol solution (mixture C'), 0.062 g of a 1.5 wt% MEK (methyl ethyl ketone) solution of photoalkali-generating agent (Wako Pure Chemical Industries Co., Ltd.: trade name WPBG266) and 0.036 g of a 5 wt% MEK solution of bis(trimethoxysilyl)ethane were added to obtain a coating solution for forming a low refractive index layer.

[0158] [Manufacturing Example 2] Preparation of the adhesive constituting the first adhesive layer

[0159] In a four-necked flask equipped with a stirring blade, thermometer, nitrogen inlet tube, and condenser, 90.7 parts of butyl acrylate, 6 parts of N-acryloylmorpholine, 3 parts of acrylic acid, 0.3 parts of 2-hydroxybutyl acrylate, and 0.1 parts by weight of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) as a polymerization initiator, along with 100g of ethyl acetate, were added together. After nitrogen purging was performed by slowly stirring and introducing nitrogen gas, the liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. An acrylic adhesive solution was prepared by mixing 100 parts of the solids component of the obtained acrylic polymer solution with 0.2 parts of isocyanate crosslinking agent (CORONATE L, manufactured by Nippon Polyurethane Kogyo Co., Ltd., an adduct of trimethylolpropane and toluene diisocyanate), 0.3 parts of benzoyl peroxide (NYPER BMT, manufactured by Nippon Yushu Co., Ltd.), and 0.2 parts of γ-glycidoxypropylmethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.). Next, the acrylic adhesive solution was coated onto one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., thickness: 38 μm) to achieve a 20 μm thickness after drying, and then dried at 150°C for 3 minutes to form an adhesive layer. The storage modulus of the obtained adhesive was 1.3 × 10⁻⁶. 5 Pa.

[0160] [Manufacturing Example 3] Preparation of the adhesive constituting the second adhesive layer

[0161] In a four-necked flask equipped with a stirring blade, thermometer, nitrogen inlet tube, and condenser, 99 parts of butyl acrylate, 1 part of 4-hydroxybutyl acrylate, 0.1 parts of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) as a polymerization initiator, and 100 parts of ethyl acetate were added together. After nitrogen purging by slowly stirring, the liquid temperature in the flask was maintained at approximately 55°C, and the polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. Relative to 100 parts of the solid content of the obtained acrylic polymer solution, 0.1 parts of isocyanate crosslinking agent (Takenate D110N, trimethylolpropanebenzene diisocyanate, manufactured by Mitsui Takeda Chemical Co., Ltd.), 0.1 parts of benzoyl peroxide (NYPER BMT, manufactured by Nippon Yushi Co., Ltd.), and 0.2 parts of γ-glycidoxypropylmethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to prepare an acrylic adhesive composition solution. Next, the solution of the above acrylic adhesive composition was coated onto one side of a polyethylene terephthalate membrane (separator: Mitsubishi Chemical Polyester Membrane Co., Ltd., MRF38) treated with an organosilicon release agent, and dried at 150°C for 3 minutes, forming an adhesive layer with a thickness of 20 μm on the surface of the separator. The resulting adhesive had a storage modulus of 8.2 × 10⁻⁶. 4 Pa.

[0162] [Manufacturing Example 4] Fabrication of Double-Sided Adhesive Film

[0163] The low-refractive-index layer forming coating liquid prepared in Manufacturing Example 1 was applied to a substrate (acrylic film) with a thickness of 20 μm. The wet thickness (thickness before drying) of the coating layer was approximately 27 μm. The coating layer was dried by treating it at a temperature of 100°C for 1 minute, forming a low-refractive-index layer (thickness of 0.9 μm) on the substrate. The porosity of the resulting low-refractive-index layer was 56%, and the refractive index was 1.15. Next, a first adhesive layer (thickness of 10 μm) composed of the adhesive prepared in Manufacturing Example 2 was formed on the surface of the low-refractive-index layer, and a second adhesive layer (thickness of 28 μm) composed of the adhesive prepared in Manufacturing Example 3 was further formed on the surface of the substrate. In this way, a double-sided adhesive film with the structure of a first adhesive layer (high storage modulus) / low-refractive-index layer / substrate / second adhesive layer (low storage modulus) was produced. The ratio of the thickness of the low-refractive-index layer to the total thickness of the adhesive layers was 1.5%. It should be noted that the refractive index of the low-refractive-index layer was measured as described below.

[0164] After forming a low-refractive-index layer on an acrylic film, it was cut into 50mm × 50mm pieces and bonded to the surface of a glass plate (thickness: 3mm) via an adhesive layer. The central portion (approximately 20mm in diameter) of the back side of the glass plate was filled with black marker, resulting in a sample that does not reflect light from the back side of the glass plate. The refractive index of the sample was measured using an ellipsometry (JAWoollam Japan: VASE) at a wavelength of 550nm and an incident angle of 50–80 degrees.

[0165] [Manufacturing Example 5] Preparation of Hard Coating Forming Material

[0166] A UV-curable resin monomer or oligomer, primarily composed of urethane acrylate, was dissolved in butyl acetate. In the resulting resin solution (manufactured by DIC, trade name "UNIDIC 17-806", solids concentration 80%), 5 parts of a photopolymerization initiator (manufactured by BASF, product name "IRGACURE906") and 0.03 parts of a leveling agent (manufactured by DIC, product name "GRANDIC C4100") were added per 100 parts of the solids in the solution. Then, butyl acetate was added to the solution to achieve a solids concentration of 75%. Cyclopentanone was further added to the solution to achieve a solids concentration of 50%. This prepared a hard coating forming material for forming hard coatings.

[0167] [Example 1]

[0168] The hard coating forming material obtained in Manufacturing Example 5 was applied to one surface of a reflector (manufactured by Toray Industries, Inc., trade name "Lumirror (registered trademark) #225E6SR") using a die-coating machine to form a coating film. The hard coating forming material was applied to a thickness of 13.8 μm to achieve a cured coating film (hard coating) thickness of 7.5 μm. The coating film was dried at 80°C for 2 minutes, and then irradiated with a high-pressure mercury lamp with a cumulative light intensity of 300 mJ / cm². 2 Ultraviolet light is used to form a hard coating. The hard coating has a coefficient of kinetic friction of 0.8 and a pencil hardness of 2H. The surface of the reflector without the hard coating is bonded to the double-sided adhesive film obtained in Manufacturing Example 4, separated by a second adhesive layer. A commercially available light guide plate is then bonded to the reflector through a first adhesive layer to create an optical component. It should be noted that the coefficient of kinetic friction was determined based on the "Test Method for Coefficient of Friction" in JIS K 7125, and the pencil hardness was determined based on the "Pencil Hardness Test" in JIS K 5400.

[0169] (I) Scar test

[0170] A laminate of a double-sided adhesive film / reflector used in optical components was subjected to a scratch test, as described below. The laminate was cut to 50mm × 1500mm dimensions and bonded to a glass plate with a first adhesive layer in between, thus creating a test sample. Next, the test sample's reflector (essentially a hard coating) was placed on a tray in contact with a diffuser sheet (manufactured by Sumitomo 3M Corporation, trade name "DBEF-D2-400"), and a vibration test of 200 vibrations / min × 10 minutes was conducted. Scratches on the reflector were visually inspected after the vibration test, and the results were evaluated based on the following criteria, as shown in Table 1.

[0171] Good: No scratches were found on the reflector surface.

[0172] Defect: Scratches were found on the reflector surface.

[0173] (II) Reoperability

[0174] The obtained optical components were placed on the back side housing of the liquid crystal display device, removed, and then placed back on the back side housing. The results were evaluated based on the following criteria and are shown in Table 1.

[0175] Good: Can be further configured

[0176] Defect: Unable to be reconfigured (damaged stack-up)

[0177] [Example 2]

[0178] A fluorine coating was formed on the surface of the hard coating as the outermost fluorine-containing layer. Otherwise, the optical component was fabricated in the same manner as in Example 1. It should be noted that the fluorine coating was formed using a commercially available fluorine-containing resin coating spray (manufactured by Taihei Kasei Corporation, trade name "JET PROTECTOR F-200SI"). The thickness of the fluorine coating was 15 μm, and the coefficient of kinetic friction was 0.4. The resulting optical component was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[0179] [Comparative Example 1]

[0180] No hard coating was formed; otherwise, the optical component was fabricated in the same manner as in Example 1. It should be noted that the coefficient of kinetic friction on the reflector surface was 1.1. The resulting optical component was evaluated in the same way as in Example 1, and the results are shown in Table 1.

[0181] [Comparative Example 2]

[0182] After attaching the reflector surface of the optical component of Comparative Example 1 to the back side housing of the liquid crystal display device using a commercially available double-sided tape, it was peeled off and reattached (attached) to the back side housing. The evaluation was carried out according to the same criteria as Example 1, and the results are shown in Table 1.

[0183] [Table 1]

[0184] coefficient of kinetic friction Scar test Reoperability Example 1 0.8 good good Example 2 0.4 good good Comparative Example 1 1.1 bad good Comparative Example 2 － － bad

[0185] As can be clearly seen from Table 1, according to embodiments of the present invention, an optical component that suppresses damage caused by vibration can be achieved. It is understood that such an optical component suppresses the degradation of display quality caused by scratches and abrasion. Furthermore, according to embodiments of the present invention, even with vibration, the low-refractive-index layer will not break.

[0186] Industrial applicability

[0187] The optical components of this invention can be applied to the backlight unit of an image display device (particularly a liquid crystal display device). The image display device can be used for automotive and / or entertainment applications.

Claims

1. An optical component having: A light guide plate having an incident end face from a light source and an exit face for escaping the incident light; and A reflector, which is bonded to the side of the light guide plate opposite to the emitting surface, through a double-sided adhesive film. The double-sided adhesive film has a first adhesive layer, a low refractive index layer, and a second adhesive layer from the light guide plate side. The first adhesive layer has a storage modulus of 1.2 × 10⁻⁶ at 23°C. 5 Above Pa, the storage modulus of the second adhesive layer at 23°C is 9.0 × 10⁻⁶. 4 Below Pa, A surface treatment layer is formed on the side of the reflector opposite to the double-sided adhesive film.

2. The optical component according to claim 1, wherein, The coefficient of dynamic friction of the surface treatment layer is below 1.

0.

3. The optical component according to claim 1 or 2, wherein, The surface treatment layer is a hard coating with a pencil hardness of H or higher.

4. The optical component according to claim 3, wherein, The surface treatment layer further has an outermost layer containing fluorine on the surface of the hard coating on the side opposite to the reflector.

5. A backlight unit, comprising: The optical component according to any one of claims 1 to 4, and light source, The light source is configured to face the end face of the light guide plate.

6. An image display device, comprising: The backlight unit as described in claim 5, and An image display panel disposed on the emission surface side of the light guide plate.

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