Optical film, and optical stack and eyewear having the same

Abstract

The present application aims to provide eyewear such as polarized sunglasses using an optical film having a light reflection layer and a polarizing element layer, eyewear having a metallic color tone that meets the signal recognition standards of various countries, and an optical film and an optical laminate for the eyewear. The present application provides an optical film in which a light reflection layer and a polarizing element layer are laminated, which satisfies any one or more of the following (a) to (d). (a) The center reflection wavelength of the light reflection layer is 600 nm or more and less than 660 nm, and the transmission color phase of the optical film is in a region where -15 ≤ a* ≤ 10 and -20 ≤ b* ≤ 20. (b) The center reflection wavelength of the light reflection layer is 500 nm or more and less than 600 nm, and the transmission color phase of the optical film is in a region where -5 ≤ a* ≤ 20 and -20 ≤ b* ≤ 30. (c) The center reflection wavelength of the light reflection layer is 660 nm or more and less than 750 nm, and the transmission color phase of the optical film is in a region where -10 ≤ a* ≤ 10 and -5 ≤ b* ≤ 35. (d) The center reflection wavelength of the light reflection layer is 400 nm or more and less than 500 nm, and the minimum light transmittance of the light reflection layer of 400 nm or more and less than 500 nm is 15% or more, and the transmission color phase of the optical film is in a region where -15 ≤ a* ≤ 25 and -10 ≤ b* ≤ 40.

Description

Technical Field

[0001] This invention relates to optical films mainly used in protective goggles (sunglasses, goggles, helmet visors, etc.), as well as optical laminates having the optical films and protective goggles. Background Technology

[0002] To reduce glare caused by reflected light from water, roads, snow, etc., protective eyewear (sunglasses, goggles, face shields, etc.) is used. For example, sunglasses use pigments in the lens to absorb light and reduce the amount of light entering the eyes, thus reducing glare. Polarized sunglasses are particularly effective for reflected light from water and snow. Because reflected light is polarized, by designing polarized sunglasses to effectively absorb light in that polarized direction, glare can be reduced without significantly decreasing the amount of light entering the eyes, improving visibility.

[0003] Polarized sunglasses are typically constructed by clamping a polarizing element layer with a plastic support such as polycarbonate, shaping it into the desired form, and embedding it into a frame. The polarizing element layer is a film obtained by uniaxially aligning a dichroic dye, a polyiodine-polyvinyl alcohol (PVA) coordination compound (so-called dichroic pigment), and a polymer such as PVA. Depending on the color of the pigment used, polarizing element layers of various colors can be obtained. In conventional sunglasses, to impart polarization to the entire visible light spectrum, they are mostly formed in gray tones.

[0004] To add design flair or further enhance visibility to polarized sunglasses, multiple layers are sometimes vapor-deposited onto the surface. By applying multiple layers, the reflected light from the sunglasses' surface appears to others to have metallic hues such as blue, green, or red. The wearer's side, by reflecting specific light, reduces glare and further improves the visibility of scenery. While this multi-layered coating is beneficial to the wearer, there are operational issues such as the difficulty in removing sebum and other substances adhering to the coating; stability issues such as coating peeling in environments exposed to water and wind, such as the ocean; and manufacturing challenges such as the difficulty in uniformly vapor-depositing the coating on both the front and curved surfaces when applying it to curved lenses used in goggles.

[0005] For this type of problem, one approach is to place a multilayer film on the inner side of the support, i.e., between the polarizing element layer and the support. However, due to the refractive index difference between the layers, the multilayer film exhibits reflectivity, making it difficult to achieve the same reflectivity as the outer air interface. Furthermore, since the multilayer film is composed of inorganic materials, there are problems with bonding it to the organic polarizing element layer.

[0006] On the other hand, as a method of imparting metallic hues to metals without using multilayer films, there is a method using a cholesteric liquid crystal layer as described in Japanese Patent Application Publication No. 2001-180200 (Patent Document 1). Cholesteric liquid crystals are liquid crystal molecules in a helical orientation, and depending on the length of the helical pitch, they have the function of selectively reflecting circularly polarized light components that are in the same orientation as the helical orientation in a specific wavelength range. Using an optical stack of a cholesteric liquid crystal layer obtained by fixing this helical orientation to a state that corresponds to the desired reflection wavelength range, a vibrant hue can be achieved, thus imparting decorative qualities.

[0007] Cholesterol-type liquid crystals are capable of reflecting circularly polarized light components in a specific wavelength range. That is, only circularly polarized light is transmitted. When combined with a polarizing element layer, the polarizing element layer cannot fully absorb the transmitted light, resulting in increased light leakage from the polarizing element layer and a reduction in its original function as a polarized sunglasses.

[0008] As a technique to suppress the decrease in polarization of protective glasses such as polarized sunglasses with cholesterol-type liquid crystals, the inventors of this invention proposed a method in WO2016 / 002582 (Patent Document 4) to suppress the decrease in polarization by using a right-handed helical oriented cholesterol-type liquid crystal layer R and a left-handed helical oriented cholesterol-type liquid crystal layer L as a stack of cholesterol-type liquid crystal layers.

[0009] The goggles with multi-layer films applied by vapor deposition and the goggles using cholesterol-type liquid crystals as described in Patent Document 4 have excellent design, appearance and polarization characteristics, and can play a superior role, mainly in sports applications.

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Publication No. 2001-180200

[0013] Patent Document 2: Japanese Patent Application Publication No. 2003-315556

[0014] Patent Document 3: Japanese Patent Application Publication No. 2004-29824

[0015] Patent Document 4: WO2016 / 002582 Summary of the Invention

[0016] The problem that the invention aims to solve

[0017] On the one hand, most of the goggles mentioned above are not suitable for the following conditions (Tables 1-3 below) and Figure 1Therefore, the signal identification standards of various countries (ISO 12312-1:2013, ANSI Z80.3:2010, AS / NZS 1067:2003, etc.) cannot be used for driving passenger vehicles, resulting in limitations on their application.

[0018] [Table 1]

[0019] Table 1. Signal identification standards for protective goggles as specified in ISO 12312-1:2013

[0020] project Specification Light source - D65, TV Spectrum, T(475-650nm) ≥0.20Tv Incandescent lamp Red signal attenuation, Qred ≥0.8 Yellow signal attenuation, Qyellow ≥0.6 Green signal attenuation, Qgreen ≥0.6 Blue signal attenuation, Qblue ≥0.6

[0021] [Table 2]

[0022] Table 2. Signal identification standards for safety goggles as specified in ANSI Z80.3:2010

[0023] project Specification Light source - C, TV Spectrum, T(475-650nm) ≥0.20Tv X - Yellow Colorimetric table Y-Yellow Colorimetric table X-Green Colorimetric table Y-Green Colorimetric table X-D65 Colorimetric table Y-D65 Colorimetric table Red signal T ≥8％ Yellow signal T ≥6％ Green signal T ≥6％

[0024] [Table 3]

[0025] Table 3. Signal identification standards for protective goggles as specified in AS / NZS 1067:2003

[0026] project Specification Light source - D65, TV － Spectrum, T(450-650nm) ≥0.20Tv Red signal attenuation, Qred ≥0.8 Yellow signal attenuation, Qyellow ≥0.8 Green signal attenuation, Qgreen ≥0.6 Blue signal attenuation, Qblue ≥0.7

[0027] The present invention was made in view of the above circumstances, and aims to provide polarized sunglasses and the like, which are suitable for signal identification standards in various countries, have a metallic tint, and optical films and optical laminates for the glasses.

[0028] Methods for solving problems

[0029] In order to solve the above-mentioned problems, the inventors of the present invention conducted in-depth research and made a new discovery: by using an optical film in the goggles that has at least a light-reflecting layer and a polarizing element layer, and is not limited to the reflection wavelength of the light-reflecting layer, or adjusts the transmission hue a* and b* values ​​according to a specific reflection wavelength, it is possible to achieve goggles with performance suitable for signal identification standards of various countries, thereby completing the present invention.

[0030] That is, the present invention relates to the following (1) to (8).

[0031] (1) An optical film having a light-reflecting layer and a polarizing element layer stacked together, satisfying any one or more of the following (a) to (d).

[0032] (a) The central reflection wavelength of the light-reflecting layer is above 600 nm and below 660 nm, and the transmission hue of the optical film is in the region of -15 ≤ a* ≤ 10 and -20 ≤ b* ≤ 20.

[0033] (b) The central reflection wavelength of the light-reflecting layer is above 500 nm and below 600 nm, and the transmission hue of the optical film is in the region of -5 ≤ a* ≤ 20 and -20 ≤ b* ≤ 30.

[0034] (c) The central reflection wavelength of the light-reflecting layer is above 660nm and below 750nm, and the transmission hue of the optical film is in the region of -10≤a*≤10 and -5≤b*≤35.

[0035] (d) The central reflection wavelength of the light-reflecting layer is above 400 nm and below 500 nm, and the minimum transmittance of the light-reflecting layer above 400 nm and below 500 nm is above 15%, and the transmission hue of the optical film is in the region of -15≤a*≤25 and -10≤b*≤40.

[0036] (2) The optical film as described in (1), wherein the light-reflecting layer comprises one or more cholesterol-type liquid crystal layers.

[0037] (3) The optical film as described in (1) or (2), wherein the light-reflecting layer comprises a cholesteric liquid crystal layer R having a right-handed helical orientation and a cholesteric liquid crystal layer L having a left-handed helical orientation.

[0038] (4) The optical film as described in any one of (1) to (3), wherein the polarizing element layer comprises a stretched polymer film containing a dichroic pigment.

[0039] (5) The optical film as described in any one of (1) to (4), wherein it meets the relevant specifications for the distinguishability of traffic signals as specified in ISO 12312-1:2013, ANSI Z80.3:2010 and / or AS / NZS 1067:2003.

[0040] (6) An optical stack in which the optical film of any one of (1) to (5) is disposed between the first support and the second support.

[0041] (7) The optical stack as described in (6), wherein the first and second supports are polycarbonate.

[0042] (8) A goggle having an optical film as described in any one of (1) to (5), or an optical laminate as described in (6) or (7).

[0043] The effects of the invention

[0044] The present invention can provide protective goggles such as polarized sunglasses with metallic tints that are suitable for signal identification standards in various countries, as well as optical films and optical laminates for the protective goggles. Attached Figure Description

[0045] Figure 1 It is a chromaticity diagram representing the acceptable range in the CIE standard marking system for traffic signals and sunlight as specified in ANSI Z80.3:2010, concerning the visibility of these signals through goggles.

[0046] Figure 2 This is a graph showing the spectral characteristics of the light-reflecting layer, polarizing element layer, and optical stack in Example 6. Detailed Implementation

[0047] The optical film of the present invention has at least a light-reflecting layer that reflects visible light and a polarizing element layer.

[0048] The light-reflecting layer is appropriately selected based on the desired hue of the reflected color, within the visible light range, specifically in the reflection wavelength region, such as a central reflection wavelength of 400nm–800nm, preferably 410–780nm, and more preferably 430–700nm. For example, at a central reflection wavelength of 400nm–500nm, the reflected color is a metallic blue; at 500nm–600nm, a metallic green; at 600nm–660nm, a metallic orange; and at 660nm–750nm, a metallic red. Hereinafter, the reflection wavelength regions of 400nm–500nm, 500nm–600nm, 600nm–660nm, and 660nm–750nm, which include the central reflection wavelength, will also be referred to as the "central reflection wavelength region".

[0049] Here, the reflected wavelength of the light-reflecting layer is located within the reflected wavelength region, and is represented by the center value of this reflected wavelength region, i.e., the center reflected wavelength. The center reflected wavelength refers to the center wavelength of the reflected region of the light-reflecting layer, and its value is the midpoint between the wavelengths on the short-wavelength side and the long-wavelength side where the transmittance in the reflected region is 75% during spectrophotometry. For example, when performing spectrophotometry on a certain light-reflecting layer, if the wavelength on the short-wavelength side where the transmittance in the reflected region is 75% is 500 nm and the wavelength on the long-wavelength side is 600 nm, then the center reflected wavelength of this light-reflecting layer is 550 nm. Furthermore, the transmittance used in the center wavelength calculation can be selected based on the waveform shape, the lowest transmittance of the region, etc., and the transmittance used in this specification and claims is 75%.

[0050] The visual sensitivity of the human eye varies depending on the wavelength range of visible light. Within this relationship, the transmitted hue, which meets the signal recognition criteria, also differs depending on the wavelength range reflected by the light-reflecting layer. Here, transmitted hue refers to the hue of light that appears when it passes through an object such as an optical film.

[0051] When the central reflection wavelength of the light-reflecting layer is in the region of 600 nm or more but less than 660 nm (the light source is a C light source or a D65 light source), the transmission hue of the optical film is in the region of -15 ≤ a* ≤ 10 and -20 ≤ b* ≤ 20, more preferably -10 ≤ a* ≤ 10 and -10 ≤ b* ≤ 10, and even more preferably -10 ≤ a* ≤ 5 and -5 ≤ b* ≤ 5. When the transmission hue is in this region, it meets the signal distinguishability standard. Furthermore, the minimum transmittance of the light-reflecting layer in this central reflection wavelength region is preferably 21% or more, more preferably 25% or more, more preferably 30% or more, and particularly preferably 40% or more. Moreover, from the viewpoint of aesthetic design (metallic tone), the upper limit is approximately 90%, more preferably approximately 80%.

[0052] When the central reflection wavelength of the light-reflecting layer is in the region of 500 nm or more but less than 600 nm (the light source is a C light source or a D65 light source), the transmission hue of the optical film is in the region of -5 ≤ a* ≤ 20 and -20 ≤ b* ≤ 30, preferably in the region of -5 ≤ a* ≤ 10 and -15 ≤ b* ≤ 15, more preferably in the region of -5 ≤ a* ≤ 10 and -15 ≤ b* ≤ 5, and even more preferably in the region of -5 ≤ a* ≤ 5 and -5 ≤ b* ≤ 5. When the transmission hue is in this region, it meets the signal distinguishability standard. Furthermore, the minimum transmittance of the reflective layer in this central reflection wavelength region is preferably 20% or more, more preferably 21% or more, more preferably 30% or more, and particularly preferably 40% or more. Moreover, from the viewpoint of aesthetic design (metallic tone), the upper limit is approximately 90%, more preferably approximately 80%.

[0053] When the central reflection wavelength of the light-reflecting layer is in the region of 660 nm or more and below 750 nm (the light source is a C light source or a D65 light source), the transmission hue of the optical film is in the region of -10 ≤ a* ≤ 10 and -5 ≤ b* ≤ 35, preferably -10 ≤ a* ≤ 5 and -5 ≤ b* ≤ 15, more preferably -5 ≤ a* ≤ 5 and -5 ≤ b* ≤ 5. When the transmission hue is in this region, it meets the signal distinguishability standard. Furthermore, the minimum transmittance of the light-reflecting layer in this central reflection wavelength region is preferably 15% or more, more preferably 21% or more, more preferably 25% or more, and particularly preferably 30% or more. Moreover, from the viewpoint of aesthetic design (metallic tone), the upper limit is approximately 90%, more preferably approximately 80%. Furthermore, when the a* value is within the region of -10 ≤ a* ≤ -5, the minimum transmittance of the light-reflecting layer within this reflection wavelength region is preferably 21% or more, more preferably 25% or more, and even more preferably 30% or more. b* is not particularly limited as long as it is within this region. In addition, from the viewpoint of appearance design (metallic tone), the upper limit of the minimum transmittance is about 90%, more preferably about 80%.

[0054] When the central reflection wavelength of the light-reflecting layer is in the region of 400nm or more but less than 500nm (the light source is a C light source or a D65 light source), the transmission hue of the optical film is in the region of -15≤a*≤25 and -10≤b*≤40, preferably -10≤a*≤10 and -10≤b*≤35, more preferably -10≤a*≤10 and -5≤b*≤35, and even more preferably -5≤a*≤5 and -5≤b*≤5. When the transmission hue is in this region, it meets the signal distinguishability standard. Furthermore, the minimum transmittance of the reflective layer in this central reflection wavelength region is 15% or more, preferably 20% or more, more preferably 21% or more, and even more preferably 30% or more. Moreover, from the viewpoint of aesthetic design (metallic tone), the upper limit of the minimum transmittance is approximately 90%, more preferably approximately 80%.

[0055] The transmission hue of the optical film is preferably within the region of -10 ≤ a* ≤ 10 and -10 ≤ b* ≤ 10, except in the case where the central reflection wavelength of the light-reflecting layer is 500 nm or more but less than 600 nm. In the case where the central reflection wavelength of the light-reflecting layer is 500 nm or more but less than 600 nm, the transmission hue of the optical film is preferably within the region of -5 ≤ a* ≤ 10 and -10 ≤ b* ≤ 10.), and more preferably within the region of -5 ≤ a* ≤ 5 and -5 ≤ b* ≤ 5. As long as the transmission hue is within this region, it meets the signal distinguishability standard. Furthermore, within this transmission hue region, the transmitted color appears natural, and when worn as goggles, a natural color is perceived, which is therefore preferred.

[0056] The preferred embodiment of this invention is a light-reflecting layer with a thickness of 0.1 μm to 10.0 μm. The lower limit of the light-reflecting layer thickness is preferably 0.5 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, or 1.3 μm (where a larger value is more preferred), and particularly preferably 1.4 μm. Furthermore, the upper limit is preferably 5.0 μm, 4.0 μm, 3.0 μm, 2.5 μm, 2.0 μm, 1.9 μm, 1.8 μm, or 1.7 μm (where a smaller value is more preferred), and particularly preferably 1.6 μm. That is, the most preferred range for the thickness of the light-reflecting layer is 1.4 μm to 1.6 μm.

[0057] The light-reflecting layer used in this invention to obtain the aforementioned transmitted hue is not particularly limited. Examples include known vapor-deposited multilayer films and cholesterol-type liquid crystal layers, with a cholesterol-type liquid crystal layer being preferred. The light-reflecting layer preferably comprises one or more cholesterol-type liquid crystal layers. Here, the light-reflecting layer may consist of only one cholesterol-type liquid crystal layer, or it may be a stack of two or more cholesterol-type liquid crystal layers. More preferably, the light-reflecting layer is a stack of a cholesterol-type liquid crystal layer R composed of a right-handed helical orientation and a cholesterol-type liquid crystal layer L composed of a left-handed helical orientation. By stacking this cholesterol-type liquid crystal layer R and cholesterol-type liquid crystal layer L, the reduction in polarization of the optical film of this invention is suppressed. For example, left-handed circularly polarized light that has passed through the cholesterol-type liquid crystal layer R is reflected by the cholesterol-type liquid crystal layer L, thereby suppressing the transmission of circularly polarized light and reducing the suppression of polarization function caused by the polarization element layer.

[0058] The light-reflecting layer preferably comprises a cholesteric liquid crystal layer R having a right-handed helical orientation and a cholesteric liquid crystal layer L having a left-handed helical orientation. Here, it is preferable that the reflection wavelengths of the cholesteric liquid crystal layer R and the cholesteric liquid crystal layer L are the same; particularly preferably, the deviation of the central reflection wavelength, which is the center of the reflection wavelength range, is between that of the cholesteric liquid crystal layer R and the cholesteric liquid crystal layer L, and is within 20 nm, more preferably within 10 nm, and even more preferably within 5 nm. According to the type of polarizing element layer used in this invention, for example, when it is a neutral gray polarizing element layer, if the deviation of the central reflection wavelength exceeds 20 nm, for example, left-handed circularly polarized light passing through the cholesteric liquid crystal layer R cannot be sufficiently reflected in the cholesteric liquid crystal layer L, resulting in a significant reduction in polarization, and sometimes leading to a decrease in the function of polarized sunglasses.

[0059] The light-reflecting layer used in this invention may comprise a group of multiple cholesterol-type liquid crystal layers R and L with different central reflection wavelengths. For example, when the cholesterol-type liquid crystal layers R and L, each with a central reflection wavelength of X nm, are designated as Rx and Lx respectively, by stacking a group of R450 and L450 with a group of R650 and L650, reflection can occur simultaneously near 450 nm and 650 nm. This combination is not particularly limited and can yield complex and diverse reflected colors.

[0060] Cholesterol-type liquid crystals are not particularly limited in that they can be formed from chiral nematic liquid crystals, liquid crystal compositions in which chiral reagents have been added to nematic liquid crystals, or compounds. Since the orientation of the helix and the reflection wavelength can be arbitrarily designed according to the type and amount of the chiral reagent, it is preferable to add a chiral reagent to a nematic liquid crystal to obtain a cholesterol-type liquid crystal. Nematic liquid crystals differ from so-called electric field-operated liquid crystals in that they are used by fixing the helical orientation state; therefore, it is preferable to use nematic liquid crystal monomers with polymerizable groups.

[0061] Nematic liquid crystal monomers with polymerizable groups are compounds that exhibit liquid crystal properties within a certain temperature or concentration range and contain polymerizable groups within the molecule. Examples of polymerizable groups include (meth)acrylamide, vinyl, carbonyl, cinnamoyl, or epoxy groups. Furthermore, to exhibit liquid crystal properties, it is preferable to have mesocrystalline groups within the molecule. Mesocrystalline groups refer to substituents such as rod-shaped, plate-shaped, or disk-shaped substituents with biphenyl, triphenyl, (poly)benzoyl benzoate, (poly)ether, benzylamino, and acenaphthenicotinamide groups, i.e., groups capable of inducing liquid crystal phase movement. Liquid crystal compounds with rod-shaped or plate-shaped groups are known in the art as rod-shaped liquid crystals. Specific examples of nematic liquid crystal monomers with polymerizable groups include the polymerizable liquid crystals described in Japanese Patent Application Publication No. 2003-315556 (Patent Document 2) and Japanese Patent Application Publication No. 2004-29824 (Patent Document 3), the PALIOCOLOR series (manufactured by BASF), such as PALIOCOLOR LC242 and PALIOCOLOR LC1057, and the RMM series (manufactured by Merck). These nematic liquid crystal monomers with polymerizable groups can be used alone or in combination.

[0062] As a chiral reagent, it is capable of orienting the aforementioned nematic liquid crystal monomer with polymerizable groups to either a right-handed or left-handed helical orientation, preferably a compound having polymerizable groups similar to those of the nematic liquid crystal monomer. Examples of such chiral reagents include Paliocolor LC756 (manufactured by BASF), Japanese Patent Application Publication No. 2002-179668, and Japanese Patent Application Publication No. 2007-271808, which describe compounds with an optically active binaphthyl structure, and Japanese Patent Application Publication Nos. 2003-306491 and 2003-313292, which describe compounds with an optically active isosorbide structure. The amount of chiral reagent added varies depending on the type of chiral reagent and the wavelength of reflection, and is preferably about 0.5 to 40 parts by weight, and more preferably about 1 to 25 parts by weight, relative to 100 parts by weight of the nematic liquid crystal monomer with polymerizable groups.

[0063] Furthermore, non-liquid-liquid polymeric compounds that can react with nematic liquid crystal monomers having polymeric groups can also be added to the liquid crystal composition. Examples of such compounds include UV-curable resins.Examples of UV-curable resins include dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate reacting with 1,6-hexamethylene diisocyanate, triisocyanates containing isocyanurate rings reacting with pentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate reacting with isoflurane diisocyanate, dipentaerythritol penta(meth)acrylate, dipentaerythritol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, tri( The reaction products of methacryloyloxyethyl isocyanurate, glyceryl triglycidyl ether and (meth)acrylic acid, caprolactone-modified tri(acryloyloxyethyl)isocyanurate, trimethylolpropane triglycidyl ether and (meth)acrylic acid, triglyceride di(meth)acrylate, propylene glycol diglycidyl ether and (meth)acrylic acid, polypropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, 1,6-hexanediol diglycidyl ether and (meth)acrylic acid ... Diol di(meth)acrylate, glycerol di(meth)acrylate, reaction product of ethylene glycol diglycidyl ether and (meth)acrylic acid, reaction product of diethylene glycol diglycidyl ether and (meth)acrylic acid, bis(acryloyloxyethyl)hydroxyethyl isocyanurate, bis(methacryloyloxyethyl)hydroxyethyl isocyanurate, reaction product of bisphenol A diglycidyl ether and (meth)acrylic acid, tetrahydrofuranyl (meth)acrylate, caprolactone-modified tetrahydrofuranyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polypropylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, phenoxyhydroxypropyl (meth)acrylate, propylene Acyloxymorpholine, methoxy polyethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxyethyl (meth)acrylate, glycidyl (meth)acrylate, glycerol (meth)acrylate, diethylene glycol ethyl ether (meth)acrylate, 2-ethoxyethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, the reaction product of butyl glycidyl ether and (meth)acrylic acid, butoxytriethylene glycol (meth)acrylate, and butanediol mono(meth)acrylate, etc., can be used alone or in combination.These non-liquid crystal UV-curable resins must be added in a manner that does not impair the liquid crystal properties of the liquid crystal composition. Preferably, the amount is 0.1 to 20 parts by weight, more preferably 1.0 to 10 parts by weight, relative to 100 parts by weight of the nematic liquid crystal monomer with polymerizable groups.

[0064] The liquid crystal composition may also contain a solvent. The solvent is not particularly limited as long as it can dissolve the liquid crystal monomers, chiral reagents, etc. used; examples include cyclopentane, methyl ethyl ketone, methyl isobutyl ketone, and toluene. The amount of solvent added is only required to dissolve the liquid crystal monomers, chiral reagents, etc. used, and can be appropriately determined by those skilled in the art.

[0065] When the nematic liquid crystal monomers and other polymeric compounds with polymerizable groups used in this invention are UV-curable, a photopolymerization initiator can be further added to the liquid crystal composition in order to use ultraviolet light to cure the liquid crystal composition. Examples of photopolymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1 (BASF Irgacure 907), 1-hydroxycyclohexylphenyl ketone (BASF Irgacure 184), 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl) ketone (BASF Irgacure 2959), 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one (Merck Darocur 953), 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one (Merck Darocur 1116), and 2-hydroxy-2-methyl-1-phenylpropane-1-one (BASF Irgacure). 1173), and acetophenone compounds such as diethoxyacetophenone; benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-2-phenylacetophenone (BASF Irgacure 651); benzoylbenzoic acid, methyl benzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl diphenyl sulfide, and 3,3'-dimethyl-4-methoxybenzophenone (Nippon Kayaku Co., Ltd. KAYACURE MBP); and thioxanone, 2-chlorothioxanone (Nippon Kayaku Co., Ltd. KAYACURE CTX), 2-methylthioxanone, 2,4-dimethylthioxanone (KAYACURE RTX), isopropylthioxanone, 2,4-dichlorothioxanone (Nippon Kayaku Co., Ltd. KAYACURE). Thioxanone compounds such as CTX, 2,4-diethylthioxanone (KAYACURE DETX, Nippon Kayaku), and 2,4-diisopropylthioxanone (KAYACURE DITX, Nippon Kayaku).Preferred photopolymerization initiators include, for example, Irgacure TPO, Irgacure TPO-L, Irgacure OXE01, Irgacure OXE02, Irgacure 1300, Irgacure 184, Irgacure 369, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 907, and Irgacure 1173 (all manufactured by BASF), with particularly preferred examples being Irgacure TPO, Irgacure TPO-L, Irgacure OXE01, Irgacure OXE02, Irgacure 1300, and Irgacure 907. These photopolymerization initiators can be used singly or in mixtures in any proportion. Preferably, at least one photopolymerization initiator with an absorption band at wavelengths above 300 nm is used.

[0066] When using benzophenone-based or thioxanthone-based compounds, auxiliaries can be used in conjunction to promote the photopolymerization reaction. Examples of such auxiliaries include amine compounds such as triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michlechne, 4,4'-diethylaminophenol, ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy) ester, and isoamyl 4-dimethylaminobenzoate.

[0067] The amounts of the aforementioned photopolymerization initiator and additives are preferably used within a range that does not affect the liquid crystallinity of the liquid crystal composition. Relative to 100 parts by weight of the UV-curable compound in the liquid crystal composition, the amount is preferably 0.5 to 10 parts by weight, more preferably 2 to 8 parts by weight. Furthermore, the additives are preferably 0.5 to 2 times the amount of the photopolymerization initiator by weight.

[0068] As a method for preparing a light-reflecting layer using cholesteric liquid crystals, a necessary amount of a chiral agent, called a dextrorotatory or levorotatory agent, is added to a nematic liquid crystal monomer having polymerizable groups in a manner that reflects the desired wavelength. These are then dissolved in a solvent, and a photopolymerization initiator is added to prepare a liquid crystal composition. This liquid crystal composition is then coated onto a plastic substrate such as a PET film to achieve a uniform thickness. The solvent is removed by heating, and the mixture is left at a temperature condition that allows the cholesteric liquid crystal to form on the substrate and be oriented with the desired helical pitch for a certain period of time. The preferred drying and orientation temperatures are 40–150°C. At this time, by performing an orientation treatment such as rubbing or stretching on the surface of the plastic film before coating, the orientation of the cholesteric liquid crystal can be made more uniform, and the haze value during film preparation can be reduced. Then, maintaining this orientation, the film is irradiated with ultraviolet light using a high-pressure mercury lamp or the like to fix the orientation, thereby obtaining a light-reflecting layer. Here, when a chiral reagent with a right-handed helical orientation is selected, a cholesterol-type liquid crystal layer R is obtained; when a chiral reagent with a left-handed helical orientation is selected, a cholesterol-type liquid crystal layer L is obtained. The cholesterol-type liquid crystal layer R selectively reflects right-handed circularly polarized light, and the cholesterol-type liquid crystal layer L selectively reflects left-handed circularly polarized light. This phenomenon of selectively reflecting specific circularly polarized light is called selective reflection, and the wavelength region of selective reflection is called the selective reflection region. In the claims and description of this application, the reflection region of the cholesterol-type liquid crystal layer refers to the selective reflection region.

[0069] There are no particular limitations on the method of laminating cholesterol-type liquid crystal layers together. Examples include direct lamination and lamination using adhesives or binders; lamination using adhesives or binders is preferred. As adhesives, examples include acrylate-based and rubber-based adhesives; acrylic adhesives, which are easy to adjust in terms of adhesion and holding power, are preferred. Furthermore, as adhesives, examples include UV-curable resin compositions and thermosetting resin compositions. When it is a UV-curable resin, a composition obtained by mixing various monomers having acryloyloxy or epoxy groups can be cured and bonded by irradiating it with ultraviolet light in the presence of a photopolymerization initiator. When it is a thermosetting resin composition, a composition obtained by mixing various monomers having epoxy groups can be cured and bonded by heating it in the presence of an oxygen catalyst. Alternatively, a composition consisting of various monomers and polymers having amino, carboxyl, or hydroxyl groups can be cured and bonded by heating it in the presence of a compound having isocyanate groups or melamine.

[0070] As the polarizing element layer used in this invention, a polarizing element layer comprising a stretched polymer film containing a dichroic dye is preferred. Typical examples of polarizing element layers usable in this invention include PVA polarizing films. The manufacturing method is not particularly limited, but from a heat resistance perspective, it is preferable to adsorb the dichroic dye onto a polymer film composed of polyvinyl alcohol or its derivatives, and then uniaxially stretch and orient the film. As the dye, direct dyes composed of azo dyes having sulfonic acid groups are particularly preferred.

[0071] Regarding the polarizing element layer used in this invention, relative to the light reflecting layer reflecting the desired wavelength, it is preferable that the product (T0%) of the minimum transmittance of the light reflecting layer and the transmittance of the polarizing element layer in the central reflection wavelength region of the light reflecting layer is preferably 5% or more, more preferably 10% or more, and the difference (T2-T1) between the average value (T1%) of the product of the transmittance of the light reflecting layer and the transmittance of the polarizing element layer in the central reflection wavelength region of the light reflecting layer and the average value (T2%) of the product of the transmittance of the light reflecting layer and the transmittance of the polarizing element layer in the visible light region of 400-750 nm excluding the central reflection wavelength region is -10 or more and 20 or less. More preferably, T2-T1 is -6 or more and 15 or less, and particularly preferably -3 or more and 10 or less. Here, the wavelength range of the central reflection wavelength region refers to, for example, the range of 500nm to 750nm when the central reflection wavelength region of the light-reflecting layer is 400nm to 500nm; the range of 400nm to 500nm and 600nm to 750nm when the central reflection wavelength region of the light-reflecting layer is 500nm to 600nm; the range of 400nm to 600nm and 660nm to 750nm when the central reflection wavelength region of the light-reflecting layer is 600nm to 660nm; and the range of 400nm to 660nm when the central reflection wavelength region of the light-reflecting layer is 660nm to 750nm. Therefore, the transmission spectrum of the stack of the light-reflecting layer and the polarizing element layer is nearly flat, allowing the transmitted color to be closer to natural.

[0072] The optical film of the present invention can be obtained by laminating a light-reflecting layer and a polarizing element. There are no particular limitations on the method of laminating the light-reflecting layer and the polarizing element; however, from the perspective of obtaining high adhesion, it is desirable to bond them together using an adhesive layer. As the adhesive layer, either a hot-melt adhesive or a curing adhesive can be used. Generally, as the curing adhesive, acrylic resin-based materials, polyurethane resin-based materials, polyester resin-based materials, melamine resin-based materials, epoxy resin-based materials, and silicone-based materials can be used. Particularly from the perspective of excellent adhesion during bending and processability, a two-component thermosetting polyurethane resin comprising a polyurethane prepolymer and a curing agent is preferred as the polyurethane resin-based material. An adhesive containing dissolved light-modifying dyes can also be used as the adhesive for bonding the light-reflecting layer and the polarizing element layer.

[0073] The optical film meets at least one of the traffic signal identification standards specified in ISO 12312-1:2013, ANSI Z80.3:2010 and AS / NZS 1067:2003, preferably all of these three standards.

[0074] The optical laminate of the present invention can be obtained by clamping an optical film with a support. In one embodiment, an optical film, particularly preferably the optical film of the present invention, is disposed between a first support and a second support. The support is preferably made of plastic, such as resins of polycarbonate, polyamide, and cellulose triacetate (TAC). In sunglasses or goggles requiring impact resistance and heat resistance, polycarbonate is preferably used in the support, and more preferably, aromatic polycarbonate made from bisphenol A is used. In the above embodiments, the first and second supports are preferably polycarbonate, and more preferably aromatic polycarbonate.

[0075] To ensure recognizability, the total light transmittance of the support is preferably 70% or more, more preferably 80% or more, and even more preferably 85% or more.

[0076] In addition, when the optimal processing temperature of each of the above-mentioned polarizing films is low, the raw materials used as the support are preferably selected from aromatic polycarbonate / alicyclopolyester compositions (particularly preferred are alicyclopolyesters with 1,4-cyclohexanedicarboxylic acid as the dicarboxylic acid component and 1,4-cyclohexanediethanol as the diol component), or polyamides with a glass transition temperature of 130°C or less.

[0077] Furthermore, a support can be provided between the light-reflecting layer and the polarizing element layer. This has advantages such as increasing the strength of the optical laminate. The method of clamping the support between the light-reflecting layer and the polarizing element layer is not particularly limited; however, to obtain high adhesion, it is desirable to clamp it with an adhesive layer. As the adhesive layer, either a hot-melt adhesive or a curing adhesive can be used. Generally, as a curing adhesive, materials such as acrylic resins, polyurethane resins, polyester resins, melamine resins, epoxy resins, and silicone resins can be used. Particularly considering excellent adhesion during bending and processability, a two-component thermosetting polyurethane resin comprising a polyurethane prepolymer and a curing agent is preferred as the polyurethane resin material.

[0078] The goggles of the present invention have the optical film of the present invention or the optical laminate of the present invention. Specifically, by using the optical film or optical laminate of the present invention obtained as described above, and shaping it into a desired shape such that the light-reflecting layer is further outward from the polarizing element layer than when viewed by the wearer, and fixing it to a frame or the like, it is possible to obtain goggles such as sunglasses, goggles, and helmet visors of the present invention.

[0079] These goggles are designed to meet the signal identification standards of various countries and feature a highly sophisticated metallic finish and anti-glare properties.

[0080] For example, in the case of sunglasses, the optical film or optical laminate can be punched into the desired shape and then bent. There are no particular limitations on the bending method; it can be performed through a process that imparts a spherical or aspherical shape corresponding to the intended purpose. For the bent product, resin can be further injected. This also has the advantage of reducing the appearance of thickness spots in the optical laminate, and can be used in lenses without focal refractive power, resulting in products with particularly excellent impact resistance, appearance, and eye fatigue reduction. As for the injected resin, to prevent appearance degradation due to refractive index differences, it is preferable that the layer in contact with the injected resin be the same material. After appropriately forming a hard coating, anti-reflective film, etc., on the surface, the lens is then fixed to a frame, etc., using methods such as lens grinding, drilling, and screw fixing, to obtain sunglasses.

[0081] Example

[0082] The present invention will be illustrated in detail below with reference to examples. In the examples, parts refer to parts by weight. Furthermore, the present invention is not limited to the illustrated examples.

[0083] <Formulation of Coating Solution (Liquid Crystal Composition)>

[0084] Prepare the coating solutions (R agent) and (L agent) with the compositions shown in the table below. In the table below, the quantities are expressed in parts by weight.

[0085] [Table 4]

[0086] Example of formulation of coating liquid (R agent)

[0087]

[0088] [Table 5]

[0089] Example of formulation of coating liquid (L agent)

[0090]

[0091] Chiral reagent: Compound 1 (Example compound 2-1 as described in Japanese Patent Application Publication No. 2002-179668)

[0092]

[0093] [Example 1]

[0094] <Fabrication of the Light Reflecting Layer>

[0095] Using the prepared coating solutions (R1) and (L1), light-reflecting layers are prepared according to the following steps, and then they are stacked to form a stack of light-reflecting layers used in this invention. Toyobo PET film (without a base coat) is used as the plastic substrate.

[0096] (1) Each coating liquid is applied to the PET film at room temperature using a wire rod so that the thickness of the dried film is 1.2 μm.

[0097] (2) Heat at 150°C for 5 minutes to remove the solvent and form a cholesterol-type liquid crystal phase. Then, irradiate with a high-pressure mercury lamp (manufactured by Harison Toshiba Lighting) at 120W output for 5-10 seconds to fix the cholesterol-type liquid crystal phase and obtain a light-reflecting layer.

[0098] (3) The cholesterol liquid crystal (R1) and cholesterol liquid crystal layer (L1) on the PET film prepared in (1) to (2) are laminated with an acrylic adhesive in such a way that the cholesterol liquid crystal layers are in contact with each other.

[0099] (4) Peel off the PET film on both sides.

[0100] Through this operation, a light-reflecting layer, consisting of two layers—a cholesterol-type liquid crystal layer (R1) and a cholesterol-type liquid crystal layer (L1)—is obtained, which is the light-reflecting layer used in this invention. The central reflection wavelengths of the cholesterol-type liquid crystal layer (R1) and the cholesterol-type liquid crystal layer (L1) are 615 nm and 620 nm, respectively.

[0101] <Fabrication of Polarization Element Layer>

[0102] Polyvinyl alcohol (manufactured by KURARAY Co., Ltd., trade name: KURARAYVinylon#750) was stained in an aqueous solution containing 0.41 g / L direct red (CHLORANTINE FAST RED, CI28160), 0.16 g / L direct yellow (CHrysophenine, CI24895), 0.14 g / L direct blue (Solophenyl Blue 4GL, CI34200), and 10 g / L sodium sulfate at 35°C for 3 minutes, and then stretched 4 times in the solution. Next, the stained slide was immersed in an aqueous solution containing 2.5 g / L nickel acetate and 6.6 g / L boric acid at 35°C for 3 minutes. Then, the slide was dried at room temperature for 3 minutes while kept taut, and then heat-treated at 70°C for 3 minutes to obtain a polarizing element layer. The polarization degree of the polarizing element layer was measured using a spectrophotometer by absolute polarization, and the result was a polarization degree of 97.1%.

[0103] <Fabrication of Optical Films>

[0104] Next, the above-mentioned stack of light-reflecting layers and polarizing element layers are bonded together with a polyurethane resin adhesive to obtain the optical film of the present invention.

[0105] <Fabrication of Optical Stacks>

[0106] An optical laminate is fabricated by bonding a 0.3 mm thick bisphenol A aromatic polycarbonate sheet (manufactured by Mitsubishi Gas Chemical Co., Ltd.) to both sides of the optical film using a polyurethane resin adhesive.

[0107] <Making Polarized Sunglasses>

[0108] The optical laminate is punched into a strip shape using a die with a basic shape of a perfect circle with a diameter of 79.5 mm and a vertical width of 55 mm. This strip is then bent using a die with an arc of 7.95 (radius of curvature of 66.67 mm). The bent optical laminate is inserted into an injection molding die, and molten polycarbonate is injected into the concave side to obtain a polarizing lens. Next, the lens is ground according to the frame, and the polarizing lens is then fitted into the frame, thus producing polarized sunglasses.

[0109] [Example 2]

[0110] <Fabrication of the Light Reflecting Layer>

[0111] Using the prepared coating solutions (R2) and (L2), the light-reflecting layers were coated to a thickness of 1.0 μm after drying, otherwise the same procedure as in Example 1 was performed, thereby obtaining the light-reflecting layers used in this invention. The center reflection wavelengths of both the cholesterol-type liquid crystal layer (R2) and the cholesterol-type liquid crystal layer (L2) are 560 nm.

[0112] <Fabrication of Polarization Element Layer>

[0113] Polyvinyl alcohol (manufactured by KURARAY Co., Ltd., trade name: KURARAYVinylon#750) was stained in an aqueous solution containing 0.07 g / L direct red (CHLORANTINE FAST RED, CI28160), 0.34 g / L direct yellow (CHrysophenine, CI24895), 0.3 g / L direct blue (Solophenyl Blue 4GL, CI34200), and 10 g / L sodium sulfate at 35°C for 3 minutes, and then stretched 4 times in the solution. Next, the stained slide was immersed in an aqueous solution containing 2.5 g / L nickel acetate and 6.6 g / L boric acid at 35°C for 3 minutes. Then, the slide was dried at room temperature for 3 minutes while kept taut, and then heat-treated at 70°C for 3 minutes to obtain a polarizing element layer. The polarization degree of the polarizing element layer was measured using a spectrophotometer by absolute polarization, and the result was a polarization degree of 98.2%.

[0114] In addition to using the light-reflecting layer and polarizing element layer described above, the optical film, optical stack, and polarized sunglasses of the present invention are obtained by the same operation as in Example 1.

[0115] [Example 3]

[0116] <Fabrication of the Light Reflecting Layer>

[0117] Using the prepared coating solutions (R3) and (L3), the light-reflecting layers were coated to a thickness of 1.5 μm after drying, otherwise the same procedure as in Example 1 was performed, thereby obtaining the light-reflecting layers used in this invention. The center reflection wavelengths of both the cholesterol-type liquid crystal layer (R3) and the cholesterol-type liquid crystal layer (L3) are 680 nm.

[0118] <Fabrication of Polarization Element Layer>

[0119] Polyvinyl alcohol (manufactured by KURARAY Co., Ltd., trade name: KURARAYVinylon#750) was stained in an aqueous solution containing 0.38 g / L direct red (CHLORANTINE FAST RED, CI28160), 0.16 g / L direct yellow (CHrysophenine, CI24895), 0.32 g / L direct blue (Solophenyl Blue 4GL, CI34200), and 10 g / L sodium sulfate at 35°C for 3 minutes, and then stretched 4 times in the solution. Next, the stained slide was immersed in an aqueous solution containing 2.5 g / L nickel acetate and 6.6 g / L boric acid at 35°C for 3 minutes. Then, the slide was dried at room temperature for 3 minutes while kept taut, and then heat-treated at 70°C for 3 minutes to obtain a polarizing element layer. The polarization degree of the polarizing element layer was measured using a spectrophotometer by absolute polarization, and the result showed a polarization degree of 99.8%.

[0120] In addition to using the light-reflecting layer and polarizing element layer described above, the optical film, optical stack, and polarized sunglasses of the present invention are obtained by the same operation as in Example 1.

[0121] [Example 4]

[0122] Except for coating in a manner that makes the thickness of the light-reflecting layer described in Example 3 2.4 μm, the same operation as in Example 3 was performed to obtain the optical film, the optical stack, and the polarized sunglasses.

[0123] [Example 5]

[0124] <Fabrication of the Light Reflecting Layer>

[0125] Using the prepared coating solutions (R4) and (L4), the light-reflecting layers were coated to a thickness of 1.0 μm after drying, otherwise the same procedure as in Example 1 was performed, thereby obtaining the light-reflecting layers used in this invention. The center reflection wavelengths of the cholesterol-type liquid crystal layer (R4) and the cholesterol-type liquid crystal layer (L4) are 485 nm and 475 nm, respectively.

[0126] <Fabrication of Polarization Element Layer>

[0127] Polyvinyl alcohol (manufactured by KURARAY Co., Ltd., trade name: KURARAYVinylon#750) was stained in an aqueous solution containing 0.18 g / L direct red (CHLORANTINE FAST RED, CI28160), 0.52 g / L direct blue (Solophenyl Blue 4GL, CI34200), and 10 g / L sodium sulfate at 35°C for 3 minutes, and then stretched 4 times in the solution. Next, the stained slide was immersed in an aqueous solution containing 2.5 g / L nickel acetate and 6.6 g / L boric acid at 35°C for 3 minutes. Then, the slide was dried at room temperature for 3 minutes while kept taut, and then heat-treated at 70°C for 3 minutes to obtain a polarizing element layer. The polarization degree of the polarizing element layer was measured using a spectrophotometer by absolute polarization, and the result was a polarization degree of 99.8%.

[0128] In addition to using the light-reflecting layer and polarizing element layer described above, the optical film, optical stack, and polarized sunglasses of the present invention are obtained by the same operation as in Example 1.

[0129] [Example 6]

[0130] <Fabrication of the Light Reflecting Layer>

[0131] Using the prepared coating solutions (R5) and (L5), the light-reflecting layers were coated to a thickness of 1.0 μm after drying, otherwise the same procedure as in Example 1 was performed, thereby obtaining the light-reflecting layers used in this invention. The center reflection wavelengths of the cholesterol-type liquid crystal layer (R5) and the cholesterol-type liquid crystal layer (L5) are 455 nm and 445 nm, respectively.

[0132] <Fabrication of Polarization Element Layer>

[0133] The polarization element layer described in Example 5 is used.

[0134] In addition to using the light-reflecting layer and polarizing element layer described above, the optical film, optical stack, and polarized sunglasses of the present invention are obtained by the same operation as in Example 1.

[0135] [Example 7]

[0136] <Fabrication of the Light Reflecting Layer>

[0137] Using the prepared coating solutions (R6) and (L6), the light-reflecting layers were coated to a thickness of 0.7 μm after drying, otherwise the same procedure as in Example 1 was performed, thereby obtaining the light-reflecting layers used in this invention. The center reflection wavelength of both the cholesterol-type liquid crystal layer (R6) and the cholesterol-type liquid crystal layer (L6) is 605 nm.

[0138] <Fabrication of Polarization Element Layer>

[0139] Polyvinyl alcohol (VF series, manufactured by KURARAY) was immersed in warm water at 40°C for 3 minutes to induce swelling. The swollen membrane was then immersed in an aqueous solution at 30°C containing 2.8 wt% boric acid, 0.044 wt% iodine, and 3.13 wt% potassium iodide for dyeing. The dyed membrane was stretched 5.0 times its original length and treated in an aqueous solution at 50°C containing 3.0 wt% boric acid for 5 minutes. While maintaining the stretched state of the boric acid-treated membrane, it was then treated with a 20-second touch-up dyeing process in an aqueous solution at 30°C containing 5.0 wt% potassium iodide. The treated membrane was immediately dried at 70°C for 9 minutes to obtain the polarizing element layer. The polarization degree of the polarizing element layer was measured using a spectrophotometer via absolute polarization, and the result was a polarization degree of 99.9%.

[0140] In addition to the light-reflecting layer and polarizing element layer obtained by such operation, optical films, optical stacks and polarized sunglasses are obtained by the same operation as in Example 1.

[0141] [Example 8]

[0142] In addition to using the light-reflecting layer described in Example 2, optical films, optical stacks, and polarized sunglasses are obtained through the same operation as in Example 7.

[0143] [Example 9]

[0144] In addition to using the light-reflecting layer described in Example 3, optical films, optical stacks, and polarized sunglasses are obtained through the same operation as in Example 7.

[0145] [Example 10]

[0146] In addition to using the light-reflecting layer described in Example 5, optical films, optical stacks, and polarized sunglasses are obtained through the same operation as in Example 7.

[0147] [Example 11]

[0148] In addition to using the light-reflecting layer described in Example 6, optical films, optical stacks, and polarized sunglasses are obtained through the same operation as in Example 7.

[0149] [Example 12]

[0150] <Fabrication of the Light Reflecting Layer>

[0151] Using the prepared coating solution (R6), a single light-reflecting layer was fabricated through the following steps. A PET film (without a base coat) manufactured by Toyobo was used as the plastic substrate. (1) The coating solution was applied to the PET film at room temperature using a wire rod to achieve a film thickness of 1.0 μm after drying. (2) The film was heated at 150°C for 5 minutes to remove the solvent and form a cholesterol-type liquid crystal phase. Then, a high-pressure mercury lamp (manufactured by Harison Toshiba Lighting) was used to irradiate the film at 120W output for 5–10 seconds to fix the cholesterol-type liquid crystal phase, resulting in a cholesterol-type liquid crystal layer (R6). (3) The PET film was peeled off to obtain a light-reflecting layer composed of the cholesterol-type liquid crystal layer (R6). The central reflection wavelength of the cholesterol-type liquid crystal layer (R6) was 605 nm.

[0152] In addition to the light-reflecting layer obtained by this operation, an optical film, an optical stack, and polarized sunglasses are obtained by the same operation as in Example 7.

[0153] [Comparative Example 1]

[0154] Except that the coating was performed in such a way that the thickness of the cholesterol-type liquid crystal layers (R) and (L) described in Example 1 was 2.0 μm respectively, the optical film, the optical stack and the polarized sunglasses were obtained by the same operation as in Example 7.

[0155] [Comparative Example 2]

[0156] Except that the coating was performed in such a way that the thickness of the cholesterol-type liquid crystal layers (R) and (L) described in Example 2 was 1.8 μm respectively, the optical film, the optical stack and the polarized sunglasses were obtained by the same operation as in Example 7.

[0157] [Comparative Example 3]

[0158] In addition to using the light-reflecting layer described in Example 4, optical films, optical stacks, and polarized sunglasses are obtained through the same operation as in Example 7.

[0159] [Comparative Example 4]

[0160] Except that the coating was performed in such a way that the thickness of the cholesterol-type liquid crystal layers (R) and (L) described in Example 5 was 1.8 μm respectively, the optical film, the optical stack and the polarized sunglasses were obtained by the same operation as in Example 7.

[0161] [Comparative Example 5]

[0162] Except that the coating was performed in such a way that the thickness of the cholesterol-type liquid crystal layers (R) and (L) described in Example 6 was 1.8 μm respectively, the optical film, the optical stack and the polarized sunglasses were obtained by the same operation as in Example 7.

[0163] [Evaluation of characteristics]

[0164] <Central reflection wavelength and minimum transmittance of the light-reflecting layer>

[0165] The transmittance of the obtained light-reflecting layer was measured using a Shimadzu UV-3600 spectrophotometer. A C light source was used. The median wavelength [nm] of the 75% transmittance of the short-wavelength and long-wavelength sides of the reflective region of the obtained light-reflecting layer was taken as the center reflection wavelength.

[0166] In addition, the minimum transmittance in the central reflection wavelength region, i.e. the minimum transmittance in the reflection region, is taken as the minimum transmittance [%).

[0167] <Transmittance product of polarizing element layer and light reflecting layer>

[0168] The transmittance of the obtained polarizing element layer was measured using a Shimadzu UV-3600 spectrophotometer. A C light source was used. T0 (%) was calculated as the product of the minimum transmittance of the light-reflecting layer at the center reflection wavelength of the light-reflecting layer and the transmittance of the polarizing element layer. The average value of the product of the transmittance of the light-reflecting layer and the transmittance of the polarizing element layer in the center reflection wavelength region of the light-reflecting layer was taken as (T1%), and the average value of the product of the transmittance of the light-reflecting layer and the transmittance of the polarizing element layer in the visible light region of 400-750 nm, excluding the center reflection wavelength region, was taken as (T2%).

[0169] Furthermore, the transmittance of the light-reflecting layer, polarizing element layer, and optical stack obtained in Example 6 was measured using a Shimadzu UV-3600 spectrophotometer (C light source). The results are shown below. Figure 2 .

[0170] <Polarization of optical films>

[0171] The polarization of the obtained optical film was measured using a Shimadzu UV-3600 spectrophotometer. A C light source was used. The measurement method was absolute polarization, using a polarizing plate with a polarization of 99.99%. The transmittance measured when the absorption axis of the polarizing plate with a polarization of 99.99% was parallel to the absorption axis of the polarized sunglasses was denoted as Tp[%], and the transmittance measured when the polarizing plate was set perpendicularly was denoted as Tc[%]. The polarization was calculated using the formula: polarization = {(Tp - Tc) / (Tp + Tc)} × 100.

[0172] <Average visible light transmittance and transmitted hue of optical films>

[0173] The transmittance of the obtained optical film was measured using a Shimadzu UV-3600 spectrophotometer. A C light source was used. Using the obtained transmittance values, the Y value of the tristimulus was calculated according to JIS Z8722:2009, and this Y value was taken as the average transmittance of visible light.

[0174] Using the transmittance of the optical film obtained above, the a* and b* values ​​in the L*a*b* color system were calculated according to JIS Z 8781-4:2013.

[0175] <Evaluation of the Compliance of Polarized Sunglasses with Signal Identifiability Standards>

[0176] The transmittance of the obtained polarized sunglasses was measured using a Shimadzu UV-3600 spectrophotometer. C and D65 light sources were used. Using the obtained transmittance, Tables 1-3 and 3 were calculated according to ISO 12312-1:2013, ANSI Z80.3:2010, and AS / NZS 1067:2003. Figure 1 The evaluation results of the aforementioned signal identification criteria are recorded as follows.

[0177] ○: Meets all requirements

[0178] ×: There are items that do not meet the requirements.

[0179] The properties of the light-reflecting layer, optical film, and polarized sunglasses described in Examples 1-12 and Comparative Examples 1-5 were evaluated, and the results are shown in Tables 6-8.

[0180] [Table 6]

[0181] project Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Center reflection wavelength [nm] 620 559 681 680 479 452 Minimum transmittance [%) 45 46 35 21 35 33 Polarization degree [%] 92.6 95.6 97.8 97.3 97.6 98.3 Average transmittance of visible light [%) 15.4 15.5 16.6 15.2 16.8 17.4 a* 4 0.1 2.1 －2.4 4.1 －8.4 b* －2.8 3.8 2.7 －2.7 0.2 8.2 T0[％] 17 12 10 7 11 11 T1[％] 17 14 23 20 18 14 T2[％] 25 24 17 16 22 23 T2-T1 8 10 －6 －4 5 9 Meets signal identification standards ○ ○ ○ ○ ○ ○

[0182] [Table 7]

[0183] project Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Central reflection wavelength [nm] 605 559 681 479 452 605 Minimum transmittance [%) 60 46 35 35 33 65 Polarization degree [%] 97.2 94.2 98.7 96.7 98.1 91.6 Average transmittance of visible light [%) 32.7 25.1 37.3 32.2 34.9 35.4 a* －8.5 7.7 －8.4 6.2 －6.1 －7.4 b* －2.2 －14.3 2.1 17.6 31.1 1.5 Meets signal identification standards ○ ○ ○ ○ ○ ○

[0184] [Table 8]

[0185] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Center reflection wavelength [nm] 630 559 681 481 458 Minimum transmittance [%) 20 13 20 10 9 Polarization degree [%] 96.1 88.9 98.2 94.2 95.6 Average transmittance of visible light [%) 28.9 16.3 37.7 28.0 32.8 a* －25.6 36.2 －13.6 15.7 －4.5 b* －8.7 －28.7 0.2 16.6 42.2 Meets signal identification standards × × × × ×

[0186] As shown in the results above, comparing Examples 1-12 with Comparative Examples 1-5, the polarized sunglasses of Examples 1-12 meet all three signal identification criteria, while Comparative Examples 1-5 do not. Specifically, it is known that in Examples 1-5, the transmitted hue, not limited to the reflective area of ​​the light-reflecting layer, is within the region of -5 ≤ a* ≤ 5 and -5 ≤ b* ≤ 5, thus meeting the signal identification criteria. Furthermore, it is known that in Examples 6-11, the transmitted hue of the optical film is within the transmitted hue region set in each reflective area of ​​the light-reflecting layer, thus meeting the signal identification criteria. On the other hand, it is known that in Comparative Examples 1-5, the minimum transmittance outside the regions where the transmitted hue of each reflective wavelength region is set and within the central reflective area of ​​the light-reflecting layer is low, thus failing to meet the signal identification criteria.

[0187] Industrial availability

[0188] By using the optical film or optical laminate of the present invention, it is possible to provide protective goggles such as polarized sunglasses, goggles, helmet visors, etc., that have a metallic tint and excellent polarization performance, which meet the signal identification standards of various countries.

Claims

1. An optical film, characterized in that: The stacked layers have a light-reflecting layer and a polarizing element layer, satisfying one or more of the following conditions (a) to (d): (a) The central reflection wavelength of the light-reflecting layer is above 600 nm and below 660 nm, and the transmission hue of the optical film is in the region of -15 ≤ a* ≤ 10 and -20 ≤ b* ≤ 20; (b) The central reflection wavelength of the light-reflecting layer is above 500 nm and below 600 nm, and the transmission hue of the optical film is in the region of -5 ≤ a* ≤ 20 and -20 ≤ b* ≤ 30; (c) The central reflection wavelength of the light-reflecting layer is above 660nm and below 750nm, and the transmission hue of the optical film is in the region of -10≤a*≤10 and -5≤b*≤35. (d) The central reflection wavelength of the light-reflecting layer is above 400 nm and below 500 nm, and the minimum transmittance of the light-reflecting layer above 400 nm and below 500 nm is above 15%. The transmission hue of the optical film is in the region of -15 ≤ a* ≤ 25 and -10 ≤ b* ≤ 40. The product T0% of the minimum transmittance of the light-reflecting layer and the transmittance of the polarization element layer in the central reflection wavelength region of the light-reflecting layer is 5% or more. The difference (T2-T1) between the average value T1% of the product of the transmittance of the light-reflecting layer and the transmittance of the polarization element layer in the visible light region of 400-750nm (excluding the central reflection wavelength region) and the average value T2% of the product of the transmittance of the light-reflecting layer and the transmittance of the polarization element layer is -10 to 20. The central reflection wavelength refers to the midpoint between the short-wavelength side and the long-wavelength side where the transmittance in the reflection region of the light-reflecting layer is 75%. The a and b values ​​in the transmitted hue of the optical film are calculated using transmittance according to JIS Z 8781-4:2013, using a C or D65 light source.

2. The optical film as described in claim 1, characterized in that: The light-reflecting layer comprises one or more cholesterol-type liquid crystal layers.

3. The optical film as described in claim 1 or 2, characterized in that: The light-reflecting layer includes a cholesterol-type liquid crystal layer R with a right-handed helical orientation and a cholesterol-type liquid crystal layer L with a left-handed helical orientation.

4. The optical film according to any one of claims 1 to 3, characterized in that: The polarizing element layer comprises a stretched polymer film containing dichroic pigments.

5. The optical film according to any one of claims 1 to 4, characterized in that: Meets the relevant specifications for the identifiability of traffic signals as specified in ISO 12312-1:2013, ANSI Z80.3:2010 and / or AS / NZS 1067:2003.

6. An optical laminate, characterized in that: An optical film according to any one of claims 1 to 5 is disposed between the first support and the second support.

7. The optical stack as described in claim 6, characterized in that: The first support and the second support are made of polycarbonate.

8. A type of protective goggles, characterized in that: It has an optical film as described in any one of claims 1 to 5, or an optical laminate as described in claim 6 or 7.

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