WO2023145683A1 - Optical film and eyeware - Google Patents

Abstract

The present invention pertains to an optical film (10) comprising: an optical laminate (1) including at least one light-reflecting layer RPRL (2, 3) in which is fixed a cholesteric liquid crystal phase having a rightward winding spiral structure having rightward circular polarization reflection capability, and at least one light-reflecting layer LPRL (2, 3) in which is fixed a cholesteric liquid crystal phase having a leftward winding spiral structure having leftward circular polarization reflection capability; and a polarization element layer (6), wherein the light reflecting layer RPRL (2, 3) and the light-reflecting layer LPRL (2, 3) are laminated to be adjacent to each other without an adhesive layer therebetween.

Description

optical film and eyewear

The present invention relates to optical films and eyewear.

Eyewear (sunglasses, goggles, visors, etc.) is used to reduce the glare caused by reflected light from water surfaces, road surfaces, snow surfaces, etc. For example, in sunglasses, the lens portion is colored with a pigment or the like, and the pigment absorbs the reflected light. As a result, the amount of light entering the eyes of the sunglasses wearer is reduced, and glare can be reduced. On the other hand, since the reflected light from the surface of water and the surface of snow generally has the property of being polarized, polarized sunglasses are particularly effective against such reflected light. Polarized sunglasses are designed to effectively absorb light in the direction of polarization, so they can reduce glare and improve visibility without significantly reducing the amount of light incident on the eyes.

The optical film used for polarized sunglasses usually has a structure in which a polarizing element is sandwiched between support materials such as polycarbonate. Polarized sunglasses can be produced by processing such an optical film into a desired shape and fitting it into a frame. A polarizing element is a film in which a so-called dichroic dye such as a dichroic dye or a polyiodine-polyvinyl alcohol (PVA) complex is uniaxially oriented together with a polymer such as PVA. element can be obtained. In the case of ordinary sunglasses, the polarizing element is often colored in a grayish color in order to impart polarizing properties to the entire visible light range.

In some cases, a multilayer film is vapor-deposited on the surface of polarized sunglasses to add design or further improve visibility. By applying a multilayer film, the reflected light on the surface of the sunglasses can be seen in metallic tones such as blue, green, and red by others who do not wear polarized sunglasses, and the wearer can see specific light. Reflection further improves the visibility of the scenery through the lens with reduced glare. Applying a multilayer film in this way is beneficial for the wearer, but there are handling problems such as sebum and the like being difficult to remove when attached to the multilayer film. The multilayer film may peel off.

A possible solution to this problem is to provide a multilayer film inside the supporting material, that is, between the polarizing element and the supporting material. However, since the multilayer film expresses reflection performance due to the difference in refractive index between the layers, it is difficult for the multilayer film to obtain the same reflection performance as that of the air interface. In addition, since the multilayer film is made of an inorganic material, there is a problem in adhesion to the polarizing element, which is an organic material.

On the other hand, a method of using a cholesteric liquid crystal layer is known as a method of imparting reflected light with a metallic color tone with an organic substance without using a multilayer film. Cholesteric liquid crystal is a state in which liquid crystal molecules are helically aligned, and has the function of selectively reflecting a circularly polarized component in the same direction as the helical direction of liquid crystal molecules in a specific wavelength region depending on the length of the helical pitch. An optical laminate using a cholesteric liquid crystal layer in which the helical orientation is fixed so that light is reflected in a desired wavelength range exhibits reflected light with a vivid color tone, and can impart decorativeness to various members.

Due to its properties, cholesteric liquid crystals can selectively reflect circularly polarized components in a specific wavelength range. There are right-handed and left-handed helical orientations. In the case of the right-handed helical orientation, only the right-handed circularly polarized light component is reflected, and in the case of the left-handed helical orientation, only the left-handed circularly polarized light component is reflected. Therefore, in the case of the right-handed helical orientation, when external light is incident, only the right-handed circularly polarized light component in the wavelength region corresponding to the helical pitch is reflected, and the left-handed circularly polarized light component in the corresponding wavelength region is transmitted.

In this way, using a cholesteric liquid crystal layer makes it possible to give reflected light with a metallic color tone without using a multilayer film. becomes polarized. A polarizing element manufactured using a dichroic dye functions with respect to linearly polarized light. Therefore, when the polarizing element is combined with a cholesteric liquid crystal layer, the polarizing element cannot sufficiently absorb transmitted light. As a result, there is concern about a new problem that the amount of light leaking from the polarizing element increases and the original function of the polarized sunglasses is deteriorated.

In order to solve this problem, in Patent Document 1, a light reflecting layer having a cholesteric liquid crystal layer having right-handed spiral alignment and a light reflecting layer having a cholesteric liquid crystal layer having left-handed spiral alignment are laminated via an adhesive layer. It is disclosed that an optical film with a polarizer layer reflects both the left-handed and right-handed circularly polarized light components at each light-reflecting layer. In Patent Document 1, a high degree of polarization is obtained by laminating a light reflecting layer and a light reflecting layer via an adhesive layer.

WO2016/002582

However, in order to improve the visibility of eyewear, it is required to increase the degree of polarization of the optical film. Also, in order to ensure the transparency of eyewear, it is desirable that the haze value of the optical film is lower.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical film having a higher degree of polarization and a lower haze value, and eyewear comprising the optical film.

The optical film according to the embodiment of the present invention includes at least one light reflecting layer RPRL in which a cholesteric liquid crystal phase having a right-handed helical structure having right-handed circularly polarized light reflectivity is fixed and a left-handed helical structure having left-handed circularly polarized light reflectivity. an optical laminate including at least one light reflecting layer LPRL in which a cholesteric liquid crystal phase is fixed; and a polarizing element layer,
The light reflecting layer RPRL and the light reflecting layer LPRL are laminated adjacent to each other without an adhesive layer interposed therebetween.

An eyewear according to an embodiment of the present invention includes the optical film.

The present invention can provide an optical film with a higher degree of polarization and a lower haze value, and eyewear comprising the optical film.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows one Embodiment of the optical film which concerns on this invention. It is a schematic diagram showing an example of an optical layered product. It is a schematic diagram showing another example of the optical layered body. 4 shows spectral data of the optical layered body produced in Example 1. FIG. 4 shows spectral data of the optical layered body produced in Example 2. FIG. 4 shows spectral data of the optical layered body produced in Example 3. FIG. 4 shows spectral data of the optical layered body produced in Example 4. FIG. 4 shows spectral data of an optical layered body produced in Example 5. FIG. 2 shows spectral data of an optical layered body produced in Example 6. FIG. 2 shows spectral data of an optical layered body produced in Example 7. FIG. 10 shows spectral data of an optical layered body produced in Example 8. FIG. 13 shows spectral data of an optical layered body produced in Example 9. FIG. 4 shows spectral data of the optical layered body produced in Comparative Example 1. FIG. 11 shows spectral data of an optical layered body produced in Example 10. FIG. 11 shows spectral data of an optical layered body produced in Example 11. FIG. 12 shows spectral data of an optical layered body produced in Example 12. FIG. 13 shows spectral data of an optical layered body produced in Example 13. FIG. 13 shows spectral data of an optical layered body produced in Example 14. FIG. 4 shows spectral data of an optical layered body produced in Comparative Example 2. FIG.

The optical film according to the present invention will be described below with reference to the drawings. It should be noted that the embodiments shown below merely exemplify representative embodiments used to specifically describe the present invention, and various embodiments can be made within the scope of the present invention.

PRL is an abbreviation for "Polarized light Reflection Layer" and means a light reflection layer. The light reflecting layer RPRL represents a light reflecting layer having a cholesteric liquid crystal layer with a right-handed spiral structure, and the light reflecting layer LPRL represents a light reflecting layer having a cholesteric liquid crystal layer with a left-handed spiral structure. Further, a numerical range represented using "to" means a range including the numerical values described before and after "to" as lower and upper limits.

[Optical film]
The optical film 10 according to the present invention comprises an optical layered body 1 and a polarizing element layer 6, and has an adhesive layer 5 between the optical layered body 1 and the polarizing element layer 6, as shown in FIG.

<Optical laminate>
The optical layered body 1 is a layered body including a light reflecting layer in which two or more cholesteric liquid crystal phases are fixed. The two or more light reflecting layers are laminated adjacently without an adhesive layer intervening, that is, directly laminated to each other. The optical laminate 1 includes at least one light reflecting layer RPRL in which a right-handed circularly polarized light reflectivity cholesteric liquid crystal phase is fixed, and a left-handed circularly polarized light reflectivity cholesteric liquid crystal phase with a left-handed spiral structure. at least one immobilized light-reflecting layer LPRL and optionally further light-reflecting layers. The additional light-reflecting layer may be either right-handed or left-handed in the helical structure, i.e., either the light-reflecting layer RPRL or the light-reflecting layer LPRL, or both. may contain

The number of light reflecting layers in the optical laminate 1 is, for example, 2 to 6 layers, preferably 2 or 3 layers. Various reflection colors can be realized by providing 2 to 6 light reflecting layers.

The order in which the light reflecting layers are stacked in the optical layered body 1 is particularly limited as long as a total of two or more light reflecting layers including at least one light reflecting layer RPRL and at least one light reflecting layer LPRL are stacked. not.

FIG. 2 shows an optical layered body 1A as an example of the optical layered body 1. FIG. The optical laminate 1A includes a first light reflecting layer 2 and a second light reflecting layer 3 in which a cholesteric liquid crystal phase is fixed. The first light reflecting layer 2 and the second light reflecting layer 3 are laminated adjacent to each other, and no adhesive layer exists between the first light reflecting layer 2 and the second light reflecting layer 3 .

The second light reflecting layer 3 is a cholesteric liquid crystal layer having a spiral rotation direction opposite to that of the cholesteric liquid crystal layer of the first light reflecting layer 2 . For example, when the first light reflecting layer 2 is a cholesteric liquid crystal layer with a right-handed spiral structure (light reflecting layer RPRL-2), the second light reflecting layer 3 is a cholesteric liquid crystal layer with a left-handed spiral structure (light reflecting layer RPRL-2). It is the reflective layer LPRL-3). That is, the optical layered body 1A shown in FIG. 2 has a layered structure of light reflecting layer RPRL-2/light reflecting layer LPRL-3. In addition, with respect to the laminated structure, when light reflecting layers whose spiral rotation directions are opposite to each other are used instead of the corresponding light reflecting layers, the optical laminated body 1A is composed of light reflecting layer LPRL-2/light reflecting layer RPRL- It may have a three-layer structure. The reference numerals following the light reflecting layer RPRL (LPRL) mean the reference numerals given as "first light reflecting layer 2" and "second light reflecting layer 3" in FIG. The same applies hereinafter.

FIG. 3 shows an optical layered body 1B as another example of the optical layered body 1. FIG. The optical laminate 1B further includes a third light reflecting layer 4 in addition to the first light reflecting layer 2 and the second light reflecting layer 3 . The second light reflecting layer 3 is a cholesteric liquid crystal layer having a spiral rotation direction opposite to that of the cholesteric liquid crystal layer used as the first light reflecting layer 2, and the third light reflecting layer 4 is a third light reflecting layer. A cholesteric liquid crystal layer having the same spiral rotation direction as that of the cholesteric liquid crystal layer used as one light reflecting layer 2 may be used. In this case, for example, when the first light reflecting layer 2 is a cholesteric liquid crystal layer with a right-handed spiral structure (light reflecting layer RPRL-2), the second light reflecting layer 3 is a cholesteric liquid crystal layer with a left-handed spiral structure. The third light reflecting layer 4 is a right-handed spiral structure cholesteric liquid crystal layer (light reflecting layer RPRL-4). In addition, with respect to this laminated structure (light reflecting layer RPRL-2/light reflecting layer LPRL-3/light reflecting layer RPRL-4), instead of corresponding light reflecting layers, light reflecting layers whose spiral rotation directions are opposite to each other To obtain an optical laminate 1B exhibiting the same effect as light reflection characteristics even in a laminated structure (light reflecting layer LPRL-2/light reflecting layer RPRL-3/light reflecting layer LPRL-4) using can be done.

From the viewpoint of application to eyewear that imparts designability, each light reflecting layer constituting the optical laminate preferably has a central reflection wavelength in the range of 380 nm or more and 900 nm or less. The lower limit of the central reflection wavelength is preferably 400 nm or longer, more preferably 420 nm or longer, and even more preferably 450 nm or longer. Also, the upper limit of the central reflection wavelength is preferably 850 nm or less, more preferably 780 nm or less, and even more preferably 750 nm or less.

The difference in central reflection wavelength between the light reflecting layer RPRL and the light reflecting layer LPRL is preferably 0 nm or more and 500 nm or less from the viewpoint of application to eyewear that imparts designability. In general, the degree of polarization increases as the difference between the central reflection wavelengths of the light reflecting layer RPRL and the light reflecting layer LPRL decreases. Therefore, the difference in central reflection wavelength between the light reflecting layer RPRL and the light reflecting layer LPRL is preferably 0 nm or more and 200 nm or less, more preferably 0 nm or more and 100 nm or less, still more preferably 0 nm or more and 60 nm or less, particularly It is preferably 0 nm or more and 40 nm or less, and most preferably 0 nm or more and 20 nm or less. When the optical laminate includes three or more light reflecting layers, the difference in central reflection wavelength between the third light reflecting layer and each of the first and second light reflecting layers affects the design. It is preferably 0 nm or more and 500 nm or less from the viewpoint of application to eyewear to be imparted, more preferably 0 nm or more and 200 nm or less from the viewpoint of obtaining a high degree of polarization, and even more preferably 0 nm or more and 100 nm or less. , more preferably 0 nm or more and 60 nm or less, particularly preferably 0 nm or more and 40 nm or less, and most preferably 0 nm or more and 20 nm or less.

From the viewpoint of applying the optical film to eyewear that requires a high degree of polarization, the maximum reflectance of the optical laminate for incident light is preferably 90% or less, more preferably 80% or less, and 70% or less. is more preferable. A high degree of polarization can be obtained when the maximum reflectance is 90% or less. In addition, "incident light" is light that enters the optical layered body perpendicularly. Further, the "maximum reflectance" means the maximum reflectance that the optical layered body has in the wavelength region of 380 nm or more and 900 nm or less, and the "minimum reflectance" means the optical layered body in the wavelength region of 380 nm or more and 900 nm or less. means minimum reflectance.

In addition, the "central reflection wavelength" means the average wavelength of the wavelength on the short wavelength side and the wavelength on the long wavelength side corresponding to 80% of the maximum reflectance of each light reflecting layer. For example, if the maximum reflectance of the light reflecting layer is 60%, the wavelength on the short wavelength side showing a reflectance of 48% corresponding to 80% is λ1, and the wavelength on the long wavelength side is λ3. λ2 indicated by (1) is the central reflection wavelength.

(λ1+λ3)/2=λ2 (1)

The thickness of each light reflecting layer is preferably 0.20 μm or more and 5.0 μm or less, more preferably 0.30 μm or more and 4.0 μm or less, and preferably 0.40 μm or more and 3.0 μm or less. More preferably, it is particularly preferably 0.50 μm or more and 2.0 μm. When the thickness of each light reflecting layer is less than 0.20 μm, the reflectance of the resulting optical laminate may be extremely low. It may not be oriented and the haze value may increase. The thickness of the optical layered body is preferably 0.40 μm or more and 100.0 μm or less, more preferably 1.0 μm or more and 30.0 μm or less, and 1.5 μm or more and 10.0 μm or less. is more preferred.

The haze value of the optical laminate is preferably less than 1.0%, more preferably 0.5% or less, even more preferably 0.4% or less, and 0.3% or less. is particularly preferred. When the haze value is 1.0% or more, the opacity of the optical layered body is large and it is not suitable for use in eyewear where transparency is important.

Each light reflecting layer can be formed by various methods. As an example, there is a method of forming by applying a liquid crystal coating liquid, which will be described later. More specifically, a curable liquid crystal composition capable of forming a cholesteric liquid crystal layer is applied to the surface of a substrate, an alignment layer, etc., and the composition is converted to a cholesteric liquid crystal phase, followed by a curing reaction (e.g., polymerization reaction , cross-linking reaction, etc.), the cholesteric liquid crystal phase is fixed, and a predetermined light reflecting layer can be formed.

Each light reflecting layer formed by fixing the cholesteric liquid crystal phase tends to deteriorate due to irradiation with ultraviolet light, and deterioration due to ultraviolet light with a wavelength of 380 nm or less is particularly remarkable. Therefore, for example, by adding a material that absorbs light in the ultraviolet region (ultraviolet absorber) to at least one light reflecting layer, or by separately laminating a layer containing an ultraviolet absorber, such as a light absorbing layer, on the optical laminate. By doing so, deterioration of the light reflecting layer can be significantly suppressed.

Various methods can be used for laminating two or more light reflecting layers adjacently without an adhesive layer. The most preferable method is to form a new light reflecting layer by directly coating the liquid crystal coating liquid on the light reflecting layer to form a film, and laminate two or more light reflecting layers without an adhesive layer. .

(Liquid crystal coating solution for forming light reflecting layer)
The liquid crystal coating liquid for forming the light reflecting layer RPRL and the light reflecting layer LPRL is preferably a curable liquid crystal composition. The liquid crystal composition contains, for example, at least each component of a rod-like liquid crystal compound, an optically active compound (chiral compound), and a polymerization initiator, and may contain two or more of each component. For example, a polymerizable liquid crystal compound and a non-polymerizable liquid crystal compound can be used together. A combination of a low-molecular-weight liquid crystal compound and a high-molecular-weight liquid crystal compound is also possible. Furthermore, in order to improve the uniformity of alignment of various liquid crystal compounds, the applicability of the liquid crystal composition, and the strength of the resulting coating film, the liquid crystal composition contains a horizontal alignment agent, an anti-mura agent, an anti-cratering agent, and a polymerizable It may contain at least one selected from various additives such as monomers. In addition, polymerization inhibitors, antioxidants, ultraviolet absorbers, light stabilizers, colorants, metal oxide fine particles, etc., may be added to the liquid crystal composition as necessary within a range that does not degrade the optical performance. can do.

(1) Rod-Like Liquid Crystal Compounds Examples of rod-like liquid crystal compounds include rod-like nematic liquid crystal compounds. Examples of rod-shaped nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, phenyldioxane, Tolanes and alkenylcyclohexylbenzonitriles are preferred. Moreover, as the rod-like liquid crystal compound, not only a low-molecular-weight liquid crystal compound but also a high-molecular-weight liquid crystal compound can be used.

The rod-like liquid crystal compound may be polymerizable or non-polymerizable. Rod-shaped liquid crystal compounds having no polymerizable group are described in various documents (eg, Y. Goto et al., Mol. Cryst. Liq. Cryst. 1995, Vol. 260, pp. 23-28). there is A polymerizable rod-like liquid crystal compound is obtained by introducing a polymerizable group into a rod-like liquid crystal compound. Examples of the polymerizable group include unsaturated polymerizable groups, epoxy groups, and aziridinyl groups, with unsaturated polymerizable groups being preferred, and ethylenically unsaturated polymerizable groups being particularly preferred. The polymerizable group can be introduced into the molecule of the rod-like liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable rod-like liquid crystal compound is preferably 1 to 6, more preferably 1 to 3. Polymerizable rod-like liquid crystal compounds include, for example, Makromol. Chem. , 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. 95/22586, WO 95/24455, WO 97/00600, WO 98/23580, WO 98/52905, JP-A-1-272551, JP-A-6-16616 JP-A-7-110469, JP-A-11-80081, and JP-A-2001-328973. Two or more polymerizable rod-like liquid crystal compounds may be used in combination as the rod-like liquid crystal compound. When two or more types of polymerizable rod-like liquid crystal compounds are used together, the alignment temperature can be lowered.

(2) Optically active compound (chiral agent)
The liquid crystal composition exhibits a cholesteric liquid crystal phase, and therefore preferably contains an optically active compound. However, when the rod-like liquid crystal compound is a molecule having an asymmetric carbon atom, it may be possible to stably form a cholesteric liquid crystal phase without adding an optically active compound. Optically active compounds include various known chiral agents (for example, Liquid Crystal Device Handbook, Chapter 3, Section 4-3, Chiral Agents for TN and STN, p. 199, Japan Society for the Promotion of Science, 142nd Committee, 1989). You can choose from Optically active compounds generally contain an asymmetric carbon atom, but axially chiral compounds or planar chiral compounds that do not contain an asymmetric carbon atom can also be used as chiral agents. Examples of axially or planarly chiral compounds include binaphthyl, helicene, paracyclophane and derivatives thereof. The optically active compound (chiral agent) may have a polymerizable group. When the optically active compound has a polymerizable group and the rod-like liquid crystal compound used in combination also has a polymerizable group, a repeating unit derived from the rod-like liquid crystal compound through the polymerization reaction of the polymerizable optically active compound and the polymerizable rod-like liquid crystal compound. and a repeating unit derived from an optically active compound. In this aspect, the polymerizable group possessed by the polymerizable optically active compound is preferably the same kind of polymerizable group possessed by the polymerizable rod-like liquid crystal compound. Therefore, the polymerizable group of the optically active compound is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. is particularly preferred. Also, the optically active compound may be a liquid crystal compound.

The content of the optically active compound contained in the liquid crystal composition is preferably 0.1 parts by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass with respect to 100 parts by mass of the liquid crystal compound used in combination. It is below. The smaller the amount of the optically active compound used, the less the liquid crystallinity is often affected, which is preferable. Therefore, the optically active compound used as the chiral agent is preferably a compound exhibiting a strong twisting force so that even a small amount can achieve the desired twisted orientation of the helical pitch. As a chiral agent exhibiting such a strong twisting force, for example, the chiral agent described in JP-A-2003-287623 can be mentioned, and preferably, the chiral agent can be used.

(3) Polymerization Initiator The liquid crystal composition used for forming each light reflecting layer is preferably a polymerizable liquid crystal composition, and accordingly preferably contains a polymerization initiator. Since the curing reaction of the applied liquid crystal composition proceeds by irradiation with ultraviolet rays, the polymerization initiator used is preferably a photopolymerization initiator capable of initiating the polymerization reaction upon irradiation with ultraviolet rays. The photopolymerization initiator is not particularly limited, for example, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one ("Omnirad 907" manufactured by IGM Resins BV), 1-hydroxy Cyclohexyl phenyl ketone ("Omnirad 184" manufactured by IGM Resins BV), 4-(2-hydroxyethoxy)-phenyl (2-hydroxy-2-propyl) ketone ("Omnirad 2959" manufactured by IGM Resins BV), 1-( 4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one (“Darocur 953” manufactured by Merck), 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one ( Merck "Darocur 1116"), 2-hydroxy-2-methyl-1-phenylpropan-1-one (IGM Resins BV "Omnirad 1173"), acetophenone compounds such as diethoxyacetophenone; benzoin, benzoin methyl ether , benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin compounds such as 2,2-dimethoxy-2-phenylacetophenone ("Omnirad 651" manufactured by IGM Resins BV); benzoylbenzoic acid, methyl benzoylbenzoate, 4- Benzophenone compounds such as phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3'-dimethyl-4-methoxybenzophenone ("KAYACURE MBP" manufactured by Nippon Kayaku Co., Ltd.); and thioxanthone, 2- Chlorothioxanthone (“KAYACURE CTX” manufactured by Nippon Kayaku Co., Ltd.), 2-methylthioxanthone, 2,4-dimethylthioxanthone (“KAYACURE RTX” manufactured by Nippon Kayaku Co., Ltd.), isopropylthioxanthone, 2,4-dichlorothioxanthone (Nippon Kayaku "KAYACURE CTX" manufactured by Nippon Kayaku Co., Ltd.), 2,4-diethylthioxanthone ("KAYACURE DETX" manufactured by Nippon Kayaku Co., Ltd.), and thioxanthone compounds such as 2,4-diisopropylthioxanthone ("KAYACURE DITX" manufactured by Nippon Kayaku Co., Ltd.). be done. These photopolymerization initiators may be used alone, or two or more of them may be used in combination.

The content of the photopolymerization initiator in the polymerizable liquid crystal composition is not particularly limited. It is 8 parts by mass or more and 8 parts by mass or less.

When using a benzophenone compound or a thioxanthone compound as a photopolymerization initiator, it is preferable to use a reaction aid in combination to promote the photopolymerization reaction. The reaction aid is not particularly limited, and examples thereof include triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4'-diethylaminophenone, 4-dimethyl. Examples include amine compounds such as ethyl aminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate.

The content of the reaction aid in the polymerizable liquid crystal composition is not particularly limited, but it is preferably used within a range that does not affect the liquid crystallinity of the polymerizable liquid crystal composition. It is preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the total amount of the active compound. Also, the content of the reaction aid is preferably 0.5 times or more and 2 times or less the content of the photopolymerization initiator.

(4) Solvent The liquid crystal composition further contains a solvent. Such a solvent is not particularly limited as long as it can dissolve the liquid crystal compound, chiral agent, and the like to be used. Cyclopentanone is preferred because it has a good Moreover, these solvents can be added in an arbitrary ratio, and only one type may be added, or a plurality of solvents may be used in combination. These solvents are removed by drying in a drying zone such as an oven or film coater line.

(5) Additives Leveling agents, antifoaming agents, ultraviolet absorbers, light stabilizers, antioxidants, polymerization inhibitors, cross-linking agents, plasticizers, inorganic fine particles, fillers, etc. may be added to the liquid crystal composition as necessary. It is also possible to further add the additive of (1) in an arbitrary ratio to impart the function of each additive to the liquid crystal composition. Examples of leveling agents include fluorine-based compounds, silicone-based compounds, and acrylic compounds. Examples of ultraviolet absorbers include benzotriazole compounds, benzophenone compounds, and triazine compounds. Examples of light stabilizers include hindered amine compounds and benzoate compounds, and examples of antioxidants include phenol compounds. Polymerization inhibitors include methoquinone, methylhydroquinone, hydroquinone, and the like, and crosslinking agents include polyisocyanates, melamine compounds, and the like. Plasticizers include phthalates such as dimethyl phthalate and diethyl phthalate, trimellitates such as tris(2-ethylhexyl) trimellitate, aliphatic dibasic acid esters such as dimethyl adipate and dibutyl adipate, tributyl phosphate and triphenyl Examples include orthophosphates such as phosphates, and acetates such as glyceryl triacetate and 2-ethylhexyl acetate.

An optical laminate can provide an optical film exhibiting a higher degree of polarization by being combined with a polarizing element layer. The degree of polarization of the optical film varies depending on the difference in central reflection wavelength between the light reflecting layer RPRL and the light reflecting layer LPRL, the maximum reflectance of the light reflecting layer RPRL and the light reflecting layer LPRL, and the central reflection wavelength of the optical laminate. In general, the higher the maximum reflectance of the light reflecting layer, the lower the degree of polarization. Further, the degree of polarization tends to decrease as the difference between the central reflection wavelengths of the light reflecting layer RPRL and the light reflecting layer LPRL increases. In addition, when the central reflection wavelength of the optical layered body is in the range of 570 nm or more and 620 nm or less, the degree of polarization tends to be lower than when it is in other wavelength ranges. In the wavelength region of 780 nm or less, the degree of polarization tends to be higher than in other wavelength regions. It is known that the degree of polarization of the optical layered body changes depending on the optical properties of the light reflecting layer. According to the optical film of the present invention, the respective light reflecting layers contained in the optical layered body are laminated adjacently without an adhesive layer, thereby improving the degree of polarization and increasing the optical property value of the light reflecting layer. A decrease in the degree of polarization due to the change can be reduced. Therefore, the optical film can have a higher degree of polarization than the conventional optical film disclosed in Patent Document 1 or the like when comparing films having similar tints.

In the optical film according to the present invention, when the optical layered body has a central reflection wavelength of 570 nm or more and 620 nm or less, the degree of polarization of the optical layered body is preferably 91% or more, more preferably 93% or more. . Further, when the optical layered body has a central reflection wavelength of 380 nm or more and less than 570 nm, or more than 620 nm and 780 nm or less, particularly when it has a central reflection wavelength of 380 nm or more and 480 nm or less, the degree of polarization of the optical layered body should exceed 98%. is preferred, and 98.5% or more is preferred.

<Polarizing element layer>
The polarizing element layer is not particularly limited, but typically includes a polyvinyl alcohol (PVA) polarizing film. The method for producing the polarizing element layer, which is a polyvinyl alcohol-based resin layer in which a dichroic dye is adsorbed and oriented, is not particularly limited. A polarizing element layer is produced by adsorbing a pigment such as a dye and then uniaxially stretching and orienting the film. As the dye, a dichroic dye is preferable from the viewpoint of heat resistance, and a direct dye of an azo dye having a sulfonic acid group is particularly preferable.

<Adhesive layer>
The adhesive layer is a layer for bonding the optical layered body and the polarizing element layer together. By laminating the optical layered body and the polarizing element layer via the adhesive layer, they can be bonded together with high adhesive strength. When the optical layered body is directly coated on the polarizing element to form a film, the adhesive layer does not necessarily exist between the optical layered body and the polarizing element layer.

Both hot-melt adhesives and curable adhesives can be used as the adhesive layer. Generally, curable adhesives include acrylic resin-based materials, urethane resin-based materials, polyester resin-based materials, melamine resin-based materials, epoxy resin-based materials, silicone-based materials, and the like. Among these, a two-liquid thermosetting urethane resin containing a polyurethane prepolymer, which is a urethane resin material, and a curing agent is preferable because of its excellent adhesive strength and workability during bending. Moreover, considering the application of the optical film to the optical member, the adhesive layer-forming material for forming the adhesive layer is preferably transparent. Examples of transparent resins that can be used for the adhesive layer forming material include acrylic resins and epoxy resins. In the adhesive for adhering the optical laminate and the polarizing element layer, a photochromic dye may be further dissolved to impart a color to the adhesive layer, thereby appropriately adjusting the transmitted light obtained from the polarizing element layer side. good.

(acrylic resin)
Acrylic resins are resins that contain acrylic monomers or oligomers as main components and are obtained by curing by anionic polymerization, radical polymerization, or redox polymerization. Examples of such acrylic resins include anionic polymerization type instant adhesives mainly composed of 2-cyanoacrylate esters, redox polymerization type acrylic adhesives mainly composed of methacrylic acid esters, and polyfunctional acrylic resins. Radical polymerization type ultraviolet curable adhesives based on ultraviolet irradiation containing an acid ester or a polyfunctional methacrylic acid ester as a main component may be mentioned. A UV curable adhesive contains a (meth)acrylate monomer, a photopolymerization initiator and an additive.

Examples of acrylic resin materials used include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta acrylates, dipentaerythritol hexaacrylate, reaction products of pentaerythritol tri(meth)acrylate and 1,6-hexamethylene diisocyanate, reaction products of pentaerythritol tri(meth)acrylate and isophorone diisocyanate, tris(acryloxyethyl ) isocyanurate, tris(methacryloxyethyl)isocyanurate, reaction products of glycerol triglycidyl ether and (meth)acrylic acid, caprolactone-modified tris(acryloxyethyl)isocyanurate, trimethylolpropane triglycidyl ether and (meth) ) reaction products with acrylic acid, triglycerol di(meth)acrylate, reaction products of 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 1,6-hexanediol di(meth)acrylate, glycerol di(meth)acrylate, reaction product of ethylene glycol diglycidyl ether and (meth)acrylic acid, diethylene glycol diglycidyl ether and (meth) Reaction products with acrylic acid, bis (acryloxyethyl) hydroxyethyl isocyanurate, bis (methacryloxyethyl) hydroxyethyl isocyanurate, reaction products of bisphenol A diglycidyl ether and (meth) acrylic acid, tetrahydrofuran Furyl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, phenoxyhydroxy Propyl (meth)acrylate, acryloylmorpholine, methoxypolyethylene glycol (meth)acrylate, methoxytetraethyleneglycol (meth)acrylate, methoxytriethyleneglycol (meth)acrylate, methoxyethyleneglycol (meth)acrylate, methoxyethyl (meth)acrylate, glycidyl (meth)acrylate, glycerol (meth)acrylate, ethyl carbitol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, butyl Examples include reaction products of glycidyl ether and (meth)acrylic acid, butoxytriethylene glycol (meth)acrylate, butanediol mono(meth)acrylate, and the like. These compounds may be used alone or in combination.

(epoxy resin)
The epoxy-based resin contains an epoxy resin and, as optional components, a curing agent such as an amine-based compound, an acid anhydride, and a metal catalyst. The epoxy resin is not particularly limited as long as it has two or more epoxy groups in one molecule. Examples include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, and phenol novolac epoxy resin , alicyclic epoxy resins, heterocyclic epoxy resins, glycidyl ester-based epoxy resins, glycidylamine-based epoxy resins, brominated epoxy resins, hydrogenated bisphenol A type epoxy resins, propylene glycol glycidyl ether and pentaerythritol polyglycidyl ether. Examples include aliphatic epoxy resins and urethane-modified epoxy resins. These epoxy resins may be used singly or in combination of two or more. In addition, if necessary, monoepoxy compounds such as butyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, and fatty alcohol glycidyl ether may be added to reduce the viscosity.

(adhesive)
A pressure-sensitive adhesive can also be used as the adhesive layer-forming material. Rubber-based, acrylic-based, and silicone-based adhesives can be used as the adhesive, but acrylic-based adhesives are particularly preferred. Examples of acrylic adhesives include adhesives using (meth)acrylic polymers obtained by copolymerizing (meth)acrylic acid alkyl esters and other (meth)acrylic monomer components.

The (meth)acrylic acid alkyl esters include, for example, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, and lauryl (meth)acrylate. .

Other (meth)acrylic monomer components include, for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, carboxyl group-containing monomers such as fumaric acid; 2-hydroxyethyl (meth)acrylate, 2-hydroxy Hydroxyl group-containing monomers such as propyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, polyoxypropylene (meth) acrylate, caprolactone-modified (meth) acrylate; N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, ( nitrogen-containing monomers such as meth)acrylamide, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate and dimethylaminopropyl (meth)acrylate; and epoxy group-containing monomers such as glycidyl (meth)acrylate.

A solvent may be added to the adhesive coating liquid to adjust the viscosity and improve the coating properties. Solvents include acetic esters such as ethyl acetate, butyl acetate and methyl acetate; alcohols such as methanol, ethanol, propanol, isopropanol and benzyl alcohol; methyl ethyl ketone, acetone, cyclopentanone and cyclohexanone. ketones; basic solvents such as benzylamine, triethylamine and pyridine; and non-polar solvents such as cyclohexane, benzene, toluene, xylene, anisole, hexane and heptane. These solvents can be added in any ratio, and only one type may be used, or multiple components may be blended. These solvents are removed by drying in ovens and drying zones of film coater lines.

<Orientation layer>
The optical film may have an alignment layer between the light reflecting layer in which the cholesteric liquid crystal phase is fixed and the polarizing element layer laminated in the optical laminate. The alignment layer has the function of more precisely defining the alignment direction of the liquid crystal compound in the cholesteric liquid crystal phase. The alignment layer can be provided by rubbing treatment of an organic compound (preferably polymer), oblique vapor deposition of an inorganic compound, formation of a layer having microgrooves, or the like. Alignment layers are also known in which an alignment function is produced by application of an electric field, application of a magnetic field, or light irradiation. The orientation layer is preferably formed on the surface of the polymer film by rubbing.

The alignment layer preferably has a certain degree of adhesion to both the light reflecting layer and the polarizing element layer, which are adjacent to each other. For example, when inserting an alignment layer in an optical film having two light-reflecting layers in which cholesteric liquid crystal layers are fixed, first, one laminate having a light-reflecting layer and an alignment layer (light-reflecting layer [1]/ An alignment layer [1]) is prepared, and a light reflecting layer [2] is formed on the light reflecting layer [1] of the laminate [1]. Next, the polarizing element layer is laminated onto the light reflecting layer [2] using an adhesive to form an orientation layer [1]/light reflecting layer [1]/light reflecting layer [2]/adhesive/polarizing element layer. A laminate [A] having a layer structure is produced. Then, the optical film can be obtained by peeling off one of the orientation layers [1]. Therefore, it is preferable that the alignment layer is interposed at the interface between the light reflecting layer in which the cholesteric liquid crystal phase is fixed and the alignment layer with a peeling force so weak that it can be peeled off. The interface where the alignment layer is peeled off is not particularly limited.

As the material used for the alignment layer, an organic compound polymer is preferable, and typically a polymer that can be crosslinked itself or a polymer that is crosslinked by a crosslinking agent is used. Alternatively, a polymer having both functions may be used. Examples of polymers include polymethyl methacrylate, acrylic acid/methacrylic acid copolymers, styrene/maleimide copolymers, polyvinyl alcohol and modified polyvinyl alcohols, poly(N-methylolacrylamide), styrene/vinyl toluene copolymers, Polymers such as chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, carboxymethylcellulose, gelatin, polyethylene, polypropylene, polycarbonate, etc. and compounds such as silane coupling agents. Examples of preferred polymers are water-soluble polymers such as poly(N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol, and gelatin, polyvinyl alcohol and modified polyvinyl alcohol. The thickness of the alignment layer is preferably 0.10 μm or more and 2.0 μm or less. When an alignment layer is provided between the light reflecting layer of the cholesteric liquid crystal phase and the polarizing element layer, it is preferable to use an alignment layer with low birefringence from the viewpoint of the degree of polarization. ), polyolefin, acrylic and the like are preferred.

<Eyewear>
By molding the optical film according to the present invention into a desired shape suitable for the eyewear and fixing it to a frame or the like, eyewear provided with the optical film according to the present invention can be obtained. Examples of such eyewear include sunglasses, goggles, helmet visors, and the like. The method of manufacturing eyewear is not particularly limited, but for example, an optical film is punched into a desired shape and then subjected to bending. The bending method is not particularly limited, and the optical film may be bent into a spherical or aspherical surface shape depending on the desired shape.

As a specific example of bending, the optical film is preformed using a heat press machine or the like in order to make it easier to combine the optical film with the lens base material and process it into a lens shape. For the shaping process, generally, a mold designed to have a predetermined size is used, and is appropriately designed according to the design of the eyewear product. The optical film can be curved by placing the optical film in a bending mold (concave mold) and pressing it with a hemispherical mold (convex mold or hot iron ball) heated to a predetermined temperature. can.

In the bending process, an integral process may be performed in which a resin as a lens base material is injected, and the optical film and the resin are integrated and processed into a lens shape. An insert molding method is generally used for such integral processing. As a result, it is possible to prevent image distortion due to uneven thickness of the optical film, and even in a lens that does not have focal power, it has particularly excellent impact resistance, appearance, and eye fatigue. be able to. The resin to be injected as the lens base material is not particularly limited. can be used. Such a resin is preferably the same material as the layer with which the resin is in contact, in order to prevent appearance deterioration due to the difference in refractive index between the optical film and the lens substrate. Moreover, a hard coat, an antireflection film, or the like may be appropriately applied to the outer surface of the optical film. A desired eyewear can be manufactured by fixing an optical film that has undergone bending processing or injection molding to a frame or the like by edging, drilling, screwing, or the like. Also, the optical film according to the present invention can be attached to a desired lens substrate or the like using a pressure-sensitive adhesive or an adhesive to produce eyewear.

Based on the above embodiments, the present invention relates to the following [1] to [8].
[1]
At least one light reflecting layer RPRL in which a cholesteric liquid crystal phase with a right-handed spiral structure having right-handed circularly polarized light reflectivity is fixed and at least one light reflection layer RPRL in which a cholesteric liquid crystal phase with a left-handed circularly polarized light reflectivity is fixed An optical laminate including a light reflecting layer LPRL and a polarizing element layer,
An optical film, wherein the light reflecting layer RPRL and the light reflecting layer LPRL are laminated adjacent to each other without an adhesive layer interposed therebetween.
[2]
The optical film of [1] above, wherein the optical laminate has a center reflection wavelength of 570 nm or more and 620 nm or less and a degree of polarization of 91% or more.
[3]
The optical film according to [2] above, wherein the degree of polarization is 93% or more.
[4]
The optical film according to [1] above, wherein the optical laminate has a central reflection wavelength of 380 nm or more and less than 570 nm, or more than 620 nm and less than or equal to 780 nm, and a degree of polarization of more than 98%.
[5]
The optical film according to [4] above, wherein the optical laminate has a central reflection wavelength of 380 nm or more and 480 nm or less.
[6]
The optical film according to the above [4] or [5], wherein the degree of polarization is 98.5% or more.
[7]
The optical film according to any one of [1] to [6] above, wherein the optical layered body has a haze value (Hz) of less than 0.5%.
[8]
Eyewear comprising the optical film according to any one of [1] to [7] above.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as it does not exceed the spirit of the present invention. Further, room temperature is assumed to be within the range of 20°C ± 5°C unless otherwise specified.

<Preparation of coating liquid (liquid crystal composition)>
Coating liquids R1 to R14 having compositions shown in Table 1 and coating liquids L1 to L14 having compositions shown in Table 2 were prepared.

キラル剤：化合物１（特開２００２－１７９６６８号公報に記載の化合物）

Chiral agent: compound 1 (compound described in JP-A-2002-179668)

<Preparation of adhesive>
An adhesive having the composition shown in Table 3 was prepared.

[Examples 1 to 14]
<Preparation of optical laminate>
Using the prepared 28 types of coating liquids R1 to R14 and L1 to L14, coating films (light reflecting layers) of cholesteric liquid crystals were prepared by the following procedure, respectively, and the central reflection wavelength was measured. As a substrate for each light reflecting layer, a rubbed PET film without an undercoat layer (manufactured by Toyobo Co., Ltd., trade name "A4100", thickness 50 μm) was used.
(1) Each of the coating liquids R1 to R14 was applied to a PET film at room temperature using a wire bar so as to have a predetermined thickness.
(2) Each coating solution was heated at 80° C. for 3 minutes to remove the solvent and form a cholesteric liquid crystal phase. Then, a high-pressure mercury lamp (“HX4000L” manufactured by Harrison Toshiba Lighting Co., Ltd.) was irradiated with UV at 120 W output for 5 to 10 seconds to form a cholesteric liquid crystal layer (light reflecting layer RPRL) in which a cholesteric liquid crystal phase with a right-handed spiral structure was fixed. made.
(3) Coating liquids L1 to L14 are used on each light reflecting layer RPRL prepared from the coating liquids R1 to R14, and a cholesteric liquid crystal phase with a left-handed spiral structure is formed in the same manner as in (1) to (2). A fixed cholesteric liquid crystal layer (light reflecting layer LPRL) was formed, and optical laminates of Examples 1 to 14 were produced.
(4) The reflection spectra of the optical laminates of Examples 1 to 14 were measured using a spectrophotometer ("MPC-3100" manufactured by Shimadzu Corporation) to determine the central reflection wavelength and maximum reflectance. In addition, the haze value of the optical laminate was measured using a haze meter manufactured by Nippon Denshoku Co., Ltd. The thickness of the optical laminate was measured using a photoelectric digital length measuring system ("Digimicro MH-15M" manufactured by Nikon Corporation). Table 4 shows the thickness, central reflection wavelength and maximum reflectance, haze values, and L ^* , a ^* , b ^* values for C light sources of the optical laminates of Examples 1-14. 4 to 12 and 14 to 18 show the measurement results of reflection spectra.

<Production of optical film>
The adhesive (S1) was applied to the light reflecting layer LPRL side of each of the optical laminates of Examples 1 to 14 using a wire bar so that the thickness of the film after drying was 10 μm. After removing the solvent by heating at 40 ° C. for 1 minute, the polarizing element layer ("SKN-18243" manufactured by Nippon Kayaku Co., Ltd.) was attached to the surface coated with the adhesive, and then the PET film on the opposite surface. was peeled off to prepare optical films of Examples 1 to 14.

[Comparative Example 1]
(1) Coating liquid R1 is applied to a PET film (manufactured by Toyobo Co., Ltd., trade name “A4100”, thickness 50 μm) at room temperature so as to have a predetermined thickness using a wire bar. was heated at 80° C. for 3 minutes to remove the solvent and form a cholesteric liquid crystal phase. Then, a high-pressure mercury lamp ("HX4000L" manufactured by Harrison Toshiba Lighting Co., Ltd.) was irradiated with UV for 5 to 10 seconds at an output of 120 W, and a cholesteric liquid crystal coating film (light reflecting layer RPRL) in which a cholesteric liquid crystal phase with a right-handed spiral structure was fixed was obtained. was made.
(2) A cholesteric liquid crystal coating film (light reflecting layer LPRL) in which a cholesteric liquid crystal phase having a left-handed spiral structure was fixed was prepared using the coating liquid L1 in the same procedure as in (1).
(3) The prepared adhesive (S1) was applied to the cholesteric liquid crystal coating surface of the light reflecting layer RPRL having a right-handed spiral structure using a wire bar so that the film thickness after drying was 10 μm. After removing the solvent by heating at 40° C. for 1 minute, the cholesteric liquid crystal coating surface of the light reflecting layer RPRL coated with the adhesive and the cholesteric liquid crystal coating surface of the light reflecting layer LPRL having a left-handed spiral structure were separated. and a hand roller to obtain an optical layered body in which two layers, a light reflecting layer RPRL having a right-handed spiral structure and a light reflecting layer LPRL having a left-handed spiral structure, are laminated via an adhesive layer. The reflection spectrum of this optical laminate was measured using a spectrophotometer ("MPC-3100" manufactured by Shimadzu Corporation) to determine the central reflection wavelength and the maximum reflectance. Also, the haze value was measured using a haze meter manufactured by Nippon Denshoku Co., Ltd. Table 5 shows the thickness of the optical laminate, the central reflection wavelength and maximum reflectance, the haze value, and the L ^* , a ^* , b ^* values at C light source. Also, FIG. 13 shows the measurement results of the reflection spectrum.
(4) After that, the PET film on the side of the light reflecting layer LPRL having a left-handed spiral structure is peeled off, and the adhesive (S1) is applied to the surface of the light reflecting layer LPRL from which the PET film has been peeled, and the thickness of the film after drying is It was applied using a wire bar so as to have a thickness of 10 μm. Furthermore, a polarizing element layer (“SKN-18243” manufactured by Nippon Kayaku Co., Ltd.) was attached to the surface coated with the adhesive to prepare an optical film of Comparative Example 1.

[Comparative Example 2]
An optical film of Comparative Example 2 was produced in the same manner as in Comparative Example 1 except that the coating liquid R10 was used instead of the coating liquid R1 and the coating liquid L10 was used instead of the coating liquid L1. FIG. 19 shows the measurement result of the reflection spectrum of the optical layered body.

[Polarization degree evaluation]
The degrees of polarization of the optical films of Examples 1 to 14 and Comparative Examples 1 and 2 were evaluated by the absolute polarization method using a spectrophotometer. The obtained results are shown in Tables 6 and 7.

As shown in Tables 4 to 7, when comparing Examples 1 to 9 and Comparative Example 1 (Group 1) in which the central reflection wavelength of the optical layered body is around 600 nm, Examples 1 to 9 are higher than Comparative Example 1. also showed a high degree of polarization. Further, when comparing Examples 10 to 14 and Comparative Example 2 (Group 2) in which the central reflection wavelength of the optical layered body is around 450 nm, Examples 10 to 14 show a higher degree of polarization than Comparative Example 2. rice field. Therefore, in both Groups 1 and 2, the optical film in which the light reflecting layer RPRL and the light reflecting layer LPRL are laminated adjacently without an adhesive layer is more It was shown that the degree of polarization increases. Moreover, each of Examples 1 to 14 showed a low haze value of 0.5% or less.

Therefore, the optical films of Examples 1 to 14 have both a high degree of polarization and a low haze value of less than 0.5%, and are suitable for use in optical members.

The optical film according to the present invention is suitable for application mainly to eyewear such as sunglasses, goggles, helmet visors, and the like.

1, 1A, 1B optical laminate 2 first light reflecting layer 3 second light reflecting layer 4 third light reflecting layer 5 adhesive layer 6 polarizer layer 10 optical film

Claims (8)

At least one light reflecting layer RPRL in which a cholesteric liquid crystal phase with a right-handed spiral structure having right-handed circularly polarized light reflectivity is fixed and at least one light reflection layer RPRL in which a cholesteric liquid crystal phase with a left-handed circularly polarized light reflectivity is fixed An optical laminate including a light reflecting layer LPRL and a polarizing element layer,
An optical film, wherein the light reflecting layer RPRL and the light reflecting layer LPRL are laminated adjacent to each other without an adhesive layer interposed therebetween. The optical film according to claim 1, wherein the optical laminate has a central reflection wavelength of 570 nm or more and 620 nm or less and a degree of polarization of 91% or more. The optical film according to claim 2, wherein the degree of polarization is 93% or more. The optical film according to claim 1, wherein the optical laminate has a central reflection wavelength of 380 nm or more and less than 570 nm or more than 620 nm and 780 nm or less, and a degree of polarization of more than 98%. The optical film according to claim 4, wherein the optical laminate has a central reflection wavelength of 380 nm or more and 480 nm or less. The optical film according to claim 5, wherein the degree of polarization is 98.5% or more. The optical film according to any one of claims 1 to 6, wherein the optical laminate has a haze value (Hz) of less than 0.5%. Eyewear comprising the optical film according to any one of claims 1 to 6.

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