Anisotropic optical film composition and anisotropic optical film

Abstract

Provided is a composition for an anisotropic optical film for producing a light-diffusing film that has both good diffusivity and good color. A composition for an anisotropic optical film, comprising (A-1) component: a (meth)acrylate having one or more fluorene skeletons and (meth)acryl groups, respectively, (A-2) component: a (meth)acrylate having one or more aromatic rings and (meth)acryl groups and not having a fluorene skeleton, (B) component: a thermoplastic polymer having a weight average molecular weight of 1,000 to 500,000 and a glass transition temperature of -40°C or higher, and (C) component: a photopolymerization initiator, the content of the (A-1) component being 3 parts by weight to 100 parts by weight relative to the content of the (A-2) component 100 parts by weight, and the content of the (B) component being 10 parts by weight to 400 parts by weight relative to the total of the (meth)acrylates including the (A-1) component and the (A-2) component 100 parts by weight.

Description

Technical Field

[0001] The present invention relates to anisotropic optical film compositions and anisotropic optical films manufactured using anisotropic optical film compositions. Background Technology

[0002] Various display devices, such as liquid crystal display (LCD) and organic electroluminescent elements (OLED), sometimes use anisotropic light diffusion films for purposes such as widening the viewing angle.

[0003] For example, Patent Document 1 discloses a composition for manufacturing a light diffusion film, comprising (meth)acrylate containing multiple aromatic rings as component (A), urethane (meth)acrylate as component (B), a photopolymerization initiator as component (C), and a specific hindered amine light stabilizer as component (D). In this composition, the content of component (A) is set to a value in the range of 25 parts by weight to 400 parts by weight relative to 100 parts by weight of component (B), and the content of component (C) is set to a value in the range of 0.2 parts by weight to 20 parts by weight relative to the total amount of components (A) and (B) (100 parts by weight), and the content of component (D) is set to a value in the range of 0.1 parts by weight to 10 parts by weight relative to the total amount of components (A) and (B) (100 parts by weight).

[0004] In addition, Patent Document 2 discloses a photocurable composition containing a fluorene compound (A) with intramolecularly polymerizable carbon-carbon double bonds, a cationic polymerizable compound (B) with a refractive index different from that of the fluorene compound (A), and a photocationic polymerization initiator (C), as a raw material suitable for use as a light control film.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 5914751

[0008] Patent Document 2: Japanese Patent Application Publication No. 2008-239757 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, the light diffusion film in Patent Document 1 has the disadvantage of requiring a relatively thick film thickness to achieve sufficient light diffusion. Furthermore, regarding the light control film in Patent Document 2, if the cationic polymerization initiator used as a composition material remains after the composition has cured, it may cause adverse effects on other components during the fabrication of display devices. Moreover, conventional light diffusion films sometimes exhibit insufficient transparency and thus a tinted appearance.

[0011] Therefore, the objective of this invention is to provide an anisotropic optical film composition for manufacturing a light-diffusing film that can achieve both good diffusion and good hue.

[0012] Methods for solving problems

[0013] The inventors conducted a detailed study of Patent Documents 1 and 2 and discovered that an anisotropic optical film composition containing specific components can solve the aforementioned problems. Therefore, the present invention is as follows.

[0014] This invention relates to a composition for anisotropic optical films, characterized in that it comprises:

[0015] (A-1) components include (meth)acrylates having one or more fluorene skeletons and (meth)acryloyl groups.

[0016] (A-2) consists of (meth)acrylates having one or more aromatic rings and (meth)acryloyl groups but lacking a fluorene skeleton.

[0017] Component (B) consists of thermoplastic polymers with a weight-average molecular weight of 1,000 to 500,000 and a glass transition temperature of -40°C or higher, and

[0018] As a photopolymerization initiator for component (C),

[0019] When the content of component (A-2) is set to 100 parts by weight, the content of component (A-1) in the above composition is 3 parts by weight to 100 parts by weight.

[0020] When the total content of (meth)acrylates containing the above-mentioned components (A-1) and (A-2) is set to 100 parts by weight, the content of component (B) in the above composition is 10 parts by weight to 400 parts by weight.

[0021] The above-mentioned (A-1) component can have two or more aromatic rings as substituents for the fluorene skeleton in one molecule.

[0022] The refractive index of the above (A-1) component can be 1.55 to 1.70.

[0023] The above-mentioned (A-1) component may have multiple (meth)acryloyl groups.

[0024] The above-mentioned component (A-2) can have multiple aromatic rings in one molecule.

[0025] The refractive index of the above (A-2) component can be 1.50 to 1.65.

[0026] The above-mentioned component (A-2) may have a biphenyl structure and / or a diphenyl ether structure.

[0027] The refractive index of component (B) can be 1.35 to 1.50.

[0028] In addition, the present invention is an anisotropic optical film, which is a cured product of the above-mentioned anisotropic optical film composition, characterized in that the above-mentioned anisotropic optical film has a substrate region and a plurality of columnar regions with a refractive index different from that of the substrate region.

[0029] The aforementioned anisotropic optical film has multiple columnar regions configured to be oriented and extend from one surface of the anisotropic optical film to another.

[0030] The average major axis / average minor axis of the columnar region in the cross section perpendicular to the columnar axis of the anisotropic optical film can be 1 to 50.

[0031] The thickness of the anisotropic optical film can be from 10 μm to 100 μm.

[0032] Invention Effects

[0033] According to the present invention, it is possible to provide an anisotropic optical film composition for manufacturing a light diffusion film that can achieve both good diffusion and good hue. Attached Figure Description

[0034] Figure 1 This is a schematic diagram illustrating an example of anisotropic optical films.

[0035] Figure 2 It is a top view showing the surface structure of anisotropic optical films.

[0036] Figure 3 This is a diagram showing an example of the optical profile in an anisotropic optical film.

[0037] Figure 4 It is a three-dimensional polar coordinate display used to illustrate the scattering center axis in anisotropic optical films.

[0038] Figure 5 This is a schematic diagram illustrating the method for measuring the diffusion properties of anisotropic optical films.

[0039] Figure 6This is a schematic diagram illustrating any step 1-3 in the manufacturing method of the anisotropic optical film of the present invention. Detailed Implementation

[0040] The anisotropic optical film composition of the present invention and the anisotropic optical film obtained by curing the anisotropic optical film composition will be described. It should be noted that the anisotropic optical film composition refers to a composition used to manufacture anisotropic optical films.

[0041] In the following description, where the upper limit and lower limit are described separately, all combinations of the upper limit and lower limit are described in this specification.

[0042] In this invention, the refractive index of each component is expressed as the refractive index determined according to the method of JIS K0062.

[0043] <<<<Compositions for Anisotropic Optical Films>>>>

[0044] <<<Ingredients>>>

[0045] The anisotropic optical film composition of the present invention comprises component (A) as a (meth)acrylate, component (B) as a thermoplastic polymer, and component (C) as a photopolymerization initiator. Furthermore, component (A) comprises component (A-1) and component (A-2), wherein component (A-1) is a (meth)acrylate having one or more fluorene backbones and (meth)acryloyl groups, and component (A-2) is a (meth)acrylate having one or more aromatic rings and (meth)acryloyl groups but without a fluorene backbone.

[0046] Furthermore, the anisotropic optical film composition may also include component (D) as another component.

[0047] The following is a description of each component.

[0048] <<(A)Ingredient>>

[0049] <(A-1) Ingredient: (Meth)acrylate>

[0050] (A-1) is a (meth)acrylate having one or more fluorene skeletons and (meth)acryloyl groups.

[0051] The (A-1) component may contain one or more aromatic rings (aromatic ring groups / groups containing aromatic rings) as substituents of the fluorene skeleton, preferably containing two or more aromatic rings as substituents of the fluorene skeleton. There is no particular limit to the upper limit of the number of aromatic rings contained in the (A-1) component as substituents of the fluorene skeleton, but for example, it is preferably 10 or less.

[0052] The number of (meth)acryloyl groups contained in component (A-1) is not particularly limited, and may be one or two or more, preferably containing multiple (meth)acryloyl groups. Furthermore, as an upper limit, there is no particular limitation, but eight or fewer is preferred.

[0053] Specifically, as a (A-1) component containing two or more aromatic rings as substituents of the fluorene skeleton, the following compound (Formula A) can be exemplified.

[0054] [Chemistry A]

[0055]

[0056] In the above formula A, R A and R C Each is independently a substituent containing a (meth)acryloyl group, preferably a (meth)acryloyloxy group (which can undergo EO addition or PO addition with a repetition number of 1 to 5), R B and R D Each is an aliphatic substituent consisting of 1 to 6 hydrogen atoms or carbon atoms.

[0057] More specifically, as component (A-1), the compounds shown in (Formula B) to (Formula D) below can be exemplified.

[0058] [Chemistry B]

[0059]

[0060] [Chemistry C]

[0061]

[0062] [Chemistry D]

[0063]

[0064] (A-1) can be a commercially available product. Examples of commercially available products that can be used as (A-1) include "A-BPEF-2" (9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene diacrylate) manufactured by Shin-Nakamura Chemical Co., Ltd., and "OGSOL EA-0200", "OGSOL EA-0300", "OGSOL EA-5060GP", and "OGSOL GA-2800" manufactured by Osaka Gas Chemical Co., Ltd.

[0065] The refractive index of the (A-1) component is preferably 1.50 or higher, more preferably 1.53 or higher, and even more preferably 1.56 or higher. There is no particular limitation on the upper limit of the refractive index; for example, it is preferably 1.70 or lower. By making the refractive index of the (A-1) component within such a range, the diffusion properties of the anisotropic optical film can be further improved.

[0066] (A-1) The ingredient may contain only one of the ingredients mentioned above, or it may contain multiple ingredients.

[0067] <(A-2) Ingredient: (Meth)acrylate>

[0068] Component (A-2) is different from component (A-1), and is a (meth)acrylate that has one or more aromatic rings and (meth)acryloyl groups but does not have a fluorene skeleton.

[0069] (A-2) The component preferably has multiple aromatic rings. As a structure containing multiple aromatic rings, it is preferably a biphenyl structure and / or a diphenyl ether structure. Such a biphenyl structure or diphenyl ether structure may be present in only one or more of the skeleton. By having such a structure, a (meth)acrylate with a very high refractive index is obtained.

[0070] The (A-2) component is typically a high refractive index material. Specifically, the refractive index of the (A-2) component is preferably 1.50 or higher, more preferably 1.53 or higher, and even more preferably 1.56 or higher. There is no particular limitation on the upper limit of the refractive index; for example, it is preferably 1.65 or lower. By making the refractive index of the (A-2) component within such a range, the diffusion properties of the anisotropic optical film can be further improved.

[0071] As such component (A-2), there are no particular limitations, and examples include biphenyl compounds represented by the following general formula (1) or diphenyl ether compounds represented by the following general formula (2).

[0072] [Chemistry 1]

[0073]

[0074] [Chemistry 2]

[0075]

[0076] In general formula (1), R 1 ~R 10 Each is independent, R 1 ~R 10 Any one of them is a substituent shown in the general formula (3) or (4) below. The others only need not contain (meth)acryloyl groups, specifically, substituents such as hydrogen atoms, hydroxyl groups, carboxyl groups, alkyl groups, alkoxy groups, haloalkyl groups, hydroxyalkyl groups, carboxylalkyl groups and halogen atoms can be included.

[0077] In addition, in general formula (2), R 11 ~R 20 Each is independent, R 11 ~R 20Any one of them is a substituent shown in the general formula (3) or (4) below. The others only need not contain (meth)acryloyl groups, specifically, substituents such as hydrogen atoms, hydroxyl groups, carboxyl groups, alkyl groups, alkoxy groups, haloalkyl groups, hydroxyalkyl groups, carboxylalkyl groups and halogen atoms can be included.

[0078] [Chemistry 3]

[0079]

[0080] In general formula (3), R 21 It can be a hydrogen atom or a methyl group, n is an integer from 1 to 4, and the repetition number m is an integer from 1 to 10.

[0081] [Chemistry 4]

[0082]

[0083] In general formula (4), R 22 It can be a hydrogen atom or a methyl group, n is an integer from 1 to 4, and the repetition number m is an integer from 1 to 10.

[0084] It is generally preferred to set the number of repetitions m in the substituents shown in the above general formulas (3) and (4) to be an integer from 1 to 10.

[0085] The reason is that if the number of repetitions m is greater than 10, the refractive index enhancement effect from the aromatic rings unique to the (A-2) component is sometimes suppressed, and the diffusivity of the anisotropic optical film will decrease.

[0086] Therefore, it is more preferable to set the number of repetitions m in the substituents shown in general formulas (3) and (4) to an integer of 1 to 4, and even more preferably to set it to an integer of 1 to 2.

[0087] It should be noted that, from the same point of view, it is generally preferred to set n in the substituents shown in general formulas (3) and (4) to be an integer from 1 to 4, and more preferably to be an integer from 1 to 2.

[0088] As a specific example of the biphenyl compound represented by the above general formula (1), the compound represented by the following formula (5) can be preferably listed.

[0089] [Chemistry 5]

[0090]

[0091] As a specific example of the diphenyl ether compound represented by the above general formula (2), the compound represented by the following formula (6) can be preferably listed.

[0092] [Chemistry 6]

[0093]

[0094] (A-2) The ingredients may contain only one of the ingredients mentioned above, or they may contain multiple ingredients.

[0095] (A-2) Component Viscosity)

[0096] The viscosity of component (A-2) at 25°C is preferably 1000 mPa·s or less, more preferably 500 mPa·s or less, and even more preferably 100 mPa·s or less. The lower limit of viscosity is not particularly limited, for example, it is 1 mPa·s.

[0097] By setting the viscosity of component (A-2) at 25°C to these ranges, the fluidity of the composition is improved when components (A-1) and (A-2) are used in combination. This promotes phase separation of the components during curing and improves the diffusion properties of the resulting anisotropic optical film.

[0098] <Other (A) Ingredients: (Meth)acrylate>

[0099] To the extent that it does not impair the effects of the invention, component (A) may contain (meth)acrylates (other (meth)acrylates commonly used in optical film compositions) other than components (A-1) and (A-2).

[0100] (A) Component viscosity)

[0101] In this invention, the viscosity of component (A) as a whole at 25°C is preferably 10,000 mPa·s or less, more preferably 5,000 mPa·s or less, even more preferably 3,000 mPa·s or less, and particularly preferably 1,000 mPa·s or less. It should be noted that the viscosity of component (A) as a whole at 25°C is most preferably 500 mPa·s or less, 250 mPa·s or less, or 100 mPa·s or less. The lower limit of viscosity is not particularly limited, for example, it is 1 mPa·s.

[0102] By setting the viscosity of component (A) as a whole at 25°C within these ranges, the fluidity of the composition is improved when components (A-1), (A-2), and other components (A) are used in combination. This promotes phase separation of the components during curing and improves the diffusion properties of the resulting anisotropic optical film.

[0103] <<(B) Composition: Thermoplastic polymer>>

[0104] (B) The glass transition temperature of the component is -40°C or higher, preferably 0°C or higher, and more preferably 30°C or higher. There is no particular upper limit to the glass transition temperature, but it is preferably 150°C or lower.

[0105] The glass transition temperature can be determined by known methods, such as those according to JIS K7121-1987 "Method for determination of transition temperature of plastics".

[0106] (B) The weight-average molecular weight of the component is 1,000 to 500,000, preferably 10,000 to 400,000, and more preferably 50,000 to 300,000.

[0107] Weight-average molecular weight can be determined using well-known methods, such as the GPC method as a conversion of molecular weight for polystyrene.

[0108] By setting the glass transition temperature and weight-average molecular weight of component (B) within the above range, the compatibility with components (A-1) and (A-2) can be improved, resulting in an anisotropic optical film with excellent performance. This improves durability in heat resistance tests and allows the anisotropic optical film to have a suitable elastic modulus before UV curing, enabling it to be stored in rolls.

[0109] Component (B) is typically a low-refractive-index material. Specifically, the refractive index of component (B) is preferably 1.50 or less, more preferably 1.49 or less, and even more preferably 1.48 or less. The lower limit of the refractive index is not particularly limited, for example, it is 1.35 or more.

[0110] As such component (B), there are no particular limitations, and examples include acrylic resins, styrene resins, styrene-acrylic copolymers, polyurethane resins, polyester resins, epoxy resins, cellulose resins, silicone resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral resins, polyvinyl alcohol resins, polyvinyl formal resins, polyvinyl acetal resins, polyvinylidene fluoride, PMMA-PBA block copolymers, PVDF-HFP copolymers, etc.

[0111] By incorporating such a (B) component, phase separation can be easily achieved through the refractive index difference with high-refractive-index materials containing (A-1) and (A-2) components. Furthermore, it is less prone to indentation when fabricating anisotropic optical films, and can produce optical films with excellent storage properties.

[0112] (B) The ingredients may contain only one of the ingredients mentioned above, or they may contain multiple ingredients.

[0113] <<(C) Component: Photopolymerization Initiator>>

[0114] (C) The photopolymerization initiator is a compound that generates free radicals by irradiation with active energy rays such as ultraviolet light, and can be a known substance.

[0115] Examples of photopolymerization initiators include benzophenone, benzoyl, michalcone, 2-chlorothioxanone, 2,4-diethylthioxanone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-diethoxyacetophenone, benzoyl dimethyl ketal, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, and 2-methyl... Examples of such products include 1-[4-(methylthio)phenyl]-2-morpholinoacetone-1, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, bis(cyclopentadienyl)-bis[2,6-difluoro-3-(pyrrolo-1-yl)phenyl]titanium, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and 2,4,6-trimethylbenzoyl diphenylphosphine oxide.

[0116] These compounds can be used individually or in combination.

[0117] Photopolymerization initiators can usually be used by directly dissolving the powder in a photopolymerizable compound. However, in cases of poor solubility, the photopolymerization initiator can also be used by pre-dissolving it in a solvent.

[0118] <<(D) Ingredients: Other Ingredients>>

[0119] To improve photopolymerization, component (D) may contain various known dyes, sensitizers, and other known additives. Additionally, it may contain solvents, dispersion media, etc.

[0120] Furthermore, a thermosetting initiator that can cure photopolymerizable compounds by heating can be used in conjunction with a photopolymerization initiator. In this case, by heating after photocuring, it is expected that the polymerization and curing of the photopolymerizable compound will be further promoted, thus achieving complete curing.

[0121] Solvents used in preparing compositions containing photopolymerizable compounds include, for example, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, xylene, etc.

[0122] It should be noted that if the acid-generating agent used as a cationic polymerization initiator remains after the composition has cured, it is considered that it may cause adverse effects on other components when used in devices such as displays. Therefore, it is preferable that the acid-generating agent is not present in the composition. For example, the content of the acid-generating agent in the composition is preferably 1% or less.

[0123] <<Content of each component>>>

[0124] When the content of component (A-2) is set to 100 parts by weight, the content of component (A-1) in the composition is 3 parts by weight to 100 parts by weight, preferably 4 parts by weight to 50 parts by weight, and more preferably 5 parts by weight to 25 parts by weight.

[0125] The total content of components (A-1) and (A-2) relative to component (A) (hereinafter, it is set as the total of (meth)acrylates including components (A-1) and (A-2)) can be set to 50% by weight or more (preferably 70% by weight or more, 80% by weight or more, or 90% by weight or more).

[0126] When the content of component (A) is set to 100 parts by weight, the content of component (B) in the composition is 10 parts by weight to 400 parts by weight, preferably 25 parts by weight to 200 parts by weight, and more preferably 50 parts by weight to 100 parts by weight.

[0127] The total proportion of component (A) and component (B) relative to the total solid components of the composition (the total amount of non-volatile components excluding volatile solvents) is not particularly limited, but can be set to 50% by weight or more.

[0128] By setting the contents of component (A) and component (B) in the composition to the ranges described above, the interaction between the components can be made appropriate.

[0129] The content of component (C) in the composition is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, relative to 100 parts by weight of component (A).

[0130] The anisotropic optical film composition of the present invention can achieve both good diffusion and good hue by setting the content of each component within the range described above.

[0131] Next, a preferred example of an anisotropic optical film obtained using the anisotropic optical film composition will be described. It should be noted that if the anisotropic optical film composition is used, anisotropic optical films other than the anisotropic optical films shown below can also be manufactured.

[0132] <<<<Anisotropic Optical Films>>>>

[0133] Anisotropic optical films exhibit anisotropy and directivity, where the diffusion, transmission, and diffusion distribution of light vary according to the incident angle. Therefore, they differ from directional diffusion films, isotropic diffusion films, and diffusion films oriented in a specific orientation, which are not dependent on the incident angle.

[0134] In anisotropic optical films, the linear transmittance (the amount of light transmitted in the straight direction of the incident light / the amount of incident light) changes depending on the incident light angle. That is, for incident light relative to the anisotropic optical film, the incident light in a predetermined angle range mainly undergoes transmission due to increased linearity, while the incident light in other angle ranges mainly undergoes diffusion due to increased diffraction.

[0135] <<<Structure>>>

[0136] The anisotropic optical film in this invention has a substrate region and multiple columnar regions with different refractive indices than the substrate region.

[0137] The "matrix region" and "multiple columnar regions" within the anisotropic optical film are regions formed by local differences in refractive index of the materials constituting the anisotropic optical film of the present invention, representing relative regions with lower or higher refractive indices compared to one another. These regions are formed through phase separation during the curing of the materials forming the anisotropic optical film.

[0138] That is, the so-called difference in refractive index is only required to be that at least a portion of the light incident on the anisotropic optical film is reflected at the interface between the substrate region and the columnar region to a different degree, without any particular limitation.

[0139] The multiple columnar regions contained in anisotropic optical films are typically configured to be oriented and extend from one surface of the anisotropic optical film to another (see reference). Figure 1 ).

[0140] <<Columnar Area>>

[0141] The length of the columnar region is not particularly limited; it can be the length that extends from one surface of the anisotropic optical film to another, or it can be the length that does not extend from one surface to another.

[0142] The surface shape of the cross section perpendicular to the column axis of multiple columnar regions of anisotropic optical films can be set to have a minor axis and a major axis.

[0143] The surface shape of the columnar region is not particularly limited; for example, it can be circular, elliptical, or polygonal. In the case of a circle, the minor axis and the major axis are equal. In the case of an ellipse, the minor axis is the length of the minor axis, and the major axis is the length of the major axis. In the case of a polygon, the shortest length connecting two points on the polygon's outline can be used as the minor axis, and the longest length can be used as the major axis. Figure 2 The image shows a columnar region as viewed from the surface direction of the anisotropic optical film. Figure 2 In this context, LA represents the major axis and SA represents the minor axis.

[0144] Regarding the minor and major axes of the columnar regions, an optical microscope can be used to observe the surface of the anisotropic optical film in a section perpendicular to the columnar axis of the columnar region. The minor and major axes of 20 randomly selected columnar regions are measured and taken as their average values.

[0145] The ratio of the average major axis to the average minor axis of the columnar region (average major axis / average minor axis), i.e., the aspect ratio, is not particularly limited, and can be set to 1 to 50 for example.

[0146] Figure 2 (a) An anisotropic optical film with an aspect ratio of 2 to 50 representing columnar regions. Figure 2 (b) indicates an anisotropic optical film with an aspect ratio of 1 or more and less than 2 in the columnar region.

[0147] When the aspect ratio is greater than or equal to 1 and less than 2, and light is irradiated with light parallel to the columnar axis of the columnar region, the transmitted light diffuses isotropically (see reference). Figure 1 (a)). On the other hand, when the aspect ratio is 2 to 50, similarly, when light parallel to the column axis is irradiated, diffusion occurs with anisotropy corresponding to the aspect ratio (see [reference]). Figure 1 (b)).

[0148] It should be noted that when the aspect ratio is set to 2-50, a more anisotropic diffusion occurs when the aspect ratio is set to a range greater than 20 and less than 50. On the other hand, when the aspect ratio is set to a range of 2-20, it has intermediate properties between an aspect ratio of 1 or more and less than 2 and an aspect ratio of more than 20 and less than 50. Thus, by dividing the aspect ratio range into 1 or more and less than 2, 2-20, and more than 20 and less than 50, anisotropic optical films with different optical properties can be produced. The anisotropic optical film composition of the present invention can be used as a preferred raw material in the manufacture of anisotropic optical films having any aspect ratio.

[0149] Anisotropic optical films can contain multiple columnar regions with one aspect ratio or multiple columnar regions with different aspect ratios.

[0150] <<<Scattering Central Axis>>>

[0151] Anisotropic optical films have a scattering central axis.

[0152] The term "scattering center axis" refers to the direction that coincides with the incident light angle when the incident light angle of an anisotropic optical film is varied, provided that the light diffraction is approximately symmetrical about that incident light angle. It is described as "approximately symmetrical" because, strictly speaking, the optical profile related to light diffraction (described later) is not symmetrical when the scattering center axis is tilted relative to the film's normal direction (the film thickness direction).

[0153] Here, the scattering center axis and the orientation direction (extension direction) of the columnar region are usually parallel. It should be noted that the parallelism between the scattering center axis and the orientation direction of the columnar region is only required to satisfy the refractive index law (Snell's law), and does not need to be strictly parallel.

[0154] In addition to observing the tilt of the columnar region in the cross-section of the anisotropic optical film using an optical microscope and changing the incident light angle to observe the projection shape of the light passing through the anisotropic optical film, the scattering center axis can also be confirmed by the optical profile.

[0155] Snell's law states that when light is incident from the interface between a medium with refractive index n1 and a medium with refractive index n2, the relationship n1sinθ1 = n2sinθ2 holds between the incident angle θ1 and the refraction angle θ2. For example, if n1 = 1 (air) and n2 = 1.51 (anisotropic optical film), then with an incident angle of 30°, the orientation direction (refraction angle) of the columnar region is approximately 19°. Thus, even if the incident angle and the refraction angle are different, as long as Snell's law is satisfied, it is included in the concept of parallelism in this invention.

[0156] As described above, the scattering center axis refers to the direction coinciding with the incident light angle of light whose diffraction is approximately symmetrical about that incident light angle when the incident light angle of the anisotropic optical film changes. It should be noted that the scattering center axis can be determined by creating an optical profile, as a graph representing the relationship, after measuring the linear transmittance based on the incident light angle of the anisotropic optical film. Let this optical profile be an example. Figure 3 The incident light angle at approximately the center of the diffuse region, sandwiched between the minimum values ​​of linear transmittance. Figure 3 (Approximately 0° in the case of conditions).

[0157] Optical profiles do not directly represent light diffusion, but if interpreted as an increase in diffuse transmittance due to a decrease in linear transmittance, then it can be said to roughly indicate light diffusion.

[0158] In addition, such as Figure 3As shown, the range of two incident light angles relative to the midpoint between the maximum and minimum linear transmittance is called the "diffusion region", and the range of incident light angles other than this is called the "non-diffusion region".

[0159] Next, refer to Figure 4 The scattering central axis P in the anisotropic optical film is explained from other viewpoints. Figure 4 It is a three-dimensional polar coordinate display used to illustrate the scattering central axis P in anisotropic optical films.

[0160] according to Figure 4 As shown in the three-dimensional polar coordinate display, if the surface of the anisotropic optical film is set as the xy plane, and the normal to the surface of the anisotropic optical film is set as the z-axis, then the scattering center axis can pass through the polar angle θ and the azimuth angle. To express it. That is, Figure 4 In this context, Pxy can be referred to as the length direction of the scattering center axis projected onto the surface of the anisotropic optical film.

[0161] Here, the normal of the anisotropic optical film can be... Figure 4 The polar angle θ (-90° < θ < 90°) between the z-axis and the columnar region is defined as the scattering center axis angle. In the process of photocuring the uncured resin composition layer to form the columnar region, the angle of the columnar axis direction of the columnar region can be adjusted to the required range by changing the direction of the irradiated light.

[0162] <<<Thickness>>>

[0163] The thickness of the anisotropic optical film is not particularly limited, but is preferably 10 μm to 500 μm, more preferably 10 μm to 200 μm, and even more preferably 10 μm to 100 μm.

[0164] <<Diffusion Properties>>

[0165] The diffusion properties of anisotropic optical films can be measured, for example, as follows. It should be noted that the measurement conditions for these diffusion properties can be found in the detailed methods described in the examples.

[0166] like Figure 5As shown, an anisotropic optical film is positioned between the light source and the detector. In this method, the detection angle is set to 0° when light is detected in the straight direction of light travel. Furthermore, the detector is configured to rotate arbitrarily while maintaining a constant distance from the anisotropic optical film, while the light source and the anisotropic optical film are fixed. Regarding the rotation angle of the detector when the anisotropic optical film is fixed, when the angle at which the incident light is perpendicularly incident on the anisotropic optical film is set to 0°, any angle within the range of -90° to +90° in one direction (the flow direction in the film manufacturing process, i.e., the MD direction, or the direction perpendicular to the MD direction, i.e., the TD direction) centered at 0° can be selected, allowing for the evaluation of diffusion performance relative to each incident light angle. According to this method, the higher the diffusion performance of the optical film, the wider the detection angle range where the detected amount of scattered and transmitted light exceeds a specific value. In this invention, the ratio of the amount of scattered transmitted light to the amount of light (the amount of incident light) directly irradiated from the light source to the detector at a detection angle of 0° without passing through the anisotropic optical film is defined as the scattering transmittance (%). The range of detection angles that satisfy "scattering transmittance (%) > 0.1%" is defined as the "diffusion width" as an indicator of diffusion performance.

[0167] An anisotropic optical film obtained by using the anisotropic optical film composition of the present invention can have a diffusion width of 32° or more.

[0168] <<<Hue>>>

[0169] The hue of the anisotropic optical film was determined using a spectrophotometer (Shimadzu Corporation, UV-2450). * a * b * (CIE1976) obtained.

[0170] Hue b of anisotropic optical films * Preferably -7.00 to +7.00, more preferably -2.00 to +2.00.

[0171] <<<Manufacturing Methods of Anisotropic Optical Films>>>

[0172] Next, a method for manufacturing anisotropic optical films using anisotropic optical film compositions will be described.

[0173] First, an anisotropic optical film composition (hereinafter sometimes referred to as "photocurable resin composition") is coated onto a suitable substrate such as a transparent PET film, formed into a sheet, dried as needed to evaporate the solvent, and an uncured resin composition layer is formed. Anisotropic optical films can be produced by irradiating light onto this uncured resin composition layer.

[0174] More specifically, the formation process of anisotropic optical films mainly includes the following steps.

[0175] (1) Step 1-1: Step of applying an uncured resin composition layer onto the substrate

[0176] (2) Process 1-2: The process of obtaining parallel light rays from the light source.

[0177] (3) Any steps 1-3: Steps to obtain directional light.

[0178] (4) Steps 1-4: Steps to cure the uncured resin composition layer

[0179] <<Process 1-1: Process of setting an uncured resin composition layer on the substrate>>

[0180] The method of applying a UV-curable resin composition as an uncured resin composition layer in sheet form on a substrate can be applied using conventional coating and printing methods. Specifically, it can utilize air knife coating, rod coating, doctor blade coating, reverse coating, transfer roller coating, gravure roller coating, kiss coating, casting coating, spraying, slotted hole coating, curtain coating, damcoating, impregnation coating, mold coating, gravure printing, screen printing, and other printing methods. When the composition has a low viscosity, a weir of a certain height can also be formed around the substrate, and the composition can be cast inside the weir.

[0181] In step 1-1, in order to prevent oxygen obstruction of the uncured resin composition layer, a columnar region characterized by anisotropic optical film is efficiently formed, which can also be laminated with the light-irradiated side of the uncured resin composition layer to locally change the light irradiation intensity.

[0182] The mask material is a material in which light-absorbing fillers such as carbon are dispersed in a matrix. A portion of the incident light is absorbed by the carbon, but the openings are preferably designed to allow sufficient light transmission. Such a matrix can be transparent plastics such as PET, TAC, PVAc, PVA, acrylic, and polyethylene, or inorganic materials such as glass and quartz. Alternatively, the mask can also be a patterned mask formed by controlling the amount of ultraviolet light transmitted through a sheet containing these matrices, or a mask containing ultraviolet-absorbing pigments.

[0183] Without using such a mask, oxygen barrier of the uncured resin composition layer can be prevented by light irradiation under a nitrogen atmosphere. Furthermore, even simply laminating a conventional transparent film onto the uncured resin composition layer is effective in preventing oxygen barrier and promoting the formation of columnar regions. During light irradiation through such a mask and transparent film, a photopolymerization reaction occurs in the composition containing the photopolymerizable compound, corresponding to the irradiation intensity, thus easily producing a refractive index distribution, which is effective for the fabrication of anisotropic optical films according to this method.

[0184] <<Process 1-2: Process of obtaining parallel light rays from a light source>>

[0185] As a light source, short-arc ultraviolet light is typically used. Specifically, high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, xenon lamps, etc., can be used. At this time, it is necessary to obtain light rays parallel to the desired scattering central axis. Such parallel light rays can be obtained, for example, by configuring a point light source and placing an optical lens, such as a Fresnel lens, between the point light source and the uncured resin composition layer to illuminate the parallel light rays. Furthermore, a reflector can be placed behind the light source to direct the light as a point light source in a predetermined direction.

[0186] <<Any Steps 1-3: Steps to Obtain Directional Light>>

[0187] Any step 1-3 is a step in which parallel light rays are incident on a directional diffuser element to obtain directional light rays. Figure 6 This is a schematic diagram illustrating any step 1-3 in the manufacturing method of the anisotropic optical film of the present invention.

[0188] The directional diffusion elements 11 and 12 used in any of the steps 1-3 only need to impart directionality to the parallel light ray A incident from the light source 10.

[0189] Figure 6 The description describes directional light (B1 or B2) incident on the uncured resin composition layer 1 in a manner that diffuses extensively in the x-direction and diffuses almost non-existently in the y-direction. To obtain such directional light, for example, a method can be used whereby needle-shaped fillers with a high aspect ratio are included in the directional diffusion elements 11 and 12, and these needle-shaped fillers are oriented such that they extend along the y-direction in the long axis direction. Besides using needle-shaped fillers, various other methods can be used for the directional diffusion elements 11 and 12.

[0190] Here, the aspect ratio of the directional light can be between 2 and 50. A columnar region with an aspect ratio that roughly corresponds to this aspect ratio is formed.

[0191] In any of steps 1-3, by adjusting the directional spread of light, the size (aspect ratio, minor axis SA, major axis LA, etc.) of the formed columnar region can be appropriately determined. For example, in Figure 6 Anisotropic optical films of this method can be obtained from either (a) or (b). Figure 6 The difference between (a) and (b) is that the directional light spread is larger in (a) (B1) and smaller in (b) (B2). The size of the columnar region varies depending on the size of the directional light spread.

[0192] The propagation of directional light depends primarily on the types of directional diffusion elements 11 and 12 and their distance from the uncured resin composition layer 1. As this distance decreases, the size of the columnar region decreases; as the distance increases, the size of the columnar region increases. Therefore, by adjusting this distance, the size of the columnar region can be adjusted.

[0193] <<Steps 1-4: Steps to cure the uncured resin composition layer>>

[0194] The light used to cure the uncured resin composition layer by irradiation needs to contain wavelengths capable of curing photopolymerizable compounds; typically, light from a mercury lamp with a wavelength centered at 365 nm is used. When using this wavelength band to fabricate anisotropic optical films, an illuminance of 0.01 mW / cm² is preferred. 2 ~100mW / cm 2 The range is more preferably 0.1 mW / cm 2 ~20mW / cm 2 This is because if the illuminance is less than 0.01 mW / cm² 2 If the curing time exceeds 100mW / cm, the production efficiency will decrease. 2 If the photopolymerizable compound cures too quickly, it will not form a structure and will not exhibit the target optical properties.

[0195] It should be noted that the irradiation time is not particularly limited, but is preferably 10 to 180 seconds, and more preferably 30 to 120 seconds. By irradiating with the above light, the anisotropic optical film of this method can be obtained.

[0196] As described above, anisotropic optical films are obtained by irradiating the uncured resin composition layer with low-intensity light for an extended period, thereby forming a specific internal structure. Therefore, with only such light irradiation, unreacted monomer components may remain, sometimes resulting in stickiness, or problems with workability and durability. In such cases, additional irradiation at 1000 mW / cm² can be applied. 2The above high-intensity light causes the residual monomers to polymerize. At this point, the light irradiation can also be performed from the opposite side of the side where the mask is stacked.

[0197] As described above, when curing the uncured resin composition layer, by adjusting the angle of the light irradiating the uncured resin composition layer, the scattering center axis of the resulting anisotropic optical film can be made to the desired value.

[0198] It should be noted that anisotropic optical films can further have other layers (adhesive layers, functional layers, transparent film layers, etc.).

[0199] <<<Applications of Anisotropic Optical Films>>>

[0200] Anisotropic optical films, due to their excellent improvement in viewing angle dependence, can be applied to all display devices, including liquid crystal displays (LCDs), organic EL displays, and plasma displays. Furthermore, when used in reflective liquid crystal displays, anisotropic optical films can be expected to improve reflective brightness relative to a specific direction. In addition to good diffusion properties, anisotropic optical films also possess excellent hue; therefore, when used in transmissive liquid crystal displays, they can be expected to improve grayscale inversion. Moreover, anisotropic optical films can also be applied to lighting fixtures and building materials.

[0201] Example

[0202] The invention will now be described in more detail by way of examples and comparative examples, but the invention is not limited by these examples.

[0203] (Manufacturing of anisotropic optical films)

[0204] The anisotropic optical film of the present invention and the anisotropic optical film of the comparative example were manufactured according to the following method.

[0205] [Example 1]

[0206] 1. Preparation of composition solution 1 for anisotropic optical films

[0207] The various materials shown below are mixed in the amounts shown below, diluted appropriately with butyl acetate solvent, and stirred to obtain an anisotropic optical film composition solution 1.

[0208] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using a type B viscometer (BM type, manufactured by Toki Sangyo Co., Ltd.), and the result was 38 mPa·s (25°C).

[0209] • (A-1) Composition: 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: A-BPEF-2, refractive index: 1.62 (25°C), viscosity: 100,000 mPa·s or more (25°C), number of aromatic rings in the substituents of the fluorene skeleton: 2) 10 parts by weight

[0210] • (A-2) Composition: 90 parts by weight of m-phenoxybenzyl acrylate (refractive index: 1.57 (25℃), viscosity: 18 mPa·s (25℃))

[0211] (B) Composition: Polyvinyl acetate (PVAc) (refractive index: 1.46 (25℃), weight-average molecular weight: 200,000, glass transition temperature: 40℃) 80 parts by weight

[0212] • (C) Ingredients: 2 parts by weight of 2,2-dimethoxy-2-phenylacetophenone

[0213] 2. Preparation of Composition 1 for Anisotropic Optical Films

[0214] The anisotropic light diffusion film composition solution 1 was applied to a 100 μm thick PET film using a spreader, and then the coating was dried in a clean oven with the drying oven temperature set to 80 °C, thereby obtaining anisotropic optical film composition 1 with a film thickness of 50 μm.

[0215] 3. Fabrication of anisotropic optical film 1

[0216] Next, for the side of the anisotropic optical film composition 1 that is not in contact with the PET film, a polyvinyl alcohol film (hereinafter referred to as a PVA mask) with uniformly dispersed carbon is laminated using a laminator. The resulting laminate is heated to 70°C, and while maintaining a constant temperature, it is irradiated from the PVA mask surface at an intensity of 2 mW / cm². 2 Parallel light emitted from the incident irradiation unit (manufactured by Hamamatsu Optoelectronics Co., Ltd., trade name: L2859-01) is irradiated from the normal direction of the above-mentioned stacked body for 30 seconds.

[0217] The PVA mask and PET film were peeled off from the obtained laminate to obtain the anisotropic optical film 1 of Example 1.

[0218] It should be noted that the surface of the anisotropic optical film 1 obtained by observing the cross section perpendicular to the column axis of the column region with an optical microscope, the minor axis and major axis of each of the 20 randomly selected column regions are measured, the average minor axis and the average major axis are calculated, and the ratio of the average major axis to the average minor axis (average major axis / average minor axis), i.e., the aspect ratio, is calculated, and the result is 1.

[0219] [Example 2]

[0220] The amount of component (A-1) was changed to 3 parts by weight and the amount of component (B) was changed to 97 parts by weight. Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film 2 of Example 2.

[0221] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using the same method as in Example 1, and the result was 21 mPa·s (25°C).

[0222] Furthermore, the aspect ratio of the obtained anisotropic optical film 2 was calculated using the same method as in Example 1, and the result was 1.

[0223] [Example 3]

[0224] The amount of component (A-1) was changed to 50 parts by weight, and the amount of component (B) was changed to 50 parts by weight. Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film 3 of Example 3.

[0225] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using the same method as in Example 1, and the result was 9000 mPa·s (25°C).

[0226] Furthermore, the aspect ratio of the obtained anisotropic optical film 3 was calculated using the same method as in Example 1, and the result was 1.

[0227] [Example 4]

[0228] In the formulation of Example 1, component (A-2) was changed to ethoxylated o-phenylphenol acrylate (refractive index: 1.58 (25°C), viscosity: 130 mPa·s (25°C)). Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film 4 of Example 4.

[0229] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using the same method as in Example 1, and the result was 225 mPa·s (25°C).

[0230] In addition, the aspect ratio of the obtained anisotropic optical film 4 was calculated using the same method as in Example 1, and the result was 1.

[0231] [Example 5]

[0232] In the formulation of Example 1, component (A-2) was changed to 2-hydroxy-3-phenoxypropyl acrylate (refractive index: 1.52 (25°C), viscosity: 170 mPa·s (25°C)). Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film 5 of Example 5.

[0233] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using the same method as in Example 1, and the result was 450 mPa·s (25°C).

[0234] Furthermore, the aspect ratio of the obtained anisotropic optical film 5 was calculated using the same method as in Example 1, and the result was 1.

[0235] [Example 6]

[0236] In the formulation of Example 1, component (A-2) was changed to modified bisphenol A dimethacrylate (refractive index: 1.54 (25°C), viscosity: 600 mPa·s (25°C)). Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film 6 of Example 6.

[0237] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using the same method as in Example 1, and the result was 1800 mPa·s (25°C).

[0238] Furthermore, the aspect ratio of the obtained anisotropic optical film 6 was calculated using the same method as in Example 1, and the result was 1.

[0239] [Comparative Example 1]

[0240] The amount of component (A-1) was 100 parts by weight, and the material that became component (A-2) was not used. Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film a of Comparative Example 1.

[0241] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using the same method as in Example 1, and the result was 100,000 mPa·s (25°C).

[0242] In addition, the aspect ratio of the obtained anisotropic optical film a was calculated using the same method as in Example 1, and the result was 1.

[0243] [Comparative Example 2]

[0244] The material that would become component (A-1) was not used, and the material that would become component (A-2) was changed to 100 parts by weight. Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film b of Comparative Example 2.

[0245] In addition, the aspect ratio of the obtained anisotropic optical film b was calculated using the same method as in Example 1, and the result was 1.

[0246] [Comparative Example 3]

[0247] Instead of using the material that forms component (A-1), component (A-2) was replaced with 100 parts by weight of modified bisphenol A diacrylate (refractive index: 1.53 (25°C), viscosity: 1100 mPa·s (25°C)). Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film c of Comparative Example 3.

[0248] In addition, the aspect ratio of the obtained anisotropic optical film c was calculated using the same method as in Example 1, and the result was 1.

[0249] [Comparative Example 4]

[0250] In the formulation of Example 1, component (A-2) was changed to dipentaerythritol hexaacrylate (refractive index: 1.49 (25°C), viscosity: 6000 mPa·s (25°C)). Otherwise, the same method as in Example 1 was used to obtain the anisotropic optical film d of Comparative Example 4.

[0251] Here, the viscosity of component (A) as a whole, which is both component (A-1) and component (A-2), was measured using the same method as in Example 1, and the result was 7200 mPa·s (25°C).

[0252] In addition, the aspect ratio of the obtained anisotropic optical film d was calculated using the same method as in Example 1, and the result was 1.

[0253] Table 1 summarizes the “types and proportions” of components (A-1), (A-2) and (B) of the anisotropic optical film compositions of the above embodiments and comparative examples.

[0254] [Table 1]

[0255]

[0256] (Evaluation Method)

[0257] The anisotropic optical films of the embodiments and comparative examples of the present invention manufactured as described above are evaluated as follows.

[0258] [Evaluation of diffusion performance]

[0259] Use such as Figure 5The variable-angle photometer goniometer (manufactured by Genesia) shown, capable of arbitrarily changing the projection angle of the light source and the receiving angle of the detector, was used to evaluate the diffusion performance of the anisotropic optical films in the examples and comparative examples. Figure 5 As shown, the anisotropic optical films of the embodiments and comparative examples are disposed between the light source and the detector (here, the light source and the anisotropic optical film are fixed in advance so that light is incident from the normal direction of the anisotropic optical film). In this evaluation, the case where light is detected in the direction of light propagation (the direction perpendicular to the anisotropic optical film) is set as a detection angle of 0°, and the detector is disposed in a manner that allows it to rotate in any direction while maintaining a constant distance from the anisotropic optical film.

[0260] Next, the detector is continuously rotated in 1° increments within a range of -75° to 75° in the coating direction based on the applicator, and the amount of light transmitted through the sample at each detection angle (scattered transmitted light) is measured. It should be noted that the scattered transmitted light is measured by determining the wavelength in the visible light region using a visibility filter. Then, the ratio of the scattered transmitted light to the amount of light directly illuminating the detector from the light source at a detection angle of 0° without passing through the anisotropic optical film (incident light, incident light) is taken as the scattered transmittance (%).

[0261] The results of the above measurements are used to generate a graph showing the relationship between the detection angle and the amount of scattered transmitted light. In this graph, the range of detection angles that satisfy "scattered transmittance (%) > 0.1%" is taken as the "diffusion width".

[0262] [Evaluation of Hue]

[0263] The Lo of the anisotropic optical films in the examples and comparative examples was measured using a spectrophotometer (Shimadzu Corporation, UV-2450). * a * b * (CIE1976).

[0264] [Evaluation Criteria]

[0265] The evaluation criteria for each evaluation in the embodiments of the present invention are as follows.

[0266] "Diffusion width"

[0267] ◎: Excellent diffusion properties, above 40°

[0268] 〇: Excellent diffusion properties, above 32° and below 40°

[0269] ×: Insufficient diffusivity less than 32°

[0270] "Hue b*"

[0271] ◎: Excellent -2.00 to +2.00

[0272] 〇: Excellent -7.00 or higher and less than -2.00 or higher than +2.00 and less than +7.00

[0273] ×: Insufficiently less than -7.00 or more than +7.00

[0274] The evaluation results of the anisotropic optical films of the embodiments and comparative examples of the present invention are shown in Table 2.

[0275] [Table 2]

[0276]

[0277] As confirmed by Examples 1 to 5 in Table 2, the anisotropic optical film of the present invention is an anisotropic optical film with excellent hue in addition to having good diffusion properties with a wide diffusion width.

[0278] In particular, in Examples 1 and 4, an acrylate having multiple aromatic rings in one molecule was used as component (A-2), and thus the combination of components (A-1) and (A-2) was optimal, resulting in particularly excellent evaluation results in the examples.

[0279] The materials used in Examples 2 and 3 are the same as those in Example 1, but the anisotropic optical films are made by changing the proportions of components (A-1) and (A-2), respectively.

[0280] Example 2 yields an anisotropic optical film with excellent diffusion and excellent hue, and Example 3 yields an anisotropic optical film with excellent diffusion and excellent hue.

[0281] Here, the reason why the hue of Example 2 is slightly worse than that of Example 1 can be attributed to the fact that there is more (A-2) component compared to Example 1, which causes the color to appear due to the π-π stacking interaction between the aromatic rings from (A-2) component.

[0282] Furthermore, it is believed that the slightly poorer diffusivity of Example 3 compared to Example 1 is due to the fact that (A-2) contains less component than Example 1, which reduces the fluidity of the anisotropic optical film composition. As a result, during curing, the phase separation between the matrix region and the multiple columnar regions inside the anisotropic optical film cannot be fully achieved.

[0283] Example 5 is an anisotropic optical film prepared using an acrylate having an aromatic ring in one molecule as component (A-2), which can produce an anisotropic optical film with excellent diffusion and very good hue.

[0284] Here, it is believed that the reason why the diffusion of Example 5 is slightly worse than that of Examples 1 and 4 is that, compared with Examples 1 and 4, the refractive index of the (A-2) component is not high enough, and the refractive index difference between the matrix region and the multiple columnar regions inside the anisotropic optical film is reduced.

[0285] Example 6 is an anisotropic optical film prepared using methacrylate with two aromatic rings in one molecule as component (A-2), which can produce an anisotropic optical film with excellent diffusion and very good hue.

[0286] Here, it is believed that the reason why the diffusion of Example 6 is slightly worse than that of Examples 1 and 4 is that, compared with Examples 1 and 4, the refractive index of the (A-2) component is not high enough, and the refractive index difference between the matrix region and the multiple columnar regions inside the anisotropic optical film is reduced.

[0287] Comparative Example 1, an anisotropic optical film produced without using the material that is component (A-2), confirmed that the diffusion of this anisotropic optical film was insufficient. This is believed to be because, since the (A-2) component is absent, the flowability of the composition for the anisotropic optical film is significantly deteriorated, and during curing, phase separation occurring between the matrix region and the multiple columnar regions within the anisotropic optical film hardly occurs.

[0288] Comparative Example 2 is an anisotropic optical film made without using a material that is (A-1) composition. It was confirmed that although the anisotropic optical film has excellent diffusion properties, its hue is insufficient.

[0289] Here, the reason for the significant deterioration in hue compared to Example 1 can be attributed to the absence of component (A-1), which resulted in a strong color development caused by the π-π stacking interaction between the aromatic rings from component (A-2).

[0290] Furthermore, it is believed that the slightly worse diffusion compared to Example 1 is due to the fact that since it does not contain the (A-1) component, the overall refractive index of the (A) component is lower, and the refractive index difference between the matrix region and the multiple columnar regions inside the anisotropic optical film is reduced.

[0291] Comparative Example 3 is an anisotropic optical film made without using the material that is component (A-1) and instead using a difunctional acrylate as component (A-2). It was confirmed that although the anisotropic optical film has a very good hue, its diffusion is insufficient.

[0292] This is believed to be because by using a difunctional acrylate as component (A-2), the overlap of aromatic rings becomes difficult to occur. Even without component (A-1), the color development caused by π-π stacking interaction can be suppressed. However, the overall refractive index of component (A) is not high enough, and the refractive index difference between the matrix region and multiple columnar regions inside the anisotropic optical film is reduced.

[0293] Comparative Example 4 is an anisotropic optical film prepared using a hexafunctional acrylate as component (A-2). It was confirmed that while this anisotropic optical film possessed excellent hue, its diffusion was insufficient. This is believed to be because the refractive index of component (A-2) was not high enough, reducing the refractive index difference between the matrix region and the multiple columnar regions within the anisotropic optical film. Furthermore, the viscosity of component (A-2) was not low enough, thus reducing the fluidity of the composition for the anisotropic optical film. During curing, phase separation between the matrix region and the multiple columnar regions within the anisotropic optical film could not proceed sufficiently.

[0294] The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above-described embodiments. That is, other embodiments or various modifications that can be conceived by those skilled in the art within the scope of the invention as described in the claims are also understood to fall within the technical scope of the present invention.

[0295] Symbol Explanation

[0296] 1: Uncured resin composition layer

[0297] 10: Light source

[0298] 11, 12: Directional diffusion elements,

[0299] LA: Major axis,

[0300] SA: Short diameter,

[0301] A: Parallel light rays,

[0302] B1, B2: Directional light.

Claims

1. A composition for anisotropic optical films, characterized in that, Include: (A-1) methacrylates having a fluorene backbone and one or more (meth)acryloyl groups; (A-2) methacrylates having one or two aromatic rings and one or more (meth)acryloyl groups and lacking a fluorene skeleton. Component (B) is a thermoplastic polymer with a weight-average molecular weight of 1,000 to 500,000, a glass transition temperature of -40°C or higher, and a refractive index of 1.35 to 1.

50. As a photopolymerization initiator for component (C); When the content of component (A-2) is set to 100 parts by weight, the content of component (A-1) in the composition is 3 parts by weight to 100 parts by weight. When the total content of (meth)acrylates containing components (A-1) and (A-2) is set to 100 parts by weight, the content of component (B) in the composition is 10 parts by weight to 400 parts by weight.

2. The anisotropic optical film composition according to claim 1, characterized in that, The (A-1) component has two or more aromatic rings as substituents for the fluorene skeleton in one molecule.

3. The anisotropic optical film composition according to claim 1 or 2, characterized in that, The refractive index of the (A-1) component is 1.55~1.

70.

4. The anisotropic optical film composition according to claim 1 or 2, characterized in that, The (A-1) component has multiple (meth)acryloyl groups.

5. The anisotropic optical film composition according to claim 1 or 2, characterized in that, The (A-2) component has two aromatic rings in one molecule.

6. The anisotropic optical film composition according to claim 1 or 2, characterized in that, The refractive index of the (A-2) component is 1.50~1.

65.

7. The anisotropic optical film composition according to claim 5, characterized in that, The (A-2) component has a biphenyl structure and / or a diphenyl ether structure.

8. An anisotropic optical film, which is a cured product of the anisotropic optical film composition according to any one of claims 1 to 7, characterized in that, The anisotropic optical film has a substrate region and multiple columnar regions with a refractive index different from that of the substrate region.

9. The anisotropic optical film according to claim 8, characterized in that, The plurality of columnar regions of the anisotropic optical film are configured to be oriented and extend from one surface of the anisotropic optical film to another surface. The average major axis / average minor axis of the columnar region in the cross section perpendicular to the columnar axis of the anisotropic optical film, i.e., the aspect ratio of the columnar region, is 1~50.

10. The anisotropic optical film according to claim 8 or 9, characterized in that, The thickness of the anisotropic optical film is 10 μm to 100 μm.

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