TWI834802B - Optical films, polarizing plates and image display devices - Google Patents

Abstract

An optical film, which is an optical film including a resin layer A. The resin layer A is formed of resin A. The resin A contains more than 50% by weight of an alicyclic structure-containing polymer and an ultraviolet absorber. The optical film has a wavelength of 300 The transmittance of light above 410 nm and below 410 nm is below 10%, the transmittance of light at wavelength 430 nm is above 80%, the increase rate of transmittance of light above wavelength 410 nm and below 420 nm is 4.0% /nm or above.

Description

Optical films, polarizing plates and image display devices

The present invention relates to optical films, polarizing plates and image display devices.

Image display devices sometimes include circular polarizers for reducing reflection of external light. Image display devices may be used outdoors and other environments where ultraviolet intensity is high. Therefore, in order to protect the polarizer from ultraviolet rays, the image display device may be equipped with an optical film containing an ultraviolet absorber (Patent Document 1).

"Patent documents" "Patent Document 1": Japanese Patent Publication No. 2017-187619

In order to reduce the impact on the color of the displayed image, the optical film included in the image display device preferably has a high light transmittance in the visible light region. For example, if the absorption loss of the light transmittance of light in the visible light region is large, the light absorption of a specific wavelength in the visible light region will become larger, and sometimes the screen will become colored when the screen is set to a white display state. image.

On the other hand, when a retardation film such as a λ/4 plate is used in a circular polarizing plate of an image display device, the image display is observed from the front direction based on the wavelength dispersion of the retardation Re of the retardation film in the in-plane direction. The hue when installed may deviate from the original color. For example, when the retardation Re in the in-plane direction of the retardation film is along the wavelength dispersion, the light of the wavelength in the purple to blue region reflected by the reflective electrode of the image display device is transmitted through It is visible due to the polarizer, so if the screen is set to a black display state, the screen may sometimes appear bluish. Here, the term "retardation in the in-plane direction has along-wavelength dispersion" means that the retardation Re (450) in the in-plane direction with a wavelength of 450 nm and the retardation Re (550) in the in-plane direction with a wavelength of 550 nm satisfy the following formulas . Re(450)／Re(550)≧1

Therefore, there is a demand for an optical film that "can protect the image display device from ultraviolet rays while improving the hue when the image display device is viewed from the front direction." A polarizing plate with "hue when viewed from the front" of an image display device, and an image display device with "improved hue when viewed from the front".

The inventors of the present invention have devoted themselves to research in order to solve the aforementioned problems. As a result, it was found that the transmittance of light with a wavelength of 300 nm or more and 410 nm or less is 10% or less, the light transmittance with a wavelength of 430 nm is more than 80%, and the light with a wavelength of 410 nm or more and 420 nm or less An optical film with an increase rate of transmittance of 4.0%/nm or more can solve the aforementioned problems, thereby completing the present invention.

That is, the present invention provides the following.

[1] An optical film including a resin layer A, The aforementioned resin layer A is formed of resin A. The aforementioned resin A contains more than 50% by weight of a polymer containing an alicyclic structure and an ultraviolet absorber. The aforementioned optical film has a light transmittance of 10% at wavelengths above 300 nm and below 410 nm. Below, the light transmittance at wavelength 430 nm is more than 80%, and the increase rate of light transmittance at wavelengths above 410 nm and below 420 nm is more than 4.0%/nm.

[2] The optical film according to [1], further comprising a resin layer B1 and a resin layer B2, The aforementioned resin layer B1 is provided on one side of the aforementioned resin layer A, and the aforementioned resin layer B2 is provided on the other side of the aforementioned resin layer A. The aforementioned resin layer B1 is made of thermoplastic material with an ultraviolet absorber content of 3.0% by weight or less. The resin layer B2 is formed of the thermoplastic resin B2 with an ultraviolet absorber content of 3.0% by weight or less.

[3] The optical film according to [2], which is a co-extruded film.

[4] The optical film according to any one of [1] to [3], wherein the ultraviolet absorber contains a compound containing a sesamol structure and a benzotriazole structure.

[5] The optical film according to any one of [1] to [4], wherein the retardation Re(590) in the in-plane direction with a wavelength of 590 nm is 0.1 nm or more.

[6] A polarizing plate including the optical film and polarizer described in any one of [1] to [5].

[7] The polarizing plate according to [6], further including a retardation layer C having a retardation Re(590) of 70 nm or more in the in-plane direction at a wavelength of 590 nm.

[8] An image display device including the polarizing plate described in [6] or [7].

This disclosure also includes the following.

[9] A method for manufacturing an optical film, which is the method for manufacturing an optical film as described in [3], including: The aforementioned thermoplastic resin B1, the aforementioned resin A and the aforementioned thermoplastic resin B2 are co-extruded from a mold to obtain an extrusion in which a layer of the aforementioned thermoplastic resin B1, a layer of the aforementioned resin A and a layer of the aforementioned thermoplastic resin B2 are stacked in sequence. film process.

According to the present invention, it is possible to provide an optical film that "can protect an image display device from ultraviolet rays while improving the hue when the image display device is viewed from the front direction." "It can protect an image display device from ultraviolet rays while improving its hue. A polarizing plate whose hue is improved when the image display device is viewed from the front, and an image display device whose hue is improved when viewed from the front.

Embodiments and examples are disclosed below to explain the present invention in detail. However, the present invention is not limited to the embodiments and examples disclosed below, and may be arbitrarily modified and implemented without departing from the patentable scope of the present invention and its equivalent scope. In addition, the same components as those already described may be given the same symbols and their descriptions may be omitted.

In the following description, the so-called front direction of the image display device, unless otherwise noted, means the normal direction of the picture of the image display device. Specifically, it refers to the direction of the aforementioned picture with a polar angle of 0° and an azimuth angle of 0°. .

In the following description, the hue when the image display device is viewed from the front direction may be simply referred to as the "front hue". Improving the frontal hue means making the bluish black display state or the yellowish white display state when the image display device is viewed from the front direction, close to the intended original black display state or white display state. .

In the following description, the term “board” includes not only rigid members but also flexible members such as resin films, unless otherwise noted.

In the following description, the so-called slow axis of a film or layer means the in-plane slow axis of the film or layer, unless otherwise noted.

In the following description, the angle between the optical axes (slow axis, transmission axis, absorption axis, etc.) of each layer in a component having multiple layers means that the aforementioned layer is viewed from the thickness direction unless otherwise noted. body time angle.

In the following description, "circular polarizing plate" includes not only circular polarizing plates in a narrow sense, but also elliptical polarizing plates.

In the following description, the so-called "long strip" film refers to a film having a length of 5 times or more relative to the width, preferably 10 times or more. Specifically, it means a film with a length that can be rolled up. Film of sufficient length to be stored or transported in roll form. The upper limit of the length of the film is not particularly limited, but may be, for example, 100,000 times or less relative to the width.

In the following description, the retardation Re of a layer in the in-plane direction is a value represented by Re=(nx-ny)×d, unless otherwise noted. In addition, the retardation Rth in the thickness direction of the layer is a value represented by Rth={[(nx+ny)/2]-nz}×d, unless otherwise noted. Here, nx represents the refractive index in the direction perpendicular to the thickness direction of the layer (in-plane direction) and in the direction giving the maximum refractive index. ny represents the refractive index in the direction in the aforementioned in-plane direction of the layer and orthogonal to the direction of nx. nz represents the refractive index in the thickness direction of the layer. d represents the thickness of the layer. Measurement wavelength, unless otherwise noted, is 590 nm.

In the following description, the so-called directions of components are "parallel", "perpendicular" and "orthogonal". Unless otherwise noted, within the scope that does not impair the effect of the present invention, they may also include, for example, ±3°, ± Error within 2° or ±1°.

[1. Optical film]

An optical film according to an embodiment of the present invention includes a resin layer A.

The resin layer A is formed of resin A. The resin A that is the material of the resin layer A contains an alicyclic structure-containing polymer (50% by weight or more relative to the resin A) and an ultraviolet absorber.

In addition, the optical film has a light transmittance of less than 10% at wavelengths above 300 nm and below 410 nm, more than 80% at wavelengths of 430 nm, and less than 80% at wavelengths above 410 nm and below 420 nm. The increase rate of transmittance is above 4.0%/nm.

[1.1. Resin A]

Resin A contains an alicyclic structure-containing polymer. Here, the so-called alicyclic structure-containing polymer refers to a polymer in which the structural unit of the polymer has an alicyclic structure. Resins containing such alicyclic structure-containing polymers generally have excellent properties such as transparency, dimensional stability, retardation development, and low-temperature elongation.

The polymer containing an alicyclic structure can be made into a polymer having an alicyclic structure in the main chain, a polymer having an alicyclic structure in the side chain, a polymer having an alicyclic structure in the main chain and side chains, or two of these. A mixture of any of the above. Among them, from the viewpoint of mechanical strength and heat resistance, a polymer having an alicyclic structure in the main chain is preferred.

Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkenes, cycloalkynes) structures. Among them, from the viewpoint of mechanical strength and heat resistance, the cycloalkane structure and the cycloolefin structure are preferred, and the cycloalkane structure is particularly preferred.

The number of carbon atoms constituting the alicyclic structure is preferably more than 4, preferably more than 5, and preferably less than 30, preferably less than 20, and less than 15 per alicyclic structure. Excellent. If the number of carbon atoms constituting the alicyclic structure is within this range, the mechanical strength, heat resistance and formability of resin A can be highly balanced.

In the polymer containing an alicyclic structure, the proportion of structural units having an alicyclic structure can be selected according to the purpose of the optical film. The proportion of structural units having an alicyclic structure in the alicyclic structure-containing polymer is preferably 55% by weight or more, more preferably 70% by weight or more, particularly preferably 90% by weight or more, and is usually determined as 100% by weight or less. If the ratio of the structural unit having an alicyclic structure in the alicyclic structure-containing polymer is within this range, the transparency and heat resistance of the resin A will be improved.

Among polymers containing alicyclic structures, cycloolefin polymers are preferred. The cycloolefin polymer is a polymer having a structure obtained by polymerizing a cycloolefin monomer. The cycloolefin monosystem "has a ring structure formed of carbon atoms, and has a polymerizable carbon-carbon double bond in the ring structure." Examples of polymerizable carbon-carbon double bonds include carbon-carbon double bonds capable of polymerization such as ring-opening polymerization. Examples of the ring structure of the cycloolefin monomer include a monocyclic ring, a polycyclic ring, a condensed ring, a bridged ring, a polycyclic ring in which these are combined, and the like. Among these, polycyclic cycloolefin monomers are preferred from the viewpoint of achieving a high balance between the dielectric properties and heat resistance of the obtained polymer.

Preferable ones among the above-mentioned cycloolefin polymers include norphene polymers, monocyclic cycloolefin polymers, cyclic conjugated diene polymers, and hydrogenated products thereof. Among these, nordecene-based polymers are particularly suitable because they have good formability.

Examples of the norphene-based polymer include ring-opened polymers of monomers having a norphene structure and hydrogenated products thereof, and addition polymers and hydrogenates of monomers having a norphene structure. Furthermore, examples of ring-opened polymers of monomers having a norbicene structure include ring-opened homopolymers of one monomer having a norbicene structure, and two or more monomers having a norbicene structure. Ring-opening copolymers of monomers, as well as ring-opening copolymers of monomers with a norvinyl structure and other monomers that can be copolymerized with them. Furthermore, examples of addition polymers of monomers having a norbicene structure include: addition homopolymers of one monomer having a norbicene structure, and addition homopolymers of two or more monomers having a norbicene structure. Addition copolymers of monomers, as well as monomers with a norvinyl structure and other monomers that can be copolymerized with them. Among these, the hydrogenated product of a ring-opened polymer of a monomer having a norvinyl structure is particularly suitable from the viewpoints of formability, heat resistance, low moisture absorption, dimensional stability, lightweight, and the like.

Examples of monomers having a norphene structure include: bicyclo[2.2.1]hept-2-ene (common name: norphene), tricyclo[4.3.0.1 ^2,5 ]dec-3,7- Diene (common name: dicyclopentadiene), 7,8-benzotricyclo[4.3.0.1 ^2,5 ]dec-3-ene (common name: dicyclopentadiene), tetracyclo[4.4.0.1 ^2,5 .1 ^7,10 ] Dodec-3-ene (common name: tetracyclododecene) and derivatives of these compounds (such as those with substituents on the ring). Here, examples of the substituent include an alkyl group, an alkylene group and a polar group. Moreover, these substituents may also have multiple identical or different ones bonded to the ring. One type of monomer having a norvinyl structure may be used alone, or two or more types may be used in combination at any ratio.

Examples of polar groups include heteroatoms and atomic groups containing heteroatoms. Examples of heteroatoms include oxygen atoms, nitrogen atoms, sulfur atoms, silicon atoms and halogen atoms. Specific examples of the polar group include carboxyl group, carbonyloxycarbonyl group, epoxy group, hydroxyl group, oxy group, ester group, silyl alcohol group, silicon group, amine group, amide group, amide imino group, and nitroyl group. and sulfonic acid group. As the polymer constituting the resin A, either those containing such a polar group or those not containing such a polar group can be used suitably.

Examples of monomers capable of ring-opening copolymerization with monomers having a norvinyl structure include: monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and their derivatives; cyclohexadiene, Cycloheptadiene and other cyclic conjugated dienes and their derivatives. The monomer capable of ring-opening copolymerization with the monomer having a norvinyl structure may be used alone, or two or more may be used in combination at any ratio.

A ring-opening polymer of a monomer having a norvinyl structure can be produced, for example, by polymerizing or copolymerizing the monomer in the presence of a ring-opening polymerization catalyst.

Examples of monomers that can be added and copolymerized with monomers having a norvinyl structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and their derivatives; Cyclic alkenes such as cyclobutene, cyclopentene, cyclohexene and their derivatives; and 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1, Non-conjugated dienes such as 4-hexadiene. Among these, α-olefin is preferred, and ethylene is preferred. Furthermore, one type of monomer capable of addition copolymerization with a monomer having a norvinyl structure may be used alone, or two or more types may be used in combination at any ratio.

An addition polymer of a monomer having a norvinyl structure can be produced, for example, by polymerizing or copolymerizing the monomer in the presence of an addition polymerization catalyst.

The hydrides of the above-mentioned ring-opening polymers and addition polymers can be obtained, for example, by adding a solution of these ring-opening polymers and addition polymers to a solution containing transition metals such as nickel and palladium. It is produced by hydrogenating the carbon-carbon double bond - preferably more than 90% - in the presence of a hydrogenation catalyst.

Examples of monocyclic cycloolefin-based polymers include addition polymers of cycloolefin-based monomers having a monocyclic ring, such as cyclohexene, cycloheptene, and cyclooctene.

Examples of cyclic conjugated diene polymers include those obtained by cyclizing addition polymers of conjugated diene monomers such as 1,3-butadiene, isoprene, chlorine, etc. Polymers; 1,2- or 1,4-addition polymers of cyclic conjugated diene monomers such as cyclopentadiene and cyclohexadiene; and hydrogenated products of these.

As the alicyclic structure-containing polymer and the resin containing the same, commercially available resins can be used. Examples of commercially available resins include Zeonor (manufactured by Nippon Zeon Co., Ltd.), ARTON (manufactured by JSR Co., Ltd.), TOPAS (manufactured by POLYPLASTICS CO., LTD.), and APEL (manufactured by Mitsui Chemicals Co., Ltd.).

The content of the alicyclic structure-containing polymer in resin A is usually 50% by weight or more, preferably 70% by weight or more, preferably 80% by weight or more, and usually 100% by weight or less. When the content of the alicyclic structure-containing polymer in the resin A is more than the aforementioned lower limit, the resin A can possess the excellent characteristics of the alicyclic structure-containing polymer.

Resin A may contain only one type of alicyclic structure-containing polymer, or may contain two or more types of alicyclic structure-containing polymers in combination at any ratio.

[1.2. Ultraviolet absorber]

Resin A contains a UV absorber. The so-called ultraviolet absorber refers to an agent that has more than one absorption maximum value at a wavelength of 250 nm or more and 400 nm or less in the light absorption spectrum. Here, the "agent" may be composed of one substance or a composition composed of two or more substances. In addition to having an absorption maximum value below a wavelength of 400 nm, the ultraviolet absorber may also have an absorption maximum value in a range beyond the wavelength of 400 nm. Resin A may contain only one type of ultraviolet absorber, or may contain two or more types of ultraviolet absorbers in combination at any ratio.

As the ultraviolet absorber, it is preferable to use an agent that has a maximum absorption maximum value at a wavelength of 400 nm or less in the light absorption spectrum between a wavelength of 250 nm or more and a wavelength of 450 nm or less. In this way, the optical film can effectively absorb ultraviolet rays and protect components of image display devices such as polarizers from ultraviolet rays.

The light absorption spectrum of the ultraviolet absorber must be measured using an ultraviolet-visible light spectrometer (for example: "UV-2450" manufactured by Shimadzu Corporation). Wavelength: 250 nm ~ 450 nm, solvent: chloroform or methanol, concentration: 10 ppm, Groove: Measured according to the conditions of a quartz groove with an optical path length of 1 cm.

As the ultraviolet absorber, it is preferable to use an ultraviolet absorber that has a wavelength range of 350 nm or more and 400 nm or less, which exhibits maximum absorbance in the light absorption spectrum with a wavelength of 250 nm or more and 450 nm or less. Hereinafter, "a specific ultraviolet absorber whose wavelength exhibits the maximum absorbance of light in the light absorption spectrum between 250 nm and above and 450 nm and below is in the range of 350 nm and 400 nm" may be referred to as ultraviolet absorber U1. By using ultraviolet absorbers whose wavelengths exhibit maximum absorbance within the aforementioned range, the transmittance of light in optical films with wavelengths above 300 nm and below 410 nm can be effectively reduced. As a result, the amount of light emitted from the image display device with a wavelength above 300 nm and below 410 nm can be effectively suppressed, and the hue when the image display device is viewed from the front can be effectively improved.

As the ultraviolet absorber U1, an ultraviolet absorber containing a compound containing a sesamol structure and a benzotriazole structure can be used. Examples of compounds containing a sesamol structure and a benzotriazole structure include compound I represented by the following general formula (1), with compound I being preferred.

"Chemical 1" (1)

In the aforementioned general formula (1), R ¹ represents a hydrogen atom, a halogen atom, a (C1-C8) alkyl group, a (C1-C8) alkoxy group, a hydroxyl group, an amino group, or a straight or branched chain having 1 to 4 carbon atoms. Monosubstituted amino group, linear or branched disubstituted amino group with 1 to 4 carbon atoms, nitro group, carboxyl group, (C1～C8) alkoxycarbonyl group, hydroxyl (C1～C8) alkyl group, (C1～C8) Alkylcarbonyloxy (C1～C8) alkyl, carboxy (C1～C3) alkyl, (Cx) alkoxycarbonyl (Cy) alkyl, aryl, acyl, sulfo or cyano. Here, the description of (Cm~Cn) before "alkyl" means that the number of carbon atoms in the alkyl group is m or more and n or less, and the description of (Cm) before "alkyl" means that The alkyl group has m carbon atoms. x and y are each an integer of 1 or more, and x+y is 2 or more and 10 or less.

R ¹ is preferably a hydrogen atom or (Cx)alkylcarbonyl (Cy)oxyalkyl group.

As specific examples of compound I, there can be cited compounds listed in Japanese Patent No. 5416171. Compound I can be produced by the method described in Japanese Patent No. 5416171.

The content of the compound containing sesamol structure and benzotriazole structure in the ultraviolet absorber is preferably more than 50% by weight, more preferably more than 70% by weight, more preferably more than 90% by weight, and it is obtained Set to 100% by weight or less.

The content of the ultraviolet absorber in resin A is preferably 2.0% by weight or more, more preferably 4.0% by weight or more, more preferably 6.0% by weight or less, and preferably less than 30% by weight, and 25% by weight or less. % or less is preferred, and 20% by weight or less is more preferred. By making the content of the ultraviolet absorber in the resin A fall within the aforementioned range, the ultraviolet absorber can be inhibited from bleeding from the resin layer A, while the image display device can be effectively protected from ultraviolet rays, further improving the front hue of the image display device.

[1.3. Any components contained in resin A]

Resin A may contain any component other than the ultraviolet absorber mentioned above. Examples of such optional components include: antioxidants, light stabilizers, waxes, nucleating agents, fluorescent whitening agents, inorganic fillers, colorants, flame retardants, flame retardant auxiliaries, antistatic agents, Plasticizers, near-infrared absorbers, lubricants, fillers, and any polymer other than polymers containing alicyclic structures, etc. Moreover, as an arbitrary component, one type may be used individually, or two or more types may be combined and used in arbitrary ratios.

[1.4. The optical film may contain any layer]

The optical film may include any layer other than the resin layer A. Examples of such arbitrary layers include a bonding layer, a layer having a phase difference, a hard coat layer, and the like.

[1.5. Characteristics of optical films]

(Light transmittance at wavelengths above 300 nm and below 410 nm)

The light transmittance of optical films at wavelengths above 300 nm and below 410 nm is usually less than 10%. The so-called light transmittance at a wavelength of 300 nm or more and 410 nm or less is 10% or less means that the maximum value of the light transmittance in the wavelength range of 300 nm or more and 410 nm or less is 10% or less. The light transmittance of optical films at wavelengths above 300 nm and below 410 nm is usually below 10%, preferably below 8%, preferably below 5%, ideally 0%, but it must be above 0% Or more than 0.01%.

By having the light transmittance of the optical film at wavelengths above 300 nm and below 410 nm below the aforementioned upper limit, the image display device can be effectively protected from ultraviolet rays and the front hue of the image display device can be further improved. In particular, organic components contained in organic electroluminescent devices (organic EL devices) are particularly susceptible to degradation by long-wavelength ultraviolet rays. Therefore, the deterioration of the organic components contained in the organic EL element can be effectively suppressed and the life of the organic EL display device can be extended.

The light transmittance of optical films can be measured using an ultraviolet, visible, and near-infrared spectrophotometer (such as "V-7200" manufactured by JASCO Corporation).

(Light transmittance at wavelength 430 nm)

The light transmittance of optical films at a wavelength of 430 nm is usually above 80%, preferably above 82%, preferably above 85%, the higher the better, but usually below 100%. By having the light transmittance of the optical film at a wavelength of 430 nm above the aforementioned lower limit, the front hue of the image display device can be improved without significantly affecting the color of the image display device. This effect is particularly significant when the light-emitting elements included in the image display device are organic EL elements. Most of the organic EL elements used in image display devices have luminous intensity that increases sharply from around 430 nm to the longer wavelength side. Therefore, by making the light transmittance of the optical film at a wavelength of 430 nm above the aforementioned lower limit, the light emitted from the organic EL element with a wavelength near 430 nm becomes less likely to be absorbed by the optical film. As a result, the influence on the color of the image display device can be reduced.

(Increase rate of light transmittance at wavelengths above 410 nm and below 420 nm)

The increase rate R of the light transmittance of optical films at wavelengths above 410 nm and below 420 nm is usually above 4.0%/nm, preferably above 4.2%/nm, preferably above 4.5%/nm, and above 4.7 %/nm or above is particularly preferred, and the larger the better, but it must be set below 7.0%/nm.

The increase rate R (%/nm) can be calculated by the following formula. R (%/nm)=(T(420)-T(410))/(420-410)

In the aforementioned formula, T(420) is the light transmittance (%) of the optical film at a wavelength of 420 nm, and T(410) is the light transmittance (%) of the optical film at a wavelength of 410 nm. The unit of the denominator is nm. .

By having the increase rate R of the optical film above the aforementioned lower limit, the optical film can effectively absorb light with a wavelength above 300 nm and below 410 nm, while allowing light with a wavelength of 430 nm to penetrate at a high rate. As a result, the image display device can be effectively protected from ultraviolet rays, and the front hue of the image display device can be further improved without causing a large impact on the color of the image display device.

(In-plane direction retardation of optical films)

The retardation Re(590) of the optical film in the in-plane direction at the wavelength of 590 nm is preferably above 0.1 nm, preferably above 1 nm, preferably above 2 nm, and preferably below 300 nm, and preferably below 270 nm. nm or less is preferred, and 250 nm or less is even more preferred. This allows the optical film to function as a retardation film such as a λ/4 plate.

The in-plane direction retardation of the optical film is preferably along wavelength dispersion. Specifically, Re(450)/Re(550) is preferably 1 or more, and more preferably greater than 1.

When the in-plane direction retardation of the optical film has along-wavelength dispersion, the front hue of the image display device can be improved.

[1.6. Thickness of resin layer A]

The thickness of the resin layer A is preferably 3 μm or more, preferably 5 μm or more, more preferably 7 μm or more, and preferably 50 μm or less, 40 μm or less, preferably 30 μm or less. good. By having the thickness of the resin layer A above the aforementioned lower limit, the image display device can be effectively protected from ultraviolet rays. Furthermore, the front hue of the image display device can be effectively improved without causing a large impact on the color of the image display device. When the thickness of the resin layer A is equal to or less than the upper limit, the optical film including the resin layer A can be made thinner.

[1.7. Optical film of the first embodiment]

The optical film according to the first embodiment is an optical film composed of the resin layer A. The resin layer A is formed of the aforementioned resin A. The optical film of this embodiment must also have the characteristics described in the aforementioned [1.5. Characteristics of Optical Film].

The optical film of this embodiment can be produced by conventionally well-known methods. For example, the optical film can be produced by a melt forming method or a solution casting method, with the melt forming method being preferred. The optical film can also be further processed by stretching, trimming, etc.

[1.8. Optical film of second embodiment]

The optical film related to the second embodiment further includes a resin layer B1 and a resin layer B2 in the resin layer A. The resin layer B1 is provided on one side of the resin layer A, and the resin layer B2 is provided on the other side of the resin layer A. . The resin layer B1 is formed of a thermoplastic resin B1 with an ultraviolet absorber content of 3.0% by weight or less. The resin layer B2 is formed of a thermoplastic resin B2 with an ultraviolet absorber content of 3.0% by weight or less.

FIG. 1 is a schematic cross-sectional view of an optical film related to the second embodiment. As shown in FIG. 1 , the optical film 100 is provided with the resin layer 102 as the resin layer B1 on one surface 101U of the resin layer 101 as the resin layer A so as to be in contact with the resin layer 101 . Furthermore, on the other surface 102D of the resin layer 101, the resin layer 103 as the resin layer B2 is provided in contact with the resin layer 101.

Thermoplastic resin B1 usually contains a thermoplastic polymer. The thermoplastic polymer is not particularly limited, but an alicyclic structure-containing polymer is preferred. As the alicyclic structure-containing polymer, the same polymer as the alicyclic structure-containing polymer contained in the aforementioned resin A can be selected.

The content of the lipid-containing ring structure polymer in the thermoplastic resin B1 is preferably 97.0 wt % or more, more preferably 98.0 wt % or more, and even more preferably 98.5 wt % or more. When the content of the lipid-containing ring structure polymer in the thermoplastic resin B1 is equal to or greater than the above lower limit, the thermoplastic resin B1 can have excellent properties of the lipid-containing ring structure polymer.

The content of the ultraviolet absorber in the thermoplastic resin B1 is usually 3.0% by weight or less, preferably 2.0% by weight or less, preferably 1.5% by weight or less, more preferably 1.0% by weight or less, and substantially 0% by weight. It is especially preferred if it does not contain ultraviolet absorbers. By keeping the ultraviolet absorber content of the thermoplastic resin B1 below the upper limit, the ultraviolet absorber can be suppressed from bleeding onto the surface of the optical film.

The thermoplastic resin B1 contains optional components in addition to the aforementioned polymer. As optional components, the same optional components as those contained in resin A may be used.

The thermoplastic resin B2 usually contains a thermoplastic polymer. The thermoplastic polymer is not particularly limited, but an alicyclic structure-containing polymer is preferred. As the alicyclic structure-containing polymer, the same polymer as the alicyclic structure-containing polymer contained in the aforementioned resin A can be selected.

The content of the alicyclic structure-containing polymer in the thermoplastic resin B2 is preferably 97.0% by weight or more, more preferably 98.0% by weight or more, and more preferably 98.5% by weight or more. When the content of the alicyclic structure-containing polymer in the thermoplastic resin B2 is above the aforementioned lower limit, the thermoplastic resin B2 can possess the excellent characteristics of the alicyclic structure-containing polymer.

The content of the ultraviolet absorber in the thermoplastic resin B2 is usually 3.0% by weight or less, preferably 2.0% by weight or less, preferably 1.5% by weight or less, more preferably 1.0% by weight or less, and substantially 0% by weight. It is especially preferred if it does not contain ultraviolet absorbers. By keeping the ultraviolet absorber content of the thermoplastic resin B2 below the aforementioned upper limit, the ultraviolet absorber can be suppressed from bleeding onto the surface of the optical film.

The thermoplastic resin B2 may contain optional components in addition to the aforementioned polymer. As optional components, the same optional components as those contained in resin A may be used.

The thermoplastic resin B1 and the thermoplastic resin B2 may be different types of resins that contain different polymers, component ratios, physical properties, and the like. However, from the viewpoint of suppressing the curling of the optical film and making the optical film easy to produce, it is preferable that the thermoplastic resin B1 and the thermoplastic resin B2 are the same resin.

The thickness of the resin layer B1 is preferably 1 μm or more, preferably 2 μm or more, 15 μm or less, and 10 μm or less.

The range of the thickness of the resin layer B2 may be set to be the same as the range of the thickness of the resin layer B1. From the viewpoint of suppressing curling of the optical film, it is preferable that the resin layer B1 and the resin layer B2 have the same thickness.

The ratio of the total thickness of the resin layer B1 and the resin layer B2 to the thickness of the resin layer A1 ((B1+B2)/A1) is preferably 1/25 or more, more preferably 1/10 or more, and 1/5 or more. Better, and below 10/1 is better, below 6/1 is better, and below 4/1 is even better.

The optical film of this embodiment must also have the characteristics described in the aforementioned [1.5. Characteristics of Optical Film].

The optical film of this embodiment can be manufactured by conventionally well-known manufacturing methods. For example, the optical film of this embodiment can be manufactured by a melt forming method or a solution casting method.

The optical film of this embodiment is preferably manufactured by a melt forming method, and preferably by a co-extrusion method. Examples of coextrusion methods include coextrusion T-die method, coextrusion blowing method, coextrusion lamination method, and the like. Among them, the co-extrusion T-shaped mold method is the best.

The following describes a method for manufacturing an optical film using the co-extrusion T-die method.

Thermoplastic resin B1, resin A and thermoplastic resin B2 are melted and supplied to a T-shaped mold for co-extrusion. By coextrusion, an extruded film in which a layer of thermoplastic resin B1, a layer of resin A, and a layer of thermoplastic resin B2 are stacked in this order can be obtained. Usually, a long optical film can be obtained by cooling the extruded film on a cooling roller and then winding it up to a winding roller.

The optical film obtained by the aforementioned co-extrusion method can also be further processed by stretching, trimming, etc. as required.

[1.9. Purposes of optical films]

Optical films are suitable for use as components of polarizing plates such as polarizing plate protective films and λ/4 plates. A polarizing plate containing an optical film is suitably used as a polarizing plate attached to an image display device such as a liquid crystal display device or an organic EL display device.

[2.Polarizing plate]

A polarizing plate related to an embodiment of the present invention includes the optical film and polarizing element disclosed above.

[2.1.Polarizer]

Examples of polarizers include: applying dichroism using iodine and dichroic dyes to a film of an appropriate vinyl alcohol-based polymer such as polyvinyl alcohol or partially formalized polyvinyl alcohol in an appropriate order and manner. Films suitable for dyeing, stretching, cross-linking, etc. of materials. Furthermore, other examples of polarizers include polarizers that have the function of separating polarized light into reflected light and transmitted light, such as grid polarizers, multilayer polarizers, and cholesteric liquid crystal polarizers. Among them, a polarizer made of a polyvinyl alcohol resin film containing polyvinyl alcohol is preferred. This type of polarizing element allows linear polarized light to pass through when natural light is incident, especially those with excellent light transmittance and polarization degree are preferred. The thickness of the polarizer is generally 5 μm to 80 μm, but is not limited to this.

[2.2. Optical film]

The optical film included in the polarizing plate is the same as the optical film described in [1. Optical film].

The optical film may be a film whose retardation Re(590) in the in-plane direction at a wavelength of 590 nm is 0.1 nm or more, or a film whose Re(590) is 300 nm or less.

For example, by selecting a film that functions as a λ/4 plate as the optical film, the polarizing plate can function as a circular polarizing plate.

The polarizing element can be disposed on either one side or the other side of the optical film. For example, when the optical film further includes the resin layer B1 and the resin layer B2 in addition to the resin layer A like the optical film related to the second embodiment, the optical film may include the polarizer, the resin layer B1, and the resin layer B2 in this order. The resin layer A and the resin layer B2 may also include a polarizer, the resin layer B2, the resin layer A, and the resin layer B1 in this order.

[2.3. Polarizing plate of third embodiment]

In the polarizing plate related to the third embodiment, an optical film is provided on one surface of the polarizer. FIG. 2 is a schematic cross-sectional view of a polarizing plate related to the third embodiment. As shown in FIG. 2 , the polarizing plate 210 includes an optical film 211 and a polarizing element 214 . An optical film 211 is provided on one surface 214U of the polarizer 214 so as to be in contact with the polarizer 214 .

The optical film 211 is preferably a film that functions as a λ/4 plate.

When the optical film 211 is a film that functions as a λ/4 plate, the angle between the slow axis of the optical film 211 and the transmission axis of the polarizer is preferably 45° or an angle close to it. Specifically, 45°±5° is better, 45°±3° is better, and 45°±1° is better. Thereby, the polarizing plate can function as a circular polarizing plate.

In another embodiment, other layers such as a bonding layer may also be provided between the polarizer and the optical film.

In yet another embodiment, a layer with a phase difference such as a λ/2 plate can also be disposed between the polarizer and the optical film.

[2.4. Polarizing plate of the fourth embodiment]

The polarizing plate related to the fourth embodiment includes an optical film, a polarizer, and a retardation layer C. The retardation Re(590) of the retardation layer C in the in-plane direction with a wavelength of 590 nm is usually 70 nm or more, preferably 80 nm or more, more preferably 90 nm or more, and preferably 300 nm or less. The retardation layer C may be, for example, a layer that functions as a λ/4 plate or a layer that functions as a λ/2 plate.

FIG. 3 is a schematic cross-sectional view of a polarizing plate related to the fourth embodiment. As shown in FIG. 3 , the polarizing plate 220 includes an optical film 221 , a polarizer 224 and a retardation layer 225 serving as the retardation layer C. An optical film 221 is provided on one surface 224U of the polarizer 224 so as to be in contact with the polarizer 224 . On the other surface 224D of the polarizer 224, a phase difference layer 225 is provided in contact with the polarizer 224.

The optical film 221 preferably has a retardation Re(590) in the in-plane direction at a wavelength of 590 nm of 0 nm or a value close to it, specifically less than 10 nm, and less than 5 nm. Thereby, the change in the polarization state of the linearly polarized light passing through the polarizer 224 can be suppressed.

In another embodiment, other layers such as a bonding layer may also be provided between the polarizer and the optical film. And in another embodiment, other layers such as a bonding layer may also be provided between the polarizer and the retardation layer.

[3.Image display device]

An image display device related to an embodiment of the present invention includes the polarizing plate and the image display device disclosed above. As the image display device, any form of image display device may be used. Examples of image display devices include a liquid crystal display device including a liquid crystal cell and an organic EL display device including an organic EL element. The following describes a preferred implementation form of the image display device.

[3.1. Image display device of fifth embodiment]

The image display device of the fifth embodiment includes an optical film, a polarizer and an image display element. FIG. 4 is a schematic cross-sectional view of an image display device related to the fifth embodiment. The image display device 310 related to this embodiment includes a polarizer 214, an optical film 211 and an image display element 316 in sequence. As mentioned above, the optical film 211 preferably functions as a λ/4 plate. Thereby, the polarizing plate 210 including the polarizer 214 and the optical film 211 can suppress the reflection of external light.

The image display device 310 uses the optical film 211 to absorb at least part of the ultraviolet light that passes through the polarizer 214, thereby reducing the amount of ultraviolet light that reaches the image display element 316. Therefore, the life of the image display device 310 can be extended.

Furthermore, the optical film 211 included in the image display device 310 effectively absorbs light with a wavelength of 300 nm or more and 410 nm or less among the light reflected by the image display element 316 . As a result, light with a wavelength of 300 nm or more and 410 nm or less is suppressed from penetrating to the outside from the polarizer 214 and being seen, thereby improving the front hue of the image display device 310 . Furthermore, the optical film 211 is required to transmit light with a wavelength of 430 nm at a high rate. As a result, the front hue of the image display device can be improved without greatly affecting the color of the image display device 310 .

[3.2. Image display device of sixth embodiment]

The image display device of the sixth embodiment includes an optical film, a polarizer, a phase difference layer C and an image display element. FIG. 5 is a schematic cross-sectional view of an image display device related to the sixth embodiment. As shown in FIG. 5 , the image display device 320 related to this embodiment includes an optical film 221 , a polarizer 224 , a phase difference layer 225 as the phase difference layer C, and an image display element 326 in sequence. The optical film 221 provided in the image display device 320 absorbs at least part of the ultraviolet rays from the outside. Thereby, the ultraviolet rays reaching the polarizer 224 can be reduced, and the polarizer 224 can be protected from ultraviolet rays. Moreover, the optical film 221 effectively absorbs light with a wavelength of 300 nm or more and 410 nm or less among the light reflected by the image display element 326 . As a result, the front hue of the image display device 320 can be improved because light with wavelengths above 300 nm and below 410 nm is suppressed from penetrating the retardation layer 225 and further penetrating the polarizer 224 to be seen. Furthermore, the optical film 221 allows light with a wavelength of 430 nm to penetrate at a high rate. As a result, the front hue of the image display device can be improved without greatly affecting the color of the image display device 320 .

"Example"

The following examples are disclosed to specifically illustrate the present invention. However, the present invention is not limited to the embodiments disclosed below, and may be arbitrarily modified and implemented within the scope of the patentable scope of the present invention and its equivalent scope.

In the following description, "%" and "parts" of amounts expressed are based on weight unless otherwise noted. Furthermore, the operations described below are performed under normal temperature and pressure conditions, unless otherwise noted.

[Evaluation method]

(Maximum absorption wavelength of UV absorber)

For the ultraviolet absorber, the light absorption spectrum at wavelengths above 250 nm and below 450 nm was measured under the following conditions. ・Device: Ultraviolet visible light spectrophotometer ("UV-2450" manufactured by Shimadzu Corporation) ・Solvent: chloroform ・Concentration: 10 ppm ・Trough: 1 cm quartz

The maximum absorption wavelength is read from the obtained light absorption spectrum.

(glass transition temperature)

The glass transition temperature of the resin was measured using a differential scanning calorimeter (DSC). The heating rate is set at 10°C/min.

(Light transmittance of the film)

Use an ultraviolet, visible, and near-infrared spectrophotometer ("V-7200" manufactured by Nippon Spectroscopic Co., Ltd.) to measure the light transmittance of optical films at wavelengths of 300 nm to 450 nm. The data collection interval during measurement is set to 1 nm.

From the obtained spectrum, read the maximum light transmittance (%) at a wavelength above 300 nm and below 410 nm, and the light transmittance at a wavelength of 430 nm.

The light transmittance T(420) (%) at the free wavelength of 420 nm and the light transmittance (%) T(410) at the wavelength of 410 nm are calculated by the following formula between the wavelength 410 nm and below 420 nm. The rate of increase of light transmittance R. R (%/nm)=(T(420)-T(410))/(420-410)

(Thickness of resin layer A)

In Examples 1 to 3 and Comparative Examples 1 to 3, the thickness of the film was measured using a contact film thickness meter as the thickness of the resin layer A.

In Examples 4 to 8 and Comparative Example 4, the thickness of the resin layer A was measured by cutting the film in the thickness direction and observing the cross section with an optical microscope.

(Measurement method of in-plane retardation Re(590) of thin films)

The in-plane retardation Re(590) of the film at a wavelength of 590 nm was measured using "AxoScan" manufactured by AXOMETRICS at a measurement wavelength of 590 nm.

(Lightfastness test)

Using the optical films of Examples 1 to 8 and Comparative Examples 1 to 4, a light resistance test using ultraviolet irradiation was performed. The irradiation was performed using a super xenon weather meter (SX75: manufactured by SUGA Testing Machine Co., Ltd.) under the conditions of 72 W/m ² , black panel temperature of 63°C, and humidity of 50% RH. After 300 hours of irradiation, take out the optical film and calculate the maintenance rate of absorbance at a wavelength of 410 nm according to the following formula. Maintenance rate (%) = (A ₁ / A ₀ ) × 100

Here, A ₀ is the absorbance of the optical film at a wavelength of 410 nm before the light resistance test, and A ₁ is the absorbance of the optical film at a wavelength of 410 nm after the light resistance test. A ₀ and A ₁ use the aforementioned ultraviolet visible light and near infrared spectrophotometry. Use a meter ("V-7200" manufactured by Nippon Spectroscopic Co., Ltd.) to measure.

From the obtained value of the absorbance maintenance rate, the light resistance was determined based on the following criteria. A: The absorbance maintenance rate is over 80%. B: The maintenance rate of absorbance does not reach 80%.

(Hue display performance)

The hue display performance was evaluated as follows.

The optical film to be evaluated was bonded to the viewing side of a commercially available organic EL image display device (Galaxy-S, manufactured by Samsung).

The organic EL image display device was placed in a white display state, and the hue was observed from the front direction of the display surface using a viewing angle measurement and evaluation device ("ErgoScope" manufactured by Autronic-MELCHERS). Hue display performance was evaluated based on the following criteria. A: Overall uniformity, no change in hue is seen. B: The whole is almost uniform, and almost no change in hue is seen. C: Changes in hue can be seen on the image.

[Production Example 1, synthesis of compound (a1): 6-(2H-benzotriazol-2-yl)benzene[1,3]dioxer-5-ol]

"Chemical 2" Compound (a1)

Assemble the spherical tube condenser, thermometer, and stirring device into a 200 mL 4-neck flask. Add 15.2 g (0.110 mol) of o-nitroaniline and 25.4 g (0.162 mol) of 62.5% sulfuric acid to dissolve them while stirring. Add 85 mL of water. 21.7 g (0.113 mol) of 36% sodium nitrite aqueous solution was added dropwise at 3 to 7°C, and stirred at the same temperature for 2 hours to obtain 147 g of diazonium salt solution. Assemble the spherical tube condenser, thermometer, and stirring device into a 500 mL 4-neck flask, and add 120 mL of methanol, 4.6 g of sodium hydroxide (0.115 mole), 6.2 g of sodium carbonate (0.058 mole), and 15.2 g of sesamol. (0.110 mol) and mix, add diazonium salt solution dropwise at 3 to 7°C, and stir at the same temperature for 4 hours. The pH was adjusted to 4 with 62.5% sulfuric acid, and the resulting precipitate was filtered, washed with water, and dried to obtain 40.3 g of red crystals. This 40.3 g was repulped and washed with isopropanol aqueous solution to obtain 22.0 g of 6-(2-nitrobenzene azo)benzene[1,3]dioxer-5-ol as red crystals.

Assemble the spherical tube condenser, thermometer, and stirring device into a 300 mL 4-neck flask, and place 22.0 g (0.077 mole) of this red crystal, 100 mL isopropanol, 50 mL water, and 3.7 g (0.093 mole) sodium hydroxide. (ear), hydroquinone 0.2 g, 60% hydrazine hydrate 3.6 g (0.043 mol) and stir at 50-55°C for 1 hour, adjust to pH 7 with 62.5% sulfuric acid, filter, wash and dry the resulting precipitate , 18.4 g of 6-(2H-benzotriazol-2-yl)benzene[1,3]dioxer-5-ol-N-oxide was obtained.

Assemble the spherical tube condenser, thermometer, and stirring device into a 1000 mL 4-neck flask, and add 18.4 g (0.068 mol) of N-oxide, 360 mL of toluene, 120 mL of water, and 8.9 g (0.136 mol) of zinc powder. And mix, maintain 70~75℃, drop 31.9 g (0.203 mol) of 62.5% sulfuric acid over 1 hour, and stir at the same temperature for 1 hour. Leave to stand, separate and remove the water layer in the lower layer, wash with 100 mL of warm water, add 0.6 g of activated carbon, reflux and stir to decolorize. Filtration was performed hot, and 180 mL of toluene was recovered from the filtrate, then cooled to 5°C. The precipitated crystals were filtered, washed with 30 mL of toluene, and dried at 60°C to obtain compound (a1) as yellow crystals (melting point 195°C). ) 9.9 g. The yield of compound (a1) from o-nitroaniline was 35%.

Furthermore, the ultraviolet to visible light absorption spectrum of compound (a1) was measured, and the maximum absorption wavelength was 367 nm, and the absorbance at the wavelength of 367 nm was 20,900.

[Production Example 2, Compound (a2): Synthesis of 6-(5-methylcarbonyloxyethyl-2H-benzotriazol-2-yl)benzene[1,3]dioxer-5-ol]

"Chemical 3" Compound (a2)

Assemble the spherical tube condenser, thermometer, and stirring device into a 200 mL 4-neck flask, and place 6-(5-hydroxyethyl-2H-benzotriazol-2-yl)benzene[1,3]dioxer 2.0 g of -5-ol (0.0067 mole), 50 mL of toluene, 1.6 g of acetic acid (0.0266 mole), and 0.1 g of methanesulfonic acid (0.0010 mole) were refluxed and dehydrated at 110 to 115°C for 4 hours. Wash 3 times with 50 mL of warm water, add 0.1 g of activated carbon, and stir under reflux to decolorize. This was hot-filtered, and the precipitated crystals were filtered, washed with 10 mL of toluene, and dried at 60° C. to obtain 2.2 g of compound (a2). The yield from 6-(5-hydroxyethyl-2H-benzotriazol-2-yl)benzene[1,3]dioxer-5-ol was 96%.

Furthermore, the ultraviolet to visible light absorption spectrum of compound (a2) was measured, and the result was that the maximum absorption wavelength was 368 nm, and the absorbance at the wavelength of 368 nm was 22500.

[Example 1]

(Manufacture of Resin A)

The cycloolefin resin C1 ("Zeonor" manufactured by Nippon Zeon Corporation, glass transition temperature Tg = 126°C) containing 99% by weight or more of a cycloolefin polymer as an alicyclic structure-containing polymer was dried. Using a twin-screw extruder, 92 parts of "dried cycloolefin resin C1" and "the compound (a1) as an ultraviolet absorber produced in the aforementioned Production Example 1 (containing a sesamol structure and a benzotriazole structure) were 8 parts of a compound (a compound in which R ¹ is a hydrogen atom in the aforementioned formula (1)) were mixed to obtain resin A1.

(Manufacture of thin films)

Prepare a single-screw extruder equipped with a gear pump and filter. Resin A1 was put into this single-screw extruder and melted. The melted resin A1 was passed through a gear pump and then through a filter, extruded from a T-die, and passed through a cooling roller to obtain an optical film with a thickness of 20 μm. The obtained optical film was evaluated by the aforementioned method.

[Example 2]

Except for changing the following matters in the production of resin A, the same operation was performed as in Example 1 to obtain an optical film with a thickness of 20 μm and evaluate it.・Change the amount of cycloolefin resin C1 to 94 parts.・Use "Compound (a2) as an ultraviolet absorber produced in the aforementioned Production Example 2 (a compound containing a sesamol structure and a benzotriazole structure, in the aforementioned formula (1) R ¹ is methylcarbonyloxyethyl base compound)" 6 parts, replacing 8 parts of compound (a1).

[Example 3]

Except for changing the following matters in the production of resin A and adjusting the film production conditions, the same operation was performed as in Example 1 to obtain an optical film with a thickness of 15 μm and evaluate it. ・93 parts of "cycloolefin resin C2 (manufactured by JSR Corporation "ARTON") containing 99% by weight or more of a cycloolefin polymer as an alicyclic structure-containing polymer" was used instead of 92 parts of "cycloolefin resin C1". ・Change the amount of compound (a1) to 7 parts.

[Example 4]

The aforementioned cycloolefin resin C1 was prepared as thermoplastic resin B1 and thermoplastic resin B2. As resin A, the aforementioned resin A1 was prepared. Prepare three single-shaft extruders equipped with gear pumps and filters. The aforementioned resin C1, resin A1 and resin C1 were respectively put into three single-screw extruders, melted, passed through a gear pump and then passed through a filter. Subsequently, the above-mentioned melted resin C1, resin A1 and resin C1 are co-extruded from a T-shaped mold with three layers of flow channels, and passed through a cooling roll to obtain a layer having (resin C1/resin A1/resin The optical film with a thickness of 34 μm was evaluated using the layer structure of C1. The thickness of the resin A1 layer is 20 μm.

[Example 5]

Prepare "Using a twin-screw extruder, 98.5 parts of "dried cycloolefin resin C1 as thermoplastic resin B1 and thermoplastic resin B2" and "the compound (a1) as an ultraviolet absorber produced in the aforementioned Production Example 1" A resin obtained by mixing 1.5 parts of a compound in which R ¹ is a hydrogen atom in the aforementioned formula (1). Resin A2 was prepared as resin A in which the following matters were changed in the above-mentioned manufacturing method of resin A1.・Change the amount of cycloolefin resin C1 to 93 parts.・Change the amount of compound (a1) to 7 parts.

Except using these resins and adjusting the film production conditions, the same operation was performed as in Example 4 to obtain an optical film with a thickness of 34 μm and evaluate it. The thickness of the layer of resin A2 is 20 μm.

[Example 6]

Resin A3 was manufactured as resin A by referring to the manufacturing operation of resin A1 mentioned above, except that the following matters were changed. ・Change the amount of cycloolefin resin C1 to 95 parts. ・Change the amount of compound (a1) to 5 parts.

Except using resin A3 instead of resin A1 and adjusting the production conditions of the film, the same operation was carried out as in Example 4 to obtain an optical film with a thickness of 90 μm. The optical film was then stretched using a biaxial stretching device (EX10-B manufactured by Toyo Seiki Seisakusho Co., Ltd.) , an optical film with a thickness of 58 μm was obtained and evaluated. The thickness of the resin A3 layer is 30 μm.

[Example 7]

Resin A4 was manufactured as resin A by referring to the manufacturing operation of resin A1 mentioned above, except that the following matters were changed. ・Change the amount of cycloolefin resin C1 to 89 parts. ・Change the amount of compound (a1) to 11 parts.

Except using resin A4 instead of resin A1 and adjusting the production conditions of the film, the same operation was carried out as in Example 4 to obtain an optical film with a thickness of 35 μm. The optical film was then stretched using a biaxial stretching device (EX10-B manufactured by Toyo Seiki Seisakusho Co., Ltd.) , an optical film with a thickness of 24 μm was obtained and evaluated. The thickness of the layer of resin A4 is 10 μm.

[Example 8]

Except for adjusting the manufacturing conditions of the film, the same operation was performed as in Example 4 to obtain an optical film with a thickness of 40 μm. This optical film was then stretched using a biaxial stretching device (EX10-B manufactured by Toyo Seiki Seisakusho Co., Ltd.) to obtain an optical film with a thickness of 27 μm. film and evaluate it. The thickness of the resin A1 layer is 13 μm.

[Comparative example 1]

Except for changing the following matters in the production of resin A and adjusting the film production conditions, the same operation was performed as in Example 1 to obtain an optical film with a thickness of 20 μm and evaluate it. ・Use polyethylene terephthalate ("SA-8339P" manufactured by UNITIKA) instead of cycloolefin resin C1. ・Use a trihydrazine-based ultraviolet absorber ("ADEKA STAB (registered trademark) LA-F70" manufactured by ADEKA Corporation) instead of compound (a1).

[Comparative example 2]

Except for changing the following matters in the production of resin A, the same operation was performed as in Example 1 to obtain an optical film with a thickness of 20 μm and evaluate it. ・Use 90.5 parts of polyethylene terephthalate ("SA-8339P" manufactured by UNITIKA) in place of 92 parts of "cycloolefin resin C1". ・Use 8 parts of trihydrazine-based ultraviolet absorber ("ADEKA STAB (registered trademark) LA-F70" manufactured by ADEKA Corporation) and indole-based compound ("BONASORB (registered trademark) UA-3911" manufactured by ORIENT Chemical Industry Co., Ltd.) 1.5 parts instead of 8 parts of compound (a1).

[Comparative example 3]

Except for changing the following matters in the production of resin A and adjusting the film production conditions, the same operation was performed as in Example 1 to obtain an optical film with a thickness of 20 μm and evaluate it. ・Change the amount of cycloolefin resin C1 to 98.5 parts. ・1.5 parts of an indole-based compound ("BONASORB (registered trademark) UA-3911" manufactured by ORIENT Chemical Industry Co., Ltd.) was used instead of 8 parts of compound (a1).

[Comparative example 4]

Resin A5 was produced as resin A by referring to the manufacturing operation of resin A1 described above, except for changing the following matters. ・Change the amount of cycloolefin resin C1 to 98.5 parts. ・1.5 parts of an indole-based compound ("BONASORB (registered trademark) UA-3911" manufactured by ORIENT Chemical Industry Co., Ltd.) was used instead of 8 parts of compound (a1).

Except using resin A5 instead of resin A1 and adjusting the production conditions of the film, the same operation was performed as in Example 4 to obtain an optical film with a thickness of 34 μm and evaluate it. The thickness of the resin A5 layer is 20 μm.

The results of the Examples and Comparative Examples are disclosed in the table below. The codes in the table below have the following meanings. C1: Cyclic olefin resin ("Zeonor" manufactured by Zeon Corporation, Japan) C2: Cyclic olefin resin ("ARTON" manufactured by JSR Corporation) a1: Compound (a1) produced in Production Example 1 a2: Compound (a2) produced in Production Example 2 LA-F70: "ADEKA STAB (registered trademark) LA-F70" made by ADEKA Corporation UA-3911: "BONASORB (registered trademark) UA-3911" manufactured by ORIENT Chemical Industry Co., Ltd. Tmax(300-410): Maximum light transmittance (%) at wavelengths above 300 nm and below 410 nm T(430): Light transmittance at wavelength 430 nm (%) Increase rate R: Increase rate R of light transmittance at wavelengths above 410 nm and below 420 nm (%/nm)

"Table 1" Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Thin film construction A A A B1/A/B2 B1/A/B2 B1/A/B2 layer material B1 - - - C1 C1, a1 C1 A C1, a1 C1, a2 C2, a1 C1, a1 C1, a1 C1, a1 B2 - - - C1 C1, a1 C1 UV absorber Kind a1 a2 a1 a1 a1 a1 Contains skeleton structure benzotriazole benzotriazole benzotriazole benzotriazole benzotriazole benzotriazole Content(wt%) 8 6 7 8 A:7 B1, 2:1.5 5 Maximum absorption wavelength (nm) 367 368 367 367 367 367 Resin layer A thickness (μm) 20 20 15 20 20 30 Tmax(300－410)(%) 3 8 10 3 3 4 T(430)(%) 83 84 86 83 83 84 Increase rate R(%/nm) 4.3 4.6 4.9 4.3 4.3 4.4 Re(590)(nm) 3 4 2 4 5 80 Lightfastness A A A A A A Hue display performance B B A B B B

"Table 2" Table 2 Example 7 Example 8 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Thin film construction B1/A/B2 B1/A/B2 A A A B1/A/B2 layer material B1 C1 C1 - - - C1 A C1, a1 C1, a1 PET, LA-F70 PET, LA-F70, UA-3911 C1, UA-3911 C1, UA-3911 B2 C1 C1 - - - C1 UV absorber Kind a1 a1 LA-F70 LA-F70 Contains skeleton structure benzotriazole benzotriazole trihydrazine trihydrazine Content(wt%) 11 8 8 8 Maximum absorption wavelength (nm) 367 367 355 355 UV absorber Kind - - - UA-3911 UA-3911 UA-3911 Contains skeleton structure - - - indole indole indole Content(wt%) - - - 1.5 1.5 1.5 Maximum absorption wavelength (nm) - - - 393 393 393 Resin layer A thickness (μm) 10 13 20 20 20 20 Tmax(300－410)(%) 9 10 67 2 3 3 T(430)(%) 86 86 88 67 69 69 Increase rate R(%/nm) 4.8 4.9 1.7 2.4 2.5 2.5 Re(590)(nm) 110 230 35 29 4 5 Lightfastness A A A B B B Hue display performance A A C B B B

The light transmittance at wavelengths above 300 nm and below 410 nm is below 10%, the light transmittance at wavelength 430 nm is above 80%, and the increase rate of light transmittance at wavelengths above 410 nm and below 420 nm The single-layer optical films of Examples 1, 2 and 3 with a thickness of 4.0%/nm or above can efficiently block ultraviolet light contained in external light without blocking the light from the organic EL image display device. It can be seen from this that while the display elements of the organic EL image display device are protected from ultraviolet rays, the image display device can display clearly with almost no change in display hue.

Furthermore, the light transmittance at a wavelength of 300 nm or more and 410 nm or less is 10% or less, the light transmittance at a wavelength of 430 nm or more is 80%, or the light transmittance at a wavelength of 410 nm or more and 420 nm or less The multi-layer optical films of Examples 4, 5, 6, 7 and 8 with an increase rate of 4.0%/nm or above can efficiently block ultraviolet light contained in external light without blocking the light from the organic EL image display device. Light. It can be seen from this that while the display elements of the organic EL image display device are protected from ultraviolet rays, the image display device can display clearly with almost no change in display hue.

100: Optical film 101:Resin layer 101U: Noodles 102:Resin layer 102D:face 103:Resin layer 210:Polarizing plate 211: Optical film 214:Polarizer 214U: Noodles 220:Polarizing plate 221: Optical film 224:Polarizer 224D:face 224U: noodles 225: Phase difference layer 310:Image display device 316:Image display component 320:Image display device 326:Image display component

<Fig. 1> Fig. 1 is a schematic cross-sectional view of an optical film related to the second embodiment. <Fig. 2> Fig. 2 is a schematic cross-sectional view of a polarizing plate related to the third embodiment. <Fig. 3> Fig. 3 is a schematic cross-sectional view of a polarizing plate related to the fourth embodiment. <Fig. 4> Fig. 4 is a schematic cross-sectional view of the image display device related to the fifth embodiment. <Fig. 5> Fig. 5 is a schematic cross-sectional view of an image display device related to the sixth embodiment.

100: Optical film

101:Resin layer

101U: Noodles

102:Resin layer

102D:face

103:Resin layer

Claims (8)

An optical film, which is an optical film including a resin layer A. The resin layer A is formed of resin A. The resin A contains more than 50% by weight of an alicyclic structure-containing polymer and an ultraviolet absorber. The optical film has a wavelength of 300 nm. The transmittance of light above and below 410nm is below 9%, the transmittance of light at wavelength 430nm is above 80%, the increase rate of the transmittance of light between wavelengths above 410nm and below 420nm is above 4.0%/nm, as mentioned above The ultraviolet absorber includes a compound containing a sesamol structure and a benzotriazole structure. The optical film according to claim 1, further comprising a resin layer B1 and a resin layer B2. The resin layer B1 is provided on one side of the resin layer A, and the resin layer B1 is provided on the other side of the resin layer A. B2, the resin layer B1 is formed of a thermoplastic resin B1 with an ultraviolet absorber content of 3.0% by weight or less, and the resin layer B2 is formed of a thermoplastic resin B2 with an ultraviolet absorber content of 3.0% by weight or less. The optical film according to claim 2, which is a co-extruded film. The optical film according to any one of claims 1 to 3, wherein the retardation Re (590) in the in-plane direction at a wavelength of 590 nm is 0.1 nm or more. A polarizing plate comprising the optical film and polarizer as described in any one of claims 1 to 4. The polarizing plate according to claim 5, further comprising a retardation layer C having a retardation Re (590) of 70 nm or more in the in-plane direction at a wavelength of 590 nm. An image display device comprising the polarizing plate as described in claim 5 or 6. An organic electroluminescent image display device, which includes the polarizing plate as described in claim 5 or 6.

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