JP7420084B2 - Organic electroluminescent image display device - Google Patents

Description

The present invention relates to an optical film, a polarizing plate, and an image display device.

Image display devices may include a circularly polarizing plate to reduce reflection of external light. Since the image display device can be used in environments such as outdoors where the intensity of ultraviolet rays is high, the image display device may be equipped with an optical film containing an ultraviolet absorber in order to protect the polarizer from ultraviolet rays ( Patent Document 1).

Japanese Patent Application Publication No. 2017-187619

It has been considered that an optical film provided in an image display device preferably has a high light transmittance for light in the visible light range in order to reduce the influence on the color of a displayed image. For example, if the absorption loss in the light transmittance of light in the visible light region is large, the absorption of light at a certain wavelength in the visible light region will be large, resulting in a tinted image when the screen is displayed in white. It may happen.

On the other hand, when a retardation film such as a λ/4 plate is used as a circularly polarizing plate of an image display device, depending on the wavelength dispersion of the retardation Re in the in-plane direction of the retardation film, it is difficult to observe the image display device from the front. The hue of the image may deviate from the original color. For example, if the retardation Re in the in-plane direction of the retardation film is normal wavelength dispersion, light with a wavelength in the violet to blue region that is reflected by the reflective electrode of an image display device will pass through the polarizer. When the screen is displayed in black, the screen may take on a bluish tinge. Here, the in-plane retardation having normal wavelength dispersion means that the in-plane retardation Re(450) at a wavelength of 450 nm and the in-plane retardation Re(550) at a wavelength of 550 nm are as follows. This means that the formula is satisfied.
Re(450)/Re(550)≧1

Therefore, an optical film that can protect the image display device from ultraviolet rays and improve the hue when the image display device is observed from the front; There is a need for a polarizing plate that can improve the hue when viewed; and an image display device that can improve the hue when viewed from the front.

The present inventors have made extensive studies to solve the above problems. As a result, 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 is 80% or more, and the increase rate of light transmittance at a wavelength of 410 nm or more and 420 nm or less is 4.0%. The inventors have discovered that the above-mentioned problems can be solved by an optical film having a particle diameter of /nm or more, and have completed the present invention.
That is, the present invention provides the following.

[1] An optical film including a resin layer A,
The resin layer A is formed from resin A,
The resin A contains 50% by weight or more of an alicyclic structure-containing polymer and an ultraviolet absorber,
The optical film has a light transmittance of 10% or less at a wavelength of 300 nm or more and 410 nm or less, a light transmittance of 80% or more at a wavelength of 430 nm, and an increase rate of light transmittance at a wavelength of 410 nm or more and 420 nm or less. 0%/nm or more,
optical film.
[2] Further comprising a resin layer B1 and a resin layer B2,
The resin layer B1 is provided on one surface of the resin layer A,
The resin layer B2 is provided on the other surface of the resin layer A,
The resin layer B1 is formed from a thermoplastic resin B1 in which the content of an ultraviolet absorber is 3.0% by weight or less,
The optical film according to [1], wherein the resin layer B2 is formed from a thermoplastic resin B2 having an ultraviolet absorber content of 3.0% by weight or less.
[3] The optical film according to [2], which is a coextruded 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], which has an in-plane retardation Re (590) of 0.1 nm or more at a wavelength of 590 nm.
[6] A polarizing plate comprising the optical film according to any one of [1] to [5] and a polarizer.
[7] The polarizing plate according to [6], further comprising a retardation layer C having an in-plane retardation Re (590) of 70 nm or more at a wavelength of 590 nm.
[8] An image display device comprising the polarizing plate according to [6] or [7].

This disclosure also includes the following content.
[9] A method for producing the optical film according to [3], comprising:
The thermoplastic resin B1, the resin A, and the thermoplastic resin B2 are coextruded from a die, and the thermoplastic resin B1 layer, the resin A layer, and the thermoplastic resin B2 layer are laminated in this order. A method for producing an optical film, comprising the step of obtaining an extruded film.

According to the present invention, an optical film that can protect an image display device from ultraviolet rays and improve the hue when the image display device is observed from the front; It is possible to provide a polarizing plate that can improve the hue when viewed from the front; and an image display device that can improve the hue when viewed from the front.

FIG. 1 is a cross-sectional view schematically showing an optical film according to a second embodiment. FIG. 2 is a cross-sectional view schematically showing a polarizing plate according to a third embodiment. FIG. 3 is a cross-sectional view schematically showing a polarizing plate according to a fourth embodiment. FIG. 4 is a cross-sectional view schematically showing an image display device according to a fifth embodiment. FIG. 5 is a cross-sectional view schematically showing an image display device according to a sixth embodiment.

Hereinafter, the present invention will be described in detail by showing embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be implemented with arbitrary changes within the scope of the claims of the present invention and equivalents thereof. Further, elements that are the same as those that have already been described may be given the same reference numerals, and their explanations may be omitted.

In the following explanation, the front direction of an image display device means the normal direction of the screen of the image display device, unless otherwise specified, and specifically, the front direction of the screen is 0° in polar angle and 0° in azimuth. Point in a direction.

In the following description, the hue when the image display device is observed from the front is sometimes simply referred to as the "front hue." Improving the front hue means changing the bluish black display state or the yellowish white display state when the image display device is viewed from the front toward the intended original black display state or white display state. It means that.

In the following description, unless otherwise specified, the term "plate" includes not only rigid members but also flexible members such as resin films.

In the following description, the slow axis of a film or layer refers to the slow axis in the plane of the film or layer, unless otherwise specified.

In the following description, unless otherwise specified, the angle formed by the optical axis (slow axis, transmission axis, absorption axis, etc.) of each layer in a member having multiple layers is the angle when the layer is viewed from the thickness direction. represents.

In the following description, the term "circularly polarizing plate" includes not only a circularly polarizing plate in a narrow sense but also an elliptically polarizing plate.

In the following description, a "long" film refers to a film having a length of 5 times or more, preferably 10 times or more, of the width, and specifically a roll A film that is long enough to be rolled up into a shape for storage or transportation. The upper limit of the length of the film is not particularly limited, and may be, for example, 100,000 times or less the width.

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

In the following description, unless otherwise specified, the directions of elements are "parallel," "perpendicular," and "perpendicular" within a range that does not impair the effects of the present invention, such as ±3°, ±2°, or ±1°. may include errors within the range of .

[1. Optical film]
The optical film according to one embodiment of the present invention includes a resin layer A.
Resin layer A is formed from resin A. Resin A, which is the material of resin layer A, contains an alicyclic structure-containing polymer in an amount of 50% by weight or more based on resin A, and an ultraviolet absorber.
In addition, the optical film has a light transmittance of 10% or less at a wavelength of 300 nm or more and 410 nm or less, a light transmittance of 80% or more at a wavelength of 430 nm, and an increase rate of light transmittance at a wavelength of 410 nm or more and 420 nm or less. .0%/nm or more.

[1.1. Resin A]
Resin A contains an alicyclic structure-containing polymer. Here, the alicyclic structure-containing polymer is a polymer whose structural unit has an alicyclic structure. Resins containing such alicyclic structure-containing polymers usually have excellent performance such as transparency, dimensional stability, retardation development, and stretchability at low temperatures.

The alicyclic structure-containing polymer includes 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 the side chain, and It may be a mixture of two or more of these in any ratio. Among these, from the viewpoint of mechanical strength and heat resistance, polymers having an alicyclic structure in the main chain are preferred.

Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkenes, cycloalkynes) structures. Among these, from the viewpoint of mechanical strength and heat resistance, cycloalkane structures and cycloalkene structures are preferable, and among them, cycloalkane structures are particularly preferable.

The number of carbon atoms constituting the alicyclic structure is preferably 4 or more, more preferably 5 or more, and preferably 30 or less, more preferably 20 or less, particularly preferably 20 or less, per alicyclic structure. is 15 or less. When the number of carbon atoms constituting the alicyclic structure is within this range, the mechanical strength, heat resistance, and moldability of the resin A are highly balanced.

In the alicyclic structure-containing polymer, the proportion of structural units having an alicyclic structure can be selected depending on the intended use 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 usually 100% by weight or less. It can be said. When the proportion of structural units 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 good.

Among the alicyclic structure-containing polymers, cycloolefin polymers are preferred. A cycloolefin polymer is a polymer having a structure obtained by polymerizing cycloolefin monomers. A cycloolefin monomer is a compound having a ring structure formed of carbon atoms and having a polymerizable carbon-carbon double bond in the ring structure. Examples of polymerizable carbon-carbon double bonds include carbon-carbon double bonds that can undergo polymerization such as ring-opening polymerization. Further, examples of the ring structure of the cycloolefin monomer include monocyclic, polycyclic, condensed polycyclic, bridged ring, and polycyclic combinations of these. Among these, polycyclic cycloolefin monomers are preferred from the viewpoint of highly balancing properties such as dielectric properties and heat resistance of the resulting polymer.

Among the above cycloolefin polymers, preferred are norbornene polymers, monocyclic olefin polymers, cyclic conjugated diene polymers, and hydrides thereof. Among these, norbornene polymers are particularly suitable because they have good moldability.

Examples of norbornene-based polymers include ring-opening polymers of monomers having a norbornene structure and hydrides thereof; addition polymers of monomers having a norbornene structure and hydrides thereof. Furthermore, examples of ring-opened polymers of monomers having a norbornene structure include ring-opened homopolymers of one type of monomer having a norbornene structure, and ring-opened polymers of two or more types of monomers having a norbornene structure. Examples include copolymers and ring-opened copolymers of a monomer having a norbornene structure and other monomers that can be copolymerized with the monomer. Furthermore, examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, and addition copolymers of two or more types of monomers having a norbornene structure. , and an addition copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer. Among these, hydrogenated ring-opening polymers of monomers having a norbornene structure are particularly suitable from the viewpoints of moldability, heat resistance, low moisture absorption, dimensional stability, lightness, and the like.

Examples of monomers having a norbornene structure include bicyclo[2.2.1]hept-2-ene (common name: norbornene), 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: methanotetrahydrofluorene), tetracyclo[4.4. 0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent on the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Further, a plurality of these substituents, which are the same or different, may be bonded to the ring. The monomers having a norbornene structure may be used alone or in combination of two or more in any ratio.

Examples of polar groups include heteroatoms and atomic groups having heteroatoms. Examples of heteroatoms include oxygen, nitrogen, sulfur, silicon, and halogen atoms. Specific examples of polar groups include carboxyl group, carbonyloxycarbonyl group, epoxy group, hydroxyl group, oxy group, ester group, silanol group, silyl group, amino group, amide group, imide group, nitrile group, and sulfonic acid group. can be mentioned. As the polymer constituting resin A, either one containing such a polar group or one not containing such a polar group can be preferably used.

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

A ring-opening polymer of a monomer having a norbornene 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 addition-copolymerized with monomers having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, and cyclohexene. and their derivatives; and nonconjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene. Among these, α-olefin is preferred, and ethylene is more preferred. Furthermore, the monomers capable of addition copolymerizing with the monomer having a norbornene structure may be used alone or in combination of two or more in any ratio.

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

The above-mentioned hydrogenated products of ring-opening polymers and addition polymers are produced by, for example, hydrogenation of carbon in a solution of these ring-opening polymers and addition polymers in the presence of a hydrogenation catalyst containing a transition metal such as nickel or palladium. - Can be produced by hydrogenating carbon unsaturated bonds, preferably 90% or more.

Examples of monocyclic olefin polymers include addition polymers of cyclic olefin monomers having a single ring such as cyclohexene, cycloheptene, and cyclooctene.

Examples of cyclic conjugated diene polymers include polymers obtained by cyclizing addition polymers of conjugated diene monomers such as 1,3-butadiene, isoprene, and chloroprene; cyclic conjugated polymers such as cyclopentadiene and cyclohexadiene; Examples include 1,2- or 1,4-addition polymers of diene monomers; and hydrides thereof.

As the alicyclic structure-containing polymer and the resin containing it, commercially available resins can be used. Examples of commercially available resins include Zeonor (manufactured by Nippon Zeon Co., Ltd.), Arton (manufactured by JSR Corporation), TOPAS (manufactured by Polyplastics Co., Ltd.), and Appel (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, 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 equal to or higher than the lower limit, the resin A can have the excellent properties of the alicyclic structure-containing polymer.
Resin A may contain only one type of alicyclic structure-containing polymer, or may contain a combination of two or more types in any ratio.

[1.2. UV absorber]
Resin A contains an ultraviolet absorber. The term "ultraviolet absorber" refers to an agent having one or more absorption maximums in a wavelength range of 250 nm or more and 400 nm or less in a light absorption spectrum. Here, the "agent" may be composed of one type of substance, or may be a composition composed of two or more types of substances. In addition to having an absorption maximum at a wavelength of 400 nm or less, the ultraviolet absorber may have an absorption maximum at a wavelength exceeding 400 nm. Resin A may contain only one type of ultraviolet absorber, or may contain a combination of two or more types in any ratio.

As the ultraviolet absorber, it is preferable to use an agent having maximum absorption at a wavelength of 400 nm or less in a light absorption spectrum of wavelengths of 250 nm or more and 450 nm or less. Thereby, the optical film can effectively absorb ultraviolet rays and protect components of the image display device, such as polarizers, from ultraviolet rays.

The light absorption spectrum of the ultraviolet absorber is measured using an ultraviolet/visible spectrometer (e.g. "UV-2450" manufactured by Shimadzu Corporation), measurement wavelength: 250 nm to 450 nm, solvent: chloroform or methanol, concentration: 10 ppm, cell: optical path length. It can be measured under the conditions of a 1 cm quartz cell.

As the ultraviolet absorber, it is preferable to use an ultraviolet absorber whose wavelength of light exhibiting maximum absorbance in a light absorption spectrum in a wavelength range of 250 nm or more and 450 nm or less is in a range of 350 nm or more and 400 nm or less. Hereinafter, in a light absorption spectrum in a wavelength range of 250 nm or more and a wavelength of 450 nm or less, a specific ultraviolet absorber whose wavelength of light exhibiting maximum absorbance is in the range of 350 nm or more and 400 nm or less may be referred to as ultraviolet absorbent U1. By using an ultraviolet absorber whose wavelength of light exhibiting maximum absorbance is within the above range, the optical film can effectively suppress the light transmittance at wavelengths of 300 nm or more and 410 nm or less. As a result, the amount of light with a wavelength of 300 nm or more and 410 nm or less emitted from the image display device can be effectively suppressed, and the hue when the image display device is observed 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.

In the general formula (1),
R ¹ is a hydrogen atom, a halogen atom, a (C1 to C8) alkyl group, a (C1 to C8) alkyloxy group, a hydroxy group, an amino group, a linear or branched monosubstituted amino group having 1 to 4 carbon atoms, carbon Number 1 to 4 linear or branched di-substituted amino groups, nitro groups, carboxy groups, (C1 to C8) alkyloxycarbonyl groups, hydroxy (C1 to C8) alkyl groups, (C1 to C8) alkylcarbonyloxy (C1 to C8) ~C8) represents an alkyl group, a carboxy (C1 to C3) alkyl group, a (Cx) alkyloxycarbonyl (Cy) alkyl group, an aryl group, an acyl group, a sulfo group, or a cyano group. Here, the description of (Cm to Cn) immediately before "alkyl" means that the number of carbon atoms in the alkyl is m or more and no more than n, and the description of (Cm) immediately before "alkyl" means that the number of carbon atoms in the alkyl is m. x and y are each integers of 1 or more, and x+y is 2 or more and 10 or less.

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

Specific examples of Compound I include 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 a sesamol structure and a benzotriazole structure in the ultraviolet absorber is preferably 50% by weight or more, more preferably 70% by weight or more, even more preferably 90% by weight or more, and can be 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, even more preferably 6.0% by weight or more, and preferably 30% by weight or less, more preferably It is preferably 25% by weight or less, more preferably 20% by weight or less. By keeping the content of the ultraviolet absorber in the resin A within the above range, it is possible to suppress the ultraviolet absorber from bleeding out from the resin layer A, effectively protect the image display device from ultraviolet rays, and further improve image display. The front hue of the device can be improved.

[1.3. Optional components contained in resin A]
Resin A may contain arbitrary components in addition to the ultraviolet absorber described above. Examples of such optional ingredients include antioxidants; light stabilizers; waxes; nucleating agents; optical brighteners; inorganic fillers; colorants; flame retardants; flame retardant aids; antistatic agents; plasticizers; Infrared absorbers; lubricants; fillers; and arbitrary polymers other than alicyclic structure-containing polymers. Further, as an arbitrary component, one type may be used alone, or two or more types may be used in combination in any ratio.

[1.4. [Any layer that can be included in the optical film]
The optical film may include any layer other than the resin layer A. Examples of such arbitrary layers include an adhesive layer, a layer having a retardation, and a hard coat layer.

[1.5. Characteristics of optical film]
(Light transmittance at wavelengths from 300 nm to 410 nm)
The optical film usually has a light transmittance of 10% or less at a wavelength of 300 nm or more and 410 nm or less. The light transmittance of 10% or less in the wavelength range of 300 nm or more and 410 nm 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 the optical film at a wavelength of 300 nm or more and 410 nm or less is usually 10% or less, preferably 8% or less, more preferably 5% or less, ideally 0%, but 0% or more or 0. It can be 0.01% or more.
When the light transmittance of the optical film at a wavelength of 300 nm or more and 410 nm or less is equal to or less than the upper limit value, the image display device can be effectively protected from ultraviolet rays, and furthermore, the front hue of the image display device can be improved. In particular, organic components contained in organic electroluminescent elements (organic EL elements) are particularly susceptible to deterioration by long wavelength ultraviolet rays. Therefore, 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 the optical film can be measured using an ultraviolet-visible near-infrared spectrophotometer (eg, "V-7200" manufactured by JASCO Corporation).

(Light transmittance at wavelength 430nm)
The light transmittance of the optical film at a wavelength of 430 nm is usually 80% or more, preferably 82% or more, more preferably 85% or more, and is preferably higher, but is usually 100% or less. When the light transmittance of the optical film at a wavelength of 430 nm is equal to or greater than the lower limit value, the front hue of the image display device can be improved without significantly affecting the color tone of the image display device. This effect is particularly noticeable when the light emitting elements included in the image display device are organic EL elements. Many of the organic EL elements used in image display devices exhibit a rapid increase in emission intensity from around a wavelength of 430 nm toward longer wavelengths. Therefore, by setting the light transmittance of the optical film at a wavelength of 430 nm to be equal to or higher than the lower limit value, the light emitted from the organic EL element at a wavelength of around 430 nm becomes difficult to be absorbed by the optical film. As a result, the influence on the color tone of the image display device can be reduced.

(Increase rate of light transmittance at wavelengths from 410 nm to 420 nm)
The optical film has an increase rate R of light transmittance at a wavelength of 410 nm or more and 420 nm or less, usually 4.0%/nm or more, preferably 4.2%/nm or more, more preferably 4.5%/nm or more, especially It is preferably 4.7%/nm or more, preferably larger, but may be 7.0%/nm or less.
The increase rate R (%/nm) is calculated by the following formula.
R (%/nm) = (T (420) - T (410)) / (420 - 410)
In the above formula, T (420) is the light transmittance (%) of the optical film at a wavelength of 420 nm, T (410) is the light transmittance (%) of the optical film at a wavelength of 410 nm, and the unit of the denominator is It is nm.

When the increase rate R of the optical film is equal to or greater than the lower limit value, the optical film can transmit light with a wavelength of 430 nm at a high rate while effectively absorbing light with a wavelength of 300 nm or more and 410 nm or less. 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 improved without significantly affecting the color tone of the image display device.

(In-plane retardation of optical film)
The in-plane retardation Re (590) at a wavelength of 590 nm of the optical film is preferably 0.1 nm or more, more preferably 1 nm or more, even more preferably 2 nm or more, preferably 300 nm or less, more preferably 270 nm or less, More preferably, it is 250 nm or less. Thereby, the optical film can have a function as a retardation film such as a λ/4 plate.

It is preferable that the in-plane direction retardation of the optical film has forward wavelength dispersion. Specifically, Re(450)/Re(550) is preferably 1 or more, more preferably larger than 1.
When the in-plane direction retardation of the optical film has normal wavelength dispersion, the front hue of the image display device can be particularly improved.

[1.6. Thickness of resin layer A]
The thickness of the resin layer A is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 7 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less. When the thickness of the resin layer A is equal to or greater than the 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 significantly affecting the color tone of the image display device. When the thickness of the resin layer A is equal to or less than the upper limit value, the optical film including the resin layer A can be made thinner.

[1.7. Optical film of first embodiment]
The optical film according to the first embodiment is an optical film made of resin layer A. The resin layer A is formed from the resin A described above. The optical film of this embodiment also includes the above [1.5. Characteristics of Optical Film].
The optical film of this embodiment can be manufactured by a conventionally known method. For example, the optical film can be manufactured by melt molding or solution casting, with melt molding being preferred. The optical film may be further subjected to treatments such as stretching and trimming.

[1.8. Optical film of second embodiment]
The optical film according to the second embodiment further includes a resin layer B1 and a resin layer B2 in the resin layer A, and the resin layer B1 is provided on one surface of the resin layer A, and the other surface of the resin layer A is A resin layer B2 is provided on the surface. The resin layer B1 is made of a thermoplastic resin B1 having an ultraviolet absorber content of 3.0% by weight or less. The resin layer B2 is made of a thermoplastic resin B2 having an ultraviolet absorber content of 3.0% by weight or less.

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

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

The content of the alicyclic structural polymer in the thermoplastic resin B1 is preferably 97.0% by weight or more, more preferably 98.0% by weight or more, and still more preferably 98.5% by weight or more. . When the content of the alicyclic structure polymer in the thermoplastic resin B1 is equal to or higher than the lower limit value, the thermoplastic resin B1 can have the excellent properties of the alicyclic structure-containing 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, more preferably 1.5% by weight or less, and even more preferably 1.0% by weight or less, particularly preferably substantially 0% by weight, and most preferably no ultraviolet absorber. When the content of the ultraviolet absorber in the thermoplastic resin B1 is equal to or less than the upper limit value, bleeding out of the ultraviolet absorber onto the surface of the optical film can be suppressed.

Thermoplastic resin B1 may contain arbitrary components in addition to the above-mentioned polymer. As the optional component, the same component as the optional component that resin A may contain can be used.

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

The content of the alicyclic structural polymer in the thermoplastic resin B2 is preferably 97.0% by weight or more, more preferably 98.0% by weight or more, and even more preferably 98.5% by weight or more. . When the content of the alicyclic structure polymer in the thermoplastic resin B2 is equal to or higher than the lower limit, the thermoplastic resin B2 can have the excellent properties 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, more preferably 1.5% by weight or less, and even more preferably 1.0% by weight or less, particularly preferably substantially 0% by weight, and most preferably no ultraviolet absorber. When the content of the ultraviolet absorber in the thermoplastic resin B2 is equal to or less than the upper limit value, bleeding out of the ultraviolet absorber onto the surface of the optical film can be suppressed.

Thermoplastic resin B2 may contain arbitrary components in addition to the above-mentioned polymer. As the optional component, the same component as the optional component that resin A may contain can be used.

The thermoplastic resin B1 and the thermoplastic resin B2 may be different types of resins having different polymers, component ratios, physical properties, and the like. However, from the viewpoint of suppressing curling of the optical film and facilitating the manufacture of the optical film, 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, more preferably 2 μm or more, and preferably 15 μm or less, more preferably 10 μm or less.

The thickness range of the resin layer B2 may be the same as the thickness range 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 ((B1+B2)/A1) of the total thickness of resin layer B1 and resin layer B2 to the thickness of resin layer A1 is preferably 1/25 or more, more preferably 1/10 or more, and even more preferably 1/5. or more, preferably 10/1 or less, more preferably 6/1 or less, still more preferably 4/1 or less.

The optical film of this embodiment also includes the above [1.5. Characteristics of Optical Film].

The optical film of this embodiment can be manufactured by a conventionally known manufacturing method. For example, the optical film of this embodiment can be manufactured by a melt molding method or a solution casting method.
The optical film of this embodiment is preferably manufactured by a melt molding method, and more preferably by a coextrusion method. Examples of the coextrusion method include a coextrusion T-die method, a coextrusion inflation method, and a coextrusion lamination method. Among these, the coextrusion T-die method is preferred.

A method for producing an optical film using the coextrusion T-die method will be described below.
Thermoplastic resin B1, resin A, and thermoplastic resin B2 are melted, each is supplied to a T-die, and coextruded. By coextrusion, an extruded film is obtained in which a layer of thermoplastic resin B1, a layer of resin A, and a layer of thermoplastic resin B2 are laminated in this order. A long optical film is obtained by cooling the extruded film usually on a cooling roll and then winding it up on a take-up roll.

The optical film obtained by the coextrusion method may be further subjected to treatments such as stretching and trimming, as necessary.

[1.9. Applications of optical film]
The optical film can be suitably used as an element of a polarizing plate, such as a polarizing plate protective film and a λ/4 plate. A polarizing plate containing an optical film can be suitably used as a polarizing plate incorporated into an image display device such as a liquid crystal display device or an organic EL display device.

[2. Polarizer]
A polarizing plate according to an embodiment of the present invention includes the disclosed optical film and a polarizer.

[2.1. Polarizer]
As a polarizer, for example, a film of an appropriate vinyl alcohol polymer such as polyvinyl alcohol or partially formalized polyvinyl alcohol is dyed with a dichroic substance such as iodine and a dichroic dye, stretched, crosslinked, etc. Examples include films that have been subjected to appropriate treatments in an appropriate order and manner. Further, other examples of the polarizer include polarizers having a function of separating polarized light into reflected light and transmitted light, such as a grid polarizer, a multilayer polarizer, and a cholesteric liquid crystal polarizer. Among these, a polarizer made of a polyvinyl alcohol resin film containing polyvinyl alcohol is preferred. Such a polarizer is capable of transmitting linearly polarized light when natural light is incident thereon, and in particular, one having excellent light transmittance and polarization degree is preferable. The thickness of the polarizer is generally 5 μm to 80 μm, but is not limited thereto.

[2.2. Optical film]
The optical film included in the polarizing plate is [1. Optical Film].
The optical film may have an in-plane retardation Re(590) of 0.1 nm or more at a wavelength of 590 nm, or may have a Re(590) of 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 be made to function as a circularly polarizing plate.
The polarizer may be provided on either side of the optical film. For example, when the optical film further includes a resin layer B1 and a resin layer B2 in addition to the resin layer A, like the optical film according to the second embodiment, the optical film includes a polarizer, a resin layer B1, and a resin layer A. , and resin layer B2 in this order, or may include a polarizer, resin layer B2, resin layer A, and resin layer B1 in this order.

[2.3. Polarizing plate of third embodiment]
In the polarizing plate according to the third embodiment, an optical film is provided on one surface of the polarizer. FIG. 2 is a cross-sectional view schematically showing a polarizing plate according to a third embodiment. As shown in FIG. 2, polarizing plate 210 includes an optical film 211 and a polarizer 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, the angle is preferably 45°±5°, more preferably 45°±3°, and even more preferably 45°±1°. This allows the polarizing plate to function as a circularly polarizing plate.

In another embodiment, other layers such as an adhesive layer may be provided between the polarizer and the optical film.
In another embodiment, a layer having a retardation, such as a λ/2 plate, may be provided between the polarizer and the optical film.

[2.4. Polarizing plate of fourth embodiment]
The polarizing plate according 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 at 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 cross-sectional view schematically showing a polarizing plate according to a fourth embodiment. As shown in FIG. 3, the polarizing plate 220 includes an optical film 221, a polarizer 224, and a retardation layer 225 as a 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. A retardation layer 225 is provided on the other surface 224D of the polarizer 224 so as to be in contact with the polarizer 224.

The optical film 221 preferably has an in-plane retardation Re (590) of 0 nm or a value close to it at a wavelength of 590 nm, specifically, preferably less than 10 nm, more preferably 5 nm or less. This can suppress changes in the polarization state of the linearly polarized light that has passed through the polarizer 224.

In another embodiment, other layers such as an adhesive layer may be provided between the polarizer and the optical film. In another embodiment, another layer such as an adhesive layer may be provided between the polarizer and the retardation layer.

[3. Image display device]
An image display device according to an embodiment of the present invention includes the disclosed polarizing plate and an image display device. As the image display device, any type of image display device can 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. Hereinafter, preferred embodiments of the image display device will be described.

[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 cross-sectional view schematically showing an image display device according to a fifth embodiment. The image display device 310 according to this embodiment includes a polarizer 214, an optical film 211, and an image display element 316 in this order. As described above, the optical film 211 preferably has a function as a λ/4 plate. Thereby, the polarizing plate 210 including the polarizer 214 and the optical film 211 can suppress reflection of external light.

In the image display device 310, the optical film 211 absorbs at least a portion of the ultraviolet rays that have passed through the polarizer 214, thereby reducing the amount of ultraviolet rays that reach the image display element 316. Therefore, the life of the image display device 310 can be extended.

Further, the optical film 211 included in the image display device 310 effectively absorbs light having 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, the front hue of the image display device 310 can be improved by suppressing light having a wavelength of 300 nm or more and 410 nm or less from being transmitted from the polarizer 214 to the outside and being visually recognized. Further, the optical film 211 can transmit light having a wavelength of 430 nm at a high rate. As a result, the front hue of the image display device 310 can be improved without significantly affecting the color tone 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 retardation layer C, and an image display element. FIG. 5 is a cross-sectional view schematically showing an image display device according to a sixth embodiment. As shown in FIG. 5, the image display device 320 according to this embodiment includes an optical film 221, a polarizer 224, a retardation layer 225 as a retardation layer C, and an image display element 326 in this order. The optical film 221 included in the image display device 320 absorbs at least a portion of ultraviolet rays from the outside. Thereby, the ultraviolet rays reaching the polarizer 224 can be reduced and the polarizer 224 can be protected from the ultraviolet rays. Further, the optical film 221 effectively absorbs light having 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 by suppressing light having a wavelength of 300 nm or more and 410 nm or less from being transmitted through the retardation layer 225 and further transmitted through the polarizer 224 to be visually recognized. Further, the optical film 221 can transmit light having a wavelength of 430 nm at a high rate. As a result, the front hue of the image display device 320 can be improved without significantly affecting the color tone of the image display device 320.

The present invention will be specifically described below with reference to Examples. However, the present invention is not limited to the embodiments shown below, and may be implemented with arbitrary changes within the scope of the claims of the present invention and equivalents thereof.

In the following description, "%" and "part" expressing amounts are based on weight, unless otherwise specified. Further, the operations described below were performed at normal temperature and normal pressure unless otherwise specified.

[Evaluation method]
(Maximum absorption wavelength of ultraviolet absorber)
The light absorption spectrum of the ultraviolet absorber at a wavelength of 250 nm or more and 450 nm or less was measured under the following conditions.
・Equipment: UV-visible spectrophotometer (“UV-2450” manufactured by Shimadzu Corporation)
・Solvent: Chloroform ・Concentration: 10ppm
- Cell: 1 cm quartz The maximum absorption wavelength was 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 temperature increase rate was 10°C/min.

(Light transmittance of film)
The light transmittance of the optical film at a wavelength of 300 nm to 450 nm was measured using an ultraviolet-visible near-infrared spectrophotometer (“V-7200” manufactured by JASCO Corporation). The data acquisition interval during measurement was 1 nm.

From the obtained spectrum, the maximum light transmittance (%) at a wavelength of 300 nm or more and 410 nm or less and the light transmittance at a wavelength of 430 nm were read.

The increase rate R of light transmittance at a wavelength of 410 nm or more and 420 nm or less was calculated from the following formula from the light transmittance T (420) (%) at a wavelength of 420 nm and the light transmittance (%) T (410) at a wavelength of 410 nm. .
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, and was defined as the thickness of resin layer A.
In Examples 4 to 8 and Comparative Example 4, the thickness of resin layer A was measured by cutting the film in the thickness direction and observing the cross section with an optical microscope.

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

(Light resistance test)
Using the optical films of Examples 1 to 8 and Comparative Examples 1 to 4, a light resistance test was conducted using ultraviolet irradiation. Irradiation was performed using a super xenon weather meter (SX75: manufactured by Suga Test Instruments Co., Ltd.) under conditions of 72 W/m ² , black panel temperature of 63° C., and humidity of 50% RH. After 300 hours of irradiation, the optical film was taken out, and the retention rate of absorbance at a wavelength of 410 nm was determined according to the following formula.
Retention rate (%) = (A ₁ /A ₀ ) x 100
Here, A ₀ is the absorbance at a wavelength of 410 nm of the optical film before the light resistance test, A ₁ is the absorbance at a wavelength of 410 nm of the optical film after the light resistance test, and A ₀ and A ₁ are the above-mentioned ultraviolet-visible Measurement was performed using a near-infrared spectrophotometer ("V-7200" manufactured by JASCO Corporation).
From the obtained absorbance retention value, light resistance was determined according to the following criteria.
A: Absorbance retention rate is 80% or more.
B: Absorbance retention rate is less than 80%.

(Hue display performance)
Evaluation of hue display performance was performed as follows.
The optical film to be evaluated was attached 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 set to a white display state, and the hue was observed from the front direction of the display surface using a viewing angle measurement evaluation device (“ErgoScope” manufactured by Autronic-MELCHERS). Hue display performance was evaluated according to the following criteria.
A: Overall uniformity and no change in hue was observed.
B: Almost uniform throughout, with almost no change in hue observed.
C: A change in hue was observed on the image.

[Production Example 1 Compound (a1): Synthesis of 6-(2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol]

Attach a beaded condenser, thermometer, and stirrer to a 200 ml four-necked flask, and add 15.2 g (0.110 mol) of orthonitroaniline and 25.4 g (0.162 mol) of 62.5% sulfuric acid to dissolve. 85 ml of water was added while stirring. To this, 21.7 g (0.113 mol) of a 36% aqueous sodium nitrite solution was added dropwise at 3 to 7° C., and the mixture was stirred at the same temperature for 2 hours to obtain 147 g of a diazonium salt aqueous solution. A 500 ml four-necked flask was equipped with a beaded condenser, a thermometer, and a stirring device, and 120 ml of methanol, 4.6 g (0.115 mol) of sodium hydroxide, 6.2 g (0.058 mol) of sodium carbonate, and 15. 2 g (0.110 mol) was added thereto and mixed, and an aqueous diazonium salt solution was added dropwise at 3 to 7°C, followed by stirring 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. 40.3 g of this was repulped and washed with an aqueous isopropyl alcohol solution to obtain 22.0 g of 6-(2-nitrophenylazo)benzo[1,3]dioxol-5-ol as red crystals.

A 300 ml four-necked flask was equipped with a beaded condenser, a thermometer, and a stirring device, and 22.0 g (0.077 mol) of this red crystal, 100 ml of isopropyl alcohol, 50 ml of water, and 3.7 g (0.093 mol) of sodium hydroxide were added. ), 0.2 g of hydroquinone, and 3.6 g (0.043 mol) of 60% hydrazine hydrate were added, stirred at 50 to 55°C for 1 hour, and adjusted to pH 7 with 62.5% sulfuric acid to form a precipitate. The mixture was filtered, washed with water, and dried to obtain 18.4 g of 6-(2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol-N-oxide.

A 1000 ml four-neck flask was equipped with a beaded condenser, a thermometer, and a stirring device, and 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 were added. 31.9 g (0.203 mol) of 62.5% sulfuric acid was added dropwise over 1 hour while maintaining the temperature at 70 to 75°C, and the mixture was stirred at the same temperature for 1 hour. The lower aqueous layer was separated and removed, washed with 100 ml of warm water, 0.6 g of activated carbon was added, and the mixture was stirred under reflux to decolorize the mixture. Filter while hot, collect 180 ml of toluene from the filtrate, cool to 5°C, filter the precipitated crystals, wash with 30 ml of toluene, dry at 60°C, and obtain a compound that is yellow crystals (melting point 195°C). 9.9g of (a1) was obtained. The yield of compound (a1) from orthonitroaniline was 35%.

Further, when the ultraviolet to visible absorption spectrum of compound (a1) was measured, 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)benzo[1,3]dioxol-5-ol]

A 200 ml four-necked flask was equipped with a beaded condenser, a thermometer, and a stirrer, and 2.0 g of 6-(5-hydroxyethyl-2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol was added. (0.0067 mol), 50 ml of toluene, 1.6 g (0.0266 mol) of acetic acid, and 0.1 g (0.0010 mol) of methanesulfonic acid were added and dehydrated under reflux at 110 to 115° C. for 4 hours. The mixture was washed three times with 50 ml of warm water, 0.1 g of activated carbon was added, and the mixture was stirred under reflux to decolorize it. It was filtered while hot, and the precipitated crystals were filtered, washed with 10 ml of toluene, and then dried at 60° C. to obtain 2.2 g of compound (a2). The yield from 6-(5-hydroxyethyl-2H-benzotriazol-2-yl)benzo[1,3]dioxol-5-ol was 96%.

Further, when the ultraviolet to visible absorption spectrum of compound (a2) was measured, the maximum absorption wavelength was 368 nm, and the absorbance at the wavelength of 368 nm was 22,500.

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

(Manufacture of film)
A single screw extruder equipped with a gear pump and filter was prepared. Resin A1 was charged into this single screw extruder and melted. The molten resin A1 was passed through a gear pump and then a filter, extruded from a T-die, and passed through a cooling roll to obtain an optical film with a thickness of 20 μm. The obtained optical film was evaluated by the method described above.

[Example 2]
An optical film with a thickness of 20 μm was obtained and evaluated in the same manner as in Example 1 except that the following items were changed in the production of resin A.
- The amount of cycloolefin resin C1 was changed to 94 parts.
- Instead of 8 parts of compound (a1), compound (a2) as an ultraviolet absorber produced in Production Example 2 (a compound containing a sesamol structure and a benzotriazole structure, in the formula (1), 6 parts of a compound in which R ¹ is a methylcarbonyloxyethyl group was used.

[Example 3]
An optical film with a thickness of 15 μm was obtained and evaluated in the same manner as in Example 1, except that the following items were changed in the production of Resin A and the film production conditions were adjusted.
- Instead of 92 parts of cycloolefin resin C1, 93 parts of cycloolefin resin C2 ("Arton" manufactured by JSR Corporation) containing 99% by weight or more of a cycloolefin polymer as an alicyclic structure-containing polymer was used.
-The amount of compound (a1) was changed to 7 parts.

[Example 4]
The cycloolefin resin C1 was prepared as the thermoplastic resin B1 and the thermoplastic resin B2. As resin A, the resin A1 was prepared. Three single-screw extruders equipped with gear pumps and filters were prepared. The resin C1, resin A1, and resin C1 were respectively charged into three single-screw extruders, melted, and passed through a gear pump and then a filter. Next, the molten resin C1, resin A1, and resin C1 are coextruded through a T-die having a three-layer flow path and passed through a cooling roll to form (layer of resin C1/layer of resin A1/layer of resin C1). An optical film having a thickness of 34 μm having a layer structure of 1) was obtained and evaluated. The thickness of the resin A1 layer was 20 μm.

[Example 5]
As thermoplastic resin B1 and thermoplastic resin B2, 98.5 parts of dried cycloolefin resin C1 and compound (a1) as an ultraviolet absorber produced in Production Example 1 (in formula (1)) , and 1.5 parts of a compound in which R ¹ is a hydrogen atom) were mixed using a twin-screw extruder to prepare a resin. As resin A, resin A2 was prepared by changing the following matters in the manufacturing method of resin A1.
- The amount of cycloolefin resin C1 was changed to 93 parts.
-The amount of compound (a1) was changed to 7 parts.
Using these resins, an optical film with a thickness of 34 μm was obtained in the same manner as in Example 4, except that the film manufacturing conditions were adjusted, and this was evaluated. The thickness of the resin A2 layer was 20 μm.

[Example 6]
As Resin A, Resin A3 was produced in the same manner as in the production of Resin A1, except that the following items were changed.
- The amount of cycloolefin resin C1 was changed to 95 parts.
-The amount of compound (a1) was changed to 5 parts.
An optical film with a thickness of 90 μm was obtained in the same manner as in Example 4, except that resin A3 was used instead of resin A1 and the film manufacturing conditions were adjusted. EX10-B) manufactured by Seisakusho Co., Ltd.) to obtain an optical film with a thickness of 58 μm, which was evaluated. The thickness of the resin A3 layer was 30 μm.

[Example 7]
As Resin A, Resin A4 was produced in the same manner as in the production of Resin A1, except that the following items were changed.
- The amount of cycloolefin resin C1 was changed to 89 parts.
-The amount of compound (a1) was changed to 11 parts.
An optical film with a thickness of 35 μm was obtained in the same manner as in Example 4, except that resin A4 was used instead of resin A1 and the film manufacturing conditions were adjusted. EX10-B) manufactured by Seisakusho Co., Ltd.) to obtain an optical film with a thickness of 24 μm, which was evaluated. The thickness of the resin A4 layer was 10 μm.

[Example 8]
An optical film with a thickness of 40 μm was obtained in the same manner as in Example 4, except that the film manufacturing conditions were adjusted, and then this optical film was stretched using a biaxial stretching device (EX10-B manufactured by Toyo Seiki Seisakusho Co., Ltd.). An optical film having a thickness of 27 μm was obtained by stretching and evaluated. The thickness of the resin A1 layer was 13 μm.

[Comparative example 1]
An optical film with a thickness of 20 μm was obtained and evaluated in the same manner as in Example 1, except that the following items were changed in the production of Resin A and the film production conditions were adjusted.
- Polyethylene terephthalate ("SA-8339P" manufactured by Unitika) was used instead of the cycloolefin resin C1.
- Instead of compound (a1), a triazine-based ultraviolet absorber ("ADEKA Stab (registered trademark) LA-F70" manufactured by ADEKA) was used.

[Comparative example 2]
An optical film with a thickness of 20 μm was obtained and evaluated in the same manner as in Example 1 except that the following items were changed in the production of resin A.
- Instead of 92 parts of cycloolefin resin C1, 90.5 parts of polyethylene terephthalate ("SA-8339P" manufactured by Unitika) was used.
・Instead of 8 parts of compound (a1), 8 parts of a triazine-based ultraviolet absorber ("ADK STAB (registered trademark) LA-F70" manufactured by ADEKA) and 8 parts of an indole-based compound ("BONASORB (registered trademark)" manufactured by Orient Chemical Co., Ltd.) UA-3911'') was used.

[Comparative example 3]
An optical film with a thickness of 20 μm was obtained and evaluated in the same manner as in Example 1, except that the following items were changed in the production of Resin A and the film production conditions were adjusted.
- The amount of cycloolefin resin C1 was changed to 98.5 parts.
- Instead of 8 parts of compound (a1), 1.5 parts of an indole compound ("BONASORB (registered trademark) UA-3911" manufactured by Orient Chemical Industry Co., Ltd.) was used.

[Comparative example 4]
As Resin A, Resin A5 was produced in the same manner as in the production of Resin A1 except for the following changes.
- The amount of cycloolefin resin C1 was changed to 98.5 parts.
- Instead of 8 parts of compound (a1), 1.5 parts of an indole compound ("BONASORB (registered trademark) UA-3911" manufactured by Orient Chemical Industry Co., Ltd.) was used.
An optical film with a thickness of 34 μm was obtained and evaluated in the same manner as in Example 4, except that resin A5 was used instead of resin A1 and the film manufacturing conditions were adjusted. The thickness of the resin A5 layer was 20 μm.

The results of Examples and Comparative Examples are shown in the table below. The abbreviations in the table below have the following meanings.
C1: Cycloolefin resin (“Zeonor” manufactured by Nippon Zeon Co., Ltd.)
C2: Cycloolefin resin (“Arton” manufactured by JSR)
a1: Compound (a1) produced in Production Example 1
a2: Compound (a2) produced in Production Example 2
LA-F70: “ADEKA Stab (registered trademark) LA-F70” manufactured by ADEKA
UA-3911: “BONASORB (registered trademark) UA-3911” manufactured by Orient Chemical Industry Co., Ltd.
Tmax (300-410): Maximum light transmittance (%) at wavelengths from 300 nm to 410 nm
T(430): Light transmittance (%) at a wavelength of 430 nm
Increase rate R: Increase rate R (%/nm) of light transmittance at a wavelength of 410 nm or more and 420 nm or less

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 is 80% or more, and the increase rate of light transmittance at a wavelength of 410 nm or more and 420 nm or less is 4.0%/nm or more. The single-layer optical films of Examples 1, 2, and 3 can efficiently cut out ultraviolet light contained in external light without interfering with light from an organic EL image display device. It can be seen that this protects the display elements and the like of the organic EL image display device from ultraviolet rays, and that the image display device can display clearly without substantially changing the display hue.
In addition, 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 is 80% or more, and the rate of increase in light transmittance at a wavelength of 410 nm or more and 420 nm or less is 4.0%/ The multilayer optical films of Examples 4, 5, 6, 7, and 8, which have a particle size of 5 nm or more, efficiently cut ultraviolet light contained in external light without interfering with light from an organic EL image display device. can. It can be seen that this protects the display elements and the like of the organic EL image display device from ultraviolet rays, and that the image display device can display clearly without substantially changing the display hue.

100: Optical film 101: Resin layer 101U: Surface 102: Resin layer 102D: Surface 103: Resin layer 210: Polarizing plate 211: Optical film 214: Polarizer 214U: Surface 220: Polarizing plate 221: Optical film 224: Polarizer 224D : Surface 224U : Surface 225 : Retardation layer 310 : Image display device 316 : Image display element 320 : Image display device 326 : Image display element

Claims (5)

An organic electroluminescent image display device comprising a polarizing plate including an optical film and a polarizer,
The optical film includes a resin layer A,
The resin layer A is formed from resin A,
The resin A contains 50% by weight or more of an alicyclic structure-containing polymer and 4.0% by weight or more and 20% by weight or less of an ultraviolet absorber,
The ultraviolet absorber includes a compound containing a sesamol structure and a benzotriazole structure,
The optical film has a light transmittance of 10% or less at a wavelength of 300 nm or more and 410 nm or less, a light transmittance of 80% or more at a wavelength of 430 nm, and an increase rate of light transmittance at a wavelength of 410 nm or more and 420 nm or less. 0%/nm or more,
Organic electroluminescent image display device. The optical film further includes a resin layer B1 and a resin layer B2,
The resin layer B1 is provided on one surface of the resin layer A,
The resin layer B2 is provided on the other surface of the resin layer A,
The resin layer B1 is formed from a thermoplastic resin B1 in which the content of an ultraviolet absorber is 3.0% by weight or less,
The organic electroluminescent image display device according to claim 1, wherein the resin layer B2 is formed from a thermoplastic resin B2 having a content of ultraviolet absorber of 3.0% by weight or less. The organic electroluminescent image display device according to claim 2, wherein the optical film is a coextruded film. The organic electroluminescent image display device according to any one of claims 1 to 3 , wherein the optical film has an in-plane retardation Re (590) of 0.1 nm or more at a wavelength of 590 nm. The organic electroluminescent image display device according to any one of claims 1 to 4 , wherein the polarizing plate further includes a retardation layer C having an in-plane retardation Re (590) of 70 nm or more at a wavelength of 590 nm. .

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