TW202011059A - Optical film and production method therefor, and polarization plate - Google Patents

Abstract

This optical film comprises a first outer resin layer, a middle resin layer containing a UV light absorbing agent and a visible light absorbing agent, and a second outer resin layer, in this order, wherein: the UV light absorbing agent has a maximum absorption wavelength, which is the maximum in a wavelength region of between 320 nm and 410 nm inclusive, in a wavelength region of 320 nm or more but less than 380 nm; the visible light absorbing agent has a maximum absorption wavelength, which is the maximum in a wavelength region of between 320 nm and 410 nm inclusive, in a wavelength region of between 380 nm and 410 nm inclusive; and the light transmittance of the optical film, for wavelengths from 300 nm to 390 nm, is 1% or less.

Description

Optical film, manufacturing method thereof and polarizing plate

The invention relates to an optical film, a method for manufacturing the same, and a polarizing plate.

In an image display device, in order to protect the components of the device from ultraviolet rays, an optical film having the ability to block ultraviolet rays may be provided. Such optical films are generally formed of resins containing ultraviolet absorbers. Therefore, this optical film has the ability to absorb ultraviolet rays incident on the film, and as a result, has the ability to weaken the ultraviolet rays penetrating the film. (Refer to Patent Documents 1 to 4).

"Patent Literature" "Patent Document 1" Japanese Patent Publication No. 2017-168430 "Patent Document 2" Japanese Patent Publication No. 2017-187619 "Patent Document 3" International Patent Publication No. 2017/150739 "Patent Document 4" Japanese Patent Publication No. 2018-4789

In Patent Document 4, the applicant proposes an optical film having a three-layer structure of "a resin layer containing an ultraviolet absorber and outer layer bodies provided on both sides of this resin layer". According to this optical film, since the movement of the ultraviolet absorber is hindered by the outer layer body, it is possible to suppress the bleeding of the ultraviolet absorber.

In addition, the applicant proposed in Patent Document 4 to use a light absorber having absorption at a specific wavelength of 390 nm. If such a light absorber is used, the ability of the optical film to suppress the penetration of ultraviolet rays can be effectively improved.

The optical film described in Patent Document 4 has excellent performance as described above, but from the viewpoint of achieving a longer life, further improvement in light resistance is required.

The present invention was first created in view of the foregoing problems, and its object is to provide an optical film having excellent light resistance, a method of manufacturing the same, and a polarizing plate provided with the optical film, which can suppress penetration of ultraviolet rays and bleed out.

The inventor has made intensive studies to solve the aforementioned problems. As a result, the present inventors found that, in an optical film including a first outer resin layer, an intermediate resin layer, and a second outer resin layer in this order, the light transmittance of the optical film at a wavelength of 300 nm to 390 nm becomes By making the intermediate resin layer contain the ultraviolet absorber and the visible light absorber in a manner below the specified value, the aforementioned problems can be solved, and the present invention has been completed.

That is, the present invention includes the following.

[1] An optical film comprising an first outer resin layer, an intermediate resin layer containing an ultraviolet absorber and a visible light absorber, and a second outer resin layer in sequence, wherein The aforementioned ultraviolet absorber has a maximum maximum absorption wavelength in the band above 320 nm and below 410 nm in the band above 320 nm and below 380 nm, and the aforementioned visible light absorber in the band above 380 nm and below 410 nm It has a maximum maximum absorption wavelength in the wavelength band above 320 nm and below 410 nm, and the light transmittance of the aforementioned optical film at a wavelength of 300 nm to 390 nm is below 1%.

[2] The optical film according to [1], wherein the intermediate resin layer includes a first intermediate resin layer containing the visible light absorber and a second intermediate resin layer containing the ultraviolet absorber.

[3] The optical film according to [1] or [2], wherein the first outer resin layer, the intermediate resin layer, and the second outer resin layer include a polymer containing an alicyclic structure.

[4] A polarizing plate including a polarizer and the optical film as described in any one of [1] to [3].

[5] A polarizing plate with: An optical film and a polarizer provided on any surface of the optical film, wherein the optical film includes a first outer resin layer, a first intermediate resin layer containing a visible light absorber, a second intermediate resin layer containing an ultraviolet absorber, and In the second outer resin layer, the ultraviolet absorber has a maximum maximum absorption wavelength in the wavelength band from 320 nm to 410 nm in the wavelength band from 320 nm to 380 nm, and the visible light absorber is from 380 nm to The wavelength band below 410 nm has the maximum maximum absorption wavelength in the band above 320 nm and below 410 nm, and the light transmittance of the aforementioned optical film at a wavelength of 300 nm to 390 nm is below 1%.

[6] A method for manufacturing an optical film, which is the method for manufacturing an optical film as described in any one of [1] to [3], including: The first outer resin layer, the intermediate resin layer, and the second outer resin layer are formed by a co-extrusion method.

According to the present invention, it is possible to provide an optical film that can suppress penetration of ultraviolet rays and bleed out and has excellent light resistance, a method for manufacturing the same, and a polarizing plate including the optical film.

The 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 shown below, and can be implemented with any changes without departing from the scope of the patent application of the present invention and its equivalent scope.

In the following description, unless otherwise noted, the so-called "polarizing plate" includes not only rigid members but also members that are flexible like resin films.

[1. Overview of optical film]

FIG. 1 is a schematic cross-sectional view of an optical film 100 related to an embodiment of the present invention. As shown in FIG. 1, the optical film 100 includes a first outer resin layer 110, an intermediate resin layer 120 and a second outer resin layer 130 in this order in the thickness direction. Generally, the first outer resin layer 110 and the intermediate resin layer 120 are directly connected without interposing the other layers, and the intermediate resin layer 120 and the second outer resin layer 130 are directly connected without interposing the other layers.

The intermediate resin layer 120 includes an ultraviolet absorber and a visible light absorber in combination. The so-called ultraviolet absorber is a compound that "has a maximum absorption wavelength in the wavelength band from 320 nm to 410 nm in the wavelength band from 320 nm to 380 nm." In addition, the so-called visible light absorber refers to a compound that has a maximum maximum absorption wavelength in the wavelength band from 320 nm to 410 nm in the wavelength band from 380 nm to 410 nm. Here, the so-called "maximum maximum absorption wavelength" means that the degree of absorption is the maximum absorption wavelength. Furthermore, the intermediate resin layer 120 contains the ultraviolet absorber and the visible light absorber in combination, and the light transmittance of the optical film at a wavelength of 300 nm to 390 nm is usually 1% or less.

According to such an optical film 100, the penetration of ultraviolet rays can be suppressed. In addition, since the first outer resin layer 110 and the second outer resin layer 130 hinder the movement of the ultraviolet absorber and the visible light absorber contained in the intermediate resin layer 120, the ultraviolet absorber and the visible light absorber can be prevented from exuding.

Furthermore, the optical film 100 is excellent in light resistance. In particular, compared to conventional films that use only ultraviolet absorbers that absorb in the bands above 320 nm and below 380 nm and the bands above 380 nm and below 410 nm, ultraviolet absorbers and visible light absorbers are used. The optical film 100 included in combination can achieve particularly excellent light resistance.

2 is a schematic cross-sectional view of an optical film 200 related to another embodiment of the present invention. In the optical film 200 shown in FIG. 2, the same components as the optical film 100 shown in FIG. 1 are marked with the same symbols as those used in FIG. 1. As shown in FIG. 2, the intermediate resin layer 220 of the optical film 200 may also have a multilayer structure. For example, as shown in FIG. 2, the intermediate resin layer 220 may also include a first intermediate resin layer 221 containing a visible light absorber and a second intermediate resin layer 222 containing an ultraviolet absorber. In this case, the intermediate resin layer 220 preferably includes only the first intermediate resin layer 221 and the second intermediate resin layer 222. According to this, it is preferable that the first intermediate resin layer 221 and the second intermediate resin layer 222 are directly connected without interposing other layers.

[2. First outer resin layer]

The first outer resin layer is a layer formed of resin on one side of the intermediate resin layer. The resin contained in the first outer resin layer is usually a thermoplastic resin. Accordingly, the resin contained in the first outer resin layer usually contains a thermoplastic polymer.

Examples of the polymer include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyarylene sulfide such as polyphenylene sulfide; polyvinyl alcohol; Polycarbonate; Polyarylate; Cellulose ester polymer, polyether satin; Polysatin; Polyarylene satin; Polyvinyl chloride; Polymers containing alicyclic structures such as norbornene-based polymers; Rod-shaped liquid crystal polymers, etc. . One type of polymer may be used alone, or two or more types may be combined in any ratio. In addition, the polymer may be a homopolymer or a copolymer. Among these, in terms of excellent mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability, and lightness, a polymer containing an alicyclic structure is preferred.

For a polymer containing an alicyclic structure, the structural unit of the polymer contains an alicyclic structure. The polymer containing an alicyclic structure is generally excellent in moisture and heat resistance. Therefore, by using a polymer containing an alicyclic structure, the moisture resistance of the optical film can be optimized.

The polymer containing an alicyclic structure may have an alicyclic structure in the main chain or an alicyclic structure in the side chain. 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 the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure. Among them, from the viewpoint of mechanical strength and heat resistance, a naphthenic structure and a cycloalkene structure are preferable, and a naphthenic structure is particularly preferable.

The number of carbon atoms constituting the alicyclic structure is "each alicyclic structure is preferably 4 or more, preferably 5 or more, and preferably 30 or less, preferably 20 or less, 15 The range below is particularly good". When the number of carbon atoms constituting the alicyclic structure is within this range, the mechanical strength, heat resistance, and moldability of the resin including the polymer containing the alicyclic structure can be highly balanced.

In the polymer containing an alicyclic structure, the proportion of structural units having an alicyclic structure is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. When the proportion of structural units having an alicyclic structure in the polymer containing an alicyclic structure is within this range, the resin containing the polymer containing an alicyclic structure has good transparency and heat resistance.

Examples of polymers containing an alicyclic structure include: norbornene-based polymers, monocyclic cyclic olefin-based polymers, cyclic conjugated diene-based polymers, vinyl alicyclic hydrocarbon polymers, and the like Hydride. Among these, since transparency and moldability are good, the norbornene-based polymer and its hydride are preferred.

As examples of the norbornene-based polymers and their hydrides, ring-opening polymers and their hydrides of monomers with a reduced-ene structure can be cited; addition polymers of monomers with a reduced-ene structure and their hydrides Hydride. In addition, as an example of a ring-opening polymer having a monomer having a reduced ene structure, a ring-opening homopolymer having one type of monomer having a reduced ene structure, and two or more types of monomers having a reduced ene structure Ring-opening copolymers, as well as monomers with a reduced ene structure and any monomers that can be copolymerized therewith. In addition, as an example of an addition polymer of a monomer having a reduced ene structure, an addition homopolymer of one type of monomer having a reduced ene structure, and two or more types of addition polymers having a reduced ene structure can be cited. Addition copolymers of monomers, as well as addition copolymers of monomers with a reduced ene structure and any monomers that can be copolymerized therewith. Examples of such polymers include those disclosed in Japanese Patent Publication No. 2002-321302. Among these, the hydrogenated product of a ring-opening polymer having a monomer having a reduced ene structure is particularly suitable from the viewpoint of formability, heat resistance, low moisture absorption, dimensional stability, and light weight.

Examples of suitable specific examples of norbornene-based polymers and these hydrides include "ZEONOR" manufactured by Japan Rion Corporation; "ATRON" manufactured by JSR Corporation; "TOPAS" manufactured by TOPAS ADVANCED POLYMERS, etc.

The weight-average molecular weight (Mw) of the polymer is preferably 10,000 or more, preferably 15,000 or more, more preferably 20,000 or more, and preferably 100,000 or less, preferably 80,000 or less, especially 50,000 or less . When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the layer containing the polymer can be highly balanced.

The molecular weight distribution (Mw/Mn) of the polymer is preferably 1.2 or more, preferably 1.5 or more, more preferably 1.8 or more, and preferably 3.5 or less, preferably 3.0 or less, especially 2.7 or less good. Here, Mn represents the number average molecular weight. When the molecular weight distribution is equal to or higher than the lower limit of the aforementioned range, the productivity of the polymer can be improved, and the manufacturing cost can be suppressed. Moreover, when it is below the upper limit, the amount of low-molecular components becomes small, so that slack when exposed to high temperatures can be suppressed, and the stability of the layered body containing the polymer can be improved.

The aforementioned weight-average molecular weight (Mw) and number-average molecular weight (Mn) were obtained by measuring the weight-average molecular weight in terms of polyisoprene or polystyrene by gel permeation chromatography using cyclohexane as a solvent. In the aforementioned gel permeation chromatography, when the sample is not dissolved in cyclohexane, toluene can also be used as a solvent.

The glass transition temperature of the polymer is preferably 100°C or higher, preferably 110°C or higher, more preferably 120°C or higher, and preferably 170°C or lower, preferably 150°C or lower, preferably 140°C or lower Is particularly good. When the glass transition temperature of the polymer is above the lower limit of the aforementioned range, the durability of the optical film in a high-temperature environment can be improved, and when it is below the upper limit of the aforementioned range, the optical film can be easily processed Extension processing.

The refractive index of the polymer is preferably 1.45 or more, preferably 1.48 or more, particularly preferably 1.50 or more, and preferably 1.60 or less, preferably 1.58 or less, and particularly preferably 1.54 or less. When the refractive index of the polymer falls within the aforementioned range, when the optical film is used as the polarizer protective film, it becomes easy to reduce the difference in refractive index between the optical film and the polarizer, and the transmittance of the polarizer can be increased.

The saturated water absorption rate of the polymer is preferably 0.03% by weight or less, more preferably 0.02% by weight or less, and particularly preferably 0.01% by weight or less. In the case where the saturated water absorption rate is in the aforementioned range, it is possible to reduce the temporal change of the optical characteristics such as the retardation of the layered body including this polymer. In addition, when an optical film is used as a polarizer protective film, the deterioration of the polarizing plate and the image display device can be suppressed, and the display of the image display device can be stably maintained for a long period of time.

Saturated water absorption rate is a value expressed by the percentage of the weight increased by immersing the sample in water at a certain temperature for a certain period of time relative to the weight of the test piece before immersion. Usually, it is immersed in water at 23°C for 24 hours and then measured. The saturated water absorption rate of the polymer can be adjusted to the aforementioned range by, for example, reducing the number of polar groups in the polymer. Accordingly, from the viewpoint of further reducing the saturated water absorption rate, it is preferable that the polymer contained in the resin does not contain a polar group.

The amount of polymer in the resin contained in the first outer resin layer is preferably 90.0% by weight to 100% by weight, and preferably 95.0% by weight to 100% by weight. When the amount of the polymer is in the aforementioned range, the moisture resistance and mechanical strength of the optical film can be effectively improved.

The resin contained in the first outer resin layer may further comprise any of the above-mentioned polymers in combination with any component. Examples of the optional components include plasticizers, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, and surfactants. These can be used alone or in combination of two or more at any ratio. However, it is desirable that the first outer resin layer does not contain ultraviolet absorbers and visible light absorbers.

The thickness of the first outer resin layer is preferably 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and preferably 10 μm or less, preferably 7 μm or less, preferably 5 μm The following is particularly preferred. When the thickness of the first outer resin layer is equal to or greater than the lower limit of the aforementioned range, the ultraviolet absorber and the visible light absorber contained in the intermediate resin layer can be effectively suppressed from bleeding out. In addition, when the thickness of the first outer resin layer is equal to or less than the upper limit of the aforementioned range, the intermediate resin layer becomes relatively thick, so that the ability of the optical film to suppress the penetration of ultraviolet rays is easily improved.

[3. Intermediate resin layer]

The intermediate resin layer is a layer formed of a resin containing an ultraviolet absorber and a visible light absorber. The resin contained in the intermediate resin layer is usually a thermoplastic resin. Accordingly, the resin contained in the intermediate resin layer usually contains a thermoplastic polymer, an ultraviolet absorber, and a visible light absorber.

As the polymer contained in the intermediate resin layer, any polymer selected from the range described for the polymer contained as the first outer resin layer may be used. With this, the intermediate resin layer can also obtain the same advantages as those described in the description of the polymer contained in the first outer resin layer. Among them, it is preferable to use the same polymer as the polymer contained in the first outer resin layer as the polymer contained in the intermediate resin layer. Thereby, it is easy to improve the bonding strength of the intermediate resin layer and the first outer resin layer, and to suppress the reflection of light at the interface between the intermediate resin layer and the first outer resin layer.

The amount of polymer in the resin contained in the intermediate resin layer is preferably 80% by weight or more, preferably 82% by weight or more, more preferably 84% by weight or more, and preferably 90% by weight or less, It is preferably 88% by weight or less, more preferably 86% by weight or less. In the case where the amount of polymer falls within the aforementioned range, the moisture and heat resistance of the optical film can be effectively improved. According to this, when an optical film is used as a polarizer protective film, the durability of the polarizing plate under humidified conditions can be improved.

Ultraviolet absorbers have more than one maximum absorption wavelength in the wavelength band above 320 nm and less than 380 nm. Moreover, the maximum absorption maximum wavelength of the ultraviolet absorber in the band above 320 nm and less than 380 nm is the maximum absorption maximum wavelength in the band above 320 nm and below 410 nm. The ultraviolet absorber satisfying this requirement has the ability to effectively absorb ultraviolet rays with a wavelength of more than 320 nm and less than 380 nm.

The ultraviolet absorber preferably has a small absorption in the wavelength band greater than 410 nm. Specifically, the total light transmittance of the optical film measured in the wavelength range of 430 nm to 700 nm can be set to the degree of the specified high range described later, so as to The absorption of the ultraviolet absorber is small. This allows the optical film to function as an optical component such as a polarizer protective film.

Generally, as ultraviolet absorbers, organic compounds are used. Hereinafter, the ultraviolet absorber as an organic compound is sometimes referred to as an "organic ultraviolet absorber". By using organic ultraviolet absorbers, it is generally possible to increase the light transmittance of optical films at visible wavelengths and reduce the haze of optical films.

Examples of the organic ultraviolet absorber include tri-based ultraviolet absorbers, diphenyl ketone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, acrylonitrile-based ultraviolet absorbers, and salicylate-based ultraviolet absorbers. Cyanoacrylate ultraviolet absorber, naphthalene imide ultraviolet absorber, phthalocyanine ultraviolet absorber, etc. Among them, from the viewpoint of remarkably obtaining the desired effect of the present invention, benzotriazole-based ultraviolet absorbers and tri-based ultraviolet absorbers are preferred.

Examples of the benzotriazole ultraviolet absorber include: 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotri Oxazol-2-yl)phenol], 2-[3,5-bis(tertiary butyl)-2-hydroxyphenyl]-5-chlorobenzotriazole, 2-(2H-benzotriazole-2 -Yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazole- 2-yl-4,6-bis(tertiary butyl)phenol, 2-[5-chloro-(2H)-benzotriazol-2-yl]-4-methyl-6-(tertiary butyl )Phenol, 2-(2H-benzotriazol-2-yl)-4,6-bis(tertiary butyl)phenol, 2-(2H-benzotriazol-2-yl)-4-(1 ,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthaloamide Iminomethyl)phenol, 3-[3-(2H-benzotriazol-2-yl)-5-tertiary butyl-4-hydroxyphenyl] propionic acid methyl ester/polyethylene glycol 300 The reaction product, 2-(2H-benzotriazol-2-yl)-6-(linear and side chain dodecyl)-4-cresol, etc. Examples of commercially available products of such triazole-based ultraviolet absorbers include "ADEKA STAB LA-31" (maximum absorption wavelength 350 nm) manufactured by ADEKA Corporation.

Examples of tri-based ultraviolet absorbers include 2-(2-hydroxy-4-hexyloxyphenyl)-4,6-diphenyl symmetric tri-, 2-(2-hydroxy-4-propoxy) Yl-5-methylphenyl)-4,6-bis(2,4-dimethylphenyl) symmetric tris, 2-(2-hydroxy-4-hexyloxyphenyl)-4,6- Biphenylphenyl symmetric tris, 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl) symmetric tri𠯤, 2,4-diphenyl-6-(2-hydroxy- 4-ethoxyphenyl) symmetrical tri, 2,4-diphenyl-6-(2-hydroxy-4-propoxyphenyl) symmetrical tri, 2,4-diphenyl-6-( 2-Hydroxy-4-butoxyphenyl) symmetrical tri, 2,4-bis(2-hydroxy-4-octyloxyphenyl)-6-(2,4-dimethylphenyl) symmetrical tri 𠯤, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl) symmetric tri 𠯤, 2,4,6-tris(2-hydroxy-4-octyloxyphenyl ) Symmetrical trio, 2-(4-isooctyloxycarbonylethoxyphenyl)-4,6-diphenyl symmetrical trio, 2-(4,6-diphenyl symmetrical trio) )-5-(2-(2-ethylhexyloxy)ethoxy)phenol and the like. As a commercially available product of such a triple UV absorber, for example, "ADEKA STAB LA-F70" (maximum absorption wavelength 357 nm) manufactured by ADEKA Corporation can be mentioned.

One type of ultraviolet absorber may be used alone, or two or more types may be used in combination at any ratio.

The amount of the ultraviolet absorber in the resin contained in the intermediate resin layer can be arbitrarily set within a range that can confine the light transmittance of the optical film with a wavelength of 300 nm to 390 nm to a desired range. Specifically, the amount of the ultraviolet absorber in the resin contained in the intermediate resin layer is preferably 1% by weight or more, preferably 2% by weight or more, more preferably 3% by weight or more, and 10% by weight % Or less is preferable, and 7% by weight or less is more preferable, and 5% by weight or less is particularly preferable. When the amount of the ultraviolet absorber is more than the lower limit of the aforementioned range, the optical film can effectively suppress the penetration of ultraviolet rays with a wavelength of 300 nm to 390 nm. In addition, when the amount of the ultraviolet absorber is equal to or less than the upper limit of the aforementioned range, it is easy to increase the light transmittance of the optical film at the wavelength of visible light. In addition, in the manufacture of the optical film, since gelation of the resin caused by the ultraviolet absorber can be suppressed, it is easy to suppress the occurrence of fish eyes in the optical film. Here, the so-called fisheye refers to a foreign substance that may be generated inside the optical film.

The visible light absorber has more than one maximum absorption wavelength in the wavelength band from 380 nm to 410 nm. Moreover, the maximum maximum absorption wavelength of the visible light absorber in the band above 320 nm and below 410 nm is the maximum maximum absorption wavelength in the band above 380 nm and below 410 nm. Visible light absorbers that meet this requirement have the ability to effectively absorb visible light with wavelengths above 380 nm and below 410 nm.

The visible light absorber preferably has a small absorption in a wavelength band greater than 410 nm. Specifically, the total light transmittance of the optical film measured in the wavelength range of 430 nm to 700 nm can be set to the degree of the specified high range described later, so as to The absorption of the visible light absorber is preferably small. This allows the optical film to function as an optical component such as a polarizer protective film.

Generally, as a visible light absorber, an organic compound is used. Hereinafter, the visible light absorber as an organic compound is sometimes referred to as an “organic visible light absorber”. By using an organic visible light absorber, the light transmittance of the optical film at the visible light wavelength can generally be increased, and the haze of the optical film can be reduced.

Examples of the visible light absorber include a formimide-based visible light absorber, an indole-based visible light absorber, a cinnamic acid-based visible light absorber, a pyrimidine-based visible light absorber, and a porphyrin-based visible light absorber. Among them, from the viewpoint of remarkably obtaining the desired effect of the present invention, the indole-based visible light absorber is preferred.

Examples of the indole-based visible light absorber include those described in Japanese Patent No. 2846091. Examples of commercially available products of such indole-based visible light absorbers include "BONASORB UA-3911" (maximum absorption wavelength 392 nm), "BONASORB UA-3912" (maximum absorption wavelength 386 nm) manufactured by ORIENT Chemical Company Wait.

One type of visible light absorber may be used alone, or two or more types may be used in combination at any ratio.

The amount of the visible light absorber in the resin contained in the intermediate resin layer can be arbitrarily set within a range where the light transmittance of the optical film at a wavelength of 300 nm to 390 nm can be confined to a desired range. Specifically, the amount of the visible light absorber in the resin contained in the intermediate resin layer is preferably 1% by weight or more, preferably 2% by weight or more, more preferably 3% by weight or more, and 10% by weight % Or less is preferable, and 7% by weight or less is more preferable, and 5% by weight or less is particularly preferable. When the amount of the visible light absorber is more than the lower limit of the aforementioned range, the optical film can also be used to suppress light with a wavelength of 380 nm or more, not just general ultraviolet light with a wavelength of less than 380 nm. According to this, the penetration of ultraviolet rays with a wavelength of 300 nm to 390 nm can be effectively suppressed. In addition, when the amount of the visible light absorber is less than or equal to the upper limit of the aforementioned range, it is easy to increase the light transmittance of the optical film at the visible light wavelength. Moreover, in the production of the optical film, since gelation of the resin caused by the visible light absorber can be suppressed, it is easy to suppress the generation of fish eyes in the optical film.

In the resin contained in the intermediate resin layer, the total amount of the ultraviolet absorber and the visible light absorber can be arbitrarily set within a range that can confine the light transmittance of the optical film at a wavelength of 300 nm to 390 nm to a desired range. Specifically, the total amount of the ultraviolet absorber and the visible light absorber in the resin contained in the intermediate resin layer is preferably 2% by weight or more, preferably 4% by weight or more, and more preferably 6% by weight or more , And preferably 20% by weight or less, preferably 14% by weight or less, and more preferably 10% by weight or less. When the total amount of the ultraviolet absorber and the visible light absorber is more than the lower limit of the aforementioned range, the penetration of ultraviolet rays with a wavelength of 300 nm to 390 nm can be effectively suppressed. In addition, when the total amount of the ultraviolet absorber and the visible light absorber is equal to or less than the upper limit of the aforementioned range, it is easy to increase the light transmittance of the optical film at the visible light wavelength. In addition, in the production of the optical film, since gelation of the resin can be suppressed, it is easy to suppress the generation of fish eyes in the optical film.

Here, a conventional optical film provided with an intermediate resin layer containing an ultraviolet absorber but not a visible light absorber is related to the present embodiment described above with an intermediate resin layer containing an ultraviolet absorber and a visible light absorber Compared with the optical film. In order to achieve the same ultraviolet blocking ability as the conventional optical film, the total amount of the ultraviolet absorber and the visible light absorber required for the optical film related to this embodiment is compared to the ultraviolet absorber contained in the conventional optical film. The amount has a smaller tendency. Accordingly, the optical film related to the above-described embodiment is also excellent in that it can reduce the amount of ultraviolet absorber and visible light absorber.

In the resin contained in the intermediate resin layer, the ratio of the amount of ultraviolet absorber to the amount of visible light absorber is within a range that can confine the light transmittance of the optical film at a wavelength of 300 nm to 390 nm to a desired range Arbitrary setting. Specifically, the amount of the visible light absorber is preferably 10 parts by weight or more relative to 100 parts by weight of the ultraviolet absorber, preferably 20 parts by weight or more, more preferably 30 parts by weight or more, and 100 parts by weight It is preferably less than 1 part by weight, preferably 80 parts by weight or less, and more preferably 60 parts by weight or less. When the amount of the visible light absorber is more than the lower limit of the aforementioned range, the penetration of ultraviolet rays with a wavelength of 300 nm to 390 nm can be effectively suppressed. In addition, when the amount of the visible light absorber is less than or equal to the upper limit of the aforementioned range, the coloring of the optical film can be suppressed.

The resin contained in the intermediate resin layer may further contain any component combined with the polymer, ultraviolet absorber and visible light absorber. Examples of the optional components include the same components as those already mentioned for the optional components contained as the resin contained in the first outer resin layer. These can be used alone or in combination of two or more at any ratio.

The intermediate resin layer may have a single-layer structure including only one layer. In the case where the intermediate resin layer has a single-layer structure, since the number of layers included in the optical film can be reduced, the manufacturing of the optical film can be simplified.

In addition, the intermediate resin layer may be a multilayer structure including two or more layers. For example, the intermediate resin layer may be a layered structure including a first intermediate resin layer containing a visible light absorber and a second intermediate resin layer containing an ultraviolet absorber. In this case, the optical film may be sequentially provided with the first outer resin layer, the first intermediate resin layer, the second intermediate resin layer, and the second outer resin layer in the thickness direction, and may be sequentially provided with the first An outer resin layer, a second intermediate resin layer, a first intermediate resin layer and a second outer resin layer. In the case of distinguishing the first intermediate resin layer containing the visible light absorber from the second intermediate resin layer containing the ultraviolet absorber, the order of passing light can be controlled, and the light resistance of the optical film can be further improved.

The thickness of the intermediate resin layer is preferably 5 μm or more, preferably 7 μm or more, more preferably 10 μm or more, and preferably 40 μm or less, preferably 30 μm or less, and 20 μm or less Especially good. When the thickness of the intermediate resin layer is more than the lower limit of the aforementioned range, the ability of the optical film to suppress the penetration of ultraviolet rays is easily improved. In addition, when the thickness of the intermediate resin layer is equal to or less than the upper limit of the aforementioned range, the optical film can be made thinner.

In particular, when the intermediate resin layer includes a first intermediate resin layer containing a visible light absorber and a second intermediate resin layer containing an ultraviolet absorber, the thickness t1 of the first intermediate resin layer and the thickness t2 of the second intermediate resin layer The ratio t1/t2 is preferably 0.5 or more, preferably 0.7 or more, more preferably 0.8 or more, and preferably 2.0 or less, 1.5 or less, and 1.3 or less. In the case where the thickness ratio t1/t2 is in the aforementioned range, curling of the optical film can be suppressed while obtaining excellent light resistance.

[4. Second outer resin layer]

The second outer resin layer is a layer formed of resin on the side of the middle resin layer opposite to the first outer resin layer. For the resin contained in the second outer resin layer, any resin selected from the range of resins described as the resin contained in the first outer resin layer is usually used. Therefore, the contained components and characteristics of the resin contained in the second outer resin layer can be selected from the ranges described as the contained components and characteristics of the resin contained in the first outer resin layer. Thereby, the second outer resin layer can also obtain the same advantages as those described in the description of the first outer resin layer.

The resin contained in the second outer resin layer may be a resin different from the resin contained in the first outer resin layer, or may be the same resin as the resin contained in the first outer resin layer. Among them, it is preferable to use the same resin as the resin contained in the first outer resin layer and the resin contained in the second outer resin layer. By using the same resin, the manufacturing cost of the optical film can be suppressed and the curl of the optical film can be suppressed.

The thickness of the second outer resin layer is made to be any thickness selected from the range described as the thickness range of the first outer resin layer. Thereby, the second outer resin layer can also obtain the same advantages as those described in the description of the thickness of the first outer resin layer. In order to suppress curling of the optical film, the thickness of the second outer resin layer is preferably the same as that of the first outer resin layer.

[5. Arbitrary layer body]

The optical film may be provided with any layer body combined with the first outer resin layer, the intermediate resin layer and the second outer resin layer as described above as required. For example, between the first outer resin layer and the middle resin layer, between the middle resin layer and the second outer resin layer, the side of the first outer resin layer opposite to the middle resin layer, the second outer resin layer An arbitrary resin layer is provided on the opposite side of the intermediate resin layer. Examples of the arbitrary resin layer include a hard coat layer, a low refractive index layer, an antistatic layer, and a refractive index matching layer.

However, from the viewpoint of thinning the optical film, the optical film is preferably a film that does not have any layer.

[6. Thickness of optical film]

The thickness of the optical film is usually 20 μm or more, preferably 23 μm or more, and more preferably 25 μm or more. Since the thickness of the optical film is larger than the aforementioned lower limit, the ability of the optical film to block ultraviolet rays can be increased. In addition, the thickness of the optical film is usually 50 μm or less, preferably 45 μm or less, and more preferably 40 μm or less. When the thickness of the optical film is equal to or less than the aforementioned upper limit, the optical film can be reduced in weight and space-saving. Moreover, even if the thickness is so thin, the penetration of ultraviolet rays can be effectively suppressed, thereby effectively protecting components susceptible to deterioration caused by ultraviolet rays (such as organic materials of organic EL display devices, etc.), which is the aforementioned optical film One of the advantages.

In addition, the optical film can adjust the ultraviolet transmittance of the entire optical film by adjusting the thickness of the intermediate resin layer. If the thickness of the intermediate resin layer is adjusted in this way, the thicknesses of the first outer resin layer and the second outer resin layer are adjusted in accordance with them, so that it is not necessary to change the thickness of the entire optical film. Accordingly, the optical film described above can be adjusted for ultraviolet transmittance without changing the thickness of the entire optical film.

[7. Physical properties of optical film]

The light transmittance of the optical film at a wavelength of 300 nm to 390 nm is usually 1% or less, preferably 0.9% or less, preferably 0.8% or less, and ideally 0%. In this way, the optical film can effectively suppress the penetration of ultraviolet rays. Therefore, when this optical film is used as a polarizer protective film, it is possible to suppress the decrease in the degree of polarization of the polarizer and suppress the coloring of the polarizer. In addition, in general, organic components contained in organic EL elements (organic electroluminescence elements) are particularly susceptible to deterioration due to long-wavelength ultraviolet rays. However, since the aforementioned optical thin film can generally effectively suppress the deterioration of the organic components contained in the organic EL element due to ultraviolet rays, the life of the organic EL display device can be extended.

The light transmittance of the optical film at a wavelength of 300 nm to 390 nm can be reduced by, for example, adjusting the types and amounts of ultraviolet absorbers and visible light absorbers or thickening the thickness of the intermediate resin layer.

The optical film has an excellent light resistance because it includes an intermediate resin layer containing a combination of an ultraviolet absorber and a visible light absorber. In particular, an optical film provided with a first intermediate resin layer containing a visible light absorber and a second intermediate resin layer containing an ultraviolet absorber is particularly excellent for light that sequentially passes through the second intermediate resin layer and the first intermediate resin layer Lightfastness. The light resistance of such an optical film is superior to the conventional optical film provided with an intermediate resin layer containing one of an ultraviolet absorber and a visible light absorber but not the other. For example, for the optical film related to the above-described implementation type, the light is irradiated from the xenon lamp at a BP temperature (black panel temperature) of 63° C. and a humidity of 50% RH at an irradiation intensity of 72 W/m ² . After 400 hours of light resistance test, it can also suppress the decrease in absorbance of this optical film at a wavelength of 390 nm. Specifically, at a wavelength of 390 nm, the residual ratio A ₁ /A ₀ ×100 (%) of the absorbance A ₁ of the optical film after the light resistance test to the absorbance A ₀ of the optical film before the light resistance test is 40% or more Good, more than 45% is better, and more than 50% is especially good.

The optical film includes a first outer resin layer and a second outer resin layer on both sides of the intermediate resin layer containing the ultraviolet absorber and the visible light absorber. According to this, the movement of the ultraviolet absorber and the visible light absorber is hindered by the first outer resin layer and the second outer resin layer. Therefore, the optical film can suppress the exudation of the ultraviolet absorber and the visible light absorber.

Optical films are generally excellent in heat resistance.

Optical films usually have excellent thickness accuracy. In general, the intermediate resin layer containing the ultraviolet absorber and the visible light absorber may have parts with different thicknesses due to changes in the resin flow and the occurrence of foreign matter. However, even if such a part is generated in the intermediate resin layer, the first outer resin layer and the second outer resin layer located on the outer side of the intermediate resin layer absorb the difference in thickness, and the thickness accuracy of the entire optical film can be suppressed decline.

From the viewpoint of stabilizing the function as an optical component, the optical film preferably has a high light transmittance in the visible light region. Specifically, the measurement of the total light transmittance of the optical film at a wavelength of 430 nm to 700 nm is preferably 70% to 100%, preferably 80% to 100%, and more preferably 90% to 100% . This total light transmittance must be measured using an ultraviolet-visible light spectrometer in the wavelength range of 430 nm to 700 nm.

For the optical film, from the viewpoint of improving the sharpness of the image of the image display device in which the optical film is installed, the haze is preferably small. The specific haze of the optical film is preferably 1% or less, preferably 0.8% or less, and particularly preferably 0.5% or less. Haze must be measured in accordance with JIS K7361-1997 using a turbidity meter.

The optical film may be an optically isotropic film that does not substantially have an in-plane retardation Re, or may be an optically anisotropic film that has an in-plane retardation Re of a size according to the application.

[8. Manufacturing method of optical film]

There are no restrictions on the manufacturing method of the optical film. The optical film can be manufactured by, for example, a manufacturing method including a step of forming a resin as a material of each layer into a layer. Examples of the resin molding method include a co-extrusion method and a co-casting method. Among these forming methods, the co-extrusion method is preferable because it has excellent manufacturing efficiency and does not easily leave volatile components in the optical film. Accordingly, the optical film is preferably manufactured by a manufacturing method including forming a first outer resin layer, an intermediate resin layer, and a second outer resin layer by a co-extrusion method.

The manufacturing method of the optical film using the co-extrusion method includes the step of co-extrusion of the resin as the material of each layer. In the co-extrusion method, the resin is extruded in a layered state in a molten state to form a first outer resin layer, an intermediate resin layer, and a second outer resin layer. In this case, examples of the resin extrusion method include a co-extrusion T-die method, a co-extrusion inflation method, and a co-extrusion lamination method. Among them, the co-extrusion T-die method is preferred.

In the co-extrusion method, the melting temperature of the extruded resin is preferably Tg+80°C or higher, preferably Tg+100°C or higher, and preferably Tg+180°C or lower, preferably Tg+150°C or lower. Here, "Tg" means the highest temperature among the glass transition temperatures of the polymers contained in the co-extruded resin. In addition, the aforementioned melting temperature means, for example, in the co-extrusion T-die method, the melting temperature of the resin in an extruder having a T-die. When the melting temperature of the extruded resin is above the lower limit of the aforementioned range, the fluidity of the resin can be sufficiently improved to optimize the moldability, and when it is below the upper limit, the deterioration of the resin can be suppressed.

The extrusion temperature should be appropriately selected according to the composition of the resin. For example, the temperature of the resin in the extruder is determined as: Tg ~ (Tg + 100 °C) at the resin inlet, (Tg + 50 °C) ~ (Tg + 170 °C) at the exit of the extruder, and the mold temperature is ( Tg+50℃)～(Tg＋170℃).

Furthermore, the arithmetic average roughness Ra of the die lips of the mold is preferably 0 μm to 1.0 μm, preferably 0 μm to 0.7 μm, and particularly preferably 0 μm to 0.5 μm. By confining the arithmetic average roughness of the die lips to the aforementioned range, it becomes easy to suppress the streak-like defects of the optical film.

In the co-extrusion method, the film-shaped molten resin extruded from the die lip is usually adhered to a cooling roller to cool and solidify it. At this time, examples of the method of adhering the molten resin to the cooling roller include, for example, an air knife method, a vacuum box method, and an electrostatic adhesion method.

In the co-extrusion method as described above, from the viewpoint of correctly controlling the thickness of each layer, the difference in the glass transition temperature of the resin of each layer included in the optical film is preferably small. Specifically, the maximum value of the absolute value of the difference in glass transition temperature (maximum interlayer ΔTg) of the resin contained in each layer is preferably 18° C. or lower, preferably 15° C. or lower, and more preferably 12° C. or lower. If the difference in the glass transition temperature of the resin of each layer is small, it is possible to suppress the disturbance of the thickness of the layer body in the junction of the flow paths in the extrusion device (the flow path of the co-extruded resin flow). According to this, thickness control can be accurately performed, and thus an optical film with excellent appearance can be easily obtained.

By forming the resin into a layer as described above, an optical film can be obtained.

In addition, the manufacturing method of the optical film may include any steps in addition to the steps described above. For example, the manufacturing method of the optical film may also include an extension process. By subjecting the optical film obtained by molding the resin as described above to extension treatment, desired optical characteristics such as retardation can be expressed in the optical film.

[9. Polarizer]

The optical film described above can be used as a retardation film, a polarizer protection film, a polarization compensation film and the like for a wide range of applications. Among them, the optical film is preferably used for the polarizer protective film. A polarizing plate that uses an optical film as a polarizer protection film, and includes a polarizer and an optical film.

FIG. 3 is a schematic cross-sectional view of a polarizing plate 300 according to an embodiment of the present invention. In the polarizing plate 300 shown in FIG. 3, the same members as the optical film 200 shown in FIG. 2 are marked with the same symbols as the user used in FIG.

As shown in FIG. 3, the polarizing plate 300 includes an optical film 200 and a polarizer 310 provided on either surface of the optical film 200. The polarizer 310 may be directly provided on the surface of the optical film 200 without interposing other layers, or may be provided indirectly through interposing any layer such as a bonding layer. Such a polarizing plate 300 is excellent in light resistance because the optical film 200 can block ultraviolet rays and protect the polarizer 310.

The polarizer 310 may also be disposed on either side of the optical film 200 and the other side. According to this, when the intermediate resin layer 220 is a multilayer structure, the optical film 200 may be provided with, for example, a first outer resin layer 110 and a first intermediate resin layer 221 including a visible light absorber from the polarizer 310 side. 2. A second intermediate resin layer 222 and a second outer resin layer 130 containing an ultraviolet absorber. Furthermore, the optical film 200 may be provided with, for example, a second outer resin layer 130, a second intermediate resin layer 222 including an ultraviolet absorber, a first intermediate resin layer 221 including a visible light absorber, and a first outer side in order from the polarizer 310 side Resin layer 110.

Such a polarizing plate 300 is generally used in a direction in which external light irradiating the polarizing plate 300 sequentially penetrates the second outer resin layer 130, the second intermediate resin layer 222, the first intermediate resin layer 221, and the first outer resin layer 110. For example, when the polarizing plate 300 is installed in an image display device (not shown), the polarizing plate 300 is disposed such that the surface 300U of the optical film 200 on the second outer resin layer 130 side faces the viewing side. If such an image display device is irradiated with external light, the external light enters the first intermediate resin layer 221 after the ultraviolet absorber contained in the second intermediate resin layer 222 absorbs the ultraviolet light. According to this, it is possible to suppress the deterioration caused by ultraviolet rays of the components such as the visible light absorber included in the first intermediate resin layer 221. Therefore, since the optical film 200 can exhibit high light resistance for a long period of time, the polarizing plate 300 having a particularly long life can be obtained.

As the polarizer 310, a film that penetrates one of two linearly polarized lights that vertically intersect in the vibration direction and absorbs or reflects the other can be used. Here, the vibration direction of linearly polarized light means the vibration direction of the electric field of linearly polarized light. To give specific examples of the polarizer 310, a film of a vinyl alcohol-based polymer such as polyvinyl alcohol and partially formalized polyvinyl alcohol may be applied in an appropriate order and by means of iodine and dichroism. Appropriate handlers such as dyeing treatment, extension treatment, cross-linking treatment due to dichroic substances such as dyes. In particular, the polarizer 310 containing polyvinyl alcohol is preferred. In addition, the thickness of the polarizer 310 is usually 5 μm to 80 μm.

The polarizing plate 300 can be manufactured by attaching the optical film 200 to the polarizing member 310. When bonding, the cement can also be used as required.

The polarizing plate 300 may further include any layer (not shown) combined with the polarizer 310 and the optical film 200 described above. For example, the polarizing plate 300 may be provided with any protective film layer (not shown) other than the optical film 200 to protect the polarizer 310. Such a protective film layer is usually provided on the surface of the polarizer 310 opposite to the optical film 200. In addition, examples of the arbitrary layer body include a hard coat layer, a low refractive index layer, an antistatic layer, and a refractive index matching layer.

The aforementioned polarizing plate can be applied to, for example, an organic EL display device (organic electroluminescence display device). Among them, it is suitably used for a medium-sized or small-sized organic EL display device and a flexible type organic EL display device.

『Examples』

The following examples are disclosed to specifically illustrate the present invention. However, the present invention is not limited to the embodiments shown below, and can be arbitrarily changed and implemented without departing from the scope of the patent application of the present invention and its equivalent scope.

In the following description, "%" and "parts" indicating amounts are based on weight unless otherwise noted. In addition, unless otherwise noted, the operations described below are performed in normal temperature and pressure atmosphere.

In the following description, unless otherwise noted, the so-called "DCP" means "tricyclo[4.3.0.1 ^2,5 ]dec-3,7-diene", and the so-called "TCD" means "tetracyclo[4.4.0.1 ^{2 ,5} .1 ^7,10 ]dodec-3-ene", the so-called "MTF" means "tetracyclo[9.2.1.0 ^2,10 .0 ^3,8 ]tetradec-3,5,7,12-tetraene ".

[Evaluation method]

(Measurement method of glass transition temperature Tg of resin)

The glass transition temperature of the resin is measured using a differential scanning calorimeter (DSC).

(Measurement method of UV transmittance)

An ultraviolet visible light near-infrared spectrophotometer ("V-7200" manufactured by Japan Spectroscopy Co., Ltd.) is used to measure the light transmittance of the optical film at a wavelength of 300 nm to 390 nm.

(Evaluation method of light resistance)

The aforementioned ultraviolet visible light near infrared spectrophotometer was used to measure the absorbance A _{0 of the} optical film at a wavelength of 390 nm.

After that, the light resistance test was performed on the second outer resin layer side of the optical film at a BP temperature of 63° C. and a humidity of 50% RH by irradiating light from a xenon lamp with an irradiation intensity of 72 W/m ² for 400 hours. Subsequently, the aforementioned ultraviolet visible light near infrared spectrophotometer was used to measure the absorbance A _{1 of the} optical film after a light resistance test at a wavelength of 390 nm.

The residual ratio of the absorbance A ₁ after the light resistance test to the absorbance A ₀ before the light resistance test was measured by the following formula. Survival rate (%) = (A ₁ /A ₀ )×100

From the value of the obtained absorbance, the light resistance was determined according to the following criteria. A: The residual rate of absorbance is 50% or more. B: The residual rate of absorbance is 40% or more and less than 50%. C: The residual rate of absorbance is 30% or more and less than 40%. D: The residual rate of absorbance was less than 30%.

(Evaluation method of exudation)

Measure the infrared absorption spectrum (IR spectrum) of the surface of the optical film. When an IR spectrum derived from an ultraviolet absorber or a visible light absorber is detected, it is determined that bleeding has occurred, and it is determined to be "bad". In addition, when the IR spectrum derived from the ultraviolet absorber or the visible light absorber is not detected, it is determined that there is no bleeding, and the determination is "good".

(Maximum ΔTg between floors)

When the optical film is manufactured by extrusion, when the difference in the glass transition temperature Tg of the resin contained in each layer of the optical film is large, in the junction where the resin of each layer in the feed block merges, it may cause Disturbed film thickness. The maximum value of the absolute value of the difference in the glass transition temperature Tg of the resin contained in each layer (maximum interlayer ΔTg) is used as an index for stably obtaining an optical film with a neat appearance.

[Production Example 1: Production of Resin J1 (COP)]

(Ring-opening polymerization)

In a reactor replaced with nitrogen, 7 parts of a mixture of DCP, TCD and MTF (DCP/TCD/MTF=55/40/5 weight ratio) and 1600 parts of cyclohexane were added. The amount of the aforementioned mixture of DCP, TCD and MTF is 1% by weight relative to the total amount of monomers used for polymerization.

Furthermore, 0.55 parts of triisobutylaluminum, 0.21 parts of isobutanol, and 0.84 parts of diisopropyl ether were added as a reaction modifier, and 3.24 parts of 1-hexene as a molecular weight modifier.

24.1 parts of a cyclohexane solution of tungsten hexachloride with a concentration of 0.65% was added here, and stirred at 55°C for 10 minutes.

Subsequently, the reaction system was maintained at 55°C, and a mixture of DCP, TCD and MTF (DCP/TCD/MTF=55/40/5 weight ratio) of 693 parts and a concentration of 0.65% was continuously dropped in the system over 150 minutes. 48.9 parts of a cyclohexane solution of tungsten hexachloride.

After that, the reaction was continued for 30 minutes to end the polymerization. With this, a ring-opening polymerization reaction liquid containing a ring-opening polymer in cyclohexane is obtained. After the polymerization, the polymerization conversion rate of the monomer measured by gas chromatography was 100% at the end of the polymerization.

(hydrogenation)

The obtained ring-opening polymerization reaction liquid was transferred to a pressure-resistant hydrogenation reactor. To this reactor, 1.4 parts of diatomite-supported nickel catalyst ("T8400RL" manufactured by Nisshin Chemical Co., Ltd., nickel bearing rate 57%) and 167 parts of cyclohexane were added to hydrogenate at 180°C and hydrogen pressure of 4.6 MPa React for 6 hours. By this hydrogenation reaction, a reaction solution containing a ring-opening polymer hydride is obtained. From this reaction solution, Radiolite #500 was used as a filter bed to filter at a pressure of 0.25 MPa (manufactured by Ishikawashima Haruma Heavy Industries Co., Ltd., product name "FUNDABAC filter") to remove the hydrogenation catalyst and obtain a colorless and transparent solution.

Subsequently, the aforementioned hydride is 0.5 parts per 100 parts of antioxidant ({3-[3,5-bis(tertiary butyl)-4-hydroxyphenyl]propionic acid}neopentyl alcohol ester, Ciba Specialty "Irganox 1010" manufactured by Chemicals Co., Ltd. is added to the obtained solution to dissolve it. Subsequently, this solution was filtered with a filter ("ZetaPlus Filter 30H" manufactured by CUNO Filter Inc., pore size 0.5 μm to 1 μm), and then filtered with another metal fiber filter (manufactured by Nichidai Corporation, pore size 0.4 μm). , To remove tiny solid components from the solution. The hydrogenation rate of the ring-opening polymer hydride is 99.9%.

Subsequently, by using a cylindrical concentration dryer (manufactured by Hitachi, Ltd.) at a temperature of 270°C and a pressure of 1 kPa or less, the solution obtained by the above filtration is treated to remove cyclohexane and other solvents from the solution. Volatile components. Then, from the mold directly bonded to the concentrator, the solid component contained in the solution was extruded into a strand in the molten state and cooled to obtain pellets of the resin J1 containing the hydride of the ring-opening polymer. The weight average molecular weight (Mw) of the hydride of the ring-opening polymer contained in the particles was 38,000, the molecular weight distribution (Mw/Mn) was 2.5, and the glass transition temperature Tg was 126°C.

[Example 1]

93 parts of dried resin J1, 5 parts of benzotriazole ultraviolet absorber ("LA-31" manufactured by ADEKA Corporation; the maximum maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 350 nm) and Two parts of the indole-based visible light absorber ("UA-3911" manufactured by ORIENT Chemical Company; the maximum maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 392 nm) are mixed using a biaxial extruder to obtain resin J2. The glass transition temperature Tg of the resin J2 is 116°C.

Prepare a single-shaft extruder equipped with gear pumps and filters. Put resin J2 in this uniaxial extruder. The resin J2 put in is melted, passes through a gear pump and a filter in order, and is supplied to a feed block connected to a T-shaped mold.

In addition, another uniaxial extruder equipped with a gear pump and a filter is prepared. In this uniaxial extruder, the dried resin J1 was placed. The introduced resin J1 is melted, passes through a gear pump and a filter in order, and is supplied to the aforementioned feed block connected to the T-shaped mold.

Resin J1 and resin J2 merge in the feed block to form a layer of each resin. After that, these resins J1 and J2 were extruded from a T-shaped die to obtain a "first outer resin layer made of resin J1 (thickness 3 μm) / an intermediate resin layer made of resin J2 (thickness 10 μm) / Optical film with a layered structure of the second outer resin layer (thickness 3 μm) made of resin J1. The optical film obtained was evaluated by the method already described above.

[Example 2]

93 parts of dried resin J1, 4 parts of three 𠯤 series ultraviolet absorber ("LA-F70" manufactured by ADEKA Corporation; the maximum maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 357 nm) and 3 parts The indole-based visible light absorber ("UA-3911" manufactured by ORIENT Chemical Company; the maximum maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 392 nm) was mixed using a biaxial extruder to obtain resin J3. The glass transition temperature Tg of the resin J3 is 115°C.

Except that the resin J3 thus obtained was used instead of the resin J2, the same operation as in Example 1 was performed to obtain an intermediate resin having "the first outer resin layer (thickness 3 μm) made of resin J1 / resin J3" Layer (thickness 10 μm) / Optical film with a layered structure of the second outer resin layer (thickness 3 μm) made of resin J1. The optical film obtained was evaluated by the method already described above.

[Example 3]

Use 97 parts of dried resin J1 and 3 parts of indole-based visible light absorber ("UA-3911" manufactured by ORIENT Chemical Company; the maximum maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 392 nm). The shaft extruder was mixed to obtain resin J4. The glass transition temperature Tg of the resin J4 is 120°C.

Prepare a single-shaft extruder equipped with gear pumps and filters. Put resin J4 in this single-shaft extruder. The introduced resin J4 is melted, passes through a gear pump and a filter in sequence, and is supplied to the aforementioned feed block connected to the T-shaped mold.

In addition, 95 parts of dried resin J1 and 5 parts of three-part ultraviolet absorbers ("LA-F70" manufactured by ADEKA Corporation; the maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 357 nm) The biaxial extruder was mixed to obtain resin J5. The glass transition temperature Tg of the resin J5 is 120°C.

Prepare another uniaxial extruder equipped with gear pump and filter. Put resin J5 in this uniaxial extruder. The resin J5 put in is melted, passes through the gear pump and the filter in order, and is supplied to the feed block connected to the T-shaped mold.

Furthermore, another uniaxial extruder equipped with a gear pump and a filter is prepared. In this uniaxial extruder, the dried resin J1 was placed. The introduced resin J1 is melted, passes through a gear pump and a filter in order, and is supplied to the aforementioned feed block connected to the T-shaped mold.

Resin J1, resin J4, and resin J5 merge in the feed block to form a layered body of each resin. After that, these resins J1, J4 and J5 were extruded from a T-shaped die to obtain a "first outer resin layer (thickness 3 μm) made of resin J1/a first intermediate resin layer made of resin J4" (Thickness 10 μm)/Second middle resin layer made of resin J5 (thickness 8 μm)/Second outer resin layer made of resin J1 (thickness 3 μm)” optical film with a layered structure. The optical film obtained was evaluated by the method already described above.

[Example 4]

The front and back sides of the optical film produced in Example 3 were reversed, and evaluation was made by the method described above. Accordingly, the optical film to be evaluated in Example 4 has the "first outer resin layer made of resin J1 (thickness 3 μm)/the second intermediate resin layer made of resin J5 (thickness 8 μm) /The first intermediate resin layer made of resin J4 (thickness 10 μm)/The second outer resin layer made of resin J1 (thickness 3 μm)” layer structure optical film.

[Example 5]

Acrylic resin ("DELPET 80NH" manufactured by Asahi Kasei Corporation; glass transition temperature 100°C) was prepared as resin J6.

93 parts of dried resin J6, 3 parts of 4 parts ultraviolet absorber ("LA-F70" manufactured by ADEKA Corporation; maximum absorption wavelength of 357 nm at a wavelength of 320 nm to 410 nm) and 3 parts The indole-based visible light absorber ("UA-3911" manufactured by ORIENT Chemical Company; the maximum maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 392 nm) was mixed using a biaxial extruder to obtain resin J7. The glass transition temperature Tg of the resin J7 is 89°C.

Prepare a single-shaft extruder equipped with gear pumps and filters. Put resin J7 in this single-shaft extruder. The resin J7 put in is melted, passes through the gear pump and the filter in order, and is supplied to the feed block connected to the T-shaped die.

In addition, another uniaxial extruder equipped with a gear pump and a filter is prepared. In this uniaxial extruder, dried resin J6 was placed. The introduced resin J6 is melted, passes through a gear pump and a filter in order, and is supplied to the aforementioned feed block connected to the T-shaped mold.

Resin J6 and resin J7 merge in the feed block to form a layer of each resin. After that, these resins J6 and J7 were extruded from a T-shaped die to obtain a "first outer resin layer made of resin J6 (thickness 3 μm) / an intermediate resin layer made of resin J7 (thickness 10 μm) / Optical film with a layered structure of the second outer resin layer (thickness 3 μm) made of resin J6. The optical film obtained was evaluated by the method already described above.

[Comparative Example 1]

Prepare a single-shaft extruder equipped with gear pumps and filters. In this uniaxial extruder, resin J2 manufactured in Example 1 was placed. The introduced resin J2 melts and is sequentially supplied to the T-shaped mold through the gear pump and the filter. After that, resin J2 was extruded from a T-shaped die to obtain an optical film having only an "intermediate resin layer (thickness 10 μm) made of resin J2". The optical film obtained was evaluated by the method already described above.

[Comparative Example 2]

Resin J1 was not supplied to the feed block using a single-axis extruder. In addition, in order to obtain an optical film of a desired thickness, the extrusion conditions from the T-shaped die are adjusted. Except for the above matters, the same operation as in Example 3 was carried out to obtain a "first intermediate resin layer made of resin J4 (thickness 10 μm) / a second intermediate resin layer made of resin J5 (thickness 10 μm) "Layer structure optical film." The optical film obtained was evaluated by the method already described above.

[Comparative Example 3]

Use 90 parts of dried resin J1 and 10 parts of indole-based visible light absorber ("UA-3911" manufactured by ORIENT Chemical Company; the maximum maximum absorption wavelength at a wavelength of 320 nm to 410 nm is 392 nm). The shaft extruder was mixed to obtain resin J8. The glass transition temperature Tg of resin J8 was 106°C.

Except that this resin J8 was used instead of resin J2, the same operation as in Example 1 was carried out to obtain a "first outer resin layer (thickness 3 μm) made of resin J1/an intermediate resin layer (thickness made of resin J8 10 μm) / Optical film with a layered structure of the second outer resin layer (thickness 3 μm) made of resin J1. The optical film obtained was evaluated by the method already described above.

[Comparative Example 4]

Except that the resin J5 manufactured in Example 3 was used instead of the resin J2, the same operation as in Example 1 was carried out to obtain a product having a "first outer resin layer (thickness 3 μm) made of resin J1/made of resin J5" Optical film with a layered structure of intermediate resin layer (thickness 10 μm)/second outer resin layer (thickness 3 μm) made of resin J1. The optical film obtained was evaluated by the method already described above.

[result]

The results of the foregoing examples and comparative examples are disclosed in Tables 1 and 2 below. In the following table, the meaning of the abbreviations is as follows. COP: polymer containing alicyclic structure. UVA: ultraviolet absorber. VLA: visible light absorber.

"Table 1" [Table 1. Results of Examples]

"Table 2" [Table 2. Results of Comparative Examples]

100, 200: optical film 110: first outer resin layer 120, 220: middle resin layer 130: second outer resin layer 221: First intermediate resin layer 222: Second intermediate resin layer 300: polarizer 310: polarizer

<FIG. 1> FIG. 1 is a schematic cross-sectional view of an optical film related to an embodiment of the present invention. <FIG. 2> FIG. 2 is a schematic cross-sectional view of an optical film related to another embodiment of the present invention. <FIG. 3> FIG. 3 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention.

100: optical film

110: first outer resin layer

120: intermediate resin layer

130: second outer resin layer

Claims (6)

An optical film comprising a first outer resin layer, an intermediate resin layer containing an ultraviolet absorber and a visible light absorber, and a second outer resin layer in sequence, wherein the ultraviolet absorber is above 320 nm and less than 380 The wavelength band of nm has the maximum maximum absorption wavelength in the band above 320 nm and below 410 nm, and the band of the aforementioned visible light absorber above 380 nm and below 410 nm has the wavelength band above 320 nm and below 410 nm The maximum maximum absorption wavelength of the optical thin film at a wavelength of 300 nm to 390 nm is less than 1%. The optical film according to claim 1, wherein the intermediate resin layer includes a first intermediate resin layer containing the visible light absorber and a second intermediate resin layer containing the ultraviolet absorber. The optical film according to claim 1 or 2, wherein the first outer resin layer, the intermediate resin layer, and the second outer resin layer include a polymer containing an alicyclic structure. A polarizing plate comprising: a polarizing member and the optical film according to any one of claims 1 to 3. A polarizing plate comprising: an optical film and a polarizer provided on any surface of the optical film, wherein the optical film is sequentially provided with a first outer resin layer, a first intermediate resin layer containing a visible light absorber, and an ultraviolet absorber Of the second intermediate resin layer and the second outer resin layer, the ultraviolet absorber in the wavelength band above 320 nm and below 380 nm has the maximum maximum absorption wavelength in the wavelength band above 320 nm and below 410 nm, and the aforementioned visible light The absorber is in the wavelength band above 380 nm and below 410 nm, and has the maximum maximum absorption wavelength in the wavelength band above 320 nm and below 410 nm, and the light transmittance of the aforementioned optical film at a wavelength of 300 nm to 390 nm is 1 %the following. A method for manufacturing an optical film, which is the method for manufacturing an optical film according to any one of claims 1 to 3, comprising: forming a first outer resin layer, an intermediate resin layer, and a second outer resin by a co-extrusion method Floor.

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