Optical film and method for manufacturing the same

Abstract

Provided is an optical film formed by resin containing a crystalline polymer having a melting point, and a non-crystalline polymer not having a melting point, wherein the resin has a glass-transition temperature Tgd satisfying expression (1) and has a cold crystallization temperature Tcd satisfying expression (2). Also provided is an optical film formed by resin containing a crystalline polymer having a melting point, and a non-crystalline polymer not having a melting point, wherein the resin has a melting point Tmd satisfying expression (3), and the glass-transition temperature Tgd.　(1): 100°C < Tgd < 140°C (2): 170°C < Tcd < 225°C (3) 50°C ≤ Tmd-Tgd ≤ 160°C

Description

Technical Field

[0001] The present invention relates to an optical film and a method for producing the same.

Background Art

[0002] Conventionally, films for optical applications have generally been produced from amorphous polymers. However, amorphous polymers tend to be inferior in solvent resistance. Therefore, it has been proposed to produce a film having excellent solvent resistance from a resin containing a combination of an amorphous polymer and a crystalline polymer (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, a film formed from a resin containing a combination of an amorphous polymer and a crystalline polymer tends to be inferior in heat resistance. Specifically, conventional films tended to cause a change in retardation and an increase in haze in a high-temperature environment.

[0005] In addition, a film formed from a resin containing a combination of an amorphous polymer and a crystalline polymer may have variations in the polarization state of transmitted light when linearly polarized light is transmitted through the film, for example.

[0006] The present invention was devised in view of the above-mentioned problems, and aims to provide an optical film and a method for manufacturing the same that are excellent in both solvent resistance and heat resistance. Furthermore, the present invention aims to provide an optical film and a method for manufacturing the same that can suppress variations in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film. [Means for solving the problem]

[0007] The inventors diligently studied to solve the aforementioned problems. As a result, the inventors found that an optical film formed from a resin containing a crystalline polymer having a melting point and an amorphous polymer without a melting point, and having a glass transition temperature and cold crystallization temperature within a specific range, exhibits excellent solvent resistance and heat resistance, and that an optical film formed from a resin containing a crystalline polymer having a melting point and an amorphous polymer without a melting point, and having a melting point and glass transition temperature of the resin satisfying a specific relationship, can suppress the variation in the polarization state of transmitted light, thus completing the present invention. In other words, the present invention includes the following:

[0008] [1] An optical film formed from a resin comprising a crystalline polymer having a melting point and an amorphous polymer not having a melting point, An optical film wherein the resin has a glass transition temperature Tgd that satisfies the following formula (1), and a cold crystallization temperature Tcd that satisfies the following formula (2). 100℃ <Tgd<140℃ (1) 170℃ <Tcd<225℃ (2) [2] An optical film formed from a resin comprising a crystalline polymer having a melting point and an amorphous polymer not having a melting point, The resin is an optical film having a melting point Tmd and a glass transition temperature Tgd that satisfy the following formula (3). 50℃ ≤ Tmd - Tgd ≤ 160℃ (3) [3] The optical film according to [1] or [2], wherein the crystalline polymer is a cyclic olefin polymer having a melting point. [4] The optical film according to any one of [1] to [3], wherein the amorphous polymer is a cyclic olefin polymer that does not have a melting point. [5] A step of mixing a crystalline polymer having a melting point and an amorphous polymer not having a melting point to obtain a resin having a glass transition temperature Tgd satisfying the following formula (1) and a cold crystallization temperature Tcd satisfying the following formula (2), A method for manufacturing an optical film, comprising the step of molding the aforementioned resin to obtain a resin film. 100℃ <Tgd<140℃ (1) 170℃ <Tcd<225℃ (2) [6] A method for manufacturing an optical film according to [5], comprising the step of stretching the resin film. [7] The method for manufacturing an optical film according to [6], wherein the stretching temperature in the step of stretching the resin film is Tg or higher and Tcd -30°C or lower. [8] A step of mixing a crystalline polymer having a melting point and an amorphous polymer not having a melting point to obtain a resin having a melting point Tmd and a glass transition temperature Tgd that satisfy the following formula (3), A method for manufacturing an optical film, comprising the step of molding the aforementioned resin to obtain a resin film. 50℃ ≤ Tmd - Tgd ≤ 160℃ (3) [9] A method for manufacturing an optical film according to [8], comprising the step of stretching the resin film. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an optical film and a method for manufacturing the same that are excellent in both solvent resistance and heat resistance. Furthermore, according to the present invention, it is possible to provide an optical film and a method for manufacturing the same that can suppress variations in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments and examples of the present invention will be described in detail. However, the present invention is not limited to the embodiments and examples shown below, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0011] In the following description, unless otherwise specified, a polymer having positive intrinsic birefringence means a polymer in which the refractive index in the stretching direction is larger than the refractive index in the direction perpendicular thereto. Further, unless otherwise specified, a polymer having negative intrinsic birefringence means a polymer in which the refractive index in the stretching direction is smaller than the refractive index in the direction perpendicular thereto.

[0012] In the following description, a "long" film means a film having a length of 5 times or more the width, preferably 10 times or more the length, and specifically means a film having a length such that it can be wound up in a roll and stored or transported. The upper limit of the length of the film is not particularly limited, and can be, for example, 100,000 times or less the width.

[0013] In the following description, unless otherwise specified, the in-plane retardation Re is a value represented by Re = (nx - ny) × d. Further, the retardation Rth in the thickness direction is a value represented by Rth = [{(nx + ny) / 2} - nz] × d unless otherwise specified. Furthermore, the birefringence Δn is, unless otherwise specified, a value represented by nx - ny, and thus is a value represented by Re / d. Here, nx represents the refractive index in the direction perpendicular to the thickness direction (in-plane direction) that gives the maximum refractive index. ny represents the refractive index in the in-plane direction that is orthogonal to the direction of nx. nz represents the refractive index in the thickness direction. d represents the thickness. The measurement wavelength is 590 nm unless otherwise specified.

[0014] [1. Overview of Optical Film] The optical film according to an embodiment of the present invention is formed of a resin containing a crystalline polymer having a melting point and an amorphous polymer having no melting point. The above resin containing the crystalline polymer and the amorphous polymer may be hereinafter referred to as "mixed resin". Since the optical film is formed of the mixed resin, it usually contains the mixed resin and preferably contains only the mixed resin.

[0015] The optical film according to an embodiment of the present invention includes at least one of the following configurations: (1) a configuration in which the mixed resin has a glass transition temperature Tgd within a specific range and a cold crystallization temperature Tcd within a specific range, and (2) a configuration in which the mixed resin has a melting point Tmd and a glass transition temperature Tgd that satisfy a specific relationship. Hereinafter, the case including the configuration of (1) will be described as the first embodiment, the case including the configuration of (2) will be described as the second embodiment, and the case including both configurations of (1) and (2) will be described as the third embodiment.

[0016] [1.1. First embodiment of the optical film] The optical film according to the first embodiment is formed of a mixed resin containing a crystalline polymer having a melting point and an amorphous polymer having no melting point. The mixed resin has a glass transition temperature Tgd within a specific range and a cold crystallization temperature Tcd within a specific range. The optical film formed of this mixed resin can be excellent in both solvent resistance and heat resistance.

[0017] [1.1.1. Crystalline polymer] The crystalline polymer represents a polymer having crystallinity. A polymer having crystallinity represents a polymer having a melting point. The melting point of the polymer can be measured by a differential scanning calorimeter (DSC). Therefore, the crystalline polymer represents a polymer in which a melting point can be observed by a differential scanning calorimeter (DSC).

[0018] The crystalline polymer may have positive intrinsic birefringence or negative intrinsic birefringence. Among them, a crystalline polymer having positive intrinsic birefringence is preferable.

[0019] Examples of crystalline polymers include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); and polyolefins such as polyethylene (PE) and polypropylene (PP); however, cyclic olefin polymers are preferred. In other words, the crystalline polymer is preferably a cyclic olefin polymer having a melting point. Hereinafter, a cyclic olefin polymer having a melting point may be referred to as a "cyclic olefin crystalline polymer."

[0020] Cyclic olefin-based crystalline polymers may have alicyclic structures within their molecules. Such cyclic olefin-based crystalline polymers may be polymers or hydrides thereof obtained by polymerization reactions using cyclic olefins as monomers, for example. When a mixed resin containing a cyclic olefin-based crystalline polymer is used, the mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability, and lightweight properties of the optical film can be improved.

[0021] Examples of alicyclic structures include cycloalkane and cycloalkene structures. Among these, cycloalkane structures are preferred because they easily yield optical films with excellent properties such as thermal stability. The number of carbon atoms in a single alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less. When the number of carbon atoms in a single alicyclic structure is within the above range, mechanical strength, heat resistance, and moldability are highly balanced.

[0022] In cyclic olefin-based crystalline polymers, the proportion of structural units having an alicyclic structure to all structural units is preferably 30% by weight or more, more preferably 50% by weight or more, and particularly preferably 70% by weight or more. When the proportion of structural units having an alicyclic structure is as high as described above, heat resistance can be improved. The proportion of structural units having an alicyclic structure to all structural units can be 100% by weight or less. Furthermore, in cyclic olefin-based crystalline polymers, the remainder other than structural units having an alicyclic structure is not particularly limited and can be appropriately selected according to the intended use.

[0023] Examples of cyclic olefin-based crystalline polymers include polymers (α) to (δ) listed below. Among these, polymer (β) is preferred because it is easier to obtain optical films with excellent heat resistance. Polymer (α): A ring-opening polymer of a cyclic olefin monomer that is crystalline. Polymer (β): A hydride of polymer (α) that is crystalline. Polymer (γ): An addition polymer of cyclic olefin monomers that is crystalline. Polymer (δ): A hydride of polymer (γ) that is crystalline.

[0024] Specifically, as crystalline polymers containing an alicyclic structure, ring-opened polymers of dicyclopentadiene that are crystalline, and hydrides of ring-opened polymers of dicyclopentadiene that are crystalline are more preferred. Among these, hydrides of ring-opened polymers of dicyclopentadiene that are crystalline are particularly preferred. Here, a ring-opened polymer of dicyclopentadiene refers to a polymer in which the proportion of structural units derived from dicyclopentadiene to the total structural units is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably 100% by weight.

[0025] The hydride of a ring-opening polymer of dicyclopentadiene preferably has a high proportion of racemo-dyads. Specifically, the proportion of racemo-dyads in the repeating units of the hydride of a ring-opening polymer of dicyclopentadiene is preferably 51% or more, more preferably 70% or more, and particularly preferably 85% or more. A high proportion of racemo-dyads indicates high syndiotactic stereoregularity. Therefore, the higher the proportion of racemo-dyads, the higher the melting point of the hydride of the ring-opening polymer of dicyclopentadiene tends to be. The proportion of the racemo dyad is described in the examples below. 13 It can be determined by analyzing the C-NMR spectrum.

[0026] As the polymers (α) to polymers (δ) mentioned above, polymers obtained by the manufacturing method disclosed in International Publication No. 2018 / 062067 may be used.

[0027] The melting point Tma of the crystalline polymer is preferably 200°C or higher, more preferably 230°C or higher, and preferably 290°C or lower. When a crystalline polymer having such a melting point Tma is used, an optical film with an even better balance of moldability and heat resistance can be obtained.

[0028] Typically, crystalline polymers have a glass transition temperature (Tga). While the specific glass transition temperature (Tga) of a crystalline polymer is not particularly limited, it is usually between 85°C and 170°C.

[0029] The glass transition temperature Tga of a crystalline polymer is preferably lower than the glass transition temperature Tgb of an amorphous polymer. When the glass transition temperature Tga is lower than the glass transition temperature Tgb, the solvent resistance, heat resistance, and flexibility of the optical film can be effectively improved.

[0030] The absolute value |Tga-Tgb|, which is the difference between the glass transition temperature Tga of a crystalline polymer and the glass transition temperature Tgb of an amorphous polymer, is preferably within a specific range. Specifically, the absolute value |Tga-Tgb| is preferably 30°C or higher, more preferably 40°C or higher, particularly preferably 50°C or higher, preferably 100°C or lower, more preferably 90°C or lower, and particularly preferably 80°C or lower. When the absolute value |Tga-Tgb| is within the above range, the solvent resistance, heat resistance, and flexibility of the optical film can be effectively improved.

[0031] The glass transition temperature and melting point of a polymer can be measured by the following method. First, the polymer is melted by heating, and the molten polymer is rapidly cooled with dry ice. Then, using this polymer as a test specimen, the glass transition temperature and melting point of the polymer can be measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min (heating mode).

[0032] The weight-average molecular weight (Mw) of the crystalline polymer is preferably 1,000 or more, more preferably 2,000 or more, preferably 1,000,000 or less, and more preferably 500,000 or less. Crystalline polymers having such a weight-average molecular weight offer an excellent balance between moldability and heat resistance.

[0033] The molecular weight distribution (Mw / Mn) of the crystalline polymer is preferably 1.0 or higher, more preferably 1.5 or higher, preferably 4.0 or lower, and more preferably 3.5 or lower. Here, Mn represents the number-average molecular weight. Crystalline polymers having such a molecular weight distribution exhibit excellent moldability.

[0034] The weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of a polymer can be measured as polystyrene equivalent values ​​by gel permeation chromatography (GPC) using tetrahydrofuran as the developing solvent. If the polymer does not dissolve in cyclohexane, the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) can be measured as polyisoprene equivalent values ​​using toluene as the solvent.

[0035] The degree of crystallinity of the crystalline polymer contained in the optical film is usually 0% or higher, preferably 20% or lower, more preferably 15% or lower, even more preferably 10% or lower, and particularly preferably 5% or lower. The degree of crystallinity of the crystalline polymer can be measured by X-ray diffraction.

[0036] Crystalline polymers may be used individually or in combination of two or more types in any ratio.

[0037] The amount of crystalline polymer contained in the mixed resin is preferably 30% by weight or more, more preferably 35% by weight or more, particularly preferably 40% by weight or more, preferably 80% by weight or less, more preferably 75% by weight or less, and particularly preferably 70% by weight or less, based on 100% by weight of the mixed resin. When the amount of crystalline polymer is within the above range, the solvent resistance, heat resistance, and flexibility of the optical film can be effectively enhanced.

[0038] The weight ratio Wa / Wb of the amount of crystalline polymer Wa and the amount of amorphous polymer Wb in the mixed resin is preferably within a specific range. Specifically, the weight ratio Wa / Wb is preferably greater than 30 / 70, more preferably greater than 35 / 65, particularly preferably greater than 40 / 60, preferably less than 80 / 20, and more preferably less than 75 / 25. When the weight ratio Wa / Wb is within the above range, the solvent resistance, heat resistance, and flexibility of the optical film can be effectively improved.

[0039] Furthermore, the total amount of crystalline polymers and amorphous polymers contained in the mixed resin is preferably 50% to 100% by weight, more preferably 70% to 100% by weight, even more preferably 80% to 100% by weight, even more preferably 90% to 100% by weight, and particularly preferably 95% to 100% by weight, based on 100% by weight of the mixed resin.

[0040] [1.1.2. Amorphous Polymers] Amorphous polymers are polymers that do not possess crystalline properties. Polymers that do not possess crystalline properties are polymers that do not have a melting point. Therefore, amorphous polymers are polymers whose melting point cannot be observed using differential scanning calorimetry (DSC).

[0041] Amorphous polymers may have positive intrinsic birefringence or negative intrinsic birefringence. Among these, amorphous polymers having positive intrinsic birefringence are preferred.

[0042] As the amorphous polymer, cyclic olefin polymers are preferred. That is, the amorphous polymer is preferably a cyclic olefin polymer that does not have a melting point. Hereinafter, cyclic olefin polymers that do not have a melting point may be referred to as "cyclic olefin amorphous polymers." Cyclic olefin amorphous polymers have excellent mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability, and lightweight properties.

[0043] Cyclic olefin amorphous polymers may have a cyclic structure within their molecule. Typically, cyclic olefin amorphous polymers have alicyclic structures as structural units. Cyclic olefin amorphous polymers can be polymers with alicyclic structures in the main chain, polymers with alicyclic structures in the side chains, polymers with alicyclic structures in both the main chain and side chains, or mixtures of two or more of these in any ratio. Among these, cyclic olefin amorphous polymers are preferably those with alicyclic structures in the main chain from the viewpoint of mechanical strength and heat resistance.

[0044] Examples of alicyclic structures include saturated alicyclic hydrocarbon (cycloalkane) structures and unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structures. Among these, cycloalkane and cycloalkene structures are preferred from the viewpoint of mechanical strength and heat resistance, and cycloalkane structures are particularly preferred.

[0045] The number of carbon atoms in a single alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less. When the number of carbon atoms constituting the alicyclic structure is within this range, mechanical strength, heat resistance, and moldability are highly balanced.

[0046] In cyclic olefin amorphous polymers, the proportion of structural units having an alicyclic structure to all structural units 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 to all structural units is within this range, transparency and heat resistance are good.

[0047] Examples of cyclic olefin amorphous polymers include norbornene polymers, monocyclic cyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers, and their hydrides. Among these, norbornene polymers and their hydrides exhibit good moldability.

[0048] Examples of norbornene polymers and their hydrides include ring-opening polymers of monomers having a norbornene structure and their hydrides; and addition polymers of monomers having a norbornene structure and their hydrides. Examples of ring-opening polymers of monomers having a norbornene structure include ring-opening homopolymers of one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of a monomer having a norbornene structure and other monomers copolymerizable thereto. Furthermore, examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of a monomer having a norbornene structure and other monomers copolymerizable thereto. Examples of these polymers include those disclosed in Japanese Patent Publication No. 2002-321302, International Publication No. 2017 / 145718, etc. Among these, hydrides of ring-opening monomer polymers having a norbornene structure are particularly preferred from the viewpoint of moldability, heat resistance, low moisture absorption, dimensional stability, and lightweight properties.

[0049] Examples of monomers having a norbornene structure include bicyclo[2.2.1]hepto-2-ene (common name: norbornene), tricyclo[4.3.0.1 2,5 Deca-3,7-diene (common name: dicyclopentadiene), tetracyclo[4.4.0.1 2,5 .1 7,10Norbornene monomers that do not contain an aromatic ring structure, such as dodeca-3-ene (common name: tetracyclododecene); norbornene monomers with aromatic substituents, such as 5-phenyl-2-norbornene, 5-(4-methylphenyl)-2-norbornene, 5-(1-naphthyl)-2-norbornene, and 9-(2-norbornene-5-yl)-carbazole; 1,4-methano-1,4,4a,4b,5,8,8a,9a-octahydrofluorene, 1,4-methano-1,4,4a,9a-tetrahydrofluorene (common name: meta Examples include norbornene monomers containing a norbornene ring structure and an aromatic ring structure in a condensed polycyclic structure, such as notetrahydrofluorene, 1,4-methano-1,4,4a,9a-tetrahydrodibenzofuran, 1,4-methano-1,4,4a,9a-tetrahydrocarbazole, 1,4-methano-1,4,4a,9,9a,10-hexahydroanthracene, and 1,4-methano-1,4,4a,9,10,10a-hexahydrophenanthrene; and derivatives of these compounds (e.g., those having substituents on the ring).

[0050] Examples of substituents include alkyl groups such as methyl, ethyl, propyl, and isopropyl groups; alkylidene groups; alkenyl groups; and polar groups. Examples of polar groups include heteroatoms or groups of atoms having heteroatoms. Examples of heteroatoms include oxygen, nitrogen, sulfur, silicon, and halogen atoms. Specific examples of polar groups include halogen groups such as fluoro, chlor, bromo, and iodo groups; carboxyl groups; carbonyloxycarbonyl groups; epoxy groups; hydroxyl groups; oxy groups; alkoxy groups; ester groups; silanol groups; silyl groups; amino groups; nitrile groups; sulfone groups; cyano groups; amide groups; and imide groups. The number of substituents may be one or two or more. Furthermore, the types of the two or more substituents may be the same or different. However, from the viewpoint of obtaining an amorphous resin with low saturated water absorption and excellent moisture resistance, it is preferable that the norbornene monomer has a small amount of polar groups, and more preferably has no polar groups at all.

[0051] Examples of cyclic olefin amorphous polymers, listed by trade name, include "ZEONEX" from Nippon Zeon Corporation, "ARTON" from JSR Corporation, "APPEL" from Mitsui Chemicals Corporation, and "TOPAS" from Polyplastics Corporation.

[0052] The glass transition temperature (Tgb) of the amorphous polymer is preferably 90°C or higher, more preferably 100°C or higher, even more preferably 110°C or higher, preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C or lower. When the glass transition temperature (Tgb) of the amorphous polymer is within the above range, both the solvent resistance and heat resistance of the optical film can be effectively improved. In addition, the stretching process can usually be carried out smoothly.

[0053] The weight-average molecular weight (Mw) of the amorphous polymer is preferably 10,000 or more, more preferably 15,000 or more, particularly preferably 20,000 or more, preferably 100,000 or less, more preferably 80,000 or less, and particularly preferably 50,000 or less. When the weight-average molecular weight is within the above range, the mechanical strength and moldability of the mixed resin are highly balanced.

[0054] The molecular weight distribution (weight-average molecular weight (Mw) / number-average molecular weight (Mn)) of the amorphous polymer is preferably 1.2 or higher, more preferably 1.5 or higher, particularly preferably 1.8 or higher, preferably 3.5 or lower, more preferably 3.0 or lower, and particularly preferably 2.7 or lower. When the molecular weight distribution is above the lower limit of the above range, the productivity of the polymer can be increased and manufacturing costs can be suppressed. Furthermore, when it is below the upper limit, the amount of low molecular weight components is reduced, which suppresses relaxation during high-temperature exposure and improves the stability of the optical film.

[0055] Amorphous polymers may be used individually or in combination of two or more types in any ratio.

[0056] The amount of amorphous polymer contained in the mixed resin is preferably 20% by weight or more, more preferably 25% by weight or more, particularly preferably 30% by weight or more, preferably 70% by weight or less, more preferably 65% ​​by weight or less, and particularly preferably 60% by weight or less, based on 100% by weight of the mixed resin. When the amount of amorphous polymer is within the above range, both the solvent resistance and heat resistance of the optical film can be effectively improved.

[0057] [1.1.3. Any ingredient] The mixed resin may contain any additional components in combination with crystalline polymers and amorphous polymers. Optional components include, for example, antioxidants such as phenolic antioxidants, phosphorus antioxidants, and sulfuric antioxidants; light stabilizers such as hindered amine light stabilizers; waxes such as petroleum waxes, Fischer-Tropsch waxes, and polyalkylene waxes; nucleating agents such as sorbitol compounds, metal salts of organic phosphoric acids, metal salts of organic carboxylic acids, kaolin, and talc; fluorescent whitening agents such as diaminostilbene derivatives, coumarin derivatives, azole derivatives (e.g., benzoxazole derivatives, benzotriazole derivatives, benzimidazole derivatives, and benzothiasol derivatives), carbazole derivatives, pyridine derivatives, naphthalic acid derivatives, and imidazolon derivatives; ultraviolet absorbers such as benzophenone ultraviolet absorbers, salicylic acid ultraviolet absorbers, and benzotriazole ultraviolet absorbers; colorants; flame retardants; flame retardant additives; antistatic agents; plasticizers; near-infrared absorbers; lubricants; and inorganic fillers such as talc, silica, calcium carbonate, and glass fibers. Any component may be used alone or in combination of two or more components in any ratio. The amount of any component can be appropriately determined within a range that does not significantly impair the effects of the present invention. For example, the amount of any component may be within a range that maintains the total light transmittance of the optical film at 85% or higher.

[0058] [1.1.4. Properties of mixed resins] The mixed resin has a glass transition temperature Tgd that satisfies the following formula (1). 100℃ <Tgd<140℃ (1) In detail, the glass transition temperature (Tgd) of the mixed resin is usually higher than 100°C, preferably higher than 102°C, particularly preferably 104°C or higher, and also usually lower than 140°C, preferably lower than 135°C, particularly preferably 130°C or lower.

[0059] The glass transition temperature (Tgd) of the mixed resin can be adjusted, for example, by adjusting the type and amount of crystalline polymer and the type and amount of amorphous polymer.

[0060] The glass transition temperature (Tgd) of a mixed resin can be measured using the same method as described above for measuring the glass transition temperature of a polymer.

[0061] The mixed resin has a cold crystallization temperature Tcd that satisfies the following formula (2). 170℃ <Tcd<225℃ (2) In detail, the cold crystallization temperature Tcd of the mixed resin is usually higher than 170°C, preferably higher than 175°C, particularly preferably 180°C or higher, and usually lower than 225°C, preferably lower than 210°C, particularly preferably lower than 205°C.

[0062] The cold crystallization temperature Tcd of the mixed resin can be adjusted, for example, by adjusting the type and amount of crystalline polymer and the type and amount of amorphous polymer.

[0063] The cold crystallization temperature (Tcd) of a mixed resin can be measured by the following method. First, the mixed resin is melted by heating, and the molten mixed resin is rapidly cooled with dry ice. Next, using this mixed resin as a test specimen, the cold crystallization temperature (Tcd) of the mixed resin can be measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min (heating mode). In this measurement method, the cold crystallization temperature (Tcd) can be obtained as the peak temperature of the exothermic peak during the heating process.

[0064] When the mixed resin has a glass transition temperature Tgd that satisfies formula (1) and a cold crystallization temperature Tcd that satisfies formula (2) described above, the optical film according to the first embodiment can have excellent solvent resistance and heat resistance.

[0065] The absolute value |Tgd-Tga|, which is the difference between the glass transition temperature Tgd of the mixed resin and the glass transition temperature Tga of the crystalline polymer, is preferably within a specific range. Specifically, the absolute value |Tgd-Tga| is preferably 3°C or higher, more preferably 6°C or higher, particularly preferably 10°C or higher, preferably 45°C or lower, more preferably 40°C or lower, and particularly preferably 35°C or lower. When the absolute value |Tgd-Tga| is within the above range, both the solvent resistance and heat resistance of the optical film can be effectively improved.

[0066] The absolute value |Tgd-Tgb|, which is the difference between the glass transition temperature Tgd of the mixed resin and the glass transition temperature Tgb of the amorphous polymer, is preferably within a specific range. Specifically, the absolute value |Tgd-Tgb| is preferably 20°C or higher, more preferably 30°C or higher, particularly preferably 35°C or higher, preferably 80°C or lower, more preferably 70°C or lower, and particularly preferably 60°C or lower. When the absolute value |Tgd-Tgb| is within the above range, both the solvent resistance and heat resistance of the optical film can be effectively improved.

[0067] The mixed resin typically has a melting point Tmd. The range of the melting point Tmd of the mixed resin is preferably 200°C or higher, more preferably 230°C or higher, particularly preferably 240°C or higher, and preferably 290°C or lower. When the mixed resin has a melting point Tmd within the above range, both the solvent resistance and heat resistance of the optical film can be effectively improved.

[0068] The melting point Tmd of the mixed resin can be measured, for example, by the same method as the method for measuring the melting point of the polymer described above.

[0069] [1.1.5. Characteristics of Optical Films] The optical film according to the first embodiment can have excellent solvent resistance. For example, when the optical film is immersed in toluene as a solvent at 23°C for 30 seconds, the film weight change rate can be made positive. The film weight change rate is the ratio obtained by dividing the amount of weight change of the optical film due to solvent immersion by the weight of the optical film before solvent immersion. The amount of weight change of the optical film due to solvent immersion is the value obtained by subtracting the weight of the optical film before solvent immersion from the weight of the optical film after solvent immersion. The fact that the film weight change rate can be made positive as described above indicates that the weight loss of the optical film due to dissolution in the solvent has been suppressed. Normally, the optical film swells when the solvent penetrates it, and as a result the weight of the optical film increases, so the film weight change rate is positive.

[0070] Furthermore, since the optical film according to the first embodiment can have excellent solvent resistance, for example, if the optical film is bent, a drop of n-hexane as a solvent is placed on the bent portion, and the solvent is allowed to air dry, cracks can be prevented from penetrating the optical film.

[0071] The optical film according to the first embodiment can have excellent heat resistance. Therefore, the optical film can suppress changes in retardation in high-temperature environments. For example, when a heat resistance test I is performed in which the optical film is stored at 95°C for 24 hours, the rate of change in in-plane retardation (retarding change rate) due to the heat resistance test I can be reduced. Specifically, this retardation change rate is preferably 2.5% or less, more preferably 2.0% or less, and particularly preferably 1.5% or less. The heat resistance test I is usually performed with the optical film sandwiched between clean paper to prevent it from sticking to the test stand. The retardation change rate represents the absolute value of the ratio obtained by dividing the amount of change in in-plane retardation of the optical film due to the heat resistance test I by the in-plane retardation of the optical film before the heat resistance test I. Furthermore, the change in the in-plane retardation of the optical film represents the difference between the in-plane retardation of the optical film before heat resistance test I and the in-plane retardation of the optical film after heat resistance test I.

[0072] The optical film according to the first embodiment can have excellent heat resistance, thus suppressing the rise of haze in high-temperature environments. For example, when the optical film is subjected to heat resistance test II, in which it is stored at 105°C for 24 hours, it can still have low haze even after heat resistance test II. Specifically, the haze of the optical film after heat resistance test II is preferably 2.0% or less, more preferably 1.0% or less, and particularly preferably 0.5% or less. The heat resistance test II is usually performed with the optical film sandwiched between clean paper, just like heat resistance test I. The haze can be measured using an NDH-7000 (manufactured by Nippon Denshoku) in accordance with JIS K7361-1997.

[0073] The inventors surmise that the mechanism by which the optical film exhibits excellent solvent resistance and heat resistance, as described above, is as follows. However, the technical scope of the present invention is not limited to the mechanism shown below.

[0074] Conventionally, it has been known that resin films containing a combination of crystalline and amorphous polymers exhibit excellent solvent resistance. However, the inventors' research has revealed that these films have poor heat resistance and are prone to retardation changes and haze increases in high-temperature environments. The inventors believe that one of the causes of the aforementioned retardation changes and haze increases is the relaxation of orientation and the progression of crystallization.

[0075] Specifically, the polymer molecules contained in optical films may undergo orientation relaxation in high-temperature environments. When such orientation relaxation occurs, the orientation direction of the polymer molecules may change. Also, when crystallization of crystalline polymers progresses in high-temperature environments, the molecules of the crystalline polymer may change their orientation to increase the regularity of their orientation. As a result, the orientation state of the molecules changes throughout the film, and consequently, the retardation of the film may change. Furthermore, as crystallization of crystalline polymers progresses, spherulites may form in the film. These spherulites cause whitening of the film and increase haze.

[0076] In contrast, in the optical film according to the first embodiment described above, the mixed resin has a high glass transition temperature Tgd within a specific range, so the relaxation of orientation is suppressed. Furthermore, since the mixed resin has a high cold crystallization temperature Tcd within a specific range, the progress of crystallization of the crystalline polymer is suppressed. Therefore, the optical film described above can suppress changes in retardation and increases in haze in high-temperature environments and exhibit excellent heat resistance. Moreover, a mixed resin having a glass transition temperature Tgd and cold crystallization temperature Tcd within a specific range that satisfies formulas (1) and (2) can exhibit resistance to solvents while possessing the aforementioned heat resistance, thus enabling improvements in both solvent resistance and heat resistance.

[0077] The optical film preferably has a large birefringence Δn. The specific range of birefringence for the optical film is preferably 0.00200 or more, more preferably 0.00205 or more, and particularly preferably 0.00210 or more. In the past, crystalline polymers and amorphous polymers tended to have poorer heat resistance as their birefringence increased. Therefore, in films where solving the problem conventionally was particularly difficult, it is preferable for the optical film to have a large birefringence Δn as described above, from the viewpoint of effectively utilizing the effects of the present invention. There is no particular upper limit to the birefringence Δn, and it may be, for example, 0.00400 or less, 0.00350 or less, etc. The birefringence Δn of an optical film can be determined by dividing the in-plane retardation of the optical film by its thickness.

[0078] The optical film may have an in-plane retardation suitable for its application. For example, the in-plane retardation Re of the optical film at a measurement wavelength of 590 nm is preferably 30 nm or more, more preferably 40 nm or more, particularly preferably 50 nm or more, preferably 300 nm or less, more preferably 290 nm or less, and particularly preferably 280 nm or less.

[0079] The optical film may have a thickness-direction retardation suitable for its application. For example, the thickness-direction retardation Rth of the optical film at a measurement wavelength of 590 nm is preferably 10 nm or more, more preferably 20 nm or more, particularly preferably 30 nm or more, preferably 300 nm or less, more preferably 250 nm or less, and particularly preferably 200 nm or less.

[0080] The in-plane retardation and thickness-direction retardation of optical films can be measured using a phase difference meter (AXOMETRICS "AxoScanOPMF-1").

[0081] The optical film preferably has high transparency. The specific total light transmittance of the optical film is preferably 80% or more, more preferably 85% or more, and particularly preferably 88% or more. The total light transmittance of the film can be measured using an ultraviolet-visible spectrometer in the wavelength range of 400 nm to 700 nm.

[0082] The optical film preferably has low haze. The haze of the optical film is preferably 2.0% or less, more preferably 1.0% or less, particularly preferably 0.5% or less, and ideally 0.0%.

[0083] The optical film may be a single-sheet film or a long film having a long shape.

[0084] The optical film may have a single-layer structure comprising only one layer formed of a mixed resin having the same composition, or it may have a multi-layer structure comprising multiple layers formed of mixed resins having different compositions.

[0085] The thickness of the optical film can be appropriately set depending on the application of the optical film, but generally a thin thickness is desirable. The specific thickness of the optical film is preferably 5 μm or more, more preferably 10 μm or more, particularly preferably 20 μm or more, preferably 500 μm or less, more preferably 200 μm or less, and particularly preferably 100 μm or less.

[0086] [1.2. Optical film according to the second embodiment] The optical film according to the second embodiment is formed from a mixed resin containing a crystalline polymer having a melting point and an amorphous polymer not having a melting point. The mixed resin may have a melting point Tmd and a glass transition temperature Tgd that satisfy a specific relationship. An optical film formed from this mixed resin can suppress variations in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film.

[0087] The crystalline polymer, amorphous polymer, and optional components used in the optical film according to the second embodiment can be appropriately selected from those described as the crystalline polymer, amorphous polymer, and optional components used in the optical film according to the first embodiment.

[0088] [1.2.1. Properties of mixed resins] The mixed resin has a melting point Tmd and a glass transition temperature Tgd that satisfy the following formula (3). 50℃ ≤ Tmd - Tgd ≤ 160℃ (3) In detail, the difference between the melting point Tmd and the glass transition temperature Tgd of the mixed resin is usually 50°C or higher, preferably 80°C or higher, more preferably 100°C or higher, and particularly preferably 120°C or higher, and usually 160°C or lower, preferably 155°C or lower, and more preferably 150°C or lower.

[0089] Mixed resins typically have a cold crystallization temperature Tcd. Furthermore, it is preferable that the cold crystallization temperature Tcd and the glass transition temperature Tgd of the mixed resin satisfy the following formula (4). 60℃≦Tcd-Tgd≦110℃ (4) More specifically, the difference between the cold crystallization temperature Tcd and the glass transition temperature Tgd of the mixed resin is preferably 60°C or higher, more preferably 70°C or higher, preferably 110°C or lower, and more preferably 105°C or lower.

[0090] The melting point Tmd, glass transition temperature Tgd, and cold crystallization temperature of the mixed resin can be adjusted, for example, by adjusting the type and amount of crystalline polymer and the type and amount of amorphous polymer.

[0091] The melting point Tmd and glass transition temperature Tgd of the mixed resin can be measured, for example, by the same method as the method for measuring the melting point and glass transition temperature of the polymer described above. Furthermore, the cold crystallization temperature of the mixed resin can be measured by the same method as the example crystallization temperature of the mixed resin according to the first embodiment.

[0092] The possible and preferred ranges for the melting point Tmd, glass transition temperature Tgd, and cold crystallization temperature Tcd of the mixed resin may be the same as those for the melting point Tmd, glass transition temperature Tgd, and cold crystallization temperature Tcd of the mixed resin according to the first embodiment.

[0093] [1.2.2. Characteristics of Optical Films] The optical film according to the second embodiment can suppress variations in the polarization state of light transmitted through the film. For example, the cross-nicol transmittance Tx(%) of the optical film, measured by cross-nicol transmittance measurement with a spectrophotometer, can be set to a small value. Specifically, the cross-nicol transmittance Tx(%) of the optical film at a wavelength of 550 nm is preferably 0.04% or less, more preferably 0.03% or less, particularly preferably 0.02% or less, and even more preferably 0.01% or less. Furthermore, while the cross-nicol transmittance is ideally 0%, it can be, for example, 0.001% or more.

[0094] Crossed nicol transmittance can be measured using two linear polarizers (polarizer and analyzer), along with the JASCO V7200 spectrophotometer and the VAP-7070S automatic polarizing film measuring device.

[0095] The inventors of this invention surmise that the mechanism that can suppress variations in the polarization state of transmitted light when linearly polarized light is transmitted through an optical film as described above is as follows. However, the technical scope of this invention is not limited to the mechanism shown below.

[0096] In resin films containing a combination of crystalline and amorphous polymers, spherulites may form within the film during the manufacturing process due to the crystallization of the crystalline polymer. Because these spherulites themselves have a different phase difference from the optical film, they scatter some of the light (polarized light) incident on the optical film, resulting in variations in the polarization state of the light transmitted through the optical film.

[0097] Furthermore, when stretching is performed during the manufacturing process of optical films, the spherulite molecules in the optical film are less mobile than the uncrystallized resin molecules. As a result, the uncrystallized resin molecules are relatively more oriented, while the spherulite molecules are relatively more oriented, or no orientation occurs at all. Consequently, variations occur in the orientation of the spherulite molecules and the uncrystallized resin molecules in the optical film, resulting in variations in the polarization state of light transmitted through the optical film.

[0098] In contrast, in the optical film according to the second embodiment, the melting point Tmd and glass transition temperature Tgd of the mixed resin satisfy a predetermined relationship, so the optical film can be manufactured under conditions that can suppress the progression of crystallization of the crystalline polymer during the manufacturing process of the optical film. Therefore, the optical film can suppress variations in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film.

[0099] The birefringence, retardation, transparency and haze, form (single-fed, long-length), layer structure, and thickness of the optical film may be the same as those described in the section on the optical film according to the first embodiment above.

[0100] [1.3. Optical film according to the third embodiment] The optical film according to the third embodiment is formed from a mixed resin containing a crystalline polymer having a melting point and an amorphous polymer not having a melting point. The mixed resin has a glass transition temperature Tgd within a specific range and a cold crystallization temperature Tcd within a specific range, and also has a melting point Tmd and glass transition temperature Tgd that satisfy a specific relationship. An optical film formed from this mixed resin has excellent solvent resistance and heat resistance, and can suppress variations in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film.

[0101] The mixed resin according to the third embodiment possesses the properties of both the mixed resin according to the first embodiment and the mixed resin according to the second embodiment. Specifically, the mixed resin has a melting point Tmd, a glass transition temperature Tgd, and a cold crystallization temperature Tcd that satisfy formulas (1) to (3) described above. Preferably, the melting point Tmd and the glass transition temperature Tgd of the mixed resin also satisfy formula (4) described above. With respect to the properties of the mixed resin, other than the points mentioned above, they may be the same as those described for the properties of the mixed resin in the sections on the optical film according to the first and second embodiments described above.

[0102] Furthermore, the crystalline polymer, amorphous polymer, optional components, and properties of the optical film used in the optical film according to the third embodiment may be the same as those described in the sections on the optical films according to the first and second embodiments above.

[0103] [2. Method for manufacturing optical films] The optical film mentioned above is, for example, (1) A step of mixing crystalline polymers and amorphous polymers to obtain a mixed resin, (2) A process of molding a mixed resin to obtain a resin film, It can be manufactured by a method including the above. In this case, the resin film may be obtained as an optical film.

[0104] Furthermore, the method for manufacturing optical films is further, Step (3) of stretching the resin film It may also include. In a manufacturing method including step (3), an optical film can be obtained as a stretched film by stretching the resin film.

[0105] In step (1), a crystalline polymer and an amorphous polymer are mixed to obtain a mixed resin. There are no particular restrictions on the mixing method. For example, the crystalline polymer and the amorphous polymer may be kneaded in a molten state to obtain the mixed resin. The kneading can be performed, for example, using a twin-screw extruder. In step (1), a mixed resin of any of the mixed resins described in the section on optical films according to the first to third embodiments described above can be obtained.

[0106] In step (2), the mixed resin is molded to obtain a resin film. There are no restrictions on the molding method of the mixed resin. Examples of molding methods include extrusion molding, solution casting, and inflation molding. Among these, extrusion molding and solution casting are preferred, and extrusion molding is particularly preferred.

[0107] The extrusion molding method typically involves melting and extruding a mixed resin. The manufacturing conditions in this extrusion molding method are preferably as follows: The cylinder temperature (molten resin temperature) is preferably above Tmd, preferably below Tmd+100°C, and more preferably below Tmd+50°C. The cooling body that the extruded molten resin first contacts is not particularly limited, but a cast roll is usually used. The temperature of this cast roll is preferably above Tgd-50°C, and preferably below Tgd+70°C.

[0108] In step (3), the resin film is stretched. This stretching orients the polymer molecules in the resin film, resulting in an optical film with desirable optical properties. This stretching is preferably carried out at a stretching temperature below the cold crystallization temperature Tcd of the mixed resin. Specifically, the stretching temperature is preferably Tgd°C or higher, more preferably Tgd+10°C or higher, particularly preferably Tgd+15°C or higher, preferably Tcd-20°C or lower, more preferably Tcd-25°C or lower, particularly preferably Tcd-30°C or lower, and even more preferably Tcd-50°C or lower. When stretching is carried out at a stretching temperature within this range, the polymer molecules in the resin film can be effectively oriented while suppressing the progression of crystallization of the crystalline polymer. Therefore, the desired optical properties can be easily expressed in the film while suppressing the increase in haze.

[0109] The stretching ratio can be set according to the optical properties that the optical film should have. The specific stretching ratio is preferably greater than 1x, more preferably 1.1x or more, particularly preferably 1.2x or more, preferably 5x or less, more preferably 4x or less, and particularly preferably 3x or less. When biaxial stretching is performed, it is preferable that the overall stretching ratio, which is the product of the stretching ratio in one direction and the stretching ratio in the other direction, falls within the above range.

[0110] The aforementioned stretching method may be, for example, uniaxial stretching, which stretches in one direction, or biaxial stretching, which stretches in two non-parallel directions. Furthermore, biaxial stretching may be simultaneous biaxial stretching, which stretches in two directions at the same time, or sequential biaxial stretching, which stretches in one direction first and then in the other direction.

[0111] The method for manufacturing an optical film may include any additional steps in combination with the steps (1) to (3) described above. For example, the method for manufacturing an optical film may include a step of preheating the resin film before stretching in step (3). The preheating temperature is preferably "stretching temperature - 40°C" or higher, more preferably "stretching temperature - 30°C" or higher, preferably "stretching temperature + 20°C" or lower, and more preferably "stretching temperature + 15°C" or lower.

[0112] Furthermore, optional steps include trimming the optical film and applying surface treatment to the optical film. [Examples]

[0113] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention.

[0114] In the following explanation, "%" and "parts" refer to weight unless otherwise specified. Furthermore, the operations described below were performed under normal temperature and pressure (23°C, 1 atm) conditions in the atmosphere unless otherwise specified.

[0115] [Evaluation Method] (Method for measuring the weight-average molecular weight Mw and number-average molecular weight Mn of polymers) The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer were measured as polystyrene equivalents using a gel permeation chromatography (GPC) system (Tosoh Corporation, "HLC-8320"). An H-type column (Tosoh Corporation) was used as the column, and tetrahydrofuran was used as the solvent. The measurement temperature was 40°C.

[0116] (Method for measuring the hydrogenation rate of polymers) The hydrogenation rate of the polymer was determined at 145°C using orthodichlorobenzene-d4 as the solvent. 1 The results were measured by 1H-NMR.

[0117] (Methods for measuring glass transition temperature, cold crystallization temperature, and melting point) The glass transition temperatures Tga, Tgb, and Tgd, the cold crystallization temperature Tcd, and the melting points Tma and Tmd of the sample (polymer or resin in the following examples) were measured as follows. First, the sample was melted by heating. The molten sample was rapidly cooled with dry ice. Subsequently, the glass transition temperature Tga, Tgb, or Tgd, the cold crystallization temperature Tcd, and the melting points Tma and Tmd were measured for this sample using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min (heating mode). The cold crystallization temperature Tcd was defined as the peak value of the exothermic peak during the heating process.

[0118] (Method for measuring the ratio of racemo-dyad in polymers) The ratio of racemo-dyads in the polymer was measured as follows: Using orthodichlorobenzene-d4 as the solvent, the polymer was decoupled at 200°C using the inverse-gated decoupling method. 13 ¹¹NMR measurements were performed. 13 In 1C-NMR measurements, using the 127.5 ppm peak of orthodichlorobenzene-d4 as the reference shift, we identified a 43.35 ppm signal originating from the meso-dyad and a 43.43 ppm signal originating from the racemo-dyad. Based on the intensity ratio of these signals, the proportion of racemo-dyad in the polymer was determined.

[0119] (Method for measuring film thickness) The film thickness was measured using a contact-type thickness gauge (MITUTOYO Code No. 543-390).

[0120] (Method for measuring in-plane retardation Re, thickness-direction retardation Rth, and birefringence Δn of a film) The in-plane retardation Re and thickness-direction retardation Rth of the film were measured using a phase difference meter (AXOMETRICS "AxoScan OPMF-1"). Measurements were taken at a wavelength of 590 nm. Furthermore, the birefringence Δn was calculated using the in-plane retardation Re and thickness d with the following formula (X1). Δn[-]=Re[nm] / d[nm] (X1)

[0121] (Solvent resistance test of optical films I) The optical film was cut into 4cm x 4cm pieces to obtain film samples. The weight of these film samples was measured to obtain the film weight before solvent immersion. Subsequently, the entire film sample was immersed in toluene as a solvent for 30 seconds, removed, and the solvent was wiped off the surface of the film sample with a Kimwipe. The film sample was dried at room temperature for 30 minutes, and the film weight after solvent immersion was measured. The rate of change in film weight was calculated using the following formula (X2). Film weight change rate (%) = {(Film weight after solvent immersion - Film weight before solvent immersion) / (Film weight before solvent immersion)} × 100 (X2)

[0122] Based on the aforementioned film weight change rate, solvent resistance can be evaluated according to the following evaluation criteria. Solvent resistance "Good": The film weight change rate is positive. This result indicates that the film sample swelled in the solvent. "Poor" solvent resistance: The film weight change rate is negative. Alternatively, holes or damage occurred in the film sample. This result indicates that the optical film dissolved in the solvent.

[0123] (Solvent resistance test of optical film II) A 5cm x 2cm optical film was cut to obtain a film sample. This film sample was bent at the center of the longer side so that the fold was parallel to the shorter side, and the ends of the shorter side were secured with clips. The radius of curvature of the bent part of the film sample was 2.5mm. Next, the film sample was placed on a table with the fold at the top and the clip at the bottom. Then, one drop (approximately 1 ml) of n-hexane as a solvent was dropped onto the bent part (top) of the film sample using a dropper, and after the solvent was allowed to air dry, the clip was removed and it was observed whether or not crack penetration had occurred. Based on the presence or absence of crack penetration, the solvent resistance can be evaluated according to the evaluation criteria below. Solvent resistance "Good": No cracks were found, or there were no cracks at all. Poor solvent resistance: Cracks had formed, causing penetration.

[0124] (Heat resistance test of optical film I: Evaluation of retardation change rate) A 50mm x 50mm optical film was cut to obtain a film sample. The in-plane retardation of this film sample was measured using the method described above, and the in-plane retardation Re0 before the heat resistance test was obtained. Subsequently, a heat resistance test I was performed by placing the film sample between clean paper and immersing it in a 95°C constant temperature bath for 24 hours without securing it with tape. After that, the in-plane retardation of the film sample was measured using the method described above, and the in-plane retardation Re1 after the heat resistance test was obtained. The retardation change rate was calculated using the following formula (X3). A smaller retardation change rate indicates that the optical film has superior heat resistance; for example, a retardation change rate of 2.5% or less can be judged as having good heat resistance. Re change rate (%) = |(Re1-Re0) / Re0| × 100 (x3)

[0125] In other words, the heat resistance can be evaluated based on the following evaluation criteria using the aforementioned Re change rate (%). Heat resistance "Good": Re change rate (%) is 2.5% or less. Heat resistance "poor": Re change rate (%) is over 2.5%.

[0126] (Heat resistance test of optical film II: Evaluation of haze change) The optical film was cut into 50mm x 50mm sections to obtain film samples. The haze of these film samples was measured to obtain the haze value Hz0 before the heat resistance test. Subsequently, the film sample was placed between clean paper and subjected to a heat resistance test II, which involved placing it in a 105°C constant temperature bath for 24 hours without securing it with tape. After that, the haze of the film sample was measured, and the haze Hz1 after the heat resistance test was obtained. The haze measurements mentioned above were performed using an NDH-7000 (manufactured by Nippon Denshoku) in accordance with JIS K7361-1997. A lower haze value is preferable; for example, if the haze Hz1 after the heat resistance test is 1% or less, the heat resistance can be judged to be good.

[0127] In other words, the heat resistance can be evaluated based on the haze Hz1 after the aforementioned heat resistance test, according to the following evaluation criteria. Heat resistance "Good": Haze Hz1 after heat resistance test is 1% or less. Heat resistance "poor": Haze Hz1 after heat resistance test exceeds 1%.

[0128] (Transmittance of crossed nicols in optical film Tx(%)) A film sample was obtained by cutting an optical film into a 4cm x 4cm section. The obtained film sample was placed between two linear polarizers (polarizer and analyzer). The linear polarizers were oriented so that their polarization transmission axes were perpendicular to each other when viewed from the thickness direction. The crossed nicol transmittance was measured by automatic detection using a spectrophotometer "V7200" and an automatic polarizing film measuring device "VAP-7070S" manufactured by JASCO. The measurement wavelength was 550nm. The smaller the crossed nicol transmittance, the more suppressed the crystallization of the crystalline polymer is, and the more the variation in the polarization state of linearly polarized light transmitted through the optical film is suppressed.

[0129] [Manufacturing Example 1. Manufacturing of crystalline resin A containing crystalline polymer] A metal pressure reactor was thoroughly dried and then purged with nitrogen. To this metal pressure reactor, 154.5 parts of cyclohexane, 42.8 parts of a 70% cyclohexane solution of dicyclopentadiene (endo-isomer content of 99% or more) (30 parts of dicyclopentadiene), and 1.9 parts of 1-hexene were added, and the mixture was heated to 53°C.

[0130] A solution was prepared by dissolving 0.014 parts of tetrachlorotungstenphenylimide (tetrahydrofuran) complex in 0.70 parts of toluene. To this solution, 0.061 parts of a 19% diethylaluminum ethoxide / n-hexane solution were added and stirred for 10 minutes to prepare a catalyst solution. This catalyst solution was added to a pressure reactor to initiate the ring-opening polymerization reaction. The reaction was then carried out for 4 hours at a temperature of 53°C to obtain a solution of the ring-opened polymer of dicyclopentadiene. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the obtained ring-opened polymer of dicyclopentadiene were 8,750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) was 3.21.

[0131] To 200 parts of the solution of the obtained ring-opened polymer of dicyclopentadiene, 0.037 parts of 1,2-ethanediol were added as a stopping agent, and the mixture was heated to 60°C and stirred for 1 hour to stop the polymerization reaction. To this, 1 part of a hydrotalcite-like compound (Kyowa Chemical Industry Co., Ltd. "Kyoword® 2000") was added, and the mixture was heated to 60°C and stirred for 1 hour. Subsequently, 0.4 parts of a filtration aid (Showa Chemical Industry Co., Ltd. "Radiolite® #1500") was added, and the adsorbent and solution were filtered off using a PP pleated cartridge filter (ADVANTEC Toyo Co., Ltd. "TCP-HX").

[0132] To 200 parts (30 parts polymer) of a filtered solution of the ring-opened polymer of dicyclopentadiene, 100 parts of cyclohexane were added, and 0.0043 parts of chlorohydridecarbonyltris(triphenylphosphine)ruthenium were added. A hydrogenation reaction was carried out at a hydrogen pressure of 6 MPa and 180°C for 4 hours. This yielded a reaction solution containing the hydride of the ring-opened polymer of dicyclopentadiene. The hydride precipitated from this reaction solution, forming a slurry solution.

[0133] The hydride and solution contained in the reaction mixture were separated using a centrifuge and dried under reduced pressure at 60°C for 24 hours to obtain 28.5 parts of a crystalline dicyclopentadiene ring-opening polymer hydride. This hydride was a crystalline cyclic olefin polymer with a hydrogenation rate of 99% or more, a glass transition temperature (Tg) of 93°C, a melting point (Tm) of 266°C, and a racemo-dyad ratio of 89%.

[0134] 100 parts of the obtained hydride of the ring-opening polymer of dicyclopentadiene were mixed with 1.1 parts of an antioxidant (tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane; "Irganox® 1010" manufactured by BASF Japan), and then fed into a twin-screw extruder (product name "TEM-37B", manufactured by Toshiba Machine Co., Ltd.) equipped with four die holes with an inner diameter of 3 mmΦ. The mixture of the hydride of the ring-opening polymer of dicyclopentadiene and the antioxidant was formed into strands by hot melt extrusion, and then shredded with a strand cutter to obtain pellet-shaped crystalline resin A. The operating conditions of the twin-screw extruder were as follows. Barrel temperature setting = 270~280℃ Die setting temperature = 250℃ • Screw rotation speed = 145 rpm

[0135] [Manufacturing Example 2. Production of crystalline resin A' containing crystalline polymer] Norbornene ring-opening polymer hydride was produced according to the description in Production Example 1 of Japanese Patent Publication No. 2007-016102. This norbornene ring-opening polymer hydride is a crystalline cyclic olefin polymer with a hydrogenation rate of 99% or more, a glass transition temperature (Tg) of -6°C, and a melting point (Tm) of 142°C.

[0136] [Manufacturing Example 3. Production of amorphous resin B' containing amorphous polymer] A norbornene ring-opening polymer hydride was produced according to the description in Production Example 3 of Japanese Patent Publication No. 2007-016102. This norbornene ring-opening polymer hydride is an amorphous cyclic olefin polymer with a hydrogenation rate of 99% or more, a glass transition temperature (Tg) of 138°C, and no melting point (Tm) was observed.

[0137] [Example 1] (1-1. Manufacturing of mixed resin D) A pelletized amorphous resin B (ZEONEX790R, manufactured by Nippon Zeon Co., Ltd.) containing 99% by weight of an amorphous cyclic olefin polymer (glass transition temperature 163°C) was prepared. Crystalline resin A and amorphous resin B were mixed in a weight ratio of crystalline resin A:amorphous resin B = 7:3 and fed into the hopper of a twin-screw compounding extruder (ratio of effective screw length L to screw diameter D L / D = 41, screw diameter = 25 mm). After twin-screw compounding of crystalline resin A and amorphous resin B in the extruder, the mixture was extruded from the extruder in a strand form and shredded using a strand cutter to obtain pelletized mixed resin D. The operating conditions of the twin-screw compounding extruder were as follows. Barrel temperature setting = 275~280℃ Die setting temperature = 275℃ • Screw rotation speed = 200 rpm

[0138] The glass transition temperature Tgd, melting point Tmd, and cold crystallization temperature Tcd of the obtained mixed resin D were measured using the method described above.

[0139] (1-2. Manufacturing of resin films) The mixed resin D produced in the above step (1-1) was molded using a hot melt extrusion film molding machine equipped with a T-die to obtain a long resin film (thickness 75 μm) with a width of approximately 400 mm. The obtained resin film was wound up into a roll. The operating conditions of the film molding machine were as follows. Barrel setting temperature = 280℃~300℃ Die temperature = 270℃ Cast roll temperature = 90°C

[0140] (1-3. Stretching of resin film) The long resin film produced in the above process (1-2) was pulled from the roll and cut to obtain a rectangular resin film measuring 100 mm in length and 100 mm in width. This resin film was supplied to a stretching machine (manufactured by Eto Co., Ltd.), and each of the four sides of the resin film was gripped with five clips. Subsequently, the resin film was preheated by heating it at a preheating temperature of 124°C for 6 minutes. Next, the resin film was uniaxially stretched in the longitudinal direction of the long resin film before cutting at a stretching temperature of 124°C for 30 seconds at a stretching ratio of 2.5 times to obtain an optical film. The obtained optical films were evaluated using the method described above.

[0141] [Example 2] The weight ratio of crystalline resin A to amorphous resin B to be mixed was changed to crystalline resin A:amorphous resin B = 6:4. In addition, the preheating temperature and stretching temperature during the stretching of the resin film were changed to 133°C. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0142] [Example 3] The weight ratio of crystalline resin A to amorphous resin B to be mixed was changed to crystalline resin A:amorphous resin B = 5:5. In addition, the preheating temperature and stretching temperature during the stretching of the resin film were changed to 145°C. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0143] [Example 4] The weight ratio of crystalline resin A to amorphous resin B to be mixed was changed to crystalline resin A:amorphous resin B = 4:6. In addition, the preheating temperature and stretching temperature during the stretching of the resin film were changed to 150°C. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0144] [Example 5] The weight ratio of crystalline resin A to amorphous resin B to be mixed was changed to crystalline resin A:amorphous resin B = 6:4. In addition, the resin film was not stretched, and the unstretched resin film itself was evaluated as an optical film. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0145] [Example 6] The weight ratio of crystalline resin A to amorphous resin B to be mixed was changed to crystalline resin A:amorphous resin B = 6:4. In addition, the preheating temperature and stretching temperature during the stretching of the resin film were changed to 150°C. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0146] [Comparative Example 1] Crystalline resin A was used instead of mixed resin D, without mixing crystalline resin A and amorphous resin B. Furthermore, the preheating temperature and stretching temperature were changed to 117°C during the stretching of the resin film. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0147] [Comparative Example 2] Crystalline resin A was used instead of mixed resin D without mixing crystalline resin A and amorphous resin B. Furthermore, during the stretching of the resin film, the preheating temperature and stretching temperature were changed to 160°C, and the stretching ratio was changed to 1.02 times. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1. In the inventors' studies, it was found that when a film of crystalline resin A is stretched significantly at the aforementioned stretching temperature, the film whitens and the haze increases significantly. Therefore, in Comparative Example 2, the stretching ratio is smaller than in the other examples and comparative examples.

[0148] [Comparative Example 3] The weight ratio of crystalline resin A to amorphous resin B to be mixed was changed to crystalline resin A:amorphous resin B = 9:1. In addition, the preheating temperature and stretching temperature during the stretching of the resin film were changed to 121°C. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0149] [Comparative Example 4] Instead of mixing crystalline resin A and amorphous resin B, amorphous resin B was used in place of mixed resin D. Furthermore, the resin film was not stretched; the unstretched resin film itself was evaluated as an optical film. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0150] [Comparative Example 5] Instead of crystalline resin A and amorphous resin B, crystalline resin A' from Production Example 2 and amorphous resin B' from Production Example 3 were mixed in a weight ratio of crystalline resin A':amorphous resin B' = 2:8. Furthermore, the resin film was not stretched, and the unstretched resin film itself was evaluated as an optical film. Except for the above, the optical film was manufactured and evaluated using the same method as in Example 1.

[0151] [result] The results of the above-mentioned examples and comparative examples are shown in the table below. In the table below, the meanings of the abbreviations are as follows. COP: Cyclic olefin polymer Mixing ratio A / B (A' / B'): The weight ratio A / B of crystalline resin A and amorphous resin B. Or, the weight ratio A' / B' of crystalline resin A' and amorphous resin B'.

[0152] [Table 1]

[0153] [Table 2]

[0154] [Table 3]

Claims

1. An optical film formed from a resin containing a crystalline polymer having a melting point and an amorphous polymer not having a melting point, The crystalline polymer is a cyclic olefin polymer having a melting point. An optical film wherein the resin has a glass transition temperature Tgd that satisfies the following formula (1), and a cold crystallization temperature Tcd that satisfies the following formula (2). 100℃<Tgd<140℃ (1) 170℃<Tcd<225℃ (2)

2. An optical film formed from a resin comprising a crystalline polymer having a melting point and an amorphous polymer not having a melting point, The amorphous polymer is a cyclic olefin polymer that does not have a melting point. An optical film wherein the resin has a glass transition temperature Tgd that satisfies the following formula (1), and a cold crystallization temperature Tcd that satisfies the following formula (2). 100℃<Tgd<140℃ (1) 170℃<Tcd<225℃ (2)

3. The optical film according to claim 2, wherein the crystalline polymer is a cyclic olefin polymer having a melting point.

4. An optical film formed from a resin containing a crystalline polymer having a melting point and an amorphous polymer not having a melting point, The crystalline polymer is a cyclic olefin polymer having a melting point. The resin is an optical film having a melting point Tmd and a glass transition temperature Tgd that satisfy the following formula (3). 50°C ≤ Tmd - Tgd ≤ 160°C (3)

5. An optical film formed from a resin comprising a crystalline polymer having a melting point and an amorphous polymer not having a melting point, The amorphous polymer is a cyclic olefin polymer that does not have a melting point. The resin is an optical film having a melting point Tmd and a glass transition temperature Tgd that satisfy the following formula (3). 50°C ≤ Tmd - Tgd ≤ 160°C (3)

6. The optical film according to claim 5, wherein the crystalline polymer is a cyclic olefin polymer having a melting point.

7. A step of mixing a crystalline polymer having a melting point with an amorphous polymer not having a melting point to obtain a resin having a glass transition temperature Tgd satisfying the following formula (1) and a cold crystallization temperature Tcd satisfying the following formula (2), The process includes molding the aforementioned resin to obtain a resin film, The crystalline polymer is a cyclic olefin polymer having a melting point. A method for producing an optical film, wherein the step of obtaining the resin is a step of kneading the crystalline polymer and the amorphous polymer in a molten state to obtain the resin. 100℃<Tgd<140℃ (1) 170℃<Tcd<225℃ (2)

8. A step of mixing a crystalline polymer having a melting point and an amorphous polymer not having a melting point to obtain a resin having a glass transition temperature Tgd satisfying the following formula (1) and a cold crystallization temperature Tcd satisfying the following formula (2), The process includes molding the aforementioned resin to obtain a resin film, The amorphous polymer is a cyclic olefin polymer that does not have a melting point. A method for producing an optical film, wherein the step of obtaining the resin is a step of kneading the crystalline polymer and the amorphous polymer in a molten state to obtain the resin. 100℃<Tgd<140℃ (1) 170℃<Tcd<225℃ (2)

9. A method for manufacturing an optical film according to claim 7 or 8, comprising the step of stretching the resin film.

10. The method for manufacturing an optical film according to claim 9, wherein the stretching temperature in the step of stretching the resin film is Tgd or higher and Tcd - 30°C or lower.

11. A step of mixing a crystalline polymer having a melting point and an amorphous polymer not having a melting point to obtain a resin having a melting point Tmd and a glass transition temperature Tgd that satisfy the following formula (3), The process includes molding the aforementioned resin to obtain a resin film, The crystalline polymer is a cyclic olefin polymer having a melting point. A method for producing an optical film, wherein the step of obtaining the resin is a step of kneading the crystalline polymer and the amorphous polymer in a molten state to obtain the resin. 50°C ≤ Tmd - Tgd ≤ 160°C (3)

12. A step of mixing a crystalline polymer having a melting point and an amorphous polymer not having a melting point to obtain a resin having a melting point Tmd and a glass transition temperature Tgd that satisfy the following formula (3), The process includes molding the aforementioned resin to obtain a resin film, The amorphous polymer is a cyclic olefin polymer that does not have a melting point. A method for producing an optical film, wherein the step of obtaining the resin is a step of kneading the crystalline polymer and the amorphous polymer in a molten state to obtain the resin. 50°C ≤ Tmd - Tgd ≤ 160°C (3)

13. A method for manufacturing an optical film according to claim 11 or 12, comprising the step of stretching the resin film.

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