TW202248359A - Optical film and manufacturing method therefor - Google Patents

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 DEG C < Tgd < 140 DEG C (2): 170 DEG C < Tcd < 225 DEG C (3) 50 DEG C ≤ Tmd-Tgd ≤ 160 DEG C.

Description

Optical thin film and its manufacturing method

The present invention relates to optical films and methods for their manufacture.

In the past, thin films for optical applications were generally made of amorphous polymers. However, amorphous polymers tend to have poor solvent resistance. Therefore, it has been proposed to manufacture a film excellent in solvent resistance by combining an amorphous polymer and a crystalline polymer together with a resin (Patent Documents 1 and 2).

"Patent Documents" "Patent Document 1": Japanese Patent Laid-Open No. 2002-249645 "Patent Document 2": Japanese Patent Laid-Open No. 2007-016102

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

In addition, when a film formed of a resin composed of an amorphous polymer and a crystalline polymer is combined, for example, when linearly polarized light is transmitted through the film, the polarization state of the transmitted light may be changed. uneven.

The present invention was made in view of the aforementioned problems, and an object of the present invention is to provide an optical film excellent in both solvent resistance and heat resistance, and a method for producing the same. Furthermore, an object of the present invention is to provide an optical film and a method for producing the same, which suppress variation in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film.

The inventors of the present invention have devoted themselves to research in order to solve the aforementioned problems. As a result, the present inventors found out that the solvent resistance of an optical film formed of a resin comprising a crystalline polymer having a melting point and an amorphous polymer having no melting point and having a glass transition temperature and a cold crystallization temperature in a specific range It is excellent in both properties and heat resistance, and is formed of a resin that includes a crystalline polymer with a melting point and an amorphous polymer without a melting point and has a melting point and a glass transition temperature of the resin satisfying a specific relationship The optical film can solve the above-mentioned problems by suppressing the variation of the polarization state of the above-mentioned transmitted light, etc., and further complete the present invention.

That is, the present invention includes the following.

[1] An optical film formed of a resin comprising a crystalline polymer having a melting point and an amorphous polymer having no melting point, wherein The aforementioned resin has a glass transition temperature Tgd satisfying the following formula (1) and a cold crystallization temperature Tcd satisfying the following formula (2). 100℃＜Tgd＜140℃ (1) 170℃＜Tcd＜225℃ (2)

[2] An optical film formed of a resin comprising a crystalline polymer having a melting point and an amorphous polymer having no melting point, wherein The aforementioned resin has a melting point Tmd and a glass transition temperature Tgd satisfying the following formula (3). 50℃≦Tmd−Tgd≦160℃ (3)

[3] The optical film as described in [1] or [2], wherein the crystalline polymer is a cycloolefin polymer having a melting point.

[4] The optical film according to any one of [1] to [3], wherein the amorphous polymer is a cycloolefin polymer having no melting point.

[5] A method for manufacturing an optical thin film, comprising: Mixing a crystalline polymer having a melting point and an amorphous polymer having no 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) process, and The process of molding the aforementioned resin to obtain a resin film. 100℃＜Tgd＜140℃ (1) 170℃＜Tcd＜225℃ (2)

[6] The method for producing an optical film according to [5], which includes the step of stretching the resin film.

[7] The method for producing an optical film according to [6], wherein the stretching temperature in the step of stretching the resin film is not less than Tg and not more than Tcd−30°C.

[8] A method for manufacturing an optical film, comprising: a process of mixing a crystalline polymer having a melting point and an amorphous polymer having no melting point to obtain a resin having a melting point Tmd and a glass transition temperature Tgd satisfying the following formula (3), and The process of molding the aforementioned resin to obtain a resin film. 50℃≦Tmd−Tgd≦160℃ (3)

[9] The method for producing an optical film according to [8], which includes the step of stretching the resin film.

According to the present invention, an optical film excellent in both solvent resistance and heat resistance and a method for producing the same can be provided. Furthermore, according to the present invention, it is possible to provide an optical film and a method for producing the optical film that suppress variations in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film.

Embodiments and examples are disclosed below to describe the present invention in detail. However, the present invention is not limited to the implementation forms and examples disclosed below, and can be implemented with arbitrary changes within the scope not departing from the patent application scope of the present invention and its equivalent scope.

In the following description, a polymer having positive intrinsic birefringence means a polymer whose refractive index in the extending direction becomes larger than that in a direction perpendicular thereto, unless otherwise noted. Also, the polymer having negative intrinsic birefringence means a polymer whose refractive index in the extending direction becomes smaller than that in a direction perpendicular thereto, unless otherwise noted.

In the following explanations, the so-called "strip-shaped" film refers to a film having a length of 5 times or more relative to the width, preferably 10 times or more in length, and specifically refers to a film that can be rolled up. A film of sufficient length to be stored or transported in roll form. The upper limit of the length of the film is not particularly limited, and may be, for example, 100,000 times or less relative to the width.

In the following description, the in-plane retardation Re, unless otherwise noted, is the value represented by Re=(nx−ny)×d. Also, the retardation Rth in the thickness direction is a value represented by Rth={[(nx+ny)/2]−nz}×d unless otherwise noted. Furthermore, the so-called birefringence Δn, unless otherwise noted, is a value represented by nx−ny, and accordingly, a value represented by Re/d. Here, nx represents the refractive index which is the direction (in-plane direction) perpendicular to the thickness direction and the direction which gives the maximum refractive index. ny represents the refractive index in the direction perpendicular to the nx direction which is the aforementioned in-plane direction. nz represents the refractive index in the thickness direction. d represents the thickness. Measurement wavelength, unless otherwise noted, is 590 nm.

[1. Outline of Optical Films]

An optical film related to an embodiment of the present invention is formed of a resin including a crystalline polymer having a melting point and an amorphous polymer having no melting point. Hereinafter, the aforementioned resin containing a crystalline polymer and an amorphous polymer may be referred to as "hybrid resin". Since the optical film is formed of a mixed resin, it usually contains the mixed resin, preferably only the mixed resin.

An optical film related to an embodiment of the present invention includes at least any one of the following configurations: (1) a composition in which the mixed resin has a glass transition temperature Tgd in a specific range and a cold crystallization temperature Tcd in a specific range, and (2) the mixed resin It has a melting point Tmd and a glass transition temperature Tgd that satisfy a specific relationship. In the following, the case of including the constitution of (1) is referred to as the first embodiment, the case of including the constitution of (2) is referred to as the second embodiment, and the case of including both of (1) and (2) is referred to as the second embodiment. Three implementation types are used for illustration.

[1.1. Optical film related to the first embodiment]

The optical film according to the first embodiment is formed of a mixed resin including a crystalline polymer having a melting point and an amorphous polymer not having a melting point.

The mixed resin has a specific range of glass transition temperature Tgd and a specific range of cold crystallization temperature Tcd. The optical film formed by this mixed resin can be excellent in both solvent resistance and heat resistance.

[1.1.1. Crystalline polymers]

A crystalline polymer means a polymer having crystallinity. A crystalline polymer means a polymer having a melting point. The melting point of a polymer can be measured using a Differential Scanning Calorimeter (DSC). Accordingly, the term "crystalline polymer" refers to a polymer whose melting point can be observed with a differential scanning calorimeter (DSC).

A crystalline polymer may have positive intrinsic birefringence or negative intrinsic birefringence. Among them, crystalline polymers having positive intrinsic birefringence are preferable.

Examples of crystalline polymers include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); polyolefins such as polyethylene (PE) and polypropylene (PP). ; etc., but cycloolefin polymers are preferred. That is, the crystalline polymer is preferably a cycloolefin polymer having a melting point. Hereinafter, a cycloolefin-based polymer having a melting point may be referred to as a "cycloolefin-based crystalline polymer".

The cycloolefin-based crystalline polymer has an alicyclic structure in its molecule. Such a cycloolefin-based crystalline polymer is, for example, a polymer obtained by polymerization using a cycloolefin as a monomer or a hydrogenated product thereof. In the case of using a mixed resin containing a cycloolefin-based crystalline polymer, mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability, and light weight of an optical film can be optimized.

As an alicyclic structure, a cycloalkane structure and a cycloalkene structure are mentioned, for example. Among these, the cycloalkane structure is preferable in terms of being easy to obtain an optical film excellent in characteristics such as thermal stability. The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, and preferably 30 or less, preferably 20 or less, especially 15 or less good. When the number of carbon atoms contained in one alicyclic structure is within the above range, mechanical strength, heat resistance, and formability can be highly balanced.

In the cycloolefin-based crystalline polymer, the ratio of structural units having an alicyclic structure to all structural units is preferably at least 30% by weight, more preferably at least 50% by weight, and most preferably at least 70% by weight . When the ratio of the structural unit having an alicyclic structure is as large as described above, heat resistance can be improved. The ratio of the structural unit having an alicyclic structure to all the structural units must be 100% by weight or less. In addition, in the cycloolefin-based crystalline polymer, residues other than structural units having an alicyclic structure are not particularly limited, and may be appropriately selected depending on the purpose of use.

Examples of the cycloolefin-based crystalline polymer include the following polymers (α) to (δ). Among them, the polymer (β) is preferable in terms of being easy to obtain an optical film excellent in heat resistance. Polymer (α): A ring-opened polymer of a cycloolefin monomer and having crystallinity. Polymer (β): A hydrogenated product of the polymer (α) having crystallinity. Polymer (γ): an addition polymer of a cycloolefin monomer and has crystallinity. Polymer (δ): A hydrogenated product of polymer (γ) that has crystallinity.

Specifically, as a crystalline polymer containing an alicyclic structure, a ring-opening polymer of dicyclopentadiene and having crystallinity and a hydrogenated product of a ring-opening polymer of dicyclopentadiene having crystallinity are preferable. good. Among them, a hydrogenated product of a ring-opening polymer of dicyclopentadiene and having crystallinity is particularly preferable. Here, the ring-opened polymer of dicyclopentadiene means that the ratio of structural units derived from dicyclopentadiene to all structural units is usually at least 50% by weight—preferably at least 70% by weight, preferably at least 90% by weight. More preferably, more than 100% by weight is a polymer.

The hydrogenated product of the ring-opened polymer of dicyclopentadiene is preferably high in the ratio of racemic dyads. Specifically, the ratio of the racemic diunits of the repeating unit in the hydrogenated product of the ring-opened polymer of dicyclopentadiene is preferably 51% or more, preferably 70% or more, and 85% or more For Yu Jia. A high proportion of racemic dyads indicates high entropy stereoisomerism. Accordingly, the higher the ratio of the racemic diad, the higher the melting point of the hydrogenated product of the ring-opened polymer of dicyclopentadiene tends to be.

The ratio of the racemic dyads can be determined by ¹³ C-NMR spectral analysis as described in Examples described later.

As the polymer (α) to polymer (δ), polymers obtained by the production method disclosed in International Patent Publication No. 2018/062067 can be used.

The melting point Tma of the crystalline polymer is preferably at least 200°C, more preferably at least 230°C, and more preferably at most 290°C. When a crystalline polymer having such a melting point Tma is used, an optical film having a better balance between formability and heat resistance can be obtained.

Generally, a crystalline polymer has a glass transition temperature Tga. The specific glass transition temperature Tga of the crystalline polymer is not particularly limited, but is usually not less than 85°C and usually not more than 170°C.

The glass transition temperature Tga of the crystalline polymer is preferably lower than the glass transition temperature Tgb of the 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.

The absolute value |Tga−Tgb| of the difference between the glass transition temperature Tga of the crystalline polymer and the glass transition temperature Tgb of the amorphous polymer is preferably within a specific range. Specifically, the absolute value |Tga−Tgb| is preferably above 30°C, more preferably above 40°C, especially above 50°C, preferably below 100°C, and more preferably below 90°C. , preferably below 80°C. When the absolute value |Tga−Tgb| is within the aforementioned range, the solvent resistance, heat resistance, and flexibility of the optical film can be effectively improved.

The glass transition temperature and melting point of polymers can be measured by the following methods. First, the polymer is melted by heating, and the melted polymer is rapidly cooled with dry ice. Next, using this polymer as a test object, the glass transition temperature and melting point of the polymer were measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C/min (heating mode).

The weight average molecular weight (Mw) of the crystalline polymer is preferably at least 1,000, more preferably at least 2,000, preferably at most 1,000,000, more preferably at most 500,000. A crystalline polymer having such a weight average molecular weight has an excellent balance between molding processability and heat resistance.

The molecular weight distribution (Mw/Mn) of the crystalline polymer is preferably at least 1.0, more preferably at least 1.5, preferably at most 4.0, more preferably at most 3.5. Here, Mn represents a number average molecular weight. A crystalline polymer having such a molecular weight distribution is excellent in molding processability.

The weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of the polymer can be measured as polystyrene-equivalent values by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent. Also, when the polymer is not soluble in cyclohexane, toluene is used as a solvent, and the weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) are measured as polyisoprene conversion values.

The crystallinity of the crystalline polymer contained in the optical film is usually 0% or more, preferably 20% or less, more preferably 15% or less, more preferably 10% or less, and most preferably 5% or less . The crystallinity of crystalline polymers can be measured by X-ray diffraction.

A crystalline polymer may be used individually by 1 type, and may use it combining 2 or more types by arbitrary ratios.

The amount of the crystalline polymer contained in the mixed resin is preferably at least 30% by weight, more preferably at least 35% by weight, particularly preferably at least 40% by weight, and more than 80% by weight relative to 100% by weight of the mixed resin. The following is preferable, preferably below 75% by weight, especially preferably below 70% by weight. When the amount of the crystalline polymer is within the aforementioned range, the solvent resistance, heat resistance, and flexibility of the optical film can be effectively improved.

The weight ratio Wa/Wb of the amount Wa of the crystalline polymer and the amount Wb of the amorphous polymer contained 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, especially greater than 40/60, and preferably less than 80/20, and less than 75 /25 is better. When the weight ratio Wa/Wb is within the aforementioned range, the solvent resistance, heat resistance, and flexibility of the optical film can be effectively improved.

In addition, the total amount of the crystalline polymer and the amorphous polymer contained in the mixed resin is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, based on 100% by weight of the mixed resin. , more preferably 80% by weight to 100% by weight, more preferably 90% by weight to 100% by weight, and most preferably 95% by weight to 100% by weight.

[1.1.2. Amorphous polymer]

An amorphous polymer means a polymer that does not have crystallinity. The polymer having no crystallinity means a polymer having no melting point. Accordingly, an amorphous polymer means a polymer whose melting point cannot be observed with a differential scanning calorimeter (DSC).

Amorphous polymers can have either positive or negative intrinsic birefringence. Among them, an amorphous polymer having positive intrinsic birefringence is preferable.

As the amorphous polymer, a cycloolefin-based polymer is preferable. That is, the amorphous polymer is preferably a cycloolefin polymer having no melting point. Hereinafter, a cycloolefin-based polymer having no melting point may be referred to as a "cycloolefin-based amorphous polymer". The cycloolefin-based amorphous polymer is excellent in mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability, and light weight.

The cycloolefin-based amorphous polymer has a ring structure in its molecule. Usually, the structural unit of the polymer of the cycloolefin-based amorphous polymer has an alicyclic structure. The cycloolefin-based amorphous polymer is a polymer having an alicyclic structure in the main chain, a polymer having an alicyclic structure in the side chain, a polymer having an alicyclic structure in the main chain and the side chain, and the like. A mixture of two or more in any ratio. Among them, the cycloolefin-based amorphous polymer preferably has an alicyclic structure in the main chain from the viewpoint of mechanical strength and heat resistance.

As an alicyclic structure, a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene, cycloalkyne) structure are mentioned, for example. Among them, from the viewpoint of mechanical strength and heat resistance, the cycloalkane structure and the cycloalkene structure are preferable, and the cycloalkane structure is particularly preferable.

The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, and preferably 30 or less, preferably 20 or less, especially 15 or less good. When the number of carbon atoms constituting the alicyclic structure falls within this range, mechanical strength, heat resistance, and formability can be highly balanced.

In the cycloolefin-based amorphous polymer, the ratio of the structural unit having an alicyclic structure to all the structural units is preferably at least 55% by weight, more preferably at least 70% by weight, especially at least 90% by weight good. When the ratio of the structural unit which has an alicyclic structure with respect to all structural units exists in this range, transparency and heat resistance tend to become favorable.

As cycloolefin-based amorphous polymers, for example: norrylene-based polymers, monocyclic cycloolefin-based polymers, cyclic conjugated diene-based polymers, vinyl alicyclic hydrocarbon-based polymers, and Such hydrides, etc. Among them, the formability of northene-based polymers and their hydrogenated products is good.

Examples of norrene-based polymers and hydrogenated products thereof include ring-opening polymers of monomers having a norrene structure and hydrogenated products thereof, addition polymers of monomers having a norrene structure and their hydrogenated products. Hydride. In addition, examples of ring-opening polymers of monomers having a northylene structure include ring-opening homopolymers of one type of monomer having a northylene structure, and ring-opening homopolymers of two or more types of monomers having a northylene structure. Ring-opening copolymers of monomers, and ring-opening copolymers of monomers having a northylene structure and other monomers that can be copolymerized with them. Furthermore, examples of addition polymers of monomers having a northylene structure include addition homopolymers of one type of monomer having a northylene structure, and two or more types of monomers having a norghene structure. Addition copolymers of monomers, as well as addition copolymers of monomers with a northylene structure and other monomers that can be copolymerized with it. Examples of such polymers include polymers disclosed in Japanese Patent Laid-Open No. 2002-321302, International Patent Laid-Open No. 2017/145718, and the like. Among these, hydrogenated products of ring-opening polymers of monomers having a northylene structure are particularly suitable from the viewpoints of formability, heat resistance, low moisture absorption, dimensional stability, and light weight.

Examples of monomers having a nor-alene structure include: bicyclo[2.2.1]hept-2-ene (common name: nor-alene), tricyclo[4.3.0.1 ^2,5 ]dec-3,7 -Diene (common name: dicyclopentadiene), tetracyclo[4.4.0.1 ^2,5 .1 ^7,10 ]dode-3-ene (common name: tetracyclododecene), etc. do not contain aromatic ring structure Noralene-based monomers; 5-phenyl-2-northene, 5-(4-methylphenyl)-2-northene, 5-(1-naphthyl)-2-northene, 9 -(2-nor-en-5-yl)carbazole and other nor-alkene monomers with aromatic substituents; 1,4-methylbridge-1,4,4a,4b,5,8,8a,9a -Octahydrofen, 1,4-Abridge-1,4,4a,9a-Tetrahydrofen (common name: Abridge Tetrahydrofen), 1,4-Abridge-1,4,4a,9a-tetrahydro Hydrogen dibenzofuran, 1,4-methyl-1,4,4a,9a-tetrahydrocarbazole, 1,4-methyl-1,4,4a,9,9a,10-hexahydroanthracene, 1 , 4-methyl-bridge-1,4,4a,9,10,10a-hexahydrophenanthrene is equal to nor-alkene-based monomers containing nor-alkene ring structure and aromatic ring structure in the fused ring structure; and derivatives of these compounds substances (such as those having substituents on the ring); etc.

Examples of substituents include alkyl groups such as methyl groups, ethyl groups, propyl groups, and isopropyl groups; alkylene groups; alkenyl groups; polar groups; As a polar group, a heteroatom or a group which has a heteroatom, etc. are mentioned, for example. As a hetero atom, an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, a halogen atom, etc. are mentioned, for example. Specific examples of polar groups include halogen groups such as fluorine, chlorine, bromine, and iodine; carboxyl; carbonyloxycarbonyl; epoxy; hydroxyl; oxy; alkoxy; ester; silanol ; silicon group; amino group; nitrile group; sulfonic acid group; cyano group; amido group; imide group; etc. The number of substituents may be one or two or more. In addition, the types of two or more substituents may be the same or different. However, from the viewpoint of obtaining an amorphous polymer with low saturated water absorption and excellent moisture resistance, the northylene-based monomer preferably has a small amount of polar groups, and preferably has no polar groups.

Examples of cycloolefin-based amorphous polymers by trade name include: "ZEONEX" manufactured by Nippon Zeon Corporation, "ARTON" manufactured by JSR Corporation, "APEL" manufactured by Mitsui Chemicals Corporation, "TOPAS" manufactured by Polyplastics Corporation, etc. .

The glass transition temperature Tgb of the amorphous polymer is preferably above 90°C, more preferably above 100°C, more preferably above 110°C, preferably below 200°C, preferably below 190°C, It is better to be below 180°C. When the glass transition temperature Tgb of an amorphous polymer exists in the said range, both of the solvent resistance and heat resistance of an optical film can be improved effectively. Also, the elongation process can usually be performed smoothly.

The weight average molecular weight (Mw) of the amorphous polymer is preferably at least 10,000, more preferably at least 15,000, more preferably at least 20,000, preferably at most 100,000, preferably at most 80,000, and at most 50,000 For Yu Jia. When the weight average molecular weight is within the aforementioned range, the mechanical strength and molding processability of the mixed resin can be highly balanced.

The molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) of the amorphous polymer is preferably 1.2 or more, more preferably 1.5 or more, particularly preferably 1.8 or more, and preferably 3.5 or less , preferably below 3.0, especially below 2.7. When the molecular weight distribution is more than the lower limit value of the said range, the productivity of a polymer can be improved and manufacturing cost can be suppressed. In addition, since the amount of the low molecular weight component is less than the upper limit, relaxation at the time of exposure to high temperature can be suppressed, and the stability of the optical film can be improved.

Amorphous polymers may be used alone or in combination of two or more in arbitrary ratios.

The amount of the amorphous polymer contained in the mixed resin is preferably at least 20% by weight, more preferably at least 25% by weight, particularly preferably at least 30% by weight, and more than 70% by weight relative to 100% by weight of the mixed resin. % or less, preferably less than 65% by weight, particularly preferably less than 60% by weight. When the amount of the amorphous polymer is within the aforementioned range, both the solvent resistance and the heat resistance of the optical film can be effectively improved.

[1.1.3. Arbitrary ingredients]

The mixed resin may further include any components combined with the crystalline polymer and the non-crystalline polymer. Examples of optional components include antioxidants such as phenolic antioxidants, phosphorus antioxidants, and sulfur antioxidants; light stabilizers such as hindered amine light stabilizers; petroleum waxes, Fischer-Tropsch waxes, polyalkylene waxes, etc. Waxes; sorbitol-based compounds, metal salts of organic phosphoric acid, metal salts of organic carboxylic acids, kaolin and talc and other nucleating agents; diaminostilbene derivatives, coumarin derivatives, azole derivatives (such as benzene Fluorescent whitening such as oxazole derivatives, benzotriazole derivatives, benzimidazole derivatives and benzothiazole derivatives), carbazole derivatives, pyridine derivatives, naphthalene dicarboxylic acid derivatives and imidazolone derivatives UV absorbers; diphenyl ketone UV absorbers, salicylic acid UV absorbers, benzotriazole UV absorbers and other UV absorbers; colorants; flame retardants; flame retardant additives; antistatic agents; plasticizers agent; near-infrared absorber; slip agent; talc, silica, calcium carbonate, glass fiber and other inorganic fillers; etc. Optional components may be used individually by 1 type, and may be used combining 2 or more types by arbitrary ratios. The amount of the optional component is appropriately determined within the range that does not significantly impair the effect of the present invention. The amount of the optional components, for example, is in a range that can maintain the total light transmittance of the optical film at 85% or more.

[1.1.4. Properties of mixed resins]

The mixed resin has a glass transition temperature Tgd satisfying the following formula (1). 100℃＜Tgd＜140℃ (1)

Specifically, the glass transition temperature Tgd of the mixed resin is generally higher than 100°C, preferably higher than 102°C, especially preferably higher than 104°C, and usually less than 140°C, preferably less than 135°C, and at least Below 130°C is especially preferred.

The glass transition temperature Tgd of the mixed resin can be adjusted, for example, by adjusting the type and amount of a crystalline polymer and the type and amount of an amorphous polymer.

The glass transition temperature Tgd of the mixed resin can be measured by the same method as the measurement method of the glass transition temperature of the above-mentioned polymer.

The mixed resin has a cold crystallization temperature Tcd satisfying the following formula (2). 170℃＜Tcd＜225℃ (2)

Specifically, the cold crystallization temperature Tcd of the mixed resin is usually higher than 170°C, preferably higher than 175°C, especially preferably higher than 180°C, and usually less than 225°C, preferably less than 210°C, and at least Less than 205°C is preferred.

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

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

In the case where the mixed resin has the glass transition temperature Tgd satisfying the formula (1) and the cold crystallization temperature Tcd satisfying the formula (2), the optical film related to the first embodiment can improve the solvent resistance and Both are excellent in heat resistance.

The absolute value |Tgd−Tga| of 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 above 3°C, more preferably above 6°C, especially above 10°C, preferably below 45°C, more preferably below 40°C, It is especially preferred below 35°C. When the absolute value |Tgd−Tga| is in the aforementioned range, both the solvent resistance and the heat resistance of the optical film can be effectively improved.

The absolute value |Tgd−Tgb| of 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 above 20°C, more preferably above 30°C, especially above 35°C, preferably below 80°C, preferably below 70°C, It is especially preferred below 60°C. When the absolute value |Tgd−Tgb| is in the aforementioned range, both the solvent resistance and the heat resistance of the optical film can be effectively improved.

Hybrid resins generally have a melting point Tmd. The range of the melting point Tmd of the mixed resin is preferably above 200°C, more preferably above 230°C, more preferably above 240°C, and preferably below 290°C. When the mixed resin has the melting point Tmd in the aforementioned range, both the solvent resistance and the heat resistance of the optical film can be effectively improved.

The melting point Tmd of the mixed resin, for example, can be measured by the same method as the melting point of the above-mentioned polymer.

[1.1.5. Properties of optical films]

The optical film related to the first embodiment can have excellent solvent resistance. For example, when an optical film is immersed in toluene as a solvent at 23° C. for 30 seconds, the rate of change in film weight can be made positive. The film weight change rate is a ratio obtained by dividing the weight change amount of the optical film by the solvent immersion by the weight of the optical film before the solvent immersion. In addition, the amount of weight change of the optical film due to the solvent immersion is a value obtained by subtracting the weight of the optical film before the solvent immersion from the weight of the optical film after the solvent immersion. As mentioned above, the rate of change in film weight can be positive, indicating that the weight loss of the optical film due to dissolution into the solvent is suppressed. Normally, the optical film swells due to the infiltration of the solvent, and as a result, the weight change rate of the film becomes a positive value due to the increase in the weight of the optical film.

Moreover, since the optical film related to the first embodiment can have excellent solvent resistance, for example, when the optical film is bent, a drop of n-hexane as a solvent is dropped on the bent part, and the solvent is naturally dried, Cracks passing through the optical film can be prevented.

The optical film related to the first embodiment can have excellent heat resistance. According to this, the optical film can suppress a change in retardation in a high-temperature environment. For example, in the case of performing the heat resistance test I in which the optical film is stored at 95° C. for 24 hours, the rate of change in in-plane retardation (retardation change rate) due to the heat resistance test I can be reduced. Specifically, the delay change rate is preferably less than 2.5%, more preferably less than 2.0%, and most preferably less than 1.5%. The aforementioned heat resistance test I is usually carried out with the optical film sandwiched between dust-free papers in order to prevent the optical film from being fixed to the test bench. In addition, the retardation change rate represents the absolute value of the ratio obtained by dividing the amount of change in the 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. The amount of change in the in-plane retardation of the optical film represents the difference between the in-plane retardation of the optical film before the heat resistance test I and the in-plane retardation of the optical film after the heat resistance test I.

Since the optical film related to the first embodiment can have excellent heat resistance, an increase in haze in a high-temperature environment can be suppressed. For example, in the case of conducting the heat resistance test II in which the optical film is stored at 105° C. for 24 hours, it may have a small haze after the heat resistance test II. Specifically, the haze of the optical film after the heat resistance test II is preferably 2.0% or less, more preferably 1.0% or less, and most preferably 0.5% or less. The aforementioned heat resistance test II is the same as the heat resistance test I, and is usually performed with the optical film sandwiched between dust-free papers. The amount of haze was measured using NDH-7000 (manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K7361-1997.

The present inventors presume that the mechanism by which the optical film is excellent in both solvent resistance and heat resistance is as follows. However, the technical scope of the present invention is not limited by the mechanism shown below.

Conventionally, it has been known that a film comprising a resin combination of a crystalline polymer and an amorphous polymer exhibits excellent solvent resistance. However, according to the study of the present inventors, it is found that this film has poor heat resistance, and changes in retardation and increase in haze tend to occur in a high-temperature environment. The present inventors conceived that one of the reasons for the aforementioned change in retardation and increase in haze is the relaxation of orientation and the progress of crystallization.

Specifically, the molecules of the polymer contained in the optical film may undergo directional relaxation in a high-temperature environment. If such orientation relaxation occurs, the orientation direction of the molecules of the polymer may change. Furthermore, if the crystallization of the crystalline polymer proceeds in a high-temperature environment, the molecules of the crystalline polymer may change direction so that the regularity of their orientation increases. If so, the retardation of the film may change as a result of the change in the orientation state of the molecules in the film as a whole. Furthermore, if the crystallization of the crystalline polymer proceeds, spherulites may be generated in the thin film. The whitening of the film occurs due to the spherulites, and the haze increases.

On the other hand, in the optical film related to the above-mentioned first embodiment, since the mixed resin has a high glass transition temperature Tgd in a specific range, the relaxation of orientation can be suppressed. Furthermore, since the mixed resin has a high cold crystallization temperature Tcd in a specific range, progress of crystallization of the crystalline polymer can be suppressed. Therefore, the above-mentioned optical film can suppress a change in retardation and an increase in haze in a high-temperature environment, and exhibit excellent heat resistance. Furthermore, the mixed resin having a glass transition temperature Tgd and a cold crystallization temperature Tcd satisfying the specific ranges of formulas (1) and (2) can improve the solvent resistance because it has the aforementioned heat resistance and can also exhibit resistance to solvents. and heat resistance.

Optical films preferably have a large birefringence Δn. The specific birefringence range of the optical film is preferably above 0.00200, more preferably above 0.00205, and most preferably above 0.00210. In conventional crystalline polymers and amorphous polymers, the larger the birefringence, the lower the heat resistance tends to be. Accordingly, among films whose conventional problems have been particularly difficult to solve, an optical film preferably has a large birefringence Δn as described above from the viewpoint of effectively utilizing the effects of the present invention. The upper limit of the birefringence Δn is not particularly limited, for example, it may be 0.00400 or less, 0.00350 or less, and the like.

The birefringence Δn of the optical film can be obtained by dividing the in-plane retardation of the optical film by the thickness.

An optical film must have in-plane retardation according to its application. For example, the in-plane retardation Re of an optical film measured at a wavelength of 590 nm is preferably above 30 nm, preferably above 40 nm, especially preferably above 50 nm, and preferably below 300 nm, It is preferably below 290 nm, especially preferably below 280 nm.

The optical film must have retardation in the thickness direction according to its application. For example, the retardation Rth in the thickness direction of an optical film measured at a wavelength of 590 nm is preferably above 10 nm, preferably above 20 nm, especially preferably above 30 nm, and preferably below 300 nm , preferably below 250 nm, especially preferably below 200 nm.

The in-plane retardation and retardation in the thickness direction of the optical film were measured with a retardation meter ("AxoScanOPMF-1" manufactured by AXOMETRICS Corporation).

Optical films preferably have high transparency. The specific total light transmittance of the optical film is preferably above 80%, preferably above 85%, and most preferably above 88%. The total light transmittance of the film is measured using an ultraviolet-visible light spectrometer at a wavelength of 400 nm to 700 nm.

Optical films preferably have low haze. The haze of the optical film is preferably 2.0% or less, more preferably 1.0% or less, more preferably 0.5% or less, ideally 0.0%.

The optical film may be a film cut into sheets, or may be an elongated film having an elongated shape.

The optical film may have a single-layer structure having only one layer made of mixed resins having the same composition, or may have a multilayer structure including multiple layers made of mixed resins having different compositions.

Although the thickness of the optical film can be appropriately set according to the application of the optical film, it is generally desirable to be thin. The specific thickness of the optical film is preferably above 5 μm, more preferably above 10 μm, especially above 20 μm, preferably below 500 μm, preferably below 200 μm, and below 100 μm For Yu Jia.

[1.2. Optical film related to the second embodiment]

The optical film related to the second embodiment is formed of a mixed resin including a crystalline polymer having a melting point and an amorphous polymer not having a melting point.

The mixed resin has a melting point Tmd and a glass transition temperature Tgd satisfying a specific relationship. The optical film formed of the mixed resin can suppress the variation in the polarization state of the transmitted light when linearly polarized light is transmitted through the optical film.

The crystalline polymer, non-crystalline polymer and optional components used in the optical film related to the second embodiment are obtained from the crystalline polymer and non-crystalline polymer used in the optical film related to the first embodiment. The polymer and optional components are appropriately selected from those already described and used.

[1.2.1. Properties of mixed resins]

The mixed resin has a melting point Tmd and a glass transition temperature Tgd satisfying the following formula (3). 50℃≦Tmd−Tgd≦160℃ (3)

Specifically, 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, particularly preferably 120°C or higher, and usually 160°C Below, preferably below 155°C, more preferably below 150°C.

Hybrid resins generally have a cold crystallization temperature Tcd. In addition, the mixed resin preferably satisfies the following formula (4) in terms of cold crystallization temperature Tcd and glass transition temperature Tgd. 60℃≦Tcd−Tgd≦110℃ (4)

Specifically, the difference between the cold crystallization temperature Tcd and the glass transition temperature Tgd of the mixed resin is preferably above 60°C, more preferably above 70°C, preferably below 110°C, and preferably below 105°C .

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 a crystalline polymer and the type and amount of an amorphous polymer.

The melting point Tmd and glass transition temperature Tgd of the mixed resin, for example, can be measured by the same method as the melting point and glass transition temperature of the above-mentioned polymer. In addition, the cold crystallization temperature of the mixed resin can be measured by the same method as the measurement method of the cold crystallization temperature of the mixed resin related to the first embodiment.

The melting point Tmd, glass transition temperature Tgd, and cold crystallization temperature Tcd of the mixed resin must be selected and the optimal range can be made into the melting point Tmd, glass transition temperature Tgd, and cold crystallization temperature of the mixed resin related to the first embodiment. The obtained range and the good range of the transition temperature Tcd are the same.

[1.2.2. Characteristics of optical films]

The optical film related to the second embodiment can suppress the variation of the polarization state of the light passing through the film. For example, the crossed Nicolium transmittance Tx (%) of the optical film can be made to a small value. It is measured by the measurement of the penetration rate of Niko 騜鏡. Specifically, the crossed Nicolium transmittance Tx (%) of the optical film at a wavelength of 550 nm is preferably less than 0.04%, more preferably less than 0.03%, more preferably less than 0.02%, and preferably less than 0.01%. The following are preferred. In addition, the above-mentioned crossed Nicolium transmittance is ideally 0%, but it has to be, for example, 0.001% or more.

The transmittance of crossed Nicolium was measured using two linear polarizers (polarizer and analyzer), a spectrophotometer "V7200" manufactured by JASCO Corporation, and an automatic polarizing film measuring device "VAP-7070S".

The present inventors presume that the mechanism of the variation in the polarization state of the transmitted light when the optical film suppresses linearly polarized light to pass through the optical film as described above is as follows. However, the technical scope of the present invention is not limited by the mechanism shown below.

In the production process of a resin film comprising a combination of a crystalline polymer and an amorphous polymer, crystallization of the crystalline polymer proceeds to generate spherulites in the film. Since the spherulite itself has a phase difference different from that of the optical film, it scatters part of the light (polarized light) incident on the optical film, whereby the polarization state of the light passing through the optical film varies.

In addition, when the stretching process is performed during the production of the optical film, the molecules of the spherulites in the optical film are less likely to move than the molecules of the uncrystallized resin. Therefore, the molecular orientation of the uncrystallized resin is relatively large, and the molecular orientation of the spherulites is relatively small, or no orientation occurs. Accordingly, the orientation state of the molecules of the spherulites in the optical film and the molecules of the uncrystallized resin vary, and as a result, the polarization state of the light passing through the optical film varies.

On the other hand, in the optical film related to the second embodiment, since the melting point Tmd and the glass transition temperature Tgd of the mixed resin satisfy a predetermined relationship, it is possible to suppress the crystallization of the crystalline polymer during the production process of the optical film. Optical thin films are produced under conditions in which chemical processes are carried out. Therefore, in the optical film, when linearly polarized light is transmitted through the optical film, the variation in the polarization state of transmitted light must be suppressed.

Regarding the birefringence, retardation, transparency, haze, shape (cut into sheets, strips), layer structure, and thickness of the optical film, it can be made into an optical film related to the first embodiment mentioned above. Film items have the same content as described.

[1.3. Optical film related to the third embodiment]

The optical film related to the third embodiment is formed of a mixed resin including 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 in a specific range and a cold crystallization temperature Tcd in a specific range, and has a melting point Tmd and a glass transition temperature Tgd of the mixed resin satisfying a specific relationship. The optical film formed by this mixed resin is excellent in both solvent resistance and heat resistance, and it is possible to suppress variation in the polarization state of transmitted light when linearly polarized light is transmitted through the optical film.

The mixed resin related to the third embodiment has both the characteristics of the mixed resin related to the first embodiment and the properties of the mixed resin related to the second embodiment. Specifically, the mixed resin has a melting point Tmd, a glass transition temperature Tgd, and a cold crystallization temperature Tcd satisfying the above-mentioned formulas (1) to (3). The mixed resin is preferably such that the melting point Tmd and the glass transition temperature Tgd satisfy the above-mentioned formula (4). Regarding the characteristics of the mixed resin, other than the above-mentioned points, it must be the same as that described as the characteristics of the mixed resin already described in the item of the optical film related to the first embodiment and the second embodiment described above. .

In addition, the characteristics of the crystalline polymer, non-crystalline polymer, optional components and optical film used in the optical film related to the third embodiment can be made to be the same as those in the first embodiment and the first embodiment mentioned above. The contents of the optical film items related to the two implementation types are the same as those already described.

[2. Manufacturing method of optical film]

The optical film mentioned above, for example, can be produced by a method comprising the following steps: a step (1) of mixing a crystalline polymer and an amorphous polymer to obtain a mixed resin, and Step (2) of molding the mixed resin to obtain a resin film. In this case, the aforementioned resin film can also be obtained as an optical film.

Moreover, the manufacturing method of the optical film may further include: Step (3) of stretching the resin film. In the production method including the step (3), the resin film may be made into a stretched stretched film to obtain an optical film.

In step (1), a crystalline polymer and an amorphous polymer are mixed to obtain a mixed resin. The mixing method is not particularly limited. For example, it is also possible to knead a crystalline polymer and an amorphous polymer in a molten state to obtain a mixed resin. For the aforementioned kneading, for example, a twin-screw extruder may be used.

In the step (1), any one of the mixed resins described in the item of the optical film related to the above-mentioned first embodiment to the third embodiment can be obtained.

In step (2), the mixed resin is molded to obtain a resin film. The molding method of the mixed resin is not limited. As a molding method, an extrusion molding method, a solution casting method, an inflation molding method, etc. are mentioned, for example. Among them, the extrusion molding method and the solution casting method are preferable, and the extrusion molding method is particularly preferable.

Extrusion methods generally involve melt extrusion of mixed resins. The production 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, more preferably below Tmd+50°C. Also, the cooling member that the molten resin extruded into a film form first contacts is not particularly limited, but casting rolls are generally used. The casting roll temperature is preferably above Tgd−50°C, and preferably below Tgd+70°C.

In step (3), the resin film is stretched. By this stretching, since the molecules of the polymer in the resin film are oriented, an optical film having good optical characteristics can be obtained. This extension is preferably performed at an extension temperature that does not reach the cold crystallization temperature Tcd of the mixed resin. The specific extension temperature is preferably above Tgd°C, preferably above Tgd+10°C, especially preferably above Tgd+15°C, preferably below Tcd−20°C, preferably below Tcd−25°C, and preferably below Tcd−25°C. It is better below −30°C, especially below Tcd−50°C. When stretching is performed at a stretching temperature within this range, the progress of crystallization of the crystalline polymer can be suppressed, and the molecules of the polymer in the resin film can be effectively oriented. According to this, a rise in haze can be suppressed, while allowing the film to easily express desired optical characteristics.

The elongation ratio of the aforementioned elongation is set according to the optical characteristics that the optical film should have. The specific elongation ratio is preferably greater than 1 time, more preferably 1.1 times or more, more preferably 1.2 times or more, and preferably less than 5 times, preferably less than 4 times, and especially less than 3 times. good. In the case of biaxial stretching, it is preferable that the overall stretching ratio represented by the product of the stretching ratio in one direction and the stretching ratio in the other direction falls within the aforementioned range.

The aspect of the above stretching may be, for example, uniaxial stretching that stretches in one direction, or biaxial stretching that stretches in two non-parallel directions. Furthermore, the biaxial stretching may be simultaneous biaxial stretching in which stretching is performed in two directions at the same time, or sequential biaxial stretching in which stretching is performed in one direction and then stretched in the other direction.

The method for producing an optical film may further include combining any steps with the aforementioned steps (1) to (3). For example, the manufacturing method of the optical film may also include the step of preheating the resin film before stretching in the step (3). The preheating temperature is preferably above "extension temperature -40°C", preferably above "extension temperature -30°C", and preferably below "extension temperature +20°C", and below "extension temperature +15°C" better.

In addition, as an arbitrary process, the process of trimming an optical film, the process of surface-treating an optical film, etc. are mentioned.

"Example"

Examples are disclosed below to specifically illustrate the present invention. However, the present invention is not limited to the embodiments disclosed below, and can be implemented with arbitrary changes within the scope not departing from the patent application scope of the present invention and its equivalent scope.

In the following descriptions, "%" and "parts" indicating amounts are based on weight unless otherwise noted. In addition, the operations described below were performed under normal temperature and normal pressure (23° C., 1 atmosphere) atmospheric conditions unless otherwise noted.

[Evaluation method]

(Measurement method of weight average molecular weight Mw and number average molecular weight Mn of polymers)

The weight average molecular weight Mw and the number average molecular weight Mn of the polymer were measured as polystyrene-equivalent values using a gel permeation chromatography (GPC) system ("HLC-8320" manufactured by Tosoh Corporation). In the measurement, an H-type column (manufactured by Tosoh Corporation) was used as a column, and tetrahydrofuran was used as a solvent. In addition, the temperature at the time of measurement was 40 degreeC.

(Measurement method of hydrogenation rate of polymer)

The hydrogenation rate of the polymer was measured by ¹ H-NMR using o-dichlorobenzene-d ₄ as a solvent at 145°C.

(Measuring method of glass transition temperature, cold crystallization temperature and melting point)

The glass transition temperatures Tga, Tgb and Tgd, cold crystallization temperature Tcd, and melting points Tma and Tmd of samples (polymers or resins in the following examples) were measured as follows.

First, the sample is melted by heating. The melted samples were rapidly cooled using dry ice. Next, use a differential scanning calorimeter (DSC) on this sample to measure the glass transition temperature Tga, Tgb or Tgd, cold crystallization temperature Tcd, and melting point at a heating rate of 10°C/min (heating mode). Tma and Tmd. The so-called cold crystallization temperature Tcd is defined as the peak value of the exothermic peak during the heating process.

(Measurement method for the ratio of racemic dyads in polymers)

The measurement of the ratio of the racemic dyads of the polymer is carried out as follows.

Using o-dichlorobenzene-d ₄ as a solvent, the ¹³ C-NMR measurement of the polymer was performed at 200° C. using the inverse-gated decoupling method. In this ¹³ C-NMR measurement result, the 127.5 ppm peak of o-dichlorobenzene-d ₄ was set as the reference shift, and the 43.35 ppm signal derived from the meso diad was identified as the signal derived from the racemic The 43.43 ppm signal of the two-unit group. From the ratio of the intensities of these signals, the ratio of the racemic dyads in the polymer is found.

(Measurement method of film thickness)

The thickness of the film was measured using a contact thickness gauge (Code No. 543-390 manufactured by MITUTOYO Corporation).

(Measurement method of in-plane retardation Re, thickness direction retardation Rth and birefringence Δn of film)

The in-plane retardation Re of the film and the retardation Rth in the thickness direction were measured with a phase difference meter (“AxoScan OPMF-1” manufactured by AXOMETRICS Corporation). At this time, the measurement was performed at a wavelength of 590 nm. Furthermore, the birefringence Δn was calculated by the following formula (X1) using the in-plane retardation Re and the thickness d. Δn[-]=Re[nm]/d[nm] (X1)

(Solvent Resistance Test I for Optical Films)

The optical film was cut into 4 cm×4 cm to obtain a film sample. The weight of the film sample was measured to obtain the film weight before solvent immersion.

Thereafter, the entire film sample was immersed in toluene as a solvent for 30 seconds, taken out, and the solvent on the surface of the film sample was wiped with Kim Wipes. The film sample was dried at room temperature for 30 minutes, and the film weight after solvent immersion was measured. The film weight change rate was calculated by 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)

From the aforementioned film weight change rate, the 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 swells in the solvent. Solvent resistance "poor": film weight change rate is negative. Or the film sample has holes or damage. This result indicates that the optical film is dissolved in the solvent.

(Solvent Resistance Test II for Optical Films)

The optical film was cut into 5 cm × 2 cm to obtain a film sample. This film sample was bent so that the creases were parallel to the short sides at the center of the long sides, and the edges of the short sides were clamped and fixed with jigs. The radius of curvature of the bend of the film sample was made 2.5 mm. Next, the film sample was set on the platform so that the aforementioned creases became the top and the jigs became the bottom. Afterwards, use a dropper to drop 1 drop (about 1 mL) of n-hexane as a solvent on the bend (top) of the film sample, let the solvent dry naturally, remove the clamp and observe whether the penetration caused by the crack occurs. The solvent resistance can be evaluated based on the following evaluation criteria from the presence or absence of penetration due to cracks. Solvent resistance "good": no penetration caused by cracks. Or no crack itself. Solvent resistance "Poor": Penetration caused by cracks occurs.

(Heat Resistance Test I of Optical Films: Evaluation of Retardation Change Rate)

The optical film was cut into 50 mm×50 mm to obtain a film sample. By measuring the in-plane retardation of the film sample by the method mentioned above, the in-plane retardation Re0 before the heat resistance test was obtained.

Afterwards, the film sample was sandwiched between dust-free paper and not fixed with adhesive tape, and placed in a constant temperature chamber at 95°C for 24 hours to perform heat resistance test I. Afterwards, the in-plane retardation of the film sample was measured by the above-mentioned method to obtain the in-plane retardation Re1 after the heat resistance test. The delay change rate was calculated by the following formula (X3). The smaller the retardation change rate, the better the heat resistance of the optical film. For example, when the retardation change rate is 2.5% or less, it can be judged that the heat resistance is good. Re change rate (%) = | (Re1−Re0) / Re0 | × 100 (X3)

That is, from the aforementioned Re change rate (%), heat resistance can be evaluated in accordance with the following evaluation criteria. Heat resistance "good": Re change rate (%) is 2.5% or less. Heat resistance "poor": Re change rate (%) exceeds 2.5%.

(Heat Resistance Test II for Optical Films: Evaluation of Haze Change)

The optical film was cut into 50 mm×50 mm to obtain a film sample. Measure the haze of this film sample to obtain the haze Hz0 before the heat resistance test.

Afterwards, the film sample was sandwiched between dust-free paper and not fixed with adhesive tape, and placed in a constant temperature chamber at 105° C. for 24 hours to conduct heat resistance test II. Afterwards, measure the haze of the film sample to obtain the haze Hz1 after the heat resistance test.

The measurement of the aforementioned haze follows JIS K7361-1997, and is performed using NDH-7000 (manufactured by Nippon Denshoku Co., Ltd.).

The smaller the haze is, the better. For example, when the haze Hz1 after the heat resistance test is 1% or less, it can be judged that the heat resistance is good.

That is, from the haze Hz1 after the said heat resistance test, heat resistance can be evaluated according to the following evaluation criteria. Heat resistance "good": The haze Hz1 after the heat resistance test is 1% or less. "Poor" heat resistance: the haze Hz1 after the heat resistance test exceeds 1%.

(Orthogonal Nicolium transmittance Tx of optical film (%))

The optical film was cut into 4 cm×4 cm to obtain a film sample. Place the obtained film sample between two linear polarizers (polarizer and analyzer). At this time, the aforementioned linear polarizers are set in such a way that the polarized light transmission axes thereof become perpendicular to each other when viewed from the thickness direction. Using the spectrophotometer "V7200" manufactured by JASCO Corporation and the automatic polarizing film measuring device "VAP-7070S", the transmittance of crossed Nicolium was measured by automatic detection. The measurement wavelength was set at 550 nm.

The smaller the crossed Nicolium transmittance, it can be judged that the crystallization of the crystalline polymer is suppressed, and the variation of the polarization state of the linearly polarized light passing through the optical film is suppressed.

[Production example 1. Production of crystalline resin A containing crystalline polymer]

The metal pressure-resistant reactor was sufficiently dried and replaced with nitrogen. 154.5 parts of cyclohexane and 42.8 parts of a 70% cyclohexane solution of dicyclopentadiene (with an endo isomer content of 99% or more) were charged to this metal pressure-resistant reactor (the amount as dicyclopentadiene was 30 parts) and 1.9 parts of 1-hexene, heated to 53°C.

A solution was prepared by dissolving 0.014 parts of phenylimide tetrachloride (tetrahydrofuran) tungsten complex in 0.70 parts of toluene. To this solution was added 0.061 parts of diethylethoxyaluminum/n-hexane solution with a concentration of 19%, and stirred for 10 minutes to prepare a catalyst solution. Add the catalyst solution into the pressure-resistant reactor to start the ring-opening polymerization reaction. Thereafter, it was allowed to react for 4 hours while maintaining 53° C. to obtain a solution of a 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) obtained from these was 3.21.

0.037 parts of 1,2-ethylene glycol was added as a terminator to 200 parts of the obtained solution of the ring-opened polymer of dicyclopentadiene, heated to 60° C., and stirred for 1 hour to terminate the polymerization reaction. One part of a hydrotalcite-like compound (“KYOWAAD (registered trademark) 2000” manufactured by Kyowa Chemical Industry Co., Ltd.) was added thereto, heated to 60° C., and stirred for 1 hour. Thereafter, 0.4 part of filter aid ("RADIOLITE (registered trademark) #1500" manufactured by Showa Chemical Industry Co., Ltd.) was added, and the adsorbent and the solution were separated by filtration using a PP pleated cartridge filter ("TCP-HX" manufactured by Advantec Toyo Co., Ltd.).

Add 100 parts of cyclohexane to 200 parts of the filtered ring-opening polymer solution of dicyclopentadiene (30 parts of polymer), add 0.0043 parts of hydrochlorinated carbonyl ginseng (triphenylphosphine) ruthenium, and press the hydrogen pressure of 6 MPa , 180 ° C for 4 hours hydrogenation reaction. Thereby, the reaction liquid containing the hydrogenated product of the ring-opening polymer of dicyclopentadiene can be obtained. The hydride in the reaction solution was precipitated to form a slurry solution.

The hydride contained in the reaction liquid was separated from the solution using a centrifugal separator, and dried under reduced pressure at 60° C. for 24 hours to obtain 28.5 parts of a hydride of a ring-opened polymer of dicyclopentadiene having crystallinity. This hydrogenated product is a crystalline cycloolefin polymer with a hydrogenation rate of over 99%, a glass transition temperature Tg of 93°C, a melting point (Tm) of 266°C, and a racemic diad ratio of 89%.

In 100 parts of the hydrogenated product of the ring-opening polymer of dicyclopentadiene mixed antioxidant (tetra{3-[3',5'-bis(tertiary butyl)-4'-hydroxyphenyl]propionic acid Methylene}methane, 1.1 parts of "Irganox (registered trademark) 1010" manufactured by BASF Japan Co. , Toshiba Machine Co., Ltd.). The mixture of the hydrogenated ring-opening polymer of dicyclopentadiene and the antioxidant is formed into strands by hot-melt extrusion, and finely chopped with a strand pelletizer to obtain crystalline resin A in the form of pellets. The operating conditions of the aforementioned twin-screw extruder are as follows. ． Barrel set temperature = 270 ~ 280 ℃ ． Mold setting temperature = 250°C ． Screw revolutions = 145 rpm

[Production example 2. Production of crystalline resin A' containing crystalline polymer]

A northylene ring-opened polymer hydrogenated product was produced following the description in Production Example 1 of Japanese Patent Laid-Open No. 2007-016102. The northylene ring-opened polymer hydrogenated product is a crystalline cycloolefin polymer with a hydrogenation rate of over 99%, a glass transition temperature Tg of −6°C, and a melting point (Tm) of 142°C.

[Production Example 3. Production of Amorphous Resin B' Containing Amorphous Polymer]

A northylene ring-opened polymer hydrogenated product was produced following the description in Production Example 3 of Japanese Patent Laid-Open No. 2007-016102. This northylene ring-opened polymer hydrogenated product is an amorphous cycloolefin-based polymer with a hydrogenation rate of 99% or more, a glass transition temperature Tg of 138°C, and no melting point (Tm) observed.

[Example 1]

(1-1. Manufacture of Hybrid Resin D)

A granular amorphous resin B ("ZEONEX790R" manufactured by Zeon Corporation) containing 99% by weight of an amorphous cycloolefin-based polymer (glass transition temperature: 163° C.) was prepared. The crystalline resin A and the non-crystalline resin B are mixed in such a way that the weight ratio is crystalline resin A: non-crystalline resin B = 7:3, and put into a twin-shaft kneading extruder (the effective length L of the screw and The ratio of screw diameter D to L/D = 41, screw diameter = 25 mm) funnel. The crystalline resin A and the non-crystalline resin B are biaxially kneaded in the extruder, extruded into strands from the extruder, and finely chopped with a strand pelletizer to obtain the mixed resin D in granular form. The operating conditions of the aforementioned twin-screw kneading extruder are as follows. ． Barrel set temperature = 275 ~ 280 ℃ ． Mold setting temperature = 275°C ． Screw revolutions = 200 rpm

The glass transition temperature Tgd, the melting point Tmd and the cold crystallization temperature Tcd of the obtained mixed resin D were measured by the methods mentioned above.

(1-2. Manufacture of resin film)

The mixed resin D produced in the above step (1-1) was molded using a hot-melt extrusion film forming machine equipped with a T-die to obtain a long resin film (thickness 75 μm) with a width of about 400 mm. The obtained resin film is made into a roll form. The operating conditions of the aforementioned film forming machine are as follows. ． Barrel set temperature = 280 ° C ~ 300 ° C ． Mold temperature = 270°C ． Casting roll temperature = 90°C

(1-3. Stretching of resin film)

The strip-shaped resin film produced in the aforementioned process (1-2) was pulled out from the roll and cut to obtain a rectangular resin film with a length of 100 mm and a width of 100 mm. 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 clamped by five clamps. Thereafter, the resin film was preheated by heating at a preheating temperature of 124° C. for 6 minutes. Subsequently, the resin film was fixedly uniaxially stretched at a stretching temperature of 124° C. for 30 seconds at a stretching ratio of 2.5 times along the long-side direction of the strip-shaped resin film before cutting to obtain an optical film.

The obtained optical film was evaluated by the above-mentioned method.

[Example 2]

The weight ratio of the mixed crystalline resin A and amorphous resin B was changed to crystalline resin A:amorphous resin B=6:4. In addition, when stretching the resin film, the preheating temperature and the stretching temperature were changed to 133°C. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Example 3]

The weight ratio of the mixed crystalline resin A and amorphous resin B was changed to crystalline resin A:amorphous resin B=5:5. In addition, when stretching the resin film, the preheating temperature and the stretching temperature were changed to 145°C. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Example 4]

The weight ratio of the mixed crystalline resin A and amorphous resin B was changed to crystalline resin A:amorphous resin B=4:6. In addition, when stretching the resin film, the preheating temperature and the stretching temperature were changed to 150°C. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Example 5]

The weight ratio of the mixed crystalline resin A and amorphous resin B was changed to crystalline resin A:amorphous resin B=6:4. In addition, the stretching of the resin film was not performed, and the unstretched resin film itself was evaluated as an optical film. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Example 6]

The weight ratio of the mixed crystalline resin A and amorphous resin B was changed to crystalline resin A:amorphous resin B=6:4. In addition, when stretching the resin film, the preheating temperature and the stretching temperature were changed to 150°C. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Comparative Example 1]

The mixing of the crystalline resin A and the amorphous resin B was not performed, and the crystalline resin A was used instead of the mixed resin D. In addition, when stretching the resin film, the preheating temperature and the stretching temperature were changed to 117°C. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Comparative Example 2]

The mixing of the crystalline resin A and the amorphous resin B was not performed, and the crystalline resin A was used instead of the mixed resin D. In addition, when stretching the resin film, the preheating temperature and the stretching temperature were changed to 160° C., and the stretching ratio was changed to 1.02 times. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

According to the study of the present inventors, when the film of the crystalline resin A is largely stretched at the above-mentioned stretching temperature, it has been found that the film is whitened and the haze is greatly increased. Accordingly, in Comparative Example 2, the stretching ratio was made smaller than that of other Examples and Comparative Examples.

[Comparative Example 3]

The weight ratio of the mixed crystalline resin A and amorphous resin B was changed to crystalline resin A:amorphous resin B=9:1. In addition, when stretching the resin film, the preheating temperature and the stretching temperature were changed to 121°C. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Comparative Example 4]

The mixing of the crystalline resin A and the non-crystalline resin B was not performed, and the non-crystalline resin B was used instead of the mixed resin D. In addition, the stretching of the resin film was not performed, and the unstretched resin film itself was evaluated as an optical film. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[Comparative Example 5]

The crystalline resin A' of Production Example 2 and the non-crystalline resin B' of Production Example 3 were mixed in a weight ratio of crystalline resin A':non-crystalline resin B'=2:8, instead of the crystalline resin A and amorphous resin B. In addition, the stretching of the resin film was not performed, and the unstretched resin film itself was evaluated as an optical film. Production and evaluation of the optical film were performed by the same method as in Example 1 except for the above matters.

[result]

The results of the examples and comparative examples mentioned above are shown in the following table. In the following tables, the meanings of the abbreviations are as follows. COP: cycloolefin polymer Mixing ratio A/B (A′/B′): The weight ratio A/B of the crystalline resin A and the amorphous resin B. Or the weight ratio A'/B' of the crystalline resin A' to the non-crystalline resin B'.

[Table 1] [Table 1. Results of Examples 1-2 and Comparative Examples 1-4] Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Crystalline polymer type COP COP COP COP COP — Tga[°C] 93 93 93 93 93 — Tma[°C] 266 266 266 266 266 — amorphous polymer Zeonex 790R Zeonex 790R — — Zeonex 790R Zeonex 790R Tgb[°C] 163 163 — — 163 163 Mixing ratio A/B 70/30 60/40 — — 90/10 — Hybrid resin D Tgd[°C] 104 113 93 93 101 — Tcd[°C] 180 189 137 137 157 — Tmd[°C] 264 264 266 266 265 — extended conditions extension method fixed single axis fixed single axis fixed single axis fixed single axis fixed single axis — Preheating temperature[℃] 124 133 117 160 121 — Extension temperature [°C] 124 133 117 160 121 — Extension magnification [times] 2.5 2.5 2.5 1.02 2.5 — Optical film Re[nm] 100.3 71.0 61.9 51.2 59.9 — Rth[nm] 83.7 60.7 46.8 36.9 51.1 — d[μm] 31.0 31.0 31.0 65 31.0 — Δn[-] 0.00324 0.00229 0.00200 0.00079 0.00193 — Solvent resistance test I Before impregnation [g] 0.1223 0.1224 0.1123 0.0788 0.1262 0.1118 After impregnation [g] 0.134 0.1335 0.1208 0.0789 0.1355 There are holes and tatters Change rate[%] 9.6% 9.1% 7.6% 0.1% 7.4% x Heat resistance test I Re0[nm] 100.3 71.0 61.9 51.2 59.9 — Re1[nm] 100.2 70.4 25.8 51.0 54.9 — Change rate[%] 0.1% 0.9% 58.3% 0.4% 8.2% — Heat Resistance Test II Hz0[%] 0.21 0.23 0.33 2.25 0.22 — Hz1[%] 0.47 0.23 34.28 2.25 5.27 —

[Table 2] [Table 2. Results of Examples 1 to 6] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Crystalline polymer type COP COP COP COP COP COP Tga[°C] 93 93 93 93 93 93 Tma[°C] 266 266 266 266 266 266 amorphous polymer Zeonex 790R Zeonex 790R Zeonex 790R Zeonex 790R Zeonex 790R Zeonex 790R Tgb[°C] 163 163 163 163 163 163 Mixing ratio A/B 70/30 60/40 50/50 40/60 60/40 60/40 Hybrid resin D Tgd[°C] 104 113 120 125 113 113 Tcd[°C] 180 189 207 221 189 189 Tmd[°C] 264 264 258 257 264 264 Tmd−Tgd[°C] 160 151 138 132 151 151 extended conditions extension method fixed single axis fixed single axis fixed single axis fixed single axis — fixed single axis Preheating temperature[℃] 124 133 145 150 — 150 Extension temperature [°C] 124 133 145 150 — 150 Extension magnification [times] 2.5 2.5 3.0 3.0 — 3.0 Optical film Re[nm] 100.3 71 38.3 33.1 — 22.5 Rth[nm] 83.7 60.7 32.4 28.6 — 9.9 d[μm] 31 31 40 40 — 40 Δn[-] 0.00324 0.00229 0.00096 0.00083 — 0.00056 Solvent Resistance Test II Evaluation good good good good good good Heat resistance test I Evaluation good good good good good good Heat Resistance Test II Evaluation good good good good good good Orthogonal Nikolai Penetration Rate Tx[%] 0.008 0.007 0.005 0.003 0.002 0.028

[Table 3] [Table 3. Results of Comparative Examples 2 to 5] Comparative example 2 Comparative example 3 Comparative example 4 Comparative Example 5 Crystalline polymer type COP COP — COP Tga[°C] 93 93 — −6 Tma[°C] 266 266 — 142 amorphous polymer — Zeonex 790R Zeonex 790R Amorphous COP Tgb[°C] — 163 163 138 Mixing ratio A/B (A'/B') — 90/10 — 20/80 Hybrid resin D Tgd[°C] 93 101 — 109 Tcd[°C] 137 157 — Unobservable Tmd[°C] 266 265 — 138 Tmd−Tgd[°C] 173 164 — 29 extended conditions extension method fixed single axis fixed single axis — — Preheating temperature[℃] 160 121 — — Extension temperature [°C] 160 121 — — Extension magnification [times] 1.02 2.5 — — Optical film Re[nm] 51.2 59.9 — — Rth[nm] 36.9 51.1 — — d[μm] 65 31 — — Δn[-] 0.00079 0.00193 — — Solvent Resistance Test II Evaluation good good bad bad Heat resistance test I Evaluation good bad - good Heat Resistance Test II Evaluation bad bad - good Orthogonal Nikolai Penetration Rate Tx[%] 0.142 0.07 - 0.05

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Claims (9)

An optical film formed of a resin comprising a crystalline polymer having a melting point and an amorphous polymer having no melting point, wherein the aforementioned resin has a glass transition temperature Tgd satisfying the following formula (1) and Satisfy the cold crystallization temperature Tcd of the following formula (2): 100°C<Tgd<140°C (1); 170°C<Tcd<225°C (2). An optical film formed of a resin comprising a crystalline polymer having a melting point and an amorphous polymer having no melting point, wherein the aforementioned resin has a melting point Tmd and a glass transition satisfying the following formula (3) Temperature Tgd, 50℃≦Tmd−Tgd≦160℃ (3). The optical film according to claim 1 or 2, wherein the crystalline polymer is a cycloolefin polymer having a melting point. The optical film according to claim 1 or 2, wherein the amorphous polymer is a cycloolefin polymer having no melting point. A method for producing an optical film, comprising: mixing a crystalline polymer with a melting point and an amorphous polymer without a melting point to obtain a glass transition temperature Tgd satisfying the following formula (1) and satisfying the following formula (2 ) of the cold crystallization temperature Tcd resin process, and the process of forming the aforementioned resin to obtain a resin film; 100 ° C < Tgd < 140 ° C (1); 170 ° C < Tcd < 225 ° C (2). The method of manufacturing an optical film according to claim 5, which includes the step of stretching the resin film. The method for producing an optical film according to claim 6, wherein the stretching temperature in the step of stretching the resin film is not less than Tg and not more than Tcd−30°C. A method for producing an optical film, comprising: mixing a crystalline polymer having a melting point and an amorphous polymer having no melting point to obtain a resin having a melting point Tmd and a glass transition temperature Tgd satisfying the following formula (3) , and the process of molding the aforementioned resin to obtain a resin film; 50°C≦Tmd−Tgd≦160°C (3). The method of manufacturing an optical film according to claim 8, which includes the step of stretching the resin film.