WO2019026842A1

WO2019026842A1 - Optical film and method for manufacturing same

Info

Publication number: WO2019026842A1
Application number: PCT/JP2018/028445
Authority: WO
Inventors: 祐二柴田
Original assignee: 日本ゼオン株式会社
Priority date: 2017-08-02
Filing date: 2018-07-30
Publication date: 2019-02-07
Also published as: JP7140124B2; TW201910398A; JPWO2019026842A1

Abstract

Provided is an optical film obtained by roughening at least one surface of a film containing an alicyclic structure-containing polymer. At the at least one surface, a maximum height Rz is 150-3000 nm inclusive, and an arithmetic mean roughness Ra is 30-1000 nm inclusive. The optical film preferably has an internal haze of 5% or less. The alicyclic structure-containing polymer is preferably a specific block copolymer hydride [E]. A method for manufacturing the optical film is collectively disclosed, the method including a roughening step.

Description

Optical film and method of manufacturing the same

The present invention relates to an optical film and a method of manufacturing the same.

In a display device such as a liquid crystal display device, various optical elements such as a polarizing plate and a retardation plate are provided. Some of such optical elements are constituted by a film. For example, the polarizing plate generally includes a film-like polarizer formed of a material such as polyvinyl alcohol and a protective film for protecting such a polarizer. As an example of such a protective film, a film of a resin containing an alicyclic structure-containing polymer is known (see Patent Documents 1 and 2). A film of a resin containing an alicyclic structure-containing polymer can be usefully used as a protective film in a polarizing plate from the viewpoint of mechanical strength and optical properties.

JP 2007-245551 A JP 2011-013378 A

The polarizing plate is required to exhibit durability in the environment at the time of production and use of the display device. For example, in the case of rework at the time of manufacture of a display, and when a polarizer shrinks at the time of use of a display, etc., it may be called for that peeling strength of a protective film in a polarizing plate is high.

However, when a conventional resin film containing an alicyclic structure-containing polymer is used as a protective film, the peel strength may be insufficient. In particular, when the protective film is a stretched film produced through the process of stretching, it is caused by cohesive failure in the vicinity of the surface layer caused by the orientation of the polymer molecules being reduced and the entanglement between molecules being reduced, and the peel strength A lack of can occur.

Accordingly, an object of the present invention is to provide an optical film which has high peel strength and can be usefully used as a protective film, and a method for producing the same.

As a result of investigations to solve the problems described above and achieve the object, the present inventor has found that at least one surface of an optical film formed by roughening at least one surface of a film containing an alicyclic structure-containing polymer, By making maximum height Rz and arithmetic mean roughness Ra into a predetermined range, it discovers that the above-mentioned subject can be solved and completed the present invention.
That is, according to the present invention, the following [1] to [7] are provided.

[1] An optical film obtained by roughening at least one surface of a film containing an alicyclic structure-containing polymer,
An optical film having a maximum height Rz of 150 nm or more and 3000 nm or less and an arithmetic average roughness Ra of 30 nm or more and 1000 nm or less in at least one surface.
[2] The optical film according to [1], having an internal haze of 5% or less.
[3] The alicyclic structure-containing polymer is a block copolymer hydride [E],
The block copolymer hydride [E] is a hydride of the block copolymer [D],
The block copolymer [D] is composed of the polymer block [A] and the polymer block [B], or is composed of the polymer block [A] and the polymer block [C].
The polymer block [A] is a polymer block mainly composed of a repeating unit [I] derived from an aromatic vinyl compound,
The polymer block [B] is a polymer block mainly comprising a repeating unit [I] derived from an aromatic vinyl compound and a repeating unit [II] derived from a chain conjugated diene compound,
The optical film according to [1] or [2], wherein the polymer block [C] is a polymer block mainly composed of a repeating unit [II] derived from a chain conjugated diene compound.
[4] The optical film according to [3], wherein the retardation Re in the in-plane direction is 3 nm or less and the absolute value of the retardation Rth in the thickness direction is 3 nm or less.
[5] The optical film according to [1] or [2], wherein the alicyclic structure-containing polymer is crystalline and the degree of crystallinity is 1% or more.
[6] The optical film according to any one of [1] to [5], which is a polarizer protective film.
[7] A method for producing an optical film according to any one of [1] to [6],
A step of stretching a film containing an alicyclic structure-containing polymer, and a treatment step including at least one of the steps of heat curing the film;
And d) roughening at least one surface of the film after the processing step.

ADVANTAGE OF THE INVENTION According to the optical film of this invention, peeling strength is high and the film which can be usefully used as a protective film in a polarizing plate can be provided. Moreover, according to the method for producing an optical film of the present invention, such an optical film of the present invention can be easily produced.

Hereinafter, the present invention will be described in detail by way of embodiments and exemplifications. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented with arbitrary modifications without departing from the scope of the claims of the present invention and the equivalents thereof.

In the present application, a "long film" refers to a film having a length of 5 times or more, preferably 10 times or more of the width of the film, and specifically, It has a length that can be rolled up and stored or transported. The upper limit of the ratio of the length to the width of the film is not particularly limited, and may be, for example, 100,000 times or less.

In the following description, the retardation Re in the in-plane direction of the film is a value represented by Re = (nx−ny) × d unless otherwise specified. In addition, the retardation Rth in the film thickness direction is a value represented by Rth = {(nx + ny) / 2−nz} × d unless otherwise specified. Here, nx represents the refractive index in the direction (in-plane direction) perpendicular to the thickness direction of the film and in the direction giving the maximum refractive index. ny represents the refractive index of the in-plane direction of the film, which is perpendicular to the nx direction. nz represents the refractive index in the thickness direction of the film. d represents the thickness of the film. The measurement wavelength is 550 nm unless otherwise stated.

[1. Optical film]
The optical film of the present invention is obtained by roughening at least one surface of a film containing an alicyclic structure-containing polymer.

[1.1. Material of optical film]
The film containing an alicyclic structure-containing polymer may be usually made of a resin containing an alicyclic structure-containing polymer. Examples of the alicyclic structure-containing polymer include a crystalline alicyclic structure-containing polymer, an amorphous alicyclic structure-containing polymer, and an alicyclic structure-containing polymer which is a specific block copolymer hydride. Polymers may be mentioned.

[1.1.1. Crystalline alicyclic structure-containing polymer]
A crystalline polymer (polymer having crystallinity) refers to a polymer having a melting point (that is, the melting point can be observed with a differential scanning calorimeter (DSC)).

The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the molecule, and means a polymer obtainable by a polymerization reaction using a cyclic olefin as a monomer or a hydrogenated product thereof. Moreover, an alicyclic structure containing polymer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

As an alicyclic structure which an alicyclic structure containing polymer has, a cycloalkane structure and a cycloalkene structure are mentioned, for example. Among these, a cycloalkane structure is preferable because an optical film having excellent properties such as thermal stability is easily obtained. The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, preferably 30 or less, more preferably 20 or less, particularly preferably 15 or less. is there. When the number of carbon atoms contained in one alicyclic structure is in the above range, mechanical strength, heat resistance, and formability are highly balanced.

In the alicyclic structure-containing polymer, the ratio 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 . By increasing the proportion of the structural unit having an alicyclic structure in the alicyclic structure-containing polymer as described above, the effects of the present invention such as high flexibility can be further enhanced.
In addition, in the alicyclic structure-containing polymer, the balance other than the structural unit having an alicyclic structure is not particularly limited, and may be appropriately selected depending on the purpose of use.

The weight average molecular weight (Mw) of the alicyclic structure-containing polymer is preferably 1,000 or more, more preferably 2,000 or more, preferably 1,000,000 or less, more preferably 500,000 or less is there. The alicyclic structure-containing polymer having such a weight average molecular weight is excellent in the balance between moldability and flexibility.

The molecular weight distribution (Mw / Mn) of the alicyclic structure-containing polymer is preferably 1.0 or more, more preferably 1.5 or more, preferably 4.0 or less, more preferably 3.5 or less . Here, Mn represents a number average molecular weight. An alicyclic structure-containing 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 alicyclic structure-containing polymer can be measured as a polystyrene conversion value by gel permeation chromatography (GPC) using tetrahydrofuran as a developing solvent.

The glass transition temperature Tg of the alicyclic structure-containing polymer is not particularly limited, but is usually 85 ° C. or more, and usually 170 ° C. or less.

Examples of the above-mentioned alicyclic structure-containing polymer include the following polymers (α) to (6). Among these, a polymer (β) is preferable as the alicyclic structure-containing polymer having crystallinity since an optical film excellent in flexibility is easily obtained.
Polymer (α): A ring-opening polymer of a cyclic olefin monomer, which has crystallinity.
Polymer (β): A hydrogenated substance of the polymer (α) and having crystallinity.
Polymer (γ): Addition polymer of cyclic olefin monomer, which has crystallinity.
Polymer (δ): A hydrogenated substance of polymer (γ) or the like, which has crystallinity.

Specifically, as the alicyclic structure-containing polymer, a ring-opened polymer of dicyclopentadiene having crystallinity and a hydrogenated product of the ring-opened polymer of dicyclopentadiene, which is a crystal Those having a property are more preferable, and those having a crystallinity and being a hydrogenated product of a ring-opening polymer of dicyclopentadiene are particularly preferable. Here, the ring-opened polymer of dicyclopentadiene means that the ratio of structural units derived from dicyclopentadiene to the total structural units is usually 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more. Particularly preferred is 100% by weight of polymer.

The cyclic olefin monomer which can be used for producing the polymer (α) and the polymer (β) is a compound having a ring structure formed of carbon atoms and having a carbon-carbon double bond in the ring . Examples of cyclic olefin monomers include norbornene monomers. When the polymer (α) is a copolymer, a monocyclic olefin may be used as the cyclic olefin monomer.

The norbornene-based monomer is a monomer containing a norbornene ring. Examples of norbornene-based monomers include bicyclo [2.2.1] hept-2-ene (common name: norbornene), 5-ethylidene-bicyclo [2.2.1] hept-2-ene (common name). : A bicyclic monomer such as ethylidene norbornene) and a derivative thereof (for example, one having a substituent in the ring); tricyclo [4.3.0.12,5] deca-3,7-diene (common name) Tricyclic monomers such as dicyclopentadiene) and derivatives thereof; 7,8-benzotricyclo [4.3.0.12,5] dec-3-ene (conventional name: methanotetrahydrofluorene: 1) -4-Methano-1,4,4a, 9a-tetrahydrofluorene) and derivatives thereof, tetracyclo [4.4.0.12,5.17,10] dodec-3-ene (common name: tetracyclodo) De cent), 8- Chile Den tetracyclo [4.4.0.12,5.17,10] -3-like dodecene and derivatives thereof, 4-cyclic monomers; and the like.

As the substituent in the above-mentioned monomer, for example, alkyl groups such as methyl group and ethyl group; alkenyl groups such as vinyl group; alkylidene groups such as propan-2-ylidene; aryl groups such as phenyl group; An acid anhydride group; a carboxyl group; an alkoxycarbonyl group such as a methoxycarbonyl group; and the like. Moreover, the said substituent may have one type independently, and may have two or more types by arbitrary ratios.

Examples of single ring cyclic olefins include cyclic monoolefins such as cyclobutene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, cyclooctene and the like; cyclohexadiene, methylcyclohexadiene, cyclooctadiene, methylcyclooctadiene, phenylcyclo Cyclic diolefins such as octadiene; and the like.

A cyclic olefin monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. When two or more cyclic olefin monomers are used, the polymer (α) may be a block copolymer or a random copolymer.

Among cyclic olefin monomers, there may be those in which stereoisomers of endo form and exo form are present. As the cyclic olefin monomer, either an endo form or an exo form may be used. Also, only one of the endo and exo isomers may be used alone, or an isomer mixture containing the endo and exo isomers in any proportion may be used. Among them, the crystallinity of the alicyclic structure-containing polymer is increased, and a film which is more excellent in heat resistance is easily obtained. Therefore, it is preferable to increase the proportion of one stereoisomer. For example, the proportion of endo or exo is preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more. In addition, since the synthesis is easy, it is preferable that the proportion of the endo form is high.

The crystallinity of the polymer (α) and the polymer (β) can usually be increased by increasing the degree of syndiotactic stereoregularity (ratio of racemo dyad). From the viewpoint of increasing the degree of stereoregularity of the polymer (α) and the polymer (β), the ratio of racemo dyads to structural units of the polymer (α) and the polymer (β) is preferably 51%. The content is more preferably 60% or more, particularly preferably 70% or more.

The proportion of racemo dyads can be determined by ¹³ C-NMR spectral analysis. Specifically, it can be measured by the following method.
Inverse-gated decoupling method is applied at 200 ° C. using ortho-dichlorobenzene-d ⁴ as a solvent, and 13 C-NMR measurement of a polymer sample is performed. Based on the result of this 13 C-NMR measurement, the intensity ratio of the 43.35 ppm signal from the meso dyad and the 43.43 ppm signal from the racemo dyad with the 127.5 ppm peak of orthodichlorobenzene-d 4 as a reference shift The ratio of racemo dyads of the polymer sample can be determined based on

The cyclic olefin monomer used for producing the polymers (γ) and (δ) is selected from the range shown as cyclic olefin monomers usable for producing the polymer (α) and the polymer (β) A thing can be used arbitrarily. Moreover, a cyclic olefin monomer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

In the production of the polymer (γ), any monomer that can be copolymerized with the cyclic olefin monomer may be used as the monomer in combination with the cyclic olefin monomer. Examples of the optional monomer include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-pentene and 1-hexene; and aromatic ring vinyl compounds such as styrene and α-methylstyrene Non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene and 1,7-octadiene; and the like. Among these, α-olefins are preferable, and ethylene is more preferable. In addition, one type of arbitrary monomer may be used alone, or two or more types may be used in combination in an arbitrary ratio.

The ratio of the amount of the cyclic olefin monomer to the optional monomer is preferably 30:70 to 99: 1, more preferably 50: weight ratio (cyclic olefin monomer: optional monomer). 50 to 97: 3, particularly preferably 70:30 to 95: 5.

When using 2 or more types of cyclic olefin monomers, and when using combining a cyclic olefin monomer and arbitrary monomers, a polymer ((gamma)) may be a block copolymer and it is random. It may be a copolymer.

The alicyclic structure-containing polymer having crystallinity as described above can be produced, for example, by the method described in WO 2016/067893.

The proportion of the crystalline alicyclic structure-containing polymer in the crystalline resin is preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. The flexibility of the optical film can be enhanced by setting the ratio of the alicyclic structure-containing polymer having crystallinity to the lower limit value of the above range or more.

When the optical film of the present invention contains a crystalline polymer as the alicyclic structure-containing polymer, the degree of crystallinity is preferably 1% or more, more preferably 2% or more, still more preferably 3% or more It is. By having such a high degree of crystallinity, the optical film can be provided with high heat resistance and chemical resistance. Although the upper limit of the degree of crystallinity of the polymer having crystallinity is not limited, it is usually 90% or less. When the degree of crystallinity is less than or equal to the above upper limit value, the transparency of the optical film can be easily improved. The crystallinity of the polymer can be measured by X-ray diffraction.

The melting point of the crystalline polymer is preferably 200 ° C. or more, more preferably 230 ° C. or more, and preferably 290 ° C. or less. By using a polymer having such a melting point, an optical film further excellent in the balance between moldability and heat resistance can be obtained.

[1.1.2. Amorphous alicyclic structure-containing polymer]
Among the alicyclic structure-containing polymers described above, the non-crystalline alicyclic structure-containing polymer is one having no crystallinity. As an example of the monomer which comprises a non-crystalline alicyclic structure containing polymer, the thing similar to the example of the monomer which comprises the crystalline alicyclic structure containing polymer described above is mentioned. It can be mentioned. The non-crystalline alicyclic structure-containing polymer is obtained by polymerizing the above-mentioned monomers by a known polymerization method, and a polymer having a low degree of syndiotactic stereoregularity, a common atactic polymer or It can be produced by forming an isotactic polymer. The mode of polymerization may be either ring-opening polymerization or addition polymerization.

[1.1.3. Noncrystalline norbornene polymer]
In the case of the non-crystalline alicyclic structure-containing polymer other than the after-mentioned block copolymer hydride, specifically, in the case of a norbornene-based polymer, for example, the ring-opening weight of the norbornene-based monomer Coalescing, ring-opening copolymers of norbornene-based monomers and other monomers capable of ring-opening copolymerization, and hydrides thereof; addition polymers of norbornene-based monomers, norbornene-based monomers And addition copolymers with other polymerizable monomers. Among these, from the viewpoint of transparency, a hydrogenated ring-opened polymer of a norbornene-based monomer is particularly preferable.
The norbornene-based polymer may be selected from, for example, the polymers disclosed in JP-A-2002-321302.

The weight average molecular weight (Mw) when the non-crystalline alicyclic structure-containing polymer is a norbornene-based polymer is preferably 10,000 or more, more preferably 15,000 or more, particularly preferably 20,000. It is the above, Preferably it is 100,000 or less, More preferably, it is 80,000 or less, Especially preferably, it is 50,000 or less.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the norbornene-based polymer can be measured as a weight average molecular weight in terms of polyisoprene or polystyrene by gel permeation chromatography using cyclohexane as a solvent. If the sample is not soluble in cyclohexane, toluene may be used instead of cyclohexane as the solvent.

[1.1.4. Block copolymer hydride]
The block copolymer hydride which is an example of the alicyclic structure-containing polymer in the present invention may be crystalline or non-crystalline, but is usually non-crystalline.

Specific block copolymer hydrides [E] can be mentioned as block copolymer hydrides. The block copolymer hydride [E] is obtained by hydrogenating the carbon-carbon unsaturated bond of the main chain and the side chain of the specific block copolymer [D] and the carbon-carbon unsaturated bond of the aromatic ring. It is a compound having the resulting structure. The block copolymer [D] is composed of a specific polymer block [A] and a specific polymer block [B], or a specific polymer block [A] and a specific polymer block [C] It consists of Polymer block [A] is a polymer block which has as a main component repeating unit [I] derived from an aromatic vinyl compound. Polymer block [B] is a polymer block which has as a main component repeating unit [I] derived from an aromatic vinyl compound and repeating unit [II] derived from a chain conjugated diene compound. Polymer block [C] is a polymer block which has repeating unit [II] derived from a chain conjugated diene compound as a main component. In the present application, the term "main component" means one whose content is 50% by weight or more of the whole.
The repeating unit derived from a certain compound means a repeating unit having a structure obtained by polymerization of the compound. The hydride of a certain polymer refers to a substance having a structure obtained by hydrogenation of the polymer. However, the said repeating unit and the hydride are not limited by the manufacturing method.

The block copolymer [D] preferably has two or more polymer blocks [A] per molecule, and one or more polymer blocks [B] or polymer blocks [C] per molecule, What consists of is preferable. When the block copolymer [D] has two or more polymer blocks [A], these may be the same as or different from each other. Moreover, the weight average molecular weights of two polymer blocks [A] which one block copolymer [D] has may be the same or different.

The weight average molecular weight Mw (A) of the polymer block [A] is 3,000 to 90,000, preferably 3,500 to 80,000, and more preferably 4,000 to 60,000. When the Mw (A) of the polymer block [A] is 3,000 or more, the mechanical strength of the block copolymer hydride [E] can be improved. On the other hand, when the Mw (A) of the polymer block [A] is 90,000 or less, the melt formability of the block copolymer hydride [E] can be made favorable.

The weight fraction wA of all the polymer blocks [A] in the block copolymer [D] in the block copolymer [D], and the block copolymer of the polymer block [B] or the polymer block [C] It is preferable that the weight fraction wB in the combined [C] has a predetermined ratio. That is, the ratio of wA to wB (wA / wB) is preferably 50/50 or more, more preferably 53/47 or more, still more preferably 57/43 or more, and on the other hand preferably 95/5 or less, more preferably It is 85/15 or less. By making wA / wB below the above-mentioned upper limit, flexibility can be given to block copolymer hydride [E], and good mechanical strength can be given. Favorable heat resistance can be provided by making wA / wB more than the said minimum.

The hydrogenation rate of the block copolymer hydride [E] (proportion of the total unsaturation of the block copolymer [D], which is hydrogenated in the block copolymer hydride [E]) is preferably It is 90% or more, preferably 95% or more, more preferably 99% or more. The higher the degree of hydrogenation, the better the weather resistance, heat resistance and transparency of the molded article. The hydrogenation rate of the block copolymer hydride [E] can be determined by ¹ H-NMR or comparison of peak areas by UV detector and RI detector by GPC, or the like. Specifically, ¹ H-NMR can be measured at 145 ° C. using ortho-dichlorobenzene-d4 as a solvent.

The molecular weight of the block copolymer hydride [E] is preferably 40,000 or more, more preferably 41,000 or more, and more preferably 40,000 or more, more preferably 41,000 or more, in terms of polystyrene equivalent weight average molecular weight (Mw) measured by GPC using THF as a solvent. It is more preferably 45,000 or more, and preferably 150,000 or less, more preferably 130,000 or less, and still more preferably 100,000 or less. The molecular weight distribution (Mw / Mn) of the block copolymer hydride [E] is preferably 3 or less, more preferably 2 or less, and particularly preferably 1.5 or less. When Mw and Mw / Mn are in the above ranges, the heat resistance and the mechanical strength to the change in retardation of the formed stretched film are good.

Specific examples and production methods of the block copolymer hydride [E] include, for example, the specific examples and production methods disclosed in WO 2016/152871.

[1.1.5. Ratio of alicyclic structure-containing polymer]
When the optical film of the present invention is composed of a resin containing an alicyclic structure-containing polymer, the proportion of the alicyclic structure-containing polymer in the resin is preferably 50% by weight or more, more preferably 70% by weight or more. Particularly preferably, it is 90% by weight or more. By setting the ratio of the alicyclic structure-containing polymer within the above range, it is possible to obtain the advantage of the alicyclic structure-containing polymer such as high mechanical strength and good optical properties.

[1.1.6. Optional ingredient]
The resin which comprises an optical film may contain arbitrary components other than an alicyclic structure containing polymer.
Examples of optional components include crosslinking aids.
Examples of crosslinking assistants include oximes such as p-quinonedioxime and p, p'-dibenzoylquinone dioxime; ethylene dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, cyclohexyl methacrylate, acrylic acid / acrylic acid / Zinc oxide mixtures, acrylates or methacrylates such as allyl methacrylate; vinyl monomers such as divinylbenzene, vinyltoluene, vinylpyridine, etc. hexamethylenediallylnadiimide, diallyl itaconate, diallyl phthalate, diallyl isophthalate, triallyl cyanurate, trilyl Allyl compounds such as allyl isocyanurate; N, N'-m-phenylenebismaleimide, N, N '-(4,4'-methylenediphenylene) dimaleimide, etc. Mid compounds and the like. As the crosslinking assistant, one type may be used alone, or two or more types may be used in combination in an arbitrary ratio. From the viewpoint of improving the properties such as the electrical properties, heat resistance and solvent resistance of the stretched film obtained, allyl compounds are preferable, and in particular from the viewpoint of thermal stability, triallyl isocyanurate (TAIC) is most preferable.

Examples of other optional components include stabilizers such as antioxidants, ultraviolet light absorbers and light stabilizers; resin modifiers such as lubricants and plasticizers; colorants such as dyes and pigments; antistatic agents etc. A compounding agent is mentioned. These compounding agents can be used singly or in combination of two or more kinds, and the compounding amount thereof is appropriately selected as long as the object of the present invention is not impaired.

[2. Method of producing optical film]
The method for producing an optical film according to the present invention comprises a step of stretching a film containing an alicyclic structure-containing polymer, and a treatment step including at least one of the steps of heat curing the film, and after the treatment step. Roughening at least one side of the film. In the following description, the film containing the alicyclic structure-containing polymer before undergoing the treatment process may be referred to as a "raw film" for the purpose of distinguishing it from the film after undergoing the treatment process. Moreover, the film before passing through the roughening process may be called "film before roughening" among the films after passing through the treatment process, and the film after passing through the roughening process may be called "roughened film".

The raw film can be produced, for example, by molding a resin containing an alicyclic structure-containing polymer into a film. The molding method of the resin containing the alicyclic structure-containing polymer is not particularly limited, and a known method such as melt extrusion molding can be adopted.

The dimensions of the raw film can be appropriately set so as to obtain the desired dimensions as a product optical film. From the viewpoint of production efficiency, the raw film is preferably a long film. The thickness of the raw film is preferably 5 μm or more, more preferably 15 μm or more, and one side is preferably 200 μm or less, more preferably 170 μm or less.

[2.1. Processing process]
The processing step is any one of a step of stretching a film containing an alicyclic structure-containing polymer (stretching step) and a step of heat curing a film containing an alicyclic structure-containing polymer (heat curing step) Or both steps. When the heat curing step and the stretching step are both included, either step may be performed first.

[2.1.1. Stretching process]
In the stretching step, any mode such as uniaxial stretching or biaxial stretching may be employed. When the film before the stretching step is a long film, the stretching direction is the longitudinal direction (the direction parallel to the longitudinal direction of the long film), the transverse direction (the width direction of the long film) And a diagonal direction (a direction which is neither vertical nor horizontal).

The stretching ratio is preferably 1.05 times or more, more preferably 1.1 times or more, and on the other hand preferably 7 times or less, more preferably 6 times or less. The stretching temperature is preferably 80 ° C. or more, more preferably 100 ° C. or more, and preferably 200 ° C. or less, more preferably 180 ° C. or less.

A large-area film can be easily obtained by performing such stretching processing. In addition, when a film having retardation is required as a product, such retardation can be easily obtained. On the other hand, when a film with little retardation is required as a product, such a film can be easily obtained by adopting, for example, the above-mentioned block copolymer hydride [E] as the alicyclic structure-containing polymer Can be obtained. However, by performing such a stretching process, the obtained film can be a film that easily breaks cohesively when subjected to a tensile force in the thickness direction. Here, in the present invention, by roughening at least one surface of the film, it is possible to suppress the problem caused by cohesive failure, and therefore it is possible to achieve peel strength while enjoying the advantage obtained by stretching. It can be enhanced.

[2.1.2. Heat curing process]
A thermosetting process crystallizes the crystalline alicyclic structure containing polymer contained in a film, for example, when a film contains a crystalline alicyclic structure containing polymer as an alicyclic structure containing polymer. Forming a film containing the crystallized resin. In the heat curing step, the crystalline alicyclic structure-containing polymer is crystallized to obtain, for example, a film whose main component is a crystallized resin having a crystallization degree of 1% or more. The heat curing step can be carried out by bringing the film containing the alicyclic structure-containing polymer into a predetermined temperature range while holding and tensioning at least two ends. Hereinafter, the film containing the alicyclic structure-containing polymer to be subjected to the heat curing step is also referred to as a "film to be cured".

The state in which the film to be cured is in tension means the state in which the film to be cured is in tension. However, the state in which the film to be cured is tensioned does not include the state in which the film to be cured is substantially stretched. Further, being substantially stretched means that the stretching ratio in any direction of the film to be cured is usually 1.1 times or more.

When holding the film to be cured, the film to be cured is held by a suitable holder. The holder may be capable of continuously holding the entire length of the edge of the film to be cured, or may be intermittently held at intervals. For example, the edge of the film to be cured may be intermittently held by holders arranged at predetermined intervals.

In the heat curing step, the film to be cured is held in tension by holding at least two ends of the film to be cured. This prevents deformation due to thermal contraction of the film to be cured in the region between the held edges. In order to prevent deformation in a large area of the film to be cured, it is preferable to hold the edge including the two opposite edges to make the region between the held edges tensed. For example, in the case of a rectangular sheet-shaped film to be cured, the two opposing ends (for example, the ends on the long side or the ends on the short side) are held and the two end sides are held By making the area of the film in tension, deformation can be prevented on the entire surface of the film to be cured. Further, in the case of a long film to be cured, the two end sides at the ends in the width direction (that is, the end sides on the long side) are held to tension the region between the two end sides. Thus, deformation can be prevented on the entire surface of the long curing target film. Thus, the film to be cured that is prevented from being deformed is prevented from being deformed, such as wrinkles, even if stress is generated in the film due to heat contraction. When using the raw film after the stretching process as the film to be cured, the deformation is suppressed by holding at least two sides orthogonal to the stretching direction (in the case of biaxial stretching, the direction in which the stretching ratio is large). It will be more reliable.

In order to more reliably suppress deformation in the heat curing step, it is preferable to hold more edges. Therefore, for example, in the film to be cured of a single wafer, it is preferable to hold all the edges thereof. As a specific example, in the case of a rectangular sheet-shaped cured film, it is preferable to hold four sides.

As a holder which can hold | maintain the edge of a film for hardening, what does not contact with the film for hardening in parts other than the edge of a film for hardening is preferable. By using such a holder, an optical film having more excellent smoothness can be obtained.

Moreover, as a holder, what can fix the relative position of holders in a thermosetting process is preferable. In such a holder, since the positions of the holders do not move relative to each other in the heat curing step, it is easy to suppress the substantial stretching of the film to be cured in the heat curing step.

As a suitable holder, for example, as a holder for a rectangular film to be cured, a grip such as a clip which is provided at a predetermined interval in a mold and can hold an end side of the film to be cured can be mentioned. In addition, for example, as a holder for holding the two end sides at the end in the width direction of the long curing target film, a grip provided on a tenter stretching machine and capable of gripping the end side of the curing target film Can be mentioned.

When a long film to be cured is used, an end side at the longitudinal end of the film to be cured (that is, an end side on the short side) may be held, but instead of holding the above-mentioned side The film may be held on both sides in the longitudinal direction of the region to be subjected to the crystallization treatment of the film to be cured. For example, holding devices capable of holding and tensioning the film to be cured may be provided on both sides in the longitudinal direction of the region of the film to be cured that is to be subjected to the crystallization treatment. Examples of such a holding device include a combination of two rolls, a combination of an extruder and a take-up roll, and the like. By applying tension such as transport tension to the film to be cured by a combination of these, thermal contraction of the film to be cured can be suppressed in the region to be subjected to the crystallization process. Therefore, if the above combination is used as a holding device, the film to be cured can be held while the film to be cured is conveyed in the longitudinal direction, so that the optical film can be efficiently manufactured.

In the heat curing step, in a state in which at least two end sides of the film to be cured are held and tensioned as described above, the film to be cured is not less than the glass transition temperature Tg of the alicyclic structure-containing polymer, alicyclic The temperature is lower than the melting point Tm of the formula structure-containing polymer. In the film to be cured which has been set to the above temperature, crystallization of the alicyclic structure-containing polymer proceeds. Therefore, a film containing the crystallized alicyclic structure-containing polymer is obtained by this heat curing step. At this time, since the film containing the crystallized alicyclic structure-containing polymer is strained while preventing deformation of the film, crystallization can be promoted without impairing the smoothness of the film.

As described above, the temperature range in the heat curing step can be arbitrarily set in the temperature range of not less than the glass transition temperature Tg of the alicyclic structure-containing polymer and the melting point Tm of the alicyclic structure-containing polymer. Among them, the temperature is preferably set to increase the crystallization rate. The temperature of the film to be cured in the heat curing step is preferably Tg + 20 ° C. or more, more preferably Tg + 30 ° C. or more, preferably Tm-20 ° C. or less, more preferably Tm-40 ° C. or less. By setting the temperature in the heat curing step to the upper limit or less of the above range, the clouding of the optical film can be suppressed, and thus an optical film suitable for the case where an optically transparent film is required can be obtained.

As a heating device used in a thermosetting process, since a contact with a heating device and a hardening object film is unnecessary, a heating device which can raise atmosphere temperature of a hardening object film is preferred. Examples of suitable heating devices include ovens and furnaces.

In the heat curing step, the treatment time for maintaining the film to be cured in the above temperature range is preferably 1 second or more, more preferably 5 seconds or more, preferably 30 minutes or less, more preferably 10 minutes or less. The flexibility of the optical film can be enhanced by sufficiently advancing the crystallization of the alicyclic structure-containing polymer in the heat curing step. In addition, by setting the treatment time to the upper limit or less of the above range, the clouding of the optical film can be suppressed, so that an optical film suitable for the case where an optically transparent film is required can be obtained.

[2.2. Roughening process]
The roughening step is a step of roughening at least one surface of the raw film (film before roughening) after the treatment step. In the roughening step, the maximum height Rz of the surface is at least 150 nm and at most 3000 nm, and the arithmetic mean roughness Ra is at least 30 nm and at most 1000 nm on at least one surface of the film after roughening (roughened film) Roughen the

The roughening method of the film before roughening is not particularly limited, and any method capable of setting the surface roughness on at least one surface of the roughened film obtained after the roughening step to the above predetermined range is selected. sell. Examples of roughening methods include buffing, blasting, hairline treatment, and dry etching (corona discharge, plasma treatment, EUV exposure). Among these methods, buff processing is preferable from the viewpoint of high-speed processing and securing of the cleanliness of the processing unit. In the present invention, when the roughening step is performed by corona discharge treatment, plasma treatment or the like, the roughening treatment is performed at an intensity (for example, 1000 w / m ² ) higher than the intensity in general corona discharge treatment and plasma treatment.

[3. Physical Properties of Optical Film]
[3.1. Film surface Rz and Ra]
In at least one surface of the optical film of the present invention, the maximum height Rz is 150 nm or more and 3000 nm or less, and the arithmetic average roughness Ra is 30 nm or more and 1000 nm or less. The maximum height Rz is preferably 200 nm or more, more preferably 300 nm or more, and preferably 2000 nm or less. Arithmetic mean roughness Ra is preferably 40 nm or more, more preferably 45 nm or more, and preferably 700 nm or less.
For example, even if a cohesive failure part is generated by strongly orienting the alicyclic structure-containing polymer contained in the film by stretching or the like, the surface of the film is adjusted so that Rz and Ra fall within the above range. Since the cohesive failure part can be peeled off by roughening, the peel strength can be increased. In the present invention, the optical film may be roughened so that the surface roughness (Ra, Rz) of one side or both sides is in the above-mentioned range.

The arithmetic average roughness Ra and the maximum height Rz of the surface of the optical film can be measured according to JIS B 0601-2001 using a color 3D laser microscope (VK-9700 manufactured by Keyence Corporation).

[3.2. Internal haze]
The internal haze of the optical film of the present invention is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less. By making internal haze below the said upper limit, transparency becomes high and it becomes a thing suitable for the use of optical films, such as a polarizer protective film.
The internal haze can be measured, for example, using a haze meter ("NDH 5000" manufactured by Nippon Denshoku Industries Co., Ltd.).

[3.3. Phase difference]
The optical film of the present invention has a retardation Re in the in-plane direction of preferably 3 nm or less, more preferably 2.5 nm or less, still more preferably 2 nm or less. In the optical film of the present invention, the absolute value of the retardation Rth in the thickness direction is preferably 3 nm or less, more preferably 2.5 nm or less, and still more preferably 2 nm or less. Among the optical films of the present invention, in those containing a block copolymer hydride as an alicyclic structure-containing polymer, it is preferable to set the absolute values of the retardation Re in the in-plane direction and Rth in the thickness direction to the above ranges. .

The absolute value of the retardation in the in-plane direction of the optical film and the retardation in the thickness direction can be measured at a measurement wavelength of 590 nm using “AxoScan” manufactured by AXOMETRICS as a measurement apparatus. When using the said measuring apparatus, the phase difference of the in-plane direction and thickness direction of an optical film is calculated using the average refractive index of the said optical film. Here, the average refractive index refers to an average value of refractive indexes in two directions which are in-plane directions of the optical film and perpendicular to each other, and in a thickness direction of the optical film.

3.4. Size]
The dimensions of the optical film of the present invention can be appropriately set to the desired dimensions as a product. Due to the efficiency of production, the optical film of the present invention can be produced as a long film. The thickness of the optical film of the present invention is preferably 5 μm or more, more preferably 10 μm or more, and preferably 200 μm or less, more preferably 170 μm or less.

[4. Applications of Optical Film]
The optical film of the present invention has high mechanical strength and good optical properties by including an alicyclic structure-containing polymer. In addition, the optical film of the present invention has high peel strength with the adherend. Therefore, the optical film of the present invention can be suitably used as a protective film for protecting other layers in display devices such as liquid crystal display devices and organic electroluminescent display devices. In particular, the optical film of the present invention can function particularly well as a polarizer protective film for protecting a polarizer in a polarizing plate.

When the optical film of the present invention is used as a polarizer protective film, an adhesive layer may be provided between the polarizer and the polarizer.

The polarizer to which the optical film of the present invention is applied is not particularly limited, and any known one may be used. As an example of a polarizer, after making materials, such as iodine and a dichroic dye, adsorb | suck to a polyvinyl alcohol film, what was extended | stretched is mentioned. As an example of the adhesive which comprises an adhesive bond layer, what made various polymers the base polymer is mentioned. Examples of such base polymers include, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyethers, and synthetic rubbers.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the embodiments shown below, and can be implemented with arbitrary modifications without departing from the scope of the claims of the present invention and the equivalents thereof.
In the following description, "%" and "parts" representing quantities are by weight unless otherwise specified. Moreover, unless otherwise indicated, the operation described below was performed under conditions of normal temperature and normal pressure.

〔Evaluation method〕
[Method of measuring weight average molecular weight and number average molecular weight]
The weight average molecular weight and the number average molecular weight of the polymer were measured as polystyrene equivalent values using a gel permeation chromatography (GPC) system (“HLC-8320” manufactured by Tosoh Corporation). At the time of measurement, an H-type column (manufactured by Tosoh Corporation) was used as a column, and tetrahydrofuran was used as a solvent. Moreover, the temperature at the time of measurement was 40.degree.

[Method of measuring glass transition temperature Tg and melting point Tm]
The sample heated to 300 ° C. in a nitrogen atmosphere was quenched with liquid nitrogen and heated at 10 ° C./min using a differential scanning calorimeter (DSC) to determine the glass transition temperature Tg and the melting point Tm of the sample.
In the case of a block copolymer hydride having two or more Tg's, the sample is press-formed to prepare a test piece 50 mm long, 10 mm wide and 1 mm thick, according to JIS-K7244-4 method. Using a visco-elasticity measuring device (manufactured by TA Instruments Japan Ltd., ARES) to measure the visco-elastic spectrum at a temperature rising rate of 5 ° C./min in the range of −100 ° C. to + 150 ° C., Two or more Tg were calculated | required from this. For example, in the case of two Tg, the glass transition temperature Tg2 derived from the hard segment was determined from the glass transition temperature Tg1 derived from the soft segment from the peak top temperature on the low temperature side of the loss tangent tan δ and the peak top temperature from the high temperature side.

[Method of measuring hydrogenation rate of crystalline polymer and hydrogenation rate of block copolymer hydride]
The hydrogenation rate of the polymer was measured by ¹ H-NMR measurement at 145 ° C. using ortho-dichlorobenzene-d4 as a solvent.

[Method of measuring crystallinity of polymer]
The crystallinity of the polymer contained in the film was confirmed by X-ray diffraction in accordance with JIS K 0131. Specifically, using a wide-angle X-ray diffractometer (RINT 2000, manufactured by Rigaku Corporation), the diffracted X-ray intensity from the crystallized portion is determined, and the ratio to the overall diffracted X-ray intensity is as follows: The degree of crystallinity was determined by (I).
Xc = K · Ic / It (I)
In the above formula (I), Xc represents the crystallinity of the test sample, Ic represents the diffracted X-ray intensity from the crystallized portion, It represents the entire diffracted X-ray intensity, and K represents the correction term.

[Method of measuring peel strength]
As the adherend, a film of a resin containing a norbornene-based polymer (Zeonor film, glass transition temperature 160 ° C., thickness 100 μm, manufactured by Nippon Zeon Co., which is not particularly stretched) is prepared. Corona treatment was applied to one side of the film to be measured (the films of Examples and Comparative Examples) and one side of the adherend. The adhesive was attached to both the corona-treated surface of the film to be measured and the corona-treated surface of the adherend, and the surfaces to which the adhesive was attached were bonded. At this time, a UV adhesive CRB series (manufactured by Toyochem) was used as an adhesive. After that, using an electrodeless UV irradiation apparatus (manufactured by Heraeus), using a D bulb as a lamp, UV irradiation was performed under the conditions of peak illuminance 100 mW / cm ² and integrated light quantity 3000 mJ / cm ² to cure the adhesive . Thereby, a sample film provided with a film to be measured and an adherend was obtained.

The 90 degree peeling test was implemented about the obtained sample film. That is, the sample film was cut to a width of 15 mm, and the film to be measured was attached to the surface of the slide glass with an adhesive. At this time, as a pressure-sensitive adhesive, a double-sided pressure-sensitive adhesive tape (manufactured by Nitto Denko Corporation, product number "CS9621") was used. Place the adherend on the tip of a high performance digital force gauge ZP-5N (made by Imada Co., Ltd.), and pull the adherend at a speed of 300 mm / min in the direction normal to the surface of the slide glass. Was measured as peel strength.

[Reference example: Evaluation of validity of measurement method of peel strength]
An experiment was conducted to evaluate whether it can be said that the measurement of the peel strength by the measurement method described above reflects the evaluation of the peel strength when the adherend is a polarizer.
A polarizing film and an adhesive were prepared by the same method as that described in Example 1 of JP-A-2005-70140. Moreover, the stretched film before treatment and the electron beam-irradiated stretched film obtained in Example 1 of the present application were prepared as films to be measured. One side of the film to be measured was subjected to corona treatment, and this side was bonded to one surface of the polarizing film via an adhesive. On the other surface of the polarizing film, a triacetyl cellulose film was bonded via an adhesive. Thereafter, it was dried at 80 ° C. for 7 minutes to cure the adhesive to obtain a sample film. About the obtained sample film, the 90 degree | times peeling test similar to the thing in [the measuring method of peeling strength] described above was done. As a result, the same values of Fa and Fb as the values obtained in Example 1 of the present application were obtained. From this, it can be said that the measurement of the peel strength by the measurement method described above reflects the evaluation of the peel strength when the adherend is a polarizer.

[Measurement method of internal haze of film]
The internal haze of the film was measured as follows.
First, the film was cut out to a size of 50 mm × 50 mm to obtain a test piece. Subsequently, a cycloolefin film ("Zeonor film" manufactured by Nippon Zeon Co., Ltd., 40 μm thickness) is bonded to both surfaces of the test piece through a transparent optical adhesive film ("8146-2" manufactured by 3M) having a thickness of 50 μm. Then, a sample multilayer body having a layer configuration of cycloolefin film / transparent optical adhesive film / test strip / transparent optical adhesive film / cycloolefin film was obtained. Subsequently, the haze of this sample multilayer body was measured using a haze meter ("NDH 5000" manufactured by Nippon Denshoku Industries Co., Ltd.).

Separately, a reference laminate comprising a cycloolefin film, a transparent optical adhesive film, a transparent optical adhesive film, and a cycloolefin film in this order was formed. And the haze of this laminate for reference was measured by the above-mentioned haze meter. The measured haze of the reference laminate was 0.04%. The haze of 0.04% of the reference laminate is the sum of the haze of two cycloolefin films and the haze of two transparent optical adhesive films.

The internal haze of the test piece was obtained by subtracting the haze value of two cycloolefin films and the sum 0.04% of the haze value of two transparent optical adhesive films from the haze of the sample multilayer body described above.

[Method of measuring absolute value of retardation in in-plane direction and retardation in thickness direction]
By measuring the films of Examples and Comparative Examples at a wavelength of 590 nm using a retardation measurement device (product name “Axoscan” manufactured by Axometric Corporation), the retardation Re in the in-plane direction and the thickness direction of the films of each example The absolute value of the phase difference Rth was determined.

[Measurement of Maximum Height Rz of Optical Film and Arithmetic Average Roughness Ra]
The arithmetic average roughness Ra and the maximum height Rz of the surface of the optical film were measured according to JIS B 0601-2001 using a color 3D laser microscope (VK-9700 manufactured by Keyence Corporation).

Production Example 1 Preparation of Hydrogenated Product of Ring-Opening Polymer of Dicyclopentadiene]
The metal pressure resistant reactor was thoroughly dried and then purged with nitrogen. In this metal pressure resistant reactor, 154.5 parts of cyclohexane, 42.8 parts of a 70% cyclohexane solution having a concentration of dicyclopentadiene (end body content of 99% or more) (30 parts as the amount of dicyclopentadiene), and 1- 1.9 parts of hexene were added and heated to 53 ° C.

To a solution of 0.014 part of tetrachlorotungsten phenylimide (tetrahydrofuran) complex dissolved in 0.70 part of toluene, 0.061 part of a 19% diethylaluminum ethoxide / n-hexane solution is added and stirred for 10 minutes. The catalyst solution was prepared.
The catalyst solution was added to a pressure resistant reactor to initiate a ring opening polymerization reaction. Then, the reaction was carried out for 4 hours while maintaining the temperature at 53 ° C. to obtain a solution of a ring-opened polymer of dicyclopentadiene.
The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the ring-opened polymer of dicyclopentadiene obtained are 8,750 and 28,100, respectively, and the molecular weight distribution (Mw / Mn) determined therefrom Was 3.21.

To 200 parts of the obtained ring-opened polymer solution of dicyclopentadiene, 0.037 parts of 1,2-ethanediol as a terminator is added, and the mixture is heated to 60 ° C. and stirred for 1 hour to stop the polymerization reaction. I did. One part of a hydrotalcite-like compound ("Kyo Ward (registered trademark) 2000" manufactured by Kyowa Chemical Industry Co., Ltd.) was added thereto, and the mixture was heated to 60 ° C and stirred for 1 hour. Thereafter, 0.4 parts of a filter aid ("Radiot (registered trademark) # 1500" manufactured by Showa Kagaku Kogyo Co., Ltd.) is added, and a PP pleated cartridge filter ("TCP-HX" manufactured by ADVANTEC Toyo Corp.) The solution was filtered off.

100 parts of cyclohexane is added to 200 parts of a ring-opened polymer solution of dicyclopentadiene (30 parts of a polymer) after filtration, and 0.0043 parts of chlorohydridocarbonyltris (triphenylphosphine) ruthenium is added to obtain hydrogen. The hydrogenation reaction was performed at a pressure of 6 MPa and 180 ° C. for 4 hours. Thus, a reaction solution containing a hydrogenated product of a ring-opened polymer of dicyclopentadiene was obtained. In this reaction solution, a hydrogenated substance was precipitated to form a slurry solution.

The hydrogenated substance and solution contained in the above reaction solution are separated using a centrifugal separator, dried under reduced pressure at 60 ° C. for 24 hours, and the hydrogenated substance of the ring-opened polymer of dicyclopentadiene having crystallinity. 28.5 parts were obtained. The hydrogenation rate of this hydrogenated substance was 99% or more, the glass transition temperature (Tg) was 95 ° C., and the melting point (Tm) was 262 ° C.

Example 1
(1-1. Preparation of resin)
In 100 parts of the hydrogenated product of the ring-opened polymer of dicyclopentadiene obtained in Preparation Example 1, an antioxidant (tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl)] ) Propionate] Methane; 1.1 parts of “Irganox (registered trademark) 1010” manufactured by BASF Japan Ltd. was mixed to obtain a resin as a film material.

(1-2. Production of film before roughening)
The resin obtained in (1-1) was introduced into a twin-screw extruder equipped with four die holes with an inner diameter of 3 mm. The resin was formed into a strand-like molded product by hot melt extrusion using the above-mentioned twin-screw extruder. The molded body was shredded with a strand cutter to obtain resin pellets. The operating conditions of the above-mentioned twin screw extruder are shown below.
Barrel set temperature: 270 ° C to 280 ° C
・ Die setting temperature: 250 ° C
-Screw rotational speed: 145 rpm
・ Feeder rotation number: 50 rpm

Subsequently, the obtained pellets were fed to a hot melt extruded film forming machine equipped with a T-die. The resin was extruded from a T-die and wound on a roll at a speed of 1 m / min to produce a long original film (50 μm in thickness) made of the resin. The operating conditions of the above-mentioned film forming machine are shown below.
Barrel temperature setting: 280 ° C to 290 ° C
・ Die temperature: 270 ° C
-Screw rotation speed: 30 rpm
Thereafter, the original film is cut into a size of 100 mm × 100 mm, and the ends of the four sides of the film are held by clips using a small biaxial stretching machine (made by Toyo Seiki Seisakusho Co., Ltd.). Fixed end uniaxial stretching was continuously performed at a draw ratio of 1.3 times to obtain a film before roughening. At this time, the crystallinity of the polymer in the pre-roughened film was 4%. When a part of the obtained film before roughening was used as a sample and the surface roughness was measured, it was Ra (nm) = 8 and Rz (nm) = 30. The peel strength Fa was measured to be 0.1 N / m.

(1-3. Production and evaluation of roughened film)
As a surface roughening device, Bafurol equipped with No. 1000 is used to roughen one surface of the film before roughening, and the surface roughness is Ra (nm) = 200, Rz (nm) = 800 A roughened film was obtained. The peel strength Fb of this roughened film was measured to be 1.5 N / m.

Example 2
(2-1. Production of a film before roughening)
The raw film cut into a size of 100 mm × 100 mm obtained in (1-2. Production of a film before roughening) is subjected to four sides of the film using a small biaxial stretching machine (made by Toyo Seiki Seisakusho Co., Ltd.) The end portion of the film was gripped with a clip and heat curing was performed at a temperature of 145 ° C. to obtain a film before roughening. When a part of the obtained film before roughening was used as a sample and the surface roughness was measured, it was Ra (nm) = 3 and Rz (nm) = 12. The peel strength Fa was measured to be 0.1 N / m.

(2-2. Production and evaluation of roughened film)
As a surface roughening device, Bafurol equipped with No. 1000 is used to roughen one surface of the film before roughening, and the surface roughness is Ra (nm) = 220, Rz (nm) = 860 Roughened film was obtained. The peel strength Fb of this roughened film was measured to obtain Fb, which was 1.5 N / m.

[Example 3]
(3-1. Production of a film before roughening)
Pellets of a resin containing a cycloolefin polymer (a resin of a norbornene polymer having a glass transition temperature of 126 ° C., manufactured by Nippon Zeon Co., Ltd.) were dried at 100 ° C. for 5 hours. Thereafter, the dried resin pellets were fed to a single screw extruder. The resin was melted in an extruder, passed through a polymer pipe and a polymer filter, extruded from a T-die onto a casting drum, and cooled. Thus, a raw film having a thickness of 50 μm and a width of 500 mm was obtained. The original film is cut into a size of 100 mm x 100 mm, and the ends of the four sides of the film are held by clips using a small biaxial stretching machine (made by Toyo Seiki Seisakusho Co., Ltd.). Fixed-end uniaxial stretching was performed continuously at 1.3 times to obtain a film before roughening. When a part of the obtained film before roughening was used as a sample, the surface roughness was measured, and it was Ra (nm) = 4 and Rz (nm) = 10. The peel strength Fa was measured to be 0.1 N / m.

(3-2. Production and evaluation of roughened film)
As a surface roughening device, Bafurol equipped with No. 1000 is used to roughen one surface of the film before roughening, and the surface roughness is Ra (nm) = 300, Rz (nm) = 900. Roughened film was obtained. The peel strength Fb of this roughened film was measured to obtain Fb, which was 1.1 N / m.

Example 4
(4-1. Block copolymer [D])
In a sufficiently dried and nitrogen-substituted stainless steel reactor equipped with a stirrer, 256 parts of dehydrated cyclohexane, 25.0 parts of dehydrated styrene, and 0.65 parts of n-dibutyl ether are charged, and stirred at 60 ° C. The polymerization reaction was initiated by adding 1.35 parts of n-butyllithium (15% cyclohexane solution). Furthermore, it was made to react at 60 degreeC for 60 minutes, stirring. The polymerization conversion at this point was 99.5% (measured by gas chromatography, the same applies below). Next, 50.0 parts of dehydrated isoprene was added, and stirring was continued for 30 minutes at the same temperature. The polymerization conversion at this point was 99%. Thereafter, 25.0 parts of dehydrated styrene was further added, and the mixture was stirred at the same temperature for 60 minutes. The polymerization conversion rate at this point was approximately 100%. Next, 0.5 parts of isopropyl alcohol was added to the reaction liquid to stop the reaction, and a polymerization reaction solution containing a block copolymer [C] was obtained. The weight average molecular weight (Mw) of the obtained block copolymer [D] was 44, 900, and the molecular weight distribution (Mw / Mn) was 1.03.

(4-2. Block copolymer hydride [E])
The polymerization reaction solution obtained in (4-1) was transferred to a pressure resistant reactor equipped with a stirrer, and a silica-alumina-supported nickel catalyst (E22U, nickel supported amount: 60% as a hydrogenation catalyst; manufactured by JGC Corporation) 4.0 parts and 350 parts of dehydrated cyclohexane were added and mixed. The inside of the reactor was replaced with hydrogen gas, and while stirring the solution, hydrogen was supplied, and a hydrogenation reaction was performed at a temperature of 170 ° C. and a pressure of 4.5 MPa for 6 hours.

After completion of the hydrogenation reaction, the reaction solution was filtered to remove the hydrogenation catalyst. In the filtrate, pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (phenol-based antioxidant) (manufactured by Koyo Chemical Laboratory, product name “Songnox 1010”) ) 1.0 part of a xylene solution in which 0.1 part was dissolved was added and dissolved. Next, the above solution is evaporated from the solution cyclohexane, xylene and other volatilization from the solution at a temperature of 260 ° C. and a pressure of 0.001 MPa or less using a cylindrical concentrator dryer (product name “Contro” manufactured by Hitachi, Ltd.). The ingredients were removed. The molten polymer is continuously filtered at a temperature of 260 ° C. by a polymer filter (manufactured by Fuji Filter Co., Ltd.) equipped with a stainless steel sintered filter with a pore diameter of 20 μm connected to a concentration dryer, and then the molten polymer is formed into strands After extrusion and cooling, a block copolymer hydride [E] was obtained by a pelletizer.

The obtained block copolymer hydride is a block containing a repeating unit derived from styrene (hereinafter referred to as “St” as appropriate) and a block containing a repeating unit derived from isoprene (hereinafter referred to as “Ip” as appropriate). And the weight ratio of each block was St: Ip: St = 25: 50: 25. Mw of the block copolymer hydride [E] is 45, 100, Mw / Mn is 1.04, the hydrogenation rate of the main chain and the aromatic ring is almost 100%, the glass transition temperature Tg1 is -50 ° C, Tg2 is It was 140 ° C.

(4-3. Preparation of resin)
100 parts of the block copolymer hydride [E] obtained in (4-2) and 5 parts of a cross-linking aid (Taike (manufactured by Nippon Kasei Co., Ltd.)) are mixed to form a resin as a film material Obtained.

(4-4. Production of film before roughening)
A film before roughening was obtained in the same manner as (1-2) in Example 1 except that the resin obtained in (4-3) was used instead of the resin obtained in (1-1). When a part of the obtained film before roughening was used as a sample and the surface roughness was measured, it was Ra (nm) = 7 and Rz (nm) = 20. The peel strength Fa was measured to be 0.1 N / m.

(4-5. Production of roughened film)
In the same manner as (1-3) in Example 1, a roughened film of Example 3 in which the surface roughness was Ra (nm) = 500 and Rz (nm) = 1600 was obtained. The peel strength Fb of this roughened film was measured to be 2.1 N / m.

[Comparative Examples 1 to 3]
The pre-roughened film obtained in (1-2) of Example 1 is used as the film of Comparative Example 1, and the pre-roughened film obtained in (3-1) of Example 3 is used as the film of Comparative Example 2. The pre-roughened film obtained in (4-4) of Example 4 was used as the film of Comparative Example 3, and evaluation was performed in the same manner as in each example.

The evaluation results (surface roughness (Ra, Rz), peel strength, internal haze, retardation (Re, Rth)) of Examples and Comparative Examples are collectively shown in Table 1.

From the results shown in Table 1, at least one surface of the film containing the alicyclic structure-containing polymer has a maximum height Rz of 150 nm to 3000 nm and an arithmetic average roughness Ra of 30 nm to 1000 nm. It was found that the roughening treatment gave an optical film having high peel strength and useful as a polarizer protective film.

Claims

An optical film obtained by roughening at least one surface of a film containing an alicyclic structure-containing polymer,
An optical film having a maximum height Rz of 150 nm or more and 3000 nm or less and an arithmetic average roughness Ra of 30 nm or more and 1000 nm or less in at least one surface.
The optical film according to claim 1, wherein the internal haze is 5% or less.
The alicyclic structure-containing polymer is a block copolymer hydride [E],
The block copolymer hydride [E] is a hydride of the block copolymer [D],
The block copolymer [D] is composed of the polymer block [A] and the polymer block [B], or is composed of the polymer block [A] and the polymer block [C].
The polymer block [A] is a polymer block mainly composed of a repeating unit [I] derived from an aromatic vinyl compound,
The polymer block [B] is a polymer block mainly comprising a repeating unit [I] derived from an aromatic vinyl compound and a repeating unit [II] derived from a chain conjugated diene compound,
The optical film according to claim 1, wherein the polymer block [C] is a polymer block having as a main component a repeating unit [II] derived from a chain conjugated diene compound.
The optical film according to claim 3, wherein the retardation Re in the in-plane direction is 3 nm or less, and the absolute value of the retardation Rth in the thickness direction is 3 nm or less.
The optical film according to claim 1, wherein the alicyclic structure-containing polymer is crystalline, and the degree of crystallinity is 1% or more.
The optical film according to any one of claims 1 to 5, which is a polarizer protective film.
A method of producing an optical film according to any one of claims 1 to 6, wherein
A step of stretching a film containing an alicyclic structure-containing polymer, and a treatment step including at least one of the steps of heat curing the film;
And d) roughening at least one surface of the film after the processing step.