JP7040175B2 - Transparent optical film and its manufacturing method - Google Patents

Description

The present invention relates to a transparent optical film and a method for producing the same.

With the development of display devices, the demand for flat panel display devices such as liquid crystal displays and organic EL display devices is increasing, and the market for flat panel display devices is expanding year by year.

In recent years, in addition to TVs and PCs, multifunctional terminals such as smartphones and tablet terminals have become widespread. The multi-function terminal is equipped with a touch panel member to improve convenience. Further, in recent years, studies have been made on flexible display devices. Since the flexible display device can be freely deformed, for example, a rollable (rewindable) mobile display device is expected to be realized. Further, the flexible display device can be manufactured by a continuous process using, for example, a long film, and has an advantage of excellent productivity.

With the expansion of multifunction terminals and flexible display devices, it is required to realize the optimum characteristics of various members according to these new applications, including thinning of various members including optical films. Examples of the characteristics of the optical film include various characteristics such as optical characteristics, mechanical strength, various durability, and transportability. Optical films are designed to meet these properties to the extent acceptable for the application.

In order to prevent the optical films from sticking to each other and to form a film roll and smoothly feed the film to the next process, a technology to provide an anti-blocking layer on the film surface and a technology to contain particles in the film itself are being studied. Has been done. Patent Document 1 describes an uneven surface containing a transparent conductive layer, a transparent organic polymer substrate, and metal oxides and / or metal fluoride ultrafine particles having an average primary particle diameter of less than 200 nm, mainly intended for touch panel applications. A cured resin layer having the same, and a transparent conductive laminate having the same material are disclosed.

For the purpose of imparting a function to an optical film, a technique for imparting light scattering properties by forming a non-uniform structure in the optical film has been studied. Patent Document 2 has image sharpness below a certain level, mainly assuming the use of a polarizing plate protective film on the backlight side when the light diffusion sheet of a thin display device is omitted, and has continuous phases and islands corresponding to the sea. A light-scattering polarizing plate protective film having a predetermined relationship with a corresponding independent phase (also referred to as a dispersed phase) is disclosed.

In order to realize an optical film having desired optical properties, techniques related to materials other than triacetyl cellulose, which are mainly used as polarizing plate protective films and retardation films, are being studied. Patent Document 3 discloses a fumaric acid diester-alkoxycinnamic acid ester copolymer having a specific structure, mainly assuming the use of a retardation film having a high out-of-plane retardation.

Japanese Unexamined Patent Publication No. 2010-157439 Japanese Unexamined Patent Publication No. 2013-97220 Japanese Unexamined Patent Publication No. 2016-98371

In display device applications, the optical film is required to be transparent in various applications. Further, the optical film used for a multifunctional terminal having a touch panel member is required to have high flexibility because the film is deformed when a key is pressed, that is, when the film is touched by a finger or a jig. Since the optical film used in the flexible display device needs to be deformed following the display unit, high flexibility is required, and high transportability is required during manufacturing in a continuous process.

However, an optical film having a curable resin layer containing inorganic particles as in Patent Document 1 has a problem that flexibility is insufficient, although it is possible to impart a certain degree of transportability. Further, the optical film having a sea-island structure of Patent Document 2 has a high light scattering property, and is not intended as a transparent optical film having a high transparency. Further, Patent Document 3 discloses an optical film composed only of a fumaric acid diester-alkoxycinnamic acid ester copolymer having a specific structure, but the optical film has a matting agent or a structure in place of the matting agent. No, and transportability is not considered.

Therefore, an object of the present invention is to provide a means for imparting excellent transportability and flexibility in a transparent optical film.

The above-mentioned problems of the present invention are solved by the following means.

Cycloolefin resin A and
The following formula (1):

In the formula (1), X ¹ independently represents a linear alkyl group, a branched chain alkyl group, or a cyclic alkyl group, and X ² independently represents a linear alkyl group and a branched chain alkyl group, respectively. , Cyclic alkyl group, alkoxy group, aryloxy group, ester group, hydroxyl group, carboxyl group, halogen atom, or cyano group, a represents an integer of 0 to 5, and * represents an adjacent structural unit or terminal group. Represents a joint;
The structural unit represented by and the following formula (2):

In formula (2), X ³ and X ⁴ independently represent a linear alkyl group, a branched chain alkyl group, or a cyclic alkyl group, and * represents a bonding portion with an adjacent structural unit or terminal group. ;
Containing, including, and including the copolymer B, which comprises the structural unit represented by.
It has a sea-island structure consisting of a continuous phase corresponding to the sea and an independent phase corresponding to an island.
The main component of the independent phase is the copolymer B.
Transparent optical film.

According to the present invention, it is possible to provide a means for imparting excellent transportability and flexibility in a transparent optical film.

<Transparent optical film>
Hereinafter, preferred embodiments of the present invention will be described. In the present specification, "XY" indicating a range means "X or more and Y or less". Unless otherwise specified, the operation and physical properties are measured under the conditions of room temperature (20 to 25 ° C.) / relative humidity of 40 to 50% RH.

Further, "(meth) acrylate" is a general term for acrylate and methacrylate. Similarly, compounds containing (meta) such as (meth) acrylic acid are a general term for compounds having "meta" in the name and compounds having no "meta".

One embodiment of the present invention is a copolymer B (hereinafter, simply referred to as a copolymer B) containing a cycloolefin resin A, a structural unit represented by the above formula (1), and a structural unit represented by the above formula (2). (Also referred to as copolymer B), and has a sea-island structure consisting of a continuous phase corresponding to the sea and an independent phase corresponding to an island, and the main component of the independent phase is copolymer B, which is transparent. It is an optical film. According to one embodiment of the present invention, it is possible to provide a means for imparting excellent transportability and flexibility in a transparent optical film.

The present inventors presume the mechanism by which the problem is solved by the above configuration as follows.

Although the continuous phase containing the cycloolefin resin A as the main component and the independent phase containing the copolymer B as the main component form a sea-island structure by phase separation, the refractive indexes are close to each other. Further, in the continuous phase and the independent phase, although they are not compatible with each other, good intramolecular interaction occurs between them due to an intramolecular force or the like, and peeling at an interface that causes light scattering. And cracks due to the peeling do not occur. As a result, the transparent optical film according to one embodiment of the present invention has a sea-island structure and high transparency.

Further, in the transparent optical film according to one embodiment of the present invention, a continuous phase and an independent phase are formed when the solvent is volatilized from the coating film at the time of production. Then, when the thickness of the coating film or the web is reduced by volatilizing the solvent or stretching at a high temperature, the deformation rate of the independent phase is slower than the deformation rate of the continuous phase. The surface of the film is pushed up to form surface irregularities. As a result, the transparent optical film according to one embodiment of the present invention has a reduced dynamic frictional force, prevents the films from sticking to each other or from the film to other devices or members, and has high transportability.

In the conventional optical film, the film itself contains a matting agent and has an anti-blocking layer to form surface irregularities to improve the transportability. In these means, the resin used as a matrix is contained. It is necessary to add a certain amount of particles such as inorganic particles or organic particles. However, in the method of adding the inorganic particles to the resin as the matrix, the intramolecular interaction between the resin and the inorganic particles is weak, peeling occurs at the interface, and cracks occur due to the peeling. Even when organic particles are used, the organic particles always exist as particles separate from the matrix from the solution used for coating film formation to the film formation, so that the adhesion to the matrix is not always sufficient and peeling at the interface. , And cracks occur due to the peeling. As a result, in the conventional optical film, the transportability and the flexibility are in a trade-off relationship, and the transportability which is indispensable at the time of manufacturing or processing is prioritized, resulting in a particularly insufficient flexibility.

However, the transparent optical film according to one embodiment of the present invention has a good intramolecular interaction between a continuous phase and an independent phase due to an intramolecular force or the like, and is peeled off at an interface or a crack caused by the peeling. Does not occur. Further, since the independent phase itself contains the copolymer B, which is a polymer compound, as a main component, the independent phase imparts high flexibility to the transparent optical film. As a result, the transparent optical film according to one embodiment of the present invention has high transportability even without the addition of particles into the resin, so that both extremely excellent transportability and flexibility can be realized. Further, even when particles are added as in the case of the conventional optical film, the effect of improving the flexibility of the independent phase realizes both excellent transportability and flexibility.

The above mechanism is based on speculation, and its correctness does not affect the technical scope of the present invention.

The total content of the cycloolefin resin A and the copolymer B contained in the transparent optical film is not particularly limited, but from the viewpoint of improving the transparency, flexibility and transportability of the transparent optical film, the total content of the transparent optical film is limited. It is preferably 51 to 100% by mass, more preferably 70% to 100% by mass, further preferably 80% to 100% by mass, and 90 to 100% by mass with respect to 100% by mass by mass. Is particularly preferable, and 95 to 100% by mass is most preferable.

[Cycloolefin resin A]
The transparent optical film according to one embodiment of the present invention contains a cycloolefin resin A. The cycloolefin-based resin A mainly forms a continuous phase of a sea-island structure.

The cycloolefin-based resin A is not particularly limited, and a known cycloolefin-based resin (cycloolefin-based polymer) can be used. Among these, the following formula (3):

In the formula (1), A ¹ to A ⁴ are independently described in the following (i) to (iv) :.
(I) Hydrogen atom (ii) Halogen atom,
(Iii) Hydrocarbon group, or (iv) Hydrogen bond accepting group,
Or the following (v) or (vi):
(V) A ¹ and A ² or A ³ and A ⁴ bind to each other to form an alkylidene group, and A ¹ to A ⁴ not involved in the binding are independent of the above (i) to (i) to (). Represents a group selected from iv),
(Vi) A ¹ and A ³ , A ¹ and A ⁴ , A ² and A ³ , or A ² and A ⁴ are bonded to each other to form a cyclic structure together with the carbon atoms to which they are bonded, and the bond is formed. A ¹ to A ⁴ not involved each independently represent a group selected from the above (i) to (iv);
, B represents 0 or 1, and c represents an integer greater than or equal to 0;
It is preferable that the cycloolefin resin has a structural unit derived from the monomer represented by.

In the formula (1), examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

In the formula (1), the hydrocarbon group is not particularly limited, and examples thereof include a hydrocarbon group having 1 to 30 carbon atoms, for example, an alkyl group such as a methyl group, an ethyl group, and a propyl group; a cyclopentyl group, Cycloalkyl groups such as cyclohexyl groups; alkenyl groups such as vinyl groups, allyl groups and propenyl groups; aromatic groups such as phenyl groups, biphenyl groups, naphthyl groups and anthracenyl groups can be mentioned. These hydrocarbon groups may be substituted, and the substituent is not particularly limited, and examples thereof include a fluorine atom, a halogen atom such as a chlorine atom and a bromine atom, and a phenylsulfonyl group.

In the present specification, the "hydrogen bond accepting group" means a group containing a negative atom such as a fluorine atom, an oxygen atom, and a nitrogen atom and capable of forming a hydrogen bond with a hydrogen atom.

The hydrogen bond-accepting group is not particularly limited, and is, for example, an alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 2 to 10 carbon atoms, an aryloxycarbonyl group, and a cyano group. , Amid group, imide ring-containing group, triorganosyloxy group, triorganosilyl group, acyl group, alkoxysilyl group having 1 to 10 carbon atoms, sulfonyl-containing group, carboxy group and the like. More specifically, these hydrogen-bonding accepting groups include, for example, a methoxy group, an ethoxy group and the like as an alkoxy group; and an alkylcarbonyloxy such as an acetoxy group and a propionyloxy group as an acyloxy group. Examples include an arylcarbonyloxy group such as a group and a benzoyloxy group; examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group; examples of the aryloxycarbonyl group include a phenoxycarbonyl group and naphthyl. Examples thereof include an oxycarbonyl group, a fluorenyloxycarbonyl group, a biphenylyloxycarbonyl group and the like; examples of the triorganosyloxy group include a trimethylsiloxy group and a triethylsiloxy group; examples of the triorganosilyl group include a trimethylsilyl group. , Triethylsilyl group and the like; examples of the alkoxysilyl group include a trimethoxysilyl group and a triethoxysilyl group.

In formula (1), one or two of A ¹ to A ⁴ is preferably a hydrogen bond accepting group. By having such a structure, it can be easily dissolved in a solvent, and film formation by solution casting becomes easy. The proportion of hydrogen bond-accepting groups present in A1 to ^A4 in the formula ( ¹ ) can be identified by using, for example, ^13C nuclear magnetic resonance spectroscopy ( ^13C -NMR).

From the viewpoint of improving solubility and facilitating film formation by casting the solution, A ¹ and A ³ in the formula (1) are preferably hydrogen atoms or hydrocarbon groups having 1 to 10 carbon atoms. , A hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms is more preferable, and a hydrogen atom or a hydrocarbon group having 1 to 2 carbon atoms is further preferable, and A ² and A ⁴ are hydrogen atoms. Alternatively, it is preferably a hydrogen-bond-accepting group, and more preferably at least one is a hydrogen-binding-accepting group. Further, from the viewpoint of forming the sea-island structure, b = 0 or 1 and c = 0 or 1 are preferable, and b = 0 and c = 1 are more preferable.

Furthermore, from the viewpoint of easy film formation by the solution casting method and easy thinning, and from the viewpoint of forming a sea-island structure, A ¹ and A ² are hydrogen atoms in the formula (1). , A ³ is a methyl group, A ⁴ is a methoxycarbonyl group, and b = 0 and c = 1.

The terminal of the cycloolefin resin A is not particularly limited, but is preferably, for example, a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms independently of each other, and has a hydrogen atom or 1 to 4 carbon atoms. It is more preferably a hydrocarbon group, further preferably a hydrogen atom or a hydrocarbon group having 1 to 2 carbon atoms, and particularly preferably a hydrogen atom.

The number average molecular weight (Mn) of the cycloolefin resin A is preferably 8000 to 100,000, more preferably 10,000 to 80,000, and even more preferably 12,000 to 50,000. The weight average molecular weight (Mw) is preferably 20,000 to 300,000, more preferably 30,000 to 250,000, and even more preferably 40,000 to 200,000. When the number average molecular weight (Mn) or the weight average molecular weight (Mw) is within the above range, the transparency, flexibility and transportability of the transparent optical film are further improved.

The intrinsic viscosity [η] inh (measurement temperature 30 ° C.) of the cycloolefin resin A is preferably 0.2 to 5 cm ³ / g, more preferably 0.3 to 3 cm ³ / g, and 0. It is more preferably .4 to 1.5 cm ³ / g. When the intrinsic viscosity [η] inh is within the above range, the transparency, flexibility and transportability of the transparent optical film are further improved. The intrinsic viscosity [η] inh is obtained by measuring a resin solution in which the cycloolefin resin A to be measured is dissolved in chloroform using an Ubbelohde viscometer (measurement temperature 30 ° C.).

The glass transition temperature (Tg) of the cycloolefin resin A is usually 110 ° C. or higher, preferably 110 to 350 ° C., more preferably 120 to 250 ° C., and preferably 120 to 220 ° C. Especially preferable. When the glass transition temperature (Tg) is 110 ° C. or higher, deformation due to use under high temperature conditions and secondary processing such as coating and printing is suppressed, which is preferable. Further, when the glass transition temperature (Tg) is 350 ° C. or lower, deterioration of the resin due to heat during molding is suppressed, which is preferable.

As the cycloolefin resin A, one synthesized by a known method may be used, or a commercially available product may be used. Examples of commercially available products include Arton G, Arton F, Arton R, and Arton RX (ARTON is a registered trademark) manufactured by JSR Corporation.

Cycloolefin from the viewpoint of generating good intermolecular interaction with the copolymer B, forming a good sea-island structure, and further improving the transparency, flexibility and transportability of the transparent optical film. The based resin A preferably has an octanol-water partition coefficient (hereinafter referred to as logP) in a predetermined range. The octanol-water partition coefficient (hereinafter referred to as logP) of the cycloolefin resin A is not particularly limited, but is preferably 5.4 to 5.9. The measurement of logP can be carried out by the flask dipping method described in JIS Z7260-107: 2000. The logP can also be estimated by a computational chemistry method or an empirical method instead of the actual measurement. As a calculation method, the Crippen's fragmentation method ("J. Chem. Inf. Comput. Sci.", Vol. 27, p21 (1987)), the Viswanadhan's fragmentation method ("J. Chem. Inf. Comput. Sci."). ", Vol. 29, p163 (1989)), Broto's fragmentation method ("Eur. J. Med. Chem.-Chim. Theor. ", Vol. 19, p71 (1984)), CLOGP method (references). Leo, A., Jow, PYC, Silipo, C., Hansch, C., J. Med. Chem., 18, 865 1975) and the like are preferably used, but the Crippen's fragmentation method (Crippen's fragmentation method). "J. Chem. Inf. Comput. Sci.", Vol. 27, p21 (1987)) is more preferable.

The content of the cycloolefin resin A is 51 mass with respect to 100% by mass of the total mass of the cycloolefin resin A and the copolymer B from the viewpoint of improving the transparency, flexibility and transportability of the transparent optical film. % Or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, further preferably 85% by mass or more and 97% by mass or more, and more than 90% by mass and 95% by mass or less. Is particularly preferable.

[Copolymer B]
The transparent optical film according to one embodiment of the present invention has a structural unit represented by the following formula (1) (hereinafter, also referred to as “constituent unit (1)”) and the following formula (2) (hereinafter, “constituent unit (hereinafter,“ structural unit (1) ”). 2) ”), and the copolymer B containing the structural unit and the like. The copolymer B mainly forms an independent phase having a sea-island structure, and the main component of the independent phase is the copolymer B. The independent phase is presumed to impart high flexibility to the transparent optical film.

First, the structure of the structural unit (1) is shown below.

In the formula (1), X ¹ independently represents a linear alkyl group, a branched chain alkyl group, or a cyclic alkyl group, and X ² independently represents a linear alkyl group and a branched chain alkyl group, respectively. , Cyclic alkyl group, alkoxy group, aryloxy group, ester group, hydroxyl group, carboxyl group, halogen atom, or cyano group, a represents an integer of 0 to 5, and * represents an adjacent structural unit or terminal group. Represents a joint.

The linear alkyl group, the branched chain alkyl group, or the cyclic alkyl group represented as X ¹ is not particularly limited, and is, for example, a linear alkyl group having 1 to 12 carbon atoms or a branched chain alkyl group having 3 to 12 carbon atoms. , Cyclic alkyl groups having 3 to 12 carbon atoms and the like. Specific examples of the linear alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group and the like; Examples of the 3 to 12 branched chain alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group and the like; examples of the cyclic alkyl group having 3 to 12 carbon atoms include a cyclopropyl group and a cyclobutyl group. Cyclopentyl group, cyclohexyl group and the like can be mentioned. Among them, from the viewpoint of polymerizable property and formation of sea-island structure, X1 is preferably ^a methyl group, an ethyl group, an n-propyl group, an isopropyl group or a cyclohexyl group, more preferably a methyl group, an ethyl group or a cyclohexyl group, and a methyl group. , Cyclohexyl group is more preferred, and methyl group is particularly preferred.

The linear alkyl group, branched chain alkyl group, or cyclic alkyl group represented as X ² is not particularly limited, and is, for example, a linear alkyl group having 1 to 12 carbon atoms or a branched chain alkyl group having 3 to 12 carbon atoms. , Cyclic alkyl groups having 3 to 12 carbon atoms and the like. Specific examples of the linear alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group and the like; Examples of the 3 to 12 branched chain alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group and the like; examples of the cyclic alkyl group having 3 to 12 carbon atoms include a cyclopropyl group and a cyclobutyl group. Cyclopentyl group, cyclohexyl group and the like can be mentioned.

The alkoxy group represented as X ² is not particularly limited, and examples thereof include an alkoxy group having 1 to 10 carbon atoms. Specific examples thereof include a methoxy group, an ethoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group and the like. Among these, from the viewpoint of forming a sea-island structure, an n-butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group are preferable, and a tert-butoxy group is more preferable.

The aryloxy group represented as X ² is not particularly limited, and examples thereof include a phenoxy group, a naphthyloxy group, a fluorenyloxy group, and a biphenylyloxy group.

Examples of the ester group represented by X ² include a group represented by the formula: —OC (= O) —R or C (= O) —OR. At this time, R is an alkyl group or an aromatic group. The alkyl group referred to here is not particularly limited, and examples thereof include a linear alkyl group having 1 to 12 carbon atoms, a branched chain alkyl group having 3 to 12 carbon atoms, and a cyclic alkyl group having 3 to 12 carbon atoms. .. Specific examples of the linear alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group and the like; Examples of the 3 to 12 branched chain alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group and the like; examples of the cyclic alkyl group having 3 to 12 carbon atoms include a cyclopropyl group and a cyclobutyl group. Cyclopentyl group, cyclohexyl group and the like can be mentioned. Examples of the aromatic group here include an aryl group having 6 to 24 carbon atoms. Specific examples thereof include a phenyl group, a p-tolyl group, a naphthyl group, a biphenyl group, a fluorenyl group, an anthryl group, a pyrenyl group, an azulenyl group, an acenaphthylenyl group, a terphenyl group and a phenanthryl group.

Examples of the halogen atom represented as X ² include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Among these, X ² is preferably an alkoxy group from the viewpoint of forming a sea-island structure.

a represents an integer from 0 to 5. Among them, from the viewpoint of polymerizable property and formation of sea-island structure, a is preferably 0 to 3, more preferably 0 to 2, further preferably 0 or 1, and particularly preferably 1. preferable. When a is 2 or more, the groups shown as X ² may be the same or different from each other.

The structural unit (1) contained in the copolymer may be contained alone or in combination of two or more.

Next, the structure of the structural unit (2) is shown below.

In formula (2), X ³ and X ⁴ independently represent a linear alkyl group, a branched chain alkyl group, or a cyclic alkyl group, and * represents a bonding portion with an adjacent structural unit or terminal group. ..

The linear alkyl group, branched chain alkyl group, or cyclic alkyl group represented by X ³ and X ⁴ is not particularly limited, and is, for example, a linear alkyl group having 1 to 12 carbon atoms and a branched chain having 3 to 12 carbon atoms. Examples thereof include a chain alkyl group and a cyclic alkyl group having 3 to 12 carbon atoms. Here, specifically, as the linear alkyl group having 1 to 12 carbon atoms, specifically, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and an n-hexyl group. Examples include groups; branched chain alkyl groups having 3 to 12 carbon atoms include isopropyl groups, isobutyl groups, sec-butyl groups, tert-butyl groups and the like; cyclic alkyl groups having 3 to 12 carbon atoms include cyclic alkyl groups. , Cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group and the like. Of these, a branched chain alkyl group and a cyclic alkyl group are preferable from the viewpoint of solubility in a solvent and formation of a sea-island structure, and an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclopropyl group and a cyclobutyl group are preferable. A group and a cyclohexyl group are more preferable, an isopropyl group, a tert-butyl group and a cyclohexyl group are further preferable, and an isopropyl group and a cyclohexyl group are particularly preferable. Further, X ³ and X ⁴ may be the same or different, but are preferably the same.

The constituent unit (2) contained in the copolymer B may be contained alone or in combination of two or more, but may be contained in combination of two or more. Is preferable.

Here, when the copolymer B contains a structural unit (2) in which X ³ and X ⁴ are branched-chain alkyl groups, and a structural unit (2) in which X ³ and X ⁴ are cyclic alkyl groups, the copolymer B contains. The content ratio is not particularly limited. For example, with respect to the total mass of 100% by mass of the structural unit (2) portion in which X ³ and X ⁴ are branched chain alkyl groups and the structural unit (2) portion in which X ³ and X ⁴ are cyclic alkyl groups. The mass of the structural unit (2) portion in which X ³ and X ⁴ are branched chain alkyl groups is 1 to 50% by mass, and the mass of the structural unit (2) portion in which X ³ and X ⁴ are cyclic alkyl groups. Is preferably 50 to 99% by mass. Further, the mass of the structural unit (2) portion in which X ³ and X ⁴ are branched chain alkyl groups is 5 to 30% by mass, and the mass of the structural unit (2) portion in which X ³ and X ⁴ are cyclic alkyl groups. Is more preferably 70 to 95% by mass, the mass of the structural unit (2) portion in which X ³ and X ⁴ are branched chain alkyl groups is 10 to 25% by mass, and X ³ and X ⁴ are cyclic alkyl. It is more preferable that the mass of the constituent unit (2) portion as a base is 75 to 90% by mass.

Here, from the viewpoint of forming a sea-island structure, a structural unit derived from diisopropyl fumarate and a structural unit derived from dicyclohexyl fumarate are particularly preferable. And it is most preferable that these are contained in the copolymer B in combination.

The terminal of the copolymer B is not particularly limited, but is preferably a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms independently, and is a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. It is more preferable that it is a hydrogen atom or a hydrocarbon group having 1 to 2 carbon atoms, and it is particularly preferable that it is a hydrogen atom.

The content ratio of the structural unit (1) and the structural unit (2) in the copolymer B is not particularly limited, but from the viewpoint of forming a sea-island structure and improving the transparency, flexibility and transportability of the transparent optical film. , The mass of the structural unit (1) is 2 to 90% by mass, and the mass of the structural unit (2) is 10 to 10 to 100% by mass of the total mass of the structural unit (1) and the structural unit (2). It is preferably 98% by mass. Further, it is more preferable that the mass of the structural unit (1) portion is 5 to 70% by mass, the mass of the structural unit (2) portion is 30 to 95% by mass, and the mass of the structural unit (1) portion is 10. It is more preferably to 70% by mass, and the mass of the constituent unit (2) portion is more preferably 30 to 90% by mass, and the mass of the constituent unit (1) portion is 20 to 50% by mass, and the constituent unit (2). It is particularly preferable that the mass of the portion is 50 to 80% by mass. That is, the monomer represented by the following formula (1a) (hereinafter, also referred to as “monomer (1a)”) and the monomer represented by the following formula (2a), which are the raw materials of the copolymer B (hereinafter, “monomer (2a)”). The ratio of the monomer (1a) and the monomer (2a) to the total mass of 100% by mass of the monomer (1a) is 2 to 90% by mass of the monomer (1a) and 10 to 98% by mass of the monomer (2a). %, The monomer (1a) is 5 to 70% by mass, the monomer (2a) is more preferably 30 to 95% by mass, and the monomer (1a) is 10 to 70% by mass. It is more preferable that the monomer (2a) is 30 to 90% by mass, the monomer (1a) is 20 to 50% by mass, and the monomer (2a) is 50 to 80% by mass.

In the formula (1a), the definitions of X ¹ , X ² , and a are the same as those in the formula (1), respectively.

Examples of the monomer (1a) include methyl cinnamic acid, ethyl cinnamic acid, tert-butyl cinnamic acid, cyclohexyl cinnamic acid, methyl 4-methyl cinnamic acid, ethyl 4-methyl cinnamic acid, and 3,4-dimethyl. Examples include, but are limited to, methyl cinnamic acid, ethyl 3,5-dimethylcinnamic acid, 4-tert-butyl cinnamic acid methyl, 4-tert-butoxy cinnamic acid methyl, 4-tert-butoxy cinnamic acid cyclohexyl and the like. Not done.

In the formula (2a), the definitions of X ³ and X ⁴ are the same as those in the formula (2), respectively.

Examples of the monomer (2a) include, but are not limited to, diisopropyl fumarate, di-sec-butyl fumarate, di-tert-butyl fumarate, dicyclopropyl fumarate, dicyclohexyl fumarate and the like.

Further, as described above, a raw material for a copolymer containing a structural unit (2) in which X ³ and X ⁴ are branched-chain alkyl groups and a structural unit (2) in which X ³ and X ⁴ are cyclic alkyl groups. The preferred proportions of the monomer (2a) in which X ³ and X ⁴ are branched-chain alkyl groups and the monomer (2a) in which X ³ and X ⁴ are cyclic alkyl groups are as follows. That is, X ³ and X ⁴ are added to 100% by mass of the total mass of the monomer (2a) in which X ³ and X ⁴ are branched-chain alkyl groups and the monomer (2a) in which X ³ and X ⁴ are cyclic alkyl groups. It is preferable that the monomer (2a) which is a branched chain alkyl group is 1 to 50% by mass, and the monomer (2a) where X ³ and X ⁴ are cyclic alkyl groups is 50 to 99% by mass. Further, the monomer (2a) in which X ³ and X ⁴ are branched-chain alkyl groups is 5 to 30% by mass, and the monomer (2a) in which X ³ and X ⁴ are cyclic alkyl groups is 70 to 95% by mass. Is more preferable. The monomer (2a) in which X ³ and X ⁴ are branched-chain alkyl groups is 10 to 25% by mass, and the monomer (2a) in which X ³ and X ⁴ are cyclic alkyl groups is 75 to 90% by mass. Is even more preferable.

The copolymer B is a structural unit derived from a monomer having at least one radically polymerizable group (hereinafter, also referred to as “another monomer”) in addition to the structural unit (1) and the structural unit (2) (hereinafter, “others”). Also referred to as "constituent unit of"). By including such other structural units, the solubility in a solvent can be improved.

The monomer having at least one radically polymerizable group (other monomer) is not particularly limited, and is, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenyl. Styrene, p-ethyl styrene, pn-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, p. Styrene-based monomers such as -n-dodecylstyrene, 2,4-dimethylstyrene, divinylbenzene; methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n- Octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate phenyl, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-octyl methacrylate, 2-Ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, isobornyl methacrylate, isobornyl acrylate, dicyclopentanyl methacrylate, dicyclopentanyl acrylate, 1,6-hexane (Meta) acrylic acid ester-based monomers such as diol diacrylate, tricyclodecanedimethanol methacrylate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, ditrimethylolpropanetetraacrylate; olefins such as ethylene, propylene, isobutylene and vinylcyclohexane. Vinyl esters such as vinyl propionate, vinyl acetate, vinyl benzoate, divinyl maleate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl cyclohexyl ether, propanediol divinyl ether; vinyl methyl ketone, vinyl ethyl ketone, Vinyl ketones such as vinyl hexyl ketone; N-vinyl compounds such as N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone. , Butadiene, vinylnaphthalene, vinyl pyridine and other vinyl compounds; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylate, acrylamide and methacrylicamide, and other maleic anhydrides, N-phenylmaleimide, N-cyclohexylmaleimide and the like. Among the monomers and the like, the monomer having at least one radically polymerizable group is preferably a (meth) acrylic acid ester-based monomer, olefins, vinyl ethers, and is a (meth) acrylic acid ester-based monomer. Is more preferable.

As the other structural units contained in the copolymer B, only one type may be contained alone, or two or more types may be contained in combination.

When the copolymer B further has other structural units, the content ratio of the other structural units is 100 parts by mass in total mass of the structural unit (1) portion and the structural unit (2) portion from the viewpoint of improving the solubility. On the other hand, it is preferably 1 to 50 parts by mass, more preferably 3 to 40 parts by mass, further preferably 5 to 30 parts by mass, and particularly preferably 10 to 20 parts by mass. ..

The weight average molecular weight (Mw) of the copolymer B is preferably 5000 to 300,000, more preferably 8,000 to 100,000 from the viewpoint of improving the transparency, flexibility and transportability of the transparent optical film. It is more preferably 10,000 to 80,000. In this specification, the polystyrene-equivalent value measured by gel permeation chromatography (GPC) is adopted as the weight average molecular weight (Mw) or the number average molecular weight (Mn).

From the viewpoint of generating good intermolecular interaction with the cycloolefin resin A and forming a good sea-island structure, and further improving the transparency, flexibility and transportability of the transparent optical film, the copolymer is used. The polymer B preferably has an octanol-water partition coefficient (hereinafter referred to as logP) in a predetermined range. The octanol-water partition coefficient (hereinafter referred to as logP) of the copolymer B is not particularly limited, but is preferably 4.4 to 4.9. The octanol-water partition coefficient of the copolymer B can be obtained by the same method as described above for the octanol-water partition coefficient of the cycloolefin resin A.

The content of the copolymer B is 1% by mass with respect to the total mass of 100% by mass of the cycloolefin resin A and the copolymer B from the viewpoint of improving the transparency, flexibility and transportability of the transparent optical film. It is preferably 49% by mass or more, more preferably 2% by mass or more and 30% by mass or less, further preferably 3% by mass or more and 15% by mass or more, and 5% by mass or more and less than 10% by mass. It is particularly preferable to have.

[Method for producing copolymer B]
The copolymer B according to this embodiment can be produced by appropriately referring to a conventionally known method. More specifically, it can be produced by polymerizing the above-mentioned monomers (1a) and (2a) and a monomer having at least one radically polymerizable group, if necessary, by radical polymerization.

The radical polymerization initiator used for radical polymerization is not particularly limited, and known compounds such as organic peroxides that generate free radicals and azobis-based radical polymerization initiators can be appropriately adopted. Specific examples of the radical polymerization initiator are not particularly limited, but for example, benzoyl peroxide (benzoyl peroxide), lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-tert-butyl peroxide, tert-butyl kumi. Organic peroxides such as ruperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (2-ethylhexanoylperoxy) hexane; 2,2'-azobis (2,4-dimethylvaleronitrile) ), 2,2'-azobis (2-butyronitrile), 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, 1,1'-azobis (cyclohexane-1- Examples thereof include azo-based initiators such as carbonitrile).

The amount of the radical polymerization initiator used is not particularly limited, but is preferably 0.01 to 20 mol%, more preferably 0.05 to 10 mol%, based on 100 mol% of the total amount of the monomers. It is more preferably 0.1 to 5 mol%.

A catalyst may be used for radical polymerization. The catalyst is not particularly limited, and examples thereof include known anionic polymerization catalysts, coordination polymerization catalysts, and cationic polymerization catalysts.

In radical polymerization, in the presence of a radical polymerization initiator or a catalyst, the above-mentioned monomer is subjected to conventional methods such as bulk polymerization method, solution polymerization method, precipitation polymerization method, emulsion polymerization method, suspension polymerization method, or bulk-suspension polymerization method. It is carried out by copolymerizing by a known method.

[Additive]
In addition to the cycloolefin resin A and the copolymer B, the transparent optical film of the present invention may further contain various additives known in the field of optical films such as matting agents, plasticizers, and ultraviolet absorbers. good.

(Mat agent)
The transparent optical film according to one embodiment of the present invention may further contain a matting agent. The matting agent is not particularly limited, and examples thereof include particles such as organic particles and inorganic particles (including silica particles). The average particle size of the primary particles of the matting agent is not particularly limited, but is preferably 5 to 400 nm, more preferably 10 to 300 nm from the viewpoint of transparency and transportability. The average particle size of the secondary particles of the matting agent is not particularly limited, but is preferably 10 to 400 nm, more preferably 100 to 400 nm.

However, it is preferable that the transparent optical film according to one embodiment of the present invention does not substantially contain particles from the viewpoint of improving the transparency and flexibility of the transparent optical film. As used herein, "substantially free of particles" means that the content of the particles is 0.1% by mass or less with respect to the total mass of the transparent optical film. The content of the particles in the transparent optical film is more preferably 0.01% by mass or less, and further preferably not contained at all (0% by mass).

In addition, in this specification, "particle" means a component which exists in a particle shape in the state of a raw material, the state of a solution or a melt, and the state of a film. Here, the "independent phase" in the sea-island structure is mixed with other components in the state of a solution or a melt to form a uniform phase, or even if phase separation occurs, it does not have a certain shape and is in a flowing state. Since it exists, it is treated as not included in the particles.

(Plasticizer)
The transparent optical film according to one embodiment of the present invention may further contain a plasticizer. The plasticizer is not particularly limited, and examples thereof include polyester, polyhydric alcohol ester, polyvalent carboxylic acid ester (including phthalate ester), glycolate, and ester (including fatty acid ester and phosphoric acid ester). Be done. Among them, a polyester containing a constituent unit derived from a dicarboxylic acid and a constituent unit derived from a diol is preferable. These plasticizers may be used alone or in combination of two or more.

The content of the plasticizer is not particularly limited, but is preferably in the range of 1 to 20 parts by mass, preferably 1.5 to 15 parts by mass, based on 100 parts by mass of the total mass of the cycloolefin resin A and the copolymer B. It is more preferably in the range of parts by mass. When the content of the plasticizer is within the above range, the effect of imparting plasticity can be exhibited, and the resistance to seepage of the plasticizer from the transparent optical film is also excellent.

(UV absorber)
The transparent optical film according to one embodiment of the present invention may further contain an ultraviolet absorber. The ultraviolet absorber is not particularly limited, and examples thereof include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, and nickel complex salt compounds. Further, the ultraviolet absorbers described in JP-A-10-182621 and JP-A-8-337574, and the polymer ultraviolet absorbers described in JP-A-6-148430 are also preferably used. The amount of the ultraviolet absorber added is not particularly limited, but is preferably in the range of 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the total mass of the cycloolefin resin A and the copolymer B. , 0.5 to 3.0 parts by mass, more preferably.

[Sea island structure]
The transparent optical film according to one embodiment of the present invention has a sea-island structure including a continuous phase corresponding to the sea and an independent phase corresponding to the island, and the main component of the independent phase is the copolymer B. The cycloolefin resin A and the copolymer B contained in the transparent optical film according to one embodiment of the present invention form a sea-island structure, and the transparent optical film according to one embodiment of the present invention has such a sea-island structure. It has high transparency while having the above. In addition, the sea-island structure forms surface irregularities, which improves the transportability of the film. Further, since the main component of the independent phase is the copolymer B, the flexibility of the film is improved.

The fact that the transparent optical film has a sea-island structure can be confirmed by observation with a transmission electron microscope (TEM) using a transmission electron microscope (TEM) "JEOL JMS-7401F" (manufactured by JEOL Ltd.) or the like.

In general, of the cycloolefin resin A and the copolymer B, the one having a large addition mass tends to be the main component of the continuous phase, and the one having a small addition mass tends to be the main component of the independent phase.

The average diameter of the independent phase is not particularly limited, but is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, still more preferably 0.8 to 1.4 μm, and 1 More than 0.0 and less than 1.2 is particularly preferable. Here, when the average diameter of the independent phase is at least the above lower limit value, the flexibility and transportability of the transparent optical film are further improved. Further, when the average diameter of the independent phase is not more than the above upper limit value, the transparency and transportability of the transparent optical film are further improved.

The aspect ratio of the independent phase is not particularly limited, but is preferably 1 to 5, more preferably 1.5 to 3.0, still more preferably 2.0 to 2.8, and 2 It is particularly preferable that it is 4.4 to 2.7. When the aspect ratio of the independent phase is the above lower limit value, particularly 1.5 or more, transparency, flexibility and transportability are further improved. Further, when the aspect ratio of the independent phase is not more than the above upper limit value, the transportability and productivity are further improved.

For the average diameter and aspect ratio of the independent phase, the image obtained by using a transmission electron microscope (TEM) "JEOL JMS-7401F" (manufactured by JEOL Ltd.) is used as an image processing device "Luzex" (manufactured by Nireco Corporation). ) Is used for image processing. The details of the measurement method will be described in Examples.

The average diameter and aspect ratio of the independent phase can be controlled by the combination of the cycloolefin resin A and the copolymer B, the content ratio, the film forming method, the stretching ratio, and the like.

The composition of the continuous phase and the independent phase can be confirmed by analyzing the composition of the transparent optical film with a confocal Raman microscope (manufactured by Tokyo Instruments Co., Ltd .: NanoFinder30). The confirmation that the main component of the independent phase is the copolymer B is that the peak is around 1650 cm ^-1 derived from the benzene ring of the above formula (1) and 1730 cm ⁻ derived from the ester bond of the above formula (2). This can be done by appropriately selecting characteristic peaks of the copolymer B such as peaks around ¹ and confirming their existence and strength. Details of the measurement method will be described in Examples.

As another method, the composition of the cycloolefin-based resin A as the main component may be determined by dissolving a transparent optical film, fractionating by a liquid chromatography method, and analyzing the composition. The method can also be applied to the composition of the copolymer B by appropriately selecting the solvent to be dissolved.

[Physical characteristics]
As used herein, the term "transparent optical film" refers to an optical film that can be used in applications that require transparency. Here, transparency can be judged by haze. The upper limit of the haze of the transparent optical film is not particularly limited, but is preferably 1.6% or less, more preferably 1.0% or less, still more preferably 0.9% or less. It is particularly preferable that it is 0.85% or less. The lower limit of the haze of the transparent optical film is most preferably 0% from the viewpoint of transparency, but preferably 0.1% or more from the viewpoint of improving flexibility and transportability, and is 0. It is more preferably 3% or more. The haze can be measured by a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.).

The surface roughness (Ra) of the transparent optical film according to one embodiment of the present invention is preferably 5 to 12 nm, more preferably 5 to 10 nm, and even more preferably 7 to 9 nm. When the surface roughness (Ra) of the transparent optical film is at least the above lower limit value, the transportability is further improved. When the surface roughness (Ra) of the transparent optical film is not more than the above upper limit value, the transparency is improved. It should be noted that the measurement can be performed by using an optical interferometry type surface roughness meter RST / PLUS (manufactured by WYKO) based on the provisions of JIS B0601: 2001.

The dynamic friction coefficient (squeak value) of the transparent optical film according to one embodiment of the present invention is preferably less than 0.8, more preferably less than 0.7, and even more preferably less than 0.55. .. When the coefficient of dynamic friction (squeak value) on the surface of the transparent optical film is not more than the above upper limit value, transparency, flexibility, transportability and productivity are further improved. The dynamic friction coefficient (squeak value) of the transparent optical film according to one embodiment of the present invention is not particularly limited, but is preferably 0.3 or more, more preferably 0.4 or more, and 0.45 or more. The above is more preferable. When the coefficient of dynamic friction (squeak value) on the surface of the transparent optical film is at least the above lower limit value, the flexibility is further improved. The coefficient of dynamic friction (squeak value) on the surface of the transparent optical film can be measured according to JIS K7125: 1987.

The haze, surface roughness (Ra) and dynamic friction coefficient (squeak value) can be controlled by the combination of the cycloolefin resin A and the copolymer B, the content ratio, the film forming method, the stretching ratio and the like. ..

[Film length, width, film thickness]
The transparent optical film is preferably long, specifically, preferably about 100 to 40,000 m in length, and is wound into a roll. The width of the transparent optical film is preferably 1 m or more, more preferably 1.3 m or more, and particularly preferably 1.3 to 4 m.

The film thickness of the transparent optical film after stretching is preferably 5 to 20 μm, more preferably 10 to 15 μm. When it is at least the above lower limit value, the strength of the transparent optical film can be improved and the flexibility is further improved. When it is not more than the above upper limit value, the polarizing plate and the display device can be further thinned, and the flexibility is further improved.

<Manufacturing method of transparent optical film>
Another aspect of the present invention relates to the above-mentioned method for producing a transparent optical film, which comprises a molding step of forming a mixture containing a cycloolefin resin A and a copolymer B into a film. It is preferable that the production method further includes stretching in at least one direction during or after the molding process. Here, the draw ratio is not particularly limited, but is preferably 1.01 times or more and 3 times or less as described later.

The method for producing the transparent optical film is not particularly limited, and a known method can be adopted, but from the viewpoint of productivity, it is preferable to produce the transparent optical film by a solution casting film forming method or a melt casting film forming method, and transparency and transport are preferable. From the viewpoint of property and flexibility, it is more preferable to produce by the solution casting film forming method.
In particular, when a thin film transparent optical film is manufactured by the solution casting film forming method, the resin chains are more likely to be loosened than by melt casting. The entanglement between them increases. From this, it is presumed that a film having excellent transparency and flexibility can be produced.

[Solution casting film formation method]
The transparent optical film has a step of preparing a dope containing at least a cycloolefin resin A, a copolymer B, and a solvent (dope preparation step), and a web (flow) in which the dope is cast on a support. It is obtained by a step of forming a film (also referred to as a spread film) (a casting step), a step of evaporating a solvent from a web on a support (solvent evaporation step), and a step of peeling the web from a support (peeling step). It is manufactured by a step of drying the polymer (pre-drying step), a step of further drying the web after pre-drying (post-drying step), and a step of winding the web after post-drying (winding step). Is preferable. Further, the web may be stretched by providing a step of stretching the web (stretching step) as a next step of each of the above steps after forming the web, particularly a peeling step, a pre-drying step, a post-drying step or a winding step. Further, the web may be stretched by performing an operation (stretching operation) of stretching the web in each of the above steps after forming the web, particularly in the peeling step or the pre-drying step. Among these, when a stretching step is provided, a step of stretching the web (stretching step) is provided as a next step of each of the above steps after web formation, particularly a peeling step, a pre-drying step, a post-drying step or a winding step. It is more preferable to stretch the web.

In each of the above steps, the casting step, the solvent evaporating step, the pre-drying step, the post-drying step and the stretching step are classified into a molding step of forming the mixture into a film.

(Dope preparation process)
The method for preparing a dope containing at least a cycloolefin resin A, a copolymer B, and a solvent in this step is not particularly limited, but includes preparation within a dissolution temperature range of 15 to 50 ° C. Is preferable.

Examples of the solvent used in the solution casting method include chlorine-based solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, isopropanol, n-butanol, and the like. Alcoholic solvents such as 2-butanol; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethylsulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methylethylketone (MEK), ethyl acetate, diethyl ether; and the like. Only one kind of these solvents may be used, or two or more kinds of these solvents may be used in combination.

When the solvent is a mixed solvent of a good solvent and a poor solvent, the good solvent is, for example, dichloromethane as a chlorine-based organic solvent, and methyl acetate, ethyl acetate, amyl acetate, acetone as a non-chlorine-based organic solvent. , Methyl ethyl ketone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3 -Difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2 , 2,3,3,3-pentafluoro-1-propanol, nitroethane and the like, with dichloromethane being preferred. As the poor solvent, an alcohol solvent is preferably used. Among them, it is preferable to select from methanol, ethanol and butanol, and ethanol is more preferable, from the viewpoint of improving the peelability and enabling high-speed casting.

When the solvent is a mixed solvent of a good solvent and a poor solvent, it is preferable to use 55% by mass or more, and 70% by mass or more, the good solvent with respect to the total amount of the solvent from the viewpoint that uniform doping can be easily obtained. It is preferable to use 80% by mass or more, and it is more preferable to use it.

Further, the total mass of the film material in the dope, that is, the cycloolefin resin A and the copolymer B is not particularly limited, but the total mass of the dope is considered from the viewpoint of coating suitability and the surface shape of the transparent optical film to be produced. It is preferably 15 to 30% by mass, more preferably 18 to 27% by mass, and even more preferably 20 to 25% by mass with respect to the mass.

(Hypersalivation process)
The casting method in the casting step is not particularly limited, but an endless metal support, for example, stainless steel, which feeds the dope to the pressure die through a liquid feeding pump (for example, a pressurized metering gear pump) and transfers the dope indefinitely. It is preferable to form a web by casting from a pressure die slit at a casting position on a metal support such as a belt or a rotating metal drum.

(Solvent evaporation step)
The solvent evaporation method in the solvent evaporation step is not particularly limited, but it is preferable to heat the web on the casting metal support to evaporate the solvent and control the amount of residual solvent at the time of peeling described later.

To evaporate the solvent, there are a method of blowing wind from the web side, a method of transferring heat from the back surface of the support by a liquid, a method of transferring heat from the front and back surfaces by radiant heat, and the like, all of which can be preferably used, but the back surface liquid. The heat transfer method is more preferable from the viewpoint of drying efficiency.

(Peeling process)
In the peeling step, the web in which the solvent has evaporated to a desired residual solvent amount on the metal support is peeled from the metal support at the peeling position. The peeled web is sent to the next process.

The temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.

The amount of residual solvent of the web on the metal support at the time of peeling is preferably 15 to 100% by mass. The amount of residual solvent is preferably controlled by the drying temperature and drying time in the solvent evaporation step. When the amount of the residual solvent is at least the above lower limit value, the continuous phase and the independent phase are diffused by the residual solvent, so that a transparent optical film having more excellent transportability and flexibility can be produced. Further, when the amount of the residual solvent is not more than the above upper limit value, the web has self-supporting property, the peeling defect of the web can be avoided, and the mechanical strength of the web can be maintained, so that the peelability is further improved and the peeling tension is applied. The occurrence of slippage and vertical streaks can be further suppressed.

In the peeling step, the web may be stretched by controlling the peeling tension as a stretching operation. The stretching operation and the stretching ratio at this time will be described as a description of the stretching step or the stretching operation described later.

(Preliminary drying process)
The drying step is preferably divided into a pre-drying step and a post-drying step.

In the pre-drying step, the web peeled from the metal support is pre-dried. Pre-drying may be performed while transporting the web with a large number of rollers arranged vertically, or may be performed while transporting the web by fixing both ends with clips as in a tenter dryer. It is preferable to perform pre-drying while fixing with a clip and transporting.

The means for drying the web is not particularly limited, and generally, hot air, infrared rays, heating rollers, microwaves, or the like can be used, but hot air is preferable from the viewpoint of convenience.

The drying temperature in the pre-drying step of the web is not particularly limited, but is preferably 30 ° C. or higher and the glass transition point of the produced transparent optical film −5 ° C. or lower. In certain embodiments, the drying temperature is more preferably 40-200 ° C, even more preferably 50-180 ° C. The drying time is not particularly limited, but is preferably 1 minute or more and 30 minutes or less.

The web may be stretched in the pre-drying step. The stretching operation and the stretching ratio at this time will be described as a description of the stretching step or the stretching operation described later.

(Post-drying process)
After this, in the drying step, the web after pre-drying is heated and dried by a drying device.

In order to adjust the amount of residual solvent contained in the produced transparent optical film, it is preferable to appropriately adjust the conditions of the post-drying step.

In the post-drying step, the web may be dried while being conveyed by a large number of rollers arranged vertically, or may be dried while being conveyed by fixing both ends with clips as in a tenter dryer. It is preferable to dry while transporting by a large number of arranged rollers.

When the web is heated by hot air or the like during drying, a means for preventing the mixing of used hot air by installing a nozzle capable of exhausting used hot air (air containing a solvent or wet air) is also preferably used. The hot air temperature is more preferably in the range of 40 to 350 ° C. The drying time is preferably about 5 seconds to 60 minutes, more preferably 10 seconds to 30 minutes.

The post-drying step is not particularly limited, but is preferably, for example, until the residual solvent amount is 2% by mass or less, more preferably 1% by mass or less, and further preferably 0.5% by mass or less. The web can be dried.

The web may be stretched in the post-drying step. The stretching operation and the stretching ratio at this time will be described as a description of the stretching step or the stretching operation described later.

(Winding process)
In the winding step, after the amount of residual solvent in the web becomes equal to or less than a desired value, the film is wound into a roll as a transparent optical film.

Before winding, the end of the web may be slit with a laser cutter.

As the winding method, a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, and the like, and these may be used properly.

(Stretching process or stretching operation)
The method for producing a transparent optical film according to one embodiment of the present invention preferably further comprises stretching in at least one direction.

The web may be stretched by providing a step of stretching the web (stretching step) as a next step of each of the above steps after forming the web, particularly a peeling step, a pre-drying step, a post-drying step, or a winding step. At this time, the stretching step is provided between the peeling step and the pre-drying step, between the pre-drying step and the post-drying step, between the post-drying step and the winding step, or after the winding step. .. When the stretching step is provided after the winding step, the web (raw film) unwound from the roll undergoes the second post-drying step provided as necessary after the stretching step, and then the second. It is preferable that the film is wound in the winding process of. Among these, it is particularly preferable that the stretching step is provided between the pre-drying step and the post-drying step. Further, the web may be stretched by performing an operation (stretching operation) of stretching the web in each of the above steps after forming the web, particularly in the peeling step or the pre-drying step. Among these, it is preferable to provide a step of stretching the web (stretching step) after the winding step, or to perform the web stretching operation in the pre-drying step, and to perform the web stretching operation in the pre-drying step. It is more preferable to do it.

The transparent optical film produced can be stretched in a stretching device under a desired residual solvent amount to control the aspect ratio of the independent phase in the sea-island structure. In the case of stretching in one direction, the aspect ratio of the independent phase tends to increase as the stretching ratio increases. Further, the stretching treatment enables thinning, widening, improvement of flatness, and the like.

The amount of residual solvent at the start of stretching is not particularly limited, but is preferably 0.01% by mass or more and less than 30% by mass, and more preferably 5 to 25% by mass. When the amount of residual solvent at the start of stretching is at least the above lower limit value, the transparency is further improved and the productivity is further improved. If the amount of residual solvent at the start of stretching is equal to or less than the above upper limit, the stability of the web containing the residual solvent, for example, the longitudinal direction (also referred to as the transport direction, the MD direction, or the spreading direction) or the width direction. Talmi (direction orthogonal to the transport direction, also referred to as TD direction) is further suppressed.

The method of stretching the web is not particularly limited, and a method of applying a peripheral speed difference to a plurality of rolls and stretching in the longitudinal direction using the roll peripheral speed difference between them, and a clip or pin at both ends of the film-like object by a tenter. A method of fixing with a clip or pin and widening the clip or pin spacing in the longitudinal direction (transport direction), fixing both ends of the web with clips or pins using a tenter, and setting the clip or pin spacing in the width direction (with respect to the transport direction). It is possible to adopt a method of expanding and stretching in the vertical direction), a method of simultaneously expanding and stretching the intervals between clips and pins in the longitudinal direction and the width direction (direction perpendicular to the transport direction), and the like. Among these, stretching in the width direction is preferably performed by a tenter. The type of tenter may be a pin tenter or a clip tenter. In the case of the so-called tenter method, it is preferable to drive the clip portion by the linear drive method because smooth stretching can be performed and the risk of breakage can be reduced.

Further, in this step, diagonal stretching may be performed using a tenter capable of diagonal stretching. As the diagonal stretching method in the film drying step and the post-film forming stretching step, a known method can be appropriately adopted.

The stretching operation may be carried out in multiple stages. Further, when biaxial stretching is performed, simultaneous biaxial stretching may be performed, or biaxial stretching may be performed step by step. In this case, the term “stepwise” means, for example, that stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any of the stages. Is also possible.

That is, for example, the following stretching step is also possible:
・ Stretching in the longitudinal direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the width direction ・ Stretching in the width direction → Stretching in the width direction → Stretching in the longitudinal direction → Stretching in the longitudinal direction ・ Stretching in the longitudinal direction → Stretching in the width direction ・ Stretching in the width direction → Stretching in the diagonal direction In addition, simultaneous biaxial stretching includes the case of stretching in one direction and contracting the other by relaxing the tension.

Among these, it is preferable to perform stretching only in the width direction, or when stretching in the longitudinal direction and the width direction, it is preferable to perform stretching so that the stretching ratio in the width direction is maximized, and only in the width direction. It is more preferable to carry out stretching.

The draw ratio in at least one direction is not particularly limited, but is preferably 1.01 times or more and 3 times or less, more preferably 1, 1 times or more and 3 times or less, as described later. It is more preferably 5 times or more and 2 times or less, particularly preferably more than 1.5 times and 1.8 times or less, and most preferably more than 1.5 times and less than 1.8 times. Further, when the draw ratio is not more than the above lower limit value, the aspect ratio of the independent phase becomes larger and the transportability is further improved. When the draw ratio is not more than the above upper limit value, transparency and flexibility are further improved. Here, it is particularly preferable that the draw ratio in the TD direction is within the above range.

The stretching temperature is not particularly limited, but is preferably 30 ° C. or higher and preferably -5 ° C. or lower, which is the glass transition point of the transparent optical film to be produced. In certain embodiments, the drying temperature is more preferably 40-200 ° C, even more preferably 50-180 ° C.

[Melting casting method]
The melt casting method is a method for producing a transparent optical film by melt-kneading a cycloolefin resin A and a copolymer B, and a mixture containing the cycloolefin resin A and the copolymer B is prepared. This is a method in which the material is heated and melted to a temperature at which it exhibits fluidity, cast as a fluidized melt, and formed into a film. That is, it includes a molding step of molding a mixture containing the cycloolefin resin A and the copolymer B into a film.

As for the melt casting film forming method, a known method can be appropriately adopted. The melt casting film forming method can be classified into an extrusion molding method, a press molding method, an inflation molding method, an injection molding method, a blow molding method, a stretch molding method, etc. In order to obtain an excellent film, an extrusion molding method, an inflation molding method, and a press molding method are preferable, and an extrusion molding method is the most preferable.

The molding conditions are appropriately selected depending on the purpose of use and the molding method, and are not particularly limited. For example, when an extrusion molding machine is used, the cylinder temperature of the extrusion molding machine is preferably 150 to 400 ° C, more preferably 200 to 350 ° C, and further preferably 230 to 330 ° C. preferable. When the cylinder temperature is equal to or higher than the above lower limit, the fluidity is further improved, and the occurrence of sink marks and strain in the transparent optical film is further suppressed. Further, when the cylinder temperature is not more than the above upper limit value, the generation of voids and the like due to thermal decomposition of the material is further suppressed, and the occurrence of molding defects such as yellowing of the transparent optical film is further suppressed.

The cycloolefin resin A and the copolymer B are dried using a hot air dryer through which air is passed to remove water, and then a molding machine having a melt kneader equipped with a screw (for example, a T-die film). It is preferable to mold at the temperature of the desired mixture and the temperature of the molding machine using a melt extrusion molding machine or the like).

In the melt casting film forming method, the same steps or operations as those in each step in the solution film forming casting method described above, particularly, a winding step, a stretching step or a stretching operation can be appropriately adopted.

<Use of transparent optical film>
The transparent optical film is preferably used for a multifunctional terminal or a flexible display device. The display device in the multifunction terminal or the flexible display device is not particularly limited, and examples thereof include various display devices such as a liquid crystal display device and an organic electroluminescence display device. The specific application is not particularly limited, but is used as, for example, a polarizing plate protective film, a retardation film, an optical compensation film, an antireflection film, a brightness improving film, a hard coat film, an antiglare film, an antistatic film and the like. sell.

[Polarizer]
A polarizing plate can be provided by arranging a transparent optical film according to an embodiment of the present invention on at least one surface of a polarizing element. The polarizing element is an element that allows only light on a plane of polarization in a certain direction to pass through, and is not particularly limited, but for example, a polyvinyl alcohol-based polarizing film is preferable. Further, the transparent optical film and the polarizing element according to one embodiment of the present invention are bonded together using a completely saponified polyvinyl alcohol aqueous solution (water glue) or an active energy ray-curable adhesive. Is preferable. When the polarizing plate protective film is arranged on both sides of the polarizing element and the transparent optical film according to one embodiment of the present invention is arranged on one surface, the polarizing plate protective film arranged on the other surface is The transparent optical film according to one embodiment of the present invention may be used, or another polarizing plate protective film may be used. The other polarizing plate protective film is not particularly limited, and for example, a known film such as a polyester resin film, a polycarbonate resin film, a cycloolefin resin film, or a cellulose ester resin film can be appropriately used.

[Display device]
The transparent optical film according to one embodiment of the present invention, or a polarizing plate containing the transparent optical film, can be suitably used by being incorporated in a display device. The type of display device is not particularly limited, but a liquid crystal display device or an organic electroluminescence display device is preferable.

(Liquid crystal display device)
By using a polarizing plate to which a transparent optical film according to an embodiment of the present invention is attached to a liquid crystal display device, various liquid crystal display devices having excellent visibility can be manufactured. The type of the liquid crystal display device is not particularly limited, and can be used for various drive type liquid crystal display devices such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB and the like. The transparent optical film according to one embodiment of the present invention is preferably arranged on the viewing side surface when used as a protective film, and is arranged on the liquid crystal cell side when used as a retardation film or an optical compensation film. Is preferable.

(Organic electroluminescence display device)
Since the transparent optical film according to one embodiment of the present invention has high transportability and flexibility, it can be suitably used for an organic electroluminescence display device expected as a flexible display. The organic electroluminescence element applicable to the organic electroluminescence display device is not particularly limited, and examples thereof include known organic electroluminescence elements.

The present invention will be described in more detail with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "part" mean "% by mass" and "part by mass", respectively. Further, as the mixing ratio of each monomer residue, the charged mass ratio is used.

<Preparation of cycloolefin resin A>
[Cycloolefin resin A-1]
A cycloolefin resin A-1 having the following structural units was prepared. The cycloolefin resin A-1 had a ClogP value of 5.456 and a weight average molecular weight (Mw) measured by GPC was 140,000.

* Represents an adjacent structural unit or a bond with a hydrogen atom at the end.

[Cycloolefin resin A-2]
A cycloolefin resin A-2 having the following structural units was prepared. The cycloolefin resin A-2 had a ClogP value of 5.8 and a weight average molecular weight (Mw) of 48,100 measured by GPC.

x: y = 60: 40 (molar ratio or charged mass ratio)
* Represents an adjacent structural unit or a bond with a hydrogen atom at the end.

<Preparation of (co) polymer B>
[Synthesis of copolymer B-1]
To 500 ml of three corbens, add 60 g of dicyclohexyl fumarate, 10 g of diisopropyl fumarate, 30 g of methyl tert-butoxykei dermatate, 0.56 g of benzoyl peroxide, and 200 ml of pure water, and vigorously for 1 hour at room temperature while flowing nitrogen. Stirred. Then, the temperature was raised to 70 ° C. and stirring was continued for 24 hours. After completion of the reaction, water was removed under reduced pressure, 100 ml of tetrahydrofuran was added, and the mixture was heated and dissolved. At that time, the precipitated insoluble matter was removed by filtration, and the obtained solution was added dropwise to 5 L of agitated methanol for reprecipitation purification. After stirring sufficiently, the precipitate was filtered and dried to obtain 34 g of the copolymer B-1. The copolymer B-1 had a ClogP value of 4.5342 and a weight average molecular weight (Mw) measured by GPC was 67,000.

[Synthesis of copolymer B-2]
Copolymer B-2 was synthesized in the same manner as in copolymer B-1, except that methyl tert-butoxykei dermatate was changed to cyclohexyl tert-butoxykei dermatate. The copolymer B-2 had a ClogP value of 4.8342 and a weight average molecular weight (Mw) of 46,000.

[Preparation of copolymer B-3]
Copolymer B-3, which is a styrene-maleimide copolymer, was prepared. The copolymer B-3 had a ClogP value of 4.1685.

The characteristics of the copolymers B-1 to B-3 are summarized in Table 1 below.

<Manufacturing of optical film>
[Manufacturing of optical film 1]
(Preparation of main dope)
A main dope having the following composition was prepared. First, dichloromethane and ethanol were added to the pressurized dissolution tank. Then, the cycloolefin resin A-1 and the copolymer B-1 synthesized above were put into the pressure dissolution tank with stirring. This is heated and completely dissolved while stirring, and this is Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. Filtration was performed using 244 to prepare the main dope.

Cycloolefin resin A-1 92.5 parts by mass Copolymer B-1 7.5 parts by mass Dichloromethane 300 parts by mass Ethanol 20 parts by mass.

(Film formation of optical film)
Using an endless belt spreading device, the main dope prepared above was uniformly cast on a stainless steel belt support at a temperature of 31 ° C. and a width of 1800 mm. The temperature of the stainless steel belt was controlled to 28 ° C. The transport speed of the stainless steel belt was set to 20 m / min. On the stainless belt support, the solvent was evaporated until the amount of residual solvent in the cast film was 40% by mass. Then, the film was peeled from the stainless belt support at a peeling tension of 128 N / m. The peeled film was stretched 1.5 times in the width direction under the condition of 175 ° C. The amount of residual solvent at the start of stretching was 5% by mass. Next, drying was completed while the drying zone was conveyed by a large number of rollers, the end portion sandwiched between the tenter clips was slit with a laser cutter, and then the film was wound to produce an optical film 1 having a film thickness of 10 μm.

[Manufacturing of optical films 2 to 6 and 8 to 10]
Optical film except that the type of copolymer B, the addition ratio of each of the cycloolefin resin A and the copolymer B when the total is 100 parts by mass, and the draw ratio are changed to those shown in Table 2. Optical films 2 to 6 and 8 to 10 were manufactured in the same manner as in 1.

[Manufacturing of optical film 7]
The above cycloolefin resin A-2 was dried at 70 ° C. for 2 hours using a hot air dryer in which air was passed to remove water, and then the cycloolefin resin A-2 was subjected to 92.5 parts by mass. Then, 7.5 parts by mass of the copolymer B-2 was added. The obtained mixture was melted and kneaded using a T-die film melt-extruding machine (T-die width 500 mm) equipped with a 65 mmφ screw under molding conditions of a molten resin temperature of 240 ° C and a T-die temperature of 240 ° C. After being extruded, it was stretched 1.8 times in the width direction under the condition of 150 ° C. As a result, an optical film 7 having a thickness of 10 μm was manufactured.

<Evaluation of optical film>
[Confirmation of sea island structure]
The fact that the transparent optical film has a sea-island structure was confirmed by observation with a transmission electron microscope (TEM) "JEOL JMS-7401F" (manufactured by JEOL Ltd.).

[Average diameter of independent phase, aspect ratio]
The average diameter of the independent phase is the image obtained by using a transmission electron microscope (TEM) "JEOL JMS-7401F" (manufactured by JEOL Ltd.) and an image processing device "Luzex" (manufactured by Nireco Corporation). It was obtained as the average value of the shape coefficients ML and BD obtained by image processing, that is, (ML + BD) / 2. Here, ML is the average value of the maximum lengths of the independent phases when 10 independent phases are observed, and BD is two straight lines parallel to the ML when 10 independent phases are observed. It is the average value of the minimum width between two straight lines when the island phase is sandwiched. Further, the aspect ratio of the independent phase was determined as ML / BD using the shape coefficients ML and BD obtained above.

[Specification of independent phase components]
The composition analysis of the transparent optical film was performed using a confocal Raman microscope (manufactured by Tokyo Instruments Co., Ltd .: NanoFinder30). The excitation wavelength was 785 nm, the laser power was 18 mW, and a 100x objective lens was used. The total time was 120 seconds.

First, a 20 cm square measurement sample was cut out from the transparent optical film. Next, the measurement sample was cut at three cutting positions so that the cutting positions viewed from one side were at intervals of 5 cm. Subsequently, for each of the obtained cut surfaces at the three cut positions, the measurement positions of the three points on each cut surface were determined so as to be at intervals of 5 cm. In this way, the measurement positions of 9 points were determined. When determining the measurement position, two cut pieces having a cut surface at the cut position can be obtained for one cut position, but one of the cut pieces is selected and the measurement is performed on each cut surface. Used to determine the position.

For each of the determined measurement positions, the interval is 0.50 μm (that is, corresponding to the interval of 0.50 μm in the film thickness direction) from the surface side of the air surface side at the time of casting toward the surface side of the stainless steel belt side at the time of casting. As a measurement point, composition analysis was performed by Raman spectroscopy (microscopic Raman spectroscopy) using the above Raman microscope. In this way, the spectra of each (co) polymer constituting the independent phase and the continuous phase were measured at each measurement point, and the components of the independent phase were specified. Here, the fact that the main component of the independent phase is the copolymer B is around 1650 cm ^{-1 derived from the benzene ring of the above formula (1) and around 1730 cm -1 derived} from the ester bond of the above formula (2). The presence and intensity of the peak of benzene were confirmed and judged.

[Haze]
In an environment of 23 ° C and 50% RH relative humidity, 10 points were measured at equal intervals in the width direction of the optical film with a haze meter (Nippon Denshoku Industries Co., Ltd., NDH2000), and the average value was calculated and haze was obtained. It was set to (%). These results are shown in Table 2.

[Surface roughness Ra]
Based on the provisions of JIS B0601: 2001, the measurement was performed using an optical interferometry surface roughness meter RST / PLUS (manufactured by WYKO) to determine the surface roughness Ra (nm) of the optical film. These results are shown in Table 2.

[Transportability]
The transportability was evaluated by measuring the dynamic friction coefficient (squeak value). For the dynamic friction coefficient between the front and back surfaces of the optical film, two transparent optical films obtained above were prepared, stacked so that the front and back surfaces of these films were in contact with each other, a weight of 150 g was placed, and the sample movement speed was 200 mm / min. A load cell (LRU-2K, manufactured by Nippon Special Instruments Co., Ltd.) was installed on one of the films under the condition of a contact area of 35 mm x 100 mm, pulled in the horizontal direction, and the average load (F) was measured. The dynamic friction coefficient (μ) was calculated. Next, after inverting the front and back of the two transparent optical films, they are overlapped so that the front and back surfaces of these films are in contact with each other, and similarly, the average load (F) while the weight is moving is measured again, and the following is performed. The dynamic friction coefficient (μ) was calculated again from the equation. The average value of the dynamic friction coefficient (μ) obtained by these two measurements in total was adopted as the dynamic friction coefficient (squeak value);
Dynamic friction coefficient = F (gf) / weight weight (gf)
The obtained results were evaluated according to the following evaluation criteria. The smaller the coefficient of dynamic friction (squeak value), the better the slipperiness and the better the transportability, and if it is Δ or more, it has the desirable characteristics for practical use;
⊚: Squeak value is less than 0.55 ○: Squeak value is 0.55 or more and less than 0.7,
Δ: Squeak value is 0.70 or more and less than 0.8,
×: Cannot be measured because the squeak value is 0.8 or more or the film is stuck.

These results are shown in Table 2.

[Flexibility]
A folding resistance tester (manufactured by Tester Sangyo Co., Ltd., MIT, BE-201 type, bending radius of curvature 0.38 mm) was used. As a test piece, an optical film having a width of 15 mm and a length of 150 mm, which was allowed to stand at a temperature of 25 ° C. and a relative humidity of 65% RH for 1 hour or more, was used, and under the condition of a load of 500 g, it complied with JIS P8115: 2001. And evaluated according to the following evaluation criteria according to the number of times until it breaks. The greater the number of times until breaking, the better the flexibility, the better the resistance to repeated bending, and if it is Δ or more, it has practically desirable characteristics;
⊚: The number of times until it breaks is 10,000 times or more,
◯: The number of times until breakage is 5,000 or more and less than 10,000 times,
Δ: The number of times until breakage is 1,000 or more and less than 5,000,
X: The number of times until it breaks is less than 1,000 times,
These results are shown in Table 2.

In Table 2, the cycloolefin resin A is simply shown as A, and the copolymer B is simply shown as B.

As shown in the results of Table 2, the optical film No. 1 according to the present invention. Nos. 1 to 7 are transparent optical films having excellent transparency, and it was confirmed that they have transportability and flexibility. On the other hand, the optical film No. 2 according to the comparative example. 8 to 10 were inferior in transportability and flexibility. The optical film No. In No. 9, it is considered difficult to transfer the film in the process because the transferability evaluation result could not be obtained due to the sticking of the film after winding. From this, the excellent effect of the present invention was confirmed.

Claims (7)

Cycloolefin resin A and
The following formula (1):

In the formula (1), X ¹ independently represents a linear alkyl group, a branched chain alkyl group, or a cyclic alkyl group, and X ² independently represents a linear alkyl group and a branched chain alkyl group, respectively. , Cyclic alkyl group, alkoxy group, aryloxy group, ester group, hydroxyl group, carboxyl group, halogen atom, or cyano group, a represents an integer of 0 to 5, and * represents an adjacent structural unit or terminal group. Represents a joint;
The structural unit represented by and the following formula (2):

In formula (2), X ³ and X ⁴ both represent a branched chain alkyl group or both represent a cyclic alkyl group, and * represents a bonding moiety with an adjacent structural unit or terminal group; Containing, comprising, the copolymer B, including the building blocks,
In the copolymer B, it is represented by the formula (1) with respect to the total mass of 100% by mass of the structural unit portion represented by the formula (1) and the structural unit portion represented by the formula (2). The mass of the structural unit portion is 2 to 90% by mass, and the mass of the structural unit portion represented by the above formula (2) is 10 to 98% by mass.
In the copolymer B, a structural unit portion represented by the above formula (2) and in which X ³ and X ⁴ are branched chain alkyl groups and represented by the above formula (2), and X ³ and X ⁴ are represented. Is represented by the above formula (2), and the mass of the structural unit portion in which X3 and X4 ^{are branched} chain alkyl groups is 1 to 1 to 100% by mass of the total mass of the structural unit portion in which is a cyclic alkyl group. The mass of the structural unit portion which is 50% by mass, is represented by the above formula (2), and X3 ^{and X4} are cyclic alkyl groups is 50 to 99% by mass.
It has a sea-island structure consisting of a continuous phase corresponding to the sea and an independent phase corresponding to an island.
The main component of the independent phase is the copolymer B,
The independent phase satisfies at least one of the aspect ratio of the independent phase of 1.5 or more and the aspect ratio of the independent phase of 1.4 or more and 5 or less.
It is a stretched film ,
Transparent optical film. The cycloolefin resin A has the following formula (3):

In the formula (1), A ¹ to A ⁴ are independently described in the following (i) to (iv) :.
(I) Hydrogen atom (ii) Halogen atom,
(Iii) Hydrocarbon group, or (iv) Hydrogen bond accepting group,
Or the following (v) or (vi):
(V) A ¹ and A ² or A ³ and A ⁴ bind to each other to form an alkylidene group, and A ¹ to A ⁴ not involved in the binding are independent of the above (i) to (i) to (). Represents a group selected from iv),
(Vi) A ¹ and A ³ , A ¹ and A ⁴ , A ² and A ³ , or A ² and A ⁴ are bonded to each other to form a cyclic structure together with the carbon atoms to which they are bonded, and the bond is formed. A ¹ to A ⁴ not involved each independently represent a group selected from the above (i) to (iv);
, B represents 0 or 1, and c represents an integer greater than or equal to 0;
The transparent optical film according to claim 1, which is a cycloolefin-based resin having a structural unit derived from the monomer represented by. The transparent optical film according to claim 1 or 2, wherein X ² is an alkoxy group. The transparent optical film according to any one of claims 1 to 3, wherein the aspect ratio of the independent phase is 1.5 or more. The transparent optical film according to any one of claims 1 to 4, wherein the haze is 0.9% or less. The transparent optical film according to any one of claims 1 to 5, which contains substantially no particles. A molding step of molding a mixture containing the cycloolefin resin A and the copolymer B into a film is included.
The method for producing a transparent optical film according to any one of claims 1 to 6, which comprises stretching at a magnification of 1.01 times or more and 3 times or less in at least one direction during or after the molding step.