JP7380559B2 - Optical films, optical laminates, and liquid crystal display devices - Google Patents

Description

The present invention relates to an optical film, an optical laminate, and a liquid crystal display device.

Conventionally, optical films made of thermoplastic resin are known. For example, Patent Document 1 discloses an optical film containing a thermoplastic norbornene resin.

Japanese Patent Application Publication No. 2003-238705 (corresponding publication: US Patent Application Publication No. 2004/057141)

Optical films used in liquid crystal display devices are required to have excellent retardation properties and high retardation Rth in the thickness direction. One possible method for obtaining an optical film with high retardation Rth in the thickness direction using a conventional film made of thermoplastic resin is to stretch it at a high stretching ratio. However, when a film obtained by stretching at a high stretching ratio is adhered to another member, there is a phenomenon (delamination) in which the film peels off from the other member due to destruction of the area near the surface of the film. Occasionally this occurred.

The present invention was created in view of the above-mentioned problems, and includes an optical film that has excellent retardation properties, high retardation in the thickness direction, and suppresses the occurrence of delamination, and an optical laminate including the optical film. , and a liquid crystal display device including the optical laminate.

The inventors of the present invention have made extensive studies to solve the above problems. As a result, the present inventor used a thermoplastic norbornene-based resin with a large stress birefringence C _R and a high glass transition temperature Tg as the material of the optical film, and the retardation in the thickness direction with respect to the thickness d of the optical film. The inventors have discovered that the above problem can be solved by setting the ratio of Rth (Rth/d) to a predetermined value or more, and have completed the present invention.
That is, the present invention includes the following.

[1] An optical film made of thermoplastic norbornene resin,
The thermoplastic norbornene resin has a stress birefringence C _R greater than 2900×10 ⁻¹² Pa ⁻¹ and a glass transition temperature Tg of 125° C. or higher,
The ratio of the retardation Rth in the thickness direction to the thickness d (Rth/d) of the optical film is 3.5×10 ⁻³ or more,
An optical film that is a stretched film.
[2] The optical film according to [1], which has an in-plane retardation Re of 40 nm or more and 80 nm or less.
[3] The thermoplastic norbornene resin contains a polymer,
The optical film according to [1] or [2], wherein the polymer contains a norbornene monomer unit having an aromatic ring structure.
[4] The optical film according to [3], wherein the polymer contains 25% by weight or more of norbornene monomer units having the aromatic ring structure.
[5] The optical film according to any one of [1] to [4],
An optical laminate comprising: a polarizing plate provided on the optical film.
[6] A liquid crystal display device comprising the optical laminate according to [5].

According to the present invention, an optical film having excellent retardation properties, high retardation in the thickness direction, and suppressing the occurrence of delamination, an optical laminate including the optical film, and a liquid crystal display including the optical laminate Display devices can be provided.

Hereinafter, the present invention will be described in detail by showing embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be implemented with arbitrary changes within the scope of the claims of the present invention and equivalents thereof.

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

In the following description, unless otherwise specified, the direction of the constituent elements is "parallel", "perpendicular", or "orthogonal" within a range that does not impair the effects of the present invention, for example, usually ±5°, preferably ±2 It may include an error within a range of 1°, more preferably ±1°.

In the following description, the MD direction (machine direction) is the flow direction of the film in the production line, and the TD direction (traverse direction) is a direction parallel to the film surface and perpendicular to the MD direction. For convenience, the longitudinal direction of a long film may be referred to as the MD direction of the film, and the width direction may be referred to as the TD direction of the film.
In the following description, a "long" film refers to a film that has a length of 5 times or more, preferably 10 times or more, with respect to the width of the film. refers to something long enough to be rolled up and stored or transported. The upper limit of the ratio of the length to the width of the film is not particularly limited, but may be, for example, 100,000 times or less.

In the following description, unless otherwise specified, the term "polarizing plate" includes not only rigid members but also flexible members such as resin films.

[1. Optical film]
The optical film of the present invention is a film made of thermoplastic norbornene resin. The optical film is a stretched film obtained by stretching a film that is a material for the optical film. In the following description, a film that is a material for an optical film is also referred to as a "unstretched film."

(Thermoplastic norbornene resin)
Thermoplastic norbornene-based resins include polymers. Examples of the polymer contained in the thermoplastic norbornene resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, or Hydrides thereof; examples include addition polymers of monomers having a norbornene structure, addition copolymers of monomers having a norbornene structure and other monomers, and hydrides thereof.

Monomers having a norbornene structure include bicyclo[2.2.1]hept-2-ene (common name: norbornene), tricyclo[4.3.0.1 ^2,5 ]deca-3,7-diene (common name: dicyclopentadiene, also referred to as "DCPD"), tetracyclo[4.4.0.1 ^2,5 . 17,10] dodec-3-ene (common name: tetracyclododecene, also referred to as "TCD"), and derivatives of these compounds (eg, those having a substituent on the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Further, a plurality of these substituents, which are the same or different, may be bonded to the ring. Monomers having a norbornene structure can be used alone or in combination of two or more.

Examples of the polar group include a heteroatom or an atomic group having a heteroatom. Examples of heteroatoms include oxygen atoms, nitrogen atoms, sulfur atoms, silicon atoms, and halogen atoms. Specific examples of the polar group include carboxyl group, carbonyloxycarbonyl group, epoxy group, hydroxyl group, oxy group, ester group, silanol group, silyl group, amino group, nitrile group, and sulfone group. In order to obtain a film with a low saturated water absorption rate, it is preferable that the amount of polar groups is small, and it is more preferable that the film has no polar groups.

As the monomer having a norbornene structure, a norbornene monomer having an aromatic ring structure may be used together with the above-mentioned monomer having a norbornene structure, or in place of the above-mentioned monomer, from the viewpoint of excellent phase difference expression property. You can use your body.

Examples of norbornene monomers having an aromatic ring structure include 5-phenyl-2-norbornene, 5-(4-methylphenyl)-2-norbornene, 5-(1-naphthyl)-2-norbornene, and 9-(2-norbornene). Norbornene monomer having an aromatic substituent such as -norbornen-5-yl)-carbazole; 1,4-methano-1,4,4a,4b,5,8,8a,9a-octahydrofluorene, 1 , 4-methano-1,4,4a,9a-tetrahydrofluorene (common name: methano-tetrahydrofluorene, hereinafter also referred to as "MTF"), 1,4-methano-1,4,4a,9a-tetrahydrodibenzofuran, 1, 4-methano-1,4,4a,9a-tetrahydrocarbazole, 1,4-methano-1,4,4a,9,9a,10-hexahydroanthracene, 1,4-methano-1,4,4a,9 , 10,10a-hexahydrophenanthrene; norbornene monomers having a norbornene ring structure and an aromatic ring structure in a condensed polycyclic structure; and the like. These monomers can be used alone or in combination of two or more.

The norbornene monomer having an aromatic ring structure may have a substituent. Examples of substituents include alkyl groups such as methyl, ethyl, propyl, and isoprokyl groups; alkylidene groups; alkenyl groups; halogen groups such as fluoro, chloro, bromo, and iodo groups; hydroxy groups; ester groups; alkoxy group; cyano group; amide group; imide group; silyl group and the like. The norbornene monomer having an aromatic ring structure may have two or more of these substituents.

Other monomers that can be ring-opening copolymerized with the monomer having a norbornene structure include monocyclic olefins and derivatives thereof such as cyclohexene, cycloheptene, and cyclooctene; cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene; Derivatives thereof; and the like.

Ring-opening polymers of monomers having a norbornene structure and ring-opening copolymers of monomers having a norbornene structure and other monomers that can be copolymerized can be prepared using a known ring-opening polymerization catalyst. It can be obtained by (co)polymerization in the presence of

Other monomers that can be addition-copolymerized with the monomer having a norbornene structure include, for example, α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, Examples include cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferred, and ethylene is more preferred.

Addition polymers of monomers having a norbornene structure and addition copolymers of monomers having a norbornene structure and other monomers that can be copolymerized are prepared by adding the monomers in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

Hydrogenated products of ring-opening polymers of monomers having a norbornene structure, hydrides of ring-opening copolymers of monomers having a norbornene structure and other monomers that can be copolymerized with ring-opening, norbornene structures hydrides of addition polymers of monomers having a ) A known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to a solution of the polymer or addition (co)polymer, and hydrogen is brought into contact with the solution to hydrogenate carbon-carbon unsaturated bonds. Obtainable.

In the present invention, the polymer used is a ring-opened (co)polymer in which non-aromatic unsaturated bonds are selectively hydrogenated, from the viewpoint of excellent retardation development properties, and which has an aromatic ring structure. It is preferable to use a norbornene monomer unit. Here, the term "monomer unit" refers to a structural unit having a structure formed by polymerizing the monomers.

A polymer containing a norbornene monomer unit having an aromatic ring structure can be obtained by adding a ruthenium catalyst to a solution of the ring-opened (co)polymer or addition (co)polymer and bringing it into contact with hydrogen. can. Ruthenium catalysts include (1,3-dimesitylimidazolidin-2-ylidene) (tricyclohexylphosphine) benzylidene ruthenium dichloride, chlorohydridocarbonyl tris (triphenylphosphine) ruthenium, bis (tricyclohexylphosphine) benzylidine ruthenium ( IV) Dichloride, dichlorotris(triphenylphosphine)ruthenium, dichlorocarbonyltris(triphenylphosphine)ruthenium. By analyzing the product obtained as a result of such hydrogenation by ¹ H-NMR, the presence or absence of carbon-carbon double bonds in the main chain structure is analyzed separately from unsaturated bonds in the aromatic ring structure. be able to. Therefore, by such ¹ H-NMR analysis, it can be confirmed whether or not non-aromatic unsaturated bonds have been selectively hydrogenated.

When the polymer contains a norbornene monomer unit having an aromatic ring structure, the amount of the norbornene monomer unit having an aromatic ring structure in the polymer is preferably 25% by weight or more, more preferably 40% by weight. % or more, preferably 80% by weight or less, more preferably 60% by weight or less. When the amount of norbornene monomer units having an aromatic ring structure in the polymer is at least the lower limit, stress birefringence _CR can be increased, while suppressing the stretching ratio when stretching the film before stretching. The Rth of the optical film can be increased.

The molecular weight of the polymer contained in the thermoplastic norbornene resin is appropriately selected depending on the intended use of the optical film, but it can be measured by gel permeation chromatography using cyclohexane (or toluene if the resin does not dissolve) as a solvent. The weight average molecular weight (Mw) in terms of polyisoprene (polystyrene when the solvent is toluene) is preferably 10,000 to 100,000, more preferably 15,000 to 80,000, particularly preferably 20,000 to 60,000. When the weight average molecular weight is within this range, the mechanical strength and moldability of the film are highly balanced, which is preferable.

The molecular weight distribution (weight average molecular weight (Mw)/number average molecular weight (Mn)) of the polymer contained in the thermoplastic norbornene resin is not particularly limited, but is usually 1.0 to 10.0, preferably 1.0 to 5.0, more preferably in the range of 1.0 to 3.5.

The thermoplastic norbornene resin may contain arbitrary components other than the polymer. Optional ingredients include ultraviolet absorbers, antioxidants, heat stabilizers, light stabilizers, antistatic agents, dispersants, chlorine scavengers, flame retardants, crystallization nucleating agents, reinforcing agents, antiblocking agents, and antifogging agents. , mold release agents, pigments, organic or inorganic fillers, neutralizing agents, lubricants, decomposers, metal deactivators, antifouling agents, and antimicrobial agents.

Examples of UV absorbers include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone UV absorbers, benzotriazole UV absorbers, acrylonitrile UV absorbers, triazine compounds, nickel complex compounds, and inorganic powders. Examples of suitable UV absorbers are 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol), 2-( 2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2,4-di-tert-butyl-6-(5-chlorobenzotriazol-2-yl)phenol, Examples include 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 2,2',4,4'-tetrahydroxybenzophenone. A particularly suitable example is 2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol).

When the thermoplastic norbornene resin contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 0.5 to 5% by weight based on 100% by weight of the thermoplastic norbornene resin.

(Physical property values of thermoplastic norbornene resin)
In the present invention, the stress birefringence C _R of the thermoplastic norbornene resin is greater than 2900×10 ⁻¹² Pa ⁻¹ . The stress birefringence C _R of the thermoplastic norbornene resin is preferably 2910×10 ⁻¹² Pa ⁻¹ or more, more preferably 3000×10 ⁻¹² Pa ⁻¹ or more, and preferably 8000×10 ⁻¹² Pa ⁻¹ It is more preferably 6000×10 ⁻¹² Pa ⁻¹ or less. By increasing the stress birefringence C _R of the thermoplastic norbornene resin to be larger than 2900×10 ⁻¹² Pa ⁻¹ , the Rth of the optical film can be increased while suppressing the stretching ratio when stretching the film before stretching. . By controlling the stress birefringence C _R of the thermoplastic norbornene resin to be less than or equal to the upper limit value, it becomes easier to control Re and Rth of the film, and in-plane variations can be suppressed.

Stress birefringence C _R can be controlled by changing the proportion of monomers used in producing the polymer contained in the thermoplastic norbornene resin. For example, stress birefringence C _R can be increased by increasing the proportion of the norbornene monomer having the above-mentioned aromatic ring structure.

Stress birefringence C _R can be measured, for example, by the following method.
A sample is prepared by molding a thermoplastic norbornene resin into a sheet, and after fixing both ends of the sample with clips, a weight of a predetermined weight (for example, 160 g) is fixed to one of the clips. Next, the sheet is hung in an oven set at a predetermined temperature (for example, the glass transition temperature (Tg) of the resin + 5°C) for a predetermined period of time (for example, 1 hour) using the clip to which the weight is not fixed as a support point. Perform stretching process. The stretched sample sheet is slowly cooled down to room temperature and used as a measurement sample. Regarding the measurement sample, the retardation value (anm) at the center of the measurement sample and the thickness (bmm) at the center of the measurement sample are measured using birefringence. Using the measured values (a, b), the δn value is calculated by the following formula (1).
δn=a×(1/b)× ^10-6 (1)

Using the δn value and the stress applied to the sample (in the above case, the stress applied when a predetermined weight was fixed), C _R can be calculated using the following formula (2).
C _R = δn/stress (2)

The glass transition temperature Tg of the thermoplastic norbornene resin is 125°C or higher. The glass transition temperature Tg is preferably 130°C or higher, more preferably 135°C or higher, and preferably 180°C or lower, more preferably 160°C or lower. By setting the glass transition temperature Tg to 125° C. or higher, the optical film can have excellent heat resistance and durability. Tg can be measured using a differential scanning calorimeter.

(Film before stretching)
The pre-stretched film, which is the material of the optical film, is a film made of the above-mentioned thermoplastic norbornene resin.
The pre-stretched film can be produced by molding a thermoplastic norbornene resin into a film by a known method, such as a cast molding method, an extrusion molding method, an inflation molding method, or the like.

(optical film)
The optical film is obtained by stretching a pre-stretched film. The conditions for stretching the pre-stretched film to form an optical film can be appropriately selected so as to obtain desired optical properties. For example, the stretching mode when stretching the pre-stretched film to form an optical film may be any mode such as uniaxial stretching, biaxial stretching (simultaneous biaxial stretching, sequential biaxial stretching), etc. Among these embodiments, biaxial stretching is preferred. In addition, when the film before stretching is a long film, the direction of stretching is the longitudinal direction (parallel to the longitudinal direction of the long film), the transverse direction (parallel to the width direction of the long film). direction) or diagonal direction (direction that is neither vertical nor horizontal).

The stretching ratio when stretching the film before stretching to form an optical film is preferably 1.4 or more, more preferably 1.5 or more, and preferably 2.2 or less, more preferably 2.1 or less. . When the stretching ratio is at most the upper limit of the range, the occurrence of delamination can be more effectively suppressed, and when the stretching ratio is at least the lower limit of the range, Rth can be increased. When the unstretched film is stretched by biaxial stretching in the MD direction and the TD direction, it is preferable that the product of the stretching ratio in the MD direction and the stretching ratio in the TD direction falls within the above range.

The stretching temperature when stretching the pre-stretched film to form an optical film is preferably Tg°C or higher, more preferably (Tg+5)°C or higher, while preferably (Tg+40)°C or lower, more preferably (Tg+30)°C. It is as follows. By setting the stretching temperature within the above range, an optical film with a uniform thickness can be obtained.

(Physical property values of optical film)
The thickness d of the optical film is preferably 30 μm or more, more preferably 40 μm or more, and preferably 150 μm or less, more preferably 100 μm or less. By setting the thickness of the optical film at or above the lower limit, the occurrence of delamination can be effectively suppressed, and by setting the thickness of the optical film at or below the upper limit, the device in which the optical film is incorporated can be made thinner. can.

In the present invention, the ratio of the retardation Rth in the thickness direction to the thickness d of the optical film (Rth/d) is 3.5×10 ⁻³ or more. Rth/d is preferably 3.5×10 ⁻³ or more, more preferably 4.0×10 ⁻³ or more, and preferably 8.0×10 ⁻³ or less, more preferably 6.0×10 ⁻³ It is as follows. By setting Rth/d to 3.5×10 ⁻³ or more, an optical film with a high Rth and a small thickness can be obtained, and thereby a film with excellent optical compensation properties can be obtained. By setting Rth/d below the upper limit value, the occurrence of delamination can be more effectively suppressed.

The in-plane retardation Re of the optical film is preferably 40 nm or more, more preferably 50 nm or more, and preferably 80 nm or less, more preferably 70 nm or less. By setting Re to be equal to or greater than the lower limit value, it is possible to improve the phase difference development property, and by setting Re to be equal to or less than the upper limit value, in-plane variation can be suppressed. The retardation Re can be appropriately selected from within the above range to suit the design of the display device.

(optical laminate)
The optical laminate of the present invention includes the optical film of the present invention and a polarizing plate provided thereon.

As a polarizing plate, a polarizer made of a polyvinyl alcohol-based polarizing film containing a dichroic substance, etc., with a film (protective film) bonded to one side or both sides to serve as a protective layer, for example, via an adhesive layer, can be used. .

As a polarizer (polarizing film), for example, a film made of a vinyl alcohol polymer such as polyvinyl alcohol or partially formalized polyvinyl alcohol is dyed with a dichroic substance such as iodine or a dichroic dye, stretched, or crosslinked. It is possible to use a material that has been subjected to processing such as treatment. As the polarizer, one that transmits linearly polarized light when natural light is incident can be used.

A transparent film can be used as the protective film material that becomes the transparent protective layer provided on one or both sides of the polarizer (polarizing film). As the transparent film, a film made of a resin having excellent transparency, mechanical strength, thermal stability, moisture shielding property, etc. is preferably used. Examples of such resins include acetate resins such as triacetylcellulose, polyester resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, norbornene resins, and acrylic resins. Examples include resin. From the viewpoint of low birefringence, acetate-based resins or norbornene-based resins are preferred, and from the viewpoints of transparency, low hygroscopicity, dimensional stability, lightweight, etc., norbornene-based resins are particularly preferred.
Although the thickness of the protective film is arbitrary, it is generally 500 μm or less, preferably 5 to 300 μm, particularly preferably 5 to 150 μm, for the purpose of making the polarizing plate thinner.

The optical film and the polarizing plate can be laminated by bonding them together via a layer that adheres them. Examples of such layers include adhesive layers and adhesive layers. Examples of the adhesive or pressure-sensitive adhesive include acrylic, silicone, polyester, polyurethane, polyether, and rubber adhesives. Among these, acrylic materials are preferred from the viewpoint of heat resistance, transparency, etc.
In the optical laminate of the present invention, the optical film of the present invention can also serve as a protective film for the polarizing plates to be laminated, and the member can be made thinner. Further, the optical film and the polarizing plate can be laminated by roll-to-roll, and a long optical laminate can be obtained. The angle between the slow axis of the optical film and the absorption axis of the polarizing plate in the optical laminate may be within the range of 90°±1°.

The thickness of the optical laminate of the present invention is preferably 30 μm or more, more preferably 40 μm or more, and preferably 150 μm or less, more preferably 100 μm or less.

[Liquid crystal display device]
The liquid crystal display device of the present invention includes the optical laminate of the present invention. The liquid crystal display device of the present invention includes the optical laminate of the present invention on at least one side of a liquid crystal cell.
In a liquid crystal display device, an optical film is usually provided between a liquid crystal cell and a viewing side polarizer of the liquid crystal display device. In such a configuration, the optical film can function as a viewing angle compensation film.

The liquid crystal cell can be operated in, for example, in-plane switching (IPS) mode, vertical alignment (VA) mode, multi-domain vertical alignment (MVA) mode, continuous spin wheel alignment (CPA) mode, hybrid alignment nematic (HAN) mode, or twisted nematic mode. A liquid crystal cell in any mode, such as (TN) mode, super twisted nematic (STN) mode, or optically compensated bend (OCB) mode, can be used.

When polarizing plates are provided on both sides of the liquid crystal cell, the polarizing plates may be the same or different.

In the liquid crystal display device of the present invention, an adhesive layer may be provided to adhere the optical laminate of the present invention and the liquid crystal cell. The adhesive layer can be appropriately formed using a conventionally known adhesive such as an acrylic adhesive. Among these, moisture absorption is important because it prevents foaming and peeling phenomena caused by moisture absorption, decreases in optical properties due to differences in thermal expansion, prevents warpage of liquid crystal cells, and the formability of high-quality and durable liquid crystal display devices. It is preferable that the adhesive layer has low heat resistance and excellent heat resistance. Further, it may be an adhesive layer or the like that contains fine particles and exhibits light diffusing properties.

The present invention will be specifically described below with reference to Examples. However, the present invention is not limited to the following examples, and may be implemented with arbitrary changes within the scope of the claims of the present invention and equivalents thereof.
In the following description, "%" and "part" expressing amounts are based on weight unless otherwise specified. The following operations were performed in the atmosphere at room temperature and pressure unless otherwise specified.

[Measurement method and calculation method of physical property values of polymer]
(Measurement of weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn))
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymers (ring-opening polymer, polymers (1) to (3), and polymers (C1) to (C5)) are determined by using cyclohexane as an eluent. It was measured by gel permeation chromatography (GPC) and calculated as a standard polyisoprene equivalent value.
As the standard polyisoprene, standard polyisoprene manufactured by Tosoh Corporation (Mw=602, 1390, 3920, 8050, 13800, 22700, 58800, 71300, 109000, 280000) was used.
The measurement was performed using three Tosoh columns (TSKgelG5000HXL, TSKgelG4000HXL, and TSKgel G2000HXL) connected in series under the conditions of a flow rate of 1.0 mL/min, a sample injection amount of 100 μL, and a column temperature of 40°C.
The molecular weight distribution (Mw/Mn) was calculated using the measured values measured by the above method.

(Measurement of glass transition temperature (Tg))
The glass transition temperature (Tg) of Polymers (1) to (3) and Polymers (C1) to (C5) was measured using a differential scanning calorimeter (manufactured by Nano Technology Co., Ltd., product name: DSC6220SII) according to JIS K. 6911, and measured at a temperature increase rate of 10° C./min.

(Measurement of stress birefringence _CR )
Samples were prepared by molding each of Polymers (1) to (3) and Polymers (C1) to (C5) into a sheet of 35 mm x 10 mm x 1 mm. After fixing both ends of this sample with clips, a 160 g weight was fixed to one of the clips. Next, the sheet was suspended for 1 hour in an oven with the temperature set to the glass transition temperature (Tg) of the polymer + 5°C using the clip to which no weight was fixed as a support point, and then stretched. The sample was slowly cooled down to room temperature and used as a measurement sample.
Regarding the measurement sample, the retardation value at the center of the measurement sample was measured using a birefringence meter (manufactured by Photonic Lattice, WPA-100) at a wavelength of 650 nm (this measurement value is referred to as anm). In addition, the thickness of the center of the measurement sample was measured (this measured value is referred to as bmm).
Using the measured values a and b, the δn value was calculated using the following formula (1).
δn=a×(1/b)× ^10-6 (1)
Using the δn value and the stress applied to the sample, _CR was calculated using the following formula (2).
C _R = δn/stress (2)

(Confirmation of presence or absence of aromatic ring in norbornene-based ring-opening copolymer hydrogenated product)
The polymer before hydrogenation and the hydrogenated polymer were analyzed by ¹ H-NMR. During the analysis, deuterated chloroform was used as a solvent. From the results of the analysis, the hydrogenation rate of non-aromatic unsaturated bonds and the hydrogenation rate of aromatic unsaturated bonds were determined. From these results, the presence or absence of an aromatic ring in the hydrogenated norbornene-based ring-opening copolymer was confirmed.

[Production Example 1: Production of polymer (1)]
(1-1) Production of ring-opening polymer A polymerization catalyst (1,3-dimesitylimidazolidin-2-ylidene) (tricyclohexylphosphine) benzylidene ruthenium dichloride 0 .05 parts by weight, 500 parts by weight of toluene, 50 parts by weight of 1,4-methano-1,4,4a,9a-tetrahydrofluorene (MTF) as a monomer, 20 parts by weight of tetracyclododecene (TCD), dicyclo 30 parts by weight of pentadiene (DCPD) and 0.75 parts by weight of 1-hexene as a chain transfer agent were added, and the entire mixture was stirred at 60°C for 2 hours to perform ring-opening polymerization. The resulting ring-opened polymer had a Mw of 3.3×10 ⁴ and a molecular weight distribution (Mw/Mn) of 2.3. Moreover, the conversion rate of monomer to polymer was 100%.

(1-2) Production of polymer (1) Next, 300 parts of the reaction solution containing the ring-opened polymer obtained in (1-1) was transferred to an autoclave equipped with a stirrer, and chlorohydridocarbonyl tris(triphenylphosphine) 0.0043 part of ruthenium (hereinafter abbreviated as "ruthenium catalyst") was added, and a hydrogenation reaction was carried out at a hydrogen pressure of 4.5 MPa and 160° C. for 4 hours.
After the hydrogenation reaction was completed, the obtained solution was poured into a large amount of isopropanol to precipitate the polymer (hydride). After the obtained polymer was collected by filtration, it was dried in a vacuum dryer (220° C., 1 Torr) for 6 hours to obtain a polymer (1). Polymer (1) had an Mw of 4.3×10 ⁴ and an Mw/Mn of 2.5. Further, the Tg of the polymer (1) was 128° C., and the _CR was 3900×10 ⁻¹² Pa ⁻¹ .
As a result of ¹ H-NMR analysis of the obtained polymer, it was found that in polymer (1), non-aromatic unsaturated bonds were selectively hydrogenated, while aromatic unsaturated bonds remained. It was confirmed that

[Production Example 2: Production of polymer (2)]
(2-1) Production of ring-opening polymer In (1-1) of Production Example 1, the amounts of monomers (MTF, TCD, and DCPD) added were 40 parts by weight of MTF, 35 parts by weight of TCD, and 25 parts by weight of DCPD. Except for the above, the same operation as in Production Example 1 (1-1) was performed to obtain a ring-opened polymer. The ring-opened polymer had an Mw of 3.1×10 ⁴ and a molecular weight distribution of 2.2. The conversion rate of monomer to polymer was 100%.

(2-2) Production of polymer (2) In (1-2) of Production Example 1, instead of 300 parts of the reaction solution containing the ring-opened polymer obtained in (1-1), (2-1 Polymer (2) was obtained by carrying out the same operation as in (1-2) except for using 300 parts of the reaction solution containing the ring-opened polymer obtained in ). Polymer (2) had an Mw of 4.0×10 ⁴ and an Mw/Mn of 2.4. Polymer (2) had a Tg of 136° C. and a _CR of 3200×10 ⁻¹² Pa ⁻¹ .
As a result of ¹ H-NMR analysis of the obtained polymer, it was found that in polymer (2), non-aromatic unsaturated bonds were selectively hydrogenated, while aromatic unsaturated bonds remained. It was confirmed that

[Production Example 3: Production of polymer (3)]
(3-1) Production of ring-opening polymer In (1-1) of Production Example 1, the amounts of monomers (MTF, TCD, and DCPD) added were 25 parts by weight of MTF, 35 parts by weight of TCD, and 40 parts by weight of DCPD. Except for the above, the same operation as in Production Example 1 (1-1) was performed to obtain a ring-opened polymer. The ring-opened polymer had an Mw of 3.2×10 ⁴ and a molecular weight distribution of 2.4. The conversion rate of monomer to polymer was 100%.

(3-2) Production of polymer (3) In (1-2) of Production Example 1, instead of 300 parts of the reaction solution containing the ring-opened polymer obtained in (1-1), (3-1 Polymer (3) was obtained by carrying out the same operation as in (1-2) except that 300 parts of the reaction solution containing the ring-opened polymer obtained in ) was used. Polymer (3) had an Mw of 4.2×10 ⁴ and an Mw/Mn of 2.6. Polymer (3) had a Tg of 128° C. and a _CR of 3000×10 ⁻¹² Pa ⁻¹ .
As a result of ¹ H-NMR analysis of the obtained polymer, it was found that in polymer (3), non-aromatic unsaturated bonds were selectively hydrogenated, while aromatic unsaturated bonds remained. It was confirmed that

[Production Example 4: Production of polymer (C1)]
(4-1) Production of ring-opening polymer In (1-1) of Production Example 1, the amounts of monomers (MTF, TCD, and DCPD) added were 22 parts by weight of MTF, 38 parts by weight of TCD, and 40 parts by weight of DCPD. Except for the above, the same operation was performed to obtain a ring-opened polymer. The ring-opened polymer had an Mw of 3.2×10 ⁴ and a molecular weight distribution of 2.3. The conversion rate of monomer to polymer was 100%.

(4-2) Production of polymer (C1) In (1-2) of Production Example 1, instead of 300 parts of the reaction solution containing the ring-opened polymer obtained in (1-1), (4-1 Polymer (C1) was obtained by carrying out the same operation as in (1-2) except that 300 parts of the reaction solution containing the ring-opened polymer obtained in ) was used. The Mw of the polymer (C1) was 4.1×10 ⁴ and the Mw/Mn was 2.5. The polymer (C1) had a Tg of 129° C. and a C _R of 2850×10 ⁻¹² Pa ⁻¹ .
As a result of ¹ H-NMR analysis of the obtained polymer, it was found that in polymer (C1), non-aromatic unsaturated bonds were selectively hydrogenated, while aromatic unsaturated bonds remained. It was confirmed that

[Production Example 5: Production of polymer (C2)]
(5-1) Production of ring-opening polymer In (1-1) of Production Example 1, the amounts of monomers (MTF, TCD, and DCPD) added were 25 parts by weight of MTF, 35 parts by weight of TCD, and 40 parts by weight of DCPD. Except for the above, the same operation as in Production Example 1 (1-1) was performed to obtain a ring-opened polymer. The ring-opened polymer had an Mw of 3.2×10 ⁴ and a molecular weight distribution of 2.4. The conversion rate of monomer to polymer was 100%.

(5-2) Production of polymer (C2) Next, 300 parts of the reaction solution containing the ring-opened polymer obtained in (5-1) was transferred to an autoclave equipped with a stirrer, and diatomaceous earth supported nickel catalyst (JGC Chemical Co., Ltd. Co., Ltd., product name "T8400RL", nickel loading rate 57%) was added thereto, and a hydrogenation reaction was carried out at a hydrogen pressure of 4.5 MPa and 160° C. for 4 hours.
After completion of the hydrogenation reaction, the resulting solution was filtered under pressure at a pressure of 0.25 MPa using Radiolite #500 as a filter bed (manufactured by Ishikawajima-Harima Heavy Industries, product name: Fundavac Filter) to remove the hydrogenation catalyst. A colorless and transparent solution was obtained. The resulting solution was poured into a large amount of isopropanol to precipitate the polymer. After the obtained polymer was collected by filtration, it was dried in a vacuum dryer (220° C., 1 Torr) for 6 hours to obtain a polymer (C2). The Mw of the polymer (C2) was 4.3×10 ⁴ and the Mw/Mn was 2.6. The polymer (C2) had a Tg of 136° C. and a _CR of 1900×10 ⁻¹² Pa ⁻¹ .
As a result of ¹ H-NMR analysis of the obtained polymer, it was found that both non-aromatic unsaturated bonds and aromatic unsaturated bonds were hydrogenated in polymer (C2). confirmed.

[Production Example 6: Production of polymer (C3)]
(6-1) Production of ring-opening polymer In (1-1) of Production Example 1, the amounts of monomers (MTF, TCD, and DCPD) added were 10 parts by weight of MTF, 40 parts by weight of TCD, and 50 parts by weight of DCPD. Except for the above, the same operation as in Production Example 1 (1-1) was performed to obtain a ring-opened polymer. The ring-opened polymer had an Mw of 3.2×10 ⁴ and a molecular weight distribution of 2.3. The conversion rate of monomer to polymer was 100%.

(6-2) Production of polymer (C3) Next, 300 parts of the reaction solution containing the ring-opened polymer obtained in (6-1) was transferred to an autoclave equipped with a stirrer, and diatomaceous earth supported nickel catalyst (JGC Chemical Co., Ltd. Co., Ltd., product name "T8400RL", nickel loading rate 57%) was added thereto, and a hydrogenation reaction was carried out at a hydrogen pressure of 4.5 MPa and 160° C. for 4 hours.
After completion of the hydrogenation reaction, the resulting solution was filtered under pressure at a pressure of 0.25 MPa using Radiolite #500 as a filter bed (manufactured by Ishikawajima-Harima Heavy Industries, product name: Fundavac Filter) to remove the hydrogenation catalyst. A colorless and transparent solution was obtained. The resulting solution was poured into a large amount of isopropanol to precipitate the polymer. After the obtained polymer was filtered, it was dried in a vacuum dryer (220° C., 1 Torr) for 6 hours to obtain a polymer (C3). The Mw of the polymer (C3) was 4.1×10 ⁴ and the Mw/Mn was 2.5. The polymer (C3) had a Tg of 128° C. and a C _R of 2200×10 ⁻¹² Pa ⁻¹ .
As a result of ¹ H-NMR analysis of the obtained polymer, it was found that in the polymer (C3), both non-aromatic unsaturated bonds and aromatic unsaturated bonds were hydrogenated. confirmed.

[Production Example 7: Production of polymer (C4)]
(7-1) Production of ring-opening polymer In (1-1) of Production Example 1, the amounts of monomers (MTF, TCD, and DCPD) added were 5 parts by weight of MTF, 5 parts by weight of TCD, and 90 parts by weight of DCPD. Except for the above, the same operation as in Production Example 1 (1-1) was performed to obtain a ring-opened polymer. The ring-opened polymer had an Mw of 3.3×10 ⁴ and a molecular weight distribution of 2.3. The conversion rate of monomer to polymer was 100%.

(7-2) Production of polymer (C4) Next, 300 parts of the reaction solution containing the ring-opened polymer obtained in (7-1) was transferred to an autoclave equipped with a stirrer, and diatomaceous earth supported nickel catalyst (JGC Chemical Co., Ltd. Co., Ltd., product name "T8400RL", nickel loading rate 57%) was added thereto, and a hydrogenation reaction was carried out at a hydrogen pressure of 4.5 MPa and 160° C. for 4 hours.
After completion of the hydrogenation reaction, the resulting solution was filtered under pressure at a pressure of 0.25 MPa using Radiolite #500 as a filter bed (manufactured by Ishikawajima-Harima Heavy Industries, product name: Fundavac Filter) to remove the hydrogenation catalyst. A colorless and transparent solution was obtained. The resulting solution was poured into a large amount of isopropanol to precipitate the polymer. After the obtained polymer was collected by filtration, it was dried in a vacuum dryer (220° C., 1 Torr) for 6 hours to obtain a polymer (C4). The Mw of the polymer (C4) was 3.9×10 ⁴ and the Mw/Mn was 2.7. The polymer (C4) had a Tg of 102° C. and a _CR of 3100×10 ⁻¹² Pa ⁻¹ .
As a result of ¹ H-NMR analysis of the obtained polymer, it was found that in the polymer (C4), both non-aromatic unsaturated bonds and aromatic unsaturated bonds were hydrogenated. confirmed.

[Production Example 8: Production of polymer (C5)]
(8-1) Production of ring-opening polymer In (1-1) of Production Example 1, 50 parts by weight of TCD and 8-methyltetracyclododecene (hereinafter referred to as MTD) were used as monomers instead of MTF, TCD and DCPD. A ring-opened polymer was obtained by carrying out the same operation as in (1-1) of Production Example 1, except that 50 parts by weight (sometimes abbreviated as ) was used. The ring-opened polymer had an Mw of 4.0×10 ⁴ and a molecular weight distribution of 2.0. The conversion rate of monomer to polymer was 100%.

(8-2) Production of polymer (C5) Next, 300 parts of the polymerization reaction solution obtained in (8-1) was transferred to an autoclave equipped with a stirrer, and diatomaceous earth supported nickel catalyst (manufactured by JGC Chemical Co., Ltd., product name: 3 parts of "T8400RL" with a nickel loading rate of 57%) were added thereto, and a hydrogenation reaction was carried out at a hydrogen pressure of 4.5 MPa and 160° C. for 4 hours.
After completion of the hydrogenation reaction, the resulting solution was filtered under pressure at a pressure of 0.25 MPa using Radiolite #500 as a filter bed (manufactured by Ishikawajima-Harima Heavy Industries, product name: Fundavac Filter) to remove the hydrogenation catalyst. A colorless and transparent solution was obtained. The resulting solution was poured into a large amount of isopropanol to precipitate the polymer. After the obtained polymer was collected by filtration, it was dried in a vacuum dryer (220° C., 1 Torr) for 6 hours to obtain a polymer. The Tg of the polymer was 158°C.
28 parts by weight of this polymer, 10 parts by weight of maleic anhydride, and 3 parts by weight of dicumyl peroxide were dissolved in 130 parts by weight of t-butylbenzene, and reacted at 140° C. for 6 hours. The reaction product solution was poured into methanol to solidify the reaction product. This coagulated product was dried in a vacuum dryer (220° C., 1 Torr) for 6 hours to obtain a hydrogenated maleic acid-modified ring-opening polymer (polymer (C5)). The Mw of the polymer (C5) was 5.6×10 ⁴ and the Mw/Mn was 2.5. The polymer (C5) had a Tg of 170° C., a _CR of 2000×10 ⁻¹² Pa ⁻¹ , and a maleic acid group content of 25 mol%.

[Evaluation method]
(Measurement of Rth, Re, d of stretched film and calculation of Rth/d)
The retardation Rth in the thickness direction and the retardation Re in the in-plane direction of the stretched films obtained in each of the examples and comparative examples were measured at a measurement wavelength of 550 nm using a retardation meter ("AXOSCAN" manufactured by AXOMETRICS). . The thickness d of the stretched films obtained in each of the Examples and Comparative Examples was measured using a snap gauge ID-C112BS (manufactured by Mitutoyo Co., Ltd.).
The measured Rth value was divided by the thickness d of the stretched film to calculate Rth/d, which was evaluated according to the following evaluation criteria, and the results are shown in Tables 1 and 2. In Tables 1 and 2, Rth/d is shown in the upper row, and the evaluation results are shown in parentheses in the lower row.
Good: 3.5×10 ^-3 or more Bad: Less than 3.5×10 ^-3

(Orientation angle accuracy)
The orientation angle θ of the stretched films obtained in each of the examples and comparative examples was measured using a polarizing microscope (manufactured by Olympus, polarizing microscope "BX51"), and the absolute value was calculated as the orientation angle. The orientation angle θ was measured at intervals of 50 mm in the width direction of the stretched film and at intervals of 10 m in the length direction. The standard deviation of these measurement results was calculated, and the orientation angle precision θσ was determined, and the results are shown in Tables 1 and 2. The smaller the orientation angle precision is, the smaller the variation in the orientation angle is, which is preferable.

(Delamination evaluation method)
<Method for measuring peel strength>
As an adherend, a resin film containing a norbornene polymer (Zeonor film, glass transition temperature 160° C., thickness 100 μm, manufactured by Nippon Zeon Co., Ltd., without any particular stretching treatment) was prepared. One side of the film to be measured (stretched films obtained in each of the examples and comparative examples) and one side of the adherend were subjected to corona treatment. An adhesive was applied to both the corona-treated surface of the film to be measured and the corona-treated surface of the adherend, and the surfaces to which the adhesive was applied were bonded together. At this time, UV adhesive CRB series (manufactured by Toyochem) was used as the adhesive. Thereafter, using an electrodeless UV irradiation device (manufactured by Heraeus) and using a D bulb as a lamp, UV irradiation was performed under conditions of a peak illuminance of 100 mW/cm ² and a cumulative light amount of 3000 mJ/cm ² to cure the adhesive. . Thereby, a sample film including a film to be measured and an adherend was obtained.

A 90 degree peel test was conducted on the obtained sample film. That is, the sample film was cut into a width of 15 mm, and the side of the film to be measured was attached to the surface of a slide glass using an adhesive. At this time, double-sided adhesive tape (manufactured by Nitto Denko Corporation, product number "CS9621") was used as the adhesive. The adherend is held between the tips of a high-performance digital force gauge ZP-5N (manufactured by Imada Corporation), and the adherend is pulled at a speed of 300 mm/min in the normal direction of the surface of the slide glass to determine the magnitude of the pulling force. The peel strength was measured as peel strength. Peel strength was evaluated using the following evaluation criteria, and the results are shown in Tables 1 and 2. In Tables 1 and 2, the measured values are listed in the upper row, and the evaluation results are listed in parentheses in the lower row.
Good: 1.0N/15mm or more Bad: Less than 1.0N/15mm

<Reference example: Evaluation of validity of peel strength measurement method>
An experiment was conducted to evaluate whether the measurement of peel strength by the above-mentioned measurement method can be said to reflect the evaluation of peel strength when the adherend is a polarizer.
A polarizing film and an adhesive were prepared by a method similar to that described in Example 1 of JP-A-2005-70140. Moreover, the stretched film obtained in Example 1 of the present application was prepared as a film to be measured. One side of the film to be measured was subjected to corona treatment, and this side was bonded to one surface of the polarizing film via an adhesive. A triacetyl cellulose film was bonded to the other surface of the polarizing film via an adhesive. Thereafter, the adhesive was cured by drying at 80° C. for 7 minutes to obtain a sample film. The obtained sample film was subjected to a 90 degree peel test similar to that in <Method for measuring peel strength> described above. As a result, peel strength values similar to those obtained in Example 1 of the present application were obtained. From this, it can be said that the measurement of peel strength by the measurement method described above reflects the evaluation of peel strength when the adherend is a polarizer.

(Rth change rate after 500 hours at 85°C)
A durability test was conducted at 85° C. for 500 hours for each stretched film of Examples and Comparative Examples, Rth of the stretched film before and after the test was measured, and the rate of change was calculated using the following formula, and evaluated using the following criteria. . The smaller the rate of change, the higher the heat resistance, which is preferable. In Tables 1 and 2, the rate of change is shown in the upper row, and the evaluation results are shown in parentheses in the lower row.
Rate of change (%) = (Rth before test - Rth after test) / Rth before test x 100
Good: Change rate is 3% or less Bad: Change rate is greater than 3%

(60℃, humidity 90%, Rth change rate after 500 hours)
The stretched films of the examples and comparative examples were subjected to a durability test at 60°C and 90% humidity for 500 hours, the Rth of the stretched films before and after the test was measured, and the rate of change was calculated using the following formula. Evaluation was made according to the criteria. The smaller the rate of change, the higher the heat resistance and moisture resistance, which is preferable. In Tables 1 and 2, the rate of change is shown in the upper row, and the evaluation results are shown in parentheses in the lower row.
Rate of change (%) = (Rth before test - Rth after test) / Rth before test x 100
Good: Change rate is 3% or less Bad: Change rate is greater than 3%

(Measurement of water absorption rate)
A test piece (size: 100 mm x 100 mm) is prepared by cutting a part of each of the stretched films of Examples and Comparative Examples, and the mass of the test piece is measured. Thereafter, this test piece is immersed in water at 23° C. for 24 hours, and the mass of the test piece after immersion is measured. Then, the ratio of the mass of the test piece increased by immersion to the mass of the test piece before immersion was calculated as water absorption rate (%). The smaller the water absorption rate, the better.

(Example 1)
(1-1) Production of pre-stretched film The polymer (1) produced in Production Example 1 was charged into a twin-screw extruder and molded into a strand-shaped body by hot melt extrusion molding. This molded body was cut into pieces using a strand cutter to obtain resin pellets containing the polymer (1).

After drying the resin pellets at 100°C for 5 hours, the pellets were fed to an extruder using a conventional method, melted at 250°C, and discharged from a die onto a cooling drum to obtain a pre-stretched film with a thickness of 110 μm. .

(1-2) Production of Stretched Film Next, the unstretched film was stretched 1.2 times in the longitudinal direction at 138° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.4 times in the transverse direction at a temperature of 138°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 320 nm, and thickness d of 65 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 1.

[Example 2]
(2-1) Production of film before stretching In (1-1) of Example 1, except that polymer (2) produced in Production Example 2 was used instead of polymer (1), The same operation as in (1-1) of 1 was performed to obtain a 118 μm thick unstretched film containing polymer (2).

(2-2) Production of Stretched Film Next, the unstretched film was stretched 1.25 times in the longitudinal direction at 146° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched by 1.45 times in the transverse direction at a temperature of 146°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 310 nm, and thickness d of 65 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 1.

[Example 3]
(3-1) Production of film before stretching In (1-1) of Example 1, except that polymer (3) produced in Production Example 3 was used instead of polymer (1), The same operation as in (1-1) of 1 was performed to obtain a 127 μm thick unstretched film containing polymer (3).

(3-2) Production of Stretched Film Next, the unstretched film was stretched 1.3 times in the longitudinal direction at 138° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.5 times in the transverse direction at a temperature of 138°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 300 nm, and thickness d of 65 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 1.

[Comparative example 1]
(C1-1) Production of film before stretching In (1-1) of Example 1, the polymer (C1) produced in Production Example 4 was used instead of polymer (1), and the molten resin was discharged. The same operation as in (1-1) of Example 1 was performed except that the amount was increased to obtain a 180 μm thick unstretched film containing the polymer (C1).

(C1-2) Production of Stretched Film Next, the unstretched film was stretched 1.4 times in the longitudinal direction at 139° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.6 times in the transverse direction at a temperature of 139°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 300 nm, and thickness of 80 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 1.

[Comparative example 2]
(C2-1) Production of pre-stretched film In (1-1) of Example 1, the polymer (C2) produced in Production Example 5 was used instead of the polymer (1), and the molten resin was discharged. The same operation as in Example 1 (1-1) was performed except that the amount was increased to obtain a pre-stretched film containing the polymer (C2) with a thickness of 198 μm.

(C2-2) Production of Stretched Film Next, the unstretched film was stretched 1.65 times in the longitudinal direction at 146° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.85 times in the transverse direction at a temperature of 146°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 250 nm, and thickness d of 65 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 1.

[Comparative example 3]
(C3-1) Production of pre-stretched film In (1-1) of Example 1, the polymer (C3) produced in Production Example 6 was used instead of the polymer (1), and the molten resin was discharged. Except for increasing the amount, the same operation as in Example 1 (1-1) was performed to obtain a 188 μm thick unstretched film containing the polymer (C3).

(C3-2) Production of Stretched Film Next, the unstretched film was stretched 1.6 times in the longitudinal direction at 138° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.8 times in the transverse direction at a temperature of 138°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 250 nm, and thickness d of 65 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 2.

[Comparative example 4]
(C4-1) Production of film before stretching In (1-1) of Example 1, except that the polymer (C4) produced in Production Example 7 was used instead of polymer (1), The same operation as in 1(1-1) was performed to obtain a 136 μm thick unstretched film containing the polymer (C4).

(C4-2) Production of Stretched Film Next, the unstretched film was stretched 1.35 times in the longitudinal direction at 112° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.55 times in the transverse direction at a temperature of 112°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 300 nm, and thickness of 65 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 2.

[Comparative example 5]
(C5-1) Production of film before stretching In (1-1) of Example 1, except that the polymer (C3) produced in Production Example 6 was used instead of the polymer (1), The same operation as in 1(1-1) was performed to obtain a 134 μm thick unstretched film containing the polymer (C3).

(C5-2) Production of Stretched Film Next, the unstretched film was stretched 1.2 times in the longitudinal direction at 138° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.4 times in the transverse direction at a temperature of 138°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 260 nm, and thickness of 80 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 2.

[Comparative example 6]
(C6-1) Production of pre-stretched film In (1-1) of Example 1, the polymer (C5) produced in Production Example 8 was used instead of the polymer (1), and the molten resin was discharged. The same operation as in Example 1 (1-1) was performed except that the amount was increased to obtain a 192 μm thick unstretched film containing the polymer (C5).

(C6-2) Production of Stretched Film Next, the unstretched film was stretched 1.62 times in the longitudinal direction at 180° C. (Tg+10° C.) using a longitudinal stretching machine using a float method between rolls. The longitudinally stretched film is further fed to a transverse stretching machine using a tenter method, and is stretched 1.82 times in the transverse direction at a temperature of 180°C (Tg + 10°C) while adjusting the take-up tension and tenter chain tension. The film was stretched to obtain a biaxially stretched film. The obtained biaxially stretched film had Re of 60 nm, Rth of 250 nm, and thickness of 65 μm. An evaluation test was conducted on the obtained biaxially stretched film, and the results are shown in Table 2.

The evaluation results of Examples and Comparative Examples are shown in the table below. In the table below, the meanings of abbreviations are as follows.
MRu: MTF in which non-aromatic unsaturated bonds are selectively hydrogenated and aromatic unsaturated bonds remain.
T: Hydrogenated TCD.
D: Hydrogenated DCPD.
M: Hydrogenated MTF (ie, MTF in which both non-aromatic unsaturated bonds and aromatic unsaturated bonds are hydrogenated).
Polar COP: cyclic olefin polymer having polar groups.
MD×TD: Stretching magnification in the longitudinal direction×Stretching magnification in the lateral direction.

[result]
As shown in Tables 1 and 2, in the stretched films of Examples that meet the requirements of the present invention, Rth/d was high despite the low stretching ratio, and the occurrence of delamination was suppressed. As a result, it was found that the films of Examples that meet the requirements of the present invention can provide viewing angle compensation films that have excellent retardation properties and high retardation in the thickness direction.

Claims (6)

An optical film made of thermoplastic norbornene resin,
The thermoplastic norbornene resin has a stress birefringence C _R of 2910×10 ⁻¹² Pa ⁻¹ to 3900×10 ⁻¹² Pa ⁻¹ and a glass transition temperature Tg of 125° C. or higher,
The stress birefringence C _R is determined by applying stress to a sheet sample made from the thermoplastic norbornene resin at +5°C, the glass transition temperature Tg of the thermoplastic norbornene resin, to obtain a measurement sample. From the retardation value a (nm) of the sample in light with a wavelength of 650 nm and the thickness b (mm) of the measurement sample, the following formula (1):
δn=a×(1/b)×10-6 ⁽ 1)
The δn value is calculated by the following formula (2) from the calculated δn value and the stress (Pa):
C _R = δn/stress (2)
This is the value calculated by
The ratio of the retardation Rth in the thickness direction to the thickness d of the optical film (Rth/d) is 3.5×10 ⁻³ or more and 8.0×10 ⁻³ or less ,
An optical film that is a stretched film. The optical film according to claim 1, having an in-plane retardation Re of 40 nm or more and 80 nm or less. The thermoplastic norbornene resin contains a polymer,
The optical film according to claim 1 or 2, wherein the polymer contains a norbornene monomer unit having an aromatic ring structure. The optical film according to claim 3, wherein the polymer contains 25% by weight or more of norbornene monomer units having the aromatic ring structure. The optical film according to any one of claims 1 to 4,
An optical laminate comprising: a polarizing plate provided on the optical film. A liquid crystal display device comprising the optical laminate according to claim 5.