Optical Film

Abstract

This optical film comprises a first resin layer formed of a first thermoplastic resin that contains a norbornene polymer and a light absorber, wherein: the norbornene polymer is selected from the group consisting of a polymer of a norbornene monomer composition and a hydride thereof; the norbornene monomer composition contains a specific monomer; the weight average molecular weight of the norbornene polymer is in a specific range; and the amount of the light absorber in the first thermoplastic resin is in a specific range.

Description

[Technical field]

[0001] The present invention relates to an optical film. [Background technology]

[0002] Conventionally, films formed from thermoplastic resins have been known. For example, Patent Document 1 describes a technique for forming an optical film from a cycloolefin resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-102310 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, optical films using cycloolefin resins are sometimes applied to deformable articles. Therefore, the optical films are required to have high resistance to deformation. Specifically, the optical films are required to have high tensile elongation at break and excellent bending resistance.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical film having a large tensile elongation at break and excellent bending resistance. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and as a result, have found that an optical film having a first resin layer formed of a first thermoplastic resin containing a norbornene-based polymer selected from the group consisting of polymers of specific norbornene-based monomer compositions and hydrogenated products thereof and having a specific weight-average molecular weight, and a light absorbent in a predetermined amount, has a large tensile elongation at break and excellent bending resistance, thereby completing the present invention. That is, the present invention includes the following.

[0007] [1] A first resin layer is formed of a first thermoplastic resin containing a norbornene-based polymer and a light absorbing agent, the norbornene-based polymer is selected from the group consisting of polymers of norbornene-based monomer compositions and hydrogenated products thereof, The norbornene-based monomer composition contains 50% by weight or more of one or more monomers selected from the group consisting of a monomer represented by the following formula (T) and a monomer represented by the following formula (D), The norbornene polymer has a weight average molecular weight of 38,000 or more and 100,000 or less, An optical film, wherein the amount of the light absorbing agent in the first thermoplastic resin is 2% by weight to 30% by weight. [ka] (In formula (T), nt1 and nt2 each independently represent 1 or 2; If nt1 is 1, then R t1 represents a divalent hydrocarbon group, If nt1 is 2, then R t1 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nt2 is 1, then R t2 represents a divalent hydrocarbon group, If nt2 is 2, then R t2 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group; In formula (D), nd1, nd2 and nd3 each independently represent 1 or 2; If nd1 is 1, R d1 represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, If nd1 is 2, R d1 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nd2 is 1, R d2represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, If nd2 is 2, R d2 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nd3 is 1, R d3 represents a divalent hydrocarbon group, If nd3 is 2, R d3 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. [2] The optical film according to [1], wherein the norbornene-based monomer composition contains 1% by weight to 15% by weight of a monomer represented by the following formula (N): [ka] (In formula (N), nn1 and nn2 each independently represent 1 or 2; If nn1 is 1, then R n1 represents a divalent hydrocarbon group, If nn1 is 2, then R n1 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nn2 is 1, then R n2 represents a divalent hydrocarbon group, If nn2 is 2, then R n2 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. [3] The optical film according to [1] or [2], wherein the light absorbent includes at least one selected from the group consisting of an ultraviolet absorbent and an infrared absorbent. [4] The optical film according to any one of [1] to [3], wherein the molecular weight of the light absorbent is 800 or less. [5] The optical film according to any one of [1] to [4], wherein the light absorber includes at least one selected from the group consisting of triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers. [6] The optical film according to any one of [1] to [5], wherein the light absorbent includes a pentaerythritol-based infrared absorbent. [7] The optical film according to any one of [1] to [6], comprising, in this order, a second resin layer formed of a second thermoplastic resin, the first resin layer, and a third resin layer formed of a third thermoplastic resin. Effect of the Invention

[0008] According to the present invention, it is possible to provide an optical film having a large tensile elongation at break and excellent bending resistance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view that illustrates an example of an optical film according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates a schematic diagram of another example of an optical film according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention will be described in detail below with reference to the embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be modified and implemented as desired without departing from the scope of the claims of the present invention and the scope of equivalents thereto.

[0011] In the following description, a "long" film refers to a film having a length of 5 times or more its width, preferably 10 times or more its width, specifically a film having a length long enough to be wound into a roll for storage or transportation. 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.

[0012] In the structural formulae shown in the following description, the following line segments represented by a combination of parallel solid and dashed lines represent either a single bond or a double bond, unless otherwise specified.

[0013] [ka]

[0014] [1. Overview of optical films] The optical film according to one embodiment of the present invention includes a first resin layer formed of a first thermoplastic resin. The first thermoplastic resin contained in the first resin layer includes one or more norbornene polymers selected from the group consisting of polymers of norbornene monomer compositions and their hydrogenated products, and a light absorber. The term "norbornene monomer composition" refers to a general term for monomers as raw materials for norbornene polymers. The norbornene monomer composition includes not only materials containing two or more types of monomers, but also materials consisting of a single monomer. Thus, the norbornene polymer may generally have a structure formed by polymerization of the norbornene monomer composition, or a structure in which the carbon-carbon unsaturated bond of the structure is hydrogenated.

[0015] The norbornene-based monomer composition contains at least one monomer selected from the group consisting of a monomer represented by formula (T) and a monomer represented by the following formula (D) in a specific ratio.

[0016] [ka] (In formula (T), nt1 and nt2 each independently represent 1 or 2; If nt1 is 1, then R t1 represents a divalent hydrocarbon group, If nt1 is 2, then R t1 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nt2 is 1, then R t2 represents a divalent hydrocarbon group, If nt2 is 2, then R t2 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group; In formula (D), nd1, nd2 and nd3 each independently represent 1 or 2; If nd1 is 1, R d1 represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, If nd1 is 2, R d1 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nd2 is 1, R d2 represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, If nd2 is 2, R d2 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nd3 is 1, R d3 represents a divalent hydrocarbon group, If nd3 is 2, R d3 each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group.

[0017] The norbornene-based polymer has a weight average molecular weight Mw in a specific range. Furthermore, the amount of the light absorbing agent in the first thermoplastic resin is in a specific range.

[0018] Fig. 1 is a cross-sectional view showing an example of an optical film according to an embodiment of the present invention. Fig. 2 is a cross-sectional view showing another example of an optical film according to an embodiment of the present invention. For example, as shown in Fig. 1, the optical film 100 may be a film having a single layer structure including only a first resin layer 110. For example, as shown in Fig. 2, the optical film 200 may be a film having a multilayer structure including any layer such as a second resin layer 220 and a third resin layer 230 in combination with the first resin layer 110.

[0019] The optical film has the effects of having a large tensile elongation at break and excellent bending resistance.

[0020] In the following description, the monomer represented by formula (T) may be referred to as a "TCD monomer", and the monomer represented by formula (D) may be referred to as a "DCP monomer".

[0021] [2. Norbornene-based polymers] The norbornene polymer is selected from the group consisting of polymers of norbornene monomer compositions and their hydrogenated products. The norbornene monomer composition contains one or more monomers selected from the group consisting of TCD monomers and DCP monomers. If necessary, the norbornene monomer composition may contain any monomer other than the TCD monomer and the DCP monomer.

[0022] The TCD monomer is represented by formula (T). Under appropriate conditions, this TCD monomer can undergo polymerization reactions such as ring-opening polymerization and addition polymerization. In addition, the polymer obtained by the polymerization reaction can be hydrogenated to convert the carbon-carbon unsaturated bond into a carbon-carbon single bond. For example, when the TCD monomer represented by formula (T-1) described later undergoes ring-opening polymerization and hydrogenation, a polymer containing a repeating unit represented by formula (TA) can be obtained.

[0023] [ka]

[0024] In formula (T), nt1 and nt2 each independently represent 1 or 2. When nt1 is 1, R t1 The bond of may represent a double bond. Also, when nt1 is 2, R t1 The bond of may represent a single bond. Furthermore, when nt2 is 1, R t2 The bond of may represent a double bond. Also, when nt2 is 2, R t2may represent a single bond. Thus, formula (T) includes structures represented by the following formulae (T-1) to (T-4). In detail, a structure in which nt1 is 1 may be represented by formulae (T-2) and (T-4), and a structure in which nt1 is 2 may be represented by formulae (T-1) and (T-3). A structure in which nt2 is 1 may be represented by formulae (T-2) and (T-3), and a structure in which nt2 is 2 may be represented by formulae (T-1) and (T-4).

[0025] [ka]

[0026] If nt1 is 1, then R t1 represents a divalent hydrocarbon group. From the viewpoint of obtaining an optical film that is particularly excellent in tensile elongation at break and bending resistance, the divalent hydrocarbon group is preferably an aliphatic hydrocarbon group, and more preferably a saturated aliphatic hydrocarbon group. The number of carbon atoms in this divalent hydrocarbon group is usually 1 or more and usually 6 or less, preferably 4 or less, more preferably 2 or less. When the number of carbon atoms is within the above range, an optical film that is particularly excellent in tensile elongation at break and bending resistance can be obtained. Examples of the divalent hydrocarbon group include a methylidene group and an ethylidene group.

[0027] If nt1 is 2, then R t1 R each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. t1 The number of carbon atoms in the alkyl group as the alkyloxycarbonyl group is usually 1 or more, and usually 6 or less, preferably 4 or less, and more preferably 2 or less. The number of carbon atoms in the alkyl group contained in the alkyloxycarbonyl group is usually 1 or more, and usually 6 or less, preferably 4 or less, and more preferably 2 or less. When the number of carbon atoms is within the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained. Examples of the alkyl group include a methyl group and an ethyl group. Among them, from the viewpoint of effectively improving the tensile elongation at break, R t1 is preferably a hydrogen atom. When nt1 is 2, the TCD monomer has multiple R t1These R t1 may be the same or different.

[0028] If nt2 is 1, then R t2 R represents a divalent hydrocarbon group. t2 The divalent hydrocarbon group represented by R t1 The divalent hydrocarbon group represented by R may be the same as that represented by R t1 The same advantages as described for

[0029] If nt2 is 2, then R t2 R each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. t2 The alkyl group and alkyloxycarbonyl group represented by R t1 The same range of alkyl groups and alkyloxycarbonyl groups represented by R can be used. t1 In particular, from the viewpoint of effectively improving the tensile elongation at break, t2 is preferably a hydrogen atom. When nt2 is 2, the TCD monomer has multiple R t2 These R t2 may be the same or different.

[0030] Examples of TCD monomers include the following monomers:

[0031] [ka]

[0032] The TCD monomer may be used alone or in combination of two or more kinds in any ratio.

[0033] The amount of the TCD monomer is usually set so that the amount of one or more monomers selected from the group consisting of TCD monomers and DCP monomers relative to the total amount of the norbornene monomer composition (100% by weight) falls within a specific range. Specifically, the amount of one or more monomers selected from the group consisting of TCD monomers and DCP monomers is usually 50% by weight or more, more preferably 60% by weight or more, particularly preferably 70% by weight or more, and usually 100% by weight or less, preferably 99% by weight or less, relative to the total amount of the norbornene monomer composition (100% by weight). When the amount of one or more monomers selected from the group consisting of TCD monomers and DCP monomers is within the above range, an optical film having excellent tensile elongation at break and bending resistance can be obtained.

[0034] The amount of the TCD monomer is preferably 20% by weight or more, more preferably 22% by weight or more, particularly preferably 25% by weight or more, and is preferably 99% by weight or less, more preferably 97% by weight or less, particularly preferably 95% by weight or less, relative to 100% by weight of the total amount of the norbornene monomer composition. When the amount of the TCD monomer is within the above range, an optical film having excellent tensile elongation at break while having high heat resistance can be obtained.

[0035] The DCP monomer is represented by formula (D). Under appropriate conditions, this DCP monomer can undergo polymerization reactions such as ring-opening polymerization and addition polymerization. Furthermore, the polymer obtained by the polymerization reaction can be hydrogenated to convert the carbon-carbon unsaturated bond into a carbon-carbon single bond. For example, when a DCP monomer represented by formula (D-1) described later undergoes ring-opening polymerization and hydrogenation, a polymer containing a repeating unit represented by formula (DA) can be obtained.

[0036] [ka]

[0037] In formula (D), nd1, nd2 and nd3 each independently represent 1 or 2. When nd1 is 1, R d1The bond of may represent a single bond or a double bond. When nd1 is 2, R d1 The bond of may represent a single bond. Furthermore, when nd2 is 1, R d2 The bond of may represent a single bond or a double bond. When nd2 is 2, R d2 The bond of may represent a single bond. d1 The carbon atom to which R is bonded d2 When the bond between the carbon atom to which is bonded (i.e., the bond represented by a combination of a solid line and a dashed line included in the five-membered ring) is a double bond, nd1 is 1, R d1 The bond of is a single bond, nd2 is 1, R d2 The bond of can represent a single bond. d1 The carbon atom to which R is bonded d2 When the bond between the carbon atom to which R is bonded is a single bond, nd1 is 1 or 2, R d1 The bond of is a single bond or a double bond, nd2 is 1 or 2, R d2 The bond of may represent a single bond or a double bond. Furthermore, when nd3 is 1, R d3 The bond of may represent a double bond. Also, when nd3 is 2, R d3 may represent a single bond. Therefore, formula (D) includes structures represented by the following formulas (D-1) to (D-10). In detail, the structure in which nd1 is 1 may be represented by formula (D-1), (D-2), (D-4), (D-7), (D-8) and (D-10), and the structure in which nd1 is 2 may be represented by formula (D-3), (D-5), (D-6) and (D-9). The structure in which nd2 is 1 may be represented by formula (D-1), (D-2), (D-5), (D-7), (D-9) and (D-10), and the structure in which nd2 is 2 may be represented by formula (D-3), (D-4), (D-6) and (D-8). Furthermore, the structure in which nd3 is 1 can be represented by formula (D-2), formula (D-6), formula (D-8), formula (D-9) and formula (D-10), and the structure in which nd3 is 2 can be represented by formula (D-1), formula (D-3), formula (D-4), formula (D-5) and formula (D-7).

[0038] [ka]

[0039] If nd1 is 1, R d1 represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group. When nd1 is 2, R d1 R each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. d1 The number of carbon atoms of the alkyl group as the alkyloxycarbonyl group is usually 1 or more, and usually 6 or less, preferably 4 or less, more preferably 2 or less. The number of carbon atoms of the alkyl group contained in the alkyloxycarbonyl group is usually 1 or more, and usually 6 or less, preferably 4 or less, more preferably 2 or less. When the number of carbon atoms is within the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained. Examples of the alkyl group include a methyl group and an ethyl group. In addition, as the divalent hydrocarbon group, from the viewpoint of obtaining an optical film having particularly excellent tensile elongation at break and bending resistance, an aliphatic hydrocarbon group is preferable, and a saturated aliphatic hydrocarbon group is more preferable. The number of carbon atoms of this divalent hydrocarbon group is usually 1 or more, and usually 6 or less, preferably 4 or less, more preferably 2 or less. When the number of carbon atoms is within the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained. Examples of the divalent hydrocarbon group include a methylidene group and an ethylidene group. Among them, from the viewpoint of effectively improving the tensile elongation at break, R d1 is preferably a hydrogen atom. When nd1 is 2, the DCP monomer has a plurality of R d1 These R d1 may be the same or different.

[0040] If nd2 is 1, R d2 represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group. When nd2 is 2, R d2 R each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. d2 The alkyl group, alkyloxycarbonyl group, and divalent hydrocarbon group represented by Rd1 The same range of alkyl groups, alkyloxycarbonyl groups, and divalent hydrocarbon groups represented by R can be used. d1 In particular, from the viewpoint of effectively improving the tensile elongation at break, d2 is preferably a hydrogen atom. When nd2 is 2, the DCP monomer has a plurality of R d2 These R d2 may be the same or different.

[0041] If nd3 is 1, R d3 R represents a divalent hydrocarbon group. d3 The divalent hydrocarbon group represented by R d1 The divalent hydrocarbon group represented by R may be the same as that represented by R d1 The same advantages as described for

[0042] If nd3 is 2, R d3 R each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. d3 The alkyl group and alkyloxycarbonyl group represented by R d1 The same range of alkyl groups and alkyloxycarbonyl groups represented by R can be used. d1 In particular, from the viewpoint of effectively improving the tensile elongation at break, d3 is preferably a hydrogen atom. When nd3 is 2, the DCP monomer has a plurality of R d3 These R d3 may be the same or different.

[0043] Examples of DCP monomers include the following monomers:

[0044] [ka]

[0045] The DCP monomer may be used alone or in combination of two or more kinds in any ratio.

[0046] The amount of the DCP monomer is preferably 65% ​​by weight or more, more preferably 66% by weight or more, particularly preferably 67% by weight or more, and is preferably 80% by weight or less, more preferably 77% by weight or less, particularly preferably 75% by weight or less, based on 100% by weight of the total amount of the norbornene monomer composition. When the amount of the DCP monomer is within the above range, an optical film having particularly excellent tensile elongation at break can be obtained.

[0047] The amount of the DCP monomer is preferably equal to or greater than the amount of the TCD monomer. More specifically, the amount of the DCP monomer relative to 100 parts by weight of the TCD monomer is preferably equal to or greater than 100 parts by weight, more preferably equal to or greater than 150 parts by weight, particularly preferably equal to or greater than 200 parts by weight, and is preferably equal to or less than 500 parts by weight, more preferably equal to or less than 450 parts by weight, particularly preferably equal to or less than 400 parts by weight. When the amount of the DCP monomer is within the above range, an optical film having particularly excellent tensile elongation at break can be obtained.

[0048] The norbornene-based monomer composition may contain, in addition to the TCD-based monomer and the DCP-based monomer, any monomer polymerizable with the TCD-based monomer or the DCP-based monomer, so long as the effect of the present invention is not significantly impaired. The any monomer may be used alone or in combination of two or more kinds in any ratio.

[0049] A preferred optional monomer is, for example, a monomer represented by the following formula (N). In the following description, the monomer represented by formula (N) may be referred to as an "NB-based monomer". The NB-based monomer can undergo polymerization reactions such as ring-opening polymerization and addition polymerization under appropriate conditions. In addition, the polymer obtained by the polymerization reaction can be hydrogenated to convert the carbon-carbon unsaturated bond into a carbon-carbon single bond. For example, when the NB-based monomer represented by formula (N-1) described later undergoes ring-opening polymerization and hydrogenation, a polymer containing a repeating unit represented by formula (NA) can be obtained. When the norbornene-based monomer composition contains the NB-based monomer, an optical film having particularly excellent tensile elongation at break can be obtained.

[0050] [ka]

[0051] In formula (N), nn1 and nn2 each independently represent 1 or 2. When nn1 is 1, R n1 The bond of may represent a double bond. Also, when nn1 is 2, R n1 The bond of may represent a single bond. Furthermore, when nn2 is 1, R n2 The bond of may represent a double bond. Also, when nn2 is 2, R n2 may represent a single bond. Therefore, formula (N) includes structures represented by the following formulae (N-1) to (N-4). In detail, a structure in which nn1 is 1 is represented by formulae (N-2) and (N-4), and a structure in which nn1 is 2 is represented by formulae (N-1) and (N-3). A structure in which nn2 is 1 is represented by formulae (N-2) and (N-3), and a structure in which nn2 is 2 can be represented by formulae (N-1) and (N-4).

[0052] [ka]

[0053] If nn1 is 1, then R n1represents a divalent hydrocarbon group. From the viewpoint of obtaining an optical film that is particularly excellent in tensile elongation at break and bending resistance, the divalent hydrocarbon group is preferably an aliphatic hydrocarbon group, and more preferably a saturated aliphatic hydrocarbon group. The number of carbon atoms in this divalent hydrocarbon group is usually 1 or more and usually 6 or less, preferably 4 or less, more preferably 2 or less. When the number of carbon atoms is within the above range, an optical film that is particularly excellent in tensile elongation at break and bending resistance can be obtained. Examples of the divalent hydrocarbon group include a methylidene group and an ethylidene group.

[0054] If nn1 is 2, then R n1 R each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. n1 The number of carbon atoms in the alkyl group as the alkyloxycarbonyl group is usually 1 or more, and usually 6 or less, preferably 4 or less, and more preferably 2 or less. The number of carbon atoms in the alkyl group contained in the alkyloxycarbonyl group is usually 1 or more, and usually 6 or less, preferably 4 or less, and more preferably 2 or less. When the number of carbon atoms is within the above range, an optical film having particularly excellent tensile elongation at break can be obtained. Examples of the alkyl group include a methyl group and an ethyl group. Among them, from the viewpoint of effectively improving the tensile elongation at break, R n1 is preferably a hydrogen atom. When nn1 is 2, the NB monomer has a plurality of R n1 These R n1 may be the same or different.

[0055] If nn2 is 1, then R n2 R represents a divalent hydrocarbon group. n2 The divalent hydrocarbon group represented by R n1 The divalent hydrocarbon group represented by R may be the same as that represented by R n1 The same advantages as described for

[0056] If nn2 is 2, then R n2 R each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group. n2The alkyl group and alkyloxycarbonyl group represented by R n1 The same range of alkyl groups and alkyloxycarbonyl groups represented by R can be used. n1 In particular, from the viewpoint of effectively improving the tensile elongation at break, n2 is preferably a hydrogen atom. When nn2 is 2, the NB monomer has a plurality of R n2 These R n2 may be the same or different.

[0057] Examples of NB-based monomers include the following monomers:

[0058] [ka]

[0059] The NB monomer may be used alone or in combination of two or more kinds in any ratio.

[0060] The amount of the NB monomer is usually 0% by weight or more, preferably 1% by weight or more, and usually 15% by weight or less, preferably 10% by weight or less, more preferably 8% by weight or less, based on 100% by weight of the total amount of the norbornene monomer composition. When the amount of the NB monomer is within the above range, an optical film having particularly excellent tensile elongation at break can be obtained.

[0061] The amount of the NB monomer is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, particularly preferably 1.0 part by weight or more, and is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, particularly preferably 10 parts by weight or less, relative to 100 parts by weight of the amount of one or more monomers selected from the group consisting of TCD monomers and DCP monomers. When the amount of the NB monomer is within the above range, an optical film having particularly excellent tensile elongation at break can be obtained.

[0062] The norbornene-based monomer composition may contain monomers other than the TCD-based monomer, the DCP-based monomer, and the NB-based monomer, as long as the effects of the present invention are not significantly impaired. The amount of the monomers other than the TCD-based monomer, the DCP-based monomer, and the NB-based monomer is preferably 0% by weight to 5.0% by weight, more preferably 0% by weight to 3.0% by weight, and particularly preferably 0% by weight to 1.0% by weight, based on 100% by weight of the total amount of the norbornene-based monomer composition. In particular, it is preferable that the norbornene-based monomer composition does not contain monomers other than the TCD-based monomer, the DCP-based monomer, and the NB-based monomer.

[0063] The norbornene-based polymer is selected from the group consisting of the polymer of the norbornene-based monomer composition and its hydrogenated product. Examples of the polymer of the norbornene-based monomer composition include a ring-opening polymer of the norbornene-based monomer composition and an addition polymer of the norbornene-based monomer composition. The hydrogenated product may be a polymer in which the non-aromatic carbon-carbon unsaturated bond in the polymer is hydrogenated, a polymer in which the aromatic carbon-carbon unsaturated bond in the polymer is hydrogenated, or a polymer in which both the non-aromatic carbon-carbon unsaturated bond and the aromatic carbon-carbon unsaturated bond in the polymer are hydrogenated. In particular, a hydrogenated product of a ring-opening polymer of a norbornene-based monomer composition is preferred, and a hydrogenated product in which both the non-aromatic carbon-carbon unsaturated bond and the aromatic carbon-carbon unsaturated bond in the ring-opening polymer of a norbornene-based monomer composition are hydrogenated is more preferred. By using such a norbornene-based polymer, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained. Furthermore, it is usually possible to improve the mechanical strength, moisture resistance, heat resistance, and other properties of the optical film.

[0064] The hydrogenation rate of the hydrogenated product may be any value within a range that does not significantly impair the effects of the present invention. From the viewpoint of improving the transparency and heat resistance of the optical film, the hydrogenation rate of the non-aromatic carbon-carbon unsaturated bonds is preferably 90% to 100%, more preferably 97% to 100%, and particularly preferably 99% to 100%. From the viewpoint of improving the transparency and heat resistance of the optical film, the hydrogenation rate of the aromatic carbon-carbon unsaturated bonds is preferably 90% to 100%, more preferably 93% to 100%, and particularly preferably 95% to 100%. The hydrogenation rate is 1 It can be measured by H-NMR.

[0065] The weight average molecular weight Mw of norbornene polymers is usually 3.8 × 10 4 More than 3.9×10 4 More preferably, 4.0×10 4 More than or equal to 10.0×10 4 Less than or equal to 8.0×10 4 Less than or equal to 6.0×10 4 By using a norbornene-based polymer having a weight-average molecular weight Mw within the above range, an optical film excellent in tensile elongation at break and bending resistance can be obtained.

[0066] The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the norbornene polymer is preferably 3.0 or less, more preferably 2.8 or less, and preferably 1.0 or more, more preferably 1.2 or more. By using a norbornene polymer having a molecular weight distribution Mw / Mn in the above range, an optical film having excellent heat resistance can be obtained.

[0067] The weight average molecular weight Mw and number average molecular weight Mn of the polymer can be measured in terms of polyisoprene by gel permeation chromatography using cyclohexane as the eluent. If the polymer is not soluble in cyclohexane, gel permeation chromatography can be performed using tetrahydrofuran (THF) as the eluent. When the eluent is THF, the weight average molecular weight Mw and number average molecular weight Mn of the polymer can be measured in terms of polystyrene.

[0068] The norbornene-based polymer may be used alone or in combination of two or more kinds in any ratio.

[0069] The norbornene polymer can be produced, for example, by a production method including polymerizing a norbornene monomer composition in the presence of a suitable catalyst. When a hydrogenated product is produced as the norbornene polymer, the production method of the norbornene polymer may include, after the polymerization, contacting the resulting polymer with hydrogen in the presence of a hydrogenation catalyst including a transition metal such as nickel, palladium, or ruthenium to hydrogenate the carbon-carbon unsaturated bonds.

[0070] [3. Light absorbers] The light absorbent refers to a compound capable of absorbing light. The light that can be absorbed by the light absorbent includes not only visible light, but also ultraviolet light and infrared light. Ultraviolet light refers to light having a wavelength of 1 nm or more and less than 400 nm. Visible light refers to light having a wavelength of 400 nm or more and 800 nm or less. Infrared light refers to light having a wavelength of more than 800 nm. The light absorbent may be an inorganic compound or an organic compound, but from the viewpoint of increasing the transparency of the optical film, an organic compound is preferable.

[0071] From the viewpoint of suppressing coloring of the optical film, it is preferable to use one or more compounds selected from the group consisting of ultraviolet absorbers and infrared absorbers as the light absorber.Ultraviolet absorbers and infrared absorbers usually have little ability to absorb visible light or no ability to absorb visible light.Therefore, when one or more compounds selected from the group consisting of ultraviolet absorbers and infrared absorbers are used as the light absorber, an optical film with little absorption of visible light can be obtained, so that coloring of the optical film can be suppressed and transparency can be increased.

[0072] Examples of the ultraviolet absorber include triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, acrylonitrile-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, azomethine-based ultraviolet absorbers, indole-based ultraviolet absorbers, naphthalimide-based ultraviolet absorbers, and phthalocyanine-based ultraviolet absorbers.

[0073] As the triazine-based ultraviolet absorbent, for example, a compound having a 1,3,5-triazine ring is preferable.Specific examples of the triazine-based ultraviolet absorbent include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine, etc.Commercially available products of such triazine-based ultraviolet absorbents include, for example, "Tinuvin 1577ED" manufactured by BASF, "LA-F70" and "LA-46" manufactured by ADEKA, etc.

[0074] Examples of benzotriazole-based ultraviolet absorbers include 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazol-2-yl)-p-cresol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazol-2-yl-4,6-di-tert-butylphenol, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol, 3-(2H-benzotriazol-2-yl)-4,6-di-tert-butylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimidylmethyl)phenol, reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300, 2-(2H-benzotriazol-2-yl)-6-(straight-chain and side-chain dodecyl)-4-methylphenol, etc. Examples of commercially available triazole-based ultraviolet absorbers include "ADEKA STAB LA-31" manufactured by ADEKA Corporation and "TINUVIN 328" manufactured by Ciba Specialty Chemicals Corporation.

[0075] Examples of azomethine ultraviolet absorbents include the materials described in Japanese Patent No. 3366697, and examples of commercially available products include "BONASORB UA-3701" manufactured by Orient Chemical Co., Ltd.

[0076] Examples of indole-based ultraviolet absorbents include the materials described in Japanese Patent No. 2846091, and commercially available products include "BONASORB UA-3911" and "BONASORB UA-3912" manufactured by Orient Chemical Co., Ltd.

[0077] Examples of phthalocyanine-based ultraviolet absorbents include the materials described in Japanese Patent No. 4403257 and Japanese Patent No. 3286905, and examples of commercially available products include "FDB001" and "FDB002" manufactured by Yamada Chemical Industry Co., Ltd.

[0078] Among the above-mentioned ultraviolet absorbents, from the viewpoint of obtaining an optical film that is particularly excellent in tensile elongation at break and bending resistance, ultraviolet absorbents selected from the group consisting of triazine-based ultraviolet absorbents and benzotriazole-based ultraviolet absorbents are preferred.

[0079] Examples of the infrared absorbing agent include pentaerythritol-based infrared absorbing agents and phthalocyanine-based infrared absorbing agents.

[0080] Examples of pentaerythritol-based infrared absorbents include pentaerythritol tetra(2-ethylhexanoate), dipentaerythritol, and the like.

[0081] Examples of the phthalocyanine infrared absorbing agent include "FDN001" and "FDN008" manufactured by Yamada Chemical Industry Co., Ltd.

[0082] Among the above-mentioned infrared absorbing agents, pentaerythritol-based infrared absorbing agents are preferred from the viewpoint of obtaining an optical film that is particularly excellent in tensile elongation at break and bending resistance.

[0083] The molecular weight of the light absorbent is preferably 800 or less, more preferably 750 or less, and particularly preferably 700 or less. By using a light absorbent having a molecular weight in such a range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained. The lower limit of the molecular weight of the light absorbent is preferably 350 or more, more preferably 380 or more, and particularly preferably 400 or more, from the viewpoint of suppressing bleeding out of the light absorbent.

[0084] The light absorbing agent may be used alone or in combination of two or more kinds in any ratio.

[0085] [4. First resin layer] The first resin layer is made of a first thermoplastic resin containing a norbornene-based polymer and a light absorbing agent. By including the first resin layer made of the first thermoplastic resin, the optical film according to the present embodiment has excellent tensile elongation at break and bending resistance.

[0086] The amount of the norbornene-based polymer contained in the first thermoplastic resin is arbitrary within a range that allows an optical film having excellent tensile elongation at break and bending resistance to be obtained. Specifically, the amount of the norbornene-based polymer contained in the first thermoplastic resin is preferably 70% by weight or more, more preferably 90% by weight or more, particularly preferably 95% by weight or more, and preferably 98% by weight or less, based on 100% by weight of the first thermoplastic resin.

[0087] The amount of the light absorbing agent contained in the first thermoplastic resin is preferably 2% by weight or more, more preferably 3% by weight or more, particularly preferably 4% by weight or more, and is preferably 30% by weight or less, more preferably 20% by weight or less, particularly preferably 15% by weight or less, based on 100% by weight of the first thermoplastic resin. By using a first thermoplastic resin containing such an amount of light absorbing agent, an optical film having excellent tensile elongation at break and bending resistance can be obtained.

[0088] The amount of the light absorbing agent contained in the first thermoplastic resin is preferably 1.5% by weight or more, more preferably 2% by weight or more, even more preferably 3% by weight or more, and is preferably 40% by weight or less, more preferably 30% by weight or less, even more preferably 20% by weight or less, and particularly preferably 15% by weight or less, based on 100 parts by weight of the norbornene polymer contained in the first thermoplastic resin. When the amount of the light absorbing agent is within the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained.

[0089] The first thermoplastic resin may contain optional components other than the norbornene polymer and the light absorber. Examples of the optional components include antioxidants, heat stabilizers, light stabilizers, antistatic agents, dispersants, chlorine scavengers, flame retardants, crystallization nucleating agents, reinforcing agents, antiblocking agents, antifogging agents, mold release agents, pigments, organic or inorganic fillers, neutralizing agents, lubricants, decomposers, metal deactivators, antifouling agents, and antibacterial agents. The optional components may be used alone or in combination of two or more at any ratio.

[0090] The glass transition temperature Tg of the first thermoplastic resin is preferably 100°C or higher, more preferably 101°C or higher, particularly preferably 102°C or higher, and is preferably less than 135°C, more preferably less than 130°C, particularly preferably less than 125°C. When the glass transition temperature Tg of the first thermoplastic resin is equal to or higher than the lower limit of the above range, relaxation of the orientation of the norbornene-based polymer in a high-temperature environment can be suppressed. Thus, the change in retardation of the optical film in a high-temperature environment can be suppressed. On the other hand, when the glass transition temperature Tg of the first thermoplastic resin is lower than the upper limit of the above range, the retardation of the optical film can be easily increased.

[0091] The glass transition temperature Tg of a thermoplastic resin can be measured using a differential scanning calorimeter in accordance with JIS K 6911 at a temperature rise rate of 10° C. / min.

[0092] The glass transition temperature Tg of the first thermoplastic resin can be adjusted by, for example, the types and quantitative ratio of monomers contained in a norbornene-based monomer composition used as a raw material for the norbornene-based polymer; the content of the norbornene-based polymer in the first thermoplastic resin; and the type and content of the light absorber.

[0093] The thickness of the first resin layer is not particularly limited, but is preferably 5 μm or more, more preferably 7 μm or more, particularly preferably 9 μm or more, and is preferably 35 μm or less, more preferably 30 μm or less, particularly preferably 25 μm or less. When the thickness of the first resin layer is within the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained.

[0094] When the optical film includes any layer in combination with the first resin layer, the ratio "t1 / T" of the thickness t1 of the first resin layer to the total thickness T of the optical film is preferably 0.2 or more, more preferably 0.25 or more, particularly preferably 0.3 or more, and preferably 0.9 or less, more preferably 0.87 or less, particularly preferably 0.85 or less. When the thickness ratio "t1 / T" is within the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained.

[0095] [5. Optional Layer] The optical film may include any layer in combination with the first resin layer described above. For example, the optical film preferably includes a second resin layer formed of a second thermoplastic resin and a third resin layer formed of a third thermoplastic resin in combination with the first resin layer. In this case, the optical film preferably includes the second resin layer, the first resin layer, and the third resin layer in this order in the thickness direction. In such an optical film, the second resin layer and the third resin layer suppress the movement of the light absorbent contained in the first resin layer. Therefore, it is possible to suppress the bleeding out of the light absorbent.

[0096] There is no limitation on the second thermoplastic resin contained in the second resin layer, and any thermoplastic resin containing a polymer can be used. The polymer may be used alone or in combination of two or more types at any ratio. Among them, the second thermoplastic resin preferably contains the above-mentioned norbornene-based polymer. By making the second resin layer from the second thermoplastic resin containing a norbornene-based polymer, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained. The norbornene-based polymer contained in the second thermoplastic resin may be different from the norbornene-based polymer contained in the first thermoplastic resin, but from the viewpoint of obtaining an optical film having particularly excellent tensile elongation at break and bending resistance, it is preferable that the norbornene-based polymer contained in the second thermoplastic resin is the same as the norbornene-based polymer contained in the first thermoplastic resin.

[0097] The amount of the norbornene-based polymer contained in the second thermoplastic resin is arbitrary within a range that allows the production of an optical film having excellent tensile elongation at break and bending resistance. Specifically, the amount of the norbornene-based polymer contained in the second thermoplastic resin is preferably 85% by weight to 100% by weight, more preferably 90% by weight to 100% by weight, and particularly preferably 95% by weight to 100% by weight, based on 100% by weight of the second thermoplastic resin.

[0098] The second thermoplastic resin may contain a light absorbing agent. However, from the viewpoint of effectively suppressing the bleed-out of the light absorbing agent, it is preferable that the second thermoplastic resin contains a small amount of the light absorbing agent, and it is more preferable that the second thermoplastic resin does not contain a light absorbing agent. To give a specific range, the amount of the light absorbing agent contained in the second thermoplastic resin is preferably 0% by weight to 5% by weight, more preferably 0% by weight to 3% by weight, and particularly preferably 0% by weight to 1% by weight, relative to 100% by weight of the second thermoplastic resin.

[0099] The second thermoplastic resin may contain an optional component in combination with the polymer. The optional components include the same examples as the optional components that the first thermoplastic resin may contain. In addition, the optional components may be used alone or in combination of two or more types in any ratio.

[0100] The glass transition temperature Tg of the second thermoplastic resin is not particularly limited. The glass transition temperature of the second thermoplastic resin may be any temperature selected from the range described as the range of the glass transition temperature Tg of the first thermoplastic resin. When the glass transition temperature Tg of the second thermoplastic resin is within the range described as the range of the glass transition temperature Tg of the first thermoplastic resin, the same advantages as those described in the section on the first resin layer can be obtained.

[0101] The thickness of the second resin layer is preferably 1.5 μm or more, more preferably 2 μm or more, particularly preferably 2.5 μm or more, and is preferably 10 μm or less, more preferably 9.5 μm or less, particularly preferably 9 μm or less. When the thickness of the second resin layer is in the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained.

[0102] There is no limitation on the third thermoplastic resin contained in the third resin layer, and any thermoplastic resin including a polymer can be used. The polymer may be used alone or in combination of two or more types at any ratio. In particular, it is preferable to use a thermoplastic resin selected from the range described as the second thermoplastic resin contained in the second resin layer as the third thermoplastic resin. Therefore, the type and amount of components contained in the third thermoplastic resin and the physical properties of the third thermoplastic resin can be selected and applied from the range described as the type and amount of components contained in the second thermoplastic resin and the physical properties of the second thermoplastic resin. This allows the same advantages as those described for the second resin layer to be obtained.

[0103] The third thermoplastic resin may be a resin different from the second thermoplastic resin, or may be the same resin. In particular, it is preferable to use the same resin as the second thermoplastic resin and the third thermoplastic resin. By using the same resin as the second thermoplastic resin and the third thermoplastic resin, it is possible to reduce the manufacturing cost of the optical film and to prevent curling of the optical film.

[0104] The thickness of the third resin layer is preferably within the range described as the range of the thickness of the second resin layer. When the thickness of the third resin layer is within the range described as the range of the thickness of the second resin layer, the same advantages as those described in the section on the second resin layer can be obtained. In particular, from the viewpoint of suppressing curling of the optical film, it is preferable that the second resin layer and the third resin layer have the same thickness.

[0105] The optical film may have layers other than the first resin layer, the second resin layer, and the third resin layer. Examples of such layers include an easy-adhesion layer, a pressure-sensitive adhesive layer, an adhesive layer, a hard coat layer, an index matching layer, an anti-reflection layer, a masking layer, an optically anisotropic layer, and a protective layer. However, from the viewpoint of obtaining an optical film that is particularly excellent in tensile elongation at break and bending resistance, it is preferable that the first resin layer and the second resin layer are directly in contact with each other without any other layer therebetween, and it is also preferable that the first resin layer and the third resin layer are directly in contact with each other without any other layer therebetween.

[0106] [6. Characteristics of optical films] The optical film described above is unlikely to break when pulled. Therefore, the optical film can have a large tensile breaking elongation E. The specific tensile breaking elongation E of the optical film is preferably 90% or more, more preferably 95% or more, and particularly preferably 100% or more. There is no particular upper limit to the tensile breaking elongation E of the optical film, and it can be, for example, 150% or less.

[0107] The tensile elongation at break E of the optical film can be measured by the following method in accordance with JIS K7127. Ten dumbbell-shaped test pieces of Type 1B are punched out from the optical film to be measured. When punching out the test pieces, the longitudinal direction of five test pieces and the longitudinal direction of the other five test pieces are set perpendicular to each other. For example, in a long optical film, the longitudinal direction of five test pieces may be set parallel to the longitudinal direction of the optical film, and the longitudinal direction of the other five test pieces may be set parallel to the width direction of the optical film. Then, the tensile elongation at break is measured for these test pieces. The tensile elongation at break is measured using a tensile tester with a thermo-hygrostat (for example, "5564" manufactured by Instron) at a tension speed of 20 mm / min in an environment of normal temperature and normal pressure. The average value of the measured tensile elongation at break of the test pieces may be the tensile elongation at break E of the optical film.

[0108] When the optical film is folded, cracks are unlikely to occur. Therefore, the optical film can have high bending resistance. Specifically, when the optical film is folded in one or more folding directions, the formation of cracks can be suppressed. The folding direction is usually an in-plane direction perpendicular to the thickness direction of the optical film, and represents the direction in which the part of the optical film moves due to folding. When folding in a manner that forms a crease, this folding direction is usually a direction perpendicular to the crease.

[0109] For example, a bending resistance test is performed by setting four bending directions at 45° intervals and bending the optical film 100,000 times in each of these bending directions. When these bending resistance tests are performed, the optical film can suppress cracks in bending resistance tests in usually one or more, preferably two or more, more preferably three or more, and particularly preferably four, bending directions. The bending resistance test can be performed under conditions of a stretch width of 50 mm, a bending radius of 1 mm, and a stretch speed of 80 times / min. The bending can be performed by a method of a planar body no-load U-shaped stretch test using a tabletop durability tester (Yuasa System Co., Ltd.'s "DLDMLH-FS").

[0110] The optical film may have retardation. For example, when the optical film is a stretched film, the molecules of the norbornene-based polymer may be oriented by stretching, and the optical film may be an optically anisotropic film having birefringence according to the orientation of the molecules. In this case, the optical film may have retardation. The specific range of retardation may be appropriately set according to the application of the optical film.

[0111] The in-plane retardation Re of the optical film is preferably 5 nm or less, more preferably 3 nm or less. The absolute value |Rth| of the thickness direction retardation Rth of the optical film is preferably 15 nm or less, more preferably 10 nm or less. The lower limits of Re and |Rth| are not particularly limited, but are both ideally 0. When the retardation of the optical film is in the above range, an optical film having particularly excellent bending resistance can be obtained.

[0112] The in-plane retardation Re of the optical film is a value expressed by Re = (nx - ny) x d, unless otherwise specified. The retardation Rth in the thickness direction of the film is a value expressed by Rth = [{(nx + ny) / 2} - nz] x d, unless otherwise specified. Here, nx represents the refractive index in the direction perpendicular to the thickness direction of the film (in-plane direction) that gives the maximum refractive index. ny represents the refractive index in the in-plane direction that is perpendicular to the direction of nx. nz represents the refractive index in the thickness direction. d represents the thickness of the film. Re and Rth can be values ​​for light with a wavelength of 590 nm.

[0113] The optical film preferably has a high total light transmittance. The specific total light transmittance of the optical film is preferably 85% to 100%, more preferably 87% to 100%, and particularly preferably 90% to 100%. The total light transmittance can be measured in the wavelength range of 400 nm to 700 nm using a commercially available spectrophotometer.

[0114] From the viewpoint of improving the image clarity of an image display device to which the optical film is applied, it is preferable that the optical film has a small haze. The haze of the optical film is preferably 1% or less, more preferably 0.8% or less, and particularly preferably 0.5% or less. The haze can be measured using a turbidimeter in accordance with JIS K7361-1997.

[0115] The thickness of the optical film is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more, particularly preferably 20 μm or more, and is preferably 35 μm or less, more preferably 27 μm or less, particularly preferably 25 μm or less. When the thickness of the optical film is within the above range, an optical film having particularly excellent tensile elongation at break and bending resistance can be obtained.

[0116] [7. Manufacturing method of optical film] The optical film described above can be manufactured, for example, by a manufacturing method including molding a first thermoplastic resin to form a first resin layer. There is no limitation on the molding method. Examples of the molding method include extrusion molding, solution casting, and inflation molding. Among them, extrusion molding and solution casting are preferred, and extrusion molding is particularly preferred.

[0117] For example, an optical film having a first resin layer, a second resin layer, and a third resin layer can be manufactured by a manufacturing method including forming a first thermoplastic resin to form a first resin layer, forming a second thermoplastic resin to form a second resin layer, and forming a third thermoplastic resin to form a third resin layer. Examples of the molding method include a co-extrusion method and a co-casting method. Among these molding methods, the co-extrusion method is preferable because it has excellent manufacturing efficiency and is unlikely to leave volatile components in the film.

[0118] The co-extrusion method includes co-extrusion of a first thermoplastic resin, a second thermoplastic resin, and a third thermoplastic resin. In this case, the extrusion method of each resin may be, for example, a co-extrusion T-die method, a co-extrusion inflation method, or a co-extrusion lamination method. Among them, the co-extrusion T-die method is preferred. The co-extrusion T-die method includes a feed block method and a multi-manifold method, and the feed block method is particularly preferred because it is easy to disassemble and clean.

[0119] The method for producing an optical film may further include any step, if necessary. For example, the method may include a step of stretching the optical film. This stretching can orient the molecules of the norbornene-based polymer in the film, so that the optical film can exhibit desired optical properties. In the following description, in order to distinguish between the optical film before stretching and the optical film after stretching, the optical film before stretching may be called an "unstretched film" and the optical film after stretching may be called a "stretched film". The stretching conditions may be set arbitrarily within a range in which the desired optical properties can be obtained.

[0120] The stretching mode may be, for example, uniaxial stretching in which stretching is performed in one direction, or biaxial stretching in which stretching is performed in two non-parallel directions. Furthermore, the biaxial stretching may be simultaneous biaxial stretching in which stretching is performed in two directions at the same time, or sequential biaxial stretching in which stretching is performed in one direction and then in the other direction.

[0121] The areal stretching ratio of the stretching is preferably 1.3 or more, more preferably 1.35 or more, particularly preferably 1.4 or more, and preferably 1.65 or less, more preferably 1.6 or less, particularly preferably 1.55 or less. The areal stretching ratio represents the product of the stretching ratios in each stretching direction. Thus, for example, in uniaxial stretching, the stretching ratio of the uniaxial stretching represents the areal stretching ratio. Also, for example, in biaxial stretching, the product of the stretching ratios in two directions represents the areal stretching ratio. When the areal stretching ratio is within the above range, a stretched film having particularly excellent breaking elongation and handling properties can be obtained.

[0122] The stretching temperature is preferably Tg° C. or higher, more preferably Tg+5° C. or higher, and preferably Tg+40° C. or lower, more preferably Tg+30° C. or lower, where Tg represents the glass transition temperature of the first thermoplastic resin. When the stretching temperature is within the above range, it is easy to make the thickness of the stretched film uniform.

[0123] Examples of further optional steps include a step of trimming the optical film, a step of laminating the optical film with another film, and a step of forming an optional further layer on the optical film.

[0124] According to the above-mentioned manufacturing method, a long optical film can be obtained. Such a long optical film can be manufactured continuously, and is excellent in productivity. In addition, lamination with other films can be performed by roll-to-roll, and in this respect, too, the productivity is excellent. Usually, a long optical film is wound up and stored and transported in a roll state.

[0125] [8. Uses of oriented films] The optical film described above can be provided in an image display device such as a liquid crystal display device. In this case, the optical film may be provided alone in the image display device, or may be attached to any film and provided in the image display device. As a specific example, the optical film may be attached to a polarizing film to obtain a multilayer film, and the multilayer film may be provided in the image display device. EXAMPLES

[0126] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples, and can be modified and carried out as desired without departing from the scope of the claims of the present invention and the scope of equivalents thereto. In the following description, the units "%" and "parts" that represent amounts are by weight unless otherwise specified. The following operations were carried out in air at room temperature and normal pressure unless otherwise specified.

[0127] [I. Methods for measuring and calculating physical properties of polymers and resins] (Method of measuring weight average molecular weight Mw of polymer) The weight-average molecular weight Mw of the polymer was measured by gel permeation chromatography (GPC) using cyclohexane as an eluent, and was calculated as a value converted into standard polyisoprene. When the polymer was not soluble in cyclohexane, THF was used as an eluent. When THF was used as an eluent, the weight-average molecular weight Mw was measured in terms of polystyrene. As the standard polyisoprene, standard polyisoprene manufactured by Tosoh Corporation (Mw=602, 1390, 3920, 8050, 13800, 22700, 58800, 71300, 109000, 280000) was used. The measurements were performed using three Tosoh columns (TSKgel G5000HXL, TSKgel G4000HXL, and TSKgel G2000HXL) connected in series under conditions of a flow rate of 1.0 mL / min, a sample injection amount of 100 μL, and a column temperature of 40°C.

[0128] (Method of measuring glass transition temperature Tg) The glass transition temperature Tg was measured using a differential scanning calorimeter ("DSC6220SII" manufactured by Nano Technology Corporation) in accordance with JIS K 6911 at a temperature rise rate of 10°C / min.

[0129] [II. Film Evaluation Method] (Method of measuring film thickness) The total thickness of the film was measured with a snap gauge ("ID-C112BS" manufactured by Mitutoyo Corporation). The thicknesses of the first resin layer, the second resin layer, and the third resin layer of the film were measured with an infrared film thickness meter (manufactured by Kurabo Industries, Ltd.) that calculates the film thickness from the absorbance of each layer.

[0130] (Method of measuring film retardation) The in-plane retardation Re and the retardation Rth in the thickness direction of the film were measured using a phase difference meter ("AXOScan" manufactured by Axometrics).

[0131] (Method of measuring tensile elongation at break E) In accordance with JIS K7127, the tensile elongation at break of the film to be measured was measured by the following method. Ten dumbbell-shaped test pieces of Type 1B were punched out from the film to be measured. Five of the test pieces were punched out so that the MD direction (flow direction, equivalent to the longitudinal direction) of the film was parallel to the longitudinal direction of the dumbbell-shaped test pieces. The remaining five test pieces were punched out so that the TD direction (direction perpendicular to the flow direction, equivalent to the width direction) of the film was parallel to the longitudinal direction of the dumbbell-shaped test pieces. The tensile elongation at break of the test pieces thus obtained was measured using a tensile tester (Instron "5564" model) equipped with a thermo-hygrostat. The tensile speed was 20 mm / min. The average value of the measured values ​​of the five test pieces having a longitudinal direction parallel to the MD direction of the film and the measured values ​​of the five test pieces having a longitudinal direction parallel to the TD direction of the film was calculated, and this average value was taken as the tensile elongation at break E of the film.

[0132] (Method of evaluating flex resistance by flex resistance test) The optical films obtained in each of the Examples and Comparative Examples were subjected to a bending resistance test using a tabletop durability tester (Yuasa System Co., Ltd.'s "DLDMLH-FS") by a method of a planar body unloaded U-shaped stretching test. The bending was performed up to 100,000 times under the conditions of a stretching width of 50 mm, a bending radius of 1 mm, and a stretching speed of 80 times / min. The bending was performed in four bending directions, namely, the MD direction, the TD direction, a 45° oblique direction that forms an angle of 45° in the MD direction, and a 135° oblique direction that forms an angle of 135° in the MD direction. Thereafter, the optical film was removed from the machine and visually observed to evaluate the bending resistance according to the following criteria. A+: No cracks in the film even after bending in any direction. A: The film cracks only after bending in a specific direction. B: After bending in any bending direction, cracks appear at the film edge extending from the edge of the film. C: Cracks appear at the film edge and center after bending in any bending direction.

[0133] [Example 1] (1-1) Preparation of norbornene ring-opening polymer: In a glass reactor with the inside substituted with nitrogen, 200 parts of dehydrated cyclohexane, 0.7 mol% of 1-hexene, 0.15 mol% of diisopropyl ether, and 0.44 mol% of triisobutylaluminum were placed at room temperature and mixed with respect to a total of 100 parts by weight of the monomers described below. Thereafter, while maintaining the polymerization temperature at 45°C, 70 parts by weight of dicyclopentadiene (abbreviated as "DCPD") and 30 parts by weight of tetracyclododecene (abbreviated as "TCD") as monomers, and 0.02 mol% of tungsten hexachloride (0.65 wt% toluene solution) were continuously added in parallel to the reactor over a period of 2 hours to polymerize. Next, 0.2 mol% of isopropyl alcohol was added to the polymerization solution to inactivate the polymerization catalyst and terminate the polymerization reaction. In the above explanation, the amount indicated by the unit "mol%" is a value assuming that the total amount of the monomers is 100 mol%. As a result, a reaction solution containing a norbornene-based ring-opening polymer as a polymer of the monomers was obtained. The weight-average molecular weight Mw of the resulting norbornene ring-opening polymer was 3.1×10 4 The conversion rate of the monomer to the polymer was 100%.

[0134] (1-2) Production of norbornene-based hydrides by hydrogenation: Next, 67 parts by weight of cyclohexane was added to 183 parts by weight of the reaction solution containing the norbornene-based ring-opening polymer obtained in the above step (1-1), and 0.8% by weight of a diatomaceous earth supported nickel catalyst ("T8400RL" manufactured by JGC Chemical Co., Ltd., nickel loading rate 57%) was further added as a hydrogenation catalyst. The amount of hydrogenation catalyst is expressed as a value relative to 100% by weight of the norbornene-based ring-opening polymer contained in the reaction solution. Thereafter, the reaction solution was pressurized to 4.5 MPa with hydrogen and heated to a temperature of 190°C while stirring, and the hydrogenation reaction was carried out for 8 hours. As a result, a reaction solution containing a norbornene-based hydrogenated product as a hydrogenated product of the norbornene-based ring-opening polymer was obtained. The hydrogenation rate of this norbornene-based hydrogenated product was calculated as follows: 1 The hydrogenation rate of the non-aromatic carbon-carbon unsaturated bonds was determined to be 99.9% by 1 H-NMR.

[0135] The obtained reaction solution was filtered under pressure at a pressure of 0.25 MPa using Radiolite #500 as a filter bed (Ishikawajima-Harima Heavy Industries Co., Ltd.'s "Fundaback Filter") to remove the hydrogenation catalyst, and a colorless, transparent solution was obtained. The obtained solution was poured into a large amount of isopropanol to precipitate a norbornene-based hydrogenated product. The precipitated norbornene-based hydrogenated product was filtered off. Then, 2.0 parts of a xylene solution in which 0.1 parts of an antioxidant [pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (Ciba Specialty Chemicals Co., Ltd.'s "Irganox (registered trademark) 1010)] was dissolved was added to 100 parts of the norbornene-based hydrogenated product. Next, the product was dried in a vacuum dryer (200°C, 1 Torr) for 6 hours to obtain a thermoplastic norbornene-based resin that does not contain a light absorber. The weight-average molecular weight of the norbornene-based hydrogenated product was 4.4 x 10 4 In the following description, this thermoplastic norbornene resin not containing a light absorbing agent may be referred to as "resin F."

[0136] The glass transition temperature Tg of the resin F was measured by the above-mentioned method. The glass transition temperature Tg of the resin F was 116° C.

[0137] (1-3) Preparation of thermoplastic resin containing light absorber: A twin-screw extruder (manufactured by Toshiba Corporation, ratio L / D of screw length L to screw diameter D = 42) with a screw having a total length of 1848 mm and a diameter of 44 mm was prepared. This screw had a total of three kneading zones at positions 685 mm, 920 mm, and 1190 mm away from the upstream end of the screw. Here, the distance from the upstream end of the screw to the position of the kneading zone refers to the distance from the upstream end of the screw to the upstream end of the kneading zone. In addition, upstream refers to the upstream in the resin flow direction. Furthermore, the ratios Lnx / D of the length Lnx of each kneading zone to the screw diameter D were Lnx / D = 4, Lnx / D = 2, and Lnx / D = 2, starting from the upstream kneading zone.

[0138] Into this twin-screw extruder, 100 parts of resin F produced in the above step (1-2), 6 parts of a benzotriazole-based ultraviolet absorber (ADEKA's "LA-31", molecular weight 659) as a light absorber, and 3 parts of a pentaerythritol-based infrared absorber (FUJIFILM Wako Chemical's "Tetra(2-ethylhexanoate)pentaerythritol", molecular weight 641) were added and kneaded to obtain a thermoplastic resin containing a light absorber. In the following description, this thermoplastic norbornene-based resin containing a light absorber may be referred to as "resin FA". The content of the light absorber in this resin FA was 8.3% by weight, and the glass transition temperature of resin FA was 106°C.

[0139] (1-4. Production of unstretched film) A double-flight type single-screw extruder (screw diameter D = 50 mm, ratio of screw length L to screw diameter D = 28) equipped with a leaf disk-shaped polymer filter with a mesh size of 3 μm was prepared. The resin FA produced in the above step (1-3) was introduced into this single-screw extruder, melted, and fed to the single-layer die via a feed block. The resin FA was introduced into the single-screw extruder via a hopper loaded into the single-screw extruder. The surface roughness (arithmetic mean roughness Ra) of the die lip of the single-layer die was 0.1 μm. Furthermore, the temperature of the resin FA at the extruder outlet was 260 ° C.

[0140] On the other hand, a single screw extruder (screw diameter D=50 mm, ratio of screw length L to screw diameter D L / D=30) equipped with a leaf disk-shaped polymer filter with a mesh size of 3 μm was prepared. Resin F produced in the above step (1-2) was introduced into this single screw extruder, melted, and fed to the above single layer die via a feed block. The temperature of Resin F at the extruder outlet was 260° C.

[0141] Thereafter, the resin FA and the resin F were extruded from a single-layer die in a molten state at 260°C so as to be extruded into a film including three layers, namely a layer of resin F, a layer of resin FA, and a layer of resin F (co-extrusion molding process). The extruded resin was cast onto a cooling roll whose temperature was adjusted to 100°C, and passed through a cooling roll whose temperature was adjusted to 50°C to obtain an unstretched film as a long optical film. When the resin was extruded from the single-layer die and cast onto the cooling roll, the air gap amount was set to 50mm. In addition, edge pinning was adopted as a method for casting the molten film-like resin onto the cooling roll.

[0142] The obtained unstretched film was a two-kind, three-layer film having a second resin layer formed of resin F, a first resin layer formed of resin FA, and a third resin layer formed of resin F, in that order in the thickness direction. "Two-kind, three-layer" means that the film contains three layers, and these layers are made of two types of resin. The total thickness of this unstretched film was 25 μm. The total thickness of the two layers formed of resin F (i.e., the second resin layer and the third resin layer) was 5 μm, and the thickness of the first resin layer formed of resin FA was 20 μm.

[0143] The obtained optical film was evaluated by the above-mentioned method, and as a result, the tensile elongation at break E was 110%, and the result of the bending test was A+.

[0144] [Example 2] In the above step (1-3), the light absorber used was changed to 5 parts of a triazine-based ultraviolet absorber (BASF's "Tinuvin 1577ED" molecular weight 425). The glass transition temperature of the obtained resin FA was 112°C. In addition, in the above-mentioned step (1-4), by adjusting the extrusion speed of resin F and resin FA, the total thickness of the two layers formed with resin F (i.e., the second resin layer and the third resin layer) was changed to 16 μm, and the thickness of the first resin layer formed with resin FA was changed to 9 μm. Except for the above, the same method as in Example 1 was used to produce and evaluate an unstretched film as an optical film.

[0145] [Example 3] In the above step (1-1), the combination of monomers used was changed to 29 parts by weight of tetracyclododecene (TCD), 70 parts by weight of dicyclopentadiene (DCPD), and 1 part by weight of norbornene (NB). The weight average molecular weight Mw of the obtained norbornene-based hydride was 4.2×10 4 The glass transition temperature of resin F was 111°C. In the above step (1-3), a pentaerythritol-based infrared absorbing agent was not used as a light absorbing agent. The glass transition temperature of the obtained resin FA was 104°C. Except for the above, the same method as in Example 1 was used to produce and evaluate an unstretched film as an optical film.

[0146] [Example 4] In the above step (1-1), the combination of monomers used was changed to 29 parts by weight of tetracyclododecene (TCD), 70 parts by weight of dicyclopentadiene (DCPD), and 1 part by weight of norbornene (NB). The weight average molecular weight Mw of the obtained norbornene-based hydride was 4.2×10 4 The glass transition temperature of resin F was 111°C, and the glass transition temperature of resin FA was 101°C. Except for the above, the same method as in Example 1 was used to produce and evaluate an unstretched film as an optical film.

[0147] [Example 5] In the above step (1-1), the combination of monomers used was changed to 29 parts by weight of tetracyclododecene (TCD), 70 parts by weight of dicyclopentadiene (DCPD), and 1 part by weight of norbornene (NB). The weight average molecular weight Mw of the obtained norbornene-based hydride was 4.2×10 4 The glass transition temperature of resin F was 111°C. In the above step (1-3), the light absorber used was changed to 5 parts of a triazine-based ultraviolet absorber (BASF's "Tinuvin 1577ED"). The glass transition temperature of the obtained resin FA was 107°C. Furthermore, in the above-mentioned step (1-4), by adjusting the extrusion speed of resin F and resin FA, the total thickness of the two layers formed with resin F (i.e., the second resin layer and the third resin layer) was changed to 16 μm, and the thickness of the first resin layer formed with resin FA was changed to 9 μm. Except for the above, the same method as in Example 1 was used to produce and evaluate an unstretched film as an optical film.

[0148] [Example 6] In the above step (1-1), the combination of monomers used was changed to 29 parts by weight of tetracyclododecene (TCD), 70 parts by weight of dicyclopentadiene (DCPD), and 1 part by weight of norbornene (NB). The weight average molecular weight Mw of the obtained norbornene-based hydride was 4.2×10 4 The glass transition temperature of resin F was 111°C. In the above step (1-3), the amount of the benzotriazole-based ultraviolet absorber was changed to 8 parts, and no pentaerythritol-based infrared absorber was used. The glass transition temperature of the obtained resin FA was 102°C. Furthermore, in the above-mentioned step (1-4), by adjusting the extrusion speed of resin F and resin FA, the total thickness of the two layers formed with resin F (i.e., the second resin layer and the third resin layer) was changed to 17 μm, the thickness of the first resin layer formed with resin FA was changed to 15 μm, and the total thickness of the unstretched film was changed to 32 μm. Except for the above, an unstretched film was produced in the same manner as in Example 1.

[0149] The unstretched film was fed to an oblique stretching machine using a tenter method. Using this oblique stretching machine, the unstretched film was stretched in an oblique direction by 1.5 times while adjusting the take-up tension and the tenter chain tension, to obtain an obliquely stretched film as an optical film having a thickness of 21 μm. The oblique direction as the stretching direction in this example was a direction forming an angle of 45° with respect to the longitudinal direction of the unstretched film. The stretching temperature of the oblique stretching machine was 109°C. The optical film thus obtained was evaluated by the above-mentioned method.

[0150] [Example 7] In the above step (1-1), the combination of monomers used was changed to 28 parts by weight of tetracyclododecene (TCD), 70 parts by weight of dicyclopentadiene (DCPD), and 2 parts by weight of norbornene (NB). The weight average molecular weight Mw of the obtained norbornene-based hydride was 3.9×10 4 The glass transition temperature of resin F was 108°C. In the above step (1-3), the amount of the benzotriazole-based ultraviolet absorber was changed to 8 parts, and the pentaerythritol-based infrared absorber was not used. The glass transition temperature of the obtained resin FA was 99°C. Furthermore, in the above-mentioned step (1-4), by adjusting the extrusion speed of resin F and resin FA, the total thickness of the two layers formed with resin F (i.e., the second resin layer and the third resin layer) was changed to 18 μm, the thickness of the first resin layer formed with resin FA was changed to 15 μm, and the total thickness of the unstretched film was changed to 33 μm. Except for the above, an unstretched film was produced in the same manner as in Example 1.

[0151] The unstretched film was fed to an oblique stretching machine using a tenter method. Using this oblique stretching machine, the unstretched film was stretched in an oblique direction by 1.45 times while adjusting the take-up tension, the tenter chain tension, and the tenter chain speed, to obtain an obliquely stretched film as an optical film having a thickness of 23 μm. The oblique direction as the stretching direction in this example was a direction forming an angle of 45° with respect to the longitudinal direction of the unstretched film. The stretching temperature of the oblique stretching machine was 110° C. The optical film thus obtained was evaluated by the above-mentioned method.

[0152] [Example 8] (8-1) 8-Methyl-8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 Preparation of ]-3-dodecene (abbreviated as "DNM"): Methyl 2-methylbicyclo[2,2,1]-5-heptene-2-carboxylate (Cas. 7398-76-7; manufactured by Angene International Limited) and dicyclopentadiene (DCPD) were charged in a high pressure vessel at a molar ratio of 88:12. The air in the vessel was then replaced with nitrogen, and the vessel was heated to 165°C at a stirring speed of 600 rpm and held for 1 minute. The vessel was then heated to 200°C and reacted for 3 hours to obtain 8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-dodecene (DNM) was obtained.

[0153] (8-2) Preparation of norbornene ring-opening polymer: In a glass reactor with the inside replaced with nitrogen, 200 parts of dehydrated toluene and 13 parts of 1-hexene were placed at room temperature, based on 100 parts by weight of the monomers described below, and mixed. Then, while keeping the temperature at 100°C, 8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 92 parts of ]-3-dodecene (DNM) were added, then 0.005 parts of triethylaluminum and 0.005 parts of methanol-modified tungsten hexachloride were added, and 8 parts of norbornene (NB) as a monomer was added over 20 minutes. The reaction was then continued for another 45 minutes. Next, 0.2 mol% of isopropyl alcohol was added to the polymerization solution to inactivate the polymerization catalyst and terminate the polymerization reaction. In the above explanation, the amount indicated by the unit "mol%" is a value assuming that the total amount of monomers is 100 mol%. As a result, a reaction solution containing a norbornene-based ring-opening polymer as a polymer of the monomer was obtained. The conversion rate of the monomer to the polymer was 100%.

[0154] (8-3) Production of norbornene-based hydrides by hydrogenation: Next, 67 parts of toluene was added to 183 parts of the reaction solution containing the norbornene-based ring-opening polymer obtained in the above step (8-2), and 0.0043 parts of chlorohydridocarbonyltris(triphenylphosphine)ruthenium (hereinafter, sometimes abbreviated as "ruthenium catalyst") was further added as a hydrogenation catalyst. Thereafter, the hydrogenation reaction was carried out at a hydrogen pressure of 4.5 MPa and 160°C for 4 hours. As a result, a reaction solution containing a norbornene-based hydride as a hydrogenated product of the norbornene-based ring-opening polymer was obtained.

[0155] The obtained solution was poured into a large amount of isopropanol to precipitate a norbornene-based hydride. The precipitated norbornene-based hydride was collected by filtration. Then, 2.0 parts of a xylene solution in which 0.1 parts of an antioxidant [pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (manufactured by Ciba Specialty Chemicals, Inc., "Irganox (registered trademark) 1010") was dissolved was added to 100 parts of the norbornene-based hydride. Then, the mixture was dried in a vacuum dryer (200°C, 1 Torr) for 6 hours to obtain a thermoplastic norbornene-based resin containing no light absorbent as resin F. The weight average molecular weight of the norbornene-based hydride was 5.0 x 10 4 It was.

[0156] The glass transition temperature Tg of the resin F was measured by the above-mentioned method. The glass transition temperature Tg of the resin F was 136°C.

[0157] (8-4) Preparation of thermoplastic resin containing ultraviolet absorber: Instead of the resin F produced in Example 1, the resin F produced in the above step (8-3) was used. In addition, the amount of the benzotriazole-based ultraviolet absorber was changed to 13 parts, and no pentaerythritol-based infrared absorber was used. Except for the above, a thermoplastic resin containing a light absorber was obtained as the resin FA by the same method as in step (1-3) of Example 1. The glass transition temperature of the obtained resin FA was 122°C.

[0158] (8-5) Production of unstretched film: Instead of the resin F and resin FA produced in Example 1, the resin F and resin FA produced in the above steps (8-3) and (8-4) were used. In addition, by adjusting the discharge speed of the resin F and resin FA, the total thickness of the two layers (i.e., the second resin layer and the third resin layer) formed with the resin F was changed to 5 μm, the thickness of the first resin layer formed with the resin FA was changed to 15 μm, and the total thickness of the unstretched film was changed to 20 μm. Except for the above, an unstretched film was obtained as a long optical film by the same method as in step (1-4) of Example 1. The obtained optical film was evaluated by the above-mentioned method.

[0159] [Comparative Example 1] (C1-1) Preparation of thermoplastic resin containing norbornene hydride: The combination of monomers used was changed to 60 parts by weight of methanotetrahydrofluorene (MTF) and 40 parts by weight of tetracyclododecene (TCD). The amount of 1-hexene was changed to 0.8 mol%. The polymerization temperature of the monomers was changed to 55°C. Except for the above, a thermoplastic norbornene-based resin was obtained as resin F containing a norbornene-based hydride and an antioxidant but not a light absorbent, by the same method as in step (1-1) and step (1-2) of Example 1. The weight average molecular weight Mw of the obtained norbornene-based hydride was 3.1 x 10 4 The glass transition temperature of resin F was 161°C.

[0160] (C1-2) Preparation of thermoplastic resin containing light absorber: Instead of the resin F produced in Example 1, the resin F produced in the above step (C1-1) was used. Except for the above, a thermoplastic resin containing a light absorbent was obtained as the resin FA by the same method as in step (1-3) of Example 1. The glass transition temperature of the obtained resin FA was 151°C.

[0161] (C1-3) Production of unstretched film: Resin F and Resin FA produced in the above steps (C1-1) and (C1-2) were used instead of Resin F and Resin FA produced in Example 1. Except for the above, a long unstretched film was obtained in the same manner as in step (1-4) of Example 1. The obtained unstretched film was evaluated by the method described above.

[0162] [Comparative Example 2] (C2-1) Production of thermoplastic resin containing norbornene hydride: The combination of monomers used was changed to 10 parts by weight of methanotetrahydrofluorene (MTF), 40 parts by weight of tetracyclododecene (TCD), and 50 parts by weight of dicyclopentadiene (DCPD). The amount of 1-hexene was changed to 0.76 mol%. The polymerization temperature of the monomers was changed to 55°C. Except for the above, a thermoplastic norbornene-based resin was obtained as resin F containing a norbornene-based hydride and an antioxidant but not containing a light absorber by the same method as in step (1-1) and step (1-2) of Example 1. The weight average molecular weight Mw of the obtained norbornene-based hydride was 3.6 x 10 4 The glass transition temperature of resin F was 128°C.

[0163] (C2-2) Preparation of thermoplastic resin containing light absorber: Instead of the resin F produced in Example 1, the resin F produced in the above step (C2-1) was used. In addition, the amount of the benzotriazole-based ultraviolet absorber was changed to 8 parts, and no pentaerythritol-based infrared absorber was used. Except for the above, a thermoplastic resin containing a light absorber was obtained as the resin FA by the same method as in step (1-3) of Example 1. The glass transition temperature of the obtained resin FA was 119°C.

[0164] (C2-3) Production of unstretched film: Instead of the resin F and resin FA produced in Example 1, the resin F and resin FA produced in the above steps (C2-1) and (C2-2) were used. In addition, by adjusting the extrusion speed of the resin F and resin FA, the total thickness of the two layers (i.e., the second resin layer and the third resin layer) formed with the resin F was changed to 20 μm, the thickness of the first resin layer formed with the resin FA was changed to 15 μm, and the total thickness of the unstretched film was changed to 35 μm. A long unstretched film was obtained by the same method as in step (1-4) of Example 1, except for the above.

[0165] (C2-4) Production of stretched film: The unstretched film was fed to an oblique stretching machine using a tenter method. Using this oblique stretching machine, the unstretched film was stretched in an oblique direction by 1.45 times while adjusting the take-up tension, the tenter chain tension, and the tenter chain speed, to obtain an obliquely stretched film having a thickness of 24 μm. The oblique direction as the stretching direction in this example was a direction forming an angle of 45° with respect to the longitudinal direction of the unstretched film. The stretching temperature of the oblique stretching machine was 110° C. The obliquely stretched film thus obtained was evaluated by the method described above.

[0166] [Comparative Example 3] (C3-1) Preparation of thermoplastic norbornene-based resin containing norbornene-based hydride: 8-Methyl-8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 The amount of 1-hexene (DNM) was changed to 100 parts. The amount of 1-hexene was changed to 10 parts. Furthermore, norbornene (NB) was not used. Except for the above, a thermoplastic norbornene resin was obtained as resin F containing a norbornene hydride and an antioxidant but not a light absorbent, in the same manner as in step (8-2) and step (8-3) of Example 8. The weight average molecular weight Mw of the obtained norbornene hydride was 13.0×10 4 The glass transition temperature of resin F was 165°C.

[0167] (C3-2) Preparation of thermoplastic resin containing light absorber: Instead of the resin F produced in Example 1, the resin F produced in the above step (C3-1) was used. In addition, no pentaerythritol-based infrared absorbent was used. Except for the above, a thermoplastic resin containing a light absorbent was obtained as the resin FA by the same method as in step (1-3) of Example 1. The glass transition temperature of the obtained resin FA was 158°C.

[0168] (C3-3) Production of unstretched film: Resin F and Resin FA produced in the above steps (C3-1) and (C3-2) were used instead of Resin F and Resin FA produced in Example 1. A long unstretched film was obtained in the same manner as in step (1-4) of Example 1, except for the above. The unstretched film thus obtained was evaluated by the method described above.

[0169] [Comparative Example 4] Resin F produced in Example 1 was introduced into a single-screw extruder, melted, and fed to a single-layer die via a feed block. The same single-layer die as that used in Example 1 was used. Resin F was extruded from the single-layer die in a molten state at 260°C (extrusion molding process). The extruded resin was cast onto a cooling roll as in Example 1, and passed through the cooling roll to obtain a long unstretched film with a thickness of 40 μm. The resulting unstretched film was evaluated by the methods described above.

[0170] [result] The results of the above-mentioned Examples and Comparative Examples are shown in the following table. In the following table, the meanings of the abbreviations are as follows. TCD: tetracyclododecene. DNM: 8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1 2,5 .1 7,10 ]-3-Dodecene. DCPD: dicyclopentadiene. NB: Norbornene. MTF: methanotetrahydrofluorene. Light absorber A: Triazine-based ultraviolet absorber (BASF's "Tinuvin 1577ED", molecular weight 425). Light absorber B: Benzotriazole-based ultraviolet absorber (ADEKA Corporation "LA-31", molecular weight 659). Light absorber C: Pentaerythritol-based infrared absorber ("Pentaerythritol tetra(2-ethylhexanoate)" molecular weight 641, manufactured by Fujifilm Wako Chemicals). Re: In-plane retardation of film. Rth: Retardation in the thickness direction of the film.

[0171] [Table 1]

[0172] [Table 2] [Explanation of symbols]

[0173] 100, 200 Optical film 110 First resin layer 220 Second resin layer 230 Third resin layer

Claims

1. A first resin layer is formed of a first thermoplastic resin containing a norbornene-based polymer and a light absorbing agent, the norbornene-based polymer is selected from the group consisting of polymers of norbornene-based monomer compositions and hydrogenated products thereof, The norbornene-based monomer composition contains one or more monomers selected from the group consisting of a monomer represented by the following formula (T) and a monomer represented by the following formula (D), The amount of the monomer represented by the following formula (D) is 65% by weight or more and 80% by weight or less with respect to 100% by weight of the total amount of the norbornene-based monomer composition, The norbornene-based polymer has a weight average molecular weight of 38,000 or more and 100,000 or less, The amount of the light absorber in the first thermoplastic resin is 2% by weight to 30% by weight. 【Chemistry 1】 (In formula (T), Each of nt1 and nt2 independently represents 1 or 2; When nt1 is 1, R ｔ１ represents a divalent hydrocarbon group, When nt1 is 2, R ｔ１ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, When nt2 is 1, R ｔ２ represents a divalent hydrocarbon group, When nt2 is 2, R ｔ２ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group; In formula (D), nd1, nd2 and nd3 each independently represent 1 or 2; When nd1 is 1, R ｄ１ represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, When nd1 is 2, R ｄ１ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, When nd2 is 1, R ｄ２ represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, When nd2 is 2, R ｄ２ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, When nd3 is 1, R ｄ３ represents a divalent hydrocarbon group, When nd3 is 2, R ｄ３ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group.

2. The optical film of claim 1 , wherein the light absorber comprises a pentaerythritol-based infrared absorber.

3. A first resin layer is formed of a first thermoplastic resin containing a norbornene-based polymer and a light absorbing agent, the norbornene-based polymer is selected from the group consisting of polymers of norbornene-based monomer compositions and hydrogenated products thereof, The norbornene-based monomer composition contains 50% by weight or more of one or more monomers selected from the group consisting of a monomer represented by the following formula (T) and a monomer represented by the following formula (D), The norbornene-based polymer has a weight average molecular weight of 38,000 or more and 100,000 or less, the amount of the light absorber in the first thermoplastic resin is 2% by weight to 30% by weight; The optical film, wherein the light absorber comprises a pentaerythritol-based infrared absorber. 【Chemistry 2】 (In formula (T), Each of nt1 and nt2 independently represents 1 or 2; When nt1 is 1, R ｔ１ represents a divalent hydrocarbon group, When nt1 is 2, R ｔ１ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, When nt2 is 1, R ｔ２ represents a divalent hydrocarbon group, When nt2 is 2, R ｔ２ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group; In formula (D), nd1, nd2 and nd3 each independently represent 1 or 2; When nd1 is 1, R ｄ１ represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, When nd1 is 2, R ｄ１ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, When nd2 is 1, R ｄ２ represents a hydrogen atom, an alkyl group, an alkyloxycarbonyl group, or a divalent hydrocarbon group, When nd2 is 2, R ｄ２ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, When nd3 is 1, R ｄ３ represents a divalent hydrocarbon group, When nd3 is 2, R ｄ３ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group.

4. The norbornene-based monomer composition contains 1% by weight to 15% by weight of a monomer represented by the following formula (N): 【Chemistry 3】 (In formula (N), nn1 and nn2 each independently represent 1 or 2; When nn1 is 1, R ｎ１ represents a divalent hydrocarbon group, When nn1 is 2, R ｎ１ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group, If nn2 is 1, then R ｎ２ represents a divalent hydrocarbon group, When nn2 is 2, R ｎ２ each independently represents a hydrogen atom, an alkyl group, or an alkyloxycarbonyl group.

5. 5. The optical film according to claim 1, wherein the light absorbing agent comprises at least one selected from the group consisting of an ultraviolet absorbing agent and an infrared absorbing agent.

6. The optical film according to any one of claims 1 to 5, wherein the molecular weight of the light absorbent is 800 or less.

7. 7. The optical film according to claim 1, wherein the light absorber comprises at least one selected from the group consisting of triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers.

8. The optical film according to any one of claims 1 to 7, comprising, in this order, a second resin layer formed of a second thermoplastic resin, the first resin layer, and a third resin layer formed of a third thermoplastic resin.

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