TW202037643A - Optical film, flexible display device, and polyamide-imide resin - Google Patents

Abstract

An optical film is provided which has high elasticity and a low humidity expansion rate. This optical film contains a polyamide-imide resin which has a weight average molecular weight of 200,000-1,000,000 and which has at least a constituent unit represented by formula (1) [in formula (1), Ar1 represents a divalent aromatic group having a fluoroalkyl group with 1-12 carbons, and X represents a divalent organic group], and a constituent unit represented by formula (2) [In formula (2), X represents a divalent organic group and Y represents a tetravalent organic group].

Description

Optical film, flexible display device and polyimide resin

The present invention relates to an optical film containing a polyimide-based resin, a flexible display device provided with the optical film, and a polyimide-based resin.

Currently, display devices such as liquid crystal display devices or organic EL (Electroluminescence) display devices are not only used in televisions, but also widely used in various applications such as mobile phones and smart watches. Previously, the industry has always used glass as the front panel of such display devices. However, glass has high transparency and can exhibit high hardness depending on its type. On the other hand, it is very rigid and easy to crack, so it is difficult to use as a front panel material for flexible display devices.

Therefore, the industry continues to study the use of polymer materials as materials to replace glass. Since the panel tends to exhibit flexibility before including a polymer material, it is expected to be used in various applications. As one of the flexible polymer materials, the industry is studying, for example, optical films using polyimide-based resins (Patent Documents 1 and 2). [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 2015-521686 [Patent Document 2] Japanese Patent Application Publication No. 2018-119132

[The problem to be solved by the invention]

However, when an optical film using polyimide-based resin is used in a flexible display device, etc., defects such as scratches, wrinkles, etc. exist on the optical film due to bending or contact with external factors. situation. The inventors of the present invention conducted various studies to improve the above-mentioned methods and found that by increasing the elastic modulus of the optical film, defects such as scratches are not easily generated on the optical film. In addition, flexible display devices are long-term users in various environments. In particular, the optical film applied with a load may expand and contract in a planar direction due to changes in temperature and humidity. Therefore, the optical film is also required to have a low humidity expansion rate for changes in temperature and humidity.

Therefore, the subject of the present invention is to provide an optical film with high elastic modulus and low humidity expansion rate. [Technical means to solve the problem]

In order to solve the above-mentioned problems, the inventors of the present invention focused on the structure of the monomer constituting the polyimide-based resin contained in the optical film, and conducted diligent research. As a result, it was found that an optical film including a polyamide imide resin having at least a specific structural unit and a weight average molecular weight in a specific range has both a high elastic modulus and a low humidity expansion rate, thereby completing the present invention.

[式(1)中，Ar¹ 表示具有碳數1～12之氟烷基之二價芳香族基，X表示二價有機基]、 及式(2)所表示之結構單元： [化2]

[式(2)中，X表示二價有機基，Y表示四價有機基]， 且重量平均分子量為200,000～1,000,000。 [2]如上述[1]中所記載之光學膜，其中式(1)中之Ar¹ 中之碳數1～12之氟烷基為碳數1～12之全氟烷基。 [3]如上述[1]或[2]中所記載之光學膜，其中式(1)所表示之結構單元包含式(4)所表示之芳香族基作為Ar¹ ， [化3]

[式(4)中， R¹ 表示碳數1～12之氟烷基， n及k相互獨立地表示1～4之整數，其中，於n及/或k表示2～4之整數之情形時，複數個存在之R¹ 相互可相同亦可不同， *表示鍵結鍵]。 [4]如上述[3]中所記載之光學膜，其中式(4)中之2個鍵結鍵相互位於對位。 [5]如上述[3]或[4]中所記載之光學膜，其中式(4)中之k為1或2。 [6]如上述[3]至[5]中任一項所記載之光學膜，其中式(4)中之R¹ 表示碳數1～12之全氟烷基，n為1或2。 [7]如上述[1]至[6]中任一項所記載之光學膜，其中式(1)所表示之結構單元及/或式(2)所表示之結構單元包含式(5)所表示之二價有機基作為X， [化4]

[式(5)中， Ar² 表示可具有取代基之二價芳香族基， V表示單鍵、-O-、二苯基亞甲基、茀基、碳數1～12之二價烴基、-SO₂ -、-S-、-CO-、-PO-、-PO₂ -、-N(R^a )-或-Si(R^b )₂ -，此處，該烴基可包含脂環式結構，該烴基中所含之氫原子可相互獨立地經鹵素原子取代，R^a 及R^b 相互獨立地表示氫原子、或可經鹵素原子取代之碳數1～12之烴基， m表示0～3之整數， *表示鍵結鍵]。 [8]如上述[7]中所記載之光學膜，其中式(5)中之m為1。 [9]如上述[1]至[6]中任一項所記載之光學膜，其中式(1)所表示之結構單元及/或式(2)所表示之結構單元包含式(5a)所表示之二價有機基作為X， [化5]

[式(5)中， R² 表示碳數1～12之氟烷基， p及q相互獨立地表示1～4之整數，其中，於p及/或q表示2～4之整數之情形時，複數個存在之R² 相互可相同亦可不同， *表示鍵結鍵]。 [10]如技術方案1至6中任一項所記載之光學膜，其中式(1)所表示之結構單元及/或式(2)所表示之結構單元包含式(5c)所表示之二價有機基作為X， [化6]

[式(5c)中之*表示鍵結鍵]。 [11]如上述[1]至[10]中任一項所記載之光學膜，其厚度為10～200 μm。 [12]一種可撓性顯示裝置，其具備如上述[1]至[11]中任一項所記載之膜。 [13]如上述[12]中所記載之可撓性顯示裝置，其進而具備觸控感測器。 [14]如上述[12]或[13]中所記載之可撓性顯示裝置，其進而具備偏光板。 [15]一種聚醯胺醯亞胺系樹脂，其至少具有由式(1)所表示之結構單元： [化7]

[式(1)中， Ar¹ 表示具有碳數1～12之氟烷基之二價芳香族基， X表示二價有機基]， 且包含式(4)所表示之芳香族基作為式(1)中之Ar¹ ： [化8]

[式(4)中， R¹ 表示碳數1～12之氟烷基， n及k相互獨立地表示1～4之整數，其中，於n及/或k表示2～4之整數之情形時，複數個存在之R¹ 相互可相同亦可不同， *表示鍵結鍵]； 以及式(2)所表示之結構單元： [化9]

[式(2)中，X表示二價有機基，Y表示四價有機基]， 且重量平均分子量為200,000～1,000,000。 [發明之效果]That is, the present invention includes the following suitable aspects. [1] An optical film comprising the following polyimide imide resin, the polyimide imine resin having at least the structural unit represented by formula (1): [化1]

[In formula (1), Ar ¹ represents a divalent aromatic group having a carbon number of 1-12 fluoroalkyl group, and X represents a divalent organic group], and the structural unit represented by formula (2): [化2]

[In formula (2), X represents a divalent organic group and Y represents a tetravalent organic group], and the weight average molecular weight is 200,000 to 1,000,000. [2] The optical film as described in [1] above, wherein the fluoroalkyl group having 1 to 12 carbons in Ar ¹ in the formula (1) is a perfluoroalkyl group having 1 to 12 carbons. [3] The optical film as described in [1] or [2] above, wherein the structural unit represented by formula (1) contains the aromatic group represented by formula (4) as Ar ¹ , [化3]

[In formula (4), R ¹ represents a fluoroalkyl group having 1 to 12 carbon atoms, and n and k independently represent an integer of 1 to 4, where n and/or k represent an integer of 2 to 4 , A plurality of R ¹ may be the same or different from each other, * indicates a bonding bond]. [4] The optical film as described in the above [3], wherein the two bonding bonds in the formula (4) are positioned opposite to each other. [5] The optical film as described in [3] or [4] above, wherein k in formula (4) is 1 or 2. [6] The optical film as described in any one of [3] to [5] above, wherein R ¹ in formula (4) represents a perfluoroalkyl group having 1 to 12 carbon atoms, and n is 1 or 2. [7] The optical film as described in any one of [1] to [6] above, wherein the structural unit represented by the formula (1) and/or the structural unit represented by the formula (2) includes the formula (5) Denote the divalent organic group as X, [化4]

[In formula (5), Ar ² represents a divalent aromatic group that may have a substituent, V represents a single bond, -O-, diphenylmethylene, stilbene, a divalent hydrocarbon group with 1 to 12 carbons, -SO ₂ -, -S-, -CO-, -PO-, -PO ₂ -, -N(R ^a )- or -Si(R ^b ) ₂ -, where the hydrocarbon group may include an alicyclic structure the hydrogen atom contained in the hydrocarbon group each independently may be substituted by a halogen atom, R ^a and R ^b each independently represent a hydrogen atom, or a hydrocarbon group may be substituted with the halogen atom of from 1 to 12 carbon atoms, m represents 0 to 3, Integer, * means bonding key]. [8] The optical film as described in [7] above, wherein m in the formula (5) is 1. [9] The optical film as described in any one of [1] to [6] above, wherein the structural unit represented by the formula (1) and/or the structural unit represented by the formula (2) includes the formula (5a) Denote the divalent organic group as X, [化5]

[In formula (5), R ² represents a fluoroalkyl group having 1 to 12 carbon atoms, and p and q independently represent an integer of 1 to 4, and when p and/or q represent an integer of 2 to 4 , A plurality of R ² may be the same or different from each other, * indicates a bonding bond]. [10] The optical film as described in any one of claims 1 to 6, wherein the structural unit represented by formula (1) and/or the structural unit represented by formula (2) includes the two represented by formula (5c) Valence organic group as X, [化6]

[* in formula (5c) represents a bonding bond]. [11] The optical film as described in any one of [1] to [10] above, which has a thickness of 10 to 200 μm. [12] A flexible display device comprising the film described in any one of [1] to [11] above. [13] The flexible display device described in [12] above, which further includes a touch sensor. [14] The flexible display device as described in [12] or [13] above, which further includes a polarizing plate. [15] A polyamide imine resin having at least a structural unit represented by formula (1): [化7]

[In formula (1), Ar ¹ represents a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbons, and X represents a divalent organic group], and includes the aromatic group represented by formula (4) as formula ( 1) Ar ^{1 in} : [化 8]

[In formula (4), R ¹ represents a fluoroalkyl group having 1 to 12 carbon atoms, and n and k independently represent an integer of 1 to 4, where n and/or k represent an integer of 2 to 4 , A plurality of R ¹ may be the same or different from each other, * represents a bonding bond]; and the structural unit represented by formula (2): [化9]

[In formula (2), X represents a divalent organic group and Y represents a tetravalent organic group], and the weight average molecular weight is 200,000 to 1,000,000. [Effects of Invention]

The optical film of the present invention has a high elastic modulus and a low humidity expansion rate.

Hereinafter, embodiments of the present invention will be described in detail. In addition, the scope of the present invention is not limited to the embodiments described here, and various changes can be made without departing from the spirit of the present invention.

[式(1)中，Ar¹ 表示具有碳數1～12之氟烷基之二價芳香族基，X表示二價有機基]、 及式(2)所表示之結構單元： [化11]

[式(2)中，X表示二價有機基，Y表示四價有機基]， 且重量平均分子量為200,000～1,000,000。式(1)所表示之結構單元係二羧酸化合物與二胺化合物進行反應而形成之結構單元，式(2)所表示之結構單元係四羧酸化合物與二胺化合物進行反應而形成之結構單元。本發明之光學膜中所含之聚醯胺醯亞胺系樹脂可具有式(1)所表示之1種結構單元，亦可具有式(1)所表示之2種以上之結構單元。同樣地，該聚醯胺醯亞胺系樹脂可具有式(2)所表示之1種結構單元，亦可具有式(2)所表示之2種以上之結構單元。於本說明書中，將式(1)所表示之結構單元稱為「結構單元(1)」，亦將式(2)所表示之結構單元稱為「結構單元(2)」。再者，式(1)及式(2)中，虛線所表示之鍵表示與鄰接之結構單元鍵結之鍵結鍵。於本說明書中，其他化學結構式中之虛線所表示之鍵亦同樣地表示與鄰接之結構單元或基鍵結之鍵結鍵。The optical film of the present invention comprises the following polyamide imine resin, which has at least the structural unit represented by formula (1): [化10]

[In formula (1), Ar ¹ represents a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbon atoms, and X represents a divalent organic group], and the structural unit represented by formula (2): [化11]

[In formula (2), X represents a divalent organic group and Y represents a tetravalent organic group], and the weight average molecular weight is 200,000 to 1,000,000. The structural unit represented by formula (1) is a structural unit formed by the reaction of a dicarboxylic acid compound and a diamine compound, and the structural unit represented by formula (2) is a structure formed by the reaction of a tetracarboxylic acid compound and a diamine compound unit. The polyimide-based resin contained in the optical film of the present invention may have one type of structural unit represented by formula (1), or may have two or more types of structural unit represented by formula (1). Similarly, the polyimide-based resin may have one type of structural unit represented by formula (2), or may have two or more types of structural unit represented by formula (2). In this specification, the structural unit represented by formula (1) is referred to as "structural unit (1)", and the structural unit represented by formula (2) is also referred to as "structural unit (2)". Furthermore, in formulas (1) and (2), the bond represented by the broken line represents the bonding bond to the adjacent structural unit. In this specification, bonds represented by dotted lines in other chemical structural formulae also represent bonding bonds to adjacent structural units or groups.

In the above-mentioned optical film of the present invention comprising a polyamideimide resin having a structural unit (1) and a structural unit (2) with a weight average molecular weight of 200,000-1,000,000, the elastic modulus can be increased and the The reason for the humidity expansion rate is not clear, but it is thought that in the skeleton of the polyamide imide resin with a specific weight average molecular weight, Ar ¹ in the above formula (1) is a halothane with 1 to 12 carbon atoms The divalent aromatic group of the group, whereby the specific part in the skeleton of the polyimide-based resin has moderate rigidity and intermolecular repulsion. As a result, it is surprisingly thought that the improvement of the elastic modulus and the reduction of the humidity expansion rate of the optical film containing the polyamideimide-based resin are achieved. The humidity expansion rate is an index indicating the degree of expansion and contraction of the optical film in the plane direction under a load. It is clear that the molecular structure of the polyimide resin constituting the optical film greatly affects the humidity expansion rate. Moreover, it is clarified that if only the structure with halogen atoms is added, it is difficult to realize the high elastic modulus and low humidity expansion rate of the optical film at the same time. In the present invention, it has been found that a polyamide having at least a structural unit (1) and a structural unit (2) containing a divalent aromatic group with a carbon number of 1-12 fluoroalkyl groups, and a weight average molecular weight in a specific range The optical film of amine imine resin can obtain an optical film with both high elastic modulus and low humidity expansion rate.

The polyimide-based resin contained in the optical film of the present invention has a structural unit (1) and a structural unit (2). From the viewpoint that it is easy to increase the elastic modulus of the optical film and decrease the humidity expansion rate, the total of the structural unit (1) and the structural unit (2) contained in the polyimide-based resin is set to 100 In mole%, the ratio of structural unit (1) is preferably 20-99 mole%, more preferably 30-98 mole%, still more preferably 40-95 mole%, particularly preferably 50-93 mole% ear%. When the ratio of the structural unit (1) is above the above lower limit, it is easy to increase the elastic modulus of the optical film, and it is easy to reduce the humidity expansion rate. Moreover, when the ratio of the structural unit (1) is below the above upper limit, it is easy to ensure the solubility of the resin in the solvent. Furthermore, the content of the structural unit (1) and the structural unit (2) can be measured using ¹ H-NMR (Nuclear Magnetic Resonance), or can also be calculated based on the addition ratio of the raw materials.

In the polyimide imine resin, the content of the structural unit represented by formula (1) is preferably 0.1 mol or more, more preferably 0.5 mol relative to 1 mol of the structural unit represented by formula (2) Ear or more, more preferably 1.0 mol or more, more preferably 1.5 mol or more, and preferably 6.0 mol or less, more preferably 5.0 mol or less, and still more preferably 4.5 mol or less. If the content of the structural unit represented by the formula (1) is more than the above lower limit, it is easy to increase the elastic modulus of the optical film, and it is easy to reduce the humidity expansion rate. Moreover, if the content of the structural unit represented by the formula (1) is below the above upper limit, the increase in the viscosity caused by the hydrogen bond between the amide bonds in the formula (1) is suppressed, and the processability of the optical film is easily improved.

Ar ¹ in the structural unit (1) represents a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbon atoms. In addition, in this specification, the so-called divalent aromatic group means that two hydrogen atoms of a monocyclic aromatic ring, a condensed polycyclic aromatic ring, or an assembling aromatic ring are substituted with a bonding group. The divalent aromatic group may include an aromatic ring that uses only carbon atoms to form a ring (monocyclic, condensed polycyclic, or collective ring), and may also include a heteroaromatic ring that includes atoms other than carbon atoms to form a ring. Examples of atoms other than carbon atoms include nitrogen atoms, sulfur atoms, and oxygen atoms. The total number of carbon atoms and atoms other than carbon atoms forming the aromatic ring is not particularly limited, but is preferably 5-18, more preferably 5-14, and still more preferably 5-12.

Examples of the monocyclic aromatic ring include benzene, furan, pyrrole, thiophene, pyridine, imidazole, pyrazole, azole, thiazole, imidazoline, and the like.

Examples of the condensed polycyclic aromatic ring include naphthalene, anthracene, phenanthrene, indole, benzothiazole, benzimidazole, and benzoxazole.

As an assembling aromatic ring, two or more monocyclic aromatic rings and/or condensed polycyclic aromatic rings are connected by a single bond. As an example, monocyclic aromatic Examples of cyclic or condensed polycyclic aromatic rings, and two or more of the rings described above are connected by a single bond, such as biphenyl, terphenyl, bitetraphenyl, binaphthyl, 1-phenyl Naphthalene, 2-phenylnaphthalene, bipyridine, etc.

From the viewpoints that it is easy to increase the elastic modulus of the optical film and decrease the humidity expansion rate, the divalent aromatic group having a fluoroalkyl group having 1 to 12 carbon atoms is preferably one having a fluoroalkyl group having 1 to 12 carbon atoms. The two hydrogen atoms of the aromatic hydrocarbon ring are replaced with bonding groups, more preferably the two hydrogen atoms of benzene, biphenyl, terphenyl or bitetraphenyl having a C1-12 fluoroalkyl group are The group substituted with a bonding bond is more preferably a group in which two hydrogen atoms of benzene or biphenyl having a fluoroalkyl group having 1 to 12 carbons are substituted with a bonding bond.

In the formula (1), the fluoroalkyl group having 1 to 12 carbon atoms in Ar ¹ is a group in which at least one hydrogen atom of a linear or branched alkyl group having 1 to 12 carbon atoms is substituted with a fluorine atom. Examples of the linear or branched fluoroalkyl group having 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, N-pentyl, 2-methylbutyl, 3-methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, tertiary octyl, n-nonyl and n-decyl, etc. At least one hydrogen atom is substituted by a fluorine atom. Specific examples of fluoroalkyl groups having 1 to 12 carbon atoms include fluoromethyl, difluoromethyl, trifluoromethyl, fluoroethyl, difluoroethyl, trifluoroethyl, and pentafluoroethyl. Group, heptafluoropropyl, nonafluorobutyl, etc. The number of carbon atoms of the fluoroalkyl group is preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 or 2.

From the viewpoints that it is easy to increase the elastic modulus of the optical film and easily reduce the humidity expansion rate, the fluoroalkyl group having 1 to 12 carbons is preferably a perfluoroalkyl group having 1 to 12 carbons, and more preferably is a perfluoroalkyl group having 1 to 12 carbons. The perfluoroalkyl group of 6 is more preferably a perfluoroalkyl group having 1 to 4 carbon atoms, and particularly preferably a trifluoromethyl group or a pentafluoroethyl group.

Ar ¹ in formula (1) only needs to have at least one fluoroalkyl group with 1 to 12 carbon atoms, and the number is not particularly limited. It is easy to increase the elastic modulus of the optical film and decrease the humidity expansion rate. In other words, the number of fluoroalkyl groups having 1 to 12 carbon atoms in Ar ¹ is preferably 1 to 4, more preferably 1 to 2. When Ar ¹ in the formula (1) has two or more fluoroalkyl groups having 1 to 12 carbon atoms, these may be the same or different from each other.

In addition to the fluoroalkyl group having 1 to 12 carbon atoms, Ar ¹ in the formula (1) may further have other substituents. Examples of other substituents include alkyl groups having 1 to 6 carbon atoms, alkoxy groups having 1 to 6 carbon atoms, or aryl groups having 6 to 12 carbon atoms.

[式(4)中， R¹ 相互獨立地表示碳數1～12之氟烷基， n及k相互獨立地表示1～4之整數，其中，於n及/或k表示2～4之整數之情形時，複數個存在之R¹ 相互可相同亦可不同， *表示鍵結鍵]。 於結構單元(1)包含式(4)所表示之二價芳香族基作為Ar¹ 之情形時，結構單元(1)中，作為Ar¹ ，可包含式(4)所表示之1種或2種以上之芳香族基，除式(4)所表示之芳香族基以外，亦可包含不符合式(4)所表示之芳香族基之具有氟烷基之其他芳香族基。In a preferred aspect of the present invention, from the viewpoint of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit represented by formula (1) includes the bivalent formula (4) The aromatic group is used as Ar ¹ , [化12]

[In formula (4), R ¹ independently represents a fluoroalkyl group having 1 to 12 carbon atoms, n and k independently represent an integer of 1 to 4, wherein n and/or k represent an integer of 2 to 4 In this case, a plurality of R ¹ may be the same or different from each other, and * represents a bonding bond]. When the structural unit (1) contains the divalent aromatic group represented by the formula (4) as Ar ¹ , in the structural unit (1), as Ar ¹ , one or 2 of the formula (4) may be contained In addition to the aromatic group represented by the formula (4), the aromatic group of more than one kind may also include other aromatic groups having a fluoroalkyl group that do not conform to the aromatic group represented by the formula (4).

The polyimide-based resin contained in the optical film of the present invention has at least a structural unit (1) and a structural unit (2) as described above, and the resin usually has a plurality of structural units (1) and a plurality of structures Unit (2) and any other structural units. In this specification, the so-called structural unit (1) containing the aromatic group represented by formula (4) as Ar ¹ means that among the plurality of structural units (1) possessed by the polyimide-based resin, at least Ar ¹ in a part of structural unit (1) is represented by formula (4). The above record also conforms to the same other records in this manual.

As the fluoroalkyl group having 1 to 12 carbon atoms in R ¹ , the above description regarding the fluoroalkyl group having 1 to 12 carbon atoms in Ar ¹ is the same, and the preferred description is also the same.

n and k independently represent an integer of 1 to 4. From the viewpoint of optical characteristics, n is preferably an integer of 1 or 2, more preferably 1. From the viewpoint of the modulus of elasticity, k is preferably an integer of 1 or 2, and more preferably 1. Here, when n and/or k represent an integer from 2 to 4, a plurality of R ¹ may be the same or different from each other. From the viewpoint of solubility in a solvent, R ¹ They are preferably the same as each other. From the viewpoint that it is easy to increase the elastic modulus of the optical film and decrease the humidity expansion rate, it is more preferable that k is 1 and n is 2, or k is 2 and n is 1.

Regarding the two bonding bonds in formula (4), the mutual position is not particularly limited. It can be any one of ortho, meta, and counter positions, which can easily increase the elastic modulus of the optical film and reduce the humidity expansion. From the viewpoint of efficiency, the bonding bonds are preferably in opposite positions.

As a preferable example of the divalent aromatic group represented by the formula (4), R ¹ in the formula (4) represents a perfluoroalkyl group having 1 to 12 carbons, k is 1 or 2, n is 1, or 2. And/or two aromatic groups whose bonding bonds are in the para position with each other.

The present invention in which the structural unit represented by formula (1) contained in the polyamide imine-based resin contained in the optical film of the present invention contains the divalent aromatic group represented by formula (4) as Ar ¹ In one of the preferred aspects, in terms of the ease of increasing the elastic modulus of the optical film and the ease of reducing the humidity expansion rate, the structure represented by the formula (1) contained in the polyimide resin When the total of the units is set to 100 mol%, the ratio of the structural unit in which Ar ¹ in formula (1) is a divalent aromatic group represented by formula (4) is preferably 70-100 mol%, more preferably 80-100 mol%, more preferably 90-100 mol%, in all the structural units represented by formula (1), Ar ¹ may be a divalent aromatic group represented by formula (4).

[式(4a)中，R³ ～R⁶ 相互獨立地表示氫原子或碳數1～12之氟烷基，其中，R³ ～R⁶ 之至少1個表示碳數1～12之氟烷基，k表示1～4之整數，*表示鍵結鍵]。 就容易提高光學膜之彈性模數，容易降低濕度膨脹率之觀點而言，於式(4a)中之k為1之情形時，R³ ～R⁶ 之至少1個表示碳數1～12之氟烷基，較佳為R³ ～R⁶ 之至少2個表示碳數1～12之氟烷基，更佳為至少R³ 及R⁵ 表示碳數1～12之氟烷基，且R³ 及R⁵ 表示碳數1～12之氟烷基，進而較佳為R⁴ 及R⁶ 表示氫原子。就容易提高光學膜之彈性模數，容易降低濕度膨脹率之觀點而言，於式(4a)中之k為2之情形時，若將第1苯環上之基設為R³ ～R⁶ ，將第2苯環上之基設為R^3' ～R^6' ，則較佳為R³ ～R⁶ 及R^3' ～R^6' 之至少2個表示碳數1～12之氟烷基，更佳為存在於接近將2個苯環鍵結之單鍵之位置的至少R⁴ 及R^6' 表示碳數1～12之氟烷基，進而較佳為R⁴ 及R^6' 表示碳數1～12之氟烷基，且R³ 、R⁵ 、R⁶ 及R^3' ～R^5' 表示氫原子。作為碳數1～12之氟烷基，與Ar¹ 中之碳數1～12之氟烷基相關之上述記載同樣地符合，且較佳之記載亦同樣地符合。就容易提高光學膜之彈性模數，容易降低濕度膨脹率之觀點而言，式(4a)中之k較佳為1或2之整數。就容易提高光學膜之鉛筆硬度之觀點而言，式(4a)中之k較佳為2～4之整數，更佳為2或3，進而較佳為2。As a preferable example of the divalent aromatic group represented by the formula (4), the aromatic group represented by the formula (4a) in which the bonding bonds in the formula (4) are in the para position with each other: [化 13]

[In formula (4a), R ³ to R ⁶ independently represent a hydrogen atom or a fluoroalkyl group with 1 to 12 carbons, wherein at least one of R ³ to R ⁶ represents a fluoroalkyl group with 1 to 12 carbons , K represents an integer from 1 to 4, * represents a bonding bond]. From the viewpoint that it is easy to increase the elastic modulus of the optical film and decrease the humidity expansion rate, when k in formula (4a) is 1, at least one of R ³ to R ⁶ represents a carbon number of 1 to 12 The fluoroalkyl group is preferably at least two of R ³ to R ⁶ representing a fluoroalkyl group having 1 to 12 carbons, more preferably at least R ³ and R ⁵ represent a fluoroalkyl group having 1 to 12 carbons, and R ³ And R ⁵ represents a fluoroalkyl group having 1 to 12 carbon atoms, and it is more preferable that R ⁴ and R ⁶ represent a hydrogen atom. From the viewpoint that it is easy to increase the elastic modulus of the optical film and decrease the humidity expansion rate, when k in formula (4a) is 2, if the group on the first benzene ring is set to R ³ ～R ⁶ , the second group on the benzene ring to R ^{3 '~} R ^6', then preferably R ³ ~ R ^6, and R ^{3 '~} R ^6' is at least two fluoroalkyl group having a carbon number of 1 to 12 , more preferably at least present in proximity to the position of R ⁴ and R ⁶ is a single bond of two benzene rings bonded to the ^'represents a fluoroalkyl group having a carbon number of 1 to 12, further preferably R ⁴ and R ^6' represents a carbon the number of the fluoroalkyl group having 1 to 12, and R ^3, R ^5, R ^6, and R ^{3 '~} R ^5' represents a hydrogen atom. As the fluoroalkyl group having 1 to 12 carbon atoms, the above description regarding the fluoroalkyl group having 1 to 12 carbon atoms in Ar ¹ is met in the same way, and the preferred description is also met in the same way. From the viewpoint that it is easy to increase the elastic modulus of the optical film and decrease the humidity expansion rate, k in formula (4a) is preferably an integer of 1 or 2. From the viewpoint of easy improvement of the pencil hardness of the optical film, k in the formula (4a) is preferably an integer of 2 to 4, more preferably 2 or 3, and even more preferably 2.

X in structural unit (1) and structural unit (2) represents a divalent organic group, preferably represents a divalent organic group with 4 to 40 carbons, more preferably represents a cyclic structure with 4 to 40 carbons Divalent organic base. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. Regarding the above-mentioned organic group, the hydrogen atom in the organic group may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. In this case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1-8. In one embodiment of the present invention, in the structural units (1) and (2) contained in the polyimide-based resin, as X, one type of organic group may be included, or two or more types of organic groups may be included. base.

[式(5)中， Ar² 表示可具有取代基之二價芳香族基， V表示單鍵、-O-、二苯基亞甲基、茀基、碳數1～12之二價烴基、-SO₂ -、-S-、-CO-、-PO-、-PO₂ -、-N(R^a )-或-Si(R^b )₂ -，此處，該烴基可包含脂環式結構，該烴基中所含之氫原子可相互獨立地經鹵素原子取代，R^a 及R^b 相互獨立地表示氫原子、或可經鹵素原子取代之碳數1～12之烴基， m表示0～3之整數， *表示鍵結鍵]。 於結構單元(1)及結構單元(2)包含式(5)所表示之二價有機基作為X之情形時，結構單元(1)及結構單元(2)可包含式(5)所表示之1種或2種以上之二價有機基作為X。結構單元(1)及結構單元(2)中，作為X，除式(5)所表示之二價有機基以外，亦可包含不符合式(5)所表示之二價有機基之其他二價有機基。In a preferred aspect of the present invention, from the viewpoints of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit represented by formula (1) and the structural unit represented by formula (2) Include the divalent organic group represented by formula (5) as X, [formation 14]

[In formula (5), Ar ² represents a divalent aromatic group that may have a substituent, V represents a single bond, -O-, diphenylmethylene, stilbene, a divalent hydrocarbon group with 1 to 12 carbons, -SO ₂ -, -S-, -CO-, -PO-, -PO ₂ -, -N(R ^a )- or -Si(R ^b ) ₂ -, where the hydrocarbon group may include an alicyclic structure the hydrogen atom contained in the hydrocarbon group each independently may be substituted by a halogen atom, R ^a and R ^b each independently represent a hydrogen atom, or a hydrocarbon group may be substituted with the halogen atom of from 1 to 12 carbon atoms, m represents 0 to 3, Integer, * means bonding key]. When the structural unit (1) and the structural unit (2) include the divalent organic group represented by the formula (5) as X, the structural unit (1) and the structural unit (2) may include the formula (5) One or more divalent organic groups are used as X. In structural unit (1) and structural unit (2), as X, in addition to the divalent organic group represented by formula (5), other divalent organic groups that do not conform to the divalent organic group represented by formula (5) may also be included. Organic base.

Ar ² in formula (5) represents a divalent aromatic group which may have a substituent. The divalent aromatic group is a monocyclic aromatic ring, a condensed polycyclic aromatic ring, or a condensed aromatic ring. Two hydrogen atoms are substituted into a bond group, and the monocyclic aromatic in Ar ¹ Examples and preferred descriptions related to the ring, condensed polycyclic aromatic ring, or assembling aromatic ring are similarly consistent with the monocyclic aromatic ring, condensed polycyclic aromatic ring, or assembling aromatic ring in Ar ² . In the case where m in formula (5) is 1 or more, plural existing Ar ² may be the same or different from each other.

From the viewpoint of easy improvement of the elastic modulus of the optical film and easy reduction of the humidity expansion rate, the divalent aromatic group which may have a substituent is preferably an aromatic hydrocarbon ring which may have a substituent. 2 hydrogen atoms are substituted with The bond-bonding group is more preferably benzene, which may have substituents, biphenyl, terphenyl or bitetraphenyl, where two hydrogen atoms are substituted for bonding bonds, and more preferably benzene that may have substituents Or the two hydrogen atoms of biphenyl are replaced with bonding groups.

Examples of the substituents in Ar ² include halogen groups, alkyl groups having 1 to 12 carbons, alkoxy groups having 1 to 6 carbons, or aryl groups having 6 to 12 carbons, or hydrogen contained in these groups. A group in which the atom is substituted by a halogen atom.

The C1-C12 alkyl group may be a C1-C12 linear or branched alkyl group, preferably a C1-C6 linear or branched alkyl group. Examples of such groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, n-pentyl, 2-methylbutyl, 3- Methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, tertiary octyl, n-nonyl and n-decyl, etc.

Examples of alkoxy groups having 1 to 6 carbon atoms include: methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tertiary butoxy, and pentoxy , Hexyloxy, cyclohexyloxy, etc.

Examples of aryl groups having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, naphthyl, biphenyl and the like.

As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned.

The substituent in Ar ² is preferably a halogen group or an alkyl group having 1 to 12 carbon atoms in which a hydrogen atom can be substituted by a halogen atom, and more preferably a methyl group, a fluoro group, a chloro group or a trifluoromethyl group.

V in the formula (5) represents a single bond, -O-, diphenylmethylene, stilbene, a divalent hydrocarbon group with 1 to 12 carbons, -SO ₂ -, -S-, -CO-, -PO -, -PO ₂ -, -N(R ^a )- or -Si(R ^b ) ₂ -. Here, the hydrocarbyl group may include an alicyclic structure, the hydrogen atoms contained in the hydrocarbyl group may be independently substituted by a halogen atom, and R ^a and R ^b independently represent a hydrogen atom or the number of carbons that may be substituted by a halogen atom 1-12 monovalent hydrocarbon group. Examples of monovalent hydrocarbon groups with 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, n-pentyl, 2-methyl Butyl, 3-methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, tertiary octyl, n-nonyl, n-decyl, etc., which can be substituted by halogen atoms . As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned. From the viewpoints that it is easy to improve the elastic modulus and bending resistance of the optical film, and it is easy to reduce the humidity expansion rate, V in formula (5) is preferably a single bond, -O- or -S-, and more preferably a single bond Or -O-, more preferably a single bond.

In formula (5), m represents an integer of 0 to 3. From the viewpoint of easy improvement of the elastic modulus of the optical film and easy reduction of the humidity expansion rate, it is preferably 0 to 2, more preferably 0 or 1, and more Best is 1.

The present invention in which the structural unit (1) and the structural unit (2) contained in the polyamideimide resin contained in the optical film of the present invention include the divalent organic group represented by the formula (5) as X In one of the preferred aspects, from the viewpoint of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit (1) and the structural unit contained in the polyimide resin When the total of (2) is set to 100 mol%, X in formula (1) is the structural unit of the divalent organic group represented by formula (5) and X in formula (2) is represented by formula (5) The total ratio of the structural units of the divalent organic group is preferably 70-100 mol%, more preferably 80-100 mol%, and further preferably 90-100 mol%, in terms of structural unit (1) and structure In all the structural units of unit (2), X may be a divalent organic group represented by formula (5).

[式(5a)中， R² 表示碳數1～12之氟烷基， p及q相互獨立地表示1～4之整數，其中，於p及/或q表示2～4之整數之情形時，複數個存在之R² 相互可相同亦可不同， *表示鍵結鍵]。 再者，式(5a)所表示之二價有機基係包含於式(5)所表示之二價有機基中之基，具體而言，式(5)中之V表示單鍵，Ar² 表示經碳數1～12之氟烷基(R² )取代之苯環，係相當於m表示0～3之整數之二價有機基之基。於結構單元(1)及結構單元(2)包含式(5a)所表示之二價有機基作為X之情形時，結構單元(1)及結構單元(2)可包含式(5a)所表示之1種或2種以上之二價有機基作為X。結構單元(1)及結構單元(2)中，作為X，除式(5a)所表示之二價有機基以外，亦可包含不符合式(5a)所表示之二價有機基之其他二價有機基。In a preferred aspect of the present invention, from the viewpoints of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit represented by formula (1) and the structural unit represented by formula (2) Include the divalent organic group represented by formula (5a) as X, [formation 15]

[In formula (5a), R ² represents a fluoroalkyl group having 1 to 12 carbon atoms, and p and q represent an integer of 1 to 4 independently of each other, where p and/or q represent an integer of 2 to 4 , A plurality of R ² may be the same or different from each other, * indicates a bonding bond]. Furthermore, the divalent organic group represented by formula (5a) is a group contained in the divalent organic group represented by formula (5). Specifically, V in formula (5) represents a single bond, and Ar ² represents The benzene ring substituted with a fluoroalkyl group (R ² ) having 1 to 12 carbon atoms is equivalent to a divalent organic group in which m represents an integer of 0 to 3. When the structural unit (1) and the structural unit (2) include the divalent organic group represented by the formula (5a) as X, the structural unit (1) and the structural unit (2) may include the formula (5a) One or more divalent organic groups are used as X. In structural unit (1) and structural unit (2), as X, in addition to the divalent organic group represented by formula (5a), other divalent organic groups that do not conform to the divalent organic group represented by formula (5a) Organic base.

R ² in the formula (5a) represents a fluoroalkyl group having 1 to 12 carbons, and as this group, it is the same as the above description regarding the fluoroalkyl group having 1 to 12 carbons in Ar ¹ , and the preferred description is also Same match.

p and q represent an integer of 1 to 4 independently of each other. From the viewpoint of the elastic modulus and humidity expansion rate of the optical film, p is preferably an integer of 1 or 2, and more preferably 2. From the viewpoint of the elastic modulus and humidity expansion rate of the optical film, q is preferably an integer of 1 or 2, and more preferably 1. Here, when p and/or q represent an integer of 2 to 4, the plural existing R ² may be the same or different from each other, and it is preferable that the plural existing R ² are the same.

Regarding the two bonding bonds in formula (5a), the mutual position is not particularly limited, and it can be any of ortho, meta, and para, from the viewpoint of the elastic modulus and humidity expansion rate of the optical film In other words, the bonding keys are preferably positioned opposite each other.

As a preferable example of the divalent aromatic group represented by the formula (5a), R ² in the formula (5a) represents a perfluoroalkyl group having 1 to 12 carbon atoms, p is 2, q is 1 or 2, And/or two aromatic groups whose bonding bonds are in the para position with each other.

The present invention in which the structural unit (1) and the structural unit (2) contained in the polyamide imine-based resin contained in the optical film of the present invention include the divalent organic group represented by formula (5a) as X In one of the preferred aspects, from the viewpoint of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit (1) and the structural unit contained in the polyimide resin When the total of (2) is set to 100 mol%, X in formula (1) is the structural unit of the divalent organic group represented by formula (5a) and X in formula (2) is represented by formula (5a) The total ratio of the structural units of the divalent organic group is preferably 70-100 mol%, more preferably 80-100 mol%, and further preferably 90-100 mol%, in terms of structural unit (1) and structure In all the structural units of the unit (2), X may be a divalent organic group represented by the formula (5a).

[式(5b)中，R⁷ ～R¹⁴ 相互獨立地表示氫原子或碳數1～12之氟烷基，其中，R⁷ ～R¹⁴ 之至少1個基表示碳數1～12之氟烷基，*表示鍵結鍵]。 再者，式(5b)所表示之二價芳香族基係相當於式(5a)中之鍵結鍵相互位於對位，且p為2之芳香族基之基。就容易提高光學膜之彈性模數，容易降低濕度膨脹率之觀點而言，式(5b)中，較佳為R⁷ ～R¹⁴ 之至少2個表示碳數1～12之氟烷基，更佳為至少R⁸ 及R¹⁴ 表示碳數1～12之氟烷基，進而較佳為R⁸ 及R¹⁴ 表示碳數1～12之氟烷基，且R⁷ 、R⁹ 、R¹⁰ 、R¹¹ 、R¹² 及R¹³ 表示氫原子。又，於上述態樣中，碳數1～12之氟烷基較佳為碳數1～12之全氟烷基，更佳為碳數1～6之全氟烷基，進而較佳為碳數1～4之全氟烷基，進而更佳為三氟甲基或五氟乙基，尤佳為三氟甲基。In a preferred aspect of the present invention, from the viewpoints of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit represented by formula (1) and the structural unit represented by formula (2) Include the divalent aromatic group represented by formula (5b) as X, [formation 16]

[In formula (5b), R ⁷ to R ¹⁴ independently represent a hydrogen atom or a fluoroalkyl group having 1 to 12 carbons, wherein at least one group of R ⁷ to R ¹⁴ represents a fluoroalkane having 1 to 12 carbons Base, * means bonding key]. Furthermore, the divalent aromatic group represented by the formula (5b) corresponds to the group of the aromatic group in which the bonding bonds in the formula (5a) are in the para position with each other, and p is 2. From the viewpoint of easily increasing the elastic modulus of the optical film and reducing the humidity expansion rate, in formula (5b), it is preferred that at least two of R ⁷ to R ¹⁴ represent a fluoroalkyl group having 1 to 12 carbon atoms, and more Preferably, at least R ⁸ and R ¹⁴ represent a fluoroalkyl group having 1 to 12 carbons, more preferably R ⁸ and R ¹⁴ represent a fluoroalkyl group having 1 to 12 carbons, and R ⁷ , R ⁹ , R ¹⁰ , and R ¹¹ , R ¹² and R ¹³ represent a hydrogen atom. Furthermore, in the above aspect, the fluoroalkyl group having 1 to 12 carbons is preferably a perfluoroalkyl group having 1 to 12 carbons, more preferably a perfluoroalkyl group having 1 to 6 carbons, and more preferably carbon The perfluoroalkyl group has a number of 1 to 4, more preferably trifluoromethyl or pentafluoroethyl, and particularly preferably trifluoromethyl.

The present invention in which the structural unit (1) and the structural unit (2) contained in the polyamidoimide resin contained in the optical film of the present invention include the divalent organic group represented by the formula (5b) as X In one of the preferred aspects, from the viewpoint of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit (1) and the structural unit contained in the polyimide resin When the total of (2) is set to 100 mol%, X in formula (1) is the structural unit of the divalent organic group represented by formula (5b) and X in formula (2) is represented by formula (5b) The total ratio of the structural units of the divalent organic group is preferably 70-100 mol%, more preferably 80-100 mol%, and further preferably 90-100 mol%, in terms of structural unit (1) and structure In all the structural units of unit (2), X may be a divalent organic group represented by formula (5b).

[式(5c)中之*表示鍵結鍵]。 再者，式(5c)所表示之二價有機基係相當於式(5b)中之R⁹ 及R¹¹ 表示三氟甲基，且R⁷ 、R⁸ 、R¹⁰ 、R¹² 、R¹³ 及R¹⁴ 表示氫原子之二價芳香族基之基。於結構單元(1)及結構單元(2)包含式(5c)所表示之二價有機基作為X之情形時，結構單元(1)及結構單元(2)中，作為X，除式(5c)所表示之二價有機基以外，亦可包含不符合式(5c)所表示之二價有機基之其他二價有機基。In a preferred aspect of the present invention, from the viewpoint of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit represented by formula (1) includes the divalent formula (5c) The organic group is used as X, [化17]

[* in formula (5c) represents a bonding bond]. Furthermore, the divalent organic group represented by the formula (5c) corresponds to the formula (5b) where R ⁹ and R ¹¹ represent trifluoromethyl, and R ⁷ , R ⁸ , R ¹⁰ , R ¹² , R ¹³ and R ¹⁴ represents a divalent aromatic group of a hydrogen atom. When structural unit (1) and structural unit (2) contain the divalent organic group represented by formula (5c) as X, in structural unit (1) and structural unit (2), as X, except for formula (5c) In addition to the divalent organic group represented by ), other divalent organic groups that do not conform to the divalent organic group represented by formula (5c) may also be included.

The present invention in which the structural unit (1) and the structural unit (2) contained in the polyamidoimide resin contained in the optical film of the present invention include the divalent organic group represented by the formula (5c) as X In one of the preferred aspects, from the viewpoint of easily increasing the elastic modulus of the optical film and easily reducing the humidity expansion rate, the structural unit (1) and the structural unit contained in the polyimide resin When the total of (2) is set to 100 mol%, X in formula (1) is the structural unit of the divalent organic group represented by formula (5c) and X in formula (2) is represented by formula (5c) The total ratio of the structural units of the divalent organic group is preferably 70-100 mol%, more preferably 80-100 mol%, and further preferably 90-100 mol%, in terms of structural unit (1) and structure In all the structural units of the unit (2), X may be a divalent organic group represented by the formula (5c).

Y in the structural unit represented by formula (2) represents a tetravalent organic group, preferably represents a tetravalent organic group with 4 to 40 carbons, more preferably represents a tetravalent organic group with 4 to 40 carbons having a cyclic structure Organic base. Examples of the cyclic structure include alicyclic, aromatic, and heterocyclic structures. The above-mentioned organic groups are those in which the hydrogen atoms in the organic groups may be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. In this case, the carbon number of the hydrocarbon group and the fluorine-substituted hydrocarbon group is preferably 1-8. In one embodiment of the present invention, in the structural unit (2), as Y, there may be one type of tetravalent organic group, or two or more types of tetravalent organic group. Examples of Y include: formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), and formula (28) And the group represented by the formula (29); the hydrogen atom in the group represented by the formula (20) to the formula (29) is substituted by a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a tetravalent group Chain hydrocarbon group with carbon number 6 or less.

[化18]

In formulas (20) to (29), * represents a bonding bond, W ¹ represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C (CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, -Ar ³ -O-Ar ³ -, -Ar ^{3 _{-CH 2 -Ar 3 -, - Ar}} 3 -C (CH 3) 2 -Ar 3 - or -Ar ³ -SO ₂ -Ar ³ -. Ar ³ represents an arylene group having 6 to 20 carbon atoms in which a hydrogen atom can be substituted with a fluorine atom, and a specific example includes a phenylene group. When there are a plurality of Ar ³ , Ar ³ may be the same or different from each other.

Among the bases represented by formulas (20) to (29), from the viewpoint of the elastic modulus, surface hardness, and bending resistance of the optical film, formulas (26), (28), or ( The group represented by 29) is more preferably the group represented by formula (26). In addition, from the viewpoint that the elastic modulus, surface hardness, and bending resistance of the optical film are easily improved, and the yellowness (hereinafter, also referred to as YI value) is easily reduced, W ¹ is preferably a single bond and -O independently of each other. -, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -, more preferably a single bond, -O- , -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -, more preferably a single bond, -C(CH ₃ ) ₂ -or -C (CF ₃ ) ₂ -.

[式(6)中，R¹⁸ ～R²⁵ 相互獨立地表示氫原子、碳數1～12之烷基、碳數1～6之烷氧基或碳數6～12之芳基，R¹⁸ ～R²⁵ 中所含之氫原子可相互獨立地經鹵素原子取代， *表示鍵結鍵]。 於結構單元(2)包含式(6)所表示之四價有機基作為Y之情形時，容易提高光學膜之彈性模數，容易降低濕度膨脹率。又，於該情形時，提高聚醯胺醯亞胺系樹脂向溶劑中之溶解性，容易降低含有該樹脂之清漆之黏度，容易提高光學膜之加工性。進而，容易提高光學膜之光學特性。In a preferred embodiment of the present invention, the structural unit represented by formula (2) includes the tetravalent organic group represented by formula (6) as Y, [化19]

[In formula (6), R ¹⁸ to R ²⁵ independently represent a hydrogen atom, an alkyl group with 1 to 12 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons, and R ¹⁸ to The hydrogen atoms contained in R ²⁵ can be independently substituted by halogen atoms, and * represents a bonding bond]. When the structural unit (2) contains the tetravalent organic group represented by the formula (6) as Y, it is easy to increase the elastic modulus of the optical film, and it is easy to reduce the humidity expansion rate. Furthermore, in this case, the solubility of the polyimide-based resin in the solvent is improved, the viscosity of the varnish containing the resin is easily reduced, and the processability of the optical film is easily improved. Furthermore, it is easy to improve the optical properties of the optical film.

In the formula (6), R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ independently represent a hydrogen atom, an alkyl group having 1 to 12 carbons, and a carbon number of 1 to Alkoxy group of 6 or aryl group of 6-12 carbons. Examples of alkyl groups having 1 to 6 carbons, alkoxy groups having 1 to 6 carbons, and aryl groups having 6 to 12 carbons include the alkyl groups having 1 to 12 carbons in Ar ² in formula (5) , C1-C6 alkoxy group or C6-C12 aryl group as exemplified above. R ¹⁸ to R ²⁵ independently of each other preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, where R ¹⁸ to R ²⁵ are The hydrogen atoms contained can be independently substituted by halogen atoms. As this halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned. From the viewpoints that it is easy to increase the elastic modulus of the optical film, to reduce the humidity expansion rate, and to increase the surface hardness, bending resistance and transparency, R ¹⁸ to R ²⁵ are independent of each other and are preferably hydrogen atoms, Group, fluoro group, chloro group or trifluoromethyl group, more preferably R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ and R ²⁵ are hydrogen atoms, and R ²¹ and R ²² are hydrogen atoms, methyl, A fluoro group, a chloro group or a trifluoromethyl group, particularly preferably R ²¹ and R ²² are methyl or trifluoromethyl.

The structural unit (2) contained in the polyamide imine-based resin contained in the optical film of the present invention includes the tetravalent organic group represented by formula (6) as Y, a preferred aspect of the present invention In terms of easy improvement of the elastic modulus of the optical film and easy reduction of the humidity expansion rate, when the total of the structural units (2) contained in the polyimide resin is set to 100 mol% , The ratio of Y in formula (2) to the structural unit of the tetravalent organic group represented by formula (6) is preferably 70-100 mol%, more preferably 80-100 mol%, and more preferably 90 ~100 mol%, in all structural units of structural unit (2), Y can be a tetravalent organic group represented by formula (6).

。 再者，式(6a)所表示之四價有機基相當於式(6)中之R²¹ 及R²² 為三全氟甲基，且R¹⁸ 、R¹⁹ 、R²⁰ 、R²³ 、R²⁴ 及R²⁵ 為氫原子之基。於結構單元(2)包含式(6a)所表示之四價有機基作為Y之情形時，容易提高光學膜之彈性模數，容易降低濕度膨脹率。又，於該情形時，提高聚醯胺醯亞胺系樹脂向溶劑中之溶解性，容易降低含有該樹脂之清漆之黏度，容易提高光學膜之加工性。進而，容易提高光學膜之光學特性。In a preferred embodiment of the present invention, the structural unit represented by formula (2) contains the tetravalent organic group represented by formula (6a) as Y, [化20]

. Furthermore, the tetravalent organic group represented by formula (6a) is equivalent to that R ²¹ and R ²² in formula (6) are triperfluoromethyl, and R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ and R ²⁵ is the radical of a hydrogen atom. When the structural unit (2) contains the tetravalent organic group represented by the formula (6a) as Y, it is easy to increase the elastic modulus of the optical film, and it is easy to reduce the humidity expansion rate. Furthermore, in this case, the solubility of the polyimide-based resin in the solvent is improved, the viscosity of the varnish containing the resin is easily reduced, and the processability of the optical film is easily improved. Furthermore, it is easy to improve the optical properties of the optical film.

The structural unit (2) contained in the polyamide imine-based resin contained in the optical film of the present invention includes a tetravalent organic group represented by formula (6a) as Y, a preferred aspect of the present invention In terms of easy improvement of the elastic modulus of the optical film and easy reduction of the humidity expansion rate, when the total of the structural units (2) contained in the polyimide resin is set to 100 mol% , The ratio of Y in formula (2) to the structural unit of the tetravalent organic group represented by formula (6a) is preferably 70-100 mol%, more preferably 80-100 mol%, and more preferably 90 ~100 mol%, in all the structural units of the structural unit (2), Y may be a tetravalent organic group represented by the formula (6a).

[式(3)中之Z係不符合具有碳數1～12之氟烷基之二價芳香族基之二價有機基，X'表示二價有機基]。 於聚醯胺醯亞胺系樹脂除結構單元(1)及結構單元(2)以外，且包含式(3)所表示之結構單元之情形時，容易提高光學膜之鉛筆硬度。In addition to the structural unit (1) and the structural unit (2), the polyamidoimide-based resin contained in the optical film of the present invention may also include the structural unit represented by the formula (3): [化21]

[Z in formula (3) is a divalent organic group that does not correspond to a divalent aromatic group having a carbon number of 1-12 fluoroalkyl group, and X'represents a divalent organic group]. When the polyimide imine resin contains the structural unit represented by the formula (3) in addition to the structural unit (1) and the structural unit (2), it is easy to increase the pencil hardness of the optical film.

Z in the formula (3) is not particularly limited as long as it is a divalent organic group that does not correspond to a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbons. For example, the following groups can be mentioned. A hydrocarbon group with 1 to 8 carbons or a fluorine-substituted hydrocarbon group with 1 to 8 carbons, including a cyclic structure (preferably alicyclic structure, aromatic ring structure, heterocyclic structure), a divalent carbon number of 4-40 The organic group does not correspond to the divalent aromatic group having a fluoroalkyl group having 1 to 12 carbon atoms described in Ar ¹ . As a divalent organic group having 4 to 40 carbon atoms containing a cyclic structure, the above formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), Among the bonding bonds of the groups represented by formula (26), formula (27), formula (28) and formula (29), two non-adjacent groups are substituted with hydrogen atoms and a group having a thiophene ring structure . Furthermore, among these groups, the bonding bond of the group represented by the formula (26) or the following formula (26') in which W ¹ is a single bond substituted by a fluorine-substituted hydrocarbon group with 1 to 8 carbons Among them, two non-adjacent groups substituted with hydrogen atoms, formula (28) and formula (29) substituted with a fluorine-substituted hydrocarbon group with 1 to 8 carbon atoms, or the following formula (28') and formula Among the bonding bonds of the group represented by (29'), two non-adjacent groups are substituted with hydrogen atoms, and a group having a thiophene ring structure substituted with a fluorine-substituted hydrocarbon group with 1 to 8 carbon atoms It corresponds to the divalent aromatic group having a fluoroalkyl group having 1 to 12 carbon atoms, which is described in Ar ¹ , and therefore does not conform to Z in formula (3).

[式(20')～式(29')中，W¹ 及*係如於式(20)～式(29)中進行定義]。As Z in the formula (3), the divalent organic group containing 4 to 40 carbons in the cyclic structure is more preferably formula (20'), formula (21'), formula (22'), and formula (23) '), formula (24'), formula (25'), formula (26'), formula (27'), formula (28') and formula (29') represented by the divalent organic group, [Chemical 22]

[In formulas (20') to (29'), W ¹ and * are as defined in formulas (20) to (29)].

[式(d1)中，R^e 相互獨立地表示氫原子、碳數1～6之烷基、碳數1～6之烷氧基或碳數6～12之芳基，R^f 表示R^e 或-C(=O)-*，*表示鍵結鍵]。In addition to the structural unit represented by the formula (1), the polyamide imine resin has any of the above formula (20') to formula (29') as Z in the formula (3) In the case of the structural unit represented by the formula (3), when Z in the formula (3) is represented by the following formula (7), it is easy to improve the film-forming property of the varnish, and it is easy to obtain the uniformity of the optical film From a viewpoint, it is preferable to have a carboxylic acid-derived structural unit represented by the following formula (d1) in addition to the structural unit, [Chemical Formula 23]

[In the formula (D1), R ^e each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, the alkoxy having 1 to 6 carbon atoms or the aryl group of 6 to 12, R ^f or R ^e represents -C(=O)-*, * means bonding key].

In R ^e, the carbon number of the alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms of the aryl group having 6 to 12, include those in the formula (1) in the R ¹ and R ² The alkyl group having 1 to 12 carbons, the alkoxy group having 1 to 12 carbons, or the aryl group having 6 to 12 carbons are exemplified above. As the structural unit (D1), and specific examples include: R ^e and R ^f are both hydrogen atoms of the structural unit (structural unit derived from the dicarboxylic acid compound), R ^e is a hydrogen atom and R ^f is -C (=O)-*The structural unit (the structural unit derived from the tricarboxylic acid compound), etc.

[式(7a)中，R^g 及R^h 相互獨立地表示鹵素原子、碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基，A、s及*與式(7)中之A、s及*相同，t及u相互獨立地為0～4之整數，其中，於s為1～4之整數，且A不為單鍵之情形時，R^g 及R^h 中所含之氫原子可相互獨立地經鹵素原子取代]， 更佳為包含式(7)所表示之二價有機基作為Z， [化25]

[式(7)中，R³¹ ～R³⁸ 相互獨立地表示氫原子、碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基， A相互獨立地表示單鍵、-O-、-CH₂ -、-CH₂ -CH₂ -、-CH(CH₃ )-、-C(CH₃ )₂ -、-C(CF₃ )₂ -、-SO₂ -、-S-、-CO-或-N(R³⁹ )-，R³⁹ 表示氫原子、可經鹵素原子取代之碳數1～12之一價烴基， s為0～4之整數， *表示鍵結鍵， 其中，於s為1～4之整數，且A不為單鍵之情形時，R³¹ ～R³⁸ 中所含之氫原子可相互獨立地經鹵素原子取代]。In the structural unit represented by the formula (3), it is preferable to include the divalent organic group represented by the formula (7a) as Z, [化24]

[In formula (7a), R ^g and R ^h independently represent a halogen atom, an alkyl group having 1 to 6 carbons, an alkoxy group having 1 to 6 carbons, or an aryl group having 6 to 12 carbons, A, s and * are the same as A, s and * in formula (7), t and u are independently integers from 0 to 4, where s is an integer from 1 to 4 and A is not a single bond , The hydrogen atoms contained in R ^g and R ^h can be substituted with halogen atoms independently of each other], and more preferably include the divalent organic group represented by formula (7) as Z, [化25]

[In formula (7), R ³¹ to R ³⁸ independently represent a hydrogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons, and A mutually Independently represent a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -,- SO ₂ -, -S-, -CO- or -N(R ³⁹ )-, R ³⁹ represents a hydrogen atom, a monovalent hydrocarbon group of 1 to 12 carbons that can be substituted by a halogen atom, and s is an integer of 0 to 4, * Represents a bonding bond, where, when s is an integer from 1 to 4 and A is not a single bond, the hydrogen atoms contained in R ³¹ to R ³⁸ may be independently substituted by halogen atoms].

In formula (7a), the bonding bond of each benzene ring is based on -A- and can be bonded to any of ortho, meta or para positions, preferably can be bonded to meta or para positions . R ^g and R ^h in the formula (7a) independently represent a halogen atom, an alkyl group having 1 to 6 carbons, an alkoxy group having 1 to 6 carbons, or an aryl group having 6 to 12 carbons. In the formula (7a), t and u are preferably 0. When t and/or u are 1 or more, R ^g and R ^h preferably represent an alkyl group having 1 to 6 carbon atoms, and more preferably represent carbon The number is an alkyl group of 1 to 3. In R ^g and R ^h in the formula (7a), as a halogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, and an aryl group with 6 to 12 carbons, respectively, they can be listed as In the formula (7), the halogen atom, the alkyl group having 1 to 6 carbons, the alkoxy group having 1 to 6 carbons, or the aryl group having 6 to 12 carbons are exemplified.

In the formula (7a), t and u are independently an integer of 0-4, preferably an integer of 0-2, more preferably 0 or 1, and even more preferably 0.

In formula (7) and formula (7a), A represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) _2- , -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -N(R ³⁹ )-, from the viewpoint of the bending resistance of the optical film, preferably represents -O- Or -S-, more preferably -O-. In formula (7), R ³¹ , R ³² , R ³³ , R ³⁴ , R ³⁵ , R ³⁶ , R ³⁷ and R ³⁸ independently represent a hydrogen atom, an alkyl group having 1 to 12 carbons, and a carbon number of 1 to Alkoxy group of 6 or aryl group of 6-12 carbons. Examples of alkyl groups having 1 to 12 carbons, alkoxy groups having 1 to 6 carbons, and aryl groups having 6 to 12 carbons include the alkyl group having 1 to 12 carbons in Ar ² in formula (5) , C1-C6 alkoxy group or C6-C12 aryl group as exemplified above. From the viewpoint of surface hardness and flexibility of the optical film, R ³¹ to R ³⁸ independently of each other preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and more preferably represent a hydrogen atom or a carbon number of 1 to 3 The alkyl group further preferably represents a hydrogen atom. Here, when s is an integer of 1 to 4 and A is not a single bond, the hydrogen atoms contained in R ³¹ to R ³⁸ may be independently substituted with halogen atoms. R ³⁹ represents a hydrogen atom or a monovalent hydrocarbon group with 1 to 12 carbon atoms which may be substituted with a halogen atom. Examples of monovalent hydrocarbon groups with 1 to 12 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, n-pentyl, 2-methyl Butyl, 3-methylbutyl, 2-ethylpropyl, n-hexyl, n-heptyl, n-octyl, tertiary octyl, n-nonyl, n-decyl, etc., which can be substituted by halogen atoms . As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned. In the polyimide imine resin, in the structural unit represented by formula (3), as Z, one type of divalent organic group represented by formula (7) or formula (7a) may be included, or the formula (7) or two or more organic groups represented by formula (7a).

In formula (7) and formula (7a), s is an integer in the range of 0-4, and if s is within this range, the bending resistance or elastic modulus of the optical film is likely to become good. Furthermore, in formula (7) and formula (7a), s is preferably an integer in the range of 0-3, more preferably 0-2, still more preferably 0 or 1, and particularly preferably 0. If s is within this range, it is easy to improve the bending resistance or elastic modulus of the optical film. Examples of X'in formula (7) include the groups described above for X in structural unit (1) and structural unit (2).

。 於該情形時，容易提高光學膜之表面硬度及耐彎曲性，容易降低YI值。In the polyamide imine-based resin contained in the optical film of the present invention, the structural unit represented by formula (3) may have the structural unit represented by formula (3') as Z, [化26]

. In this case, it is easy to increase the surface hardness and bending resistance of the optical film, and it is easy to reduce the YI value.

In addition to the structural unit (1) and the structural unit (2), the polyimide imine resin contained in the optical film of the present invention also includes the structural unit represented by the formula (3) (hereinafter, also referred to as " In the case of the structural unit (3)"), from the viewpoint that it is easy to increase the elastic modulus of the optical film and easily reduce the humidity expansion rate, the structural unit (1) contained in the polyimide resin , When the total of structural unit (2) and structural unit (3) is set to 100 mol%, the total ratio of structural unit (1) and structural unit (2) is preferably 60 mol% or more, more preferably 70 mol% Ear% or more, more preferably 80 mol% or more, still more preferably 85 mol% or more, and particularly preferably 90 mol% or more. The upper limit of the above-mentioned ratio of the total of the structural unit (1) and the structural unit (2) should just be less than 100 mol%. Furthermore, the content of the structural unit (1), the structural unit (2), or the structural unit (3) can be measured, for example, using ¹ H-NMR, or can be calculated based on the addition ratio of the raw materials.

In addition to the structural unit (1) and the structural unit (2), the polyimide imine resin contained in the optical film of the present invention also includes the structural unit represented by the formula (3) (hereinafter, also referred to as " In the case of the structural unit (3)"), from the viewpoint that it is easy to increase the elastic modulus of the optical film and easily reduce the humidity expansion rate, the structural unit (1) contained in the polyimide resin When the total of the structural unit (3) is set to 100 mol%, the ratio of the structural unit (1) is preferably 60 mol% or more, more preferably 70 mol% or more, and still more preferably 80 mol% or more , Particularly preferably more than 90 mol%. The upper limit of the above-mentioned ratio of the structural unit (1) should just be less than 100 mol%. The content of the structural unit (1), the structural unit (2), or the structural unit (3) can be measured using ¹ H-NMR, for example, or can be calculated based on the addition ratio of the raw materials.

In addition to the structural unit represented by the formula (1) and the formula (2), the polyimide imine resin may also include the structural unit represented by the formula (30) and/or the structural unit represented by the formula (31). [化27]

In formula (30), Y ¹ is a tetravalent organic group, preferably an organic group in which the hydrogen atom in the organic group can be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ¹ , the group described as Y in formula (2) can be cited. In an embodiment of the present invention, the polyimide-based resin may include a plurality of Y ¹ , and the plurality of Y ¹ may be the same or different from each other.

In formula (31), Y ² is a trivalent organic group, preferably an organic group in which the hydrogen atom in the organic group can be substituted by a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ² , any one of the bonding bonds of the group described in Y in the formula (2) is substituted with a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms. In an embodiment of the present invention, the polyimide-based resin may include a plurality of Y ² , and the plurality of Y ² may be the same or different from each other.

In formula (30) and formula (31), X ¹ and X ² are independently a divalent organic group, preferably an organic group in which the hydrogen atom in the organic group can be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As X ¹ and X ² , the group described as X in formulas (1) and (2) can be exemplified.

In one embodiment of the present invention, the polyimide-based resin includes a structural unit represented by formula (1), a structural unit represented by formula (2), and optionally a structure represented by formula (3) Unit, structural unit represented by formula (30), and/or structural unit represented by formula (31). From the viewpoints that it is easy to increase the elastic modulus of the optical film, easily reduce the humidity expansion rate, and easily improve the optical properties, surface hardness and bending resistance, in the above-mentioned polyimide resin, formula (1) and formula (2) The structural unit represented is based on all structural units represented by formula (1) and formula (2), and as appropriate, formula (3), formula (30) and formula (31), preferably 80 mol % Or more, more preferably 90 mol% or more, and still more preferably 95 mol% or more. Furthermore, in the polyimide-imide resin, the structural units represented by formula (1) and formula (2) are based on formula (1) and formula (2), as well as formula (3) and formula ( 30) and/or all structural units represented by formula (31) are usually 100% or less. In addition, the above-mentioned ratio can be measured using ¹ H-NMR, for example, or it can also be calculated based on the addition ratio of raw materials.

In one embodiment of the present invention, relative to 100 parts by mass of the optical film, the content of the polyimide-based resin in the optical film is preferably 10 parts by mass or more, more preferably 30 parts by mass or more, and still more preferably It is 50 parts by mass or more, preferably 99.5 parts by mass or less, more preferably 95 parts by mass or less. If the content of the polyimide-based resin is within the above range, the optical properties and elastic modulus of the optical film are easily improved, and the humidity expansion rate is easily reduced.

The weight average molecular weight (Mw) of the polyimide-based resin is 200,000-1,000,000 in terms of standard polystyrene. When the weight average molecular weight (Mw) of the polyimide-based resin is less than 200,000, the elastic modulus of the optical film cannot be sufficiently increased, and the humidity expansion rate cannot be sufficiently reduced. In addition, when the weight average molecular weight (Mw) of the polyimide-based resin exceeds 1,000,000, the solubility of the polyimide-based resin in a solvent is reduced, making it difficult to process the optical film. From the viewpoint that it is easy to increase the elastic modulus, surface hardness and bending resistance of the optical film, and to reduce the humidity expansion rate of the optical film, the weight average molecular weight (Mw) of the polyimide resin is based on the standard polyphenylene Ethylene conversion is preferably 220,000 or more, more preferably 250,000 or more, further preferably 270,000 or more, and particularly preferably 300,000 or more. In addition, from the viewpoint of easily improving the solubility of the polyimide-based resin in solvents and easily improving the elongation and processability of the optical film, the weight average molecular weight of the resin is preferably 900,000 or less, and more preferably 800,000 or less, more preferably 700,000 or less, and particularly preferably 600,000 or less. The weight average molecular weight can be measured by, for example, GPC (Gel Permeation Chromatography) and can be calculated by standard polystyrene conversion, and can be calculated, for example, by the method described in the examples.

Regarding the elastic modulus of the optical film of the present invention, from the viewpoint of easily preventing wrinkles or damage of the optical film, it is preferably 4 GPa or more, more preferably 4.5 GPa or more, and still more preferably 4.8 GPa or more. The upper limit of the elastic modulus is not particularly limited, but is usually 100 GPa or less. In addition, the elastic modulus can be measured using a tensile testing machine (the distance between the chucks is 50 mm, the tensile speed is 10 mm/min), for example, it can be measured by the method described in the examples.

In the state where a load is applied to the optical film, from the viewpoint of easily suppressing the expansion and contraction of the optical film in the plane direction when temperature and humidity change, the humidity expansion coefficient (CME) of the optical film of the present invention is preferably 23 ppm Below, it is more preferably 22 ppm or less, still more preferably 21 ppm or less, and particularly preferably 20 ppm or less. The smaller the humidity expansion rate is, the easier it is to suppress the expansion and contraction of the optical film in the plane direction when the temperature and humidity change when a load is applied to the optical film. The lower limit is not particularly limited, as long as it is 0 ppm or more. Furthermore, the CME can be the humidity expansion rate of the film when it is controlled to 60°C, 90% R.H. and kept for 1 hour, for example, it can be measured by the method described in the examples.

The total light transmittance of the optical film of the present invention and/or the light transmittance of light from 300 to 800 nm is preferably 80% or more, more preferably 85% or more, more preferably 90% or more, and particularly preferably 91 %the above. If the total light transmittance is greater than or equal to the above lower limit, it is easy to improve visibility when the optical film is used as a front panel and incorporated into a display device. The optical film of the present invention generally exhibits a higher total light transmittance, so for example, compared with the case of using a film with a lower transmittance, the luminous intensity of the display element required to obtain a certain brightness can be suppressed. Therefore, power consumption can be reduced. For example, when the optical film of the present invention is incorporated into a display device, there is a tendency to obtain a bright display even if the amount of light of the backlight is reduced, which can contribute to energy saving. The upper limit of total light transmittance is usually below 100%. In addition, the total light transmittance can be measured using a haze meter in accordance with JIS K 7361-1:1997, for example. The total light transmittance may be the total light transmittance in the thickness range of the following optical film.

The haze of the optical film of the present invention is preferably 5% or less, more preferably 4% or less, still more preferably 3% or less, still more preferably 2.5% or less, particularly preferably 2% or less, especially more preferably 1 % Or less, more preferably 0.5% or less, particularly preferably 0.2% or less, and usually 0.01% or more. If the haze of the optical film is equal to or less than the above upper limit, it is easy to improve visibility when the optical film is used as a front panel and incorporated into a display device. In addition, the haze can be measured using a haze meter in accordance with JIS K 7136:2000.

The YI value of the optical film of the present invention is preferably 3.5 or less, more preferably 3.0 or less, and still more preferably 2.5 or less. If the YI value of the optical film is less than the above upper limit, the transparency becomes good, and when used in the front panel of a display device, it can contribute to higher visibility. In addition, the YI value is usually -5 or more, and preferably -2 or more. Furthermore, the YI value can be measured with a UV-visible-near-infrared spectrophotometer to measure the transmittance of light from 300 to 800 nm to obtain 3 stimulus values (X, Y, Z), and based on YI=100×(1.2769X- 1.0592Z)/Y. Furthermore, in this specification, the so-called excellent optical properties of the optical film means that the light transmittance is high.

The thickness of the optical film of the present invention is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 25 μm or more, particularly preferably 30 μm or more, and preferably 200 μm or less, more preferably 100 μm or less , And more preferably 80 μm or less, particularly preferably 60 μm or less, and may be a combination of the upper and lower limits. If the thickness of the optical film is within the above range, it is easier to increase the elastic modulus of the optical film. Furthermore, the thickness of the optical film can be measured using a micrometer, for example, can be measured by the method described in the Example.

The number of bending (bending radius R=1 mm) in the bending resistance test of the optical film of the present invention is preferably 150,000 times or more, more preferably 180,000 times or more, and still more preferably 200,000 times or more. If the number of bending is more than the above lower limit, it has sufficient bending resistance as a front panel material such as a flexible display device. In addition, the number of bending in the bending resistance test means that the bending radius (radius of curvature) R is 1 mm, and the optical film is repeatedly bent, and the film is back and forth to the point when a crack occurs on the film. The number of bends (set the round trip to 1 time).

The pencil hardness of at least one side of the optical film of the present invention is preferably H or more, more preferably 2 H or more. When the pencil hardness on at least one side of the optical film is higher than the above-mentioned hardness, it is easy to prevent scratches on the surface of the optical film. In addition, the pencil hardness can be measured in accordance with JIS K 5600-5-4: 1999, for example, it can be measured by the method described in the examples.

[式(1)中， Ar¹ 表示具有碳數1～12之氟烷基之二價芳香族基， X表示二價有機基]， 且包含式(4)所表示之二價芳香族基作為式(1)中之Ar¹ 之結構單元： [化29]

[式(4)中， R¹ 表示碳數1～12之氟烷基， n及k相互獨立地表示1～4之整數，其中，於n及/或k表示2～4之整數之情形時，複數個存在之R¹ 相互可相同亦可不同， *表示鍵結鍵]； 以及式(2)所表示之結構單元： [化30]

[式(2)中，X表示二價有機基，Y表示四價有機基]， 且重量平均分子量為200,000～1,000,000。關於該聚醯胺醯亞胺系樹脂中之各符號之種類及結構單元之比率的例示及較佳之態樣等，與本發明之光學膜中所含之聚醯胺醯亞胺系樹脂相關之上述記載同樣地符合。In addition to the above-mentioned optical film containing polyimide-based resin, the present invention also provides the above-mentioned polyimide-based resin suitable for manufacturing the optical film. The polyimide-based resin may be, for example, the following polyimide-based resin, which at least has the formula (1): [化28]

[In formula (1), Ar ¹ represents a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbon atoms, and X represents a divalent organic group], and includes the divalent aromatic group represented by formula (4) as The structural unit of Ar ¹ in formula (1): [化29]

[In formula (4), R ¹ represents a fluoroalkyl group having 1 to 12 carbon atoms, and n and k independently represent an integer of 1 to 4, where n and/or k represent an integer of 2 to 4 , A plurality of R ¹ may be the same or different from each other, * represents a bonding bond]; and the structural unit represented by formula (2): [化30]

[In formula (2), X represents a divalent organic group and Y represents a tetravalent organic group], and the weight average molecular weight is 200,000 to 1,000,000. Examples and preferred aspects of the types of symbols and the ratios of structural units in the polyimide-based resin are related to the polyimide-based resin contained in the optical film of the present invention The above description is the same.

The content of halogen atoms in the polyimide-based resin is based on the mass of the polyimide-based resin, preferably 1-60% by mass, more preferably 5-55% by mass, and still more preferably 10-50% by mass. If the content of the halogen atom is more than the above lower limit, the elastic modulus of the optical film is easily increased, the humidity expansion rate is easily reduced, and the transparency and visibility are more easily improved. If the content of halogen atoms is less than the above upper limit, it is easy to synthesize resin.

The imidization rate of the polyimide-based resin is preferably 90% or more, more preferably 93% or more, and still more preferably 96% or more. From the viewpoint of easy improvement of the optical properties of the optical film, the imidization rate is preferably at least the above lower limit. In addition, the upper limit of the imidization rate is 100% or less. The imidization rate represents the molar amount of the amide bond in the polyamide-imide resin relative to the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyamide-imide resin The ratio of 2 times the value. Furthermore, when the polyamide-imide-based resin contains a tricarboxylic acid compound, it means that the molar amount of the amide bond in the polyamide-imide-based resin is relative to the polyamide-imide-based resin The ratio of the value of twice the molar amount of the structural unit derived from the tetracarboxylic acid compound to the total molar amount of the structural unit derived from the tricarboxylic acid compound. In addition, the imidization rate can be determined by an IR (Infrared Radiation) method, an NMR method, or the like.

＜Manufacturing method of resin＞

[式(8)中，Ar¹ 為如對式(1)中之Ar¹ 進行定義，R^c 及R^d 相互獨立地表示羥基、甲氧基、乙氧基、正丙氧基、異丙氧基、正丁氧基、第二丁氧基、第三丁氧基或氯原子]The polyamide imide resin having at least the above-mentioned specific structural unit (1) and structural unit (2) contained in the optical film of the present invention and having a weight average molecular weight of 200,000 to 1,000,000 can be, for example, a tetracarboxylic acid compound , Dicarboxylic acid compounds and diamine compounds are the main raw materials and are manufactured. Here, the structural unit represented by the above formula (1) is a structural unit formed by the reaction of a dicarboxylic acid compound and a diamine compound, and the structural unit represented by the above formula (2) is a tetracarboxylic acid compound and a diamine compound. The structural unit formed by the reaction. Therefore, the dicarboxylic acid compound, the tetracarboxylic acid compound, and the diamine compound which become the structural unit represented by said formula (1) and formula (2) can be used, and a polyimide imine type resin can be manufactured. From this viewpoint, the dicarboxylic acid compound preferably contains at least the compound represented by formula (8). [化31]

[In the formula (8), Ar ¹ is as in the formula ⁽¹⁾ Ar 1 is defined, R ^c and R ^d each independently represents a hydroxy, methoxy, ethoxy, n-propoxy, isopropoxy Group, n-butoxy group, second butoxy group, third butoxy group or chlorine atom]

In a preferred embodiment of the present invention, the dicarboxylic acid compound is a compound represented by formula (8) in which R ^c and R ^d are chlorine atoms. In addition, a diisocyanate compound may be used instead of the diamine compound.

As the dicarboxylic acid compound used in the production of the resin, it is preferable to use an aromatic dicarboxylic acid having a fluoroalkyl group or such chlorinated compounds such as terephthalic acid having a fluoroalkyl group, 4,4'- Oxybisbenzoic acid or these chlorinated compounds. In addition to terephthalic acid or 4,4'-oxybisbenzoic acid or these chlorine compounds, other dicarboxylic acid compounds may also be used. Examples of other dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and these related chlorinated compounds, acid anhydrides, etc., and two or more of them may be used in combination. As a specific example, an aromatic dicarboxylic acid compound having a trifluoromethyl group (isophthalic acid; naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid Acid), a compound in which two benzoic acids with trifluoromethyl group are linked by a single bond or a phenylene group, and these chlorinated compounds. As a specific example, 2,2'-bis(trifluoromethyl)-4,4'-biphenyl dimethyl chloride, and 2,5-bis(trifluoromethyl) terephthalic dimethyl chloride are preferable.

[式(7')中，R³¹ ～R³⁸ 相互獨立地表示氫原子、碳數1～6之烷基、碳數1～6之烷氧基、或碳數6～12之芳基，R³¹ ～R³⁸ 中所含之氫原子可相互獨立地經鹵素原子取代， A表示單鍵、-O-、-CH₂ -、-CH₂ -CH₂ -、-CH(CH₃ )-、-C(CH₃ )₂ -、-C(CF₃ )₂ -、-SO₂ -、-S-、-CO-或-N(R³⁹ )-， R³⁹ 表示氫原子、可經鹵素原子取代之碳數1～12之一價烴基， s為0～4之整數， R^c 及R^d 為如對式(8)中之R^c 及R^d 進行定義]。As the dicarboxylic acid compound, the compound represented by formula (8) and other dicarboxylic acid compounds can be used. As other dicarboxylic acid compounds, the dicarboxylic acid compounds represented by the formula (7') can be cited: [化32]

[In formula (7'), R ³¹ to R ³⁸ independently represent a hydrogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or an aryl group with 6 to 12 carbons, R The hydrogen atoms contained in ³¹ to R ³⁸ can be independently substituted by halogen atoms. A represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-,- C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -S-, -CO- or -N(R ³⁹ )-, R ³⁹ represents a hydrogen atom, which can be substituted by a halogen atom one having 1 to 12 carbon atoms, monovalent hydrocarbon group, s is an integer of 0 to 4, R ^c, and R ^d is defined as in the formula (8) R ^c, and R ^d].

In one embodiment of the present invention, the other dicarboxylic acid compound may be a compound represented by formula (7') in which s is 1 to 4, and A is an oxygen atom.

As the diamine compound used in the production of the resin, for example, aliphatic diamine, aromatic diamine, and mixtures thereof can be cited. Furthermore, in this embodiment, the so-called "aromatic diamine" means a diamine in which an amine group is directly bonded to an aromatic ring, and a part of its structure may contain an aliphatic group or other substituents. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a sulphur ring, but are not limited to these. Among them, a benzene ring is preferred. In addition, the term "aliphatic diamine" means a diamine in which an amine group is directly bonded to an aliphatic group, and an aromatic ring or other substituents may be included in a part of the structure.

As aliphatic diamines, for example, acyclic aliphatic diamines such as hexamethylene diamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl) Group) cyclohexane, noralkylene diamine and 4,4'-diaminodicyclohexylmethane and other cyclic aliphatic diamines. These can be used individually or in combination of 2 or more types.

Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2 ,6-Diaminonaphthalene and other aromatic diamines with one aromatic ring, 4,4'-diaminodiphenylmethane, 4,4'-diaminobiphenylpropane, 4,4'-diamine Diphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether Benzene, 3,3'-diaminobiphenyl, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis[4 -(4-Aminophenoxy) phenyl] ash, bis[4-(3-aminophenoxy) phenyl] ash, 2,2-bis[4-(4-aminophenoxy) Phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl) -4,4'-diaminobiphenyl (sometimes described as TFMB), 4,4'-bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl) Chrysanthemum, 9,9-bis(4-amino-3-methylphenyl)pyridium, 9,9-bis(4-amino-3-chlorophenyl)pyridium, 9,9-bis(4-amine Aromatic diamines having two or more aromatic rings, such as -3-fluorophenyl) pyridine. These can be used individually or in combination of 2 or more types.

The aromatic diamine is preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,3'-diamine Diphenyl ether, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 1,4-bis(4-aminophenoxy)benzene, bis[4-( 4-aminophenoxy)phenyl]supplement, bis[4-(3-aminophenoxy)phenyl]supplement, 2,2-bis[4-(4-aminophenoxy)phenyl ]Propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)-4 ,4'-diaminodiphenyl (TFMB), 4,4'-bis(4-aminophenoxy)biphenyl, more preferably 4,4'-diaminodiphenylmethane, 4,4' -Diaminobiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminobiphenyl, 1,4-bis(4-aminophenoxy)benzene, bis[ 4-(4-aminophenoxy)phenyl] chrysene, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2 ,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB), 4,4'-bis(4-aminophenoxy)biphenyl. These can be used individually or in combination of 2 or more types.

Among the above-mentioned diamine compounds, from the viewpoints of high surface hardness, high transparency, high flexibility, high bending resistance and low colorability of the optical film, it is preferable to use aromatic diamine compounds selected from the group having a biphenyl structure. One or more of the group consisting of amines. More preferably, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and At least one of the group consisting of 4,4'-diaminodiphenyl ether, and more preferably 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (TFMB).

Examples of the tetracarboxylic acid compound used in the production of the resin include aromatic tetracarboxylic acid compounds such as aromatic tetracarboxylic dianhydride; and aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used alone or in combination of two or more kinds. In addition to the dianhydride, the tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as a chlorine compound.

Specific examples of aromatic tetracarboxylic dianhydrides include: non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides, and condensed polycyclic aromatic tetracarboxylic dianhydrides Acid dianhydride. Examples of non-condensed polycyclic aromatic tetracarboxylic dianhydrides include: 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid Dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3' -Biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2, 2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene Yl)diphthalic dianhydride (sometimes described as 6FDA), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxybenzene Base) ethane dianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3 ,4-Dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic dianhydride, 4, 4'-(Phenylenedioxy)diphthalic dianhydride. In addition, examples of monocyclic aromatic tetracarboxylic dianhydrides include 1,2,4,5-benzenetetracarboxylic dianhydride, and examples of condensed polycyclic aromatic tetracarboxylic dianhydrides include 2,3,6,7-Naphthalenetetracarboxylic dianhydride.

Among these, preferred examples include 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride , 3,3',4,4'-diphenyl tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3- Dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic acid Anhydride (6FDA), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis (3,4-Dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, Bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic dianhydride and 4,4'-(p-phenylenedioxy)di Phthalic dianhydride, more preferably, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-Biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), bis(3,4-dicarboxyphenyl)methane Anhydride and 4,4'-(p-phenylenedioxy) diphthalic dianhydride. These can be used individually or in combination of 2 or more types.

As the aliphatic tetracarboxylic dianhydride, cyclic or acyclic aliphatic tetracarboxylic dianhydride can be mentioned. The so-called cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure. Specific examples thereof include: 1,2,4,5-cyclohexane tetracarboxylic dianhydride, 1 , 2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride and other cycloalkane tetracarboxylic dianhydride, bicyclo[2.2.2]oct-7 -En-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride and their positional isomers. These can be used individually or in combination of 2 or more types. Specific examples of acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butane tetracarboxylic dianhydride, 1,2,3,4-pentane tetracarboxylic dianhydride, etc. These can be used alone or in combination of two or more. In addition, it is also possible to use a combination of cyclic aliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride.

Among the above-mentioned tetracarboxylic dianhydrides, from the viewpoints of high surface hardness, high transparency, high flexibility, high bending resistance, and low colorability of the optical film, 4,4'-oxydicarboxylate is preferred. Phthalic acid dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3 ,3'-Biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride , 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and mixtures thereof, more preferably 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4 ,4'-(hexafluoroisopropylidene)diphthalic dianhydride and mixtures thereof, and more preferably 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA).

Furthermore, the above polyamide imine-based resin can be used in addition to the above-mentioned tetracarboxylic acid compound, as long as it does not impair the various physical properties of the optical laminate. And derivatives to react.

Examples of the tetracarboxylic acid include water adducts of anhydrides of the aforementioned tetracarboxylic acid compounds.

As a tricarboxylic acid compound, aromatic tricarboxylic acid, aliphatic tricarboxylic acid, and these related chlorinated compounds, acid anhydride, etc. can be mentioned, You may use in combination of 2 or more types. Specific examples include: 1,2,4-benzenetricarboxylic acid anhydride; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; phthalic anhydride and benzoic acid have a single bond,- O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or phenylene-linked compound.

In the production of the resin, the usage amount of the diamine compound, the tetracarboxylic acid compound and/or the dicarboxylic acid compound can be appropriately selected according to the required ratio of each structural unit of the polyimide-based resin.

The method for producing a polyamide resin having at least a structural unit (1) and a structural unit (2) and a weight average molecular weight of 200,000 to 1,000,000, as long as the polyamide resin can be obtained. It is not particularly limited. From the viewpoint of easy improvement of the elastic modulus of the optical film and easy reduction of the humidity expansion rate, it is preferable to react the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound and add the two in batches. The method for producing a carboxylic acid compound to produce a polyimide-based resin is more preferably a step (I) comprising reacting a diamine compound and a tetracarboxylic acid compound to produce an intermediate (A), and making the intermediate The step (II) of reacting the compound (A) with the dicarboxylic acid compound (preferably the compound represented by formula (8)), and in this step (II), the method of adding the dicarboxylic acid compound in batches is produced Polyimide resin.

It is considered that the polyamide imine-based resin contained in the optical film of the present invention has a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbon atoms through the Ar ¹ in the above formula (1). The specific part of the skeleton of the amine imine resin has moderate rigidity and intermolecular repulsion. When the polyamide resin having such a structure is produced without using the method of adding the dicarboxylic acid compound in batches, it is difficult to make the weight average molecular weight of the polyamide resin become the above-mentioned requirement. The scope of the situation. In addition, it is produced by using a method of adding a dicarboxylic acid compound in batches. Although the reason is not clear, it is thought that a resin that is most suitable for increasing the elastic modulus of the optical film and reducing the humidity expansion rate can be obtained.

Therefore, the polyamide imine resin contained in the optical film of the present invention and the polyamide imine resin of the present invention are preferably prepared by using a diamine compound, a tetracarboxylic acid compound, and a dicarboxylic acid The resin produced by the method for producing a dicarboxylic acid compound by reacting the compound and adding the dicarboxylic acid compound in batches is more preferably by including the step (I) of reacting the diamine compound and the tetracarboxylic acid compound to produce the intermediate (A), and making The step (II) of the reaction between the intermediate (A) and the dicarboxylic acid compound (preferably the compound represented by formula (8)), and in this step (II), the production of the dicarboxylic acid compound in batches Method of manufacturing resin. In the manufacturing method by including the step of adding in batches the dicarboxylic acid compound of the polyamide imide resin having at least the structural unit (1) and the structural unit (2) and the weight average molecular weight of 200,000 to 1,000,000 In the case of production, it is easy to adjust the weight average molecular weight of the polyimide-based resin within the above-mentioned range.

In the case of producing a polyamidoimide-based resin by the production method including the above step (I) and step (II), the step of reacting a diamine compound with a tetracarboxylic acid compound to produce an intermediate (A) The reaction temperature of (I) is not particularly limited. For example, it may be 5 to 200°C, preferably 5 to 100°C, more preferably 5 to 50°C, and still more preferably 5°C to room temperature (25°C). about). The reaction time can be, for example, 1 minute to 72 hours, preferably 10 minutes to 24 hours. In addition, the reaction can be carried out while stirring in air or in an inert gas atmosphere (for example, nitrogen, argon, etc.), and can also be carried out under normal pressure, under pressure, or under reduced pressure. In a preferred embodiment, it is performed while stirring under normal pressure and/or an inert gas atmosphere.

In step (I), the diamine compound and the tetracarboxylic acid compound react to produce intermediate (A), that is, polyamide acid. Therefore, the intermediate (A) has at least a structural unit derived from a diamine compound and a structural unit derived from a tetracarboxylic acid compound.

Next, in step (II), the intermediate (A) is reacted with the dicarboxylic acid compound. Here, it is preferable to add the dicarboxylic acid compound in batches. The dicarboxylic acid compound is added in batches to the reaction liquid obtained in step (I), and the intermediate (A) is reacted with the dicarboxylic acid compound. By adding the dicarboxylic acid compound in batches without adding the dicarboxylic acid compound at a time, it is easy to increase the molecular weight of the polyimide resin. Furthermore, in this specification, the so-called batch addition means adding the added dicarboxylic acid compound in several divisions, and more specifically, dividing the added dicarboxylic acid into a specific amount, separated by a specific interval (specific Time) and added separately. The specific interval (specific time) also includes a very short interval (or time), so batch addition also includes continuous addition (or continuous feeding). Furthermore, in this specification, the so-called batch addition means adding the added dicarboxylic acid compound in several divisions, and more specifically, dividing the added dicarboxylic acid into a specific amount, separated by a specific interval (specific Time) and added separately. The specific interval (specific time) also includes a very short interval (or time), so batch addition also includes continuous addition (or continuous feeding).

In step (II), the number of batches when adding the dicarboxylic acid compound in batches can be appropriately selected according to the scale of the reaction or the type of raw materials, etc., preferably 2-20 times, more preferably 3-10 times, and more It is preferably 3 to 6 times. If the number of batches is in the above range, it is easy to increase the molecular weight of the polyimide-based resin.

The dicarboxylic acid compound can be added in equal amounts in batches, or added in unequal amounts in batches. The time between each addition (hereinafter, sometimes referred to as the addition interval) may all be the same or different. In addition, when two or more dicarboxylic acid compounds are added, the term "addition in batches" means that the total amount of all dicarboxylic acid compounds is added in batches. There is no special method for the batchwise addition of each dicarboxylic acid compound. Limited, for example, each dicarboxylic acid compound may be added all at once or in batches, or each dicarboxylic acid compound may be added in batches together, or a combination of these.

In step (II), it is preferable that the weight average molecular weight of the polyamide-based resin relative to the weight-average molecular weight of the polyamide-based resin to be obtained is preferably 10% or more, more preferably 15% or more At this point in time, the amount of the dicarboxylic acid compound added is preferably 1-40 mol%, more preferably -25 mol% relative to the total molar amount of the added dicarboxylic acid compound.

The reaction temperature of step (II) is not particularly limited. For example, it may be 5 to 200°C, preferably 5 to 100°C, more preferably 5 to 50°C, and even more preferably 5°C to room temperature (25 ℃). In addition, the reaction can be carried out while stirring in air or in an inert gas atmosphere such as nitrogen or argon, and can also be carried out under normal pressure, under pressure or under reduced pressure. In a preferred aspect, step (II) is performed while stirring under normal pressure and/or an inert gas atmosphere.

In step (II), after the dicarboxylic acid compound is added in batches, it is stirred for a specific time or the like to react, thereby obtaining a polyamide imine precursor. Furthermore, the polyimide imine precursor can be precipitated by adding a large amount of water to the reaction solution containing the polyimide imine precursor, and then filtered and concentrated. , Drying and so on.

In step (II), the intermediate (A) is reacted with the dicarboxylic acid compound to obtain a polyimide imine precursor. Therefore, the polyimide imine precursor means that it has at least a structural unit derived from a diamine compound, a structural unit derived from a tetracarboxylic acid, and a structural unit derived from a dicarboxylic acid compound before the imidization (pre-ring closure) ) Of polyamide imine.

In the production of the resin, the reaction temperature of the diamine compound, the tetracarboxylic acid compound, and the dicarboxylic acid compound is not particularly limited, and is, for example, 5 to 350°C, preferably 5 to 200°C, and more preferably 5 to 100°C. The reaction time is also not particularly limited, and for example, it is about 30 minutes to 10 hours. If necessary, the reaction can be carried out under an inert atmosphere or under reduced pressure. In a preferred aspect, the reaction is carried out while stirring under normal pressure and/or an inert gas atmosphere. Moreover, it is preferable to perform the reaction in a solvent inert to the reaction. The solvent is not particularly limited as long as it does not affect the reaction. Examples include water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, Alcoholic solvents such as 1-methoxy-2-propanol, 2-butoxyethanol, propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, Ester solvents such as γ-valerolactone, propylene glycol methyl ether acetate and ethyl lactate; ketones such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, methyl isobutyl ketone, etc. Solvents; aliphatic hydrocarbon solvents such as pentane, hexane and heptane; alicyclic hydrocarbon solvents such as ethylcyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; tetrahydrofuran and dimethoxy Ether solvents such as methyl ethane; chlorine-containing solvents such as chloroform and chlorobenzene; amine solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; dimethyl sulfide, two Sulfur-containing solvents such as methyl sulfite and cyclobutyl; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations (mixed solvents) of these. Among these, from the viewpoint of solubility, an amide-based solvent can be suitably used.

The production method of the polyimide-based resin may further include the step (III) of imidizing the polyimide imide precursor in the presence of the imidization catalyst. By supplying the polyamide imide precursor obtained in step (II) to step (III), among the structural units of the polyamide imide precursor, a part of the structural unit having a polyamide acid structure After imidization (through ring closure), a polyamidoimide-based resin containing the structural unit represented by formula (1) and the structural unit represented by formula (2) can be obtained. Examples of the imidization catalyst include: aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, N -Alicyclic amines such as butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine (monocyclic); azabicyclo[2.2.1]heptane, azabicyclo[3.2. 1] Octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2.2]nonane and other alicyclic amines (polycyclic); and pyridine, 2-picoline (2-picoline) ), 3-picoline, 4-picoline, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-lutidine , 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline and other aromatic amines. Furthermore, from the viewpoint of facilitating the promotion of the imidization reaction, it is preferable to use an imidization catalyst and acid anhydride. The acid anhydride can be exemplified by commonly used acid anhydrides used in the imidization reaction, and specific examples thereof include aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic acid anhydrides such as phthalic acid.

Polyamidoimine-based resins can be separated by conventional methods such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography and other separation methods, or a combination of these separation methods. ). In a preferred aspect, isolation can be performed by adding a large amount of alcohol such as methanol to the reaction solution containing the polyimide-based resin to precipitate the resin, and then performing concentration, filtration, drying, etc. for isolation.

＜Filling＞ The optical film of the present invention may contain at least one type of filler. As the filler, for example, organic particles, inorganic particles, etc. can be cited, preferably, inorganic particles can be cited. Examples of inorganic particles include metal oxide particles such as silicon dioxide, zirconium oxide, aluminum oxide, titanium oxide, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide. ; Metal fluoride particles such as magnesium fluoride and sodium fluoride. Among them, in terms of improving the elastic modulus and/or tearing strength of the optical film and easily improving the impact resistance, it is preferable to include : Silica particles, zirconia particles, alumina particles, more preferably, silica particles can be cited. These fillers can be used alone or in combination of two or more kinds.

The filler, preferably silica particles, have an average primary particle size of 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, still more preferably 15 nm or more, and particularly preferably 20 nm or more, and It is preferably 100 nm or less, more preferably 90 nm or less, still more preferably 80 nm or less, still more preferably 70 nm or less, particularly preferably 60 nm or less, especially more preferably 50 nm or less, and especially more preferably Below 40 nm. If the average primary particle size of the silicon dioxide particles is within the above range, the aggregation of the silicon dioxide particles is suppressed, and the optical properties of the obtained optical film are easily improved. The average primary particle size of the filler can be measured by the BET method. Furthermore, the image analysis of a transmission electron microscope or a scanning electron microscope can be used to determine the average primary particle size.

When the optical film of the present invention contains a filler, preferably silica particles, the content of the filler relative to 100 parts by mass of the optical film is usually 0.1 part by mass or more, preferably 1 part by mass or more, more preferably It is 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 20 parts by mass or more, particularly preferably 30 parts by mass or more, and preferably 60 parts by mass or less. If the content of the filler is more than the above lower limit, it is easy to increase the elastic modulus of the obtained optical film. In addition, if the content of the filler is less than or equal to the above upper limit, the optical properties of the optical film are easily improved.

＜Ultraviolet absorber＞ The optical film of the present invention may contain at least one ultraviolet absorber. The ultraviolet absorber can be appropriately selected from those generally used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may also include compounds that absorb light with wavelengths below 400 nm. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, and triazole-based compounds. The ultraviolet absorber can be used alone or in combination of two or more kinds. Since the optical film contains an ultraviolet absorber, deterioration of the resin is suppressed, and therefore, the visibility can be improved when the optical film of the present invention is applied to a display device or the like. In this specification, the "system compound" refers to the derivative of the compound to which the "system compound" is attached. For example, the so-called "benzophenone-based compound" refers to a compound having benzophenone as a parent skeleton and a substituent bonded to benzophenone.

When the optical film of the present invention contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 0.01-10 parts by mass, more preferably 0.01-10 parts by mass, relative to the mass of the polyamideimide-based resin contained in the optical film 1-8 parts by mass, more preferably 2-7 parts by mass. If the content of the ultraviolet absorber is more than the above lower limit, it is easy to improve the ultraviolet absorbability. If the content of the ultraviolet absorber is less than the above upper limit, the decomposition of the ultraviolet absorber caused by the heat during the production of the base material can be suppressed, and the optical properties are easily improved, for example, the haze is easily reduced.

＜Other additives＞ The optical film of the present invention may further contain other additives other than fillers and ultraviolet absorbers. Examples of other additives include: antioxidants, mold release agents, stabilizers, bluing agents and other colorants, flame retardants, pH adjusters, silica dispersants, lubricants, tackifiers, and leveling agents剂 etc. In the case of containing other additives, relative to the mass of the optical film, its content may preferably be 0.001-20% by mass, more preferably 0.01-15% by mass, and still more preferably 0.1-10% by mass.

(Method of manufacturing optical film) The manufacturing method of the optical film of the present invention is not particularly limited. For example, it may be a manufacturing method including the following steps: (a) A step of preparing a polyimide-based resin composition (hereinafter, also referred to as "varnish") containing at least the above-mentioned polyimide-based resin and a solvent (varnish preparation step), (b) The step of applying the varnish to the support material to form a coating film (coating step), and (c) The step of drying the applied liquid (coating film) to form an optical film (optical film forming step).

In the varnish preparation step, the polyimide imine-based resin is dissolved in a solvent, and additives such as the filler and ultraviolet absorber are added as necessary, and the varnish is prepared by stirring and mixing. Furthermore, when silica particles are used as a filler, silica sol can be added to the resin. The silica sol is a solvent that can be dissolved in the above resin, such as the solvent used in the preparation of the varnish below It is formed by replacing the dispersion liquid of silica sol containing silica particles.

The solvent used in the preparation of the varnish is not particularly limited as long as it can dissolve the above-mentioned resin. Examples of the solvent include: amide-based solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; lactone-based solvents such as γ-butyrolactone and γ-valerolactone Solvents; sulfur-containing solvents such as dimethyl sulfide, dimethyl sulfide, and cyclobutyl sulfide; carbonate-based solvents such as ethylene carbonate and propylene carbonate; and combinations of these (mixed solvents). Among these, an amide-based solvent or a lactone-based solvent is preferred. These solvents can be used alone or in combination of two or more. In addition, water, alcohol-based solvents, ketone-based solvents, acyclic ester-based solvents, ether-based solvents, and the like may also be contained in the varnish. The solid content concentration of the varnish is preferably 1 to 25% by mass, more preferably 5 to 20% by mass, and still more preferably 5 to 15% by mass.

In the coating step, a varnish is applied to the support material by a known coating method to form a coating film. As well-known coating methods, for example, roll coating methods such as wire bar coating, reverse coating, and gravure coating, die nozzle coating methods, camber coating methods, die lip coating methods, Spin coating method, screen coating method, spray coating method, dipping method, spray method, casting method, etc.

In the film forming step, the coating film is dried and peeled from the support material to form an optical film. After peeling, a step of drying the optical film can be set. The drying of the coating film can usually be carried out at a temperature of 50 to 350°C. If necessary, the coating film can be dried in an inert atmosphere or under reduced pressure.

As an example of the support material, if it is a metal system, SUS board can be cited, and if it is a resin system, it can be cited: PET (Polyethylene Terephthalate) film, PEN (Polyethylene Naphthalate, polyethylene naphthalate) Diester) film, polyimide-based resin film, polyimide-based resin film, cycloolefin-based polymer (COP) film, acrylic film, etc. Among them, from the viewpoint of excellent smoothness and heat resistance, a PET film, a COP film, etc. are preferred, and further, from the viewpoint of adhesion to an optical film and cost, a PET film is more preferred.

(Functional layer) One or more functional layers can be used in at least one area layer of the optical film of the present invention. As the functional layer, for example, an ultraviolet absorbing layer, a hard coat layer, an undercoat layer, a gas barrier layer, an adhesion layer, a hue adjustment layer, a refractive index adjustment layer, etc. may be mentioned. The functional layer can be used alone or in combination of two or more.

The ultraviolet absorbing layer is a layer with ultraviolet absorbing function, such as a main material selected from ultraviolet curable transparent resin, electron beam curable transparent resin, and thermosetting transparent resin, and dispersed in the main material Consists of ultraviolet absorbers.

(Hard coating) A hard coat layer can be provided on at least one side of the optical film of the present invention. The thickness of the hard coat layer is not particularly limited, and may be, for example, 2 to 100 μm. If the thickness of the hard coat layer is within the above range, sufficient scratch resistance can be ensured, and the bending resistance is unlikely to decrease, and there is a tendency that problems caused by curling caused by hardening shrinkage are unlikely to occur. The hard coat layer can be formed by curing a hard coat composition containing a reactive material capable of forming a crosslinked structure by irradiation of active energy rays or heat energy, and is preferably performed by irradiation of active energy rays. Active energy rays are defined as energy rays that can decompose compounds that produce active species to produce active species. Examples include visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron beams. Examples include ultraviolet rays. The above-mentioned hard coating composition contains at least one polymer of a radical polymerizable compound and a cation polymerizable compound.

The above-mentioned radically polymerizable compound is a compound having a radically polymerizable group. The radical polymerizable group possessed by the above radical polymerizable compound may be a functional group capable of generating a radical polymerization reaction, and includes a group containing a carbon-carbon unsaturated double bond, etc., specifically, Vinyl, (meth)acryloyl, etc. Furthermore, when the above-mentioned radically polymerizable compound has two or more radically polymerizable groups, these radically polymerizable groups may be the same or different from each other. In terms of increasing the hardness of the hard coat layer, the number of radical polymerizable groups of the radical polymerizable compound in one molecule is preferably 2 or more. As the above-mentioned radically polymerizable compound, a compound having a (meth)acryloyl group is preferred in terms of high reactivity, and specific examples include: 2 to 6 (methyl) groups per molecule Acrylic acid-based compound called multifunctional acrylate monomer or called epoxy (meth)acrylate, (meth)acrylate urethane, polyester (meth)acrylate Oligomers having several (meth)acrylic acid groups with a molecular weight of several hundreds to several thousand, preferably selected from epoxy (meth)acrylate, (meth)acrylate urethane and One or more of polyester (meth)acrylates.

The above-mentioned cationically polymerizable compound is a compound having a cationically polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. In terms of increasing the hardness of the hard coat layer, the number of cationically polymerizable groups in one molecule of the above-mentioned cationically polymerizable compound is preferably 2 or more, more preferably 3 or more. Furthermore, as the above-mentioned cationically polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cationically polymerizable group is preferred. Cyclic ether groups such as epoxy groups and oxetanyl groups are preferred in terms of less shrinkage accompanying the polymerization reaction. In addition, the compound having the epoxy group in the cyclic ether group has a compound that is easy to obtain a diversified structure, does not adversely affect the durability of the obtained hard coat, and is easy to control and free radically polymerizable compound The advantages of compatibility. In addition, the oxetanyl group in the cyclic ether group has a higher degree of polymerization than the epoxy group, which speeds up the formation speed of the network structure obtained from the cationically polymerizable compound of the hard coat layer, and is more effective The region where the radical polymerizable compound is mixed does not leave unreacted monomers in the film and forms an independent network structure. Examples of cationic polymerizable compounds having epoxy groups include: by using appropriate oxidizing agents such as hydrogen peroxide and peracid, polyglycidyl ethers of polyhydric alcohols having alicyclic rings or cyclohexene rings, Cycloaliphatic epoxy resin obtained by epoxidation of compound of cyclopentene ring; polyglycidyl ether of aliphatic polyol, or its alkylene oxide adduct, polyglycidyl ester of aliphatic long-chain polybasic acid, ( Aliphatic epoxy resins such as homopolymers and copolymers of glycidyl methacrylate; by bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or their alkylene oxide adducts , Glycidyl ether produced by the reaction of derivatives such as caprolactone adducts and epichlorohydrin, and glycidyl ether type epoxy resins derived from bisphenols such as novolac epoxy resins.

The above-mentioned hard coating composition may further contain a polymerization initiator. Examples of the polymerization initiator include radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, and the like, which can be appropriately selected and used. The polymerization initiators are those that decompose by at least one of active energy ray irradiation and heating, and generate free radicals or cations for radical polymerization and cationic polymerization. The radical polymerization initiator may release at least any one of active energy ray irradiation and heating to start radical polymerization. For example, as a thermal radical polymerization initiator, organic peroxides, such as hydrogen peroxide and perbenzoic acid, azo compounds, such as azobisbutyronitrile, etc. are mentioned. As active energy ray radical polymerization initiators, there are type 1 radical polymerization initiators that generate free radicals by the decomposition of molecules, and type 2 that coexist with tertiary amines to generate free radicals by hydrogen abstraction reaction. Radical polymerization initiators are used alone or in combination. The cationic polymerization initiator may release at least one of active energy ray irradiation and heating to start cationic polymerization. As the cationic polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron (II) complex, and the like can be used. These can start cationic polymerization by either or all of active energy ray irradiation or heating depending on the structure.

The polymerization initiator may preferably be contained at 0.1 to 10% by mass relative to 100% by mass of the entire hard coating composition. If the content of the polymerization initiator is within the above range, the curing can be carried out sufficiently, and the mechanical properties or adhesive force of the finally obtained coating film can be set in a good range, and the curing shrinkage is not likely to occur. Poor adhesion or cracking and curling tendency.

The above-mentioned hard coating composition may further include one or more selected from the group consisting of solvents and additives. The above-mentioned solvent can dissolve or disperse the above-mentioned polymerizable compound and polymerization initiator, as long as it is a solvent known as a solvent for a hard coat composition in the technical field, and it can be used within a range that does not hinder the effect of the present invention. The aforementioned additives may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

The adhesive layer is a layer with adhesive function and has the function of adhering the optical film to other components. As the forming material of the adhesive layer, generally known ones can be used. For example, a thermosetting resin composition or a photocuring resin composition can be used. In this case, by supplying energy afterwards, the resin composition can be polymerized and hardened.

The adhesive layer may be a layer which is called a pressure sensitive adhesive (PSA, Pressure Sensitive Adhesive) that is adhered to an object by pressing. Pressure-sensitive adhesives can be used as "substances that are adhesive at room temperature and adhere to the material to be adhered with a lighter pressure" (JIS K6800), and can also be used as an adhesive to "enclose specific ingredients in protection It is a capsule type adhesive agent that can maintain stability until the film is covered (microcapsules) and destroyed by appropriate methods (pressure, heat, etc.)" (JIS K6800).

The hue adjustment layer is a layer with a hue adjustment function, and is a layer that can adjust the layered body including the optical film to the target hue. The hue adjusting layer is, for example, a layer containing resin and coloring agent. Examples of the coloring agent include inorganic pigments such as titanium oxide, zinc oxide, red lead, titanyl calcined pigments, ultramarine blue, cobalt aluminate, and carbon black; azo compounds, quinacridone compounds, and anthraquinone Organic pigments such as series compounds, perylene series compounds, isoindolinone series compounds, phthalocyanine series compounds, quinophthalone series compounds, anthracene series compounds, and diketopyrrolopyrrole series compounds; barium sulfate, calcium carbonate, etc. Extender pigments; and dyes such as basic dyes, acid dyes, and mordant dyes.

The refractive index adjustment layer is a layer having a refractive index adjustment function, for example, has a refractive index different from that of an optical film, and is a layer that can give a specific refractive index to the optical laminate. The refractive index adjustment layer may be, for example, a resin layer containing appropriately selected resins and pigments as appropriate, or a metal film. Examples of pigments that adjust the refractive index include silica, alumina, antimony oxide, tin oxide, titanium oxide, zirconium oxide, and tantalum oxide. The average primary particle size of the pigment may be 0.1 μm or less. By setting the average primary particle size of the pigment to 0.1 μm or less, the diffuse reflection of the light passing through the refractive index adjustment layer can be prevented and the decrease in transparency can be prevented. Examples of metals used in the refractive index adjustment layer include titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and nitride Metal oxides or metal nitrides such as silicon.

In a preferred embodiment of the present invention, the optical film of the present invention is more useful as a front panel of a display device, especially a front panel of a flexible display device (hereinafter, sometimes referred to as window film). The flexible display device has, for example, a flexible functional layer and an optical film superimposed on the flexible functional layer to function as a front panel. That is, the front panel of the flexible display device is arranged on the visible side of the flexible functional layer. The front panel has the function of protecting the flexible functional layer.

Examples of display devices include: televisions, smart phones, mobile phones, car navigation systems, tablet PCs (Personal Computers), portable game consoles, electronic paper, indicators, bulletin boards, clocks, and smart watches Wearable devices, etc. As the flexible display device, all display devices having flexibility characteristics can be cited.

[Flexible display device] The invention also provides a flexible display device equipped with the optical film of the invention. The optical film of the present invention is preferably used as a front panel in a flexible display device, and the front panel is sometimes called a window film. The flexible display device includes a laminated body for a flexible display device and an organic EL display panel. The laminated body for a flexible display device is arranged on the visible side of the organic EL display panel and is flexible. The laminated body for the flexible display device may include a window film, a polarizing plate, and a touch sensor. The order of these layers is arbitrary, and it is preferable to laminate the window film, polarizing plate, and touch sensor in order from the viewing side Mirror or window film, touch sensor, polarizing plate. If there is a polarizing plate on the viewing side of the touch sensor, the pattern of the touch sensor is not easy to see, and the visibility of the displayed image becomes good, which is better. Each member can be laminated using adhesives, adhesives, etc. In addition, it may be provided with a light-shielding pattern formed on at least one surface of any one of the above-mentioned window film, polarizer, and touch sensor.

[Polarizer] The flexible display device of the present invention may further include a polarizing plate, preferably a circular polarizing plate. The circular polarizing plate is a functional layer that has a function of transmitting only the right-handed circularly polarized light component or the left-handed circularly polarized light component by laminating a λ/4 phase difference plate on the linear polarizing plate. For example, it is used to block the conversion of external light into right-handed circularly polarized light, which is reflected by the organic EL panel to become left-handed circularly polarized outer light, and only transmits the luminous components of the organic EL, thereby suppressing the influence of reflected light and making the image Easy to see. In order to achieve the circular polarization function, the absorption axis of the linear polarizer and the late axis of the λ/4 retardation plate need to be 45° in theory, and 45±10° in practice. The linear polarizing plate and the λ/4 retardation plate do not necessarily need to be laminated adjacently, as long as the relationship between the absorption axis and the slow phase axis satisfies the above range. It is preferable to achieve complete circular polarization at the full wavelength, but this is not necessarily required in practice. Therefore, the circular polarization plate in the present invention also includes an elliptical polarization plate. It is also preferable to laminate a λ/4 retardation film on the visibility side of the linear polarizing plate to make the emitted light circularly polarized, thereby improving the visibility when wearing polarized sunglasses.

The linear polarizer is a functional layer that has the function of passing light that vibrates in the direction of the transmission axis, but blocking the polarization of the vibration component perpendicular to it. The above-mentioned linear polarizing plate may be a structure having a linear polarizing element alone, or a structure having a linear polarizing element and a protective film attached to at least one surface thereof. The thickness of the linear polarizing plate may be 200 μm or less, preferably 0.5-100 μm. If the thickness is within the above range, the flexibility tends not to be easily reduced. The linear polarizing element may be a film-type polarizing element manufactured by dyeing and stretching a polyvinyl alcohol (PVA) film. By adsorbing dichroic pigments such as iodine to the PVA-based film aligned by stretching, or by stretching while adsorbing on PVA, the dichroic pigments are aligned to exhibit polarization performance. In the manufacture of the above-mentioned film-type polarizing element, it can also have steps such as swelling, cross-linking with boric acid, washing with aqueous solution, and drying. The stretching or dyeing step may be performed on a PVA-based film alone, or may be performed in a state of being laminated with other films such as polyethylene terephthalate. The thickness of the PVA-based film used is preferably 10-100 μm, and the stretching ratio is preferably 2-10 times. Furthermore, as another example of the above-mentioned polarizing element, it may be a liquid crystal coating type polarizing element formed by coating a liquid crystal polarizing composition. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. The above-mentioned liquid crystalline compound only needs to have the property of displaying a liquid crystal state, and if it has an alignment state of the same order as the smectic sequence, it can exhibit higher polarization performance, so it is preferable. Moreover, it is also preferable that the liquid crystal compound has a polymerizable functional group.

The dichroic dye is a dye that is aligned together with the liquid crystal compound to exhibit dichroism. The dichroic dye itself may have liquid crystallinity or may have a polymerizable functional group. Any compound in the liquid crystal polarizing composition has a polymerizable functional group. The above-mentioned liquid crystal polarizing composition may further include a starter, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The above-mentioned liquid crystal polarizing layer is manufactured by coating a liquid crystal polarizing composition on an alignment film to form a liquid crystal polarizing layer. The liquid crystal polarizing layer can be formed thinner than the thickness of the film-type polarizing element. The thickness of the liquid crystal polarizing layer may preferably be 0.5-10 μm, more preferably 1-5 μm. The above-mentioned alignment film can be produced, for example, by coating an alignment film forming composition on a substrate, and imparting alignment properties by rubbing, polarized light irradiation, or the like. In addition to the alignment agent, the alignment film forming composition may also include a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. As the above-mentioned alignment agent, for example, polyvinyl alcohols, polyacrylates, polyamides, and polyimines can be used. In the case of applying optical alignment, it is preferable to use an alignment agent containing a cinnamate group. The weight average molecular weight of the polymer used as the alignment agent can be about 10,000-1,000,000. Regarding the thickness of the aforementioned alignment film, from the viewpoint of the alignment restriction force, it is preferably 5 to 10,000 nm, and more preferably 10 to 500 nm. The above-mentioned liquid crystal polarizing layer may be peeled from the base material and transferred and laminated, or the above-mentioned base material may be directly laminated. The above-mentioned base material is also preferably used as a transparent base material for a protective film, a phase difference plate, and a window.

The protective film may be a transparent polymer film, and the materials and additives used for the transparent substrate may be used. Preferred are cellulose-based films, olefin-based films, acrylic-based films, and polyester-based films. It can be a coating type protective film obtained by applying and curing a cationic curing composition such as epoxy resin or a radical curing composition such as acrylate. If necessary, it can also contain plasticizers, ultraviolet absorbers, infrared absorbers, pigments or dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, Lubricants, solvents, etc. The thickness of the protective film can be 200 μm or less, preferably 1-100 μm. If the thickness of the protective film is within the above range, the flexibility of the protective film will not easily decrease. The protective film can also double as the transparent substrate of the window.

The above-mentioned λ/4 retardation plate is a film that gives a λ/4 retardation to the direction orthogonal to the direction of the incident light, that is, the in-plane direction of the film. The above-mentioned λ/4 retardation plate may be a stretched retardation plate manufactured by stretching a polymer film such as a cellulose-based film, an olefin-based film, or a polycarbonate-based film. If necessary, it can also contain phase difference adjusters, plasticizers, ultraviolet absorbers, infrared absorbers, pigments or dyes and other coloring agents, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, and antistatic Agents, antioxidants, lubricants, solvents, etc. The thickness of the extended phase difference plate may be 200 μm or less, preferably 1-100 μm. If the thickness is within the above range, there is a tendency that the flexibility of the film is not easily reduced. Furthermore, as another example of the above-mentioned λ/4 retardation plate, a liquid crystal coating type retardation plate formed by coating a liquid crystal composition may be used. The above-mentioned liquid crystal composition contains a liquid crystal compound exhibiting liquid crystal states such as nematic, cholesteric, and smectic. Any compound including the liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The above-mentioned liquid crystal coating type retardation plate may further include a starter, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be manufactured by applying a liquid crystal composition to an alignment film and curing it to form a liquid crystal retardation layer in the same manner as described in the liquid crystal polarizing layer. The liquid crystal coating type retardation plate can be formed thinner than the extension type retardation plate. The thickness of the above-mentioned liquid crystal polarizing layer can usually be 0.5-10 μm, preferably 1-5 μm. The above-mentioned liquid crystal coating type retardation plate may be peeled from the base material and transferred and laminated, or the base material may be directly laminated. The above-mentioned base material is also preferably used as a transparent base material for a protective film, a phase difference plate, and a window.

Generally, the shorter the wavelength, the greater the birefringence, and the longer the wavelength, the smaller the birefringence. In this case, the phase difference of λ/4 cannot be achieved in the entire visible light region. Therefore, in most cases, the in-plane phase difference of λ/4 becomes 100 to 180 nm relative to the vicinity of 560 nm where the visibility is higher. It is better to design for 130～150 nm method. It is preferable to use a reverse dispersion λ/4 retardation plate made of a material having birefringence wavelength dispersion characteristics opposite to that of usual, which can improve the visibility. It is also preferable to use the material described in Japanese Patent Laid-Open No. 2007-232873 in the case of an extended retardation plate and the Japanese patent in the case of a liquid crystal coating type retardation plate. Those mentioned in JP 2010-30979. Furthermore, as another method, a technique of obtaining a wide-band λ/4 retardation plate by combining with a λ/2 retardation plate is also known (Japanese Patent Laid-Open No. 10-90521). The λ/2 retardation plate is also manufactured by the same material method as the λ/4 retardation plate. The combination of the extension type retardation plate and the liquid crystal coating type retardation plate is arbitrary, and it is preferable to use a liquid crystal coating type retardation plate for any one of them to make the thickness thinner. Among the above-mentioned circularly polarizing plates, in order to improve the visibility in the oblique direction, a method of laminating positive C plates is also known (Japanese Patent Laid-Open No. 2014-224837). The positive C plate can be a liquid crystal coating type retardation plate or an extended type retardation plate. The phase difference in the thickness direction is -200 to -20 nm, preferably -140 to -40 nm.

[Touch Sensor] The flexible display device of the present invention may further include a touch sensor. The touch sensor can be used as an input mechanism. As a touch sensor, various methods such as a resistive film method, a surface elastic wave method, an infrared method, an electromagnetic induction method, and an electrostatic capacitance method have been proposed in the industry, and any method may be adopted. Among them, the electrostatic capacitance method is preferred. The capacitive touch sensor is divided into an active area and an inactive area located at the outline of the active area. The active area corresponds to the area that is the display part of the display panel and senses the user's touch. The inactive area corresponds to the area that is the non-display part of the display device that does not display the picture.的区。 The area. The touch sensor may include: a substrate having flexibility characteristics; a sensing pattern formed on the active area of the substrate; and each sensing line formed on the inactive area of the substrate for passing through the pad portion Connect the above-mentioned sensing pattern to an external drive circuit. As a substrate with flexibility, the same material as the transparent substrate of the above-mentioned window can be used. Regarding the substrate of the touch sensor, in terms of suppressing cracks of the touch sensor, it is preferably one with a toughness of 2,000 MPa% or more. More preferably, the toughness may be 2,000 to 30,000 MPa%. Here, the toughness is defined as the area under the curve up to the point of failure by using the stress-strain curve (MPa)-strain (%) obtained through the tensile test of the polymer material.

The aforementioned sensing pattern may include a first pattern formed in the first direction and a second pattern formed in the second direction. The first pattern and the second pattern are arranged in mutually different directions. The first pattern and the second pattern are formed on the same layer. In order to sense the touch location, each pattern must be electrically connected. The first pattern is a form in which each unit pattern is connected to each other via a joint, and the second pattern is a structure in which each unit pattern is separated into an island form. Therefore, in order to electrically connect the second pattern, another bridge electrode is required. The sensing pattern can use well-known transparent electrode materials. Examples include: indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium zinc tin oxide (IZTO), indium gallium zinc oxide (IGZO), cadmium tin oxide (CTO) ), PEDOT (poly(3,4-ethylenedioxythiophene), poly(3,4-ethylenedioxythiophene)), carbon nanotube (CNT), graphene, metal wire, etc., these can be used alone or in combination Use more than two types. Preferably, ITO can be used. The metal used in the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, and chromium. These can be used individually or in mixture of 2 or more types.

The bridging electrode can be formed on the upper part of the insulating layer via the insulating edge layer on the upper part of the sensing pattern, and the bridging electrode can be formed on the substrate, and the insulating layer and the sensing pattern can be formed thereon. The bridging electrode may be formed of the same material as the sensing pattern, or may be formed of metals such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or two or more alloys of these. The first pattern and the second pattern must be electrically insulated, so an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joints of the first pattern and the bridging electrodes, or may be formed as a structure covering the sensing pattern. In the latter case, the bridge electrode can be connected to the second pattern via a contact hole formed in the insulating layer. Regarding the above-mentioned touch sensor, it is used to appropriately compensate for the difference in transmittance between the patterned area and the unpatterned non-patterned area, specifically, it is induced by the difference in refractive index in these areas The method for the difference in light transmittance may further include an optical adjustment layer between the substrate and the electrode, and the optical adjustment layer may include an inorganic insulating material or an organic insulating material. The optical adjustment layer can be formed by coating a photocuring composition containing a photocuring organic binder and a solvent on a substrate. The above-mentioned photocurable composition may further contain inorganic particles. The above-mentioned inorganic particles can increase the refractive index of the optical adjustment layer. The photocurable organic adhesive may include, for example, copolymers of monomers such as acrylate monomers, styrene monomers, and carboxylic acid monomers. The photocurable organic adhesive may be, for example, a copolymer containing repeating units that are different from each other, such as epoxy-containing repeating units, acrylate repeating units, and carboxylic acid repeating units. The above-mentioned inorganic particles may include, for example, zirconium oxide particles, titanium oxide particles, and alumina particles. The aforementioned photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

[Next layer] The window film, circular polarizer, touch sensor and other layers forming the laminate for the flexible display device, as well as the film members such as the linear polarizer and λ/4 phase difference plate constituting each layer, can be bonded with an adhesive. As the adhesive, water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent-volatile adhesives, water-based solvent-volatile adhesives, moisture-curing adhesives, and heat-curing adhesives can be used Adhesives, anaerobic curing type adhesives, active energy ray curing type adhesives, curing agent mixed type adhesives, hot melt type adhesives, pressure sensitive adhesives, pressure sensitive adhesives, rewetting type adhesives, etc. user. Among them, water-based solvent volatile adhesives, active energy ray hardening adhesives, and adhesives can be used well. The thickness of the subsequent layer can be appropriately adjusted according to the required adhesive force, etc., for example, 0.01-500 μm, preferably 0.1-300 μm. The adhesive layer may have a plurality of layers in the above-mentioned laminate for flexible display devices, and the thicknesses and the types of adhesives used may be the same or different.

As the above-mentioned water-based solvent-volatile adhesive, water-dispersed polymers such as polyvinyl alcohol-based polymers, starch, etc., ethylene-vinyl acetate-based latex, styrene-butadiene-based latex, and other water-dispersed polymers can be used as the main Agent polymer. In addition to water and the above-mentioned main agent polymer, crosslinking agents, silane compounds, ionic compounds, crosslinking catalysts, antioxidants, dyes, pigments, inorganic fillers, organic solvents, etc. can also be formulated. When the water-based solvent-volatile adhesive is used for bonding, the water-based solvent-volatile adhesive is injected between the layers to be bonded to bond the bonded layers, and then dried to impart adhesiveness. In the case of using the above-mentioned water-based solvent-volatile adhesive, the thickness of the adhesive layer may be 0.01-10 μm, preferably 0.1-1 μm. When the water-based solvent-volatile adhesive is used in the formation of multiple layers, the thickness of each layer and the type of the adhesive may be the same or different.

The active energy ray curable adhesive can be formed by curing an active energy ray curable composition containing a reactive material that forms an adhesive layer by irradiating active energy rays. The active energy ray hardening composition may contain at least one polymer of a radical polymerizable compound and a cation polymerizable compound similar to the hard coat composition. The above-mentioned so-called radically polymerizable compound is the same as the hard coat composition, and the same kind as the hard coat composition can be used. The radically polymerizable compound used in the adhesive layer is preferably a compound having an acrylic group. In order to reduce the viscosity of the adhesive composition, it is also preferable to include a monofunctional compound.

The above-mentioned cationically polymerizable compound is the same as the hard coating composition, and the same type as the hard coating composition can be used. The cationic polymerizable compound used in the active energy ray curing composition is more preferably an epoxy compound. In order to reduce the viscosity of the adhesive composition, it is also preferable to include a monofunctional compound as a reactive diluent. The active energy ray composition may further include a polymerization initiator. As the polymerization initiator, there are radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc., which can be appropriately selected and used. The polymerization initiators are those that decompose by at least one of active energy ray irradiation and heating, and generate free radicals or cations for radical polymerization and cationic polymerization. In the description of the hard coating composition, an initiator that can start at least one of radical polymerization and cationic polymerization by active energy ray irradiation can be used.

The active energy ray curable composition may further include an ion scavenger, an antioxidant, a chain transfer agent, an adhesion imparting agent, a thermoplastic resin, a filler, a fluid viscosity adjuster, a plasticizer, a defoamer solvent, an additive, and a solvent. In the case of bonding with the above-mentioned active energy ray-curing adhesive, the above-mentioned active energy ray-curing composition is applied to either or both of the layers to be bonded and then bonded, and then is bonded by either The layer or both of the adhered layers are irradiated with active energy rays to harden them, thereby enabling adhesion. In the case of using the active energy ray-curable adhesive, the thickness of the adhesive layer may be 0.01-20 μm, preferably 0.1-10 μm. When the active energy ray-curable adhesive is used in the formation of multiple layers, the thickness of each layer and the type of adhesive used may be the same or different.

As the above-mentioned adhesive, depending on the main agent polymer, it may be classified into an acrylic adhesive, a urethane adhesive, a rubber adhesive, a silicone adhesive, etc., and any of them may be used. In the adhesive, in addition to the main agent polymer, crosslinking agents, silane compounds, ionic compounds, crosslinking catalysts, antioxidants, adhesion imparting agents, plasticizers, dyes, pigments, inorganic fillers, etc. can also be blended . Each component constituting the adhesive is dissolved and dispersed in a solvent to obtain an adhesive composition, and the adhesive composition is applied on a substrate and dried to form an adhesive layer (adhesive layer). The adhesive layer can be formed directly, or the one formed on the substrate can be transferred by transfer. In order to cover the adhesive surface before bonding, it is also preferable to use a release film. In the case of using the above-mentioned adhesive, the thickness of the adhesive layer may be 1 to 500 μm, preferably 2 to 300 μm. When the above-mentioned adhesive is used in the formation of multiple layers, the thickness of each layer and the type of adhesive used may be the same or different.

[Shading Pattern] The aforementioned light-shielding pattern can be applied as at least a part of the frame or housing of the aforementioned flexible display device. The wiring arranged at the edge of the flexible display device is shielded by the light-shielding pattern and is not easily visible, so the visibility of the image is improved. The aforementioned light-shielding pattern may be in the form of a single layer or a multiple layer. The color of the shading pattern is not particularly limited, and can have various colors such as black, white, and metallic colors. The light-shielding pattern can be formed using pigments used to realize colors, and polymers such as acrylic resins, ester resins, epoxy resins, polyurethanes, and silicones. These can also be used alone or in a mixture of two or more. The above-mentioned light-shielding pattern can be formed by various methods such as printing, offset printing, and inkjet. The thickness of the light-shielding pattern is usually 1-100 μm, preferably 2-50 μm. Moreover, it is also preferable to give a shape such as an inclination to the thickness direction of the light shielding pattern. [Example]

Hereinafter, the present invention will be explained in more detail with examples. The "%" and "parts" in the examples refer to mass% and parts by mass unless otherwise stated. First, the evaluation method will be described.

＜Determination of elastic modulus＞ Using "Autograph AG-IS" manufactured by Shimadzu Corporation, the elastic modulus of the polyamide imide film obtained in the examples and comparative examples was measured. A film with a width of 10 mm is produced, and the S-S curve is measured under the conditions of a distance between the chucks of 50 mm and a stretching speed of 10 mm/min, and the elastic modulus is calculated based on its slope.

＜Measurement of light transmittance＞ For the total light transmittance Tt of the sample, in accordance with JIS K 7105:1981, the optical film obtained in the examples and comparative examples was measured using a fully automatic direct reading haze meter HGM-2DP manufactured by Suga Tester.

＜Measurement of humidity expansion rate (CME)＞ The CME was measured using "TMA/SS6100 Type" manufactured by Hitachi High-Tech Science Co., Ltd. Specifically, a film with a width of 2 mm and a length of 20 mm is placed in a chuck (the distance between the chucks is 10 mm) in a nitrogen atmosphere, and it is maintained at 60°C and 0% RH until saturation under a load of 20 mN. After that, the temperature was controlled to 60°C and 90% RH, and the humidity expansion rate of the film when kept for 1 hour was measured. Furthermore, set the humidity expansion rate as the length of the film as L (mm), set the change in the length of the film before and after it is kept at 90% RH for 1 hour as ΔL (mm), and set the change in humidity as It is ΔM(%) and is calculated by the following formula. Humidity expansion rate=(1/L)(ΔL/ΔM)

＜YI value of film＞ According to JIS K 7373: 2006, the YI value (Yellow Index) of the sample was measured using the UV-Vis-NIR Spectrophotometer V-670 manufactured by JASCO Corporation. After the background measurement is performed without the sample, the sample is set in the sample holder, and the transmittance of light from 300 to 800 nm is measured, and 3 stimulus values (X, Y, Z) are obtained. The YI value was calculated based on the following formula. YI=100×(1.2769X－1.0592Z)/Y

＜Haze＞ The haze of the optical film is measured in accordance with JIS K7105:1981, using the automatic direct reading haze meter HGM-2DP manufactured by Suga Testing Machine Co., Ltd.

＜Measurement of pencil hardness＞ As the surface hardness of the polyimide film obtained in the examples and comparative examples, the pencil hardness of the film surface is used in accordance with JIS K 5600-5-4:1999. The load is set to 100 g, the scanning speed is set to 60 mm/min, and the scratches are evaluated under an environment of 4,000 lux, and the surface hardness (pencil hardness) is measured.

＜Determination of weight average molecular weight＞ Gel Permeation Chromatography (GPC) determination (1) Pretreatment method Add DMF (Dimethyl Formamide) chaotropic solution (10 mmol/L lithium bromide solution) to the sample at a concentration of 2 mg/mL, stir at 80°C for 30 minutes while heating, and after cooling, Filter with a 0.45 μm membrane filter, and use the result as a measurement solution. (2) Measurement conditions Column: TSKgel α-2500((7)7.8 mm diameter×300 mm)×1, α-M((13)7.8 mm diameter×300 mm)×2 pieces manufactured by Tosoh Co., Ltd. Eluent: DMF (add 10 mmol/L lithium bromide) Flow rate: 1.0 mL/min Detector: RI detector Column temperature: 40℃ Injection volume: 100 μL Molecular weight standard: standard polystyrene

＜Measurement of thickness＞ The thickness of the polyimide film obtained in Examples and Comparative Examples was measured using a micrometer ("ID-C112XBS" manufactured by Mitutoyo Co., Ltd.).

<Example 1> [Preparation of polyamide imide resin (1)] In a nitrogen atmosphere, add 2,2'-bis(trifluoromethyl)benzidine (TFMB) and N,N to a separable flask equipped with stirring wings so that the solid content of TFMB becomes 4.90% by mass -Dimethylacetamide (DMAc), stirring at room temperature while dissolving TFMB in DMAc. Next, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA) was added to the flask so that it became 30.30 mol% with respect to TFMB, and stirred at room temperature for 3 hours. Then, after cooling to 10°C, 4,4'oxybis(benzyl chloride) (OBBC) was added so as to become 5.05 mol% with respect to TFMB, and 2 was added so as to become 27.28 mol% with respect to TFMB. ,5-Bis(trifluoromethyl)terephthalic acid chloride (6FTPC), stirred for 10 minutes, and then added OBBC so that it became 5.05 mol% relative to TFMB, and added it so that it became 27.28 mol% 6FTPC, and stir for 30 minutes. After that, the same amount of DMAc as the DMAc added for the first time was added, and after stirring for 10 minutes, 6FTPC was added so as to be 6.06 mol% with respect to TFMB, and stirred for 2 hours. Then, 70.71 mol% of diisopropylethylamine and 4-picoline relative to TFMB were added to the flask, and 212.12 mol% of acetic anhydride relative to TFMB was added to the flask. After stirring for 30 minutes, the internal temperature was raised. The temperature was raised to 70°C and further stirred for 3 hours to obtain a reaction liquid. The obtained reaction solution was cooled to room temperature, and poured into a large amount of methanol in a linear fashion, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain polyimide resin (1).

[Manufacturing of polyimide film (1)] To the obtained polyimide resin (1), DMAc was added so that the concentration became 10% by mass to prepare a polyimide varnish (1). On the smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name "A4100"), use an applicator to coat the polyimide varnish (1 ), dried at 50°C for 30 minutes, and then dried at 140°C for 15 minutes to obtain an independent film. The independent film was fixed in a gold frame, and then dried at 200° C. for 60 minutes to obtain a polyamide imide film (1) with a thickness of 45 μm.

<Example 2> [Preparation of polyamide imide resin (2)] Under a nitrogen atmosphere, add TFMB and DMAc to a separable flask equipped with stirring wings so that the solid content of TFMB becomes 2.36% by mass, and stir while stirring at room temperature to dissolve TFMB in DMAc. Next, 6FDA was added to the flask so that it became 30.30 mol% with respect to TFMB, and stirred at room temperature for 3 hours. Then, after cooling to 10°C, OBBC was added so that it became 5.05 mol% with respect to TFMB, and 2,2'-bis(trifluoromethyl)-4,4 was added so that it became 27.28 mol% with respect to TFMB. '-Biphenyl Dimethyl Chloride (6FBPDOC), and stir for 10 minutes, and then add OBBC so that it becomes 5.05 mol% relative to TFMB, and add 6FBPDOC so that it becomes 27.28 mol% relative to TFMB, and stir for 30 minute. After that, the same amount of DMAc as the DMAc added for the first time was added, and after stirring for 10 minutes, 6FBPDOC was added so as to be 6.06 mol% with respect to TFMB, and stirred for 2 hours. Then, 70.71 mol% of diisopropylethylamine and 4-picoline relative to TFMB were added to the flask, and 212.12 mol% of acetic anhydride relative to TFMB was added to the flask. After stirring for 30 minutes, the internal temperature was raised. The temperature was raised to 70°C and further stirred for 3 hours to obtain a reaction liquid. The obtained reaction solution was cooled to room temperature, and poured into a large amount of methanol in a linear fashion, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain a polyimide resin (2).

[Manufacturing of Polyimide Film (2)] To the obtained polyimide resin (2), DMAc was added so that the concentration would be 10% by mass to produce a polyimide varnish (2). On the smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name "A4100"), the thickness of the independent film becomes 55 μm using an applicator to coat the polyimide varnish (2 ), dried at 50°C for 30 minutes, and then dried at 140°C for 15 minutes to obtain an independent film. The independent film was fixed on a gold frame, and then dried at 200° C. for 60 minutes to obtain a polyamide imide film (2) with a thickness of 50 μm.

<Comparative example 1> [Preparation of polyamide imide resin (3)] Under a nitrogen atmosphere, add TFMB and DMAc to a separable flask equipped with stirring wings so that the solid content of TFMB becomes 5.54% by mass, and stir while stirring at room temperature to dissolve TFMB in DMAc. Next, 6FDA was added to the flask so that it became 30.20 mol% with respect to TFMB, and it stirred at room temperature for 3 hours. Thereafter, after cooling to 10°C, OBBC was added so as to be 10.07 mol% with respect to TFMB, and terephthalic acid chloride (TPC) was added so as to be 54.35 mol% with respect to TFMB, and stirred for 30 minutes. After that, the same amount of DMAc as the DMAc added for the first time was added, and after stirring for 10 minutes, TPC was added so as to be 6.04 mol% with respect to TFMB, and stirred for 2 hours. Then, 70.46 mol% of diisopropylethylamine and 4-picoline relative to TFMB were added to the flask, and 211.37 mol% of acetic anhydride relative to TFMB were added to the flask. After stirring for 30 minutes, the internal temperature was raised. The temperature was raised to 70°C and further stirred for 3 hours to obtain a reaction liquid. The obtained reaction solution was cooled to room temperature, and poured into a large amount of methanol in a linear fashion, and the deposited precipitate was taken out, immersed in methanol for 6 hours, and washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain a polyimide resin (3).

[Manufacturing of polyimide film (3)] To the obtained polyimide resin (3), DMAc was added so that the concentration became 10% by mass to produce a polyimide varnish (3). On the smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name "A4100"), the thickness of the independent film becomes 55 μm using an applicator to coat the polyimide varnish (3 ), dried at 50°C for 30 minutes, and then dried at 140°C for 15 minutes to obtain an independent film. The independent film was fixed on a gold frame, and then dried at 200° C. for 60 minutes to obtain a polyamide imide film (3) with a thickness of 50 μm.

According to the above method, the weight average molecular weight (Mw) of the polyimide resins (1) to (3), the elastic modulus and CME of the polyimide films (1) to (3) , Light transmittance, YI value and haze are measured. The results obtained are shown in Table 1. In addition, the pencil hardness of the optical film (1) is 3 B, and the pencil hardness of the optical film (2) is 2 H.

[Table 1] Polyimide resin film Polyimide resin Modulus of Elasticity [GPa] CME [ppm] Light transmittance [%] YI Haze [%] species Mw Example 1 (1) (1) 237,000 5 19 93 2.5 0.1 2 (2) (2) 363,000 5 17 92 3.1 2.4 Comparative example 1 (3) (3) 402,000 5 25 92 1.4 0.2

Claims (15)

An optical film comprising the following polyimide-based resin, the polyimide-based resin having at least the structural unit represented by formula (1): [化33]

[In formula (1), Ar ¹ represents a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbons, and X represents a divalent organic group], and the structural unit represented by formula (2): [化34]

[In formula (2), X represents a divalent organic group and Y represents a tetravalent organic group], and the weight average molecular weight is 200,000 to 1,000,000. The optical film of claim 1, wherein the fluoroalkyl group having 1 to 12 carbon atoms in Ar ¹ in the formula (1) is a perfluoroalkyl group having 1 to 12 carbon atoms. The optical film of claim 1 or 2, wherein the structural unit represented by the formula (1) contains the aromatic group represented by the formula (4) as Ar ¹ , [化35]

[In formula (4), R ¹ represents a fluoroalkyl group having 1 to 12 carbon atoms, and n and k independently represent an integer of 1 to 4, where n and/or k represent an integer of 2 to 4 , A plurality of R ¹ may be the same or different from each other, * indicates a bonding bond]. Such as the optical film of claim 3, wherein the two bonding keys in the formula (4) are in alignment with each other. Such as the optical film of claim 3 or 4, wherein k in formula (4) is 1 or 2. The optical film according to any one of claims 3 to 5, wherein R ¹ in formula (4) represents a perfluoroalkyl group having 1 to 12 carbon atoms, and n is 1 or 2. The optical film according to any one of claims 1 to 6, wherein the structural unit represented by formula (1) and/or the structural unit represented by formula (2) includes the divalent organic group represented by formula (5) as X , [化36]

[In formula (5), Ar ² represents a divalent aromatic group that may have a substituent, V represents a single bond, -O-, diphenylmethylene, stilbene, a divalent hydrocarbon group with 1 to 12 carbons, -SO ₂ -, -S-, -CO-, -PO-, -PO ₂ -, -N(R ^a )- or -Si(R ^b ) ₂ -, where the hydrocarbon group may include an alicyclic structure the hydrogen atom contained in the hydrocarbon group each independently may be substituted by a halogen atom, R ^a and R ^b each independently represent a hydrogen atom, or a hydrocarbon group may be substituted with the halogen atom of from 1 to 12 carbon atoms, m represents 0 to 3, Integer, * means bonding key]. Such as the optical film of claim 7, wherein m in formula (5) is 1. The optical film of any one of claims 1 to 6, wherein the structural unit represented by formula (1) and/or the structural unit represented by formula (2) includes the divalent organic group represented by formula (5a) as X , [化37]

[In formula (5), R ² represents a fluoroalkyl group having 1 to 12 carbon atoms, and p and q independently represent an integer of 1 to 4, and when p and/or q represent an integer of 2 to 4 , A plurality of R ² may be the same or different from each other, * indicates a bonding bond]. The optical film according to any one of claims 1 to 6, wherein the structural unit represented by formula (1) and/or the structural unit represented by formula (2) includes the divalent organic group represented by formula (5c) as X , [化38]

[* in formula (5c) represents a bonding bond]. The optical film of any one of claims 1 to 10 has a thickness of 10 to 200 μm. A flexible display device is provided with the film of any one of claims 1 to 11. For example, the flexible display device of claim 12 further includes a touch sensor. For example, the flexible display device of claim 12 or 13 further includes a polarizing plate. A polyamide imine resin, which has at least the structural unit represented by formula (1): [化39]

[In formula (1), Ar ¹ represents a divalent aromatic group having a fluoroalkyl group having 1 to 12 carbons, and X represents a divalent organic group], and includes the aromatic group represented by formula (4) as formula ( 1) Ar ^{1 in} : [化40]

[In formula (4), R ¹ represents a fluoroalkyl group having 1 to 12 carbon atoms, and n and k independently represent an integer of 1 to 4, where n and/or k represent an integer of 2 to 4 , A plurality of R ¹ may be the same or different from each other, * represents a bonding bond]; and the structural unit represented by formula (2): [化41]

[In formula (2), X represents a divalent organic group, and Y represents a tetravalent organic group].