TW202035537A - Optical film, flexible display device and resin composition - Google Patents

Abstract

The invention relates to an optical film, a flexible display device and a resin composition. The invention aims to provide a resin film with high elastic modulus. The settlement solution of the optical film is characterized in that the optical film comprises at least one resin in a group composed of polyimide resin and polyamide resin; the ratio (INa/ICH3) between the Na ionic strength (INa) of the optical film obtained through time of flight secondary ion mass spectrometry relative to the CH3 ionic strength (ICH3) is above 0.2.

Description

Optical film, flexible display device, and resin composition

The present invention relates to an optical film, a flexible display device, and a resin composition.

Nowadays, image display devices such as liquid crystal display devices or organic EL (Electroluminescence) display devices are widely used in various applications such as mobile phones and smart watches. As the front panel of such an image display device, glass has been used, but the glass is very rigid and easy to break, so it is difficult to use it as a front panel material for a flexible display device, for example. Therefore, the application of a polymer material as one of the materials to replace glass is studied, for example, an optical film using a polyimide-based resin is studied (for example, Patent Document 1). [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-119132

[The problem to be solved by the invention]

However, when optical films using polyimide resins and polyimide resins are used in flexible display devices, etc., damage may occur in the optical film due to bending or contact with external factors. , Wrinkles and other defects. The inventors studied various methods to improve the above, and found that by increasing the elastic modulus of the optical film, defects such as damage are not easily generated in the optical film. Therefore, the subject of the present invention is to provide a resin film with a higher elastic modulus. [Technical means to solve the problem]

In order to solve the above-mentioned problems, the inventors of the present invention focused on the types and amounts of components contained in the resin film and conducted intensive research. As a result, the ratio of the ionic strength of Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) obtained by the time-of-flight secondary ion mass spectrometry in the optical film For an optical film of 0.2 or more, it was unexpectedly found that it is easy to increase the elastic modulus, thus completing the present invention.

That is, the present invention includes the following preferable aspects. [1] An optical film containing at least one resin selected from the group consisting of polyimide resins and polyimide resins, and the optical film is analyzed by time-of-flight secondary ion mass spectrometry The ratio (I _Na /I _CH3 ) of the ionic strength (I _Na ) of Na obtained by the method to the ionic strength (I _CH3 ) of CH ₃ is 0.2 or more. [2] The optical film of [1] above, wherein the polyimide resin and the polyimide resin are aromatic resins. [3] The optical film of [1] or [2] above, wherein the ratio of the structural unit derived from the aromatic monomer to all the structural units in the polyimide resin and the polyamide resin is 80 More than mol%. [4] The optical film of any one of [1] to [3] above, which has a thickness of 10 to 100 μm and a total light transmittance of 80% or more. [5] The optical film of any one of [1] to [4] above, wherein the weight average molecular weight of the polyimide resin and the polyimide resin is 200,000 or more. [6] The optical film according to any one of [1] to [5] above, wherein the polyimide resin is a polyimide resin. [7] The optical film according to any one of [1] to [6] above, wherein the polyimide-based resin and the polyimide-based resin contain a structural unit derived from terephthalic acid. [8] The optical film of any one of [1] to [7] above, which is a film for the front panel of a flexible display device. [9] A flexible display device including the optical film of any one of [1] to [8] above. [10] The flexible display device of [9] above, which further includes a touch sensor. [11] The flexible display device according to [9] or [10] above, which further includes a polarizing plate. [12] A resin composition containing at least one resin selected from the group consisting of polyimide resins and polyamide resins, selected from compounds containing sodium atoms, sodium and sodium ions At least one sodium-containing component in the group and a solvent. [Effects of Invention]

The optical film of the present invention has a higher elastic modulus.

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

The optical film of the present invention is an optical film containing at least one resin selected from the group consisting of polyimide resins and polyimide resins, and the optical film is analyzed by time-of-flight secondary ion mass spectrometry The ratio (I _Na /I _CH3 ) of the ionic strength (I _Na ) of Na obtained by the method (TOF-SIMS) to the ionic strength (I _CH3 ) of CH ₃ is 0.2 or more.

In the optical film of the present invention, the ratio (I _Na /I _CH3 ) of the ionic strength of _Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) is calculated as follows: Time-of-Flight Secondary Ion Mass Spectrometry (Time-of-Flight Secondary Ion Mass Spectrometry: hereinafter also referred to as "TOF-SIMS") measures the ionic strength of CH ₃ (I _CH3 ) and Na (I _Na ) of the optical film. Divide I _Na by I _CH3 . Furthermore, in this specification, the ionic strength of CH ₃ (I _CH3 ) and the ionic strength of _Na (I _Na ) measured by the time-of-flight secondary ion mass spectrometry method will be attributed to the measurement data the integral value of the peak of the ions as CH ₃ CH ₃ the ionic strength (I _CH3), attributable to the integral value of the peak of Na ions as ionic strength of Na (I _Na).

TOF-SIMS is a type of mass spectrometry method. According to TOF-SIMS, the elements or molecular species present on the outermost surface of the sample can be obtained with very high detection sensitivity, and the elements present on the outermost surface of the sample can also be measured. Or the distribution of molecular species.

TOF-SIMS is a method in which ion beams (primary ions) are irradiated to the sample in high vacuum, and the ions emitted from the surface are separated by the difference in flight time. If irradiated with primary ions, positively or negatively charged ions (secondary ions) will be emitted from the surface of the sample. The lighter the ion, the faster the flight, and the heavier the ion, the slower it will fly. Until the time (time of flight) is detected, the mass of the secondary ion produced can be calculated.

In the measurement by TOF-SIMS, CH ₃ ions were detected near mass 15.02 u, and Na ions were detected near mass 22.99 u. In addition, the plasma is an ion that can be detected in any of positive ion analysis and negative ion analysis. In the present invention, the ratio of the ionic strength of _Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) can be the ratio detected by positive ion analysis, or it can be analyzed by negative ion From the viewpoint of obtaining higher detection sensitivity, the detected ratio is preferably to use the condition of positive ion analysis. As long as at least one of the above ratios is 0.2 or more, the ratio of the present invention (I _Na /I _CH3 ) Is a necessary condition of 0.2 or more.

The TOF-SIMS measurement can use a time-of-flight secondary ion mass spectrometer for the optical film. The primary ion is Bi ^{3 + +} , the acceleration voltage of the primary ion is 25 kV, the irradiation ion current is 0.23 pA, and the measurement range is 200 Under the condition of μm×200 μm, it is carried out by positive ion analysis or negative ion analysis. The measurement by TOF-SIMS can be performed, for example, according to the method described in the Examples. As long as the ratio (I _Na /I _CH3 ) measured on at least a part of the surface or cross-section of the optical film is within the above range, it is assumed that the internal composition of the optical film is more likely to affect the mechanical strength of the optical film, so it is better to The above-mentioned ratio (I _Na /I _CH3 ) of the _cross- sectional measurement of the optical film is within the above-mentioned range.

According to the present invention, the ratio (I _Na /I _CH3 ) of the ionic strength of Na obtained by the time-of-flight secondary ion mass spectrometry (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) is 0.2 or more The optical film can unexpectedly increase the elastic modulus of the optical film. Here, the ionic strength of CH ₃ (I _CH3 ) and the ionic strength of _Na (I _Na ) obtained by the time-of-flight secondary ion mass spectrometry method relatively represent the carbon atoms and/or that are present in the optical film Or the amount of carbon ions and the amount of sodium atoms and/or sodium ions. The above ratio of 0.2 or more means that a certain amount or more of the total amount of sodium atoms (Na) and/or sodium ions is present relative to the total amount of carbon atoms and/or carbon ions present in the optical film. Furthermore, the reason why carbon atoms and carbon ions are detected as CH ₃ ions is as follows: In time-of-flight secondary ion mass spectrometry, there is a feature that various secondary ions produced are also detected in the form of protons. , The CH ₃ ion in the carbon atom is produced simultaneously as a proton.

The reason why the elastic modulus of the optical film can be increased by the presence of a certain amount of sodium atoms is not clear. For example, it is considered that the elastic modulus can be increased by the following mechanism, but the present invention is not limited by the following mechanism. It is considered that when the optical film of the present invention is produced, since the composition containing polyimide resin and/or polyimide resin contains a compound containing sodium atoms, sodium and/or sodium ions, the resin contained The amide bond and/or the amide bond, preferably the amide bond contained in the polyimide resin, and the compound containing sodium atoms, sodium and/or sodium ions have some interaction (such as , The electrostatic interaction between the carbonyl group of the amide bond or the amide bond and the sodium ion). It is considered that the result is that the polyimide-based resin and/or polyimide-based resin contained in the obtained optical film is present in the film in a state of interaction with the compound containing sodium atoms, sodium and/or sodium ions, or Due to the interaction of the compound containing sodium atoms, sodium and/or sodium ions with the polyimide resin and/or the polyimide resin, the alignment state of the resin is changed, thereby increasing the elastic modulus of the optical film. From the viewpoint of easy interaction with the polyimide resin and/or the amide bond and/or the amide bond of the polyimide resin, it is preferable that the sodium-containing component contained in the optical film is ionized The state. In addition, in this specification, it is considered that the sodium atom-containing compound that may be contained in the optical film detected as the ionic strength of _Na (I _Na ) when the optical film is subjected to time-of-flight secondary ion mass spectrometry, Sodium and/or sodium ions are also called "sodium-containing ingredients". Furthermore, the so-called compound containing sodium atom refers to a compound containing sodium atom as the constituent atom of the molecule.

The ratio (I _Na /I _CH3 ) of the ionic strength of _Na (I _Na ) to the ionic strength (I _CH3 ) of CH ₃ (I _Na /I _CH3 ) is preferably 1 or more from the viewpoint of easy improvement of the elastic modulus of the optical film It is more preferably 1.5 or more, still more preferably 3 or more, still more preferably 5 or more, still more preferably 10 or more, and particularly preferably 15 or more. The upper limit of the ratio (I _Na /I _CH3 ) is preferably 100 or less, more preferably 50 or less, still more preferably 30 or less, still more preferably 25 or less, and particularly preferably 20 or less.

The method of adjusting the ratio (I _Na /I _CH3 ) to the above-mentioned range is not particularly limited, and examples include: adjusting the sodium content in the optical film of the present invention containing polyimide resin and/or polyimide resin The method of the content of the components (compounds containing sodium atoms, sodium and/or sodium ions) and the method of adjusting the content of the polyimide-based resin and/or polyamide-based resin contained in the optical film. Specifically, if the content of sodium-containing components in the optical film is increased, the ionic strength (I _Na ) of Na obtained by TOF-SIMS of the optical film also increases. If the content of the polyimide resin and/or polyimide resin contained in the optical film is increased, the ionic strength (I _CH3 ) of the CH ₃ obtained by TOF-SIMS of the optical film also changes Big. Therefore, if the content of sodium-containing components in the optical film is increased, the value of the ratio (I _Na /I _CH3 ) becomes larger, and if the polyimide resin and/or polyamide resin contained in the optical film is increased The content of the resin decreases the value of the ratio (I _Na /I _CH3 ). By the above method, the ratio (I _Na /I _CH3 ) can be adjusted to the desired range.

In the optical film of the present invention, the ionic strength of CH ₃ (I _CH3 ) and the ionic strength of _Na (I _Na ) obtained by TOF-SIMS are not particularly limited, as long as the ratio (I _Na /I _CH3 ) is the value The above range is sufficient, and it is easy to ensure sufficient quantification by TOF-SIMS measurement. Preferably, the ionic strength of _Na (I _Na ) is preferably 100 or more, more preferably 300 or more, and more preferably Measure under the condition of 500 or more.

The optical film of the present invention having a ratio (I _Na /I _CH3 ) of 0.2 or more has a higher elastic modulus. The elastic modulus of the optical film of the present invention is preferably 5.0 MPa or more, more preferably 5.1 MPa or more, and still more preferably 5.2 MPa or more. The upper limit of the elastic modulus is not particularly limited, but is usually 100 MPa or less. Furthermore, the modulus of elasticity can be measured using a tensile testing machine (for example, the distance between the chucks is 50 mm, and the tensile speed is 10 mm/min). 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 is preferably 80% or more, more preferably 85% or more, still more preferably 88% or more, still more preferably 90% or more, and particularly preferably 91% or more. If the total light transmittance is more than the above lower limit, it is easy to improve visibility when the optical film is incorporated into an image display device as a front panel. 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 display elements necessary for obtaining 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 an image display device, there is a tendency to obtain a brighter display even if the amount of light of the backlight is reduced, which can help save energy. 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 can be the total light transmittance in the range of the thickness of the following optical film.

The haze of the optical film of the present invention is preferably 1% or less, more preferably 0.5% or less, and still more preferably 0.2% or less. 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 incorporated into an image display device as a front panel. In addition, the lower limit of the haze is usually 0.01% or more. In addition, the haze can be measured using a haze meter in accordance with JIS K 7136:2000.

The yellowness (YI value) of the optical film of the present invention is preferably 3.0 or less, more preferably 2.5 or less, and still more preferably 2.2 or less. If the yellowness of the optical film is less than the above upper limit, the transparency becomes good, and when used in the front panel of an image display device, it helps to obtain higher visibility. The yellowness is usually -5 or higher, preferably -2 or higher. Furthermore, the yellowness (YI value) can be measured by the ultraviolet-visible-near-infrared spectrophotometer for the transmittance of light from 300 to 800 nm, and the tristimulus values (X, Y, Z) can be calculated based on YI=100×( 1.2769X－1.0592Z)/Y. Furthermore, in this specification, the so-called excellent optical properties of the optical film means higher total light transmittance, lower haze and/or lower YI value (lower yellowness).

The thickness of the optical film of the present invention is preferably 10 μm or more, more preferably 20 μm or more, more preferably 25 μm or more, particularly preferably 30 μm or more, preferably 100 μm or less, more preferably 80 μm or less, More preferably, it is 60 μm or less, which may be a combination of the upper and lower limits. If the thickness of the optical film is within the above range, it is easy to further increase the elastic modulus of the optical film. Furthermore, the thickness of the optical film can be measured using a micrometer, for example, it 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. Furthermore, the number of bending in the bending resistance test means that the bending radius (radius of curvature) R of the optical film is repeatedly bent using a bending test machine under the condition of 1 mm, until the film is broken. The number of reciprocating bending (take 1 reciprocating as 1 time).

<Polyimide resin and polyimide resin> The optical film of the present invention contains polyimide resin and/or polyimide resin. In this specification, the so-called polyimide resin refers to a resin selected from the group consisting of a repeating structural unit containing an imine group (hereinafter, sometimes referred to as polyimide resin), and a resin containing an imine group and At least one resin in the group consisting of the resin of the two repeating structural units of the amide group (hereinafter, sometimes referred to as polyamide resin). That is, in this specification, the so-called polyimide-based resin means polyimide resin and/or polyimide resin. In addition, the so-called polyamide-based resin refers to a resin containing a repeating structural unit containing an amide group. The optical film of the present invention may contain one kind of polyimide resin or polyimide resin, or a combination of two or more polyimide resins and/or polyimide resins. For the optical film of the present invention, from the viewpoint that it is easy to balance the chemical stability of the optical film and the high elastic modulus, it is preferable to contain a polyimide resin, and it is more preferable that the polyimide resin is a polyimide resin. Amide imine resin.

In a preferred embodiment of the present invention, from the viewpoint that it is easy to further increase the elastic modulus of the optical film, the polyimide resin and the polyamide resin are preferably aromatic resins. In this specification, the so-called aromatic resin refers to polyimide resins and resins in which the structural units contained in polyimide resins are mainly aromatic structural units.

In the above-mentioned preferred embodiment, in terms of the ease of further improving the elastic modulus of the optical film, relative to all the structural units contained in the polyimide-based resin, the structural units are derived from aromatic monomers The ratio is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and particularly preferably 85 mol% or more. Here, the structural unit derived from an aromatic monomer refers to a monomer derived from a structure containing an aromatic system (for example, an aromatic ring) in at least a part, and a structure containing an aromatic system (for example, an aromatic The structural unit of ring). Examples of aromatic monomers include aromatic tetracarboxylic acid compounds, aromatic diamines, and aromatic dicarboxylic acids.

In a preferred embodiment of the present invention, the polyimide resin is preferably a polyimide resin having a structural unit represented by formula (1), or a structural unit and formula represented by formula (1) (2) Polyimide resin of the structural unit represented. In addition, the polyamide resin is preferably a polyamide resin having a structural unit represented by formula (2). The formula (1) and formula (2) are described below. The description of formula (1) is about both polyimide resin and polyimide resin, and the description of formula (2) is about polyimide resin. Both amide resin and polyamide resin. [化1]

The structural unit represented by formula (1) is a structural unit formed by the reaction of a tetracarboxylic acid compound and a diamine compound, and the structural unit represented by formula (2) is a structural unit formed by the reaction of a dicarboxylic acid compound and a diamine compound.

In formula (2), Z is a divalent organic group, preferably a divalent organic group with 4 to 40 carbons that can be substituted by a hydrocarbon group with 1 to 8 carbons or a hydrocarbon group with 1 to 8 carbons substituted with fluorine More preferably, it is a divalent organic group with a cyclic structure and a carbon number of 4-40 that can be substituted by a C1-C8 hydrocarbon group or a fluorine-substituted C1-C8 hydrocarbon group. The cyclic structure may, for example, be an alicyclic, aromatic, or heterocyclic structure. As the organic group of Z, the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), Among the bonding bonds of the groups represented by formula (28) and formula (29), two non-adjacent groups substituted with hydrogen atoms and a divalent chain hydrocarbon group with 6 or less carbon atoms can be exemplified as having a thiophene ring skeleton as The base of the heterocyclic structure of Z. From the viewpoint of easily suppressing the yellowness of the optical film (reducing the YI value), the group represented by formula (20) to formula (27) and a group having a thiophene ring skeleton are preferable.

[式(3)中， R¹ ～R⁸ 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，R¹ ～R⁸ 中所含之氫原子可相互獨立地被取代為鹵素原子， 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(R⁹ )-，R⁹ 表示氫原子、可經鹵素原子取代之碳數1～12之1價烴基， m為0～4之整數， *表示鍵結鍵]。In one embodiment of the present invention, the polyamide resin and the polyamide resin may contain a plurality of types of Z, and the plurality of types of Z may be the same or different from each other. In particular, from the viewpoint that it is easy to increase the elastic modulus of the optical film of the present invention and the optical characteristics, it is preferable that at least a part of Z is represented by the formula (3): [化2]

[In formula (3), R ¹ to R ⁸ independently represent a hydrogen 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, and R ¹ to The hydrogen atoms contained in R ⁸ can be independently substituted with halogen atoms, and A independently 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 ⁹ )-, R ⁹ represents a hydrogen atom, which can be halogenated The substituted monovalent hydrocarbon group with 1-12 carbons, m is an integer of 0-4, and * represents a bonding bond].

In formula (3), A independently 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 ⁹ )-, from the viewpoint of the bending resistance of the optical film, preferably represents -O- or- S-, more preferably represents -O-. R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ independently represent a hydrogen atom, an alkyl group with 1 to 6 carbons, an alkoxy group with 1 to 6 carbons, or carbon The number of aryl groups from 6 to 12. As the alkyl group having 1 to 6 carbon atoms, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, n-pentyl, 2-methyl Base-butyl, 3-methylbutyl, 2-ethyl-propyl, n-hexyl, etc. Examples of alkoxy groups having 1 to 6 carbon atoms include: methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, and pentoxy Group, hexyloxy, cyclohexyloxy, etc. As a C6-C12 aryl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a biphenyl group etc. are mentioned, for example. From the viewpoint of the surface hardness and flexibility of the optical film, R ¹ to R ⁸ are independent of each other, and 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, the hydrogen atoms contained in R ¹ to R ⁸ may be substituted with halogen atoms independently of each other. R ⁹ represents a hydrogen atom or a monovalent hydrocarbon group with 1 to 12 carbon atoms which may be substituted with a halogen atom. As the monovalent hydrocarbon group having 1 to 12 carbon atoms, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, second butyl, tertiary butyl, n-pentyl, 2- Methyl-butyl, 3-methylbutyl, 2-ethyl-propyl, n-hexyl, n-heptyl, n-octyl, tertiary octyl, n-nonyl, n-decyl, etc., which can be The halogen atom is substituted. As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned.

In formula (3), m is an integer in the range of 0-4. If m is within this range, it is easy to improve the elastic modulus and bending resistance of the optical film. From the viewpoint that it is easy to further improve the elastic modulus and bending resistance of the optical film, m in formula (3) is preferably an integer in the range of 0 to 3, more preferably an integer in the range of 0 to 2, and more Preferably, it is 0 or 1, particularly preferably 0. The structural unit represented by formula (3) where m is 0 is a structural unit derived from terephthalic acid, and the structural unit is particularly preferably a structure where R ⁵ to R ⁸ in formula (3) are hydrogen atoms and m is 0 unit. The resin may contain one or two or more structural units represented by formula (3) in Z. From the viewpoints of improving the elastic modulus and bending resistance of the optical film and reducing the yellowness (YI value), the resin preferably contains two or more structures with different values of m in formula (3) in Z The unit more preferably contains two structural units with different values of m in formula (3). In this case, from the viewpoint of easy improvement of the elastic modulus and bending resistance of the optical film, and the viewpoint of easy reduction of the yellowness (YI value) of the optical film, the resin is particularly preferably contained in Z with m being 0 The structural unit represented by the formula (3), in addition to the structural unit, further contains the structural unit represented by the formula (3) where m is 1.

於該情形時，易於提高光學膜之彈性模數及耐彎曲性，並且易於減低黃度。In a preferred embodiment of the present invention, the resin has a structural unit in which m=0 and R ⁵ to R ⁸ are hydrogen atoms as the structural unit represented by formula (3). In a more preferable embodiment of the present invention, the resin has a structural unit represented by formula (3) where m=0 and R ⁵ to R ⁸ are hydrogen atoms, and a structure represented by formula (3') Unit: [化3]

In this case, it is easy to improve the elastic modulus and bending resistance of the optical film, and it is easy to reduce the yellowness.

In a preferred embodiment of the present invention in which the optical film contains a polyamideimide resin, the structural unit represented by formula (1) and the structural unit represented by formula (2) of the polyamideimide resin When the total is set to 100 mol%, the ratio of the structural unit represented by formula (3) is preferably 20 mol% or more, more preferably 30 mol% or more, and still more preferably 40 mol% or more, especially It is preferably 50 mol% or more, most preferably 60 mol% or more, preferably 90 mol% or less, more preferably 85 mol% or less, and still more preferably 80 mol% or less. If the ratio of the structural unit represented by the formula (3) is more than the above lower limit, it is easy to improve the elastic modulus and bending resistance of the optical film. If the ratio of the structural unit represented by the formula (3) is below the above upper limit, the increase in the viscosity of the resin-containing varnish caused by the hydrogen bond between the amide bonds of the formula (3) is suppressed, and the processability of the film is easily improved .

In addition, when the polyamide imide resin has a structural unit represented by formula (3) with m=1 to 4, the structural unit and formula represented by formula (1) of the polyamide imide resin (2) When the total of the structural units represented is 100 mol%, the ratio of the structural units represented by formula (3) in which m is 1 to 4 is preferably 3 mol% or more, more preferably 5 mol% % Or more, more preferably 7 mol% or more, particularly preferably 9 mol% or more, preferably 90 mol% or less, more preferably 70 mol% or less, and still more preferably 50 mol% or less, More preferably, it is 30 mol% or less. If the ratio of the structural unit represented by the formula (3) in which m is 1 to 4 is more than the above lower limit, it is easy to improve the elastic modulus and the bending resistance of the optical film. If the ratio of the structural units represented by the formula (3) in which m is 1 to 4 is less than the above upper limit, the resin-containing content caused by the hydrogen bonding between the amide bonds of the structural units represented by the formula (3) is suppressed The increase in the viscosity of the varnish makes it easy to improve the processability of the film. In addition, the ratio of the structural unit represented by formula (1), formula (2) or formula (3) can be measured using ¹ H-NMR, for example, or it can also be calculated from the feed ratio of raw materials.

In a preferred embodiment of the present invention, Z in the polyamide resin or polyimide resin is preferably 30 mol% or more, more preferably 40 mol% or more, and still more preferably 45 mol% or more, more preferably 50 mol% or more is a structural unit represented by formula (3) where m is 0-4. If the above lower limit of Z is a structural unit represented by formula (3) in which m is 0 to 4, it is easy to improve the elastic modulus and bending resistance of the optical film. Moreover, 100 mol% or less of Z in the polyamide resin or polyamide resin may be a structural unit represented by formula (3) in which m is 0-4. In addition, the ratio of the structural unit represented by formula (3) in which m in the resin is 0 to 4 can be measured, for example, using ¹ H-NMR, or can be calculated from the feed ratio of the raw materials.

In a preferred embodiment of the present invention, Z in the polyamide resin or polyimide resin is preferably 5 mol% or more, more preferably 8 mol% or more, and still more preferably 10 mol% or more, and more preferably 12 mol% or more are expressed by the formula (3) where m is 1 to 4. When the above lower limit of Z of the polyimide resin is represented by the formula (3) where m is 1 to 4, it is easy to improve the elastic modulus and bending resistance of the optical film. In addition, Z is preferably 90 mol% or less, more preferably 70 mol% or less, still more preferably 50 mol% or less, and particularly preferably 30 mol% or less. It is a formula in which m is 1 to 4 ( 3) Represented. When the above upper limit of Z is represented by formula (3) where m is 1 to 4, the hydrogen bond between amide bonds derived from the structural unit represented by formula (3) where m is 1 to 4 is suppressed. The resulting increase in the viscosity of the resin-containing varnish is easy to improve the processability of the film. In addition, the ratio of structural units represented by formula (3) in which m in the resin is 1 to 4 can be measured, for example, using ¹ H-NMR, or can be calculated from the feed ratio of the raw materials.

In formula (1) and formula (2), X independently represents a divalent organic group, preferably represents a divalent organic group having 4 to 40 carbons, and more preferably represents 4 to 4 carbons with a cyclic structure 40 divalent organic base. The cyclic structure may, for example, be an alicyclic, aromatic, or heterocyclic structure. For the above-mentioned organic groups, the hydrogen atoms in the organic groups may be substituted with hydrocarbon groups or fluorine-substituted hydrocarbon groups. In this case, the carbon numbers of the hydrocarbon groups and fluorine-substituted hydrocarbon groups are preferably 1-8. In one embodiment of the present invention, the polyamide resin, polyimide resin, or polyimide resin may contain a plurality of types of X, and the plurality of types of X may be the same or different from each other. Examples of X include: formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17), and formula (18) The group represented by the formula (10) ~ formula (18) in which the hydrogen atom in the group represented by the formula (10) ~ formula (18) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain with a carbon number of 6 or less式hydrocarbyl.

[化4]

In formulas (10) to (18), * represents a bonding bond, V ¹ , V ² and V ³ independently represent a single bond, -O-, -S-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, -CO- or -N(Q)-. Here, Q represents a monovalent hydrocarbon group having 1 to 12 carbons which may be substituted with a halogen atom. As the monovalent hydrocarbon group having 1 to 12 carbon atoms, the group described above for R ⁹ may be mentioned. An example is: V ¹ and V ³ are single bonds, -O- or -S-, and V ² is -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -or -SO ₂ -. The bonding position of V ¹ and V ² to each ring and the bonding position of V ² and V ³ to each ring are independent of each other, and each ring is preferably meta or para, more preferably para.

Among the bases represented by formulas (10) to (18), from the viewpoint of easily improving the elastic modulus and bending resistance of the optical film, formulas (13), (14), and (15) are preferred , The group represented by formula (16) and formula (17) is more preferably the group represented by formula (14), formula (15) and formula (16). In addition, as V ¹ , V ² and V ³ , from the viewpoint of easy improvement of the elastic modulus and flexibility of the optical film, a single bond, -O- or -S- is preferable independently of each other, and a single bond is more preferable. Key or -O-.

[式(4)中， R¹⁰ ～R¹⁷ 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，R¹⁰ ～R¹⁷ 中所含之氫原子可相互獨立地被取代為鹵素原子， *表示鍵結鍵]。 若式(1)及式(2)中之複數個X之至少一部分為式(4)所表示之基，則易於提高光學膜之彈性模數及透明性。In a preferred embodiment of the present invention, at least a part of the plurality of X in formula (1) and formula (2) is the structural unit represented by formula (4): [化5]

[In formula (4), R ¹⁰ to R ¹⁷ 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 R ¹⁰ to The hydrogen atoms contained in R ¹⁷ can be substituted with halogen atoms independently of each other, and * represents a bonding bond]. If at least a part of the plural X in the formula (1) and formula (2) is the base represented by the formula (4), it is easy to improve the elastic modulus and transparency of the optical film.

In formula (4), R ¹⁰ , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 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, or aryl groups having 6 to 12 carbons include the alkyl groups having 1 to 6 carbons in formula (3), The alkoxy group of 1 to 6 or the aryl group of 6 to 12 carbons are exemplified. R ¹⁰ to R ¹⁷ independently of each other preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbons, and more preferably represent a hydrogen atom or an alkyl group having 1 to 3 carbons. Here, R ¹⁰ to R ¹⁷ are The hydrogen atoms contained can be independently substituted with halogen atoms. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example. From the viewpoints of the elastic modulus, transparency, and bending resistance of the optical film, R ¹⁰ to R ¹⁷ are independent of each other and are preferably a hydrogen atom, a methyl group, a fluorine group, a chlorine group, or a trifluoromethyl group, and more preferably R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are hydrogen atoms, R ¹¹ and R ¹⁷ are hydrogen atoms, methyl, fluoro, chloro or trifluoromethyl, and R ^{11 is} particularly preferred And R ¹⁷ is methyl or trifluoromethyl.

， 即，複數個X之至少一部分為式(4')所表示之結構單元。於該情形時，藉由含有氟元素之骨架而使聚醯亞胺系樹脂或聚醯胺系樹脂於溶劑中之溶解性提高，從而易於提高含有該樹脂之清漆之保管穩定性，並且易於減低該清漆之黏度，易於提高光學膜之加工性。又，藉由含有氟元素之骨架，易於提高光學膜之光學特性。In a preferred embodiment of the present invention, the structural unit represented by formula (4) is the structural unit represented by formula (4'): [化6]

, That is, at least a part of the plurality of Xs is a structural unit represented by formula (4'). In this case, the solubility of polyimide resin or polyimide resin in the solvent is improved by the skeleton containing fluorine element, so that the storage stability of the varnish containing the resin is easily improved, and the reduction is easy The viscosity of the varnish is easy to improve the processability of the optical film. In addition, the fluorine-containing skeleton makes it easy to improve the optical properties of the optical film.

In a preferred embodiment of the present invention, X in the polyimide resin or polyimide resin is preferably 30 mol% or more, more preferably 50 mol% or more, and still more preferably More than 70 mol% is represented by formula (4), especially formula (4'). When X in the above-mentioned range in the polyimide resin or polyimide resin is represented by formula (4), especially formula (4'), the resulting optical film is enhanced by the skeleton containing fluorine element The solubility of the resin to solvents makes it easy to improve the storage stability of the varnish containing the resin, and it is easy to reduce the viscosity of the varnish, and it is easy to improve the processability of the optical film. In addition, it is easy to improve the optical properties of the optical film by the skeleton containing the fluorine element. Furthermore, it is preferable that 100 mol% or less of X in the polyimide resin or polyimide resin is represented by formula (4), especially formula (4'). X in the above resin may be formula (4), especially formula (4'). The ratio of the structural unit represented by the formula (4) of X in the above resin can be measured, for example, using ¹ H-NMR, or can also be calculated from the feed ratio of the raw materials.

In the formula (1), Y represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbons, and more preferably a tetravalent organic group having 4 to 40 carbons having a cyclic structure. The cyclic structure may, for example, be an alicyclic ring, an aromatic ring, or a heterocyclic structure. From the viewpoint of easy improvement of the elastic modulus, an aromatic ring is preferably mentioned. The above-mentioned organic group is 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. 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, the polyimide-based resin may contain a plurality of types of Y, and the plurality of types of Y may be the same or different from each other. As Y, the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula ( 28) and the group represented by the formula (29); the hydrogen atom in the group represented by the formula (20) ~ formula (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; And tetravalent chain hydrocarbon group with carbon number 6 or less.

[化7]

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-O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C(CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents an aryl group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, and as a specific example, a phenyl group may be mentioned.

Among the bases represented by formulas (20) to (29), in terms of easy improvement of the elastic modulus and bending resistance of the optical film, formulas (26), (28) or (29) are preferred The group represented is more preferably the group represented by formula (26). In addition, as W ¹ , 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 yellowness of the light film, it is preferably a single bond, -O-, -CH ₂ -independently of each other. , -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(5)中， R¹⁸ ～R²⁵ 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，R¹⁸ ～R²⁵ 中所含之氫原子可相互獨立地被取代為鹵素原子， *表示鍵結鍵]。 若複數個式(1)中之Y之至少一部分為式(5)所表示之基，則聚醯亞胺系樹脂之對溶劑之溶解性提高，從而易於減低含有聚醯亞胺系樹脂之清漆之黏度，易於提高光學膜之加工性。又，易於提高光學膜之彈性模數及光學特性。In a preferred embodiment of the present invention, at least a part of Y in the plural formula (1) is a structural unit represented by formula (5): [化 8]

[In formula (5), R ¹⁸ to R ²⁵ 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 ¹⁸ to The hydrogen atoms contained in R ²⁵ can be substituted with halogen atoms independently of each other, and * represents a bonding bond]. If at least a part of Y in the formula (1) is the group represented by the formula (5), the solubility of the polyimide resin in solvents is improved, and it is easy to reduce the varnish containing the polyimide resin The viscosity is easy to improve the processability of the optical film. In addition, it is easy to improve the elastic modulus and optical properties of the optical film.

In formula (5), 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 6 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 6 carbons in formula (3), The alkoxy group having 1 to 6 or the aryl group having 6 to 12 carbons are those exemplified above. R ¹⁸ to R ²⁵ are independent of each other, and preferably represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, 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 with halogen atoms. As this halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned. R ¹⁸ to R ²⁵ are independent of each other. From the viewpoints of easy improvement of the elastic modulus and bending resistance of the optical film, and easy improvement of transparency and easy maintenance of the transparency, hydrogen atoms, methyl groups, A fluoro group, a chloro group, or a 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 groups, and fluoro groups , Chloro or trifluoromethyl, particularly preferably R ²¹ and R ²² are methyl or trifluoromethyl.

， 即複數個Y之至少一部分為式(5')所表示之結構單元。於該情形時，藉由含有氟元素之骨架，聚醯亞胺系樹脂之對溶劑之溶解性提高，從而易於提高含有該樹脂之清漆之保管穩定性，並且易於減低該清漆之黏度，易於提高光學膜之加工性。又，藉由含有氟元素之骨架，易於提高光學膜之光學特性。In a preferred embodiment of the present invention, the structural unit represented by formula (5) is the base represented by formula (5'): [化9]

, That is, at least a part of the plurality of Y is the structural unit represented by formula (5'). In this case, by containing the fluorine element skeleton, the solubility of the polyimide resin to the solvent is improved, so that the storage stability of the varnish containing the resin is easily improved, and the viscosity of the varnish is easily reduced, and the viscosity of the varnish is easily improved. Processability of optical film. In addition, the fluorine-containing skeleton makes it easy to improve the optical properties of the optical film.

In a preferred embodiment of the present invention, Y in the polyimide resin is preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more. The formula (5), especially the formula (5'). If Y in the above-mentioned range in the polyimide-based resin is represented by formula (5), especially formula (5'), the fluorine-containing skeleton will increase the solubility of the polyimide-based resin to solvents It is easy to reduce the viscosity of the varnish containing the resin, and it is easy to improve the processability of the optical film. In addition, the fluorine-containing skeleton makes it easy to improve the optical properties of the optical film. Furthermore, it is preferable that 100 mol% or less of Y in the polyimide resin is represented by formula (5), especially formula (5'). Y in the polyimide-based resin may be formula (5), especially formula (5'). The ratio of the structural unit represented by the formula (5) of Y in the polyimide resin can be measured, for example, using ¹ H-NMR, or can be calculated from the feed ratio of the raw materials.

In addition to the structural units represented by formula (1) and optionally formula (2), polyimide resins may also contain structural units represented by formula (30) and/or structural units represented by formula (31) . [化10]

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 with a hydrocarbon group or a fluorine-substituted hydrocarbon group. Examples of Y ^{1 include} : formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) ) And the group represented by the formula (29), wherein the hydrogen atom in the group represented by the formula (20) ~ formula (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and A tetravalent chain hydrocarbon group with 6 or less carbon atoms. In one embodiment of the present invention, the polyimide-based resin may contain a plurality of types of Y ¹ , and the plurality of types 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 with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As Y ² , the above-mentioned formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula ( 28) and any one of the bonding bonds of the group represented by the formula (29) is substituted with a hydrogen atom, and a trivalent chain hydrocarbon group with 6 or less carbon atoms. In one embodiment of the present invention, the polyimide-based resin may contain a plurality of types of Y ² , and the plurality of types 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 a hydrogen atom in the organic group can be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. Examples of X ¹ and X ² include the above-mentioned formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), and formula (17) And the group represented by the formula (18); the hydrogen atom in the group represented by the formula (10) to the formula (18) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and carbon Chain hydrocarbon group with number 6 or less.

In one embodiment of the present invention, the polyimide-based resin includes structural units represented by formula (1) and/or formula (2), and optionally represented by formula (30) and/or formula (31) The structural unit. In addition, from the viewpoint of easily improving the optical properties, elastic modulus, and bending resistance of the optical film, in the above-mentioned polyimide resin, the ratio of the structural units represented by the formulas (1) and (2) is Formula (1) and formula (2), and optionally formula (30) and formula (31) are based on all the structural units represented, preferably 80 mol% or more, more preferably 90 mol% or more, More preferably, it is 95 mol% or more. Furthermore, in the polyimide resin, the ratio of the structural units represented by formula (1) and formula (2) is based on formula (1) and formula (2), as well as formula (30) and/or as appropriate All the structural units represented by the formula (31) are on a basis, and it is 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 from the feed ratio of raw materials.

In one embodiment of the present invention, the content of the polyimide resin and/or polyimide resin in the optical film relative to 100 parts by mass of the optical film, preferably 10 parts by mass or more, more preferably 30 parts by mass Parts or more, more preferably 50 parts by mass or more, preferably 99.5 parts by mass or less, and more preferably 95 parts by mass or less. If the content of the polyimide resin and/or the polyimide resin is within the above range, it is easy to improve the optical properties and elastic modulus of the optical film.

Regarding the weight average molecular weight (Mw) of the polyimide-based resin or polyimide-based resin, in terms of the ease of improving the elastic modulus and bending resistance of the optical film, it is preferably calculated as standard polystyrene 200,000 or more, more preferably 230,000 or more, still more preferably 250,000 or more, still more preferably 270,000 or more, particularly preferably 300,000 or more. In addition, with regard to the weight average molecular weight of the polyimide resin and the polyimide resin, it is preferable from the viewpoints that the solubility of the resin to the solvent and the elongation and processability of the optical film are easily improved. It is 1,000,000 or less, more preferably 800,000 or less, still more preferably 700,000 or less, and particularly preferably 500,000 or less. The weight average molecular weight can be measured, for example, by GPC, and can be obtained by standard polystyrene conversion, and can be calculated, for example, by the method described in the examples.

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

In a preferred embodiment of the present invention, the polyimide-based resin and/or polyimide-based resin contained in the optical film may contain, for example, halogens such as fluorine atoms that can be introduced by the above-mentioned fluorine-containing substituents. atom. When the polyimide resin and/or the polyimide resin contains halogen atoms, it is easy to increase the elastic modulus of the optical film and reduce the yellowness (YI value). If the elastic modulus of the optical film is high, it is easy to suppress the damage and wrinkles of the film. Moreover, if the yellowness of the optical film is low, the transparency and visibility of the film can be easily improved. The halogen atom is preferably a fluorine atom. As a preferable fluorine-containing substituent for making the polyimide resin contain a fluorine atom, a fluorine group and a trifluoromethyl group can be mentioned, for example.

The content of the halogen atoms in the polyimide resin and the polyimide resin is based on the mass of the polyimide resin and the polyimide resin, respectively, and is preferably 1-40% by mass, more preferably 5 -40% by mass, more preferably 5-30% by mass. If the content of halogen atoms is more than the above lower limit, it is easy to further increase the elastic modulus of the optical film, reduce the water absorption rate, further reduce the yellowness, and further improve the transparency and visibility. If the content of halogen atoms is equal to or less than the above upper limit, synthesis becomes easy.

The polyimide resin and the polyimide resin have an imidization rate of 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 rate of imidization means that the molar amount of the amide bond in the polyimine resin is twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimine resin. Value ratio. Furthermore, when the polyimide-based resin contains a tricarboxylic acid compound, it means that the molar amount of the imine bond in the polyimide-based resin is relative to the molar amount of the polyimide-based resin. The ratio of the value of twice the molar amount of the structural unit of the carboxylic acid compound to the total molar amount of the structural unit derived from the tricarboxylic acid compound. In addition, the imidization rate can be obtained by IR (Infrared Spectroscopy) method, NMR (nuclear magnetic resonance, nuclear magnetic resonance) method, etc.

As the polyimide-based resin and the polyimide-based resin, commercially available products can be used. As a commercially available product of polyimide resin, for example, Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd., KPI-MX300F manufactured by Kawamura Sangyo Co., Ltd., etc. may be mentioned.

In the present invention, the optical film may contain polyamide-based resin. The polyamide resin of this embodiment is a polymer mainly composed of the repeating structural unit represented by formula (2). The preferred examples and specific examples of Z in the formula (2) in the polyimide-based resin are the same as the preferred examples and specific examples of Z in the polyimide-based resin. The polyamide resin may contain two or more repeating structural units represented by formula (2) with different Z.

[式(3'')中， R¹ ～R⁸ 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，R¹ ～R⁸ 中所含之氫原子可相互獨立地被取代為鹵素原子， A表示單鍵、-O-、-CH₂ -、-CH₂ -CH₂ -、-CH(CH₃ )-、-C(CH₃ )₂ -、-C(CF₃ )₂ -、-SO₂ -、-S-、-CO-或-N(R⁹ )-， R⁹ 表示氫原子、可經鹵素原子取代之碳數1～12之1價烴基， m為0～4之整數， R³¹ 及R³² 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](Method for producing resin) Polyimide resin can be produced by using, for example, tetracarboxylic acid compounds and diamine compounds as main raw materials, and polyimide resin can be produced by using, for example, tetracarboxylic acid compounds, dicarboxylic acid compounds, and diamine compounds. The compound is produced as a main raw material, and the polyamide resin can be produced using, for example, a dicarboxylic acid compound and a diamine compound as the main raw material. Here, the dicarboxylic acid compound preferably contains at least the compound represented by formula (3''). [化11]

[In formula (3''), R ¹ to R ⁸ independently represent a hydrogen 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, R The hydrogen atoms contained in ¹ to R ⁸ can be independently substituted with 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 ⁹ )-, R ⁹ represents a hydrogen atom, which can be substituted by a halogen atom The monovalent hydrocarbon group with 1-12 carbon atoms, m is an integer of 0-4, R ³¹ and R ³² independently represent hydroxyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butyl Oxy, second butoxy, tertiary butoxy or chlorine atom]

In a preferred embodiment of the present invention, the dicarboxylic acid compound is a compound represented by formula (3") in which m is 0. More preferably, in addition to the compound represented by formula (3'') in which m is 0, a compound represented by formula (3'') in which A is an oxygen atom is also used as the dicarboxylic acid compound. Furthermore, in another preferred embodiment, the dicarboxylic acid compound is a compound represented by formula (3'') in which R ³¹ and R ³² are chlorine atoms. In addition, a diisocyanate compound may be used instead of the diamine compound.

As the diamine compound used in the production of the resin, for example, aliphatic diamine, aromatic diamine, and mixtures thereof can be mentioned. Furthermore, in this embodiment, the term "aromatic diamine" refers to a diamine in which an amine group is directly bonded to an aromatic ring, and it may contain an aliphatic group or other substituents in a part of its structure. The aromatic ring may be a monocyclic ring or a condensed ring. Examples of the aromatic ring 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. The so-called "aliphatic diamine" refers to a diamine in which an amine group is directly bonded to an aliphatic group, which may contain an aromatic ring or other substituents in a part of its structure.

As aliphatic diamines, for example, acyclic aliphatic diamines such as hexamethylene diamine, 1,3-bis(aminomethyl)cyclohexane, and 1,4-bis(aminomethyl) Cyclic aliphatic diamines such as cyclohexane, noralkylene diamine and 4,4'-diaminodicyclohexylmethane, etc. These can be used alone or in combination of two or more.

As the aromatic diamine, for example, 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'-diaminodiphenylpropane, 4,4' -Diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'- Diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 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 referred to as TFMB), 4,4'-bis(4-aminophenoxy)biphenyl, 9,9-bis(4 -Aminophenyl) pyrene, 9,9-bis(4-amino-3-methylphenyl) pyrene, 9,9-bis(4-amino-3-chlorophenyl) pyrene, 9,9 -Aromatic diamines with two or more aromatic rings, such as bis(4-amino-3-fluorophenyl) pyridium. These can be used alone or in combination of two or more.

The aromatic diamine is preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,3'- Diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 1,4-bis(4-aminophenoxy)benzene, double [4-(4-Aminophenoxy)phenyl] ash, bis[4-(3-aminophenoxy)phenyl] ash, 2,2-bis[4-(4-aminophenoxy) Yl)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethane) )-4,4'-diaminobiphenyl (TFMB), 4,4'-bis(4-aminophenoxy)biphenyl, more preferably 4,4'-diaminodiphenylmethane , 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylene, 1,4-bis(4-aminobenzene Oxy)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 alone or in combination of two or more.

Among the above-mentioned diamine compounds, from the viewpoints of high elastic modulus, 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, use selected from 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'-Diaminodiphenyl ether is composed of more than one type, 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 also be a tetracarboxylic acid compound related product 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. Carboxylic dianhydride. As the non-condensed polycyclic aromatic tetracarboxylic dianhydride, for example, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid 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'-(hexafluoroiso Propyl)diphthalic dianhydride (sometimes referred to as 6FDA), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyl) Phenyl)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'-(m-phenylenedioxy) diphthalic dianhydride. Moreover, as the monocyclic aromatic tetracarboxylic dianhydride, for example, 1,2,4,5-benzenetetracarboxylic dianhydride can be exemplified, and as the condensed polycyclic aromatic tetracarboxylic dianhydride, for example For example: 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'-(m-phenylenedioxy) ) Diphthalic 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 dianhydride and 4,4'-(p-phenylenedioxy) diphthalic dianhydride. These can be used alone or in combination of two or more.

The aliphatic tetracarboxylic dianhydride may, for example, be a cyclic or acyclic aliphatic tetracarboxylic dianhydride. The so-called cyclic aliphatic tetracarboxylic dianhydride refers to tetracarboxylic dianhydride having an alicyclic hydrocarbon structure. As a specific example, 1,2,4,5-cyclohexane tetracarboxylic dianhydride can be mentioned , 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride and other cycloalkane tetracarboxylic dianhydrides, bicyclo[2.2.2]octane -7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride and their positional isomers. These can be used alone or in combination of two or more. Specific examples of acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butane tetracarboxylic dianhydride and 1,2,3,4-pentane tetracarboxylic dianhydride These can be used alone or in combination of two or more. In addition, cycloaliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride can be used in combination.

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'-oxydiphthalate is preferred Formic 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) .

As the dicarboxylic acid compound used in the production of the resin, terephthalic acid, 4,4'-oxybisbenzoic acid, or these chlorinated compounds can be preferably used. In addition to terephthalic acid or 4,4'-oxybisbenzoic acid or these chlorine compounds, other dicarboxylic acid compounds can also be used. Examples of other dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and related chlorinated compounds, acid anhydrides, etc., and two or more of them can be used in combination. Specific examples include: isophthalic acid; naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; two of chain hydrocarbons with carbon number 8 or less A compound composed of a carboxylic acid compound and two benzoic acids connected by a single bond, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or phenylene, and These chlorinated compounds. As specific examples, 4,4'-oxybis(benzyl chloride) and terephthalate chloride are preferred, and 4,4'-oxybis(benzyl chloride) is more preferably used in combination with Terephthalic acid chloride.

Furthermore, the above-mentioned polyimide-based resin may be in a range that does not impair the various physical properties of the optical film. In addition to the above-mentioned tetracarboxylic acid compound, tetracarboxylic acid, tricarboxylic acid, and these acid anhydrides and derivatives Those who respond.

The tetracarboxylic acid may, for example, be a water adduct of the acid anhydride of the above-mentioned tetracarboxylic acid compound.

Examples of tricarboxylic acid compounds include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and related chlorinated compounds, acid anhydrides, etc., and two or more of them can be used in combination. As a specific example, anhydrides of 1,2,4-benzenetricarboxylic acid; 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 desired ratio of each structural unit of the polyimide resin.

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 20 to 200°C, and more preferably 25 to 100°C. The reaction time is also not particularly limited, and is, for example, about 30 minutes to 10 hours. If necessary, the reaction can be carried out in an inert environment or under reduced pressure. In a preferred aspect, the reaction is carried out under normal pressure and/or an inert gas environment while stirring. Furthermore, the reaction is preferably carried out in a solvent inert to the reaction. The solvent is not particularly limited as long as it does not affect the reaction. For example, water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1- Alcohol solvents such as methoxy-2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, γ- Ester solvents such as valerolactone, propylene glycol methyl ether acetate and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone ; Aliphatic hydrocarbon solvents such as pentane, hexane and heptane; alicyclic hydrocarbon solvents such as ethyl cyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; tetrahydrofuran and dimethoxyethane Ether solvents such as alkane; chlorine-containing solvents such as chloroform and chlorobenzene; amine-based solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; dimethyl sulfide, dimethyl Sulfur-containing solvents such as 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, it is preferable to use an amide-based solvent.

In the imidization step in the production of polyimide resins, imidization can be performed in the presence of an imidization catalyst. As the imidization catalyst, for example, aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; N-ethylpiperidine, N-propylpiperidine, and N-butylpyrrole Alicyclic amines such as pyridine, N-butylpiperidine and N-propyl hexahydroazepine (monocyclic); azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, Alicyclic amines (polycyclic) such as azabicyclo[2.2.2]octane and azabicyclo[3.2.2]nonane; and pyridine, 2-picoline, 3-methyl Pyridine (3-picoline), 4-picoline (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2,4-lutidine, 2,4,6 -Aromatic amines such as trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline and isoquinoline. In addition, from the viewpoint of facilitating the promotion of the imidization reaction, it is preferable to use an acid anhydride together with the imidization catalyst. The acid anhydrides can be exemplified by commonly used acid anhydrides used in the imidization reaction. Specific examples include aliphatic anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatic anhydrides such as phthalic acid. .

Polyimide resins and polyimide 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 (Separation and purification). In a preferred aspect, a large amount of methanol and other alcohols are added to the reaction solution containing the transparent polyimide resin to precipitate the resin, which is then concentrated, filtered, dried, etc. from.

<Sodium-containing component> The optical film of the present invention contains a sodium-containing component selected from the group consisting of sodium atom-containing compounds, sodium, and sodium ions. The content of the sodium-containing component in the optical film of the present invention only needs to be the ratio of the ionic strength of Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) obtained by time-of-flight secondary ion mass spectrometry (I _{The amount of Na} /I _CH3 ) is 0.2 or more, and there is no particular limitation, as long as it is set so that the above ratio (I _Na /I _CH3 ) becomes a specific range according to the type of polyimide resin contained in the optical film OK. For example, as the content of the sodium-containing component in the varnish used to make the optical film of the present invention, from the viewpoint of easily improving the elastic modulus of the optical film, it is relative to the polyimide-based resin and/ Or the total amount of polyamide resin is preferably 0.002% by mass or more, more preferably 0.004% by mass or more, still more preferably 0.01% by mass or more, still more preferably 0.02% by mass or more, and still more preferably 0.03% by mass % Or more, particularly preferably 0.04% by mass or more. As the upper limit of the content of the sodium-containing component in the varnish used to make the optical film of the present invention, from the viewpoint of easily obtaining a homogeneous film, it is relative to the polyimide resin and/or polyamide contained in the varnish. The total amount of the amine resin is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less. In addition, the content of the sodium-containing component in the optical film of the present invention is relative to the polyimide-based resin and/or polyamide contained in the optical film from the viewpoint that it is easy to increase the elastic modulus of the optical film. The total amount of the resin is preferably 0.002% by mass or more, more preferably 0.004% by mass or more, still more preferably 0.01% by mass or more, still more preferably 0.02% by mass or more, and still more preferably 0.03% by mass or more, especially Preferably, it is 0.04% by mass or more. As the upper limit of the content of the sodium-containing component in the optical film of the present invention, from the viewpoint of easily obtaining a homogeneous film, it is relative to the polyimide resin and/or polyimide resin contained in the optical film. The total amount is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less. The content of sodium-containing components relative to the total amount of polyimide resin and/or polyimide resin contained in the optical film can be measured by spectroscopy methods such as infrared absorption spectroscopy. Optical films can also be manufactured The content in the varnish used at the time is regarded as the content in the optical film. Furthermore, when a compound containing sodium atoms is used as a sodium-containing component, the compound can be decomposed in the process of manufacturing an optical film within the range that does not impair the effects of the present invention.

The type of the compound containing sodium atom is not particularly limited. When using a resin composition containing at least a polyimide resin and/or a polyimide resin and a solvent (also called "varnish") to produce an optical film, it is easy to dissolve the component in the solvent of the varnish. From the viewpoint of easy inclusion of this component in the optical film, the compound containing a sodium atom is preferably an organic sodium salt. The organic sodium salt may, for example, be sodium alkoxide having 1 to 6 carbon atoms. Furthermore, the above-mentioned sodium atom-containing compound added to the resin composition does not need to be contained in the optical film of the present invention without maintaining the form of an organic sodium salt. For example, it can be combined with water or alcohol that can be contained in the resin composition. Hydrolysis of other salts, ion exchange reaction with other salts, etc., form other salts in the final optical film, which can also be contained as sodium or sodium ions.

＜Additives＞ The optical film of the present invention may contain fillers. As the filler, for example, organic particles, inorganic particles, etc. may be mentioned, preferably, inorganic particles may be mentioned. Examples of inorganic particles include metal oxide particles such as silicon oxide, zirconium oxide, aluminum oxide, titanium oxide, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide. , Magnesium fluoride, sodium fluoride and other metal fluoride particles. From the viewpoint that it is easy to improve the elastic modulus of the optical film and the impact resistance of the optical film, the filler is preferably silica particles, zirconia particles, or alumina particles, more preferably, silica particles. These fillers can be used alone or in combination of two or more.

The filler is preferably silica particles with an average primary particle size of 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, particularly preferably 20 nm or more, more 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, still more preferably 50 nm or less, and particularly preferably 40 nm or less. If the average primary particle size of the silicon oxide particles is within the above range, the aggregation of the silicon oxide 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 determined by the BET (Brunauer-Emmett-Teller, Buert) method. Furthermore, the primary particle size (average primary particle size) can be measured by image analysis of a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

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 5 parts by mass 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 more 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. Moreover, if the content of the filler is less than or equal to the above upper limit, it is easy to improve the optical properties of the optical film.

The optical film of the present invention may further contain an 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 contain a compound that absorbs light with a wavelength below 400 nm. As the ultraviolet absorber, for example, at least one compound selected from the group consisting of a benzophenone compound, a salicylate compound, a benzotriazole compound, and a triazole compound. The ultraviolet absorber can be used alone or in combination of two or more. By containing the ultraviolet absorber in the optical film, the deterioration of the resin can be suppressed, and therefore the visibility can be improved when the obtained optical film is applied to an image display device or the like. In this specification, the "system compound" refers to a derivative of the compound with the "system compound" attached. For example, the "benzophenone-based compound" refers to a compound having benzophenone as a parent skeleton and a substituent bonded to the benzophenone.

When the optical film contains an ultraviolet absorber, the content of the ultraviolet absorber relative to 100 parts by mass of the optical film is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more , Preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 6 parts by mass or less. The preferred content varies according to the ultraviolet absorber used. If the content of the ultraviolet absorber is adjusted so that the light transmittance of 400 nm becomes about 20-60%, the light resistance of the optical film can be improved and it is easy to improve Transparency.

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, flame retardants, pH adjusters, silica dispersants, lubricants, thickeners, and levelers. When other additives are contained, the content thereof is preferably 0.001 to 20 parts by mass relative to 100 parts by mass of the optical film, more preferably 0.01 to 15 parts by mass, and still more preferably 0.1 to 10 parts 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) Prepare a resin composition containing at least one resin selected from the group consisting of the above-mentioned polyimide-based resin and polyamide-based resin, a compound containing sodium atoms, sodium and/or sodium ions, and a solvent (Hereinafter also referred to as "varnish") steps (varnish preparation steps), (b) the step of applying varnish to the support 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). The present invention also provides a resin composition suitable for manufacturing the optical film of the present invention. The resin composition contains at least one resin selected from the group consisting of polyimide resins and polyimide resins. At least one sodium-containing component from the group consisting of sodium atom-containing compound, sodium and sodium ion, and solvent.

In the varnish preparation step, the polyimide resin and/or the polyimide resin and the sodium-containing component are dissolved in a solvent, and additives such as the filler and the ultraviolet absorber are added as necessary and stirred and mixed to prepare the varnish. Furthermore, in the case of using silica particles as a filler, add a dispersion of silica sol containing silica particles to the resin with a solvent that can dissolve the above resin, such as the solvent used in the preparation of the varnish as follows Of silica sol.

The sodium-containing component is not particularly limited as long as it is a component that can contain at least one selected from the group consisting of sodium atom-containing compounds, sodium, and sodium ions in the optical film of the present invention, and it is easy to dissolve the component From the viewpoint that the solvent of the varnish is easy to contain the component in the optical film, a compound containing a sodium atom is preferred, and an organic sodium salt is more preferred. The organic sodium salt may, for example, be sodium alkoxide having 1 to 6 carbon atoms. The sodium-containing component contained in the varnish may be one component or a combination of two or more components.

As the content of the sodium-containing component contained in the resin composition, from the viewpoint of easily improving the elastic modulus of the optical film, it is relative to the polyimide resin and/or polyimide resin contained in the resin composition. The total amount of resin is preferably 0.002 mass% or more, more preferably 0.004 mass% or more, still more preferably 0.01 mass% or more, still more preferably 0.02 mass% or more, particularly preferably 0.03 mass% or more, particularly preferred It is 0.04% by mass or more. As the upper limit of the content of the sodium-containing component in the resin composition of the present invention, from the viewpoint of the adjustability of the varnish viscosity and the film-forming properties, it is relative to the polyimide-based resin and/or the resin composition contained in the resin composition. The total amount of the polyamide resin is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less. When the content of the sodium-containing component is below the above upper limit, the viscosity of the varnish will not be too high, and the resin solid content in the varnish is easily increased, so it is easy to improve the film-forming properties.

The solvent used in the preparation of the varnish is not particularly limited as long as it can dissolve the above-mentioned resin. As the solvent, for example, amide solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; γ-butyrolactone (GBL), γ-valerolactone Lactone-based 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. Furthermore, water, alcohol solvents, ketone solvents, acyclic ester solvents, ether solvents, etc. may 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 can be applied to the support 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, gravure coating, die nozzle coating method, chipped wheel coating method, die lip coating method, Spin coating method, screen coating method, spray coating method, dipping method, spray method, casting method, etc.

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

As an example of the support material, if it is a metal system, it can be SUS (Steel Use Stainless) plate, if it is a resin system, it can be a PET (polyethylene terephthalate, polyethylene terephthalate). Film, PEN (polyethylene naphthalate, polyethylene naphthalate) film, polyamide resin film, other polyimide resin film, cycloolefin 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 layered on at least one area 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. When the optical film has the functional layer, it is preferable to perform the TOF-SIMS measurement on the cross section of the optical film.

The ultraviolet absorbing layer is a layer that has the function of absorbing ultraviolet rays, such as a main material selected from the group consisting of ultraviolet curable transparent resin, electron beam curable transparent resin, and thermosetting transparent resin, and ultraviolet rays dispersed in the main material Absorbent.

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, the resin composition can be cured by polymerizing the resin composition by supplying energy afterwards.

The adhesive layer may be a layer called Pressure Sensitive Adhesive (PSA) that adheres 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 bonded with a lighter pressure" (JIS K 6800), or can be used as "a specific component contained in the protective film" (Microcapsules), an adhesive that can maintain stability until the film is broken by an appropriate method (pressure, heat, etc.)" (JIS K 6800) capsule type adhesive.

The hue adjustment layer is a layer with the function of hue adjustment, and is a layer that can adjust the layered body containing the optical film to the target hue. The hue adjusting layer is, for example, a layer containing resin and coloring agent. As the colorant, for example, inorganic pigments such as titanium oxide, zinc oxide, red lead, titanyl calcined pigments, ultramarine blue, cobalt aluminate, and carbon black; azo compounds, quinacridone compounds, anthracene Organic pigments such as quinone compounds, perylene compounds, isoindolinone compounds, phthalocyanine compounds, quinophthalone compounds, threne compounds, and diketopyrrolopyrrole compounds; barium sulfate and carbonic acid Extender pigments such as calcium; 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, a layer that has a refractive index different from that of an optical film and 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 resin and pigments as appropriate, or a metal film. Examples of pigments for adjusting 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, thereby preventing the decrease in transparency. As the metal used in the refractive index adjustment layer, for example, titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, nitrogen Metal oxide or metal nitride such as silicide.

The optical film of the present invention may be a single layer or a laminate. For example, the optical film manufactured as described above may be used as it is, or it may be used as a laminate with other films. The optical film of the present invention with the ratio (I _Na /I _CH3 ) of the ionic strength of Na obtained by time-of-flight secondary ion mass spectrometry (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) of 0.2 or more The elastic modulus is excellent, so it has impact resistance and is useful as an optical film in image display devices.

In a preferred embodiment of the present invention, the optical film of the present invention is useful as a front panel of an image display device, especially a front panel (window film) of a flexible display device. The flexible display device has, for example, a flexible functional layer and an optical film superimposed on the flexible functional layer and functioning 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 image display devices include televisions, smart phones, mobile phones, car navigation, tablet PCs (personal computers), portable game consoles, electronic paper, indicators, bulletin boards, watches , And wearable devices such as smart watches. As the flexible display device, all image display devices having flexibility can be cited.

[Flexible display device] The invention also provides a flexible display device equipped with the optical film of the invention. The flexible display device includes a laminate for a flexible display device and an organic EL display panel. The laminate for a flexible display device is arranged on the viewing side of the organic EL display panel and is configured to be flexible. The laminate for a flexible display device may contain the optical film (window film) of the present invention, a circular polarizer, and a touch sensor. The order of these layers is in any order. Circular polarizing plate, touch sensor or window film, touch sensor, circular polarizing plate are laminated in sequence. If there is a circular polarizer on the viewing side of the touch sensor, it is difficult to see the pattern of the touch sensor, and the visibility of the displayed image becomes better, 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 layer of the window film, the circular polarizer, and the touch sensor.

[Window film] The window film is arranged on the visual recognition side of the flexible image display device, and is responsible for protecting other components from external impact or environmental changes such as temperature and humidity. Previously, glass was used as such a protective layer, but the window film in the flexible image display device is not as rigid and hard as glass, but has the characteristics of flexibility. As the window film, the optical film of the present invention can be used, which includes a flexible transparent substrate like the film, and can include a hard coat layer on at least one surface.

(Transparent substrate) The transmittance of the visible light range of the transparent substrate is usually 70% or more, preferably 80% or more. As the transparent substrate, it is preferable to use an optical film containing the polyimide resin and/or polyimide resin of the present invention. In the optical film of the present invention, inorganic particles such as silicon oxide, organic fine particles, rubber particles, etc. can be dispersed. Furthermore, it may contain coloring agents such as pigments or dyes, fluorescent whitening agents, dispersants, plasticizers, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents, antioxidants, and lubricants. , Solvents and other blending agents. The thickness of the above-mentioned transparent substrate is usually 5 to 200 μm, preferably 20 to 100 μm.

(Hard coating) A hard coat layer can be provided on at least one surface of the transparent substrate of the above-mentioned window film. 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 above-mentioned hard coat layer is in the above-mentioned range, sufficient scratch resistance can be ensured, while the bending resistance is unlikely to decrease, and the problem of curling due to hardening shrinkage is unlikely to occur. The above-mentioned hard coat layer can be formed by curing a hard coat composition containing a reactive material capable of forming a cross-linked structure by active energy ray irradiation or application of thermal energy, and is preferably formed by active energy ray irradiation. 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. Preferably, ultraviolet rays can be cited. 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. As the radical polymerizable group possessed by the above radical polymerizable compound, as long as it is a functional group capable of generating a radical polymerization reaction, a group containing a carbon-carbon unsaturated double bond can be mentioned, specifically: Vinyl, (meth)acryloyl, etc. In addition, when the above-mentioned radically polymerizable compound has two or more radically polymerizable groups, the radically polymerizable groups may be the same or different. As the number of radically polymerizable groups which the said radically polymerizable compound has in 1 molecule, the point which improves the hardness of a hard-coat layer is 2 or more. As the above-mentioned radically polymerizable compound, in terms of high reactivity, a compound having a (meth)acryloyl group is preferably exemplified, and specific examples include: having 2 to 6 (formaldehyde) in one molecule (Base) acryl-based compound called multifunctional acrylate monomer or epoxy (meth)acrylate, (meth)acrylate urethane, polyester (meth)acrylate An oligomer having several (meth)acrylic acid groups with a molecular weight of several hundred to several thousand in the molecule, preferably selected from epoxy (meth)acrylate, (meth)acrylic urethane One or more of acid ester and polyester (meth)acrylate.

The above-mentioned cationically polymerizable compound is a compound having a cationically polymerizable group such as an epoxy group, an oxycyclobutyl group, and a vinyl ether group. The number of cationically polymerizable groups contained in one molecule of the above-mentioned cationically polymerizable compound is preferably 2 or more, and more preferably 3 or more in terms of increasing the hardness of the hard coat layer. Furthermore, as the above-mentioned cationically polymerizable compound, a compound having at least one of an epoxy group and an oxycyclobutyl group as the cationically polymerizable group is preferred. In terms of small shrinkage accompanying the polymerization reaction, cyclic ether groups such as epoxy groups and oxycyclobutyl groups are preferred. In addition, the compound having an epoxy group in the cyclic ether group has the advantage of being easy to obtain a compound of various structures, without adversely affecting the durability of the obtained hard coat layer, and the compatibility with the radical polymerizable compound is also easy to control. In addition, in the cyclic ether group, the oxycyclobutyl group has a higher degree of polymerization than an epoxy group, and is low in toxicity. It accelerates the formation speed of the network structure obtained from the cation polymerizable compound of the obtained hard coat layer. The region mixed with the radical polymerizable compound will not leave unreacted monomers in the film, forming an independent network structure. As a cationic polymerizable compound having an epoxy group, for example, polyglycidyl ether of a polyhydric alcohol having an alicyclic ring, or a compound containing a cyclohexene ring and a cyclopentene ring with hydrogen peroxide The alicyclic epoxy resin obtained by epoxidizing suitable oxidizing agents such as peracid; polyglycidyl ether of aliphatic polyol or its alkylene oxide adduct, polyglycidyl ester of aliphatic long-chain polyacid, ( 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 novolac epoxy resins, that is, glycidyl ether type epoxy resins derived from bisphenols.

The above-mentioned hard coat composition may further contain a polymerization initiator. The polymerization initiator may, for example, be a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, etc., which are appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate free radicals or cations, thereby performing radical polymerization and cationic polymerization. The radical polymerization initiator may release a substance that initiates radical polymerization by at least one of active energy ray irradiation and heating. For example, as a thermal radical polymerization initiator, organic peroxides, such as hydrogen peroxide and perbenzoic acid, and azo compounds, such as azobisbutyronitrile, etc. are mentioned. As active energy ray radical polymerization initiators, there are Type1 radical polymerization initiators that generate free radicals by the decomposition of molecules, and those that coexist with tertiary amines and generate free radicals by hydrogen abstraction reaction. Type 2 radical polymerization initiator, which can be used alone or in combination. The cationic polymerization initiator may release a substance that initiates cationic polymerization by at least any one of active energy ray irradiation and heating. As the cationic polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron (II) complex, and the like can be used. Depending on the structure, the cationic polymerization can be started by either irradiation with active energy rays or heating, or both can start cationic polymerization by irradiation with active energy rays or heating.

The polymerization initiator may preferably contain 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 in the above range, there is a tendency that curing can be carried out sufficiently, and the mechanical properties or adhesion of the finally obtained coating film can be in a good range, and adhesion caused by curing shrinkage is unlikely to occur. Poor force or cracking phenomenon and curling phenomenon.

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

[Polarizer] The flexible display device provided with the optical film of the present invention may further be provided with a polarizing plate. The circular polarizing plate is a functional layer that has the function of transmitting only the right-handed or left-handed circularly polarized light component by laminating a λ/4 retardation plate on the linear polarizing plate. For example, it is used for the following purposes: converting external light into right-handed circularly polarized light, blocking the outer boundary light of left-handed circularly polarized light reflected by the organic EL panel, and transmitting only the light-emitting components of the organic EL, thereby suppressing reflection The effect of light makes it easy to view the image. In order to achieve the circularly polarized light function, the absorption axis of the linear polarizer and the retardation axis of the λ/4 retardation plate must be 45 degrees in theory, and 45±10 degrees in practice. The linear polarizing plate and the λ/4 retardation plate do not necessarily have to be laminated adjacent to each other, and the relationship between the absorption axis and the slow axis only needs to satisfy the above range. It is preferable to achieve complete circularly polarized light in all wavelengths, but this is not necessary in practice. Therefore, the circular polarizing plate of the present invention also includes an elliptical polarizing plate. It is also preferable to laminate a λ/4 retardation film on the visibility side of the linear polarizer to make the emitted light circularly polarized light, 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 composition of a linear polarizing element alone or a composition 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 in the above-mentioned range, there is a tendency that flexibility is unlikely to decrease. The linear polarizing element may be a film-type polarizing element manufactured by dyeing and stretching a polyvinyl alcohol (PVA)-based film. Dichroic pigments such as iodine are adsorbed on the PVA-based film aligned by stretching, or stretched while the dichroic pigments are adsorbed in the PVA, thereby aligning the dichroic pigments and exhibiting polarization performance. In the manufacture of the above-mentioned film-type polarizing element, there may be additional steps such as swelling, cross-linking with boric acid, washing with aqueous solution, and drying. The stretching or dyeing step can be performed alone with a PVA-based film, or 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, a liquid crystal coating type polarizing element formed by coating a liquid crystal polarizing composition may be used. The liquid crystal polarizing composition may contain 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 especially if it has an alignment state of the same order as the smectic sequence, it can exhibit higher polarization performance, so it is preferable. In addition, it is also preferable when the liquid crystal compound has a polymerizable functional group.

The dichroic dye compound is a dye that is aligned with the liquid crystal compound and exhibits 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 contain 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 made thinner than 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 manufactured by, for example, 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 aforementioned alignment film forming composition may also contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. Examples of the above-mentioned alignment agent include polyvinyl alcohols, polyacrylates, polyamic acids, and polyimines. 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 above-mentioned alignment agent can be, for example, about 10,000 to 1,000,000. The thickness of the above-mentioned alignment film is preferably 5 to 10,000 nm, more preferably 10 to 500 nm from the viewpoint of the alignment restriction force. The liquid crystal polarizing layer may be peeled from the base material and transferred to be laminated, or the base material may be directly laminated. It is also preferable when the above-mentioned base material serves as a transparent base material for protective films, phase difference plates, and window films.

As the above-mentioned protective film, it is sufficient as long as it is a transparent polymer film. Specifically, as the polymer film used, there may be mentioned: polyethylene, polypropylene, polymethylpentene, and a Cycloolefin derivatives such as olefin monomer units, polyolefins, diacetyl cellulose, triacetyl cellulose, propylene cellulose, etc. (modified) cellulose, methyl methacrylate Acrylics such as (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile-butadiene-styrene copolymers, acrylonitrile-styrene copolymers, ethylene-vinyl acetate copolymers Materials, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, etc. Polyamides, polyimines, polyimines, polyetherimines, polyether nitrites, polyvinyls, polyvinyl alcohols, polyvinyl acetals such as esters and nylons Films such as polyamides, polyurethanes, epoxy resins, etc., in terms of excellent transparency and heat resistance, preferably, polyamide, polyimidimide, polyimide, Polyester, olefin, acrylic or cellulosic film. These polymers can be used alone or in combination of two or more. These films can be used in the unstretched state, or used as uniaxially or biaxially stretched films. 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 coating and curing a cationic curing composition such as epoxy resin or a radical curing composition such as acrylate. If necessary, it may contain plasticizers, ultraviolet absorbers, infrared absorbers, coloring agents such as pigments or dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, and 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 in the above range, the flexibility of the protective film will not easily decrease.

The above-mentioned λ/4 retardation plate is a film that provides a λ/4 retardation in a direction orthogonal to the traveling direction of incident light (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 contain phase difference adjuster, plasticizer, ultraviolet absorber, infrared absorber, coloring agent such as pigment or dye, fluorescent brightener, dispersant, heat stabilizer, light stabilizer, antistatic agent, 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 in the above range, the flexibility of the film tends to be less likely to decrease. 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 having the property of displaying liquid crystal states such as nematic, cholesteric, and smectic. Any compound including a liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The above-mentioned liquid crystal coating type retardation plate may further contain 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 in the same manner as described in the liquid crystal polarizing layer by the following method: a liquid crystal composition is coated on an alignment film and cured to form a liquid crystal retardation layer. The liquid crystal coating type retardation plate can be made 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 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. It is also preferable when the above-mentioned base material serves as a transparent base material for protective films, phase difference plates, and window films.

Generally, the shorter the wavelength, the greater the birefringence, and the longer the wavelength, the smaller the birefringence. In this case, the λ/4 phase difference cannot be achieved in the entire visible light region, so the in-plane phase difference that becomes λ/4 near 560 nm, where the visual sensitivity is high, is 100 to 180 nm, preferably 130 to 150 There are many cases of nm design. When using a reverse-dispersion λ/4 retardation plate that uses a material with a birefringence wavelength dispersion characteristic opposite to that of usual, the visibility can be improved, which is preferable. As such a material, in the case of the extension type retardation plate, the one described in Japanese Patent Laid-Open No. 2007-232873 etc. is used, and in the case of the liquid crystal coating type retardation plate, the Japanese Patent Laid-Open No. 2010-30979 is used. It is also better when the situation is recorded in the bulletin. In addition, as another method, a technique of obtaining a wide-band λ/4 retardation plate by combining a λ/2 retardation plate is also known (Japanese Patent Laid-Open No. 10-90521, etc.). The λ/2 phase difference plate is also manufactured by the same material method as the λ/4 phase difference plate. The combination of the extension type retardation plate and the liquid crystal coating type retardation plate is arbitrary, and when both liquid crystal coating type retardation plates are used, the thickness can be made thinner, which is preferable. A method of laminating a positive C plate on the above-mentioned circular polarizing plate in order to improve the visibility in the oblique direction (Japanese Patent Laid-Open No. 2014-224837 etc.) is known. The positive C plate can also 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 provided with the optical film of the present invention may further be provided with a touch sensor. The touch sensor is used as an input mechanism. As a touch sensor, various styles such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and an electrostatic capacitance method have been proposed, and any method may be used. Among them, the electrostatic capacitance method is preferred. The capacitive touch sensor is divided into an active area and an inactive area located outside the active area. The active area is the area corresponding to the area of the display screen (display part) in the display panel, and is the area that perceives the user's touch, and the inactive area is the area corresponding to the area (non-display part) where no picture is displayed in the display device. The touch sensor may include: a substrate with flexible characteristics; a sensing pattern formed in the active area of the substrate; and an inactive area formed on the substrate and used to communicate with each other through the sensing pattern and the pad portion Each sensing line connected to the external drive circuit. As a substrate with flexible characteristics, the same material as the above-mentioned polymer film can be used. Among the substrates of the touch sensor, those with a toughness of 2,000 MPa% or more are better in terms of crack suppression of the touch sensor. The toughness can be 2,000～30,000 MPa%. Here, the toughness is defined as the area under the curve up to the point of failure in the stress-strain curve obtained by 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 where each unit pattern is separated into an island form. Therefore, to electrically connect the second pattern, another bridge electrode is required. A well-known transparent electrode material can be used for the sensing pattern. For example, 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 singly or mixed Use more than two kinds. 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 alone or in combination of two or more.

The bridge electrode can be formed on the upper part of the above-mentioned insulating layer via an insulating layer on the upper part of the sensing pattern, and the bridge electrode can be formed on the substrate, and the insulating layer and the sensing pattern can be formed thereon. The above-mentioned bridging electrode can be formed by the same material as the sensing pattern, or by metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of these And formed. 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 electrode, 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. The above-mentioned touch sensor may further include an optical adjustment layer between the substrate and the electrode, as a suitable compensation for the difference in transmittance between the patterned area and the non-patterned area, specifically because of these As a mechanism for the difference in light transmittance induced by the difference in refractive index in the region, the optical adjustment layer may contain 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 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 contain, 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 different repeating units such as epoxy-containing repeating units, acrylate repeating units, and carboxylic acid repeating units. The above-mentioned inorganic particles may contain zirconium oxide particles, titanium oxide particles, aluminum oxide particles, and the like, for example. The photocurable composition may further contain various additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

[Next layer] The layers (window film, circular polarizing plate, touch sensor) and the film members (linear polarizing plate, λ/4 phase difference plate, etc.) constituting each layer of the above-mentioned laminated body for flexible image display devices can be formed by Then the agent followed. As the adhesive, water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent-volatile adhesives, moisture-curing adhesives, heat-curing adhesives, and anaerobic curing adhesives can be used Adhesives, active energy ray hardening adhesives, hardener mixed adhesives, hot melt adhesives, pressure sensitive adhesives (adhesives), rewetting adhesives, etc. are usually used. Among them, water-based solvent volatile adhesives, active energy ray hardening adhesives, and adhesives are often used. The thickness of the adhering layer can be appropriately adjusted according to the required adhesive force, etc., for example, 0.01-500 μm, preferably 0.1-300 μm. There may be a plurality of adhesive layers in the above-mentioned laminate for flexible image display devices, and the thickness of each and the type of adhesive 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 and other water-soluble polymers, ethylene-vinyl acetate emulsions, and styrene-butadiene emulsions 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. In the case of bonding with the water-based solvent-volatile adhesive, the water-based solvent-volatile adhesive is injected between the layers to be bonded and the bonded layers are bonded, 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 is 0.01-10 μm, preferably 0.1-1 μm. When the above-mentioned water-based solvent-volatile adhesive is used in the formation of multiple layers, the thickness of each layer and the type of the above-mentioned 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 for forming an adhesive layer by irradiating active energy rays. The active energy ray hardening composition may contain at least one polymer of the same radical polymerizable compound and cationic polymerizable compound as the hard coating composition. The above-mentioned 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 when it contains a monofunctional compound.

The above-mentioned cationically polymerizable compound is the same as the hard coat composition, and the same kind as the hard coat composition can be used. As the cationic polymerizable compound used in the active energy ray curing composition, epoxy compounds are particularly preferred. In order to reduce the viscosity of the adhesive composition, it is also preferable to contain a monofunctional compound as the reactive diluent. The active energy ray composition may further contain a polymerization initiator. As the polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, etc. can be selected and used appropriately. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate free radicals or cations, thereby performing radical polymerization and cationic polymerization. In the description that the hard coat composition can be used, an initiator that can start at least any one of radical polymerization or cationic polymerization by active energy ray irradiation.

The active energy ray curable composition may further contain ion scavengers, antioxidants, chain transfer agents, adhesion imparting agents, thermoplastic resins, fillers, flow viscosity modifiers, plasticizers, defoamer solvents, additives, and solvents. In the case of bonding by the above-mentioned active energy ray-curable adhesive, the above-mentioned active energy ray-curing composition is applied to either or both of the layers to be adhered and then bonded, passing through either or both layers. The layer to be adhered is irradiated with active energy rays and hardened, thereby enabling adhesion. In the case of using the active energy ray-curable adhesive, the thickness of the adhesive layer is 0.01-20 μm, preferably 0.1-10 μm. When the above-mentioned active energy ray-curing 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.

The above-mentioned adhesives are classified into acrylic adhesives, urethane adhesives, rubber-based adhesives, silicone-based adhesives, etc. according to the main agent polymer, and any of them can be used. In addition to the main agent polymer, the adhesive can also be formulated with crosslinking agents, silane-based compounds, ionic compounds, crosslinking catalysts, antioxidants, adhesion imparting agents, plasticizers, dyes, pigments, inorganic fillers, etc. The components constituting the adhesive are 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. In order to cover the adhesive surface before bonding, it is also better 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 light-shielding pattern can be used as at least a part of the frame or housing of the flexible image display device. The light-shielding pattern hides the wiring arranged at the edge of the flexible image display device so that it is not easily visible, thereby improving the visibility of the image. The aforementioned light-shielding pattern may be in the form of a single layer or multiple layers. The color of the shading pattern is not particularly limited, and can have multiple colors such as black, white, and metallic. The light-shielding pattern can be formed by pigments and polymers such as acrylic resins, ester resins, epoxy resins, polyurethanes, and silicones for color development. These can be used alone or in a mixture of two or more. The aforementioned light-shielding pattern can be formed by various methods such as printing, lithography, and inkjet. The thickness of the light-shielding pattern is usually 1-100 μm, preferably 2-50 μm. In addition, 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 described in further detail with examples. The "%" and "parts" in the examples indicate mass% and mass parts respectively, unless otherwise stated. First, the method of measuring physical properties is explained. In addition, the results shown in Table 1 are measured according to the following measurement methods.

(Determination of weight average molecular weight (Mw)) The weight average molecular weight of the resin is measured using gel permeation chromatography (GPC). The preparation method and measurement conditions of the measurement sample are as follows. (1) Sample preparation method Weigh 20 mg of resin and add 10 mL of DMF (Dimethylformamide) (10 mM lithium bromide) to completely dissolve it. This solution was filtered through a chromatographic disc (pore size 0.45 μm) and used as a sample solution. (2) Measurement conditions Device: HLC-8020GPC Column: Guard column＋TSKgelα-M(300 mm×7.8 mm diameter)×2 pieces+α-2500(300 mm×7.8 mm diameter)×1 pieces Eluent: DMF (add 10 mM lithium bromide) Flow rate: 1.0 mL/min. Detector: RI detector Column temperature: 40℃ Injection volume: 100 μL Molecular weight standard: standard polystyrene

(Determination of total light transmittance) The total light transmittance of the optical film is measured in accordance with JIS K 7105:1981, by the automatic direct reading haze meter HGM-2DP manufactured by Suga Test Instruments Co., Ltd.

(Determination of elastic modulus) Use a dumbbell cutter to cut the optical film into short strips of 10 mm×100 mm to obtain test samples. For the elastic modulus of the test sample, the Autograph AG-IS manufactured by Shimadzu Corporation was used to measure the SS curve at a distance between the chucks of 50 mm and a tensile speed of 10 mm/min. The range is from 5 to 20 MPa The tilt calculates the elastic modulus (GPa) of the optical film.

(Measurement of thickness) For the optical films obtained in the examples and comparative examples, the thickness of the optical film was measured using an ABS digital scale (manufactured by Mitutoyo Co., Ltd., "ID-C112BS").

(Determination of time-of-flight secondary ion mass spectrometry (TOF-SIMS)) The "Ultramicrotome EM UC6" manufactured by Leica Microsystems (stock) was used to make the cross section of the optical film.

Analyze the cross-section of the produced resin film by TOF-SIMS. The TOF-SIMS device and measurement conditions used in the analysis are as follows. (1) Device: "TOF.SIMS V" manufactured by ION-TOF Corporation (2) Primary ion: Bi ^{3 ＋＋} (3) Primary ion acceleration voltage: 25 kV (4) Irradiation ion current: 0.23 pA (5) Measurement conditions : In the spotlight (high-quality decomposition energy) mode, measure positive and negative ions (6) Measuring range: 200 μm×200 μm.

The data analysis system of TOF-SIMS uses SurfaceLab. Carry out the mass calibration of the measurement data, and calculate the integrated value of the peaks for the peaks attributed to Na ion and CH ₃ ion. The integral value of the peak of Na ions is taken as the ionic strength of _Na I _Na , and the integral value of the peak of CH ₃ ions is taken as the ionic strength of CH ₃ I _CH3 , and the ratio I _Na /I _{CH3 is} calculated.

(Determination of viscosity) The viscosity of the resin composition is measured under the following conditions. Device name: LVDV-II+Pro (manufactured by Brookfield) Measuring temperature: 25℃ Shaft: CPE-52 Sample size: 0.8 mL Rotor speed: 3 rpm

[Synthesis example: production of polyimide resin] Pass nitrogen through a reaction vessel equipped with a fully dried stirrer and thermometer, and replace the vessel with nitrogen. The reaction vessel was charged with 1907.2 parts by mass of dimethylacetamide (DMAc), and 111.94 parts by mass of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 4,4'-(hexafluoro 46.84 parts by mass of isopropylidene) diphthalic dianhydride (6FDA) were reacted. Then, 10.37 parts by mass of 4,4'-oxybis(benzyl chloride) (OBBC) and 42.79 parts by mass of terephthalate chloride (TPC) were added and reacted. Then, 37.66 parts by mass of acetic anhydride was added, and after stirring for 15 minutes, 11.45 parts by mass of 4-picoline was added, and the reaction vessel was heated to 70° C., followed by stirring for 3 hours to obtain a reaction liquid. The reaction liquid was cooled, 3794.5 parts by mass of methanol was added, and then 1419.4 parts by mass of ion-exchange water was added dropwise to precipitate a white solid. The precipitated white solid was captured by centrifugal filtration, and washed with methanol, thereby obtaining a wet cake containing polyimide resin. The obtained wet cake was dried at 78°C under reduced pressure, thereby obtaining a powder of polyimide resin. The weight average molecular weight of the obtained resin was 466,000.

[Manufacture of GBL solution containing sodium] A sodium ethoxide ethanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) containing 20% by mass of sodium ethoxide (NaOEt, a compound containing sodium atoms) as a sodium component was diluted with γ-butyrolactone (GBL) to prepare a 0.1 mass % NaOEt solution containing sodium ethoxide.

[Manufacturing of polyamide imide resin composition (varnish)] The polyamide imide resin, GBL obtained in the above synthesis example, and the NaOEt solution prepared as described above are set to the following values as the content ratio of polyamide imide resin and NaOEt in each resin composition The amount is mixed to prepare a polyimide resin composition (varnish) for film formation. The content of the polyimide resin in each resin composition is 6.3% by mass relative to the total amount of the polyimide resin composition, and the content of NaOEt in each resin composition is relative to that in each resin composition The amount of the polyimide resin contained is 0% by mass, 0.005% by mass, 0.05% by mass, 0.1% by mass, or 1% by mass, respectively.

[Examples 1, 2 and Comparative Example 3: Production of polyimide resin film] Using an applicator, the polyamide imide resin composition (resin composition with a NaOEt content of 0.05% by mass, 0.005% by mass or 0% by mass) manufactured as described above is made into a self-supporting film with a thickness of 55 μm Coated on the smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name "A4100"), dried at 50°C for 30 minutes, and then dried at 140°C for 15 minutes, and then the resulting coating film was self-polymerized The ester substrate was peeled off to obtain a self-supporting film. The self-supporting film was fixed to a metal frame, and then dried in the atmosphere at 200° C. for 40 minutes to obtain a polyamide imide resin film with a thickness of 50 μm. Various physical properties of this film were measured, and the results are shown in Table 1.

[Table 1] Adding amount of NaOEt [mass%] TOF-SIMS Modulus of elasticity [MPa] Total light transmittance [%] I _Na I _{CH 3} I _Na /I _CH3 Example 1 0.05 57182 2983 19.166 5.3 91.1 Example 2 0.005 3146 1714 1.835 5.2 91.5 Comparative example 1 0 - 4.9 91.2

[Examples 3 and 4: Viscosity measurement of polyimide resin composition] The ratio of the amount of NaOEt obtained as described above to the amount of polyimide resin is 0% by mass, 0.1% by mass or 1% by mass, respectively, according to the above measurement method Determine the viscosity. The results obtained are shown in Table 2.

[Table 2] Adding amount of NaOEt [mass%] Viscosity [mPas] Comparative example 1 0 32,089 Example 3 0.1 41,011 Example 4 1 85,991

As shown in Table 1, it is confirmed that the ratio of the ionic strength measured by TOF-SIMS (I _Na /I _CH3 ) with NaOEt added to the varnish is 0.2 or more. The optical films of Examples 1 and 2 have high elasticity Modulus. On the other hand, in the case of the optical film of Comparative Example 1 where NaOEt was not added to the varnish, a sufficient elastic modulus was not obtained. Moreover, as shown in Table 2, it was confirmed that the viscosity of the resin composition tends to increase by adding a sodium-containing component to the resin composition. The reason why the viscosity of the resin composition increases by adding sodium-containing ingredients is not clear, but it is guessed that the functional groups in the resin, such as imine bonds and/or amide bonds, and sodium-containing components (compounds containing sodium atoms, Sodium and/or sodium ions). It is believed that this interaction leads to an increase in the elastic modulus of the obtained optical film, but this discussion has any limitation on the present invention.

Claims (12)

An optical film containing at least one resin selected from the group consisting of polyimide resins and polyamide resins, and the optical film is obtained by time-of-flight secondary ion mass spectrometry The ratio of the ionic strength of Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) is 0.2 or more. The optical film of claim 1, wherein the polyimide resin and the polyimide resin are aromatic resins. The optical film of claim 1 or 2, wherein the ratio of the structural unit derived from the aromatic monomer to all the structural units in the polyimide resin and the polyimide resin is 60 mol% or more. The optical film of any one of claims 1 to 3 has a thickness of 10-100 μm and a total light transmittance of 80% or more. The optical film according to any one of claims 1 to 4, wherein the weight average molecular weight of the polyimide-based resin and the polyimide-based resin is 200,000 or more. The optical film according to any one of claims 1 to 5, wherein the polyimide resin is a polyimide resin. The optical film according to any one of claims 1 to 6, wherein the polyimide resin and the polyimide resin contain structural units derived from terephthalic acid. The optical film according to any one of claims 1 to 7, which is a film for the front panel of a flexible display device. A flexible display device provided with the optical film as claimed in any one of claims 1 to 8. For example, the flexible display device of claim 9 further includes a touch sensor. For example, the flexible display device of claim 9 or 10 is further provided with a polarizing plate. A resin composition containing at least one resin selected from the group consisting of polyimide resins and polyamide resins, selected from the group consisting of compounds containing sodium atoms, sodium and sodium ions At least one sodium-containing component, and a solvent.