KR20200095406A - Optical film, flexible display device and resin composition - Google Patents

Abstract

Provided is an optical film having high abrasion resistance and a high elastic modulus. The optical film contains at least one type of resin selected from a group consisting of a polyimide-based resin and a polyamide-based resin, and a ratio of ionic strength of K (I_K) to ionic strength of CH_3 (I_CH3), obtained by time-of-flight secondary ion mass spectrometry, in the optical film (I_K/I_CH3) is 0.2 or more.

Description

An optical film, a flexible display device, and a resin composition TECHNICAL FIELD [OPTICAL FILM, FLEXIBLE DISPLAY DEVICE AND RESIN COMPOSITION}

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

Currently, image display devices such as a liquid crystal display device and an organic EL display device are widely used for various purposes such as mobile phones and smart watches. Although glass has been used as the front plate of such an image display device, since the glass is very rigid and fragile, it is difficult to use, for example, a front plate material of a flexible display device. Therefore, utilization of a polymer material as one of the materials instead of glass has been studied, and an optical film using, for example, a polyimide resin has been studied (for example, Patent Document 1).

Japanese Unexamined Patent Application Publication No. 2018-119132

When manufacturing a flexible display device containing an optical film, attaching a protective film to an optical film, winding an optical film in a roll shape, conveying an optical film, etc. are performed. In these cases, the optical film and the protective film and/or the packaging film may be rubbed against each other, and fine scratches may occur on the surface of the optical film due to friction. In addition, when an optical film containing a polyimide resin, a polyamide resin, etc. is used in a flexible display device, etc., when defects such as scratches and wrinkles occur in the optical film due to bending or contact with external factors. In addition, from the viewpoint of preventing these, it is also required to increase the elastic modulus of the optical film and improve the impact resistance.

Therefore, the present invention makes it a subject to provide an optical film having high abrasion resistance and high elastic modulus.

In order to solve the above problems, the inventors of the present invention have conducted intensive examinations, paying attention to the types and amounts of components contained in the resin film. As a result, the ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) obtained by the time-of-flight secondary ion mass spectrometry in the optical film (I _K / I _CH3 ) was 0.2 In the above case, surprisingly, it was found that the abrasion resistance and the elastic modulus of the optical film were easily improved, and the present invention was completed.

That is, the present invention includes the following suitable aspects.

[1] An optical film comprising at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, the ionic strength of CH ₃ obtained by a time-of-flight secondary ion mass spectrometry method of the optical film The optical film, wherein the ratio of the ionic strength (I _K ) of K to (I _CH3 ) (I _K /I _CH3 ) is 0.2 or more.

[2] The optical film according to [1], wherein the polyimide-based resin and the polyamide-based resin are aromatic resins.

[3] The optical film according to [1] or [2], wherein the ratio of the constitutional units derived from the aromatic monomer to all constitutional units in the polyimide resin and the polyamide resin is 60 mol% or more.

[4] The optical film according to any one of [1] to [3], wherein the thickness is 10 to 100 µm, and the total light transmittance is 80% or more.

[5] The optical film according to any one of [1] to [4], wherein the weight average molecular weight of the polyimide resin and the polyamide resin is 200,000 or more.

[6] The optical film according to any one of [1] to [5], wherein the polyimide resin is a polyamideimide resin.

[7] The optical film according to any one of [1] to [6], wherein the polyimide resin and the polyamide resin contain a structural unit derived from terephthalic acid.

[8] The optical film according to any one of [1] to [7], wherein the elastic modulus is 5.0 GPa or more.

[9] The optical film according to any one of [1] to [8], which is a film for a front plate of a flexible display device.

[10] A flexible display device comprising the optical film according to any one of [1] to [9].

[11] The flexible display device according to [10], further comprising a touch sensor.

[12] The flexible display device according to [10] or [11], further comprising a polarizing plate.

(13) at least one resin selected from the group consisting of polyimide resins and polyamide resins, a compound containing potassium atoms, at least one potassium-containing component selected from the group consisting of potassium and potassium ions, and , A resin composition containing at least a solvent.

The optical film of the present invention has high abrasion resistance and high elastic modulus.

1 is a diagram for explaining a test method of an abrasion test.
It is a figure for demonstrating the test method of the abrasion test.
3 is a diagram for explaining a test method of an abrasion test.

Hereinafter, an embodiment of the present invention will be described in detail. In addition, the scope of the present invention is not limited to the embodiments described herein, and various changes can be made without departing from the spirit 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 a polyimide resin and a polyamide resin, and the time-of-flight secondary ion mass spectrometry (TOF-SIMS) of the optical film The ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) obtained by) (I _K /I _CH3 ) is 0.2 or more.

In the optical film of the present invention, the ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) (I _K / I _CH3 ) is the time-of-flight secondary ion mass spectrometry (Time-of -Flight Secondary Ion Mass Spectrometry: In this specification, also referred to as ``TOF-SIMS''), the ionic strength of CH ₃ (I _CH3 ) and the ionic strength of _K (I _K ) of the optical film were measured, and I _K It is calculated by dividing by I _CH3 . In addition, in this specification, the ionic strength of CH ₃ (I _CH3 ) and the ionic strength of _K (I _K ) measured by the time-of-flight secondary ion mass spectrometry are peaks attributed to CH ₃ ions in the measurement data. The integral value of is called the ionic strength of CH ₃ (I _CH3 ), and the integral value of the peak attributable to K ions is called the ionic strength of _K (I _K ).

TOF-SIMS is a type of mass spectrometry, and according to TOF-SIMS, it is possible to obtain an element or molecular species present on the outermost surface of a sample with very high detection sensitivity, and also, an element or molecular species present on the outermost surface of a sample. The distribution of can also be investigated.

TOF-SIMS is a method of irradiating a sample with an ion beam (primary ions) in a high vacuum, and mass-separating the ions emitted from the surface using the flight time difference. When primary ions are irradiated, positive or negatively charged ions (secondary ions) are released from the sample surface, but lighter ions fly faster and heavier ions fly slower, so secondary ions are generated. Then, by measuring the time until detection (flight time), the mass of the generated secondary ions can be calculated.

In the measurement by TOF-SIMS, CH ₃ ions are detected in the vicinity of 15.02 u in mass and K ions are detected in the vicinity of 38.96 u in mass. In addition, these ions are ions detected in either positive (positive) ion analysis and negative (negative) ion analysis. In the present invention, the ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) (I _K / I _CH3 ) may be a ratio detected by positive ion analysis, or may be used in negative ion analysis. The ratio detected by this method may be sufficient, and if the ratio of at least one of the above ratios is 0.2 or more, the requirement that the ratio (I _K /I _CH3 ) in the present invention is 0.2 or more is satisfied. From the viewpoint of obtaining higher detection sensitivity, conditions using positive ion analysis are preferable.

Measurement by TOF-SIMS was performed using a time-of-flight secondary ion mass spectrometer for the optical film, where the primary ion was Bi ³⁺⁺ , the acceleration voltage of the primary ion was 25 kV, and the irradiated ion current was 0.23 kW, It can be carried out by positive ion analysis or negative ion analysis under conditions of a measurement range of 200 μm×200 μm. Measurement by TOF-SIMS can be performed according to the method described in Examples, for example. The ratio (I _K / I _CH3 ) measured with respect to at least a portion of the surface or cross-section of the optical film should be within the above range, but it is assumed that the composition inside the optical film is likely to be affected by the mechanical strength of the optical film. It is preferable that the ratio (I _K /I _CH3 ) measured with respect to the cross section of the optical film is within the above range.

According to the optical film of the present invention in which the ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) obtained by time-of-flight secondary ion mass spectrometry (I _K / I _CH3 ) is 0.2 or more, Surprisingly, it is possible to improve the abrasion resistance and elastic modulus of the optical film. Here, the ionic strength of CH ₃ (I _{CH 3} ) and the ionic strength of _K (I _K ) obtained by the time-of-flight secondary ion mass spectrometry are the amount of carbon atoms and/or carbon ions present in the optical film, potassium atoms, and /Or the amount of potassium ions is shown relatively. The ratio of 0.2 or more indicates that a certain amount of potassium atoms (K) and/or the total amount of potassium ions is present with respect to the total amount of carbon atoms and/or carbon ions present in the optical film. In addition, the reason why carbon atoms and carbon ions are detected as CH ₃ ions is that in the time-of-flight secondary ion mass spectrometry, various secondary ions generated are also detected in the form of proton adducts, and This is because CH ₃ ions are generated simultaneously as a proton adduct.

The reason why the abrasion resistance and the elastic modulus of the optical film are improved by the presence of potassium atoms and/or potassium ions in a certain amount or more is not clear, and the present invention is not limited at all to the mechanisms described later, for example, the following mechanisms. It is thought that the abrasion resistance and elastic modulus are improved by this. When preparing the optical film of the present invention, the imide contained in the resin by including a compound containing a potassium atom, potassium and/or potassium ions in a composition containing a polyimide resin and/or a polyamide resin A bond and/or an amide bond, preferably an imide bond included in the polyimide resin, and a compound containing a potassium atom, potassium and/or potassium ions, some interaction (for example, It is thought that an electrostatic interaction between the carbonyl group of the imide bond or the amide bond and the potassium ion) occurs. As a result, the polyimide-based resin and/or polyamide-based resin contained in the obtained optical film is present in the film while interacting with a compound containing a potassium atom, potassium and/or potassium ions, or potassium Abrasion resistance and elastic modulus of the optical film are improved by changing the orientation state of the resin due to the interaction of the compound containing an atom, potassium and/or potassium ions with the polyimide resin and/or the polyamide resin. I think it works. From the viewpoint of easy interaction with the polyimide resin and/or the imide bond and/or the amide bond of the polyimide resin and/or the polyamide resin, the potassium-containing component contained in the optical film is preferably in an ionized state. In addition, in the present specification, a compound containing a potassium atom that can be included in the optical film, potassium and/or is considered to be detected as an ionic strength (I _K ) of _K when the optical film is subjected to time-of-flight secondary ion mass spectrometry. Alternatively, the potassium ion is also referred to as a "potassium-containing component". In addition, the compound containing a potassium atom is a compound containing a potassium atom as a constituent atom of a molecule.

The ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) (I _K /I _CH3 ) is preferably 0.95 or more from the viewpoint of easy to increase the abrasion resistance and elastic modulus of the optical film. , More preferably 1.0 or more, more preferably 1.2 or more, even more preferably 1.4 or more, even more preferably 1.5 or more, even more preferably 3 or more, particularly preferably 5 or more, more particularly preferably Is 10 or more, most preferably 12 or more. The upper limit of the ratio (I _K /I _CH3 ) is preferably 100 from the viewpoint of easy to increase the film-forming properties of a varnish containing a polyimide-based resin and/or a polyamide-based resin, and to increase the uniformity of an optical film. Hereinafter, more preferably 50 or less, still more preferably 30 or less, even more preferably 25 or less, and particularly preferably 20 or less.

The method of adjusting the ratio (I _K / I _CH3 ) to the above range is not particularly limited, but a potassium-containing component (potassium) in the optical film of the present invention containing a polyimide resin and/or a polyamide resin A method of adjusting the content of the compound containing an atom, potassium and/or potassium ion), and a method of adjusting the content of the polyimide resin and/or polyamide resin included in the optical film are mentioned. Specifically, when the content of the potassium-containing component in the optical film is increased, the ionic strength (I _K ) of _K obtained by TOF-SIMS of the optical film is also increased. When the content of the polyimide resin and/or the polyamide resin contained in the optical film is increased, the ionic strength (I _CH3 ) of CH ₃ obtained by TOF-SIMS of the optical film is also increased. Therefore, when the content of the potassium-containing component in the optical film is increased, the value of the ratio (I _K / I _CH3 ) increases, and when the content of the polyimide resin and/or polyamide resin contained in the optical film is increased , The value of the ratio (I _K /I _CH3 ) decreases. By the above method, the ratio (I _K /I _CH3 ) can be adjusted to a desired range.

In the optical film of the present invention, the ionic strength of CH ₃ (I _CH3 ) and the ionic strength of _K (I _K ) by TOF-SIMS are not particularly limited, and the value of the ratio (I _K /I _CH3 ) is the above The range is sufficient, but from the viewpoint of easy to secure the accuracy of measurement by TOF-SIMS, the ionic strength (I _K ) of _K is preferably 100 or more, more preferably 300 or more, and more preferably 500 or more. It is preferable to perform the measurement under the conditions that become.

The optical film of the present invention having a ratio (I _K /I _CH3 ) of 0.2 or more has high abrasion resistance. In the present specification, the abrasion resistance means when friction occurs between the optical film and the protective film and/or the packaging film (for example, at the time of manufacturing a film roll, at the time of transporting the optical film, etc.) , It indicates that the optical film is hardly scratched due to the friction. The abrasion resistance of the optical film is, for example, using a steel wool tester as described in Examples, while applying a load of 500 gf, while contacting the film used as a protective film or packaging film and the optical film, the It can be evaluated by the abrasion test in which friction is caused between the film and the optical film, and the number of frictions until the optical film is scratched is measured. In the optical film of the present invention, the number of reciprocations that can withstand the occurrence of scratches in the abrasion test described above is preferably 400 or more, more preferably 500 or more, further preferably 550 or more, Even more preferably, it is 600 or more times.

The optical film of the present invention having a ratio (I _K /I _CH3 ) of 0.2 or more has a high modulus of elasticity. The elastic modulus of the optical film of the present invention is preferably 5.0 GPa or more, more preferably 5.1 GPa or more, and still more preferably 5.2 GPa or more. The upper limit of the elastic modulus is not particularly limited, but is usually 100 GPa or less. In addition, the modulus of elasticity can be measured using a tensile tester (e.g., a chuck distance of 50 mm and a tensile speed of 10 mm/min), and, for example, can be measured by the method described in Examples. . By increasing the elastic modulus of the optical film, the impact resistance of the optical film is improved and it tends to be easy to prevent scratching of the optical film due to bending, etc., but when only improving the elastic modulus is not sufficient abrasion resistance There is also. However, the optical film of the present invention has high abrasion resistance and has a high elastic modulus. In addition, if the weight average molecular weight of the resin contained in the optical film is increased, the elastic modulus tends to increase, but according to the optical film of the present invention, even when the weight average molecular weight of the resin contained in the optical film is relatively low, the optical film The modulus of elasticity can be increased.

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, even more preferably 90% or more, and particularly preferably 91% or more. , Usually less than 100%. When the total light transmittance is more than the above lower limit, it is easy to increase the visibility when the optical film is assembled to an image display device, particularly as a front plate. Since the optical film of the present invention usually exhibits a high total light transmittance, it becomes possible to suppress the luminous intensity of a display element or the like necessary for obtaining a constant brightness as compared to a case where a film having a low transmittance is used, for example. For this reason, power consumption can be reduced. For example, in the case of assembling the optical film of the present invention in an image display device, a bright display tends to be obtained even if the amount of light of the backlight is reduced, and thus it can contribute to energy saving. The upper limit of the total light transmittance is usually 100% or less. In addition, the total light transmittance can be measured using a haze computer in conformity with JIS K 7105:1981, for example. The total light transmittance may be a total light transmittance in the range of the thickness of the optical film described later.

The haze of the optical film of the present invention is preferably 1% or less, more preferably 0.5% or less, even more preferably 0.2% or less, even more preferably 0.15% or less, particularly preferably 0.14% or less, more It is particularly preferably 0.1% or less, and usually 0.01% or more. When the haze of the optical film is less than or equal to the above upper limit, when the optical film is assembled to an image display device, particularly as a front plate, it is easy to increase visibility. Moreover, the lower limit of haze is usually 0.01% or more. In addition, haze can be measured using a haze computer according to JIS K 7105:1981.

The yellowness (hereinafter, also referred to as 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. When the YI value of the optical film is less than or equal to the above upper limit, transparency becomes good, and when used for the front plate of an image display device, high visibility can be contributed. Moreover, the YI value is usually -5 or more, and preferably -2 or more. In addition, the YI value was measured by measuring the transmittance of light of 300 to 800 nm using an ultraviolet visible near-infrared spectrophotometer to obtain three stimulation values (X, Y, Z), and YI = 100 × (1.2769X-1.0592Z). It can be calculated based on the equation of )/Y.

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, even more preferably 30 μm or more, preferably 100 μm or less, more It is preferably 80 µm or less, more preferably 60 µm or less, and a combination of these upper and lower limits may be used. When the thickness of the optical film is within the above range, it is easy to further increase the abrasion resistance and elastic modulus of the optical film. In addition, the thickness of the optical film can be measured using a micrometer, and for example, can be measured by the method described in Examples.

In the optical film of the present invention, the number of bending (bending radius R = 1 mm) in the bending resistance test is preferably 150,000 or more, more preferably 180,000 or more, and still more preferably 200,000 or more. . When the number of bending is more than the above lower limit, it has sufficient bending resistance as a front plate material for a flexible display device or the like. In addition, the number of bending in the bending resistance test was repeated using a bending tester and bending the optical film repeatedly under the condition that the bending radius (curvature radius) (R) was 1 mm, and the film was broken. It shows the number of reciprocating bends (one reciprocation is referred to as one) until the time when this occurs.

<Polyimide resin and polyamide resin>

The optical film of the present invention contains a polyimide resin and/or a polyamide resin. In the present specification, the polyimide resin refers to at least one resin selected from the group consisting of a polyimide resin, a polyamideimide resin, a polyimide precursor resin, and a polyamideimide precursor resin. The polyimide resin is a resin containing a repeating structural unit containing an imide group, and the polyamideimide resin is a resin containing a repeating structural unit containing both an imide group and an amide group (兩方). Each of the polyimide precursor resin and the polyamideimide precursor resin is a precursor before imidization that provides a polyimide resin and a polyamideimide resin by imidization, and is a resin also called polyamic acid. In addition, in this specification, the polyamide resin is a resin containing a repeating structural unit containing an amide group. The optical film of the present invention may contain one type of polyimide type resin or polyamide type resin, or may contain two or more types of polyimide type resin and/or polyamide type resin in combination. The optical film of the present invention preferably contains a polyimide resin, and the polyimide resin is preferably a polyimide resin or a polyamide from the viewpoint of being easy to achieve both chemical stability and high modulus of elasticity of the optical film. It is a mid resin, More preferably, it is a polyamideimide resin.

In a preferred embodiment of the present invention, it is preferable that the polyimide-based resin and the polyamide-based resin are aromatic resins from the viewpoint of easier to increase the abrasion resistance and elastic modulus of the optical film. In the present specification, the aromatic resin refers to a resin in which the structural units contained in the polyimide resin and the polyamide resin are mainly aromatic structural units.

In the above-described preferred embodiment, from the viewpoint of more easily increasing the abrasion resistance and elastic modulus of the optical film, a structural unit derived from an aromatic monomer with respect to all the structural units contained in the polyimide resin and the polyamide resin The ratio of 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 is derived from a monomer containing at least a part of an aromatic structure (eg, an aromatic ring), and at least a part of the aromatic structure (eg, an aromatic ring) It is a structural unit included in. As an aromatic monomer, an aromatic tetracarboxylic acid compound, an aromatic diamine, an aromatic dicarboxylic acid, etc. are mentioned, for example.

In a preferred embodiment of the present invention, the polyimide resin is a polyimide resin having a structural unit represented by formula (1), or a structural unit represented by formula (1) and formula (2). It is preferable that it is a polyamide-imide resin which has the structural unit shown. Moreover, it is preferable that the polyamide-type resin is a polyamide-type resin which has a structural unit represented by Formula (2). Hereinafter, formulas (1) and (2) will be described, but the description of formula (1) relates to both a polyimide-based resin and a polyamide-imide-based resin, and the description of formula (2) is , To both a polyamide-based resin and a polyamide-imide-based resin.

[Formula 1]

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

In formula (2), Z is a divalent organic group, preferably a C 1 to C 8 hydrocarbon group, a fluorine-substituted C 1 to C 8 hydrocarbon group, a C 1 to C 6 alkoxy group, or a fluorine-substituted carbon number. It is a C4 to C40 divalent organic group which may be substituted by an alkoxy group of 1 to 6, more preferably a C 1 to C 8 hydrocarbon group, a fluorine substituted C 1 to C 8 hydrocarbon group, or a C 1 to C 6 It represents a C4 to C40 divalent organic group having a cyclic structure which may be substituted with an alkoxy group of or a fluorine-substituted alkoxy group having 1 to 6 carbon atoms. As a cyclic structure, an alicyclic, an aromatic ring, and a heterocyclic structure are mentioned. As the organic group of Z, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula ( Among the bond hands of the groups represented by 28) and formula (29), a group in which two non-adjacent groups are substituted with hydrogen atoms and a divalent chain hydrocarbon group having 6 or less carbon atoms are exemplified, and the heterocyclic structure of Z is a thiophene ring skeleton. The group to have is illustrated. From the viewpoint of being easy to reduce the YI value of the optical film, a group represented by formulas (20) to (29) and a group having a thiophene ring skeleton are preferred. In one embodiment of the present invention, the polyamide-based resin and the polyamide-imide-based resin may contain one type of organic group as Z, or may contain two or more types of organic groups.

As the organic group of Z, formula (20'), formula (21'), formula (22'), formula (23'), formula (24'), formula (25'), formula (26'), formula (27 '), Equation (28') and Equation (29'):

[Formula 2]

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

The divalent organic group represented by is more preferable. In addition, the hydrogen atom on the ring in the formulas (20) to (29) and (20') to (29') is a hydrocarbon group having 1 to 8 carbon atoms or a fluorine-substituted hydrocarbon group having 1 to 8 carbon atoms. , An alkoxy group having 1 to 6 carbon atoms or a fluorine-substituted alkoxy group having 1 to 6 carbon atoms may be substituted.

When the polyamide resin or polyamideimide resin has a structural unit represented by any of the above formulas (20') to (29') in the formula (b), the polyamide resin or polyamide Mid-based resin, in addition to the structural unit, the following formula (d1):

[Formula 3]

[In formula (d1), R ²⁴ represents, independently of each other, a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and R ²⁵ is R ²⁴ Or -C (=O)-*, * represents a bond hand]

It is preferable from the viewpoint that it is easy to improve the film-forming property of a varnish and it is easy to obtain the uniformity of the optical film obtained to further have a structural unit derived from a carboxylic acid represented by.

In R ²⁴ , examples of the alkyl group having 1 to 6 carbon atoms, the alkoxy group having 1 to 6 carbon atoms, and the aryl group having 6 to 12 carbon atoms respectively include those exemplified for R ¹ to R ⁸ in Formula (3) described later. have. As the structural unit (d1), specifically, R ²⁴ and R ²⁵ are both hydrogen atoms (constituent units derived from a dicarboxylic acid compound), R ²⁴ are all hydrogen atoms, and R ²⁵ is -C (= The structural unit (constituent unit derived from a tricarboxylic acid compound) etc. which represent O)-* are mentioned.

In one embodiment of the present invention, the polyamide-based resin and the polyamide-imide-based 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 of easy to increase the abrasion resistance and elastic modulus of the optical film of the present invention, and also to increase the optical properties, at least part of Z is represented by Formula (3a):

[Formula 4]

[In formula (3a), R ^g and R ^h each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and R ^g and R The hydrogen atoms contained in ^h may be each independently substituted by a halogen atom, A, m and * are the same as A, m and * in formula (3), and t and u are each independently 0 to It is an integer of 4]

It is preferably represented by,

Equation (3):

[Formula 5]

[In equation (3),

R ¹ to R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹ to R ⁸ are , Independently of each other, may be substituted with a halogen atom,

A is, independently of each other, 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 or a monovalent hydrocarbon group having 1 to 12 carbon atoms which may be substituted by a halogen atom. ,

m is an integer from 0 to 4,

* Indicates a bond hand]

It is more preferable that it is represented by.

In formulas (3) and (3a), A is independently 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 -O- or -S-, more preferably -O-.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 It shows the aryl group of -12. R ^g and R ^h each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2-methyl-butyl Group, 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl group, and the like. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, propyloxy group, isopropyloxy group, butoxy group, isobutoxy group, tert-butoxy group, pentyloxy group, hexyloxy group, and cyclohexyl group. Siloxy groups, etc. are mentioned. 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 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms And more preferably a hydrogen atom. Here, the hydrogen atoms contained in R ¹ to R ⁸ , R ^g and R ^h may be independently of each other substituted with a halogen atom.

R ⁹ represents a C 1 to C 12 monovalent hydrocarbon group which may be substituted with a hydrogen atom or a halogen atom. As a C1-C12 monovalent hydrocarbon group, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2- Methyl-butyl group, 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl group, n-heptyl group, n-octyl group, tert-octyl group, n-nonyl group, n-decyl group, and the like. And these may be substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In formula (3a), t and u are each independently an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

In the formulas (3) and (3a), m is an integer in the range of 0 to 4, and when m is within this range, it is easy to improve the abrasion resistance, elastic modulus, and bending resistance of the optical film. In formulas (3) and (3a), m is an integer in the range of preferably 0 to 3, more preferably 0 to from the viewpoint of more easily improving the abrasion resistance, elastic modulus, and bending resistance of the optical film. It is an integer in the range of 2, more preferably 0 or 1, even more preferably 0. The structural unit represented by formula (3) or formula (3a) in which m is 0 is a structural unit derived from terephthalic acid or isophthalic acid, and the structural unit is particularly, wherein R ⁵ to R ⁸ in formula (3) are hydrogen atoms And it is preferable that it is a structural unit in which m is 0, and a structural unit in which u is 0 and m is 0 in Formula (3a). From the viewpoint of being easy to improve abrasion resistance, elastic modulus, and bending resistance of an optical film, it is preferable that the polyimide resin and the polyamide resin contain a structural unit derived from terephthalic acid. In Z, the polyimide resin and the polyamide resin may contain one or two or more structural units represented by the formula (3) or (3a). From the viewpoint of improving the abrasion resistance, elastic modulus and flexural resistance of the optical film, and reducing the YI value, the resin includes two or more structural units having different values of m in the formula (3) or (3a) in Z. It is preferable, and it is more preferable that the value of m in Formula (3) or Formula (3a) contains 2 types or 3 types of structural units which differ. In this case, from the viewpoint of being easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint of being easy to reduce the YI value of the optical film, the resin is Z, and m is 0. It is particularly preferable to contain the structural unit shown, and to further contain a structural unit represented by formula (3) in which m is 1 in addition to the structural unit. Moreover, it is also preferable to further have a structural unit represented by the said formula (d1) in addition to the structural unit represented by Formula (2) which has Z represented by Formula (3) in which m is 0.

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 a structural unit represented by formula (3). In one more preferred embodiment of the present invention, the resin is a structural unit represented by formula (3), m=0, and a structural unit wherein R ⁵ to R ⁸ is a hydrogen atom, and formula (3'):

[Formula 6]

It has a structural unit represented by In this case, it is easy to improve the abrasion resistance, elastic modulus, and bending resistance of the optical film, and it is easy to reduce the YI value.

In a preferred embodiment of the present invention in which the optical film contains a polyamideimide resin, the ratio of the structural units represented by formula (3) or (3a) is represented by the formula (1) of the polyamideimide resin. When the sum of the structural units represented and the structural units represented by formula (2) is 100 mol%, preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 40 mol% or more, It is still more preferably 50 mol% or more, particularly preferably 60 mol% or more, preferably 90 mol% or less, more preferably 85 mol% or less, and still more preferably 80 mol% or less. When the ratio of the structural unit represented by Formula (3) or Formula (3a) is more than the above lower limit, it is easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film. When the ratio of the constituent units represented by formula (3) or formula (3a) is less than or equal to the above upper limit, the viscosity increase of the resin-containing varnish due to hydrogen bonds between amide bonds derived from formula (3) or formula (3a) is suppressed, and , It is easy to improve the processability of the film.

In addition, when the polyamide-imide resin has a structural unit represented by formula (3) or formula (3a) in which m=1 to 4, m is represented by formula (3) or formula (3a) in which m is 1 to 4 The proportion of the constituent units is preferably 3 mol% or more, when the total of the constituent units represented by formula (1) and the structural units represented by formula (2) of the polyamideimide resin is 100 mol%. Preferably it is 5 mol% or more, more preferably 7 mol% or more, even more preferably 9 mol% or more, preferably 90 mol% or less, more preferably 70 mol% or less, even more preferably 50 It is mol% or less, and even more preferably, it is 30 mol% or less. When the ratio of the structural unit represented by formula (3) or formula (3a) in which m is 1 to 4 is equal to or greater than the above lower limit, it is easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film. Hydrogen bonds between amide bonds derived from structural units represented by formula (3) or formula (3a) if the ratio of the structural units represented by formula (3) or formula (3a) in which m is 1 to 4 is less than or equal to the above upper limit It is easy to suppress an increase in viscosity of the resin-containing varnish due to this and improve the workability of the film. In addition, the ratio of the structural unit represented by Formula (1), Formula (2), Formula (3) or Formula (3a) can be measured using, for example, ¹ H-NMR, or the introduction ratio of the raw material It can also be calculated from

In a preferred embodiment of the present invention, of Z in the polyamide-based resin or polyamide-imide-based resin, preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 45 mol% or more , More preferably, 50 mol% or more is a structural unit represented by formula (3) or formula (3a) wherein m is 0 to 4. If more than the said lower limit of Z is a structural unit represented by Formula (3) or Formula (3a) in which m is 0-4, it is easy to improve the abrasion resistance, elasticity modulus, and bending resistance of an optical film. Further, 100 mol% or less of Z in the polyamide-based resin or polyamide-imide-based resin may be a structural unit represented by formula (3) or formula (3a) in which m is 0 to 4. In addition, the ratio of the structural unit represented by formula (3) or formula (3a) in which m is 0 to 4 in the resin can be measured using, for example, ¹ H-NMR, or from the introduction ratio of the raw material. It can also be calculated.

In a preferred embodiment of the present invention, Z in the polyamide-based resin or polyamide-imide-based resin is preferably 5 mol% or more, more preferably 8 mol% or more, still more preferably 10 mol% or more. , More preferably, 12 mol% or more is represented by formula (3) or formula (3a) wherein m is 1 to 4. When the above lower limit of Z of the polyamideimide resin is represented by formula (3) or formula (3a) in which m is 1 to 4, the abrasion resistance, elastic modulus, and bending resistance of the optical film are easily improved. Further, of Z, preferably 90 mol% or less, more preferably 70 mol% or less, still more preferably 50 mol% or less, and even more preferably 30 mol% or less, m is 1 to 4 formula ( 3) or formula (3a). When the above upper limit of Z is represented by formula (3) or formula (3a) in which m is 1 to 4, it is derived from a structural unit represented by formula (3) or formula (3a) in which m is 1 to 4 It is easy to suppress an increase in viscosity of the resin-containing varnish due to hydrogen bonds between amide bonds and improve the processability of the film. In addition, the ratio of the structural unit represented by Formula (3) or Formula (3a) in which m in the resin is 1 to 4 can be measured using, for example, ¹ H-NMR, or calculated from the introduction ratio of the raw material. You may.

In the formulas (1) and (2), X represents, independently of each other, a divalent organic group, preferably a divalent organic group having 4 to 40 carbon atoms, more preferably 4 to 40 carbon atoms having a cyclic structure. Represents a divalent organic group of. As a cyclic structure, an alicyclic, an aromatic ring, and a heterocyclic structure are mentioned. In the organic group, the hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in that case, the hydrocarbon group and the fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. In one embodiment of the present invention, the polyamide resin, polyimide resin, or polyamideimide 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. X is a group represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) and formula (18) ; A group in which a hydrogen atom in the groups represented by the formulas (10) to (18) is substituted with a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group; And a chain hydrocarbon group having 6 or less carbon atoms.

[Formula 7]

In formulas (10) to (18),

* Represents a bond hand,

V ¹ , V ² and V ³ are each independently 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 C1-C12 monovalent hydrocarbon group which may be substituted with a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 carbon atoms include the groups described above for R ⁹ .

In one example, V ¹ and V ³ are a single bond, -O- or -S-, and V ² is -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) _2- Or -SO ₂ -. The bonding positions for each ring of V ¹ and V ² , and the bonding positions for each ring of V ² and V ³ , are independently of each other, preferably a meta position or a para position with respect to each ring, more preferably It is a para position.

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

In a preferred embodiment of the present invention, at least a part of a plurality of X in formulas (1) and (2) is formula (4):

[Formula 8]

[In equation (4),

R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹⁰ to R ¹⁷ are, Independently of each other, they may be substituted with a halogen atom,

* Indicates a bond hand]

It is a structural unit represented by. When at least a part of a plurality of X in formulas (1) and (2) is a group represented by formula (4), it is easy to improve the abrasion resistance, 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 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and 1 to 6 carbon atoms. Represents an alkoxy group of or an aryl group having 6 to 12 carbon atoms. As a C1-C6 alkyl group, a C1-C6 alkoxy group, or a C6-C12 aryl group, the C1-C6 alkyl group, C1-C6 alkoxy group, or C6-C12 in Formula (3) The groups exemplified as the aryl group of are mentioned. R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R ¹⁰ to R ¹⁷ The hydrogen atoms contained may be independently of each other and substituted with a halogen atom. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example. R ¹⁰ to R ¹⁷ each independently represent a hydrogen atom, a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group from the viewpoint of abrasion resistance, elastic modulus, transparency, and bending resistance of the optical film. , Particularly preferably R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ represent a hydrogen atom, R ¹¹ and R ¹⁷ represent a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group. , Particularly preferably R ¹¹ and R ¹⁷ represent a methyl group or a trifluoromethyl group.

In a preferred embodiment of the present invention, the structural unit represented by formula (4) is formula (4'):

[Formula 9]

It is a structural unit represented by, that is, at least a part of a plurality of X among the plurality of structural units represented by formulas (1) and (2) is a structural unit represented by formula (4'). In this case, the solubility of the polyimide resin or polyamide resin in the solvent is increased by the skeleton containing the fluorine element, and the viscosity of the varnish is reduced while the storage stability of the varnish containing the resin is easily improved. It is easy to do, and it is easy to improve the workability of an optical film. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element.

In a preferred embodiment of the present invention, X in the polyimide resin or polyamide resin is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more. It is represented by formula (4), especially formula (4'). When X within the above range in a polyimide resin or polyamide resin is represented by formula (4), particularly formula (4'), the resulting optical film is in a resin solvent by a skeleton containing a fluorine element. It is easy to improve the solubility of the resin and improve the storage stability of the varnish containing the resin, it is easy to reduce the viscosity of the varnish, and the workability of the optical film is easily improved. Moreover, the optical properties of the optical film are also easily improved by the skeleton containing the fluorine element. Further, preferably, 100 mol% or less of X in the polyimide resin or polyamide resin is represented by formula (4), particularly formula (4'). X in the said resin may be Formula (4), especially Formula (4'). The ratio of the structural unit represented by the formula (4) of X in the resin can be measured using, for example, ¹ H-NMR, or can be calculated from the introduction ratio of the raw material.

In the formula (1), Y represents a tetravalent organic group, preferably a tetravalent organic group having 4 to 40 carbon atoms, more preferably a tetravalent organic group having a cyclic structure and having 4 to 40 carbon atoms. Examples of the cyclic structure include an alicyclic, aromatic ring, and heterocyclic structure, and preferably an aromatic ring is used from the viewpoint of easy to increase abrasion resistance and elastic modulus. The organic group is an organic group in which a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group, and in that case, the hydrocarbon group and the fluorine-substituted hydrocarbon group preferably have 1 to 8 carbon atoms. In one embodiment of the present invention, the polyimide 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 formula A group represented by (29); A group in which a hydrogen atom in the groups represented by the formulas (20) to (29) is substituted with a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group; And a tetravalent C6 or less chain hydrocarbon group.

[Formula 10]

In formulas (20) to (29), * represents a bond, and 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 arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, and a phenylene group is exemplified as a specific example.

Among the groups represented by formulas (20) to (29), from the viewpoint of being easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film, it is represented by formula (26), formula (28) or formula (29). A group is preferable, and a group represented by formula (26) is more preferable. In addition, W ¹ is independent of each other, preferably a single bond, -O-, from the viewpoint of being easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film and easy to reduce the YI value of the optical film. -CH ₂ -, -CH ₂ -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -, more preferably a single bond, -O-, -CH ₂ -, -CH(CH ₃ )-, -C(CH ₃ ) ₂ -or -C(CF ₃ ) ₂ -, more preferably a single bond, -C(CH ₃ ) ₂ -or -C( CF ₃ ) ₂ -.

In a preferred embodiment of the present invention, of Y in the polyimide-based resin, preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, by formula (26) Is shown. In the polyimide resin, Y within the above range is formula (26), preferably W ¹ is a single bond, -C (CH ₃ ) ₂ -or -C (CF ₃ ) _2- Preferably, when W ¹ is represented by a single bond or -C(CF ₃ ) ₂ -in Equation (26), it is easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film, while reducing the YI value of the optical film. easy to do. The ratio of the structural unit in which Y in the polyimide resin is represented by the formula (26) can be measured using, for example, ¹ H-NMR, or can be calculated from the introduction ratio of the raw material.

In a preferred embodiment of the present invention, at least a part of Y in a plurality of formulas (1) is formula (5):

[Formula 11]

[In equation (5),

R ¹⁸ to R ²⁵ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹⁸ to R ²⁵ are, Independently of each other, they may be substituted with a halogen atom,

* Indicates a bond hand]

And/or equation (9)

[Formula 12]

[In formula (9), R ³⁵ to R ⁴⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ³⁵ to R ⁴⁰ are each Independently, it may be substituted with a halogen atom, and * represents a bonding hand]

It is represented by When at least a part of Y in a plurality of formulas (1) is represented by formula (5) and/or is represented by formula (9), it is easy to improve the abrasion resistance, 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 are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and 1 to 6 carbon atoms. Represents an alkoxy group or an aryl group having 6 to 12 carbon atoms. As a C1-C6 alkyl group, a C1-C6 alkoxy group, or a C6-C12 aryl group, the C1-C6 alkyl group, C1-C6 alkoxy group, or C6-C12 in Formula (3) Examples of the aryl group of may include those exemplified above. R ¹⁸ to R ²⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R ¹⁸ to R ²⁵ The hydrogen atoms contained may be independently of each other and substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. R ¹⁸ to R ²⁵ are, independently of each other, more preferably from the viewpoint of easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint of being easy to increase transparency and easy to maintain the transparency. Is a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and even more preferably R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ and R ²⁵ are hydrogen atoms, R ²¹ and R ²² Is a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and particularly preferably R ²¹ and R ²² are a methyl group or a trifluoromethyl group.

In Formula (9), from the viewpoint of easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint that the transparency is easily increased and the transparency is easily maintained, R ³⁵ to R ⁴⁰ are, Preferably, a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and still more preferably a hydrogen atom. Here, the hydrogen atoms contained in R ³⁵ to R ⁴⁰ may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. have. Examples of the alkyl group having 1 to 6 carbon atoms and the aryl group having 6 to 12 carbon atoms in R ³⁵ to R ⁴⁰ are each exemplified above.

In a preferred embodiment of the present invention, formula (5) is represented by formula (5'), and formula (9) is formula (9'):

[Formula 13]

It is represented by That is, at least a part of a plurality of Ys is represented by formula (5') and/or formula (9'). In this case, it is easy to increase the abrasion resistance, elastic modulus, and bending resistance of the optical film. In addition, when the formula (5) is represented by the formula (5'), the solubility of the polyimide resin in the solvent is increased by the skeleton containing the fluorine element, and the storage stability of the varnish containing the resin is easily improved. In addition, the viscosity of the varnish is easily reduced, and the workability of the optical film is easily improved. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element.

In a preferred embodiment of the present invention, of Y in the polyimide resin, preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, formula (5), In particular, it is represented by formula (5'). When Y within the above range in the polyimide resin is represented by formula (5), particularly formula (5'), the solubility of the polyimide resin in the solvent is increased by the skeleton containing a fluorine element, and the resin is It is easy to reduce the viscosity of the varnish to be contained, and it is easy to improve the workability of the optical film. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element. Further, preferably, 100 mol% or less of Y in the polyimide resin is represented by formula (5), particularly formula (5'). Y in the polyimide resin may be a formula (5), particularly a formula (5'). The ratio of the structural unit represented by the formula (5) of Y in the polyimide resin can be measured using, for example, ¹ H-NMR, or can be calculated from the introduction ratio of the raw material.

In a preferred embodiment of the present invention, in the plurality of structural units represented by formula (1), Y is further added to the structural unit represented by formula (5), and Y is a structural unit represented by formula (9). It is preferable to include. When Y further contains the structural unit represented by Formula (9), it is easy to further improve the abrasion resistance and elastic modulus of an optical film.

The polyimide resin may contain a structural unit represented by formula (30) and/or a structural unit represented by formula (31), and may be represented by formula (1) and optionally formula (2). In addition to the structural unit, the structural unit represented by formula (30) and/or the structural unit represented by formula (31) may be included.

[Formula 14]

In formula (30), Y ¹ is a tetravalent organic group, and preferably, a hydrogen atom in the organic group is an organic group in which a hydrocarbon group or a fluorine-substituted hydrocarbon group may be substituted. As Y ^1, formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28), and formula ( 29), a group in which a hydrogen atom in the group represented by the formulas (20) to (29) is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and a tetravalent C6 or less A chain hydrocarbon group is illustrated. In one embodiment of the present invention, a polyimide-based resin may include a plurality of types of Y ^1, Y ¹ of a plurality of species may be the same or different from each other.

In formula (31), Y ² is a trivalent organic group, and preferably, a hydrogen atom in the organic group is an organic group in which a hydrocarbon group or a fluorine-substituted hydrocarbon group may be substituted. As Y ^{2, the} above formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and A group in which any one of the bond hands of the group represented by formula (29) is substituted with a hydrogen atom, and a trivalent chain hydrocarbon group having 6 or less carbon atoms are exemplified. In one embodiment of the present invention, a polyimide-based resin may include a plurality of types of Y ^2, Y ² is a plurality of types may be the same or different from each other.

In formulas (30) and (31), X ¹ and X ² are each independently a divalent organic group, and preferably a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group. As X ¹ and X ^{2, the} above formulas (10), (11), (12), (13), (14), (15), (16), (17), and ( A group represented by 18); A group in which a hydrogen atom in the groups represented by the formulas (10) to (18) is substituted with a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group; And a chain hydrocarbon group having 6 or less carbon atoms.

In one embodiment of the present invention, the polyimide resin is a structural unit represented by formula (1) and/or formula (2), and in some cases, a structural unit represented by formula (30) and/or formula (31). It consists of a constituent unit. In addition, from the viewpoint of being easy to increase the optical properties, abrasion resistance, elastic modulus, and bending resistance of the optical film, in the polyimide resin, the ratio of the structural units represented by formulas (1) and (2) is the formula (1) and formula (2), and in some cases, based on the total structural units represented by formulas (30) and (31), preferably 80 mol% or more, more preferably 90 mol% or more, further It is preferably 95 mol% or more. In addition, in the polyimide resin, the ratio of the structural units represented by formulas (1) and (2) is formula (1) and formula (2), and in some cases, formula (30) and/or formula ( It is usually 100% or less based on all the structural units represented by 31). In addition, the ratio can be measured using, for example, ¹ H-NMR, or can be calculated from the introduction ratio of raw materials.

In one embodiment of the present invention, the content of the polyimide resin and/or polyamide resin in the optical film is preferably 10 parts by mass or more, and more preferably 30 parts by mass per 100 parts by mass of the optical film. It is at least 50 parts by mass, more preferably at least 50 parts by mass, preferably at most 99.5 parts by mass, and more preferably at most 95 parts by mass. When the content of the polyimide resin and/or the polyamide resin is within the above range, it is easy to improve the optical properties, abrasion resistance, and elastic modulus of the optical film.

The weight average molecular weight (Mw) of the polyimide-based resin and the polyamide-based resin is in terms of standard polystyrene, preferably 200,000 or more, and more preferably from the viewpoint of easy to increase the abrasion resistance, elastic modulus, and flex resistance of the optical film. Is 230,000 or more, more preferably 250,000 or more, still more preferably 270,000 or more, and even more preferably 280,000 or more. In addition, the weight average molecular weight of the polyimide resin and the polyamide resin is preferably 1,000,000 from the viewpoint that the solubility of the resin in the solvent is easily improved and the stretchability and processability of the optical film are easily improved. Below, it is more preferably 800,000 or less, still more preferably 700,000 or less, and even more preferably 500,000 or less. The weight average molecular weight can be obtained by performing GPC measurement, for example, in terms of standard polystyrene, and may be calculated by, for example, a method described in Examples.

In the polyamideimide resin, the content of the structural unit represented by formula (2) is preferably 0.1 mol or more, more preferably 0.5 mol or more, per 1 mol of the structural unit represented by formula (1), It is more preferably 1.0 mol or more, even 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. When the content of the structural unit represented by Formula (2) is more than the above lower limit, it is easy to increase the abrasion resistance and elastic modulus of the optical film. Moreover, when the content of the structural unit represented by formula (2) is less than or equal to the above upper limit, thickening due to hydrogen bonds between amide bonds in formula (2) is suppressed, and workability of the optical film is easily improved.

In a preferred embodiment of the present invention, the polyimide resin and/or the polyamide resin contained in the optical film is, for example, a halogen atom such as a fluorine atom that can be introduced by the above fluorine-containing substituent. You may include. When the polyimide resin and/or the polyamide resin contains a halogen atom, it is easy to improve the elastic modulus of the optical film and to reduce the YI value. When the elastic modulus of the optical film is high, it is easy to improve the impact resistance of the film and it is easy to suppress the occurrence of scratches and wrinkles. Moreover, when the YI value of an optical film is low, it becomes easy to improve the transparency and visibility of this film. The halogen atom is preferably a fluorine atom. Preferred fluorine-containing substituents in order to contain a fluorine atom in the polyimide resin include, for example, a fluoro group and a trifluoromethyl group.

The content of halogen atoms in the polyimide resin and the polyamide resin is preferably 1 to 40 mass%, more preferably 5, based on the mass of the polyimide resin and the polyamide resin, respectively. It is -40 mass%, More preferably, it is 5-30 mass%. When the content of the halogen atom is more than the above lower limit, the elastic modulus of the optical film is further improved, the absorption rate is lowered, the YI value is further reduced, and transparency and visibility are more easily improved. When the content of the halogen atom is less than or equal to the above upper limit, it becomes easy to synthesize.

The imidation ratio of the polyimide resin and the polyamideimide resin is preferably 90% or more, more preferably 93% or more, and still more preferably 96% or more. It is preferable that the imidation ratio is more than the said lower limit from a viewpoint of being easy to improve the optical property of an optical film. Moreover, the upper limit of the imidation ratio is 100% or less. The imidation ratio represents the ratio of the molar amount of imide bonds in the polyimide resin to the value twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimide resin. In addition, when the polyimide resin contains a tricarboxylic acid compound, the value of twice the molar amount of the constituent unit derived from the tetracarboxylic acid compound in the polyimide resin and the constituent unit derived from the tricarboxylic acid compound The ratio of the molar amount of imide bonds in the polyimide-based resin to the sum of the molar amount is shown. Moreover, the imidation ratio can be calculated|required by IR method, NMR method, etc.

As the polyimide resin and the polyamide resin, a commercial item may be used. As a commercial item of a polyimide resin, Mitsubishi Gas Chemical Co., Ltd. Neopurim (registered trademark), Kawamura Industrial Co., Ltd. KPI-MX300F, etc. are mentioned, for example.

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

(Resin manufacturing method)

The polyimide resin and the polyimide precursor resin can be produced using, for example, a tetracarboxylic acid compound and a diamine compound as the main raw materials, and the polyamideimide resin and the polyamideimide precursor resin, for example , A tetracarboxylic acid compound, a dicarboxylic acid compound, and a diamine compound as main raw materials, and the polyamide-based resin can be manufactured, for example, using a diamine compound and a dicarboxylic acid compound as the main raw materials. Here, it is preferable that the dicarboxylic acid compound contains at least a compound represented by formula (3").

[Formula 15]

[In formula (3"),

R ¹ to R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and the hydrogen atoms contained in R ¹ to R ⁸ are , Independently of each other, may be substituted with a halogen atom,

A is 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 or a C 1 to C 12 monovalent hydrocarbon group which may be substituted by a halogen atom,

m is an integer from 0 to 4,

R ³¹ and R ³² are, independently of each other, a hydroxyl group, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group or a chlorine atom. Show.]

In a preferred embodiment of the present invention, the dicarboxylic acid compound is a compound represented by formula (3") in which m is 0. As a dicarboxylic acid compound, represented by formula (3") in which m is 0 In addition to the compound, it is more preferable to use a compound represented by the formula (3") in which A is an oxygen atom. Further, in another preferred embodiment, in the dicarboxylic acid compound, R ³¹ and R ³² are chlorine It is an atom, and is a compound represented by formula (3"). Moreover, you may use a diisocyanate compound instead of a diamine compound.

Examples of the diamine compound used in the production of the resin include aliphatic diamine, aromatic diamine, and mixtures thereof. In addition, in this embodiment, "aromatic diamine" represents a diamine in which an amino group is directly bonded to an aromatic ring, and an aliphatic group or other substituent may be included in a part of the structure. This aromatic ring may be a monocyclic ring or a condensed ring, and a benzene ring, a naphthalene ring, an anthracene ring, a fluorene ring, etc. are illustrated, but are not limited to these. Among these, preferably, it is a benzene ring. In addition, "aliphatic diamine" represents a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be included in a part of the structure.

Examples of aliphatic diamines include acyclic aliphatic diamines such as hexamethylenediamine, and 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine and 4, Cyclic aliphatic diamines, such as 4'-diaminodicyclohexylmethane, etc. are mentioned. These can be used alone or in combination of two or more.

As aromatic diamine, for example, p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2 Aromatic diamine having one aromatic ring, such as, 6-diaminonaphthalene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether , 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'- Diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis (4-(4-aminophenoxy)phenyl) sulfone, bis [4-(3-aminophenoxy)phenyl] sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl] Propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (sometimes described as TFMB), 4,4'-bis (4 -Aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(4-amino-3 And aromatic diamines having two or more aromatic rings such as -chlorophenyl)fluorene and 9,9-bis(4-amino-3-fluorophenyl)fluorene. These can be used alone or in combination of two or more.

Aromatic diamine is preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether , 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, bis (4-(4-aminophenoxy)phenyl] Sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy) ) Phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB), 4,4'-bis (4-aminophenoxy) Si) biphenyl, more preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diamino Diphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl] Propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB), 4,4'-bis (4-aminophenoxy) ratio It is phenyl. These can be used alone or in combination of two or more.

Among the diamine compounds, it is preferable to use at least one selected from the group consisting of aromatic diamines having a biphenyl structure from the viewpoint of high elastic modulus, high transparency, high flexibility, high bending resistance and low colorability of the optical film. Consisting of 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-bis(4-aminophenoxy)biphenyl and 4,4'-diaminodiphenyl ether It is more preferable to use one or more selected from the group, and even 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 acid dianhydride; And aliphatic tetracarboxylic acid compounds such as aliphatic tetracarboxylic acid dianhydride, and the like. Tetracarboxylic acid compounds may be used alone or in combination of two or more. In addition to dianhydride, the tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound.

Specific examples of the aromatic tetracarboxylic dianhydride include non-condensed polycyclic aromatic tetracarboxylic dianhydride, monocyclic aromatic tetracarboxylic dianhydride, and condensed polycyclic aromatic tetracarboxylic dianhydride. As non-condensed polycyclic aromatic tetracarboxylic dianhydride, for example, 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'-diphenylsulfonetetracarboxylic 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 dianhydride (6 FDA) ), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxy) Phenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane 2 Anhydride, 4,4'-(p-phenylenedioxy)diphthalic dianhydride, and 4,4'-(m-phenylenedioxy)diphthalic dianhydride. In addition, examples of monocyclic aromatic tetracarboxylic dianhydride include 1,2,4,5-benzenetetracarboxylic dianhydride, and examples of condensed polycyclic aromatic tetracarboxylic dianhydride include For example, 2,3,6,7-naphthalene tetracarboxylic dianhydride is mentioned.

Among these, preferably 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic acid Dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-di Phenylsulfonetetracarboxylic 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 dianhydride (6FDA), 1,2-bis(2,3-dicarboxyphenyl)ethane 2 anhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane 2 anhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane 2 anhydride, 1,1-bis(3,4-di Carboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic acid 2 Anhydride and 4,4'-(m-phenylenedioxy)diphthalic dianhydride, more preferably 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-biphenyl Tetracarboxylic 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.

As aliphatic tetracarboxylic dianhydride, a cyclic or acyclic aliphatic tetracarboxylic dianhydride can be mentioned. Cyclic aliphatic tetracarboxylic dianhydride is tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclo Cycloalkanetetracarboxylic dianhydride, such as butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, and bicyclo[2.2.2]oct-7-ene-2,3,5 ,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, and regioisomers thereof. These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, and 1,2,3,4-pentanetetracarboxylic dianhydride, and the like. Alternatively, it can be used in combination of two or more. Moreover, you may use combining cyclic aliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride.

Among the tetracarboxylic dianhydrides, 4,4'-oxydiphthalic dianhydride from the viewpoint of high abrasion resistance, high modulus of elasticity, high surface hardness, high transparency, high flexibility, high flexural resistance, and low colorability of the optical film. , 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetra Carboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 4,4'-(hexafluoro Loisopropylidene)diphthalic dianhydride, and mixtures thereof are preferred, and 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-(hexafluoroisopropylidene)di Phthalic dianhydride, and mixtures thereof are more preferred, and 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA) and 3,3',4,4'-biphenyltetracarboxylic acid 2 Anhydride (BPDA) is more preferred.

As the dicarboxylic acid compound used in the production of the resin, terephthalic acid, 4,4'-oxybisbenzoic acid, or their acid chloride compounds are preferably used. In addition to terephthalic acid, 4,4'-oxybisbenzoic acid or their acid chloride compounds, other dicarboxylic acid compounds may be used. Examples of other dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and their related acid chloride compounds, acid anhydrides, and the like, and may be used in combination of two or more. As a specific example, isophthalic acid; Naphthalenedicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; A dicarboxylic acid compound of a chain hydrocarbon having 8 or less carbon atoms and two benzoic acids are a single bond, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or a phenylene group. Linked compounds and their acid chloride compounds. As a specific example, 4,4'-oxybis (benzoyl chloride) and terephthaloyl chloride are preferable, and it is more preferable to use a combination of 4,4'-oxybis (benzoyl chloride) and terephthaloyl chloride.

In addition, the polyimide-based resin may be obtained by further reacting tetracarboxylic acid and tricarboxylic acid, and anhydrides and derivatives thereof, in addition to the tetracarboxylic acid compound, within a range that does not impair various physical properties of the optical film. .

Examples of the tetracarboxylic acid include a water adduct of the anhydride of the tetracarboxylic acid compound.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and related acid chloride compounds and acid anhydrides thereof, and may be used in combination of two or more. As a specific example, an anhydride of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; Phthalic anhydride and benzoic acid are linked by a single bond, -O-, -CH _2- , -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, or a phenylene group. .

In the production of the resin, the amount of the diamine compound, the tetracarboxylic acid compound and/or the dicarboxylic acid compound to be used can be appropriately selected according to the ratio of each structural unit of the desired 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, but, for example, 5 to 350°C, preferably 20 to 200°C, more preferably 25 It is -100°C. The reaction time is also not particularly limited, but is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be performed under an inert atmosphere or under reduced pressure conditions. In a preferred embodiment, the reaction is carried out while stirring under normal pressure and/or an inert gas atmosphere. Moreover, it is preferable to perform reaction in a solvent inert to reaction. The solvent is not particularly limited as long as it does not affect the reaction. For example, water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy- Alcohol solvents such as 2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, γ-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 ethylcyclohexane; Aromatic hydrocarbon solvents such as toluene and xylene; Nitrile solvents such as acetonitrile; Ether solvents such as tetrahydrofuran and dimethoxyethane; Chlorine-containing solvents such as chloroform and chlorobenzene; Amide solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; Carbonate solvents such as ethylene carbonate and propylene carbonate; And combinations thereof. Among these, from the viewpoint of solubility, an amide solvent can be suitably used.

In the imidation step in the production of a polyimide resin, imidization can be performed in the presence of an imidization catalyst. Examples of the imidation catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; Alicyclic amines (monocyclic) such as N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine; Alicyclic amines (polycyclic) such as azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2.2]nonane; And pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine , 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and aromatic amines such as isoquinoline. . Moreover, it is preferable to use an acid anhydride together with an imidation catalyst from a viewpoint of being easy to accelerate an imidation reaction. Examples of the acid anhydride include conventional acid anhydrides used in the imidation reaction, and specific examples thereof include aliphatic acid anhydrides such as acetic anhydride, propionic anhydride and butyric anhydride, and aromatic acid anhydrides such as phthalic acid.

Polyimide resins and polyamide resins are isolated by conventional methods, such as separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination of these. In a preferred embodiment, it can be isolated by adding a large amount of alcohol such as methanol to a reaction solution containing a transparent polyamide-imide resin, to precipitate the resin, and perform concentration, filtration, drying, or the like.

<Ingredients containing potassium>

The optical film of the present invention contains a potassium-containing component selected from the group consisting of a compound containing a potassium atom, potassium and potassium ions. The content of the potassium-containing component in the optical film of the present invention is the ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) obtained by time-of-flight secondary ion mass spectrometry (I _K /I _CH3 ) is not particularly limited as long as it is an amount equal to or greater than 0.2, and the ratio (I _K /I _CH3 ) may be set in a predetermined range according to the type of polyimide resin contained in the optical film. . For example, the content of the potassium-containing component in the varnish for producing the optical film of the present invention is a polyimide resin contained in the varnish and/or from the viewpoint of easy to increase the abrasion resistance and elastic modulus of the optical film. With respect to the total amount of the polyamide resin, preferably 0.002 mass% or more, more preferably 0.005 mass% or more, still more preferably 0.015 mass% or more, even more preferably 0.03 mass% or more, particularly preferably 0.05 It is mass% or more, and more particularly preferably 0.08 mass% or more. The upper limit of the content of the potassium-containing component in the varnish for producing the optical film of the present invention is to the total amount of the polyimide-based resin and/or polyamide-based resin contained in the varnish from the viewpoint of easy obtaining a homogeneous film. On the other hand, it is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, and even more preferably 0.2% by mass or less. In addition, the content of the potassium-containing component in the optical film of the present invention is the total amount of the polyimide-based resin and/or polyamide-based resin contained in the optical film from the viewpoint of easy to increase the abrasion resistance and elastic modulus of the optical film. With respect to, preferably 0.002% by mass or more, more preferably 0.005% by mass or more, still more preferably 0.015% by mass or more, even more preferably 0.03% by mass or more, particularly preferably 0.05% by mass or more, more particularly Preferably it is 0.08 mass% or more. The upper limit of the content of the potassium-containing component in the optical film of the present invention is preferably based on the total amount of the polyimide-based resin and/or polyamide-based resin contained in the optical film from the viewpoint of easy obtaining a homogeneous film. Is 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, and even more preferably 0.2% by mass or less. The content of the potassium-containing component relative to the total amount of the polyimide resin and/or polyamide resin contained in the optical film may be measured by a spectroscopic method such as an infrared absorption spectrum, or the varnish used when manufacturing the optical film. Content in is good also as content in an optical film. In addition, when a compound containing a potassium atom is used as the potassium-containing component, the compound may be decomposed in the process of producing an optical film within a range that does not impair the effects of the present invention.

The kind of the compound containing a potassium atom is not specifically limited. When producing an optical film using a resin composition (also referred to as ``varnish'') containing at least a polyimide resin and/or a polyamide resin and a solvent, the component is easily dissolved in the solvent of the varnish, and the component From the viewpoint of being easily contained in the optical film, the compound containing a potassium atom is preferably an organic potassium salt. Examples of the organic potassium salt include potassium alkoxide having 1 to 6 carbon atoms. In addition, the compound containing the potassium atom added to the resin composition does not need to be contained in the optical film of the present invention in the form of, for example, an organic potassium salt, and may be included in the resin composition. Other salts may be formed in the final optical film by hydrolysis with existing moisture or alcohol, ion exchange reactions with other salts, or the like, and may be contained as potassium or potassium ions.

<Additive>

The optical film of this invention may contain a filler. Examples of the filler include organic particles and inorganic particles, and preferably inorganic particles. As inorganic particles, metal oxide particles such as silica, zirconia, alumina, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, cerium oxide, and metal fluorides such as magnesium fluoride and potassium fluoride Particles and the like. The filler is preferably silica particles, zirconia particles, and alumina particles, and more preferably silica particles from the viewpoint of easy to increase the elastic modulus of the optical film and easy to improve the impact resistance of the optical film. These fillers can be used alone or in combination of two or more.

The average primary particle diameter of the filler, preferably silica particles, is 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, and even more preferably 20 nm or more. , Preferably 100 nm or less, more preferably 90 nm or less, still more preferably 80 nm or less, even more preferably 70 nm or less, particularly preferably 60 nm or less, more particularly preferably 50 nm or less, More preferably, it is 40 nm or less. When the average primary particle diameter of the silica particles is within the above range, it is easy to suppress aggregation of the silica particles and improve the optical properties of the resulting optical film. The average primary particle diameter of the filler can be measured by the BET method. Further, the average primary particle diameter may be measured by image analysis of a transmission electron microscope or a scanning electron microscope.

When the optical film of the present invention contains a filler, preferably silica particles, the content of the filler is usually 0.1 parts by mass or more, preferably 1 part by mass or more, more preferably 5 parts by mass, based on 100 parts by mass of the optical film. It is at least 10 parts by mass, more preferably at least 10 parts by mass, even more preferably at least 20 parts by mass, particularly preferably at least 30 parts by mass, and preferably at most 60 parts by mass. When the content of the filler is more than the above lower limit, it is easy to improve the elastic modulus of the obtained optical film. Moreover, when 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 commonly used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light with a wavelength of 400 nm or less. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of benzophenone compounds, salicylate compounds, benzotriazole compounds, and triazine compounds. The ultraviolet absorber may be used alone or in combination of two or more. When the optical film contains an ultraviolet absorber, deterioration of the resin is suppressed, and thus 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 to which the "system compound" is attached. For example, "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 is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, based on 100 parts by mass of the optical film. , Preferably it is 10 mass parts or less, More preferably, it is 8 mass parts or less, More preferably, it is 6 mass parts or less. The appropriate content varies depending on the ultraviolet absorber to be used, but when the content of the ultraviolet absorber is adjusted so that the light transmittance of 400 nm is about 20 to 60%, the light resistance of the optical film is improved and transparency is easily improved.

The optical film of the present invention may further contain other additives other than a filler and an ultraviolet absorber. Examples of other additives include antioxidants, mold release agents, stabilizers, bluing agents, flame retardants, pH adjusters, silica dispersants, lubricants, thickeners, and leveling agents. When other additives are contained, the content may be preferably 0.001 to 20 parts by mass, more preferably 0.01 to 15 parts by mass, and still more preferably 0.1 to 10 parts by mass per 100 parts by mass of the optical film. .

(Manufacturing method of optical film)

The manufacturing method of the optical film of the present invention is not particularly limited, but, for example, the following steps:

(a) at least one resin selected from the group consisting of the polyimide-based resin and polyamide-based resin, and at least one potassium-containing component selected from the group consisting of a compound containing a potassium atom, potassium and potassium ions And, the step of preparing a resin composition (hereinafter, also referred to as "varnish") containing at least a solvent (varnish preparation step),

(b) a process of forming a coating film by applying a varnish to a support material (application process), and

(c) Drying the applied liquid (coating film) to form an optical film (optical film forming process)

It may be a manufacturing method containing. The present invention comprises at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, a compound containing a potassium atom, potassium and potassium ions suitable for producing the optical film of the present invention. A resin composition containing at least one potassium-containing component selected from the group consisting of and a solvent is also provided.

In the varnish preparation process, at least one resin selected from the group consisting of polyimide resins and polyamide resins and potassium-containing components are dissolved in a solvent, and additives such as the above filler and ultraviolet absorber are added as necessary. Then, the varnish is prepared by stirring and mixing. In the case of using silica particles as a filler, a dispersion of silica sol containing silica particles is substituted with a solvent in which the resin is soluble, for example, a solvent used for preparing the following varnish. You may add it.

The potassium-containing component is not particularly limited as long as it is a component capable of containing at least one selected from the group consisting of a compound containing a potassium atom, potassium and potassium ions in the optical film of the present invention, but the component is a solvent of the varnish From the viewpoint that it is easy to dissolve in and the component is easily contained in the optical film, it is preferably a compound containing a potassium atom, and more preferably an organic potassium salt. Examples of the organic potassium salt include potassium alkoxide having 1 to 6 carbon atoms. The potassium-containing component to be contained in the varnish may be a single component or a combination of two or more components.

The content of the potassium-containing component contained in the resin composition is at least one selected from the group consisting of polyimide-based resins and polyamide-based resins contained in the resin composition from the viewpoint of easy to increase the abrasion resistance and elastic modulus of the optical film. With respect to the total amount of the resin, preferably 0.002% by mass or more, more preferably 0.005% by mass or more, still more preferably 0.015% by mass or more, even more preferably 0.03% by mass or more, particularly preferably 0.05% by mass The above, more particularly preferably 0.08% by mass or more. The upper limit of the content of the potassium-containing component in the resin composition of the present invention is at least 1 selected from the group consisting of polyimide-based resins and polyamide-based resins contained in the resin composition from the viewpoints of adjustability and film-forming properties of the varnish viscosity. It is preferably 1.0 mass% or less, more preferably 0.5 mass% or less, and still more preferably 0.1 mass% or less with respect to the total amount of the type of resin. When the content of the potassium-containing component is less than or equal to the above upper limit, the viscosity of the varnish does not become too high, and the resin solid content in the varnish is easily increased, so that the film-forming properties are easily improved.

The solvent used for preparing the varnish is not particularly limited as long as the resin can be dissolved. Examples of such a solvent include amide solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; lactone solvents such as γ-butyrolactone (GBL) and γ-valerolactone; Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; Carbonate solvents such as ethylene carbonate and propylene carbonate; And combinations thereof. Among these, amide solvents or lactone solvents are preferred. These solvents can be used alone or in combination of two or more. Among these, from the viewpoint of solubility, an amide solvent can be suitably used. Further, the varnish may contain water, an alcohol solvent, a ketone solvent, an acyclic ester solvent, an ether solvent, and the like. The solid content concentration of the varnish is preferably 1 to 25 mass%, more preferably 5 to 20 mass%, further preferably 5 to 15 mass%.

In the coating process, a varnish is applied on the support material by a known coating method to form a coating film. Known coating methods include, for example, wire bar coating, reverse coating, roll coating such as gravure coating, die coating, comma coating, lip coating, spin coating, screen coating, fountain coating, The dipping method, the spray method, the casting (流涎) molding method, etc. are mentioned.

In the film formation process, an optical film can be formed by drying the coating film and peeling it from the support material. After peeling, you may provide the process of drying an optical film further. Drying of the coating film can be performed usually at a temperature of 50 to 350°C. If necessary, the coating film may be dried under conditions of an inert atmosphere or reduced pressure.

Examples of the support material include a metal-based SUS plate, a resin-based PET film, a PEN film, a polyamide-based resin film, other polyimide-based resin films, cycloolefin-based polymer (COP) films, and acrylic films. Among them, from the viewpoint of excellent smoothness and heat resistance, a PET film, a COP film, and the like are preferable, and from the viewpoint of adhesion and cost with an optical film, a PET film is more preferable.

(Functional layer)

One or more functional layers may be laminated on at least one surface of the optical film of the present invention. Examples of the functional layer include an ultraviolet absorbing layer, a hard coating layer, a primer layer, a gas barrier layer, an adhesive layer, a color adjustment layer, and a refractive index adjustment layer. The functional layer can be used alone or in combination of two or more. When an optical film has the said functional layer, it is preferable to perform measurement by TOF-SIMS on the cross section of an optical film.

A hard coating layer may be provided on at least one surface of the optical film of the present invention. The thickness of the hard coating layer is not particularly limited, and may be, for example, 2 to 100 µm. When the thickness of the hard coat layer is within the above range, sufficient scratch resistance can be ensured, and the bending resistance is hardly lowered, and there is a tendency that the problem of curling due to cure shrinkage does not occur. The hard coating layer can be formed by curing a hard coating composition containing a reactive material capable of forming a crosslinked structure by irradiation with active energy rays or imparting thermal energy, and is preferably irradiated with active energy rays. Active energy rays are defined as energy rays capable of generating active species by decomposing compounds that generate active species, and include visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron rays. And, preferably, ultraviolet rays are used. The hard coating composition contains at least one polymer of a radical polymerizable compound and a cation polymerizable compound.

The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound may be a functional group capable of causing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specifically, a vinyl group, (meta) Acryloyl group, etc. are mentioned. Further, when the radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be the same or different, respectively. The number of radical polymerizable groups that the radical polymerizable compound has in one molecule is preferably 2 or more from the viewpoint of improving the hardness of the hard coat layer. As the radical polymerizable compound, a compound having a (meth)acryloyl group is preferably exemplified from the viewpoint of high reactivity, and specifically, it has 2 to 6 (meth)acryloyl groups in one molecule. Compounds called functional acrylate monomers or oligomers of hundreds to thousands of molecular weights having several (meth)acryloyl groups in a molecule called epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate And, preferably, one or more selected from epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate.

The cation polymerizable compound is a compound having a cation polymerizable group such as an epoxy group, an oxetanyl group, and a vinyl ether group. The number of cation polymerizable groups in one molecule of the cation polymerizable compound is preferably 2 or more, and more preferably 3 or more from the viewpoint of improving the hardness of the hard coat layer.

Further, as the cation polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cation polymerizable group is particularly preferable. Cyclic ether groups, such as an epoxy group and an oxetanyl group, are preferable in that the shrinkage due to the polymerization reaction is small. Further, the compound having an epoxy group among the cyclic ether groups has the advantage that it is easy to obtain compounds of various structures, does not adversely affect the durability of the obtained hard coating layer, and is easy to control compatibility with the radical polymerizable compound. In addition, the oxetanyl group among the cyclic ether groups tends to have a higher degree of polymerization compared to the epoxy group, and is less toxic, thereby speeding up the rate of network formation obtained from the cation polymerizable compound of the obtained hard coating layer, and even in a region mixed with the radical polymerizable compound. There is an advantage of forming an independent network without leaving unreacted monomers in the film.

As a cationic polymerizable compound having an epoxy group, for example, polyglycidyl ether of a polyhydric alcohol having an alicyclic ring or a cyclohexene ring or a cyclopentene ring-containing compound may be used as an epoxy agent using a suitable oxidizing agent such as hydrogen peroxide or peracid. Alicyclic epoxy resin obtained by converting; Aliphatic epoxy resins such as polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof, polyglycidyl ester of an aliphatic long-chain polybasic acid, homopolymer of glycidyl (meth)acrylate, and a copolymer; Glycidyl ether prepared by reaction of bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or derivatives such as alkylene oxide adducts and caprolactone adducts, and epichlorohydrin , And a glycidyl ether type epoxy resin derived from bisphenols, such as novolac epoxy resins.

The hard coating composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cation polymerization initiator, a radical and a cation polymerization initiator, and the like, and are appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cation to proceed radical polymerization and cation polymerization.

The radical polymerization initiator may be capable of releasing a substance that initiates radical polymerization by at least any of irradiation with active energy rays and heating. For example, examples of the thermal radical polymerization initiator include organic peroxides such as hydrogen peroxide and hyperbenzoic acid, and azo compounds such as azobisbutyronitrile.

As the active energy ray radical polymerization initiator, there are Type 1 type radical polymerization initiators that generate radicals by decomposition of molecules, and Type 2 type radical polymerization initiators that coexist with tertiary amines to generate radicals by hydrogen extraction type reaction, They are used alone or in combination.

The cation polymerization initiator may be capable of releasing a substance for initiating cation polymerization by at least any of irradiation with active energy rays and heating. As the cation polymerization initiator, an aromatic iodonium salt, an aromatic sulfonium salt, a cyclopentadienyl iron (II) complex, or the like can be used. These can initiate cation polymerization in any or any of irradiation with active energy rays or heating depending on the difference in structure.

The polymerization initiator may preferably contain 0.1 to 10 mass% with respect to the total 100 mass% of the hard coating composition. If the content of the polymerization initiator is in the above range, curing can be sufficiently advanced, and the mechanical properties and adhesion of the finally obtained coating film can be in a good range, and poor adhesion or cracking due to curing shrinkage and curling. There is a tendency that the phenomenon is less likely to occur.

The hard coating composition may further include one or more selected from the group consisting of solvents and additives.

The solvent is one capable of dissolving or dispersing the polymerizable compound and the polymerization initiator, and as long as it is a solvent known as a solvent for the hard coating composition in the art, it can be used within a range that does not impair the effects of the present invention.

The additive may further include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, antifouling agents, and the like.

The ultraviolet absorbing layer is a layer having a function of absorbing ultraviolet rays, and for example, a main material selected from an ultraviolet curable transparent resin, an electron beam curable transparent resin, and a thermosetting transparent resin, and dispersed in the main material. It consists of an ultraviolet absorber.

The adhesive layer is a layer having an adhesive function and has a function of adhering an optical film to other members. As the material for forming the adhesive layer, a commonly known material can be used. For example, a thermosetting resin composition or a photocurable resin composition can be used. In this case, the resin composition can be polymerized and cured by supplying energy afterwards.

The pressure-sensitive adhesive layer may be a layer that is referred to as a pressure sensitive adhesive (PSA) and adheres to the object by pressure. The pressure-sensitive adhesive may be a pressure-sensitive adhesive that is "a substance that has adhesiveness at room temperature and adheres to an adherend with light pressure" (JIS K 6800), or "a certain component is contained in a protective film (microcapsule), and An adhesive capable of maintaining stability until the film is destroyed by means (pressure, heat, etc.)" (JIS K 6800) may be a capsule adhesive.

The hue adjustment layer is a layer having a color adjustment function, and is a layer capable of adjusting a layered product including an optical film to a target hue. The hue adjustment layer is, for example, a layer containing a resin and a colorant. Examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, bengala, titanium oxide-based calcined pigments, ultramarine, cobalt aluminate, and carbon black; Organic pigments such as an azo compound, a quinacridone compound, an anthraquinone compound, a perylene compound, an isoindolinone compound, a phthalocyanine compound, a quinophthalone compound, a srene compound, and a diketopyrrolopyrrole compound; Extender pigments such as barium sulfate and calcium carbonate; And dyes such as basic dyes, acid dyes, and mordant dyes.

The refractive index adjusting layer is a layer having a function of adjusting the refractive index, for example, a layer having a refractive index different from that of an optical film and capable of imparting a predetermined refractive index to the optical laminate. The refractive index adjusting layer may be, for example, an appropriately selected resin and, if necessary, a resin layer containing a pigment further, or a thin metal film. As a pigment for adjusting the refractive index, silicon oxide, aluminum oxide, antimony oxide, tin oxide, titanium oxide, zirconium oxide, and tantalum oxide are mentioned, for example. The average primary particle diameter of the pigment may be 0.1 µm or less. By setting the average primary particle diameter of the pigment to 0.1 µm or less, diffuse reflection of light passing through the refractive index adjusting layer can be prevented, and a decrease in transparency can be prevented. Examples of the metal used in the refractive index adjustment layer include metal oxides such as titanium oxide, tantalum oxide, zirconium oxide, zinc oxide, tin oxide, silicon oxide, indium oxide, titanium oxynitride, titanium nitride, silicon oxynitride, and silicon nitride. And metal nitrides.

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

In a preferred embodiment of the present invention, the optical film of the present invention is very suitable as a front plate of an image display device, especially a front plate (window film) of a flexible display device, especially a front plate of a rollable display or a foldable display. useful. The flexible display device has, for example, a flexible functional layer and an optical film that is superimposed on the flexible functional layer and functions as a front plate. That is, the front plate of the flexible display device is disposed on the visible side on the flexible functional layer. This front plate has a function of protecting a flexible functional layer, for example, an image display element in a flexible display.

Examples of the image display device include a television, a smart phone, a mobile phone, a car navigation system, a tablet PC, a portable game machine, an electronic paper, an indicator, a bulletin board, a watch, and a wearable device such as a smart watch. As a flexible display device, all image display devices which have flexible characteristics are mentioned.

[Flexible display device]

The present invention also provides a flexible display device provided with the optical film of the present invention. The optical film of the present invention is preferably used as a front plate in a flexible display device, and the front plate is sometimes called a window film. The flexible display device is composed of a laminate for flexible display devices and an organic EL display panel, and a laminate for flexible display devices is disposed on the viewing side of the organic EL display panel and is bendable. The laminate for a flexible display device may contain the optical film (window film), circular polarizing plate, and touch sensor of the present invention, and the order of lamination thereof is arbitrary, but from the viewing side, the window film, circular polarizing plate, touch sensor, or window film , A touch sensor, and a circular polarizing plate are preferably stacked in this order. If the circular polarizing plate is present on the viewing side of the touch sensor, the pattern of the touch sensor is difficult to be recognized, and the visibility of the displayed image is improved, which is preferable. Each member may be laminated using an adhesive or an adhesive. In addition, a light shielding pattern formed on at least one surface of any layer of a window film, a circular polarizing plate, and a touch sensor may be provided.

[Polarizing plate]

The flexible display device of the present invention may further include a polarizing plate, preferably a circular polarizing plate. The circular polarizing plate is a functional layer having a function of transmitting only the right circularly polarized component or the left circularly polarized component by laminating a λ/4 retardation plate on the linear polarizing plate. For example, it is used for converting external light into right-circular polarized light and blocking external light that is reflected by an organic EL panel to become left-circularly polarized light, and by transmitting only the light-emitting component of the organic EL to suppress the influence of the reflected light to make an image easier to see. In order to achieve the circular polarization function, the absorption axis of the linear polarizing plate and the ground axis of the λ/4 retardation plate need to be 45° in theory, but are 45±10° in practical use. The linear polarizing plate and the λ/4 retardation plate do not necessarily need to be stacked adjacent to each other, and the relationship between the absorption axis and the slow axis may satisfy the above range. It is desirable to achieve complete circular polarization in all wavelengths, but practically, it is not necessary to do so, and thus the circular polarizing plate in the present invention also includes an elliptically polarizing plate. It is also preferable to laminate a λ/4 retardation film on the viewing side of the linear polarizing plate to make the outgoing light circularly polarized, thereby improving the visibility in the state of wearing polarized sunglasses.

The linear polarizing plate is a functional layer having a function of allowing light vibrating in a transmission axis direction to pass, but blocking polarization of a vibration component perpendicular thereto. The linear polarizing plate may be configured with a linear polarizer alone or a linear polarizer and a protective film attached to at least one surface thereof. The thickness of the linear polarizing plate may be 200 µm or less, and preferably 0.5 to 100 µm. When the thickness is in the above range, the flexibility tends to be difficult to decrease.

The linear polarizer may be a film-type polarizer manufactured by dyeing and stretching a polyvinyl alcohol (PVA)-based film. A dichroic dye is oriented to the PVA-based film oriented by stretching, or a dichroic dye such as iodine is adsorbed or stretched in a state adsorbed by PVA, thereby oriented and exhibiting polarization performance. In the production of the film-type polarizer, other steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be provided. The stretching or dyeing process may be performed by the PVA-based film alone, or may be performed in a state of being laminated with other films such as polyethylene terephthalate. The thickness of the PVA-based film to be used is preferably 10 to 100 µm, and the draw ratio is preferably 2 to 10 times.

Further, as another example of the polarizer, a liquid crystal coating type polarizer formed by applying 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 liquid crystal compound should have a property of showing a liquid crystal state, and particularly, if it has a high-order alignment state such as a smectic phase, it is preferable because it can exhibit high polarization performance. Moreover, it is also preferable that a liquid crystal compound has a polymerizable functional group.

The dichroic dye is a dye that is oriented together with the liquid crystal compound to exhibit dichroism, and the dichroic dye itself may have liquid crystal properties or may have a polymerizable functional group. Any compound in the liquid crystal polarizing composition has a polymerizable functional group.

The liquid crystal polarizing composition may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like.

The liquid crystal polarizing layer is produced by forming a liquid crystal polarizing layer by applying a liquid crystal polarizing composition on an alignment film.

The liquid crystal polarizing layer can be formed to have a thinner thickness compared to the film-type polarizer. The thickness of the liquid crystal polarizing layer may be preferably 0.5 to 10 µm, more preferably 1 to 5 µm.

The alignment layer can be produced, for example, by applying an alignment layer forming composition on a substrate and imparting alignment by rubbing, polarized light irradiation, or the like. In addition to the alignment agent, the alignment film forming composition may contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. As the aligning agent, for example, polyvinyl alcohol, polyacrylates, polyamic acids, and polyimides can be used. When applying photo-alignment, it is preferable to use an aligning agent containing a cinnamate group. The weight average molecular weight of the polymer used as the aligning agent may be about 10,000 to 1,000,000. The thickness of the alignment film is preferably 5 to 10,000 nm, more preferably 10 to 500 nm, from the viewpoint of alignment regulating force. The liquid crystal polarizing layer may be peeled off from the substrate and transferred to be laminated, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a transparent substrate for a protective film, a retardation plate, or a window film.

As the protective film, a transparent polymer film may be used. Specifically, as the polymer film to be used, a cycloolefin derivative having a monomer unit including polyethylene, polypropylene, polymethylpentene, norbornene or a cycloolefin, etc. (Modified) celluloses such as polyolefins, diacetylcellulose, triacetylcellulose, propionylcellulose, etc., acrylics such as methyl methacrylate (co)polymers, polystyrenes such as styrene (co)polymers, acrylonitrile/butadiene Styrene copolymers, acrylonitrile/styrene copolymers, ethylene-vinyl acetate copolymers, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyallylate Polyesters such as polyester, polyamides such as nylon, polyimides, polyamideimides, polyetherimides, polyethersulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, epoxy Films such as resins may be mentioned, and from the viewpoint of excellent transparency and heat resistance, preferably polyamide, polyamideimide, polyimide, polyester, olefin, acrylic, or cellulose-based films are used. These polymers may be used alone or in combination of two or more. These films are used unstretched or as a uniaxial or biaxially stretched film. A cellulose film, an olefin film, an acrylic film, and a polyester film are preferable. It may be a coating-type protective film obtained by coating and curing a cation curing composition such as an epoxy resin or a radical curing composition such as an acrylate. Plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments or dyes, fluorescent whitening agents, dispersants, thermal stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, solvents, etc. may be included as needed. The thickness of the protective film may be 200 µm or less, and preferably 1 to 100 µm. When the thickness of the protective film is in the above range, the flexibility of the protective film is difficult to decrease.

The λ/4 retardation plate is a film that imparts a phase difference of λ/4 in a direction orthogonal to the advancing direction of incident light, in other words, in the in-plane direction of the film. The λ/4 retardation plate may be a stretched retardation plate manufactured by stretching a polymer film such as a cellulose film, an olefin film, or a polycarbonate film. If necessary, a phase difference adjuster, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or dye, a fluorescent whitening agent, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, a solvent, etc. may be included. The thickness of the stretched retardation plate may be 200 μm or less, preferably 1 to 100 μm. When the thickness is in the above range, there is a tendency that the flexibility of the film is difficult to decrease.

Further, as another example of the λ/4 retardation plate, a liquid crystal coating type retardation plate formed by applying a liquid crystal composition may be used. The liquid crystal composition includes a liquid crystal compound having a liquid crystal state such as nematic, cholesteric, and smectic. Any of the compounds including the liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The liquid crystal coating type retardation plate may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be manufactured by forming a liquid crystal retardation layer by coating and curing a liquid crystal composition on an alignment film, similarly to the substrate in the liquid crystal polarizing layer. The liquid crystal coated retardation plate can be formed to have a thinner thickness compared to the stretched retardation plate. The thickness of the liquid crystal polarizing layer may be usually 0.5 to 10 µm, preferably 1 to 5 µm. The liquid crystal coating type retardation plate may be peeled off from the substrate and transferred to be laminated, or the substrate may be laminated as it is. It is also preferable that the substrate serves as a transparent substrate for a protective film, a retardation plate, or a window film.

In general, the shorter the wavelength, the greater the birefringence, and the longer the wavelength, the smaller the number of materials. In this case, since it is not possible to achieve a phase difference of λ/4 in the entire visible light region, the in-plane phase difference equal to λ/4 in the vicinity of 560 nm with high visibility, that is, 100 to 180 nm, preferably 130 to 150 It is often designed to be nm. It is preferable to use an inversely dispersed λ/4 retardation plate using a material having a birefringence wavelength dispersion characteristic opposite to that of usual, since it can improve visibility. As such a material, it is also preferable to use those described in Japanese Unexamined Patent Application Publication No. 2010-30979, such as in the case of an elongated retardation plate, and in the case of a liquid crystal coated retardation plate.

In addition, as another method, a technique for obtaining a broadband λ/4 retardation plate by combining with a lambda /2 retardation plate is also known (Japanese Laid-Open Patent Application Laid-Open No. 10-90521). The λ/2 retardation plate is also manufactured by the same material and method as the λ/4 retardation plate. Although the combination of the stretched retardation plate and the liquid crystal coated retardation plate is arbitrary, use of a liquid crystal coated retardation plate in either case is preferable because the thickness can be reduced.

In order to increase visibility in an oblique direction on the circular polarizing plate, a method of laminating a positive C plate is also known (Japanese Laid-Open Patent Publication No. 2014-224837). The positive C plate may also be a liquid crystal coating type retardation plate or a stretch type retardation plate. The retardation in the thickness direction is usually -200 to -20 nm, preferably -140 to -40 nm.

[Touch sensor]

The flexible display device of the present invention may further include a touch sensor. The touch sensor is used as an input means. As a touch sensor, various modes such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitance method have been proposed, and any method may be used. Among them, the electrostatic capacity method is preferable. The capacitive touch sensor is divided into an active area and an inactive area located on an outer portion of the active area. The active area is an area corresponding to an area (display unit) where a screen is displayed by the display panel, and is an area where a user's touch is sensed, and the inactive area corresponds to an area (non-display unit) where the screen is not displayed by the display device. Area. The touch sensor includes a substrate having a flexible characteristic; A sensing pattern formed in the active area of the substrate; Each sensing line may be formed in the non-active region of the substrate and connected to an external driving circuit through the sensing pattern and the pad part. As the substrate having flexible properties, the same material as the polymer film can be used. It is preferable that the substrate of the touch sensor has a toughness of 2,000 MPa% or more in terms of crack suppression of the touch sensor. More preferably, the toughness may be 2,000 to 30,000 MPa%. Here, toughness is defined as the lower area of the curve from the stress-strain curve (%) obtained through the tensile test of the polymer material to the point of failure.

The sensing pattern may include a first pattern formed in a first direction and a second pattern formed in a second direction. The first pattern and the second pattern are arranged in different directions. The first pattern and the second pattern are formed on the same layer, and in order to sense a touched point, each pattern must be electrically connected. In the first pattern, each unit pattern is connected to each other through a seam, but in the second pattern, since each unit pattern is separated from each other in an island shape, a separate bridge electrode is required to electrically connect the second pattern. need. As the sensing pattern, a known transparent electrode material can be applied. 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)), carbon nanotubes (CNT), graphene, metal wires, and the like, and these may be used alone or in combination of two or more. Preferably, ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, and chromium. These may be used alone or in combination of two or more.

The bridge electrode may be formed on the insulating layer by interposing an insulating layer on the sensing pattern, a bridge electrode may be formed on a substrate, and an insulating layer and a sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of them. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed in the structure of the layer covering the sensing pattern. In the latter case, the bridge electrode may connect the second pattern through a contact hole formed in the insulating layer. The touch sensor appropriately compensates for the difference in transmittance between the patterned area in which the pattern is formed and the non-patterned area in which the pattern is not formed, specifically, the difference in light transmittance caused by the difference in refractive index in these areas. An optical control layer may be further included between the substrate and the electrode as a means, and the optical control layer may include an inorganic insulating material or an organic insulating material. The optical control layer may be formed by coating a photocurable composition including a photocurable organic binder and a solvent on a substrate. The photocurable composition may further include inorganic particles. The refractive index of the optical control layer may be increased by the inorganic particles.

The photocurable organic binder may include, for example, a copolymer of each monomer such as an acrylate-based monomer, a styrene-based monomer, and a carboxylic acid-based monomer. The photocurable organic binder may be, for example, a copolymer containing different repeating units such as an epoxy group-containing repeating unit, an acrylate repeating unit, and a carboxylic acid repeating unit.

The inorganic particles may include, for example, zirconia particles, titania particles, alumina particles, and the like. The photocurable composition may further include additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

[Adhesive layer]

Each layer, such as a window film, a circular polarizing plate, and a touch sensor, forming the laminate for a flexible display device, and a film member such as a linear polarizing plate and a λ/4 retardation plate constituting each layer may be bonded with an adhesive. Examples of adhesives include water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent vaporizing adhesives, water-based solvent vaporizing adhesives, moisture curing adhesives, heat curing adhesives, anaerobic curing adhesives, active energy ray curing adhesives, curing agent mixture adhesives, A heat-melt adhesive, a pressure-sensitive adhesive (adhesive), a rewet-type adhesive, or the like can be used. Among them, water-based solvent volatilization type adhesives, active energy ray-curable adhesives, and pressure-sensitive adhesives are often used. The thickness of the adhesive layer can be appropriately adjusted depending on the required adhesive force, etc., and is, for example, 0.01 to 500 µm, preferably 0.1 to 300 µm. Although a plurality of adhesive layers may be present in the laminate for a flexible image display device, each thickness and the type of adhesive used may be the same or different.

As the aqueous solvent volatilization adhesive, a water-dispersed polymer such as polyvinyl alcohol-based polymer, water-soluble polymer such as starch, ethylene-vinyl acetate-based emulsion, and styrene-butadiene-based emulsion can be used as the main polymer. In addition to water and the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a dye, a pigment, an inorganic filler, an organic solvent, and the like may be blended. In the case of bonding with the water-based solvent vaporizing adhesive, the water-based solvent vaporizing adhesive may be injected between the adherend layers to bond the adhered layers, followed by drying to impart adhesiveness. In the case of using the water-based solvent volatilization type adhesive, the thickness of the adhesive layer may be 0.01 to 10 µm, preferably 0.1 to 1 µm. When the water-based solvent volatilization adhesive is used to form a plurality of layers, the thickness of each layer and the type of the adhesive may be the same or different.

The active energy ray-curable adhesive may be formed by curing an active energy ray-curable composition including a reactive material that forms an adhesive layer by irradiating with an active energy ray. The active energy ray-curable composition may contain at least one polymer of a radical polymerizable compound and a cation polymerizable compound similar to the hard coating composition. The radical polymerizable compound is the same as the hard coating composition, and the same type of the hard coating composition can be used. The radical polymerizable compound used for the adhesive layer is preferably a compound having an acryloyl group. It is also preferable to include a monofunctional compound in order to lower the viscosity as an adhesive composition.

The cation polymerizable compound is the same as the hard coating composition, and the same type of the hard coating composition can be used. As the cationic polymerizable compound used in the active energy ray curing composition, an epoxy compound is particularly preferable. It is also preferable to include a monofunctional compound as a reactive diluent in order to lower the viscosity of the adhesive composition.

The active energy ray composition may further include a polymerization initiator. Examples of the polymerization initiator include a radical polymerization initiator, a cation polymerization initiator, a radical and a cation polymerization initiator, and the like, and may be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cation to proceed radical polymerization and cation polymerization. Among the substrates of the hard coating composition, an initiator capable of initiating at least either radical polymerization or cationic polymerization by irradiation with active energy rays can be used.

The active energy ray curing composition may further include an ion trapping agent, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, an antifoaming agent, an additive, and a solvent. In the case of bonding with the active energy ray-curable adhesive, the active energy ray-curable composition is applied to any or both of the adhered layer and then bonded, and the active energy ray is irradiated by passing through any or both adhered layers. It can be bonded by curing. When using the active energy ray-curable adhesive, the thickness of the adhesive layer may be usually 0.01 to 20 µm, preferably 0.1 to 10 µm. When the active energy ray-curable adhesive is used to form a plurality of layers, the thickness of each layer and the type of adhesive used may be the same or different.

As the pressure-sensitive adhesive, it is classified into an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and the like, depending on the main polymer. In addition to the main polymer, a crosslinking agent, a silane compound, an ionic compound, a crosslinking catalyst, an antioxidant, a tackifier, a plasticizer, a dye, a pigment, an inorganic filler, and the like may be blended in the pressure-sensitive adhesive. Each component constituting the pressure-sensitive adhesive is dissolved and dispersed in a solvent to obtain a pressure-sensitive adhesive composition, and the pressure-sensitive adhesive composition is applied on a substrate and then dried to form an adhesive layer (adhesive layer). The adhesive layer may be formed directly or may be transferred to a separate substrate. It is also preferable to use a release film in order to cover the adhesive surface before adhesion. In the case of using the pressure-sensitive adhesive, the thickness of the adhesive layer may be usually 1 to 500 µm, preferably 2 to 300 µm. When the pressure-sensitive adhesive is used to form a plurality of layers, the thickness of each layer and the type of the pressure-sensitive adhesive used may be the same or different.

[Shading pattern]

The light blocking pattern may be applied as at least a part of a bezel or a housing of the flexible image display device. The light-shielding pattern hides the wiring arranged at the marginal portion of the flexible image display device and makes it difficult to recognize the image, thereby improving the visibility of the image. The shading pattern may be in the form of a single layer or a multilayer. The color of the shading pattern is not particularly limited, and may have various colors such as black, white, and metallic colors. The shading pattern may be formed of a pigment for realizing color and a polymer such as acrylic resin, ester resin, epoxy resin, polyurethane, and silicone. These may be used alone or in a mixture of two or more. The shading pattern may be formed by various methods such as printing, lithography, and inkjet. The thickness of the shading pattern is usually 1 to 100 µm, preferably 2 to 50 µm. Moreover, it is also preferable to provide a shape such as an inclination in the thickness direction of the light shielding pattern.

[Example]

Hereinafter, the present invention will be described in more detail by examples. "%" and "parts" in the examples mean mass% and mass parts, respectively, unless otherwise specified. First, a method of measuring physical property values will be described for the first time.

(Measurement of weight average molecular weight (Mw))

The weight average molecular weight of the resin was measured using gel permeation chromatography (GPC). The preparation method and measurement conditions of the measurement sample are as follows.

(1) Sample preparation method

20 mg of the resin was measured and added, 10 mL of DMF (10 mmol lithium bromide) was added, and completely dissolved. This solution was filtered through a chromatographic disk (pore diameter of 0.45 µm) to obtain a sample solution.

(2) Measurement conditions

Device: HLC-8020GPC

Column: Guard column + TSKgelα-M (300 mm x 7.8 mm diameter) x 2 +α-2500 (300 mm x 7.8 mm diameter) x 1

Eluent: DMF (10 mmol of lithium bromide added)

Flow: 1.0 mL/min

Detector: RI detector

Column temperature: 40℃

Injection volume: 100 μL

Molecular weight standard: standard polystyrene

(Abrasion test)

The abrasion test was performed using a steel wool tester (manufactured by Daiei Science & Technology Co., Ltd.). A specific test method will be described with reference to FIGS. 1 to 3. First, the optical film test sample 3 shown in FIG. 1 was created. Specifically, a 4.5 cm x 9 cm optical film 1 was placed on a 9 cm x 9 cm glass plate 31, and a tape 32 (manufactured by 3M Company, Scotch (registered trademark) tape) was used as an optical film. (1) was fixed so as to be in close contact with the glass plate 31. Here, a 1 cm x 1 cm square marking 33 for indicating the observation position was described in the center of the surface of the glass plate 31 on the opposite side to the mounting surface of the optical film 1 with a sign pen. Next, the film test sample 4 shown in FIG. 2 was created. In FIG. 2, a top view and a side view of the film test sample 4 are shown. As the film 2 in Fig. 2, a film of 2.5 cm x 2.5 cm (Unipack (registered trademark) manufactured by Japan Co., Ltd., a polyethylene (PE) film having a thickness of 0.08 mm) was used, and the film was formed on a glass plate. It affixed to (41) with double-sided tape 421. In addition, a double-sided tape 422 for fixing the film test sample 4 to the bottom surface of the weight 51 in FIG. 3 on the side opposite to the mounting surface of the film 2 of the glass plate 41 is also provided. Attached.

The optical film test sample 3 produced as described above was fixed to the measuring table 52 of the measuring device so that the optical film 1 became the upper surface, as shown in FIG. 3. Next, the film test sample 4 was affixed to the bottom surface of the weight 51 (500 g) so that the film 2 is the lower surface, and the optical film 1 and the film 2 were loaded with a load of 500 gf. To make contact. The weights 51 to which the film test sample 4 was attached were rubbed against each other at a speed of 1 reciprocation/second in the direction of the arrow in FIG. 3. In addition, the direction of the arrow in FIG. 3 corresponds to the direction of the arrow in FIG. 1, and the movement distance of one reciprocation was 5 cm. Every 100 round trips, by using an optical microscope (manufactured by Giens Co., Ltd., VHX-2000), at a magnification of 30 times, the inside of the marking 33 on the optical film was observed, and the presence or absence of a scratch was confirmed, and the following 1 to It evaluated by the evaluation criteria of 5, 4 and 5 were said to be good, and the evaluation of 3 or less was said to be poor.

(Abrasion evaluation)

5: No scratches were observed after 500 round trips.

4: After 400 round trips, no scratches were confirmed, but after 500 round trips, scratches were confirmed.

3: After 300 round trips, no scratch was confirmed, but after 400 round trips, scratch was confirmed.

2: After 200 round trips, no scratches are found, but after 300 round trips, scratches are confirmed.

1: After 100 round trips, scratches are not confirmed, but after 200 round trips, scratches are confirmed.

0: A scratch is confirmed after 100 round trips.

(Measurement of total light transmittance)

The total light transmittance of the optical film was measured by a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Testing Instruments Co., Ltd. in accordance with JIS K 7105:1981.

(Measurement of haze)

The haze of the optical film was measured by a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Testing Instruments Co., Ltd. in accordance with JIS K 7105:1981.

(Measurement of modulus of elasticity)

The optical films obtained in Examples and Comparative Examples were cut into a 10 mm×100 mm long rectangular shape using a dumbbell cutter to obtain a test sample. The elastic modulus of this test sample was measured by measuring the stress-strain curve (SS curve) under conditions of a distance between chuck of 50 mm and a tensile speed of 10 mm/min using Autograph AG-IS manufactured by Shimadzu Corporation. The elastic modulus (GPa) of the optical film was calculated from the inclination in 5 to 20 MPa.

(Measurement of thickness)

For the optical films obtained in Examples and Comparative Examples, the thickness of the optical film was measured using an ABS Digimatic Indicator (manufactured by Mitsutoyo Co., Ltd., "ID-C112BS").

(Measurement of time-of-flight secondary ion mass spectrometry (TOF-SIMS))

Using "Ultra Microtome EM UC6" manufactured by Leica Microsystems Co., Ltd., a cross section of an optical film was produced.

The cross section of the produced resin film was analyzed by TOF-SIMS. The TOF-SIMS device and measurement conditions used for analysis are as follows.

(1) Device: ION-TOF's "TOF. SIMS V」

(2) Primary ion: Bi ³⁺⁺

(3) Acceleration voltage of primary ions: 25 kV

(4) Irradiation ion current: 0.23 ㎀

(5) Measurement conditions: In bunching (high mass resolution) mode, positive and negative ions are measured.

(6) Measurement range: 200 μm×200 μm

The TOF-SIMS data was analyzed using SurfaceLab. Mass calibration of the measurement data was performed, and the integral value of the peak was calculated for each of the peaks attributed to K ions and CH ₃ ions. The ratio (I _K /I _CH3 ) was calculated by using the integral value of the peak of K ions as the ionic strength of _K (I _K ) and the integrated value of the peak of CH ₃ ions as the ionic strength of CH ₃ (I _CH3 ).

(Measurement of viscosity)

The viscosity of the resin composition was measured under the following conditions.

Device name: LVDV-II+Pro (manufactured by Brookfield)

Measurement temperature: 25℃

Spindle: CPE-52

Sample volume: 0.8 mL

Rotor rotation speed: 3 rpm

[Synthesis Example 1: Preparation of polyamideimide resin (1)]

Nitrogen was conducted to a reaction vessel equipped with a sufficiently dried stirrer and thermometer, and the inside of the vessel was replaced with nitrogen. In this reaction vessel, 1907.2 parts by mass of dimethylacetamide (DMAc) was put, and 111.94 parts by mass of 2,2′-bis(trifluoromethyl)benzidine (TFMB) and 4,4′-(hexafluoroisopropylidene) di It was reacted by adding 46.84 parts by mass of phthalic acid dianhydride (6FDA).

Then, 10.37 parts by mass of 4,4'-oxybis(benzoyl chloride) (OBBC) and 42.79 parts by mass of terephthaloyl chloride (TPC) were added and reacted.

Subsequently, 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, the reaction vessel was heated to 70° C., and stirred for an additional 3 hours to obtain a reaction solution.

The reaction solution was cooled, 3794.5 parts by mass of methanol was added, and then 1419.4 parts by mass of ion-exchanged water was added dropwise to precipitate a white solid. The precipitated white solid was collected by centrifugal filtration and washed with methanol to obtain a wet cake containing a polyamideimide resin. The obtained wet cake was dried at 78° C. under reduced pressure to obtain a powder of a polyamideimide resin. The weight average molecular weight of the obtained polyamideimide resin (1) was 466,000.

[Synthesis Example 2: Preparation of polyamideimide resin (2)]

Nitrogen was conducted to a reaction vessel equipped with a sufficiently dried stirrer and thermometer, and the inside of the vessel was replaced with nitrogen. To the reaction vessel, 250.00 parts by mass of DMAc and 14.64 parts by mass of TFMB were added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 6.15 parts by mass of 6 FDA and 1.36 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added, followed by stirring at room temperature for 16 hours. Then, 2.53 parts by mass of TPC was added and stirred for 10 minutes, and then 2.53 parts by mass of TPC were further added and stirred for 20 minutes. After adding 250.00 parts by mass of DMAc and stirring for 10 minutes, 0.56 parts by mass of TPC was further added, followed by stirring at room temperature for 2 hours.

Next, 2.58 parts by mass of 4-picoline and 13.20 parts by mass of acetic anhydride were added to the flask, and after stirring at room temperature for 30 minutes, the reaction vessel was heated to 70° C. and stirred for an additional 3 hours to obtain a reaction solution.

The reaction solution was cooled, and 888 parts by mass of methanol was added at the point where it went down to 40°C or less, and then 344 parts by mass of ion-exchanged water was added dropwise thereto to precipitate a white solid. The precipitated white solid was collected by filtration under reduced pressure and washed with methanol to obtain a wet cake containing a polyamideimide resin. The obtained wet cake was dried at 75°C under reduced pressure to obtain a powder of a polyamideimide resin. The weight average molecular weight of the obtained polyamideimide resin (2) was 290,000.

[Preparation of t-BuOK solution]

A THF solution of t-BuOK (Wako Pure Chemical Industries, Ltd.) containing 1 mol% of potassium t-butoxide (a compound containing a potassium atom hereinafter also referred to as ``t-BuOK'') as a potassium-containing component Agent) was diluted with DMAc, and a solution containing t-BuOK at a concentration of 0.2% by mass (hereinafter also referred to as "t-BuOK solution") was prepared.

[Example 1]

The polyamideimide resin (1), DMAc, and the t-BuOK solution prepared as described above were obtained in Synthesis Example 1, wherein the content ratio of the polyamideimide resin in the resin composition was 9.0% by mass, and t-BuOK was contained. The mixture was mixed in an amount such that the ratio was 0.01% by mass to prepare a polyamideimide resin composition (varnish for film formation). The obtained resin composition was applied using an applicator so that the thickness of the self-supporting film was 55 µm on the smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., brand name "A4100"), and then at 50°C for 30 minutes, then 140°C After drying for 15 minutes, the obtained coating film was peeled from the polyester substrate to obtain a self-supporting film. The self-supporting film was fixed to a metal frame, and further dried at 200°C for 40 minutes under air to obtain a polyamideimide resin film (1) having a thickness of 50 μm.

[Example 2]

The polyamideimide resin (1), DMAc, and the t-BuOK solution prepared as described above were obtained in Synthesis Example 1, wherein the content ratio of the polyamideimide resin in the resin composition was 9.0% by mass, and t-BuOK was contained. The mixture was mixed in an amount of 0.1% by mass to prepare a polyamide-imide resin composition. Except having used the resin composition obtained in this way, it carried out similarly to Example 1, and obtained the polyamide-imide resin film (2) which has a thickness of 50 micrometers.

[Example 3]

The polyamideimide resin (2) obtained in Synthesis Example 2, DMAc, and the t-BuOK solution prepared as described above, the content ratio of the polyamideimide resin in the resin composition is 10.8 mass%, and the content of t-BuOK The mixture was mixed in an amount of 0.1% by mass to prepare a polyamide-imide resin composition. Except having used the thus obtained resin composition, it carried out similarly to Example 1, and obtained the polyamideimide resin film (3) which has a thickness of 50 micrometers.

[Comparative Example 1]

The polyamideimide resin (1) and DMAc obtained in Synthesis Example 1 were mixed in an amount such that the content ratio of the polyamideimide resin in the resin composition was 9.0% by mass, to prepare a polyamideimide resin composition. Except having used the resin composition obtained in this way, it carried out similarly to Example 1, and obtained the polyamide-imide resin film (4) which has a thickness of 50 micrometers.

Table 1 shows the results of measuring various physical properties of the polyamideimide resin films (1) to (4) obtained in Examples 1 to 3 and Comparative Example 1.

[Examples 4 and 5]

The polyamideimide resin (1), DMAc, and the t-BuOK solution prepared as described above were obtained in Synthesis Example 1, wherein the content ratio of the polyamideimide resin in the resin composition was 9.0% by mass, and t-BuOK was contained. The mixture was mixed in an amount of 0.2% by mass (Example 4) or 1% by mass (Example 5) to prepare a polyamideimide resin composition.

For each of the polyamideimide resin compositions obtained in Examples 1, 2, 4 and 5, and Comparative Example 1, the viscosity was measured according to the above measurement method. Table 2 shows the obtained results.

As shown in Table 1, the optical films of Examples 1 to 3 in which t-BuOK was added to the varnish and the ionic strength ratio (I _K / I _{CH 3} ) by TOF-SIMS was 0.2 or more had a high elastic modulus, In addition, it was confirmed that the abrasion resistance was excellent. On the other hand, in the case of the optical film of Comparative Example 1 in which t-BuOK was not added to the varnish, sufficient abrasion resistance and elastic modulus were not obtained. Moreover, as shown in Table 2, it was confirmed that the viscosity of the resin composition tends to increase by adding a potassium-containing component to the resin composition. The cause of the increase in the viscosity of the resin composition by adding the potassium-containing component is not clear, but functional groups in the resin, such as imide bonds and/or amide bonds, and potassium-containing components (compounds containing potassium atoms, potassium and / Or potassium ion) and some kind of interaction is expected to occur. It is thought that the improvement of the abrasion resistance and the elasticity modulus of the obtained optical film are brought about by such an interaction, but the said consideration does not limit this invention at all.

1: optical film
2: film
3: Optical film test sample
31: glass plate
32: tape
33: marking
4: Film test sample
41: glass plate
421: double-sided tape
422: double sided tape
51: pendulum
52: measuring table

Claims (13)

An optical film comprising at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, the ionic strength of CH ₃ obtained by the time-of-flight secondary ion mass spectrometry of the optical film (I _CH3 The ratio of the ionic strength (I _K ) of _{K to} ) (I _K /I _CH3 ) is 0.2 or more. The method of claim 1,
An optical film in which the polyimide resin and the polyamide resin are aromatic resins. The method of claim 1,
An optical film in which the ratio of the structural units derived from the aromatic monomer to all the structural units in the polyimide resin and the polyamide resin is 60 mol% or more. The method of claim 1,
An optical film having a thickness of 10 to 100 µm and a total light transmittance of 80% or more. The method of claim 1,
An optical film having a weight average molecular weight of 200,000 or more of a polyimide-based resin and a polyamide-based resin. The method of claim 1,
The polyimide resin is an optical film which is a polyamideimide resin. The method of claim 1,
An optical film in which the polyimide resin and the polyamide resin contain structural units derived from terephthalic acid. The method of claim 1,
An optical film having an elastic modulus of 5.0 GPa or more. The method of claim 1,
An optical film which is a film for a front plate of a flexible display device. A flexible display device comprising the optical film according to any one of claims 1 to 9. The method of claim 10,
A flexible display device further comprising a touch sensor. The method of claim 10,
A flexible display device further comprising a polarizing plate. At least one resin selected from the group consisting of polyimide resins and polyamide resins, a compound containing potassium atoms, at least one potassium containing component selected from the group consisting of potassium and potassium ions, and a solvent A resin composition containing at least.

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