KR20210002016A - Optical film, flexible display device and method for producing optical film - Google Patents

Abstract

The present invention relates to a resin film having high impact resistance. The present invention provides an optical film including at least one resin selected from the group consisting of polyimide resins and polyamide resins, wherein the ratio (I_Na / I_CH3) of the ionic strength (I_Na) of Na to the ionic strength (I_CH3) of CH_3 is 0.2 or more, and the ratio (I_K / I_CH3) of the ionic strength (I_K) of K to the ionic strength (I_CH3) of CH_3 is 0.2 or more, as determined by the time-of-flight secondary ion mass spectrometry of the corresponding optical film.

Description

An optical film, a flexible display device, and a manufacturing method of an optical film TECHNICAL FIELD [OPTICAL FILM, FLEXIBLE DISPLAY DEVICE AND METHOD FOR PRODUCING OPTICAL FILM]

The present invention relates to an optical film, a flexible display device, and a method of manufacturing an optical film.

Currently, image display devices such as a liquid crystal display device and an organic EL display device are widely used in various applications such as mobile phones and smart watches. Although glass has been used as the front plate of such an image display device, since glass is very rigid and fragile, it is difficult to use it as a front plate material for, for example, 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

However, according to the research of the present inventors, the optical film used as the front plate material of such a flexible display device is directly touched by the user or the surrounding objects collide, so if the contact or collision is repeatedly performed, the surface It has been found that there are cases in which scratches such as dents are generated, and optical properties and visibility are deteriorated.

Therefore, it is an object of the present invention to provide an optical film excellent in impact resistance and a flexible display device including the optical film, which can suppress a decrease in optical properties and visibility due to repeated object collisions.

In order to solve the said subject, the present inventors paid attention to the kind and quantity of the component contained in a resin film, and performed a thorough examination. As a result, the ratio of the ionic strength of _Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) obtained by the time-of-flight secondary ion mass spectrometry in the optical film (I _Na / I _CH3 ) was 0.2 or more and, also, when the ratio of the ionic strength (I _K) of K for the ionic strength (I _CH3) of _{CH 3 (I K / I CH3} ) is 0.2 or more, surprisingly discovered that easy to increase the impact resistance of the optical film , Came to complete the present invention.

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

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

[2] The optical film according to [1], wherein the polyimide resin and the polyamide 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-based resin and the polyamide-based 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-based resin and the polyamide-based resin contain a structural unit derived from terephthalic acid.

[8] The optical film according to any one of [1] to [7], wherein the optical film has a brightness (L ^* ) of 90 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) (a) At least one resin selected from the group consisting of polyimide resins and polyamide resins, at least one sodium-containing component, at least one potassium-containing component, and at least a solvent. A step of preparing a resin composition, wherein the sodium-containing component is selected from the group consisting of a compound containing a sodium atom, sodium and sodium ions, and the potassium-containing component is a compound containing a potassium atom, potassium and Is selected from the group consisting of potassium ions,

(b) forming a coating film by applying the resin composition to a support material, and

(c) drying the coating film to form an optical film

The method for producing an optical film according to any one of the above [1] to [9], including at least.

According to the present invention, an optical film excellent in impact resistance can be provided.

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 _Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) is 0.2 or more, and furthermore, the ionic strength of CH ₃ (I _CH3 ) The ratio of the ionic strength of _{K to} (I _K ) (I _K /I _CH3 ) is 0.2 or more.

In the optical film of the present invention, the K for the ratio (I _Na / I _CH3) and ionic strength (I _CH3) of CH ₃ of the ionic strength (I _Na) of Na on the ionic strength (I _CH3) in CH ₃ The ratio of the ionic strength (I _K ) (I _K /I _CH3 ) is determined by the time-of-flight secondary ion mass spectrometry (Time-of-Flight Secondary Ion Mass Spectrometry: also referred to herein as ``TOF-SIMS''). , It is calculated by measuring the ionic strength of CH ₃ (I _CH3 ), the ionic strength of _Na (I _Na ) and the ionic strength of _K (I _K ) of the optical film, and dividing each of I _Na and I _K by I _{CH 3} . In addition, in this specification, the ionic strength of CH ₃ (I _CH3 ) measured by the time-of-flight secondary ion mass spectrometry is the integral value of the peak attributable to the CH ₃ ion in the measurement data, and the Na ion Intensity (I _Na ) is an integral value of a peak attributable to Na ions in the measurement data, and K ionic strength (I _K ) is an integral value of a peak attributable to K ions in measurement data.

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 in which a sample is irradiated with an ion beam (primary ions) in a high vacuum, and ions emitted from the surface are subjected to mass separation using the difference in flight time. When primary ions are irradiated, positive or negatively charged ions (secondary ions) are released from the sample surface. Lighter ions fly faster and heavier ions fly slower, so when secondary ions are generated and then detected. By measuring the time to (flight time), the mass of the generated secondary ions can be calculated.

In the measurement by TOF-SIMS, CH ₃ ions were detected at a mass of around 15.02u, Na ions were detected at a mass of around 22.99u, and K ions were detected at a mass of around 38.96u. In addition, such ions are ions that are detected in either positive (positive) ion analysis and negative (negative) ion analysis. In the present invention, the ratio of the ionic strength of _Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ), and the ion of K to the ionic strength of CH ₃ (I _CH3 ) The ratio of the intensity (I _K ) (I _K /I _CH3 ) may be a ratio detected by a cation analysis or a ratio detected by an anion analysis. If at least one ratio of the ratio detected by cation analysis and the ratio detected by anion analysis with respect to the ratio in the present invention (I _Na / I _CH3 ) is 0.2 or more, the ratio in the present invention (I _Na / I _It satisfies the requirement that _CH3 ) is 0.2 or more. In addition, if at least one ratio of the ratio detected by cation analysis and the ratio detected by anion analysis is 0.2 or more with respect to the ratio in the present invention (I _K / I _CH3 ), the ratio in the present invention (I _K /I _CH3 ) satisfies the requirement of 0.2 or more. From the viewpoint of obtaining higher detection sensitivity, conditions using cation 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 primary ion acceleration voltage was 25 kV, and the irradiated ion current was 0.23 pA. , In the condition that the measurement range is 200 µm × 200 µm, it can be carried out by cation analysis or anion analysis. Measurement by TOF-SIMS can be performed according to the method described in Examples, for example. The ratio (I _Na /I _CH3 ) and the ratio (I _K /I _CH3 ) measured for at least a portion of the surface or cross-section of the optical film should be within the above range, but the composition inside the optical film depends on the mechanical strength of the optical film. From the point that it is assumed that it is more likely to have an influence, it is preferable that the ratio (I _Na /I _CH3 ) and the ratio (I _K /I _CH3 ) measured with respect to the cross section of the optical film are within the above range.

Ratio, ionic strength, ionic strength (I _Na) of Na for (I _CH3) in CH ₃ obtained by the time-of-flight secondary ion mass spectrometry (I _Na / I _CH3) is not less than 0.2, and, of CH ₃ According to the optical film of the present invention in which the ratio of the ionic strength of K to the ionic strength (I _CH3 ) (I _K ) (I _K /I _CH3 ) is 0.2 or more, the impact resistance of the optical film can be surprisingly improved. Here, the ionic strength of CH ₃ (I _CH3 ), the ionic strength of _Na (I _Na ), and the ionic strength of _K (I _K ), which are obtained by time-of-flight secondary ion mass spectrometry, are present in the optical film. The amounts of carbon atoms and/or carbon ions, the amounts of sodium atoms and/or sodium ions, and the amounts of potassium atoms and/or potassium ions are shown relatively. The ratio (I _Na /I _CH3 ) of 0.2 or more indicates the presence of a certain amount of sodium atoms (Na) and/or sodium ions relative to the total amount of carbon atoms and/or carbon ions present in the optical film. The ratio (I _K /I _CH3 ) of 0.2 or more indicates that a certain amount or more of potassium atoms (K) and/or potassium ions exist 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 the carbon atom This is because CH ₃ ions are generated simultaneously as a proton adduct.

The reason why the impact resistance of the optical film is improved by the presence of sodium atoms and/or sodium ions, and potassium atoms and/or potassium ions in a certain amount or more is not clear, and the present invention is not limited to the mechanisms described later, but examples For example, it can be considered that the impact resistance is improved by the following mechanism. In addition, in the present specification, when the optical film is subjected to time-of-flight secondary ion mass spectrometry, a compound containing sodium atoms that can be included in the optical film, which can be considered to be detected as the ionic strength (I _Na ) of _Na , sodium and / Or sodium ion is also called "sodium-containing component". In addition, the compound containing a sodium atom is a compound containing a sodium atom as a constituent atom of a molecule. In addition, when the optical film is subjected to a time-of-flight secondary ion mass spectrometry, a compound containing a potassium atom that can be included in the optical film, which can be considered to be detected as an ionic strength (I _K ), potassium and/or potassium ions. , Also referred to as "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.

When manufacturing the optical film of the present invention, a sodium-containing component (a compound containing a sodium atom, sodium and/or sodium ions) and a potassium-containing component (potassium) in the composition containing the polyimide resin and/or the polyamide resin. By including an atom-containing compound, potassium and/or potassium ion), an imide bond and/or an amide bond contained in the resin, preferably an imide bond contained in a polyimide resin, a sodium-containing component, and Some interactions with potassium-containing components (e.g., between the carbonyl group and sodium ion of the imide bond or the amide bond, and the carbonyl group of the imide bond or the amide bond and the potassium ion, electrostatic interaction. Action) can be thought to occur. As a result, the polyimide-based resin and/or polyamide-based resin contained in the obtained optical film is present in the film in an interactive state with the sodium-containing component and the potassium-containing component, or the sodium-containing component and the potassium-containing component It is considered that the impact resistance of the optical film is improved by changing the orientation state of the resin due to the interaction between the polyimide resin and/or the polyamide resin. In addition, compared to the case where only one of the sodium-containing component or the potassium-containing component is present in the optical film, when both components are present, sodium-containing components having different atomic radius, ionic radius, and/or molecular size from each other It is also conceivable that the and potassium-containing components coexist in the optical film, and as a result, the packing of the polyimide resin and/or the polyamide resin contained in the optical film becomes strong, and the impact resistance of the optical film is improved. In addition, the above consideration does not limit the present invention at all. From the viewpoint of easy interaction with the imide bond and/or amide bond of the polyimide resin and/or the polyamide resin, the sodium-containing component and the potassium-containing component contained in the optical film are preferably in an ionized state. Do.

The ratio of the ionic strength of _Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) (I _Na /I _CH3 ) is preferably 0.95 or more, more preferably from the viewpoint of increasing the impact resistance of the optical film. Is 1.0 or more, more preferably 1.2 or more, even more preferably 1.4 or more, particularly preferably 1.5 or more, particularly more preferably 3 or more, particularly more preferably 5 or more, particularly preferably 7 or more, particularly It is more preferably 10 or more, and most preferably 12 or more. The upper limit of the ratio (I _Na / I _CH3 ) is preferably 100 or less from the viewpoint of easy to increase the film-forming properties of a varnish containing a polyimide resin and/or a polyamide resin, and to increase the uniformity of an optical film. , More preferably 50 or less, still more preferably 30 or less, even more preferably 25 or less, and particularly preferably 20 or less.

The ratio of the ionic strength of _K (I _K ) to the ionic strength of CH ₃ (I _CH3 ) (I _K /I _CH3 ) is from the viewpoint of easy to increase the impact resistance of the optical film, preferably 0.95 or more, more preferably Is 1.0 or more, more preferably 1.2 or more, even more preferably 1.4 or more, particularly preferably 1.5 or more, particularly more preferably 3 or more, particularly more preferably 5 or more, particularly preferably 10 or more, most It is preferably 12 or more. The upper limit of the ratio (I _K /I _CH3 ) is preferably 100 or less 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. , More preferably 50 or less, still more preferably 30 or less, even more preferably 25 or less, and particularly preferably 20 or less.

The sum of the ratio (I _Na /I _CH3 ) and the ratio (I _K /I _CH3 ) is preferably 0.5 or more, more preferably 1.0 or more, and more preferably from the viewpoint of easy to increase the impact resistance of the optical film. 1.5 or more, even more preferably 2 or more, particularly preferably 4 or more, particularly more preferably 5 or more, particularly more preferably 10 or more, particularly preferably 15 or more, most preferably 20 or more. The upper limit of the total value of the ratio (I _Na /I _CH3 ) and the ratio (I _K /I _CH3 ) is easy to increase the film-forming properties of a varnish containing a polyimide resin and/or a polyamide resin, and the optical film is uniform. From the viewpoint of easy property improvement, it is preferably 200 or less, more preferably 100 or less, still more preferably 50 or less, even more preferably 30 or less, and particularly preferably 25 or less.

The method of adjusting the ratio (I _Na /I _CH3 ) and the ratio (I _K /I _CH3 ) to the above range is not particularly limited, but the optical film of the present invention comprising a polyimide resin and/or a polyamide resin In the method of adjusting the content of the sodium-containing component (a compound containing a sodium atom, sodium and/or sodium ion) and a potassium-containing component (a compound containing a potassium atom, potassium and/or potassium ion), and The method of adjusting the content of the polyimide resin and/or the polyamide resin contained in the optical film is mentioned. Specifically, when the content of the sodium-containing component in the optical film is increased, the ionic strength (I _Na ) of _Na obtained by TOF-SIMS of the optical film is also increased. Further, 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 sodium-containing component in the optical film is increased, the value of the ratio (I _Na /I _CH3 ) increases, and when the content of the potassium-containing component in the optical film is increased, the ratio (I _K /I _CH3 ) The value of is increased, and when the content of the polyimide resin and/or polyamide resin contained in the optical film is increased, the values of the ratio (I _Na /I _CH3 ) and the ratio (I _K /I _CH3 ) decrease. By the above method, the ratio (I _Na /I _CH3 ) and 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 _{CH 3} ), the ionic strength of _Na (I _Na ), and the ionic strength of _K (I _K ) by TOF-SIMS are not particularly limited, and the ratio (I _Na The values of /I _CH3 ) and ratio (I _K /I _CH3 ) should be within the above ranges, but from the viewpoint of easy to secure measurement accuracy by TOF-SIMS, the ionic strength of _Na (I _Na ) and the ion of K It is preferable to perform the measurement under conditions such that the strength (I _K ) is each, preferably 100 or more, more preferably 300 or more, and still more preferably 500 or more.

The optical film of the present invention in which the ratio (I _Na /I _CH3 ) is 0.2 or more and the ratio (I _K /I _CH3 ) is 0.2 or more has high impact resistance. In the present specification, impact resistance indicates that even if an object around the surface of the optical film collides with the surface of the optical film, scratches such as dents are difficult to occur in the optical film, and/or it is difficult to remain. When the impact resistance of the optical film is high, it is easy to suppress a decrease in optical properties and visibility of the optical film due to the fact that scratches such as dents are hardly generated on the surface of the optical film, and/or it is difficult to remain. In addition, in the optical film of the present invention, the impact resistance can be improved particularly when subjected to a concentrated load, and the occurrence of minute dents as a starting point for deteriorating the characteristics of the optical film can also be suppressed. The impact resistance of the optical film can be measured, for example, by an impact resistance test that measures the amount of dents in the impact resistance test as described in Examples. In the optical film of the present invention, the depth of the depression in the impact resistance test is preferably 29 µm or less, more preferably 27 µm or less, still more preferably 26 µm or less, even more preferably 25 Μm or less, particularly preferably 24 µm or less.

The elastic modulus of the optical film of the present invention in which the ratio (I _Na /I _CH3 ) is 0.2 or more, and the ratio (I _K /I _CH3 ) is 0.2 or more, is preferably 5.0 GPa or more, more preferably 5.1 GPa or more, More preferably, it is 5.2 GPa or more, and usually 100 GPa or less. The elastic modulus can be measured using a tensile tester (for example, a chuck distance of 50 mm and a tensile speed of 10 mm/min). Further, simply by improving the elastic modulus of the optical film, the toughness of the optical film is low, and sufficient impact resistance may not be obtained. However, the optical film of the present invention has high impact resistance. Further, 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 impact resistance of the optical film can be improved.

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 89% or more, particularly preferably 90% or more, It is particularly more preferably 91% or more. When the total light transmittance is more than the above lower limit, it is easy to increase the visibility when the optical film is installed in 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, when the optical film of the present invention is installed in an image display device, there is a tendency that a bright display can be obtained even when the amount of light of the backlight is reduced, which 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 according to, for example, JIS K 7105:1981 or JIS K 7361-1:1997. In addition, the total light transmittance should just be the total light transmittance in the range of the thickness of an optical film mentioned later.

The haze of the optical film of the present invention is preferably 1% or less, more preferably 0.5% or less, further preferably 0.2% or less, even more preferably 0.15% or less, particularly preferably 0.14% or less, particularly It is more 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 installed in an image display device, particularly as a front plate, it is easy to increase visibility. In addition, haze can be measured using a haze computer according to JIS K 7105:1981 or JIS K 7136:2000.

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, still more preferably 2.2 or less, preferably -5 or more, more preferably -2 or more. 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 a front plate of an image display device, high visibility can be contributed. In addition, the YI value is measured by measuring the transmittance of light of 300 to 800 nm using an ultraviolet visible near-infrared spectrophotometer to obtain the tristimulus values (X, Y, Z), and YI = 100 × (1.2769X-1.0592Z) It can be calculated based on the equation of )/Y.

The lightness (L ^* ) value of the optical film of the present invention is preferably 90 or more, more preferably 93 or more, and still more preferably 95 or more, from the viewpoint of easily enhancing transparency and visibility of the optical film. The upper limit of the L ^* value is not particularly limited and may be 100 or less. The above brightness (L ^* ) value can be measured using a spectrophotometer, for example, can be measured by the method described in Examples.

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 sufficient. When the thickness of the optical film is within the above range, it is easy to increase the impact resistance of the optical film. In addition, the thickness of the optical film can be measured using a micrometer, for example, it can be measured by the method described in Examples.

The number of bending (bending radius (R) = 1 mm) in the bending resistance test in the optical film of the present invention is preferably 150,000 times or more, more preferably 180,000 times or more, further preferably 200,000 times. That's it. When the number of bending is greater than or equal to the above lower limit, it has sufficient bending resistance as a front plate material such as a flexible display device. In addition, the number of bends in the bending resistance test is until the time when the optical film is repeatedly bent, using a bending tester, under the condition that the bending radius (curvature radius) (R) is 1 mm, and the film is cracked. It represents the number of reciprocating bendings (one round trip is made once).

<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. Each of the polyimide precursor resin and the polyamideimide precursor resin is a precursor before imidization, which imparts a polyimide resin and a polyamideimide resin by imidization, and is a resin also called polyamic acid. In addition, in the present 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 polyamideimide from the viewpoint of being easy to achieve both chemical stability and impact resistance of the optical film. It is a 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 more easily enhancing the impact resistance 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 preferred embodiment, from the viewpoint of more easily enhancing the impact resistance of the optical film, the ratio of the structural units derived from the aromatic monomer to all the structural units contained in the polyimide resin and the polyamide resin, It 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, such as an aromatic ring, and a constitution containing at least a part of an aromatic structure, for example an aromatic ring. Unit. 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 a structural unit represented by formula (2). It is preferable that the paper is a polyamideimide resin having a structural unit. Further, it is preferable that the polyamide resin is a polyamide resin having a structural unit represented by formula (2). Hereinafter, formulas (1) and (2) will be described, but the description of formula (1) relates to both polyimide resin and polyamideimide resin, and the description of formula (2) is poly It relates to both an amide resin and a polyamide-imide 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 or a fluorine-substituted C 1 to C 8 hydrocarbon group, a C 1 to C 6 alkoxy group, or a fluorine-substituted It is a C4-C40 divalent organic group which may be substituted by a C1-C6 alkoxy group, More preferably, a C1-C8 hydrocarbon group, a fluorine-substituted C1-C8 hydrocarbon group, and a C1-C4 hydrocarbon group It represents a C4-C40 divalent organic group having a cyclic structure which may be substituted with a 6 alkoxy group 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 as the heterocyclic structure of Z, a thiophene ring skeleton is used. The branch group is illustrated. From the viewpoint of easily suppressing the yellowness of the optical film (reducing the YI value), groups represented by formulas (20) to (29) and groups having a thiophene ring skeleton are preferred. In one embodiment of the present invention, the polyamide-based resin and the polyamide-imide resin may contain one type of organic group as Z, and 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 hydrocarbon group having 1 to 8 carbon atoms substituted with fluorine. , 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'), Z in formula (2), polyamide resin or polyamideimide 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)-*, * indicates 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 obtained optical film 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 resin and the polyamide-imide 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 impact resistance of the optical film of the present invention and also to increase the optical properties, at least a part of Z is 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 the formula (3):

[Formula 5]

[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 R ¹ to R The hydrogen atoms contained in ⁸ may be each independently 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,

* Represents 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 C1-C6 alkyl group 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, and n-hexyl group. 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 cyclohexyloxy group. Time, etc. As a C6-C12 aryl group, a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a biphenyl group, etc. are mentioned, for example. From the viewpoint of 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, and 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 substituted with halogen atoms independently of each other.

R ⁹ represents a C 1 to C 12 monovalent hydrocarbon group which may be substituted with a hydrogen atom or a halogen atom. Examples of the monovalent hydrocarbon group having 1 to 12 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, 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, the impact resistance, elastic modulus, and bending resistance of the optical film are easily improved. In the formulas (3) and (3a), m is an integer in the range of preferably 0 to 3, more preferably 0 to 2 from the viewpoint of more easily improving the impact resistance, elastic modulus, and bending resistance of the optical film. It is an integer in the range, 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 the formula (3) is a hydrogen atom. 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 easy improvement of the impact resistance, elastic modulus, and bending resistance of the 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 type or two or more types of structural units represented by formula (3). From the viewpoint of improving the impact resistance, elastic modulus and flexural resistance of the optical film, and reducing the yellowness (YI value), the resin is two or more structural units having different values of m in the formula (3) or (3a) in Z It is preferable to include, and it is more preferable to include two or three structural units having different values of m in the formula (3) or (3a). In this case, from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint of easy reduction of the yellowness (YI value) of the optical film, the resin is Z, and m is 0 It is particularly preferable to contain the structural unit represented by and further contain the structural unit represented by formula (3) in which m is 1 in addition to the structural unit. In addition, it is also preferable to further have a structural unit represented by the above formula (d1) in addition to the structural unit represented by the formula (2) having Z represented by the 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 a hydrogen atom 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 in which R ⁵ to R ⁸ is a hydrogen atom, and formula (3'):

[Formula 6]

It has a structural unit represented by In this case, while it is easy to improve the impact resistance, elastic modulus, and bending resistance of the optical film, 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 formula (1) of the polyamideimide resin. When the total of the structural units and the structural units represented by formula (2) is 100 mol%, preferably 20 mol% or more, more preferably 30 mol% or more, still more preferably 40 mol% or more, even more It is 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 units represented by Formula (3) or Formula (3a) is more than the above lower limit, it is easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film. If the ratio of the constituent units represented by formula (3) or formula (3a) is less than or equal to the upper limit, the viscosity increase of the resin-containing varnish due to hydrogen bonding between amide bonds derived from formula (3) or formula (3a) is suppressed. , It is easy to improve the processability of the film.

In addition, when the polyamideimide resin has a structural unit represented by formula (3) or formula (3a) in which m=1 to 4, the configuration represented by formula (3) or formula (3a) in which m is 1 to 4 The ratio of the unit is, when the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) of the polyamideimide resin is 100 mol%, preferably 3 mol% or more, more preferably Is 5 mol% or more, more preferably 7 mol% or more, particularly preferably 9 mol% or more, preferably 90 mol% or less, more preferably 70 mol% or less, even more preferably 50 mol% or less , Particularly preferably 30 mol% or less. When the ratio of the structural units represented by the 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 impact resistance, elastic modulus, and bending resistance of the optical film. Hydrogen bonds between amide bonds derived from the constituent units represented by formula (3) or (3a) if the ratio of the constituent 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 units represented by formula (1), formula (2), formula (3) or formula (3a) 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 resin or polyamideimide resin is preferably 30 mol% or more, more preferably 40 mol% or more, still more preferably 45 mol% or more, particularly 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 impact resistance, elastic modulus, and bending resistance of an optical film. Further, 100 mol% or less of Z in the polyamide resin or polyamideimide 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 calculated from the introduction ratio of the raw material. You may.

In a preferred embodiment of the present invention, the Z in the polyamide resin or polyamideimide resin is preferably 5 mol% or more, more preferably 8 mol% or more, still more preferably 10 mol% or more, particularly 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 impact 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, particularly preferably 30 mol% or less, is the formula (3) wherein m is 1 to 4 ) Or formula (3a). If less than or equal to the above upper limit of Z is represented by formula (3) or formula (3a) where m is 1 to 4, it is derived from a structural unit represented by formula (3) or formula (3a) wherein m is 1 to 4 It is easy to suppress an increase in the viscosity of the resin-containing varnish due to hydrogen bonding 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. May be.

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. As X, represented by Formula (10), Formula (11), Formula (12), Formula (13), Formula (14), Formula (15), Formula (16), Formula (17) and Formula (18) group; 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 (16) from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film. And a group represented by formula (17) is preferred, and a group represented by formula (14), formula (15), and formula (16) is more preferred. In addition, V ¹ , V ² and V ³ are independently of each other, preferably a single bond, -O- or -S-, more preferably a single bond, from the viewpoint of easy to increase the impact resistance, elastic modulus and flexibility of the optical film. Is a 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,

* Represents a bond hand]

It is a structural unit represented by. If 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 impact 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 contained hydrogen atoms may be substituted with halogen atoms independently of each other. 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 impact resistance, elastic modulus, transparency and bending resistance of the optical film, Even more 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. And 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 the polyamide 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, and the viscosity of the varnish is reduced. It is easy to do, and it is easy to improve the processability of an optical film. In addition, it is easy to improve the optical properties of the optical film by the skeleton containing the 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, still more preferably 70 mol% or more. It is represented by formula (4), especially formula (4'). When X within the above range in the polyimide resin or polyamide resin is represented by formula (4), in particular formula (4'), the resulting optical film is in a resin solvent by a skeleton containing a fluorine element. The solubility to the resin is improved, the storage stability of the varnish containing the resin is easily improved, the viscosity of the varnish is easily reduced, and the processability 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 formula (1), Y represents a tetravalent organic group, preferably represents a tetravalent organic group having 4 to 40 carbon atoms, and more preferably represents a tetravalent organic group having 4 to 40 carbon atoms having a cyclic structure. Examples of the cyclic structure include an alicyclic, aromatic ring, and heterocyclic structure, and from the viewpoint of easy to increase impact resistance and elastic modulus, an aromatic ring is preferably used. 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 A group represented by 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 chain hydrocarbon group.

[Formula 10]

In formulas (20) to (29), * represents a bond hand, 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), groups represented by formulas (26), (28) or (29) are preferred from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film. And the group represented by formula (26) is more preferable. In addition, W ¹ is independent of each other, preferably a single bond, -O-, -CH from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and to reduce the YI value of the optical film. 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 -, particularly preferably a single bond 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, and 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, if W ¹ is a single bond or -C(CF ₃ ) ₂ -represented by the equation (26), it is easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and to reduce the YI value of the optical film. easy. The ratio of the structural unit in which Y in the polyimide resin is represented by 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 formula (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 R ¹⁸ to R ²⁵ The hydrogen atoms contained in may be independently of each other and may be substituted with a halogen atom,

* Represents 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 impact 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 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 contained hydrogen atoms may be substituted with halogen atoms independently of each other. 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 each independently a hydrogen atom from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint of easy to increase transparency and easy to maintain the transparency, more preferably , A methyl group, a fluoro group, a chloro group, or a trifluoromethyl group, more preferably R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ and R ²⁵ are hydrogen atoms, R ²¹ and R ²² are hydrogen An atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group is represented, and particularly preferably R ²¹ and R ²² represent a methyl group or a trifluoromethyl group.

In formula (9), from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint of easy to increase the transparency and easy to maintain the transparency, 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. . Examples of the C1-C6 alkyl group and the C6-C12 aryl group for R ³⁵ to R ⁴⁰ include those exemplified above, respectively.

In a preferred embodiment of the present invention, equation (5) is represented by equation (5'), and equation (9) is equation (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 impact resistance, elastic modulus, and bending resistance of the optical film. In addition, when formula (5) is represented by formula (5'), the solubility of the polyimide resin in the solvent is increased due to 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. In addition, it is easy to improve the optical properties of the optical film by the skeleton containing the 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. In addition, it is easy to improve the optical properties of the optical film by the skeleton containing the fluorine element. In addition, 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) or (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), in addition to the structural units in which Y is represented by formula (5), Y is additionally 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 impact resistance and the elastic modulus of the optical film.

The polyimide resin may contain a structural unit represented by formula (30) and/or a structural unit represented by formula (31), or may be represented by formula (1) and optionally formula (2). In addition to the structural unit, a structural unit represented by formula (30) and/or a 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 A group represented by (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 carbon number of 6 or less The chain hydrocarbon group of is illustrated. In one embodiment of the present invention, a polyimide-based resin may include a plurality of types of Y ^1, Y ¹ may be a plurality of types it is 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 formulas (20), (21), (22), (23), (24), (25), (26), (27), and (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, and 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 formulas 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 structural unit. In addition, from the viewpoint of easy to increase the optical properties, impact 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 formula (1) ) And formula (2), and in some cases, based on the total structural units represented by formula (30) and/or formula (31), preferably 80 mol% or more, more preferably 90 mol% or more, further It is preferably 95 mol% or more, and usually 100% or less. 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 the polyamide resin in the optical film is preferably 10 parts by mass or more, more preferably 30 parts by mass, based on 100 parts by mass of the optical film. It is mass part or more, more preferably 50 mass parts or more, preferably 99.5 mass parts or less, more preferably 95 mass parts or less. 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, impact resistance and elastic modulus of the optical film.

The weight average molecular weight of the polyimide resin and the polyamide resin is, in terms of standard polystyrene, from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, preferably 200,000 or more, more preferably 230,000 or more, and more It is preferably 250,000 or more, even more preferably 270,000 or more, particularly preferably 280,000 or more. In addition, the weight average molecular weight of the polyimide-based resin and the polyamide-based resin is preferably 1,000,000 or less from the viewpoint of improving the solubility of the resin in a solvent and easily improving the stretchability and processability of the optical film. , More preferably 800,000 or less, still more preferably 700,000 or less, and particularly preferably 500,000 or less. The weight average molecular weight can be obtained by performing GPC measurement, for example, in terms of standard polystyrene, and may be calculated, for example, by the method described in Examples.

In the polyamideimide resin, the content of the structural unit represented by the formula (2) is preferably 0.1 mole or more, more preferably 0.5 mole or more, and more with respect to 1 mole of the structural unit represented by formula (1). It is preferably 1.0 mol or more, particularly 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 the formula (2) is more than the above lower limit, it is easy to increase the impact resistance and elastic modulus of the optical film. In addition, when the content of the structural unit represented by the formula (2) is equal to or less than the above upper limit, thickening due to hydrogen bonds between the amide bonds in the 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 polyamide resin contained in the optical film contains halogen atoms such as fluorine atoms that can be introduced by, for example, the above fluorine-containing substituents. You may include it. 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 further reduce the YI value. When the elastic modulus of the optical film is high, it is easy to suppress the occurrence of wounds and wrinkles. Moreover, when the YI value of an optical film is low, it becomes easy to improve the transparency and visibility of the said 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 the halogen atom 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 water 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, still more preferably 96% or more, and usually 100% or less. It is preferable that the imidation ratio is more than the above lower limit from the viewpoint of easy to increase the optical properties of the optical film. The imidation ratio represents the ratio of the molar amount of imide bonds in the polyimide-based resin to a value twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimide-based resin. In addition, when the polyimide resin contains a tricarboxylic acid compound, the value of twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyimide resin and the structural unit derived from the tricarboxylic acid compound The ratio of the molar amount of imide bonds in the polyimide resin to the sum of the molar amounts is shown. In addition, 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. Neoprem (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 resin according to the present embodiment is a polymer mainly comprising a repeating structural unit represented by formula (2). Preferred examples and specific examples of Z in formula (2) in the polyamide-based resin are the same as those of the preferred examples and specific examples of Z in the polyimide-based resin. The polyamide-based resin may contain repeating structural units represented by two or more types of formula (2) from which Z differs.

(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 main raw materials, and the polyamideimide resin and polyamideimide precursor resin are, for example, tetracarboxylic acid. A compound, a dicarboxylic acid compound, and a diamine compound can be used as the main raw materials, and the polyamide resin can be produced, 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 a compound represented by at least 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 R ¹ The hydrogen atoms contained in -R ⁸ may be each independently 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 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,

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

Examples of the diamine compound used in the production of 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 although a benzene ring, a naphthalene ring, an anthracene ring, a fluorene ring, etc. are illustrated, it is not limited to these. Among these, preferably, it is a benzene ring. In addition, "aliphatic diamine" refers to 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 an aromatic diamine, for example, p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2, Aromatic diamines 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'-dia Minodiphenylsulfone, 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 (hereinafter sometimes referred to 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- And aromatic diamines having two or more aromatic rings such as 3-chlorophenyl)fluorene and 9,9-bis(4-amino-3-fluorophenyl)fluorene. These can be used alone or in combination of two or more.

The aromatic diamine is preferably 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether. , 4,4'-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 viewpoints 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 dianhydride and the like. Tetracarboxylic acid compounds may be used alone or in combination of two or more. In addition to the 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 acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid 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 acid dianhydride (hereinafter, 6 FDA) Yes), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-di Carboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane Dianhydride, 4,4'-(p-phenylenedioxy)diphthalic dianhydride, and 4,4'-(m-phenylenedioxy)diphthalic dianhydride. In addition, examples of monocyclic aromatic tetracarboxylic dianhydride include 1,2,4,5-benzenetetracarboxylic dianhydride, and condensed polycyclic aromatic tetracarboxylic dianhydride include, for example 2,3,6,7-naphthalene tetracarboxylic dianhydride is mentioned.

Among these, preferably 4,4'-oxydiphthalic acid dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, 2,2',3,3'-benzophenone tetracarboxylic acid Dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-di Phenylsulfonetetracarboxylic acid 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 Dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 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 acid dianhydride. These can be used alone or in combination of two or more.

As the aliphatic tetracarboxylic dianhydride, a cyclic or acyclic aliphatic tetracarboxylic dianhydride can be mentioned. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4- Cycloalkanetetracarboxylic dianhydrides such as cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene-2,3, 5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, and positional isomers 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 may be used in combination of two or more. Further, a cyclic aliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

Among the tetracarboxylic dianhydrides, from the viewpoint of high impact resistance, high modulus of elasticity, high surface hardness, high transparency, high ductility, high flexural resistance, and low colorability of the optical film, 4,4'-oxydiphthalic acid dianhydride, 3 ,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid Dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 4,4'-(hexafluoroiso Propylidene)diphthalic dianhydride, and mixtures thereof are preferred, and 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-(hexafluoroisopropylidene)diphthalic acid 2 Anhydrides, and mixtures thereof are more preferable, and 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride (6FDA) and 3,3',4,4'-biphenyltetracarboxylic acid dianhydride ( Hereinafter, it may be described as BPDA) is more preferable.

As the dicarboxylic acid compound used in the production of the resin, terephthalic acid, 4,4'-oxybisbenzoic acid, or an acid chloride compound thereof is 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; Of a chain hydrocarbon having 8 or less carbon atoms, a dicarboxylic acid compound 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.

Further, the polyimide 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 a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -or a phenylene group.

In the production of a 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 to It is 100℃. 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, and examples include 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-based 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. . Further, from the viewpoint of facilitating the imidation reaction, it is preferable to use an acid anhydride together with the imidation catalyst. 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-based resins and polyamide-based resins are separated and purified by a common method, for example, separation means such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or a combination of them. In a preferred embodiment, a large amount of alcohol such as methanol is added to a reaction solution containing a transparent polyamideimide resin, the resin is precipitated, and the resin can be isolated by performing concentration, filtration, drying, etc. .

<Ingredients containing sodium>

The optical film of the present invention contains a sodium-containing component selected from the group consisting of a compound containing a sodium atom, sodium and sodium ions. The content of the sodium-containing component in the optical film of the present invention is the ratio of the ionic strength of _Na (I _Na ) to the ionic strength of CH ₃ (I _CH3 ) obtained by time-of-flight secondary ion mass spectrometry (I _Na It is not particularly limited as long as /I _CH3 is an amount of 0.2 or more, and the ratio (I _Na /I _CH3 ) may be set in a predetermined range according to the type of polyimide resin included in the optical film. For example, the content of the sodium-containing component in the varnish for producing the optical film of the present invention is a polyimide-based resin and/or a polyamide-based resin contained in the varnish from the viewpoint of easy to increase the impact resistance of the optical film. With respect to the total amount of, preferably 0.002 mass% or more, more preferably 0.004 mass% or more, still more preferably 0.01 mass% or more, even more preferably 0.02 mass% or more, particularly preferably 0.03 mass% or more, In particular, it is more preferably 0.04 mass% or more. The upper limit of the content of the sodium-containing component in the varnish for producing the optical film of the present invention is relative to the total amount of the polyimide resin and/or polyamide resin contained in the varnish from the viewpoint of easy obtaining a homogeneous film. , Preferably it is 1 mass% or less, More preferably, it is 0.5 mass% or less, More preferably, it is 0.1 mass% or less. In addition, the content of the sodium-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 easily enhancing the impact resistance of the optical film. Preferably at least 0.002% by mass, more preferably at least 0.004% by mass, more preferably at least 0.01% by mass, even more preferably at least 0.02% by mass, particularly preferably at least 0.03% by mass, particularly more preferably at least 0.04 It is not less than mass%. The upper limit of the content of the sodium-containing component in the optical film of the present invention is, from the viewpoint of easy to obtain a homogeneous film, with respect to the total amount of the polyimide resin and/or polyamide resin contained in the optical film, preferably It is 1 mass% or less, More preferably, it is 0.5 mass% or less, More preferably, it is 0.1 mass% or less. The content of the sodium-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 sodium atom is used as the sodium-containing component, the compound may be decomposed or the like in the process of manufacturing an optical film within a range that does not impair the effects of the present invention.

The kind of the compound containing a sodium atom is not particularly limited. When manufacturing 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 sodium atom is preferably an organic sodium salt. As an organic sodium salt, a C1-C6 sodium alkoxide, etc. are mentioned. It is preferable to use an aprotic polar solvent as the solvent for the varnish from the viewpoint of increasing the solubility of the compound containing sodium atoms and obtaining a resin composition containing a polyimide resin and/or a polyamide resin having excellent film formability. Do. When an aprotic polar solvent is used, for example, when a salt such as sodium hydroxide or sodium chloride is used as a compound containing a sodium atom, the salt is easily dissolved in the varnish, and the polyimide resin and/or polyamide in the varnish It can be considered that the interaction between the resin and the compound containing a sodium atom becomes easy to increase. In addition, the compound containing the sodium 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 sodium salt. For example, moisture or moisture that may be included in the resin composition A separate salt may be formed in the final optical film by hydrolysis with alcohol or the like, ion exchange reaction with another salt, or the like, and may be contained as sodium or sodium ions. Here, the polyimide-based resin and/or the polyamide-based resin contained in the optical film is a resin that is easy to absorb moisture, and the resin composition and optical film containing such a resin usually contain moisture. In addition, as described above, it is conceivable that hydrolysis occurs due to reaction with moisture in the resin composition, for example, the sodium-containing component added to the resin composition in the form of an organic sodium salt such as sodium alkoxide, In the final optical film, it may be considered that at least a part thereof is a salt sodium hydroxide or the like, and the sodium hydroxide or the like is, for example, partially ionized and interacts with a carbonyl group to exist.

<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 It is not particularly limited as long as /I _CH3 is an amount of 0.2 or more, 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-based resin and/or a polyamide-based resin contained in the varnish from the viewpoint of easy to increase the impact resistance of the optical film. With respect to the total amount of, 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 mass% or more, Particularly more preferably, it is 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 from the viewpoint of easy to obtain a homogeneous film, with respect to the total amount of the polyimide resin and/or polyamide resin contained in the varnish. , Preferably it is 1 mass% or less, More preferably, it is 0.5 mass% or less, More preferably, it is 0.3 mass% or less, Especially preferably, it is 0.2 mass% or less. In addition, 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 easily enhancing the impact resistance of the optical film. 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, particularly more preferably 0.08 It is not less than mass%. The upper limit of the content of the potassium-containing component in the optical film of the present invention is, from the viewpoint of easy to obtain a homogeneous film, with respect to the total amount of the polyimide resin and/or polyamide resin contained in the optical film, preferably It is 1 mass% or less, more preferably 0.5 mass% or less, still more preferably 0.3 mass% or less, particularly preferably 0.2 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 or the like in the process of manufacturing 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. In the case of producing an optical film using a 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 is easily contained in the optical film. In, 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. It is preferable to use an aprotic polar solvent as a solvent for the varnish from the viewpoint of enhancing the solubility of the compound containing potassium atoms and obtaining a resin composition containing a polyimide resin and/or a polyamide resin having excellent film formability. Do. In the case of using an aprotic polar solvent, for example, even when a salt such as potassium hydroxide or potassium chloride is used as a compound containing a potassium atom, the salt is easily dissolved in the varnish, and the polyimide resin and/or polyamide in the varnish It can be considered that the interaction between the resin and the compound containing a potassium atom becomes easy to increase. 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. For example, moisture or moisture that may be included in the resin composition Another salt may be formed in the final optical film by hydrolysis with alcohol or the like, ion exchange reaction with another salt, or the like, and may be contained as potassium or potassium ions. Here, the polyimide-based resin and/or the polyamide-based resin contained in the optical film is a resin that is easy to absorb moisture, and the resin composition and optical film containing such a resin usually contain moisture. In addition, as described above, it is also conceivable that hydrolysis occurs due to reaction with moisture in the resin composition. For example, the potassium-containing component added to the resin composition in the form of an organic potassium salt such as potassium alkoxide, In the final optical film, it can be considered that at least a part thereof is a salt of potassium hydroxide or the like, and the potassium hydroxide or the like is, for example, partially ionized and interacts with a carbonyl group to exist.

<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. Examples of inorganic particles include metal oxide particles such as silica, zirconia, alumina, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide, antimony oxide, cerium oxide, and metal fluoride particles such as magnesium fluoride and potassium fluoride. Can be mentioned. The filler is preferably silica particles, zirconia particles, 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 may be used alone or in combination of two or more.

The average primary particle diameter of the filler, preferably silica particles, is usually 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, and particularly 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, particularly more preferably 50 nm or less, It is particularly more preferably 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. In addition, 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. In addition, 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 type of compound selected from the group consisting of a benzophenone compound, a salicylate compound, a benzotriazole compound, and a triazine compound. 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, and 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 preferable 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 can be improved and transparency can be easily improved.

The optical film of the present invention may further contain additives other than a filler and an ultraviolet absorber. Examples of other additives include antioxidants, 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 method for producing the optical film of the present invention is not particularly limited, but, for example, the following steps:

(a) A resin comprising at least one resin selected from the group consisting of the polyimide resin and polyamide resin, at least one sodium-containing component, at least one potassium-containing component, and a solvent A step of preparing a composition (hereinafter also referred to as ``varnish'') (varnish preparation step), wherein the sodium-containing component is selected from the group consisting of a compound containing a sodium atom, sodium and sodium ions, and the potassium The contained component is selected from the group consisting of a compound containing a potassium atom, potassium and potassium ions,

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

(c) Drying the coating film to form an optical film (optical film forming step)

What is necessary is just to be a manufacturing method containing at least The present invention is suitable for producing the optical film of the present invention, at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, at least one sodium-containing component, and at least one The production method described above using a resin composition containing at least a potassium-containing component and a solvent is also provided.

In the varnish preparation step, at least one resin selected from the group consisting of polyimide resins and polyamide resins, at least one sodium-containing component, and at least one potassium-containing component are dissolved in a solvent, If necessary, additives such as the above filler and ultraviolet absorber are added and mixed with stirring to prepare a varnish. In addition, when silica particles are used as the filler, a silica sol dispersion liquid containing silica particles is added to the resin by a solvent in which the resin is soluble, for example, a silica sol substituted with a solvent used for preparing the following varnish. You can do it.

The sodium-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 sodium atom, sodium and sodium ions in the optical film of the present invention, but the component is a solvent of the varnish From the viewpoint of being easy to dissolve in and to contain the component in an optical film, it is preferably a compound containing a sodium atom, and more preferably an organic sodium salt. As an organic sodium salt, a C1-C6 sodium alkoxide, etc. are mentioned. The sodium-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 sodium-containing component contained in the resin composition is at least one resin 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 impact resistance and elastic modulus of the optical film. With respect to the total amount of, preferably 0.002 mass% or more, more preferably 0.004 mass% or more, still more preferably 0.01 mass% or more, even more preferably 0.02 mass% or more, particularly preferably 0.03 mass% or more, In particular, it is more preferably 0.04 mass% or more. The upper limit of the content of the sodium-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 viewpoint of adjustability of the varnish viscosity and film-forming properties. With respect to the total amount of the resin of the species, it is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less. When the content of the sodium-containing component is 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 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 resin 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 impact resistance and elastic modulus of the optical film. With respect to the total amount of, 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 mass% or more, Particularly more preferably, it is 0.08 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 viewpoint of adjustability of the varnish viscosity and film-forming properties. With respect to the total amount of the resin of the species, it is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.1% by mass or less. When the content of the 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 (hereinafter, sometimes referred to as DMAc) and N,N-dimethylformamide (hereinafter, referred to as DMF); lactone solvents such as γ-butyrolactone (hereinafter sometimes referred to as GBL) and γ-valerolactone; Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; Carbonate-based solvents such as ethylene carbonate and propylene carbonate; And combinations thereof. Among these, an amide solvent or a lactone solvent is preferred. These solvents may be used alone or in combination of two or more. In addition, 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%, and still more preferably 5 to 15 mass%. Here, from the viewpoint of easy to increase the interaction between the polyimide resin and/or the polyamide resin and the sodium-containing component and/or the potassium-containing component, it is preferable to use a solvent capable of dissolving them in the preparation of the varnish. For example, from the viewpoint of the solubility of the resin, the above solvent is preferable, and from the viewpoint of the solubility of the sodium-containing component and/or the potassium-containing component, an aprotic polar solvent is preferable, and consists of an amide-based solvent and a lactone-based solvent. An aprontic polar solvent selected from the group is more preferred. In addition, since the above-mentioned solvent easily takes moisture in the atmosphere and contains it, it is considered that water is often contained in the varnish even if water is not intentionally added to the varnish. In addition, when the sodium-containing component and/or a part of the potassium-containing component, which are sodium ions and/or potassium ions in the varnish, interact with the resin, the equilibrium proceeds in the direction in which the sodium-containing component and/or the potassium-containing component are ionized. You can think of it. Therefore, even if the sodium-containing component and/or the potassium-containing component is a compound such as a salt that is difficult to dissolve in the solvent used for preparing the varnish, since polyimide-based resin and/or polyamide-based resin are contained in the varnish, It becomes possible to dissolve the said contained component. In addition, it is also possible to promote the interaction between the resin and the sodium-containing component and/or the potassium-containing component by leaving it in the state of the varnish for a certain period of time.

It has been confirmed that the viscosity of the resin composition containing the resin, the sodium-containing component, the potassium-containing component, and the solvent is high compared to the viscosity of the composition before adding the sodium-containing component and the potassium-containing component. Such an increase in viscosity is considered to be due to the interaction between the resin, the sodium-containing component, and the potassium-containing component due to the addition of the sodium-containing component and the potassium-containing component. Specifically, when the viscosity of the resin composition is measured using a viscometer, for example, under the conditions described in the Examples, the viscosity increases due to the addition of the sodium-containing component and/or the addition of the potassium-containing component. I can confirm. In addition to having such an interaction, it is expected that packing between the resins is further strengthened by coexisting sodium-containing components and potassium-containing components having different atomic radii, ionic radii, or molecular sizes in the resin.

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, di The ping method, the spray method, the casting method, etc. are mentioned.

In the film formation process, an optical film can be formed by drying a coating film and peeling it from a support material. After peeling, you may form 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, drying of the coating film may be performed under conditions of an inert atmosphere or reduced pressure. In addition, a part of the solvent contained in the varnish may slightly remain in the obtained optical film. The amount of the solvent contained in the optical film is preferably 1.5% or less, more preferably 1.2% or less, still more preferably 1.1% or less, and even more preferably 1.0% or less, based on the mass of the optical film. The lower limit of the amount of the solvent is preferably 0% or more, more preferably 0.02% or more, still more preferably 0.1% or more, and even more preferably 0.3% or more. When the amount of residual solvent in the optical film is within the above range, the impact resistance of the optical film can be increased and the YI value can be made low. In addition, the amount of residual solvent in the optical film can be adjusted under the drying conditions of the coating film.

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

(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 adjusting layer, and a refractive index adjusting layer. The functional layer can be used alone or in combination of two or more. When the optical film has the functional layer, it is preferable to perform measurement by TOF-SIMS on the cross section of the 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 coating layer is within the above range, the impact resistance can be further improved, the bending resistance is difficult to decrease, and the problem of curling due to cure shrinkage tends to be difficult to 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. In addition, when the radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be the same or different. The number of radically polymerizable groups in one molecule of the radical polymerizable compound 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 mentioned from the viewpoint of high reactivity, and specifically, a polyfunctional compound having 2 to 6 (meth)acryloyl groups in one molecule Compounds called 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.

In addition, 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 accompanying the polymerization reaction is small. In addition, the compound having an epoxy group among the cyclic ether groups has the advantage that compounds of various structures are easily available, does not adversely affect the durability of the obtained hard coating layer, and compatibility with the radical polymerizable compound is also easy to control. In addition, the oxetanyl group among the cyclic ether groups tends to have a higher degree of polymerization compared to the epoxy group, has low toxicity, and accelerates the rate of network formation obtained from the cation polymerizable compound of the obtained hard coating layer, 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 is epoxidized with a suitable oxidizing agent such as hydrogen peroxide or peracid. The alicyclic epoxy resin obtained; Aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers and copolymers of glycidyl (meth)acrylates; Bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or derivatives such as alkylene oxide adducts and caprolactone adducts thereof, and glycidyl ether prepared by reaction with epichlorohydrin, and novolac And glycidyl ether type epoxy resins derived from bisphenols, such as 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. Such a polymerization initiator is decomposed by at least one kind of active energy ray irradiation and heating, and generates radicals or cation to proceed radical polymerization and cation polymerization.

The radical polymerization initiator may be capable of releasing a substance for initiating 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 perbenzoic acid, and azo compounds such as azobisbutyronitrile.

As active energy ray radical polymerization initiators, 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 through hydrogen extraction reaction. It can be used as or in combination.

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

The polymerization initiator may preferably contain 0.1 to 10% by mass based on 100% by mass of the total hard coating composition. When 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 also poor adhesion due to curing shrinkage, cracking phenomenon, 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 a solvent and an additive.

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 is composed of, for example, a main material selected from an ultraviolet curable transparent resin, an electron beam curable transparent resin, and a thermosetting transparent resin, and an ultraviolet absorber dispersed in the main material. do.

The adhesive layer is a layer having an adhesive function, and has a function of adhering an optical film to another member. 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 adhesive layer may be a layer that is adhered to the object by pressure, called a pressure sensitive adhesive (PSA). 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 specific component is contained in a protective film (microcapsule), and An adhesive that can maintain 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 function of hue adjustment, and is a layer capable of adjusting a laminate 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 azo compounds, quinacridone compounds, anthraquinone compounds, perylene compounds, isoindolinone compounds, phthalocyanine compounds, quinophthalone compounds, srene compounds, and diketopyrrolopyrrole compounds; Extender pigments such as barium sulfate and calcium carbonate; And dyes such as alkaline dyes, acid dyes, and mordant dyes.

The refractive index adjusting layer is a layer having a function of adjusting the refractive index, and has a refractive index different from that of an optical film, for example, and is a layer capable of imparting a predetermined refractive index to an optical laminate. The refractive index adjustment layer may be, for example, an appropriately selected resin, and a resin layer further containing a pigment as the case may be, or may be 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 for 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 another film. Ratio, ionic strength, ionic strength (I _Na) of Na for (I _CH3) in CH ₃ obtained by the time-of-flight secondary ion mass spectrometry (I _Na / I _CH3) is not less than 0.2, and, of CH ₃ the ratio of the ionic strength ionic strength (I _K) of K for _{(I CH3) (I K /} I CH3) is 0.2 or more optical films of the invention, obtain the high impact resistance, as an optical film in such an image display device, It is a useful film.

In a preferred embodiment of the present invention, the optical film of the present invention is a front plate of an image display device, among others, a front plate (window film) of a flexible display device, in particular, a rollable display that may be bent or returned flat. It is very useful as a front panel of a foldable display. The flexible display device has, for example, a flexible functional layer and an optical film that is superposed 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 the flexible display device, any image display device having flexible characteristics can be 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 a flexible display device and an organic EL display panel, and a laminate for a flexible display device is disposed on a viewing side of the organic EL display panel, and is configured to be bent. 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, it is preferable that the pattern of the touch sensor is difficult to be recognized and the visibility of the displayed image is improved. Each member may be laminated using an adhesive or an adhesive. In addition, a light blocking 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.

[Polarizer]

The flexible display device of the present invention may further include a polarizing plate, preferably a circular polarizing plate. The circular polarizing plate is a functional layer 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 linearly polarizing plate. For example, external light is converted into right circularly polarized light, which is reflected by the organic EL panel to block external light that has become left circularly polarized light, and is used to suppress the influence of reflected light by transmitting only the light emission component of the organic EL to make the image easier to see. In order to achieve the circular polarization function, the absorption axis of the linear polarizing plate and the slow axis of the λ/4 retardation plate need to be 45° in theory, but are practically 45±10°. The linear polarizing plate and the λ phase difference plate do not necessarily need to be stacked adjacent to each other, and the relationship between the absorption axis and the slow axis should satisfy the above range. Although it is desirable to achieve complete circular polarization at all wavelengths, in practical use, 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 further increase the visibility in the state of wearing polarized sunglasses by laminating a λ/4 retardation film further on the viewing side of the linear polarizing plate to make the outgoing light circularly polarized.

The linear polarizing plate is a functional layer having a function of allowing light vibrating in the 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 such as iodine is adsorbed to the PVA-based film oriented by stretching or stretched in a state adsorbed by PVA, whereby the dichroic dye is oriented and polarizing performance is exhibited. In the production of the film polarizer, other steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be provided. The stretching and dyeing process may be performed by the PVA-based film alone, or may be performed in a state of being laminated with another film 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 that exhibits 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 be thinner than 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 film can be produced, for example, by applying an alignment film-forming composition on a substrate and imparting alignment by rubbing, polarization 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 photo-alignment is applied, it is preferable to use an alignment 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, transferred, and 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 used, a cycloolefin derivative having a monomer unit including polyethylene, polypropylene, polymethylpentene, norbornene or cycloolefin, etc. (Modified) celluloses such as polyolefins, diacetyl cellulose, triacetyl cellulose and propionyl cellulose, 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, polyarylate Polyesters such as polyesters, polyamides such as nylon, polyimides, polyamideimides, polyetherimides, polyethersulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, Films, such as epoxy resins, are mentioned, From the viewpoint of being excellent in transparency and heat resistance, Preferably, polyamide, polyamide-imide, polyimide, polyester, olefin, acrylic, or a cellulose film is mentioned. These polymers may be used alone or in combination of two or more. Such a film is used as 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. If necessary, 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, and the like may be included. 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, it is difficult to reduce the flexibility of the protective film.

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, and preferably 1 to 100 µm. When the thickness is in the above range, the flexibility of the film tends to be 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 property of exhibiting a liquid crystal state such as nematic, cholesteric, and smectic. Any compound including a 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 produced 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 coating type retardation plate can be formed to have a thinner thickness compared to the stretched type 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 coated 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, that is, 100 to 180 nm, preferably 130 to be λ/4 for the vicinity of 560 nm with high luminous sensitivity. It is often designed to be -150 nm. It is preferable to use an inverse dispersion λ/4 retardation plate using a material having a birefringence wavelength dispersion characteristic opposite to that of the 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, for example, in the case of an elongated retardation plate, and Japanese Unexamined Patent Publication No. 2007-232873.

In addition, as another method, a technique for obtaining a broadband λ/4 retardation plate by combining it with a lambda /2 retardation plate is also known (Japanese Laid-Open Patent Publication No. Hei 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.

A method of laminating a positive C plate to the circular polarizing plate in order to increase visibility in an oblique direction is also known (Japanese Laid-Open Patent Publication No. 2014-224837). The positive C plate may 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 the 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 at an outer portion of the active area. The active area is an area in which the screen is displayed on the display panel, that is, an area corresponding to the display unit, and is an area in which a user's touch is sensed, and the inactive area is an area in which the screen is not displayed on the display device, that is, an area corresponding to the non-display unit. . 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 to the point of failure obtained through a tensile test of a polymer material.

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 each pattern must be electrically connected in order to sense a touched point. In the first pattern, each unit pattern is connected to each other through a seam, but the second pattern is a structure in which each unit pattern is separated from each other in the form of an island, so a separate bridge electrode is required to electrically connect the second pattern. I need this. 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 wire, 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 can 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 a layer structure covering the sensing pattern. In the latter case, the bridge electrode can 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 indices in these areas. As a means for, an optical control layer may be further included between the substrate and the electrode, 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 contain additives such as a photopolymerization initiator, a polymerizable monomer, and a curing aid.

[Adhesive layer]

Each layer, such as a window film, a polarizing plate, and a touch sensor, which forms 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 can be adhered with an adhesive. Examples of adhesives include water-based adhesives, organic solvent-based adhesives, solvent-free adhesives, solid adhesives, solvent vaporizing adhesives, moisture curing adhesives, heat curing adhesives, anaerobic curing adhesives, aqueous solvent vaporizing adhesives, active energy ray curing adhesives, and curing agent mixture adhesives. , Heat-melting adhesives, pressure-sensitive adhesives, pressure-sensitive adhesives, rewet-type adhesives, etc., which are generally used can be used. Among them, a water-based solvent volatilization adhesive, an active energy ray curable adhesive, and an adhesive are often used. The thickness of the adhesive layer can be appropriately adjusted according to 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 polymer in a water dispersion state such as a polyvinyl alcohol-based polymer, a water-soluble polymer such as starch, an ethylene-vinyl acetate-based emulsion, and a 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 is injected between the adhered layers to bond the adhered layers and then dried to impart adhesiveness. In the case of using the aqueous 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 for forming 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 containing 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 cationic 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 or a cation polymerization initiator, and the like, and can be appropriately selected and used. Such a polymerization initiator is decomposed by at least one of active energy ray irradiation and heating, and generates 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 any of radical polymerization or cationic polymerization by irradiation with active energy rays can be used.

The active energy ray curing composition may further contain an ion scavenger, an antioxidant, a chain transfer agent, an adhesion imparting agent, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, a defoaming agent, a solvent, 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 layers and then bonded, and cured by irradiating with active energy rays through any or both adhered layers. By making it possible to bond. 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 for forming 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, depending on the main polymer, it is classified into an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive, and any one may be used. In addition to the main polymer, the pressure-sensitive adhesive may contain 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, or the like. 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. When using the pressure-sensitive adhesive, the thickness of the adhesive layer may be usually 1 to 500 µm, preferably 2 to 300 µm. When using the pressure-sensitive adhesive for forming 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 in the periphery of the flexible image display device and makes it difficult to visually recognize, 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 implementing color and a polymer such as an acrylic resin, an ester resin, an epoxy resin, polyurethane, or silicone. These may be used alone or as 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 light-shielding pattern is usually 1 to 100 µm, preferably 2 to 50 µm. In addition, it is also preferable to give a shape such as an inclination in the thickness direction of the shading 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.

<Measurement of weight average molecular weight>

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 stocked, and 10 mL of DMF (10 mmol/L lithium bromide) was added to completely dissolve. This solution was filtered through a chromatographic disk (pore size: 0.45 µm) to obtain a sample solution.

(2) Measurement conditions

Device: HLC-8020GPC

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

Eluent: DMF (10mmol/L lithium bromide added)

Flow: 1.0mL/min

Detector: RI detector

Column temperature: 40°C

Injection volume: 100μL

Molecular weight standard: standard polystyrene

<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 brightness (L ^* value)>

The brightness (L ^* ) value of the optical film was measured with a spectrophotometer ("V-670" manufactured by Nippon Spectrophotometer). After background measurement was performed without a sample, the optical film was set in a sample holder, transmittance was measured for light having a wavelength of 300 to 800 nm, and L ^* value was calculated.

<Measurement of thickness>

About 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 method of residual solvent>

Using TG-DTA (EXSTAR6000 TG/DTA6300 manufactured by SII Corporation), the polyamideimide resin film obtained in Example 1 and Comparative Example 1 was heated from 30°C to 120°C, and held at 120°C for 5 minutes, Then, it heated up to 400 degreeC at a temperature raising rate of 5 degreeC/min. The ratio of the reduction in the mass of the optical film at 120°C to 250°C with respect to the mass of the resin film at 120°C was calculated as the content of the solvent contained in the resin film (referred to as the amount of residual solvent). The amount of the residual solvent in the resin film represents the ratio of the solvent contained in the resin film to the mass of the resin film.

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

Using "Ultra Microtome EM UC6" manufactured by Leica Microsystems, 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: "TOF.SIMS V" manufactured by ION-TOF

(2) Primary ion: Bi ³⁺⁺

(3) Acceleration voltage of primary ions: 25kV

(4) Irradiation ion current: 0.23pA

(5) Measurement conditions: In bunching (high mass resolution) mode, cation and anion are measured.

(6) Measurement range: 200㎛×200㎛

The data analysis of TOF-SIMS used Surface Lab. Mass calibration of the measurement data was performed, and the integral value of the peak was calculated for each of the peaks attributable to Na ions, K ions, and CH ₃ ions. To the integral of the peaks of the Na ion the integrals of the peak of the Na in the ionic strength of I _Na, K ion strength of the integrals of the peak of the ion K I _K, CH ₃ ions, the ionic strength I _CH3 of CH _3, non- I _Na /I _CH3 and ratio I _K /I _CH3 were calculated.

<Impact resistance test>

(Preparation of samples for impact resistance evaluation)

In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 97.0 parts by mass of n-butyl acrylate, 1.0 parts by mass of acrylic acid, 0.5 parts by mass of 2-hydroxyethyl acrylate, 200 parts by mass of ethyl acetate, and 0.08 parts by mass of 2,2'-azobisisobutyronitrile was added, and the air in the reaction vessel was replaced with nitrogen gas. While stirring under a nitrogen atmosphere, the reaction solution was heated to 60° C., reacted for 6 hours, and then cooled to room temperature. When the weight average molecular weight of a part of the obtained solution was measured, formation of 1,800,000 (meth)acrylic acid ester polymer was confirmed.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step (solid content conversion value; the same below), and as an isocyanate-based crosslinking agent, trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, brand name ``Coronate (registered trademark)) L") 0.30 parts by mass and 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name "KBM403") as a silane coupling agent were mixed, sufficiently stirred, and ethyl acetate was used. By diluting, a coating solution of the pressure-sensitive adhesive composition was obtained.

The coating solution was applied to the release treatment surface (peel layer surface) of a separator (Lintec Co., Ltd.: SP-PLR382190) with an applicator so that the thickness after drying became 25 μm, and then dried at 100° C. for 1 minute, Another separator (manufactured by Lintec Co., Ltd.: SP-PLR381031) was bonded to the side opposite to the side on which the separator of the pressure-sensitive adhesive layer was bonded to obtain a pressure-sensitive adhesive layer having a double-sided separator.

A pressure-sensitive adhesive layer is formed by attaching a pressure-sensitive adhesive layer to glass from a pressure-sensitive adhesive layer having a double-sided separator, and the optical films obtained in Examples and Comparative Examples are bonded on the pressure-sensitive adhesive layer, and glass, pressure-sensitive adhesive layer, and optical film A laminate (sample for impact resistance evaluation) laminated in this procedure was obtained.

(Impact resistance evaluation)

Impact resistance was evaluated. Specifically, a weight was dropped from a height of 10 cm on the optical film surface of the layered product (sample for impact resistance evaluation) to produce a recess. The weight has a mass of 4.6 g, and a point colliding with the surface of the optical film has a spherical shape of 0.75 mm in diameter and is made of stainless steel. Subsequently, the shape of the dent on the surface of the optical film was observed using an optical interference film thickness meter (manufactured by Ryoka Systems Co., Ltd., ``Micromap (MM557N-M100 type)''), and the shape of the dent before the test was not observed. The depth of the largest dent point (shortest distance from the film surface in the non-depressed state before the test to the largest dent point) was measured based on the film surface of. The measurement was repeated three times, and the average value of the depth of the depression was taken as the amount of the depression in the impact resistance test.

<Measurement of viscosity>

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

Apparatus: Brookfield viscometer (DV2THBCJO)

Measurement temperature: 25℃

Spindle: CPA-52Z

Sample volume: 0.5mL

Rotor rotation speed: 3rpm

<Synthesis Example 1: Preparation of polyamideimide resin (1)>

Nitrogen was passed through the reaction vessel equipped with a sufficiently dried stirrer and thermometer, and the inside of the vessel was replaced with nitrogen. In the 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, after adding 37.66 parts by mass of acetic anhydride and stirring for 15 minutes, 11.45 parts by mass of 4-picoline was added, and the reaction vessel was heated to 70° C. and stirred for 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 passed through the reaction vessel equipped with a sufficiently dried stirrer and thermometer, and the inside of the vessel was replaced with nitrogen. 529.0 parts by mass of DMAc and 14.64 parts by mass (45.72 mmol) of TFMB were added to the reaction vessel, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 6.15 parts by mass (13.85 mmol) of 6 FDA and 1.36 parts by mass (4.62 mmol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) were added, and at room temperature for 16 hours. Stirred. Next, 2.53 parts by mass (12.47 mmol) of TPC was added and stirred for 10 minutes, and then 2.58 parts by mass (12.47 mmol) of TPC were further added and stirred for 20 minutes. Further, 0.56 parts by mass (2.77 mmol) of TPC was added, followed by stirring at room temperature for 2 hours.

Then, 2.58 parts by mass (27.70 mmol) of 4-picoline and 13.21 parts by mass (129.40 mmol) 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 further The mixture was stirred for 3 hours to obtain a reaction solution.

When the reaction liquid was cooled and lowered to 40°C or less, 954 parts by mass of methanol was added, and then 360 parts by mass of ion-exchanged water was added dropwise to precipitate a white solid. The white solid precipitated 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 room temperature under reduced pressure to obtain a powder of a polyamideimide resin. The weight average molecular weight of the obtained polyamideimide resin (2) was 260,000.

<Preparation of solution containing sodium-containing component>

Sodium ethoxide ethanol solution (manufactured by Fujifilm Wako Pure Chemical Co., Ltd.) containing 20% by mass of sodium ethoxide (a compound containing a sodium atom, also referred to as ``NaOEt'' hereinafter) as a sodium-containing component Was diluted with DMAc to prepare a solution containing sodium ethoxide at a concentration of 0.1% by mass (hereinafter also referred to as "NaOEt solution").

<Preparation of a solution containing a potassium-containing component>

As a potassium-containing component, a THF solution of t-BuOK containing 1 mol% of potassium tert-butoxide (a compound containing a potassium atom, also referred to as ``t-BuOK'' below) (Fujifilm Wako Pure Chemical Co., Ltd. ) Agent) was diluted with DMAc to prepare a solution containing t-BuOK at a concentration of 0.2% by mass (hereinafter also referred to as “t-BuOK solution”).

<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. Thereto, the NaOEt solution and t-BuOK solution prepared as described above were added so that the peak intensity of TOF-SIMS shown in Table 1 was added 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”), followed by 30 minutes at 50° C., 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. The amount of residual solvent in the polyamideimide resin film (1) was 0.7%.

<Example 2>

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. Thereto, the NaOEt solution and t-BuOK solution prepared as described above were added so that the peak intensity of TOF-SIMS shown in Table 1 was added to prepare a polyamideimide resin composition (varnish for film formation). Except having used the resin composition thus obtained, it carried out similarly to Example 1, and obtained the 50 micrometers-thick polyamide-imide resin film (2).

<Example 3>

The polyamideimide resin (2) and DMAc obtained in Synthesis Example 2 were mixed in an amount such that the content ratio of the polyamideimide resin in the resin composition was 11.0% by mass. Thereto, the NaOEt solution and t-BuOK solution prepared as described above were added so that the peak intensity of TOF-SIMS shown in Table 1 was added to prepare a polyamideimide resin composition (varnish for film formation). Except having used the resin composition thus obtained, it carried out similarly to Example 1, and obtained the polyamide-imide resin film (3) of 50 micrometers in thickness.

<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. Except having used the resin composition thus obtained, it carried out similarly to Example 1, and obtained the 50 micrometers-thick polyamide-imide resin film (4). The amount of residual solvent in the polyamideimide resin film 4 was 0.7%.

<Comparative Example 2>

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. There, the NaOEt solution prepared as described above was added so that the peak intensity of TOF-SIMS shown in Table 1 was added to prepare a polyamideimide resin composition (varnish for film formation). Except having used the thus obtained resin composition, it carried out similarly to Example 1, and obtained the 50 micrometers-thick polyamide-imide resin film (5).

<Comparative Example 3>

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. Thereto, the t-BuOK solution prepared as described above was added so that the peak strength of TOF-SIMS shown in Table 1 was added to prepare a polyamideimide resin composition (varnish for film formation). Except having used the thus obtained resin composition, it carried out similarly to Example 1, and obtained the 50 micrometers-thick polyamide-imide resin film (6).

<Comparative Example 4>

The polyamideimide resin (2) and DMAc obtained in Synthesis Example 2 were mixed in an amount such that the content ratio of the polyamideimide resin in the resin composition was 11.0% by mass. A polyamideimide resin film (7) having a thickness of 50 µm was obtained in the same manner as in Example 1 except that the resin composition thus obtained was used.

The results of measuring various physical properties of the polyamideimide resin films (1) to (7) obtained in Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Tables 1 and 2.

<Example 4>

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. Thereto, the content ratio of sodium chloride (manufactured by Fujifilm Wako Pure Chemical Co., Ltd.) is 0.05% by mass, and the content ratio of potassium chloride (manufactured by Fujifilm Wako Pure Chemical Co., Ltd.) is 0.06% by mass. A mid resin composition was prepared.

<Reference Example>

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. Thereto, the content ratio of potassium chloride (manufactured by Fujifilm Wako Pure Chemicals Co., Ltd.) was mixed in an amount of 0.12% by mass to prepare a polyamideimide resin composition.

For each of the polyamideimide resin compositions obtained in Examples 2 to 4, Comparative Examples 1 and 4, and Reference Example, the viscosity was measured according to the above measurement method. Table 3 shows the obtained results.

As shown in Tables 1 and 2, the ratio of the ionic strength by TOF-SIMS (I _Na / I _CH3 ) to which NaOEt and t-BuOK were added to the varnish was 0.2 or more, and the ratio (I _K / I It was confirmed that the optical films of Examples 1 to 3 having a _CH3 ) of 0.2 or more had a small amount of dents in the impact resistance test and high impact resistance. On the other hand, in the case of the optical films of Comparative Examples 1 and 4 in which neither NaOEt nor t-BuOK was added to the varnish, and Comparative Examples 2 and 3 in which only one of them was added and the other was not added, the impact resistance test was performed. The resulting dents were large, and sufficient impact resistance was not obtained. Although the cause of the increase in the impact resistance of the optical film to which a certain amount of NaOEt and t-BuOK is added is not clear, the sodium-containing component and potassium-containing component having different atomic radii, ionic radii, or molecular size coexist in the resin, thereby preventing packing between the resins. It is expected to be strengthened further. It may be considered that the impact resistance of the resulting optical film is improved by such an action, but this consideration does not limit the present invention at all.

Claims (13)

An optical film comprising at least one resin selected from the group consisting of a polyimide resin and a polyamide resin, which is obtained by a time-of-flight secondary ion mass spectrometry of the optical film, and the ionic strength of CH ₃ (I The ratio of the ionic strength of Na to _CH3 (I _Na ) (I _Na / I _CH3 ) is 0.2 or more, and the ratio of the ionic strength of K to the ionic strength of CH ₃ (I _CH3 ) (I _K ) ( I _K /I _CH3 ) of 0.2 or more, optical film. The method of claim 1,
The optical film, wherein 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 unit 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,
The brightness (L ^* ) of the optical film is 90 or more, the optical film. 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. (a) a resin comprising at least one resin selected from the group consisting of polyimide resins and polyamide resins, at least one sodium-containing component, at least one potassium-containing component, and a solvent The step of preparing a composition, wherein the sodium-containing component is selected from the group consisting of a compound containing a sodium atom, sodium and sodium ions, and the potassium-containing component is a compound containing a potassium atom, potassium and potassium ions. Is selected from the group consisting of,
(b) forming a coating film by applying the resin composition to a support material, and
(c) drying the coating film to form an optical film
The manufacturing method of the optical film in any one of Claims 1-9 containing at least.