KR20210055621A - Polyamideimide resin, optical film and flexible display device - Google Patents

Abstract

The present invention relates to an optical film inhibited from degradation of optical and mechanical properties with time and having excellent quality stability, and a polyamideimide resin which provides the optical film. The polyamideimide resin shows that a ratio of the integral value (int_A) of peaks present in a region (A) showing a proton chemical shift of 8.06-8.14 ppm and a carbon chemical shift of 129.6-130.3 ppm to the integral value (int_B) of peaks present in a region (B) showing a proton chemical shift of 7.26-7.85 ppm and a carbon chemical shift of 132.4-134.0 ppm is 1.5% or less, in the ^1H-^13C HSQC spectrum obtained by using a deuterated dimethyl sulfoxide solution of the polyamideimide resin as a sample.

Description

Polyamideimide resin, optical film, and flexible display device TECHNICAL FIELD

The present invention relates to a polyamide-imide resin, an optical film containing a polyamide-imide resin, and a flexible display device including the optical film.

Currently, display devices such as a liquid crystal display device and an organic EL display device are widely used not only for television but also for various purposes such as mobile phones and smart watches. Conventionally, glass has been used as a front plate of such a display device. However, while glass has high transparency and can exhibit high hardness depending on its type, it is very rigid and fragile, so it is difficult to use it as a front plate material for a flexible display device.

Therefore, utilization of a polymer material as a material instead of glass is being studied. Since the front plate made of a polymer material tends to exhibit flexible properties, it is expected to be used for various purposes. As one of the flexible polymeric materials, for example, an optical film using a polyamideimide resin has been studied (Patent Document 1).

Japanese Patent Publication No. 2015-521686

When an optical film containing a polyamideimide resin is used, for example, in a flexible display device, it is required to satisfy various properties such as optical properties and mechanical properties. However, when the flexible display device provided with the optical film is used for a long period of time, depending on the environment in which the flexible display device is placed, the optical film deteriorates and the optical properties and mechanical properties deteriorate over time. I knew there was.

Accordingly, it is an object of the present invention to provide an optical film excellent in quality stability in which a decrease in optical properties and mechanical properties over time is suppressed, and a polyamideimide resin for providing the optical film.

In order to solve the above problems, the inventors of the present invention conducted a thorough study. When ^{the peak volume of a specific peak in the 1} H- ¹³ C HSQC spectrum of the polyamideimide resin satisfies a specific relationship, the polyamideimide resin was It was discovered that the quality stability of the included optical film could be improved, and the present invention was completed.

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

[1] In the polyamide-deuterated dimethyl sulfoxide solution of the resins in H- ¹³ C HSQC spectrum obtained by ¹ as a measurement sample, and the proton chemical shift that 8.06~8.14 ppm, Also, the chemical shift of the carbon 129.6~ _{The integral value (int A} ) of the peak present in the region (A) of 130.3 ppm and the chemical shift of the proton is 7.26 to 7.85 ppm, and the chemical shift of carbon is present in the region (B) of 132.4 to 134.0 ppm. The polyamideimide resin, wherein the ratio of the integral value (int _B ) of the _{peak (int A} /int _B ) is 1.5% or less.

(2) Equation (1):

[Formula 1]

[In formula (1), Y represents a tetravalent organic group,

X represents a divalent organic group,

* Represents a bond hand]

The structural unit represented by, and, formula (2):

[Formula 2]

[In formula (2), Z and X each independently represent a divalent organic group,

* Represents a bond hand]

The polyamideimide resin according to [1], which has at least a structural unit represented by.

[3] The polyamideimide resin according to [1] or [2], having a weight average molecular weight of 200,000 or more and 1,000,000 or less.

[4] As X in formula (1) or X in formula (2), formula (4):

[Formula 3]

[In formula (4), H ^4a and H ^4b represent a hydrogen atom,

R ^4a to ^{R 4d} 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 4a} to ^{R 4d are,} Independently of each other, they may be substituted with a halogen atom,

* Represents a bond hand]

The polyamideimide resin according to any one of the above [1] to [3], having at least a structure represented by.

[5] As Z in formula (2), formula (3):

[Formula 4]

[In formula (3), R ^3a and R ^3b represent, independently of each other, 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 are included in ^{R 3a} and R ^3b The hydrogen atoms used may be independently of each other and may be substituted with a halogen atom,

W 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⁾ - represents a, R ⁹ represents a monovalent hydrocarbon group having 1 to 12 carbon atoms that may be substituted by a hydrogen atom, a halogen atom ,

s is an integer from 0 to 4,

t is an integer from 0 to 4,

u is an integer from 0 to 4,

* Represents a bond hand]

The polyamideimide resin according to any one of the above [1] to [4], which has at least a structure represented by.

[6] An optical film containing the polyamideimide resin according to any one of [1] to [5].

[7] An optical film containing a polyamideimide resin, wherein the optical film has a rate of change of 26% or less in the weight average molecular weight before and after a storage test in which the optical film is stored for one week under conditions of 85°C and 85% humidity.

[8] The optical film according to [7], wherein a rate of change of the weight average molecular weight before and after the storage test is 25% or less.

[9] A front plate of a flexible display device having the optical film according to any one of [6] to [8].

[10] A flexible display device comprising the front plate according 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 method for producing a polyamideimide resin in which a diamine compound, a tetracarboxylic acid compound and a dicarboxylic acid compound are reacted, wherein the ratio of the number of moles of the diamine compound to the total number of moles of the tetracarboxylic acid compound and the dicarboxylic acid compound The method for producing a polyamideimide resin according to any one of the above [1] to [5], which exceeds 1.000.

Advantageous Effects of Invention According to the present invention, an optical film excellent in quality stability in which deterioration in optical properties and mechanical properties over time is suppressed, and a polyamideimide resin giving the optical film can be provided.

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

[Polyamideimide resin]

The polyamideimide resin of the present invention has a proton chemical shift of 8.06 to 8.14 ppm in ^{a 1} H- ¹³ C HSQC spectrum obtained using a deuterated dimethyl sulfoxide solution of a polyamide imide resin as a measurement sample, and carbon _{The integral value (int A} ) of the peak present in the region (A) in which the chemical shift of is 129.6 to 130.3 ppm, the chemical shift of the proton is 7.26 to 7.85 ppm, and the chemical shift of the carbon is 132.4 to 134.0 ppm The ratio (int _A /int _B ) of the integral value (int _B ) of the peak present in (B) is 1.5% or less.

¹ H- ¹³ C Heteronuclear Single Quantum Correlation (HSQC) spectrum is an NMR spectrum showing heteronuclear coupling between a proton and carbon, and usually, in the spectrum, the vertical axis represents the chemical shift of carbon, and the horizontal axis It shows the chemical shift of this proton. _{In the present inventors, the integral value (int A} ) of the peak present in the region (A) where the chemical shift of proton is 8.06 to 8.14 ppm and the chemical shift of carbon is 129.6 to 130.3 ppm, and the chemical shift of proton are 7.26 _A polyamideimide resin having a ratio (int A /int _B ) of 1.5% or less of _{the peak integral value (int B} ) present in the region (B) where the chemical shift of carbon is -7.85 ppm and the carbon chemical shift is 132.4 to 134.0 ppm By using it, it was found that it is possible to provide an optical film excellent in quality stability in which a decrease in optical properties and mechanical properties over time is suppressed. When the ratio (int _A /int _B ) exceeds 1.5%, the optical film containing the resin tends to deteriorate over time in optical properties and mechanical properties. The ratio (int _A /int _B ) is preferably 1.2% or less, more preferably 1.0% or less, further preferably 0.8% from the viewpoint of more easily improving the suppression effect of the decrease in optical properties and mechanical properties. Or less, particularly preferably 0.6% or less. The smaller the ratio (int _A /int _B ) is, the more preferable, and the lower limit thereof is not particularly limited, and is usually 0 or more, for example, 0.01% or more.

When the ratio (int _A /int _B ) is 1.5% or less, the reason why the decrease in optical properties and mechanical properties of the obtained optical film over time can be suppressed is not clear, but it is considered to be due to the reasons described later. The polyamideimide resin is usually obtained by polymerization using a tetracarboxylic acid compound, a dicarboxylic acid compound, and a diamine compound as monomers. In addition, depending on the ratio of the monomer to be polymerized and the polymerization conditions of the polymer, a carboxylic acid moiety derived from dicarboxylic acid may remain at the terminal of the obtained polymer. Here, in the region (A) in which the chemical shift of proton is 8.06 to 8.14 ppm in the ¹ H- ^{13 C HSQC spectrum and the chemical shift of carbon is 129.6 to 130.3 ppm, polyamide originating from dicarboxylic acid} It is thought that there is a proton peak corresponding to the amount of the carboxylic acid moiety present at the terminal of the mid resin. Therefore, the integral value (volume of the peak) of the peak present in the region (A), which relatively represents the abundance of the carboxylic acid moiety derived from the terminal dicarboxylic acid, corresponds to the proton of the other part of the polyamideimide resin. With respect to the integral value of the peak present in the region (B), when it is less than or equal to a predetermined value, it indicates that the amount of the carboxylic acid moiety present at the end of the polyamideimide resin is very small, and the optical properties and mechanical properties of the resulting optical film It is thought that the deterioration of the characteristic over time can be suppressed. When the optical film is used for a long period of time, it is considered that the optical properties and mechanical properties may deteriorate over time due to erosion caused by external environments or the like, particularly from the surface of the optical film. When the amount of the carboxylic acid moiety present at the end of the polyamideimide resin contained in the optical film is small, erosion of the surface of the optical film, for example, under high temperature and high humidity conditions can be reduced, and such reduction of erosion is possible. , It is considered to be one cause of suppression of deterioration of optical properties and mechanical properties over time. Further, for the same reason, _{an optical film obtained from a resin having a ratio (int A} /int _B ) of 1.5% or less can also suppress a decrease in the weight average molecular weight over time.

Int _A ratio of the _(A int / int _B) is, as described above, the amount of polyamide-terminal carboxylic acid portion of the dicarboxylic acid present at the terminal of the imide resin becomes large when a lot. Therefore, by synthesizing the polyamideimide resin so that the number of terminal carboxylic acid moieties derived from dicarboxylic acid becomes as small as possible, the above ratio can be adjusted to a range of 1.5% or less. As an example of a method of synthesizing a polyamideimide resin so that the terminal carboxylic acid moiety is as small as possible, when synthesizing a polyamideimide resin, among the dicarboxylic acid compounds, a compound that is low in reactivity and tends to become a terminal carboxylic acid is first used. It is conceivable to add or to make the molar amount of the diamine monomer higher than the total molar amount of dicarboxylic acid and tetracarboxylic acid. Specifically, for example, in order to obtain a polyamideimide resin, when copolymerizing a tetracarboxylic acid compound, a dicarboxylic acid compound, and a diamine compound, when the total molar amount of the tetracarboxylic acid compound and the dicarboxylic acid compound is 1 The ratio of the molar amount of the diamine compound (molar amount of the diamine compound/(the total molar amount of the tetracarboxylic acid compound and the dicarboxylic acid compound), this ratio is also referred to as ``amine ratio'' hereinafter) is preferably 1.000 or more, more When the ratio is adjusted to be preferably 1.003 or more, more preferably 1.005 or more, even more preferably 1.008 or more, and particularly preferably 1.01 or more, the ratio (int _A /int _B ) is easily adjusted to the above range. The upper limit of the amine ratio is preferably 1.05 or less, more preferably 1.03 or less, and still more preferably 1.02 or less, from the viewpoint of easily increasing the weight average molecular weight of the polyamideimide resin.

_{Further, the ratio (int A} /int _B ) can be adjusted within the above range also by adjusting the water content in the solvent used when synthesizing the polyamideimide resin. Specifically, when a certain amount of water is present in the solvent, a part of the dicarboxylic acid compound in the synthesis solvent is deactivated, making it difficult to introduce into the polyamideimide resin. As a result, when a certain amount of water is present in the solvent, the abundance of the dicarboxylic acid-derived carboxylic acid moiety present at the terminal of the polyamideimide resin can be reduced, and the ratio (int _A /int _B ) is within the above range. It is thought that it becomes easy to adjust with. From the viewpoint of being easy to adjust the ratio (int _A /int _B ) to the above range, the water content in the solvent used when synthesizing the polyamideimide resin is preferably 400 ppm or more, more preferably 500 ppm or more. , From the viewpoint of suppressing decomposition of the polyamideimide resin, it is preferably 1,000 ppm or less, and more preferably 800 ppm or less.

_{Moreover, the ratio (int A} /int _B ) can be adjusted to the above range also by adjusting the imidization temperature increase rate. Specifically, when synthesizing a polyamideimide resin, if the imidation temperature rise rate is too fast, the imidation catalyst cannot sufficiently trap all of the hydrochloric acid in the synthesis solvent, and this hydrochloric acid decomposes the polyamideimide resin, The carboxylic acid moiety derived from a dicarboxylic acid compound tends to exist at the terminal of the polyamideimide resin. _{Therefore, the ratio (int A} /int _B ) can be adjusted within the above range by adjusting the rate of temperature increase during imidization and suppressing decomposition of the polyamideimide resin. From the viewpoint of being easy to adjust the ratio (int _A /int _B ) to the above range, it is preferable to lower the rate of temperature increase during imidization, and it is more preferable to take 30 minutes or more to increase the temperature from 10°C to 50°C. Do.

Further, also by adjusting the heating conditions during the reaction, the ratio (int _A /int _B ) can be adjusted within the above range. Specifically, when synthesizing the polyamideimide resin, in order to achieve the same heating rate, by heating the reaction vessel locally rather than heating the entire reaction vessel, decomposition of the main chain of the polyamideimide resin is suppressed. , It was found that the hydrolysis of the terminal carboxylic acid was easy to proceed. Since the amine terminal is exposed instead of the carboxylic acid at the terminal, the ratio (int _A /int _B ) can be adjusted within the above range. When synthesizing the polyamideimide resin, when the entire reaction vessel is heated with a heat medium, the amount of the reaction solution heated excessively increases, and not only the hydrolysis of the carboxylic acid at the end of the resin, but also the decomposition of the main chain proceeds. As a result, _{it is considered because it becomes difficult to adjust the ratio (int A} /int _B ) to the above range, and a decrease in molecular weight tends to occur. When the reaction vessel is heated locally, hydrolysis of the carboxylic acid terminal, which is more reactive than that of the main chain, occurs preferentially, while reducing the decomposition of the main chain of the polyamideimide resin, and the ratio (int _A /int _B ) It is thought that it is easy to adjust to the above range.

In a preferred embodiment of the present invention, the polyamideimide resin is formula (1):

[Formula 5]

[In formula (1), Y represents a tetravalent organic group,

X represents a divalent organic group,

* Represents a bond hand]

Structural unit represented by and formula (2):

[Formula 6]

[In formula (2), Z and X are independently of each other,

Represents a divalent organic group,

* Represents a bond hand]

It has at least a structural unit represented by.

The structural unit represented by formula (1) is a structural unit formed by a reaction of a tetracarboxylic acid compound and a diamine compound, and the structural unit represented by formula (2) is a structural unit formed by a reaction of a dicarboxylic acid compound and a diamine compound. It is a constituent unit. When the polyamideimide resin has a structural unit represented by formula (1) and a structural unit represented by formula (2), the polyamideimide resin usually has a plurality of structural units represented by formula (1) and a formula ( It has a plurality of structural units represented by 2). The plurality of structural units represented by formula (1) may be one type of structural unit or two or more types of structural units. Moreover, a plurality of structural units represented by Formula (2) may also be one type of structural unit or two or more types of structural units. In addition, the polyamideimide resin may have additional structural units different from formulas (1) and (2).

In the above formula (2), Z is a divalent organic group, preferably 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 (the hydrogen atom in these groups Is a divalent organic group having 4 to 40 carbon atoms, which may be substituted by a halogen atom, preferably a fluorine atom, more preferably an alkyl group having 1 to 6 carbon atoms, An alkoxy group or an aryl group having 6 to 12 carbon atoms (the hydrogen atom in these groups may be substituted with a halogen atom, preferably a fluorine atom). It represents a divalent organic group. In addition, as an example of a C1-C6 alkyl group, a C1-C6 alkoxy group, or a C6-C12 aryl group, the example ^{concerning R 3a} and R ^3b in Formula (3) mentioned later fits similarly. 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 (28) and Equation (29):

[Formula 7]

[In formulas (20) to (29), W ¹ is 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-, wherein Ar is independently of each other, an arylene group having 6 to 20 carbon atoms in which a hydrogen atom may be substituted with a fluorine atom, For example, a phenylene group is represented, and * represents a bonding hand]

Among the bond hands of the group represented by, a group in which two non-adjacent hydrogen atoms are substituted and a divalent chain hydrocarbon group having 6 or less carbon atoms are exemplified, and a group having a thiophene ring skeleton is illustrated as the heterocyclic structure of Z. As Z, a group represented by formulas (20) to (29), and a thiophene ring skeleton, from the viewpoint of being easy to reduce the yellowness of the optical film (hereinafter, it may be simply described as a YI value). A group having is preferred.

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 8]

[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 formulas (20) to (29) and formulas (20') to (29') is an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or 6 You may be substituted by the aryl group of -12 (the hydrogen atom in these groups may be substituted with a halogen atom, preferably a fluorine atom).

In the polyamideimide resin, when Z in formula (2) has a structural unit represented by any of the above formulas (20') to (29'), among them, Z in formula (2) is a formula ( In the case of having a structural unit represented by 3'), the polyamideimide resin is in addition to the structural unit, and the following formula (d1):

[Formula 9]

[In formula (d1), R ²⁴ represents a group or a hydrogen atom defined for ^{R 3a} in formula (3) described later,

R ²⁵ represents R ²⁴ or -C(=O)-*,

* Represents a bond hand]

It is preferable from the viewpoint that it is easy to increase the film-forming property of the varnish containing the said resin, and the uniformity of the optical film obtained is easy to have further a structural unit derived from a carboxylic acid represented by. As the structural unit (d1), specifically ^{, a structural unit in which both R 24} and R ²⁵ are hydrogen atoms, that is, a structural unit derived from a dicarboxylic acid compound, R ²⁴ is a hydrogen atom, and R ²⁵ is -C(= The structural unit representing O)-*, that is, the structural unit derived from a tricarboxylic acid compound, etc. are mentioned.

The polyamideimide resin of the present invention may contain a plurality of types of Z as Z in the formula (2), and the plurality of types of Z may be the same or different from each other. Among them, from the viewpoint of easy to increase the impact resistance of the optical film obtained by using the polyamideimide resin of the present invention, and also to increase the optical properties, Z in Formula (2) is preferably Formula (3):

[Formula 10]

[In formula (3), R ^3a and R ^3b represent, independently of each other, 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 are included in ^{R 3a} and R ^3b The hydrogen atoms used may be independently of each other and may be substituted with a halogen atom,

W 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 )-, and 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. ,

s is an integer from 0 to 4,

t is an integer from 0 to 4,

u is an integer from 0 to 4,

* Represents a bond hand]

, More preferably formula (3'):

[Formula 11]

[In formula (3'), R ^3a , R ^3b , s, t, u, W, and * are as defined in formula (3)]

It is preferable to have at least the structural unit represented by. In addition, in the present specification, wherein Z in formula (2) has a structural unit represented by formula (3), and polyamideimide resin is represented by formula (3) as Z in formula (2), Having a losing structure has the same meaning, and among the structural units represented by the plurality of formulas (2) contained in the polyamideimide resin, Z in at least some of the structural units is represented by the formula (3). it means. This description also applies to other similar descriptions.

In formulas (3) and (3'), W is each 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 Represents -O- or -S-, more preferably -O-.

R ^3a and R ^3b each independently represent a C 1 to C 6 alkyl group, a C 1 to C 6 alkoxy group, or a C 6 to C 12 aryl group. Examples of the C1-C6 alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, 2 -Methyl-butyl group, 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl group, etc. are mentioned. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, propyloxy group, isopropyloxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, pentyloxy group , A hexyloxy group, and a cyclohexyloxy group. 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 ^3a and R ^3b each independently represent an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. Here, ^{the hydrogen atoms contained in R 3a} and R ^3b may be each independently substituted with a halogen atom.

R ⁹ represents a C 1 to C 12 monovalent hydrocarbon group which may be substituted with a hydrogen atom or a halogen atom. 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, isobutyl group, sec-butyl group, tert-butyl group, n-phen Tyl group, 2-methyl-butyl group, 3-methylbutyl group, 2-ethyl-propyl group, n-hexyl, 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.

T and u in formulas (3) and (3') are, independently of each other, an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0 or 1, even more preferably 0 to be.

In formulas (3) and (3'), s is an integer in the range of 0 to 4, and if s is within this range, the impact resistance, elastic modulus, and bending resistance of the optical film obtained by using the polyamideimide resin of the present invention Easy to improve. In formulas (3) and (3'), s is an integer in the range of preferably 0 to 3, more preferably 0 from the viewpoint of more easily improving the impact resistance, elastic modulus, and bending resistance of the resulting optical film. It is an integer in the range of 2, more preferably 0 or 1, particularly preferably 0. The structural unit containing the structure represented by formula (3) or formula (3') in which s is 0 as Z in formula (2) is, for example, a structural unit derived from terephthalic acid or isophthalic acid, and the structural unit In particular, it is preferable that it is a structural unit containing a structure in which s is 0 and u is 0 in Formula (3) or Formula (3'). From the viewpoint of being easy to improve the impact resistance, elastic modulus, and bending resistance of the optical film, it is preferable that the polyamideimide resin contains a structural unit derived from terephthalic acid. The polyamideimide resin may contain one type or two or more types of structural units in which Z is represented by formula (3) or formula (3'). From the viewpoint of improving the impact resistance, elastic modulus and flexural resistance of the optical film, and reducing the YI value, the polyamideimide resin is Z in the formula (2), and the value of s in the formula (3) or (3') is different. It is preferable to contain more than a kind of structure, and it is more preferable to contain two types or three types of structures different in the value of s in Formula (3) or Formula (3'). In this case, from the viewpoint of being easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint of being easy to reduce the YI value of the optical film, the polyamideimide resin is in the structural unit represented by formula (2). As Z of, it contains a structure represented by formula (3) in which s is 0, and in addition to the structural unit including the structure, a structural unit including a structure represented by formula (3) in which s is 1 It is particularly preferred to contain. Moreover, it is also preferable to further have a structural unit represented by the said formula (d1) in addition to the structural unit represented by Formula (2) which has Z represented by Formula (3) in which s is 0.

In a preferred embodiment of the present invention, the polyamideimide resin has a structure (divalent group) represented by formula (3) or formula (3'), s=0, and u=0. . In a more preferred embodiment of the present invention, the polyamideimide resin is a structure represented by formula (3) or formula (3'), wherein s = 0 and u = 0, and formula (3") :

[Formula 12]

It has a structure represented by In this case, while it is easy to improve the impact resistance, elastic modulus, and bending resistance of the optical film obtained by using the polyamideimide resin, it is easy to reduce the YI value.

When the polyamideimide resin of the present invention has a structural unit in which Z in formula (2) is represented by formula (3) or formula (3'), the ratio is represented by formula (1) of polyamideimide resin. When the sum of the constitutional units and the constitutional 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, more It is more preferably 50 mol% or more, particularly preferably 60 mol% or more, preferably 90 mol% or less, more preferably 85 mol% or less, still more preferably 80 mol% or less. When Z in Formula (2) is the ratio of the structural unit represented by Formula (3) or Formula (3') is more than the said lower limit, it is easy to improve the impact resistance, elastic modulus, and bending resistance of an optical film. If Z in formula (2) is less than or equal to the upper limit of the structural unit represented by formula (3) or formula (3'), the viscosity of resin-containing varnish is increased by hydrogen bonding between amide bonds derived from formula (3). And it is easy to improve the workability of the film.

Further, when the polyamideimide resin has a structure represented by formula (3) or formula (3') in which s=1-4 as Z in formula (2), formula (3) or formula in which s is 1-4 The ratio of the structural unit represented by formula (2) having Z represented by (3') is the sum of the structural unit represented by formula (1) and the structural unit represented by formula (2) of the polyamideimide resin. In the case of 100 mol%, preferably 3 mol% or more, more preferably 5 mol% or more, more preferably 7 mol% or more, particularly preferably 9 mol% or more, preferably 90 mol% or less , More preferably 70 mol% or less, still more preferably 50 mol% or less, particularly preferably 30 mol% or less. Impact resistance, elastic modulus, and bending resistance of the optical film if the ratio of the structural unit represented by the formula (2) having Z represented by the formula (3) or formula (3') in which s is 1 to 4 is equal to or greater than the above lower limit Easy to increase. Formula (3) or formula (3') if the ratio of the structural unit represented by formula (2) having Z represented by formula (3) or formula (3') in which s is 1 to 4 is less than or equal to the above upper limit It is easy to suppress an increase in the viscosity of the resin-containing varnish due to hydrogen bonding between amide bonds derived from the structure represented by and improve the processability of the film. In addition, the ratio of the structural units in which Z in formulas (1), (2), and (2) is represented by formula (3) or formula (3') is ^{measured using, for example, 1} H-NMR. It can be done, or it can also be calculated from the introduction ratio of the raw material.

In a preferred embodiment of the present invention, Z in the polyamideimide resin of the present invention 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 represented by formula (3) or formula (3') in which s is 0 to 4. When the above lower limit of Z is represented by the formula (3) or (3') in which s is 0 to 4, it is easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film. Further, 100 mol% or less of Z in the polyamideimide resin may be represented by formula (3) or formula (3') in which s is 0 to 4. In addition, the ratio of the structural unit represented by Formula (2) having Z represented by Formula (3) or Formula (3') in which s is 0 to 4 in the resin is, for example, ¹ H-NMR. It can be measured, or it can also be calculated from the introduction ratio of the raw material.

In a preferred embodiment of the present invention, Z in the polyamideimide resin of the present invention 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 (3') in which s is 1 to 4. When the above lower limit of Z of the polyamideimide resin is represented by formula (3) or formula (3') in which s 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 ) Or formula (3'). When the above upper limit of Z is represented by formula (3) in which s is 1 to 4, hydrogen between amide bonds derived from a structural unit represented by formula (3) or formula (3') wherein s is 1 to 4 It is easy to suppress an increase in the viscosity of the resin-containing varnish due to bonding and to improve the processability of the film. In addition, the ratio of the structural unit represented by formula (3) or formula (3') in which s is 1 to 4 in the resin ^{can be measured using, for example, 1} H-NMR, or from the introduction ratio of the raw material. It can also be calculated.

As a structure of a carboxylic acid terminal portion derived from a dicarboxylic acid compound in the polyamideimide resin of the present invention, for example, formula (32):

[Formula 13]

[In formula (32), R ^32a and R ^32b represent, independently of each other, 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 are included in ^{R 32a} and R ^32b The hydrogen atoms used may be independently of each other and may be substituted with a halogen atom,

R ^32c represents a hydrogen atom (in this case, -OR ^32c is -OH), an alkali metal atom, a halogen atom, or an alkyl group having 1 to 3 carbon atoms,

p is an integer from 0 to 4,

r is an integer of 0 to 4, preferably an integer of 0 to 2, more preferably 0,

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 )-, and 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. ,

q is an integer from 0 to 4,

* Represents a bond hand]

The structure represented by is mentioned. When the structure of the carboxylic acid terminal moiety is represented by formula (32) (preferably r=0, q=0, and the substitution position of the carboxylic acid group is para to the amide group), the carboxylic acid group (-C( It is thought that the peak attributable to the hydrogen atom bonded to the carbon atom on the benzene ring having =O)OR ^{32c) is detected in the region (A).} The structure of the carboxylic acid terminal moiety represented by formula (32) is the dicarboxylic acid and diamine in the dicarboxylic acid and diamine where Z in the formula (2) gives the structural unit represented by the above formula (3). It is a structure derived from a part of. Therefore, in the case where Z in the formula (2) has a structural unit represented by the above formula (3), the terminal structure represented by the formula (32) may be contained in the polyamideimide resin. Therefore, R ^3a , R ^3b , W, s, t and u in Formula (3) ^{can correspond to R 32a} , R ^32b , A, p, q and r in Formula (32), respectively.

In 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. 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 polyamideimide resin of the present invention 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, a group represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) and formula (18) ; A group in which a hydrogen atom in the groups represented by the above 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 14]

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, with respect to each ring, preferably a meta position or a para position, more preferably Is the para position.

Among the groups represented by formulas (10) to (18), formulas (13), (14), (15), and (16) from the viewpoint of being easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film. ) And a group represented by formula (17) are 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, from the viewpoint of easy to increase the impact resistance, elastic modulus and flexibility of the optical film. It is a single bond or -O-.

In a preferred embodiment of the present invention, the polyamideimide resin of the present invention is X in formula (1) or X in formula (2), wherein formula (4):

[Formula 15]

[In formula (4), H ^4a and H ^4b represent a hydrogen atom, and R ^4a to ^{R 4d} 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 12 aryl group is represented, and ^{the hydrogen atoms contained in R 4a} to ^{R 4d} may be each independently substituted with a halogen atom,

* Represents a bond hand]

It has a structure represented by When the polyamideimide resin has a structure represented by formula (4) as X in formula (1) or X in formula (2), peaks attributable to ^{H 4a} and H ^{4b in formula (4) are regions (} It is thought to be detected in B). In addition, the structural unit represented by formula (1) and the structural unit represented by formula (2) are present in plural in the polyamideimide resin. In at least a part of these structural units, when X in formulas (1) and (2) is represented by formula (4), it is easy to increase the impact resistance, elastic modulus, and transparency of the optical film.

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

[Formula 16]

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 polyamideimide 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 easily reduced, and the optical film It is easy to improve the workability of the. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element. When the polyamideimide resin contains a structure represented by Formula (4) or Formula (4') as X in Formula (1) or Formula (2), represented by H ^4a and H ^{4b in Formula (4)} It is considered that a peak attributable to a hydrogen atom or a hydrogen atom at the same position in the formula (4') is detected in the region (B).

In a preferred embodiment of the present invention, X in the polyamideimide resin is preferably 30 mol% or more, more preferably 50 mol% or more, and still more preferably 70 mol% or more of the formula (4), Among them, it is represented by formula (4'). When X in the above range in the polyamideimide resin is represented by formula (4), especially formula (4'), the resulting optical film increases the solubility of the resin in a solvent due to a skeleton containing a fluorine element. , It is easy to improve the storage stability of the varnish containing the resin, it is easy to reduce the viscosity of the varnish, and it is easy to improve the workability of the optical film. Moreover, it is easy to improve the optical properties of the optical film by the skeleton containing the fluorine element. Further, preferably, 100 mol% or less of X in the polyamideimide resin is represented by formula (4), particularly (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.

Formula (1) or Formula (2), wherein X in Formula (1) or Formula (2) is contained in addition to or in place of the structural unit represented by Formula (4) or Formula (4'). As a structural unit in which X in) is represented by other structural formulas, for example, X in formula (1) or formula (2) is formula (6):

[Formula 17]

[In formula (6), 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 R ¹⁰ to ^{R 17} The hydrogen atoms contained in may be each independently substituted with a halogen atom, provided ^{that any one of R 11} and R ¹² and any one of R ¹⁴ and R ¹⁷ are trifluoromethyl groups. Excluding cases,

* Represents a bond hand]

The structural unit represented by is mentioned. Even when at least a part of a plurality of X in formulas (1) and (2) is a group represented by formula (6), it is easy to improve the impact resistance, elastic modulus, and transparency of the optical film.

^{R 4a} , R ^4b , R ^4c and R ^{4d in} formula (4) ^{, and R 10} , R ¹¹ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R in formula (6) ¹⁷ independently of each other represents 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. 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 ^4a to ^{R 4d} and 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: The ^{hydrogen atoms contained in R 4a} to ^{R 4d} and R ¹⁰ to ^{R 17} may be each independently substituted with a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. R ^4a to ^{R 4d} and R ¹⁰ to ^{R 17} are each independently a hydrogen atom, a methyl group, a fluoro group, a chloro group or a tree from the viewpoint of impact resistance, elastic modulus, transparency, and bending resistance of the optical film. A fluoromethyl group, particularly preferably R ^{4a to R 4d} are a hydrogen atom, R ¹⁰ , R ¹² , R ¹³ , R ¹⁴ , R ¹⁵ and R ¹⁶ are a hydrogen atom, and R ¹¹ and R ¹⁷ are a hydrogen atom, It is a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group. However, in formula (6), the case ^{where any one of R 11} and R ¹² and any one of R ¹⁴ and R ¹⁷ becomes a trifluoromethyl group is excluded.

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 a cyclic structure and having 4 to 40 carbon atoms. As the cyclic structure, an alicyclic, an aromatic ring, and a heterocyclic structure can be mentioned, and from the viewpoint that the impact resistance and the elastic modulus are easily improved, 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 polyamideimide resin may contain a plurality of types of Y, and the plurality of types of Y may be the same or different from each other. As Y, the following formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula A group represented by (29); A group in which a hydrogen atom in the groups represented by the formulas (20) to (29) is substituted with a methyl group, a fluoro group, a chloro group, or a trifluoromethyl group; And a tetravalent C6 or less chain hydrocarbon group.

[Formula 18]

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

In a preferred embodiment of the present invention, of Y in the polyamideimide resin, preferably 50 mol% or more, more preferably 60 mol% or more, still more preferably 70 mol% or more, is represented by the formula (26). Is shown. In the polyamideimide resin, Y in the above range is formula (26), preferably W ¹ is a single bond, -C (CH ₃ ) ₂ -or -C (CF ₃ ) _2- Preferably, when W ¹ is a single bond or -C(CF ₃ ) ₂ -represented by 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 polyamideimide 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 19]

[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 substituted with a halogen atom,

* Represents a bond hand]

And/or Equation (9):

[Formula 20]

[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 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) As the aryl group of, those exemplified above can be mentioned. R ¹⁸ to ^{R 25} each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R ¹⁸ to ^{R 25} The hydrogen atoms contained may be independently of each other and 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. R ¹⁸ to ^{R 25} are, independently of each other, more preferably from the viewpoint of being easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint of being easy to increase transparency and easy to maintain the transparency. A hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and even more preferably R ¹⁸ , R ¹⁹ , R ²⁰ , R ²³ , R ²⁴ and R ²⁵ are a hydrogen atom, R ²¹ and R ²² are A hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and particularly preferably R ²¹ and R ²² are a methyl group or a trifluoromethyl group.

In Formula (9), from the viewpoint of easy to increase the impact resistance, elastic modulus, and bending resistance of the optical film, and from the viewpoint that the transparency is easily improved and the transparency is easily maintained, R ³⁵ to ^{R 40} are preferably Preferably, it is a hydrogen atom or a C1-C6 alkyl group, More preferably, it is a hydrogen atom or a C1-C3 alkyl group, More preferably, it is a hydrogen atom. Here, ^{the hydrogen atoms contained in R 35} to ^{R 40} may be each independently substituted with a halogen atom, and examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. have. Examples of the 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, formula (5) is represented by formula (5'), and formula (9) is formula (9'):

[Formula 21]

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'), it is easy to improve the solubility of the polyamideimide resin in the solvent by the skeleton containing the fluorine element, and to improve the storage stability of the varnish containing the resin. In addition, it is easy to reduce the viscosity of the varnish, and it is easy to improve the workability of the optical film. Moreover, it is easy to improve the optical properties of an optical film by the skeleton containing a fluorine element.

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

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

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

[Formula 22]

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

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

In formulas (30) and (31), X ¹ and X ² are each independently a divalent organic group, and preferably, a hydrogen atom in the organic group may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. It is an organic group. As X ¹ and X ^{2, the} above formulas (10), (11), (12), (13), (14), (15), (16), (17), and ( A group represented by 18); A group in which a hydrogen atom in the groups represented by the above 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 polyamideimide resin is a structural unit represented by formulas (1) and (2), and optionally, a structural unit represented by formula (30) and/or formula (31). Consists of In addition, from the viewpoint of being easy to increase the optical properties, impact resistance, elastic modulus, and bending resistance of the optical film, in the polyamideimide resin, the ratio of the structural units represented by formulas (1) and (2) is the formula ( 1) and formula (2), and in some cases, based on the total structural units represented by formulas (30) and (31), preferably 80 mol% or more, more preferably 90 mol% or more, more preferably It is 95 mol% or more. In addition, in the polyamideimide resin, the ratio of the structural units represented by formulas (1) and (2) is formulas (1) and (2), and in some cases, formulas (30) and/or formulas ( It is usually 100% or less based on all the structural units represented by 31). In addition, the ratio ^{can be measured using, for example, 1} H-NMR, or can be calculated from the introduction ratio of raw materials.

In 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 further, per 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 Formula (2) is equal to or greater 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 the workability of the optical film is easily improved.

In a preferred embodiment of the present invention, the polyamideimide resin of the present invention may contain, for example, a halogen atom such as a fluorine atom that can be introduced by the above fluorine-containing substituent or the like. When the polyamideimide 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 scratches 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 polyamideimide resin include, for example, a fluoro group and a trifluoromethyl group.

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

The imidation ratio of 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 said lower limit from a viewpoint of being easy to improve the optical property of an optical film. The imidation ratio represents the ratio of the molar amount of imide bonds in the polyamideimide resin to a value twice the molar amount of the structural unit derived from the tetracarboxylic acid compound in the polyamideimide resin. In addition, when the polyamideimide 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 polyamideimide resin and the structural unit derived from the tricarboxylic acid compound The ratio of the molar amount of imide bonds in the polyamideimide resin to the sum of the molar amount is shown. Moreover, the imidation ratio can be calculated|required by IR method, NMR method, etc.

The weight average molecular weight of the polyamideimide 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, more 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 polyamideimide resin is preferably 1,000,000 or less, more preferably 1,000,000 or less, more preferably, from the viewpoint of being easy to improve the solubility of the resin in a solvent and to improve the stretchability and processability of the optical film. Is 800,000 or less, more preferably 700,000 or less, 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 by, for example, a method described in Examples.

[Method for producing polyamideimide resin]

The polyamideimide resin and the polyamideimide precursor resin can be produced using, for example, a tetracarboxylic acid compound, a dicarboxylic acid compound, and a diamine compound as main raw materials.

Examples of the diamine compound used in the production of the resin include aliphatic diamines, aromatic diamines, and mixtures thereof. In addition, in this embodiment, the term "aromatic diamine" refers to 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" represents a diamine in which an amino group is directly bonded to an aliphatic group, and an aromatic ring or other substituent may be included in a part of the structure.

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

As an aromatic diamine, for example, p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2 Aromatic diamine having one aromatic ring, such as ,6-diaminonaphthalene, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether , 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'- Diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, bis (4-(4-aminophenoxy)phenyl) sulfone, bis [4-(3-aminophenoxy)phenyl] sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl] Propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl (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, TFMB, 4,4'-bis(4-aminophenoxy)biphenyl, more preferably 4,4'-diaminodiphenylmethane, 4,4' -Diaminodiphenylpropane, 4,4'-diaminodiphenylether, 4,4'-diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, bis (4-(4- Aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, TFMB, 4,4'-bis(4-aminophenoxy) It is biphenyl. 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 types selected from the group, and even more preferable to use 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 a non-condensed polycyclic aromatic tetracarboxylic dianhydride, for example, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2' ,3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl) ) Propane dianhydride, 2,2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic acid dianhydride (hereinafter, when described as 6 FDA) ), 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4- Dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl) Methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic dianhydride, and 4,4'-(m-phenylenedioxy)diphthalic dianhydride. Further, examples of the monocyclic aromatic tetracarboxylic dianhydride include 1,2,4,5-benzenetetracarboxylic dianhydride, and examples of the condensed polycyclic aromatic tetracarboxylic dianhydride include For example, 2,3,6,7-naphthalenetetracarboxylic 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 2 Anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl Sulfontetracarboxylic 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, 6FDA, 1,2-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride , 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride , Bis(2,3-dicarboxyphenyl)methane dianhydride, 4,4'-(p-phenylenedioxy)diphthalic dianhydride and 4,4'-(m-phenylenedioxy)diphthalic dianhydride. And more preferably 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracar Dianhydride of main acid, 6FDA, bis(3,4-dicarboxyphenyl)methane dianhydride, and 4,4'-(p-phenylenedioxy)diphthalic dianhydride. These can be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydrides. 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-cyclo Cycloalkanetetracarboxylic dianhydride, such as butanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, and bicyclo[2.2.2]oct-7-ene-2,3,5 ,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride, and regioisomers thereof. These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, and 1,2,3,4-pentanetetracarboxylic dianhydride, and the like. Alternatively, it can be used in combination of two or more. 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 bending 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, 6FDA, and mixtures thereof are preferred, 3,3',4,4'-biphenyltetracarboxylic dianhydride and 6FDA, and mixtures thereof are more preferable, and 6FDA and 3,3',4,4'-biphenyltetracarboxylic dianhydride are more desirable.

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

In addition, the polyamide-imide 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. Specific examples include anhydrides of 1,2,4-benzenetricarboxylic acid and anhydrides of 1,3,5-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; Phthalic anhydride and benzoic acid are linked by a single bond, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -C(CF ₃ ) ₂ -, -SO ₂ -, or a phenylene group. .

In the production of the resin, the amount of the diamine compound, the tetracarboxylic acid compound and/or the dicarboxylic acid compound may be appropriately selected according to the ratio of each structural unit of the desired polyamideimide resin, but as described above, the polyamideimide resin It is possible to adjust the _{ratio (int A} /int _B ) to a desired range by synthesizing the polyamideimide resin so that the dicarboxylic acid present at the terminal of is as small as possible. Therefore, as described above, the amine ratio (molar amount of diamine compound/(total molar amount of tetracarboxylic acid compound and dicarboxylic acid compound)) when copolymerizing the tetracarboxylic acid compound, dicarboxylic acid compound and diamine compound) is preferably It is preferable to adjust the amount of each monomer to be more than 1.000, more preferably 1.003 or more, more preferably 1.005 or more, even more preferably 1.008 or more, particularly preferably 1.01 or more.

Further, the present invention is a method for producing a polyamideimide resin in which a diamine compound, a tetracarboxylic acid compound and a dicarboxylic acid compound are reacted, wherein the diamine compound relative to the total number of moles of the tetracarboxylic acid compound and the dicarboxylic acid compound A method for producing a polyamideimide resin in which the ratio of the number of moles (amine ratio) exceeds 1.000 is also provided.

In the production of the resin, the reaction temperature of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is not particularly limited, but, for example, 5 to 350°C, preferably 20 to 200°C, more preferably 25 It is -100°C. From the viewpoint of being easy to adjust the ratio (int _A /int _B ) to a desired range, the reaction vessel may be locally heated as the case may be, adjusted so as to reach the reaction temperature, and manufactured at the same time as local heating. You may adjust the amount of an acid anhydride, such as acetic anhydride, together with the amount of the imidation catalyst mentioned later. The reaction time is also not particularly limited, but is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be carried out under an inert atmosphere or under reduced pressure conditions. In a preferred embodiment, the reaction is carried out while stirring under normal pressure and/or an inert gas atmosphere. Moreover, it is preferable to perform reaction in a solvent inert to reaction. The solvent is not particularly limited as long as it does not affect the reaction. For example, water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, 1-methoxy- Alcohol solvents such as 2-propanol, 2-butoxyethanol, and propylene glycol monomethyl ether; Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone (hereinafter sometimes referred to as GBL), 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 (hereinafter sometimes referred to as DMAc) and N,N-dimethylformamide (hereinafter referred to as DMF); Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; Carbonate solvents such as ethylene carbonate and propylene carbonate; And combinations thereof. Among these, from the viewpoint of solubility, an amide solvent can be suitably used. From the viewpoint of being easy to adjust the ratio (int _A /int _B ) to a desired range, the moisture content in the solvent to be used is adjusted to be preferably 400 ppm or more, more preferably 500 ppm or more. In addition, from the viewpoint of suppressing decomposition of the polyamideimide resin, the water content in the solvent is preferably 1,000 ppm or less, more preferably 800 ppm or less.

In the imidation step in the production of a polyamideimide resin, imidization can be performed in the presence of an imidization catalyst. Examples of the imidation catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; Alicyclic amines (monocyclic) such as N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepine; Alicyclic amines (polycyclic) such as azabicyclo[2.2.1]heptane, azabicyclo[3.2.1]octane, azabicyclo[2.2.2]octane, and azabicyclo[3.2.2]nonane; And pyridine, 2-methylpyridine (2-picoline), 3-methylpyridine (3-picoline), 4-methylpyridine (4-picoline), 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine. , 2,4-dimethylpyridine, 2,4,6-trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and aromatic amines such as isoquinoline. . Moreover, it is preferable to use an acid anhydride together with an imidation catalyst from a viewpoint of being easy to accelerate an imidation reaction. Examples of the acid anhydride include conventional acid anhydrides used in the imidation reaction, and specific examples thereof include aliphatic acid anhydrides such as acetic anhydride, propionic anhydride and butyric anhydride, and aromatic acid anhydrides such as phthalic acid. From the viewpoint of being easy to adjust the ratio (int _A /int _B ) to a desired range, it is preferable to lower the temperature increase rate in the imidization process, and it is more preferable to take 30 minutes or more to increase the temperature from 10°C to 50°C. Do.

The polyamideimide resin may be separated and purified by a conventional method such as filtration, concentration, extraction, crystallization, recrystallization, column chromatography, or other separation means, or a combination of these separation means. In a preferred embodiment, isolation can be achieved by adding a large amount of alcohol such as methanol to a reaction solution containing a transparent polyamideimide resin, depositing the resin, and performing concentration, filtration, drying, or the like.

[Optical film]

The present invention also provides an optical film containing the polyamideimide resin of the present invention described above. In one embodiment of the present invention, the content of the polyamideimide resin of the present invention in the optical film of the present invention is preferably 10 parts by mass or more, and more preferably 30 parts by mass per 100 parts by mass of the optical film. It is at least 50 parts by mass, more preferably at least 50 parts by mass, preferably at most 99.5 parts by mass, and more preferably at most 95 parts by mass. When the content of the polyamideimide resin is within the above range, it is easy to improve the optical properties, impact resistance and elastic modulus of the optical film, and it is easy to suppress the deterioration of the optical properties and mechanical properties of the optical film over time, and the quality of the optical film Easy to improve stability.

The optical film of the present invention may contain at least one filler in addition to the polyamideimide resin of the present invention. Examples of the filler include organic particles and inorganic particles, and preferably inorganic particles. As inorganic particles, metal oxide particles such as silica, zirconia, alumina, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, cerium oxide, and metal fluorides such as magnesium fluoride and sodium fluoride Particles, etc. are mentioned, and among these, from the viewpoint of increasing the elastic modulus and/or tear strength of the optical film, and easily improving the impact resistance, silica particles, zirconia particles, and alumina particles are preferably mentioned, and more preferably Examples include silica particles. These fillers can be used alone or in combination of two or more.

The average primary particle diameter of the filler, preferably silica particles, is usually 1 nm or more, preferably 5 nm or more, more preferably 10 nm or more, still more preferably 11 nm or more, particularly preferably 13 nm or more. , Preferably 100 nm or less, more preferably 90 nm or less, 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 , More preferably 40 nm or less. When the average primary particle diameter of the filler, preferably silica particles is within the above range, aggregation of the filler, preferably silica particles, is suppressed, and it is easy to improve the optical properties of the obtained optical film. The average primary particle diameter of the filler can be measured by the BET method. Further, the average primary particle diameter may be measured by image analysis of a transmission electron microscope TEM or a scanning electron microscope SEM.

When the optical film of the present invention contains a filler, preferably silica particles, the content of the filler is usually 0.1 parts by mass or more, preferably 1 part by mass or more, and more preferably 5 parts by mass, based on 100 parts by mass of the optical film. It is at least 10 parts by mass, more preferably at least 10 parts by mass, even more preferably at least 20 parts by mass, particularly preferably at least 30 parts by mass, and preferably at most 60 parts by mass. When the content of the filler is more than the above lower limit, it is easy to improve the elastic modulus of the obtained optical film. Moreover, when the content of the filler is less than or equal to the above upper limit, it is easy to improve the optical properties of the optical film.

The optical film of the present invention may further contain an ultraviolet absorber. The ultraviolet absorber can be appropriately selected from those commonly used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light with a wavelength of 400 nm or less. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of 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 the present specification, the "system compound" refers to a derivative of the compound to which the "system compound" is attached. For example, the "benzophenone-based compound" refers to a compound having a 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, further preferably 3 parts by mass or more, based on 100 parts by mass of the optical film, It is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and still more preferably 6 parts by mass or less. The appropriate content varies depending on the ultraviolet absorber to be used, but when the content of the ultraviolet absorber is adjusted so that the light transmittance of 400 nm is about 20 to 60%, the light resistance of the optical film is improved and transparency is easily improved.

The optical film of the present invention may further contain other additives other than a filler and an ultraviolet absorber. Examples of other additives include antioxidants, 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, based on 100 parts by mass of the optical film.

In a preferred embodiment of the present invention, the optical film of the present invention comprising the polyamideimide resin of the present invention described above is easy to suppress deterioration over time in optical properties and mechanical properties, and from the viewpoint of being easy to increase quality stability. , It is preferable that the rate of change in the weight average molecular weight before and after the storage test is stored for 1 week under conditions of 85°C and 85% humidity, and is 26% or less. Further, in a more preferred aspect of the present invention, the optical film of the present invention containing the polyamideimide resin of the present invention is easy to suppress deterioration over time in optical properties and mechanical properties, and is easy to improve quality stability. From the viewpoint of, it is preferable that the rate of change of the weight average molecular weight before and after the storage test stored for one week under conditions of temperature 85°C and humidity 85% is 25% or less. When the rate of change of the weight average molecular weight under the above conditions exceeds 26% or 25%, depending on the storage conditions in the optical film and the storage conditions of the display device in which the optical film is assembled, what in the polyamide resin contained in the optical film It is considered that there may be a case where a reaction of application occurs, and a decrease in optical properties and/or mechanical properties over time tends to occur. The rate of change of the weight average molecular weight is more preferably 25% or less, still more preferably 23% or less, and even more preferably 22% or less. In the present invention, the change rate of the weight average molecular weight before and after a storage test stored for one week under conditions of 85° C. and 85% humidity, which is unlikely to cause deterioration of optical properties and/or mechanical properties over time, is preferably 26% or less, An optical film containing a polyamideimide resin, which is more preferably 25% or less, is also provided. The rate of change in the weight average molecular weight before and after the storage test is preferably 26% or less, more preferably 25% or less, still more preferably 23% or less, and even more preferably 22% or less. In addition, the rate of change of the weight average molecular weight can be calculated, for example, by the method described in Examples. It relates to the polyamideimide resin-containing optical film, wherein the rate of change of the weight average molecular weight before and after the storage test is preferably 26% or less, more preferably 25% or less, and the rate of change of the weight average molecular weight is less than or equal to the above upper limit. way that is not particularly limited, for example, the art according to ¹ H- ¹³ C HSQC spectrum obtained deuterated dimethyl sulfoxide solution of the polyamide-imide resin as a measurement sample contained in the optical film, the proton chemical shift Is 8.06 to 8.14 ppm, and the chemical shift of carbon is 129.6 to 130.3 ppm, the integral value (int _A ) of the peak present in the region (A) and the chemical shift of proton is 7.26 to 7.85 ppm, and carbon _{When the ratio of the integral value (int B} ) of the peak present in the region (B) where the chemical shift of is 132.4 to 134.0 ppm _{(int A} /int _B ) is 1.5% or less, the rate of change in the weight average molecular weight is the upper limit. It is easy to adjust to the following. In addition, by making the ratio (int _A /int _B ) below a specific range, it is easy to adjust the rate of change of the weight average molecular weight to a specific range, but from the viewpoint of suppressing the deterioration of optical properties and mechanical properties over time, the rate of change of the weight average molecular weight It is not essential to set the ratio (int _A /int _B ) to be less than or equal to the specific range.

The elastic modulus of the optical film of the present invention is preferably 4.5 GPa or more, more preferably 4.8 GPa or more, still more preferably 5.0 GPa or more, even more preferably from the viewpoint of easy prevention of wrinkles or scratches of the optical film. It is preferably 5.1 GPa or more, particularly preferably 5.2 GPa or more, and usually 100 GPa or less. Incidentally, the modulus of elasticity can be measured using a tensile tester (50 mm interchuck distance, 10 mm/min tensile speed), and, for example, can be measured by the method described in Examples.

The total light transmittance of the optical film of the present invention (hereinafter, may be simply described as Tt) is preferably 80% or more, more preferably 85% or more, even more preferably 88% or more, more It is more preferably 89% or more, particularly preferably 90% or more, and usually 100% or less. When the total light transmittance is more than the above lower limit, it is easy to increase visibility when the optical film is assembled as a front plate to a display device. 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 device or the like necessary for obtaining a certain brightness as compared to the case where a film having a low transmittance is used, for example. For this reason, power consumption can be reduced. For example, in the case of assembling the optical film of the present invention to a display device, even if the amount of light of the backlight is reduced, a bright display tends to be obtained, thereby contributing to energy saving. In addition, the total light transmittance can be measured using a haze computer in conformity with, for example, JIS K7361-1:1997. The total light transmittance may be a total light transmittance in the range of the thickness of the optical film described later. In addition, in this specification, that the optical film is excellent in optical properties means that the total light transmittance is high and/or the haze is low, and/or the YI is low.

The haze of the optical film of the present invention is preferably 5% or less, more preferably 4% or less, more preferably 3% or less, even more preferably 2.5% or less, particularly preferably 2% or less, particularly It is more preferably 1% or less, particularly more preferably 0.5% or less, and usually 0.01% or more. When the haze of the optical film is less than or equal to the above upper limit, when the optical film is assembled to a display device as a front plate, it is easy to increase visibility. In addition, haze can be measured using a haze computer in accordance with JIS K 7136:2000.

The YI value of the optical film of the present invention is preferably 3.0 or less, more preferably 2.0 or less, more preferably 1.9 or less, particularly preferably 1.8 or less, and is usually -5 or 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 a display device, high visibility can be contributed. In addition, the YI value is preferably within the above range even after storage for one week under conditions of 85°C and 85% humidity from the viewpoint of improving quality stability. This 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. In addition, it is preferable that the optical film has a YI value in the above range even after a storage test stored for one week under conditions of a temperature of 85°C and a humidity of 85%.

The thickness of the optical film of the present invention is preferably 10 µm or more, more preferably 20 µm or more, more preferably 25 µm or more, particularly preferably 30 µm or more, preferably 200 µm or less, more preferably Is 100 µm or less, more preferably 80 µm or less, particularly preferably 60 µm or less, and the range of the thickness may be a combination of their upper and lower limits. When the thickness of the optical film is within the above range, it is easy to further increase the elastic modulus of the optical film. In addition, the thickness of the optical film can be measured using a micrometer, and for example, can be measured by the method described in Examples.

The pencil hardness of at least one surface of the optical film of the present invention is preferably HB or higher, more preferably F or higher. When the pencil hardness of at least one surface of the optical film is more than the above-described hardness, it is easy to prevent scratches and the like on the surface of the optical film. In addition, pencil hardness can be measured according to JIS K 5600-5-4:1999.

The optical film of the present invention has excellent bending resistance. The number of flexion resistance in the MIT thermal fatigue test according to ASTM standard D2176-16 of the present invention is preferably 50,000 times or more, more preferably 60,000 times or more, and still more preferably 70,000 times or more. When the number of times of bending resistance is more than the above lower limit, scratches due to bending when used as a front plate material such as a flexible display can be prevented. In addition, the MIT internal fatigue test can be measured using an MIT internal fatigue tester, for example, it can be measured by the method described in the examples. In addition, the optical film is preferably 35,000 times or more, more preferably 40,000 times or more, even more preferably 50,000 times or more, even after a storage test of storage for one week under conditions of 85°C and 85% humidity. It is desirable to satisfy the number of times.

The optical film of the present invention is an optical film excellent in quality stability in which deterioration of optical properties and mechanical properties over time is suppressed. Specifically, the optical film was stored for 1 week in an environment of 85°C and 85% relative humidity, and the number of bending resistance (N1) of the optical film before the storage test and the number of bending resistance (N2) of the optical film after the storage test were determined. , After standing at a temperature of 25°C and 50% of humidity for 24 hours or more, measurement is performed under the conditions described in Examples, for example, using an MIT internal fatigue tester. From the obtained number of flexure resistances, the following equation:

Rate of change in the number of internal bending (%) = {(N1-N2)/N1}×100

The rate of change (%) of the number of flexure resistance calculated by is smaller, the better, but preferably 40% or less, more preferably 35% or less, more preferably 30% or less, even more preferably 25% Hereinafter, it is particularly preferably 20% or less.

In addition, the YI value (Y1) of the optical film before the storage test and the YI value (Y2) of the optical film after the storage test were measured using an ultraviolet visible near-infrared spectrophotometer, for example, by the method described in the Examples. Calculate. From the obtained YI value, the following formula:

Rate of change in YI value (%) = {(Y2-Y1)/Y1}×100

The smaller the rate of change (%) of the YI value calculated according to, the better, but preferably 25% or less, more preferably 20% or less, and still more preferably 15% or less.

[Method of manufacturing 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 step of preparing a resin composition containing at least the polyamideimide resin and a solvent (hereinafter, also referred to as "varnish") (varnish preparation step),

(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)

It may be a manufacturing method containing at least.

In the varnish preparation step, a polyamideimide resin is dissolved in a solvent, and if necessary, additives such as the above filler and ultraviolet absorber are added and mixed with stirring to prepare a varnish. In the case of using silica particles as a filler, a dispersion of silica sol containing silica particles is substituted with a solvent in which the resin is soluble, for example, a solvent used for preparing the following varnish. You may add it.

The 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 DMAc and DMF; Lactone solvents such as GBL and γ-valerolactone; Sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; Carbonate solvents such as ethylene carbonate and propylene carbonate; And combinations thereof. Among these, an amide-based solvent or a lactone-based solvent is preferable. These solvents may be used alone or in combination of two or more. Further, the varnish may contain water, an alcohol solvent, a ketone solvent, an acyclic ester solvent, an ether solvent, and the like. The solid content concentration of the varnish is preferably 1 to 25% by mass, more preferably 5 to 20% by mass, and still more preferably 5 to 15% by mass.

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

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

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

The use of the optical film of the present invention is not particularly limited, and may be used for various purposes. The optical film of the present invention may be a single layer or a laminate, and the optical film of the present invention may be used as it is, or may be used as a laminate with other films. In addition, when the optical film is a laminated body, it is referred to as an optical film including all layers laminated on one side or both sides of the 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 adjustment layer, and a refractive index adjustment layer. The functional layer can be used alone or in combination of two or more.

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 heat energy, and is preferably irradiated with active energy rays. Active energy rays are defined as energy rays capable of generating active species by decomposing compounds that generate active species, and include visible light, ultraviolet rays, infrared rays, X-rays, α rays, β rays, γ rays, and electron rays. And, preferably, ultraviolet rays are used. The hard coating composition contains at least one polymer of a radical polymerizable compound and a cation polymerizable compound.

The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound may be a functional group capable of causing a radical polymerization reaction, and examples thereof include a group containing a carbon-carbon unsaturated double bond. Specifically, a vinyl group, (meta) Acryloyl group, etc. are mentioned. Further, when the radically polymerizable compound has two or more radically polymerizable groups, these radically polymerizable groups may be the same or different, respectively. 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. The radical polymerizable compound is preferably a compound having a (meth)acryloyl group from the viewpoint of high reactivity, and specifically, a polyfunctional compound having 2 to 6 (meth)acryloyl groups per molecule Compounds called acrylate monomers, or oligomers having several (meth) acryloyl groups in molecules called epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate, having a molecular weight of hundreds to thousands of And, preferably, at least one 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. In terms of improving the hardness of the hard coat layer, the number of cation polymerizable groups in the cation polymerizable compound in one molecule is preferably 2 or more, and more preferably 3 or more.

Further, as the cation polymerizable compound, among others, a compound having at least one of an epoxy group and an oxetanyl group as a cation polymerizable group is preferable. Cyclic ether groups, such as an epoxy group and an oxetanyl group, are preferable in that the shrinkage due to the polymerization reaction is small. In addition, the compound having an epoxy group among the cyclic ether groups is advantageous in that it is easy to obtain compounds of various structures, does not adversely affect the durability of the obtained hard coating layer, and is easy to control compatibility with radical polymerizable compounds. have. 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, speeds up the network formation rate obtained from the cation polymerizable compound of the obtained hard coating layer, and also in the region where it is 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, a cyclopentene ring-containing compound is epoxidized with a suitable oxidizing agent such as hydrogen peroxide or peracid. Alicyclic epoxy resin obtained by doing so; 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 of glycidyl (meth)acrylates, and copolymers; Glycidyl ether produced by reaction of bisphenols such as bisphenol A, bisphenol F or hydrogenated bisphenol A, or derivatives such as alkylene oxide adducts and caprolactone adducts, and epichlorohydrin And glycidyl ether type epoxy resins derived from bisphenols, such as novolac epoxy resins, and the like.

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

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

As an active energy ray radical polymerization initiator, a Type 1 type radical polymerization initiator that generates radicals by decomposition of molecules, and a Type 2 type radical polymerization initiator that coexists with a tertiary amine to generate radicals through a hydrogen extraction type reaction. And they are used alone or in combination.

The cation polymerization initiator may be capable of releasing a substance for initiating cation polymerization by at least any of irradiation with active energy rays and heating. As 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 by either or both irradiation with active energy rays or heating depending on the difference in structure.

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

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

The solvent is capable of dissolving or dispersing the polymerizable compound and the polymerization initiator, and any solvent known as a solvent for the hard coating composition in the art 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. For example, a main material selected from UV-curable transparent resin, electron beam-curable transparent resin, and thermosetting transparent resin, and ultraviolet rays dispersed in the main material. It consists of an absorbent.

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

The adhesive layer may be a layer, called a pressure sensitive adhesive (PSA, in some cases), which is adhered to the object by pressure. The pressure-sensitive adhesive may be a pressure-sensitive adhesive that is ``a substance that has adhesiveness at room temperature and adheres to an adherend with light pressure'' (JIS K 6800), or ``a specific component is contained in a protective film (microcapsule), and pressure An adhesive that can maintain stability until the film is destroyed by suitable means such as heat or heat." (specified in JIS K 6800) may be a capsule-type adhesive.

The color adjustment layer is a layer having a function of color adjustment, and is a layer capable of adjusting a layered product including an optical film to a target color. 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 basic dyes, acid dyes, and mordant dyes.

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

The optical film of the present invention may be a single layer or a laminate, for example, the optical film produced as described above may be used as it is, or may be used as a laminate with other films.

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 of a flexible display device (hereinafter, sometimes referred to as a window film), a rollable display or a foldable. It is very useful as a front panel of a display. A flexible display device has, for example, a flexible functional layer and an optical film that is superimposed on the flexible functional layer and functions as a front plate. That is, the front plate of the flexible display device is disposed on the viewer 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. In addition, the flexible display device is a display device used with operations such as repeatedly bending or repeatedly winding the image display device. High bending resistance is required for the front plate of a flexible display device used in conjunction with such repeated bending operations. In addition, high visibility is also required for the front panel. Compared with the film for the substrate of the image display device used inside the image display device, the front plate of the image display device, especially the film for the front plate of the flexible display device, requires high visibility and high bending resistance. do. For example, the film of the present invention preferably has a total light transmittance, haze and/or YI value as described above, from the viewpoint of being easy to increase visibility when used for a front plate of a flexible display device, and It is preferable to satisfy the number of bending resistances in the MIT fatigue resistance test as described above from the viewpoint of being easy to increase the bending resistance when used as a front plate of a flexible display device.

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. Examples of the flexible display device include all image display devices having flexible characteristics, and examples thereof include the above-described rollable display and foldable display. A rollable display is an image display device used in a state in which an image display portion including a front plate is wound in a roll shape, and the image display portion is pulled out to form a flat or curved surface, and operations such as winding up in a roll shape It is an image display device such as that performed every time it is used. In addition, the foldable display is an image display device that is used in a state in which an image display portion including a front panel is bent and the image display portion is opened to form a flat or curved surface, and an operation such as bending is performed each time it is used. It is the same image display device. An image display device in which such operations such as winding and bending are repeatedly performed is referred to as a flexible image display device.

[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. The flexible display device is composed of a laminate for flexible display devices and an organic EL display panel, and a laminate for flexible display devices is disposed on the viewing side of the organic EL display panel and is bendable. The laminate for a flexible display device may contain a window film, a polarizing plate, and a touch sensor, which are the optical films of the present invention, and the order of lamination thereof is arbitrary, but from the viewing side, a window film, a polarizing plate, a touch sensor or a window film, a touch sensor It is preferable that they are laminated in the order of the polarizing plates. If the polarizing plate is present on the visible 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. Further, a light shielding pattern formed on at least one surface of a layer of any of a window film, a 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 a right circularly polarized component or a left circularly polarized component by laminating a λ/4 retardation plate on a linear polarizing plate. For example, it is used for converting external light into right-circular polarized light, blocking external light reflected from the organic EL panel to become left-circularly polarized light, and transmitting only light-emitting components of the organic EL to suppress the influence of the reflected light 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 ground axis of the λ/4 retardation plate need to be 45° in theory, but are 45±10° in practical use. The linear polarizing plate and the λ/4 retardation plate do not necessarily need to be stacked adjacent to each other, and the relationship between the absorption axis and the slow axis may satisfy the above range. It is desirable to achieve complete circular polarization at all wavelengths, but in practical use, it is not necessary to do so, so the circular polarizing plate in the present invention also includes an elliptically polarizing plate. It is also preferable to laminate a λ/4 retardation film on the viewing side of the linear polarizing plate to make the outgoing light circularly polarized, thereby improving visibility in a state of wearing polarized sunglasses.

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 affixed 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 (hereinafter, sometimes simply described as PVA)-based film. A dichroic dye such as iodine is adsorbed to a 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-type polarizer, other steps such as swelling, crosslinking with boric acid, washing with an aqueous solution, and drying may be provided. The stretching or dyeing process may be performed by the PVA-based film alone, or may be performed in a state of being laminated with other films such as polyethylene terephthalate. The thickness of the PVA-based film to be used is preferably 10 to 100 µm, and the draw ratio is preferably 2 to 10 times.

Further, as another example of the polarizer, a liquid crystal coating type polarizer formed by applying a liquid crystal polarizing composition may be used. The liquid crystal polarizing composition may include a liquid crystal compound and a dichroic dye compound. The liquid crystalline compound should just have a property showing a liquid crystal state, and it is preferable because it can exhibit high polarization performance if it has a high-order alignment state such as a smectic phase. 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 coated polarizer is manufactured by forming a liquid crystal polarizing layer by applying a liquid crystal polarizing composition on an alignment film.

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

The alignment layer can be produced, for example, by applying an alignment layer forming composition on a substrate and imparting alignment by rubbing, polarized light irradiation, or the like. In addition to the alignment agent, the alignment film forming composition may contain a solvent, a crosslinking agent, an initiator, a dispersant, a leveling agent, a silane coupling agent, and the like. As the aligning agent, for example, polyvinyl alcohols, polyacrylates, polyamic acids, and polyimides can be used. When applying photo-alignment, 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, and more preferably 10 to 500 nm, from the viewpoint of alignment regulating power. The liquid crystal polarizing layer may be peeled off from the substrate and transferred to be laminated thereon, or the substrate may be laminated as it is. It is also preferable that the said base material serves as a transparent base material of a protective film, a retardation plate, and a window film.

As the protective film, a transparent polymer film may be used. Specifically, as a polymer film to be used, a polyolefin such as a cycloolefin derivative having a monomer unit including polyethylene, polypropylene, polymethylpentene, norbornene or a cycloolefin. (Modified) celluloses, such as 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, etc. Polyesters, polyamides such as nylon, polyimides, polyamideimides, polyetherimides, polyethersulfones, polysulfones, polyvinyl alcohols, polyvinyl acetals, polyurethanes, epoxy Films such as resins may be mentioned, and from the viewpoint of being excellent in transparency and heat resistance, preferably, a polyamide, polyamideimide, polyimide, polyester, olefin, acrylic or cellulose-based film is used. These polymers may be used alone or in combination of two or more. These films are 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, plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent whitening agents, dispersants, thermal stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, solvents, etc. 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 within the above range, the flexibility of the protective film is difficult to decrease.

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

Further, as another example of the λ/4 retardation plate, a liquid crystal coating type retardation plate formed by applying a liquid crystal composition may be used. The liquid crystal composition includes a liquid crystal compound having a liquid crystal state such as nematic, cholesteric, and smectic. Any of the compounds including the liquid crystal compound in the liquid crystal composition has a polymerizable functional group. The liquid crystal coating type retardation plate may further include an initiator, a solvent, a dispersant, a leveling agent, a stabilizer, a surfactant, a crosslinking agent, a silane coupling agent, and the like. The liquid crystal coating type retardation plate can be manufactured by forming a liquid crystal retardation layer by coating and curing a liquid crystal composition on an alignment film in the same manner as the substrate in the liquid crystal polarizing layer. The liquid crystal coated retardation plate can be formed to have a thinner thickness compared to the stretched retardation plate. The thickness of the liquid crystal phase difference 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 said base material serves as a transparent base material of a protective film, a retardation plate, and 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, an in-plane phase difference equal to λ/4 in the vicinity of 560 nm with high visibility, i.e., 100 to 180 nm, preferably 130 to It is often designed to be 150 nm. It is preferable to use an inversely dispersed λ/4 retardation plate using a material having a birefringence wavelength dispersion characteristic opposite to that of usual, since it can improve visibility. As such a material, it is also preferable to use those described in Japanese Unexamined Patent Application Publication No. 2010-30979, for example, in the case of an elongated retardation plate, and Japanese Unexamined Patent Application Publication No. 2007-232873, in the case of a liquid crystal coated retardation plate.

In addition, as another method, a technique for obtaining a broadband λ/4 retardation plate by combining it with a λ/2 retardation plate is also known (for example, Japanese Unexamined Patent Application 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, it is preferable to use a liquid crystal coated retardation plate in either case 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 (for example, Japanese Unexamined Patent Application Publication No. 2014-224837). The positive C plate may also be a liquid crystal coating type retardation plate or a stretch type retardation plate. The retardation in the thickness direction is usually -200 to -20 nm, preferably -140 to -40 nm.

[Touch sensor]

The flexible display device of the present invention may further include a touch sensor. The touch sensor is used as an input means. As a touch sensor, various modes such as a resistive film method, a surface acoustic wave method, an infrared method, an electromagnetic induction method, and a capacitance method have been proposed, and any method may be used. Among them, the electrostatic capacity method is preferable. The capacitive touch sensor is divided into an active area and an inactive area located 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, corresponding to the non-display unit. Area. The touch sensor includes a substrate having a flexible characteristic; A sensing pattern formed in the active area of the substrate; Each sensing line formed in the non-active region of the substrate and connected to an external driving circuit through the sensing pattern and the pad portion may be included. 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 fracture point 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 disposed in different directions. The first pattern and the second pattern are formed on the same layer, and each pattern must be electrically connected to detect 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 used 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 wires, and the like, and these may be used alone or in combination of two or more. Preferably, ITO can be used. The metal used for the metal wire is not particularly limited, and examples thereof include silver, gold, aluminum, copper, iron, nickel, titanium, selenium, and chromium. These may be used alone or in combination of two or more.

The bridge electrode may be formed on the insulating layer by interposing an insulating layer on the sensing pattern, a bridge electrode may be formed on a substrate, and an insulating layer and a sensing pattern may be formed thereon. The bridge electrode may be formed of the same material as the sensing pattern, or may be formed of a metal such as molybdenum, silver, aluminum, copper, palladium, gold, platinum, zinc, tin, titanium, or an alloy of two or more of them. Since the first pattern and the second pattern must be electrically insulated, an insulating layer is formed between the sensing pattern and the bridge electrode. The insulating layer may be formed only between the joint of the first pattern and the bridge electrode, or may be formed in a structure of a layer covering the sensing pattern. In the latter case, the bridge electrode may connect the second pattern through a contact hole formed in the insulating layer. The touch sensor is for appropriately compensating for a difference in transmittance between a patterned area in which a pattern is formed and a non-patterned area in which a pattern is not formed, specifically, a difference in light transmittance caused by a difference in refractive indices in these areas. As a means, 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 include 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 bonded with an adhesive. As adhesives, 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, curing agent mixture adhesives, A heat-melt adhesive, a pressure-sensitive adhesive, a pressure-sensitive adhesive, a rewet-type adhesive, or the like can be used. Among them, water-based solvent volatilization type adhesives, active energy ray-curable adhesives, and pressure-sensitive adhesives are often used. The thickness of the adhesive layer can be appropriately adjusted 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 to be used may be the same or different.

As the aqueous solvent volatilization adhesive, a water-dispersed polymer such as polyvinyl alcohol-based polymer, water-soluble polymer such as starch, ethylene-vinyl acetate-based emulsion, and styrene-butadiene-based emulsion can be used as the main polymer. have. 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 aqueous solvent volatilization type adhesive, adhesion can be imparted by injecting the aqueous solvent volatilization type adhesive between layers to be adhered to bond the adherend layers and then drying. 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 to form a plurality of layers, the thickness of each layer and the type of the adhesive may be the same or different.

The active energy ray-curable adhesive may be formed by curing an active energy ray-curable composition 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 cation polymerizable compound is the same as the hard coating composition, and the same type of the hard coating composition can be used. As the cation polymerizable compound used in the active energy ray curing composition, an epoxy compound is 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 may be appropriately selected and used. These polymerization initiators are decomposed by at least one of active energy ray irradiation and heating to generate radicals or cation to proceed radical polymerization and cation polymerization. Among the base materials of the hard coating composition, an initiator capable of initiating at least either radical polymerization or cationic polymerization by irradiation with active energy rays can be used.

The active energy ray curing composition may further include an ion trapping agent, an antioxidant, a chain transfer agent, an adhesion-imparting agent, a thermoplastic resin, a filler, a flow viscosity modifier, a plasticizer, 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 one or both of the adhered layers and then bonded, and activated by passing through either or both of the adhered layers. It can be bonded by irradiation with energy rays and curing. In the case of using the active energy ray-curable adhesive, the thickness of the adhesive layer may be usually 0.01 to 20 µm, preferably 0.1 to 10 µm. When the active energy ray-curable adhesive is used to form a plurality of layers, the thickness of each layer and the type of adhesive to be 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, a silicone-based pressure-sensitive adhesive, and the like, 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, and 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 or an 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 to form a plurality of layers, the thickness of each layer and the type of the pressure-sensitive adhesive to be 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 marginal portion of the flexible image display device and makes it difficult to visually recognize, thereby improving the visibility of the image. The light shielding 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 shading pattern is usually 1 to 100 µm, preferably 2 to 50 µm. Moreover, it is also preferable to give a shape, such as an inclination, to the thickness direction of a light-shielding pattern.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples. "%" and "parts" in the examples mean mass% and mass parts unless otherwise specified. First, the evaluation method will be described.

<Measurement _{of (int A} /int _B ) by HSQC-NMR>

_{(Int A} /int _B ) by HSQC-NMR was calculated as follows.

(1) How to prepare a measurement sample

The polyamideimide resin was dissolved in deuterated dimethyl sulfoxide (DMSO-d ₆ ) to obtain a 2% by mass solution, as a measurement solution.

(2) Measurement conditions

Measurement device: Bruker 600 MHz NMR device AVANCE600

Sample temperature: 303 K

Measurement method: HSQC

Chemical shift criteria: DMSO (2.49 ppm proton, 40.44 ppm carbon)

(3) Analysis method

In the obtained HSQC-NMR spectrum, the volume of the peak present in the region A in which the proton chemical shift is 8.06 to 8.14 ppm and the carbon chemical shift is 129.6 to 130.3 ppm is obtained by integration, and the integral value (int _A ) Got it. Further, the volume of the peak present in the region B in which the proton chemical shift is 7.26 to 7.85 ppm and the carbon chemical shift is 132.4 to 134.0 ppm was obtained by integration to obtain an _{integral value (int B ).} By calculating the ratio of the integral value (int _A ) to the integral value (int _B ), a ratio (int _A /int _B ) [%] was obtained.

<Measurement of the weight average molecular weight (weight average molecular weight in terms of polystyrene) of the polyamideimide resin>

Gel Permeation Chromatography (GPC) measurement

(1) Pre-treatment method

DMF eluent (10 mmol/L lithium bromide added solution) was added to the polyamideimide film to a concentration of 2 mg/mL, heated while stirring at 80° C. for 30 minutes, cooled, and filtered with a 0.45 μm membrane filter. It was set as a solution.

(2) Measurement conditions

Column: Tosoh Corporation TSKgel α-2500 ((7) 7.8 mm diameter x 300 mm) x 1, α-M ((13)7.8 mm diameter x 300 mm) x 2

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

Flow: 1.0 mL/min

Detector: RI detector

Column temperature: 40°C

Injection volume: 100 μL

Molecular weight standard: standard polystyrene

<Change rate of weight average molecular weight>

The optical films obtained in Examples and Comparative Examples were stored for 1 week in an environment at a temperature of 85°C and a relative humidity of 85%. In addition, the weight average molecular weight (Mw1) of the polyamideimide resin contained in the optical film before the storage test and the weight average molecular weight (Mw2) of the polyamideimide resin contained in the optical film after the storage test were determined according to the above method. It was measured. From the obtained weight average molecular weight, the rate of change (%) of the weight average molecular weight was calculated according to the following equation.

Change rate of weight average molecular weight (%) = {(Mw1-Mw2)/Mw1}×100

<thickness>

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

<Modulus of elasticity>

The elastic modulus at a temperature of 25°C and a relative humidity of 50% of the optical films obtained in Examples and Comparative Examples was measured using "Autograph AG-IS" manufactured by Shimadzu Corporation. In more detail, a film having a width of 10 mm in length and width was prepared, a stress-strain curve (S-S curve) was measured under conditions of a chuck distance of 50 mm and a tensile speed of 20 mm/min, and an elastic modulus was calculated from the slope.

<Total light transmittance (Tt)>

In accordance with JIS K 7105:1981, the total light transmittance of the optical films obtained in Examples and Comparative Examples was measured with a fully automatic direct reading haze computer (HGM-2DP manufactured by Suga Testing Instruments Co., Ltd.).

<Haze>

In accordance with JIS K 7136:2000, the optical films obtained in Examples and Comparative Examples were cut to a size of 30 mm x 30 mm, and haze (HGM-2DP manufactured by Suga Testing Instruments Co., Ltd.) was used. %) was measured.

<YI value>

Using an ultraviolet visible near-infrared spectrophotometer (manufactured by Japan Spectroscopy Co., Ltd. V-670), the three stimulus values (X, Y, Z) were calculated and substituted into the following calculation formula to calculate the YI value.

YI=100×(1.2769X-1.0592Z)/Y

<Rate of change of YI value>

A storage test was conducted in which the optical films obtained in Examples and Comparative Examples were stored for 1 week in an environment of 85°C and 85% relative humidity. The YI value (Y1) of the optical film before the storage test and the YI value (Y2) of the optical film after the storage test were measured according to the method described above. From each of the obtained YI values, the rate of change (%) of the YI value was calculated according to the following equation.

Rate of change in YI value (%) = {(Y2-Y1)/Y1}×100

<Number of flexion resistance in MIT test>

The optical films obtained in Examples and Comparative Examples were each cut into a size of 10 mm×100 mm using a dumbbell cutter. The cut film was allowed to stand at a temperature of 25°C and 50% humidity for more than 24 hours, and set in an MIT internal fatigue tester (“MIT-DA” manufactured by Toyo Seiki Co., Ltd., type: 0530), and a test speed of 175 cpm and a bending angle of 135 A bending test was carried out in both the front and back directions under conditions of °, a load of 750 g and an R of 1.0 mm of a bending clamp, and the number of times that each film can be bent without breaking was measured.

<Change rate of the number of internal bending>

The optical films obtained in Examples and Comparative Examples were stored for 1 week in an environment at a temperature of 85°C and a relative humidity of 85%. Then, the number of bending resistances (N1) of the optical film before the storage test and the number of bending resistances (N2) of the optical film after the storage test are respectively set at a temperature of 25°C and 50% humidity for 24 hours or more, and then the above method. It was measured according to. From the obtained number of bending resistances, the rate of change (%) of the number of bending resistances was calculated according to the following equation.

Rate of change in the number of internal bending (%) = {(N1-N2)/N1}×100

<Amine ratio>

The molar amount of the diamine compound used in the synthesis of the polyamideimide resin is _{referred to as M A} mole. The molar amount of the dicarboxylic acid compound was _{referred to as M B} mole, and the mole _{amount of the tetracarboxylic acid compound was referred to as M C} mole, and the amine ratio in the synthesis of the resin was calculated by the following formula.

Amine ratio=M _A /(M _B +M _C )

<Example 1>

In a nitrogen gas atmosphere, 313.57 g of DMAc was added to a 1 L separable flask equipped with a stirring blade, and a required amount of ion-exchanged water was added so that the moisture content became 700 ppm. Then, 18.53 g (57.86 mmol) of TFMB was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 7.64 g (17.19 mmol) of 6FDA was added to the flask, cooled to 10°C, and stirred for 16 hours. Then, 1.69 g (5.73 mmol) of OBBC, followed by 6.28 g (30.93 mmol) of TPC were added to the flask, followed by stirring at 10° C. for 30 minutes. Subsequently, 313.57 g of DMAc adjusted to a moisture content of 700 ppm was added, and after stirring for 10 minutes, 0.70 g (3.45 mmol) of TPC was further added to the flask, followed by stirring at 10° C. for 30 minutes, and further TFMB 0.0367 g (0.115 mmol) was added, and the mixture was stirred for 2 hours. Then, diisopropylethylamine 5.18 g (40.11 mmol), 4-methylpyridine 3.74 g (40.11 mmol), and acetic anhydride 12.29 g (120.30 mmol) were added to the flask, followed by stirring at 10° C. for 30 minutes. Then, using an oil bath, the temperature was raised from 10℃ to 50℃ for 30 minutes, from 50℃ to 60℃ for 10 minutes, and from 60℃ to 65℃ for 10 minutes, and then from 65℃ to 70℃ for 10 minutes, The temperature was raised in stages from 70°C to 75°C over 10 minutes, and further stirred while keeping the temperature at 70°C for 3 hours to obtain a reaction solution.

The obtained reaction liquid was cooled to room temperature, put into a large amount of methanol in a yarn shape, and the precipitated precipitate was taken out, and after being immersed in methanol for 6 hours, it was washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain a polyamideimide resin (1).

The polyamideimide resin (1) was dissolved in DMAc to obtain a 10% by mass solution, and the obtained polyamideimide varnish was filtered through a filter having a pore size of 10 μm, and then a polyester substrate (manufactured by Toyobo Corporation, brand name " A4100") on the smooth surface of the self-supporting film was applied using an applicator so that the thickness of the self-supporting film was 55 µm, dried at 50° C. for 30 minutes, and then at 140° C. for 15 minutes, and then the obtained coating film was peeled from the polyester substrate to form a self-supporting film. Got it. The self-supporting film was fixed to a metal frame, and further dried at 200°C for 40 minutes under air to obtain an optical film 1 having a thickness of 50 μm.

<Comparative Example 1>

In a nitrogen gas atmosphere, 313.57 g of DMAc was added to a 1 L separable flask equipped with a stirring blade, and a required amount of ion-exchanged water was added so that the moisture content became 700 ppm. Then, 18.27 g (57.05 mmol) of TFMB was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 7.76 g (17.47 mmol) of 6FDA was added to the flask, cooled to 10°C, and stirred for 16 hours. Then, 1.72 g (5.85 mmol) of OBBC, followed by 6.38 g (31.43 mmol) of TPC were added to the flask, followed by stirring at 10° C. for 30 minutes. Subsequently, 313.57 g of DMAc adjusted to a moisture content of 700 ppm was added, and after stirring for 10 minutes, 0.71 g (3.50 mmol) of TPC was additionally added to the flask, and after stirring at 10° C. for 30 minutes, additional TFMB 0.186 After adding g (0.581 mmol) and stirring for 30 minutes, 0.0932 g (0.291 mmol) of TFMB was further added, followed by stirring for 2 hours. Next, diisopropylethylamine 5.27 g (40.76 mmol), 4-methylpyridine 3.80 g (40.76 mmol), and acetic anhydride 12.48 g (122.27 mmol) were added to the flask, followed by stirring at 10°C for 30 minutes. . After that, using an oil bath, the temperature was raised in stages from 10℃ to 50℃ for 20 minutes, from 50℃ to 60℃ for 20 minutes, and from 60℃ to 75℃ for 20 minutes, and kept warm at 75℃ for 3 hours. It stirred and obtained the reaction liquid.

The obtained reaction solution was cooled to room temperature, put into a large amount of methanol in a yarn shape, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain a polyamideimide resin (2).

Except having used the said polyamide-imide resin (2), it carried out similarly to Example 1, and obtained the optical film 2 of 50 micrometers in thickness.

<Comparative Example 2>

In a nitrogen gas atmosphere, to a 1 L separable flask equipped with a stirring blade, 313.57 g of DMAc was added. At this time, the moisture content in DMAc was 300 ppm. Then, 18.36 g (57.33 mmol) of TFMB was added, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 7.72 g (17.38 mmol) of 6FDA was added to the flask, cooled to 10°C, and stirred for 16 hours. Then, 1.71 g (5.81 mmol) of OBBC, followed by 6.35 g (31.28 mmol) of TPC were added to the flask, followed by stirring at 10° C. for 30 minutes. Subsequently, 313.57 g of DMAc with a water content of 300 ppm was added, and after stirring for 10 minutes, 0.71 g (3.48 mmol) of TPC was further added to the flask, followed by stirring for 2 hours. Then, 5.24 g (40.54 mmol) of diisopropylethylamine, 7.55 g (81.08 mmol) of 4-methylpyridine, and 26.61 g (260.60 mmol) of acetic anhydride were added to the flask, followed by stirring at 10° C. for 30 minutes. After that, using an oil bath, the temperature was raised in stages from 10℃ to 55℃ for 20 minutes, from 55℃ to 65℃ for 20 minutes, and from 65℃ to 85℃ for 20 minutes, and additionally kept warm at 85℃ for 3 hours. It stirred and obtained the reaction liquid.

The obtained reaction solution was cooled to room temperature, put into a large amount of methanol in a yarn shape, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain a polyamideimide resin (3).

Except having used the said polyamide-imide resin (3), it carried out similarly to Example 1, and obtained the optical film 3 of 50 micrometers in thickness.

<Example 2>

In a nitrogen atmosphere, to a 3 m 3 reaction vessel equipped with a stirring blade, 23.66 kg of TFMB and DMAc adjusted to a moisture content of 300 ppm were added so that the solid content concentration of TFMB in the reaction mixture was 5.54 mass%, and stirred at room temperature. While TFMB was dissolved in DMAc. Next, 6FDA was added to the reaction vessel to be 30.21 mol% based on TFMB, and stirred at 25°C for 16 hours. Thereafter, TPC and OBBC were added so as to be 60.42 mol% and 10.07 mol%, respectively, with respect to TFMB, and stirred for 60 minutes. Subsequently, 4-methylpyridine and acetic anhydride were added so as to be 35.25 mol% and 105.74 mol% with respect to TFMB, respectively, and after stirring for 30 minutes, the average temperature of the wall and bottom portions of the reaction mixture was from 25°C to 50°C. After raising the temperature for 30 minutes until the temperature is reached, 50 to 60°C for 10 minutes, and 60 to 65°C for 10 minutes, step by step over 10 minutes until the temperature reaches 65°C to 70°C. The temperature was raised. At this time, a heating part is provided on the wall of the reaction vessel to heat about 70% from the top of the liquid level of the reaction mixture, and the remaining bottom is a non-heating part, so that a temperature difference occurs between the wall surface and the bottom of the reaction vessel. By setting, the wall surface of the reaction vessel was heated, and only the vicinity of the wall surface of the reaction mixture was locally heated. In this state, the mixture was stirred for 3 hours to obtain a reaction solution. At the end of the reaction, the unheated bottom portion was 65°C, whereas the locally heated wall portion was 81°C.

The obtained reaction solution was cooled to room temperature, and 1.6 times the weight ratio of methanol and 0.55 times water were added while stirring with respect to the reaction solution, and the precipitated precipitate was taken out and washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain a polyamideimide resin (4). The weight average molecular weight of the obtained polyamideimide resin (4) was 429,000.

The polyamideimide resin (4) was dissolved in DMAc to obtain a 10% by mass solution, and the obtained polyamideimide varnish was filtered through a filter having a pore size of 10 µm, and then a polyester substrate (manufactured by Toyobo Co., Ltd., brand name " A4100") on the smooth surface of the self-supporting film was applied using an applicator so that the thickness of the self-supporting film was 55 µm, dried at 50° C. for 30 minutes, and then at 140° C. for 15 minutes, and then the obtained coating film was peeled from the polyester substrate, thereby forming the self-supporting film. Got it. The self-supporting film was fixed to a metal frame, and further dried at 200°C for 40 minutes under air to obtain an optical film 4 having a thickness of 50 μm.

<Example 3>

In a nitrogen atmosphere, to a 3 m 3 reaction vessel equipped with a stirring blade, 23.66 kg of TFMB and DMAc adjusted to a moisture content of 300 ppm were added so that the solid content concentration of TFMB in the reaction mixture was 5.54 mass%, and stirred at room temperature. While TFMB was dissolved in DMAc. Next, 6FDA was added to the reaction vessel to be 30.21 mol% based on TFMB, and stirred at 25°C for 16 hours. Thereafter, TPC and OBBC were added so as to be 60.42 mol% and 10.07 mol%, respectively, with respect to TFMB, and stirred for 60 minutes. Subsequently, 4-methylpyridine and acetic anhydride were added so as to be 35.25 mol% and 105.74 mol%, respectively, with respect to TFMB, and after stirring for 30 minutes, the average temperature of the wall and bottom portions of the reaction mixture was from 25°C to 50°C. After raising the temperature for 30 minutes until the temperature is reached, 50 to 60°C for 10 minutes, and 60 to 65°C for 10 minutes, step by step over 10 minutes until the temperature reaches 65°C to 70°C. The temperature was raised. At this time, a heating part is provided on the wall of the reaction vessel to heat about 70% from the top of the liquid level of the reaction mixture, and the remaining bottom is a non-heating part, so that a temperature difference occurs between the wall surface and the bottom of the reaction vessel. By setting, the wall surface of the reaction vessel was heated, and only the vicinity of the wall surface of the reaction mixture was locally heated. It stirred for 3 hours in this state, and obtained the reaction liquid. At the end of the reaction, the unheated bottom portion was 68°C, whereas the locally heated wall portion was 78°C.

The obtained reaction solution was cooled to room temperature, and 1.6 times the weight ratio of methanol and 0.55 times water were added while stirring with respect to the reaction solution, and the precipitated precipitate was taken out and washed with methanol. Next, the precipitate was dried under reduced pressure at 60°C to obtain a polyamideimide resin (5). The weight average molecular weight of the obtained polyamideimide resin (5) was 410,000.

The polyamideimide resin (5) was dissolved in DMAc to obtain a 10% by mass solution, and the obtained polyamideimide varnish was filtered through a filter having a pore size of 10 μm, and then a polyester substrate (manufactured by Toyobo Corporation, brand name " A4100") on the smooth surface of the self-supporting film was applied using an applicator so that the thickness of the self-supporting film was 55 µm, dried at 50° C. for 30 minutes, and then at 140° C. for 15 minutes, and then the obtained coating film was peeled from the polyester substrate, thereby forming the self-supporting film. Got it. The self-supporting film was fixed to a metal frame, and further dried at 200°C for 40 minutes under air to obtain an optical film 5 having a thickness of 50 μm.

For Examples and Comparative Examples, the weight average molecular weight of the polyamideimide resin, the elastic modulus of the optical film, the total light transmittance (Tt), haze, and YI values were measured. In addition, using the optical film after storage for 1 week in an environment of 85°C and 85% relative humidity, similarly, the weight average molecular weight, YI value and the number of flexion resistance were measured, and their rate of change was calculated according to the above equation. I did. The obtained results are shown in Table 1 below. In addition, about the optical film of Comparative Example 1, the rate of change of the YI value was very large, and since it was not usable as an optical film, evaluation of the number of times of bending resistance was not performed.

Claims (13)

In the ¹ H- ¹³ C HSQC spectrum obtained from the polyamide-imide resin in deuterated dimethyl sulfoxide was added to the test sample, and the proton chemical shift that 8.06~8.14 ppm, Furthermore, in the chemical shift of the carbon 129.6~130.3 ppm Integral value of the peak present in the region (A) (int _A ) and the peak present in the region (B) where the chemical shift of proton is 7.26 to 7.85 ppm and the chemical shift of carbon is 132.4 to 134.0 ppm Polyamideimide resin, wherein the ratio of the value (int _{B ) (int A} /int _B ) is 1.5% or less. The method of claim 1,
Equation (1):

[In formula (1), Y represents a tetravalent organic group,
X represents a divalent organic group,
* Represents a bond hand]
The structural unit represented by, and, formula (2):

[In formula (2), Z and X each independently represent a divalent organic group,
* Represents a bond hand]
A polyamide-imide resin having at least a structural unit represented by. The method of claim 1,
A polyamideimide resin having a weight average molecular weight of 200,000 or more and 1,000,000 or less. The method of claim 1,
As X in formula (1) or X in formula (2), formula (4):

[In formula (4), H ^4a and H ^4b represent a hydrogen atom,
R ^4a to ^{R 4d} 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 4a} to ^{R 4d are,} Independently of each other, they may be substituted with a halogen atom,
* Represents a bond hand]
A polyamide-imide resin having at least a structure represented by. The method of claim 1,
As Z in formula (2), formula (3):

[In formula (3), R ^3a and R ^3b represent, independently of each other, 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 are included in ^{R 3a} and R ^3b The hydrogen atoms used may be independently of each other and may be substituted with a halogen atom,
W 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 )-, and 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. ,
s is an integer from 0 to 4,
t is an integer from 0 to 4,
u is an integer from 0 to 4,
* Represents a bond hand]
A polyamideimide resin having at least a structure represented by. An optical film containing the polyamideimide resin according to any one of claims 1 to 5. An optical film containing a polyamideimide resin, wherein the optical film has a rate of change of 26% or less in the weight average molecular weight before and after a storage test in which the optical film is stored for one week under conditions of 85°C and 85% humidity. The method of claim 7,
The optical film, wherein the rate of change of the weight average molecular weight before and after the storage test is 25% or less. A front plate of a flexible display device having the optical film according to claim 6. A flexible display device comprising the front plate according to claim 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 method for producing a polyamideimide resin in which a diamine compound, a tetracarboxylic acid compound, and a dicarboxylic acid compound are reacted, wherein the ratio of the number of moles of the diamine compound to the total number of moles of the tetracarboxylic acid compound and the dicarboxylic acid compound is 1.000. The method for producing a polyamideimide resin according to any one of claims 1 to 5 which is exceeded.