CN110191910B

CN110191910B - Polyamideimide resin and optical member comprising the same

Info

Publication number: CN110191910B
Application number: CN201880007377.6A
Authority: CN
Inventors: 宫本皓史; 増井希望; 杉山纮子; 望月胜纪; 池内淳一
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2017-01-20
Filing date: 2018-01-15
Publication date: 2021-10-29
Anticipated expiration: 2038-01-15
Also published as: KR102475748B1; CN110191910A; JP7084710B2; KR20190102286A; JP2018119132A

Abstract

The invention provides a polyamideimide resin for an optical member which achieves both high flexibility and high bending resistance, particularly a polyamideimide resin for a front panel of an image display device, and an optical member such as a front panel comprising the polyamideimide resin. A polyamide-imide resin having structural units represented by the following formulae (1) and (2). In the formulas (1) and (2), X and Z independently represent an organic group with a valence of 2, Y represents an organic group with a valence of 4, at least one part of Z is a structural unit represented by a formula (3), and in the formula (3), R¹～R⁸Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹～R⁸Each independently of the others, may be substituted by halogen atoms, A represents-O-, -S-, -CO-or-NR⁹‑，R⁹Represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom, and m is an integer of 1 to 4.

Description

Polyamideimide resin and optical member comprising the same

Technical Field

The present invention relates to a polyamideimide resin and an optical member comprising the polyamideimide resin.

Background

Currently, image display devices such as liquid crystal display devices and organic EL display devices are widely used not only for televisions but also for various applications such as mobile phones and smartwatches. With such expansion of use, an image display device (flexible display) having flexible characteristics is being sought.

The image display device includes a display element such as a liquid crystal display element or an organic EL display element, and a polarizing plate, a retardation plate, a front panel, and other components. In order to realize a flexible display, all of the above-described constituent members need to have flexibility.

Heretofore, glass has been used as the front panel. Glass has high transparency and can exhibit high hardness depending on the kind of glass, but on the other hand, it is very rigid and easily broken, and thus it is difficult to use it as a front panel material for a flexible display.

Therefore, application of polymer materials has been studied as materials replacing glass. A front panel made of a polymer material is expected to be used for various applications because it is easy to exhibit flexibility. Examples of the resin having flexibility include various resins, and polyamide-imide resins are one of them. Polyamide-imide resins have been used for various purposes from the viewpoint of transparency and heat resistance (patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent application No. 2010-150552

Disclosure of Invention

Problems to be solved by the invention

When the flexible display is bent, all the constituent members are bent. If the flexibility of each component member is insufficient, other component members may be damaged. Therefore, the front panel, which is one of the constituent members, is also required to have high flexibility. Meanwhile, if wrinkles remain on the surface of the front panel after bending, a problem arises in visibility of the display, and therefore the front panel needs to have high bending resistance.

Accordingly, an object of the present invention is to provide a polyamideimide resin for an optical member which achieves both high flexibility and high bending resistance, particularly a polyamideimide resin for a front panel of an image display device, and an optical member such as a front panel including the polyamideimide resin.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have completed the present invention.

That is, the present invention provides the following preferred embodiments.

[1] A polyamideimide resin having structural units represented by the formulae (1) and (2).

[ chemical formula 1]

[ in the formulae (1) and (2), X and Z each independently represent a 2-valent organic group,

y represents an organic group having a valence of 4,

at least a part of Z is a structural unit represented by formula (3) ]

[ chemical formula 2]

[ in formula (3), R¹～R⁸Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹～R⁸Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

a represents-O-, -S-, -CO-or-NR⁹-，R⁹Represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom,

m is an integer of 1 to 4,

represents a chemical bond ]

[2] The polyamideimide resin according to the above [1], wherein the content of the structural unit represented by the formula (3) is 3 mol% or more and 90 mol% or less with respect to the total of Y and Z.

[3] The polyamideimide resin according to the above [1], wherein 5 mol% or more and 100 mol% or less of Z is represented by the formula (3).

[4] The polyamideimide resin according to the above [1], wherein a ratio of the structural unit represented by the formula (3) is 3 mol% or more and 90 mol% or less with respect to a total of the structural unit represented by the formula (1) and the structural unit represented by the formula (2).

[5] The polyamideimide resin according to any one of the above [1] to [4], wherein the content of the structural unit represented by the formula (1) is 10 mol% or more and 90 mol% or less with respect to the total of the structural unit represented by the formula (1) and the structural unit represented by the formula (2).

[6] The polyamideimide resin according to any one of the above [1] to [5], wherein at least a part of X is a structural unit represented by formula (4).

[ chemical formula 3]

[ in the formula (4), R¹⁰～R¹⁷Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁰～R¹⁷Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

represents a chemical bond ]

[7] The polyamideimide resin according to any one of the above [1] to [6], wherein at least a part of Y is a structural unit represented by formula (5).

[ chemical formula 4]

[ in the formula (5), R¹⁸～R²⁵Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁸～R²⁵Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

represents a chemical bond ]

[8] The polyamideimide resin according to any one of the above [1] to [7], wherein the glass transition temperature Tg calculated from tan. delta. in the DMA measurement is less than 380 ℃.

[9] An optical member comprising the polyamideimide resin according to any one of the above [1] to [8 ].

[10] An image display device comprising the optical member according to [9 ].

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can provide a polyamideimide resin for an optical member that achieves both high flexibility and high bending resistance, particularly a polyamideimide resin for a front panel of an image display device, and an optical member such as a front panel including the polyamideimide resin. Further, according to the present invention, an optical member having excellent surface hardness can be provided.

Detailed Description

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

The polyamide-imide resin according to one embodiment of the present invention is a polyamide-imide resin having a structural unit represented by formula (1) and a structural unit represented by formula (2).

[ chemical formula 5]

In formula (2), each Z independently represents a 2-valent organic group. The polyamideimide resin according to one embodiment of the present invention may include a plurality of kinds of Z, and the plurality of kinds of Z may be the same or different. At least a part of Z is a structural unit represented by formula (3).

[ chemical formula 6]

[ in the formula (3), R¹～R⁸Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹～R⁸Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

m is an integer of 1 to 4,

denotes a bond. ]

In formula (3), A each independently represents-O-, -S-, -CO-, or-NR⁹From the viewpoint of flexibility of an optical member comprising the polyamideimide resin, the compound preferably represents-O-or-S-, and more preferably represents-O-. R¹～R⁸Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and preferably represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and further preferably a hydrogen atom, from the viewpoint of flexibility and surface hardness of an optical member comprising the polyamideimide resin. Here, R¹～R⁸Each hydrogen atom contained in (a) may be independently substituted with a halogen atom. R⁹Represents a hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a halogen atom.

In the formula (3), when m is an integer in the range of 1 to 4, and m is within the above range, the flexibility of the optical member is good. In the formula (3), m is preferably an integer in the range of 1 to 3, more preferably 1 or 2, and further preferably 1, and when m is within the above range, the flexibility of the optical member is good and the availability of the raw material is good.

In a preferred embodiment of the present invention, formula (3) is a structural unit represented by formula (3 '), that is, at least a part of a plurality of Z is a structural unit represented by formula (3'). In this case, an optical member comprising the polyamideimide resin can exhibit high surface hardness, low elastic modulus, and high flexibility.

[ chemical formula 7]

In a preferred embodiment of the present invention, the content of the structural unit represented by formula (3) is preferably 3 mol% or more, more preferably 5 mol% or more, still more preferably 7 mol% or more, still more preferably 9 mol% or more, particularly preferably 15 mol% or more, very preferably 30 mol% or more, preferably 90 mol% or less, more preferably 87 mol% or less, further preferably 85 mol% or less, particularly preferably 83 mol% or less, and very preferably 80 mol% or less, relative to the total of Y and Z in the polyamideimide resin. When the content of the structural unit represented by formula (3) is not less than the lower limit relative to the total of Y and Z in the polyamideimide resin, an optical member comprising the polyamideimide resin has a low elastic modulus, excellent flexibility, and high surface hardness. When the content of the structural unit represented by formula (3) is not more than the upper limit value with respect to the total of Y and Z in the polyamideimide resin, thickening due to hydrogen bonds between amide bonds derived from formula (3) is suppressed, whereby the viscosity of the polyamideimide varnish described later can be suppressed, and the optical member can be easily processed. The content of the structural unit represented by the formula (3) is, for exampleCan be used¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

In a preferred embodiment of the present invention, preferably 5 mol% or more, more preferably 7 mol% or more, still more preferably 9 mol% or more, and particularly preferably 11 mol% or more of Z in the polyamideimide resin is represented by the formula (3). When the lower limit value of Z in the polyamideimide resin is represented by formula (3) or more, an optical member comprising the polyamideimide resin can exhibit high surface hardness, low elastic modulus, and high flexibility. Preferably, 100 mol% or less of Z in the polyamideimide resin is represented by formula (3). The content of the structural unit represented by the formula (3) in the polyamideimide resin can be, for example, the content of the structural unit¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

In a preferred embodiment of the present invention, the proportion of the structural unit represented by formula (3) is preferably 3 mol% or more, more preferably 5 mol% or more, further preferably 7 mol% or more, further more preferably 9 mol% or more, particularly preferably 15 mol% or more, very preferably 30 mol% or more, preferably 90 mol% or less, more preferably 87 mol% or less, further preferably 85 mol% or less, particularly preferably 83 mol% or less, and very preferably 80 mol% or less, relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the polyamide imide resin. When the ratio of the structural unit represented by formula (3) to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the polyamideimide resin is not less than the lower limit value, an optical member comprising the polyamideimide resin has a low elastic modulus, excellent flexibility, and high surface hardness. When the ratio of the structural unit represented by formula (3) to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2) in the polyamideimide resin is not more than the above upper limit, the thickening due to hydrogen bonds between amide bonds derived from formula (3) is suppressed, whereby the viscosity of the polyamideimide varnish described later can be suppressed, and the viscosity can be easily suppressedThe optical member is processed. The content of the structural unit represented by the formula (3) can be determined, for example¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

In the formulae (1) and (2), X each independently represents a 2-valent organic group, and is 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. X in formula (1) may be the same as or different from X in formula (2). The polyamideimide resin according to an embodiment of the present invention may include a plurality of kinds of X, and the plurality of kinds of X may be the same or different. Examples of X may include a group represented by the following formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) or formula (18); a group in which a hydrogen atom in the group represented by these formulae 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.

[ chemical formula 8]

[ formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) or formula (18) < CHEM > represents a bond,

V¹～V³each independently represents a single bond, -O-, -S-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or-CO-.]

V¹And V²Bonding position with respect to each ring, and V²And V³The bonding position to each ring is preferably meta or para, and more preferably para, to each ring.

Among the groups represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) or formula (18), formula (13), formula (14), formula (15), formula (16) or formula (18) are preferable from the viewpoint of the surface hardness and flexibility of the optical member comprising the polyamideimide resin(17) The group represented by the formula (14), the formula (15) or the formula (16) is more preferable. V is a value obtained from the viewpoint of the surface hardness and flexibility of an optical member comprising the polyamideimide resin¹～V³Each independently is preferably a single bond, -O-or-S-, more preferably a single bond or-O-.

In a preferred embodiment of the present invention, at least a part of the plurality of xs in the formulae (1) and (2) is a structural unit represented by the formula (4). When at least a part of the plurality of xs in the formula (1) and the formula (2) is a group represented by the formula (4), the optical member comprising the polyamideimide resin can exhibit high surface hardness while exhibiting high transparency.

[ chemical formula 9]

denotes a bond. ]

In the formula (4), R¹⁰～R¹⁷Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R represents¹⁰～R¹⁷Each hydrogen atom contained in (a) may be independently substituted with a halogen atom. From the viewpoint of surface hardness, flexibility and transparency of an optical member comprising the polyamideimide resin, R¹⁰～R¹⁷Each independently is further preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and particularly preferably a hydrogen atom or a trifluoromethyl group.

In a preferred embodiment of the present invention, the structural unit represented by formula (4) is a structural unit represented by formula (4 '), that is, at least a part of the plurality of xs is a structural unit represented by formula (4'). In this case, the optical member comprising the polyamideimide resin exhibits high transparency, and the fluorine-containing skeleton can improve the solubility of the polyamideimide resin in a solvent, thereby suppressing the viscosity of the polyamideimide varnish to a low level and facilitating the processing of the optical member.

[ chemical formula 10]

[ in the formula (4'), represents a bond ]

In a preferred embodiment of the present invention, preferably 30 mol% or more, more preferably 50 mol% or more, further preferably 60 mol% or more, and particularly preferably 70 mol% or more of X in the polyamideimide resin is represented by formula (4), particularly formula (4'). When X in the above range in the polyamideimide resin is represented by formula (4), particularly formula (4'), the optical member comprising the polyamideimide resin exhibits high transparency and, at the same time, can be improved in solubility in a solvent by a fluorine element-containing skeleton, can be suppressed in viscosity to a low level, and can be easily processed into an optical member. In the polyamideimide resin, 100 mol% or less of X is preferably represented by formula (4), particularly formula (4'). The X in the above polyamideimide resin may be formula (4), especially formula (4'). The content of the structural unit represented by the formula (4) of X in the polyamideimide resin can be, for example, used¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

In formula (1), Y each independently represents a 4-valent 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. The polyamideimide resin according to one embodiment of the present invention may include a plurality of kinds of Y, and the plurality of kinds of Y may be the same or different. Examples of Y may include a group represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29); a group in which a hydrogen atom in the group represented by these formulae is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; and a chain hydrocarbon group having a valence of 4 and 6 or less carbon atoms.

[ chemical formula 11]

[ formula (20) to formula (29),

the symbol represents a chemical bond,

W¹represents a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-、-C(CF₃)₂-、-Ar-、-SO₂-、-CO-、-O-Ar-O-、-Ar-O-Ar-、-Ar-CH₂-Ar-、-Ar-C(CH₃)₂-Ar-or-Ar-SO₂-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 specific examples thereof include phenylene groups.]

Among the groups represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) and formula (29), the group represented by formula (26), formula (28) or formula (29) is preferred, and the group represented by formula (26) is more preferred, from the viewpoint of the surface hardness and flexibility of the optical member comprising the polyamideimide resin. From the viewpoint of easily suppressing the yellowness, a group represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26) or formula (27); and groups in which a hydrogen atom in these groups is substituted with a methyl group, a fluoro group, a chloro group or a trifluoromethyl group. In addition, from the viewpoint of surface hardness and flexibility of an optical member comprising the polyamideimide resin, W¹Each independently preferably being a single bond, -O-, -CH₂-、-CH₂-CH₂-、-CH(CH₃)-、-C(CH₃)₂-or-C (CF)₃)₂-, more preferably a single bond, -O-, -CH₂-、-CH(CH₃)-、-C(CH₃)₂-or-C (CF)₃)₂-, more preferably a single bond, -O-, -C (CH)₃)₂-or-C (CF)₃)₂-O-or-C (CF) is particularly preferred₃)₂-。

In a preferred embodiment of the present invention, at least a part of Y in formula (1) is a structural unit represented by formula (5). When at least a part of the plurality of Y in the formula (1) is a group represented by the formula (5), the optical member comprising the polyamideimide resin exhibits high transparency, and the polyamideimide resin can be improved in solubility in a solvent due to a high bendability skeleton, and the viscosity of the polyamideimide varnish can be suppressed to a low level, and the optical member can be easily processed.

[ chemical formula 12]

denotes a bond. ]

In the formula (5), R¹⁸～R²⁵Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, wherein R represents¹⁸～R²⁵Each hydrogen atom contained in (a) may be independently substituted with a halogen atom. From the viewpoint of surface hardness and flexibility of an optical member comprising the polyamideimide resin, R¹⁸～R²⁵Each independently is further preferably a hydrogen atom, a methyl group, a fluoro group, a chloro group or a trifluoromethyl group, and particularly preferably a hydrogen atom or a trifluoromethyl group.

In a preferred embodiment of the present invention, the structural unit represented by formula (5) is a group represented by formula (5 '), that is, at least a part of the plurality of Y is a structural unit represented by formula (5'). In this case, an optical member including the polyamideimide resin may have high transparency.

[ chemical formula 13]

[ in formula (5') ]

In a preferred embodiment of the present invention, preferably 50 mol% or more, more preferably 60 mol% or more, and still more preferably 70 mol% or more of Y in the polyamideimide resin is represented by formula (5), particularly formula (5'). When Y in the above range in the polyamideimide resin is represented by the formula (5), particularly the formula (5'), the optical member comprising the polyamideimide resin can have high transparency, and the solubility of the polyamideimide resin in a solvent can be improved by the fluorine element-containing skeleton, the viscosity of the polyamideimide varnish can be suppressed to a low level, and the production of the optical member can be easily carried out. Preferably, 100 mol% or less of Y in the polyamideimide resin is represented by formula (5), particularly formula (5'). Y in the above polyamideimide resin may be formula (5), particularly formula (5'). The content of the structural unit represented by the formula (5) in Y in the polyamideimide resin can be, for example, used¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

The weight average molecular weight (Mw) of the polyamideimide resin is preferably 5,000 or more, more preferably 10,000 or more, further preferably 50,000 or more, particularly preferably 70,000 or more, particularly preferably 100,000 or more, preferably 800,000 or less, more preferably 600,000 or less, further preferably 500,000 or less, particularly preferably 450,000 or less. When the weight average molecular weight (Mw) of the polyamideimide resin is not less than the lower limit, an optical member comprising the polyamideimide resin further has good bending resistance. When the weight average molecular weight (Mw) of the polyamideimide resin is not more than the upper limit, the viscosity of the polyamideimide varnish can be suppressed to a low level, and the optical member, particularly the optical film, can be easily stretched, and therefore, the processability is good. In the present invention, the weight average molecular weight (Mw) can be determined, for example, by GPC measurement in terms of standard polystyrene, and specifically, can be determined by the method described in examples.

In the polyamide-imide resin, the content of the structural unit represented by formula (1) is preferably 10 mol% or more, more preferably 15 mol% or more, further preferably 18 mol% or more, particularly preferably 20 mol% or more, preferably 90 mol% or less, more preferably 70 mol% or less, further preferably 60 mol% or less, and particularly preferably 50 mol% or less, relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2). In the above polyamideimide resin, when the content ratio of the structural unit represented by formula (1) is not less than the lower limit, the thickening due to hydrogen bonding between amide bonds in formula (2) can be suppressed, the viscosity of the polyamideimide varnish can be reduced, and the production of the optical member can be easily performed. When the content of the structural unit represented by formula (1) in the polyamideimide resin is not more than the upper limit, an optical member comprising the polyamideimide resin exhibits high surface hardness. The above ratio can be used, for example¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

In the polyamide-imide resin, the content of the structural unit represented by formula (2) is preferably 20 mol% or more, more preferably 30 mol% or more, further preferably 40 mol% or more, particularly preferably 50 mol% or more, preferably 80 mol% or less, more preferably 70 mol% or less, further preferably 60 mol% or less, and particularly preferably 50 mol% or less, relative to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2). In the above polyamideimide resin, when the content ratio of the structural unit represented by formula (1) is not more than the above upper limit, the thickening due to the hydrogen bond between the amide bonds in formula (2) can be suppressed, the viscosity of the polyamideimide varnish can be reduced, and the production of the optical member can be easily performed. On the upper partWhen the content of the structural unit represented by formula (1) in the polyamideimide resin is not less than the lower limit, an optical member comprising the polyamideimide resin exhibits high surface hardness. The above ratio can be used, for example¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

The glass transition temperature Tg of the polyamide imide resin calculated from tan δ in dynamic viscoelasticity measurement (DMA measurement) is preferably less than 380 ℃, more preferably 379 ℃ or less, still more preferably 378 ℃ or less, for example 370 ℃ or less. When the glass transition temperature Tg of the polyamideimide resin is lower than the upper limit value (or is not higher than the upper limit value), an optical member including the polyamideimide resin exhibits high surface hardness, and at the same time, has a low elastic modulus, and can have high flexibility. In order to control the glass transition temperature within the above range, the monomer constituting the polyamideimide is preferably a monomer containing a divalent group capable of imparting flexibility to the polyamideimide film obtained by film formation, and specific examples of the divalent group capable of imparting flexibility include-O-, -CH₂-、-CF₂-、-C(CH₃)₂-、-C(CF₃)₂As the monomer having a divalent group which can impart flexibility, a monomer having a divalent group containing — O "is more preferably contained. The glass transition temperature Tg of the polyamideimide resin is usually 300 ℃ or higher. The method for calculating the glass transition temperature from tan δ in the dynamic viscoelasticity measurement (DMA measurement) can be specifically performed as in the examples.

The polyamideimide resin may contain a structural unit represented by the formula (10-2) and/or a structural unit represented by the formula (11-2) in addition to the structural unit represented by the formula (1) and the structural unit represented by the formula (2).

[ chemical formula 14]

In the formula (10-2), Y¹Each independently is a 4-valent 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 Y¹Examples of the hydrocarbon group include a group represented by formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29), and a chain hydrocarbon group having 4-valent carbon atoms of 6 or less. The polyamideimide resin, which is one embodiment of the present invention, may include a plurality of Y' s¹Plural kinds of Y¹May be the same or different from each other.

In the formula (11-2), Y²Is a 3-valent 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 Y²Examples thereof include a group obtained by replacing any one of the chemical bonds of the group represented by the above formula (20), formula (21), formula (22), formula (23), formula (24), formula (25), formula (26), formula (27), formula (28) or formula (29) with a hydrogen atom, and a chain hydrocarbon group having 3-valent carbon atoms of 6 or less. The polyamideimide resin, which is one embodiment of the present invention, may include a plurality of Y' s²Plural kinds of Y²May be the same or different from each other.

In the formulae (10-2) and (11-2), X¹And X²Each independently is a 2-valent 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 X¹And X²Examples of the "substituent" may include a group represented by formula (10), formula (11), formula (12), formula (13), formula (14), formula (15), formula (16), formula (17) or formula (18); a group in which a hydrogen atom in the group represented by these formulae 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 formed of a structural unit represented by the formula (1), a structural unit represented by the formula (2), and, optionally, a structural unit represented by the formula (10-2) and/or the formula (11-2). In the polyamideimide resin, the structural unit represented by formula (1) and the formula (2) are shown in the following table from the viewpoint of flexibility and surface hardness of an optical member comprising the polyamideimide resinThe structural units shown are preferably 80% or more, more preferably 90% or more, and still more preferably 95% or more, based on the total structural units represented by the formulae (1) and (2) and, if necessary, the formulae (10-2) and (11-2). In the above polyamideimide resin, the content ratio of the structural unit represented by the formula (1) and the structural unit represented by the formula (2) is usually 100% or less based on the total structural units represented by the formula (1) or the formula (2) or, if necessary, the formula (10-2) or the formula (11-2). The content ratio can be used, for example¹H-NMR, or it can be calculated from the charge ratio of the starting materials.

The polyamideimide resin can be produced, for example, from a tetracarboxylic acid compound, a dicarboxylic acid compound, and a diamine compound, which will be described later, as main raw materials. Here, the dicarboxylic acid compound contains at least a compound represented by the formula (3').

[ chemical formula 15]

[ formula (3) ], R¹～R⁸Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹～R⁸Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

m is an integer of 1 to 4,

R³¹and R³²Each independently is-OH or-Cl.]

In a preferred embodiment, the dicarboxylic acid compound is a compound represented by the formula (3') wherein A is-O-. In another preferred embodiment, the dicarboxylic acid compound is R³²A compound represented by the formula (3') which is-Cl. In addition, a diisocyanate compound may be used instead of the diamine compound.

Examples of tetracarboxylic acid compounds that can be used for the synthesis of the polyamideimide resin include aromatic tetracarboxylic acid and anhydrides thereof, preferably aromatic tetracarboxylic acid compounds such as dianhydrides thereof; and aliphatic tetracarboxylic acid and anhydride thereof, preferably an aliphatic tetracarboxylic acid compound such as dianhydride thereof. The tetracarboxylic acid compound may be used alone or in combination of 2 or more. The tetracarboxylic acid compound may be a tetracarboxylic acid compound analog such as an acid chloride compound, in addition to the dianhydride. These may be used alone or in combination of 2 or more.

Examples of the aromatic tetracarboxylic dianhydride include non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides, and condensed polycyclic aromatic tetracarboxylic dianhydrides. Specific examples of the non-condensed polycyclic aromatic tetracarboxylic acid dianhydride include 4,4 '-oxydiphthalic dianhydride (sometimes referred to as OPDA), 3, 3', 4,4 '-benzophenone tetracarboxylic acid dianhydride, 2', 3,3 '-benzophenone tetracarboxylic acid dianhydride, 3, 3', 4,4 '-biphenyl tetracarboxylic acid dianhydride (sometimes referred to as BPDA), 2', 3,3 '-biphenyl tetracarboxylic acid dianhydride, 3, 3', 4,4 '-diphenylsulfone tetracarboxylic acid dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 2-bis (3, 4-dicarboxyphenoxyphenyl) propane dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic acid dianhydride (sometimes referred to as 6FDA), and the like, 1, 2-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1-bis (2, 3-dicarboxyphenyl) ethane dianhydride, 1, 2-bis (3, 4-dicarboxyphenyl) ethane dianhydride, 1-bis (3, 4-dicarboxyphenyl) ethane dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, 4 '- (p-phenylenedioxy) diphthalic dianhydride, 4' - (m-phenylenedioxy) diphthalic dianhydride. Further, examples of the monocyclic aromatic tetracarboxylic acid dianhydride include 1,2,4, 5-benzenetetracarboxylic acid dianhydride, examples of the condensed polycyclic aromatic tetracarboxylic acid dianhydride include 1,2,4, 5-benzenetetracarboxylic acid dianhydride, and examples of the condensed polycyclic aromatic tetracarboxylic acid dianhydride include 2,3,6, 7-naphthalenetetracarboxylic acid dianhydride. These may be used alone or in combination of 2 or more.

Among these, 4,4 '-oxydiphthalic dianhydride, 3, 3', 4,4 '-benzophenonetetracarboxylic dianhydride, 2', 3,3 '-benzophenonetetracarboxylic dianhydride, 3, 3', 4,4 '-biphenyltetracarboxylic dianhydride, 2', 3,3 '-biphenyltetracarboxylic dianhydride, 3, 3', 4,4 '-diphenylsulfonetetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 2-bis (2, 3-dicarboxyphenyl) propane dianhydride, 2-bis (3, 4-dicarboxyphenoxyphenyl) propane dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride, 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-bis (3, 4-dicarboxyphenyl) ethane dianhydride, bis (3, 4-dicarboxyphenyl) methane dianhydride, bis (2, 3-dicarboxyphenyl) methane dianhydride, 4,4 '- (p-phenylenedioxy) diphthalic dianhydride and 4, 4' - (m-phenylenedioxy) diphthalic dianhydride, more preferably 4,4 '-oxydiphthalic dianhydride, 3', 4,4 '-biphenyltetracarboxylic dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride.

Examples of the aliphatic tetracarboxylic dianhydride include cyclic and acyclic aliphatic tetracarboxylic dianhydrides. The cyclic aliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include cycloalkanetetracarboxylic dianhydrides such as 1,2,4, 5-cyclohexanetetracarboxylic dianhydride, 1,2,3, 4-cyclobutanetetracarboxylic dianhydride and 1,2,3, 4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, dicyclohexyl-3, 3 '-4, 4' -tetracarboxylic dianhydride and positional isomers thereof. These may be used alone or in combination of 2 or more. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydride include 1,2,3, 4-butanetetracarboxylic acid dianhydride, and 1,2,3, 4-pentanedicarboxylic acid dianhydride, and these can be used alone or in combination of 2 or more. In addition, cyclic aliphatic tetracarboxylic dianhydride and acyclic aliphatic tetracarboxylic dianhydride may be used in combination.

Among the tetracarboxylic dianhydrides, from the viewpoint of high surface hardness, high flexibility, high bending resistance, high transparency and low coloring property of the optical member, 4,4 '-oxydiphthalic dianhydride, 3, 3', 4,4 '-benzophenone tetracarboxylic dianhydride, 3, 3', 4,4 '-biphenyl tetracarboxylic dianhydride, 2', 3,3 '-biphenyl tetracarboxylic dianhydride, 3, 3', 4,4 '-diphenylsulfone tetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride and mixtures thereof are preferable, and 4,4 '-oxydiphthalic dianhydride, 3, 3', 4,4 '-biphenyl tetracarboxylic dianhydride and 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride, and mixtures thereof are more preferable, And mixtures thereof, more preferably 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride.

As the dicarboxylic acid compound that can be used for the synthesis of the polyamideimide resin, 4' -oxybis benzoic acid and/or its acid chloride compound can be preferably used. Specifically, 4' -oxybis (benzoyl chloride) is given as a preferable example. In addition to 4, 4' -oxybis benzoic acid or its acid chloride compound, other dicarboxylic acid compounds may be used. Examples of the other dicarboxylic acid compounds include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and acid chloride compounds and acid anhydrides similar thereto, and 2 or more kinds thereof may be used in combination. Specific examples thereof include terephthalic acid; isophthalic acid; naphthalenedicarboxylic acid; 4, 4' -biphenyldicarboxylic acid; 3, 3' -biphenyldicarboxylic acid; dicarboxylic acid compound of chain hydrocarbon having 8 or less carbon atoms and 2 benzoic acid with single bond, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or phenylene group-linked compounds and their acid chloride compounds. Specifically, terephthaloyl chloride is given as a preferable example.

The polyamideimide resin may be obtained by reacting a tetracarboxylic acid compound that can be used in the polyamideimide synthesis, and further reacting a tetracarboxylic acid, a tricarboxylic acid, and anhydrides and derivatives thereof, within a range that does not impair various physical properties of an optical member including the polyamideimide resin.

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

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acid, aliphatic tricarboxylic acid, and acid chloride compounds and acid anhydrides similar thereto, and 2 or more kinds thereof may be used in combination.

Specific examples thereof include anhydrides of 1,2, 4-benzenetricarboxylic acid; 2,3, 6-naphthalene tricarboxylic acid-2, 3-anhydride; phthalic anhydride with benzoic acid by single bond, -O-, -CH₂-、-C(CH₃)₂-、-C(CF₃)₂-、-SO₂-or phenylene groups.

Examples of the diamine compound that can be used for synthesizing the polyamideimide resin include aliphatic diamines, aromatic diamines, and mixtures thereof. In this embodiment, the "aromatic diamine" refers to a diamine in which an amino group is directly bonded to an aromatic ring, and may include an aliphatic group or another substituent in a part of the structure. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a fluorene ring, but are not limited thereto. Of these, benzene rings are preferred. The "aliphatic diamine" refers to a diamine in which an amino group is directly bonded to an aliphatic group, and may contain an aromatic ring or other substituent in a part of the structure.

Examples of the aliphatic diamine include acyclic aliphatic diamines such as hexamethylenediamine and cyclic aliphatic diamines such as 1, 3-bis (aminomethyl) cyclohexane, 1, 4-bis (aminomethyl) cyclohexane, norbornanediamine and 4, 4' -diaminodicyclohexylmethane. These may be used alone or in combination of 2 or more.

Examples of the aromatic diamine include aromatic diamines having 1 aromatic ring such as p-phenylenediamine, m-phenylenediamine, 2, 4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1, 5-diaminonaphthalene, and 2, 6-diaminonaphthalene; 4,4 '-diaminodiphenylmethane, 4' -diaminodiphenylpropane, 4 '-diaminodiphenyl ether (sometimes referred to as ODA), 3, 4' -diaminodiphenyl ether, 3 '-diaminodiphenyl ether, 4' -diaminodiphenyl sulfone, 3 '-diaminodiphenyl sulfone, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 4' -diaminodiphenyl sulfone, bis [4- (4-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, methyl methacrylate, ethyl methacrylate, and the like, Aromatic diamines having 2 or more aromatic rings, such as 2, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2 ' -dimethylbenzidine (sometimes referred to as MB), 2 ' -bis (trifluoromethyl) benzidine (sometimes referred to as TFMB), 4 ' -bis (4-aminophenoxy) biphenyl, 9-bis (4-aminophenyl) fluorene, 9-bis (4-amino-3-methylphenyl) fluorene, 9-bis (4-amino-3-chlorophenyl) fluorene, and 9, 9-bis (4-amino-3-fluorophenyl) fluorene. These may be used alone or in combination of 2 or more.

The aromatic diamine is preferably 4,4 '-diaminodiphenylmethane, 4' -diaminodiphenylpropane, 4 '-diaminodiphenylether, 3' -diaminodiphenylether, 4 '-diaminodiphenylsulfone, 3' -diaminodiphenylsulfone, 1, 4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, bis [4- (3-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (3-aminophenoxy) phenyl ] propane, 2 '-dimethylbenzidine, 2' -bis (trifluoromethyl) -4,4 '-diaminobiphenyl, 4' -bis (4-aminophenoxy) biphenyl, more preferably 4,4 '-diaminodiphenylmethane, 4' -diaminodiphenylpropane, 4 '-diaminodiphenyl ether, 4' -diaminodiphenylsulfone, 1, 4-bis (4-aminophenoxy) benzene, bis [4- (4-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2 '-dimethylbenzidine, 2' -bis (trifluoromethyl) -4,4 '-diaminobiphenyl, 4' -bis (4-aminophenoxy) biphenyl. These may be used alone or in combination of 2 or more.

Among the above diamine compounds, 1 or more selected from the group consisting of aromatic diamines having a biphenyl structure are preferably used from the viewpoints of high surface hardness, high flexibility, high bending resistance, high transparency, and low coloring properties of the optical member. More preferably, 1 or more selected from the group consisting of 2,2 ' -dimethylbenzidine, 2 ' -bis (trifluoromethyl) benzidine, 4 ' -bis (4-aminophenoxy) biphenyl, and 4,4 ' -diaminodiphenyl ether is used, and still more preferably, 2 ' -bis (trifluoromethyl) benzidine is used.

The polyamideimide resin according to an embodiment of the present invention is: a condensation-type polymer which is a polycondensation product of a diamine compound, a tetracarboxylic acid compound (such as an acid chloride compound or a tetracarboxylic acid dianhydride), a dicarboxylic acid compound (such as an acid chloride compound or a dicarboxylic acid compound), and optionally a tricarboxylic acid compound (such as an acid chloride compound or a tricarboxylic acid anhydride). The structural units represented by the formulae (1) and (10-2) are generally derived from diamines and tetracarboxylic acid compounds. The structural unit represented by the formula (2) is usually derived from a diamine and a dicarboxylic acid compound. The structural unit represented by the formula (11-2) is usually derived from diamine and tricarboxylic acid compounds.

In a preferred embodiment of the present invention, the polyamideimide resin may contain a halogen atom as described above. Specific examples of the fluorine-containing substituent include a fluoro group and a trifluoromethyl group. When the polyamideimide resin contains a halogen atom, the yellowness (sometimes referred to as YI) of an optical member containing the polyamideimide resin may be reduced, and high flexibility and high bending resistance may be simultaneously achieved. In addition, the halogen atom is preferably a fluorine atom from the viewpoints of reduction in yellowness (i.e., improvement in transparency), reduction in water absorption, and bending resistance of the optical member.

The content of the halogen atom in the polyamideimide resin is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, and even more preferably 5 to 32% by mass, based on the mass of the polyamideimide resin, from the viewpoints of reduction in yellowness (improvement in transparency), reduction in water absorption, and suppression of deformation of an optical member.

In one embodiment of the present invention, an imidization catalyst may be present in the reaction for synthesizing the polyamideimide resin. Examples of the imidization catalyst include aliphatic amines such as tripropylamine, dibutylpropylamine, and ethyldibutylamine; n-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine, and N-propylhexahydroazepino

Iso-alicyclic amines (monocyclic)) (ii) a Azabicyclo [2.2.1]Heptane, azabicyclo [3.2.1]Octane, azabicyclo [2.2.2]Octane, and azabicyclo [3.2.2]Alicyclic amines (polycyclic) such as nonane; and aromatic amines such as pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 2, 4-dimethylpyridine, 2,4, 6-trimethylpyridine, 3, 4-cyclopentenopyridine, 5,6,7, 8-tetrahydroisoquinoline, and isoquinoline.

The reaction temperature of the diamine compound, the tetracarboxylic acid compound and the dicarboxylic acid compound is not particularly limited, and is, for example, 50 to 350 ℃. The reaction time is also not particularly limited, and is, for example, about 30 minutes to 10 hours. If necessary, the reaction may be carried out in an inert atmosphere or under reduced pressure. The reaction is preferably carried out in a solvent, and examples of the solvent include those described later and used for the preparation of a polyamide-imide varnish.

(optical Member)

In another embodiment of the present invention, an optical member is provided which is a polyamideimide film containing the polyamideimide resin. Examples of the optical member include an optical film. The optical member is excellent in flexibility, bending resistance and surface hardness, and therefore, is suitable as a front panel of an image display device, particularly a front panel (window film) of a flexible display. The optical member may be a single layer or a plurality of layers. When the optical member is a multilayer, the respective layers may have the same composition or different compositions.

In one embodiment of the present invention, the content of the polyamideimide resin in the optical member is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, particularly preferably 80% by mass or more, and very preferably 90% by mass or more, based on the total mass of the optical member. When the content of the polyamideimide resin is not less than the lower limit, the optical member has good bending resistance. The content of the polyamideimide resin in the optical member is usually 100% by mass or less based on the total mass of the optical member.

(inorganic Material)

The optical member may contain an inorganic material such as inorganic particles in addition to the polyamideimide resin. Examples of the inorganic material include inorganic particles such as titanium dioxide particles, alumina particles, zirconium dioxide particles, and silica particles, and silicon compounds such as tetraalkoxysilanes such as tetraethylorthosilicate. The inorganic material is preferably an inorganic particle, particularly a silica particle, from the viewpoint of stability of the polyamideimide varnish used for producing the optical member. The inorganic particles may be bonded to each other by molecules having siloxane bonds (i.e., -SiOSi-).

The average primary particle diameter of the inorganic particles is preferably 10 to 100nm, more preferably 20 to 80nm, from the viewpoints of transparency of the optical member, mechanical properties, and inhibition of aggregation of the inorganic particles. In the present invention, the average primary particle diameter can be determined by measuring the average value of 10 unidirectional particle diameters by a transmission electron microscope.

The content of the inorganic material in the optical member is preferably 0% by mass or more and 90% by mass or less, more preferably 0.01% by mass or more and 60% by mass or less, and further preferably 5% by mass or more and 40% by mass or less, based on the total mass of the optical member. When the content of the inorganic material is within the above range, the transparency and mechanical properties of the optical member tend to be easily achieved at the same time.

(ultraviolet absorber)

The optical member may contain 1 or 2 or more ultraviolet absorbers. The ultraviolet absorber can be appropriately selected from those generally used as ultraviolet absorbers in the field of resin materials. The ultraviolet absorber may contain a compound that absorbs light having a wavelength of 400nm or less. Examples of the ultraviolet absorber include at least 1 compound selected from the group consisting of benzophenone-based compounds, salicylate-based compounds, benzotriazole-based compounds, and triazine-based compounds. By incorporating an ultraviolet absorber into the optical member, deterioration of the polyamideimide resin can be suppressed, and thus, visibility of the optical member can be improved.

In the present specification, the term "related compound" refers to a derivative of a compound to which the "related compound" is attached. For example, the "benzophenone-based compound" refers to a compound having benzophenone as a matrix skeleton and a substituent bonded to benzophenone.

When the optical member contains the ultraviolet absorber, the content of the ultraviolet absorber is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 3% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 6% by mass or less, based on the total mass of the optical member. The preferable content varies depending on the ultraviolet absorber used, and when the content of the ultraviolet absorber is adjusted so that the light transmittance at 400nm becomes about 20 to 60%, the light resistance of the optical member can be improved and an optical member having high transparency can be obtained.

(other additives)

The optical member may further contain other additives. Examples of the other components include an antioxidant, a release agent, a stabilizer, a bluing agent, a flame retardant, a pH adjuster, a silica dispersant, a lubricant, a thickener, and a leveling agent.

The content of the other additive is preferably 0 mass% or more and 20 mass% or less, and more preferably 0 mass% or more and 10 mass% or less, with respect to the mass of the optical member.

The thickness of the optical member, particularly the optical film, can be suitably adjusted depending on the application, and is usually 10 to 1000. mu.m, preferably 15 to 500. mu.m, more preferably 20 to 400. mu.m, and still more preferably 25 to 300. mu.m. In the present invention, the thickness can be measured by a contact type digital dial gauge.

Among the optical members, the optical members were measured according to JIS K7105: the total light transmittance Tt in 1981 is preferably 70% or more, more preferably 80% or more, further preferably 85% or more, and particularly preferably 90% or more. When the total light transmittance Tt of the optical member is equal to or higher than the lower limit value, sufficient visibility can be ensured when the optical member is incorporated into an image display device. The upper limit of the total light transmittance Tt of the optical member is usually 100% or less.

(method of manufacturing optical Member)

The method for producing the above-mentioned optical member, particularly the optical film, is not particularly limited as long as the optical member contains the above-mentioned polyamideimide resin. In one embodiment of the present invention, an optical member, particularly an optical film, can be manufactured by a manufacturing method including, for example, the following steps:

(a) a step (coating step) of applying a liquid (polyamideimide varnish) containing a polyamideimide resin to a substrate to form a coating film, and

(b) and a step (forming step) of drying the applied liquid (polyamideimide varnish) to form an optical member, particularly an optical film (polyamideimide film).

The steps (a) and (b) may be generally performed sequentially.

In the coating step, first, a liquid containing a polyamideimide resin (polyamideimide varnish) is prepared. In order to produce the polyamideimide varnish, the diamine compound, the tetracarboxylic acid compound, the dicarboxylic acid compound, and, if necessary, other components such as a tertiary amine and a dehydrating agent which function as an imidization catalyst are mixed and reacted to produce a polyamideimide mixture. Examples of the tertiary amine include the aromatic amines and the aliphatic amines described above. Examples of the dehydrating agent include acetic anhydride, propionic anhydride, isobutyric anhydride, pivalic anhydride, butyric anhydride, and isovaleric anhydride. A poor solvent is added to the mixed polyamide-imide solution, a polyamide-imide resin is precipitated by reprecipitation, and the precipitate is taken out by drying.

The polyamide imide resin precipitate taken out is dissolved in a solvent, and the ultraviolet absorber and other additives are added as necessary and stirred to prepare a liquid containing a polyamide imide resin (polyamide imide varnish).

The solvent that can be used in the preparation of the polyamideimide varnish is not particularly limited as long as the polyamideimide resin can be dissolved. Examples of the solvent include amide solvents such as N, N-dimethylacetamide and N, N-dimethylformamide; lactone solvents such as γ -butyrolactone and γ -valerolactone; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide and sulfolane; carbonate-based solvents such as ethylene carbonate and 1, 2-propylene carbonate; and combinations thereof (mixed solvents). Among these solvents, an amide solvent or a lactone solvent is preferable. The polyamide-imide varnish may contain water, an alcohol solvent, a ketone solvent, an acyclic ester solvent, an ether solvent, and the like.

Next, a coating film can be formed on a substrate such as a resin substrate, SUS band, or glass substrate by casting or the like using a polyamideimide varnish by a known roll-to-roll or batch method.

In the forming step, the coating film is dried and peeled from the substrate, whereby an optical member can be formed. After the peeling, a drying step of drying the optical member may be further performed. The drying of the coating film can be carried out at a temperature of 50 to 350 ℃. If necessary, the coating film may be dried in an inert atmosphere or under reduced pressure.

A surface treatment process of performing a surface treatment on at least one surface of the optical member may be performed. Examples of the surface treatment include UV ozone treatment, plasma treatment, and corona discharge treatment.

Examples of the resin substrate include a PET film, a PEN film, a polyimide film, and a polyamideimide film. Among them, a PET film, a PEN film, a polyimide film, and other polyamide-imide films are preferable from the viewpoint of excellent heat resistance. Further, from the viewpoint of adhesion to an optical member and cost, a PET film is more preferable.

[ functional layer ]

An optical member according to an embodiment of the present invention may include a functional layer. Examples of the functional layer include layers having various functions such as an ultraviolet absorbing layer, an adhesive layer, a hue adjusting layer, and a refractive index adjusting layer. The optical member may be provided with one or more functional layers. In addition, one functional layer may serve multiple functions.

The ultraviolet absorbing layer is a layer having a function of absorbing ultraviolet rays, and is composed of a main material selected from an ultraviolet curing type transparent resin, an electron beam curing type transparent resin, and a thermosetting type transparent resin, and an ultraviolet absorber dispersed in the main material, for example. By providing the ultraviolet absorbing layer as the functional layer, the change in the yellowness due to light irradiation can be easily suppressed.

The adhesive layer is a layer having an adhesive function, and has a function of bonding the optical member to another member. As a material for forming the adhesive layer, a generally known material can be used. For example, a thermosetting resin composition or a photocurable resin composition can be used.

The adhesive layer may be composed of a resin composition containing a component having a polymerizable functional group. In this case, after the optical member is bonded to another member, the resin composition constituting the adhesive layer is further polymerized, whereby strong adhesion can be achieved. The adhesive strength between the optical member and the adhesive layer may be 0.1N/cm or more, or 0.5N/cm or more.

The adhesive layer may contain a thermosetting resin composition or a photocurable resin composition as a material. In this case, the resin composition can be polymerized and cured by supplying energy afterwards.

The Adhesive layer may be a layer made of an Adhesive that is pressed to be attached to an object, which is called a Pressure Sensitive Adhesive (PSA). The pressure-sensitive adhesive may be a capsule adhesive as "an adhesive having adhesiveness at normal temperature and adhering to an adherend by light pressure" (JIS K6800) or as "an adhesive which contains a specific component in a protective film (microcapsule) and can maintain stability until the film is broken by an appropriate means (pressure, heat, etc.)" (JIS K6800).

The hue adjustment layer is a layer having a hue adjustment function and is a layer capable of adjusting the optical member to a target hue. The hue adjustment layer is, for example, a layer containing a resin and a colorant. Examples of the colorant include inorganic pigments such as titanium oxide, zinc oxide, red iron oxide, titanium oxide-based calcined pigments, ultramarine blue, cobalt aluminate, and carbon black; organic pigments such as azo-based compounds, quinacridone-based compounds, anthraquinone-based compounds, perylene-based compounds, isoindolinone-based compounds, phthalocyanine-based compounds, quinophthalone-based compounds, threne-based compounds, and diketopyrrolopyrrole-based compounds; bulk pigments such as barium sulfate and calcium carbonate; and basic dyes, acid dyes, mordant dyes, and the like.

The refractive index adjusting layer is a layer having a refractive index adjusting function, and has a refractive index different from that of the optical member, and can provide a predetermined refractive index to the optical member. The refractive index adjusting layer may be, for example, a resin layer containing an appropriately selected resin and, in some cases, a pigment, or may be a metal thin 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 transmitted through the refractive index adjustment layer can be prevented, and deterioration in transparency can be prevented.

Examples of the metal usable for the refractive index adjustment layer include metal oxides and metal nitrides 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.

In addition, the optical member may be provided with a hard coating layer. Examples of the hard coat layer include known hard coat layers such as acrylic, epoxy, urethane, benzyl chloride, and vinyl. In a preferred embodiment of the present invention, the optical member can exhibit a high surface hardness even without a hard coat layer. Therefore, a hard coat laminate comprising an optical member formed of the polyamideimide resin can exhibit a higher surface hardness than a hard coat laminate comprising an optical member which cannot exhibit a high surface hardness alone.

The optical member can exhibit high surface hardness. In a preferred embodiment of the present invention, the surface hardness of the optical member is preferably 2B or more, more preferably B or more, further preferably HB or more, particularly preferably H or more, and very preferably 2H or more. When the surface hardness of the optical member is not less than the lower limit, it is possible to favorably suppress damage to the surface of the image display device when used as a front panel (window film) of the image display device, and it is possible to contribute to prevention of shrinkage and expansion of the optical member. The surface hardness of the optical member is usually 9H or less. In the present invention, the surface hardness may be measured in accordance with JIS K5600-5-4: 1999, the presence or absence of a flaw was evaluated under an environment of 4000 lux with a load of 100g and a scanning speed of 60mm/min, for example. The image display device can be formed not only in a flat shape but in various shapes due to the flexibility of the flexible display, and the image display device is more flexible, so that the chance that the user directly touches the screen or the surrounding objects directly touch the screen increases. Therefore, the optical member as one embodiment of the present invention is very useful as a front panel of a flexible display.

The optical member can exhibit high flexibility. In a preferred embodiment of the present invention, the elastic modulus of the optical member is preferably 5.9GPa or less, more preferably 5.5GPa or less, still more preferably 5.2GPa or less, particularly preferably 5.0GPa or less, and very preferably 4.5GPa or less. When the elastic modulus of the optical member is equal to or less than the upper limit value, damage to other members due to the optical member can be suppressed when the flexible display is bent. The elastic modulus of the optical member is usually 2.0GPa or more. For example, the elastic modulus can be measured from the slope of an S-S curve measured with respect to a 10mm wide test piece by using an automatic plotter (AUTOGRAPH) AG-IS (manufactured by Shimadzu corporation) under conditions of an inter-chuck distance of 500mm and a stretching speed of 20 mm/min.

The optical member, particularly the optical film, can exhibit excellent bending resistance. In a preferred embodiment of the present invention, the number of times of reciprocal bending until breakage of the optical member, measured under conditions of R ═ 1mm, 135 °, load of 0.75kgf, and speed of 175cpm, is preferably 10,000 or more, more preferably 20,000 or more, further preferably 30,000 or more, particularly preferably 40,000 or more, and very preferably 50,000 or more. When the number of times of reciprocal bending of the optical member is equal to or greater than the lower limit value, wrinkles generated when the optical member is bent can be further suppressed. The number of times of reciprocal bending of the optical member is not limited, and it is generally practical if 1,000,000 times of bending can be performed. The number of reciprocating bending times can be determined, for example, by using an MIT bending fatigue tester (model 0530) manufactured by Toyo Seiki Seisaku-Sho Ltd, and using a test piece (optical member) having a thickness of 50 μm and a width of 10 mm.

The optical member can exhibit excellent transparency. Therefore, the above optical member is very useful as a front panel (window film) of an image display device, particularly a flexible display. In a preferred embodiment of the present invention, the optical member has a thickness in accordance with JIS K7373: the yellow color YI of 2006 is preferably 5 or less, more preferably 3 or less, and further preferably 2.5 or less. The optical member having the yellowness YI of the upper limit or less contributes to high visibility of a display device or the like. The optical member preferably has a yellowness index of 0 or more.

An optical member, particularly an optical film, which is one embodiment of the present invention is useful as a front panel of an image display device, particularly a front panel (window film) of a flexible display. The optical member may be disposed as a front panel on a viewing side surface of an image display device, particularly a flexible display. The front panel has a function of protecting the image display elements within the flexible display. The image display device provided with the optical member has high flexibility, high bending resistance and high surface hardness, so that other members are not damaged during bending, and the optical member itself is not easily wrinkled, and damage to the surface can be favorably suppressed.

Examples of the image display device include wearable devices such as a television, a smartphone, a mobile phone, a car navigation system, a tablet PC, a portable game machine, electronic paper, a pointer, a signboard, a clock, and a smart watch. Examples of the flexible display include an image display device having a flexible property, such as a television, a smartphone, a mobile phone, a car navigation device, a tablet PC, a portable game device, electronic paper, a pointer, a signboard, a clock, and a wearable device.

Examples

The present invention will be described in further detail below with reference to examples. In the examples, "%" and "part(s)" refer to% by mass and part(s) by mass unless otherwise specified. First, the evaluation method will be explained.

< determination of elastic modulus >

The elastic modulus of the polyamideimide film obtained in the examples was measured by using an automatic plotter AG-IS manufactured by Shimadzu corporation. A10 mm wide film was prepared, and the S-S curve was measured under the conditions that the distance between chucks was 500mm and the stretching speed was 20mm/min, and the elastic modulus was calculated from the slope thereof.

< determination of surface hardness >

As the surface hardness of the polyamideimide film obtained in the examples, the surface hardness was measured in accordance with JIS K5600-5-4: 1999, the pencil hardness of the film surface was measured. The presence or absence of a flaw was evaluated under an environment of 4000 lux with a load of 100g and a scanning speed of 60 mm/min.

< measurement of bending resistance >

The bending resistance of the polyamideimide films obtained in the examples was measured using an MIT bending fatigue tester (model 0530) manufactured by tokyo seiki inc. A film having a thickness of 50 μm and a width of 10mm was produced, and when the film was measured under conditions of R1 mm, 135 degrees, a load of 0.75kgf, and a speed of 175cpm, the number of reciprocal bending until breakage was evaluated.

< determination of weight average molecular weight (Mw) >)

Gel Permeation Chromatography (GPC) measurement

(1) Pretreatment method

To the sample was added a DMF eluent (10mM lithium bromide solution) so that the concentration became 2mg/mL, and the mixture was heated at 80 ℃ for 30 minutes with stirring, cooled, and then filtered through a 0.45 μm membrane filter to obtain a solution as a measurement solution.

(2) Measurement conditions

Column: TSKgel SuperAWM-H.times.2 + SuperAW 2500X 1(6.0mm I.D.. times.150 mm. times.3 pieces) (all manufactured by Tosoh Corporation)

Eluent: DMF (with addition of 10mM lithium bromide)

Flow rate: 1.0mL/min.

A detector: RI detector

Column temperature: 40 deg.C

Sample introduction amount: 100 μ L

Molecular weight standard: standard polystyrene

< measurement of Total light transmittance (Tt) >

According to JIS K7105: 1981, the total light transmittance Tt of the polyamideimide film obtained in the examples was measured by using a fully automatic direct reading haze computer HGM-2DP manufactured by Suga Test Instruments Co., Ltd.

< determination of the Yellowness (YI) >

According to JIS K7373: the yellowness of the polyamideimide films obtained in the examples was measured (yellowness Index (YI): YI) by using an ultraviolet-visible near-infrared spectrophotometer V-670 manufactured by Nippon spectral Co., Ltd.). The background was measured in a film-free state, and then the film was placed on a sample holder, and the transmittance with respect to light of 300 to 800nm was measured to obtain the tristimulus value (X, Y, Z). YI is calculated based on the following formula.

YI＝100×(1.2769X-1.0592Z)/Y

< determination of glass transition temperature (Tg) >

The polyamide-imide films obtained in examples were prepared into samples as described below using DMA Q800 manufactured by TA Instrument, and measured under the following conditions to obtain tan δ curves, which are ratios of values of loss modulus and storage modulus. Tg was calculated from the uppermost point of the peak of the tan δ curve.

-a sample: the length is 5-15mm, and the width is 5mm

Experimental mode: DMA Multi-Frequency Strain (Multi-Frequency-Strain)

Experimental mode details conditions:

(1) a clamp: stretching: film (Clamp: Tension: Film)

(2) Amplitude (Amplitude): 5 μm

(3) Frequency (Frequncy): 10Hz (no variation in all temperature ranges)

(4) Pretension (Preload Force): 0.01N

(5) Force Track (Force Track): 125N

-temperature conditions: (1) temperature rise range: normal temperature to 400 ℃, and (2) heating rate: 5 ℃ per minute

-the main collected data: (1) storage modulus (E '), (2) Loss modulus (Loss modulus, E "), (3) tan delta (E"/E')

Example 1

[ preparation of polyamideimide resin (1) ]

52g (162.38mmol) of 2, 2' -bis (trifluoromethyl) benzidine (TFMB) and 734.10g of N, N-dimethylacetamide (DMAc) were added to a 1L separable flask equipped with a stirring blade under a nitrogen atmosphere, and TFMB was dissolved in DMAc with stirring at room temperature. Subsequently, 28.90g (65.05mmol) of 4, 4' - (hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was added to the flask, and stirring was performed at room temperature for 3 hours. Then, 28.80g (97.57mmol) of 4, 4' -oxybis (benzoyl chloride) (OBBC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Then, 7.49g (94.65mmol) of pyridine and 26.56g (260.20mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, then heated to 70 ℃ using an oil bath, and further stirred for 3 hours to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, put into a large amount of methanol in a linear form, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Then, the precipitate was dried under reduced pressure at 100 ℃ to obtain a polyamideimide resin (1).

[ production of Polyamide-imide film (1) ]

DMAc was added to the obtained polyamideimide resin (1) so that the concentration thereof became 15% by mass, thereby preparing a polyamideimide varnish (1). The obtained polyamideimide varnish (1) was applied to a smooth surface of a polyester substrate (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the thickness of the self-supporting film became 55 μm, and dried at 50 ℃ for 30 minutes and then at 140 ℃ for 15 minutes to obtain a self-supporting film. The self-supporting film was fixed to a metal frame, and further dried at 300 ℃ for 30 minutes under a nitrogen atmosphere, to obtain a polyamideimide film (1) having a film thickness of 50 μm. When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (1) were measured according to the above measurement methods, the Mw was 120,000, the Tt was 91%, the YI was 2.2 and the Tg was 345 ℃. The molar ratios of the respective components are shown in table 1.

Example 2

[ preparation of polyamideimide resin (2) ]

A polyamideimide resin (2) was obtained in the same manner as in [ preparation of polyamideimide resin (1) ] of example 1 except that the amount of DMAc used was changed to 701.64g, the amount of 6FDA used was changed to 14.45g (32.52mmol), the amount of OBBC used was changed to 38.39g (130.10mmol), the amount of pyridine used was changed to 9.98g (126.20mmol), and the amount of acetic anhydride used was changed to 13.28g (130.10 mmol). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (2) ]

A polyamideimide film (2) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that the polyamideimide resin (2) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (2) were measured according to the above measurement methods, the Mw was 150,000, the Tt was 91%, the YI was 2.5 and the Tg was 345 ℃.

Example 3

[ preparation of polyamideimide resin (3) ]

In a 1L separable flask equipped with a stirring blade, TFMB52g (162.38mmol) and DMAc697.82g were added under a nitrogen atmosphere, and TFMB was dissolved in DMAc with stirring at room temperature. Subsequently, 6FDA21.67g (48.79mmol) was added to the flask, and the mixture was stirred at room temperature for 3 hours. Then, 24.00g (81.31mmol) of OBBCC and 6.60g (32.52mmol) of terephthaloyl chloride (TPC) were added to the flask, and the mixture was stirred at room temperature for 1 hour. Subsequently, 8.73g (110.42mmol) of pyridine and 19.92g (195.15mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, then heated to 70 ℃ using an oil bath, and further stirred for 3 hours to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, put into a large amount of methanol in a linear form, and the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Then, the precipitate was dried under reduced pressure at 100 ℃ to obtain a polyamideimide resin (3). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (3) ]

A polyamideimide film (3) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that the polyamideimide resin (3) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (3) were measured according to the above measurement methods, the Mw was 100,000, the Tt was 91%, the YI was 2.3 and the Tg was 340 ℃.

Example 4

[ preparation of polyamideimide resin (4) ]

A polyamideimide resin (4) was obtained in the same manner as in [ preparation of polyamideimide resin (3) ] of example 3 except that the amount of DMAc used was changed to 667.75g, the amount of 6FDA used was changed to 21.67g (162.38mmol), the amount of OBBC used was changed to 9.60g (48.79mmol), the amount of TPC used was changed to 16.51g (81.31mmol), the amount of pyridine used was changed to 8.73g (110.42mmol), and the amount of acetic anhydride used was changed to 19.92g (195.15 mmol). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (4) ]

A polyamideimide film (4) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that a polyamideimide resin (4) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (4) were measured according to the above measurement methods, the Mw was 230,000, the Tt was 91%, the YI was 2.3 and the Tg was 369 ℃.

Example 5

[ preparation of polyamideimide resin (5) ]

A polyamideimide resin (5) was obtained in the same manner as in [ preparation of polyamideimide resin (3) ] of example 3 except that the amount of DMAc used was changed to 884.53g, the amount of 6FDA used was changed to 21.67g (38.79mmol), the amount of OBBC used was changed to 4.80g (16.26mmol), the amount of TPC used was changed to 19.81g (97.57mmol), the amount of pyridine used was changed to 8.73g (110.42mmol), and the amount of acetic anhydride used was changed to 19.92g (195.15 mmol). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (5) ]

A polyamideimide film (5) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that a polyamideimide resin (5) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), total light transmittance Tt, yellowness YI and glass transition temperature Tg of the polyamideimide film (5) were measured according to the above measurement methods, Mw was 345,000, Tt was 91%, YI was 2.2 and Tg was 377 ℃.

Example 6

[ preparation of polyamideimide resin (6) ]

A polyamideimide resin (6) was obtained in the same manner as in [ preparation of polyamideimide resin (3) ] of example 3 except that the amount of DMAc used was changed to 849.23g, the amount of 6FDA used was changed to 14.45g (32.52mmol), the amount of OBBC used was changed to 4.80g (16.26mmol), the amount of TPC used was changed to 23.11g (113.84mmol), the amount of pyridine used was changed to 9.98g (126.20mmol), and the amount of acetic anhydride used was changed to 13.28g (130.10 mmol). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (6) ]

A polyamideimide film (6) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that a polyamideimide resin (6) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (6) were measured according to the above measurement methods, the Mw was 341,000, the Tt was 91%, the YI was 2.4 and the Tg was 378 ℃.

Comparative example 1

[ preparation of polyamideimide resin (7) ]

A polyamideimide resin (7) was obtained in the same manner as in [ preparation of polyamideimide resin (3) ] of example 3 except that the amount of DMAc used was changed to 647.70g, the amount of 6FDA used was changed to 21.67g (48.79mmol), the amount of TPC used was changed to 23.11g (113.84mmol), the amount of pyridine used was changed to 8.73g (110.42mmol), the amount of acetic anhydride used was changed to 19.92g (195.15mmol), and OBBC was not added. The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (7) ]

A polyamideimide film (7) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that a polyamideimide resin (7) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), total light transmittance Tt, yellowness YI and glass transition temperature Tg of the polyamideimide film (7) were measured according to the above measurement methods, Mw was 80,000, Tt was 90%, YI was 2.4 and Tg was 380 ℃.

Comparative example 2

[ preparation of polyimide resin (8) ]

A polyimide resin (8) was obtained in the same manner as in [ preparation of polyamideimide resin (1) ] of example 1 except that the amount of DMAc used was changed to 831.46g, the amount of 6FDA used was changed to 72.24g (162.62mmol), the amount of pyridine used was changed to 18.72g (236.62mmol), the amount of acetic anhydride used was changed to 66.41g (650.49mmol), and OBBC was not added. The molar ratios of the respective components are shown in table 1.

[ production of polyimide film (8) ]

A polyimide film (8) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that a polyimide resin (8) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), total light transmittance Tt, yellowness YI and glass transition temperature Tg of the polyimide film (8) were measured according to the above measurement methods, Mw was 268,000, Tt was 92%, YI was 2.0 and Tg was 361 ℃.

Comparative example 3

[ preparation of polyimide resin (9) ]

A polyimide resin (9) was obtained in the same manner as in [ preparation of polyamideimide resin (1) ] of example 1 except that the amount of DMAc used was changed to 732.20g, the amount of 6FDA used was changed to 28.9g (65.05mmol), the amount of pyridine used was changed to 18.72g (236.62mmol), the amount of acetic anhydride used was changed to 66.41g (650.49mmol), and 28.51g (97.57mmol) of 4, 4' -biphenyltetracarboxylic dianhydride (BPDA) was added together with 6FDA without adding OBBC. The molar ratios of the respective components are shown in table 1.

[ production of polyimide film (9) ]

A polyimide film (9) having a film thickness of 50 μm was obtained in the same manner as in [ production of a polyamideimide film (1) ] of example 1 except that a polyimide resin (9) was used in place of the polyamideimide resin (1). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyimide film (9) were measured according to the above measurement methods, the Mw was 276,000, the Tt was 85%, the YI was 5.8 and the Tg was 365 ℃.

Example 7

[ preparation of polyamideimide resin (10) ]

In a 1L separable flask equipped with a stirring blade, TFMB45.00g (140.5mmol) and DMAc600.9g were added under a nitrogen atmosphere, and TFMB was dissolved in DMAc with stirring at room temperature. Next, BPDA4.14g (14.1mmol) was added to the flask, and stirring was performed at room temperature for 2.5 hours, followed by addition of 6FDA25.01g (56.3mmol) and stirring at room temperature for 15 hours. Further, OBBC4.15g (14.1mmol) and TPC11.43g (56.3mmol) were added to the flask, and the mixture was stirred at room temperature for 1 hour. Then, 21.55g (211.1mmol) of acetic anhydride and 3.28g (35.2mmol) of 4-methylpyridine were added to the flask, and the mixture was stirred at room temperature for 30 minutes, then heated to 70 ℃ using an oil bath, and further stirred for 3 hours to obtain a reaction solution.

The resulting reaction solution was cooled to room temperature, and then 647g of methanol and 180g of ion-exchanged water were added to the reaction solution, thereby obtaining a polyamide imide precipitate. This was immersed in methanol for 12 hours, recovered by filtration, and washed with methanol. Then, the precipitate was dried under reduced pressure at 100 ℃ to obtain a polyamideimide resin (10). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (10) ]

A polyamideimide film (10) having a film thickness of 50 μm was obtained in the same manner as [ production of a polyamideimide film (1) ] of example 1 except that the polyamideimide resin (10) was used in place of the polyamideimide resin (1) and the polyamide imide resin was dried at 300 ℃ for 30 minutes in a nitrogen atmosphere and then dried at 200 ℃ for 30 minutes in the atmosphere. When the weight average molecular weight (Mw), total light transmittance Tt, yellowness YI and glass transition temperature Tg of the polyamideimide film (10) were measured according to the above measurement methods, Mw was 208,000, Tt was 91.8%, YI was 1.8 and Tg was 373 ℃.

Example 8

[ preparation of polyamideimide resin (11) ]

In a 1L separable flask equipped with a stirring blade, TFMB14.67g (45.8mmol) and DMAc233.3g were added under a nitrogen atmosphere, and TFMB was dissolved in DMAc with stirring at room temperature. Next, 4.283g (13.8mmol) of 4, 4' -oxydiphthalic dianhydride (OPDA) was added to the flask, and the mixture was stirred at room temperature for 16.5 hours. Then, OBBC1.359g (4.61mmol) and TPC5.609g (27.6mmol) were added to the flask, and stirring was performed at room temperature for 1 hour. Next, 4.937g (48.35mmol) of acetic anhydride and 1.501g (16.12mmol) of 4-methylpyridine were added to the flask, and stirring was performed at room temperature for 30 minutes, and then, the temperature was raised to 70 ℃ using an oil bath, and further stirring was performed for 3 hours to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, and then 360g of methanol and 170g of ion-exchanged water were added to the reaction solution, thereby obtaining a polyamide-imide precipitate. This was immersed in methanol for 12 hours, recovered by filtration, and washed with methanol. Then, the precipitate was dried under reduced pressure at 100 ℃ to obtain a polyamideimide resin (11). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (11) ]

A polyamideimide film (11) having a film thickness of 50 μm was obtained in the same manner as [ production of a polyamideimide film (10) ] of example 7, except that a polyamideimide resin (11) was used in place of the polyamideimide resin (10). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (11) were measured according to the above measurement methods, the Mw was 259,000, the Tt was 91.0%, the YI was 1.9 and the Tg was 362 ℃.

Example 9

[ preparation of polyamideimide resin (12) ]

A polyamideimide resin (12) was obtained in the same manner as in [ preparation of polyamideimide resin (11) ] of example 8 except that 6FDA6.140g was used in place of 4.283g of 4,4 '-oxydiphthalic dianhydride (OPDA), and TFMB8.809g (27.5mmol) and 2, 2' -dimethylbenzidine (MB)3.889g (18.3mmol) were used in place of TFMB14.67g (45.8 mmol). The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (12) ]

A polyamideimide film (12) having a film thickness of 50 μm was obtained in the same manner as [ production of a polyamideimide film (11) ] of example 8 except that a polyamideimide resin (12) was used in place of the polyamideimide resin (11). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (12) were measured according to the above measurement methods, the Mw was 189,000, the Tt was 91.1% and the Tg was 393 ℃.

Example 10

[ preparation of polyamideimide resin (13) ]

A polyamideimide resin (13) was obtained in the same manner as in [ preparation of polyamideimide resin (12) ] of example 9 except that 3.670g (18.3mmol) of 4, 4' -diaminodiphenyl ether (ODA) was used in place of MB3.889g. The molar ratios of the respective components are shown in table 1.

[ production of Polyamide-imide film (13) ]

A polyamideimide film (13) having a film thickness of 50 μm was obtained in the same manner as [ production of a polyamideimide film (12) ] of example 9 except that a polyamideimide resin (13) was used in place of the polyamideimide resin (12). When the weight average molecular weight (Mw), the total light transmittance Tt, the yellowness YI and the glass transition temperature Tg of the polyamideimide film (13) were measured according to the above measurement methods, the Mw was 166,000, the Tt was 91.3% and the Tg was 350 ℃.

The molar ratios of the components in the above examples and comparative examples are shown in table 1 below.

[ Table 1]

The obtained polyamide films (1) to (9) were measured for elastic modulus, surface hardness, and bending resistance according to the above-described measurement methods. The results are shown in Table 2.

[ Table 2]

As is clear from the above, a polyamideimide film (optical member) formed from the polyamideimide resin according to the present invention has a low elastic modulus, is excellent in flexibility, and has high bending resistance. It also exhibits high surface hardness and is also capable of suppressing surface damage.

Claims

1. A polyamideimide resin having structural units represented by the formulae (1) and (2),

[ chemical formula 1]

In the formulae (1) and (2), X and Z each independently represent a 2-valent organic group,

y represents an organic group having a valence of 4,

at least a part of Z is a structural unit represented by formula (3),

[ chemical formula 2]

In the formula (3), R¹～R⁸Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹～R⁸Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

a represents-O-or-S-,

m is an integer of 1 to 4,

the symbol represents a chemical bond,

wherein the content of the structural unit represented by formula (3) is 3 mol% or more and 90 mol% or less with respect to the total of Y and Z.

2. The polyamideimide resin according to claim 1, wherein 5 mol% or more and 100 mol% or less of Z is represented by formula (3).

3. The polyamideimide resin according to claim 1, wherein a ratio of the structural unit represented by formula (3) is 3 mol% or more and 90 mol% or less with respect to a total of the structural unit represented by formula (1) and the structural unit represented by formula (2).

4. The polyamideimide resin according to any one of claims 1 to 3, wherein the content of the structural unit represented by formula (1) is 10 mol% or more and 90 mol% or less with respect to the total of the structural unit represented by formula (1) and the structural unit represented by formula (2).

5. The polyamideimide resin according to claim 1 or 2, wherein at least a part of X is a structural unit represented by formula (4),

[ chemical formula 3]

In the formula (4), R¹⁰～R¹⁷Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁰～R¹⁷Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

denotes a bond.

6. The polyamideimide resin according to claim 1 or 2, wherein at least a part of Y is a structural unit represented by formula (5),

[ chemical formula 4]

In the formula (5), R¹⁸～R²⁵Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, R¹⁸～R²⁵Each hydrogen atom contained in (a) may independently be substituted with a halogen atom,

denotes a bond.

7. The polyamideimide resin according to claim 1 or 2, wherein the glass transition temperature Tg, calculated from tan δ in DMA measurement, is lower than 380 ℃.

8. An optical member comprising the polyamideimide resin according to any one of claims 1 to 7.

9. An image display device comprising the optical member according to claim 8.