Patent Description:
Research efforts have been undertaken to produce a colorless transparent material that is suitable for diverse purposes such as for an optical lens, a functional optical film, and a disk substrate. However, as information devices are being further miniaturized and display devices are providing higher resolution, more functions and greater performance are required from the material.

Therefore, research efforts are currently underway to develop a colorless transparent material having improved transparency, heat resistance, mechanical strength, and flexibility.

<CIT> discloses an adhesive composition including a solvent and a polyamic acid.

<CIT> discloses linear polymers containing amide linkages prepared by the reaction of diaminodiamido aryl organic compounds with difunctional acid halides.

<CIT> discloses a poly(amide-imide) block copolymer, an article including the same, and a display device including the article.

The invention provides a novel monomer that is applicable to a compensation film.

Another embodiment provides a polymer obtained by polymerizing the novel monomer.

Yet another embodiment provides a compensation film including the polymer.

Still another embodiment provides an optical film including the compensation film.

Further embodiment provides a display device including the compensation film or the optical film.

An aspect of the invention provides a monomer in accordance with claim <NUM>.

The monomer of the invention is represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>,.

The dianhydride represented by Chemical Formula <NUM>-<NUM> may include dianhydride represented by Chemical Formula <NUM>-<NUM>, dianhydride represented by Chemical Formula <NUM>-<NUM>, or a combination thereof and the dianhydride represented by Chemical Formula <NUM>-<NUM> may include dianhydride represented by Chemical Formula <NUM>-<NUM>, dianhydride represented by Chemical Formula <NUM>-<NUM>, or a combination thereof:
<CHM>
<CHM>
wherein, in Chemical Formula <NUM>-<NUM> and Chemical Formula <NUM>-<NUM>,.

The polymer may be a product of reactants further including a dicarboxylic acid derivative represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>,.

The polymer may be a product of reactants further including diamine represented by Chemical Formula <NUM>:.

[Chemical Formula <NUM>]     NH<NUM>-Rc-NH<NUM>.

wherein, in Chemical Formula <NUM>,
Rc includes a substituted or unsubstituted C6 to C30 aromatic organic group, wherein the substituted or unsubstituted C6 to C30 aromatic organic group is present as a substituted or unsubstituted single aromatic ring; a fused ring including two or more substituted or unsubstituted aromatic rings; or a ring system including two or more of the substituted or unsubstituted single aromatic ring and/or the fused ring that are linked by a single bond, or a functional group selected from a fluorenylene group, a substituted or unsubstituted C1 to C10 cycloalkylene group, a substituted or unsubstituted C6 to C15 arylene group, - O-, -S-, -C(=O)-, -CH(OH)-, -S(=O)<NUM>-, -Si(CH<NUM>)<NUM>-, -(CH<NUM>)p- (wherein, <NUM>≤p≤<NUM>), - (CF<NUM>)q- (wherein, <NUM>≤q≤<NUM>), -C(CH<NUM>)<NUM>-, -C(CF<NUM>)<NUM>-, -C(=O)NH-, or a combination thereof.

The diamine represented by Chemical Formula <NUM> may be represented by at least one of Chemical Formula <NUM> to Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>,.

The diamine represented by Chemical Formula <NUM> may include at least one of the diamine represented by Chemical Formula <NUM> and the diamine represented by Chemical Formula <NUM>, the diamine represented by Chemical Formula <NUM> may include <NUM>,<NUM>'-bis(trifluoromethyl)benzidine (TFDB), and the diamine represented by Chemical Formula <NUM> may include <NUM>,<NUM>'-diaminodiphenyl sulfone (DADPS).

The diamine represented by Chemical Formula <NUM> may be included in an amount of less than or equal to <NUM> mol% based on a total amount of the monomer represented by Chemical Formula <NUM> and the diamine represented by Chemical Formula <NUM>.

Another embodiment provides a compensation film including the polymer according to the embodiment.

Another embodiment provides an optical film including the compensation film according to the embodiment and a polarizer.

Another embodiment provides a display device including the compensation film according to the embodiment.

Another embodiment provides a display device including the optical film according to the embodiment.

Hereinafter, the embodiments are described in detail.

A novel monomer according to an embodiment reacts with dianhydride and thus may be used to form a polyimide film having high transmittance, a low yellow index, and low haze, as well as a high out-of-plane birefringence. The novel monomer is prepared from inexpensive raw materials, and accordingly, may be used to manufacture an optical film requiring excellent optical characteristics and mechanical properties.

Hereinafter, exemplary embodiments will be described in detail, and may be readily performed by those who have common knowledge in the related art. However, this disclosure may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein.

The term "or" means "and/or. " Expressions such as "at least one of" when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the present embodiments.

The term "or" means "and/or.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this general inventive concept belongs.

For example, a region illustrated or described as flat may, typically, have rough and/or non-linear features.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present.

As used herein, when a definition is not otherwise provided, the term "substituted" refers to replacement of a hydrogen atom of a compound or a functional group by a substituent selected from a halogen atom, a hydroxy group, an alkoxy group, a nitro group, a cyano group, an amino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C6 to C30 aryl group, a C7 to C30 arylalkyl group, a C1 to C30 alkoxy group, a C1 to C20 heteroalkyl group, a C3 to C20 heteroarylalkyl group, a C3 to C30 cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C15 cycloalkynyl group, a C3 to C30 heterocycloalkyl group, and a combination thereof.

As used herein, when a definition is not otherwise provided, the term "hetero" refers to inclusion of <NUM> to <NUM> hetero atoms selected from N, O, S, Se, and P.

As used herein, when a definition is not otherwise provided, the term "alkyl" indicates a group derived from a completely saturated, branched or unbranched (or a straight or linear) hydrocarbon and having a specified number of carbon atoms.

As used herein, the term "cycloalkyl group" refers to a monovalent group having one or more saturated rings in which all ring members are carbon. Non-limiting examples of the cycloalkyl group are cyclopentyl and cyclohexyl.

As used herein, when a definition is not otherwise provided, the term "alkoxy" represents "alkyl-O-", wherein the term "alkyl" has the same meaning as described above.

As used herein, when a definition is not otherwise provided, the term "cycloalkoxy" represents "cycloalkyl-O-", wherein the term "cycloalkyl" has the same meaning as described above.

As used herein, when a definition is not otherwise provided, the term "aryl" indicates an aromatic hydrocarbon containing at least one ring and having the specified number of carbon atoms.

As used herein, when a definition is not otherwise provided, the term "arylalkyl" represents "aryl-alkyl-", wherein the terms "aryl" and "alkyl" have the same meaning as described above.

As used herein, the term "alkylene" indicates a group having one or more saturated rings in which all ring members are carbon having a valence of at least two, optionally substituted with one or more substituents where indicated, provided that the valence of the cycloalkylene group is not exceeded.

As used herein, the term "cycloalkylene" indicates a straight or branched saturated aliphatic hydrocarbon group having a valence of at least two, optionally substituted with one or more substituents where indicated, provided that the valence of the alkylene group is not exceeded.

As used herein, when a definition is not otherwise provided, the term "arylene" indicates a divalent group formed by the removal of two hydrogen atoms from one or more rings of an arene, wherein the hydrogen atoms may be removed from the same or different rings of the arene.

An optically transparent heat resistant polymer described herein may be applied to various optoelectronic devices, for example, an image device, a liquid crystal alignment layer, a color filter, an optical compensation film, an optic fiber, a light guide, optical lens.

In this regard, research efforts have been recently made to realize a remarkably light and flexible display panel by replacing a fragile inorganic glass substrate (e.g., about <NUM> to about <NUM> thick) in an image device with a plastic substrate (< about <NUM> thick) has drawn attention.

However, the plastic substrate has not secured reliability yet, because it is difficult to simultaneously achieve optical transmittance, heat resistance, dimensional stability (thermal dimensional stability) at a thermal cycle during the assembly process of a device, film flexibility, and film-forming process compatibility (a solution process) in a high level. The plastic substrate is excellent in terms of flexibility and thin film formality but inferior in terms of heat resistance and thermal dimensional stability compared with the inorganic glass substrate.

Poly(ether sulfone) (PES) is known to have the highest glass transition temperature (Tg, <NUM>) among commercially available super engineering plastics. However, PES may be unsuitable for the plastic substrate in terms of heat resistance and thermal dimensional stability. A plastic substrate having insufficient thermal dimensional stability may be thermally expanded/contracted during repetitive heating/cooling cycles in a process of forming an ITO (indium tin oxide) electrode and a thin film transistor and thus may cause a serious problem of destroying an ITO layer.

A high temperature resistant polymer material having the highest reliability may be polyimide (PI). A part of aromatic PI systems simultaneously has much higher Tg than a device operating temperature and a low linear coefficient of thermal expansion (CTE) along a film plane (X-Y) direction in a glassy region and thus excellent thermal dimensional stability. However, common aromatic PI is strongly colored due to a charge transfer (CT) interaction and often disturbs an optical device. Accordingly, academic and industrial research efforts on a coloring/discoloring mechanism of an aromatic PI film have been widely conducted. One of the effective approaches for discoloring the film is to block the CT interaction by selecting a nonaromatic (alicyclic) monomer from diamine, tetracarboxylic dianhydride, or both of them. However, the alicyclic monomer may cause a serious problem in some uses. In other words, a partly or wholly alicyclic PI film often has insufficient thermal dimensional stability due to a high linear coefficient of thermal expansion CTE (><NUM> ppm K-<NUM>) in the glassy region despite a high glass transition temperature Tg (><NUM>). This high linear coefficient of thermal expansion is actually generated from a randomly three dimensionally disposed chain alignment. The alicyclic monomer mostly has a nonlinear/nonplanar cubic structure. As a result, linearity of a PI main chain is completely destroyed. In this twisted backbone structure, chains may not be highly aligned along an X-Y direction (hereinafter, "planar alignment") during a thermal imidization process. Among the alicyclic monomers, <NUM>,<NUM>,<NUM>,<NUM>-cyclobutane tetracarboxylic dianhydride (CBDA) and trans-<NUM>,<NUM>-cyclohexane diamine (t-CHDA) uncommonly has a rigid and linear structure. However, a final PI using this monomer may not be applied to a solution process. However, a wholly aromatic PI system induced from <NUM>,<NUM>'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and <NUM>,<NUM>'-bis(trifluoromethyl)benzidine (TFMB) has no low coefficient of thermal expansion due to a nonlinear/non-coplanar cubic structure of a <NUM>-FDA-based diimide unit but high transparency and excellent solubility.

Accordingly, a plastic material simultaneously satisfying desired various characteristics and thus having high reliability is difficult to develop.

The present inventors synthesize a novel monomer capable of forming polyimide simultaneously satisfying thermal stability and optical transparency and thus, has completed the present inventive concept by confirming that a polymer formed from the monomer has a high thermal stability due to a high glass transition temperature, as well as particular optical properties, for example, high out-of-plane birefringence along with high transparency. A monomer not according to the invention may be represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>,.

The compound not according to the invention represented by Chemical Formula <NUM> has an overall rigid planar structure wherein two aromatic rings are linearly linked and also, includes a bulky substituent at a side chain of the aromatic rings, and thus may improve solubility due to a much higher molecular volume, and in addition, may improve optical characteristics by suppressing formation of an intermolecular stacking structure of a polyimide or poly(amide-imide) copolymer and decreasing charge transfer when amino groups bound at both ends of two aromatic ring react with a dianhydride or a dicarboxylic anhydride to form a polyimide or poly(amide-imide) copolymer. The rigid planar structure has a much lower linear coefficient of thermal expansion, a high glass transition temperature, a high out-of-plane birefringence, high mechanical properties, but may easily form an intermolecular stacking structure and thus form an intermolecular charge transfer complex, and accordingly, a polymer formed therefrom appears yellow and deteriorates optical properties. The compound represented by Chemical Formula <NUM> has a rigid planar structure overall but includes a bulky substituent at a side chain of the two aromatic rings which are linearly linked, and thus may suppress formation of a complex among polymer chains and a charge transfer complex therefrom, and thus, reduce a deterioration of optical properties and simultaneously maintain high thermal stability, a low linear coefficient of thermal expansion, a high out-of-plane birefringence, and excellent mechanical properties due to the overall planar structure. Accordingly, polyimide obtained by reacting the monomer with aromatic dianhydride or the poly(amide-imide) copolymer obtained by reacting the monomer with aromatic dianhydride and aromatic dicarboxylic acid derivative may satisfy high thermal stability and excellent optical properties. Furthermore, the compound may be prepared from easily available inexpensive starting materials, as shown through Examples that will be described later and thus may lower a preparation cost compared with a conventional particular expensive aromatic diamine or an aromatic dianhydride showing excellent optical properties, mechanical properties.

L<NUM> and L<NUM> of Chemical Formula <NUM> are independently O or NH, and for example, L<NUM> and L<NUM> may be O, and
A<NUM> and A<NUM> may independently be a C6 to C20 aromatic ring or a C3 to C20 hetero aromatic ring wherein at least one carbon is replaced by at least one of nitrogen and sulfur, for example, an arylene group selected from benzene, naphthalene, anthracene, and pentalene or a heteroarylene group selected from pyrazole, imidazole, thiazole, triazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, indazole, indolizine, benzimidazole, benzthiazole, benzothiophene, benzopurine, isoquinoline, or purine.

A<NUM> and A<NUM> may independently be an arylene group such as benzene, naphthalene, or anthracene or may independently be a heteroarylene group selected from benzimidazole, benzthiazole, benzothiophene, benzopurine, isoquinoline, or purine.

p and q of Chemical Formula <NUM> may independently be an integer ranging from <NUM> to <NUM>, for example, p and q may independently be an integer of <NUM> or <NUM>, for example, p and q may be all <NUM>, o and r may independently be an integer ranging from <NUM> to <NUM>, for example, o and r may independently be an integer of <NUM> or <NUM>, for example, o and r may be all <NUM> or may be all <NUM>.

In Chemical Formula <NUM>, R<NUM> and R<NUM> may independently be hydrogen, a C1 to C20 alkyl group, for example, one of a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group and a decyl group, for example, an isopropyl group, or a tertiary butyl group (t-butyl group), a C6 to C10 aryl group, for example, a phenyl group or a naphthyl group, a C1 to C10 alkoxy group, for example, a methoxy group, an ethoxy group, or a propoxy group, or a hydroxy group, a halogen, for example, a fluoro group, a nitro group, -CO-NR'R" (wherein, R' and R" are independently hydrogen, a C1 to C20 alkyl group, or C6 to C20 aryl group), or a group represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>,.

L<NUM> and L<NUM> of Chemical Formula <NUM> may independently be COO, C=C, or CONH, A<NUM> and A<NUM> may be a substituted or unsubstituted benzene ring, and s and t may independently be an integer ranging from <NUM> to <NUM>, provided that <NUM>≤ s + t ≤<NUM>.

The monomer represented by Chemical Formula <NUM> may not include a halogen atom.

In an example embodiment, o and r of Chemical Formula <NUM> may independently be an integer ranging from <NUM> to <NUM>, for example, o and r may independently be <NUM> or <NUM>, and in an example embodiment, o and r may be all <NUM> or may be all <NUM>.

In an example embodiment, R<NUM> and R<NUM> of Chemical Formula <NUM> may independently be hydrogen, a C1 to C10 alkyl group, for example, one of a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, and a decyl group, for example, an isopropyl group, or a tertiary butyl group (t-butyl group), a C6 to C10 aryl group, for example, a phenyl group or a naphthyl group, a C1 to C10 alkoxy group, for example, a methoxy group, an ethoxy group, or a propoxy group, a halogen, for example, a fluoro group, a nitro group, -CO-NR'R" (wherein, R' and R" are independently hydrogen, a C1 to C20 alkyl group, a C6 to C20 aryl group, or a C7 to C20 arylalkyl group), or a group represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>,.

In an example embodiment, s and t may independently be an integer ranging from <NUM> to <NUM>, provided that <NUM>≤ s + t ≤<NUM>.

In an example embodiment, the monomer represented by Chemical Formula <NUM> may not include a halogen atom.

Examples of the monomer according to an embodiment may be Compounds M-<NUM> to M-<NUM>, but are not limited thereto:
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>
<CHM>.

In an example embodiment, among the monomers represented by Chemical Formula <NUM>, a compound wherein L<NUM> and L<NUM> are O, and p and q are <NUM> may be prepared according to Reaction Scheme <NUM>:
<CHM>
wherein, in Reaction Scheme <NUM>, "R-" corresponds to moieties represented by "(R<NUM>)o-A<NUM>-" and "(R<NUM>)r-A<NUM>-" in Chemical Formula <NUM> and "Hal" refers to a halogen atom, for example, F, Cl, Br, and I.

As shown in Reaction Scheme <NUM>, the monomer according to an embodiment may be easily prepared according to Reaction Scheme by using commercially available inexpensive starting materials by a person having an ordinary skill in this art.

The monomer is a diamine compound having amino groups at both ends, and accordingly, reacts with a dianhydride compound in the same mole amount to form a polyimide or reacts with a dicarboxylic acid derivative in the same mole amount to form a polyamide. Or, <NUM> mole of the monomer reacts with <NUM> mole of a sum of the dianhydride and the dicarboxylic acid derivative to form a poly(amide-imide) copolymer.

Accordingly, in another embodiment, a polymer, a product of reactants including the monomer according to the embodiment and a dianhydride is provided.

The dianhydride that reacts with the monomer in order to prepare the polyimide is represented by Chemical Formula <NUM>-<NUM> and/or Chemical Formula <NUM>-<NUM>:
<CHM>
wherein in Chemical Formula <NUM>-<NUM>,.

A polymer prepared by reacting a monomer with the dianhydride represented by Chemical Formula <NUM>-<NUM> may include a first imide structural unit represented by Chemical Formula <NUM>-<NUM>:
<CHM>
wherein, in Chemical Formula <NUM>-<NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM>, and R<NUM>, R<NUM>, R<NUM>, n7, and n8 are the same as defined in Chemical Formula <NUM>-<NUM>.

A polymer prepared by reacting a monomer with the dianhydride represented by Chemical Formula <NUM>-<NUM> may include a second imide structural unit represented by Chemical Formula <NUM>-<NUM>:
<CHM>
wherein, in Chemical Formula <NUM>-<NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM>, and L<NUM>, A<NUM>, Ra, m, and n are the same as defined in Chemical Formula <NUM>-<NUM>.

When the monomer is represented by Chemical Formula <NUM>, the first imide structural unit may be represented by Chemical Formula <NUM>-<NUM>:
<CHM>
wherein, in Chemical Formula <NUM>-<NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM>, and R<NUM>, R<NUM>, R<NUM>, n7, and n8 are the same as defined in Chemical Formula <NUM>-<NUM>.

The dianhydride represented by Chemical Formula <NUM>-<NUM> may include dianhydride represented by Chemical Formula <NUM>-<NUM>, dianhydride represented by Chemical Formula <NUM>-<NUM>, or a combination thereof:
<CHM>
<CHM>
wherein, in Chemical Formula <NUM>-<NUM> and Chemical Formula <NUM>-<NUM>,.

When a polymer is prepared by reacting the monomer represented by Chemical Formula <NUM> with the dianhydride represented by Chemical Formula <NUM>-<NUM>, the first imide structural unit may include a structural unit represented by Chemical Formula <NUM>-<NUM>:
<CHM>
wherein, in Chemical Formula <NUM>-<NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM>, and R<NUM>, R<NUM>, n7, and n8 are the same as defined in Chemical Formula <NUM>-<NUM>.

When the monomer is by Chemical Formula <NUM>, the second imide structural unit may be represented by Chemical Formula <NUM>-<NUM>:
<CHM>
wherein, in Chemical Formula <NUM>-<NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM>, and L<NUM>, A<NUM>, Ra, m, and n are the same as defined in Chemical Formula <NUM>-<NUM>.

The dianhydride represented by Chemical Formula <NUM>-<NUM> may include dianhydride represented by Chemical Formula <NUM>-<NUM>, dianhydride represented by Chemical Formula <NUM>-<NUM>, or a combination thereof:
<CHM>
<CHM>
wherein, in Chemical Formula <NUM>-<NUM> and Chemical Formula <NUM>-<NUM>, L<NUM>, A<NUM>, Ra, m, and n are the same as defined in Chemical Formula <NUM>-<NUM>.

When a polymer is prepared by reacting the monomer represented by Chemical Formula <NUM> with the dianhydride represented by Chemical Formula <NUM>-<NUM>, the second imide structural unit may include a structural unit represented by Chemical Formula <NUM>-<NUM>:
<CHM>
wherein, in Chemical Formula <NUM>-<NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM>, and L<NUM>, A<NUM>, Ra, m, and n are the same as defined in Chemical Formula <NUM>-<NUM>.

In another embodiment, a polymer is a product of reactants including the monomer according to the embodiment and a dicarboxylic acid derivative. The polymer may be polyamide.

The dicarboxylic acid derivative to provide the polyamide may be represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>,
R<NUM> is at least one of a substituted or unsubstituted phenylene group and a substituted or unsubstituted biphenylene group, each of X is the same or different and is a halogen atom.

In Chemical Formula <NUM>,
R<NUM> may be at least one of a phenylene group and a biphenylene group, and X may independently be Cl or Br.

Polyamide prepared from the monomer represented by Chemical Formula <NUM> and the dicarboxylic acid derivative represented by Chemical Formula <NUM> may include a first amide structural unit represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM> and R<NUM> is the same as defined in Chemical Formula <NUM>.

When the monomer is the diamine represented by Chemical Formula <NUM>, Chemical Formula <NUM> may be represented by Chemical Formula <NUM>:
<CHM>
wherein, in Chemical Formula <NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM> and R<NUM> is the same as defined in Chemical Formula <NUM>.

R<NUM> of Chemical Formula <NUM> may be a phenylene group or a biphenylene, and when R<NUM> is a phenylene group, the amide structural unit represented by Chemical Formula <NUM> may be represented by Chemical Formula <NUM> or Chemical Formula <NUM>:
<CHM>
<CHM>.

In Chemical Formula <NUM> and Chemical Formula <NUM>, R<NUM>, R<NUM>, A<NUM>, A<NUM>, L<NUM>, L<NUM>, o, p, q, and r are the same as defined in Chemical Formula <NUM>.

When R<NUM> of Chemical Formula <NUM> is a biphenylene group, the amide structural unit represented by Chemical Formula <NUM> may be represented by Chemical Formula <NUM> or Chemical Formula <NUM>:
<CHM>
<CHM>.

The polymer may be a polymer that is a polymerization product of reactants including the monomer represented by Chemical Formula <NUM> according to an embodiment, a dianhydride, and a dicarboxylic acid derivative and may be a poly(amide-imide) copolymer. The poly(amide-imide) copolymer may include at least one of the first imide structural unit and the second imide structural unit, and the first amide structural unit.

In an example embodiment, the polymer may be a product of reactants further including diamine represented by Chemical Formula <NUM> in addition to the diamine represented by Chemical Formula <NUM> according to an embodiment:.

wherein, in Chemical Formula <NUM>,
Rc is a substituted or unsubstituted C6 to C30 aromatic organic group, wherein the substituted or unsubstituted C6 to C30 aromatic organic group is present as a substituted or unsubstituted single aromatic ring; a fused ring including two or more substituted or unsubstituted aromatic rings; or a ring system including two or more of the substituted or unsubstituted single aromatic ring and/or the fused ring that are linked by a single bond, or a functional group of a fluorenylene group, a substituted or unsubstituted C1 to C10 cycloalkylene group, a substituted or unsubstituted C6 to C15 arylene group, -O-, -S-, -C(=O)-, -CH(OH)-, -S(=O)<NUM>-, -Si(CH<NUM>)<NUM>-, -(CH<NUM>)p- (wherein, <NUM>≤p≤<NUM>), -(CF<NUM>)q- (wherein, <NUM>≤q≤<NUM>), -C(CH<NUM>)<NUM>-, -C(CF<NUM>)<NUM>-, -C(=O)NH-, or a combination thereof.

The diamine represented by Chemical Formula <NUM> may include at least one of the diamine represented by Chemical Formula <NUM> and the diamine represented by Chemical Formula <NUM>, wherein the diamine represented by Chemical Formula <NUM> may include <NUM>,<NUM>'-bis(trifluoromethyl)benzidine (TFDB), and the diamine represented by Chemical Formula <NUM> may include <NUM>,<NUM>'-diaminodiphenyl sulfone (DADPS).

The diamine represented by Chemical Formula <NUM> may be included in an amount of less than or equal to <NUM> mol%, for example, about <NUM> mol% to <NUM> mol%, for example, about <NUM> mol% to <NUM> mol%, for example, about <NUM> mol% to about <NUM> mol%, for example, about <NUM> mol% to about <NUM> mol%, for example, about <NUM> mol% to about <NUM> mol%, for example, about <NUM> mol% to about <NUM> mol%, and for example, about <NUM> mol% to about <NUM> mol% based on a total amount of the monomer represented by Chemical Formula <NUM> and the diamine represented by Chemical Formula <NUM>.

When the diamine represented by Chemical Formula <NUM>, for example, at least one of diamine represented by Chemical Formula <NUM> to Chemical Formula <NUM>, is polymerized with a dianhydride, a dicarboxylic acid derivative, or a combination thereof in addition to the monomer represented by Chemical Formula <NUM>, the polymer may further include a second imide structural unit formed by the diamine represented by Chemical Formula <NUM>, for example, at least one of diamine represented by Chemical Formula <NUM> to Chemical Formula <NUM>, the dianhydride represented by Chemical Formula <NUM>, for example, the dianhydride represented by Chemical Formula <NUM> and/or Chemical Formula <NUM>, and may also include a second amide structural unit formed along with the dicarboxylic acid derivative represented by Chemical Formula <NUM>.

The polyimide, polyamide, or the poly(amide-imide) copolymer according to the embodiment may be prepared by a known method in this art by a person having an ordinary skill and is not limited to a particular method.

A polymer prepared from reactants including the monomer according to an embodiment, a dianhydride, a dicarboxylic acid derivative, and/or a combination thereof by a known method may be a polymer of polyimide, polyamide, or a poly(amide-imide) copolymer having desirable optical properties and high heat resistance by adjusting ratios of the monomer, dianhydride, and/or dicarboxylic acid.

The polymer may be, for example, formed as a film, and thus used as a polymer film. The polymer film may be, for example, transparent, and thus used for any use requiring transparency. The polymer film may be, for example, used for various uses such as a substrate, a protective film, a compensation film, an optical film, a dielectric layer, an insulation layer, an adhesive layer.

Hereinafter, a compensation film according to an embodiment is described.

A compensation film according to an embodiment includes the polymer.

That is, the compensation film according to an embodiment may include a polyimide-based polymer including an imide structural unit prepared by reacting the monomer according to an embodiment, that is, the monomer represented by Chemical Formula <NUM> with dianhydride, for example, a first imide structural unit represented by Chemical Formula <NUM>-<NUM> which is prepared by reacting the monomer represented by Chemical Formula <NUM> with dianhydride represented by Chemical Formula <NUM>-<NUM>.

Or, the compensation film according to an embodiment may include a polyimide-based polymer including a second imide structural unit represented by Chemical Formula <NUM>-<NUM> which is prepared by reacting the monomer according to an embodiment, that is, the monomer represented by Chemical Formula <NUM> with dianhydride represented by Chemical Formula <NUM>-<NUM>.

Or, the compensation film according to an embodiment may include a polyimide-based polymer including a first imide structural unit and a second imide structural unit which is prepared by reacting the monomer according to an embodiment, that is, the monomer represented by Chemical Formula <NUM> with dianhydride represented by Chemical Formula <NUM>-<NUM> and dianhydride represented by Chemical Formula <NUM>-<NUM>.

Or, the compensation film may include a polyimide-based polymer that is product of reactants further including the diamine represented by Chemical Formula <NUM> as an additional diamine in addition to the monomer represented by Chemical Formula <NUM>, and the polymer may include a polyimide-based polymer that further includes a third imide structural unit and/or a fourth imide structural unit derived from a reaction of the diamine represented by Chemical Formula <NUM> with dianhydride represented by at least one of Chemical Formula <NUM>-<NUM> and Chemical Formula <NUM>-<NUM>, in addition to the first imide structural unit and second imide structural unit.

In addition, the compensation film may include a polyamide-based polymer including a first amide structural unit prepared by reacting the monomer represented by Chemical Formula <NUM> with the dicarboxylic acid derivative represented by Chemical Formula <NUM> and represented by Chemical Formulae <NUM> to <NUM>.

Or, the compensation film may include a polyamide-based polymer that further includes a second amide structural unit produced from a polymerization reaction of the diamine represented by Chemical Formula <NUM> and the dicarboxylic acid derivative represented by Chemical Formula <NUM> in addition to the first amide structural unit.

Furthermore, the compensation film may include a poly(amide-imide) copolymer including at least one of the first imide structural unit and the second imide structural unit and the first amide structural unit.

In addition, the compensation film may include a poly(amide-imide) copolymer including an imide structural unit including at least one of the third imide structural unit and the fourth imide structural unit in addition to the first imide structural unit and the second imide structural unit, and at least one of the first amide structural unit and/or the second amide structural unit.

A polymer according to an embodiment may include, if necessary, a structural unit that is a reaction product of additional non-limiting monomers, dianhydride, diamine, and/or, dicarboxylic acid derivatives, along with the first imide structural unit and/or second imide structural unit in addition to the structural unit. The additional monomers, dianhydride, diamine and/or dicarboxylic acid derivatives, have no particular limit but may be used along with any other kinds which may reinforce a function of an article manufactured from a polymer or a copolymer formed thereof, for example, an optical film, for example, a compensation film.

A film formed of the polymer according to an embodiment may have high thermal stability, for example, a high glass transition temperature of greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, and for example, greater than or equal to about <NUM>.

In addition, the film formed of the polymer according to an embodiment may have excellent optical characteristic, for example, high light transmittance at about <NUM>, for example, transmittance of greater than or equal to about <NUM> %, for example, greater than or equal to about <NUM> %, for example, greater than or equal to about <NUM> %, for example, greater than or equal to about <NUM> %, and for example, greater than or equal to about <NUM> %.

In addition, the film formed of the polymer according to an embodiment may have a high out-of-plane birefringence, for example, a retardation of greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, for example, greater than or equal to about <NUM>, and for example, greater than or equal to about <NUM> at a thin film thickness of less than or equal to about <NUM>, for example, less than or equal to about <NUM>, for example, less than or equal to about <NUM>, for example, less than or equal to about <NUM>, for example, less than or equal to about <NUM>, for example, less than or equal to about <NUM>, for example, less than or equal to about <NUM>, for example, less than or equal to about <NUM>, for example, less than or equal to about <NUM>.

In other words, the film formed of the polymer according to an embodiment shows high thermal stability, for example, a high glass transition temperature and excellent optical characteristics, for example, high light transmittance at <NUM>, and high birefringence, particularly, at a thin film thickness of less than or equal to about <NUM>, and thus, may be used as an optical film such as a compensation film.

When the film is used as a compensation film, the compensation film may have a predetermined retardation by changing light absorption characteristics depending on a refractive index and a wavelength.

A retardation (R) of the compensation film may be represented by an in-plane retardation (Ro) and a thickness direction retardation (Rth). The in-plane retardation (Ro) of compensation film is a retardation generated in in-plane of the compensation film and may be represented by Ro=(nx-ny)d. The thickness direction retardation (Rth) of the compensation film is a retardation generated in a thickness direction of the compensation film and may be represented by Rth={[(nx+ny)/<NUM>]-nz}d. Herein, nx is a refractive index in a direction having a highest in-plane refractive index in a plane of the compensation film (hereinafter, referred to as a 'slow axis'), ny is a refractive index in a direction having a lowest in-plane refractive index in a plane of the compensation film (hereinafter, referred to as a 'fast axis'), nz is a refractive index in a direction perpendicular to the slow axis and the fast axis of the compensation film, and d is a thickness of the compensation film.

The compensation film may have predetermined in-plane retardation and thickness direction retardation by changing the nx, ny, nz, and/or thickness (d).

The retardation of the compensation film may be the same or different depending on a wavelength.

For example, the compensation film may have a forward wavelength dispersion retardation wherein a retardation about light at a short wavelength is larger than a retardation about light at a long wavelength. When a <NUM> wavelength is a reference wavelength, for example retardations (R) at <NUM>, <NUM>, and <NUM> wavelengths of the compensation film may satisfy Relationship Equation <NUM> or <NUM>. <MAT> <MAT>.

For example, the compensation film may have a flat wavelength dispersion retardation wherein a retardation about light at a long wavelength is substantially equivalent to a retardation about light at a short wavelength and retardations (R) at <NUM>, <NUM>, and <NUM> wavelengths of the compensation film may satisfy Relationship Equation <NUM>.

For example, the compensation film may have a reverse wavelength dispersion retardation wherein a retardation about light at a long wavelength is larger than a retardation about light at a short wavelength and for example retardations (R) at <NUM>, <NUM>, and <NUM> wavelengths of the compensation film may satisfy Relationship Equation <NUM> or <NUM>. <MAT> <MAT>.

In Relationship Equations <NUM> to <NUM>,.

The compensation film may be adjusted to have a desired retardation depending on a wavelength.

The compensation film may have high birefringence and thus a relatively thin thickness. The compensation film may have, for example, a thickness of about <NUM> to about <NUM>, within the range, a thickness of about <NUM> to about <NUM>, and within the range, a thickness of about <NUM> to about <NUM>.

The compensation film includes a substantially transparent polymer and thus may be used as a substrate, and accordingly, a separate substrate beneath the compensation film may be omitted. Accordingly, a thickness of the compensation film may be further reduced. Accordingly, the compensation film may be effectively applied to a flexible display device such as a foldable display device or a bendable display device and thus improve optical properties and display characteristics.

The compensation film may be formed, for example, through preparation of the monomer according to an embodiment, polymerization of the monomer into a polymer, formation of the polymer into a polymer film, and elongation of the polymer film.

The polymer film may be elongated, for example, at an elongation rate of about <NUM> % to about <NUM> % at about <NUM> to about <NUM>. Herein, the elongation rate indicates a length ratio after and before the elongation, that is, a degree of length increase of the polymer film after elongation in a uniaxial direction. For example, the polymer film may be elongated in a uniaxial direction.

The compensation film may be prepared by a method including, for example, preparing a monomer according to an embodiment, preparing a polymer by polymerizing the monomer, dissolving or dispersing the polymer in a solvent to prepare a polymer solution or dispersion, forming a thin film by coating the polymer solution or dispersion on a substrate, and heating the thin film.

The compensation film may be used alone or along with other compensation films.

The compensation film may be used with a polarizer and may be used as an optical film to prevent reflection of external light of a display device. The optical film may be for example an anti-reflective film, but is not limited thereto.

<FIG> is a schematic cross-sectional view of an optical film according to an embodiment, <FIG> is a schematic view showing the external light anti-reflection principle of an optical film, and <FIG> is a schematic view showing an embodiment of a polarizing film.

Referring to <FIG>, an optical film <NUM> according to an embodiment includes a polarizer <NUM> and a compensation film <NUM>. The compensation film <NUM> may circularly polarize light passing the polarizer <NUM> to generate retardation and may have an effect on reflection and /or absorption of light.

For example, the optical film <NUM> may be formed on one surface or both surfaces of a display device and particularly on the screen side of the display device and thus may prevent reflection of light inflowing from the outside (hereinafter referred to as "external light"). Accordingly, visibility deterioration due to reflection of external light may be prevented.

<FIG> is a schematic view showing the external light anti-reflection principle of an optical film.

Referring to <FIG>, while the incident unpolarized light having entered from the outside is passed through the polarizer <NUM>, only a first polarized perpendicular component, which is one polarized perpendicular component of two polarized perpendicular components, is transmitted, and the polarized light is shifted into circularly polarized light by passing through the compensation film <NUM>. While the circularly polarized light is reflected in a display panel <NUM> including a substrate, an electrode, and so on, and changes to the circular polarization direction, and the circularly polarized light is passed through the compensation film <NUM> again, only a second polarized perpendicular component, which is the other polarized perpendicular component of the two polarized perpendicular components, may be transmitted. As the second polarized perpendicular component is not passed through the polarizer <NUM>, and light does not exit to the outside, effects of preventing the external light reflection may be provided.

The polarizer <NUM> may be for example a polarizing plate or a polarizing film.

The polarizer <NUM> may be, for example, a PVA polarizer that includes polyvinyl alcohol.

Referring to <FIG>, the polarizer <NUM> may be a polarizing film having an integral structure that is made of for example a melt blend of a polymer resin <NUM> and a dichroic dye <NUM>.

The polymer resin <NUM> may be for example a hydrophobic polymer resin, for example polyolefin such as polyethylene (PE), polypropylene (PP) and a copolymer thereof; polyamide such as nylon and aromatic polyamide; polyester such as polyethylene terephthalate (PET), glycol modified polyethylene terephthalate (PETG), and polyethylene naphthalate (PEN); polyacrylate such as polymethyl(meth)acrylate; polystyrene (PS) such as polystyrene (PS) and an acrylonitrile-styrene copolymer; polycarbonate; a vinyl chloride-based resin; polyimide; a sulfone resin; polyethersulfone; polyether-etherketone; polyphenylene sulfide; a polyvinyl alcohol resin; a polyvinylidene chloride resin; a polyvinyl butyral resin; an allylate resin; polyoxymethylene; epoxy resin, a copolymer thereof, or a combination thereof.

Among them, the polymer resin <NUM> may be for example a polyolefin resin, a polyamide resin, a polyester resin, a polyacrylic resin, a polystyrene resin, a copolymer thereof, or a combination thereof, for example polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), glycol modified polyethylene terephthalate (PETG), polyethylene naphthalate (PEN), nylon, a copolymer thereof, or a combination thereof.

Among them, the polymer resin <NUM> may be polyolefin. The polyolefin may be for example a mixture of at least two selected from polyethylene (PE), polypropylene (PP), a copolymer of polyethylene and polypropylene (PE-PP), and may be for example a mixture of polypropylene (PP) and a polyethylene-polypropylene copolymer (PE-PP).

The polymer resin <NUM> may have transmittance of greater than or equal to about <NUM> % in a wavelength region of about <NUM> to <NUM>. The polymer resin <NUM> may be elongated in a uniaxial direction. The uniaxial direction may be the same as a length direction of the dichroic dye <NUM> that will be described later.

The dichroic dye <NUM> is dispersed in the polymer resin <NUM> and aligned in one direction along the elongation direction of the polymer resin <NUM>. The dichroic dye <NUM> transmits one perpendicular polarization component out of two perpendicular polarization components in a predetermined wavelength region.

The dichroic dye <NUM> may be included in an amount of about <NUM> to about <NUM> parts by weight based on <NUM> parts by weight of the polymer resin <NUM>. Within the range, sufficient polarization characteristics may be obtained without deteriorating transmittance of a polarization film. Within the above range, the dichroic dye <NUM> may be included in an amount of about <NUM> to about <NUM> part by weight based on <NUM> parts by weight of the polymer resin <NUM>.

The polarizer <NUM> may have a relatively thin thickness of less than or equal to about <NUM>, for example, about <NUM> to about <NUM>. When the polarizing film <NUM> has a thickness with the range, the polarizer <NUM> is relatively thinner than a polyvinyl alcohol polarizing plate requiring a protective layer such as triacetyl cellulose (TAC), and thus may realize a thin display device.

The compensation film <NUM> is the same as described above.

The optical film <NUM> may further include a correction layer (not shown) disposed on one surface of the compensation film <NUM>. The correction layer may be for example a color shift resistant layer, but is not limited thereto.

The optical film <NUM> may further include a light blocking layer (not shown) extended along the edge. The light blocking layer may be extended along the circumference of the optical film <NUM> and may be for example disposed between the polarizer <NUM> and the compensation film <NUM>. The light blocking layer may include an opaque material, for example, a black material. For example, the light blocking layer may be made of a black ink.

The optical film <NUM> may be applied to various display devices.

A display device according to an embodiment includes a display panel and an optical film disposed on one surface of the display panel. The display panel may be a liquid crystal panel or an organic light emitting panel, but is not limited thereto.

Hereinafter, for one example of the display device, an organic light emitting diode (OLED) display is described.

<FIG> is a schematic cross-sectional view of an organic light emitting diode (OLED) display according to an embodiment.

Referring to <FIG>, an organic light emitting diode (OLED) display according to an embodiment includes an organic light emitting panel <NUM> and an optical film <NUM> disposed on one surface of the organic light emitting panel <NUM>.

The organic light emitting panel <NUM> may include a base substrate <NUM>, a lower electrode <NUM>, an organic emission layer <NUM>, an upper electrode <NUM>, and an encapsulation substrate <NUM>.

The base substrate <NUM> may be made of glass or a plastic.

One of the lower electrode <NUM> and the upper electrode <NUM> may be an anode and the other may be a cathode. The anode may be an electrode into which holes are injected and may be made of a transparent conductive material having a high work function and passing the emitted light externally, for example ITO or IZO. The cathode is an electrode into which electrons are injected and may be made of a conducting material having a low work function and having no effect on an organic material, such as organic emission layer <NUM>, for example aluminum (Al), calcium (Ca), and barium (Ba).

The organic emission layer <NUM> includes an organic material which may emit light when applying a voltage to the lower electrode <NUM> and the upper electrode <NUM>.

An auxiliary layer (not shown) may be further provided between the lower electrode <NUM> and the organic emission layer <NUM> and/or between the upper electrode <NUM> and the organic emission layer <NUM>. The auxiliary layer may include a hole transporting layer, a hole injecting layer, an electron injecting layer, and an electron transporting layer in order to balance electrons and holes.

The encapsulation substrate <NUM> may be made of glass, a metal, or a polymer, and may seal the lower electrode <NUM>, the organic emission layer <NUM>, and the upper electrode <NUM> to prevent moisture and/or oxygen inflowing from the outside.

The optical film <NUM> may be disposed at a light emitting side. For example, in the case of a bottom emission structure emitting light at the side of the base substrate <NUM>, the optical film <NUM> may be disposed on the exterior side of the base substrate <NUM>, while on the other hand, in the case of a top emission structure emitting light at the side of the encapsulation substrate <NUM>, the optical film <NUM> may be disposed on the exterior side of the encapsulation substrate <NUM>.

The optical film <NUM> may include the integral structured polarizer <NUM> and the integral structured compensation film <NUM>. The polarizer <NUM> and the compensation film <NUM> are the same as described above and may prevent light passing the polarizer <NUM> from being reflected by a metal such as an electrode of the organic light emitting panel <NUM> and emitting outside of the organic light emitting device, and thus prevents visibility from being deteriorated by externally inflow light. Therefore, display characteristics of the organic light emitting diode (OLED) display may be improved.

Hereinafter, for one example of the display device, a liquid crystal display (LCD) is described.

<FIG> is a schematic cross-sectional view of a liquid crystal display (LCD) according to an embodiment.

Referring to <FIG>, a liquid crystal display (LCD) according to an embodiment includes a liquid crystal panel <NUM> and an optical film <NUM> positioned on one surface or both surfaces of the liquid crystal panel <NUM>.

The liquid crystal panel <NUM> may be a twist nematic (TN) mode panel, a vertical alignment (PVA) mode panel, an in-plane switching (IPS) mode panel, an optically compensated bend (OCB) mode panel.

The liquid crystal panel <NUM> may include a first display panel <NUM>, a second display panel <NUM>, and a liquid crystal layer <NUM> interposed between the first display panel <NUM> and the second display panel <NUM>.

The first display panel <NUM> may include, for example, a thin film transistor (not shown) formed on a substrate (not shown) and a first electric field generating electrode (not shown) connected to the same, and the second display panel <NUM> may include, for example, a color filter (not shown) formed on a substrate (not shown) and a second electric field generating electrode (not shown). However, it is not limited thereto, and the color filter may be included in the first display panel <NUM>, while the first electric field generating electrode and the second electric field generating electrode may be disposed on the first display panel <NUM> together.

The liquid crystal layer <NUM> may include a plurality of liquid crystal molecules. The liquid crystal molecules may have positive or negative dielectric anisotropy. In the case of the liquid crystal molecules having positive dielectric anisotropy, the major axes thereof may be aligned substantially parallel to the surface of the first display panel <NUM> and the second display panel <NUM> when not applying an electric field, and the major axes may be aligned substantially perpendicular to the surface of the first display panel <NUM> and second display panel <NUM> when applying an electric field. On the contrary, in the case of the liquid crystal molecules having negative dielectric anisotropy, the major axes may be aligned substantially perpendicular to the surface of the first display panel <NUM> and the second display panel <NUM> when not applying an electric field, and the major axes may be aligned substantially parallel to the surface of the first display panel <NUM> and the second display panel <NUM> when applying an electric field.

The optical film <NUM> may be disposed on the outside of the liquid crystal panel <NUM>. Although the optical film <NUM> is shown to be provided on both the lower part and the upper part of the liquid crystal panel <NUM> in the drawing, it is not limited thereto, and it may be formed on only one of the lower part and the upper part of the liquid crystal panel <NUM>.

Hereinafter, the present disclosure is illustrated in more detail with reference to examples.

Compound M-<NUM> is prepared according to Reaction Scheme M-<NUM>, and a method of preparing Intermediate I-<NUM> and Compound M-<NUM> as a final product are classified into Steps <NUM> and <NUM> and illustrated in detail as follows:
<CHM>.

<NUM>,<NUM>'-dinitro-<NUM>,<NUM>'-biphenic acid (mw = <NUM>/mol, <NUM> mol, m = <NUM> gr), benzylbromide (mw = <NUM>/mol, <NUM> mol, m = <NUM> gr), and potassium hydrogen carbonate (m = <NUM><NUM>/mol, <NUM> mol, m = <NUM> gr) are added to <NUM> of dimethyl acetamide (DMAC), and the mixture is stirred under a nitrogen atmosphere at <NUM> for <NUM> hours. When a reaction is complete, the mixture is poured into <NUM> of water, and surplus potassium hydrogen carbonate is decomposed by adding aqueous hydrochloric acid thereto. A brown solid precipitated therein is filtered, washed with water, and dried. A crude product is three times crystallized by using a mixed solvent of dichloromethane (DCM) and methanol. Intermediate I-<NUM> as a product is light yellow crystalline and has m = <NUM> gr (mw = <NUM>/mol, <NUM> mol) and an yield of <NUM> %. A <NUM>H NMR graph of Intermediate I-<NUM> is shown in <FIG>.

<NUM>H NMR (DMSO-d<NUM>) <NUM>, δ, ppm: <NUM> (s, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM> (d, <NUM>, J<NUM> = <NUM>), <NUM> (dd, <NUM>, J<NUM> = <NUM>, J<NUM> = <NUM>), <NUM> (d, <NUM>, J<NUM> = <NUM>).

<NUM> gr of Intermediate I-<NUM> (<NUM>,<NUM>'-dinitro-biphenyl-<NUM>,<NUM>'-dicarboxylic acid dibenzyl ester) (mw = <NUM>/mol, <NUM> mol) is put into a <NUM> beaker and dissolved in a mixture of <NUM> of acetic acid and <NUM> of methanol. <NUM> gr of iron powder (mw = <NUM>/mol, <NUM> mol) is little by little added to the dinitro compound solution within <NUM> minutes while stirred. The mixture is maintained for one hour while heated and stirred (a color of a suspension gradually becomes bright). When a reaction is complete, <NUM> of cold water is added to the suspension, and a diamino compound is extracted by three times using <NUM> of ethyl acetate at each time. The collected ethyl acetate extract is washed with water (<NUM> X <NUM>) and a <NUM> % aqueous sodium bicarbonate (2X0. <NUM>) and dried with magnesium sulfate. The ethyl acetate is evaporated under a reduced pressure to obtain a bright yellow solid. A crude product is dissolved in <NUM> of water including <NUM> of concentrated hydrochloric acid. The boiling solution is treated with two spoonful of charcoal, and filtered in a hot state. The filtered solution is cooled down to room temperature to precipitate white crystalline hydrochloric acid. The precipitate is filtered and then, redissolved in <NUM> of boiling water including <NUM> L of concentrated aqueous hydrochloric acid. The solution is once more treated with one spoonful of charcoal and filtered in a hot state. A resulting material is strongly stirred while a colorless hydrochloric acid solution is slowly added to <NUM> of ice-cooled water including <NUM> of <NUM> % aqueous ammonium hydroxide. A white diamine precipitate is produced therefrom. The product is filtered, clearly washed with water, and dried for <NUM> hours in the air to remove extra water and at <NUM> under vacuum. <NUM> gr of Compound M-<NUM> (mw = <NUM>/mol, <NUM> mmol) is obtained as a white solid (an yield: <NUM> %). <FIG> shows a <NUM>H NMR graph of Compound M-<NUM>, <FIG> shows a <NUM>C NMR graph, and <FIG> shows an enlarged graph of aromatic region of the <NUM>C NMR graph. In addition, <FIG> shows a HRMS APCI mode, <FIG> shows a TGA graph, and <FIG> shows a DSC graph.

<NUM>H NMR (DMSO-d<NUM>) <NUM>, δ, ppm: <NUM> (s, <NUM>), <NUM> (s, <NUM>), <NUM> (dd, <NUM>, J<NUM> = <NUM>, J<NUM> = <NUM>), <NUM> (d, <NUM>, J<NUM> = <NUM>), <NUM> (d, <NUM>, J<NUM> = <NUM>), <NUM>-<NUM> (m, <NUM>), <NUM>-<NUM> (m, <NUM>).

<NUM>C NMR (DMSO-d<NUM>) <NUM>, δc, ppm: <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

Rf= <NUM> (blue-green fluorescent spot, EtOAc:Hex = <NUM>:<NUM>, TLC silica gel <NUM> F254).

HRMS APCI (m/z): <NUM> (measured mass), <NUM> (calculated mass).

Compound M-<NUM> according to Example <NUM> as a diamine, and 6FDA (<NUM>,<NUM>'-(hexafluoroisopropylidene)diphthalic anhydride), s-BPDA (<NUM>,<NUM>',<NUM>,<NUM>'-biphenyl tetracarboxylic dianhydride), and/or DA520 (ester group-containing dianhydride represented by Chemical Formula <NUM>) as dianhydrides are mixed in each ratio shown in Table <NUM> and reacted to prepare each polyamic acid solution according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM>.

Specifically, the polyamic acid solutions according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM> are obtained by dissolving <NUM> equivalent of Compound M-<NUM> according to Example <NUM> as a diamine in dry DAMC, adding <NUM> equivalent of one kind of dianhydride or a mixture of at least two kinds of dianhydrides in each ratio shown in Table <NUM>, and stirring the mixture at <NUM> for <NUM> to <NUM> hours.

A composition, a solid content, and polymerization time of the obtained polyamic acid solutions are shown in Table <NUM>.

The polyamic acid solutions according to Preparation Examples <NUM>-<NUM> and <NUM>-<NUM> are respectively spin-coated at a speed of <NUM>,<NUM> rpm on a <NUM> x <NUM> glass substrate and thermally imidized to form films. Specifically, the spin coated substrates are respectively heated on a hot plate set at <NUM> for <NUM> minutes to be dried, and then, in a furnace, heated at a speed of <NUM>/min from about <NUM> to about <NUM> and maintained at <NUM> for <NUM> minutes to form the films. Herein, the films formed by using the polyamic acid solution according to Preparation Example <NUM>-<NUM> are formed to have two kinds of thickness.

As for the films, thicknesses, out-of-plane birefringences (Δntn), and optical characteristics such as light transmittance at <NUM> (Tr), haze, and YI are measured and shown in Table <NUM>. Each property is measured as below:.

(i) Film Thickness: measured by using Filmetrics F20 (Filmetrics, Inc. , Kanagawa, Japan)
(ii) Out-of-plane Birefringence (Δnth): measured at a wavelength of <NUM> by using a prism coupler (Metricon MODEL <NUM>/M)
(iii) Optical Characteristics (Transmittance, Haze, and Yellow Index): measured by using a spectrophotometer, "Konica Minolta CM3600d" in a transmittance opacity/haze mode.

As shown in Table <NUM>, the polyimide film formed by using novel Compound M-<NUM> as a diamine and a known compound of <NUM>-FDA as a dianhydride according to Preparation Example <NUM>-<NUM> shows high transmittance of greater than or equal to <NUM> %, specifically, greater than or equal to <NUM> %, at <NUM>, but low haze and low YI, and thus excellent optical characteristics. In addition, when the polyamic acid solution according to Preparation Example <NUM>-<NUM> is formed into films having a different thickness, all the films show a high out-of-plane birefringence, but in general, as the thickness is thicker, an out-of-plane birefringence is higher.

The film according to Preparation Example <NUM>-<NUM> is formed by using novel Compound M-<NUM> according to an embodiment as diamine and a mixture of novel dianhydride of the compound represented by Chemical Formula <NUM>, DA520, along with the known compound, <NUM>-FDA, as dianhydrides, and is thinner than the film according to Preparation Example <NUM>-<NUM>, but shows a much high out-of-plane birefringence. In addition, the film according to Preparation Example <NUM>-<NUM> shows high transmittance of greater than or equal to <NUM> % at <NUM> and similar haze and YI to those of the film according to Preparation Example <NUM>-<NUM>, and thus, overall excellent optical characteristics.

Each polyimide solution according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM> is prepared by additionally adding <NUM> equivalents of acetic anhydride and <NUM> equivalents of pyridine to each polyamic acid solution according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM> and stirring the mixture at <NUM> for <NUM> to <NUM> hours for a partially chemical imidization. Compositions, imidization times, solid contents, and inherent viscosity (ηinh) of the obtained polyimide solutions are shown in Table <NUM>.

The inherent viscosity (ηinh) is measured regarding <NUM>/dL of a polymer solution in DMAc by using Cannon PolyVisc Automated Viscosimeter.

The polyimide solutions according to Preparation Examples <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> are respectively spin-coated at a speed of <NUM> rpm to <NUM>,<NUM> rpm on a <NUM> x <NUM> glass substrate. The coated film is dried on a hot plate set at <NUM> for <NUM> minutes and then heated at a temperature-increasing rate of <NUM>/min from about <NUM> to about <NUM> and then, maintained at <NUM> for <NUM> minutes in a furnace. Herein, the polyimide films according to Preparation Examples <NUM>-<NUM> and <NUM>-<NUM> are respectively fromed to have various thicknesses. A thickness, an out-of-plane birefringence (Δntn), light transmittance (%) at <NUM>, haze, YI, and a glass transition temperature of the film are measured and shown in Table <NUM>.

The glass transition temperature (Tg) is measured by using a thermal mechanical analyzer (TMA Q400, TA Instruments) with a fixed tension force of <NUM> N at a speed of <NUM>/min within a temperature range of <NUM> to <NUM>.

As shown in Tables <NUM> and <NUM>, polyimide films may have a different out-of-plane birefringence depending on a method of forming the polyimide films, which are formed by using a polyamic acid solution having the same composition through a thermal imidization or chemical imidization. However, a polyimide film formed by using a novel diamine compound M-<NUM> according to an embodiment has excellent optical properties such as high light transmittance at <NUM>, low haze, and low YI despite an overall thin thickness, for example, a thickness of less than <NUM> and also, shows a high out-of-plane birefringence and thus may be usefully used as an optical film, for example, a compensation film regardless of a thermal or chemical imidization.

As shown in Table <NUM>, as a film thickness is thicker, an out-of-plane birefringence tends to be larger, and transmittance at <NUM>, haze, Yl are not substantially much deteriorated.

In addition, the film obtained by mixing novel dianhydride, DA520, with known dianhydride, 6FDA, and reacting them with novel diamine, Compound M-<NUM>, according to Preparation Example <NUM>-<NUM>, has a much higher out-of-plane birefringence at an equivalent or similar thickness, and in addition, maintains excellent properties, such as, light transmittance at <NUM>, haze, Yl compared with the films formed by using known dianhydride, 6FDA alone (Preparation Example <NUM>-<NUM>) or mixing another known dianhydride, s-BPDA, along with 6FDA (Preparation Examples <NUM>-<NUM> and <NUM>-<NUM>).

Each poly(amide-imide) copolymer according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM> is prepared by mixing Compound M-<NUM> according to Example <NUM>, 6FDA as a dianhydride, and TPCI (terephthaloyl chloride) or BPCI (biphenyl dicarbonylchloride) as a dicarboxylic acid derivative in a ratio shown in Table <NUM> and reacting them.

Specifically, <NUM> equivalents of Compound M-<NUM> according to Example <NUM> as a diamine and <NUM> equivalent of <NUM>-FDA as a dianhydride are added to DAMC and reacted therewith at <NUM> for <NUM> to <NUM> hours to obtain an amic acid solution capped with an amino group at both ends. Subsequently, <NUM> equivalent of a dicarboxylic acid derivative, TPCI or BPCI, are added to the obtained amic acid solution in a ratio shown in Table <NUM>, reacted and copolymerized at <NUM> for <NUM> hours, added with <NUM> equivalents of acetic anhydride and <NUM> equivalents of pyridine, and further reacted at <NUM> for <NUM> to <NUM> hours to obtain a chemically partially imidized poly(amide-imide) copolymer solutions according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM>.

A composition, reaction time, a solid content, and inherent viscosity (ηinh) of the obtained poly(amide-imide) copolymers are shown in Table <NUM>.

The poly(amide-imide) copolymer films according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM> are formed by using the same chemical imidization as illustrated in Preparation Examples <NUM>-<NUM> to <NUM>-<NUM> except for using the polyamideimide) solutions according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM> instead of the polyimide solutions according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM>, and then, a thickness, an out-of-plane birefringence (Δntn), light transmittance (%) at <NUM>, haze, YI, and Tg of the films are measured and shown in Table <NUM>. Each property is measured in the same method as aforementioned.

As shown in Table <NUM>, a poly(amide-imide) copolymer film formed by using Compound M-<NUM> as a novel diamine compound according to an embodiment, 6FDA as a known dianhydride, and a known aromatic dicarboxylic acid derivative has a very thin thickness of around <NUM> or less but a very high out-of-plane birefringence (Δntn). In addition, the film has very high light transmittance of greater than or equal to <NUM> % at <NUM> and excellent optical characteristics, such as, haze, YI. In addition, the film has a glass transition temperature of greater than or equal to <NUM>, and thus high heat resistance and excellent mechanical characteristics.

Poly(amide-amic acid) is prepared by using TFDB (<NUM>,<NUM>'-bis(trifluoromethyl)benzidine), instead of Compound M-<NUM> according to Example <NUM> as diamine.

Specifically, polyamic acid caped with an amino group at both ends is obtained by adding <NUM> equivalents of TFDB as diamine and <NUM> equivalent of <NUM>-FDA as a dianhydride to DMAc and reacting them at <NUM> for <NUM> hours. Then, chemically partially imidized poly(amide-imide) copolymer solutions according to Comparative Preparation Examples <NUM>-<NUM> and <NUM>-<NUM> are obtained by respectively adding <NUM> equivalent of a dicarboxylic acid derivative, TPCI or BPCI, to the obtained polyamic acid solution as shown in Table <NUM>, copolymerizing the mixture at <NUM> for <NUM> hour, adding <NUM> equivalent of acetic anhydride and <NUM> equivalent of pyridine thereto, and further reacting them at <NUM> for <NUM> hours.

A composition, a solid content, and inherent viscosity (ηinh) of the obtained poly(amide-imide) copolymer solution are shown in Table <NUM>.

As shown in Table <NUM>, the films according to Comparative Preparation Examples <NUM>-<NUM> and <NUM>-<NUM> have the similar composition to those of the polyamideimide) copolymer film according to Preparation Examples <NUM>-<NUM> and <NUM>-<NUM>, except for using a known compound, TFDB, instead of Compound M-<NUM> according to Example <NUM> as diamine.

A poly(amide-imide) copolymer film is formed by using the same chemical imidization as illustrated in Preparation Examples <NUM>-<NUM> to <NUM>-<NUM>, except for using the poly(amide-imide) copolymer solutions according to Comparative Preparation Examples <NUM>-<NUM> and <NUM>-<NUM> instead of the polyimide solutions according to Preparation Examples <NUM>-<NUM> to <NUM>-<NUM>, and then, a thickness, an out-of-plane birefringence (Δntn), light transmittance (%) at <NUM>, haze, and YI of the film are measured and shown in Table <NUM>. Each property is measured as illustrated above.

As shown in Table <NUM>, the poly(amide-imide) copolymer films formed to have the same composition as those of Preparation Examples <NUM>-<NUM> and <NUM>-<NUM> by using known TFDB instead of Compound M-<NUM> according to Example <NUM> as a diamine according to Comparative Preparation Examples <NUM>-<NUM> and <NUM>-<NUM> have a much thicker thickness but a lower out-of-plane birefringence (Δnth) than those of the films according to Preparation Examples <NUM>-<NUM> and <NUM>-<NUM>. The films may have a little higher or equivalent optical characteristics such as light transmittance at <NUM>, haze, and YI compared with those of the films according to Preparation Examples <NUM>-<NUM> and <NUM>-<NUM>.

As illustrated hereinbefore, the film including a polyimide prepared by polymerizing the novel diamine Compound M-<NUM> according to Example <NUM> with a dianhydride or a poly(amide-imide) copolymer prepared by polymerizing the novel diamine Compound M-<NUM> according to Example <NUM>, a dianhydride, and a dicarboxylic acid derivative has excellent optical characteristics such as high light transmittance of greater than or equal to <NUM> %, for example, greater than or equal to <NUM> %, for example, greater than or equal to <NUM> %, for example, greater than or equal to <NUM> % at <NUM>, low haze, and low YI, and particularly, a high birefringence (Δnth) at a low thin film thickness, for example, a thickness of less than or equal to <NUM>, for example, less than or equal to <NUM>, for example, less than or equal to <NUM>, for example, less than or equal to <NUM>, for example, less than or equal to <NUM>, compared with a polyimide or poly(amide-imide) film formed by using a known diamine, and thus may be usefully used as an optical film, for example, a compensation film.

Furthermore, the novel compounds according to an embodiment may be easily prepared from an inexpensive starting material and thus have an effect of sharply reducing a manufacturing cost when being used to replace an expensive conventional aromatic diamine and/or aromatic dianhydride to prepare a film having high optical properties and high mechanical properties.

Claim 1:
A monomer represented by Chemical Formula <NUM>:
<CHM>
wherein in Chemical Formula <NUM>,
L<NUM> and L<NUM> are independently O or NH,
A<NUM> and A<NUM> are independently benzene, pentalene, pyrazole, imidazole, thiazole, triazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, indazole, indolizine, benzimidazole, benzthiazole, benzothiophene, benzopurine, isoquinoline, or purine,
p and q are independently an integer ranging from <NUM> to <NUM>,
o and r are independently an integer ranging from <NUM> to <NUM>, and
R<NUM> and R<NUM> are independently a group represented by Chemical Formula <NUM>, hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C3 to C30 cycloalkoxy group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C2 to C30 heteroaryl group, a substituted or unsubstituted C7 to C30 arylalkyl group, a hydroxy group, a halogen, a nitro group, -NR'R" , -CO-NR'R", or -SiR'R"R"' wherein R', R", and R"' are independently hydrogen, a C1 to C30 alkyl group, a C6 to C30 aryl group, or a C7 to C30 arylalkyl group:
<CHM>
wherein in Chemical Formula <NUM>,
L<NUM> and L<NUM> are independently O, CO, COO, C=C, or CONRb wherein Rb is hydrogen or a C1 to C30 alkyl group,
A<NUM> and A<NUM> are independently a substituted or unsubstituted C6 to C30 aromatic ring, a substituted or unsubstituted fluorene ring, a substituted or unsubstituted C7 to C30 arylalkyl group, or a substituted or unsubstituted C3 to C30 hetero aromatic ring group, and
s and t are independently an integer ranging from <NUM> to <NUM>.