KR20130048135A - Polyamide-based photoreactive polymer and preparation method thereof - Google Patents

Abstract

PURPOSE: A polyamide-based photoreactive polymer is provided to have excellent orientation and electric performance, thereby providing an alignment film and a liquid crystal display device with superior performance. CONSTITUTION: A polyamide-based photoreactive polymer comprises a repeating unit represented by chemical formula 1. A manufacturing method of the polyamide-based photoreactive polymer comprises a step of forming the repeating unit represented by chemical formula 1, by reacting polysuccinimide which includes a repeating unit represented by chemical formula 3, under the presence of a compound represented by R1-O-(CH2)n-NH2. In the chemical formulas; m is 10-1000; n is 2-6; R1 is a photoreactive functional group of a cinnamate-based functional group, azo-based functional group, or coumarin-based functional group.

Description

POLYAMIDE-BASED PHOTOREACTIVE POLYMER AND PREPARATION METHOD THEREOF}

The present invention relates to a novel polyamide-based photoreactive polymer exhibiting excellent photoalignment, a method for preparing the same, and an alignment film including the same.

Liquid crystal displays have the advantages of light weight and low power consumption, and have emerged as the most competitive display to replace CRTs. In particular, since the TFT-LCD driven by the thin film transistor independently drives individual pixels, the response speed of the liquid crystal is very excellent and a high quality moving image can be realized. In order to use the liquid crystal as an optical switch in the TFT-LCD, the liquid crystal must be initially oriented in a predetermined direction on the layer on which the thin film transistor is formed. For this purpose, a liquid crystal alignment layer is used.

For such liquid crystal alignment, a rubbing process has been applied in which a heat-resistant polymer such as polyimide is applied on a transparent glass to form a polymer alignment film, and a rubbing process is performed by rubbing the alignment film while rotating a rotating roller wound with a rubbing cloth at high speed. However, the rubbing process may destroy thin film transistors because foreign matters accumulate on the surface of the alignment layer during rubbing, cause mechanical scratches, or generate high static electricity. In addition, defects are generated due to the fine fibers generated in the rubbing cloth, which is an obstacle in improving production yield.

A liquid crystal alignment method newly designed to overcome the problems of such a rubbing process is liquid crystal alignment (hereinafter, referred to as “light alignment”) by polarized light such as UV.

Photo-alignment means that the photoreactive functional groups bonded to a constant photoreactive polymer by linearly polarized UV cause a photoreaction, and in this process, the main and side groups of the polymer are arranged in a certain direction, thereby aligning the liquid crystals. Refers to mechanism. Many materials have been developed or proposed for photoalignment of liquid crystals. In particular, considerable studies have been made on polymers having photoreactive functional groups such as azo-based functional groups such as azobenzene, cinnamate-based functional groups, coumarin-based functional groups or stilbene-based functional groups (V. Chigrinov, V. Kozenkov, H. -S. Kwok, Photoalignment of Liquid Crystalline Materials: Physics and Application, Wiley, NY, 2008).

Among such photo-oriented polymers, there are polyacrylate-based polymers, polymethacrylate-based polymers or polyvinyl ester-based polymers having the photoreactive functional groups (US Patent, No. 6,001,277, 1999 K. Ichimura et al. And US Patent). No. 5,543,267, 1996, J. Stumpe, V. Shibaev et al. In addition, polyamide-based polymers or polyimidoamide-based polymers have been known (U.S. Patent, No 6,001,277, 1999 K. Ichimura et al.).

However, among these polymers, those showing excellent photo-alignment properties are quite limited, and thus, various applications of the photo-alignment polymers are facing limitations. For this reason, studies on various polymers exhibiting excellent optical orientation are continued.

The present invention provides a novel polyamide-based photoreactive polymer exhibiting excellent photoalignment and a process for producing the same.

The present invention also provides an alignment film including the photoreactive polymer and a display device including the same.

The present invention provides a polyamide-based photoreactive polymer comprising a repeating unit of formula (I):

[Formula 1]

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group.

In addition, the present invention, in the presence of the compound represented by R ₁ -O- (CH ₂ ) _n -NH ₂ ring-opening reaction of the polysuccinimide including the repeating unit of the formula (3) to the repeating unit of the formula (1) It provides a process for preparing the polyamide-based photoreactive polymer comprising the step of forming:

(3)

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group.

In addition, the present invention comprises the steps of ring-opening a polysuccinimide containing a repeating unit of the formula (3) in the presence of a compound represented by HO- (CH ₂ ) _n -NH ₂ to form a repeating unit of the formula (3b); And reacting at least a portion of the repeating unit of formula 3b with a compound represented by R ₁ -Cl to form the repeating unit of formula 1, wherein the polyamide-based photoreactive polymer is prepared.

(3)

(3b)

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group having a carbonyl group at the terminal bonded to chlorine (Cl). .

The present invention also provides an alignment film containing the photoreactive polymer and a display element comprising such an alignment film.

The photoreactive polymers according to the present invention may exhibit improved photoalignment compared to previously known photoalignable polymers. Therefore, it is possible to provide a display device such as an alignment film and a liquid crystal display having excellent characteristics by using the photoreactive polymer, and the process efficiency can also be greatly improved.

FIG. 1 schematically illustrates an example of a process of forming an alignment layer using the photoreactive polymer and aligning the liquid crystal using the photoreactive polymer.
FIG. 2 is an example of a UV absorbance measurement result showing that the maximum absorbance decreases due to photoreaction at a reference wavelength of about 312 nm when the cinnamate photoreactive functional group is bonded to the photoreactive polymer of one embodiment.
Figure 3 is an example of UV absorbance measurement results showing that when the coumarin-based photoreactive functional group is bonded to the photoreactive polymer of one embodiment, the decrease in absorbance by the photoreaction at wavelengths of about 227, 280 and 345nm.
4A to 4E show absorbance measurement results and anisotropy measurement results of A (parallel) and A (perpendicular) when the alignment layer and the liquid crystal cell are formed using the photoreactive polymers of Examples 1 to 5, respectively.

Hereinafter, a photoreactive polymer, a method for preparing the same, and an alignment layer including the photoreactive polymer according to an embodiment of the present invention will be described in detail.

According to one embodiment of the invention, there is provided a polyamide-based photoreactive polymer comprising a repeating unit of formula (I):

[Formula 1]

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group.

The photoreactive polymer has a structure in which a photoreactive functional group exhibiting excellent photoalignment is bonded to a polymer terminal via a constant linker (ie, -C (= O) -NH- (CH ₂ ) _n -O-). Due to these structural properties, when polarized light is irradiated on the photoreactive polymer, the photoreactive functional groups may be more smoothly photoreacted and arranged in a predetermined direction. More specifically, the photoreaction occurs through a reaction mechanism such as photochemical isomerization of the photoreactive functional group or [2 + 2] cycloaddition reactions. As a result, the orientation of the photoreaction product is formed along the polarization direction, and anisotropy appears. And the liquid crystal can be oriented by such a photoreaction product. Therefore, the photoreactive polymer can be preferably applied to the alignment layer in a display element such as a liquid crystal display.

In such a photoreactive polymer, the photoreactive functional group such as the cinnamate-based functional group, azo-based functional group or coumarin-based functional group may have various structures including the functional group such as cinnamate group, azobenzene or coumarin group. For example, in consideration of the excellent photo-alignment of the photoreactive polymer, the photoreactive functional group R ₁ has the same structure as the cinnamate functional group represented by Formula 1a, the coumarin functional group represented by Formula 1b or the azo functional group represented by Formula 1c Can have:

[Formula 1a]

[Chemical Formula 1b]

[Chemical Formula 1c]

In Chemical Formulas 1a to 1c,

n1 is an integer of 0 to 4, n2 is an integer of 0 to 5,

A is substituted or unsubstituted alkylene having 1 to 20 carbon atoms, carbonyl, carboxy, substituted or unsubstituted arylene having 6 to 40 carbon atoms, or a simple bond,

B is a simple bond; Substituted or unsubstituted alkylene having 1 to 20 carbon atoms; Carbonyl; Carboxy; ester; Substituted or unsubstituted alkoxylene having 1 to 10 carbon atoms; Substituted or unsubstituted arylene having 6 to 40 carbon atoms; And substituted or unsubstituted heteroarylene having 6 to 40 carbon atoms,

X is oxygen or sulfur,

P is a simple bond; Substituted or unsubstituted alkylene having 1 to 20 carbon atoms; Carbonyl; Substituted or unsubstituted alkenylene having 2 to 20 carbon atoms; Substituted or unsubstituted cycloalkylene having 3 to 12 carbon atoms; Substituted or unsubstituted arylene having 6 to 40 carbon atoms; Substituted or unsubstituted aralkylene having 7 to 15 carbon atoms; Substituted or unsubstituted alkynylene having 2 to 20 carbon atoms; And substituted or unsubstituted cycloalkylene having 4 to 8 carbon atoms,

R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are the same as or different from each other, and each independently hydrogen; halogen; Substituted or unsubstituted alkyl having 1 to 20 carbon atoms; Substituted or unsubstituted cycloalkyl having 4 to 8 carbon atoms; Substituted or unsubstituted alkoxy having 1 to 20 carbon atoms; Substituted or unsubstituted aryloxy having 6 to 30 carbon atoms; Substituted or unsubstituted C6-C40 aryl; Heteroaryl having 6 to 40 carbon atoms, including group 14, 15 or 16 hetero elements; Substituted or unsubstituted alkoxyaryl having 6 to 40 carbon atoms; Nitrile; Nitro; And hydroxy.

More specific examples of such photoreactive functional groups R ₁ include the functional groups listed below, and having such photoreactive functional groups, the photoreactive polymer may exhibit better photoalignment:

In addition, the photoreactive polymer may be a homopolymer including one repeating unit of Formula 1, or may be a copolymer including two or more repeating units belonging to Formula 1. In the structure of such copolymers, each repeating unit may have a different kind of photoreactive functional group. In addition, the photoreactive polymer may be a copolymer further comprising another type of repeating unit together with the repeating unit of Formula 1. Examples of such repeating units include any polyamide repeating unit, an olefin repeating unit, an acrylate repeating unit, or a cyclic olefin based on which a cinnamate-based, coumarin-based or azo-based photoreactive functional group is bonded or unbonded. Can be a repeating unit. For example, the photoreactive polymer may be a copolymer further comprising repeating units represented by the following Formula 2 in terms of compatibility with various organic solvents, coating properties, or adhesion to a substrate. On the other hand, various examples of repeating units that may be further included in the copolymer are disclosed in Patent Publication No. 2010-0021751 and the like:

[Formula 2]

Wherein l is 10 to 1000, n is 2 to 6, and R ₂ is hydrogen; Or substituted or unsubstituted alkyl having 1 to 20 carbon atoms.

,

또는

와 같이 말단에 카보닐기를 갖는 작용기로 될 수 있다. When the photoreactive polymer is a copolymer further comprising a repeating unit of the formula (2), the photoreactive functional group R ₁ is in terms of ease of polymer preparation, etc.,

,

or

It may be a functional group having a carbonyl group at the end, such as.

However, the photoreactive polymer may include the repeating unit of Formula 1 in an amount of at least 10 mol% or more, specifically, about 30 mol% or about 50 mol% or more so that the excellent orientation and the like according to Chemical Formula 1 are not inhibited. Can be. In addition, when the photoreactive polymer includes a repeating unit of Formula 1 and 2, the repeating unit of Formula 1: The repeating unit of Formula 2 is about 0.1: 0.9 to 0.9: 0.1, preferably about 0.2: 0.8 to And may be included in a molar ratio of about 0.8: 0.2.

In addition, the repeating unit of Formula 1 or 2 constituting the photoreactive polymer may have a degree of polymerization of about 10 to 1,000, preferably about 50 to 500. In addition, the photoreactive polymer may have a weight average molecular weight of about 15000 to 200000, preferably about 30000 to 150000. Accordingly, the photoreactive polymer may be suitably included in the composition for forming the alignment layer to exhibit excellent coating properties, but the alignment layer formed therefrom may exhibit excellent photoalignment or the like.

Meanwhile, in the structure of the photoreactive polymer described above, the definition of each substituent is specifically as follows:

Firstly, "alkyl" means a linear or branched saturated monovalent hydrocarbon moiety of 1 to 20, preferably 1 to 10, more preferably 1 to 6 carbon atoms. The alkyl group is not only unsubstituted but can also be referred to as being further substituted by a certain substituent group described later. Examples of alkyl groups include methyl, ethyl, propyl, 2-propyl, n-butyl, iso-butyl, tert- butyl, pentyl, hexyl, dodecyl, fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, Dichloromethyl, trichloromethyl, iodomethyl, bromomethyl and the like.

"Cycloalkyl" refers to a saturated or unsaturated non-aromatic monovalent monocyclic, bicyclic or tricyclic hydrocarbon moiety of 3 to 12 ring carbons, which also includes those further substituted by certain substituents described below. can do. For example, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl, cyclooctyl, decahydronaphthalenyl, adamantyl, norbornyl (ie, bicyclo [2,2, 1] hept-5-enyl).

“Aryl” means a monovalent monocyclic, bicyclic or tricyclic aromatic hydrocarbon moiety having from 6 to 40, preferably from 6 to 12 ring atoms, encompassing those further substituted by certain substituents described below. May be referred to. Examples of the aryl group include phenyl, naphthalenyl and fluorenyl.

"Alkoxyaryl" means that at least one hydrogen atom of the aryl group defined above is substituted with an alkoxy group. Examples of alkoxyaryl groups include methoxyphenyl, ethoxyphenyl, propoxyphenyl, butoxyphenyl, pentoxyphenyl, hexoxyphenyl, heptoxy, octoxy, noxy, methoxybiphenyl, methoxynaphthalenyl, Methoxyfluorenyl, methoxyanthracenyl and the like.

"Alkylene" means a linear or branched saturated divalent hydrocarbon moiety of 1 to 20, preferably 1 to 10, more preferably 1 to 6 carbon atoms. The alkylene group may be referred to as being further substituted by a certain substituent group described later. Examples of the alkylene group include methylene, ethylene, propylene, butylene, hexylene and the like.

“Alkenylene” means a linear or branched divalent hydrocarbon moiety of 2 to 20, preferably 2 to 10, more preferably 2 to 6 carbon atoms containing at least one carbon-carbon double bond. do. The alkenylene group may be bonded through a carbon atom containing a carbon-carbon double bond and / or through a saturated carbon atom. Alkenylene group can also refer to what is further substituted by the specific substituent mentioned later.

“Cycloalkylene” refers to a saturated or unsaturated non-aromatic divalent monocyclic, bicyclic or tricyclic hydrocarbon moiety of 3 to 12 ring carbons, including those further substituted by certain substituents described below. May be referred to. Examples thereof include cyclopropylene and cyclobutylene.

“Arylene” means a divalent monocyclic, bicyclic or tricyclic aromatic hydrocarbon moiety having 6 to 20, preferably 6 to 12 ring atoms, which is further substituted by the following substituents It may be referred to inclusively. The aromatic moiety contains only carbon atoms. Examples of the arylene group include phenylene and the like.

“Aralkylene” means a divalent moiety in which at least one hydrogen atom of the alkyl group defined above is substituted with an aryl group, and may be referred to as a whole further substituted by a specific substituent described below. For example, benzylene etc. can be mentioned.

By "alkynylene" it is meant a linear or branched divalent hydrocarbon moiety of 2 to 20 carbon atoms, preferably 2 to 10, more preferably 2 to 6, carbon atoms containing at least one carbon-carbon triple bond do. The alkynylene group may be bonded through a carbon atom containing a carbon-carbon triple bond or through a saturated carbon atom. The alkynylene group may be referred to collectively as being further substituted by a certain substituent group described later. For example, ethynylene or propynylene.

Substituted or unsubstituted substituents described above encompass not only each of these substituents themselves, but also those further substituted by constant substituents. In the present specification, examples of the substituent which may be further substituted with each substituent include halogen, alkyl, alkenyl, alkynyl, haloalkyl, haloalkenyl, haloalkynyl, aryl, haloaryl, aralkyl, haloaralkyl, Alkoxy, haloalcohol, carbonyloxy, halocarbonyloxy, aryloxy, haloaryloxy, silyl or siloxy and the like.

The photoreactive polymers described above may exhibit photoreactivity under exposure of polarized light having a wavelength of about 150 to 450 nm, for example, in the UV region having a wavelength of about 200 to 400 nm, more specifically, a wavelength of about 250 to 350 nm. Excellent photoreactivity, orientation, etc. can be exhibited under the exposure of the polarized light.

The photoreactive polymer may be photo-oriented by causing a photoreaction through a predetermined mechanism depending on the photoreactive functional group. For example, in the case of an azo functional group such as Chemical Formula 1c, photo-alignment may be caused by photoreaction through a reaction mechanism of cyclic trans-cis-trans ( EZE ) isomerization of an azo-containing chromophore. That is, the azobenzene group of the rigid rod structure (rigid rod) can be converted from the E isomer to the bent shape Z isomer through the photoreaction. This is reversible, and through this photoreaction all photoreactive functional groups and functional groups bound thereto can be oriented in a direction perpendicular to the direction of the electric field vector of polarization. As a result, photo-alignment can proceed (VP Shibaev, A. Yu. Bobrovsky, NI Boiko ＂Photoactive liquid crystalline polymer systems with light-controllable structure and optical properties Progress / Progress in Polymer Science , 2003, v. 28, No. 5, 729-836; Polymers as Electrooptical and Photooptical Active Media.Ed. By VP Shibaev , Springer-Verlag, Berlin-Heidelberg-New-York, 1996; K. Ichimura ＂Photoalignment of liquid crystal systems＂ // Chem. Pew. , 2000, 100, 1847; US Patent No. 5,543,267, 1996, J. Stumpe, V. Shibaev et al.

In the case of coumarin-based functional groups such as Chemical Formula 1b, non-contact optical alignment is possible by forming a stable anisotropic network structure by polarized light irradiation (T. Ikeda, Y. Tian, et al. Synthesis and properties of side-chain). LC polymers with coumarin moieties ＂// Macromol. Chem. Phys. , 2000, v. 201, 1640).

In addition, cinnamate-based functional groups such as Formula 1a may exhibit photoreactivity through two reaction mechanisms, tran-cis isomerization and [2 + 2] -cycloaddition, and may be photo-oriented by such photoreaction (N Kawatsuki et al. ＂Photoregulated LC alignment on photoreactive side chain LC polymers＂ // Jpn. J. Appl. Phys . , 1997, 36, 6464.

The photoreactive polymer of the above-described embodiment may allow the photoreaction and photo-alignment through the above-described reaction mechanism to occur more smoothly as these photoreactive functional groups are bonded to the polyamide ends in a specific structure. Therefore, the photoreactive polymer exhibits more improved photo-alignment property and can be preferably applied to the liquid crystal alignment of the display device.

On the other hand, according to another embodiment of the invention, there is provided a method for producing the photoreactive polymer described above. First, a first embodiment of this production method, by ring-opening a polysuccinimide containing a repeating unit of the formula (3) in the presence of a compound represented by R ₁ -O- (CH ₂ ) _n -NH ₂ Forming a repeating unit of Formula 1 above:

 (3)

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group.

When the polysuccinimide is ring-opened in the presence of a compound represented by R ₁ -O- (CH ₂ ) _n -NH ₂ , the repeating unit of Formula 3 is first ring-opened and the R ₁ -O- By reacting with a terminal amine group of the compound of (CH ₂ ) _n -NH ₂ , a repeating unit of Formula 1 may be formed. This ring-opening reaction can be carried out according to conventional ring-opening reaction conditions, for example, under an organic solvent such as DMF. More specific reaction conditions are described in the Examples below.

In addition, the polysuccinimide including the repeating unit of Formula 3 may be prepared according to conventional methods well known to those skilled in the art. For example, polysuccinimides can be prepared by condensation of aspartic acid in the presence of phosphoric acid ( J. Medicinal Chem. , 1973, v. 16, No. 8, 893).

Meanwhile, a second embodiment of the method for preparing the photoreactive polymer, ring-opening reaction of the polysuccinimide containing the repeating unit of Formula 3 in the presence of a compound represented by HO- (CH ₂ ) _n -NH ₂ To form a repeating unit of Formula 3b; And reacting at least a portion of the repeating unit of Formula 3b with a compound represented by R ₁ -Cl to form a repeating unit of Formula 1 above:

 (3b)

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group having a carbonyl group at the terminal bonded to chlorine (Cl). .

In the presence of the compound of HO- (CH ₂ ) _n -NH ₂ , when the ring-opening reaction of the polysuccinimide including the repeating unit of Formula 3 is carried out, the repeating unit of Formula 3 is first ring-opened while the HO- (CH ₂ ) A repeating unit of Formula 3b may be formed by reacting with a terminal amine group of the compound of _n- NH ₂ . This resultant is then reacted with a photoreactive functional group R ₁ having a carbonyl group at its end with R ₁ -Cl in the form of an acid chloride bonded with chlorine (Cl), such a compound reacts with the terminal hydroxyl group of the repeating unit of Formula 3b. Thus, the repeating unit of Formula 1 may be formed.

,

또는

와 같이 말단에 카보닐기를 갖는 작용기로 될 수 있다. 이로서, 상기 R₁-Cl이 R₁의 말단 카보닐기가 염소에 결합된 산 클로라이드(acyl chloride)의 형태로 되어, 상기 화학식 3b의 반복 단위에 포함된 히드록시기와 적절히 반응해 화학식 1의 반복 단위 및 광반응성 중합체를 높은 수율로 형성할 수 있다. At this time, the ring-opening reaction conditions are similar to those described for the first embodiment of the production method. In addition, in the reaction step of the repeating unit of Formula 3b and R ₁ -Cl, R ₁ is

,

or

It may be a functional group having a carbonyl group at the end, such as. As a result, the R ₁ -Cl is in the form of an acid chloride in which the terminal carbonyl group of R ₁ is bonded to chlorine, and reacts appropriately with a hydroxyl group included in the repeating unit of Formula 3b, thereby repeating the repeating unit of Formula 1 and Photoreactive polymers can be formed in high yields.

In addition, the R ₁ -Cl may react with at least a part of the repeating unit of Formula 3b. At this time, the R ₁ -Cl may react with only some of the repeating units of Formula 3b, for example, about 10 to 90 mol%, preferably about 20 to 80 mol% of Formula 3b. In this case, together with the repeating unit of Formula 1, a photoreactive polymer in the form of a copolymer further comprising the repeating unit of Formula 2 may be appropriately formed. Other more specific reaction conditions are described in Examples described later.

On the other hand, according to another embodiment of the invention, there is provided an alignment film comprising the polyamide-based photoreactive polymer described above. Such an alignment film may also include an alignment film in the form of a film as well as a thin film.

Such alignment films may be prepared using components and manufacturing methods known in the art, except that the above-described photoreactive polymer is included as a photoalignment polymer.

For example, the alignment layer may be formed by dissolving the photoreactive polymer in an organic solvent to obtain a coating composition, then coating the coating composition on a substrate and irradiating UV polarization.

In this case, in consideration of the solubility of the photoreactive polymer, N-methyl-pyrrolidone or dimethylformamide, dimethyl sulfoxide, etc. may be used as the organic solvent, and various organic solvents may be used. After coating the coating composition on the substrate, a drying process may be performed to remove the solvent.

In addition, as a substrate for coating the coating composition, a glass substrate or a quartz substrate may be used, and an alignment film having excellent orientation can be obtained therefrom. In addition, as a coating method of the coating composition, a conventional coating method such as a casting method or a printing method may be applied without particular limitation.

After coating of the coating composition, the alignment layer may be formed by irradiating UV polarization of about 150 to 450 nm. In this case, the UV polarization can be irradiated using a Hg lamp, Xe lamp or a laser having a constant wavelength as a light source, with a polarizing plate or a Glan-Taylor prism.

As for the substrate temperature at the time of irradiating the said UV polarization, normal temperature is preferable. However, in some cases, UV polarized light may be irradiated in a heated state within a temperature range of 100 ° C or lower. The film thickness of the final coating formed through the above-described series of steps is preferably 30 to 1000 nm.

Photoreactivity and photoalignment according to the irradiation of the UV polarization can be confirmed by measuring the absorbance with a UV-vis spectrometer or the like for a predetermined reference wavelength. For example, when a photoreactive functional group bonded to a photoreactive polymer becomes a cinnamate-based functional group, as shown in FIG. 2, the isomerization according to the photoreaction from the decrease of the maximum absorbance at the reference wavelength of about 312 nm and [2] +2] -cycloaddition can be identified. In the case of the coumarin-based functional group, as shown in FIG. 3, the [2 + 2] -cycloaddition by photoreaction can be confirmed from the decrease in absorbance at wavelengths of 227, 280, and 345 nm. In the same way, the azo-based functional group can confirm the isomerization according to the photoreaction.

In addition, A (parallel) and A (perpendicular) were respectively measured in the measurement of stomach absorbance, and DR = (A (∥) -A (⊥)) / (A (∥) + A (⊥)) Anisotropy can be calculated, and the degree of optical orientation can be confirmed from this. As a result of the inventors' identification, the alignment layer including the photoreactive polymer of the embodiment showed anisotropy of about 0.70, for example, about 0.60 to 0.70, so that the photoreactive polymer exhibited excellent photoalignment. To confirm such anisotropy and photoalignment, a dichroic dye represented by the following DD can be used.

DD

DD

Since the above-described alignment layer may exhibit excellent photoalignment by including the photoreactive polymer of one embodiment, it may be preferably used for the alignment of the liquid crystal in a display element such as a liquid crystal display.

For reference, FIG. 1 illustrates an example in which an alignment layer is formed using the photoreactive polymer and the liquid crystal is aligned using the photoreactive polymer. Referring to Figure 1, by applying a coating composition comprising a photoreactive polymer (3) on the substrate (2) and irradiating UV polarization (3), through the photoreaction to arrange the photoreactive functional groups of the polymer in a certain direction (5), and as a result, an alignment film is formed. By forming the liquid crystal molecules 4 on the alignment layer and interacting with the photoreaction products in the alignment layer, the liquid crystal molecules 4 may be aligned (6). In this case, the photoreactive polymer of one embodiment can effectively align the liquid crystal molecules 4 as described above.

Accordingly, according to another embodiment of the present invention, a display device including the alignment layer is provided. Such a display element may be a liquid crystal display device or the like in which the alignment layer is included for alignment of liquid crystals. However, since the configuration of these display elements includes the photoreactive polymer and the alignment layer described above, since the structure of the display device is the same as that of a conventional device, detailed description thereof will be omitted.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. However, the following embodiments are intended to illustrate the invention, but the invention is not limited thereto.

In the examples below all operations dealing with air or water sensitive compounds were carried out using standard Schlenk techniques or dry box techniques. Nuclear magnetic resonance (NMR) spectra were obtained using a Bruker 300 spectrometer, ¹ H NMR at 300 MHz and ¹³ C NMR at 75 MHz, respectively. The molecular weight and molecular weight distribution of the ring-opened hydrogenated polymer were measured using gel permeation chromatography (GPC), in which a polystyrene sample was used as a standard. Toluene was purified by distillation in potassium / benzophenone and dichloromethane was distilled and purified in CaH ₂ .

Example 1

)의 제조는 하기 반응식 1의 3 단계로 이루어졌다. 처음 두 단계는 저 분자량 전구체의 제조를 나타낸다. Azobenzene-containing polyamide-based photoreactive polymer PI (Formula 1, n = 3, R ₁ =

) Was made in three steps of Scheme 1 below. The first two steps represent the preparation of low molecular weight precursors.

[Reaction Scheme 1]

In the first step, (tert-butyl (3- {4- (4-cyanophenyl) diazenyl] phenoxy} propyl) carbamate ( I ) was synthesized. For this purpose, 1 g (4.2 mmmol) in a round bottom flask Tert-butyl-N- (3-bromopropyl) -carbamate, 0.75 g (3.8 mmol) of 4-[(4-hydroxyphenyl) diazenyl] -benzonitrile and 0.82 g (6 mmol) Anhydrous potassium carbonate was added, then 20-30 mL of anhydrous acetone was added and the mixture was refluxed for 24 h The reaction was thin layer chromatography (TLC) (eluent: chloroform / methanol = 10/1). After completion, the reaction precipitate was washed three times with acetone after filtration, the solvent was evaporated with a rotor evaporator and the precipitate was dried The resulting powder was recrystallized from ethanol and dried in air.

In the second step, component ( I ) was suspended in a small amount of ethyl acetate and 2 ml of concentrated hydrochloric acid was slowly added dropwise for 1 hour under vigorous stirring. After 2 hours, the precipitate was filtered off, washed several times with a 5% aqueous solution of potassium carbonate and then dried under room temperature and vacuum. As a result, a brown / yellow powder of 4-{[4- (3-aminopropoxy) phenyl] diazenyl} benzonitrile ( II ) was obtained.

In a third step, polymer PI was produced. To this end, 0.24 g (2.5 mmol) of polysuccinimide ( PSI ) solution dissolved in 5 mL DMF was added into the glass ampoule. Then, under stirring for 10 minutes, a solution of 0.77 g (2.6 mmol) of Component II dissolved in 5 mL DMF was added. Then, argon gas was purged through the reaction mixture for 30 minutes. The ampoule was sealed and placed in an oven at 50 ° C. After 2 days, the ampoule was opened and the DMF was removed with a rotor evaporator. The dry residue was dissolved in tetrahydrofuran (THF) to give a solution of ˜10% concentration; Hexane was added until the formation of the precipitate was complete. The precipitate was filtered off and dissolved in chloroform with 5 vol.% Methanol added. Thereafter, hexanes were added gradually until the formation of the precipitate was complete. The resulting precipitate comprising polymer PI was filtered and dried under vacuum at 90 ° C. for 1 day. Yield: 0.65 g (70%), Mw: 188,000. The polymer PI forms a nematic liquid crystalline phase with an isotropization temperature of 230-236 ° C. (decomposition). The chemical structure of the obtained polymer was confirmed by NMR spectrum; TMS was used as standard and DMSO was used as solvent. NMR ¹ H was measured with a “Bruker Avance-400:” spectrometer with a frequency of 400 MHz.

¹ H-NMR (ppm): 1.7-1.8 (2H), 2.4-2.7 (2H), 3.1-3.3 (2H), 4.0-4.1 (2H), 4.5-5.0 (1H), 7.0-7.1 (2H), 7.7-8.0 (6H). Of PI Chemical shifts in the ¹ H NMR spectrum were as follows:

A thin film of PI on a quartz plate was obtained by spin coating of a chloroform solution and assembled into a light irradiation, sandwich structured cell and filled with nematic liquid crystals (MLC6816, Merck ) doped with a dichroic dye designated DD . As a result, it was confirmed that anisotropic D = 0.67 was reached and exhibits excellent liquid crystal orientation.

[Example 2]

)의 제조는 실시예 1에서 설명된 방법을 사용하는 3 단계로 이루어졌다 (반응식 2 참조). Coumarin-containing polyamide-based photoreactive polymer P-II (in formula 1, n = 3, R ₁ =

) Consisted of three steps using the method described in Example 1 (see Scheme 2).

[Reaction Scheme 2]

In the first two steps, 6- (3-aminopropoxy) coumarin ( III ) was synthesized using 6-hydroxycoumarin and tert-butyl-N- (3-bromopropyl) -carbamate and reacted with the reactants. Used. In the third step, using PSI and precursor III , the synthesis of polyamide proceeded in the same manner as the polymerization method of polyamide PI . The yield of P-II was about 65%. Mw: 158,000. Polymer P-II was an amorphous white-brown powder. The chemical structure of polymer P-II was confirmed by the same NMR spectrum as PI . ¹ H-NMR (ppm): 1.7-1.9 (2H), 2.4-2.7 (2H), 3.1-3.3 (2H), 3.8-4.0 (2H), 4.5-5.1 (1H), 6.4-6.5 (1H), 7.0-7.3 (3H), 7.9-8.0 (1H). Of P-II Chemical shifts in the ¹ H NMR spectrum were as follows:

A thin film of P-II on a quartz plate was obtained by spin coating of a DMF solution and assembled into a cell of light irradiation, sandwich structure and filled with nematic liquid crystal (MLC6816, Merck ) doped with a dichroic dye denoted by DD . lost. As a result, it was confirmed that anisotropic D = 0.66 was shown and excellent liquid crystal alignability was shown.

[Example 3]

)의 제조는 실시예 1에서 설명된 방법을 사용하는 3 단계로 이루어졌다 (반응식 3 참조). Coumarin-containing polyamide-based photoreactive polymer P-III (in formula 1, n = 3, R ₁ =

) Consisted of three steps using the method described in Example 1 (see Scheme 3).

[Reaction Scheme 3]

In the first two steps, 7- (3-aminopropoxy) -4-methyl-coumarin using 4-methylumbelliferone and tert-butyl-N- (3-bromopropyl) -carbamate ( IV ) was synthesized and used as reaction. In the third step, the synthesis of polyamide proceeded in the same manner as the polymerization method of polyamide PI , using PSI and precursor IV . The yield of P-III was about 70%. Mw: 165,000. Polymer P-III was an amorphous white-brown powder. The chemical structure of polymer P-III was confirmed by the same NMR spectrum as PI . ¹ H-NMR (ppm): 1.7-1.9 (2H), 2.2-2.3 (3H), 2.4-2.7 (2H), 3.1-3.3 (2H), 3.8-4.0 (2H), 4.5-5.1 (1H), 6.1--6.2 (1H), 6.7--6.8 (2H), 7.4-7.5 (1H). Of P-III Chemical shifts in the ¹ H NMR spectrum were as follows:

A thin film of P-III on a quartz plate was obtained by spin coating of a chloroform solution and assembled into a light irradiated, sandwich structured cell filled with a nematic liquid crystal (MLC6816, Merck ) doped with a dichroic dye designated DD . lost. As a result, it was confirmed that anisotropic D = 0.61 was shown and excellent liquid crystal alignability was shown.

Example 4

)의 제조는 반응식 4와 같은 두 단계로 이루어졌다. Cinnamoyl-containing polyamide-based photoreactive copolymer P-IV (molar ratio y = 0.6, x = 0.4 in Scheme 4; n = 6 in formula 1, R ₁ =

) Was made in two steps as in Scheme 4.

[Reaction Scheme 4]

In the first step, 1.17 g (10 mmol) of 6-aminohexanol was added while stirring 1 g (10 mmol) of polysuccinimide ( PSI ) solution dissolved in DMF for 30 minutes. After stirring for 8 hours, the mixture was added to excess 1,2-dichloroethane and the precipitate of poly (hydroxyethyl) aspartamide ( PHHA ) formed was separated and dried in vacuo at 80 ° C.

In the second step, a polymer-like reaction of the hydrophilic side chain group of PHHA with chloride anhydride of methoxycinnamic acid was carried out. The degree of modification of PHHA can be varied by varying the molar ratio of the initial reactants.

0.5 g of PHHA was dissolved in DMF and 0.3 g of triethylamine was added. To the resulting solution under stirring and ice cooling, 0.38 g (1.9 mmol) of methoxycinnamic acid chloride DMF solution were added dropwise. After stirring for one hour, the cooling bath was removed and the mixture was stirred continuously at room temperature for 48 hours. The precipitate was then filtered and excess triethylamine was removed by rotor evaporator. The remaining solution of P-IV was added to the excess hexane / methanol mixture (70/30). The precipitate was filtered off and dried under vacuum at 50 ° C. for 1 day. The yield of P-IV was about 60%. Mw: 155,000. Polymer P-IV was an amorphous pale yellow powder. The chemical structure of polymer P-IV was confirmed by NMR spectrum. ¹ H-NMR (ppm): 1.1 to 2.0 (16H), 2.4 to 2.7 (4H), 3.1 to 3.3 (4H), 3.5 to 3.6 (2H), 3.7 to 3.8 (3H), 4.1 to 4.2 (2H), 4.5 ~ 5.0 (2H), 6.3 ~ 6.4 (1H), 6.8 ~ 7.0 (2H), 7.4 ~ 7.6 (2H). Of P-IV Chemical shifts in the ¹ H NMR spectrum were as follows:

A thin film of P-IV on a quartz plate was obtained by spin coating a chloroform solution and assembled into a light irradiated, sandwich-shaped cell filled with nematic liquid crystals (MLC6816, Merck ) doped with a dichroic dye designated DD . lost. As a result, it was confirmed that anisotropic D = 0.67 was reached and exhibits excellent liquid crystal orientation.

[Example 5]

)의 제조는 반응식 5와 같은 두 단계로 이루어졌다. Polyamide-based photoreactive copolymer P-IV (molar ratio y = 0.25, x = 0.75 in Scheme 5 below; n = 6 in formula 1, R ₁ =

) Was made in two steps as in Scheme 5.

Scheme 5

In the first step, the synthesis of poly (hydroxyethyl) aspartamide ( PHHA ) was carried out in the same manner as in Example 4. In the second step, the PHHA was modified with 4-{( E )-[4- (chlorocarbonyl) phenyl] diazenyl} phenyl ethyl carbonate; The molar ratio of each component was 1: 0.25. The reaction of these components was carried out in the same manner as the synthesis of P-IV (see Example 4). The yield of PV was about 60%. Mw: 135,000. Polymer PV was an amorphous orange powder. The chemical structure and degree of modification of the polymer PV was confirmed by NMR spectrum. Of P-IV Chemical shifts in the ¹ H NMR spectrum were as follows. ¹ H-NMR (ppm): 1.1 to 2.0 (16H), 2.4 to 2.7 (4H), 3.1 to 3.3 (4H), 3.5 to 3.6 (2H), 4.3 to 4.4 (2H), 4.5 to 5.0 (2H), 7.4-7.6 (2H), 7.8-8.2 (6H).

A thin film of PV on a quartz plate was obtained by spin coating of a chloroform solution and assembled into a light irradiation, sandwich structured cell and filled with nematic liquid crystals (MLC6816, Merck ) doped with a dichroic dye denoted by DD . As a result, it was confirmed that anisotropic D = 0.70 was shown and excellent liquid crystal alignability was shown.

Test Example 1: Anisotropy Measurement

In Examples 1 to 5 described above, the anisotropy was measured by the following method.

By the method described in each embodiment, a chloroform solution containing the photoreactive polymers PI to PV was applied to the substrate and polarized light to form an alignment layer, and a nematic liquid crystal (MLC6816) doped with a dichroic dye represented by DD . , ＂ Merck ＂) was used to form a liquid crystal cell.

DD

DD

Place a polarizer on the UV-vis spectrometer and measure A (parallel) and A (perpendicular) respectively, and measure DR = (A (∥) -A (⊥)) / (A (∥) + A (⊥)) Anisotropy was calculated according to the formula. In the measurement, the reference wavelength was 600 nm.

As a result, measurement results of A (parallel) and A (perpendicular) as shown in FIGS. 4A to 4E were derived for each example, and as described in each example, anisotropy of about 0.6 to 0.7 was obtained. It was confirmed that the. Accordingly, it was confirmed that the photoreactive polymers PI to PV of the examples exhibited excellent liquid crystal photoalignment.

Test Example  2: Orientation  And VHR  ( Voltage Holding Ratio ) Measure

N-methylpyrrolidone solutions of the photoreactive polymers P-I to P-V of Examples 1 to 5 were spin-coated onto a glass substrate patterned with two metal interconnections, respectively, to form an alignment film having a thickness of 100 nm. On the other hand, polarized UV was irradiated with the light quantity of about 1 J / cm <2>, and the upper and lower board | substrates were laminated using the sealant. At this time, after laminating the cell gap to about 4um, the IPS liquid crystal was filled between the cells using a capillary force. And it heat-processed for about 10 minutes at the temperature of 90 degreeC.

After the heat treatment, the degree of liquid crystal alignment was confirmed by measuring the black luminance. To this end, between the two polarized cross plates, the prepared cell was placed, and the luminance of the light passing through the 6000 cd / cm ² backlight was measured. If the luminance of the passed light is 0 ~ 2 cd / cm ² , the standard is 5, 2 ~ 4 cd / cm ² is 4, 4 ~ 6 cd / cm ² is 3, 6 ~ 10 cd / cm ² is 2, 10 to 20 cd / cm ² was set to 1, and 20 to 20 cd / cm ² or more. The higher the number, the better the black luminance and the better the liquid crystal alignment. And, VHR was measured at 60 Hz, 60 ° C.

The evaluation results for the orientation and VHR are shown in Table 1 below.

VHR Orientation Example 1 97.5 5 Example 2 96.8 5 Example 3 98 5 Example 4 98.2 5 Example 5 96.1 5

Referring to Table 1 above, it was confirmed that the photoreactive polymers P-I to P-V prepared in Examples exhibit excellent VHR with excellent liquid crystal photoalignment. Therefore, it was confirmed that the photoreactive polymer exhibits excellent orientation and electrical properties, and thus can be preferably used as a liquid crystal photoalignable polymer of display elements such as liquid crystal displays.

Claims (12)

A polyamide-based photoreactive polymer comprising a repeating unit of formula
[Formula 1]

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group.
The polyamide photoreactive polymer according to claim 1, wherein the photoreactive functional group R ₁ is selected from the group consisting of cinnamate-based functional groups of Formula 1a, coumarin-based functional groups of Formula 1b, and azo-based functional groups of Formula 1c.
[Formula 1a]

[Chemical Formula 1b]

[Chemical Formula 1c]

In Chemical Formulas 1a to 1c,
n1 is an integer of 0 to 4, n2 is an integer of 0 to 5,
A is substituted or unsubstituted alkylene having 1 to 20 carbon atoms, carbonyl, carboxy, substituted or unsubstituted arylene having 6 to 40 carbon atoms, or a simple bond,
B is a simple bond; Substituted or unsubstituted alkylene having 1 to 20 carbon atoms; Carbonyl; Carboxy; ester; Substituted or unsubstituted alkoxylene having 1 to 10 carbon atoms; Substituted or unsubstituted arylene having 6 to 40 carbon atoms; And substituted or unsubstituted heteroarylene having 6 to 40 carbon atoms,
X is oxygen or sulfur,
P is a simple bond; Substituted or unsubstituted alkylene having 1 to 20 carbon atoms; Carbonyl; Substituted or unsubstituted alkenylene having 2 to 20 carbon atoms; Substituted or unsubstituted cycloalkylene having 3 to 12 carbon atoms; Substituted or unsubstituted arylene having 6 to 40 carbon atoms; Substituted or unsubstituted aralkylene having 7 to 15 carbon atoms; Substituted or unsubstituted alkynylene having 2 to 20 carbon atoms; And substituted or unsubstituted cycloalkylene having 4 to 8 carbon atoms,
R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are the same as or different from each other, and each independently hydrogen; halogen; Substituted or unsubstituted alkyl having 1 to 20 carbon atoms; Substituted or unsubstituted cycloalkyl having 4 to 8 carbon atoms; Substituted or unsubstituted alkoxy having 1 to 20 carbon atoms; Substituted or unsubstituted aryloxy having 6 to 30 carbon atoms; Substituted or unsubstituted C6-C40 aryl; Heteroaryl having 6 to 40 carbon atoms, including group 14, 15 or 16 hetero elements; Substituted or unsubstituted alkoxyaryl having 6 to 40 carbon atoms; Nitrile; Nitro; And hydroxy.
The polyimide photoreactive polymer of claim 1, wherein the photoreactive functional group R ₁ is selected from the group consisting of:

The polyamide-based photoreactive polymer according to claim 1, which is a copolymer further comprising a repeating unit of formula (2):
(2)

Wherein l is 10 to 1000, n is 2 to 6, and R ₂ is hydrogen; Or substituted or unsubstituted alkyl having 1 to 20 carbon atoms.
The polyamide-based photoreactive polymer of claim 4, wherein the polyamide-based photoreactive polymer comprises a repeating unit of Formula 1: a repeating unit of Formula 2 at a molar ratio of 0.1: 0.9 to 0.9: 0.1.
The polyamide-based photoreactive polymer according to claim 1, having a weight average molecular weight of 15000 to 200000.
The polyamide-based photoreactive polymer according to claim 1, which exhibits photoreactivity under exposure of polarized light having a wavelength of 150 to 450 nm.
In the presence of a compound represented by R ₁ -O- (CH ₂ ) _n -NH ₂ , ring-opening the polysuccinimide containing a repeating unit of Formula 3 to form a repeating unit of Formula 1 A process for preparing the polyamide-based photoreactive polymer of claim 1
(3)

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group.
In the presence of a compound represented by HO— (CH ₂ ) _n —NH ₂ , ring-opening the polysuccinimide including the repeating unit of Formula 3 to form a repeating unit of Formula 3b; And
A method for preparing the polyamide-based photoreactive polymer of claim 1 comprising reacting at least a portion of the repeating unit of formula 3b with a compound represented by R ₁ -Cl to form the repeating unit of formula 1 above:
(3)

(3b)

Wherein m is 10 to 1000, n is 2 to 6, and R ₁ is a photoreactive functional group of a cinnamate functional group, an azo functional group or a coumarin functional group having a carbonyl group at the terminal bonded to chlorine (Cl). .
The method of claim 9, wherein R ₁ -Cl reacts with 10 to 90 mol% of the repeating unit of Formula 3b.
An alignment film comprising the photoreactive polymer of any one of claims 1 to 7.
 A display element comprising the alignment layer of claim 11.

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