Photoalignable polymeric material for forming a liquid crystal alignment film

Abstract

A photoalignable polymeric material for forming a liquid crystal alignment film comprises repeating units represented by formula (I), (I), wherein P1 is a divalent residue of a diamine HN2- Ar1-X1-NH2; and repeating units represented by formula (II), (II), wherein P2 is a divalent residue of a diamine HN2-Ar2-X2-Ar3-NH2; and wherein Q is a tetravalent residue of a cyclobutylene tetracarboxylic dianhydride Further provided is a process for producing the photoalignable polymeric material, a liquid crystal alignment film and a process for forming the film, as well as a liquid crystal alignment film optical device comprising the liquid crystal alignment film. The photoalignable polymeric material minimizes light leakage and improves the dark state of liquid crystal displays.

Description

[0001] Photoalignable Polymeric Material for Forming a Liquid Crystal Alignment Film

[0002] The present invention relates to a photoalignable polymeric material for forming a liquid crystal alignment film, a photoalignable polymeric material composition comprising the photoalignable polymeric material, a process for producing the photoalignable polymeric material, a process for forming a liquid crystal alignment film, a liquid crystal alignment film and an optical device comprising the liquid crystal alignment film.

[0003] Liquid crystal display devices provide displays by controlling the alignment direction of liquid crystal molecules contained in a liquid crystal layer disposed between two display substrates. In particular, the liquid crystal display generates an electric field by applying a voltage to electrodes arranged on liquid crystal layer side-surfaces of the substrates so as to realign liquid crystal molecules of the liquid crystal layer and thus control transmittance of light so as to display images.

[0004] In order to provide high-quality liquid crystal display devices, it is necessary for liquid crystal (LC) molecules to exhibit excellent initial alignment. The alignment of liquid crystal molecules significantly affects the display characteristics, including light leakage, response time and viewing angle.

[0005] The liquid crystal display device generally includes a liquid crystal alignment film for controlling the alignment direction of the liquid crystal molecules, which alignment film is arranged on the liquid crystal layer side-surface of the substrate. The alignment layer material in particular critically affects the orientation and homogeneity of the liquid crystal molecules.

[0006] Known alignment film materials include resins such as polyamic acids, polyimides, polyamides, polysiloxanes, polymaleimides and polyacrylates. For example, alignment films comprising polyamic acids and / or polyimides have been found to exhibit excellent physical properties such as heat resistance, compatibility with liquid crystals, and mechanical strength.

[0007] Rubbed polyimide films are still mainstream alignment layers for common liquid crystal displays. Polyimide is coated as a thin alignment film and dried. Then, the surface of the thin film is mechanically rubbed with a specifically manufactured cloth. Rubbing is, however, not appropriate for alignment over large areas.

[0008] In the photoalignment method, an alignment layer is given an alignment direction by irradiating a substrate coated with a photoalignment material with aligning light, especially linearly polarized UV light (LPUV). In polyimide-based photoalignment materials, exposure to the aligning light induces a partial decomposition of the polyimide main chain in a certain direction, thereby inducing an anisotropic angular distribution so as to achieve photoaligning properties.

[0009] In case of planar modes, such as IPS and FFS, the liquid crystal director in the dark state is oriented parallel or perpendicular to the polarization directions of the attached, normally crossed polarization films. Liquid crystal domains which are not perfectly aligned in the desired direction cause light leakage due to depolarization of the light. Hence, well-defined planar alignment of the liquid crystals on the alignment layers is crucial to achieve low dark state brightness for planar mode LCDs, in particular when operated in the normally black mode.

[0010] When applying a voltage to an LCD to switch it to a grey or bright state, the liquid crystal layer is deformed and again the alignment layer has to provide strong anchoring forces for the liquid crystals in order to drive them back to the initial off-state configuration, as soon as the applied voltage is below the threshold voltage of the LCD. Any deviation to the initial off-state configuration will be observed as image sticking and therefore display quality is reduced. Because an alternate current (AC) voltage is applied to switch the LCD to different grey levels, the image sticking, which occurs after the AC-voltage is changed or removed, is also referred to as AC-memory.

[0011] EP 2 527 916 A2 describes an alignment film material comprising a rigid polyimide and a flexible polyimide.

[0012] WO 2024 / 029576 A1 relates to a liquid crystal alignment film comprising a polyimide having repeating units derived from two different diamines, one of which is a diether compound.

[0013] It is desirable to provide improved alignment materials. In particular, it is desirable to provide alignment materials minimizing the light leakage of liquid crystal displays. In particular, it is an object of the invention to provide photo-alignment materials and photoalignment layers for planar LCD modes.

[0014] The present invention provides a photoalignable polymeric material for forming a liquid crystal alignment film, comprising repeating units represented by formula (I) wherein P1is a divalent residue of a diamine HN2-Ar1-X1-NH2; and repeating units represented by formula (II) wherein P2is a divalent residue of a diamine HN2-Ar2-X2-Ar3-NH2;

[0015] Ar1, Ar2and Ar3are independently selected from C3-Ci4-arylene, wherein Ar1, Ar2and Ar3may be independently substituted with one or more of OH, O-Ci-Ce-alkyl, Ci-Ce- alkyl, COOH, COO-Ci-Ce-alkyl and Ci-Ce-fluoroalkyl;

[0016] X1is independently selected from a bond, Ci-Ce-alkylene, O-Ci-Ce-alkylene, and NH-Ci-Ce-alkylene, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F;

[0017] X2is independently selected from a bond, O, NH, Ci-Ce-alkylene, O-Ci-Ce-alkylene, NH-Ci-C6-alkylene, NH-Ci-C6-alkylene-NH, NH-CO-(Ci-C6-alkylene), NH-CO-(CI-C6- alkylene)-CO-NH, CO-NH-(Ci-C6-alkylene), and CO-NH-(Ci-C6-alkylene)-NH-CO, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F;

[0018] Q is a tetravalent residue of a tetracarboxylic dianhydride, and at least a portion of Q is represented by the formula (A)

[0019] R1is independently selected from H and Ci-Ce-alkyl;

[0020] Y is independently selected from OH, O~M+and O-Ci-Ce-alkyl, wherein M+is an alkaline metal cation.

[0021] It has surprisingly been found that the photoalignable polymeric material allows for forming a liquid crystal alignment film inducing improved initial alignment of liquid crystals, and in particular of liquid crystal displays, thereby improving light leakage. The photoalignable polymeric material comprises repeating units represented by formulae (I) and (II), and thus constitutes a polyamic acid or a polyamic acid derivative, depending on the definition of moiety Y. Polyamic acids and polyamic acid derivatives may be subjected to thermal treatment so as to obtain a polyimide.

[0022] Polyimides derived from a cyclobutane tetracarboxylic acid dianhydride and a diamine may be subjected to UV-induced cleavage of the cyclobutane fragment, thereby inducing photoaligning properties of the polyimide. In particular, UV-polarized exposure produces an anisotropic angular distribution of broken and unreacted imide fragments due to the absorption dichroism of the photosensitive polyimide fragments.

[0023] As a result, anisotropy is induced in the alignment film. Liquid crystals contained in a layer formed on the alignment film may be aligned under the influence of such a photoinduced alignment film.

[0024] In the present photoalignable polymeric material, the repeating units represented by formula (I) comprise moiety P1, which is a divalent residue of a diamine HN2-Ar1-X1-NH2, whereas the repeating units represented by formula (II) comprise a moiety P2, which is a divalent residue of a diamine HN2-Ar2-X2-Ar3-NH2. The divalent residues P1and P2are each understood to be a residue equal to a diamine minus the two amino groups.

[0025] Without wishing to be bound by theory, it is believed that the advantageous properties of the photoalignable polymeric material derive from the simultaneous presence of both of the divalent residue of a diamine HN2-Ar1-X1-NH2 and the divalent residue of a diamine HN2-Ar2-X2-Ar3-NH2.

[0026] Ar1, Ar2and Ar3are independently selected from C3-Ci4-arylene, wherein Ar1, Ar2and Ar3may be independently substituted with one or more of OH, O-Ci-Ce-alkyl, Ci-Ce-alkyl, COOH, COO-Ci-Ce-alkyl and Ci-Ce-fluoroalkyl, in particular one or more Ci-Ce-alkyL

[0027] Herein, the term “independently selected” is understood to mean that a moiety is selected for each occurrence in a repeating unit and for each instance of a repeating unit, independently of its definition in other repeating units and independently of the definition of other such moieties.

[0028] Herein, each Ci-Ce-alkyl may be a branched or linear Ci-Ce-alkyl, preferably a C1-C3- alkyl, such as methyl or ethyl, in particular methyl.

[0029] In a preferred embodiment, Ar1, Ar2and Ar3are independently selected from phenylene and naphthylene, wherein Ar1, Ar2, Ar3may be independently substituted with one or more Ci-Cs-alkyL In a particularly preferred embodiment, Ar1is selected from phenylene and naphthylene; and Ar2and Ar3are phenylene.

[0030] X1is independently selected from a bond, Ci-Ce-alkylene, O-Ci-Ce-alkylene, and NH-Ci-Ce-alkylene, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F. In a preferred embodiment, X1is independently selected from a bond and Ci-Ce-alkylene. In a particularly preferred embodiment, X1is a bond.

[0031] Herein, each Ci-Ce-alkylene may be a branched or linear Ci-Ce-alkylene, preferably a Ci-C4-alkylene, such as methylene, ethylene, propylene or butylene, in particular ethylene or propylene, preferably ethylene.

[0032] X2is independently selected from a bond, O, NH, Ci-Ce-alkylene, O-Ci-Ce-alkylene, NH- Ci-C6-alkylene, NH-Ci-C6-alkylene-NH, NH-CO-(Ci-C6-alkylene), NH-CO-(CI-C6- alkylene)-CO-NH, CO-NH-(Ci-C6-alkylene), and CO-NH-(Ci-C6-alkylene)-NH-CO, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F. In a preferred embodiment, X2is independently selected from a bond, O, NH and Ci-Ce-alkylene.

[0033] In a preferred embodiment, Ar1, Ar2and Ar3are independently selected from phenylene and naphthylene; and X1and X2are each a bond; wherein Ar1, Ar2, Ar3may be independently substituted with one or more Ci-Cs-alkyL In a particularly preferred embodiment, Ar1is independently selected from phenylene and naphthylene; Ar2and Ar3are each phenylene; and X1and X2are each a bond; wherein Ar1, Ar2, Ar3may be independently substituted with one or more Ci-Cs-alkyL

[0034] Q is a tetravalent residue of a tetracarboxylic dianhydride, and at least a portion of Q is represented by the formula (A)

[0035] The tetravalent residue Q is understood to be a residue equal to a tetracarboxylic acid (underlying a tetracarboxylic dianhydride) minus the four carboxylic groups. R1is independently selected from H and Ci-Ce-alkyL In one embodiment, two moieties of R1are H and two moieties of R1are Ci-Ce-alkyL In a particularly preferred embodiment, two moieties of R1are H and two moieties of R1are Ci-Ce-alkyl, wherein the two Ci-Ce-alkyl moieties are arranged isolated from each other, i.e. , not vicinal.

[0036] Y is independently selected from OH, O~M+and O-Ci-Ce-alkyl, wherein M+is an alkaline metal cation, in particular selected from OH and O~M+. M+is preferably selected from a lithium cation, a sodium cation and a potassium cation, in particularly from a sodium cation and a potassium cation.

[0037] In one embodiment, the molar ratio of the repeating units of formula (I) to the repeating units of formula (II) is in the range of 1 : 100 to 100 : 1 , preferably 1 : 10 to 10 : 1 , more preferably 1 : 5 to 5 : 1 , most preferably 1 : 4 to 4 : 1 .

[0038] In one embodiment, a portion of Q is represented by the formula (B)

[0039] Herein, n is an integer independently selected from 0 and 1 .

[0040] In one embodiment, a portion of Q is represented by the formula (B-1 )

[0041] (B-1 ).

[0042] In one embodiment, the molar ratio of the portions of Q represented by the formula (A) to the portions of Q represented by the formula (B) is in the range of 1 : 10 to 10 : 1 , preferably 1 : 5 to 5 : 1 , more preferably 1 : 4 to 4 : 1 .

[0043] The invention in addition provides a photoalignable polymeric material composition comprising the photoalignable polymeric material and a polyamic acid and / or polyimide. Preferred is a photoalignable polymeric material composition wherein the polyamic acid and / or polyimide and the photoalignable polymeric material independently from each other comprise repeating units represented by of formula (II), which have the same meaning and preferences as described above.

[0044] Further preferred is a photoalignable polymeric material composition wherein the content of the photoalignable polymeric material is 90% by weight to 10% by weight, and the content of the polyamic acid and / or polyimide is 10% by weight to 90% by weight, provided that the sum total of the photoalignable polymeric material and the polyamic acid and / or polyimide is 100% by weight.

[0045] The invention further provides a photoalignable polymeric material composition comprising the photoalignable polymeric material or the photoalignable polymeric material composition and at least one solvent.

[0046] Suitable solvents include

[0047] (i) aprotic polar solvents such as N-methyl pyrrolidone; N-ethyl pyrrolidone; N-vinyl pyrrolidone; N,N-dimethyl formamide; N,N-dimethyl acetamide; 1 ,3-dimethyl-2- imidazolidinone; and dimethylsulfoxide;

[0048] (ii) esters such as methyl acetate; ethyl acetate; n-propyl acetate; isopropyl acetate; n-butyl acetate; isobutyl acetate; n-amyl acetate; isoamyl acetate; isopropyl propionate; n-butyl propionate; n-pentyl propionate; isobutylpropionate; isobutyl isobutyrate; 2-ethylhexylacetate; propylene glycol monomethyl ether acetate; propylene glycol monoethyl ether acetate; propylene glycol monobutyl ether acetate; 1 -methoxypropylacetate; 2-hydroxy ethyl acetate; 2-hydroxy ethyl propionate; 2-hydroxy-2-methyl ethyl propionate; cyclohexanol acetate; propylenglycol diacetate; dipropylenglycol methyl ether acetate; 1 ,4-butanediol diacetate; 1 ,6-hexanediol diacetate; butyl cellosolve acetate; ethyl lactate; n-propyl lactate; isopropyl lactate; methyl 3-methoxypropionate; methyl 3-ethoxypropionate; ethyl 3-methoxypropionate; and ethyl 3-ethoxypropionate;

[0049] (iii) lactones such as gamma-butyrolactone; and caprolactone;

[0050] (iv) ketones such as acetone; methyl ethyl ketone; methyl propyl ketone; methyl isobutyl ketone; 2-heptanone; 3-heptanone; 4-heptanone; methyl isoamyl ketone (2-methyl-5-hexanone); diisobutyl ketone; 5-methyl-3-heptanone; 2-octanone; isophorone; mesityl oxide; cyclohexanone; 3,3,5-trimethylcyclohexanione; and cyclopentanone;

[0051] (v) carbonates such as diethylcarbonate; dipropylcarbonate; and methylpropylcarbonate; (vi) glycols and glycol ethers such as ethylene glycol mono ethyl ether; ethylene glycol mono butyl ether; ethylene glycol mono hexyl ether; ethylene glycol mono isopropyl ether; ethylene glycol mono propyl ether; diethylene glycol mono ethyl ether; diethylene glycol mono butyl ether; diethylene glycol mono hexyl ether; diethylene glycol mono isopropyl ether; propylene glycol mono methyl ether; propylene glycol mono ethyl ether; propylene glycol mono propyl ether; propylene glycol mono butyl ether; dipropylene glycol mono methyl ether; dipropylene glycol mono butyl ether; ethylene glycol dimethyl ether; diethylene glycol dimethyl ether; diethylene glycol diethyl ether; propylene glycol dimethyl ether; dipropylene glycol dimethyl ether; and dipropylen glycol methyl n-propyl ether;

[0052] (vii) ethers such as anisole; tetrahydrofurane; 2-methyl tetrahydrofurane; dioxane; and methyl tert butyl ether;

[0053] (viii) nitriles such as acetonitrile; isovaleronitrile; and 2-methyl butyronitrile;

[0054] (ix) acetals such as ethylal (formaldehyde diethylacetal); propylal (formaldehyde di-n- propyl acetal); butylal (formaldehyde di-n-butyl acetal); 1 ,3-dioxolane; and 2,5,7, 10-tetraoxaundecane;

[0055] (x) alcohols such as isopropanol; iso-butanol; butanol; pentanol; iso-pentanol; cyclohexanol; n-hexanol; methyl iso-butyl-carbinol; 1 -methoxypropanol; 2-ethyl-1 - hexanol; and 2-methyl-1 -pentanol;

[0056] (xi) halogenated hydrocarbon solvents such as dichloromethane; 1 ,2-dichloroethane; 1 ,4-dichloro butane; trichloro ethane; chlorobenzene; o-dichlorobenzene; and a,a,a-trifluorotoluene;

[0057] (xii) hydrocarbons such as hexane; heptane; octane; nonane; decane; undecane; benzene; toluene; and xylene; and mixtures thereof.

[0058] The type and the proportion of solvents or solvent mixtures in the composition of the present invention mainly depends on the coating or printing methods used to prepare the liquid crystal alignment film or coating layer for the fabrication of optical and electro- optical elements and devices.

[0059] In addition, in order to improve the handling property, the coating quality or to adjust viscosity, the formulation may further include a polar protic or aprotic poor solvent or an apolar poor solvent. Examples of polar protic or aprotic poor solvents include acetals, alcohols, monoalkylated or dialkylated glycols, carboxylic acid esters preferably highly branched, alkoxy aliphatic-carboxylic acid ester, lactate, ketones preferably highly branched, ethers, carbonates, nitrile as long as the dissolved photoalignable polymeric material is not precipitated. Examples of apolar poor solvent hydrocarbons and halogenated hydrocarbon solvents, as long as the dissolved photoalignable polymeric material is not precipitated. Especially preferred polar protic or aprotic poor solvents include monoalkylated or dialkylated glycol ethers and alkoxy aliphatic carboxylic acid esters such as ethyl 3-ethoxy propionate.

[0060] In one embodiment, the photoalignable polymeric material composition has a solids content of 3.0 to 10.0% by weight, preferably 3.5 to 8.0% by weight, more preferably 4.0 to 7.0% by weight, most preferably 4.5 to 6.7% by weight. The solids comprise the photoalignable polymeric material, as well as additional polymeric materials. It is understood that the composition may comprise more than one photoalignable polymeric material.

[0061] Suitable photoalignable polymeric materials are well-known in the field of liquid crystal alignment materials. Such materials are used for the preparation of liquid crystal alignment films for the fabrication of optical and electro-optical devices, and are for instance disclosed in the following publications: O. Yaroshuk, Y. Renikov, J. Mater. Chem., 2012, 22, 286-300 and references cited therein; US 5,389,698; US 5,838,407; US 5,602,661 ; US 6,160,597; US 6,369,869; US 6,717,644; US 6,215,539; US 6,300,991 and US 6,608,661.

[0062] Further, the photoalignable polymeric material composition of the present invention may optionally comprise one or several additives. Such additives are generally used in minor amounts to improve certain performance criteria of the present composition, such as for instance coating and printing behaviour, storage stability and inhibition of colour formation as well as for instance improving the mechanical and thermal properties and the photoalignable properties of the alignment layer produced from the present composition.

[0063] The optional additives are commonly classified in groups such as antioxidants, inhibitors, stabilizers, surface active agents, flow improvers, defoaming agents, sensitizers, adhesion promoters, thixotropic agents, pigments, initiators, nucleating agents, clarifying agents, antistatic, slip agents, silica, talc, stabilizers, UV stabilizers, lubricants, coupling agents, antimicrobial agents, crosslinking agents, surfactants, photo-active agents, photo-sensitizers, photo generators and others.

[0064] Additives such as silane-containing compounds and epoxy-containing crosslinking agents may be added. Suitable silane-containing additives are described in Plast. Eng. 36 (1996), (Polyimides, fundamentals and applications), Marcel Dekker, Inc. Suitable epoxy-containing cross-linking additives include 4,4'-methylene-bis- (N , N-diglycidylaniline), trimethylolpropane triglycidyl ether, benzene-1 ,2,4,5- tetracarboxylic acid 1 ,2,4,5-N ,N'-diglycidyldiimide, polyethylene glycol diglycidyl ether, N,N-diglycidylcyclohexylamine, (3-glycidoxypropyl)triethoxysilane and N,N,N',N'- T etrakis(2-hyd roxyethyl )ad i pam i de .

[0065] Other suitable additives include 2,2-dimethoxyphenylethanone, a mixture of diphenylmethanone and N,N-dimethylbenzenamine or ethyl 4-(dimethylamino)benzoate, 1- hydroxy-cyclohexyl-phenyl-ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)- butanone-1 , lrgacure®500 (1 :1 mixture by weight of 1 -hydroxy-cyclohexyl-phenyl-ketone and benzophenone), 2,2-dimethoxy-1 ,2-diphenylethan-1-one or Michler’s ketone. Nonlimiting examples are hydroquinone, 2,6-di-tert-butyl-4-methylphenol (BHT), 4- ethoxyphenol, 4-methoxyphenol, phenothiazine, and N-phenyl-2-naphthylamine.

[0066] The amount of additives in the composition is generally less than 25% relative to the total weight of the photoalignable polymeric material, preferably less than 15% and more preferably less than 10%.

[0067] The invention moreover provides a process for producing a photoalignable polymeric material for forming a liquid crystal alignment film, comprising copolymerizing a mixture comprising a diamine of formula (1 ), a diamine of formula (2) and a cyclobutane tetracarboxylic acid dianhydride of formula (3) or a derivative thereof

[0068] HN2-Ar1-X1-NH2(1 )

[0069] HN2-Ar2-X2-Ar3-NH2(2) wherein

[0070] Ar1, Ar2and Ar3are independently selected from C3-Ci4-arylene, wherein Ar1, Ar2and Ar3may be independently substituted with one or more of OH, O-Ci-Ce-alkyl, Ci-Ce-alkyl, COOH, COO-Ci-Ce-alkyl and Ci-Ce-fluoroalkyl;

[0071] X1is independently selected from a bond, Ci-Ce-alkylene, O-Ci-Ce-alkylene, and NH-Ci-Ce-alkylene, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F; X2is independently selected from a bond, O, NH, Ci-Ce-alkylene, O-Ci-Ce-alkylene, NH-Ci-C6-alkylene, NH-Ci-C6-alkylene-NH, NH-CO-(Ci-C6-alkylene), NH-CO-(CI-C6- alkylene)-CO-NH, CO-NH-(Ci-C6-alkylene), and CO-NH-(Ci-C6-alkylene)-NH-CO, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F; and

[0072] R1is independently selected from H and Ci-Ce-alkyL

[0073] The embodiments discussed for the photoalignable polymeric material of the invention above are understood to also hold true for the process of the invention, where applicable.

[0074] In one embodiment, the molar ratio of the first diamine of formula (1 ) to the second diamine of formula (2) is in the range of 1 : 10 to 10 : 1 , preferably 1 : 10 to 5 : 1 , more preferably 1 : 5 to 2 : 1 , most preferably 1 : 4 to 2 : 1 .

[0075] In one embodiment, the mixture comprises a cyclopentane tetracarboxylic acid dianhydride of formula (4) or a derivative thereof

[0076] Herein, n is an integer independently selected from 0 and 1 .

[0077] In one embodiment, the molar ratio of the cyclobutane tetracarboxylic acid dianhydride of formula (3) and derivatives thereof to the cyclopentane tetracarboxylic acid dianhydride of formula (4) and derivatives thereof is in the range of 1 : 10 to 10 : 1 , preferably 1 : 5 to 5 : 1 , more preferably 1 : 4 to 4 : 1 .

[0078] Suitable diamines of formula (1 ) include

[0079] 1 .2-diaminobenzene;

[0080] 1 .3-diaminobenzene;

[0081] 1 .4-diaminobenzene;

[0082] 3-methyl-1 ,2-diaminobenzene;

[0083] 4-methyl-1 ,2-diaminobenzene;

[0084] 2-methyl-1 ,3-diaminobenzene; 4-methyl-1 ,3-diaminobenzene;

[0085] 5-methyl-1 ,3-diaminobenzene;hk

[0086] 2-methyl-1 ,4-diaminobenzene;

[0087] 2.5-dimethyl-1 ,4-diaminobenzene;

[0088] 4-(2-aminoethyl)aniline;

[0089] 1 .5-diaminonaphthalene; and

[0090] 1 ,8-diaminonaphthalene.

[0091] Preferred diamines of formula (1) include

[0092] 1 .2-diaminobenzene;

[0093] 1 .3-diaminobenzene;

[0094] 1 .4-diaminobenzene;

[0095] 4-methyl-1 ,2-diaminobenzene;

[0096] 2-methyl-1 ,3-diaminobenzene;

[0097] 4-methyl-1 ,3-diaminobenzene;

[0098] 2.5-dimethyl-1 ,4-diaminobenzene;

[0099] 4-(2-aminoethyl)aniline; and

[0100] 1 .5-diaminonaphthalene.

[0101] It is understood that the divalent diamine residue P1in the repeating units represented by formula (I) in the photoalignable polymeric material of the invention is derivable from a diamine of formula (1).

[0102] Suitable diamines of formula (2) include

[0103] 4,4'-methylenedianiline;

[0104] 3,3'-methylenedianiline;

[0105] 3,4'-methylenedianiline;

[0106] 4,4'-ethylenedianiline;

[0107] 4,4'-diamino-2,2'-dimethylbiphenyl;

[0108] 4,4'-diamino-3,3'-dimethylbiphenyl;

[0109] 4,4'-oxydianiline;

[0110] 3,4'-oxydianiline; N-(4-aminophenyl)benzene-1 ,4-diamine;

[0111] N-(4-aminophenyl)benzene-1 ,3-diamine;

[0112] 2.2-bis(4-aminophenyl)hexafluoropropane;

[0113] 2-amino-4-[1-(3-amino-4-hydroxy-phenyl)-1-methyl-ethyl]phenol;

[0114] 4-[4-amino-2-(trifluoromethyl)phenyl]-3-(trifluoromethyl)aniline;

[0115] 4-[(4-amino-2-methyl-phenyl)methyl]-2-methyl-aniline;

[0116] 4,4'-methylene-bis(2-chloroaniline); and bis(4-aminophenoxy)-2,2-dimethylpropane

[0117] Preferred diamines of formula (2) include

[0118] 4,4'-diamino-2,2'-dimethylbiphenyl;

[0119] 4-[(4-amino-2-methyl-phenyl)methyl]-2-methyl-aniline;

[0120] N-(4-aminophenyl)benzene-1 ,4-diamine; and

[0121] 4,4'-oxydianiline.

[0122] It is understood that the divalent diamine residue P2in the repeating units represented by formula (II) in the photoalignable polymeric material of the invention is derivable from a diamine of formula (2).

[0123] Suitable cyclobutane tetracarboxylic dianhydrides of formula (3) include:

[0124] 1 .2.3.4-cyclobutanetetracarboxylic dianhydride (4,9-dioxatricyclo[5.3.0.02’6]decane- 3,5,8,10-tetrone, CBDA);

[0125] 1 .3-dimethyl-1 ,2,3,4-cyclobutanetetracarboxylic dianhydride (1 ,6-dimethyl-4,9- dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone, DM-CBDA); and

[0126] 1 .2.3.4-tetramethyl-1 ,2,3,4-cyclobutanetetracarboxylic dianhydride.

[0127] Preferred cyclobutane tetracarboxylic dianhydrides of formula (3) include:

[0128] 1 .2.3.4-cyclobutanetetracarboxylic dianhydride (4,9-dioxatricyclo[5.3.0.02’6]decane- 3,5,8,10-tetrone, CBDA); and

[0129] 1 ,3-dimethyl-1 ,2,3,4-cyclobutanetetracarboxylic dianhydride (1 ,6-dimethyl-4,9- dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone, DM-CBDA).

[0130] Derivatives of cyclobutane tetracarboxylic acid dianhydrides of formula (3) include acids, Ci-Ce-esters and acid chlorides thereof. It is understood that the portion (A) of tetravalent organic residue Q in the repeating units (I) and (II) is derivable from cyclobutane tetracarboxylic acid dianhydrides of formula (3) and derivatives thereof.

[0131] Suitable cyclopentane tetracarboxylic dianhydrides of formula (4) include

[0132] 1 ,2,3,4-cyclopentanetetracarboxylic dianhydride and 3-(carboxymethyl)-1 ,2,4- cyclopentanetricarboxylic acid 1 ,4:2,3-dianhydride (TCA-AH).

[0133] Derivatives of cyclopentane tetracarboxylic acid dianhydrides of formula (4) include acids, Ci-Ce-esters and acid chlorides thereof.

[0134] It is understood that the optional portion (B) of tetravalent organic residue Q in the repeating units (I) and (II) is derivable from cyclopentane tetracarboxylic acid dianhydrides of formula (4) and derivatives thereof.

[0135] The photoalignable polymeric materials may be prepared in accordance with methods know to the person skilled in the art, e.g., by methods described in Plast. Eng. 36 (1996), “Polyimides, Fundamentals and Application”, Marcel Dekker, Inc.

[0136] The invention further relates to a process for forming a liquid crystal alignment film, comprising:

[0137] - applying a photoalignable polymeric material of the invention, or a photoalignable polymeric material as obtained according to a process of the invention, onto a substrate;

[0138] - drying the wet film thus obtained, and

[0139] - irradiating the dried film to impart liquid crystal alignment capability.

[0140] The substrate may be transparent or non-transparent, and is preferably selected from glass and plastic substrates, polymer films, such as polyethyleneterephthalat (PET), triacetyl cellulose (TAG), polypropylen, optionally coated with indium tin oxide (ITO). In particular, the composition may be applied to a support optionally coated with an electrode, for example a glass plate coated with indium-tin oxide (ITO), so that homogeneous layers of 0.005 to 50 pm thickness are produced, preferably 0.025 to 1 .00 pm, more preferably 0.050 to 0.200 pm.

[0141] The composition may be applied onto the substrate by general coating and printing methods known in the art. Coating methods are for example spin coating, blade coating, knife coating, reverse-roll coating, transfer roll coating, gravure roll coating, kiss roll coating, cast coating, spray coating, slot-orifice coating, calendar coating, electrodepositing coating, dip coating or die coating. Printing methods include relief printing such as flexographic printing, inkjet printing, intaglio printing such as direct gravure printing or offset gravure printing, lithographic printing such as offset printing, or stencil printing such as screen printing. Preferred printing methods are offset printing and inkjet printing.

[0142] After applying the composition onto the substrate, the wet film is dried and the regions to be oriented are irradiated, for example, with a high-pressure mercury vapour lamp, a xenon lamp or a pulsed UV laser, using a polarizer and optionally a mask for creating images of structures.

[0143] The process suitably comprises a heat treatment step of the dried film at a temperature in the range of 80 to 230 °C. The heat treatment step allows for converting most or all of the polyamic acid groups to polyimide groups. The thus obtained polyimide film exhibits excellent physical properties such as heat resistance, compatibility with liquid crystals, and mechanical strength.

[0144] In one embodiment, aligning light is used. Preferably, the wavelengths are in the UV-A, UVB and / or UV / C-range, or in the visible range. Appropriate wavelengths may be in the range of 100 to 350 nm, preferably 100 to 280 nm. The instant direction of the aligning light may be normal to the substrate or at any oblique angle. The irradiation with aligning light may be conducted in a single step or in several separate steps. In a preferred embodiment of the invention the treatment with aligning light is conducted in a single step.

[0145] More preferably, aligning light is at least partially linearly polarized, elli ptically polarized, such as for example circularly polarized, or non-polarized; most preferably at least circularly or partially linearly polarized light, or non-polarized light exposed obliquely. Especially, most preferred aligning light denotes substantially polarised light, especially linearly polarised light.

[0146] Polarised light direction is understood to mean the intersection line of the alignment layer surface and the plane of polarization of the polarised light during the exposure. If the polarised light is elliptically polarized, the plane of polarization shall mean the plane defined by the incident direction of the light and by the major axis of the polarization ellipse.

[0147] The term polarised light direction is used in the context of the present invention not only to describe a direction for the duration of the exposure process, but also after exposure to refer to the direction of the polarised light on the alignment layer as it was applied during exposure.

[0148] The irradiation time is dependent upon the output of the individual lamps and can vary from a few seconds to several hours. Irradiation of the homogeneous layer can also be performed using filters that, for example, allow only certain wavelengths to pass, e.g., wavelengths suitable for inducing retro-cycloaddition [2+2],

[0149] The invention further relates to a liquid crystal alignment film obtained by the process of the invention.

[0150] The invention moreover relates to an optical device comprising the liquid crystal alignment film of the invention. Optical devices are understood to include structured or unstructured optical and electro-optical elements and devices comprising the liquid crystal alignment film obtained by the process of the invention. Examples of structured or unstructured optical and electro-optical elements and devices include optical films, retarders, liquid-crystal displays (LCD), organic field-effect transistors (OFET), organic light-emitting diodes (OLED), smart windows and sensors.

[0151] The invention is described in more detail by the subsequent examples.

[0152] Polyamic acids and alignment formulations thereof were prepared. The alignment formulations were subjected to testing.

[0153] Method A: Intrinsic Viscosity

[0154] The intrinsic viscosity of the polyamic acids was determined via an Ubbelohde viscosimeter consisting consists of a capillary tube through which a sample flows under the influence of gravity. The time (t) in which a certain volume passes through the capillary tube is measured, and the intrinsic viscosity ([qintr] = [dL / g]) is calculated.

[0155] Method B: Alignment Quality

[0156] The alignment quality of cells obtained from the alignment formulations was quantified by evaluating the output ellipticity ratio of each cell on a polarized optical microscope (POM) between polarizer and analyzer. The cell is illuminated with linearly polarizer white light with the polarization parallel to in-plane optical axis. Using a photomultiplier as a voltage, the maximum intensity “a” when the analyzer is parallel to the polarizer and the minimum intensity “b” when the analyzer is perpendicular to the polarizer are measured. The light leakage factor is calculated by the formula a / b. The alignment quality is defined to be excellent for a value of a / b of more than 3500, good for a value of a / b between more than 2500 and 3500, medium for a value of a / b between more than 1500 and 2500, and bad for a value of a / b below or equal to 1500.

[0157] Examples

[0158] In the following, the abbreviation NMP relates to 1-methyl-2-pyrrolidone (CAS: 872-50-4). The abbreviation BC relates to 2-butoxyethanol (Butyl CELLOSOLOVE, (CAS: 11-76-2).

[0159] The following compounds were used for obtaining the polymers of the examples:

[0160] A1 1 ,3-diaminobenzene

[0161] A2 1 ,2-diaminobenzene

[0162] A3 4-methyl-1 ,2-diaminobenzene

[0163] A4 2-methyl-1 ,3-diaminobenzene

[0164] A5 4-methyl-1 ,3-diaminobenzene

[0165] A6 1 ,4-diaminobenzene

[0166] A7 2,5-dimethyl-1 ,4-diaminobenzene

[0167] A8 1 ,5-diaminonaphthalene

[0168] A9 4-(2-aminoethyl)aniline

[0169] B1 4,4'-diamino-2,2'-dimethylbiphenyl

[0170] B2 4-[(4-amino-2-methyl-phenyl)methyl]-2-methyl-aniline

[0171] B3 N-(4-aminophenyl)benzene-1 ,4-diamine

[0172] B4 4,4'-oxydianiline

[0173] B5 4-[2-(4-aminophenoxy)ethoxy]aniline

[0174] C1 1 ,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA)

[0175] C2 1 ,3-dimethyl-1 ,2,3,4-cyclobutanetetracarboxylic dianhydride (DM-CBDA)

[0176] Comparative Example 1 : Preparation of polyamic acid CP1 and corresponding alignment formulation CF1

[0177] 1813 mg (9.247 mmol) of 4,9-dioxatricyclo[5.3.0.02,6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 1000 mg (9.247 mmol) of benzene-1 ,3-diamine in 11254 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP1 was obtained with an intrinsic viscosity qintr of 0.34 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF1 . Comparative Example 2: Preparation of polyamic acid CP2 and corresponding alignment formulation CF2

[0178] 2073 mg (9.247 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 1000 mg (9.247 mmol) of benzene-1 ,3- diamine in 12292 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP2 was obtained with an intrinsic viscosity qintr of 0.43 dL / g. To 2500 mg of this 20 wt.-% NMP- solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF2.

[0179] Comparative Example 3: Preparation of polyamic acid CP3 and corresponding alignment formulation CF3

[0180] 924 mg (4.711 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl- aniline in 7695 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP3 was obtained with an intrinsic viscosity qintr of 0.52 dL / g. To 2500 mg of this 20 wt.-% NMP- solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF3.

[0181] Comparative Example 4: Preparation of polyamic acid CP4 and corresponding alignment formulation CF4

[0182] 2112 mg (9.421 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0. 02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 2000 mg (9.421 mmol) of 4-(4-amino-2- methyl-phenyl)-3-methyl-aniline in 16448 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP4 was obtained with an intrinsic viscosity qintr of 0.74 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF4.

[0183] Example 1 : Preparation of polyamic acid P1 and corresponding alignment formulation F1

[0184] 1232 mg (6.281 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 170 mg (1 .570 mmol) of benzene-1 ,3-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 11254 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P1 was obtained with an intrinsic viscosity qintr of 0.63 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F1 .

[0185] Example 2: Preparation of polyamic acid P2 and corresponding alignment formulation F2 1.848 mg (9.421 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 509 mg (4.711 mmol) of benzene-1 ,3-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 13428 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P2 was obtained with an intrinsic viscosity qintr of 0.41 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F2.

[0186] Example 3: Preparation of polyamic acid P3 and corresponding alignment formulation F3

[0187] 1408 mg (6.281 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 170 mg (1 .570 mmol) of benzene-1 ,3-diamine and 1000 mg (4.711 mmol) of4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 10311 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P3 was obtained with an intrinsic viscosity qintr of 0.53 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F3.

[0188] Example 4: Preparation of polyamic acid P4 and corresponding alignment formulation F4

[0189] 2112 mg (9.421 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 509 mg (4.711 mmol) of benzene-1 ,3-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 14485 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P4 was obtained with an intrinsic viscosity r|jntr of 0.39 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F4.

[0190] Example 5: Preparation of polyamic acid P5 and corresponding alignment formulation F5

[0191] A mixture of 907 mg (4.624 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone and 3109 mg (13.871 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 500 mg (4.624 mmol) of benzene-1 ,3-diamine and 2945 mg (13.871 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 29843 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P5 was obtained with an intrinsic viscosity qintr of 0.55 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F5.

[0192] Example 6: Preparation of polyamic acid P6 and corresponding alignment formulation F6

[0193] A mixture of 453 mg (2.312 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone and 1555 mg (6.935 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 500 mg (4.624 mmol) of benzene-1 ,3-diamine and 982 mg (4.624 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 13959 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P6 was obtained with an intrinsic viscosity qintr of 0.46 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F6.

[0194] Example 7: Preparation of polyamic acid P7 and corresponding alignment formulation F7 1232 mg (6.281 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 170 mg (1 .570 mmol) of benzene-1 ,2-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 11254 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P7 was obtained with an intrinsic viscosity qintr of 0.43 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F7.

[0195] Example 8: Preparation of polyamic acid P8 and corresponding alignment formulation F8 1.848 mg (9.421 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 509 mg (4.711 mmol) of benzene-1 ,2-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 13428 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P8 was obtained with an intrinsic viscosity qintr of 0.23 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F8.

[0196] Example 9: Preparation of polyamic acid P9 and corresponding alignment formulation F9 1408 mg (6.281 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 170 mg (1 .570 mmol) of benzene-1 ,2-diamine and 1000 mg (4.711 mmol) of4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 10311 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P9 was obtained with an intrinsic viscosity qintr of 0.38 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F9.

[0197] Example 10: Preparation of polyamic acid P10 and corresponding alignment formulation F10

[0198] 1605 mg (8.185 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene-1 ,2-diamine and 1303 mg (6.139 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 12634 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P10 was obtained with an intrinsic viscosity qintr of 0.42 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F10. Example 11 : Preparation of polyamic acid P11 and corresponding alignment formulation F11

[0199] 803 mg (4.093 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene-1 ,2-diamine and 434 mg (2.046 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 5948 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P11 was obtained with an intrinsic viscosity qintr of 0.40 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F11 .

[0200] Example 12: Preparation of polyamic acid P12 and corresponding alignment formulation F12

[0201] 1835 mg (8.185 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene- 1 ,2-diamine and 1303 mg (6.139 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 13553 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P12 was obtained with an intrinsic viscosity qintr of 0.69 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F12.

[0202] Example 13: Preparation of polyamic acid P13 and corresponding alignment formulation F13

[0203] 917 mg (4.093 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene- 1 ,2-diamine and 434 mg (2.046 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 6407 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P13 was obtained with an intrinsic viscosity qintr of 0.43 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F13. Example 14: Preparation of polyamic acid P14 and corresponding alignment formulation F14

[0204] 1605 mg (8.185 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 2-methylbenzene-1 ,3-diamine and 1303 mg (6.139 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 12634 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P14 was obtained with an intrinsic viscosity qintr of 0.58 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F14.

[0205] Example 15: Preparation of polyamic acid P15 and corresponding alignment formulation F15

[0206] 803 mg (4.093 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 2-methylbenzene-1 ,3-diamine and 434 mg (2.046 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 5948 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P15 was obtained with an intrinsic viscosity qintr of 0.42 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F15.

[0207] Example 16: Preparation of polyamic acid P16 and corresponding alignment formulation F16

[0208] 1835 mg (8.185 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 2-methylbenzene- 1 ,3-diamine and 1303 mg (6.139 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 13553 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P16 was obtained with an intrinsic viscosity qintr of 0.49 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F16. Example 17: Preparation of polyamic acid P17 and corresponding alignment formulation F17

[0209] 917 mg (4.093 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 2-methylbenzene- 1 ,3-diamine and 434 mg (2.046 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 6407 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P17 was obtained with an intrinsic viscosity qintr of 0.38 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F17.

[0210] Example 18: Preparation of polyamic acid P18 and corresponding alignment formulation F18

[0211] 1605 mg (8.185 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene-1 ,3-diamine and 1303 mg (6.139 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 12634 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P18 was obtained with an intrinsic viscosity qintr of 0.79 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F18.

[0212] Example 19: Preparation of polyamic acid P19 and corresponding alignment formulation F19

[0213] 803 mg (4.093 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene-1 ,3-diamine and 434 mg (2.046 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 5948 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P19 was obtained with an intrinsic viscosity qintr of 0.40 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F19. Example 20: Preparation of polyamic acid P20 and corresponding alignment formulation F20

[0214] 1835 mg (8.185 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene- 1 ,3-diamine and 1303 mg (6.139 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 13553 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P20 was obtained with an intrinsic viscosity qintr of 0.59 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F20.

[0215] Example 21 : Preparation of polyamic acid P21 and corresponding alignment formulation F21

[0216] 917 mg (4.093 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (2.046 mmol) of 4-methylbenzene- 1 ,3-diamine and 434 mg (2.046 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 6407 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P21 was obtained with an intrinsic viscosity qintr of 0.44 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F21 .

[0217] Example 22: Preparation of polyamic acid P22 and corresponding alignment formulation F22

[0218] 1232 mg (6.281 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 170 mg (1 .570 mmol) of benzene-1 ,4-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 11254 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P22 was obtained with an intrinsic viscosity qintr of 0.50 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F22. Example 23: Preparation of polyamic acid P23 and corresponding alignment formulation F23

[0219] 1.848 mg (9.421 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 509 mg (4.711 mmol) of benzene-1 ,4-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 13428 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P23 was obtained with an intrinsic viscosity qintr of 0.41 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F23.

[0220] Example 24: Preparation of polyamic acid P24 and corresponding alignment formulation F24

[0221] 1408 mg (6.281 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 170 mg (1 .570 mmol) of benzene- 1 ,4-diamine and 1000 mg (4.711 mmol) of4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 10311 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P24 was obtained with an intrinsic viscosity qintr of 0.53 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F24.

[0222] Example 25: Preparation of polyamic acid P25 and corresponding alignment formulation F25

[0223] A mixture of 907 mg (4.624 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone and 3109 mg (13.871 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 500 mg (4.624 mmol) of benzene-1 ,4-diamine and 2945 mg (13.871 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 29843 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P25 was obtained with an intrinsic viscosity qintr of 0.63 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F25. Example 26: Preparation of polyamic acid P26 and corresponding alignment formulation F26

[0224] 1440 mg (7.343 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (1.836 mmol) of 2,5-dimethylbenzene-1 ,4-diamine and 1169 mg (5.507 mmol) of4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 11436 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P26 was obtained with an intrinsic viscosity qintr of 0.59 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F26.

[0225] Example 27: Preparation of polyamic acid P27 and corresponding alignment formulation F27

[0226] 1646 mg (7.343 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (1 .836 mmol) of 2,5-dimethylbenzene- 1 ,4-diamine and 1169 mg (7.343 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 12260 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P27 was obtained with an intrinsic viscosity qintr of 0.68 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F27.

[0227] Example 28: Preparation of polyamic acid P28 and corresponding alignment formulation F28

[0228] 823 mg (3.671 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 250 mg (1 .836 mmol) of 2,5-dimethylbenzene- 1 ,4-diamine and 390 mg (1.836 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 5851 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P28 was obtained with an intrinsic viscosity qintr of 0.62 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F28. Example 29: Preparation of polyamic acid P29 and corresponding alignment formulation F29

[0229] 1232 mg (6.281 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 248 mg (1.570 mmol) of naphthalene-1 ,5-diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 9920 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P29 was obtained with an intrinsic viscosity qintr of 0.51 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F29.

[0230] Example 30: Preparation of polyamic acid P30 and corresponding alignment formulation F30

[0231] 1408 mg (6.281 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 248 mg (1 .570 mmol) of naphthalene-1 ,5- diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 10625 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P30 was obtained with an intrinsic viscosity qintr of 0.47 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F30.

[0232] Example 31 : Preparation of polyamic acid P31 and corresponding alignment formulation F31

[0233] 2112 mg (9.421 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 745 mg (4.711 mmol) of naphthalene-1 ,5- diamine and 1000 mg (4.711 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 15.429 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P31 was obtained with an intrinsic viscosity qintr of 0.45 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F31 . Example 32: Preparation of cell with F1 and alignment quality quantification

[0234] Formulation F1 was spin-coated onto two ITO coated glass substrates at a spin speed of c.a. 2500 rpm for 30 seconds. After spin-coating, the substrates were subjected to a baking procedure consisting of pre-baking for 130 seconds at 120 °C and baking for 30 min at 230 °C. Then, the substrates were exposed to linearly polarized light at an incidence angle of 0° relative to the normal of the substrate surface (500 mJ -cm-2- LPUVC). The substrates were subjected to a post-baking for 30 min at 230 °C. The cells were fabricated by assembling the 2 substrates, the exposed polymer layers facing the inside of the cell. The substrates were adjusted relative to each other such that the induced alignment directions were parallel to each other. The cells were capillary filled with liquid crystal with following properties: TS^N <40 °C, TN^I =80 °C, An (589 nnm, 25 °C) = 0.103 and As (1 kHz, 25 °C) = 10.1 , K11 (25 °C) = 11.6, K11 (25 °C) = 6.9, K33 (25 °C) = 14.7. Finally, the filled cells were further subjected to a thermal annealing at 90 °C for 30 min, thereby completing the cell assembling process. The alignment quality of the resulting cell was quantified by the method described above.

[0235] The liquid crystal in the cell prepared using F1 showed well defined and homogeneous planar orientation before and after thermal annealing of the cell. A tilt angle of below 1 ° was measured using the rotating analyser method from Shintech and an excellent light leakage factor was measured.

[0236] Comparative Example 5: Preparation of cell with CF 1 and alignment quality quantification Cell was prepared as in Example 32 with F1 , except that formulation CF1 was coated. The liquid crystal in the cell showed bad orientation before thermal annealing and planar orientation after thermal annealing of the cell. A tilt angle of below 1 ° was measured using the rotating analyser method from Shintech and a bad light leakage factor was measured.

[0237] Example 33: Preparation of cells with CF2 to CF4 and F2 to F31 and alignment quality comparison

[0238] Cell was prepared as in Example 32, except that formulation CF2 to CF4 and F2 to F31 were coated. A tilt angle of below 1 ° was measured for all cells using the rotating analyser method from Shintech and the alignment quality was measured and the results are shown in the following Table 1 . Table 1 Comparative Example 6: Preparation of polyamic acid CP5 and corresponding alignment formulation CF5

[0239] 867 mg (4.419 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 1000 mg (4.419 mmol) of 4-[(4-amino-2-methyl-phenyl)methyl]-2- methyl-aniline in 7466 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP5 was obtained with an intrinsic viscosity qintr of 0.48 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF5.

[0240] Comparative Example 7: Preparation of polyamic acid CP6 and corresponding alignment formulation CF6

[0241] 991 mg (4.419 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 1000 mg (4.419 mmol) of 4-[(4-amino-2- methyl-phenyl)methyl]-2-methyl-aniline in 7962 mg of NMP. After 2 h at O °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP6 was obtained with an intrinsic viscosity qintr of 0.42 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF6.

[0242] Comparative Example 8: Preparation of polyamic acid CP7 and corresponding alignment formulation CF7

[0243] 1125 mg (5.019 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 1000 mg (5.019 mmol) of 4-[(4-amino-2- methyl-phenyl)methyl]-2-methyl-aniline in 8500 mg of NMP. After 2 h at O °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP7 was obtained with an intrinsic viscosity qintr of 0.73 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF7.

[0244] Comparative Example 9: Preparation of polyamic acid CP8 and corresponding alignment formulation CF8

[0245] 984 mg (5.019 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 500 mg (2.509 mmol) of N 1 -(4-aminophenyl)benzene-1 ,4-diamine and 502 mg (2.509 mmol) of 4-(4-aminophenoxy)aniline in 7947 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP8 was obtained with an intrinsic viscosity qintr of 0.42 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF8.

[0246] Comparative Example 10: Preparation of polyamic acid CP9 and corresponding alignment formulation CF9

[0247] 984 mg (5.019 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 500 mg (2.509 mmol) of N 1 -(4-aminophenyl)benzene-1 ,4-diamine and 533 mg (2.509 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 8068 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP9 was obtained with an intrinsic viscosity qintr of 0.74 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF9.

[0248] Example 34: Preparation of polyamic acid P32 and corresponding alignment formulation F32

[0249] 1813 mg (9.247 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.312 mmol) of benzene-1 ,3-diamine and 1382 mg (6.935 mmol) of 4 N1-(4-aminophenyl)benzene-1 ,4-diamine in 13781 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P32 was obtained with an intrinsic viscosity qintr of 0.55 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F32.

[0250] Example 35: Preparation of polyamic acid P33 and corresponding alignment formulation F33

[0251] 907 mg (4.624 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 250 mg (2.312 mmol) of benzene-1 ,3-diamine and 461 mg (2.312 mmol) of 4 N1-(4-aminophenyl)benzene-1 ,4-diamine in 8087 mg of NMP. After 2 h at O °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P33 was obtained with an intrinsic viscosity qintr of 0.51 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F33.

[0252] Comparative Example 11 : Preparation of polyamic acid CP10 and corresponding alignment formulation CF10

[0253] 1120 mg (4.994 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 1000 mg (4.994 mmol) of 4-(4- aminophenoxy)aniline in 8478 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP10 was obtained with an intrinsic viscosity qintr of 0.45 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF10.

[0254] Example 36: Preparation of polyamic acid P34 and corresponding alignment formulation F34

[0255] 1306 mg (6.659 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 263 mg (1.665 mmol) of naphthalene-1 ,5-diamine and 1000 mg (4.994 mmol) of 4-(4-aminophenoxy)aniline in 10277 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P34 was obtained with an intrinsic viscosity qintr of 0.47 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F34.

[0256] Example 37: Preparation of polyamic acid P35 and corresponding alignment formulation F35

[0257] 1959 mg (9.988 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 790 mg (4.994 mmol) of naphthalene-1 ,5-diamine and 1000 mg (4.994 mmol) of 4-(4-aminophenoxy)aniline in 14995 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P35 is with an intrinsic viscosity qintr of 0.46 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F35. Example 38: Preparation of polyamic acid P36 and corresponding alignment formulation F36

[0258] 1679 mg (7.491 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 593 mg (3.746 mmol) of naphthalene-1 ,5- diamine and 593 mg (3.746 mmol) of 4-(4-aminophenoxy)aniline in 12087 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P36 was obtained with an intrinsic viscosity qintr of 0.24 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filterto give the alignment formulation F36.

[0259] Example 39: Preparation of cells with CF5 to CF10 and F32 to F36 and alignment quality comparison

[0260] Cell was prepared as in Example 32, except that formulation CF5 to CF10 and F32 to F36 were coated. The alignment quality was measured for each cell and the results are shown in the following Table 2.

[0261] Table 2

[0262] Comparative Example 12: Preparation of polyamic acid CP11 and corresponding alignment formulation CF11

[0263] 1440 mg (7.343 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 1000 mg (7.343 mmol) of 4-(2-aminoethyl)aniline in 9760 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP11 was obtained with an intrinsic viscosity F|intr of 0.48 dL / g. To 2500 mg of this 20 wt.-% NMP- solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF11 .

[0264] Comparative Example 13: Preparation of polyamic acid CP12 and corresponding alignment formulation CF12

[0265] 1646 mg (7.343 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 1000 mg (7.343 mmol) of 4-(2- aminoethyl)aniline in 10584 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP12 was obtained with an intrinsic viscosity qintr of 0.62 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF12.

[0266] Example 40: Preparation of polyamic acid P37 and corresponding alignment formulation F37

[0267] 1440 mg (7.343 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 500 mg (3.671 mmol) of 4-(2-aminoethyl)aniline and 779 mg (3.671 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl-aniline in 10877 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P37 was obtained with an intrinsic viscosity qintr of 0.82 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F37.

[0268] Example 41 : Preparation of polyamic acid P38 and corresponding alignment formulation F38

[0269] 1646 mg 7.343 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 500 mg (3.671 mmol) of 4-(2- aminoethyl)aniline and 779 mg (3.671 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl- aniline in 11702 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P38 was obtained with an intrinsic viscosity qintr of 0.81 dL / g. To 2500 mg of this 20 wt.-% NMP- solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F38.

[0270] Example 42: Preparation of polyamic acid P39 and corresponding alignment formulation F39

[0271] A mixture of 720 mg (3.671 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone and 2469 mg (11.014 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone were added at 0 °C to a solution of 1000 mg (7.343 mmol) of 4-(2- aminoethyl)aniline and 1559 mg (7.343 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl- aniline in 22991 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P39 was obtained with an intrinsic viscosity qintr of 0.57 dL / g. To 2500 mg of this 20 wt.-% NMP- solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F39.

[0272] Example 43: Preparation of polyamic acid P40 and corresponding alignment formulation F40

[0273] A mixture of 1440 mg (7.343 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10- tetrone and 1646 mg (7.343 mmol) of 1 ,6-dimethyl-4,9-dioxatricyclo[5.3.0.02’6]decane- 3,5,8,10-tetrone were added at 0 °C to a solution of 1000 mg (7.343 mmol) of 4-(2- aminoethyl)aniline and 1559 mg (7.343 mmol) of 4-(4-amino-2-methyl-phenyl)-3-methyl- aniline in 22579 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P40 was obtained with an intrinsic viscosity qintr of 0.52 dL / g. To 2500 mg of this 20 wt.-% NMP- solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F40.

[0274] Example 44: Preparation of polyamic acid P41 and corresponding alignment formulation F41

[0275] 1440 mg (7.343 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 500 mg (3.671 mmol) of 4-(2-aminoethyl)aniline, 199 mg (1 .836 mmol) of benzene-1 ,3-diamine and 390 mg (1 .836 mmol) of 4-(4-amino-2-methyl- phenyl)-3-methyl-aniline in 10113 mg of N M P. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid P41 was obtained with an intrinsic viscosity qintr of 0.65 dL / g. To 2500 mg of this 20 wt.-% NMP-solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F41 .

[0276] Comparative Example 45: Preparation of polyamic acid CP13 and corresponding alignment formulation CF13

[0277] 802 mg (4.092 mmol) of 4,9-dioxatricyclo[5.3.0.02’6]decane-3,5,8,10-tetrone were added at 0 °C to a solution of 1000 mg (4.092 mmol) of 4-[2-(4-aminophenoxy)ethoxy]aniline in 7052 mg of NMP. After 2 h at 0 °C; the reaction mixture was allowed to warm to room temperature and allowed to react for an additional 72 h. Polyamic acid CP13 was obtained with an inherent viscosity [q] of 0.71 dL / g. To 2500 mg of this 20 wt.-% NMP- solution were added 4650 mg of NMP and 2850 mg of BC. The resulting mixture was stirred for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation CF13.

[0278] Example 46: Preparation of cells with CF11 , CF12, CF13 and F37 to F41 and alignment quality comparison

[0279] Cell was prepared as in Example 32, except that formulation CF11 , CF12, CF13 and F37 to F41 were coated. The alignment quality was measured for each cell and the results are shown in the following Table 3.

[0280] Table 3

[0281] Example 47: Preparation of alignment formulation F43 3500mg of alignment formulation F3 and 1500mg of alignment formulation CF13 were stirred together for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F43.

[0282] Example 48: Preparation of alignment formulation F44

[0283] 3000mg of alignment formulation F3 and 2000mg of alignment formulation CF13 were stirred together for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F44.

[0284] Example 49: Preparation of alignment formulation F45

[0285] 3500mg of alignment formulation F1 and 1500mg of alignment formulation CF13 were stirred together for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F45.

[0286] Example 50: Preparation of alignment formulation F46

[0287] 3500mg of alignment formulation F3 and 1500mg of alignment formulation CF5 were stirred together for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F46.

[0288] Example 51 : Preparation of alignment formulation F47

[0289] 3500mg of alignment formulation F3 and 1500mg of alignment formulation CF6 were stirred together for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F47.

[0290] Example 52: Preparation of alignment formulation F48

[0291] 3500mg of alignment formulation F3 and 1500mg of alignment formulation CF10 were stirred together for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F48.

[0292] Example 53: Preparation of alignment formulation F49 3000mg of alignment formulation F3 and 3000mg of alignment formulation CF13 were stirred together for 30 min at room temperature and filtrated over a 0.2 pm PTFE-filter to give the alignment formulation F49. Example 54: Preparation of cells with CF5, CF6, CF10 and CF13 and F43 to F49 and alignment quality comparison

[0293] Cell is prepared as in Example 32 with F1 , except that formulation CF5, CF6, CF10 and CF13 and F43 to F49 are coated. The alignment quality is measured for each cell and resume in the following Table 4.

[0294] Table 4 It is evident that the photoalignable polymeric materials of the invention exhibit medium to excellent alignment quality.

Claims

Claims1 . A photoalignable polymeric material for forming a liquid crystal alignment film, comprising repeating units represented by formula (I)wherein P1is a divalent residue of a diamine HN2-Ar1-X1-NH2; and repeating units represented by formula (II)wherein P2is a divalent residue of a diamine HN2-Ar2-X2-Ar3-NH2;Ar1, Ar2and Ar3are independently selected from C3-Ci4-arylene, wherein Ar1, Ar2and Ar3may be independently substituted with one or more of OH, O-Ci-Ce-alkyl, Ci-Ce- alkyl, COOH, COO-Ci-Ce-alkyl and Ci-Ce-fluoroalkyl;X1is independently selected from a bond, Ci-Ce-alkylene, O-Ci-Ce-alkylene, and NH-Ci-Ce-alkylene, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F; X2is independently selected from a bond, O, NH, Ci-Ce-alkylene, O-Ci-Ce-alkylene, NH-Ci-C6-alkylene, NH-Ci-C6-alkylene-NH, NH-CO-(Ci-C6-alkylene), NH-CO-(CI-C6- alkylene)-CO-NH, CO-NH-(Ci-C6-alkylene), and CO-NH-(Ci-C6-alkylene)-NH-CO, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F;Q is a tetravalent residue of a tetracarboxylic dianhydride, and at least a portion of Q is represented by the formula (A)whereinR1is independently selected from H and Ci-Ce-alkyl;Y is independently selected from OH, O~M+and O-Ci-Ce-alkyl, wherein M+is an alkaline metal cation.

2. The photoalignable polymeric material according to claim 1 , whereinAr1, Ar2and Ar3are independently selected from phenylene and naphthylene;X1and X2are each a bond; wherein Ar1, Ar2, Ar3may be independently substituted with one or more Ci-Cs-alkyL3. The photoalignable polymeric material according to claim 2, whereinAr1is independently selected from phenylene and naphthylene; andAr2and Ar3are each phenylene.

4. The photoalignable polymeric material according to any one of the preceding claims, wherein the molar ratio of the repeating units of formula (I) to the repeating units of formula (II) is in the range of 1 : 10 to 10 : 1.

5. The photoalignable polymeric material according to any one of the preceding claims, wherein a portion of Q is represented by the formula (B)wherein n is an integer independently selected from 0 and 1 .

6. A photoalignable polymeric material composition comprising the photoalignable polymeric material as described above and polyamic acid and / or polyimide.

7. A photoalignable polymeric material composition comprising the photoalignable polymeric material and at least one solvent.

8. A process for producing a photoalignable polymeric material for forming a liquid crystal alignment film, comprising copolymerizing a mixture comprising a diamine of formula (1), a diamine of formula (2) and a cyclobutane tetracarboxylic acid dianhydride of formula (3) or a derivative thereofHN2-Ar1-X1-NH2(1 )HN2-Ar2-X2-Ar3-NH2(2)whereinAr1, Ar2and Ar3are independently selected from C3-Ci4-arylene, wherein Ar1, Ar2and Ar3may be independently substituted with one or more of OH, O-Ci-Ce-alkyl, Ci-Ce- alkyl, COOH, COO-Ci-Ce-alkyl and Ci-Ce-fluoroalkyL;X1is independently selected from a bond, Ci-Ce-alkylene, O-Ci-Ce-alkylene, and NH-Ci-Ce-alkylene, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F;X2is independently selected from a bond, O, NH, Ci-Ce-alkylene, O-Ci-Ce-alkylene, O-Ci-Ce-alkylene-O, NH-Ci-Ce-alkylene, NH-Ci-Ce-alkylene-NH, NH-CO-(Ci-C6-alkylene), NH-CO-(Ci-C6-alkylene)-CO-NH, CO-NH-(Ci-C6-alkylene), and CO-NH-(Ci-C6-alkylene)-NH-CO, wherein each Ci-Ce-alkylene independently may be substituted with one or more of OH, O-Ci-Ce-alkyl and F; andR1is independently selected from H and Ci-Ce-alkyL9. The process according to claim 8, whereinAr1, Ar2and Ar3are independently selected from phenylene and naphthylene;X1and X2are each a bond; wherein Ar1, Ar2, Ar3may be independently substituted with one or more Ci-Cs-alkyL10. The process according to claim 9, whereinAr1is independently selected from phenylene and naphthylene; andAr2and Ar3are each phenylene.11 . The process according to any one of claims 8 to 10, wherein the molar ratio of the first diamine of formula (1) to the second diamine of formula (2) is in the range of 1 : 10 to 10 : 1.

12. The process according to any one of claims 8 to 11 , wherein the mixture comprises a cyclopentane tetracarboxylic acid dianhydride of formula (4) or a derivative thereofwherein n is an integer independently selected from 0 and 1 .

13. A process for forming a liquid crystal alignment film, comprising:- applying a photoalignable polymeric material according to any one of claims 1 to 5, a photoalignable polymeric material composition according to claim 6 and / or 7, or a photoalignable polymeric material as obtained in a process according to any one of claims 8 to 12, onto a substrate;- drying the wet film thus obtained; and- irradiating the dried film to impart liquid crystal alignment capability.

14. A liquid crystal alignment film obtained by the process of claim 13.

15. An optical device comprising the liquid crystal alignment film according to claim 14.

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