Film

A film comprising a layer of an anisotropic polymer material with an optical axis substantially parallel to the plane of the layer, said film being obtainable by a process comprising the following steps

• A) coating a polymerizable mesogenic composition comprising:
• a) 10 to 50% by weight of one or two polymerizable mesogenic compounds of formula Ia and 5 to 35% by weight of one or two polymerizable mesogenic compounds of formula Ib
• wherein
• W is H or CH3,
• n is an integer from 3 to 6, and
• R is alkyl or alkoxy with 1 to 8 C atoms,
• b) 15 to 60% by weight of a polymerizable mesogenic compound of formula II
• wherein
• W is H or CH3
• n is an integer from 3 to 6,
• Z1 and Z2 are each independently —COO— or —OCO—, and
• X1 and X2 are each independently H or CH3, and
• c) 0.1 to 8% by weight of a photoinitiator, said mixture optionally being dissolved in an organic solvent in a concentration of up to 50% by weight, on a substrate in form of a layer,
• B) aligning the polymerizable mesogenic composition into a homogeneous orientation,
• C) polymerizing the polymerizable mesogenic composition by exposure to UV light, and
• D) optionally removing the substrate from the polymerized material,
• wherein
• I) 50 to 2500 ppm of a mixture of non-ionic fluoroalkyl-alkoxylate surfactants selected from the following formulae
• CnF2n+1SO2N(C2H5)(CH2CH2O)xCH3 III
• CnF2n+1(CH2CH2O)xH IV
• with n being an integer from 4 to 12 and x being an integer from 5 to 15,
• are added to the polymerizable mesogenic composition prior to or during step A) of said process, and
• II) a PET or TAC film is used as the substrate onto which said polymerizable mesogenic composition is coated in step A) of said process, and
• III) prior to step A) of said process the surface of said PET or TAC film adjacent to said polymerizable mesogenic composition is rubbed unidirectionally or is covered by a polyimide layer which is rubbed unidirectionally.

A film being obtainable by a process comprising the following steps

• A) coating a polymerizable mesogenic composition comprising:
• a) 10 to 50% by weight of one or two polymerizable mesogenic compounds of formula Ia and 5 to 35% by weight of one or two polymerizable mesogenic compounds of formula Ib
• wherein
• W is H or CH3,
• n is an integer from 3 to 6, and
• R is alkyl or alkoxy with 1 to 8 C atoms,
• b) 15 to 60% by weight of a polymerizable mesogenic compound of formula II
• wherein
• W is H or CH3
• n is an integer from 3 to 6,
• Z1 and Z2 are each independently —COO— or —OCO—, and
• X1 and X2 are each independently H or CH3, and
• c) 0.1 to 8% by weight of a photoinitiator, said mixture optionally being dissolved in an organic solvent in a concentration of up to 50% by weight, on a substrate in form of a layer,
• B) aligning the polymerizable mesogenic composition into a homogeneous orientation,
• C) polymerizing the polymerizable mesogenic composition and
• D) optionally removing the substrate from the polymerized material,
• wherein optionally
• I) 50 to 2500 ppm of a mixture of non-ionic fluoroalkyl-alkoxylate surfactants selected from the following formulae
• CnF2n+1SO2N(C2H5)(CH2CH2O)xCH3 III
• CnF2n+1(CH2CH2O)xH IV
• with n being an integer from 4 to 12 and x being an integer from 5to 15,
• are added to the polymerizable mesogenic composition prior to or during step A) of said process, and
• II) a PET or TAC film is used as the substrate onto which said polymerizable mesogenic composition is coated in step A) of said process, and
• III) prior to step A) of said process the surface of said PET or TAC film adjacent to said polymerizable mesogenic composition is rubbed unidirectionally or is covered by a polyimide layer which is rubbed unidirectionally.