Patent EA-000614-B1 (EA)
Title: Temperature matched retardation layer
Inventor: DE WIT PAULUS PIETER
IPC: C08G65/22
Filed: 1996-12-16
Abstract: 1. A liquid crystalline display comprising a display cell containing liquid crystalline material and a retardation layer, said retardation layer comprising a high-molecular weight material layer and a substrate, wherein the high-molecular weight material has a nematic phase above its Tg and a dynamic viscosity at the working temperature of at least 100 Pas, and the difference of the Tc of the high-molecular weight material and the Tc of the low-molecular weight material of the display cell is in the range of -30 degree C to +30 degree C, preferably in the range of -20 degree C to +20 degree C, and more preferably in the range of -10 degree C to +10 degree C; and the Tg of the high-molecular weight liquid crystalline material is lower than 50 degree C. 2. The liquid crystalline display of Claim 1 wherein the high-molecular weight material of the retardation layer is slightly cross-linked. 3. The liquid crystalline display of Claim 1 or 2 wherein the Tg of the high-molecular weight liquid crystalline material is -50 to +35 degree C. 4. The liquid crystalline display of any one of Claims 1 to 3 wherein the high-molecular weight material layer has a chiral nematic calamitic or discotic structure. 5. The liquid crystalline display of any one of Claims 1-4 wherein the high-molecular weight material is a polyether obtainable by polymerizing a monomer mixture comprising: a) an OH-containing compound; and b) a mesogenic group-containing -mono-epoxide. 6. The liquid crystalline display of Claim 5 wherein the monomer mixture comprises oxiranylmethane. 7. The liquid crystalline display of Claim 5 wherein the mesogenic group-containing mono-epoxide has a spacer. 8. The liquid crystalline display of any one of Claims 5-7 wherein the epoxy groups/hydroxy groups ratio in the monomer mixture is in the range of 5:1 to 1:1. 9. The liquid crystalline display according to any one of Claims 5-8 wherein the OH-containing compound is a mono-OH-containing compound according to the formula below: HO-(Y)m-Z wherein: Z stands for H (when m  [not equal]  0), -O-C(O)-CH=CH2,, -O-C (O)-C (CH3)=CH2, a cyclic, aromatic, or heterocyclic compound having 4-10 carbon atoms. which compound may comprise a mesogenic group, -CH- (CH2-O-C (O)-CH=CH2)2,-C (CH2-OC (O)-CH=CH2)3, -C (CH2-O-C (O)-CH=CH2)2-CH3, -CH (CH2-O-C (O)-C (CH3)=CH2)2, -C (CH2-OC (O)-C (CH3)=CH2)3, or -C (CH2-O-C (O)-C(CH3)=CH2)2-CH3; Y stands for -CH2-, -C (CH3)2, -CH (CH3)-, -CH2-O-φ<1>-(CH2)m-, or -HC[-(CH2)m-O-φ<1>-(Q)n-φ<2>-R<1>]-, wherein the various Y groups may be the same or different; m stands independently for an integer from 0-12, with the proviso that compounds having an oxygen atom in the a or p position vis-a-vis the OH group are excluded: Q stands for-C (O)-O-, -C=C-, -C=N-. -N=C-, O-C (O)-, -C [triple bond] C-, -N=N-. or -N(<- O)=N-; R<1> stands for -O-R<2>, -NO2, -CN, -HC=C (CN)2, -C (CN)=C (CN)2. or -R<2>; R<2> stands for an alkyl group having 1-15 carbon atoms, -(CH2)k-O-C (O)-CH=CH2, -(CH2)k-O-C (O)-C (CH3)=CH2, or -(CH2)-OH; x stands for an integer from 0-12: k stands for an integer from 0-12, with the proviso that k is not 0 or 1 when R<1> =-O-R<2>; φ<1> stands for an cyclic, aromatic, or heterocyclic compound having 4-10 carbon atoms, which compound may be substituted with a mesogenic group; φ<2> stands for a cyclic, aromatic, or heterocyclic compound having 4-10 carbon atoms, which compound may be substituted with a mesogenic group; and n stands for 0 or 1. 10. The liquid crystalline display of any one of Claims 5-9 wherein the OH-containing compound is a compound according to any one of the formulae below:   wherein R<3> stands for an alkyl group having 1-12 carbon atoms, and Z, Y, φ<1>, φ<2>, m, and n have the same meaning as in the formula of Claim 9. 11. The liquid crystalline display of any one of Claims 5-10 wherein the mesogenic group-containing mono-epoxide group satisfies one of the formulae below:     wherein Q1 stands for -C (O)-O-, -C=C-, -O-C (O)-, -N=C-, -C=N-, -C [triple bond] C-, -N=N-, or -N(<- O)=N-; W stands for C, O, or S; A stands for   Q2 stands for -O-C (O)-, -O-, or -O-C (O)-C=C-; R<4> stands for-O-R<8>, -COO-R<8>, -OCO-R<8>, -NO2, -CN, -HC=C (CN)2, -C (CN)=C(CN)2, or-R<8>; R<5> stands for an alkyl group having 1-5 carbon atoms; R<6> stands for an alkyl group having 1-5 carbon atoms; R<7> stands for H or CH3; p is 1-7; m is 0-12 with the proviso that compounds having an oxygen atom in the a or p position vis-a-vis the oxygen of the epoxy group are excluded; n is 0 or 1; q is 0-3, with the proviso that q  [not equal]  0 when m =0; r is 0 or 1; R<8> stands for an alkyl group having 1-15 carbon atoms; R<9> stands for H or an alkyl group having 1-15 carbon atoms; and R<10> stands for an alkyl or alkoxy group having 1-20 carbon atoms. 12. A slightly cross-linkable or cross-linked liquid crystalline polyether obtainable by polymerizing a monomer mixture comprising: a) an OH-containing compound; b) a mesogenic group-containing mono-epoxide; and c) an acrylic group-containing epoxide or OH-containing compound.