| 摘要 |
PROBLEM TO BE SOLVED: To obtain an alignment layer material which can give a good coating having a low pretilt angle, adhesiveness, and stability by forming a polyamic acid comprising specified repeating units. SOLUTION: Provided is a polyamic acid alignment layer material used to form a pretilt angle of below 2 deg., wherein the polyamic acid comprises repeating units represented by formula I (wherein the ratio x/y is in the range of 0.8-1.2; and R is selected from among tetracarboxyl groups such as represented by formulae II, III, etc.). This polyamic acid is obtained by the condensation polymerization of a dianhydride with an aromatic diamine, and the aromatic diamine is 4,4'-bis(4-aminophenoxy)biphenyl. The polyamic acid has a degree of polymerization of 10-5,000, desirably, 40-250 and a weight- average molecular weight of 2,000-2,000,000, desirably, 8,000-50,000. The polymerization is conducted at -20 to 120 deg.C, desirably, 10-60 deg.C for 3 min to 24 h, desirably, 10 min to 6 h. |
