Orientation film materials and liquid crystal display device using it
View Patent ↗Various layer separation states are generated by the combination of a polyamide acid ester and a polyamide acid and a long residual image characteristic cannot be further improved merely by combining them. A liquid crystal display device comprises a substrate, a liquid crystal layer, and an orientation film placed between the substrate and the liquid crystal layer. The orientation film comprises a polyimide precursor having two or more components. In the polyimide precursor, an octanol-water partition coefficient is defined as log P and the difference in log P (Δ log P) between the two components having most distant log Ps is set so as to fall within a prescribed range.
1. A liquid crystal display device comprising
a substrate,
a liquid crystal layer, and
an orientation film placed between the substrate and the liquid crystal layer, wherein
the orientation film comprises a polyimide formed from a polyimide precursor having at least a first component and a second component, and
in the polyimide precursor, when an octanol-water partition coefficient is defined as log P and the difference in log P between the first component and the second component having most distant log Ps are defined as Δ log P, the relational expression 1.20<Δ log P<2.50 is satisfied,
wherein the polyimide precursor contains a polyamide acid ester and a polyamide acid,
the first component and the second component includes a structure represented by the following chemical formula (1),
X represents a hydrogen atom or an alkyl group, Y represents a divalent organic group, and Z represents a tetravalent organic group, and
the first component contains the following chemical formula (Z4) as the Z of the chemical formula (1)
2. The liquid crystal display device according to claim 1 , wherein the relational expression 1.30<Δ log P<2.00 is satisfied.
3. The liquid crystal display device according to claim 2 , wherein the relational expression 1.40<Δ log P<1.80 is satisfied.
4. The liquid crystal display device according to claim 1 , wherein the orientation film is given a liquid crystal orientation capability by being irradiated with polarized ultraviolet light.
5. The liquid crystal display device according to claim 4 , wherein the polyamide acid ester contains a cyclobutane ring.
6. The liquid crystal display device according to claim 1 , comprising
an electrode group for applying an electric field to the liquid crystal layer, and
a plurality of active elements connected to the electrode group.
7. An orientation film material comprising a polyimide precursor having two or more components containing a polyamide acid and a polyamide acid ester, wherein, in the polyimide precursor, when an octanol-water partition coefficient is defined as log P, log P of the polyamide acid is defined as log P(A), log P of the polyamide acid ester is defined as log P(E), and the difference between log P(A) and log P(E) is defined as Δ log P, the relational expression 1.20<Δ log P<2.50 is satisfied,
wherein the polyamide acid and the polyamide acid ester include a structure the following chemical formula (1);
X represents a hydrogen atom or an alkyl group, Y represents a divalent organic group, and Z represents a tetravalent organic group; and
the polyamide acid ester contains the following chemical formula (Z4) as Z of the above chemical formula (1)
8. The orientation film material according to claim 7 , wherein the relational expression 1.30<Δ log P<2.00 is satisfied.
9. The orientation film material according to claim 8 , wherein the relational expression 1.40<Δ log P<1.80 is satisfied.
10. The orientation film material according to claim 7 , wherein the polyamide acid ester contains a cyclobutane ring.
11. The orientation film material according to claim 10 , wherein the orientation film material is given a liquid crystal orientation capability by being irradiated with polarized ultraviolet light.
12. The orientation film material according to claim 7 , wherein the blend ratio of the polyamide acid and the polyamide acid ester is in the range of 10/90 to 90/10.
13. The liquid crystal display device according to claim 1 , wherein;
the orientation film includes an upper layer contacting the liquid crystal layer and a lower layer; and
the upper layer comprises a polyimide immunized from the first compound.