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CN-121986293-A - Liquid crystal aligning agent, liquid crystal alignment film and liquid crystal display element

CN121986293ACN 121986293 ACN121986293 ACN 121986293ACN-121986293-A

Abstract

The invention provides a liquid crystal alignment film which has good liquid crystal alignment property and excellent pretilt angle expression capability, a liquid crystal display element with the liquid crystal alignment film, and a liquid crystal alignment agent for the liquid crystal alignment film. The invention provides a liquid crystal aligning agent, which contains a compound having a photo-alignment group shown in the following formula (pa-1), an oxetanyl group and a polar group as a component (A), polyamide acid as a component (B), and a solvent. [ chemical 1] (In the formula (pa-1), A represents phenylene, etc., R 1 is-COO-or-OCO-, R 2 is cyclohexane-1, 4-diyl, R 3 is cyclohexane-1, 4-diyl, R 4 is a linear or branched alkyl group having 1 to 40 carbon atoms, part or all of hydrogen atoms of the alkyl group may be substituted with fluorine atoms, D represents an oxygen atom, a sulfur atom or-NR d -, a is an integer of 0 to 3, Indicating the bonding position).

Inventors

  • Yutai Iizuka
  • MORIUCHI MASATO

Assignees

  • 日产化学株式会社

Dates

Publication Date
20260505
Application Date
20241011
Priority Date
20231012

Claims (9)

  1. 1. A liquid crystal aligning agent characterized by comprising: A compound having a photo-alignment group represented by the following formula (pa-1), an oxetanyl group and a polar group as the component (A); polyamide acid as component (B), and The solvent is used for the preparation of the aqueous solution, Wherein A represents pyrimidine-2, 5-diyl, pyridine-2, 5-diyl, thiophene-2, 5-diyl, furan-2, 5-diyl, 1, 4-naphthylene, 2, 6-naphthylene or phenylene, wherein the group A is substituted or not with a group selected from the group consisting of a fluorine atom, a chlorine atom, a cyano group, an alkoxy group having 1 to 5 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms and a branched alkyl group having 1 to 5 carbon atoms, the alkyl group being optionally substituted with 1 cyano group or with 1 or more halogen atoms, R 1 is a single bond, an oxygen atom, COO-or-OCO-, R 2 is a 2-valent aromatic group, a 2-valent alicyclic group, a 2-valent heterocyclic group, R 3 is a single bond, an oxygen atom, COO-or-OCO-, R 4 is a linear or branched alkyl group having 1 to 40 carbon atoms, or a cyclic group having 3 carbon atoms and a 3-to 40 carbon atoms, wherein R 1 is a 2-valent alicyclic group or a 2-valent fused ring group, R 3 is a carbon atom, and the carbon atoms of the NR is an integer of 3 to 3; wherein when a is 2 or more, R 1 and R 2 are each independently defined as above, X and Y are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group having 1 to 3 carbon atoms, a part or all of the hydrogen atoms of the alkyl group is substituted with a fluorine atom or is not substituted with a fluorine atom, The "wavy line" between "C" and "A" and between "C" and "X" is denoted as the E isomer or as the Z isomer.
  2. 2. The liquid crystal aligning agent according to claim 1, wherein the polar group of component (a) is a group selected from the group consisting of a hydroxyl group, a thiol group, an amino group, a monoalkylamino group, a dialkylamino group, a carboxyl group, a sulfonyl group, a pyridyl group, an imidazolyl group and a triazolyl group.
  3. 3. The liquid crystal aligning agent according to claim 1, wherein the polar group of component (a) is a hydroxyl group.
  4. 4. A liquid crystal alignment film comprising the liquid crystal alignment agent according to any one of claims 1 to 3.
  5. 5. A method for producing a liquid crystal alignment film, comprising: A process for forming a coating film by applying the liquid crystal aligning agent according to any one of claims 1 to 3 to a substrate, and And irradiating the coating film with light in a state where the coating film is not in contact with the liquid crystal layer or in a state where the coating film is in contact with the liquid crystal layer.
  6. 6. A liquid crystal display element comprising the liquid crystal alignment film according to claim 4 or the liquid crystal alignment film obtained by the production method according to claim 5.
  7. 7. A compound having a photo-alignment group represented by the following formula (pa-1), an oxetanyl group and a polar group, Wherein A represents pyrimidine-2, 5-diyl, pyridine-2, 5-diyl, thiophene-2, 5-diyl, furan-2, 5-diyl, 1, 4-naphthylene, 2, 6-naphthylene or phenylene, wherein the group A is substituted or not with a group selected from the group consisting of a fluorine atom, a chlorine atom, a cyano group, an alkoxy group having 1 to 5 carbon atoms, a linear alkyl group having 1 to 5 carbon atoms and a branched alkyl group having 1 to 5 carbon atoms, the alkyl group being optionally substituted with 1 cyano group or with 1 or more halogen atoms, R 1 is a single bond, an oxygen atom, COO-or-OCO-, R 2 is a 2-valent aromatic group, a 2-valent alicyclic group, a 2-valent heterocyclic group, R 3 is a single bond, an oxygen atom, COO-or-OCO-, R 4 is a linear or branched alkyl group having 1 to 40 carbon atoms, or a cyclic group having 3 carbon atoms and a 3-to 40 carbon atoms, wherein R 1 is a 2-valent alicyclic group or a 2-valent fused ring group, R 3 is a carbon atom, and the carbon atoms of the NR is an integer of 3 to 3; wherein when a is 2 or more, R 1 and R 2 are each independently defined as above, X and Y are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a cyano group or an alkyl group having 1 to 3 carbon atoms, a part or all of the hydrogen atoms of the alkyl group is substituted with a fluorine atom or is not substituted with a fluorine atom, The "wavy line" between "C" and "A" and between "C" and "X" is denoted as the E isomer or as the Z isomer.
  8. 8. The compound according to claim 7, wherein the polar group is a group selected from the group consisting of hydroxyl, thiol, amino, monoalkylamino, dialkylamino, carboxyl, sulfonyl, pyridyl, imidazolyl, and triazolyl.
  9. 9. A compound represented by any one of the following formulas (AD-1) to (AD-4): 。

Description

Liquid crystal aligning agent, liquid crystal alignment film and liquid crystal display element Technical Field The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film obtained therefrom, and a liquid crystal display element provided with the obtained liquid crystal alignment film. More specifically, the present invention relates to a liquid crystal aligning agent which can provide a liquid crystal alignment film having good liquid crystal alignment properties, excellent pretilt angle expression ability, and high reliability, and a liquid crystal display element having excellent display quality. Background In a liquid crystal display element, a liquid crystal alignment film plays a role of aligning liquid crystal in a certain direction. Currently, a main liquid crystal alignment film industrially used is produced by applying a polyimide-based liquid crystal alignment agent containing a solution of a polyamic acid (also referred to as a polyamic acid), a polyamic acid ester, or a polyimide, which is a polyimide precursor, onto a substrate to form a film. In the case of aligning the liquid crystal parallel to the substrate surface or obliquely, after film formation, a surface stretching treatment by friction is further performed. On the other hand, when the liquid crystal is aligned vertically to the substrate (referred to as a Vertical Alignment (VA) system), a liquid crystal alignment film in which a long-chain alkyl group, a cyclic group, or a combination of a cyclic group and an alkyl group (for example, see patent document 1), a steroid skeleton (for example, see patent document 2), or other hydrophobic groups are introduced into a side chain of polyimide is used. In this case, when a voltage is applied between the substrates to tilt the liquid crystal molecules in a direction parallel to the substrates, it is necessary to tilt the liquid crystal molecules from the substrate normal direction toward one direction within the substrate surface. As a method for this, for example, a method of providing a projection on a substrate, a method of providing a slit on a display electrode, a method of slightly tilting (pretilting) liquid crystal molecules from the substrate normal direction toward one direction in the substrate surface by rubbing, a method of pretilting liquid crystals by adding a photopolymerizable compound to a liquid crystal composition in advance, and applying a voltage to a liquid crystal cell while applying ultraviolet light together with a vertical alignment film such as polyimide, and the like are proposed (for example, refer to patent document 3). In recent years, as a method for replacing the formation of protrusions or slits and PSA technology in VA-mode liquid crystal alignment control, a method (photo-alignment method) using anisotropic photochemical reaction by polarized ultraviolet irradiation or the like has also been proposed. That is, it is known that by irradiating a polyimide film having a photoreactive vertical alignment property with polarized ultraviolet light, alignment regulating ability and pretilt angle expressivity are imparted, and thus the tilt direction of liquid crystal molecules at the time of voltage application can be uniformly controlled (see patent document 4). VA-mode liquid crystal display elements are used for TV and in-vehicle displays because of their high contrast and wide viewing angle. In order to obtain high luminance, a backlight having a large heat generation amount is used as a liquid crystal display element for TV applications, or a liquid crystal display element used for in-vehicle applications, for example, in car navigation systems and dashboards, and may be used or left in a high-temperature environment for a long period of time. Under such severe conditions, when the pretilt angle gradually changes, there occurs a problem that initial display characteristics cannot be obtained, display unevenness occurs, or the like. Further, the voltage holding characteristics and the charge accumulation characteristics at the time of driving the liquid crystal are also affected by the liquid crystal alignment film, and when the voltage holding ratio is low, a phenomenon occurs in which the contrast of the display screen is lowered, and when the charge accumulation with respect to the dc voltage is large, a phenomenon occurs in which the display screen burns. Prior art literature Patent literature Patent document 1 Japanese patent laid-open No. 3-179323 Patent document 2 Japanese patent laid-open No. 4-281427 Patent document 3 Japanese patent No. 4504626 Patent document 4 Japanese patent No. 4995267 Disclosure of Invention Technical problem to be solved by the invention The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal alignment film having excellent vertical alignment and high voltage holding characteristics, a liquid crystal di