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CN-122012118-A - Liquid crystal alignment agent for photoalignment method, liquid crystal photoalignment film, and liquid crystal display element

CN122012118ACN 122012118 ACN122012118 ACN 122012118ACN-122012118-A

Abstract

The present invention relates to a liquid crystal alignment agent for a photoalignment method, a liquid crystal photoalignment film, and a liquid crystal display element. The present invention relates to a liquid crystal alignment agent for a photoalignment method having excellent heat resistance, a liquid crystal photoalignment film formed of the liquid crystal alignment agent, and a liquid crystal display element including the liquid crystal photoalignment film. The liquid crystal alignment agent for photoalignment method comprises a polymer component (A), a solvent (B) and a compound (C). The polymer component (a) includes a first polymer (A1) selected from at least one of the group consisting of polyimide precursors and imidized polymers formed from polyimide precursors. The polyimide precursor of the first polymer (A1) comprises a structure shown as a formula (I), and the compound (C) comprises a structure shown as a formula (C-1), and the definitions of the structure are respectively as described in the specification and the claims. By using the compound (C), the liquid crystal display element including the liquid crystal photoalignment film formed of the liquid crystal alignment agent is excellent in heat resistance. (I) (c-1)

Inventors

  • WANG BOSHI
  • WANG JIANZHI
  • HUANG WANTING
  • CHEN ZHIRONG

Assignees

  • 奇美实业股份有限公司

Dates

Publication Date
20260512
Application Date
20260112

Claims (10)

  1. 1. A liquid crystal alignment agent for a photoalignment method is characterized by comprising the following components: a polymer component (a) including a first polymer (A1), and the first polymer (A1) is selected from at least one of the group consisting of a polyimide precursor and an imidized polymer formed by the polyimide precursor; solvent (B) A compound (C); The polyimide precursor of the first polymer (A1) comprises a structure as shown in formula (I), (I) In the formula (I), X 1 represents at least one of the group consisting of structures represented by the formulas (I-1) to (I-7), " "Means that the position of the bond, (I-1)、 (I-2)、 (I-3)、 (I-4)、 (I-5)、 (I-6)、 (I-7), In the formula (I-1), X 11 、X 12 、X 13 and X 14 each independently represent hydrogen, halogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing fluorine, or phenyl, In the formula (I-7), X 15 and X 16 each independently represent hydrogen or methyl, X 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, X 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, Y 1 represents a divalent organic group, The compound (C) comprises a structure represented by the formula (C-1), (c-1) In the formula (c-1), R 1 represents an n-valent organic group containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group having a carbon number of 1 to 20, N represents an integer of 2 to 6, R 2 represents an alkyl group having 5 to 20 carbon atoms, an alkenyl group having 5 to 20 carbon atoms, or an alkynyl group having 5 to 20 carbon atoms, and the R 2 may have a substituent selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and at least one hydroxy group is contained in the substituent.
  2. 2. The liquid crystal alignment agent for photoalignment method according to claim 1, wherein the compound (C) is at least one selected from the group consisting of a compound having a structure represented by the formula (C-1-1) and a compound having a structure represented by the formula (C-1-2), (c-1-1) In the formula (c-1-1), R 3 、R 4 、R 5 is independently alkyl with 1 to 20 carbon atoms, alkenyl with 1 to 20 carbon atoms or alkynyl with 1 to 20 carbon atoms, and R 3 , R 4 and R 5 can have substituent groups, wherein the substituent groups are at least one selected from methoxy, ethoxy, halogen, hydroxy, phenyl and tolyl, and the substituent groups of R 3 at least contain one hydroxy, the sum of the carbon numbers of R 3 , R 4 and R 5 is more than 4, R 6 represents an m-valent organic group comprising an aliphatic hydrocarbon group or an aromatic hydrocarbon group having a carbon number of 1 to 20, m represents an integer of 2 to 6, (c-1-2) In the formula (c-1-2), R 7 、R 8 、R 9 is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, or an alkynyl group having 1 to 20 carbon atoms, and R 7 , R 8 , R 9 may have a substituent selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and at least one hydroxy group is contained in the substituent of R 7 , the sum of the carbon numbers of R 7 , R 8 , and R 9 is 3 or more, R 10 represents a p-valent organic group containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group having a carbon number of 1 to 20, and p represents an integer of 2 to 6.
  3. 3. A liquid crystal alignment agent for photoalignment method according to claim 2, wherein the substituent R 4 in the formula (c-1-1) contains at least one hydroxyl group.
  4. 4. A liquid crystal alignment agent for photoalignment method according to claim 2, wherein the substituent R 8 in the formula (c-1-2) contains at least one hydroxyl group.
  5. 5. A liquid crystal alignment agent for photoalignment method according to claim 1, wherein the compound (C) is used in an amount ranging from 0.5 to 20 parts by weight based on 100 parts by weight of the total used amount of the polymer component (A).
  6. 6. The liquid crystal alignment agent for photoalignment method according to claim 1, wherein X 1 is a structure selected from the group consisting of the structures represented by the formulas (I-1-1) to (I-1-6), (I-1-1)、 (I-1-2)、 (I-1-3)、 (I-1-4)、 (I-1-5)、 (I-1-6)。
  7. 7. The liquid crystal alignment agent for photoalignment method according to claim 6, wherein X 1 has a structure represented by the formula (I-1-1), (I-1-1)。
  8. 8. The liquid crystal alignment agent for photoalignment method according to claim 1, wherein the polymer component (A) further comprises a second polymer (A2), wherein the second polymer (A2) is at least one selected from the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor, the polyimide precursor of the second polymer (A2) is formed by reacting a reaction composition comprising a tetracarboxylic dianhydride component (A2) and a diamine component (b 2), the diamine component (b 2) comprises a diamine compound (b 2-1) having a nitrogen atom structure, and the nitrogen atom structure of the diamine compound (b 2-1) having a nitrogen atom structure is at least one selected from the group consisting of a heterocycle, a secondary amino group and a tertiary amino group having a nitrogen atom.
  9. 9. A liquid crystal photoalignment film, characterized in that the liquid crystal photoalignment film is formed of the liquid crystal alignment agent for photoalignment method according to any of claims 1 to 8.
  10. 10. A liquid crystal display element comprising the liquid crystal photoalignment film according to claim 9.

Description

Liquid crystal alignment agent for photoalignment method, liquid crystal photoalignment film, and liquid crystal display element Technical Field The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a liquid crystal display device, and more particularly, to a liquid crystal alignment agent, a liquid crystal photoalignment film and a liquid crystal display device for a photoalignment method having excellent heat resistance. Background Conventional liquid crystal display devices are widely used as display elements for personal computers, smart phones, mobile phones, television sets, and the like. The liquid crystal display device may include, for example, a liquid crystal layer sandwiched between a device substrate and a color filter substrate, a pixel electrode and a common electrode for applying an electric field to the liquid crystal layer, a liquid crystal alignment film for controlling the alignment of liquid crystal molecules of the liquid crystal layer, and a Thin Film Transistor (TFT) for switching an electronic signal supplied to the pixel electrode. As a driving method of liquid crystal molecules, a vertical electric field method such as a twisted nematic (TWISTED NEMATIC, abbreviated as TN) method and a vertical alignment (VERTICAL ALIGNMENT, abbreviated as VA) method, and a transverse electric field method such as an In-plane switching (In-PLANE SWITCHING, abbreviated as IPS) method and a fringe field switching (FRINGE FIELD SWITCHING, abbreviated as FFS) method are known. Currently, the most popular liquid crystal alignment film in industry is produced by rubbing a surface of a film formed on an electrode substrate and composed of polyamic acid and/or polyimide obtained by imidizing the polyamic acid with cotton cloth, nylon cloth, polyester cloth, or the like in one direction. The rubbing treatment is a simple and convenient industrial common alignment treatment method with high productivity. However, with the increase in performance, the miniaturization, and the size enlargement of the liquid crystal display device, various problems such as alignment unevenness of the liquid crystal alignment film are caused by scratches on the surface of the liquid crystal alignment film due to dust, mechanical force, and static electricity generated by the rubbing treatment. As an alignment treatment method instead of rubbing treatment, a photoalignment method is known in which polarized radiation is irradiated to impart alignment ability to liquid crystals. For the photoalignment method, japanese patent application laid-open No. 9-297313 discloses the use of a photoisomerization reactor, a photocrosslinking reactor, a photodecomposition reactor, or the like. However, the conventional liquid crystal alignment film prepared by the photoalignment method is prone to have poor heat resistance, and cannot meet the application requirements. Disclosure of Invention The first object of the present invention is to provide a liquid crystal alignment agent for a photoalignment method which can impart good heat resistance to a liquid crystal display element. The liquid crystal alignment agent for the photoalignment method comprises a polymer component (A), a solvent (B) and a compound (C). The polymer component (a) includes a first polymer (A1), and the first polymer (A1) is selected from at least one of the group consisting of a polyimide precursor and an imidized polymer formed from the polyimide precursor. The polyimide precursor of the first polymer (A1) comprises a structure as shown in formula (I), (I) In the formula (I), X 1 represents at least one of the group consisting of structures represented by the formulas (I-1) to (I-7), ""Means that the position of the bond, (I-1)、 (I-2)、 (I-3)、 (I-4)、 (I-5)、 (I-6)、 (I-7), In the formula (I-1), X 11、X12、X13 and X 14 each independently represent hydrogen, halogen, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and containing fluorine, or phenyl, In the formula (I-7), X 15 and X 16 each independently represent hydrogen or methyl, X 2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, X 3 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, Y 1 represents a divalent organic group. The compound (C) comprises a structure represented by the formula (C-1), (c-1) In the formula (c-1), R 1 represents an n-valent organic group containing an aliphatic hydrocarbon group or an aromatic hydrocarbon group having a carbon number of 1 to 20, N represents an integer of 2 to 6, R 2 represents an alkyl group having 5 to 20 carbon atoms, an alkenyl group having 5 to 20 carbon atoms, or an alkynyl group having 5 to 20 carbon atoms, and the R 2 may have a substituent selected from at least one of methoxy, ethoxy, halogen, hydroxy, phenyl, and tolyl, and at least one hydroxy group i