Liquid crystal additive, liquid crystal composition and display panel

Abstract

The invention discloses a liquid crystal additive, a liquid crystal composition and a display panel. The liquid crystal additive has a chemical structural formula shown in a formula (1), the liquid crystal additive provided by the invention can be added into the liquid crystal composition, and can realize horizontal orientation of liquid crystal compound molecules in the liquid crystal composition under the conditions that an azobenzene structure is not contained and a PI orientation layer is not needed, so that the display problem caused by coloring is avoided while low-cost liquid crystal orientation is realized.

Description

Technical Field

[0001] This application relates to the field of display technology, specifically to a liquid crystal additive, a liquid crystal composition, and a display panel. Background Technology

[0002] A liquid crystal display (LCD) consists of a thin-film transistor (TFT) array substrate, a color filter (CF) substrate, and liquid crystal sandwiched between the TFT array substrate and the CF substrate. The TFT array substrate provides switching and data signals, while the CF substrate provides color. The brightness of the display is controlled by the deflection of the liquid crystal between the TFT array substrate and the CF substrate. This deflection is primarily achieved by an anisotropic liquid crystal alignment film anchoring the liquid crystal to its initial orientation.

[0003] Currently, polyimide (PI) is commonly used as the liquid crystal alignment material for fringe field switching (FFS) or in-plane switching (IPS) display modes. Using PI as a horizontal liquid crystal alignment agent requires alignment treatments such as rubbing or polarized light exposure, as well as a high-temperature curing process, resulting in high manufacturing costs. Therefore, patent document (JP2015064465A) proposes dissolving a dendritic polymer containing an azobenzene structure in a liquid crystal composition, then using phase separation technology to form a thin film of the dendritic polymer on a substrate. The substrate is then heated and irradiated with linearly polarized light, causing the dendritic polymer to dimerize or isomerize, aligning its molecules in a direction relative to the substrate's horizontal plane. This method can be used to manufacture liquid crystal display elements for horizontal alignment modes such as IPS or FFS. However, the conjugated structure of azobenzene easily leads to polymer or film coloring, thereby compromising the light transmittance and color accuracy of the liquid crystal display element. Summary of the Invention

[0004] This application provides a liquid crystal additive, a liquid crystal composition, and a display panel. The liquid crystal additive can be added to the liquid crystal composition. Without the presence of an azobenzene structure and without the need for a PI alignment layer, it can achieve horizontal alignment of liquid crystal compound molecules in the liquid crystal composition, thereby achieving low-cost liquid crystal alignment while avoiding display problems caused by coloring.

[0005] This application provides a liquid crystal additive having the chemical structural formula shown in formula (1): (1); Wherein, A is selected from any one of tetravalent phenyl, tetravalent cyclohexyl, tetravalent pyridyl, tetravalent pyrimidinyl, tetravalent naphthyl, tetravalent tetrahydronaphthyl, tetravalent fluorenyl and tetravalent biphenyl; A1 and A2 are independently selected from polymerizable groups containing carbon-carbon double bonds and / or carbon-carbon triple bonds; B1 is selected from the first functional group containing a cinnamic acid ester structure or a chalcone structure; B2 is selected from a second functional group containing a polar group; m and n are independently selected from any integer from 0 to 5.

[0006] Optionally, A is selected from any of the following groups: ; In this context, * represents a bond.

[0007] Optionally, the polymerizable group contains any one or more combinations of acryloyloxy, methacryloxy, fluoroacrylate, vinyl, vinyloxy, and epoxy groups.

[0008] Optionally, the polar group in the second functional group is selected from hydroxyl or phosphate groups.

[0009] Optionally, the liquid crystal additive is selected from any one or more combinations of compounds represented by formulas (1-1) to (1-9): (1-1) (1-2) (1-3) (1-4) (1-5) (1-6) (1-7) (1-8) (1-9); Where m1 and n1 are independently selected from any integer from 1 to 8.

[0010] Optionally, the liquid crystal additive is selected from any one or a combination of two of the compounds shown in formula (1-1-1) and formula (1-2-1): (1-1-1) (1-2-1).

[0011] Accordingly, this application also provides a liquid crystal composition comprising at least one liquid crystal compound and at least one of the liquid crystal additives described above.

[0012] Optionally, in the liquid crystal composition, the mass percentage of the liquid crystal additive is from 0.01% to 20%.

[0013] In addition, this application also provides a display panel, the display panel comprising: A first substrate and a second substrate arranged opposite to each other; A liquid crystal layer sandwiched between the first substrate and the second substrate; A first liquid crystal alignment layer is disposed on the side of the first substrate near the liquid crystal layer; A second liquid crystal alignment layer is disposed on the side of the second substrate near the liquid crystal layer; Wherein, the material of the first liquid crystal alignment layer and / or the material of the second liquid crystal alignment layer are selected from photo-alignment polymers, and the monomers of the photo-alignment polymers are selected from at least one of the liquid crystal additives mentioned above.

[0014] Optionally, the material of the first liquid crystal alignment layer is selected from the photo-alignment polymer, and the material of the second liquid crystal alignment layer includes polyimide.

[0015] The liquid crystal additive, liquid crystal composition, and display panel provided in this application have a chemical structure as shown in formula (1). This liquid crystal additive has high chemical stability and a high ability to horizontally align liquid crystal molecules. By adding this liquid crystal additive to the liquid crystal composition of the liquid crystal cell, horizontal alignment of liquid crystal molecules can be achieved without a PI alignment layer. In the chemical structure of the liquid crystal additive shown in formula (1), the polar group in the B2 group can interact with the substrate of the liquid crystal cell, allowing the liquid crystal additive molecules to adhere to the substrate surface; the B1 group contains a cinnamic acid ester structure or a chalcone structure, which allows the liquid crystal additive molecules to dimerize or isomerize under polarized ultraviolet light irradiation in a non-heated state, causing the liquid crystal additive molecules to align in a fixed direction, thereby achieving horizontal alignment of the liquid crystal molecules; A1 and A2 are polymerizable groups, which can increase the crosslinking density of the alignment layer obtained after the liquid crystal additive is polymerized, thus becoming a film layer with stable and firm alignment properties.

[0016] Therefore, the liquid crystal additive provided in this application can be added to the liquid crystal composition to achieve horizontal alignment of liquid crystal compound molecules in the liquid crystal composition without the presence of an azobenzene structure or the need for a PI alignment layer, thereby achieving low-cost liquid crystal alignment while avoiding display problems caused by coloring. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a display panel provided in an embodiment of this application; Figure 2 This is a schematic diagram of another display panel structure provided in an embodiment of this application; Figure 3 This is a schematic diagram of the test of the orientation angle of the liquid crystal cell provided in the embodiment of this application; Figure 4 This is a schematic diagram of the structure of a display device provided in an embodiment of this application.

[0019] Explanation of reference numerals in the attached figures: 1. Display panel; 2. First substrate; 3. Second substrate; 4. First liquid crystal alignment layer; 5. Second liquid crystal alignment layer; 6. Liquid crystal layer; 7. Electrode layer; 8. Pixel; 8a. Upper half domain; 8b. Lower half domain; 9. Backlight module; 10. Display device. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] This application provides a liquid crystal additive, a liquid crystal composition, and a display panel. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms "first", "second", etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0022] This application provides a liquid crystal additive having the chemical structural formula shown in formula (1): (1); Wherein, A is selected from any one of tetravalent phenyl, tetravalent cyclohexyl, tetravalent pyridyl, tetravalent pyrimidinyl, tetravalent naphthyl, tetravalent tetrahydronaphthyl, tetravalent fluorenyl and tetravalent biphenyl; A1 and A2 are independently selected from polymerizable groups containing carbon-carbon double bonds and / or carbon-carbon triple bonds; B1 is selected from the first functional group containing a cinnamic acid ester structure or a chalcone structure; B2 is selected from a second functional group containing a polar group; m and n are independently selected from any integer from 0 to 5.

[0023] It should be noted that the liquid crystal additive shown in formula (1) is a specially designed horizontal liquid crystal alignment agent. It is a small molecule additive with a specially designed structure, which can achieve horizontal alignment of liquid crystal molecules. At the same time, it can replace existing polyimide (PI) liquid crystal alignment materials, reduce the use of polyimide liquid crystal alignment materials, reduce the cost of polyimide liquid crystal alignment materials, and reduce the alignment layer process and save production capacity. In addition, compared with dendritic polymers containing azobenzene structures, the liquid crystal additive shown in formula (1) provided in this application embodiment does not have coloring problems and will not damage the light transmittance and color accuracy of liquid crystal display elements.

[0024] In this embodiment, the liquid crystal additive has the chemical structure shown in formula (1). This liquid crystal additive has high chemical stability and a high ability to horizontally align liquid crystal molecules. By adding this liquid crystal additive to the liquid crystal composition of the liquid crystal cell, horizontal alignment of liquid crystal molecules can be achieved without a PI alignment layer. In the chemical structure of the liquid crystal additive shown in formula (1), the polar group in the B2 group can interact with the substrate of the liquid crystal cell, allowing the liquid crystal additive molecules to adhere to the substrate surface; the B1 group contains a cinnamic acid ester structure or a chalcone structure, which allows the liquid crystal additive molecules to dimerize or isomerize under polarized ultraviolet light irradiation in a non-heated state, causing the liquid crystal additive molecules to align in a fixed direction, thereby achieving horizontal alignment of the liquid crystal molecules; A1 and A2 are polymerizable groups, which can increase the crosslinking density of the alignment layer obtained after the liquid crystal additive is polymerized, thus becoming a film layer with stable and firm alignment properties.

[0025] Therefore, the liquid crystal additives provided in this application embodiment can be added to the liquid crystal composition to achieve horizontal alignment of liquid crystal compound molecules in the liquid crystal composition without the presence of an azobenzene structure or the need for a PI alignment layer, thereby achieving low-cost liquid crystal alignment while avoiding display problems caused by coloring.

[0026] In some embodiments, A is selected from any of the following groups: ; In this context, * represents a bond.

[0027] Understandably, the location of the asterisk (*) is a connection point.

[0028] In some embodiments, the polymerizable group contains any one or more combinations of acryloyloxy, methacryloyloxy, fluoroacrylate, vinyl, vinyloxy, and epoxy groups.

[0029] It is understandable that A1 and A2 in the liquid crystal additive shown in formula (1) are polymerizable groups, which can cause polymerization reactions to occur on both sides of the A group of the main structure at the same time, thereby increasing the crosslinking density of the orientation layer obtained after the liquid crystal additive is polymerized and becoming a film layer with stable and firm orientation properties.

[0030] In some embodiments, the polar group in the second functional group is selected from hydroxyl or phosphate groups.

[0031] It is understandable that the polar groups (e.g., hydroxyl groups) in the B2 group of the liquid crystal additive shown in formula (1) can interact with the substrate of the liquid crystal cell, so that the liquid crystal additive molecules can better adhere to the substrate surface, which is beneficial to improving the connection stability between the alignment layer obtained after the liquid crystal additive is polymerized and the substrate, thereby ensuring alignment stability.

[0032] In some embodiments, m and n are independently selected from any integer from 0 to 3, which is beneficial to improving the flexibility and adaptability of liquid crystal additives.

[0033] For example, the flexibility of small-molecule liquid crystal additives allows them to better embed themselves in the gaps between liquid crystal molecules and move rapidly within these gaps, reducing intermolecular friction and shortening alignment time. The flexibility of small-molecule liquid crystal additives also helps reduce the interaction forces between them and the liquid crystal molecules, thereby improving the chemical stability of both the additives and the molecules. Furthermore, this flexibility makes small-molecule liquid crystal additives easier to dissolve in liquid crystal compositions, eliminating the need for high temperatures or special stirring processes, simplifying the mixing process, and reducing production energy consumption and costs.

[0034] In some embodiments, the liquid crystal additive is selected from any one or more combinations of compounds represented by formulas (1-1) to (1-9): (1-1) (1-2) (1-3) (1-4) (1-5) (1-6) (1-7) (1-8) (1-9); Where m1 and n1 are independently selected from any integer from 1 to 8.

[0035] In a preferred embodiment, m1 and n1 are independently selected from any integer from 2 to 4.

[0036] It is understood that the chemical structural formulas of the liquid crystal additives provided in the embodiments of this application are not limited to the several listed above.

[0037] In one specific embodiment, the liquid crystal additive is selected from any one or a combination of two of the compounds shown in formula (1-1-1) and formula (1-2-1): (1-1-1) (1-2-1).

[0038] Specifically, the synthesis route of the liquid crystal additive shown in equation (1-1-1) is as follows:

[0039]

[0040] .

[0041] Specifically, the preparation process of the liquid crystal additive shown in formula (1-1-1) is as shown in steps (1) to (6).

[0042] (1) 22.8 g (68.6 mmol) of 3-[4-(4-chlorobenzyloxy)-3-methoxyphenyl]-methyl acrylate (the compound shown in Formula 1-1-1-0, CAS: 1269593-03-4) was dissolved in 280 mL of toluene / water (volume ratio 10:1), and Pd(OAc)2 (5-10 mol%), triphenylphosphine (PPh3, 20 mol%) and silver carbonate (Ag2CO3) were added. The reaction mixture was stirred at 80-100 °C for 6-12 hours under atmospheric pressure and nitrogen protection. The catalyst and AgCl precipitate in the reaction mixture were removed by filtration. The reaction mixture was acidified with dilute hydrochloric acid, extracted with ethyl acetate, washed with water and dried under vacuum. The crude product was recrystallized from ethanol / water (volume ratio 1:1) to obtain a colorless solid product (the compound shown in Formula 1-1-1-1).

[0043] The obtained colorless solid product was analyzed by proton nuclear magnetic resonance spectroscopy, and the results are shown below: ¹H NMR (500MHz, CDCl3): δ=3.82ppm(s,3H,Ar-OCH3), 3.85ppm(s,3H,-COOCH3), 5.01ppm(s,2H,-O-CH2-C6H4-OH), 5.28(d,J=11.0 Hz,1H,CH=CH-COOCH3,cis / H_Z), 6.45(d,J=11.0Hz,1H,Ar-CH=CH-,cis / H_E), 6.72(d,J=8.5 6.83 (d, J = 8.2 Hz, 2H, HO-C6H4-CH2-O- ortho-hydrogen), 6.91 (dd, J = 8.2, 2.0 Hz, 1H, Ar-5-hydrogen), 7.05 (d, J = 2.0 Hz, 1H, Ar-2-hydrogen), 7.18 (d, J = 8.5 Hz, 2H, HO-C6H4-CH2-O- para-hydrogen), 8.15 (s, 1H, Ar-OH). Based on the above-described 1H NMR characterization, the obtained colorless solid product can be confirmed as the compound shown in Formula 1-1-1-1, namely methyl 3-[4-(4-hydroxybenzyloxy)-3-methoxyphenyl]-acrylate.

[0044] (2) 21.4 g (67.3 mmol) of methyl 3-[4-(4-hydroxybenzyloxy)-3-methoxyphenyl]-acrylate (Formula 1-1-1-1) was suspended in 400 mL of dichloromethane and 2.00 mL (14.0 mmol) of diisopropylamine was added; 24.00 g (134.8 mmol) of N-bromosuccinimide (NBS) was dissolved in 200 mL of dichloromethane (DCM) and added dropwise to the reaction mixture at room temperature; the reaction mixture was stirred at room temperature for 16 hours, then water was added, the mixture was stirred and the phases were separated; the aqueous phase was extracted with dichloromethane, the combined organic phases were washed with saturated NaCl solution, dried with sodium sulfate, filtered and evaporated under vacuum to give a yellow solid, which was crystallized from heptane (volume ratio 1:5) at 5 °C to give a pale yellow solid product (the compound shown in Formula 1-1-1-2).

[0045] The obtained pale yellow solid product was analyzed by proton nuclear magnetic resonance spectroscopy, and the results are shown below: ¹H NMR (500MHz, CDCl3): δ = 3.81ppm (s, 3H, Ar-OCH3), 3.86ppm (s, 3H, -COOCH3), 5.03ppm (s, 2H, -O-CH2-C6H4-OH), 5.30 (d, J = 11.1Hz, 1H, CH=CH-COOCH3), 6.47 (d, J = 11.1Hz, 1H, Ar-CH=CH-), 6.75 (d, J = 8.6Hz, 2H, HO-C6H4-CH2-O- ortho-hydrogen), 7.19 (d, J = 8.6Hz, 2H, HO-C6H4-CH2-O- para-hydrogen), 7.62 (s, 1H, Ar-2-hydrogen), 7.81 (s, 1H, Ar-6-hydrogen), 8.33 (s (broad), 1H).

[0046] Based on the above-described proton nuclear magnetic resonance (NMR) spectroscopy characterization, it can be confirmed that the obtained colorless solid product is the compound shown in Formula 1-1-1-2.

[0047] (3) Dissolve 8.70 g (20.36 mmol) of the compound shown in Formula 1-1-1-2, 11.32 g (25.5 mmol) of alcohol S (which can be synthesized according to the method described in EP2918658A2) and 6.70 g (25.55 mmol) of triphenylphosphine in 70.0 mL of tetrahydrofuran, and then add 5.30 mL (27.00 mmol) of diisopropyl azodicarbonate (DIAD) dropwise; stir the reaction mixture at room temperature for 16 hours, and then evaporate under vacuum; filter the resulting solid through silica gel with heptane and heptane / ethyl acetate (volume ratio 9:1), combine the product fractions and evaporate under vacuum to give a yellow solid product (the compound shown in Formula 1-1-1-3).

[0048] (4) Dissolve 26.5 g (38.0 mmol) of the compound shown in Formula 1-1-1-3 in 371.3 mL of tetrahydrofuran, add 59.6 g (420.1 mmol) of 2-butoxy-1,2-oxabortane; dissolve 18.13 g (171.1 mmol) of sodium carbonate in 96.4 mL of water and pour it into the above reaction mixture; add 0.53 mL (3.81 mmol) of triethylamine, 0.80 g (4.58 mmol) of palladium(II) chloride and 4.28 g (9.17 mmol) of triethylamine to the reaction mixture in sequence. 2-Dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl (RuPhos); The reaction mixture was stirred at 80 °C for 72 hours. After the reaction mixture was cooled to room temperature, water and methyl tert-butyl ether were added, the mixture was stirred and the phases were separated. The aqueous phase was extracted with methyl tert-butyl ether, the combined organic phases were washed with saturated NaCl solution, dried over sodium sulfate, filtered and evaporated under vacuum. The resulting orange-yellow oil was filtered through silica gel with heptane / ethyl acetate (volume ratio 8:2), the product fractions were combined and evaporated under vacuum to give a pale yellow oily product (the compound shown in Formula 1-1-1-4).

[0049] (5) 11.8 g (13.0 mmol) of the compound shown in Formula 1-1-1-4 and 4.5 mL (53.1 mmol) of methacrylic acid were dissolved in 60 mL of dichloromethane and cooled to 2 °C. Then, 9.10 mL (52.8 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC) was added dropwise to 40 mL of dichloromethane solution containing the compound shown in Formula 1-1-1-4 and methacrylic acid. The reaction mixture was heated to room temperature and stirred for 16 hours. The reaction mixture was evaporated under vacuum and filtered through a silica gel column with alkaline Al2O3 as the upper layer. The product fractions were eluted sequentially with dichloromethane and dichloromethane / methyl tert-butyl ether (volume ratio 95:5). The product fractions were combined and evaporated under vacuum to obtain a colorless oily product (the compound shown in Formula 1-1-1-5).

[0050] The obtained colorless oily product was analyzed by 1H NMR spectroscopy, and the results are shown below: ¹H NMR (500MHz, CDCl3): δ=0.05ppm (s, 12H, 2×Si-(CH3)2), 0.86ppm (s (overlapping), 21H, 2×Si-C(CH3)3, -CH2CH2CH2CH3 terminal methyl), 0.92-1.08 (m, 2H, -Si-CH2-CH2CH2CH3), 1.28-1.36 (m, 2H, -Si-CH2-CH2CH2CH3), 1.54-1.62 (m, 2H, -Si-CH2-CH2CH2CH3), 1.75 (m, 4H, 2×-CH2- CH2-COO-intermediate methylene), 1.93 (s, 6H, 2×CH2=C(CH3)-COO-methyl), 2.68 (t, J=7.6Hz, 4H, 2×Ar-CH2-CH2-aromatic ring ortho-methylene), 3.81ppm (s, 3H, Ar-OCH3), 3.85ppm (s, 3H, -COOCH3), 3.90-4.03 (m, 6H, -O-CH2-CH(O)-CH2-O-CH2-CH2-O-oxoheterocyclic and dioxoheterocyclic methylene hydrogen), 4.15 (t, J=6.6Hz, 4H, 2×-CH2-OOC-C (CH3)=CH2 ester group ortho-methylene), 4.33 (d, J = 4.8 Hz, 1H, -O-CH(O)-CH2-oxocyclic methine hydrogen), 5.01 ppm (s, 2H, -O-CH2-C6H4-O-), 5.29 (d, J = 11.0 Hz, 1H, CH=CH-COOCH3), 5.53 (t, J = 1.6 Hz, 2H, 2×CH2=C(CH3)-COO-cis) (Hydrogen), 6.07 (s, 2H, 2×CH2=C(CH3)-COO-trans hydrogen), 6.46 (d, J=11.0Hz, 1H, Ar-CH=CH-), 6.73 (d, J=8.5Hz, 2H, -O-C6H4-CH2-O-ortho hydrogen), 6.86 (s, 1H, Ar-4 hydrogen), 7.17 (d, J=8.5Hz, 2H, -O-C6H4-CH2-O-para hydrogen).

[0051] Based on the above-described proton nuclear magnetic resonance (NMR) characterization, it can be confirmed that the obtained colorless oily product is the compound shown in Formula 1-1-1-5.

[0052] (6) Dissolve 5.9 g (5.0 mmol) of the compound shown in Formula 1-1-1-5 in 40 mL of tetrahydrofuran and cool to 2 °C; then add 7.00 mL (14.0 mmol) of hydrochloric acid (2N) dropwise; heat the reaction mixture to room temperature and stir for 4 hours; after deprotection, neutralize the reaction mixture to pH 7-8 with saturated NaHCO3 solution, add methyl tert-butyl ether, stir and separate the phases; extract the aqueous phase with methyl tert-butyl ether, wash the combined organic phases with water and saturated NaCl solution, dry with anhydrous sodium sulfate, filter and evaporate under vacuum at the highest temperature of 40 °C; filter the crude product with heptane / ethyl acetate (volume ratio 1:1) through silica gel, combine the product fractions and evaporate under vacuum; crystallize the obtained solid from heptane / methyl tert-butyl ether (volume ratio 95:5) (dissolved by heating at 60 °C), precipitate as a colorless solid at room temperature, and obtain the product by suction filtration. The product is confirmed to be the compound shown in Formula 1-1-1 by nuclear magnetic resonance hydrogen spectroscopy.

[0053] Specifically, the 1H NMR spectrum of the product from step (6) is shown below: ¹H NMR (500MHz, CDCl3): δ=0.96ppm (t, J=7.3Hz, 3H), 1.21-1.33 (m, 6H), 1.52-1.63 (m, 2H), 1.63ppm (m, 4H), 1 .90ppm (m, 4H), 1.93ppm (s, 6H), 2.55ppm (t, J=7.6Hz, 4H), 3.45ppm (t, J=6.2Hz, 4H), 3.73ppm (s, 3H), 3.76 ppm (s, 3H), 3.94ppm (m, 8H), 4.15ppm (t, J=6.6Hz, 4H), 2.0ppm (br s, 2H, -OH), 5.20ppm (s, 2H), 5.58ppm (t, J=1.6Hz, 2H), 6.15ppm (br s, 2H), 6.39ppm (d, J=11.0Hz, 1H), 6.61-6.76ppm (m, 5H), 7.64ppm (d, J=11.0Hz, 1H).

[0054] Specifically, the compound shown in Formula 1-2-1 can be synthesized by first referring to the synthetic route of Formula 1-1-1 to obtain the compound described in Formula 1-2-1-1, and then using the following route to obtain the compound shown in Formula 1-2-1: .

[0055] The product obtained through the above synthetic route was confirmed by 1H NMR spectroscopy to be the compound shown in Formula 1-2-1. The 1H NMR spectroscopy results of the product are shown below: ¹H NMR (500MHz, CDCl3): δ=2.00 (s, 2H), 1.93 (s, 6H), 1.90 (m, 4H), 2.55 (m, 4H), 3.73 (s, 3H), 3.76 (s, 3H), 4.00 (m), 4.15 (t, J≈6.3Hz, 4H), 5.20 (m, 2H), 5.58 (d, J≈1.5Hz, 2H), 6.15 (d, J≈1.5Hz, 2H), 6.39 (m, 1H), 6.61 (s, 1H), 6.70 (s, 1H), 6.75 (s, 1H), 6.76 (s, 2H), 7.64 (m,1H).

[0056] It is understood that other liquid crystal additives provided in the embodiments of this application can be prepared by referring to the above synthesis route.

[0057] In this embodiment, the liquid crystal additive has the chemical structure shown in formula (1). This liquid crystal additive has high chemical stability and a high ability to horizontally align liquid crystal molecules. By adding this liquid crystal additive to the liquid crystal composition of the liquid crystal cell, horizontal alignment of liquid crystal molecules can be achieved without a PI alignment layer. In the chemical structure of the liquid crystal additive shown in formula (1), the polar group in the B2 group can interact with the substrate of the liquid crystal cell, allowing the liquid crystal additive molecules to adhere to the substrate surface; the B1 group contains a cinnamic acid ester structure or a chalcone structure, which allows the liquid crystal additive molecules to dimerize or isomerize under polarized ultraviolet light irradiation in a non-heated state, causing the liquid crystal additive molecules to align in a fixed direction, thereby achieving horizontal alignment of the liquid crystal molecules; A1 and A2 are polymerizable groups, which can increase the crosslinking density of the alignment layer obtained after the liquid crystal additive is polymerized, thus becoming a film layer with stable and firm alignment properties.

[0058] Therefore, the liquid crystal additives provided in this application embodiment can be added to the liquid crystal composition to achieve horizontal alignment of liquid crystal compound molecules in the liquid crystal composition without the presence of an azobenzene structure or the need for a PI alignment layer, thereby achieving low-cost liquid crystal alignment while avoiding display problems caused by coloring.

[0059] This application also provides a liquid crystal composition comprising at least one liquid crystal compound and at least one liquid crystal additive described in the foregoing embodiments.

[0060] It should be noted that the liquid crystal compound in the liquid crystal composition described in this application refers to a liquid crystal monomer used to adjust the luminous flux through the electro-optic effect. For FFS-type display products, the liquid crystal composition consists of at least one of the liquid crystal compounds and at least one or more of the liquid crystal additives described. For vertical alignment (VA)-type display products, a polymerizable compound (RM) may also be added to the liquid crystal composition to react with the liquid crystal additives to form a liquid crystal alignment layer. This application uses an FFS-type display product as an example for illustration.

[0061] In some embodiments, the liquid crystal additive in the liquid crystal composition is 0.01% to 20% by mass.

[0062] For example, when the liquid crystal composition comprises at least one of the liquid crystal compounds and at least one or more of the liquid crystal additives, the mass percentage of the liquid crystal additives is 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, or 20%.

[0063] In some embodiments, the liquid crystal compound is selected from mass-produced Merck liquid crystal LCCC-22-740, but is not limited thereto.

[0064] In a preferred embodiment, the liquid crystal additive is selected from any one or a mixture of two of the compounds shown in Formula 1-1-1 and Formula 1-2-1, but is not limited thereto.

[0065] It is understood that the liquid crystal composition provided in the embodiments of this application can be used to manufacture the liquid crystal layer and liquid crystal alignment layer in a liquid crystal display panel.

[0066] In some embodiments, the process of preparing a liquid crystal alignment film using the liquid crystal composition includes the following steps: A first substrate and a second substrate are provided that are disposed opposite to each other; A liquid crystal composition is added between the first substrate and the second substrate; wherein the liquid crystal composition comprises at least one liquid crystal compound and at least one liquid crystal additive of formula (1); At room temperature, the liquid crystal composition is phototreated with linearly polarized ultraviolet light to form a liquid crystal alignment layer on the first substrate and / or the second substrate.

[0067] Specifically, the first substrate is selected from an array substrate, and the second substrate is selected from a color filter (CF) substrate, or vice versa. In other embodiments, the first substrate may also be an opposing substrate, and the second substrate may be an array substrate with a color filter layer, or vice versa.

[0068] Specifically, the liquid crystal composition is added to the empty cell formed between the first substrate and the second substrate by an injection method (e.g., depressurized injection), but is not limited thereto.

[0069] Specifically, the wavelength range of the linearly polarized ultraviolet light is 200 nanometers to 380 nanometers, and the energy density range of the linearly polarized ultraviolet light is 0.1 J / cm². 2 Up to 20J / cm 2 .

[0070] In one specific embodiment, the wavelength of the linearly polarized ultraviolet light is 313 nanometers, and the energy density of the light at the preset wavelength is 5 J / cm². 2 However, it is not limited to this.

[0071] Understandably, the wavelength and energy density of linearly polarized ultraviolet light can be adjusted according to actual conditions, and are not limited to the exemplary parameters listed above.

[0072] In some embodiments, the liquid crystal alignment layer formed using the liquid crystal composition is formed on the side of the first substrate near the second substrate, and a PI alignment layer is formed on the second substrate before the first substrate and the second substrate are positioned opposite each other. Alternatively, the liquid crystal alignment layer formed using the liquid crystal composition is formed on the side of the second substrate near the first substrate, and a PI alignment layer is formed on the first substrate before the first substrate and the second substrate are positioned opposite each other.

[0073] It is understood that the liquid crystal alignment layer formed by the liquid crystal additive in this application embodiment is only formed on the first substrate or the second substrate. That is to say, this application can replace only the PI alignment film on the first substrate or the second substrate side. This design can reduce the use of PI material on one side, reduce the material cost of PI, and reduce the manufacturing process of PI alignment film, which is conducive to saving production capacity.

[0074] It should be noted that since a PI alignment layer is formed on one of the first and second substrates, the PI alignment layer can align the liquid crystal molecules, thereby making the alignment state of the liquid crystal compound after implantation treatment a weak horizontal alignment relative to the first and second substrates. When the side of the substrate without the PI alignment layer is exposed to linearly polarized ultraviolet light in a non-heated state, the liquid crystal additives in the liquid crystal composition will undergo photoisomerization or dimerization, and a polymerization reaction will also occur, thereby forming a stable liquid crystal alignment film on the substrate without the PI alignment layer, so that the alignment state of the liquid crystal compound changes to a strong horizontal alignment relative to the first and second substrates.

[0075] Of course, in other embodiments, the liquid crystal alignment layer formed using the liquid crystal composition is formed on the side of the first substrate near the second substrate and on the side of the second substrate near the first substrate. That is, this application can replace only the PI alignment film on the first substrate and the second substrate side. This design can reduce the use of PI material on both sides, further reducing the material cost of PI, and further reducing the PI alignment film manufacturing process, which is beneficial for further saving production capacity.

[0076] Therefore, the liquid crystal additive provided in this application embodiment can be used in the case where there is no PI alignment layer on both sides, or in the case where there is a PI alignment layer on one side.

[0077] In this embodiment of the application, the liquid crystal composition containing the liquid crystal additive shown in formula (1) can be used to form the liquid crystal layer and liquid crystal alignment layer of the liquid crystal cell during the liquid crystal cell assembly process. The liquid crystal alignment layer has a simple process and can achieve horizontal alignment of liquid crystal molecules, thereby replacing the existing polyimide liquid crystal alignment material, reducing the use of polyimide liquid crystal alignment material, reducing the cost of polyimide liquid crystal alignment material, and reducing the process to save production capacity.

[0078] like Figure 1 and Figure 2 The embodiment shown in this application also provides a display panel 1, which includes: The first substrate 2 and the second substrate 3 are arranged opposite to each other; A liquid crystal layer 6 sandwiched between the first substrate 2 and the second substrate 3; The first liquid crystal alignment layer 4 is disposed on the side of the first substrate 2 near the liquid crystal layer 6; The second liquid crystal alignment layer 5 is disposed on the side of the second substrate 3 near the liquid crystal layer 6; The materials of the first liquid crystal alignment layer 4 and / or the second liquid crystal alignment layer 5 are selected from photo-alignment polymers, and the monomers of the photo-alignment polymers are selected from at least one of the liquid crystal additives described in the foregoing embodiments.

[0079] It is understood that the photo-aligned polymer is formed from at least one of the liquid crystal additives described in the foregoing embodiments through photoisomerization or dimerization and polymerization. Furthermore, the liquid crystal layer 6 and the liquid crystal alignment layer made of the photo-aligned polymer are prepared from the liquid crystal composition described in the foregoing embodiments. The liquid crystal material in the liquid crystal layer 6 is the liquid crystal compound in the liquid crystal composition.

[0080] In one specific embodiment, such as Figure 2 As shown, the materials of the first liquid crystal alignment layer 4 and the second liquid crystal alignment layer 5 are both selected from the photo-alignment polymer.

[0081] In other specific embodiments, such as Figure 1 As shown, the material of the first liquid crystal alignment layer 4 is selected from the photo-alignment polymer, and the material of the second liquid crystal alignment layer 5 includes polyimide. That is, the second liquid crystal alignment layer 5 is a PI alignment layer.

[0082] In some embodiments, the first substrate 2 is a color filter substrate and the second substrate 3 is an array substrate, but not limited thereto.

[0083] In some embodiments, an electrode layer 7 is further provided between the second substrate 3 and the second liquid crystal alignment layer 5. The electrode layer 7 can be a pixel electrode or a common electrode, and there is no limitation on this.

[0084] This application also provides a set of comparative examples and two sets of embodiments. The comparative examples provide a comparative liquid crystal cell, and the embodiments provide a first experimental liquid crystal cell and a second experimental liquid crystal cell, respectively. The alignment effect of the liquid crystal alignment layer formed by the above-mentioned organic compound was verified by the three liquid crystal cells prepared by liquid crystal compositions of three different materials.

[0085] (a) Liquid crystal configuration and liquid crystal cell manufacturing a. Liquid crystal preparation: Using mass-produced Merck liquid crystal LCCC-22-740 as the master liquid crystal, 5% by mass of the liquid crystal additives shown in Formula 1-1-1 and Formula 1-2-1 were mixed in two identical portions of the master liquid crystal to obtain the first experimental liquid crystal composition and the second experimental liquid crystal composition, which are referred to as Example 1 and Example 2, respectively.

[0086] b. Liquid crystal cell assembly: Nissan RB053 polyimide (PI) solution is coated on a thoroughly cleaned thin film transistor (TFT) substrate. After the polyimide solution on the TFT substrate is cured, the obtained PI alignment film is subjected to photoalignment or rubbing treatment to obtain an anisotropic PI alignment film on the TFT substrate. A sealant was printed between a thoroughly cleaned color filter (CF) substrate and a TFT substrate with a PI alignment film (except at the liquid crystal injection port), and then they were bonded together. The sealant was then cured to create an empty cell with a cell gap of 3.0 μm. Additive-free master phase liquid crystal (a control liquid crystal composition, designated as the comparative example), a first experimental liquid crystal composition, and a second experimental liquid crystal composition were injected into three identical empty cells using a depressurized injection method. The injection ports were then sealed to obtain a control liquid crystal cell, a first experimental liquid crystal cell, and a second experimental liquid crystal cell, respectively. Then, at room temperature, the three liquid crystal cells were subjected to a force of 5 J / cm from the normal direction. 2 Irradiation with linearly polarized ultraviolet light at an energy density of 313 nm promotes the photoisomerization or dimerization of liquid crystal additive monomers in the first and second experimental liquid crystal cells. The photoisomerized or dimerized compounds align in a fixed direction, and photopolymerization also occurs between the liquid crystal additive monomers during the photoisomerization or dimerization process, thereby forming a thin film on the CF substrate. This thin film functions as a liquid crystal alignment film. Through the above steps, the first experimental alignment film and the second experimental alignment film are formed in the first and second experimental liquid crystal cells, respectively.

[0087] Understandably, the structures of the first and second experimental liquid crystal cells are similar to... Figure 1 The structure of the display panel 1 shown is the same.

[0088] (II) Evaluation methods and results of the optical performance of liquid crystal cells The optical performance of the comparative liquid crystal cell, the first experimental liquid crystal cell, and the second experimental liquid crystal cell provided in the aforementioned comparative examples, Example 1, and Example 2 was tested, and the results are shown in Table 1.

[0089] 1. Evaluation methods for the uniformity of horizontal orientation: The three types of liquid crystal cells described above are horizontally positioned within polarizers with orthogonal polarization axes. The orientation direction of the liquid crystal molecules is 0 degrees to the polarization axis of the lower polarizer. Light is shone from the lower polarizer side, and the presence or absence of light transmitted through the polarizer is observed. If no light is observed to transmit through the polarizer (dark state), the orientation is determined to be "good." The liquid crystal cell is then horizontally rotated within the polarizer. The intensity of light transmitted through the polarizer increases as the angle between the polarizer's transmission axis and the orientation direction of the liquid crystal molecules increases, reaching approximately its maximum at 45 degrees. In the liquid crystal cell obtained through this method, the liquid crystal molecules are oriented approximately horizontally relative to the main surface of the substrate, and this is determined to be "horizontal orientation."

[0090] 2. Evaluation of image retention caused by long-term interaction: Using the liquid crystal cell fabricated above, an AC voltage of ±6V at a frequency of 60Hz was applied for 48 hours in a constant temperature environment of 25°C. Then, the pixel electrode and the counter electrode of the liquid crystal cell were short-circuited, and the cell was left to stand at room temperature for one day. After this period, the liquid crystal cell was placed between two polarizers arranged orthogonally to their polarization axes. With no voltage applied, the backlight was turned on, and the arrangement angle of the liquid crystal cell was adjusted to minimize the brightness of the transmitted light. Then, as... Figure 3 As shown, the orientation angles of the upper half-domain 8a and lower half-domain 8b of 10 pixels (8) were measured before and after applying voltage at the same position. The difference in orientation angles between the upper half-domain 8a and lower half-domain 8b before and after applying voltage was recorded and denoted as angle. 初始态 and angle aging态 Δangle = angle aging态 -angle 初始态 .

[0091] 3. Contrast measurement: The brightness of a liquid crystal cell placed under crossed polarizers is measured in the dark state, which is the brightness transmitted through the polarizer. When a voltage is applied to the liquid crystal and the cell reaches its maximum brightness, this brightness is measured as the bright state brightness. Contrast ratio = bright state brightness / dark state brightness.

[0092] Table 1

[0093] As shown in Table 1, compared with the comparative examples, Examples 1 and 2, by adding the liquid crystal additives provided in the embodiments of this application to the liquid crystal compound, achieved good horizontal alignment of liquid crystal molecules even without a PI alignment film on one side, and the liquid crystal molecules were aligned in a fixed horizontal direction. Furthermore, compared with the comparative examples, the contrast ratio of the liquid crystal cells provided in Examples 1 and 2 was significantly improved, indicating that the display panel using the liquid crystal cells provided in Examples 1 and 2 would have a significantly improved display contrast ratio, thereby improving the display effect. Moreover, compared with the comparative examples, the AC image retention of the liquid crystal cells provided in Examples 1 and 2 was significantly reduced, further demonstrating that the display effect of the display panel using the liquid crystal cells provided in Examples 1 and 2 can be significantly improved.

[0094] In this embodiment, the liquid crystal alignment layer on the first substrate 2 and / or the second substrate 3 in the display panel 1 is made by the liquid crystal additive. The process is simple and easy to implement, and can reduce the number of process steps, save production capacity, and reduce PI cost. It has positive significance for the development of green manufacturing processes.

[0095] like Figure 4As shown, this application embodiment also provides a display device 10, which includes the display panel 1 and backlight module 9 described in the foregoing embodiment, wherein the display panel 1 is located on the light-emitting side of the backlight module 9.

[0096] It should be noted that the structure of the backlight module 9 is not limited in the embodiments of this application.

[0097] It should be noted that the application of the liquid crystal additive shown in general formula (1) provided in the embodiments of this application in the preparation of liquid crystal compositions, liquid crystal display materials or optoelectronic display element materials without PI alignment layers and having horizontal alignment, as well as liquid crystal compositions, liquid crystal display materials or electro-optical display element materials containing the liquid crystal additive shown in formula (1), are also within the scope of protection of this application.

[0098] The above provides a detailed description of a liquid crystal additive, liquid crystal composition, and display panel provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A liquid crystal additive, characterized in that, The liquid crystal additive has the chemical structural formula shown in formula (1): （1）； Wherein, A is selected from any one of tetravalent phenyl, tetravalent cyclohexyl, tetravalent pyridyl, tetravalent pyrimidinyl, tetravalent naphthyl, tetravalent tetrahydronaphthyl, tetravalent fluorenyl and tetravalent biphenyl; A1 and A2 are independently selected from polymerizable groups containing carbon-carbon double bonds and / or carbon-carbon triple bonds; B1 is selected from the first functional group containing a cinnamic acid ester structure or a chalcone structure; B2 is selected from a second functional group containing a polar group; m and n are independently selected from any integer from 0 to 5.

2. The liquid crystal additive according to claim 1, characterized in that, A is selected from any of the following groups: ； In this context, * represents a bond.

3. The liquid crystal additive according to claim 1, characterized in that, The polymerizable group contains any one or more combinations of acryloyloxy, methacryloyloxy, fluoroacrylate, vinyl, vinyloxy, and epoxy groups.

4. The liquid crystal additive according to claim 1, characterized in that, The polar group in the second functional group is selected from hydroxyl or phosphate groups.

5. The liquid crystal additive according to any one of claims 1 to 4, characterized in that, The liquid crystal additive is selected from any one or more combinations of compounds shown in formulas (1-1) to (1-9): （1-1） （1-2） （1-3） （1-4） （1-5） （1-6） （1-7） （1-8） （1-9）； Where m1 and n1 are independently selected from any integer from 1 to 8.

6. The liquid crystal additive according to claim 5, characterized in that, The liquid crystal additive is selected from any one or a combination of two of the compounds shown in formula (1-1-1) and formula (1-2-1): （1-1-1） （1-2-1）。 7. A liquid crystal composition, characterized in that, It includes at least one liquid crystal compound and at least one liquid crystal additive as described in any one of claims 1 to 6.

8. The liquid crystal composition according to claim 7, characterized in that, In the liquid crystal composition, the liquid crystal additive has a mass percentage of 0.01% to 20%.

9. A display panel, characterized in that, include: A first substrate and a second substrate arranged opposite to each other; A liquid crystal layer sandwiched between the first substrate and the second substrate; A first liquid crystal alignment layer is disposed on the side of the first substrate near the liquid crystal layer; A second liquid crystal alignment layer is disposed on the side of the second substrate near the liquid crystal layer; Wherein, the material of the first liquid crystal alignment layer and / or the material of the second liquid crystal alignment layer are selected from photo-alignment polymers, and the monomers of the photo-alignment polymers are selected from at least one of the liquid crystal additives according to any one of claims 1 to 6.

10. The display panel according to claim 9, characterized in that, The material of the first liquid crystal alignment layer is selected from the photo-alignment polymer, and the material of the second liquid crystal alignment layer includes polyimide.

Images