A positive frequency conversion display liquid crystal material

Abstract

The present invention discloses a positive variable frequency display liquid crystal material, belonging to the technical field of variable frequency display materials. The material, calculated by the total mass fraction of 100%, includes the following components: at least one or more compounds having the structure shown in general formula I, with a mass fraction of 1% to 25%; at least one or more compounds having the structure shown in general formula II, with a mass fraction of 2% to 70%; at least one or more compounds having the structure shown in general formula III, with a mass fraction of 2% to 40%; at least one or more compounds having the structure shown in general formula IV, with a mass fraction of 2% to 35%. The material of the present invention has a large elastic constant and a low rotational viscosity, can respond quickly and is suitable for different usage scenarios.

Description

Technical Field

[0001] The invention belongs to the technical field of frequency conversion display materials, and in particular relates to a positive frequency conversion display liquid crystal material. Background Art

[0002] IPS display mode has high contrast, wide viewing angle and low color deviation, and is widely used in display products. With the advancement of display technology and the improvement of people's living standards, people have higher requirements for display quality and display experience. At the same time, in order to adapt to the requirements of modern society for environmental protection, it is necessary to reduce power consumption and save electricity. Variable frequency LCD can be applied to different usage scenarios. For example, high frequency drive is used when displaying dynamic images, and low frequency drive can be used when displaying static images, which further reduces power loss.

[0003] However, positive ordinary liquid crystals are prone to flickering when driven at low frequencies, resulting in blurred and poor display images; when driven at high frequencies, power consumption is high. Therefore, a variable frequency display liquid crystal material that is suitable for both high and low frequency usage scenarios and can switch quickly is needed. Summary of the invention

[0004] Technical problem to be solved: In response to the above technical problem, the present invention provides a positive frequency-variable display liquid crystal material, which has a large elastic constant and a low rotational viscosity, can respond quickly and is suitable for different usage scenarios.

[0005] Technical solution: A positive frequency conversion display liquid crystal material, calculated by total mass fraction of 100%, includes the following components:

[0006] Contains at least one or more compounds having a structure shown in general formula I, with a mass fraction of 1% to 25%, and general formula I is:

[0007]

[0008] Wherein, R1 represents a C1-C7 straight chain alkyl or straight chain alkenyl, and Y1 represents H or F substitution;

[0009] At least one or more compounds having a structure shown in general formula II, with a mass fraction of 2% to 70%, and general formula II is:

[0010]

[0011] Wherein, R2 represents a C1-C6 straight-chain alkyl group, R3 represents a C1-C7 straight-chain alkyl group or a C1-C5 straight-chain alkenyl group, and ring A1 and ring A2 each independently represent:

[0012] At least one or more compounds having a structure shown in general formula III are contained, and the mass fraction thereof is 2% to 40%. General formula III is:

[0013]

[0014] Wherein, R4 represents a C1-C5 straight chain alkyl group, R5 represents a C1-C5 straight chain alkyl group or -OCF3, substituted, Y2 represents H or F atom substitution, and rings A3 to A5 each independently represent:

[0015] At least one or more compounds having a structure shown in general formula IV, with a mass fraction of 2% to 35%, and general formula IV is:

[0016]

[0017] Wherein, R6 represents a C1-C5 straight chain alkyl group, Z represents -CF2O-, Y3 represents H or F atom substitution, and ring A6 represents:

[0018] Preferably, the compound represented by general formula I is selected from one or more of the following formulae:

[0019]

[0020]

[0021] Preferably, the compound represented by general formula II is selected from one or more of the following formulae:

[0022]

[0023]

[0024] Preferably, the compound represented by general formula III is selected from one or more of the following formulae:

[0025]

[0026]

[0027] Preferably, the compound represented by general formula IV is selected from one or more of the following formulae:

[0028]

[0029]

[0030] Preferably, the material comprises, by mass fraction, 2-20% of the compound represented by general formula I, 2-65% of the compound represented by general formula II, 2-35% of the compound represented by general formula III and 2-30% of the compound represented by general formula IV.

[0031] Preferably, the material further comprises 0 to 15% by mass of one or more compounds having a structure represented by general formula V, wherein the general formula V is:

[0032]

[0033] Here, R7 represents a C1-C5 straight-chain alkyl group.

[0034] Preferably, the compound represented by general formula V is selected from one or more of the following formulae:

[0035]

[0036] Preferably, the material also includes 2-15% by mass of the compound represented by general formula I, 2-60% by mass of the compound represented by general formula II, 2-30% by mass of the compound represented by general formula III, 2-25% by mass of the compound represented by general formula IV and 0-7% by mass of the compound represented by general formula V.

[0037] The positive frequency conversion display liquid crystal material is used in the IPS display mode.

[0038] Beneficial effects: The liquid crystal material of the present invention has moderate clearing point, appropriate refractive index, large elastic constant, good low-temperature miscibility and fast response time.

[0039] The present invention can display normally at low frequency and high frequency, and has the functions of fast response (response time is within 6ms) and high-quality display. The liquid crystal material has the characteristics of large K value, low viscosity and fast response, and can be applied to the field of variable frequency liquid crystal in IPS display mode. Common ordinary liquid crystal has a relatively small K value, especially positive ordinary liquid crystal, most of the K values ​​are around 12.5. The smaller K value leads to weak recovery ability of liquid crystal, which slows down the response speed. And the flicker phenomenon is generated at low frequency, resulting in blurred display and poor picture. Liquid crystal with large K value and fast response speed can reduce power consumption when driven at low frequency, and will not produce flicker to deteriorate the picture quality. Variable frequency liquid crystal can be applied to different usage scenarios, such as high-frequency drive when displaying dynamic pictures, and low-frequency drive when displaying static pictures, to further reduce power consumption loss. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments.

[0041] The abbreviated codes for the test items in the following embodiments are as follows:

[0042] Tni: clearing point (℃)

[0043] no: refractive index of ordinary light (589nm, 25℃)

[0044] ne: refractive index of extraordinary light (589nm, 25℃)

[0045] Δn: refractive index anisotropy (589nm, 25℃);

[0046] T: response time measured at 25°C (ms)

[0047] Δε: dielectric anisotropy (1Khz, 25℃);

[0048] Among them, Δε=ε∥-ε ⊥ , where ε∥ is the dielectric constant parallel to the molecular axis, ε⊥ is the dielectric constant perpendicular to the molecular axis, and the test conditions are: 25℃, 1KHz.

[0049] K11: splay elastic constant

[0050] K33: Bending elastic constant

[0051] γ1: represents the rotational viscosity [mPa·s] measured at 25°C and 20 μm cell thickness, measured by LCM-2.

[0052] VHR: Voltage holding ratio, measured by LCM-2 under the test conditions (5V, 6Hz, 60℃).

[0053] In the following examples, the group structures in the liquid crystal compounds are represented by the codes shown in Table 1.

[0054] Table 1: Liquid crystal compound functional group code

[0055]

[0056] Take the following compound structure as an example:

[0057]

[0058] Functional group code: 5PGUQUF

[0059]

[0060] Functional group code: 3PPUF

[0061] According to the mass percentage in the embodiment, weigh the compound of the corresponding general structure, place the weighed monomer in a hard borosilicate glass bottle, heat it under nitrogen protection, stir it by electromagnetic or mechanical stirring until it becomes a molten, clear, uniform and transparent solution, and continue stirring for 30 minutes to make the materials thoroughly and evenly mixed, then stop heating. Degas under reduced pressure while stirring; as the temperature decreases, the vacuum degree increases until the temperature cools to room temperature, stop stirring, and continue to evacuate until no bubbles appear. Then it can be poured into the test box for testing.

[0062] Example 1

[0063]

[0064]

[0065] From Example 1, it can be found that the material has a large K value, low rotational viscosity, fast response time, and excellent quality parameters, which greatly improves the quality of the liquid crystal display device.

[0066] Example 2

[0067]

[0068] Example 3

[0069]

[0070]

[0071] Example 4

[0072]

[0073] Example 5

[0074]

[0075] Example 6

[0076]

[0077] Example 7

[0078]

[0079] Comparative Example 1

[0080]

[0081] The performance parameter values ​​of the liquid crystal materials obtained in Example 1, Comparative Example 1 and Comparative Example 2 (CN 109251749 A) ​​are summarized and compared, as shown in the following table:

[0082]

[0083] A comparison of the three shows that the liquid crystal material of Example 1 has a larger elastic constant, a lower viscosity rotation, and a better response speed. Compared with Comparative Example 1, the K11 bending elastic number of Example 1 is increased by about 12%, and the K33 bending constant is increased by about 5%; compared with Comparative Example 2, it also has an increased elastic constant and a lower rotational viscosity.

[0084] It can be seen from the above embodiments that the liquid crystal material provided by the present invention has a large elastic constant, wherein a large flexure constant (K11) can enhance the recovery ability of the liquid crystal itself, so that the liquid crystal can work normally even when driven at a low frequency, and will not produce a flicker phenomenon, resulting in poor image quality. When displaying dynamic images, a high-frequency drive is used, and when displaying static images, a low-frequency drive can be used to further reduce power consumption losses. At the same time, a larger K11 can increase the response speed of the liquid crystal. The product also has a lower rotational viscosity, which greatly improves the response speed of the liquid crystal.

Claims

1. A positive frequency conversion display liquid crystal material, characterized in that: Based on the total mass fraction of 100%, it includes the following components: Wherein, Z represents -CF2O-.

2. A positive frequency conversion display liquid crystal material, characterized in that: Based on the total mass fraction of 100%, it includes the following components: Wherein, Z represents -CF2O-.

3. Application of the positive frequency-variable display liquid crystal material according to claim 1 or 2 in an IPS display mode.

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