TWI863632B - Low refractive index liquid crystal composition, liquid crystal display element and liquid crystal display - Google Patents

Abstract

The present invention relates to a low refractive index liquid crystal composition, and a liquid crystal display element and a liquid crystal display comprising the liquid crystal composition, belonging to the field of liquid crystal display. The liquid crystal composition comprises a compound represented by formula I and a compound represented by formula II with a mass content of ≥50%. The liquid crystal composition has a low scattering coefficient and good reliability, and has obvious advantages in display fields such as medical equipment, full reflection screens, and 3D printing.

Description

Low refractive index liquid crystal composition, liquid crystal display element and liquid crystal display

The present invention belongs to the field of liquid crystal display, and more specifically, relates to a liquid crystal composition with a low refractive index and a liquid crystal display element and a liquid crystal display comprising the liquid crystal composition.

The LCD displays of existing electronic products such as televisions, mobile phones, and computers all rely on backlights to emit light. Watching LCD displays for a long time will cause certain damage to the eyes. In order to reduce the damage to the eyes caused by LCD displays, people will control the time they watch electronic products such as televisions, mobile phones, and computers to reduce eye irritation. However, with the advancement of science and technology and the popularization of electronic products, people's daily life, production, and learning are increasingly inseparable from electronic products. Then how to reduce the damage to the eyes caused by LCD displays of electronic products has become an important topic for researchers. At present, the LCD displays on the market are all displayed through the backlight brightness. If the backlight source of the display can be changed to natural light, the irritation to the eyes will be greatly reduced, and it will definitely be welcomed by consumers.

On the other hand, with the advancement of science and technology, the application scope and field of LCDs are becoming increasingly broad. They are not only used in TV, MB and other display fields, but also in medical equipment, 3D printing and other fields. More perfect visual enjoyment, higher clarity and better environmental adaptability are the goals of the above equipment displays. In medical equipment, display clarity directly affects the doctor's diagnosis, so "precision" and "clarity" are necessary attributes of medical display panels, so liquid crystal materials are required to have high contrast and high reliability performance. 3D printing technology is a technology based on digital model files, using powdered metal or plastic and other adhesive materials, using digital technology material printers, and using short-wave curing of adhesive materials to achieve layer-by-layer printing. Generally, the curing conditions for adhesive materials in 3D printing are 405 nm wavelength and temperature controlled at around 60 ℃, which requires liquid crystal materials to have better tolerance at 405 nm wavelength and high temperature of 60 ℃ to extend the service life of liquid crystal displays. At present, the market mostly regards the life of liquid crystal displays of 3D printers as one of the key breakthrough points of current 3D printing technology. At the same time, in order to achieve the printing of more precise mold materials, the improvement of resolution and contrast is also a development demand of 3D printing technology.

Therefore, developing a liquid crystal material with high reliability and high contrast that can be used in full reflection screens, medical devices, and 3D printing displays will help solve the above problems.

The object of the present invention is to provide a low refractive index liquid crystal composition, which has a lower scattering coefficient and better reliability and can be used to develop a liquid crystal display element or liquid crystal display with high contrast and high reliability.

To achieve the above object, the present invention adopts the following technical solution: The present invention provides a low refractive index liquid crystal composition, the liquid crystal composition comprises a compound represented by formula I and at least two compounds represented by formula II, and the mass content of the compound represented by formula II is ≥50%, Ⅰ II wherein _Ra , _Rb , _R1 and _R2 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an _alkenyl group having 2 to 8 carbon atoms or an alkenyloxy group having 3 to 8 carbon atoms; and _Z1 represents a single bond, _-CH2CH2- , _-CH2O- , _-C2H2- or _-COO- .

Furthermore, the present invention provides a liquid crystal display element, comprising the liquid crystal composition, wherein the liquid crystal display element is an active matrix addressing display element or a passive matrix addressing display element.

Furthermore , the present invention provides a display comprising the above-mentioned liquid crystal composition, wherein the liquid crystal display is an active matrix addressing display or a passive matrix addressing display.

The liquid crystal composition of the present invention has a relatively low scattering coefficient and relatively high reliability, and has obvious advantages in display fields such as medical equipment, full reflection screens, and 3D printing, and can be applied to the development of liquid crystal display elements or liquid crystal displays with high reliability and high contrast display.

The present invention provides a liquid crystal composition, which comprises one or more compounds represented by formula I and at least two compounds represented by formula II, and the mass content of the compounds represented by formula II is ≥50%, Ⅰ II wherein _Ra , _Rb , _R1 and _R2 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an _alkenyl group having 2 to 8 carbon atoms or an alkenyloxy group having 3 to 8 carbon atoms; and _Z1 represents a single bond, _-CH2CH2- , _-CH2O- , _-C2H2- or _-COO- .

In the liquid crystal composition of the present invention, the compound represented by formula I is preferably selected from at least one compound represented by formula I-1 to I-10. Ⅰ-1 Ⅰ-2 Ⅰ-3 Ⅰ-4 Ⅰ-5 Ⅰ-6 Ⅰ-7 Ⅰ-8 Ⅰ-9 Ⅰ-10.

In the liquid crystal composition of the present invention, the compound represented by formula I is further preferably selected from at least two compounds represented by formulas I-1 to I-10.

In the liquid crystal composition of the present invention, further preferably, the compound represented by formula I includes at least two compounds represented by I-1 to I-5. Further preferably, the compound represented by formula I also includes a compound represented by formula I-7.

In the liquid crystal composition of the present invention, the compound represented by formula II comprises at least one or more compounds represented by formula II-1 with a mass content of ≥25% and/or one or more compounds represented by formula II-2 with a mass content of ≥22%. Ⅱ-1 II-2 wherein _R1 and _R2 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 8 carbon atoms or an alkenyloxy group having 3 to 8 carbon atoms.

As a specific implementation mode of the present invention, in the liquid crystal composition of the present invention, the compound represented by formula II is preferably composed of compounds represented by formula II-1 to II-5 or compounds represented by formula II-1 to II-3. Ⅱ-1 Ⅱ-2 Ⅱ-3 Ⅱ-4 II-5 wherein _R1 and _R2 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 8 carbon atoms or an alkenyloxy group having 3 to 8 carbon atoms.

In the liquid crystal composition of the present invention, the compound represented by formula II-1 is preferably selected from at least two compounds represented by formulas II-1-1 to II-1-5. Ⅱ-1-1 Ⅱ-1-2 Ⅱ-1-3 Ⅱ-1-4 Ⅱ-1-5.

In the liquid crystal composition of the present invention, the compound represented by formula II-2 is preferably selected from at least two compounds represented by formulas II-2-1 to II-2-3. Ⅱ-2-1 Ⅱ-2-2 Ⅱ-2-3.

In the liquid crystal composition of the present invention, the compound represented by formula II-3 is preferably selected from the group consisting of compounds represented by formula II-3-1 or II-3-2 or both. Ⅱ-3-1 Ⅱ-3-2.

In the liquid crystal composition of the present invention, the compound represented by formula II-4 is preferably selected from the group consisting of compounds represented by formula II-4-1 or II-4-2 or both. Ⅱ-4-1 Ⅱ-4-2

In the liquid crystal composition of the present invention, the compound represented by formula II-5 is preferably selected from the group consisting of compounds represented by formula II-5-1 or II-5-2 or both. Ⅱ-5-1 Ⅱ-5-2.

The liquid crystal composition of the present invention preferably does not contain the compound represented by formula III. III wherein R ₃ and R ₄ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms substituted with fluorine; X ₂ , X ₃ , X ₄ and X ₅ each independently represent H or F; It may represent 1,4-cyclohexylene or 1,4-phenylene.

Preferably, the compound represented by the aforementioned formula III includes compounds represented by the following formula III-1 to formula III-4, III-1 III-2 III-3 III-4 wherein R ₃ and R ₄ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms substituted with fluorine.

The liquid crystal compound of the present invention preferably further comprises one or more compounds represented by formula IV: IV wherein R ₅ and R ₆ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms substituted with fluorine.

The liquid crystal compound of the present invention preferably further comprises one or more compounds represented by formula V, V wherein _R7 and _R8 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms substituted with fluorine.

In the liquid crystal composition of the present invention, preferably, the compound represented by formula V is selected from the group consisting of compounds represented by the following formulas V-1 to V-6, Ⅴ-1 Ⅴ-2 Ⅴ-3 Ⅴ-4 Ⅴ-5 Ⅴ-6.

In the liquid crystal composition of the present invention, further preferably, the compound represented by formula V contains 2%-7% by weight of the compound represented by formula V-2, and even more preferably, the compound represented by formula V-2 has a mass content of 5%-7%.

The liquid crystal compound of the present invention preferably further comprises one or more compounds represented by formula VI, VI wherein _R9 and _R10 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms substituted with fluorine.

In the liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned formula VI is selected from the group consisting of compounds represented by the following formulae VI-1 to VI-4, VI-1 VI-2 VI-3 VI-4.

In the liquid crystal composition of the present invention, further preferably, the compound represented by formula VI contains the compound represented by formula VI-3 in an amount of 4% to 15% by mass.

The liquid crystal compound of the present invention preferably further comprises one or more compounds represented by formula VII, VII wherein R ₁₁ and R ₁₂ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a fluorine-substituted alkenyl group having 2 to 10 carbon atoms.

In the liquid crystal composition of the present invention, preferably, the compound represented by the aforementioned formula VII is selected from the group consisting of compounds represented by the following formulas VII-1 to VII-2, VII-1 Ⅶ-2.

The present invention also relates to a liquid crystal display element or a liquid crystal display comprising any one of the above liquid crystal compositions; the display element or the display is an active matrix display element or the display or a passive matrix display element or the display.

Optionally, the liquid crystal display element or liquid crystal display is preferably an active matrix liquid crystal display element or liquid crystal display.

Optionally, the active matrix display element or display is a liquid crystal display element or display of FFS-TFT, IPS-TFT, VA-TFT or other TFT mode.

The liquid crystal display element or liquid crystal display comprising the aforementioned liquid crystal composition has high reliability and high contrast, and can be applied to display fields such as medical equipment, full reflection screens, and 3D printing.

Embodiment

In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the content described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

In this manual, unless otherwise specified, percentages refer to mass percentages, and temperatures are in degrees Celsius (℃). The specific meanings of other symbols and test conditions are as follows: Cp represents the clearing point of liquid crystal (℃), tested by DSC quantitative method; Δn represents optical anisotropy, n _o represents the refractive index of ordinary light, _ne represents the refractive index of extraordinary light, and the test conditions are 25±2 ℃, 589 nm, and Abbe refractometer test; Δε represents dielectric anisotropy, Δε=ε _∥ -ε _⊥ , where ε _∥ is the dielectric constant parallel to the molecular axis, and ε _⊥ is the dielectric constant perpendicular to the molecular axis. The test conditions are 25±0.5 ℃, 20 micron parallel box, and INSTEC:ALCT-IR1 test; γ ₁ represents rotational viscosity (mPa·s), and the test conditions are 25±0.5 ℃, 20 micron parallel box, INSTEC: ALCT-IR1 test; K ₁₁ is the splay elastic constant, K ₂₂ is the torsion elastic parameter, K ₃₃ is the bending elastic constant, and the test conditions are: 25 ℃, INSTEC: ALCT-IR1, 20 micron vertical box; VHR represents voltage holding rate (%), and the test conditions are 60±1 ℃, voltage is ±5V, pulse width is 10ms, and voltage holding time is 1.667ms. The test equipment is TOYO Model6254 LCD performance comprehensive tester; CR represents the contrast of LCD devices, which is the bright state of the LCD divided by the dark state of the LCD. The test conditions are 25±1℃, the test voltage is the normal driving voltage, the test frequency is 64 Hz, and the test equipment is DMS505.

The preparation method of the liquid crystal composition in each embodiment is as follows: each liquid crystal monomer is weighed according to the ratio of each embodiment and put into a stainless steel beaker, and the stainless steel beaker containing each liquid crystal monomer is placed on a magnetic stirrer to heat and melt. After most of the liquid crystal monomers in the stainless steel beaker are melted, a magnetic rotor is added to the stainless steel beaker, and the mixture is stirred evenly. After cooling to room temperature, the liquid crystal composition is obtained.

The liquid crystal monomer structure of the embodiment of the present invention is represented by a code, and the code representation method of the liquid crystal ring structure, end group, and connecting group is shown in Table 1 and Table 2 below.

Table 1 Corresponding codes of ring structures Ring structure Corresponding code C P L Y G Gi A D U

Table 2 Corresponding codes of terminal groups and linking groups End Groups and Linking Groups Corresponding code C _n H _2n+1 - n- C _n H _2n+1 O- nO- -CF ₃ -T -OCF ₃ -OT _-CH2O- -O- -COO- -Z- -F -F -CH ₂ CH ₂ - -E- -CH=CH- -V- -CH=CH-C _n H _2n+1 -Vn Cp- Cpr- Cpr1-

For example: , its code is CC-Cp-V1; , its code is PGUQU-3-F; , its code is CCY-3-O2; , its code is COY-3-O2; , its code is CCOY-3-O2.

Embodiment 1

The formula of the liquid crystal composition and the corresponding properties are shown in Table 3 below.

Table 3 Formulation of the liquid crystal composition of Example 1 and its corresponding properties Category Liquid crystal unit code content(%) Ⅰ CC-3-V1 8 Ⅰ CC-2-3 19 Ⅰ CC-5-3 10 Ⅱ CCOY-3-O2 12 Ⅱ CCOY-2-O2 13 Ⅱ CCY-3-O1 9 Ⅱ CCY-3-O2 12 Ⅱ CCY-4-O2 6.5 Ⅱ CCEY-3-O2 8 IV COY-3-O2 2.5 Δε [1K Hz, 25 ℃]: -4.6 Δn [589 nm, 25 ℃]: 0.085 Cp: 116 ℃ K ₁₁ : 19.1 K ₂₂ : 9.6 K ₃₃ : 22.5

Embodiment 2

The formula of the liquid crystal composition and the corresponding properties are shown in Table 4 below.

Table 4 Formulation of the liquid crystal composition of Example 2 and its corresponding properties Category Liquid crystal monomer code content(%) Ⅰ CC-3-V1 8 Ⅰ CC-2-3 19 Ⅰ CC-5-3 10 Ⅱ CCOY-3-O2 9 Ⅱ CCOY-2-O2 11 Ⅱ CCY-3-O1 11 Ⅱ CCY-3-O2 13.5 Ⅱ CCY-4-O2 8 Ⅱ CCEY-3-O2 8 IV COY-3-O2 2.5 Δε [1K Hz, 25 ℃]: -4.7 Δn [589 nm, 25 ℃]: 0.085 Cp: 116 ℃ K ₁₁ : 18.9 K ₂₂ : 9.5 K ₃₃ : 22.0

Embodiment 3

The formula of the liquid crystal composition and the corresponding properties are shown in Table 5 below.

Table 5 Formulation and corresponding properties of the liquid crystal composition of Example 3 Category Liquid crystal monomer code content(%) Ⅰ CC-3-V1 8 Ⅰ CC-2-3 19 Ⅰ CC-5-3 10 Ⅱ CCOY-3-O2 14 Ⅱ CCOY-2-O2 15.5 Ⅱ CCY-3-O1 8 Ⅱ CCY-3-O2 10 Ⅱ CCY-4-O2 5 Ⅱ CCEY-3-O2 8 IV COY-3-O2 2.5 Δε [1K Hz, 25 ℃]: -4.8 Δn [589 nm, 25 ℃]: 0.083 Cp: 119 ℃ K ₁₁ : 19.7 K ₂₂ : 9.9 K ₃₃ : 23.0

Embodiment 4

The formula of the liquid crystal composition and the corresponding properties are shown in Table 6 below.

Table 6 Formulation and corresponding properties of the liquid crystal composition of Example 4 Category Liquid crystal unit code content(%) Ⅰ CC-2-3 12 Ⅰ CC-4-3 9 Ⅰ CC-3-V1 8 Ⅱ CCOY-3-O2 13 Ⅱ CCOY-2-O2 12 Ⅱ CCY-2-O2 10 Ⅱ CCY-3-O1 8 Ⅱ CCY-3-O2 10 Ⅱ CCEY-3-O2 8 Ⅴ CP-3-O2 5 VI CY-3-O2 5 Δε [1K Hz, 25 ℃]: -4.8 Δn [589 nm, 25 ℃]: 0.086 Cp: 108 ℃ K ₁₁ : 19.2 K ₂₂ : 9.6 K ₃₃ : 21.1

Embodiment 5

The formula of the liquid crystal composition and the corresponding properties are shown in Table 7 below.

Table 7 Formulation and corresponding properties of the liquid crystal composition of Example 5 Category Liquid crystal monomer code content(%) Ⅰ CC-2-3 12 Ⅰ CC-4-3 9 Ⅰ CC-3-V1 8 Ⅱ CCOY-3-O2 10 Ⅱ CCOY-2-O2 9 Ⅱ CCY-2-O2 7 Ⅱ CCY-3-O1 8 Ⅱ CCY-3-O2 7 Ⅱ CCEY-3-O2 10 Ⅴ CP-3-O2 7 VI CY-3-O2 13 Δε [1K Hz, 25 ℃]: -4.4 Δn [589 nm, 25 ℃]: 0.088 Cp: 103 ℃ K ₁₁ : 17.7 K ₂₂ : 8.9 K ₃₃ : 18.2

Embodiment 6

The formula of the liquid crystal composition and the corresponding properties are shown in Table 8 below.

Table 8 Formulation and corresponding properties of the liquid crystal composition of Example 6 Category Liquid crystal monomer code content(%) Ⅰ CC-3-2 20.5 Ⅰ CC-5-3 7 Ⅰ CC-3-V1 5 Ⅱ CCOY-3-O2 13 Ⅱ CCOY-2-O2 10 Ⅱ CCY-2-O2 10 Ⅱ CCY-3-O1 7 Ⅱ CCY-3-O2 6 Ⅱ CCY-4-O2 6 Ⅱ CCEY-3-O2 8 VI CY-3-O2 7.5 Δε [1K Hz, 25 ℃]: -4.5 Δn [589 nm, 25 ℃]: 0.085 Cp: 108 ℃ K ₁₁ : 19.4 K ₂₂ : 9.7 K ₃₃ : 21.0

Embodiment 7

The formula of the liquid crystal composition and the corresponding properties are shown in Table 9 below.

Table 9 Formulation of the liquid crystal composition of Example 7 and its corresponding properties Category Liquid crystal unit code content(%) Ⅰ CC-2-3 20 Ⅰ CC-4-3 9 Ⅱ CCOY-3-O2 13 Ⅱ CCOY-2-O2 10 Ⅱ CCY-2-O2 9 Ⅱ CCY-3-O1 9 Ⅱ CCY-3-O2 10 IV COY-3-1 7 IV COY-3-O1 5 Ⅴ CP-3-O2 3 VI CY-3-O2 3 VII CCP-3-1 2 Δε [1K Hz, 25 ℃]: -5.3 Δn [589 nm, 25 ℃]: 0.079 Cp: 86 ℃ K ₁₁ : 14.8 K ₂₂ : 7.4 K ₃₃ : 16.9

Embodiment 8

The formula of the liquid crystal composition and the corresponding properties are shown in Table 10 below.

Table 10 Formulations and corresponding properties of the liquid crystal composition of Example 8 Category Liquid crystal monomer code content(%) Ⅰ CC-2-3 20 Ⅰ CC-4-3 9 Ⅱ CCOY-3-O2 11 Ⅱ CCOY-2-O2 12 Ⅱ CCY-2-O2 9 Ⅱ CCY-3-O1 9 Ⅱ CCY-3-O2 12 IV COY-3-1 9 IV COY-3-O1 7 Ⅴ CP-3-O2 2 Δε [1K Hz, 25 ℃]: -5.2 Δn [589 nm, 25 ℃]: 0.083 Cp: 84 ℃ K ₁₁ : 17.2 K ₂₂ : 8.6 K ₃₃ : 18.2

Embodiment 9

The formula of the liquid crystal composition and the corresponding properties are shown in Table 11 below.

Table 11 Formulation of the liquid crystal composition of Example 9 and its corresponding properties Category Liquid crystal monomer code content(%) Ⅰ CC-2-3 20 Ⅰ CC-4-3 9 Ⅱ CCOY-3-O2 11 Ⅱ CCOY-2-O2 11 Ⅱ CCY-2-O2 9 Ⅱ CCY-3-O1 8 Ⅱ CCY-3-O2 12 III CPY-3-O2 3 IV COY-3-1 9 IV COY-3-O1 6 Ⅴ CP-3-O2 2 Δε [1K Hz, 25 ℃]: -5.2 Δn [589 nm, 25 ℃]: 0.083 Cp: 84 ℃ K ₁₁ : 16.2 K ₂₂ : 8.1 K ₃₃ : 18.2

Comparison ratio 1

The formula of the liquid crystal composition and the corresponding properties are shown in Table 12 below.

Table 12 Formulation and corresponding properties of the liquid crystal composition of Comparative Example 1 Category Liquid crystal monomer code content(%) Ⅰ CC-3-V 32.5 Ⅰ CC-3-V1 5 VII CCP-V-1 14 PUQU-3-F 4 VII CCP-3-1 4.5 VII CCP-V2-1 7 CCVC-3-3 6 CCOC-4-3 2 APUQU-2-F 4 CDUQU-3-F 7 APUQU-3-F 6 DPGU-4-F 2 CCZPC-3-3 3 CCZPC-3-5 3 Δε [1K Hz, 25 ℃]: 6.1 Δn [589 nm, 25 ℃]: 0.090 Cp: 96 ℃ K ₁₁ : 18.0 K ₂₂ : 9.0 K ₃₃ : 22.5

Comparison ratio 2

The formula of the liquid crystal composition and the corresponding properties are shown in Table 13 below.

Table 13 Formulation and corresponding properties of the liquid crystal composition of Comparative Example 2 Category Liquid crystal monomer code content(%) Ⅰ CC-3-V 26 Ⅱ CCY-2-O2 8 Ⅱ CCY-3-O2 9 Ⅱ CCY-3-O1 5 III PYP-2-3 5 III CPY-2-O2 10.5 III CPY-3-O2 11 VI CY-3-O2 8 CLY-3-O3 6 CLY-4-O2 6 CLY-3-O2 5.5 Δε [1K Hz, 25 ℃]: -4.5 Δn [589 nm, 25 ℃]: 0.115 Cp: 110 ℃ K ₁₁ : 18.3 K ₂₂ : 9.2 K ₃₃ : 20.7

Comparison ratio 3

The formula of the liquid crystal composition and the corresponding properties are shown in Table 14 below.

Table 14 Formula and corresponding properties of the liquid crystal composition of Comparative Example 3 Category Liquid crystal monomer code content(%) Ⅰ CC-2-3 6 Ⅰ CC-3-V 31.5 Ⅰ CC-4-3 6 Ⅱ CCY-3-O1 5.5 Ⅱ CCY-3-O2 3 Ⅱ CCY-4-O2 4 III CPY-2-O2 10 III CPY-3-O2 10 III PGiY-2-O4 3 VI CY-3-O2 7 CLY-3-O2 4 CLY-2-O4 10 Δε [1K Hz, 25 ℃]: -3.2 Δn [589 nm, 25 ℃]: 0.098 Cp: 85 ℃ K ₁₁ : 14.0 K ₂₂ : 7.0 K ₃₃ : 14.4

Comparison ratio 4

The formula of the liquid crystal composition and the corresponding properties are shown in Table 15 below.

Table 15 Formulation and corresponding properties of the liquid crystal composition of Comparative Example 4 Category Liquid crystal unit code content(%) Ⅰ CC-2-3 20 Ⅰ CC-4-3 8 Ⅱ CCOY-3-O2 13 Ⅱ CCY-2-O2 9 Ⅱ CCY-3-O1 7 Ⅱ CCY-3-O2 12 III PGY-3-O2 10 IV COY-3-1 8 IV COY-3-O1 5 Ⅴ CP-3-O2 3 VI CY-3-O2 5 Δε [1K Hz, 25 ℃]: -3.8 Δn [589 nm, 25 ℃]: 0.099 Cp: 110 ℃ K ₁₁ : 21.0 K ₂₂ : 10.5 K ₃₃ : 27.0

Comparison ratio 5

The formula of the liquid crystal composition and the corresponding properties are shown in Table 16 below.

Table 16 Formula and corresponding properties of the liquid crystal composition of Comparative Example 5 Category Liquid crystal monomer code content(%) Ⅰ CC-2-3 20 Ⅰ CC-4-3 9 Ⅱ CCOY-3-O2 7 Ⅱ CCY-2-O2 7 Ⅱ CCY-3-O1 7 Ⅱ CCY-3-O2 7 Ⅱ CCOY-2-O2 10 IV COY-3-1 12 IV COY-3-O1 9 Ⅴ CP-3-O2 3 VI CY-3-O2 9 Δε [1K Hz, 25 ℃]: -4.7 Δn [589 nm, 25 ℃]: 0.085 Cp: 85 ℃ K ₁₁ : 15.8 K ₂₂ : 7.4 K ₃₃ : 16.7

Table 17 Comparison of VHR and service life of Examples 1-9 and Comparative Examples 1-5 Experiment number VHR initial (60±1℃, 0.6 Hz) 405 nm aging 2000h (60±1℃, 0.6 Hz) 405 nm LCD life/h Comparative Example 1 90.2 83.4 1000 Comparative Example 2 88.2 75.6 ＜300 Comparative Example 3 85.2 72.3 ＜300 Comparative Example 4 89.5 86.3 1500 Comparative Example 5 89.2 85.8 1000 Embodiment 1 90.2 88.9 ＞2000 Embodiment 2 90.1 88.8 ＞2000 Embodiment 3 90.3 88.9 ＞2000 Embodiment 4 90.2 88.8 ＞2000 Embodiment 5 90.4 89.0 ＞2000 Embodiment 6 90.4 89.1 ＞2000 Embodiment 7 90.6 89.3 ＞2000 Embodiment 8 90.3 88.5 ＞2000 Embodiment 9 90.2 88.3 ＞2000

Description: Comparative Example 1 is a 3D printing liquid crystal composition of positive specifications mass-produced on the market; Comparative Example 2 is a 3D printing liquid crystal composition of negative specifications mass-produced on the market; Comparative Example 3 is a negative TV liquid crystal composition mass-produced on the market.

VHR evaluation conditions: 405 nm wavelength backlight exposure, ambient temperature 60 ℃.

Evaluation method for LCD monitor service life: The time when VHR decreases by 3% from the initial value is defined as the LCD monitor service life, with 2000h as the upper limit of the experimental time.

As shown in Table 17, the service life of the liquid crystal composition of Examples 1-9 at a wavelength of 405 nm is significantly better than that of Comparative Examples 1-5. When working at an ambient temperature of 60°C, 3D printing requires a stronger UV and high temperature resistance of the liquid crystal composition. The present invention provides a high temperature and UV resistant liquid crystal composition, which greatly extends the service life of the 3D printing display.

Table 18 Comparison table of CR of Examples 1-9 and Comparative Examples 1-5 _K11 K ₂₂ K ₃₃ Contrast CR Comparative Example 1 18.0 9.0 22.5 - Comparative Example 2 18.3 9.2 20.7 Down 47% Comparative Example 3 14.0 7.0 14.4 45% decrease Comparative Example 4 14.0 7.0 14.4 Down 6% Comparative Example 5 15.8 7.4 16.7 Down 7% Embodiment 1 19.1 9.6 22.5 Increased by 24% Embodiment 2 18.9 9.5 22.0 Increased by 22% Embodiment 3 19.7 9.9 23.0 Increased by 21% Embodiment 4 19.2 9.6 21.1 Increase by 25% Embodiment 5 17.7 8.9 18.2 Increased by 12% Embodiment 6 19.4 9.7 21.0 Increased by 21% Embodiment 7 14.8 7.4 16.9 Increased by 14% Embodiment 8 17.2 8.6 18.2 Increase by 10% Embodiment 9 16.2 8.1 18.2 Increase by 6%

Note: LCD contrast = bright state / dark state. The higher the contrast, the higher the display clarity. The contrast calculation method is based on Comparative Example 1.

The bright state of an LCD is the brightness of the backlight passing through the panel when the LCD is turned on, which mainly depends on the brightness of the backlight and the transmittance of the light after penetrating the liquid crystal; the dark state is the brightness of the backlight passing through the panel by scattering when the LCD is opaque, which mainly depends on the pre-tilt angle of the display, circuit design, aperture design and the arrangement of liquid crystal molecules. The liquid crystal of the present invention mainly reduces the scattering of light in the liquid crystal by improving the arrangement of the liquid crystal, reduces the dark state brightness value, and improves the contrast.

It can be seen from Table 18 that when the K values are not much different, the contrast of Comparative Examples 1 and 2 is much lower than the contrast of Examples 1, 2, 3, 4 and 6; when the K values of Examples 5, 7, 8 and 9 are less than those of Comparative Examples 1 and 2, the contrast of Examples 5, 7, 8 and 9 is still much higher than that of Comparative Examples 1 and 2; it can be seen that the liquid crystal composition of the present invention is not only far superior to the comparative example liquid crystal in terms of service life, but also has obvious advantages over the comparative example liquid crystal in terms of contrast, and can be applied to higher definition display devices.

The advantages of the liquid crystal of the present invention are as follows: 1. The initial VHR is significantly better than that of the comparative liquid crystal; 2. The VHR after simultaneous irradiation for 2000 hours at a wavelength of 405 nm is significantly better than that of the comparative liquid crystal; 3. The service life of the liquid crystal display is much longer than that of the mass-produced liquid crystal on the market; 4. The contrast is much higher than that of the comparative liquid crystal.

The above embodiments disclosed in the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For ordinary technical personnel in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims (10)

A low refractive index liquid crystal composition, comprising one or more compounds of formula I and at least two compounds of formula II, wherein the compounds of formula II comprise at least one or more compounds of formula II-1 and one or more compounds of formula II-2, and the mass content of the compounds of formula II is

50%,

wherein _Ra and _Rb2 independently represent an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 8 carbon atoms; _R1 represents an alkyl group having 1 to 6 carbon atoms; _R2 represents an alkoxy group having _{1 to 6 carbon atoms; and Z1 represents a single bond, -CH2CH2- or -CH2O- .} The liquid crystal composition according to claim 1, wherein the mass content of the one or more compounds represented by formula II-1 is

25% mass content of one or more compounds represented by formula II-2

twenty two%. The liquid crystal composition according to claim 1, wherein the compound represented by formula I is selected from at least one compound represented by formula I-1 to I-10,

The liquid crystal composition according to claim 1, wherein the liquid crystal composition does not contain the compound represented by formula III,

wherein R ₃ and R ₄ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkenyl group having 2 to 10 carbon atoms substituted with fluorine; X ₂ , X ₃ , X ₄ and X ₅ each independently represent H or F;

It may represent 1,4-cyclohexylene or 1,4-phenylene. The liquid crystal composition according to claim 1 further comprises one or more compounds of formula IV:

wherein R ₅ and R ₆ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a fluorine-substituted alkenyl group having 2 to 10 carbon atoms. The liquid crystal composition according to claim 1 further comprises one or more compounds represented by formula V:

wherein _R7 and _R8 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a fluorine-substituted alkenyl group having 2 to 10 carbon atoms. The liquid crystal composition according to claim 1 further comprises one or more compounds represented by formula VI,

wherein _R9 and _R10 each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a fluorine-substituted alkenyl group having 2 to 10 carbon atoms. The liquid crystal composition according to claim 1 further comprises one or more compounds represented by formula VII,

wherein R ₁₁ and R ₁₂ each independently represent an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a fluorine-substituted alkenyl group having 2 to 10 carbon atoms. A liquid crystal display element, comprising the liquid crystal composition described in any one of claims 1 to 8, wherein the liquid crystal display element is an active matrix addressing display element or a passive matrix addressing display element. A liquid crystal display comprising the liquid crystal composition described in any one of claims 1 to 8, wherein the liquid crystal display is an active matrix addressing display or a passive matrix addressing display.