TW201715026A - Liquid crystal composition and display element or displayer with same - Google Patents

Abstract

The invention discloses a liquid crystal composition and a display element or displayer with the same. The liquid crystal composition has one or more compositions of the general formula I, compositions of the general formula II and compositions of the general formula III, wherein the formulas can be seen in the specification, R1, R3 and R4 represent gaseous normal alkyl with 1-5 carbon atoms, R2 represents gaseous normal alkyl with 1-5 carbon atoms and alkenyl with 2-5 carbon atoms, and R5 represents H or gaseous normal alkyl with 1-3 carbon atoms. The liquid crystal composition is high in response speed, large in dielectric anisotropy, moderate in optical anisotropy, and high in light and heat stability and particularly suitable for IPS liquid crystal displays devices.

Description

Liquid crystal composition

The present invention relates to a liquid crystal composition and a liquid crystal display element or liquid crystal display comprising the liquid crystal composition.

At present, the application range of liquid crystal compounds is expanding wider and wider, and it can be applied to various types of displays, photoelectric elements, sensors, and the like. There are many kinds of liquid crystal compounds used in the above display field, and the nematic liquid crystal is most widely used. Nematic liquid crystals have been used in passive TN, STN matrix displays and systems with TFT active matrices.

For the application of thin film transistor technology (TFT-LCD), although the market has been very large in recent years, and the technology has gradually matured, people's requirements for display technology are also constantly improving, especially in achieving fast response and lowering the driving voltage. Reduce power consumption and other aspects. As one of the important optoelectronic materials for liquid crystal displays, liquid crystal materials play an important role in improving the performance of liquid crystal displays.

As a liquid crystal material, it is required to have good chemical and thermal stability as well as stability against electric fields and electromagnetic radiation. As a liquid crystal material for thin film transistor technology (TFT-LCD), it is not only required to have the above stability, but also has a wide nematic phase temperature range, a suitable birefringence anisotropy, a very high resistivity, Good UV resistance, high charge retention and low vapor pressure.

In the dynamic picture display process, it is desirable to eliminate the image sticking and smearing of the display screen as much as possible, and the liquid crystal has a fast response speed, so the liquid crystal is required to have a low rotational viscosity γ ₁ ; in addition, for the portable device, in order to reduce For the energy consumption of the device, it is desirable that the driving voltage of the liquid crystal is as low as possible; and for a display such as a television, the driving voltage requirement for the liquid crystal is not so low.

The viscosity of the liquid crystal compound, especially the rotational viscosity γ ₁ directly affects the response time after the liquid crystal is powered on, whether it is the rise time (t _on ) or the fall time (t _off ), which is proportional to the rotational viscosity γ ₁ of the liquid crystal, and rises. The time (t _on ) is related to the liquid crystal cell and the driving voltage, and can be adjusted by increasing the driving voltage and reducing the thickness of the liquid crystal cell; and the falling time (t _off ) is independent of the driving voltage, mainly the elastic constant of the liquid crystal. In relation to the thickness of the liquid crystal cell, the decrease in the thickness of the cell reduces the fall time (t _off ), while in different display modes, the liquid crystal molecules move in different ways. The three modes of TN, IPS and VA are respectively the average elastic constant K and the torsional elasticity. The constant and the bending elastic constant are inversely proportional.

According to the theory of liquid crystal continuum, after different kinds of liquid crystals are deformed by external force (electric field, magnetic field), they will "rebound" back to the original shape through the interaction between molecules; similarly, the liquid crystal is also due to the intermolecular The interaction forces form a "viscosity." Small changes in liquid crystal molecules can cause significant changes in the performance of conventional parameters of liquid crystals. Some of these changes are regular, some are almost impossible to find, and liquid crystal materials and their ratios also produce interactions between liquid crystal molecules. The obvious effects, these effects are very subtle, and so far there is no perfect theoretical explanation.

The viscosity of liquid crystals is related to the molecular structure of liquid crystals. It is one of the important tasks of liquid crystal formulators to study the relationship between the viscosity of liquid crystal systems formed by different liquid crystal molecules and the molecular structure of liquid crystals.

The technical problem to be solved by the present invention is to provide a liquid crystal composition and a liquid crystal display element or liquid crystal display comprising the same, which has a low viscosity, can achieve a fast response, and has a large dielectric difference. Directional Δ ε, moderate optical anisotropy Δn, high stability to heat and light, good UV resistance, high charge retention, and low vapor pressure.

In order to solve the above technical problems, the technical means adopted by the present invention is: a liquid crystal composition containing one or more compounds of the formula I, one or more compounds of the formula II, one or more compounds of the formula III, Wherein R ₁ , R ₃ and R ₄ represent a linear alkyl group having 1 to 5 carbon atoms, and R ₂ represents a linear alkyl group having 1 to 5 carbon atoms and an alkenyl group having 2 to 5 carbon atoms. ; R ₅ represents H or a linear alkyl group having 1 to 3 carbon atoms.

The liquid crystal composition provided by the present invention has Δn [589 nm, 25 ° C] > 0.08, Δ ε [1 KHz, 25 ° C] > 2, clearing point C _p > 70.0 ° C, and rotational viscosity γ ₁ [25 ° C] at 40 ~110mPa. Between s.

The content of the compound of the formula I in the liquid crystal composition provided by the invention is 5-30%, the mass percentage of the compound of the formula II is 5-20%, and the mass percentage of the compound of the formula III is 20-50%.

Further improvement of the present invention is that the compound of the formula I is a compound of the formula I1 to I4, the compound of the formula II is a compound of the formula II1 to II25, and the compound of the formula III is a compound of the formula III1 to III4.

The dielectric anisotropy Δ ε of each of the compounds represented by the general formulae I1 to I4 is between 25 and 30, and at the same time, the rotational viscosity is low, the clearing point is above 120 ° C, and the Δn is 0.2 or more. It is beneficial to increase the liquid crystal composition Δ ε, improve the clearing point, and improve Δn.

The compounds represented by the general formulae II1 to II25 generally have an optical anisotropy Δn of a suitable size, and a moderate clearing point value. Among them, the terminal alkyl compounds of II1 to II15 have good high temperature resistance and UV stability, and the terminal alkenyl compounds of II16 to II25 have a large elastic constant K value, a low viscosity and a fast response speed.

The compounds represented by the general formulae III1 to III4 have a very low rotational viscosity γ ₁ , a near-neutral dielectric anisotropy Δ ε , and a small optical anisotropy Δ n , which are advantageous in improving liquid crystal viscosity and low temperature performance. Different alkyl substituents have an effect on the rotational viscosity γ ₁ and clearing point C _p of the liquid crystal. Generally, the longer alkyl chain or alkenyl chain increases the rotational viscosity γ _{1 of the} liquid crystal while increasing the clearing point C _p .

One or more compounds of the formula IV may also be added to the liquid crystal composition provided by the present invention. R ₆ represents an alkyl group having a carbon number of 2 to 5. Multi alkyl chain carbon atoms, the C _p of the liquid crystal will be higher, but at the same time increases the viscosity.

A further improvement of the present invention is that the compound of the formula IV is a compound of the formula IV1 to IV4, and the compound of the formula IV in the liquid crystal composition has a mass percentage of 1 to 25%.

Each compound represented by Formula IV has a moderate Δ ε (about 6) and a high C _p , and a low viscosity is suitable for adjusting the viscosity, C _p , Δ ε of the liquid crystal.

The liquid crystal composition provided by the present invention may further contain one or more compounds represented by the formula V, and the preferred mass percentage of the compound represented by the formula V in the liquid crystal composition is 1 to 25%. R ₇ represents an alkenyl group having 2 to 5 carbon atoms.

A further improvement of the present invention is that the compound of the formula V is a compound of the formula V1 to V2,

A compound of formula V with a compound of formula Ⅳ higher compared with C _p, low viscosity, in particular, has a larger spring constant. Helps improve response speed.

One or more compounds of the formula VI may also be added to the liquid crystal composition provided by the present invention. R ₈ and R ₉ are a linear alkyl group having 1 to 5 carbon atoms; and (F) is hydrogen or fluorine.

The compound of formula VI has a large elastic constant K (largeer K11, K22, K33), a high clearing point C _p (higher than 200 ° C), but also has a large viscosity γ ₁ , which can be used for adjustment. The K value parameter of the liquid crystal and the clearing point C _p .

The compound of formula VI is preferably a compound of formula VI1 to VI8,

The dielectric anisotropy Δ ε of the VI1 to VI8 compounds is substantially close to neutral, and the VI1 to VI5 compounds also have a lateral fluorine atom, which is advantageous for improving the mutual solubility of the liquid crystal.

The compound of the formula VI in the liquid crystal composition provided by the present invention preferably has a mass percentage of 1 to 15%.

The different ratios of the components of the liquid crystal composition may exhibit slightly different properties, such as dielectric anisotropy Δ ε, optical anisotropy Δn, conversion of liquid crystal nematic phase to liquid, clearing point Cp, low temperature The lower stability will vary and can be applied to different types of display elements, but the same feature is that the rotational viscosity γ _{1 is} lower. Applied to liquid crystal display elements for fast response.

The liquid crystal compound provided by the invention may also be added with dopants of various functions, and the dopant content is preferably between 0.01 and 1%. These dopants are mainly antioxidants, ultraviolet absorbers, and chiral agents. The antioxidant, ultraviolet absorber is preferably the following compound: S in the above formula is an integer from 1 to 10.

The chiral agent is preferably (left-handed or right-handed) as follows:

The invention further relates to a liquid crystal display element or display comprising any of the liquid crystal compositions described above, the display element or display being an active matrix display element or display, a passive matrix display element or a display.

The liquid crystal display element or liquid crystal display is preferably an active matrix addressed liquid crystal display element or a liquid crystal display.

The active matrix display element or display is specifically a TN-TFT or IPS-TFT liquid crystal display element or display.

The technical progress achieved by the present invention is that the liquid crystal composition provided by the invention has low viscosity and can achieve fast response, and has moderate dielectric anisotropy Δ ε and moderate optical difference. Directional Δn, high stability to heat and light.

The liquid crystal material comprising the liquid crystal composition provided by the present invention not only has good chemical and thermal stability and stability against electric fields and electromagnetic radiation. Moreover, as a liquid crystal material for thin film transistor technology (TFT-LCD), it also has a wide nematic phase temperature range, suitable birefringence anisotropy, very high resistivity, good ultraviolet resistance, and high charge. Maintainability and low vapor pressure.

The present invention will be further described in detail below with reference to specific embodiments, but the invention is not limited to the following examples. The method is a conventional method unless otherwise specified. The raw materials can be obtained from an open commercial route unless otherwise specified. The percentages are percentages by mass unless otherwise specified.

In the following examples, C _p denotes clearing point, directly WRX-1S microscopic thermal analyzer measurement, is set a heating rate of 3 ℃ / min.

Δn represents optical anisotropy (589 nm, 20 ° C), Δ ε represents dielectric anisotropy (25 ° C, 1 KHz, HP 4284 A, 5.2 μm TN left-handed box), and γ ₁ represents rotational viscosity (mpa.s) at 20 ° C. , VHR (%) represents charge retention (5V, 60Hz, 20 ° C), ρ (×10 ¹³ Ω.cm) represents resistivity (20 ° C), voltage retention rate VHR (%) of the tester and resistivity ρ ( ×10 ¹³ Ω·cm) are TOYO06254 and TOYO6517 liquid crystal physical property evaluation systems (test temperature 20 ° C, time 16 ms, test box 7.0 μm).

The structure of the liquid crystal monomer in the embodiment of the present invention is represented by a code, and the code representation methods of the liquid crystal ring structure, the terminal group and the linking group are shown in the following Table (1) and Table (2).

Example: Expressed as 3CCV1, Expressed as 3BB(3F)B(3F,5F)QB(3F,5F)F.

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

It can be seen from the above examples that the liquid crystal composition of the present invention has a low rotational viscosity γ ₁ for liquid crystal display and can achieve a fast response. It is especially suitable for liquid crystal materials for TN and IPS modes.

Claims (10)

A liquid crystal composition comprising one or more compounds of formula I, one or more compounds of formula II, one or more compounds of formula III, Wherein R ₁ , R ₃ and R ₄ represent a linear alkyl group having 1 to 5 carbon atoms, and R ₂ represents a linear alkyl group having 1 to 5 carbon atoms and an alkenyl group having 2 to 5 carbon atoms. ; R ₅ represents H or a linear alkyl group having 1 to 3 carbon atoms. The liquid crystal composition according to claim 1, wherein the compound of the formula I has a mass percentage of 5 to 30%, the compound of the formula II has a mass percentage of 5 to 20%, and the compound of the formula III has a mass percentage of 20 to 50. %. The liquid crystal composition according to claim 1, wherein the compound of the formula I is a compound of the formula I1 to I4, the compound of the formula II is a compound of the formula II1 to II25, and the compound of the formula III is a compound of the formula III1 to III4. The liquid crystal composition according to claim 1, wherein: the compound of the formula IV is further contained, and the mass percentage thereof is 1 to 25%. R ₆ represents an alkyl group having 2 to 5 carbon atoms. The liquid crystal composition according to claim 4, wherein the compound of the formula IV is a compound of the formula IV1 to IV4, The liquid crystal composition according to claim 1, wherein: the compound of the formula V is further contained, and the mass percentage thereof is 1 to 25%. R ₇ represents an alkenyl group having 2 to 5 carbon atoms. The liquid crystal composition according to claim 6, wherein the compound of the formula V is a compound of the formula V1 to V2, The liquid crystal composition according to claim 1, wherein: the compound of the formula VI is further contained, and the mass percentage thereof is from 1 to 15%. R ₈ and R ₉ are a linear alkyl group having 1 to 5 carbon atoms; and (F) is hydrogen or fluorine. The liquid crystal composition according to claim 8, wherein the compound represented by the formula VI is a compound of the formula VI1 to VI8, The liquid crystal composition according to any one of claims 1 to 9, wherein the liquid crystal composition has a mass percentage of the compound of the formula I of 6 to 20%, and the mass percentage of the compound of the formula II is 5 to 15%. The compound of formula III has a mass percentage of 20 to 42%, the mass percentage of the compound of formula IV is 10 to 20%, the mass percentage of the compound of formula V is 8 to 20%, and the mass percentage of the compound of formula VI is 5 to 15%. .