TWI487779B - Liquid crystal composition and liquid crystal display device - Google Patents

Description

Liquid crystal composition and liquid crystal display element

The present invention relates to a liquid crystal composition, and more particularly to a liquid crystal composition having good low temperature storage (low temperature storage) and a liquid crystal display element containing the liquid crystal composition.

Liquid crystal displays have the advantages of light weight, power saving, no radiation and full color display, so they have become the most common display products.

In recent years, with the continuous improvement of technology and the requirements for high resolution, high reaction rate and high image quality, liquid crystal displays have been twisted nematic (TN) and super twisted nematic (STN). The passive drive display mode has been developed into an active matrix liquid crystal display having a thin filmed transistor (TFT). With the demand of wide viewing angle technology, the development and breakthrough of liquid crystal display modes such as in-plane switching (IPS) and vertical alignment (VA) are very important for the application and development of future panels.

In the liquid crystal composition, in order to lower the threshold voltage (Vth) of the liquid crystal display element, a higher dielectric anisotropy (Δε) is required; in order to speed up the response speed, a lower requirement is required. Rotational viscosity Γ1); A higher optical anisotropy (Δn) is required for the purpose of improving contrast; a higher clearing point temperature (Tni) is required in order to be suitable for use in various environments. Although various studies have been conducted on the liquid crystal composition in order to satisfy these requirements, the satisfaction of a certain property is often accompanied by the sacrifice of another property, and therefore, a liquid crystal composition which satisfies various requirements has not been obtained.

The present invention provides a liquid crystal composition using the liquid crystal composition to produce a liquid crystal display element, which enables the liquid crystal display element to have good performance.

The liquid crystal composition of the present invention comprises a component represented by Formula I, a component represented by Formula II, and a component represented by Formula III in an amount of more than 10% by weight: Formula I; Formula II; Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently -H, C ₁ -C ₁₅ alkyl or C ₂ -C ₁₅ alkenyl, and -CH ₂ - in the aforementioned alkyl or alkenyl group may be Substituted by -O-, -CO-, -COO- or -OCO-, provided that the heteroatoms are not directly bonded to each other; A ₁ , A ₂ , A ₃ and A ₄ are each selected from 1,4-phenylene, a group consisting of 1,4-cyclohexylene, 2,5-indan and 2,5-extended tetrahydropyranyl, wherein 1,4-phenylene, 1,4-cyclohexylene and 2,5 - the hydrogen on the helium may be unsubstituted or substituted by a fluorine atom, and at least one of A ₁ , A ₂ , A ₃ and A ₄ is 2,5-indan; A ₅ , A ₆ , A ₇ , A ₈ And A ₉ are respectively selected from the group consisting of 1,4-phenylene, 1,4-cyclohexylene and 2,5-tetrahydropyranyl, wherein 1,4-phenyl and 1,4- The hydrogen on the cyclohexylene group may be unsubstituted or substituted by a fluorine atom; m, n, o, and p are 0 or 1, respectively, and m+n+o+p>2; Z ₁ , Z ₂ , Z ₃ , Z ₄ , Z ₅ and Z ₆ are each a single bond, -CH=CH-, -C≡C-, -COO-, -OCO-, -CF ₂ O- or -OCF ₂ -, wherein -CH=CH- hydrogen may be replaced by fluorine atom; and X ₁ is -H, -F, -Cl, unsubstituted C ₁ -C ₂₀ alkyl, halo-substituted C ₁ -C ₂₀ alkyl , Unsubstituted C ₁ -C ₂₀ alkoxy group or a halogen-substituted C ₁ -C ₂₀ alkoxy; of X ₁ -CH ₂ - may be -O -, - S -, - CH = CH -, -C≡C-, -CF=CF-, -CH=CF-, -CF=CH-, -COO- or -OCO-substitution, provided that the heteroatoms are not directly linked to each other.

In one embodiment of the invention, the component represented by Formula II includes a component represented by Formula II-A and a component represented by Formula II-B: Formula II-A Formula II-B, wherein X ₂ is -H, -F, -Cl, unsubstituted C ₁ -C ₂₀ alkyl, halogen-substituted C ₁ -C ₂₀ alkyl, unsubstituted C ₁ -C ₂₀ alkoxy or C ₁ -C ₂₀ alkoxy substituted by halogen, but X ₂ does not contain -OCF ₃ ; -CH ₂ - in X ₂ may be -O-, -S-, -CH=CH- , -C≡C-, -CF=CF-, -CH=CF-, -CF=CH-, -COO- or -OCO-substitution, provided that the heteroatoms are not directly linked to each other.

In one embodiment of the present invention, the component represented by the formula II-A accounts for 4 to 60% by weight, preferably 12 to 60% by weight, more preferably 25 to 55% by weight in the liquid crystal composition; The component represented by II-B accounts for 2 to 45% by weight, preferably 2 to 30% by weight in the liquid crystal composition. The amount % is more preferably 8 to 25% by weight.

In one embodiment of the present invention, the component represented by Formula I accounts for 1 to 30% by weight, preferably 1 to 25% by weight, more preferably 4 to 15% by weight, based on Formula II, in the liquid crystal composition. The component is 5 to 70% by weight, preferably 15 to 70% by weight, more preferably 30 to 70% by weight, based on the liquid crystal composition, and the component represented by Formula III accounts for 15 to 70% by weight in the liquid crystal composition. % is preferably 15 to 60% by weight, more preferably 16 to 41% by weight.

In one embodiment of the invention, p is not equal to 0 and A ₁ comprises 2,5-infill.

In one embodiment of the invention, at least one of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ , A ₇ , A ₈ and A ₉ is .

In one embodiment of the invention, at least one of A ₅ , A ₆ and A ₇ is

In one embodiment of the invention, m+n+o+p≦4.

The liquid crystal display element of the present invention includes the liquid crystal composition of any of the foregoing embodiments.

Based on the above, the present invention provides a liquid crystal composition which has good low temperature resistance and high Tni, high Δn and high Δ ε. The liquid crystal display element is produced by using the liquid crystal composition, and the liquid crystal display element can have power saving and high contrast. And other characteristics, and can be used in outdoor environments.

The above described features and advantages of the present invention will be more apparent from the following description.

In the present specification, the range represented by "a value to another value" is a schematic representation that avoids enumerating all the values in the range in the specification. Therefore, a particular numerical range is recited and is equivalent to the disclosure of any numerical value in the range of the value and the numerical range defined by any value in the numerical range, as the The smaller value range is the same. For example, the description of the "content of 10 to 80%" is equivalent to the disclosure of the "content of 20% to 40%", regardless of whether other values are listed in the specification.

Herein, if a group is not specifically indicated to be substituted, the group may represent a substituted or unsubstituted group. For example, "alkyl" can mean a substituted or unsubstituted alkyl group.

In this context, the structure of a compound is sometimes represented by a skeleton formula. This representation can omit carbon atoms, hydrogen atoms, and carbon-hydrogen bonds. Of course, if the atom or atomic group is clearly drawn in the structural formula, the person who prescribes it shall prevail.

A first embodiment of the present invention provides a liquid crystal composition comprising a first component represented by Formula I, a second component represented by Formula II, and a third component represented by Formula III: Formula I; Formula II; Formula III.

R ₁ , R ₂ , R ₃ and R ₄ are each independently -H, C ₁ -C ₁₅ alkyl or C ₂ -C ₁₅ alkenyl, preferably -H, C ₁ -C ₁₀ alkyl or C ₁ -C ₁₀ alkenyl, and -CH ₂ - in the aforementioned alkyl or alkenyl group may be substituted by -O-, -CO-, -COO- or -OCO-, provided that the heteroatoms are not directly bonded to each other.

A ₁ , A ₂ , A ₃ and A ₄ are each selected from the group consisting of 1,4-phenylene, 1,4-cyclohexylene, 2,5-indan and 2,5-tetrahydropyranyl. a group wherein the hydrogen on the 1,4-phenylene group, the 1,4-cyclohexylene group and the 2,5-indan may be unsubstituted or substituted by a fluorine atom, and A ₁ , A ₂ , A ₃ and A ₄ At least one of them is 2,5-filled.

A ₅ , A ₆ , A ₇ , A ₈ and A ₉ are respectively selected from the group consisting of 1,4-phenylene, 1,4-cyclohexylene and 2,5-tetrahydropyranyl, wherein 1 The hydrogen on the 4-phenylene group and the 1,4-cyclohexylene group may be unsubstituted or substituted by a fluorine atom.

m, n, o, and p are 0 or 1, respectively, and m+n+o+p>2.

Z ₁ , Z ₂ , Z ₃ , Z ₄ , Z ₅ and Z ₆ are a single bond, -CH=CH-, -C≡C-, -COO-, -OCO-, -CF ₂ O- or -OCF, respectively. ₂ - wherein hydrogen of -CH=CH- may be substituted by a fluorine atom.

X ₁ is -H, -F, -Cl, unsubstituted C ₁ -C ₂₀ alkyl, halogen-substituted C ₁ -C ₂₀ alkyl, unsubstituted C ₁ -C ₂₀ alkoxy or via a halogen-substituted C ₁ -C ₂₀ alkoxy group, wherein the alkyl group or the alkoxy group preferably has a carbon number of from 1 to 10; -CH ₂ - in X ₁ may be -O-, -S-, -CH= CH-, -C≡C-, -CF=CF-, -CH=CF-, -CF=CH-, -COO- or -OCO-substitution, provided that the heteroatoms are not directly linked to each other.

Since the sum of m, n, o, and p is greater than 2, and at least one of A ₁ to A ₄ is 2,5-indan (this is a compound having a bicyclic structure, and its structure can be referred to in the "Experiment" section. RI"). Therefore, the first component represented by Formula I has a relatively large number of rings (for example, 4 or more), which allows the liquid crystal composition to have a high Δ ε, a high Δn, and a high Tni, thereby further providing a liquid crystal display element containing the liquid crystal composition. Features power saving, high contrast and outdoor use. Further, in general, high Δε, high Δn, high Tni, and excellent low-temperature storage property are often difficult to coexist, but when the liquid crystal composition contains the aforementioned first to third components, not only Δε, Δn, and Tni can satisfy The application of the surface is also very good at low temperature storage. These features will be demonstrated experimentally below.

In one embodiment, p is not equal to 0 and A ₁ includes 2,5-indan. In other words, 2,5-infill is located in the first component and at the opposite end of the -OCF ₃ . More specifically, in one embodiment, p is equal to 1, A ₁ is 2,5-incomplete, and A ₂ , A _{3 ,} and A ₄ may not include 2,5-infill.

In one embodiment, the component represented by Formula I accounts for 1 to 30% by weight, preferably 1 to 25% by weight, more preferably 4 to 15% by weight in the liquid crystal composition, and the component represented by Formula II is in the The liquid crystal composition accounts for 5 to 70% by weight, preferably 15 to 70% by weight, more preferably 30 to 70% by weight, and the component represented by the formula III accounts for 15 to 70% by weight in the liquid crystal composition, preferably It is 15 to 60% by weight, more preferably 16 to 41% by weight.

In one embodiment of the invention, at least one of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ , A ₇ , A ₈ and A ₉ is . More specifically, at least one of A ₅ , A ₆ and A ₇ is .

A ₅ , A ₆ and A ₇ with or without The structure may affect the dielectric anisotropy of the liquid crystal monomer to make it a positive liquid crystal or a negative liquid crystal. However, regardless of whether or not the liquid crystal composition contains a negative liquid crystal monomer, as long as the liquid crystal composition contains both the first to third components, the effect of low-temperature storage property can be achieved.

In one embodiment of the invention, the component represented by Formula II includes a component represented by Formula II-A and a component represented by Formula II-B: Formula II-A Formula II-B.

R ₂ , A ₅ , A ₆ , A ₇ , Z ₄ , Z ₅ are the same as described above.

X ₂ is -H, -F, -Cl, unsubstituted C ₁ -C ₂₀ alkyl, halogen-substituted C ₁ -C ₂₀ alkyl, unsubstituted C ₁ -C ₂₀ alkoxy or via a halogen-substituted C ₁ -C ₂₀ alkoxy group, but X ₂ does not contain -OCF ₃ , and the carbon number of the aforementioned alkyl group and alkoxy group is preferably from 1 to 10; -CH ₂ - in X ₂ may be - O-, -S-, -CH=CH-, -C≡C-, -CF=CF-, -CH=CF-, -CF=CH-, -COO- or -OCO-substitution, provided that the hetero atom Not directly connected to each other. In other words, the component represented by Formula II may contain both a component having an end of -OCF _{3 and} a component having no -OCF ₃ at the end.

In one embodiment, the component represented by the formula II-A accounts for 4 to 60% by weight, preferably 12 to 60% by weight, more preferably 25 to 55% by weight, based on the liquid crystal composition; The component accounts for 2 to 45% by weight, preferably 2 to 30% by weight, more preferably 8 to 25% by weight, based on the liquid crystal composition.

For the synthesis method of the first component, for example, refer to the Taiwan Patent Application No. 9914-3515, entitled "Liquid Crystal Compound and Liquid Crystal Mixture", which is published on December 13, 2010, and which is published on June 1, 2012. The entire content is incorporated herein by reference to the present application as a basis for modification and interpretation of the present application. As for the second component and the third component, the liquid crystal compound is known in the art, and the synthesis method thereof will not be repeated here.

Another embodiment of the present invention provides a liquid crystal display element characterized by comprising the liquid crystal composition of any of the foregoing embodiments. Of course, the liquid crystal display element may also have other known liquid crystal display elements. A member such as a substrate, a polarizer, a color filter or an alignment film, or the like. In addition to the liquid crystal composition contained therein, the manufacturing method and constituent elements of the liquid crystal display element can be arbitrarily selected from the prior art, and therefore are not here. Said.

<experiment>

The invention will be described more specifically below with reference to examples. Although the following examples are described, the materials used, the amounts and ratios thereof, the processing details, the processing flow, and the like can be appropriately changed without departing from the scope of the invention. Therefore, the present invention should not be construed restrictively according to the embodiments described below.

Since the liquid crystal compositions of the comparative examples and the examples each contain tens of liquid crystal compounds, in order to clarify the expression, different liquid crystal compounds will be denoted hereinafter by a combination of codes, each of which represents the following structural unit.

In the code "V1", the number "1" represents a methyl group, and similarly, the number shown in a normal font represents an alkyl group having a carbon number equal to the number. For example, 3RIUQU-OCF ₃ represents a compound of the formula: And 3CCP1 represents a compound of the formula:

The liquid crystal compositions of Comparative Examples 1 to 3 and the liquid crystal compositions of Examples 1 to 14 were prepared by mixing various liquid crystal compounds in the proportions (% by weight) shown in Table 1. In Table 1, "C-1" to "C-4" represent Comparative Example 1 to Comparative Example 4, respectively; "E-01" to "E-15" represent Example 1 to Example 15, respectively.

In Table 1 and Table 1 (continued 1) of the next page, the applicant will belong to the first component (represented by Formula I), the second component (represented by Formula II-A or Formula II-B), and The various components of the three components (represented by Formula III) are clearly classified. The components described in Table 1 (continued 2) are other compounds contained in the liquid crystal composition.

Table 2 shows the performances of the liquid crystal compositions of the respective comparative examples and the respective examples in terms of Tni, Vth, Δε, γ1, Δn, and LTS (low temperature storage). These properties are determined by the following methods:

Clarification point (Tni):

Using a differential scanning calorimeter (DSC; manufacturer: TA; model: Q200), the liquid crystal compound was placed in an aluminum pan with a scale of 0.5 to 10 mg. After the aluminum pan was pressed, the phase change temperature was tested by DSC. The endothermic peak appearing in phase change and the starting point of the exothermic peak to obtain a phase change temperature. Since the liquid crystal compound is a nematic phase, it is heated from room temperature. Only the endothermic peak of the nematic phase to the liquid phase appears on the map, and the clearing point temperature (Tni) can be read.

Optical anisotropy (Δn):

The Abbe refractometer (manufacturer: ATAGO; model: DR-M2) equipped with a polarizing plate on one eyepiece was used for measurement. First, apply the alignment liquid in a single direction on the main surface of the Abbe refractometer, and wipe the alignment in the same direction with a dust-free cloth. Then, add a small amount of the test solution to the main crucible at a test temperature of 25 ° C. Optical anisotropy was measured using a filter having a wavelength of 589 nm. When the polarizing direction is parallel to the wiping direction, the measured refractive index is n∥; when the polarizing direction is perpendicular to the wiping direction, the measured refractive index is n⊥; optical anisotropy (Δn)=n∥-n⊥.

Dielectric anisotropy (Δε):

The liquid crystal compound to be tested is placed in a liquid crystal cell, and a voltage of 0 V to 20 V is applied to the liquid crystal cell at a temperature of 25 ° C, and a capacitance versus voltage curve (CV curve) is measured, in a high voltage region and a low voltage region. The CV curve will be horizontal, reading the capacitance C⊥ in the low voltage region, reading the capacitance C∥ in the high voltage region, and converting from C⊥ and C∥ to ε⊥, ε∥, dielectric anisotropy by the formula (Δε) = ε ∥ - ε ⊥.

Threshold voltage (Vth):

If the capacitance-to-voltage curve (C-V curve) is measured in the previous section, the software will automatically read the voltage value at which the capacitor starts to rise from the horizontal in the low voltage region. This voltage value is the threshold voltage (Vth).

Rotational viscosity (γ1, unit: mPa‧s):

After the dielectric anisotropy (Δε) is measured as described above, the soft body can be converted from the rotational viscosity (γ1) by the Δε value.

Low temperature storage (LTS; unit: day):

0.3 g of the liquid crystal composition was placed in a 7 mL glass bottle, and the glass bottle was placed in a constant temperature low temperature freezer at -30 ° C or -40 ° C to record the time of liquid crystal deposition, which is the number of days of low temperature storage. The longer the low temperature storage days, the better the storage.

In addition to the above properties, in order to collectively compare the liquid crystal compositions of the examples and the comparative examples, Table 2 also re-shows the total contents of the first component, the second component, and the third component in the respective examples. Referring to Table 2, if the liquid crystal composition does not contain the first component represented by Formula I (e.g., Comparative Example 1 and Comparative Example 4), liquid crystals are precipitated in less than three days in an environment of -30 °C. In particular, Example 10 and Comparative Example 4, which have substantially the same composition, can be clearly seen. Meanwhile, if the liquid crystal composition does not contain the second component represented by Formula II-A or Formula II-B (such as Comparative Example 2), or although the first to third components are contained at the same time, the content of the third component is insufficient (eg, In Comparative Example 3), the low-temperature storage property was also inferior to that of all the examples.

Further, the second components of Examples 1 to 2 are each composed of the compound represented by Formula II-A and the compound represented by Formula II-B, and their low-temperature storage properties are superior to Comparative Examples 1 to 4, and the simultaneous inclusion formula Examples 3 to 15 of the compounds II-A and II-B have better low-temperature storage properties.

In summary, the present invention provides a liquid crystal composition containing a specific first component, second component, and third component. When the liquid crystal composition contains these components, it has good low temperature resistance as well as high Tni, high Δn and high Δ ε. By using the liquid crystal composition to produce a liquid crystal display element, the liquid crystal display element can have characteristics such as power saving and high contrast, and can be applied to an outdoor environment.

Although the present invention has been described above by way of examples, it is not intended to limit the invention. Any changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the scope of protection of this application is subject to the definition of the scope of the patent application attached.

Claims (10)

A liquid crystal composition comprising: a component represented by Formula I, wherein the component represented by Formula I accounts for 4 to 30% by weight in the liquid crystal composition, a component represented by formula II, And a component represented by Formula III, the content of which is greater than 10% by weight in the liquid crystal composition, Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently -H, C ₁ -C ₁₅ alkyl or C ₂ -C ₁₅ alkenyl, and -CH ₂ - in the aforementioned alkyl or alkenyl group may be - O-, -CO-, -COO- or -OCO-substituted, provided that the heteroatoms are not directly bonded to each other; A ₁ , A ₂ , A ₃ and A ₄ are each selected from 1,4-phenylene, 1, a group consisting of 4-cyclohexylene, 2,5-indan and 2,5-extended tetrahydropyranyl, wherein 1,4-phenylene, 1,4-cyclohexylene, and 2,5-fluorene The hydrogen remaining may be unsubstituted or substituted with a fluorine atom, and at least one of A ₁ , A ₂ , A ₃ and A ₄ is 2,5-indan; A ₅ , A ₆ , A ₇ , A ₈ and A ₉ are respectively selected from the group consisting of 1,4-phenylene, 1,4-cyclohexylene and 2,5-tetrahydropyranyl, wherein 1,4-phenylene and 1,4-extension The hydrogen on the hexyl group may be unsubstituted or substituted by a fluorine atom; m, n, o, and p are 0 or 1, respectively, and m+n+o+p>2; Z ₁ , Z ₂ , Z ₃ , Z ₄ , Z ₅ and Z ₆ are each a single bond, -CH=CH-, -C≡C-, -COO-, -OCO-, -CF ₂ O- or -OCF ₂ -, wherein -CH=CH- may be hydrogen substituted by a fluorine atom; and X ₁ is -H, -F, -Cl, unsubstituted C ₁ -C ₂₀ alkyl, halo-substituted C ₁ -C ₂₀ alkyl, Substituted C ₁ -C ₂₀ alkoxy group or a halogen-substituted C ₁ -C ₂₀ alkoxy group; and X is ₁ -CH ₂ - may be -O -, - S -, - CH = CH-, -C≡C-, -CF=CF-, -CH=CF-, -CF=CH-, -COO- or -OCO-substitution, provided that the heteroatoms are not directly linked to each other. The liquid crystal composition according to claim 1, wherein the component represented by Formula II includes a component represented by Formula II-A and a component represented by Formula II-B: Wherein X ₂ is -H, -F, -Cl, unsubstituted C ₁ -C ₂₀ alkyl, halogen-substituted C ₁ -C ₂₀ alkyl, unsubstituted C ₁ -C ₂₀ alkoxy Or a C ₁ -C ₂₀ alkoxy group substituted by halogen, but X ₂ does not contain -OCF ₃ ; -CH ₂ - in X ₂ may be -O-, -S-, -CH=CH-, -C≡ C-, -CF=CF-, -CH=CF-, -CF=CH-, -COO- or -OCO-substitution, provided that the heteroatoms are not directly linked to each other. The liquid crystal composition according to claim 2, wherein the component represented by the formula II-A accounts for 4 to 60% by weight in the liquid crystal composition, and the component represented by the formula II-B is in the liquid crystal composition. 2 to 45% by weight. The liquid crystal composition according to claim 3, wherein the component represented by the formula II-A accounts for 12 to 60% by weight in the liquid crystal composition, and the component represented by the formula II-B is in the liquid crystal composition. 2 to 30% by weight. The liquid crystal composition according to claim 1, wherein the component represented by the formula II accounts for 5 to 70% by weight in the liquid crystal composition, and the component represented by the formula III is in the liquid crystal composition. It accounts for 15~70% by weight. The liquid crystal composition according to claim 5, wherein the component represented by the formula I accounts for 4 to 25% by weight in the liquid crystal composition, and the component represented by the formula II accounts for 15 to 70 in the liquid crystal composition. The component represented by the formula III accounts for 15 to 60% by weight of the liquid crystal composition. The liquid crystal composition of claim 1, wherein p is not equal to 0, and A ₁ comprises 2,5-indan. The liquid crystal composition according to claim 1, wherein at least one of A ₁ , A ₂ , A ₃ , A ₄ , A ₅ , A ₆ , A ₇ , A ₈ and A ₉ is . The liquid crystal composition of claim 1, wherein at least one of A ₅ , A ₆ and A ₇ is . A liquid crystal display element comprising the liquid crystal composition according to any one of claims 1 to 9.