JP5428164B2 - Nematic liquid crystal composition - Google Patents

Description

  The present invention relates to a nematic crystal composition having a negative dielectric anisotropy useful as an electro-optical liquid crystal display material and a liquid crystal display device using the same.

  Due to the excellent display quality, active matrix liquid crystal display devices are put on the market for portable terminals, liquid crystal televisions, projectors, computers and the like. In the active matrix display method, TFT (thin film transistor) or MIM (metal insulator metal) is used for each pixel, and high voltage holding ratio is regarded as important for this method. In order to obtain a wider viewing angle characteristic, a TFT display combined with VA, IPS, and OCB modes and a reflection type in ECB mode have been proposed to obtain a brighter display. In order to cope with such display elements, new liquid crystal compounds or liquid crystal compositions have been proposed (Patent Document 1 and Patent Document 2).

  Today, there is a demand for a liquid crystal composition having a reduced viscosity in order to increase the response speed. In addition, in order to obtain a wide operating temperature range from a low temperature region to a high temperature region, a liquid crystal composition having a wide nematic temperature range is required.

  Many bicyclohexane compounds and liquid crystal compositions using the same have been introduced to date (see Patent Documents 8 and 9), which contributed to the reduction of viscosity of liquid crystal compositions, that is, improved response speed, but further improvements are required. This is a well-known fact. In addition, these bicyclohexane compounds have high smectic properties, and when the content of the bicyclohexane compound is increased, the nematic phase lower limit temperature (Tn) increases, making it difficult to obtain a liquid crystal composition having a wide nematic temperature range. Met.

  On the other hand, as liquid crystal materials having a negative dielectric anisotropy, specific examples of the following liquid crystal compounds having a 2,3-difluorophenylene skeleton and liquid crystal compositions using the same are disclosed (see Patent Document 3). ).

  In addition, specific examples of the following liquid crystal compound having a 2,3-difluorophenylene skeleton and a liquid crystal composition using the same are disclosed (see Patent Documents 4 and 5). However, the viscosity of these liquid crystal compositions was not sufficiently low.

  Furthermore, as liquid crystal materials having negative dielectric anisotropy, the following liquid crystal compounds having a 2,3-difluorophenylene skeleton (see Patent Documents 6 and 7) are disclosed.

  However, a liquid crystal composition having a negative dielectric anisotropy composed only of the compounds described in the cited document realizes a sufficiently low viscosity in a liquid crystal composition that requires a high-speed response such as a liquid crystal television. It has not reached.

  From the above, it is difficult to obtain a liquid crystal composition having a wide liquid crystal phase temperature range, low viscosity, and negative dielectric anisotropy, and development of a liquid crystal composition that can solve these problems It was desired.

JP-A-2-233626 Special Publication 4-501575 Publication JP2007-39642 (ZAB / ZAC priority application) JP 2006-233182 (Application for priority of alkyl ZBA) JP2007-39639 (Application for priority of alkenyl ZBA) JP-A-60-199840 JP-A-2-4725 JP 59-70624 (Chisso Corporation) JP 60-16940 (Merck Patent)

  The problem to be solved is to provide a liquid crystal composition for an active matrix liquid crystal display device having a wide liquid crystal phase temperature range, low viscosity, and negative dielectric anisotropy, and an active matrix type using the same The object is to provide a liquid crystal display element.

As a result of intensive studies to solve the above problems, the present inventors have found the usefulness of a liquid crystal composition containing liquid crystal compounds having three characteristic structures, and have completed the present invention.
The present invention is a general formula (1) as a first component.

（式中、R¹は炭素数1〜15のアルキル基または炭素数2〜15のアルケニル基を表し、mは0または1を表す。）及び一般式(2)

(Wherein R ¹ represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and m represents 0 or 1) and the general formula (2)

（式中、R²は炭素数1〜15のアルキル基または炭素数2〜15のアルケニル基を表す。）で表される化合物群から選ばれる化合物を含有し、第二成分として、式(3)

(Wherein R ² represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms), and a compound selected from the group of compounds represented by formula (3 )

で表される化合物を含有し、誘電率異方性が負であることを特徴とするネマチック液晶組成物及びこれを用いた液晶表示素子に関する。

The present invention relates to a nematic liquid crystal composition containing a compound represented by the formula (1) and having a negative dielectric anisotropy, and a liquid crystal display device using the same.

  A liquid crystal composition for an active matrix liquid crystal display element, which has a lower viscosity, a wide liquid crystal phase temperature range, can adjust the refractive index anisotropy over a wide range, and is excellent in reliability by the combination of the liquid crystal compounds of the present invention was gotten. By using this liquid crystal composition, an active matrix type liquid crystal display device having a high response speed and a wide operating temperature range is provided, which is very useful as a liquid crystal display in a transmissive mode, a reflective mode or a transflective mode.

  The liquid crystal composition in the present invention is characterized by containing a compound selected from the compound group represented by the general formula (1) and the general formula (2) and a compound represented by the formula (3). The content may be 5 to 60% of a compound selected from the compound group represented by the general formula (1) and the general formula (2), and 5 to 25% of the compound represented by the formula (3). Preferably, it contains 20 to 60% of a compound selected from the group of compounds represented by general formula (1) and general formula (2), and 10 to 20% of a compound represented by formula (3). Particularly preferred.

In the general formula (1), R ¹ represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, more preferably an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms. Preferably, an alkyl group having 2 to 5 carbon atoms is particularly preferable.

In the general formula (2), R ² represents an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, more preferably an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms. An alkenyl group having 2 to 5 carbon atoms is preferable.

In order to adjust the physical properties of the liquid crystal composition of the present invention, the general formula (4) and the general formula (5)

（式中、R³及びR⁴はそれぞれ独立して炭素数1〜10のアルキル基、アルコキシル基または炭素数2〜10のアルケニル基を表し、R⁵及びR⁶はそれぞれ独立して炭素数1〜10のアルキル基またはアルコキシル基を表し、A〜Eはそれぞれ独立的してトランス-1,4-シクロへキシレン基または1,4-フェニレン基を表すが、これらの基中の水素原子はそれぞれ独立して-CH3、-Fまたは-Clで置換されていても良く、L¹〜L⁴はそれぞれ独立して単結合、-CH₂CH₂-、-(CH₂)₄-、-CH=CH-、-COO-、-OCH₂-、-CH₂O-、-OCF₂-または-CF₂O-を表し、n及びoはそれぞれ独立して0〜2を表し、X¹〜X²はそれぞれ独立して水素原子、-Fまたは-Clを表す。）で表される化合物群から選ばれる1種または2種以上の化合物を含有しても良い。但し、該化合物群から一般式(2)及び式(3)で表される化合物は除かれる。

(In the formula, R ³ and R ⁴ each independently represent an alkyl group having 1 to 10 carbon atoms, an alkoxyl group, or an alkenyl group having 2 to 10 carbon atoms, and R ⁵ and R ⁶ each independently represent 1 carbon atom. Represents an alkyl group or an alkoxyl group of -10, and A to E each independently represent a trans-1,4-cyclohexylene group or a 1,4-phenylene group, and the hydrogen atoms in these groups are independently --CH3, may be substituted by -F or -Cl, L ¹ ~L ⁴ each independently represent a single _{bond, -CH 2 CH 2 -, -} (CH 2) 4 -, - CH = CH—, —COO—, —OCH ₂ —, —CH ₂ O—, —OCF ₂ — or —CF ₂ O—, each independently represents 0 to 2, and X ^{1 to} X ² Each independently represents a hydrogen atom, -F or -Cl.) And may contain one or more compounds selected from the group of compounds represented by: However, the compounds represented by the general formulas (2) and (3) are excluded from the compound group.

  When it contains the compound chosen from the compound group represented by General formula (4) and General formula (5), 1 type-15 types are preferable and 1 type-5 types are more preferable.

  When the compound selected from the compound group represented by the general formula (4) and the general formula (5) is contained, the content is preferably 5 to 40%, and particularly preferably 5 to 25%.

In the general formula (5), X ^{1 to} X ² each independently represent —H, —F or —Cl, more preferably —H or —F, and particularly preferably X ¹ = X ² = −F.

  More specifically, the following compounds are preferred as specific structures of the general formula (4).

（式中R⁷及びR⁸はそれぞれ独立して、炭素数1〜5のアルキル基またはアルコキシル基、炭素数2〜5のアルケニル基またはアルケニルオキシ基を表し、フェニル基中の水素原子は-Fで置換されていても良い。）

(Wherein R ⁷ and R ⁸ each independently represents an alkyl group or alkoxyl group having 1 to 5 carbon atoms, an alkenyl group or alkenyloxy group having 2 to 5 carbon atoms, and a hydrogen atom in the phenyl group represents —F May be replaced with.)

  The following compounds are preferred as the specific structure of the general formula (5).

（式中R⁹及びR¹¹は炭素数1〜5のアルキル基、R¹⁰は炭素数1〜5のアルキル基またはアルコキシル基を表す。）

(Wherein R ⁹ and R ¹¹ represent an alkyl group having 1 to 5 carbon atoms, and R ¹⁰ represents an alkyl group or alkoxyl group having 1 to 5 carbon atoms.)

  In addition to the above compounds, normal nematic liquid crystals, smectic liquid crystals, cholesteric liquid crystals, and the like may be contained.

In the present invention, the nematic phase-isotropic liquid phase transition temperature (T _NI ) is 68 to 120 ° C, more preferably 70 to 105 ° C, and particularly preferably 75 to 95 ° C. The solid phase or smectic phase-nematic phase transition temperature (T _{→ N} ) is -80 to -20 ° C, more preferably -30 ° C or less, and particularly preferably -40 ° C or less. The refractive index anisotropy (Δn) at 25 ° C. is 0.05 to 0.15, more preferably 0.07 to 0.13, and particularly preferably 0.08 to 0.11. The dielectric anisotropy (Δε) at 25 ° C. is −1.5 to −8.0, more preferably −1.5 to −6.0, and particularly preferably −1.5 to −5.5.

  The nematic liquid crystal composition of the present invention is useful for a liquid crystal display device, but is particularly useful for a liquid crystal display device for active matrix driving, and can be used for a liquid crystal display device for a transmission mode, a reflection mode and a transflective mode.

  Hereinafter, although an example is given and this invention is further explained in full detail, this invention is not limited by these. “%” Means “% by mass”.

T _NI : Nematic phase-isotropic liquid phase transition temperature (℃) is the upper limit temperature of liquid crystal phase
T _{→ N} : The solid phase or smectic phase-nematic phase transition temperature (° C.) is the liquid crystal phase lower limit temperature.
Δε: dielectric anisotropy at 25 ° C. Δn: refractive index anisotropy at 25 ° C. η: viscosity at 20 ° C.
VHR: Retention rate at 60 ° C (%)
(The value is expressed in% as the ratio of the measured voltage to the initial applied voltage when injected into a VA-LCD with a cell thickness of 3.5 μm and measured with 5 V applied, frame time 16.7 ms, and pulse width 64 μs.)

The following abbreviations are used in the description of compounds.
Terminal n (number) C _n H _{2n + 1-}
-2- -CH ₂ CH ₂ -
-1O- -CH ₂ O-
-O1- -OCH _2-
-On -OC _n H _{2n + 1}
ndm- C _n H _{2n + 1} -C = C- (CH ₂ ) _m-1-

  Table 1 shows the compositions and physical property values of Example 1 (No. 1), Comparative Example 1 (R1) and Comparative Example 2 (R2) of the present invention.

Example 1 (No. 1), which is the liquid crystal composition of the present invention, has a sufficiently low T _{→ N} and η is greatly reduced compared to Comparative Example 1 (R1) and Comparative Example 2 (R2). The other physical property values were equivalent or higher. On the other hand, Comparative Example 1 (R1), which is a liquid crystal composition described in Patent Document 3, does not include General Formula (2), which is an essential component of the present invention, and Comparative Example 2 (R2) is an essential component of the present invention. Some general formula (1) was not included, and problems such as high η and high T _{→ N} remained. From the above, Example 1 (No. 1), which is the liquid crystal composition of the present invention, is excellent in low-temperature stability because T _{→ N} is low, the liquid crystal phase temperature range is wide, and the viscosity η related to the response speed is It turns out that it is very low.

  Table 2 shows the compositions and physical property values of Example 2 (No. 2), Example 3 (No. 3) and Comparative Example 3 (R3) of the present invention.

Example 2 (No. 2) and Example 3 (No. 3), which are liquid crystal compositions of the present invention, have a sufficiently low T _{→ N and a} large reduction in η compared to Comparative Example 3 (R3). It had been. From the above, Example 2 (No. 2) and Example 3 (No. 3), which are liquid crystal compositions of the present invention, have excellent low-temperature stability because T _{→ N} is low, and the liquid crystal phase temperature range is wide, Moreover, it can be seen that the viscosity η related to the response speed is very low.

  Table 3 shows the composition and physical property values of Example 4 (No. 4) of the present invention.

In Example 4 (No. 4) which is the liquid crystal composition of the present invention, it was confirmed that T _{→ N} was low and η was also low. From the above, it can be seen that Example 4 (No. 4) which is a liquid crystal composition of the present invention is excellent in low-temperature stability, has a wide liquid crystal phase temperature range, and has a very low viscosity η.

Claims (7)

General formula (1) as the first component

(Wherein R ¹ represents an alkyl group having 1 to 15 carbon atoms, and m represents 0 or 1) and the general formula (2)

(Wherein, R ² represents. An alkenyl group of alkyl or 2 to 15 carbon atoms having 1 to 15 carbon atoms) contains a compound selected from the group consisting of compounds represented by,
As the second component, the formula (3)

A nematic liquid crystal composition comprising a compound represented by formula (1) and having a negative dielectric anisotropy. In the general formula (1), nematic liquid crystal composition according to claim 1, wherein R ¹ is wherein the Dearuko alkyl group having 2 to 5 carbon atoms. 3. The nematic liquid crystal composition according to claim 1, wherein in the general formula (2), R ² is an alkenyl group having 2 to 5 carbon atoms. The nematic liquid crystal composition according to any one of claims 1 to 3, wherein the compound is contained in an amount of 5 to 60% by mass from the group consisting of the compounds represented by the general formula (1) and the general formula (2). The liquid crystal display device using a nematic composition according to any one of claims 1 to 4. A liquid crystal display element for driving an active matrix using the nematic composition according to any one of claims 1 to 4. A VA mode, IPS mode or ECB mode liquid crystal display element using the nematic composition according to any one of claims 1 to 3.