JP4348594B2 - Nematic liquid crystal composition and liquid crystal display device using the same - Google Patents

Description

(各式中、R¹及びR²は、それぞれ独立的に炭素原子数1〜10のアルキル基、炭素原子数2〜10のアルケニル基又は炭素原子数1〜10のアルコキシル基を表し、Aは(a)〜(d)から選ばれる基を表し、
【００１０】
【化７】

Bは、トランス-1,4-シクロヘキシレン基、1,4-フェニレン基又は1個若しくは2個のフッ素原子を有する1,4-フェニレン基であり、Dは(e)〜(h)から選ばれる基を表し、
【００１１】
【化８】

Z¹及びZ²はそれぞれ独立的に単結合又は-CH₂CH₂-を表し、
X¹〜X¹⁴はそれぞれ独立的にF、Cl又はHを表す。
Y¹〜Y⁵はそれぞれ独立的に、F、Cl、CF₃、OCF₃、OCHF₂又はOCH₂Fを表わす。)からなる群から少なくとも1種選ばれた化合物を20〜60質量%含有し、
【００１２】
一般式(2)
【化９】

(式中、R³及びR⁴は、それぞれ独立的に炭素原子数1〜10のアルキル基、炭素原子数2〜10のアルケニル基又は炭素原子数1〜10のアルコキシル基を表し、E及びGはそれぞれ独立的に、トランス-1,4-シクロヘキシレン基又は1,4-フェニレン基を表し、Z³は単結合、-CH₂CH₂-又は-C≡C-を表す。)で表される化合物10〜40質量%を含有し、
【００１３】
一般式(3)
【化１０】

(式中、R⁵は炭素原子数1〜10のアルキル基、炭素原子数2〜10のアルケニル基又は炭素原子数1〜10のアルコキシル基を表し、J、K及びLはそれぞれ独立的に、トランス-1,4-シクロヘキシレン基、1,4-フェニレン基又は1個若しくは2個のフッ素原子を有する1,4-フェニレン基であり、Z⁴ 、Z⁵ 及びZ⁶は単結合又は-CH₂CH₂-を表し、X¹⁵及びX¹⁶はそれぞれ独立的にF、Cl又はHを表し、Y⁶はF、Cl、CF₃、OCF₃、OCHF₂又はOCH₂Fを表わす。)で表される化合物20〜50質量%を含有し、ネマチック相−等方性液体相転移温度が75℃〜120℃であり、誘電率異方性が3〜8であり、屈折率異方性が0.075〜0.160である液晶組成物を提供する。
【００１４】
【発明の実施の形態】
（誘電率異方性が正の化合物）
既存のΔεが正である(以下Δεが正であることをP型と言う。)フルオロ2環系液晶化合物はネマチック相−等方性液体相転移温度(Tni)が-100℃〜-20℃と低く、液晶組成物の液晶温度範囲を実用レベルにすることが困難なことから、従来はP型フルオロ3環系化合物主体の組成物となっていた。液晶表示素子の駆動電圧を低くするためには、液晶組成物のしきい値電圧を低くする必要がある。
【００１５】
しかし、Δεが同じ大きさのP型フルオロ2環系からP型フルオロ3環系へ置換すると、P型フルオロ3環系化合物主体系組成物のしきい値電圧は、Δεの割に小さくならない傾向がみられた。
【００１６】
一方、縮合環を有する一般式(1-1)及び一般式(1-2)からなる群から選ばれる化合物(以下、化合物(1)と言う。)はTniが-70℃〜40℃であり、既存のP型フルオロ2環系化合物よりもTniが高い。
【００１７】
化合物(1)と、特定のP型4環系化合物と、減粘効果の高く極性の小さい2環系化合物とを用いて、液晶組成物のTniを75〜120℃にし、屈折率異方性(Δn)を0.075〜0.160にし、Δεを3〜8にした液晶組成物は、従来の液晶組成物で得られる「しきい値電圧」と、液晶組成物の「Δε」との関係より、より小さいΔεで同等のしきい値電圧が達成されることを見いだした。
【００１８】
さらに、従来では液晶温度範囲を拡大するために用いた3環系の極性の小さい化合物の代わりに、減粘効果の大きい2環系の極性の小さい化合物を用いるため、低粘性の液晶組成物を得ることも可能になった。
【００１９】
以下に本発明を更に詳細に説明する。
(化合物(1))
化合物(1)は1〜10種含有されることが好ましく、1〜5種がさらに好ましい。化合物(1)の含有率は25〜50質量%の範囲が好ましく、30〜45質量%がより好ましい。また、一般式(1-1)で表される化合物を25〜60質量%含有することが好ましい。
【００２０】
含有率が20質量%より小さいと、しきい値電圧を低下させることが難しく、含有量が60%より大きいと、ネマチック相−等方性液体相転移温度が低く、粘度が上昇しやすくなる。
【００２１】
一般式(1-1)及び(1-2)における各基の好ましい態様として、次の基を挙げることができる。
R¹及びR²は、それぞれ独立に炭素数1〜7のアルキル基が好ましく、炭素数2〜5のアルキル基が特に好ましい。
Aは、低いしきい値電圧を必要とする場合は、(a)及び(b)が好ましく、特にX³〜X⁵の少なくとも1つがFである(a)若しくは、X⁶及びX⁷の少なくとも1つがFである(b)が好ましい、特にX³がFである若しくはX³〜X⁵の少なくとも2つ以上がFである(a)及びX⁶及びX⁷の両方がFである(b)が最も好ましい。
【００２２】
小さいΔnを必要とする場合は、(b)、(c)及び(d)が好ましく、特に(d)が好ましい。
Z¹及びZ²は、単結合であることが好ましい。
X¹及びX²は少なくとも1つがFであることが好ましく、両方がFであることが更に好ましい。
Y¹は、F又はOCF₃であることが好ましく、Fが最も好ましい。
【００２３】
Bは、少なくとも1個のFで置換された1,4-フェニレン基及びトランス-1,4-シクロヘキシレン基が好ましく、小さいΔnを必要とする場合は、トランス-1,4-シクロヘキシレン基が好ましい。
Dは、低いしきい値電圧を必要とする場合は、(e)及び(f)が好ましく、特にX⁹〜X¹¹の少なくとも1つがFである(e)若しくは、X¹²及びX¹³の少なくとも1つがFである(f)が好ましい、特にX⁹がFである若しくはX⁹〜X¹¹の少なくとも2つ以上がFである(e)及び、X¹²及びX¹³の両方がFである(f)が最も好ましい。
【００２４】
化合物(1)のより好ましい形態は、一般式(1-1a)〜(I-1h)で表される化合物及び一般式(1-2a)〜(1-2g)で表される化合物である。
【００２５】
【化１１】

（各式中、R¹は、一般式(1-2)におけるR¹と同じ意味を有する。）
【００２６】
【化１２】

（各式中、R²は、一般式(1-2)におけるR²と同じ意味を有する。）
【００２７】
(化合物(2))
一般式(2)で表される化合物(以下、化合物(2)と言う。)の含有率は10〜30質量%が好ましく、15〜25質量%がより好ましい。10質量%より少ないとしきい値電圧低下の効果及び減粘効果が得られにくく、40質量%より多いと液晶組成物のネマチック相−等方性液体相転移温度が低下する。
一般式(2)における各基の好ましい態様として、次の基を挙げることができる。
R³及びR⁴は、それぞれ独立に炭素数1〜7のアルキル基又は炭素数2〜7のアルケニル基が好ましく、炭素数1〜5のアルキル基又は2〜5のアルケニル基がより好ましい。R³とR⁴の両方が炭素数2〜5のアルケニル基が特に好ましい。
E及びGはそれぞれ独立に、トランス-1,4-シクロヘキシレン基が好ましい。
Z³は、Δnを大きくするためには、単結合又は-C≡C-が好ましく、Δnを小さくするためには、単結合又は-CH₂CH₂-が好ましい。
【００２８】
化合物(2)のより好ましい形態は、一般式(2a)〜(2d)で表される化合物である。
【化１３】

（各式中、R³及びR⁴は、一般式(2)におけると同じ意味を有する。）
【００２９】
化合物(2)におけるR³及びR⁴がアルケニル基である場合は、式(a)〜(c)
【化１４】

で表されるアルケニル基が特に好ましい。
【００３０】
(化合物(3))
一般式(3)で表される化合物(以下、化合物(3)と言う。)の含有率は20〜40質量%がより好ましく、20〜30質量%がより好ましい。
R⁵は炭素原子数1〜5のアルキル及び炭素原子数2〜5のアルケニル基が好ましい。
J、K及びLは、Δnを小さくするためには、トランス-1,4-シクロヘキシレン基が好ましく、Δnを大きくするためには、1,4-フェニレン基が好ましい。
X¹⁵とX¹⁶の少なく一方がFであることが好ましく、両方がFであることがより好ましい。Y⁶はFであることが好ましい。
【００３１】
化合物(3)のより好ましい形態は、一般式(3a)〜(3d)で表される化合物である。
【化１５】

（式中、R⁵は一般式(3)におけるR⁵と同じ意味を有する。）
化合物(3)を10質量%以上使用するときは、(3a)及び(3b)からなる群から1種と、(3c)及び(3d)からなる群から1種を同時に使用することが好ましい。
【００３２】
(その他の成分)
本発明の液晶組成物は、上記化合物(1)、化合物(2)及び化合物(3)以外に、他のネマチック液晶、スメクチック液晶、コレステリック液晶及び光学活性物質(キラル剤)などを含有していてもよい。
【００３３】
本発明の液晶組成物は、Δεを或る特定の値に設定した場合、従来の組成物に比べて90°捻れツイストセルで測定したしきい値電圧(Vth)を10%〜30%低くすることができる。また、逆に或るVthを達成するのに必要なΔεの値を5%〜20%減少させることができる。
【００３４】
一般的に液晶表示素子を低電圧駆動にするためには、液晶組成物のΔεを大きくする必要がある。しかしΔεを大きくすると、液晶を注入したセルの電気容量が増加し、駆動するにあたっての回路に負荷がかかり、駆動波形に対する応答が悪くなる。また、液晶材料のΔεが大きいと電圧保持率が悪化するため、Δεを小さくして駆動できることは、非常に有用である。
【００３５】
本発明の液晶組成物を使用し、6μmセル厚の90°捻れツイストセルで測定したしきい値電圧(Vth)と液晶組成物のΔεの関係が、式 Vth≦−0.225 Δε＋3.12を満たす液晶表示素子を作製することができる。
【００３６】
【実施例】
以下、実施例を挙げて本発明を詳述するが、本発明はこれらの実施例に限定されるものではない。以下の実施例及び比較例の組成物における「%」は「質量%」を意味する。
【００３７】
実施例中、測定した特性は以下の通りである。
Tni ：ネマチック相−等方性液体相転移温度(℃)
T_{→ n} ：固体相又はスメクチック相−ネマチック相転移温度(℃)
Vth ：25℃でセル厚6.0μmのTN-液晶表示素子を構成したとき、初期状態から透過率が10%変化するのに必要な電圧(V)
Δn ：屈折率異方性（25℃）
η ：25℃での回転粘度（mPa・s）
90°捻れTN液晶表示素子の作製は以下のようにして行った。
【００３８】
対向する平面透明電極上に配向膜「AL-1051」(JSR社製)を塗布し、この配向膜をラビングして配向状態を形成したツイスト角90°のTN-LCDセルを作製し、このセルにカイラル化合物を添加した液晶組成物を注入してTN液晶表示素子を作製した。
【００３９】
化合物記載に下記の略号を使用する。
-n 数字 ：-C_nH_2n+1 (アルキル側鎖は数字。)
-On ：-OC_nH_2n+1
-ndm ：-(C_nH_2n+1-CH=CH-(CH₂)_m-1)
ndm- ：C_nH_2n+1-CH=CH-(CH₂)_m-1-
-Od(m)n ：-O(C_nH_2n+1-CH=CH-(CH₂)_m-2)
d(m)nO- ：C_nH_2n+1-CH=CH-(CH₂)_m-2O-
連結基
-VO- ：-COO- -T- ：-C≡C-
-2- ：-CH₂CH₂-
置換基
-CN ：-C≡N -F ：-F -OCF₃ ：-OCF₃
【００４０】
環
【化１６】

【００４１】
(実施例1、2と比較例1、2)
本願発明の液晶組成物No.1(実施例1)、液晶組成物No.2(実施例2)と、本願発明外の液晶組成物M1(比較例1)及び液晶組成物M2(比較例2)を調製した。また、これらの液晶組成物を使用した90°捻れのTN-LCDを作製した。それぞれの液晶組成物には、必要な捻れ(ピッチ100μm)を付与するためにカイラル化合物(コレステリックノナネート)を添加した。表1には、これらの液晶組成物の組成比と液晶組成物を使用したTN-LCDの特性測定値を示す。下記の実施例1及び2に記載の液晶組成物は4V駆動TFT液晶表示素子用として使用することができる。
【００４２】
【表１】

【００４３】
表中、(化1)は化合物(1)、(化2)は化合物(2)、(化3)は化合物(3)を示す。
【００４４】
実施例1のNo.1は、比較例1のM1よりもTniが2℃高くT_{→ n} が同等で、液晶温度範囲を若干拡大しており、Δnを0.093から0.080へと小さくし、Vthを1.73Vから1.50Vと約12%小さくしたにもかかわらず、Δεは6.7から5.7へと約15%小さくできた。
【００４５】
実施例2のNo.2は、比較例2のM2と比べて、Tni、T_{→ n}、Δn、Vth、ηとほぼ同等の物性値であるにもかかわらず、Δεは7.4から6.1へと約18%小さくできた。
【００４６】
(実施例3〜7と比較例3〜5)
本願発明の液晶組成物No.3(実施例3)、No.4(実施例4)、No.5(実施例5)、No.6(実施例6)と液晶組成物No.7(実施例7)と、本願発明外の液晶組成物M3(比較例3)、液晶組成物M4(比較例4)及び液晶組成物M5(比較例5)を調製した。それぞれの液晶組成物には、必要な捻れ(ピッチ100μm)を付与するためにカイラル化合物(コレステリックノナネート)を添加した。また、これらの液晶組成物を使用した90°捻れのTN-LCDを作製した。表2には、これらの液晶組成物の組成比と液晶組成物を使用したTN-LCDの特性測定値を示す。下記の実施例3〜7に記載の5組成物は5V駆動TFT液晶表示素子用として使用することができる。
【００４７】
【表２】

【００４８】
実施例3の液晶組成物No.3は、比較例4の液晶組成物M4よりもVthが2.17Vから1.95Vへと約10%小さくしたにもかかわらず、Δεは4.7から4.6と若干小さくでき、Δεを大きくすることなくしきい値電圧を小さくできた。
【００４９】
実施例4の液晶組成物No.4は、比較例3の液晶組成物M3よりもVthを1.81Vから1.62Vへ約10%と小さくしたにもかかわらず、Δεは6.4から4.8へと約25%と大幅に小さくできた。
【００５０】
実施例5の液晶組成物No.5は、比較例4の液晶組成物M4よりもVthを2.17Vから1.85Vへと約15%小さくしたにもかかわらず、Δεは4.7から4.6へと若干小さくできた。
【００５１】
実施例6の液晶組成物No.6は、比較例4の液晶組成物M4よりもVthを2.17Vから1.95Vへと約10%小さくしたにもかかわらず、Δεは4.7と同等であった。
【００５２】
実施例7の液晶組成物No.7は、比較例5の液晶組成物M5よりも、Vthを1.98Vから1.95Vへと若干小さくしたにもかかわらず、Δεは5.3から4.1へと約23%と大幅に小さくすることができた。
【００５３】
上記の実施例1〜7及び比較例1〜5のVthと液晶組成物のΔεを図1にプロットした。比較例に比べて実施例が同じΔεで比較すると低いVthを示すことが明らかである。実施例のプロットから、本発明の組成物は、式 Vth ≦−0.225 Δε＋3.12 を満たす液晶表示素子を作製することができることがわかる。
【００５４】
(実施例8、10〜13及び比較例6〜11)
本願発明の液晶組成物No.8(実施例8)、No.10(実施例10)、No.11(実施例11)、液晶組成物No.12(実施例12)、液晶組成物No.14(実施例14)及び本願発明外の液晶組成物M6(比較例6)、液晶組成物M7(比較例7)、液晶組成物M8(比較例8)、液晶組成物M9(比較例9)、液晶組成物M10(比較例10)及び液晶組成物M11(比較例11)を調製した。それぞれの液晶組成物には、必要な捻れ(ピッチ100μm)を付与するために実施例1及び2と同様にカイラル化合物(コレステリックノナネート)を添加した。また、これらの液晶組成物を使用した90°捻れのTN-LCDを作製した。表3及び表4には、これらの液晶組成物の組成比と液晶組成物を使用したTN-LCDの特性測定値を示す。
【００５５】
【表３】

表中、(化1)は化合物(1)、(化2)は化合物(2)、(化3)は化合物(3)を示す。
【００５６】
【表４】

表中、(化1)は化合物(1)、(化2)は化合物(2)、(化3)は化合物(3)を示す。
【００５７】
【表５】

表中、(化1)は化合物(1)、(化2)は化合物(2)、(化3)は化合物(3)を示す。
【００５８】
上記の実施例8〜14及び比較例6〜11のVthと液晶組成物のΔεを、実施例1〜7及び比較例1〜5を併せて図2にプロットした。比較例に比べて実施例が同じΔεで比較すると低いVthを示すことが明らかである。実施例のプロットから、本発明の組成物は、式 Vth ≦−0.225 Δε＋3.12 を満たす液晶表示素子を作製することができることがわかる。
【００５９】
【発明の効果】
本発明の液晶組成物は、所望の駆動電圧を達成するのに必要な誘電率異方性を通常より小さくすることができる。
【図面の簡単な説明】
【図１】実施例1〜7及び比較例1〜5のVthと液晶組成物のΔεをプロットしたグラフ
【図２】実施例1〜14及び比較例1〜11のVthと液晶組成物のΔεをプロットしたグラフ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nematic liquid crystal composition useful as a liquid crystal display material and a liquid crystal display element using the same.
[0002]
[Prior art]
In recent years, liquid crystal display elements have been used for various purposes. In particular, there is an increasing demand for an active matrix type display element with higher display quality. As the application expands, it can operate in a wider temperature range, has a quick response, and is required to be driven at a lower voltage in order to reduce power consumption. Usually, in order to reduce the voltage of a liquid crystal display element, it is necessary to increase Δε of the liquid crystal composition in the element. On the other hand, in an active matrix type display element represented by a TFT drive liquid crystal display element, a high voltage holding ratio is required to maintain display quality.
[0003]
WO98 / 17664 proposes a liquid crystal compound and a liquid crystal composition having a large dielectric anisotropy (Δε) in order to cope with low voltage driving while maintaining as high a voltage holding ratio as possible.
[0004]
[Problems to be solved by the invention]
However, when Δε of the liquid crystal composition is increased, the voltage holding ratio is lowered, and the contrast is lowered in the active drive liquid crystal display element. Therefore, there has been a demand for a liquid crystal composition that can maintain a high voltage holding ratio and can be driven at a low voltage.
[0005]
Further, when a liquid crystal composition having a small Δε is used, the capacitance of the liquid crystal layer in the liquid crystal display element becomes small, and the load on driving is reduced.
[0006]
For this reason, a liquid crystal composition that can achieve an equivalent threshold voltage with a smaller Δε is sought from the relationship between the “threshold voltage” obtained with a conventional liquid crystal composition and the “Δε” of the liquid crystal composition. It has been.
[0007]
The problem to be solved by the present invention is to provide a liquid crystal composition having a smaller dielectric constant anisotropy necessary to achieve a desired driving voltage than a normal liquid crystal composition.
[0008]
[Means for Solving the Problems]
As a result of studying liquid crystal compositions using various liquid crystal compounds in order to solve the above problems, the present inventor has solved the above problems by a liquid crystal composition containing a specific compound and a liquid crystal display device using the same. I found something to be done.
[0009]
That is, the present invention is a general formula (1-1) and (1-2)
[Chemical 6]

(In each formula, R ¹ and R ² each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms; represents a group selected from (a) to (d),
[0010]
[Chemical 7]

B is a trans-1,4-cyclohexylene group, 1,4-phenylene group, or a 1,4-phenylene group having one or two fluorine atoms, and D is selected from (e) to (h) Represents a group
[0011]
[Chemical 8]

Z ¹ and Z ² each independently represent a single bond or —CH ₂ CH ₂ —,
X ^{1 to} X ¹⁴ each independently represents F, Cl or H.
Y ^{1 to} Y ⁵ each independently represent F, Cl, CF ₃ , OCF ₃ , OCHF ₂ or OCH ₂ F. 20 to 60% by mass of a compound selected from the group consisting of:
[0012]
General formula (2)
[Chemical 9]

(Wherein R ³ and R ⁴ each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms, and E and G Each independently represents a trans-1,4-cyclohexylene group or a 1,4-phenylene group, and Z ³ represents a single bond, —CH ₂ CH ₂ — or —C≡C—. Containing 10-40% by mass of
[0013]
General formula (3)
Embedded image

(In the formula, R ⁵ represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms, and J, K and L are each independently, A trans-1,4-cyclohexylene group, a 1,4-phenylene group, or a 1,4-phenylene group having one or two fluorine atoms, and Z ⁴ , Z ⁵ and Z ⁶ are a single bond or —CH ₂ CH _2- , X ¹⁵ and X ¹⁶ each independently represent F, Cl or H, and Y ⁶ represents F, Cl, CF ₃ , OCF ₃ , OCHF ₂ or OCH ₂ F). The nematic phase-isotropic liquid phase transition temperature is 75 ° C. to 120 ° C., the dielectric anisotropy is 3 to 8, and the refractive index anisotropy is 0.075. Provided is a liquid crystal composition which is ˜0.160.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(Compound with positive dielectric anisotropy)
The existing Δε is positive (hereinafter, “Δε is positive” is referred to as P-type). The fluorobicyclic liquid crystal compound has a nematic phase-isotropic liquid phase transition temperature (Tni) of −100 ° C. to −20 ° C. Since it is difficult to bring the liquid crystal temperature range of the liquid crystal composition to a practical level, it has heretofore been a composition mainly composed of a P-type fluorotricyclic compound. In order to lower the driving voltage of the liquid crystal display element, it is necessary to lower the threshold voltage of the liquid crystal composition.
[0015]
However, when a P-type fluorotricyclic system having the same Δε is replaced with a P-type fluorotricyclic system, the threshold voltage of the P-type fluorotricyclic compound-based composition tends not to be as small as Δε. Was seen.
[0016]
On the other hand, a compound selected from the group consisting of general formula (1-1) and general formula (1-2) having a condensed ring (hereinafter referred to as compound (1)) has Tni of −70 ° C. to 40 ° C. Tni is higher than existing P-type fluorobicyclic compounds.
[0017]
Using compound (1), a specific P-type tetracyclic compound, and a bicyclic compound with high viscosity reducing effect and low polarity, the Tni of the liquid crystal composition is adjusted to 75 to 120 ° C., and the refractive index anisotropy A liquid crystal composition having (Δn) of 0.075 to 0.160 and Δε of 3 to 8 has a greater relationship between the “threshold voltage” obtained with the conventional liquid crystal composition and the “Δε” of the liquid crystal composition. We have found that comparable threshold voltages are achieved with small Δε.
[0018]
Furthermore, instead of the tricyclic low polarity compound used to expand the liquid crystal temperature range in the past, a bicyclic low polarity compound with a large viscosity reducing effect is used. It became possible to get.
[0019]
The present invention is described in further detail below.
(Compound (1))
It is preferable that 1-10 types of compounds (1) are contained, and 1-5 types are more preferable. The content of compound (1) is preferably in the range of 25 to 50% by mass, more preferably 30 to 45% by mass. Moreover, it is preferable to contain 25-60 mass% of compounds represented by general formula (1-1).
[0020]
When the content is less than 20% by mass, it is difficult to lower the threshold voltage, and when the content is more than 60%, the nematic phase-isotropic liquid phase transition temperature is low and the viscosity tends to increase.
[0021]
Preferable embodiments of each group in the general formulas (1-1) and (1-2) include the following groups.
R ¹ and R ² are each independently preferably an alkyl group having 1 to 7 carbon atoms, particularly preferably an alkyl group having 2 to 5 carbon atoms.
When A requires a low threshold voltage, (a) and (b) are preferred, and in particular, at least one of X ^{3 to} X ⁵ is F (a), or at least X ⁶ and X ⁷ (B) in which one is F is preferred, in particular X ³ is F or at least two of X ^{3 to} X ⁵ are F (a) and both X ⁶ and X ⁷ are F (b ) Is most preferred.
[0022]
When a small Δn is required, (b), (c) and (d) are preferable, and (d) is particularly preferable.
Z ¹ and Z ² are preferably single bonds.
At least one of X ¹ and X ² is preferably F, and more preferably both are F.
Y ¹ is preferably F or OCF ₃ and most preferably F.
[0023]
B is preferably a 1,4-phenylene group and a trans-1,4-cyclohexylene group substituted with at least one F. When a small Δn is required, the trans-1,4-cyclohexylene group is preferable.
D is preferably (e) and (f) when a low threshold voltage is required, in particular, at least one of X ^{9 to} X ¹¹ is F (e), or at least X ¹² and X ¹³ (F) in which one is F is preferred, in particular, X ⁹ is F or at least two of X ^{9 to} X ¹¹ are F (e), and both X ¹² and X ¹³ are F ( f) is most preferred.
[0024]
More preferred forms of the compound (1) are the compounds represented by the general formulas (1-1a) to (I-1h) and the compounds represented by the general formulas (1-2a) to (1-2g).
[0025]
Embedded image

(In each formula, R ¹ has the same meaning as R ¹ in formula (1-2).)
[0026]
Embedded image

(In each formula, R ² has the same meaning as R ² in formula (1-2).)
[0027]
(Compound (2))
The content of the compound represented by the general formula (2) (hereinafter referred to as the compound (2)) is preferably 10 to 30% by mass, and more preferably 15 to 25% by mass. If it is less than 10% by mass, it is difficult to obtain the effect of lowering the threshold voltage and the effect of reducing the viscosity, and if it exceeds 40% by mass, the nematic phase-isotropic liquid phase transition temperature of the liquid crystal composition is lowered.
As preferred embodiments of each group in the general formula (2), the following groups can be exemplified.
R ³ and R ⁴ are each independently preferably an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms. R ³ and R ⁴ are particularly preferably alkenyl groups having 2 to 5 carbon atoms.
E and G are preferably each independently a trans-1,4-cyclohexylene group.
Z ³ is preferably a single bond or —C≡C— for increasing Δn, and is preferably a single bond or —CH ₂ CH ₂ — for decreasing Δn.
[0028]
A more preferred form of the compound (2) is a compound represented by the general formulas (2a) to (2d).
Embedded image

(In each formula, R ³ and R ⁴ have the same meaning as in general formula (2).)
[0029]
When R ³ and R ⁴ in the compound (2) are alkenyl groups, the formulas (a) to (c)
Embedded image

An alkenyl group represented by the formula is particularly preferred.
[0030]
(Compound (3))
The content of the compound represented by the general formula (3) (hereinafter referred to as the compound (3)) is more preferably 20 to 40% by mass, and more preferably 20 to 30% by mass.
R ⁵ is preferably an alkyl group having 1 to ⁵ carbon atoms and an alkenyl group having 2 to 5 carbon atoms.
J, K, and L are preferably a trans-1,4-cyclohexylene group for decreasing Δn, and a 1,4-phenylene group for increasing Δn.
At least one of X ¹⁵ and X ¹⁶ is preferably F, and more preferably both are F. Y ⁶ is preferably F.
[0031]
A more preferred form of the compound (3) is a compound represented by the general formulas (3a) to (3d).
Embedded image

(In the formula, R ⁵ has the same meaning as R ⁵ in formula (3).)
When the compound (3) is used in an amount of 10% by mass or more, it is preferable to use one type from the group consisting of (3a) and (3b) and one type from the group consisting of (3c) and (3d) at the same time.
[0032]
(Other ingredients)
The liquid crystal composition of the present invention contains other nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal and optically active substance (chiral agent) in addition to the above compound (1), compound (2) and compound (3). Also good.
[0033]
In the liquid crystal composition of the present invention, when Δε is set to a specific value, the threshold voltage (Vth) measured with a twisted twist cell of 90 ° is lower by 10% to 30% than the conventional composition. be able to. Conversely, the value of Δε required to achieve a certain Vth can be reduced by 5% to 20%.
[0034]
In general, in order to drive a liquid crystal display element at a low voltage, it is necessary to increase Δε of the liquid crystal composition. However, if Δε is increased, the electric capacity of the cell into which the liquid crystal is injected increases, and a load is applied to the circuit for driving, resulting in poor response to the driving waveform. Further, since the voltage holding ratio deteriorates when Δε of the liquid crystal material is large, it is very useful to be able to drive with a small Δε.
[0035]
A liquid crystal satisfying the formula Vth ≦ −0.225 Δε + 3.12 using the liquid crystal composition of the present invention and the relationship between the threshold voltage (Vth) measured by a 90 ° twisted twist cell of 6 μm cell thickness and Δε of the liquid crystal composition. A display element can be manufactured.
[0036]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is explained in full detail, this invention is not limited to these Examples. “%” In the compositions of the following Examples and Comparative Examples means “% by mass”.
[0037]
In the examples, the measured characteristics are as follows.
Tni: Nematic phase-isotropic liquid phase transition temperature (° C)
T _{→ n} : Solid phase or smectic phase-nematic phase transition temperature (° C)
Vth: Voltage (V) required for 10% change in transmittance from the initial state when a TN-liquid crystal display element with a cell thickness of 6.0μm is constructed at 25 ° C
Δn: Refractive index anisotropy (25 ° C)
η: rotational viscosity at 25 ° C (mPa · s)
A 90 ° twisted TN liquid crystal display element was produced as follows.
[0038]
An alignment film “AL-1051” (manufactured by JSR) was applied on the opposing flat transparent electrode, and this alignment film was rubbed to produce a TN-LCD cell with a twist angle of 90 °. A liquid crystal composition with a chiral compound added thereto was injected to prepare a TN liquid crystal display device.
[0039]
The following abbreviations are used in compound descriptions.
-n Number: -C _n H _{2n + 1} (Alkyl side chain is a number.)
-On: -OC _n H _{2n + 1
-ndm :-( C n H 2n + 1} -CH = CH- (CH 2) m-1)
ndm-: C _n H _{2n + 1} -CH = CH- (CH ₂ ) _m-1-
-Od (m) n: -O ( C n H 2n + 1 -CH = CH- (CH 2) m-2)
d (m) nO-: C _n H _{2n + 1} -CH = CH- (CH ₂ ) _m-2 O-
Linking group
-VO-: -COO- -T-: -C≡C-
-2-: -CH ₂ CH ₂ -
Substituent
-CN: -C≡N -F: -F -OCF ₃ : -OCF ₃
[0040]
Ring [Chemical Formula 16]

[0041]
(Examples 1 and 2 and Comparative Examples 1 and 2)
Liquid crystal composition No. 1 (Example 1) of the present invention, Liquid crystal composition No. 2 (Example 2), Liquid crystal composition M1 (Comparative Example 1) and Liquid crystal composition M2 (Comparative Example 2) outside the present invention ) Was prepared. In addition, a 90 ° twisted TN-LCD using these liquid crystal compositions was fabricated. A chiral compound (cholesteric nonanate) was added to each liquid crystal composition in order to impart the necessary twist (pitch 100 μm). Table 1 shows composition ratios of these liquid crystal compositions and measured values of characteristics of TN-LCDs using the liquid crystal compositions. The liquid crystal compositions described in the following Examples 1 and 2 can be used for 4V driving TFT liquid crystal display devices.
[0042]
[Table 1]

[0043]
In the table, (Chemical Formula 1) represents Compound (1), (Chemical Formula 2) represents Compound (2), and (Chemical Formula 3) represents Compound (3).
[0044]
In No. 1 of Example 1, Tni is 2 ° C. higher than M1 of Comparative Example 1, and T _{→ n} is equivalent, the liquid crystal temperature range is slightly expanded, Δn is decreased from 0.093 to 0.080, and Vth is Despite being about 12% smaller from 1.73V to 1.50V, Δε was about 15% smaller from 6.7 to 5.7.
[0045]
No. 2 of Example 2 is substantially equivalent to Tni, T _{→ n} , Δn, Vth, η, compared to M2 of Comparative Example 2, but Δε is about 7.4 to 6.1. 18% smaller.
[0046]
(Examples 3-7 and Comparative Examples 3-5)
Liquid crystal composition No. 3 (Example 3), No. 4 (Example 4), No. 5 (Example 5), No. 6 (Example 6) and liquid crystal composition No. 7 (implementation) of the present invention Example 7), a liquid crystal composition M3 (Comparative Example 3), a liquid crystal composition M4 (Comparative Example 4) and a liquid crystal composition M5 (Comparative Example 5) other than the present invention were prepared. A chiral compound (cholesteric nonanate) was added to each liquid crystal composition in order to impart the necessary twist (pitch 100 μm). In addition, a 90 ° twisted TN-LCD using these liquid crystal compositions was fabricated. Table 2 shows the composition ratios of these liquid crystal compositions and measured values of the characteristics of TN-LCDs using the liquid crystal compositions. The five compositions described in Examples 3 to 7 below can be used for 5V-driven TFT liquid crystal display devices.
[0047]
[Table 2]

[0048]
In the liquid crystal composition No. 3 of Example 3, Δε can be slightly reduced from 4.7 to 4.6, although the Vth is about 10% smaller from 2.17 V to 1.95 V than the liquid crystal composition M4 of Comparative Example 4. The threshold voltage could be reduced without increasing Δε.
[0049]
The liquid crystal composition No. 4 of Example 4 had a Δth of about 25 from 6.4 to 4.8, although Vth was about 10% smaller from 1.81 V to 1.62 V than the liquid crystal composition M3 of Comparative Example 3. It was significantly reduced to%.
[0050]
In the liquid crystal composition No. 5 of Example 5, Δε was slightly smaller from 4.7 to 4.6, although the Vth was about 15% smaller from 2.17 V to 1.85 V than the liquid crystal composition M4 of Comparative Example 4. did it.
[0051]
In the liquid crystal composition No. 6 of Example 6, Δε was equal to 4.7, although the Vth was about 10% smaller than the liquid crystal composition M4 of Comparative Example 4 from 2.17 V to 1.95 V.
[0052]
The liquid crystal composition No. 7 of Example 7 was about 23% from 5.3 to 4.1 even though Vth was slightly smaller from 1.98 V to 1.95 V than the liquid crystal composition M5 of Comparative Example 5. It was possible to make it much smaller.
[0053]
Vth and Δε of the liquid crystal compositions of Examples 1 to 7 and Comparative Examples 1 to 5 are plotted in FIG. It is clear that the example shows a lower Vth when compared with the same Δε as compared with the comparative example. From the plots of the examples, it can be seen that the composition of the present invention can produce a liquid crystal display element satisfying the formula Vth ≦ −0.225 Δε + 3.12.
[0054]
(Examples 8, 10-13 and Comparative Examples 6-11)
Liquid crystal composition No. 8 (Example 8), No. 10 (Example 10), No. 11 (Example 11), Liquid crystal composition No. 12 (Example 12), Liquid crystal composition No. Liquid crystal composition M6 (Comparative Example 6), liquid crystal composition M7 (Comparative Example 7), liquid crystal composition M8 (Comparative Example 8), liquid crystal composition M9 (Comparative Example 9) A liquid crystal composition M10 (Comparative Example 10) and a liquid crystal composition M11 (Comparative Example 11) were prepared. To each liquid crystal composition, a chiral compound (cholesteric nonanate) was added in the same manner as in Examples 1 and 2 in order to give the necessary twist (pitch 100 μm). In addition, a 90 ° twisted TN-LCD using these liquid crystal compositions was fabricated. Tables 3 and 4 show composition ratios of these liquid crystal compositions and measured values of characteristics of TN-LCDs using the liquid crystal compositions.
[0055]
[Table 3]

In the table, (Chemical Formula 1) represents Compound (1), (Chemical Formula 2) represents Compound (2), and (Chemical Formula 3) represents Compound (3).
[0056]
[Table 4]

In the table, (Chemical Formula 1) represents Compound (1), (Chemical Formula 2) represents Compound (2), and (Chemical Formula 3) represents Compound (3).
[0057]
[Table 5]

In the table, (Chemical Formula 1) represents Compound (1), (Chemical Formula 2) represents Compound (2), and (Chemical Formula 3) represents Compound (3).
[0058]
Vth and Δε of the liquid crystal compositions of Examples 8 to 14 and Comparative Examples 6 to 11 are plotted in FIG. 2 together with Examples 1 to 7 and Comparative Examples 1 to 5. It is clear that the example shows a lower Vth when compared with the same Δε as compared with the comparative example. From the plots of the examples, it can be seen that the composition of the present invention can produce a liquid crystal display element satisfying the formula Vth ≦ −0.225 Δε + 3.12.
[0059]
【The invention's effect】
The liquid crystal composition of the present invention can make the dielectric anisotropy necessary to achieve a desired driving voltage smaller than usual.
[Brief description of the drawings]
FIG. 1 is a graph plotting Vth of Examples 1 to 7 and Comparative Examples 1 to 5 and Δε of liquid crystal compositions. FIG. 2 is a graph of Vth of Examples 1 to 14 and Comparative Examples 1 to 11 and Δε of liquid crystal compositions. Plotting

Claims (5)

General formula (1-1) and general formula (1-2)

(In each formula, R ¹ and R ² each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms; represents a group selected from (a) to (d),

B is a trans-1,4-cyclohexylene group, 1,4-phenylene group, or a 1,4-phenylene group having one or two fluorine atoms, and D is selected from (e) to (h) Represents a group

Z ¹ and Z ² each independently represent a single bond or —CH ₂ CH ₂ —,
X ^{1 to} X ¹⁴ each independently represents F, Cl or H.
Y ^{1 to} Y ⁵ each independently represent F, Cl, CF ₃ , OCF ₃ , OCHF ₂ or OCH ₂ F. 20 to 60% by mass of a compound selected from the group consisting of:
General formula (2)

(Wherein R ³ and R ⁴ each independently represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms, and E and G Each independently represents a trans-1,4-cyclohexylene group or a 1,4-phenylene group, and Z ³ represents a single bond, —CH ₂ CH ₂ — or —C≡C—. Containing 10-40% by mass of
General formula (3a)-(3d)

(Wherein R ⁵ represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms). Containing one or more compounds selected from the group consisting of (3a) and (3b), and one or more compounds selected from the group consisting of general formulas (3c) and (3d), (3d) content is 20-50% by mass, nematic phase-isotropic liquid phase transition temperature is 75 ° C-120 ° C, dielectric anisotropy is 3-8, refractive index anisotropic A liquid crystal composition having a property of 0.075 to 0.160. Compounds represented by the general formula (1-1) are represented by the general formulas (1-1a) to (I-1g)

(In each formula, R ¹ represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms). Compounds represented by the general formula (1-2) are represented by the general formulas (1-2a) to (1-2g)

(Wherein R ² represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or an alkoxyl group having 1 to 10 carbon atoms). Item 2. A liquid crystal composition according to item 1. Compounds represented by the general formula (2) are represented by the general formulas (2a) to (2d)

^3. The liquid crystal composition according to claim 1, wherein R ³ and R ⁴ have the same meanings as in general formula (2).   2. The liquid crystal composition according to claim 1, comprising 25 to 60% by mass of the compound represented by the general formula (1-1).   5. The dielectric constant anisotropy (Δε) of the liquid crystal composition and the threshold voltage (Vth) measured with a twist twist cell of 90 ° satisfy the formula Vth ≦ −0.225 Δε + 3.12. The liquid crystal composition described in 1.

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