JP3598614B2 - Liquid crystal device and method of manufacturing the same - Google Patents

Description

【００３２】
で表わされる分岐率で判断することができる。
【００３３】
このとき、（メタ）アクリレート誘導体分子内の最も長いアルキル直鎖部分を主鎖とし、その主鎖から枝分かれしたアルキル基をすべてアルキル分岐鎖とする。
【００３４】
本発明で使用する分岐率は、（メタ）アクリレート酸とエステル結合したアルキル基に対するアルキル分岐鎖基の割合を表わし、分岐率が高いほど分岐鎖分子の割合が高く、よりバルキーな構造を有する。
【００３５】
分岐率の値は、０．３〜０．７の範囲が好ましい。分岐率の値が０．３よりも小さい材料を用いた場合、得られた液晶デバイスの低温メモリー現象抑制効果が小さくなる傾向にあるので好ましくなく、分岐率の値が０．７よりも大きい材料を用いた場合、主鎖のアルキル鎖数が小さくなるために、得られた液晶デバイスの低電圧効果が小さくなる傾向にあるので好ましくない。
【００３６】
本発明で使用する単官能型アルキル（メタ）アクリレート誘導体の分岐アルキル基の炭素原子数が１４よりも小さい場合、蒸気圧が低いために、真空注入時に単官能アルキル（メタ）アクリレート誘導体が揮発し易くなる傾向にあり、また、得られる液晶デバイスの低電圧効果が小さいので、好ましくない。また、本発明で使用する単官能型アルキル（メタ）アクリレート誘導体の分岐アルキル基の炭素原子数が３０よりも大きい場合、液晶材料との溶解性が低下し、重合時の相分離が不均一に進行するため、良好な透明性固体物質の３次元ネットワーク構造あるいは網目の大きさを得ることができないので、好ましくない。
【００３７】
そのため、本発明で使用する単官能型アルキル分岐鎖を有するアルキル（メタ）アクリレート誘導体は、請求項１で規定したように、分岐アルキル基の炭素原子数は１４〜３０の範囲が好ましい。
【００３８】
本発明で使用する分岐アルキル基の炭素原子数が１４〜３０の範囲にある分岐アルキル基から成る単官能型アルキル（メタ）アクリレート誘導体は、低極性であり、液晶デバイスの駆動電圧を低下させる効果があり、また、高抵抗であるため、電圧保持率を向上させることができる。さらに、アルキル基の炭素原子数が１４以上で分子量が大きく、蒸気圧が低く、液晶デバイスの製造方法で一般的に用いられている真空注入法の際に生じる（メタ）アクリレート誘導体の揮発の問題も少ない。
【００３９】
本発明で使用する分岐アルキル基の炭素原子数が１４〜３０の範囲にある分岐アルキル基から成る単官能型アルキル（メタ）アクリレート誘導体の分岐アルキル基主鎖部分の長さは、液晶デバイスの低電圧駆動効果を高めるため、炭素原子数７〜１８であることが好ましく、７〜１４の範囲が特に好ましい。
【００４０】
本発明で使用する分岐アルキル基の炭素原子数が１４〜３０の範囲にある分岐アルキル基から成る単官能型アルキル（メタ）アクリレート誘導体は、低温メモリー現象を抑制する効果は大きいが、低電圧駆動化させる効果を十分に得るために、その使用割合は、重合性組成物中の１０〜９５％の範囲であることが好ましい。
【００４１】
本発明で使用する分岐アルキル基の炭素原子数が１４〜３０の範囲にある分岐アルキル基から成る単官能型アルキル（メタ）アクリレート誘導体としては、例えば、イソミリスチル（メタ）アクリレート、イソパルミチル（メタ）アクリレート、イソステアリル（メタ）アクリレート、イソイコシル（メタ）アクリレート、イソドコシル（メタ）アクリレート、イソテトラコシル（メタ）アクリレート、イソヘキサコシル（メタ）アクリレート、イソオクタコシル（メタ）アクリレート、トリアコンチル（メタ）アクリレート、トリアコンチル（メタ）アクリレート等が挙げられる。これらの中でも、分岐率が０．３〜０．７の範囲にある単官能型分岐アルキル（メタ）アクリレート誘導体が好ましい。
【００４２】
分岐アルキル基の炭素原子数が１４〜３０の範囲にあって、分岐率が０．３〜０．７の範囲にある分岐アルキル基から成る単官能型アルキル（メタ）アクリレート誘導体としては、例えば、１−ヘキシルヘプチルアクリレート（分岐率＝４６．４％）、１，１−ジエチルオクチルアクリレート（分岐率＝３４．３％）、２−（３−メチルブチル）−７−メチルオクチルアクリレート（分岐率＝４３．７％）、２−（１−メチルブチル）−５−メチルオクチルアクリレート（分岐率＝４３．７％）、２−（１−メチル−３，３−ジメチルブチル）−５−メチル−７，７−ジメチルオクチルアクリレート（分岐率＝５６．９％）、２−ヘキシルデシルアクリレート（分岐率＝３７．８％）、２−オクチルデシルアクリレート（分岐率＝４４．７％）、２−オクチルドデシルアクリレート（分岐率＝４０．２％）、２−ドデシルドデシルアクリレート（分岐率＝５０．１％）、２−ウンデシルトリデシルアクリレート（分岐率＝５４．３％）、２−ウンデシルペンタデシルアクリレート（分岐率＝４２．５％）等が挙げられる。
【００４３】
本発明で使用する分岐アルキル基の炭素原子数が１４〜３０の範囲にある分岐アルキル基から成る単官能型アルキル（メタ）アクリレート誘導体は、例えば、（メタ）アクリル酸又は（メタ）アクリル酸クロリドを用いて、分岐アルカノールを（メタ）アクリル化することによって容易に製造することができる。
【００４４】
製造原料となる分岐アルキルアルコールの市販品としては、汎用の分岐アルカノールに加え、例えば、東京化成社製の「７−エチル−２−メチルウンデカノール」（分岐率＝２２．３％）、日産化学社製の「ファインオキソコール１４０」［２−（３−メチルブチル）−７−メチルオクタノール（分岐率＝４３．７％）及び２−（１−メチルブチル）−５−メチルオクタノール（分岐率＝４３．７％）］、「ファインオキソコール１６００」［２−ヘキシルデカノール（分岐率＝３７．８％）］、「ファインオキソコール１８０」、「ファインオキソコール１８００」［２−（１−メチル−３，３−ジメチルブチル）−５−メチル−７，７−ジメチルオクタノール（分岐率＝５６．９％）］、花王社製「カルコール２００ＧＤ」［２−オクチルドデカノール（分岐率＝４０．２％）］、「カルコール１６０ＧＤ」［（２−ヘキシルデカノール（分岐率＝３７．８％）］等のさまざまの分岐鎖数を有するものが挙げられる。
【００４５】
本発明で使用する分岐アルキル基の炭素原子数が１４〜３０の範囲にある分岐アルキル基から成る単官能型アルキル（メタ）アクリレート誘導体の市販品としては、例えば、共栄社化学社製の「ＩＭ−Ａ」［２−（３−メチルブチル）−７−メチルオクチルアクリレート（分岐率＝４３．７％）及び／又は２−（１−メチルブチル）−５−メチルオクチルアクリレート（分岐率＝４３．７％）］、「ＩＳ−Ａ」［２−（１−メチル−３，３−ジメチルブチル）−５−メチル−７，７−ジメチルオクチルアクリレート（分岐率＝５６．９％）］等を挙げることができる。
【００４６】
任意成分として使用することができるその他の重合体形成性モノマーとしては、例えば、スチレン、クロロスチレン、α−メチルスチレン、ジビニルベンゼン；置換基として、メチル、エチル、プロピル、ブチル、アミル、２−エチルヘキシル、シクロヘキシル、ベンジル、メトキシエチル、ブトキシエチル、フェノキシエチル、アルリル、メタリル、グリシジル、２−ヒドロキシエチル、２−ヒドロキシプロピル、３−クロロ−２−ヒドロキシプロピル、ジメチルアミノエチル、ジエチルアミノエチルの如き基を有するアクリレート、メタクリレート又はフマレート；酢酸ビニル、酪酸ビニル又は安息香酸ビニル、アクリロニトリル、セチルビニルエーテル、リモネン、シクロヘキセン、ジアリルフタレート、２−、３−又は４−ビニルピリジン、アクリル酸、メタクリル酸、アクリルアミド、メタクリルアミド、Ｎ−ヒドロキシメチルアクリルアミド又はＮ−ヒドロキシエチルメタクリルアミド及びそれらのアルキルエーテル化合物；２−ヒドロキシエチル（メタ）アクリレート１モルとフェニルイソシアネート若しくはｎ−ブチルイソシアネート１モルとの反応生成物等を挙げることができる。
【００４７】
重合開始剤としては、例えば、２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン（メルク社製「ダロキュア１１７３」）、１−ヒドロキシシクロヘキシルフェニルケトン（チバ・ガイギー社製「イルガキュア１８４」）、１−（４−イソプロピルフェニル）−２−ヒドロキシ−２−メチルプロパン−１−オン（メルク社製「ダロキュア１１１６」）、ベンジルジメチルケタール（チバ・ガイギー社製「イルガキュア６５１」）、２−メチル−１−〔４−（メチルチオ）フェニル〕−２−モルホリノプロパノン−１（チバ・ガイギー社製「イルガキュア９０７」）、２，４−ジエチルチオキサントン（日本化薬社製「カヤキュアＤＥＴＸ」）とｐ−ジメチルアミノ安息香酸エチル（日本化薬社製「カヤキュアＥＰＡ」）との混合物、イソプロピルチオキサントン（ワードプレキンソツプ社製「カンタキュアーＩＴＸ」）とｐ−ジメチルアミノ安息香酸エチルとの混合物、アシルホスフィンオキシド（ＢＡＳＦ社製「ルシリンＴＰＯ」）等が挙げられる。
【００４８】
光重合開始剤の使用割合は、重合性組成物に対して、０．１〜１０％の範囲であることが好ましい。
【００４９】
本発明の液晶デバイスは、その調光層の厚さによって、コントラスト、駆動電圧が変化する。調光層の厚さが、薄い場合は駆動電圧が非常に低くなり、汎用の回路の使用で駆動ができ、低電力消費のデバイスとなる。調光層の厚さが、厚い場合は電圧無印加時の調光層の散乱性が高くなり、白くて明るいデバイスとなる。
【００５０】
調光層の厚さは、各々の用途によって自由に選択できるが、５〜１００μｍの範囲が好ましく、８〜６０μｍの範囲が特に好ましい。調光層の厚さが５μｍよりも薄い場合、コントラストが低下する傾向にあるので、好ましくなく、１００μｍよりも厚い場合、従来のものと比べ充分駆動電圧が低いものの、駆動電圧の上昇、駆動時の透明性の低下を招く傾向にあるので、好ましくない。特に、直視形用途として反射率を高めるためには、調光層の厚さを厚めに設定することで、３０％以上の高い反射率を有し、かつ、従来の高反射率の液晶デバイスより低電圧で駆動することができる。その際の調光層の厚さは、２５〜６０μｍの範囲が好ましい。
【００５１】
本発明の液晶デバイスは、調光層中に占める液晶材料の比率が高く、特に、液晶材料が連続層を形成している場合には、駆動電圧が低く、電圧印加時の透明性が高い。
【００５２】
【実施例】
以下、実施例及び比較例を用いて本発明を更に詳細に説明するが、本発明はこれらの実施例に限定されるものではない。なお、以下、実施例において「％」は「重量％」を表わし、評価特性の各々は以下の記号及び内容を意味する。
Ｔ_０ ：白濁度 ；印加電圧０Ｖの時の光透過率（％）
Ｔ_１００ ：透明度 ；印加電圧を増加させていき光透過率がほとんど増加しなくなった時の光透過率（％）
Ｖ_１０ ：しきい値；Ｔ_０ を０％、Ｔ_１００ を１００％としたとき光透過率が１０％となる印加電圧（Ｖ_ｒｍｓ ）
Ｖ_９０ ：飽和電圧；同上光透過率が９０％となる印加電圧（Ｖ_ｒｍｓ ）
ＣＲ ：コントラスト＝Ｔ_１００ ／Ｔ_０
Ｒ ：反射率 ；標準白色板の反射強度を１００％とした時の反射強度の割合（％）
【００５３】
又、紫外線の照度は、ウシオ電機社製の受光器ＵＶＤ−３６５ＰＤ付きユニメータＵＩＴ−１０１を用いて測定した。
【００５４】
（実施例１）
＜液晶材料＞
下記液晶組成物（Ａ） ７８．０％
＜重合性組成物＞
「カヤラッド（ＫＡＹＡＲＡＤ ）−ＨＸ−６２０」 １０．８％
（日本化薬社製、カプロラクトン変性ヒドロキシピバリン酸エステルネオ
ペンチルグリコールジアクリレート）
「ＩＭ−Ａ」 １０．８％
［共栄社化学社製の式
【００５５】
【化１】

【００５６】
で表わされる炭素原子数１４の分岐アルキル基を有する２−（３−メチ
ルブチル）−７−メチルオクチルアクリレート（分岐率＝４３．７％）
及び／又は２−（１−メチルブチル）−５−メチルオクチルアクリレー
ト（分岐率＝４３．７％）］
＜重合開始剤＞
「イルガキュア６５１」 ０．４％
（チバ・ガイギー社製、ベンジルジメチルケタール）
からなる調光層形成材料を、１１．０μｍのガラスファイバー製スペーサーが塗布された２枚のＩＴＯ電極ガラス基板に挟み込み、基板全体を調光層形成材料を均一な溶液状態に保ちながら、 ４０ｍＷ／ｃｍ^２の紫外線を６０秒間照射して、重合性組成物を硬化させて、液晶材料と透明性固体物質から成る厚さが１１．３μｍの調光層を有する液晶デバイスを得た。
【００５７】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００５８】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表１に示した。
【００５９】
液晶組成物（Ａ）の組成：
【００６０】
【化２】

【００６１】

【００６２】
（比較例１）
実施例１において、「ＩＭ−Ａ」に代えて、ｎ−ミリスチルアクリレート（炭素原子数１４の直鎖アルキル基からなる直鎖アルキルアクリレート、分岐率＝０％）を用いた以外は、実施例１と同様にして、液晶材料と透明性固体物質から成る厚さが１１．２μｍの調光層を有する液晶デバイスを得た。
【００６３】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００６４】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表１に示した。
【００６５】
（比較例２）
実施例１において、「ＩＭ−Ａ」に代えて、２−メチルウンデシルアクリレート（炭素原子数１２の分岐アルキル基から成る分岐アルキルアクリレート、分岐率＝８．９％）を用いた以外は、実施例１と同様にして、液晶材料と透明性固体物質から成る厚さが１１．２μｍの調光層を有する液晶デバイスを得た。
【００６６】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００６７】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表１に示した。
【００６８】
【表１】

【００６９】
表１に示した結果から、実施例１で得た液晶デバイスは、低温でも支障なく駆動し得ることが理解できる。一方、比較例１で得た液晶デバイスは、２５℃では、実施例１で得た液晶デバイスとほぼ同等の性能を示すが、−２０℃では、電圧印加後の透明状態から電圧無印加で散乱状態に戻らなくなり、実駆動できないことが理解できる。また、比較例２で得た液晶デバイスは、２５℃では、実施例１で得た液晶デバイスとほぼ同等の性能を示すが、−２０℃では、Ｖ_１０及びＶ_９０の値がそれぞれ９．８Ｖ及び１８．０Ｖと高く、駆動電圧の温度依存性が大きいという問題点を有することが理解できる。
【００７０】
（実施例２）
＜液晶材料＞
前記液晶組成物（Ａ） ７８．０％
＜重合性組成物＞
「カヤラッド（ＫＡＹＡＲＡＤ ）−ＨＸ−２２０」 １０．８％
２−ヘキシルデシルアクリレート １０．８％
（東亜合成化学社製の炭素原子数１６の分岐アルキル基を有する分岐アル
キルアクリレート、分岐率＝３７．８％）
＜重合開始剤＞
「イルガキュア６５１」 ０．４％
からなる調光層形成材料を、１１．０μｍのガラスファイバー製スペーサーが塗布された２枚のＩＴＯ電極ガラス基板に挟み込み、基板全体を調光層形成材料を均一な溶液状態に保ちながら、 ４０ｍＷ／ｃｍ^２の紫外線を６０秒照射して、重合性組成物を硬化させて、液晶材料と透明性固体物質から成る厚さが１１．２μｍの調光層を有する液晶デバイスを得た。
【００７１】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００７２】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表２に示した。
【００７３】
【表２】

【００７４】
表２に示した結果から、実施例２で得た液晶デバイスは、低温でも支障なく駆動し得ることが理解できる。
【００７５】
（実施例３）
＜液晶材料＞
前記液晶組成物（Ａ） ７８．０％
＜重合性組成物＞
「カヤラッド（ＫＡＹＡＲＡＤ ）−ＨＸ−２２０」 １０．８％
（日本化薬社製、カプロラクトン変性ヒドロキシピバリン酸エステルネオ
ペンチルグリコールジアクリレート）
「ＩＳ−Ａ」 １０．８％
（共栄社化学社製の式
【００７６】
【化３】

【００７７】
で表わされる炭素原子数１８の分岐アルキル基を有する２−（１−メチ
ル−３，３−ジメチルブチル）−５−メチル−７，７−ジメチルオクチ
ルアクリレート、分岐率＝５６．９％）
＜重合開始剤＞
「イルガキュア６５１」 ０．４％
からなる調光層形成材料を、１２．０μｍのガラスファイバー製スペーサーが塗布された２枚のＩＴＯ電極ガラス基板に挟み込み、基板全体を調光層形成材料を均一な溶液状態に保ちながら、 ４０ｍＷ／ｃｍ^２の紫外線を６０秒照射して、重合性組成物を硬化させて、液晶材料と透明性固体物質から成る厚さが１２．３μｍの調光層を有する液晶デバイスを得た。
【００７８】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００７９】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表３に示した。
【００８０】
【表３】

【００８１】
表３に示した結果から、実施例３で得た液晶デバイスは、低温でも支障なく駆動し得ることが理解できる。
【００８２】
（実施例４）
＜液晶材料＞
前記液晶組成物（Ａ） ７８．０％
＜重合性組成物＞
「カヤラッド（ＫＡＹＡＲＡＤ ）−ＨＸ−２２０」 １２．９６％
式
【００８３】
【化４】

【００８４】
で表わされるイソテトラコシルモノアクリレート ８．６４％
（東亜合成社製の炭素原子数２４の分岐アルキル基を有する分岐アルキル
アクリレート、分岐率＝４６．０％）
＜重合開始剤＞
「イルガキュア６５１」 ０．４％
からなる調光層形成材料を、１１．０μｍのガラスファイバー製スペーサーが塗布された２枚のＩＴＯ電極ガラス基板に挟み込み、基板全体を調光層形成材料を均一な溶液状態に保ちながら、 ４０ｍＷ／ｃｍ^２の紫外線を６０秒照射して、重合性組成物を硬化させて、液晶材料と透明性固体物質から成る厚さが１１．３μｍの調光層を有する液晶デバイスを得た。
【００８５】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００８６】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表４に示した。
【００８７】
（実施例５）
実施例４において、１１．０μｍのガラスファイバー製スペーサーに代えて、５０．０μｍのガラスファイバー製スペーサーを用いた以外は、実施例４と同様にして液晶デバイスを得た。
【００８８】
このようにして得た液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表４に示した。
【００８９】
【表４】

【００９０】
表４に示した結果から、実施例４で得た液晶デバイスは、低温でも支障なく駆動し得ることが理解できる。また、実施例５で得た液晶デバイスは、反射率が３０％以上と白くて明るく、特に直視形用途に優れた表示特性を示すものであり、しかも、低温でも支障なく駆動し得ることが理解できる。
【００９１】
（実施例６）
実施例２において、２−ヘキシルデシルアクリレートに代えて、１−トリドデシルテトラデシルアクリレート（炭素原子数２７の分岐アルキル基を有する分岐アルキルアクリレート、分岐率＝４８．３％）を用いた以外は、実施例２と同様にして、液晶材料と透明性固体物質から成る厚さが１１．３μｍの調光層を有する液晶デバイスを得た。
【００９２】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００９３】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表５に示した。
【００９４】
【表５】

【００９５】
表５に示した結果から、実施例６で得た液晶デバイスは、低温でも支障なく駆動し得ることが理解できる。
【００９６】
（比較例３）
実施例２において、２−ヘキシルデシルアクリレートに代えて、１−ペンタデシルヘキシルアクリレート（炭素原子数３１の分岐アルキル基を有する分岐アルキルアクリレート、分岐率＝４８．３％）を用いた以外は、実施例２と同様にして、液晶材料と透明性固体物質から成る調光層を有する液晶デバイスを作成しようとしたが、使用した分岐アルキルアクリレートの分岐アルキル基の分子量が大きいため、調光層形成材料中の液晶材料と重合性組成物の相溶性が低下し、そのため、重合性組成物を硬化させた時に、均一な三次元網目状の透明性固体物質から成る調光層を有する液晶デバイスを得ることができなかった。
【００９７】
（実施例７）
＜液晶材料＞
下記液晶組成物（Ｂ） ７８．０％
＜重合性組成物＞
「カヤラッド（ＫＡＹＡＲＡＤ ）−ＨＸ−２２０」 １０．８％
２−オクチルデシルアクリレート（炭素原子数１８の分岐アルキル基を有
する分岐アルキルアクリレート、分岐率＝４４．７％）１０．８％
＜重合開始剤＞
「イルガキュア６５１」 ０．４％
からなる調光層形成材料を、１１．０μｍのガラスファイバー製スペーサーが塗布された２枚のＩＴＯ電極ガラス基板に挟み込み、基板全体を調光層形成材料を均一な溶液状態に保ちながら、 ４０ｍＷ／ｃｍ^２の紫外線を６０秒照射して、重合性組成物を硬化させて、液晶材料と透明性固体物質から成る厚さが１１．２μｍの調光層を有する液晶デバイスを得た。
【００９８】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【００９９】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表６に示した。
【０１００】
液晶組成物（Ｂ）の組成：
【化５】

【０１０１】

【０１０２】
【表６】

【０１０３】
表６に示した結果から、実施例７で得た液晶デバイスは、低温でも支障なく駆動し得ることが理解できる。
【０１０４】
（実施例８）
実施例７において、２−オクチルデシルアクリレートに代えて、式
【０１０５】
【化６】

【０１０６】
で表わされるイソイコシルモノアクリレート（東亜合成社製の炭素原子数２０の分岐アルキル基を有する分岐アルキルアクリレート、分岐率＝４０．２％）１０．８％を用いた以外は、実施例７と同様にして、液晶材料と透明性固体物質から成る厚さが１１．２μｍの調光層を有する液晶デバイスを得た。
【０１０７】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【０１０８】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表７に示した。
【０１０９】
（実施例９）
実施例８において、１１．０μｍのガラスファイバー製スペーサーに代えて、３０．０μｍのガラスファイバー製スペーサーを用いた以外は、実施例８と同様にして液晶デバイスを得た。
【０１１０】
このようにして得た液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表７に示した。
【０１１１】
（比較例４）
実施例７において、２−オクチルデシルアクリレートに代えて、ｎ−イコシルモノアクリレート（炭素原子数２０の直鎖アルキル基から成る直鎖アルキルアクリレート）１０．８％を用いた以外は、実施例７と同様にして、液晶材料と透明性固体物質から成る厚さが１１．２μｍの調光層を有する液晶デバイスを得た。
【０１１２】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【０１１３】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表７に示した。
【０１１４】
【表７】

【０１１５】
表７に示した結果から、実施例８で得た液晶デバイスは、低温でも支障なく駆動し得ることが理解できる。また、実施例９で得た液晶デバイスは、比較例４で得た液晶デバイスの駆動電圧と比較して、充分低いうえ、反射率が３０％以上と白くて明るく、特に直視形用途に優れた表示特性を示すものであり、しかも、低温でも支障なく駆動し得ることが理解できる。一方、比較例４で得た液晶デバイスは、２５℃では、実施例８で得た液晶デバイスとほぼ同等の性能を示すが、−２０℃では、電圧印加後の透明状態から電圧無印加で散乱状態に戻らなくなり、実駆動できないことが理解できる。
【０１１６】
（比較例１０）実施例７において、２−オクチルデシルアクリレートに代えて、式
【０１１７】
【化７】

【０１１８】
で表わされる１−メチル−１−トリデシルアクリレート（東京化成社製の炭素原子数１４の分岐アルキル基から成る分岐アルキルアクリレート、分岐率＝７．６％）を用いた以外は、実施例７と同様にして、液晶材料と透明性固体物質から成る厚さが１１．３μｍの調光層を有する液晶デバイスを得た。
【０１１９】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【０１２０】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表８に示した。
【０１２１】
（比較例５）
実施例７において、２−オクチルデシルアクリレートに代えて、式
【０１２２】
【化８】

【０１２３】
で表わされる２−エチルヘキシルアクリレート（東京化成社製の炭素原子数８の分岐アルキル基から成る分岐アルキルアクリレート、分岐率＝２５．７％）を用いた以外は、実施例７と同様にして、液晶材料と透明性固体物質から成る厚さが１１．２μｍの調光層を有する液晶デバイスを得た。
【０１２４】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【０１２５】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表８に示した。
【０１２６】
（比較例６）
実施例７において、２−オクチルデシルアクリレートに代えて、２−メチルウンデシルアクリレート（炭素原子数１２の分岐アルキル基から成る分岐アルキルアクリレート、分岐率＝８．９％）を用いた以外は、実施例７と同様にして、液晶材料と透明性固体物質から成る厚さが１１．３μｍの調光層を有する液晶デバイスを得た。
【０１２７】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【０１２８】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表８に示した。
【０１２９】
【表８】

【０１３０】
表８に示した結果から、実施例１０で得た液晶デバイスは、２５℃では、実施例１で得た液晶デバイスとほぼ同等の性能を示すが、−２０℃では、実駆動可能ではあるが、分岐率の低いアクリレート誘導体（７．６％）を使用しているため、低温メモリー現象を完全に抑制することできず、コントラストの低下が認められる。しかしながら、−２０℃におけるＴ_０ が１０％程度であるため、実用化できないレベルではない。一方、比較例５で得た液晶デバイスは、−２０℃におけるコントラストは十分であるが、炭素原子数が８と小さく低電圧効果の低いアルキルアクリレートを使用しているため、駆動電圧が１３．７Ｖ_ｒｍｓ と高く、満足できるものではないことが理解できる。更に、比較例６で得た液晶デバイスは、２５℃におけるＶ_９０の値が２０Ｖに近いので満足できるものではないことが理解できる。
【０１３１】
（比較例７）
＜液晶材料＞
前記液晶組成物（Ｂ） ７８．０％
＜重合性組成物＞
「カヤラッド（ＫＡＹＡＲＡＤ ）−ＨＸ−２２０」 ２１．６％
＜重合開始剤＞
「イルガキュア６５１」 ０．４％
からなる調光層形成材料を、５０．０μｍのガラスファイバー製スペーサーが塗布された２枚のＩＴＯ電極ガラス基板に挟み込み、基板全体を調光層形成材料を均一な溶液状態に保ちながら、 ４０ｍＷ／ｃｍ^２の紫外線を６０秒照射して、重合性組成物を硬化させて、液晶材料と透明性固体物質から成る厚さが５０．２μｍの調光層を有する液晶デバイスを得た。
【０１３２】
このようにして得た液晶デバイスの調光層を電子顕微鏡を用いて観察した結果、三次元網目状の透明性固体物質を確認することができた。
【０１３３】
また、この液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表９に示した。
【０１３４】
（比較例８）
比較例４において、１１．０μｍのガラスファイバー製スペーサーに代えて、５０．０μｍのガラスファイバー製スペーサーを用いた以外は、比較例４と同様にして液晶デバイスを得た。
【０１３５】
このようにして得た液晶デバイスの２５℃及び−２０℃における印加電圧と光透過率の関係を測定し、その結果を下記表９に示した。
【０１３６】
【表９】

【０１３７】
＊）比較例７で得た液晶デバイスは、 ５０Ｖ_ｒｍｓまで電圧を印加しても透過率が十分に飽和しなかったため、表９における比較例７のＴ_１００の欄には、 印加電圧５０Ｖ_ｒｍｓの時の光透過率を掲げた。 同様に、表９における比較例７のＣＲの値は、 印加電圧０の光透過率と印加電圧５０Ｖ_ｒｍｓの光透過率から算出したコントラストの値を掲げた。 また、表９における比較例７のＶ_１０の値は、Ｔ_１００の値が測定不能であるから、測定できなかった。
【０１３８】
表９に示した結果から、比較例７で得た液晶デバイスの反射率は３０％以上と高いものであったが、 印加電圧を５０Ｖ_ｒｍｓにしても透過率が飽和せず、駆動電圧が極めて高いものであることが理解できる。比較例８で得た液晶デバイスは、２５℃では、実施例９で得た液晶デバイスとほぼ同等の性能を示すが、−２０℃では、電圧印加後の透明状態から電圧無印加で散乱状態に戻らなくなり、実駆動できなかった。
【０１３９】
（比較例９）
実施例７において、２−オクチルデシルアクリレートに代えて、１−ヘキサデシルノナデシルアクリレート（炭素原子数３５の分岐アルキル基から成る分岐アルキルアクリレート、分岐率＝４５．８％）を用いた以外は、実施例７と同様にして、液晶材料と透明性固体物質から成る調光層を有する液晶デバイスを作成しようとしたが、使用した分岐アルキルアクリレートの分岐アルキル基の分子量が大きいため、調光層形成材料中の液晶材料と重合性組成物の相溶性が低下し、そのため、重合性組成物を硬化させた時に、均一な三次元網目状の透明性固体物質から成る調光層を有する液晶デバイスを得ることができなかった。
【０１４０】
【発明の効果】
本発明の液晶デバイスは、偏光板が不要で明るい表示画面のものであり、大面積薄膜型のものであって、 低電圧駆動が可能であり、又、明るく高反射率の表示が可能であり、更に、−２０℃もの低温温度域においても駆動が可能となるので、実用性が向上する。
【０１４１】
従って、従来のこの種の調光用液晶デバイスのみならず、大画面で薄型の、より高度な表示品位を有する液晶デバイスとして極めて有用である。[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light-scattering type liquid crystal display device capable of forming a large area with a bright display screen of a scattering type and a method for manufacturing the same, and more particularly, to blocking, releasing and lighting of light, or scattering, limiting transmission and blocking of illumination light. , Which can be electrically or thermally controlled for transmission, used as a screen to block the view of a building window or show window, or as a curtain for daylighting control, and displays characters and figures, and electrically By switching the display, a light scattering type liquid crystal used as a display body such as an advertising board, a guide board, a decorative display board, a high information display body such as a display of OA equipment or a projection type display device such as a projection. The present invention relates to a display element and a method for manufacturing the same.
[0002]
[Prior art]
As a large and inexpensive liquid crystal device that does not require a polarizing plate or alignment treatment, is bright and has good contrast, Japanese Patent Publication No. 58-501631 and U.S. Pat. There has been proposed a liquid crystal device having a dimming layer formed by dispersing liquid crystal droplets into a film and polymerizing the polymer. Here, gelatin, gum arabic, polyvinyl alcohol and the like have been proposed as encapsulating substances.
[0003]
In the technology disclosed in the above specification, the liquid crystal molecules encapsulated with polyvinyl alcohol or the like, if they have a positive dielectric anisotropy in a thin layer, the liquid crystal in the presence of an electric field The molecules are arranged in the direction of the electric field and the refractive index n of the liquid crystal_o  And the refractive index n of the polymer_p  When are equal, transparency is exhibited. When the electric field is removed, the liquid crystal molecules return to a random arrangement, and the refractive index of the liquid crystal droplet becomes n._oBecause of the shift, the liquid crystal droplets scatter light at the interface, and the thin body becomes cloudy. In addition to the above-mentioned technologies, some techniques for forming a thin film of a polymer in which encapsulated liquid crystals are dispersed and encapsulated are known. JP-A-62-2231 discloses a liquid crystal dispersed in a special ultraviolet-curable polymer, and JP-A-63-271233 discloses a photocurable vinyl compound and a liquid crystal. A technique is disclosed in which a light modulating layer is formed by utilizing the phase separation of a liquid crystal substance accompanying the photocuring of the photocurable vinyl compound in the above solution.
[0004]
In addition to the technique of dispersing liquid crystal droplets in such a polymer to form a light control layer, JP-A-1-198725 discloses that a liquid crystal material is a continuous layer in which a polymer is three-dimensionally uniform. A technique that enables a liquid crystal device to be driven at a low voltage by forming a liquid crystal device in a simple network structure, and Japanese Patent Application Laid-Open No. H04-40417 discloses a technique of polymerizing a polymerizable composition containing a monofunctional alkyl (meth) acrylate compound. There has been disclosed a technology that enables low-voltage driving by using a polymer material made of such a material.
[0005]
[Problems to be solved by the invention]
However, in a liquid crystal device having a dimming layer composed of a liquid crystal and a polymer, such as a liquid crystal device formed by forming a polymer having a three-dimensional network structure in a continuous layer of a liquid crystal material, a liquid crystal device IC which is currently widely used The driving voltage was not always low enough to use a driver.
[0006]
On the other hand, in a liquid crystal device capable of driving at a low voltage, an electric field is applied by driving in a low temperature range of −10 ° C. or lower, which is a practical driving temperature, and light is removed even when the electric field is removed from a state where light is transmitted. A phenomenon that does not return to the state of scattering occurs, and in this temperature range, the contrast is greatly deteriorated, and there is a practical problem that driving cannot be performed substantially (hereinafter, referred to as a “low-temperature memory phenomenon”).
[0007]
The problem to be solved by the present invention is to provide a light-scattering type liquid crystal display device which can be driven at a low voltage, has a high contrast, and can be driven practically without problems even in a low temperature range.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies, and as a result, have solved the present invention.
[0009]
That is, the present invention, in order to solve the above problems,
A liquid crystal device comprising at least one transparent substrate having an electrode layer and a light control layer supported between the substrates, wherein the light control layer contains a liquid crystal material and a transparent solid substance; Solid substance
(1) polyfunctional (meth) acrylate derivatives and
(2) A monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having a carbon number of 14 to 30 in the branched alkyl group
A liquid crystal device characterized by being a transparent solid substance obtained by polymerizing a polymerizable composition containing
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The substrate used in the present invention may be a rigid material, for example, glass, metal, or the like, or may be a flexible material, for example, a plastic film. The two substrates are opposed to each other and are obtained at an appropriate interval. In addition, at least one of them must be transparent and allow the light control layer sandwiched between the two to be seen from the outside. However, complete transparency is not essential. If the liquid crystal device is used to act on light passing from one side of the device to the other, both substrates are provided with the appropriate transparency. Appropriate transparent and opaque electrodes may be disposed on the entire or partial surface of the substrate according to the purpose.
[0011]
A light control layer made of a liquid crystal material and a transparent polymer substance is interposed between the two substrates. In general, it is desirable to interpose a spacer for maintaining a space between the two substrates, similarly to a known liquid crystal device.
[0012]
As the spacer, for example, those for various liquid crystal cells such as plastic beads, silica beads, and alumina can be used.
[0013]
The liquid crystal material used in the present invention need not be a single liquid crystal compound, but may be a mixture containing two or more liquid crystal compounds or substances other than the liquid crystal compound. Any material that is recognized as a liquid crystal material in this technical field may be used, and among them, a material having a positive dielectric anisotropy is preferable. As the liquid crystal used, a nematic liquid crystal, a smectic liquid crystal, and a cholesteric liquid crystal are preferable, and a nematic liquid crystal is particularly preferable. In order to improve the performance, a cholesteric liquid crystal, a chiral nematic liquid crystal, a chiral smectic liquid crystal, a chiral compound, or the like may be appropriately contained.
[0014]
The liquid crystal material that can be used in the present invention is a compounded composition composed of the following compound group, and has the properties of the liquid crystal material, that is, the phase transition temperature, melting point, viscosity, and birefringence of the isotropic liquid and the liquid crystal. For the purpose of considering the dielectric anisotropy, or adjusting the solubility with the polymerizable composition or the like, it can be appropriately selected and blended.
[0015]
Various liquid crystal materials such as benzoate ester, cyclohexane carboxylate, biphenyl, terphenyl, phenylcyclohexanoate, biphenylcyclohexanoate, pyrimidine, dioxane, cyclohexanecyclohexane ester, and tolane Compounds are used.
[0016]
Examples of such a liquid crystal material include 4-substituted benzoic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4′-substituted biphenyl ester, (4-substituted cyclohexanecarbonyloxy) benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4'-substituted cyclohexyl ester 4-substituted 4'-substituted biphenyl, 4-substituted phenyl 4'-substituted cyclohexane, 4-substituted 4 "-substituted terphenyl, 4-substituted biphenyl 4'-substituted cyclohexane, 2- (4-substituted phenyl) 5 -Substituted pyrimidine and the like.
[0017]
The ratio of the liquid crystal material in the light control layer is preferably in the range of 60 to 99% by weight, and particularly preferably in the range of 70 to 90% by weight. (Hereinafter, “%” means “% by weight”.)
[0018]
The transparent solid substance formed in the light control layer may be a substance in which a liquid crystal material is dispersed as droplets in a polymer, but a substance having a three-dimensional network structure is more preferable.
[0019]
It is preferable that the liquid crystal material is filled in the three-dimensional network structure portion of the transparent solid substance and that the liquid crystal material be formed continuously, whereby the disordered state of the liquid crystal molecules is formed. To form an optical boundary surface and to exhibit light scattering.
[0020]
The average network size of the three-dimensional network structure is preferably in the range of 0.2 to 5 μm, and more preferably in the range of 0.5 to 3 μm.
[0021]
The transparent polymer substance having a three-dimensional network structure interposed in the continuous layer of the liquid crystal material is not limited to a rigid one, and may have flexibility, flexibility, and elasticity as long as it can meet the purpose. .
[0022]
The liquid crystal device of the present invention can be manufactured as follows. That is, the number of carbon atoms of (I) a liquid crystal material, (II) (1) a polyfunctional (meth) acrylate derivative, and (2) a branched alkyl group is between at least one transparent substrate having an electrode layer. A polymerizable composition containing a monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group in the range of 14 to 30, (III) a photopolymerization initiator, and (IV) a chain transfer agent, A light modulating layer-forming material comprising a sensitizer, a cross-linking agent, a dye, and the like is interposed, and the polymerizable composition is polymerized by irradiating the light modulating layer-forming material with an actinic ray. A light modulating layer formed by forming a transparent solid substance having a structure in which a liquid crystal material is dispersed in a liquid crystal material, or a light modulating layer formed by forming a transparent solid substance having a three-dimensional network structure in a continuous layer of a liquid crystal material To form
[0023]
In order to interpose the dimming layer forming material between the two substrates, the dimming layer forming material may be injected between the substrates. However, an appropriate solution coating machine or a spin coater may be used on one of the substrates. Then, the other substrate may be overlaid and pressed.
[0024]
In addition, a liquid crystal device is manufactured by applying a light modulating layer constituent material on one substrate to a uniform thickness, polymerizing and curing the polymerizable composition to form a light modulating layer, and then bonding the other substrate. The method is also effective.
[0025]
In the polymerization of a polymerizable composition in a liquid crystal material by ultraviolet irradiation, the light irradiation intensity and the irradiation amount also need to be at least a certain intensity, but by selecting an appropriate light intensity, the formation of a three-dimensional network and the size of the network Uniformity can be achieved.
[0026]
More preferably, as the light irradiation method, the time and plane uniform irradiation is such that the photopolymerizable composition interposed between the substrates is instantaneously irradiated with strong light to cause polymerization to proceed, whereby It is effective in making the size of the uniform. That is, by irradiating ultraviolet rays with uniform and appropriate intensity, a transparent solid substance having a uniform three-dimensional network structure can be formed in the liquid crystal material, and as a result, the obtained liquid crystal device is This has a clear threshold value and sharpness, and enables time-division driving.
[0027]
The polymerization of the polymerizable composition preferably starts at a temperature at which the light modulating layer forming material shows an isotropic liquid state.
[0028]
The photopolymerizable composition used in the present invention, as an essential component,
(1) It contains a polyfunctional (meth) acrylate derivative and (2) a monofunctional alkyl (meth) acrylate derivative composed of a branched alkyl group having 14 to 30 carbon atoms in the branched alkyl group. May contain other polymer-forming monomers or oligomers as optional components.
[0029]
Examples of the polyfunctional (meth) acrylate derivative used in the present invention include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, and tripentyl glycol. Di (meth) acrylate or poly (meth) acrylate such as methylolpropane, glycerin and pentaerythritol; di (meth) acrylate of a diol obtained by adding 2 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol; Di (meth) acrylate or tri (meth) of triol obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of trimethylolpropane Acrylate; di (meth) acrylate of diol obtained by adding at least 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A; poly (meth) acrylate of dipentaerythritol; neopentyl glycol diacrylate pivalate; Caprolactone-modified hydroxypivalic acid ester neopentyl glycol diacrylate; linear aliphatic diacrylate; polyolefin-modified neopentyl glycol diacrylate; epoxy (meth) acrylate, polyester (meth) acrylate, polyurethane ( (Meth) acrylate, polyether (meth) acrylate, fluoro (meth) acrylate, silicon (meth) acrylate; tris- (hydroxyethyl) -isocyanuric acid poly (meth) Acrylate; poly (meth) acrylate of tris- (hydroxyethyl) -phosphoric acid; di (meth) acrylate of di- (hydroxyethyl) -dicyclopentadiene; di or tri (meth) acrylate having an isocyanurate ring in the molecule And the like.
[0030]
The monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having 14 to 30 carbon atoms in the branched alkyl group used in the present invention has a bulky steric structure due to a branched chain, and therefore, at low temperatures. Inhibits the alignment of liquid crystal molecules and suppresses the low-temperature memory phenomenon. The degree of branching of the branched alkyl group of the monofunctional alkyl (meth) acrylate derivative is determined by the formula (a)
[0031]
(Equation 3)

[0032]
Can be determined by the branching rate represented by
[0033]
At this time, the longest alkyl straight chain portion in the molecule of the (meth) acrylate derivative is used as the main chain, and all the alkyl groups branched from the main chain are used as the alkyl branched chains.
[0034]
The branching ratio used in the present invention indicates the ratio of the alkyl branched group to the alkyl group ester-bonded to the (meth) acrylate acid, and the higher the branching ratio, the higher the ratio of the branched chain molecules, and has a more bulky structure.
[0035]
The value of the branching ratio is preferably in the range of 0.3 to 0.7. When a material having a branching ratio of less than 0.3 is used, the effect of suppressing the low-temperature memory phenomenon of the obtained liquid crystal device tends to decrease. The use of is not preferred because the number of alkyl chains in the main chain becomes small and the low voltage effect of the obtained liquid crystal device tends to be small.
[0036]
When the number of carbon atoms of the branched alkyl group of the monofunctional alkyl (meth) acrylate derivative used in the present invention is smaller than 14, the vapor pressure is low and the monofunctional alkyl (meth) acrylate derivative volatilizes during vacuum injection. This is not preferable because the liquid crystal device tends to have a low voltage effect and the obtained liquid crystal device has a small low voltage effect. Further, when the number of carbon atoms of the branched alkyl group of the monofunctional alkyl (meth) acrylate derivative used in the present invention is larger than 30, the solubility with the liquid crystal material is reduced and the phase separation at the time of polymerization becomes uneven. Since the process proceeds, it is not possible to obtain a good three-dimensional network structure or mesh size of the transparent solid substance, which is not preferable.
[0037]
Therefore, in the alkyl (meth) acrylate derivative having a monofunctional alkyl branched chain used in the present invention, the number of carbon atoms of the branched alkyl group is preferably in the range of 14 to 30, as defined in claim 1.
[0038]
The monofunctional alkyl (meth) acrylate derivative composed of a branched alkyl group having 14 to 30 carbon atoms in the branched alkyl group used in the present invention has low polarity and has an effect of lowering the driving voltage of a liquid crystal device. In addition, since the resistance is high, the voltage holding ratio can be improved. Furthermore, the alkyl group has 14 or more carbon atoms, has a high molecular weight, has a low vapor pressure, and has a problem of volatilization of the (meth) acrylate derivative which occurs during a vacuum injection method generally used in a liquid crystal device manufacturing method. Less.
[0039]
The length of the main part of the branched alkyl group of the monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having a carbon number in the range of 14 to 30 used in the present invention is low. In order to enhance the voltage driving effect, the number of carbon atoms is preferably from 7 to 18, and particularly preferably from 7 to 14.
[0040]
The monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having 14 to 30 carbon atoms in the branched alkyl group used in the present invention has a large effect of suppressing a low-temperature memory phenomenon, but has a low driving voltage. In order to sufficiently obtain the effect of the polymerization, the use ratio is preferably in the range of 10 to 95% in the polymerizable composition.
[0041]
Examples of the monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having 14 to 30 carbon atoms in the branched alkyl group used in the present invention include, for example, isomyristyl (meth) acrylate and isopalmityl (meth) Acrylate, isostearyl (meth) acrylate, isoicosyl (meth) acrylate, isodocosyl (meth) acrylate, isotetracosyl (meth) acrylate, isohexacosyl (meth) acrylate, isooctacosyl (meth) acrylate, triacontyl (meth) acrylate, triacontyl (meth) acrylate And the like. Among these, a monofunctional branched alkyl (meth) acrylate derivative having a branching ratio in the range of 0.3 to 0.7 is preferable.
[0042]
Examples of the monofunctional alkyl (meth) acrylate derivative composed of a branched alkyl group having a carbon number of the branched alkyl group in the range of 14 to 30 and a branching ratio in the range of 0.3 to 0.7 include: 1-hexylheptyl acrylate (branch rate = 46.4%), 1,1-diethyloctyl acrylate (branch rate = 34.3%), 2- (3-methylbutyl) -7-methyloctyl acrylate (branch rate = 43) 0.7%), 2- (1-methylbutyl) -5-methyloctyl acrylate (branch rate = 43.7%), 2- (1-methyl-3,3-dimethylbutyl) -5-methyl-7,7 -Dimethyloctyl acrylate (branch rate = 56.9%), 2-hexyldecyl acrylate (branch rate = 37.8%), 2-octyldecyl acrylate (branch rate = 44.7%) 2-octyldodecyl acrylate (branch rate = 40.2%), 2-dodecyldodecyl acrylate (branch rate = 50.1%), 2-undecyltridecyl acrylate (branch rate = 54.3%), 2- And undecyl pentadecyl acrylate (branch rate = 42.5%).
[0043]
The monofunctional alkyl (meth) acrylate derivative composed of a branched alkyl group having 14 to 30 carbon atoms in the branched alkyl group used in the present invention is, for example, (meth) acrylic acid or (meth) acrylic chloride. Can be easily produced by (meth) acrylating a branched alkanol.
[0044]
Commercially available branched alkyl alcohols to be used as production raw materials include, in addition to general-purpose branched alkanols, for example, “7-ethyl-2-methylundecanol” (branch rate = 22.3%) manufactured by Tokyo Chemical Industry Co., Ltd., Nissan Chemical Fine Co., Ltd. “Fineoxocol 140” [2- (3-methylbutyl) -7-methyloctanol (branch rate = 43.7%) and 2- (1-methylbutyl) -5-methyloctanol (branch rate = 43 .7%)], "Fineoxocol 1600" [2-hexyldecanol (branch rate = 37.8%)], "Fineoxochol 180", "Fineoxochol 1800" [2- (1-methyl-3, 3-dimethylbutyl) -5-methyl-7,7-dimethyloctanol (branching ratio = 56.9%)], “Kalcol 200GD” [2-octy] manufactured by Kao Corporation Dodecanol (branching ratio = 40.2%)], "Kalcol 160GD" [(2-hexyl decanol (those having a number of branched various such branch ratio = 37.8%).
[0045]
As a commercially available product of a monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having 14 to 30 carbon atoms in the branched alkyl group used in the present invention, for example, "IM-" manufactured by Kyoeisha Chemical Co., Ltd. A "[2- (3-methylbutyl) -7-methyloctyl acrylate (branch rate = 43.7%) and / or 2- (1-methylbutyl) -5-methyloctyl acrylate (branch rate = 43.7%) ], "IS-A" [2- (1-methyl-3,3-dimethylbutyl) -5-methyl-7,7-dimethyloctyl acrylate (branch rate = 56.9%)] and the like. .
[0046]
Other polymer-forming monomers that can be used as optional components include, for example, styrene, chlorostyrene, α-methylstyrene, divinylbenzene; methyl, ethyl, propyl, butyl, amyl, 2-ethylhexyl as a substituent Having a group such as cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, aryl, methallyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, dimethylaminoethyl, and diethylaminoethyl. Acrylate, methacrylate or fumarate; vinyl acetate, vinyl butyrate or vinyl benzoate, acrylonitrile, cetyl vinyl ether, limonene, cyclohexene, diallyl phthalate, 2-, 3- or 4-vinylpi Gin, acrylic acid, methacrylic acid, acrylamide, methacrylamide, N-hydroxymethylacrylamide or N-hydroxyethylmethacrylamide and their alkyl ether compounds; 1 mol of 2-hydroxyethyl (meth) acrylate and phenylisocyanate or n-butylisocyanate Reaction products with 1 mol can be exemplified.
[0047]
Examples of the polymerization initiator include 2-hydroxy-2-methyl-1-phenylpropan-1-one (“Darocur 1173” manufactured by Merck) and 1-hydroxycyclohexylphenyl ketone (“Irgacure 184” manufactured by Ciba Geigy). ), 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one (“Darocure 1116” manufactured by Merck), benzyldimethylketal (“Irgacure 651” manufactured by Ciba-Geigy), 2- Methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1 (“Irgacure 907” manufactured by Ciba-Geigy) and 2,4-diethylthioxanthone (“Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.) Mixing with ethyl p-dimethylaminobenzoate ("Kayacure EPA" manufactured by Nippon Kayaku Co., Ltd.) , Isopropylthioxanthone (word pre Kin graduate flop Co. "singer cure ITX") and p- dimethylaminobenzoic mixture of ethyl, acyl phosphine oxide (BASF Corp. "Lucirin TPO"), and the like.
[0048]
The usage ratio of the photopolymerization initiator is preferably in the range of 0.1 to 10% based on the polymerizable composition.
[0049]
In the liquid crystal device of the present invention, the contrast and the driving voltage change depending on the thickness of the light control layer. When the thickness of the dimming layer is small, the driving voltage becomes extremely low, the driving can be performed by using a general-purpose circuit, and the device has low power consumption. When the thickness of the light control layer is large, the light control layer has a high scattering property when no voltage is applied, and a white and bright device is obtained.
[0050]
The thickness of the light control layer can be freely selected depending on the intended use, but is preferably in the range of 5 to 100 μm, particularly preferably in the range of 8 to 60 μm. When the thickness of the light control layer is less than 5 μm, the contrast tends to decrease. Therefore, when the thickness is more than 100 μm, although the drive voltage is sufficiently lower than that of the conventional one, the drive voltage increases and Is unfavorable because the transparency tends to decrease. In particular, in order to increase the reflectance for direct-view applications, the thickness of the light control layer is set to be relatively large, so that the liquid crystal device has a high reflectance of 30% or more and is higher than a conventional high reflectance liquid crystal device. It can be driven at a low voltage. In this case, the thickness of the light control layer is preferably in the range of 25 to 60 μm.
[0051]
The liquid crystal device of the present invention has a high ratio of the liquid crystal material in the light modulating layer. In particular, when the liquid crystal material forms a continuous layer, the driving voltage is low, and the transparency when a voltage is applied is high.
[0052]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Hereinafter, in the examples, "%" represents "% by weight", and each of the evaluation characteristics means the following symbols and contents.
T₀    : White turbidity; light transmittance (%) at an applied voltage of 0 V
T₁₀₀  : Transparency; Light transmittance (%) when light transmittance hardly increases as applied voltage is increased
V₁₀  : Threshold; T₀  0%, T₁₀₀  Is 100%, the applied voltage (V) at which the light transmittance becomes 10%_rms  )
V₉₀  : Saturation voltage; same as above. Applied voltage (V) at which light transmittance becomes 90%._rms  )
CR: contrast = T₁₀₀  / T₀
R: reflectance; ratio (%) of the reflection intensity when the reflection intensity of the standard white plate is set to 100%
[0053]
The illuminance of the ultraviolet rays was measured using a unimeter UIT-101 with a photo detector UVD-365PD manufactured by Ushio Inc.
[0054]
(Example 1)
<Liquid crystal material>
The following liquid crystal composition (A): 78.0%
<Polymerizable composition>
"Kayarad-HX-620" 10.8%
(Nippon Kayaku Co., Ltd., caprolactone-modified hydroxypivalic acid ester neo
Pentyl glycol diacrylate)
"IM-A" 10.8%
[Kyoeisha Chemical Co., Ltd. formula
[0055]
Embedded image

[0056]
2- (3-methyl) having a branched alkyl group having 14 carbon atoms represented by
Rubutyl) -7-methyloctyl acrylate (branch rate = 43.7%)
And / or 2- (1-methylbutyl) -5-methyloctyl acrylate
(Branch rate = 43.7%)]
<Polymerization initiator>
"Irgacure 651" 0.4%
(Benzyl dimethyl ketal manufactured by Ciba Geigy)
The light modulating layer-forming material consisting of is sandwiched between two ITO electrode glass substrates coated with a 11.0 μm glass fiber spacer, and the entire substrate is maintained at a uniform solution state of 40 mW / cm²Was irradiated for 60 seconds to cure the polymerizable composition to obtain a liquid crystal device having a light control layer having a thickness of 11.3 μm and comprising a liquid crystal material and a transparent solid substance.
[0057]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0058]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 1 below.
[0059]
Composition of liquid crystal composition (A):
[0060]
Embedded image

[0061]

[0062]
(Comparative Example 1)
Example 1 Example 1 was repeated except that n-myristyl acrylate (a straight-chain alkyl acrylate comprising a straight-chain alkyl group having 14 carbon atoms, branching ratio = 0%) was used in place of “IM-A”. In the same manner as in the above, a liquid crystal device having a light control layer having a thickness of 11.2 μm comprising a liquid crystal material and a transparent solid substance was obtained.
[0063]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0064]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 1 below.
[0065]
(Comparative Example 2)
Example 1 was repeated except that "IM-A" was replaced by 2-methylundecyl acrylate (a branched alkyl acrylate comprising a branched alkyl group having 12 carbon atoms, branching ratio = 8.9%). In the same manner as in Example 1, a liquid crystal device having a light modulating layer made of a liquid crystal material and a transparent solid substance and having a thickness of 11.2 μm was obtained.
[0066]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0067]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 1 below.
[0068]
[Table 1]

[0069]
From the results shown in Table 1, it can be understood that the liquid crystal device obtained in Example 1 can be driven without any trouble even at a low temperature. On the other hand, the liquid crystal device obtained in Comparative Example 1 shows almost the same performance at 25 ° C. as the liquid crystal device obtained in Example 1, but at −20 ° C., it scatters from the transparent state after the application of the voltage without applying a voltage It can be understood that the state does not return to the state and the actual driving cannot be performed. Further, the liquid crystal device obtained in Comparative Example 2 shows almost the same performance at 25 ° C. as the liquid crystal device obtained in Example 1, but at −20 ° C., V₁₀And V₉₀Are as high as 9.8 V and 18.0 V, respectively, and the temperature dependency of the driving voltage is large.
[0070]
(Example 2)
<Liquid crystal material>
78.0% of the liquid crystal composition (A)
<Polymerizable composition>
“Kayarad-HX-220” 10.8%
2-hexyldecyl acrylate 10.8%
(Toa Gosei Chemical Co., Ltd. has a branched alkyl group having a branched alkyl group having 16 carbon atoms.
(Kil acrylate, branching rate = 37.8%)
<Polymerization initiator>
"Irgacure 651" 0.4%
The light modulating layer-forming material consisting of is sandwiched between two ITO electrode glass substrates coated with a 11.0 μm glass fiber spacer, and the entire substrate is maintained at a uniform solution state of 40 mW / cm²Was irradiated for 60 seconds to cure the polymerizable composition to obtain a liquid crystal device having a light control layer having a thickness of 11.2 μm and comprising a liquid crystal material and a transparent solid substance.
[0071]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0072]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 2 below.
[0073]
[Table 2]

[0074]
From the results shown in Table 2, it can be understood that the liquid crystal device obtained in Example 2 can be driven without any trouble even at a low temperature.
[0075]
(Example 3)
<Liquid crystal material>
78.0% of the liquid crystal composition (A)
<Polymerizable composition>
“Kayarad-HX-220” 10.8%
(Nippon Kayaku Co., Ltd., caprolactone-modified hydroxypivalic acid ester neo
Pentyl glycol diacrylate)
"IS-A" 10.8%
(Kyoeisha Chemical Co., Ltd. formula
[0076]
Embedded image

[0077]
2- (1-methyl) having a branched alkyl group having 18 carbon atoms represented by
-3,3-dimethylbutyl) -5-methyl-7,7-dimethyloctyl
Acrylate, branching rate = 56.9%)
<Polymerization initiator>
"Irgacure 651" 0.4%
The light modulating layer-forming material consisting of is sandwiched between two ITO electrode glass substrates coated with a 12.0 μm glass fiber spacer, and the entire substrate is maintained at a uniform solution state of 40 mW / cm²Was irradiated for 60 seconds to cure the polymerizable composition, thereby obtaining a liquid crystal device having a light control layer having a thickness of 12.3 μm and comprising a liquid crystal material and a transparent solid substance.
[0078]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0079]
In addition, the relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 3 below.
[0080]
[Table 3]

[0081]
From the results shown in Table 3, it can be understood that the liquid crystal device obtained in Example 3 can be driven without any trouble even at a low temperature.
[0082]
(Example 4)
<Liquid crystal material>
78.0% of the liquid crystal composition (A)
<Polymerizable composition>
"Kayarad-HX-220" 12.96%
formula
[0083]
Embedded image

[0084]
8.64% of isotetracosyl monoacrylate represented by
(Branched alkyl having a branched alkyl group having 24 carbon atoms manufactured by Toagosei Co., Ltd.
(Acrylate, branching rate = 46.0%)
<Polymerization initiator>
"Irgacure 651" 0.4%
The light modulating layer-forming material consisting of is sandwiched between two ITO electrode glass substrates coated with a 11.0 μm glass fiber spacer, and the entire substrate is maintained at a uniform solution state of 40 mW / cm²Was irradiated for 60 seconds to cure the polymerizable composition to obtain a liquid crystal device having a light modulating layer composed of a liquid crystal material and a transparent solid substance and having a thickness of 11.3 μm.
[0085]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0086]
In addition, the relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 4 below.
[0087]
(Example 5)
A liquid crystal device was obtained in the same manner as in Example 4, except that a 50.0 μm glass fiber spacer was used instead of the 11.0 μm glass fiber spacer.
[0088]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device thus obtained was measured, and the results are shown in Table 4 below.
[0089]
[Table 4]

[0090]
From the results shown in Table 4, it can be understood that the liquid crystal device obtained in Example 4 can be driven without any problem even at a low temperature. In addition, it is understood that the liquid crystal device obtained in Example 5 is white and bright with a reflectivity of 30% or more, and exhibits excellent display characteristics particularly for direct-view applications, and can be driven without trouble even at low temperatures. it can.
[0091]
(Example 6)
In Example 2, except that 1-tridodecyltetradecyl acrylate (a branched alkyl acrylate having a branched alkyl group having 27 carbon atoms, branching ratio = 48.3%) was used instead of 2-hexyldecyl acrylate, In the same manner as in Example 2, a liquid crystal device having a light modulating layer made of a liquid crystal material and a transparent solid substance and having a thickness of 11.3 μm was obtained.
[0092]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0093]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 5 below.
[0094]
[Table 5]

[0095]
From the results shown in Table 5, it can be understood that the liquid crystal device obtained in Example 6 can be driven without trouble even at a low temperature.
[0096]
(Comparative Example 3)
Example 2 was repeated except that 2-hexyldecyl acrylate was replaced with 1-pentadecylhexyl acrylate (branched alkyl acrylate having a branched alkyl group having 31 carbon atoms, branching rate = 48.3%) in Example 2. An attempt was made to produce a liquid crystal device having a light modulating layer composed of a liquid crystal material and a transparent solid substance in the same manner as in Example 2. However, since the molecular weight of the branched alkyl group of the branched alkyl acrylate used was large, the light modulating layer forming material was used. The compatibility between the liquid crystal material and the polymerizable composition in the polymer composition is reduced, and thus, when the polymerizable composition is cured, a liquid crystal device having a light modulating layer composed of a uniform three-dimensional network transparent solid material is obtained. I couldn't do that.
[0097]
(Example 7)
<Liquid crystal material>
The following liquid crystal composition (B): 78.0%
<Polymerizable composition>
“Kayarad-HX-220” 10.8%
2-octyldecyl acrylate (having a branched alkyl group having 18 carbon atoms)
Branched alkyl acrylate, branch ratio = 44.7%) 10.8%
<Polymerization initiator>
"Irgacure 651" 0.4%
The light modulating layer-forming material consisting of is sandwiched between two ITO electrode glass substrates coated with a 11.0 μm glass fiber spacer, and the entire substrate is maintained at a uniform solution state of 40 mW / cm²Was irradiated for 60 seconds to cure the polymerizable composition to obtain a liquid crystal device having a light control layer having a thickness of 11.2 μm and comprising a liquid crystal material and a transparent solid substance.
[0098]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0099]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 6 below.
[0100]
Composition of liquid crystal composition (B):
Embedded image

[0101]

[0102]
[Table 6]

[0103]
From the results shown in Table 6, it can be understood that the liquid crystal device obtained in Example 7 can be driven without any problem even at a low temperature.
[0104]
(Example 8)
In Example 7, instead of 2-octyldecyl acrylate, the formula
[0105]
Embedded image

[0106]
Example 7 except that 10.8% of isoicosyl monoacrylate (a branched alkyl acrylate having a branched alkyl group having 20 carbon atoms, manufactured by Toagosei Co., Ltd., branching ratio = 40.2%) represented by Similarly, a liquid crystal device having a light control layer having a thickness of 11.2 μm and comprising a liquid crystal material and a transparent solid substance was obtained.
[0107]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0108]
Further, the relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 7 below.
[0109]
(Example 9)
A liquid crystal device was obtained in the same manner as in Example 8, except that a 30.0 μm glass fiber spacer was used instead of the 11.0 μm glass fiber spacer.
[0110]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device thus obtained was measured, and the results are shown in Table 7 below.
[0111]
(Comparative Example 4)
Example 7 Example 7 was repeated except that 1-0.8% of n-icosyl monoacrylate (linear alkyl acrylate comprising a linear alkyl group having 20 carbon atoms) was used in place of 2-octyldecyl acrylate in Example 7. In the same manner as in the above, a liquid crystal device having a light control layer having a thickness of 11.2 μm comprising a liquid crystal material and a transparent solid substance was obtained.
[0112]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0113]
Further, the relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 7 below.
[0114]
[Table 7]

[0115]
From the results shown in Table 7, it can be understood that the liquid crystal device obtained in Example 8 can be driven without any trouble even at a low temperature. In addition, the liquid crystal device obtained in Example 9 was sufficiently low in comparison with the driving voltage of the liquid crystal device obtained in Comparative Example 4, and was white and bright with a reflectance of 30% or more, and was particularly excellent in direct-view type applications. It can be understood that it shows display characteristics and can be driven without any trouble even at a low temperature. On the other hand, the liquid crystal device obtained in Comparative Example 4 shows almost the same performance at 25 ° C. as the liquid crystal device obtained in Example 8, but at −20 ° C., it scatters from the transparent state after the application of a voltage without applying a voltage. It can be understood that the state does not return to the state and the actual driving cannot be performed.
[0116]
(Comparative Example 10) In Example 7, instead of 2-octyldecyl acrylate, the formula
[0117]
Embedded image

[0118]
Example 7 except that 1-methyl-1-tridecyl acrylate (a branched alkyl acrylate comprising a branched alkyl group having 14 carbon atoms, manufactured by Tokyo Chemical Industry Co., Ltd., branching ratio = 7.6%) represented by In the same manner, a liquid crystal device having a light control layer having a thickness of 11.3 μm comprising a liquid crystal material and a transparent solid substance was obtained.
[0119]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0120]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 8 below.
[0121]
(Comparative Example 5)
In Example 7, instead of 2-octyldecyl acrylate, the formula
[0122]
Embedded image

[0123]
Liquid crystal was prepared in the same manner as in Example 7, except that 2-ethylhexyl acrylate (a branched alkyl acrylate comprising a branched alkyl group having 8 carbon atoms, manufactured by Tokyo Chemical Industry Co., Ltd .; branching ratio = 25.7%) was used. A liquid crystal device having a light modulating layer made of a material and a transparent solid substance and having a thickness of 11.2 μm was obtained.
[0124]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0125]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 8 below.
[0126]
(Comparative Example 6)
Example 7 was repeated except that 2-methylundecyl acrylate (branched alkyl acrylate comprising a branched alkyl group having 12 carbon atoms, branching ratio = 8.9%) was used in place of 2-octyldecyl acrylate in Example 7. In the same manner as in Example 7, a liquid crystal device having a light control layer having a thickness of 11.3 μm and comprising a liquid crystal material and a transparent solid substance was obtained.
[0127]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0128]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 8 below.
[0129]
[Table 8]

[0130]
From the results shown in Table 8, the liquid crystal device obtained in Example 10 shows almost the same performance at 25 ° C. as the liquid crystal device obtained in Example 1, but it can be actually driven at −20 ° C. Since the acrylate derivative having a low branching ratio (7.6%) is used, the low-temperature memory phenomenon cannot be completely suppressed, and a decrease in contrast is observed. However, T at -20 ° C₀  Is about 10%, which is not a level that cannot be put to practical use. On the other hand, the liquid crystal device obtained in Comparative Example 5 has a sufficient contrast at −20 ° C., but has a driving voltage of 13.7 V because alkyl acrylate having a small number of carbon atoms of 8 and a low voltage effect is used._rms  It can be understood that it is not high and is not satisfactory. Further, the liquid crystal device obtained in Comparative Example 6 had a V₉₀Is close to 20 V, which is not satisfactory.
[0131]
(Comparative Example 7)
<Liquid crystal material>
78.0% of the liquid crystal composition (B)
<Polymerizable composition>
“Kayarad-HX-220” 21.6%
<Polymerization initiator>
"Irgacure 651" 0.4%
The light modulating layer-forming material consisting of is sandwiched between two ITO electrode glass substrates coated with a 50.0 μm glass fiber spacer, and the entire substrate is kept at 40 mW / cm²Was irradiated for 60 seconds to cure the polymerizable composition, thereby obtaining a liquid crystal device having a light control layer having a thickness of 50.2 μm and comprising a liquid crystal material and a transparent solid substance.
[0132]
As a result of observing the light control layer of the liquid crystal device thus obtained by using an electron microscope, a three-dimensional network transparent solid material could be confirmed.
[0133]
In addition, the relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device was measured, and the results are shown in Table 9 below.
[0134]
(Comparative Example 8)
A liquid crystal device was obtained in the same manner as in Comparative Example 4, except that a 51.0 μm glass fiber spacer was used instead of the 11.0 μm glass fiber spacer.
[0135]
The relationship between the applied voltage and the light transmittance at 25 ° C. and −20 ° C. of the liquid crystal device thus obtained was measured, and the results are shown in Table 9 below.
[0136]
[Table 9]

[0137]
*) The liquid crystal device obtained in Comparative Example 7_rmsSince the transmittance was not sufficiently saturated even when a voltage was applied up to₁₀₀Column, the applied voltage 50V_rmsThe light transmittance at the time of is listed. Similarly, the value of CR of Comparative Example 7 in Table 9 is the light transmittance at an applied voltage of 0 and the applied voltage of 50 V_rmsThe values of the contrast calculated from the light transmittance of the sample were listed. Also, V of Comparative Example 7 in Table 9₁₀Is T₁₀₀Was not able to be measured because the value of was not measurable.
[0138]
From the results shown in Table 9, the reflectivity of the liquid crystal device obtained in Comparative Example 7 was as high as 30% or more, but the applied voltage was 50 V._rmsEven so, it can be understood that the transmittance is not saturated and the driving voltage is extremely high. At 25 ° C., the liquid crystal device obtained in Comparative Example 8 exhibits almost the same performance as the liquid crystal device obtained in Example 9, but at −20 ° C., it changes from the transparent state after voltage application to the scattering state without voltage application. I could not return and could not actually drive.
[0139]
(Comparative Example 9)
In Example 7, except that 1-hexadecylnonadecyl acrylate (a branched alkyl acrylate composed of a branched alkyl group having 35 carbon atoms, branching ratio = 45.8%) was used instead of 2-octyldecyl acrylate, An attempt was made to produce a liquid crystal device having a dimming layer composed of a liquid crystal material and a transparent solid substance in the same manner as in Example 7. The compatibility between the liquid crystal material in the material and the polymerizable composition is reduced, and therefore, when the polymerizable composition is cured, a liquid crystal device having a light modulating layer composed of a uniform three-dimensional network transparent solid material is used. I couldn't get it.
[0140]
【The invention's effect】
The liquid crystal device of the present invention has a bright display screen without a polarizing plate, is a large-area thin film type, can be driven at a low voltage, and can display bright and high reflectance. In addition, since driving can be performed even in a low temperature range of −20 ° C., practicability is improved.
[0141]
Therefore, it is extremely useful not only as a conventional dimming liquid crystal device of this type but also as a liquid crystal device having a large screen, a thin shape and a higher display quality.

Claims (7)

A liquid crystal device comprising at least one transparent substrate having an electrode layer and a light control layer supported between the substrates, wherein the light control layer contains a liquid crystal material and a transparent solid substance; sex solid material, (1) polyfunctional (meth) acrylate derivative and (2) a monofunctional alkyl carbon atoms as the branched alkyl group consisting of branched alkyl groups in the range of 14-30 (meth) acrylate derivative Then, the branching ratio of the branched alkyl group, the formula (a)

A transparent solid substance obtained by polymerizing a polymerizable composition containing a monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group in the range of 0.3 to 0.7. device. The liquid crystal device according to claim 1, wherein the number of carbon atoms in the main chain of the branched alkyl group of the monofunctional alkyl (meth) acrylate derivative is in the range of 7 to 18. 3. The liquid crystal device according to claim 1, wherein the light modulating layer has a three-dimensional network transparent solid substance in a continuous layer of a liquid crystal material. 4. The liquid crystal device according to claim 1, wherein the light modulating layer has a thickness of 8 to 80 [mu] m. 4. The liquid crystal device according to claim 1, wherein the thickness of the light control layer is in the range of 25 to 80 [mu] m. After sandwiching a light modulating layer forming material containing a liquid crystal material, a polymerizable composition, and a photopolymerization initiator between two substrates having at least one transparent electrode layer, the polymerizable material is irradiated with an actinic ray to polymerize the material. In the method for producing a liquid crystal device in which the composition is polymerized to form a light control layer having a liquid crystal material and a transparent solid substance, the polymerizable composition may be (1) a polyfunctional (meth) acrylate derivative and (2) A monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having from 14 to 30 carbon atoms in the branched alkyl group, wherein the branching ratio of the branched alkyl group is represented by the formula (a)

A method for producing a liquid crystal device, comprising using a polymerizable composition containing a monofunctional alkyl (meth) acrylate derivative comprising a branched alkyl group having a range of 0.3 to 0.7 . The method for producing a liquid crystal device according to claim 6, wherein the number of carbon atoms in the main chain of the branched alkyl group of the monofunctional alkyl (meth) acrylate derivative is in the range of 7 to 18.