申请人:Merck Patent GmbH
公开号:US20010016238A1
公开(公告)日:2001-08-23
To improve switching times, especially at low temperatures, one or more reactive liquid crystalline compounds is added to a liquid crystal mixture used in an electroptical system. The electroptical system comprises
a PDLC film comprising a liquid crystal mixture forming micro- droplets in an optically isotropic, transparent polymer matrix between 2 electrode layers,
one of the refractive indices of the liquid crystal mixture is matched to the refractive index of the polymer matrix,
the PDLC film exhibits an electrically switching transparency essentially independent of the polarization of the incident light,
the precursor of the PDLC film comprises one or more monomers, oligomers and/or prepolymers and a photoinitiator, and is cured photoradically,
the liquid crystal mixture comprises one or more compounds of the formula I
1
wherein R, A
1
, A
2
, Z
1
, Z
2
, X
1
, X
2
, Q, Y and n are as defined herein.
2
independently of one another, are trans-1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene or 3,5-difluoro-1,4-phenylene and one of
3
may also be pyrimidine-2,5-diyl, pyridine-2,5-diyl or trans-1,3-dioxane-2,5-diyl,
X
1
and X
2
, independently from one another, are H or F,
Q is —CF
2
, —OCF
2
, —C
2
F
4
, —OC
2
F
4
or a single bond,
Y is —H, —F, —Cl or —CN,
n is 0, 1 or 2 and
R is alkyl having up to 13 C atoms, in which one or two non-adjacent CH
2
groups can also be replaced by —O— and/or —CH═CH—
characterized in that the liquid crystal mixture additionally contains one or more reactive liquid crystalline compounds in order to obtain improved switching times especially at low temperatures.
为了提高开关时间,尤其是在低温条件下的开关时间,可将一种或多种活性液晶化合物添加到用于光电系统的液晶混合物中。光电系统包括
由液晶混合物组成的 PDLC 薄膜,该液晶混合物在两个电极层之间的光学各向同性透明聚合物基质中形成微液滴、
液晶混合物的折射率之一与聚合物基体的折射率相匹配、
PDLC 薄膜显示出与入射光偏振基本无关的电开关透明度、
PDLC 薄膜的前体包括一种或多种单体、低聚物和/或预聚物以及光引发剂,并经光固化、
液晶混合物包括一种或多种式 I 的化合物
1
其中 R、A
1
, A
2
, Z
1
, Z
2
, X
1
, X
2
Q、Y 和 n 的定义与本文相同。
2
分别是反式-1,4-环己烯、1,4-亚苯基、2-氟-1,4-亚苯基、3-氟-1,4-亚苯基、2,3-二氟-1,4-亚苯基或 3,5-二氟-1,4-亚苯基,以及下列物质之一
3
也可以是嘧啶-2,5-二基、吡啶-2,5-二基或反式-1,3-二氧六环-2,5-二基、
X
1
和 X
2
相互独立地为 H 或 F、
Q 是-CF
2
,-OCF
2
, -C
2
F
4
, -OC
2
F
4
或单键、
Y 是-H、-F、-Cl 或-CN、
n 是 0、1 或 2,以及
R 是具有多达 13 个 C 原子的烷基,其中一个或两个不相邻的 CH
2
基团也可以被-O-和/或-CH═CH-取代。
其特征在于,液晶混合物中还含有一种或多种活性液晶化合物,以获得更好的开关时间,尤其是在低温条件下。