Liquid-crystal display device and process for producing liquid-crystal display device

Patent metadata

Field	Value
Publication number	US-2016170269-A1
Application number	US-201314436580-A
Country	US
Kind code	A1
Filing date	Oct 17, 2013
Priority date	Oct 19, 2012
Publication date	Jun 16, 2016
Grant date	—

Abstract

The present invention provides a liquid-crystal display device capable of maintaining a high voltage holding ratio even without an alignment film. The liquid-crystal display device of the present invention includes a pair of substrates, a liquid crystal layer which is sandwiched between the substrates and which contains a liquid crystal material, and a polymer layer which is disposed on a surface of each of the substrates and which controls the alignment of liquid crystal molecules. The outermost surfaces of both the substrates comprise substantially no alignment film. The polymer layer is formed by polymerizing one or more radical polymerizable monomer species added to the liquid crystal layer. At least one species of the one or more radical polymerizable monomer species is a biphenyl compound having a specific structure.

First claim

1 : A liquid-crystal display device comprising
a pair of substrates; a liquid crystal layer which is sandwiched between the substrates and which contains a liquid crystal material; and a polymer layer which is disposed on a surface of each of the substrates and which controls the alignment of liquid crystal molecules, the outermost surfaces of both the substrates comprising substantially no alignment film, the polymer layer being formed by polymerizing one or more radical polymerizable monomer species added to the liquid crystal layer, and at least one species of the one or more radical polymerizable monomer species being a compound represented by the following formula (1):

wherein
X 1 and X 2 may be the same as or different from each other, and represent acryloyl, methacryloyl, vinyl, or allyl;
a is 0 or 1;
b is 0 or 1;
c is 0 or 1;
R is a C1-C20 alkyl; and
each hydrogen atom may optionally be replaced by halogen, methyl, ethyl, or propyl.

2 : The liquid-crystal display device according to claim 1 ,
wherein R in the compound of the formula (1) is a C4-C20 alkyl.

3 : The liquid-crystal display device according to claim 1 ,
wherein R in the compound of the formula (1) is a C8-C20 alkyl.

4 : The liquid-crystal display device according to claim 1 ,
wherein R in the compound of the formula (1) is a C16-C20 alkyl.

5 : The liquid-crystal display device according to claim 1 ,
wherein at least another one species of the one or more radical polymerizable monomer species has a cyclic structure and a monofunctional polymerizable group.

6 : The liquid-crystal display device according to claim 5 ,
wherein the radical polymerizable monomer having a cyclic structure and a monofunctional polymerizable group is a compound represented by the following formula (2):

wherein
X represents acrylate, methacrylate, acryloyloxy, methacryloyloxy, vinyl, or allyl;
m is an integer of 0 to 12;
a is 0 or 1;
b is 0 or 1;
R is a C1-C20 alkyl; and
each hydrogen atom may optionally be replaced by halogen, methyl, ethyl, or propyl.

7 : The liquid-crystal display device according to claim 6 ,
wherein R in the compound of the formula (2) is a C4-C12 alkyl.

8 : The liquid-crystal display device according to claim 6 ,
wherein R in the compound of the formula (2) is a C8-C12 alkyl.

9 : The liquid-crystal display device according to claim 6 ,
wherein m in the compound of the formula (2) is an integer of 2 or greater.

10 : The liquid-crystal display device according to claim 6 ,
wherein m in the compound of the formula (2) is an integer of 4 or greater.

11 : The liquid-crystal display device according to claim 6 ,
wherein m in the compound of the formula (2) is an integer of 8 or greater.

12 : The liquid-crystal display device according to claim 1 ,
wherein the proportion of the compound of the formula (1) is not lower than 0.5% by weight and not higher than 2.5% by weight in the whole liquid crystal composition constituting the liquid crystal layer before the polymerization.

13 : The liquid-crystal display device according to claim 5 ,
wherein the ratio of the radical polymerizable monomer having a cyclic structure and a monofunctional polymerizable group is 10 mol % or more to the compound of the formula (1) before the polymerization.

14 : The liquid-crystal display device according to claim 1 ,
wherein the liquid crystal material has negative dielectric constant anisotropy.

15 : A process for producing a liquid-crystal display device, comprising the steps of:
injecting a liquid crystal composition that contains a liquid crystal material and one or more radical polymerizable monomer species into between a pair of substrates the outermost surfaces of which comprise substantially no alignment film; and applying light to the liquid crystal composition to polymerize the radical polymerizable monomers to thereby form a polymer layer which controls the alignment of liquid crystal molecules on a surface of each of the substrates, at least one species of the one or more radical polymerizable monomer species being a compound represented by the following formula (1):

wherein
X 1 and X 2 may be the same as or different from each other, and represent acryloyl, methacryloyl, vinyl, or allyl;
a is 0 or 1;
b is 0 or 1;
c is 0 or 1;
R is a C1-C20 alkyl; and
each hydrogen atom may optionally be replaced by halogen, methyl, ethyl, or propyl.

16 - 28 . (canceled)

29 : The process for producing a liquid-crystal display device according to claim 15 , further comprising
a heating step at a temperature not lower than the temperature 30° C. lower than the phase transition temperature of the liquid crystal material.

30 : The process for producing a liquid-crystal display device according to claim 15 , further comprising:
an annealing step before the light application step.

Assignees

• Sharp Kk

Inventors

• Noma Takeshi
• Nakanishi Youhei
• Mizusaki Masanobu

Classifications

• C09K2019/548

  stabilizing the alignment; Polymer stabilized alignment · CPC title

• C09K19/542

  Macromolecular compounds · CPC title

• C09K2019/122

  Ph-Ph · CPC title

• G02F2202/023

  curable · CPC title

• C09K3/10

  {Materials in mouldable or extrudable form} for sealing or packing joints or covers (filling pastes C09D5/34) · CPC title