JP2000281629A - Polymerizable rod-shaped nematic liquid crystal compound, cholesteric liquid crystal composition, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new compound producible by introducing plural polymerizable groups to both terminals of a trans compound containing at least plural ethynylene bonds, having high Δn, usable for a cholesteric reflection membrane and providing a liquid crystal display device having high utilization efficiency of light. SOLUTION: The objective compound is expressed by formula I (Ar1 to Ar4 are each an aromatic ring or an aromatic heterocyclic group; L1 and L5 are each a linking group selected from among single bond, O, CO and the like; L2 to L4 are each single bond, an alkenylene or the like and containing at least two ethynylene bonds; (m) and (n) are each 0 or 1; Q1 and Q2 are each a polymerizable group) and preferably exhibits nematic phase of >=Δ0.25, such as the compound of formula II. The objective compound can be produced by preparing a rod-shaped nematic liquid crystal compound free from polymerizable group by conventional method and introducing the polymerizable groups Q1 and Q2 by conventional method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymerizable rod-like nematic liquid crystal compound, a cholesteric liquid crystal composition, a cholesteric alignment optical thin film, a cholesteric polarizing plate, a cholesteric reflective polarizing plate, and a liquid crystal display device.

[0002]

2. Description of the Related Art It is a well-known phenomenon that an optical thin film formed from a cholesteric liquid crystalline composition exhibits selective reflection at a specific wavelength (for example, see Surface Vol. 2).
2, 538 (1984)). The half width of the selective reflection wavelength depends on Δn of the cholesteric liquid crystal. Since Δn of the conventional cholesteric liquid crystal is generally small, the half width of the selective reflection wavelength of the optical thin film formed from the cholesteric liquid crystal composition is also narrow. Conventionally, various means have been proposed for reflecting the optical thin film in as wide a range as possible within the visible region. JP-A-1-207328
In Japanese Patent Application Laid-Open Publication No. H11-264, a method is proposed in which a cholesteric reflection film is heated to increase the half width. Also, European Patent 69
In the specification of 06940A2, in the polymerization fixing treatment,
A method for extending the width of a cholesteric helical pitch is disclosed. Further, US Pat. No. 5,486,935 discloses a cholesteric liquid crystal in which Δn shows a large value.
It has been proposed to use cyanotran.

[0003]

The means proposed to increase the half width of the cholesteric reflection film proposed so far is complicated in processing, high in cost, or insufficient in effect, and is put to practical use. Had a problem. Therefore, means for laminating a large number of cholesteric reflective films having a narrow half-value width has been proposed (R. Mauer, SID'90Digest) and has been actually used. Although multilayer films have problems of manufacturing cost and delamination, practical alternative means have not been proposed yet. An object of the present invention is to provide a polymerizable rod-like nematic liquid crystal compound and a cholesteric liquid crystal composition which have a large Δn and can be used for a cholesteric reflection film. Another object of the present invention is to provide a cholesteric alignment optical thin film having a wide half width, a cholesteric polarizing plate, and a cholesteric reflective polarizing plate. Still another object of the present invention is to provide a liquid crystal display device having high light use efficiency.

[0004]

An object of the present invention is to provide a polymerizable rod-like nematic liquid crystal compound of the following (1) to (3):
A cholesteric liquid crystalline composition of the following (4) to (6), a cholesteric alignment optical thin film of the following (7) to (11),
This has been achieved by the following cholesteric polarizing plates (12) to (13), cholesteric reflective polarizing plates (14) to (15), and liquid crystal display devices (16) to (17). (1) A polymerizable rod-like nematic liquid crystal compound represented by the following formula (I). (I) Q ¹ -L ¹ -Ar ^1- (L ² -Ar ² ) _m- (L ³ -Ar ³ )
_n -L ⁴ -Ar in ⁴ -L ⁵ -Q ^{2 Formula, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
m and n are 0 or 1; and Q1 and Q2 are each independently a polymerizable group. (2) The polymerizable rod-like nematic liquid crystal compound according to (1), wherein the polymerizable rod-like nematic liquid crystal compound exhibits a nematic phase having a Δn of 0.25 or more. (3) The polymerizable rod-like nematic liquid crystal compound according to claim 1, wherein the polymerizable group of Q ¹ and Q ² is an ethylenically unsaturated group or an epoxy group.

(4) A cholesteric liquid crystal composition containing a polymerizable rod-like nematic liquid crystal compound represented by the following formula (I) and an optically active compound. (I) Q ¹ -L ¹ -Ar ^1- (L ² -Ar ² ) _m- (L ³ -Ar ³ )
_n -L ⁴ -Ar in ⁴ -L ⁵ -Q ^{2 Formula, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
m and n are 0 or 1; and Q ¹ and Q ² are each independently a polymerizable group. (5) The cholesteric liquid crystal composition according to (4), wherein the optically active compound has a polymerizable group. (6) The cholesteric liquid crystalline composition according to (5), wherein the polymerizable group of the optically active compound is an ethylenically unsaturated group or an epoxy group.

(7) A cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active compound. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. (8) A cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active structure. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. (9) The cholesteric alignment optics according to (7) or (8), wherein the rod-like nematic liquid crystalline repeating unit is twist-aligned so as to have a helical axis in a direction substantially perpendicular to the surface of the optical thin film. Thin film. (10) The cholesteric alignment optical thin film according to (7) or (8), wherein a horizontal alignment film having a function of substantially horizontally aligning the rod-shaped nematic liquid crystal molecules is provided adjacent to the optical thin film. (11) The cholesteric alignment optical thin film according to (7) or (8), having a selective reflection wavelength region in a range of 400 to 850 nm.

(12) A cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active compound:
A cholesteric polarizing plate having a / 4 plate. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. (13) A cholesteric alignment optical thin film including a polymer having a rod-shaped nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active structure, and a cholesteric polarizing plate having a λ / 4 plate. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1.

(14) A cholesteric orienting optical thin film comprising a reflecting plate, a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active compound, and a cholesteric having a λ / 4 plate in this order: Reflective polarizing plate. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. (15) Cholesteric reflection-type polarized light having a reflector, a cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystal repeating unit represented by the following formula (II) and a polymer having an optically active structure, and a λ / 4 plate in this order: Board. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1.

(16) A reflection plate, a cholesteric alignment optical thin film, a λ / 4 plate and a liquid crystal cell comprising a polymer having a rod-like nematic liquid crystal repeating unit represented by the following formula (II) and an optically active compound: Liquid crystal display device having in order. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. (17) A liquid crystal having a reflecting plate, a cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystal repeating unit represented by the following formula (II) and an optically active structure, a λ / 4 plate and a liquid crystal cell in this order Display device. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1.

[0010]

As a result of research, the present inventor has found that two polymerizable groups are introduced into both ends of a tolane compound containing at least two ethynylene (-C≡C-) bonds to form a polymerizable rod-like nematic liquid crystal. The compound was successfully obtained. This compound has a large Δn and can be used for a cholesteric reflective film. That is, from the cholesteric liquid crystal composition containing the polymerizable rod-shaped nematic liquid crystal compound and the optically active compound (chiral agent), a cholesteric alignment optical thin film functioning as a cholesteric reflection film can be obtained.
The obtained cholesteric reflective film has a wide half width even if it is a single layer. Accordingly, the cholesteric polarizing plate or the cholesteric reflective polarizing plate using the cholesteric reflective film exhibits excellent optical functions. Further, the liquid crystal display device using the cholesteric reflective polarizing plate selectively reflects light, and thus has high light use efficiency.

[0011]

FIG. 1 is a schematic sectional view of a liquid crystal display device using a cholesteric reflection type polarizing plate. FIG.
The transmission type liquid crystal display device shown in (a) has a reflector (RP),
It has a configuration of a backlight (BL), a cholesteric alignment optical thin film (1), a λ / 4 plate (2), a lower polarizing plate (3a), a liquid crystal cell (4), and an upper polarizing plate (3b).
The reflection type liquid crystal display device shown in FIG.
P), a backlight (BR), a cholesteric alignment optical thin film (1), a λ / 4 plate (2), a polarizing plate (3), and a liquid crystal cell (4). Backlight (B
R) may be arranged on the side surface of the liquid crystal display device, and the light may be guided from the side surface to the position immediately below the cholesteric alignment optical thin film (1) (the position of BL in FIG. 1) by the light guide plate. A light diffusion plate is provided between the cholesteric alignment optical thin film (1) and the λ / 4 plate (2), or between the λ / 4 plate (2) and the lower polarizing plate (3a) or the polarizing plate (3). It may be provided. Polarizing plate (3
An optical compensation sheet may be inserted between a, 3b, 3) and the liquid crystal cell (4).

[Polymerizable rod-shaped nematic liquid crystalline compound] The polymerizable rod-shaped nematic liquid crystalline compound is represented by the following formula (I). (I) Q ¹ -L ¹ -Ar ^1- (L ² -Ar ² ) _m- (L ³ -Ar ³ )
_{^{n -L 4 -Ar 4 -L 5 -Q}} 2 In formula ^{(I), Ar 1, Ar} 2, Ar 3 and Ar
⁴ is each independently an aromatic ring or an aromatic heterocyclic ring. Examples of the aromatic ring include a benzene ring, an indene ring,
A naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, a triphenylene ring and a pyrene ring are included. The aromatic heterocycle is generally a 5- or 6-membered unsaturated heterocycle. The heterocycle preferably contains the most double bonds. Another heterocyclic ring, aromatic ring or aliphatic ring may be fused to the aromatic heterocyclic ring. Examples of the aromatic heterocyclic ring include a furan ring, a thiophene ring, a pyrrole ring,
Oxazole ring, isoxazole ring, thiazole ring,
Isothiazole ring, imidazole ring, pyrazole ring, furazane ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, benzothiazole ring, benzoxazole ring, Indolizine ring, chromene ring, quinoline ring, isoquinoline ring, quinolidine ring, purine ring, indazole ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring and phenanthridine ring .

An aromatic ring is preferable to an aromatic hetero ring, and a benzene ring is more preferable. -Ar ^1- , -A
r ² —, —Ar ³ — and —Ar ⁴ — are particularly preferably p-phenylene. The aromatic ring and the aromatic heterocyclic ring may have a substituent. Examples of substituents include
Includes halogen atoms (F, Cl, Br), carboxyl, cyano, alkyl groups, cycloalkyl groups and alkoxy groups. The alkyl group may have a branch. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, and preferably 1 to 15 carbon atoms.
It is more preferably from 10 to 10, and most preferably from 1 to 6. The cycloalkyl group is preferably cyclohexyl. The alkoxy group is
It may have a branch. The alkoxy group preferably has 1 to 20 carbon atoms, more preferably 1 to 15, more preferably 1 to 10, and most preferably 1 to 6.

In the formula (I), L ¹ and L ⁵ are each independently a single bond or a divalent linking group selected from —O—, —CO—, —alkylene group— and a combination thereof. L ¹ and L ⁵ are preferably each independently a divalent linking group consisting of a combination of —O—, —CO—, or —alkylene group—. L ¹
And examples of L ^5, below. Q is a polymerizable group (Q ¹ or Q ² ), and Ar is an aromatic ring or an aromatic hetero ring (Ar ¹ or Ar ⁴ ) closest to the polymerizable group. (L-0) Single bond (L-1) Q-CO-O-alkylene group-O-Ar (L-2) Q-alkylene group-O-alkylene group-O-
Ar (L-3) Q-O-CO-alkylene group-O-Ar (L-4) Q-CO-O-alkylene group-O-alkylene group-Ar The alkylene group has a branched or cyclic structure. May be. The number of carbon atoms of the alkylene group is preferably 1 to 30, more preferably 1 to 20, still more preferably 1 to 15, and 1 to 1
Most preferably, it is 2.

In the formula (I), L^Two, L^ThreeAnd L^Four
Are each independently a single bond, an alkenylene group or
Is -alkynylene-. Where L^Two, L^ThreeAnd
And L ^FourHas at least two ethynylene bonds (-C≡C
-) Is included. L^Two, L^ThreeAnd L^FourIs German
Preferably, it is a single bond or -alkynylene-.
Good. L^Two, L^ThreeAnd L^FourIs shown below. (L-10) Single bond (L-11) -C≡CC−C- (L-12) -C≡C- (L-13) -C≡C-CH = CH-C≡C- ( L-14) -C≡CC−CC−C-

In the formula (I), m and n are 0 or 1. m is preferably 0 or 1 and n is preferably 0 (the number of aromatic rings or aromatic heterocycles is 2 or 3), and m is 1 and n is 0 (the number of aromatic rings or aromatic heterocycles). Most preferably, the number is 3). In the formula (I), Q ¹ and Q ² are each independently a polymerizable group. The polymerizable group is determined according to the type of the polymerization reaction. Examples of the polymerizable group (Q) are shown below.

[0017]

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[0018]

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[0019]

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The polymerizable group (Q) is an unsaturated polymerizable group (Q-
1 to Q-7), an epoxy group (Q-7) or an aziridinyl group (Q-8), more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group (Q- 1 to Q-6). Hereinafter, specific examples of the polymerizable rod-like nematic liquid crystal compound represented by the formula (I) are shown.

[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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The polymerizable rod-like nematic liquid crystalline compound has a Δ
It is preferable that n shows a nematic phase of 0.25 or more, and it is more preferable that Δn shows a nematic phase of 0.35 to 0.80. A variety of literatures (for example, Y.G.
oto et.al., Mol. Cryst. Liq. Cryst. 1995, Vol. 26
0, pp.23-28). Polymerizable groups (Q ¹ and Q
² ) can be introduced into a rod-like nematic liquid crystal compound by a known method. Two or more polymerizable rod-shaped nematic liquid crystal compounds may be used in combination. When two or more polymerizable rod-shaped nematic liquid crystal compounds are used in combination, the alignment temperature can be lowered.

[Cholesteric liquid crystalline composition] A cholesteric liquid crystalline composition can be obtained by mixing a polymerizable rod-like nematic liquid crystalline compound and an optically active compound (chiral agent). As the optically active compound, known chiral agents (for example, Liquid Crystal Device Handbook, Chapter 3, 4-3)
Section, TN and STN chiral agents, p. 199, described in the 142nd Committee of the Japan Society for the Promotion of Science, 1989). The optically active compound generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound containing no asymmetric carbon atom can also be used as a chiral agent. Examples of the axially or planarly asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. Optically active compounds (chiral agents)
It may have a polymerizable group. When the optically active compound has a polymerizable group, a polymer having a rod-shaped nematic liquid crystal repeating unit and an optically active structure can be formed by a polymerization reaction of the polymerizable rod-shaped nematic liquid crystal compound. The polymerizable group of the optically active compound is preferably the same as the polymerizable group of the polymerizable rod-shaped nematic liquid crystal compound. Therefore, the polymerizable group of the optically active compound may be an unsaturated polymerizable group (Q-1 to Q-7 in the example described above), an epoxy group (Q-7) or an aziridinyl group (Q-8). Preferably, it is more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group (Q-1 to Q-6)
Is most preferred. The amount of the optically active compound used is 0.01% of the amount of the polymerizable rod-like nematic liquid crystal compound.
It is preferable that the content be from 200 to 200 mol%.

It is preferable to add a polymerization initiator for the polymerization reaction to the cholesteric liquid crystalline composition. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. Photopolymerization reactions are preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in U.S. Pat. Nos. 2,367,661 and 2,367,670) and acyloin ethers (U.S. Pat.
828), α-hydrocarbon-substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512),
Polynuclear quinone compounds (U.S. Pat.
51758), a combination of a triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), an acridine and phenazine compound (Japanese Unexamined Patent Publication No. Sho 60-105667).
No. 4,239,850) and oxadiazole compounds (described in US Pat. No. 4,221,970). The amount of the photopolymerization initiator used is preferably 0.01 to 20% by weight, more preferably 0.5 to 5% by weight of the solid content of the coating solution.

[Cholesteric alignment optical thin film] The cholesteric alignment optical thin film can be obtained by aligning and polymerizing the cholesteric liquid crystal composition. The cholesteric liquid crystal composition is applied on a horizontal alignment film on a support, horizontally aligned, and further polymerized,
It is preferable to produce a cholesteric oriented optical thin film.

As the support, a transparent support having a small optical anisotropy is preferably used. Transparent support means that the light transmittance is 80% or more. When the optical anisotropy is small, specifically, the in-plane retardation (Re) is preferably 20 nm or less,
The thickness is more preferably 10 nm or less, and most preferably 5 nm or less. Further, the retardation (Rth) in the thickness direction is preferably 100 nm or less, more preferably 50 nm or less, and 30 nm or less.
Most preferably, it is not more than nm. In-plane retardation (Re) and thickness direction retardation (Rth)
Are respectively defined by the following formulas. Re = (nx−ny) × d Rth = [{(nx + ny) / 2} −nz] × d where nx and ny are in-plane refractive indices of the transparent support, and nz is the thickness of the transparent support. Is the refractive index in the direction, and d is the thickness of the transparent support.

As a material for the support, glass or a polymer is used. Examples of polymers include cellulose esters, polycarbonates, polysulfones, polyethersulfones, polyacrylates and polymethacrylates. Cellulose esters are preferred, acetyl cellulose is more preferred, and triacetyl cellulose is most preferred. The polymer film used as the support is preferably formed by a solvent casting method. The thickness of the support is preferably from 20 to 500 μm, more preferably from 50 to 200 μm. In order to improve the adhesion between the support and the layer provided thereon, the support may be subjected to a surface treatment (eg, a glow discharge treatment, a corona discharge treatment, an ultraviolet (UV) treatment, a flame treatment). An adhesive layer (undercoat layer) may be provided on the support.

The horizontal alignment film is formed by rubbing an organic compound (preferably a polymer), obliquely depositing an inorganic compound, forming a layer having microgrooves, or an organic compound (eg, a LB film) by the Langmuir-Blodgett method (LB film). ω
-Tricosanoic acid, dioctadecylmethyl ammonium chloride, methyl stearylate). Further, an alignment film in which an alignment function is generated by application of an electric field, a magnetic field, or light irradiation is also known. An alignment film formed by rubbing a polymer is particularly preferable. The rubbing treatment is performed by rubbing the surface of the polymer layer several times with paper or cloth in a certain direction.

The cholesteric liquid crystalline composition can be applied onto the alignment film by a known method (eg, a curtain coating method,
Extrusion coating, direct gravure coating, die coating, spin coating,
Dip coating, spray coating, slide coating). The applied cholesteric liquid crystalline composition is heated to orient the liquid crystalline composition. The heating temperature is preferably 200 ° C. or lower, more preferably 130 ° C. or lower. By the alignment treatment, an optical thin film is obtained in which the polymerizable rod-like nematic liquid crystalline compound is twist-aligned so as to have a helical axis in a direction substantially perpendicular to the plane of the optical thin film.

The aligned polymerizable rod-like nematic liquid crystal compound is further polymerized. Photopolymerization is preferred over thermal polymerization. Light irradiation is preferably performed using ultraviolet light.
The irradiation energy is 20 mJ / cm ^{2 to} 50 J / cm
² , preferably 100 to 800 mJ / cm
More preferably, it is ² . Light irradiation may be performed under heating conditions to promote the photopolymerization reaction. A cholesteric alignment optical thin film containing a polymer having a rod-shaped nematic liquid crystal repeating unit represented by the following formula (II) and an optically active compound (when the optically active compound does not have a polymerizable group), or A cholesteric alignment optical thin film (when the optically active compound has a polymerizable group) containing a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active structure is obtained.

(II) -L¹-Ar¹-(L^Two-Ar^Two)_m-(L^Three
-Ar^Three)_n-L^Four-Ar^Four-L^Five-In formula (II), Ar¹, Ar^Two, Ar^ThreeAnd Ar
^FourAre each independently an aromatic ring or an aromatic heterocyclic ring
It is. Definitions and examples of aromatic rings and aromatic heterocycles
Is the same as in formula (I). In the formula (II), L¹You
And L^FiveIs independently a single bond or -O-,
-CO-, -alkylene group- and combinations thereof
And a divalent linking group selected from L¹And L^FiveIs
L of the formula (I)¹And L^FiveAnd Q¹And Q ^TwoPolymerizability
Linking group whose group has been changed (for a polymerizable group
Alkylene group for epoxy group, alkyleneoxy for epoxy group
Group) is bonded. In the formula (II), L
^Two, L^ThreeAnd L^FourAre each independently a single bond,
A rukenylene group- or -alkynylene group-, wherein L
^Two, L^ThreeAnd L^FourHas at least two ethynylene bonds
Is included. L^Two, L^ThreeAnd L^FourDefinitions and examples
Is L of the formula (I)^Two, L^ThreeAnd L^FourIs the same as formula
In (II), m and n are 0 or 1. formula
As in (I), m is 0 or 1 and n is 0 (such as an aromatic ring).
Or the number of aromatic heterocycles is preferably 2 or 3).
More preferably, m is 1 and n is 0 (aromatic ring or aromatic complex)
Most preferably, the number of rings is 3).

The thickness of the cholesteric oriented optical thin film is
It is preferably 0.1 to 50 μm, more preferably 0.5 to 10 μm, still more preferably 1 to 5 μm, still more preferably 2 to 5 μm, and still more preferably 3 to 5 μm. Is most preferred. The cholesteric alignment optical thin film is 400 to 8
It is preferable to have the selective reflection wavelength region in the range of 50 nm, and it is more preferable that the selective reflection wavelength region is in the range of 400 to 700 nm.

[Cholesteric Oriented Optical Thin Film] A cholesteric polarizing plate can be obtained by laminating a cholesteric oriented optical thin film and a λ / 4 plate. Regarding the λ / 4 plate, see JP-A-8-14616 and JP-A-10-68816.
And 10-90521.

[Cholesteric Reflective Polarizing Plate] A cholesteric reflective polarizing plate can be obtained by providing a reflecting plate on a cholesteric oriented optical thin film. As the reflecting plate, a polymer film covered with a metal plate or a metal foil is generally used.

[Liquid crystal display device] The cholesteric reflective polarizing plate can be used in various display modes, for example, TN (Twisted Nem).
atic), IPS (In-Plane Switching), FLC (Ferr
oelectric Liquid Crystal), OCB (Optically Comp
ensatory Bend), STN (Supper Twisted Nemati)
c), VA (Vertically Aligned) or HAN (Hyb
rid Aligned Nematic). In a transmission type liquid crystal display device, two polarizing plates are provided on both sides of a liquid crystal cell, and in a reflection type liquid crystal display device, one polarizing plate is provided between a liquid crystal cell and a reflection plate. A polarizing plate generally includes a polarizing film and a protective film. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine-based polarizing film and the dye-based polarizing film are generally manufactured using a polyvinyl alcohol-based film. The protective films are provided on both surfaces of the polarizing film. The transparent support of the optical compensation sheet can also function as a protective film on one side of the polarizing film. As a protective film for the other polarizing film, it is preferable to use a cellulose ester film having high optical isotropy, particularly a triacetyl cellulose film.

[0058]

[Example 1] A polyimide-based horizontal alignment film having a thickness of 0.5 µm was formed on a glass plate by spin coating. The surface of the alignment film is rubbed, and a polymerizable rod-like nematic liquid crystal compound (4) and a methyl ethyl ketone solution (cholesteric liquid crystal composition) of the following optically active compound (chiral agent) are applied by spin coating. A 1.5 μm thin film was formed. Δn of the polymerizable rod-like nematic liquid crystal compound (4) was 0.38.

[0059]

Embedded image

The thin film was heated to 120 ° C. to form a cholesteric monodomain phase. 600 mJ / cm ²
UV light was applied to polymerize the terminal vinyl group of the polymerizable rod-like nematic liquid crystalline compound (4) to fix the alignment state. Thus, a cholesteric alignment optical thin film was produced. The transmittance of the cholesteric oriented optical thin film was measured. FIG. 2 shows the measurement results. Half width is almost 100
nm.

Comparative Example 1 A 0.5 μm-thick polyimide-based horizontal alignment film was formed on a glass plate by spin coating. The surface of the alignment film is rubbed, and the following polymerizable rod-like nematic liquid crystal compound (x) and the following optically active compound (chiral agent) in a methyl ethyl ketone solution (cholesteric liquid crystal composition) are applied by spin coating.
A thin film having a thickness of 1.5 μm was formed. Δn of the polymerizable rod-like nematic liquid crystal compound (x) was 0.46.

[0062]

Embedded image

The thin film was heated to 120 ° C. to form a cholesteric phase. Further, an ultraviolet ray of 600 mJ / cm ² was irradiated to polymerize the terminal vinyl group of the polymerizable rod-like nematic liquid crystal compound (x), thereby fixing the alignment state. Thus, a cholesteric alignment optical thin film was produced. When the transmittance of the cholesteric alignment optical thin film was measured,
It showed little selective reflection.

Example 2 A 0.5 μm-thick polyimide horizontal alignment film was formed on a glass plate by spin coating. The surface of the alignment film is rubbed, and a polymerizable rod-like nematic liquid crystal compound (4) and a solution of the optically active compound (chiral agent) used in Example 1 in methyl ethyl ketone (cholesteric liquid crystal composition) are applied by spin coating. Then, a thin film having a thickness of 4.5 μm was formed. 145 thin films
C. to form a cholesteric monodomain phase. Further, an ultraviolet ray of 600 mJ / cm ² was irradiated to polymerize the terminal vinyl group of the polymerizable rod-like nematic liquid crystal compound (4) to fix the alignment state. Thus, a cholesteric alignment optical thin film was produced. The transmittance of the cholesteric oriented optical thin film was measured. FIG. 3 shows the measurement results. The half width was approximately 250 nm.

Example 3 A 0.5 μm-thick polyimide horizontal alignment film was formed on a glass plate by spin coating. The surface of the alignment film is rubbed, and a polymerizable rod-like nematic liquid crystal compound (4) and a methyl ethyl ketone solution (cholesteric liquid crystal composition) of the following polymerizable optically active compound (chiral agent) are applied by spin coating.
A thin film having a thickness of 1.5 μm was formed.

[0066]

Embedded image

The thin film was heated to 120 ° C. to form a cholesteric monodomain phase. 600 mJ / cm ²
UV light was applied to polymerize the terminal vinyl group of the polymerizable rod-like nematic liquid crystalline compound (4) to fix the alignment state. Thus, a cholesteric alignment optical thin film was produced. The FWHM of the transmittance of the cholesteric alignment optical thin film was almost 100 nm.

Example 4 Using the cholesteric alignment optical thin film produced in Example 1, a transmission type liquid crystal display device having the structure shown in FIG. 1A was produced. With the obtained liquid crystal display device, a bright image was obtained even with a relatively small amount of light.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display device using a cholesteric reflective polarizing plate.

FIG. 2 is a graph showing the transmittance of the cholesteric alignment optical thin film produced in Example 1.

FIG. 3 is a graph showing the transmittance of the cholesteric alignment optical thin film produced in Example 2.

[Explanation of symbols]

 Reference Signs List 1 cholesteric alignment optical thin film 2 λ / 4 plate 3, 3a, 3b polarizing plate 4 liquid crystal cell BL backlight RP reflector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C07D 303/24 C07D 303/24 4C056 493/04 101 493/04 101C 4C071 521/00 521/00 4F071 C08F 212 / 00 C08F 212/00 4H006 216/12 216/12 4H027 216/36 216/36 4J100 C09K 19/38 C09K 19/38 G02B 5/30 G02B 5/30 G02F 1/13 500 G02F 1/13 500 1/1335 1/1335 1/1337 1/1337 // C08J 5/18 C08J 5/18 F term (reference) 2H049 BA03 BA05 BA07 BA08 BA16 BA42 BA43 BB03 BB63 BC04 BC22 2H090 HB08Y HC02 HC05 KA18 LA09 LA20 MA02 MA04 MB01 MB06 2H091 FA01Z FA08X FA08Z FA14Z FB02 FC01 FC04 FC23 FD06 FD08 GA06 KA02 LA30 4C031 BA05 DA04 4C048 AA01 BB09 BB11 CC01 CC02 UU03 UU10 XX04 XX10 4C056 AA0 1 AB01 AC02 AD03 AE02 CA28 CC01 CD06 4C071 AA01 BB01 CC12 DD04 EE05 FF15 GG01 HH05 JJ01 LL05 4F071 AA36 AA38 AA42 AA62 AC04 AC10 AC19 AF12 BB02 BD11 BB12 BB13 BC01 4H006 AA01 AA03 GPB FCB FCB FCB GPA GPA 4J100 AT13P AT15P AT22P BA02P BA03P BA04P BA05P BA13P BA15P BA16P BA29P BA40P BA42P BA50P BA52P BA56P BB01P BB03P BB07P BC04P BC42P BC43P BC44P BC48P BC49P BC53P BC54P BC65P BC69P BC73BC79

Claims (17)

[Claims] 1. A polymerizable rod-like nematic liquid crystal compound represented by the following formula (I). (I) Q ¹ -L ¹ -Ar ^1- (L ² -Ar ² ) _m- (L ³ -Ar ³ )
_n -L ⁴ -Ar in ⁴ -L ⁵ -Q ^{2 Formula, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
m and n are 0 or 1; and Q ¹ and Q ² are each independently a polymerizable group. 2. The polymerizable rod-like nematic liquid crystal compound according to claim 1, which exhibits a nematic phase having Δn of 0.25 or more. 3. The polymerizable rod-like nematic liquid crystal compound according to claim 1, wherein the polymerizable group of Q ¹ and Q ² is an ethylenically unsaturated group or an epoxy group. 4. A cholesteric liquid crystal composition comprising a polymerizable rod-like nematic liquid crystal compound represented by the following formula (I) and an optically active compound. (I) Q ¹ -L ¹ -Ar ^1- (L ² -Ar ² ) _m- (L ³ -Ar ³ )
_n -L ⁴ -Ar in ⁴ -L ⁵ -Q ^{2 Formula, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
m and n are 0 or 1; and Q ¹ and Q ² are each independently a polymerizable group. 5. The cholesteric liquid crystalline composition according to claim 4, wherein the optically active compound has a polymerizable group. 6. The cholesteric liquid crystalline composition according to claim 5, wherein the polymerizable group of the optically active compound is an ethylenically unsaturated group or an epoxy group. 7. A cholesteric alignment optical thin film comprising a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active compound. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. 8. A cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active structure. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. 9. A rod-like nematic liquid crystalline repeating unit comprising:
9. The cholesteric-oriented optical thin film according to claim 7, wherein the cholesteric-oriented optical thin film is twisted so as to have a helical axis in a direction substantially perpendicular to the plane of the optical thin film. 10. The cholesteric alignment optical thin film according to claim 7, wherein a horizontal alignment film having a function of substantially horizontally aligning the rod-like nematic liquid crystal molecules is provided adjacent to the optical thin film. 11. The cholesteric optically oriented thin film according to claim 7, which has a selective reflection wavelength region within a range of 400 to 850 nm. 12. A cholesteric alignment optical thin film comprising a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active compound, and λ / 4:
Cholesteric polarizing plate having a plate. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. 13. A cholesteric polarizing optical plate having a cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and an optically active structure, and a λ / 4 plate. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. 14. A cholesteric reflection plate comprising a reflector, a cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystal repeating unit represented by the following formula (II) and an optically active compound, and a λ / 4 plate in this order. Type polarizing plate. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. 15. A cholesteric reflection comprising a reflector, a cholesteric alignment optical thin film containing a polymer having a rod-like nematic liquid crystalline repeating unit represented by the following formula (II) and a polymer having an optically active structure, and a λ / 4 plate in this order. Type polarizing plate. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. 16. A reflector, a cholesteric alignment optical thin film comprising a polymer having a rod-like nematic liquid crystal repeating unit represented by the following formula (II) and an optically active compound:
A liquid crystal display device having a / 4 plate and a liquid crystal cell in this order. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or —O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1. 17. A cholesteric alignment optical thin film comprising a reflector, a rod-shaped nematic liquid crystal repeating unit represented by the following formula (II) and a polymer having an optically active structure:
A liquid crystal display device having four plates and a liquid crystal cell in this order. ^{(II) -L 1 -Ar 1 -} (L 2 -Ar 2) m - (L 3 -Ar 3) n -
L ⁴ -Ar ⁴ -L ⁵ - ^{wherein, Ar 1, Ar 2, Ar} 3 and Ar ⁴ each independently, an aromatic ring or aromatic heterocyclic ring; L ¹
And L ⁵ are each independently a single bond or -O
-, - CO -, - alkylene group - and a divalent linking group selected from their combinations; L ^2, L ³ and L ⁴ are each independently a single bond, - alkenylene - or - alkynylene group - an at least contains two ethynylene bond to L ^2, L ³ and L ^4;
And m and n are 0 or 1.