JPH11293252A - Cholesteric liquid crystal laminate - Google Patents

Abstract

(57) [Problem] To provide a novel cholesteric liquid crystal laminate which is thin and excellent in light use efficiency. SOLUTION: This film is formed from at least two layers of cholesteric alignment films having different helical pitch sizes, and at least one layer of the film is 4'-hydroxy-4.
-Cholesteric liquid crystalline polyester composition containing 50 to 99.5% by weight of a liquid crystalline polyester having a stilbene carboxylic acid unit, a dicarboxylic acid unit functioning as a mesogen such as 4,4'-stilbene carboxylic acid, and a catechol unit. Is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel cholesteric liquid crystal laminate having a small thickness and excellent light use efficiency.

[0002]

2. Description of the Related Art In recent years, selective reflection, which is a specific property of a cholesteric liquid crystal phase, has been applied to various fields including the optical field. For example, a cholesteric liquid crystal laminate has been developed as a member for improving and improving the brightness of a liquid crystal display device. The laminate was obtained by laminating cholesteric liquid crystalline polymer films, but had poor light use efficiency. In order to increase the light use efficiency, it is conceivable to laminate a cholesteric liquid crystal polymer film having a high birefringence (Δn). When a liquid crystal that normally exhibits cholesteric liquid crystallinity is formed into a film or a thin film, the liquid crystal molecules are oriented parallel to the film surface, and the cholesteric layer is also parallel to the film surface. When light enters the film surface at an angle, only circularly polarized light of a specific wavelength is selectively reflected according to the cholesteric pitch. That is, a film / thin film obtained by fixing the cholesteric liquid crystal can be essentially a selective reflection filter. Center wavelength of selective reflection (λs)
Is defined by the helical pitch of the cholesteric liquid crystal (P: the film thickness when twisted by 360 °) and the average refractive index (N), and the selective reflection bandwidth (Δλ) is determined by the birefringence (Δn) of the cholesteric liquid crystal. Dependent.

[0003]

(Equation 1)

The value of the birefringence Δn of the liquid crystal is usually 0.1 to
The selective reflection bandwidth Δλ at 590 nm is usually 30 to 100 nm (assuming N = 1.7). However, in order to obtain a value greatly exceeding this, Δn is determined by a unique molecular structure. Need to be increased. Since Δn depends on the polarizability of molecules and the orientational order parameter, molecules with high polarizability causing optical anisotropy,
It is known that the improvement is achieved by a compound having a high electron density, such as a benzene ring, a polycyclic aromatic, an ethylene-acetylene chain group, or a terminal cyano group, which is a conjugated molecule. Examples of such a low-molecular liquid crystal include M.I. Hird et al. (M. Hird et. Al, Liquid)
Crystals, 1993, 15, 123). However, there is no known polymer liquid crystal having such a high Δn. As described above, in the conventional cholesteric liquid crystal laminate, the use efficiency of light is low because the birefringence (Δn) of the film constituting the laminate is low, and the laminate is used as a member for improving brightness. In this case, there is also a problem that the viewing angle dependence of the color is increased, and an improvement has been desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a cholesteric liquid crystalline polyester composition containing a nematic liquid crystalline polyester having a specific structural unit as an essential component is formed into a film. By developing a laminate having one layer, it is possible to provide a cholesteric liquid crystal laminate having improved light use efficiency and improved color viewing angle dependency.

[0006]

That is, the first aspect of the present invention is as follows.
Is formed from at least two layers of cholesteric alignment films having different helical pitches, and at least one layer of the film has the following liquid crystalline polyester of 50 to 9
The present invention relates to a cholesteric liquid crystal laminate, which is a cholesteric alignment film formed from a cholesteric liquid crystal polyester composition containing 9.5% by weight. [Liquid-Crystalline Polyester] It has the following structural units (A), (B) and (C) as essential structural units, and optionally has at least one structure selected from structural units (D), (E) and (F) Liquid crystalline polyester having units.

[0007]

Embedded image [Where R represents H, F, Cl, Br or an alkyl group or an alkoxyl group having 1 to 5 carbon atoms, and R ′ represents H,
F, Cl, Br or an alkyl group having 1 to 5 carbon atoms, and n represents 1 or 2] 20 to 80 mol%

[0008]

Embedded image Represents one or more structural units selected from the group consisting of:
0-40 mol%

[0009]

Embedded image 10-40 mol%

[0010]

Embedded image Represents one or more structural units selected from the group consisting of:
-10 mol%

[0011]

Embedded image Represents one or more structural units selected from the group consisting of:
~ 20 mol%

[0012]

Embedded image At least one structural unit selected from the group consisting of
R ″ represents a C _{1 to} C ₂₀ linear or side chain alkyl group, and n represents 1 or 2.] 0 to 30 mol%

A second aspect of the present invention is a liquid crystal display device comprising at least a light source / cholesteric liquid crystal layer / quarter wavelength plate / lower polarizing plate / driving liquid crystal cell / upper polarizing plate, wherein the cholesteric liquid crystal layer Is the first cholesteric liquid crystal laminate described above.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The present invention is formed from at least two layers of cholesteric alignment films having different helical pitch sizes, and at least one layer of the cholesteric alignment film comprises a cholesteric liquid crystal polyester composition containing a specific amount of a nematic liquid crystal polyester described below. It is a cholesteric alignment film to be formed. The nematic liquid crystalline polyester has structural units (A), (B),
(C) as an essential structural unit, optionally a structural unit (D),
It has at least one structural unit selected from (E) and (F). The structural unit (A) has an alkyl-substituted, alkoxy-substituted, halogen-substituted, α-substituted 4′-hydroxy-4-stilbenecarboxylic acid as a basic skeleton.
A unit derived from an alkyl-substituted product, an α, α′-dialkyl-substituted product, or a functional derivative of the carboxylic acid. Here, the various substituents of the carboxylic acid include 4′-hydroxy-3′-methoxy-4-stilbenecarboxylic acid,
4'-hydroxy-3 ', 5'-dimethoxy-4-stilbenecarboxylic acid, 4'-hydroxy-3'-ethoxy-4-stilbenecarboxylic acid, 4'-hydroxy-
3 ′, 5′-diethoxy-4-stilbenecarboxylic acid,
4'-hydroxy-3'-methoxy-5'-ethoxy-
4-stilbenecarboxylic acid, 4'-hydroxy-3-methoxy-4-stilbenecarboxylic acid, 4'-hydroxy-3-ethoxy-4-stilbenecarboxylic acid, 4'-hydroxy-3'-methyl-4-stilbenecarboxylic acid acid,
4'-hydroxy-3'-ethyl-4-stilbenecarboxylic acid, 4'-hydroxy-3 ', 5'-dimethyl-4
-Stilbenecarboxylic acid, 4'-hydroxy-3 ',
5'-diethyl-4-stilbenecarboxylic acid, 4'-hydroxy-2'-fluoro-4-stilbenecarboxylic acid, 4'-hydroxy-2'-chloro-4-stilbenecarboxylic acid, 4'-hydroxy-3 ' -Chloro-4-stilbenecarboxylic acid, 4'-hydroxy-2'-bromo-4-stilbenecarboxylic acid, 4'-hydroxy-
3 ′, 5′-difluoro-4-stilbenecarboxylic acid,
4'-hydroxy-3 ', 5'-dichloro-4-stilbenecarboxylic acid, 4'-hydroxy-3', 5'-dibromo-4-stilbenecarboxylic acid, α-methyl-4'-
Hydroxy-4-stilbenecarboxylic acid, α-methyl-
4′-hydroxy-3′-methoxy-4-stilbenecarboxylic acid, α-ethyl-4′-hydroxy-4-stilbenecarboxylic acid, α-ethyl-4′-hydroxy-3 ′
-Methoxy-4-stilbenecarboxylic acid, α, α′-dimethyl-4′-hydroxy-4-stilbenecarboxylic acid, α, α′-diethyl-4′-hydroxy-4-stilbenecarboxylic acid and the like.

As a hydroxycarboxylic acid component other than the structural unit (A) having the same function as the structural unit (A), specifically, 4- (4'-hydroxyphenyl) as the structural unit (E)
A unit derived from benzoic acid, 6-hydroxy-2-naphthalenecarboxylic acid, 4-hydroxybenzoic acid or a functional derivative thereof (eg, an acetoxy compound, an alkyl ester such as a methyl ester) can be contained as necessary. . The structural unit (A) is present in the liquid crystalline polyester at a ratio of usually 20 to 80 mol%, preferably 25 to 75 mol%, more preferably 30 to 70 mol%. When the structural unit (E) is included, the composition ratio (molar ratio) of the structural units (A) and (E) is (A) / (E)
As usually 1/19 to 79/1, preferably 10/20
Although it is determined in the range of -69/1, it is desirable in the present invention that the polyester contains at least 20 mol% of the structural unit (A).

The structural unit (B) is a component that plays a role as a mesogen for exhibiting liquid crystallinity, and specifically includes 4,4′-stilbene dicarboxylic acid, 4,4′-biphenyl dicarboxylic acid, , 6-naphthalenedicarboxylic acid, 4,4'-dicarboxydiphenyl ether, terephthalic acid, bromoterephthalic acid or functional derivatives of these dicarboxylic acids (for example, dialkyl esters such as dimethyl ester and acid chlorides such as dichloride). Is a unit. In the structural unit (B), a monofunctional carboxylic acid component other than the unit, specifically 4′-alkoxy-4-stilbene carboxylic acid or 4- (4′-alkoxyphenyl) benzoic acid as the structural unit (F) , 6
A unit derived from -alkoxy-2-naphthalenecarboxylic acid, 4-alkoxybenzoic acid or a functional derivative thereof (eg, an alkyl ester such as a methyl ester or an acid chloride such as a chloride) can be contained as necessary. . Here, the alkoxy group substituted by the monofunctional carboxylic acid is a linear or side chain unit of C _{1 to} C ₂₀ , specifically, methoxy, ethoxy, n-propoxy, n-butoxy, n -Pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy,
n-nonyloxy, n-decyloxy, n-octadecyloxy, 2-ethylhexyloxy, i-propoxy and the like. The structural unit (B) is
Usually 10 to 40 mol%, preferably 15 to 35 mol%,
More preferably, it is present in a proportion of 20 to 35 mol%.
When the structural unit (F) is included, the structural unit (B),
The composition ratio (molar ratio) of (F) is usually 1/9 to 39/1, preferably 5/10 to 34/1, as (B) / 2 (F).
In the present invention, the polyester preferably contains at least 10 mol% or more of the structural unit (B).

Next, the structural unit (C) is a component that plays a role in fixing the liquid crystal phase under cooling, and specifically, is derived from catechol or a functional derivative of catechol (for example, a derivative such as a diacetoxy compound). Unit. In addition, a diol component other than the unit, specifically, 4,4′-dihydroxystilbene, 4,4′-biphenol, 2,6-dihydroxynaphthalene, hydroquinone, methylhydroquinone or a functional derivative thereof as the structural unit (D) (For example, a derivative derived from a diacetoxy compound or the like), if necessary. The structural unit (C) is
Usually 10 to 40 mol%, preferably 15 to 35 mol%,
More preferably, it is present in a proportion of 20 to 35 mol%.
When the structural unit (D) is included, the structural unit (C),
The composition ratio (molar ratio) of (D) is usually determined as (C) / (D) in the range of 1/9 to 39/1, preferably 5/10 to 34/1. It is desirable in the present invention that the structural unit (C) contains at least 10 mol% or more. The composition ratio (molar ratio) when the structural units (B) and (C) and, if necessary, the structural unit (D) is included, is (B) / (C) or (B) +2 (F) /
It is approximately 1 as (C) + (D), and is usually 45 / 55-55.
55/45, preferably in the range of 48/52 to 52/48. Specific examples of the nematic liquid crystalline polyester used in the present invention are described below.

[0018]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c: 10 to 40 mol%, preferably 15 to 3
5mol%

[0019]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c: 10 to 40 mol%, preferably 15 to 3
5mol%

[0020]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c: 10 to 40 mol%, preferably 15 to 3
5mol%

[0021]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c: 10 to 40 mol%, preferably 15 to 3
5mol%

[0022]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c + d: 10 to 40 mol%, c / d = 1/9
３９39/1, preferably b or c + d: 15-35
mol%, c / d = 5/10 to 34/1

[0023]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c + d: 10 to 40 mol%, c / d = 1/9
３９39/1, preferably b or c + d: 15-35
mol%, c / d = 5/10 to 34/1

[0024]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c + d: 10 to 40 mol%, c / d = 1/9
３９39/1, preferably b or c + d: 15-35
mol%, c / d = 5/10 to 34/1

[0025]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c + d: 10 to 40 mol%, c / d = 1/9
３９39/1, preferably b or c + d: 15-35
mol%, c / d = 5/10 to 34/1

[0026]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 a: 20~80mol%, preferably 30~70mol
% B or c + d: 10 to 40 mol%, c / d = 1/9
３９39/1, preferably b or c + d: 15-35
mol%, c / d = 5/10 to 34/1

[0027]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
H ₃ , OC ₂ H ₅ R ′: H, F, Cl, Br, CH ₃ , C ₂ H ₅ a + d: 20 to 80 mol%, a / d = 1/19 to 79
/ 1, preferably a + d: 30 to 70 mol%, a / d
= 10/20 to 69/1 b or c: 10 to 40 mol%, preferably b or c: 15 to 35 mol%,

[0028]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
H ₃ , OC ₂ H ₅ R ′: H, F, Cl, Br, CH ₃ , C ₂ H ₅ a + d: 20 to 80 mol%, a / d = 1/19 to 79
/ 1, preferably a + d: 30 to 70 mol%, a / d
= 10/20 to 69/1 b or c: 10 to 40 mol%, preferably b or c: 15 to 35 mol%,

[0029]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
H ₃ , OC ₂ H ₅ R ′: H, F, Cl, Br, CH ₃ , C ₂ H ₅ a + d: 20 to 80 mol%, a / d = 1/19 to 79
/ 1, preferably a + d: 30 to 70 mol%, a / d
= 10/20 to 69/1 b or c: 10 to 40 mol%, preferably b or c: 15 to 35 mol%,

[0030]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 R ": CH 3 ~C 20 H 41 a: 20~80mol%, preferably 30~70mol
% B + f / 2 or c: 10 to 40 mol%, preferably 15 to 35 mol%, b / 2f = 1/9 to 39/1, preferably 5/10 to 34/1

[0031]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 R ": CH 3 ~C 20 H 41 a: 20~80mol%, preferably 30~70mol
% B + f / 2 or c: 10 to 40 mol%, preferably 15 to 35 mol%, b / 2f = 1/9 to 39/1, preferably 5/10 to 34/1

[0032]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 R ": CH 3 ~C 20 H 41 a: 20~80mol%, preferably 30~70mol
% B + f / 2 or c: 10 to 40 mol%, preferably 15 to 35 mol%, b / 2f = 1/9 to 39/1, preferably 5/10 to 34/1

[0033]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
_{H 3, OC 2 H 5 R} ': H, F, Cl, Br, CH 3, C 2 H 5 R ": CH 3 ~C 20 H 41 a: 20~80mol%, preferably 30~70mol
% B + f / 2 or c: 10 to 40 mol%, preferably 15 to 35 mol%, b / 2f = 1/9 to 39/1, preferably 5/10 to 34/1

[0034]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
H ₃ , OC ₂ H ₅ R ′: H, F, Cl, Br, CH ₃ , C ₂ H ₅ R ″: CH _{3 to} C ₂₀ H ₄₁ a + e: _{20 to} 80 mol%, a / e = 1/19 to 79
/ 1, preferably a + e: 30 to 70 mol%, a / e
= 10/20 to 69/1; b + f / 2 or c: 10
40 mol%, preferably 15 to 35 mol%, b / 2
f = 1 / 9-39 / 1, preferably 5 / 10-34 / 1

[0035]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
H ₃ , OC ₂ H ₅ R ′: H, F, Cl, Br, CH ₃ , C ₂ H ₅ R ″: CH _{3 to} C ₂₀ H ₄₁ a + e: _{20 to} 80 mol%, a / e = 1/19 to 79
/ 1, preferably a + e: 30 to 70 mol%, a / e
= 10/20 to 69/1; b + f / 2 or c: 10
40 mol%, preferably 15 to 35 mol%, b / 2
f = 1 / 9-39 / 1, preferably 5 / 10-34 / 1

[0036]

Embedded image R: H, F, Cl, Br, CH 3, C 2 H 5, OC
H ₃ , OC ₂ H ₅ R ′: H, F, Cl, Br, CH ₃ , C ₂ H ₅ R ″: CH _{3 to} C ₂₀ H ₄₁ a + e: _{20 to} 80 mol%, a / e = 1/19 to 79
/ 1, preferably a + e: 30 to 70 mol%, a / e
= 10/20 to 69/1; b + f / 2 or c: 10
40 mol%, preferably 15 to 35 mol%, b / 2
f = 1 / 9-39 / 1, preferably 5 / 10-34 / 1

The nematic liquid crystalline polyester can be obtained by condensation copolymerizing monomer components corresponding to the above structural units. The polymerization method is not particularly limited, and can be synthesized by applying a polymerization method known in the art, for example, a melt polymerization method or a solution polymerization method. When a nematic liquid crystalline polyester is synthesized by a melt polymerization method, for example, a predetermined amount of 4′-acetoxy-3 ′
-Methoxy-4-stilbenecarboxylic acid (structural unit (A) -forming monomer), 4,4'-stilbenedicarboxylic acid (structural unit (B) -forming monomer), and catechol diacetate (structural unit (C) -forming monomer) The desired polyester can be easily obtained by polymerizing under high temperature, reduced pressure or high vacuum. Where the structural units (A), (B), (C) and optionally (D)
The charge ratio (molar ratio) of the monomer component constituting at least one structural unit selected from (E) and (F) is A / (B + C), A / (B + C + D), A / (B +
C + D + 2F), (A + E) / (B + C), (A + E)
/ (B + C + D) or (A + E) / (B + C + D +
The value of 2F) is usually 20/80 to 80/20, preferably 25/75 to 75/25, more preferably 30/80.
It is in the range of 70 to 70/30. The value of A / E is 1/19 to 79/1, preferably 10/20 to 69.
/ 1 range. The value of B / 2F is 1/9 to
39/1, preferably in the range of 5/10 to 34/1. The value of B / C or (B + 2F) / (C + D) is approximately 1, and is usually in the range of 45/55 to 55/45, preferably 48/52 to 52/48. Further, the value of C / D is from 1/9 to 39/1, preferably 5
/ 10 to 34/1.

[0038] The polymerization conditions are not particularly limited, but are usually 150-350 ° C, preferably 200-300 ° C, and the reaction time is 30 minutes or more, preferably about 1-40 hours. It is desirable to carry out the polymerization reaction under normal pressure. In order to promote the polymerization reaction, 1-methylimidazole, amines such as 4-dimethylaminopyridine,
Alkali metal salt, Fe, Mn, Ti, Co, Sb, Sn
Such metal salts may be used alone or in combination. Further, the molecular weight of the nematic liquid crystalline polyester can be easily adjusted by controlling the polymerization time and the like as in the ordinary condensation reaction. Here, the molecular weight of the nematic liquid crystalline polyester is such that the logarithmic viscosity [ηinh] measured at 30 ° C. in a phenol / tetrachloroethane mixed solvent (60/40 weight ratio) is usually 0.05 to 0.5, preferably 0.1 to 0.5. 07-0.4, more preferably 0.1-0.3. When the value of ηinh is lower than 0.05, the strength may be weakened, which may cause a practical problem.
On the other hand, if it is higher than 0.5, the fluidity in the liquid crystal state may decrease, and it may be difficult to obtain uniform alignment.

Further, when a nematic liquid crystalline polyester is produced by a solution polymerization method, for example, a predetermined amount of 4'-
Hydroxy-3′-methoxy-4-stilbenecarboxylic acid (structural unit (A) forming monomer), 4,4′-stilbene dicarboxylic acid (structural unit (B) forming monomer), catechol (structural unit (C) forming monomer) Is dissolved in a solvent and heated. Alternatively, the desired polyester can be easily obtained by dissolving in pyridine or the like and heating in the presence of arylsulfonyl chloride / dimethylformamide or chlorophosphate diphenyl / dimethylformamide.

Further, when synthesizing the liquid crystalline polyester by the solution polymerization method, the structural units (A), (B),
The charging ratio (molar ratio) of the monomer component constituting (C) and optionally at least one structural unit selected from (D), (E) and (F) is the same as in the above melt polymerization method,
Specifically, A / (B + C), A / (B + C + D), A /
(B + C + D + 2F), (A + E) / (B + C), (A
+ E) / (B + C + D) or (A + E) / (B + C
+ D + 2F), usually 20/80 to 80/20,
Preferably it is in the range of 25/75 to 75/25, more preferably 30/70 to 70/30. The value of A / E is 1/19 to 79/1, preferably 10/20.
６９69/1. The value of B / 2F is 1
/ 9 to 39/1, preferably 5/10 to 34/1. The value of B / C or (B + 2F) / (C + D) is approximately 1, and is usually 45/55 to 55/4.
5, preferably in the range of 48/52 to 52/48.
Further, the value of C / D is in the range of 1/9 to 39/1, preferably 5/10 to 34/1.

The solvent used in the solution polymerization is not particularly limited. For example, halogen solvents such as o-dichlorobenzene, dichloroethane and tetrachloroethane, dimethyl sulfoxide (DMSO), dimethylformamide (DMF), N-methylpyrrolidone (NMP ) And ether solvents such as tetrahydrofuran (THF) and dioxane. Examples of the acid acceptor include, but are not particularly limited to, pyridine, triethylamine, and tripropylamine. The reaction conditions for the solution polymerization are not particularly limited, but are usually 50 to 200 ° C., preferably 60 to 150 ° C., and the reaction time is usually 1 hour or more, preferably 2 hours to 10 hours.

Next, the optically active compound to be imparted to impart a twist to the above nematic liquid crystalline polyester will be described. A typical example is an optically active low molecular compound. Any compound having optical activity can be used in the present invention, but an optically active liquid crystal compound is desirable from the viewpoint of compatibility with the liquid crystalline polyester. Specifically, the following low molecular compounds can be exemplified.

[0043]

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[0044]

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Examples of the optically active compound include an optically active polymer compound. Any polymer compound having an optically active group in the molecule can be used, but a polymer compound exhibiting liquid crystallinity is desirable from the viewpoint of compatibility with the above nematic liquid crystal polyester. Examples thereof include liquid crystalline polyacrylates, polymethacrylates, polymalonates, polysiloxanes, polyesters, polyamides, polyesteramides, polycarbonates, polypeptides, and celluloses having an optically active group. Of these, aromatic-based optically active polyesters are most preferred because of their compatibility with the nematic liquid crystalline polyester described above. In particular,

[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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Examples can be given as examples. The ratio of the optically active group in these optically active polyesters is usually from 2 to 80 mol%, preferably from 5 to 7 mol%.
The range is 0 mol%. The preparation of the cholesteric liquid crystalline polyester composition used in the present invention is performed by mixing the nematic liquid crystalline polyester and the optically active compound at a predetermined ratio, respectively, by a method such as solid mixing, solution mixing or melt mixing. Can be. The proportion of the optically active compound in the composition varies depending on the ratio of the optically active group in the optically active compound or the twisting force of the optically active compound when the nematic liquid crystal is twisted. Wt% range, preferably 1-4
The range is 0% by weight. If less than 0.5 wt%,
There is a possibility that a sufficient twist cannot be given to the nematic liquid crystal. If it is more than 70 wt%, the orientation may be adversely affected.

The cholesteric liquid crystalline polyester composition adjusted as described above undergoes a film forming step described below, and is then laminated to obtain a cholesteric liquid crystalline laminate. Here, the cholesteric liquid crystalline polyester composition used in the present invention forms a uniform and monodomain cholesteric alignment in a liquid crystal state. Further, when the composition in a liquid crystal state is cooled at an arbitrary cooling rate, substantially no phase transition to a crystal phase occurs. That is, the composition provided in the present invention exhibits a monodomain cholesteric alignment state in a liquid crystal state, and the alignment state can be easily fixed by cooling. In order to stably immobilize the cholesteric phase, in the case of the liquid crystal phase series, if a crystal phase exists at a lower temperature than the cholesteric phase, it will inevitably pass through the crystal phase when cooling for immobilization. As a result, the cholesteric orientation obtained once is destroyed. The cholesteric liquid crystalline polyester composition used in the present invention basically exhibits a monodomain cholesteric phase in a liquid crystal state, and exhibits a glass state at a liquid crystal transition temperature or lower. Therefore, by cooling the molecular alignment state in the liquid crystal state, that is, the cholesteric alignment state to a liquid crystal transition temperature (glass transition point) or lower, the liquid crystal can be maintained as it is.

The cholesteric liquid crystalline polyester composition can be formed into a film by applying the polyester composition on an alignment substrate, followed by heat treatment and cooling. Thus, a cholesteric alignment film is formed on the alignment substrate. You.

The alignment substrate has the ability to orient the cholesteric liquid crystalline polyester composition into a desired cholesteric structure, heat resistance and solvent resistance within a range that does not impair the object of the present invention. There is no particular limitation as long as it has a releasability that can be peeled off at the interface with the oriented film. Examples of such an alignment substrate include polyimide, polyamide imide, polyamide, polyether imide, polyether ether ketone, polyether ketone, polyketone sulfide, polyether sulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, and polyacetal. , Polycarbonate, acrylic resin, polyvinyl alcohol, cellulosic plastics, epoxy resin, phenolic resin, etc., various plastic films or sheets are directly rubbed on the surface of a substrate or polyimide film rubbed on these films or sheets And a substrate having an oriented thin film such as a rubbed polyvinyl alcohol film. Kill.

Examples of the method of applying the cholesteric liquid crystalline polyester composition to the alignment substrate include a solution application using a solution of the polyester composition and a melt application using the composition in a molten state. As the solvent used for the solution coating, although it cannot be said unconditionally due to the composition ratio of the cholesteric liquid crystalline polyester composition and the like, it is usually a halogenated hydrocarbon such as chloroform, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, orthodichlorobenzene, and the like. Mixed solvents with phenols, ketones, ethers,
Dimethylformamide, dimethylacetamide, dimethylsulfoxide, N-methylpyrrolidone, sulfolane,
A polar solvent such as cyclohexane can be used.
The concentration of the solution is appropriately selected depending on the composition ratio of the cholesteric liquid crystalline polyester composition to be used, but is usually in the range of 5 to 50% by weight, preferably 10 to 50% by weight.
A range of 30% by weight is desirable.

Next, this cholesteric liquid crystalline polyester composition solution is applied on an alignment substrate. Examples of the coating method include a spin coating method, a roll coating method, a gravure coating method, a curtain coating method, a slot coating method, and a dipping pulling method. After the application, the solvent is removed by drying, and heat treatment is performed at a predetermined temperature for a predetermined time to form a uniform monodomain cholesteric alignment. Since the viscosity of the cholesteric liquid crystalline polyester composition is preferably low in order to assist the alignment by the interface effect, the heat treatment temperature is preferably high. However, if the temperature is too high, the cost may increase and the workability may deteriorate, which is not preferable. In addition, depending on the composition ratio of the cholesteric liquid crystalline polyester composition, a liquid crystal phase (cholesteric phase)
Since it has an isotropic phase in a higher temperature part, cholesteric orientation cannot be obtained even when heat treatment is performed in this temperature range. As described above, according to the characteristics of the cholesteric liquid crystalline polyester composition to be used, the isotropic phase is higher than the liquid crystal transition point (in the case of a liquid crystalline polymer which is in a glassy state below the liquid crystal transition point, the liquid crystal transition point = glass transition point). It is desirable to perform a heat treatment at a temperature at which a liquid crystal phase below the transition point to the liquid crystal phase is exhibited. Usually, it is arbitrarily selected from the range of 50 to 300 ° C, preferably 100 to 250 ° C.

The time required to obtain a sufficient alignment in the liquid crystal state on the alignment substrate depends on the composition ratio and the molecular weight of the cholesteric liquid crystalline polyester composition and cannot be determined unconditionally, but is usually from 10 seconds to 100 minutes, preferably from 10 seconds to 100 minutes. Is 30
Seconds to 60 minutes. If the time is shorter than 10 seconds, the cholesteric alignment may be insufficient. When the time is longer than 100 minutes, the transparency of the obtained cholesteric alignment film may be reduced. The same cholesteric alignment can be obtained by applying the cholesteric liquid crystalline polyester composition in a molten state to an alignment substrate and then performing a heat treatment.

By cooling the cholesteric alignment obtained as described above and fixing it without impairing the cholesteric alignment in a liquid crystal state, a cholesteric alignment film can be obtained on an alignment substrate. The cholesteric liquid crystalline polyester composition provided in the present invention can be immobilized without impairing the cholesteric orientation by cooling to a temperature below the liquid crystal transition point, that is, below the glass transition point. Generally, when a liquid crystalline polymer having a crystal phase in a lower temperature part than a liquid crystal phase is used, the alignment in the liquid crystal state may be broken, but such a phenomenon cannot occur in the present invention. The cooling rate is not particularly limited, and the cooling can be performed simply by taking out from the heating atmosphere into an atmosphere having a glass transition temperature or lower. In order to increase the production efficiency, forced cooling such as air cooling or water cooling may be performed.

The thickness of the cholesteric alignment film after immobilization is not particularly limited, but is usually 0.3 to 30 μm.
Preferably, the range is 0.5 to 10 μm. When the film thickness is smaller than 0.3 μm, for example, when used as a liquid crystal display element, a desired optical characteristic effect may not be obtained. If the thickness is more than 30 μm, uniform cholesteric alignment may not be obtained, which is not desirable.

The cholesteric alignment film having a fixed orientation obtained as described above cannot be said unconditionally because it varies depending on the composition ratio of the cholesteric liquid crystalline polyester composition, but the helical pitch is usually 0.05 to 5 μm.
Range. The center wavelength is usually 300 to 800 n
m. Further, the selective reflection area is usually 300 to
The range is 800 nm.

Further, the cholesteric alignment film obtained from the cholesteric liquid crystalline polyester composition cannot be specified unconditionally due to the composition ratio of the composition, but the single-layer film usually has a birefringence of 0.1 at a wavelength of 590 nm. It has a unique physical property value of 2 or more and 0.3 or more depending on the composition ratio, which has been difficult to achieve with the self-alignment type polymer liquid crystal until now. The physical properties as described above make it possible to obtain a cholesteric oriented film having a desired value by adjusting the composition ratio of the cholesteric liquid crystalline polyester composition and the like.

A cholesteric liquid crystalline laminate is obtained using at least one cholesteric alignment film obtained as described above. The film other than the cholesteric alignment film is not particularly limited as long as it has a different helical pitch.

In the present invention, the cholesteric liquid crystal laminate is preferably manufactured by the following steps (FIG. 1).
See). Cholesteric alignment film 1 on alignment substrate (1)
(2) (State A in FIG. 1) is bonded to the removable substrate (4) via an adhesive (3) on the surface opposite to the alignment substrate (State B in FIG. 1). After bonding the removable substrate (4), the alignment substrate (1)
Is peeled off, and the cholesteric alignment film 1 (2) is transferred to the removable substrate (state C in FIG. 1). A translucent support substrate (6) is adhered to the surface of the cholesteric alignment film 1 (2) opposite to the removable substrate (4) via an adhesive (3) (D state in FIG. 1). After bonding the translucent support substrate (6), the removable substrate (4) is peeled off, and the cholesteric alignment film 1 (2) is transferred to the support substrate (6) (state E in FIG. 1). The cholesteric alignment film 2 (7) formed on the alignment substrate is bonded to the removable substrate (9) via an adhesive (8) on the surface opposite to the alignment substrate (corresponding to the above). After bonding the removable substrate (9), the alignment substrate is peeled off, and the cholesteric alignment film 2 (7) is transferred to the removable substrate (9) (corresponding to the above). The surface of the cholesteric alignment film 1 (2) opposite to the translucent support substrate (6) via the adhesive (3) on the surface opposite to the removable substrate (9) of the cholesteric alignment film 2 (7). (F state in FIG. 1). Translucent support substrate (6) / adhesive (5) / cholesteric alignment film 1 (2) / adhesive (3) / cholesteric alignment film 2 (7) / adhesive (8) / removable substrate (9) After obtaining the laminate (G state in FIG. 1), the removable substrate (9) is peeled from the cholesteric alignment film 2 (7) (H state in FIG. 1). Repeat the above steps as necessary,
The cholesteric alignment films are adhered to each other via an adhesive and laminated on one support substrate (I, J, and K states in FIG. 1). In the figure, 10 is a cholesteric oriented film 3, 11
Denotes an adhesive, and 12 denotes a removable substrate.

In the above step, the cholesteric alignment films are preferably laminated in the order of the helical pitch of the liquid crystal layer. For example, when the cholesteric alignment film 1 is laminated on a supporting substrate, the cholesteric alignment film 2
Must have a helical pitch larger than the helical pitch of the oriented film 1. Further, when the cholesteric oriented film 3 is laminated on the oriented film 2, the oriented film 3 is laminated so as to have a helical pitch larger than the helical pitch of the oriented film 2.

Here, the adhesive in the above steps will be described. As an adhesive used when bonding the cholesteric alignment film and the removable substrate,
There is no particular limitation as long as they can adhere to each other and have the property of being peelable from the removable substrate. Such an adhesive may be any one that shows optical isotropy after curing, and may be, for example, a photo-curing type by a curing means.
An adhesive such as an electron beam curing type or a thermosetting type may be used. Above all, photo-curing type mainly composed of acrylic oligomer,
An electron beam-curable adhesive, an epoxy resin-based photocurable, and an electron beam-curable adhesive are preferably used. The form of adhesion between the cholesteric alignment film and the removable substrate is not particularly limited, but it is common to arrange a layered adhesive layer between the liquid crystal film and the substrate. Although the thickness of the adhesive layer is not particularly limited, it is usually 1 μm to
It is about 30 μm. In addition, various additives such as an antioxidant and an ultraviolet absorber may be added to the adhesive as long as the effects of the present invention are not impaired.

Next, the re-peelable substrate is not particularly limited as long as it has re-peelability and has self-supporting properties. In the present invention, a plastic film having releasability is usually desirable. Here, the term "removability" as used in the present invention means that in the state where the cholesteric alignment film and the removable substrate are bonded via an adhesive, the releasability can be removed at the interface between the adhesive and the removable substrate. Preferably, when the cholesteric alignment film transferred to the removable substrate and the cholesteric alignment film transferred to the support substrate are bonded so as to be adjacent to each other via an adhesive, the removable substrate comes into direct contact with the adhesive. Can be peeled off at the interface.
As the plastic film to be a removable substrate as described above, the peel strength at the interface with the adhesive (after curing) (18)
(0 ° peeling test, peeling speed 30 cm / min), usually 0.5 to 80 gf / 25 mm, preferably 2 to 50 g
Those having a peel strength of f / 25 mm can be suitably used.

Specific examples of the plastic film serving as the removable substrate include polyethylene, polypropylene,
Olefin resins such as methylpentene-1 resin, polyamide, polyimide, polyamideimide, polyetherimide, polyetherketone, polyetheretherketone, polyethersulfone, polyketonesulfide, polysulfone, polystyrene, polyphenylenesulfide, polyphenyleneoxide, polyethylene Examples include terephthalate, polybutylene terephthalate, polyarylate, polyacetal, polycarbonate, polyvinyl alcohol, and cellulosic plastics. Further, in the present invention, in order to impart a suitable removability, the plastic film is coated with silicone on its surface, an organic thin film or an inorganic thin film is formed, a chemical treatment, a corona discharge treatment, etc. It is also possible to use a material subjected to such a physical treatment as described above. In the present invention, polypropylene, polyether ether ketone, polyethylene terephthalate, polycarbonate, and plastic films obtained by subjecting these film surfaces to silicone treatment or corona discharge treatment are desirable because they have both an adhesive and appropriate adhesiveness and peelability.

Next, the support substrate in the above is not particularly limited as long as it is a light-transmitting plastic film exhibiting suitable adhesive strength with an adhesive and having self-supporting properties. Specifically, polyethylene, polypropylene, olefinic resins such as 4-methylpentene-1 resin, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate,
Polyarylate, polyacetal, polycarbonate,
Examples include polyvinyl alcohol, triacetyl cellulose, diacetyl cellulose and the like. In addition, if necessary, the surface of these translucent plastic films is subjected to a physical treatment such as a mat treatment or a sand treatment, or an overcoat composed of an organic thin film or an inorganic thin film, as long as the object of the present invention is not impaired. A film having a layer or the like, a film in which an additive such as an ultraviolet absorber is blended in the film, or the like can also be used.

In the above steps, and
The method of adhering the cholesteric alignment film to the support substrate and the removable substrate via the adhesive as described above and bonding them together is not particularly limited. Usually, both are bonded by an arbitrary method, and thereafter, the adhesive is cured.

Next, a method for peeling the alignment substrate and the removable substrate in the above and steps will be described. After the adhesive is cured, the transfer of the cholesteric alignment film to the removable substrate can be performed by separating the alignment substrate at the interface with the alignment film. The peeling method is not particularly limited, and a suitable method is selected according to the adhesion between the cholesteric alignment film and the alignment substrate. For example, when the alignment substrate is a film, the edges of the alignment substrate and the cholesteric alignment film can usually be grasped by hand or peeled off with an adhesive tape such as a vinyl tape. Also, when peeling, it is recommended that the oriented substrate is peeled in a direction of usually 90 to 180 degrees, preferably almost 180 degrees. Similarly, a method for peeling the removable substrate from the cholesteric liquid crystal film also selects an appropriate method according to the adhesion between the alignment film and the substrate.

Through the above steps, a cholesteric liquid crystal laminate can be obtained. In the laminate,
Any number of layers can be laminated without sandwiching the alignment substrate, which is an essential member when forming the cholesteric alignment film, between the cholesteric alignment films. Therefore, it is possible to reduce the thickness of the laminate, and since there is substantially only an adhesive layer showing optical isotropy between the cholesteric alignment films, a laminate excellent in optical properties can be obtained. .

In the above-mentioned cholesteric liquid crystal laminate, as the combination of the cholesteric alignment films, films having different helical pitches are appropriately combined in accordance with the optical characteristics of the intended use. Here, as the application, a cholesteric liquid crystal laminate used as a brightness enhancement member used for a liquid crystal display element will be described. In this use, the cholesteric liquid crystal laminate of the present invention is usually used in a liquid crystal display device comprising at least a light source / brightness improving member / quarter wavelength plate / lower polarizing plate / driving liquid crystal cell / upper polarizing plate. It is arranged as a brightness enhancement member.

When used in the above-mentioned applications, the cholesteric liquid crystalline laminate has a short wavelength end of 300 to 400 nm and a long wavelength end of 700 to 8 in the selective reflection wavelength region of the laminate.
It is preferable that the layers have a total selective reflection bandwidth of 350 nm or more and are stacked according to the size of the helical pitch. Here, when a cholesteric liquid crystal laminate that does not satisfy the above conditions is provided in the liquid crystal display element, there is a possibility that the brightness of the liquid crystal display cannot be improved. In addition, unnecessary coloring may occur. Further, in the liquid crystal display device, it is desirable that the cholesteric alignment film constituting the laminate be disposed between the light source and the quarter-wave plate such that the plane with the smallest pitch is closest to the light source side.

The light source is desirably a surface light source in order to make the entire display screen uniform brightness. In a normal liquid crystal display device, in order to uniformly irradiate light from a cold cathode tube of a light source to the entire display device, a reflection plate, a light guide plate, a diffusion plate,
A member such as a lens sheet is used. Further, a backlight system integrating the characteristics of these members is designed to be a surface light source with high in-plane uniformity of illuminance. Examples of the backlight system include an EL type backlight, a fluorescent tube, and an edge type backlight. An edge light type backlight having a feature of being lightweight and thin is often used (for example, Kazuo Murauchi, Plastic Age) March issue, pp., 149-154,
1997). In the present invention, the type of the backlight system is not particularly limited as long as it can be used for a liquid crystal display device or the like, without being limited to the above-described backlight system.

The 波長 wavelength plate is not particularly limited as long as it is a transparent film that converts circularly polarized light emitted from the cholesteric liquid crystal laminate into linearly polarized light. A film formed of a single transparent film or a laminate thereof is preferable, and a retardation film is also included in this category. The material of the transparent film is polycarbonate,
Polyvinyl alcohol, polysulfone, polyethylene,
Examples include, but are not limited to, polypropylene, polystyrene, polyarylate, polyethylene terephthalate, triacetyl cellulose, diacetyl cellulose, polyethylene-ethyl vinyl alcohol, and the like. Further, as the transparent film, a liquid crystalline polymer film having a fixed liquid crystal orientation, a film made of a mixture of the material of the transparent film and a low molecular or high molecular liquid crystal, or the like can be used.

The driving liquid crystal cell used in the present invention includes a TN type, an STN type, a ferroelectric liquid crystal type, an antiferroelectric liquid crystal type, a TFD type and a TFT type. Is not limited to this. Further, it is preferable to use a polarizing plate having a high degree of polarization, such as an iodine-based or dye-based absorption linear polarizer.

In the case where the cholesteric liquid crystal laminate of the present invention is arranged as a brightness improving member in the above-described liquid crystal display element, substantially only a cholesteric liquid crystal layer is laminated on one support film substrate. Therefore, it is useful as a thinned liquid crystal display device. In addition, it has at least one cholesteric alignment film formed from a cholesteric liquid crystalline polyester composition containing a specific amount of a nematic liquid crystalline polyester having a specific structural unit as an essential component. The arrangement has an effect of being extremely excellent in light use efficiency and viewing angle characteristics. In the above liquid crystal display device, the viewing angle compensation film and the color compensation film are provided between one or both of the liquid crystal cell for driving and the upper polarizer or between the liquid crystal cell and the quarter wave plate. A functional optical film such as the above can be sandwiched. By providing the film or the like, it is possible to obtain a liquid crystal display device in which a wider viewing angle and a wider contrast are achieved.

[0085]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. Note that the present invention is not limited to the embodiments. Embodiment 1 FIG. Nematic liquid crystalline polyester A (birefringence 0.441) and optically active polyester B were synthesized, and three compositions having different composition ratios were prepared. A tetrachloroethane solution containing each composition at a concentration of 15% by weight was applied on a rubbed polyetherketone film by a spinner, and then 200 ° C., 10 minutes, and 180 ° C.
Heat treatment was performed for 0 minutes to obtain cholesteric alignment films 1, 2, and 3 having a thickness of 5 μm. The film has a wavelength of 5
The birefringence (Δn) at 90 nm was 0.410.

[0086]

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[0087]

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(1) Film 1 composition ratio (weight ratio) A / B = 79.7 / 20.3 Selected wavelength region 602 to 758 nm Center wavelength 680 nm (2) Film 2 composition ratio (weight ratio) A / B = 74 9.9 / 25.1 Selected wavelength region 487-613 nm Center wavelength 550 nm (3) Film 3 composition ratio (weight ratio) A / B = 69.0 / 31.0 Selective reflection region 394-496 nm Center wavelength 445 nm

A cholesteric liquid crystal film 3 having a center wavelength of 445 nm and formed on a polyetheretherketone film (alignment substrate) was cut into a size of 20 × 30 cm, and a commercially available light-cured film was formed on the film 3 using a bar coater. An adhesive composed of a mold-type acrylic oligomer was applied to a thickness of 5 μm. Next, the peel strength at the interface with the cured acrylic resin adhesive layer (18
After a corona discharge treated polypropylene film (removable substrate) having a thickness of 38 μm and a size of 25 × 35 cm having a corona discharge treatment of 2 gf / 25 mm and a corona discharge treated surface side of 2 gf / 25 mm, they were bonded together with a desktop laminator. The adhesive was cured by irradiating ultraviolet rays. After curing the adhesive, polyetheretherketone film (oriented substrate)
, The polyetheretherketone film was peeled in the 180 ° direction at the interface with the cholesteric liquid crystal film 3, and the film 3 was transferred onto a polypropylene film.

Next, an acrylic pressure-sensitive adhesive was applied to the air side of the film 3 so as to have a thickness of 5 μm, and a thickness of 80 μm was applied.
A triacetylcellulose film (support substrate) having a size of 35 × 45 cm and a size of 35 × 45 cm was adhered using a desktop laminator, and irradiated with ultraviolet rays to cure the adhesive. After the adhesive between the film 3 and the triacetylcellulose film is cured, the end of the polypropylene film (removable substrate) is held by hand, and the polypropylene film and the cured acrylic adhesive are oriented in the 180 ° direction. At the interface with

An acrylic adhesive was applied to a thickness of 5 μm using a bar coater on the side of the cholesteric liquid crystal film 3 transferred to the triacetyl cellulose from which the polypropylene film had been peeled off. A film 2 having a center wavelength of 550 nm, which has been peeled off from the polyetheretherketone film (orientable substrate) and transferred to a polypropylene film (removable substrate), is adhered to the cholesteric liquid crystal film 3 using a desktop laminator so as to be adjacent thereto. Irradiation cured the adhesive. After the adhesive is cured, the end of the polypropylene film (removable substrate) adhered to the film 2 is held by hand and pulled in the 180 ° direction, and the polypropylene film is bonded to the cured acrylic adhesive layer. Peeled off at the interface.

Next, an acrylic adhesive was applied to a thickness of 5 μm using a bar coater on the side of the triacetyl cellulose / film 3 / film 2 from which the polypropylene film of the film 2 was peeled off. A film 1 having a center wavelength of 680 nm, which was transferred to a polypropylene film (removable substrate) in the same manner as described above, was attached to a cholesteric liquid crystal film 2 using a desktop laminator so as to be adjacent to the cholesteric liquid crystal film 2, and was irradiated with ultraviolet rays for adhesion. After the adhesive between the film 2 and the film 1 has been cured, the end of the polypropylene film adhered to the film 1 is held by hand, and the polypropylene film is bonded in a 180 ° direction with the film and the cured acrylic adhesive. Peeled off at the interface.

Next, an acrylic adhesive was applied to a thickness of 5 μm using a bar coater on the side of the film 1 from which the polypropylene film was peeled, and then a 30 μm-thick polyethylene-ethyl vinyl alcohol (1/4) (A wave plate) was adhered with a desktop laminator, irradiated with ultraviolet rays, and adhered.

The obtained laminate was prepared as follows: triacetyl cellulose (support substrate) / film 3 / film 2 / film 1
/ Polyethylene-ethylvinyl alcohol (1/4 wavelength plate), and the thickness including the cured acrylic adhesive layer substantially existing between the layers was 155 μm. Also, triacetyl cellulose (support substrate) /
The selective reflection wavelength region of the cholesteric laminate composed of film 3 / film 2 / film 1 is 394 nm to 75 nm.
It was 8 nm.

FIG. 2 shows the laminated state of each layer. Next, the obtained laminate was arranged on a liquid crystal display device having a backlight system shown in FIG. 5 (FIG. 6), and the luminance improvement rate and the viewing angle dependency of color were measured. Table 1 shows the results.

Comparative Example 1 Films 1, 2, and 3 used in Example 1 were laminated by the following method. First, films 1, 2, which are oriented on a polyetheretherketone film (orientation substrate)
Sample No. 3 was cut into 20 × 30 cm, and an adhesive made of a commercially available photocurable acrylic oligomer was applied to each film to a thickness of 5 μm using a bar coater.
Next, a triacetyl cellulose film (support substrate) having a thickness of 80 μm and a size of 35 × 45 cm was bonded to the application surface using a desktop laminator, and then irradiated with ultraviolet rays to cure the adhesive. After curing the adhesive,
Hold the end of the polyetheretherketone film 18
By peeling in the 0 ° direction, the film was peeled at the interface with the cholesteric liquid crystalline polymer layer, and the cholesteric liquid crystal films 1, 2, and 3 were transferred to triacetyl cellulose films, respectively.

Next, a 5 μm adhesive of a commercially available photocurable acrylic oligomer was applied to the cholesteric liquid film 3 having a central wavelength of 445 nm transferred to the triacetyl cellulose film. A cholesteric liquid crystal film 2 having a center wavelength of 550 nm transferred to a triacetyl cellulose film on a coating surface was bonded using a desktop laminator so that the liquid crystal films were adjacent to each other, and then the adhesive was cured by irradiating ultraviolet rays. .

After the adhesive between the film 3 and the film 2 is cured, a photo-curable adhesive is applied to a thickness of 5 μm on the surface of the triacetyl cellulose film in contact with the film 2, and triacetyl cellulose is applied thereon. The liquid crystal surface of the cholesteric liquid crystal film 1 having a center wavelength of 680 nm transferred to the film was bonded using a desktop laminator so that the liquid crystal surface of the cholesteric liquid crystal film 1 was in contact with the triacetyl cellulose film surface of the film 2, and the adhesive was cured by irradiating ultraviolet rays.

After curing the adhesive between the film 1 and the triacetylcellulose film in contact with the film 2, the acrylic adhesive was applied to the triacetylcellulose film in contact with the film 1 using a bar coater by 5 μm.
After applying to a thickness of 30 μm,
Ethyl vinyl alcohol (1/4 wavelength plate) was bonded with a desktop laminator, irradiated with ultraviolet light to cure the adhesive, and bonded. The obtained laminate was made of a triacetyl cellulose film (supporting substrate) / film 3 / film 2 / triacetyl cellulose film (supporting substrate) / film 1 / triacetyl cellulose film / polyethylene-ethylvinyl alcohol (1/4 wavelength plate). ), And the thickness including the cured acrylic adhesive layer substantially existing between the respective layers was 310 μm.

FIG. 6 shows the laminated state of each layer. Next, the obtained laminate was arranged on a liquid crystal display device having a backlight system shown in FIG. 5 (FIG. 6), and the luminance improvement rate and the viewing angle dependency of color were measured. Table 1 shows the results.

Comparative Example 2 A triacetylcellulose film (supporting substrate) / film 1 / film 2 / film 3 / polyethylene-ethylvinyl alcohol (except that the order of lamination of the films 1, 2 and 3 was different) (積 層 wavelength plate). The thickness of the obtained laminate is 15 including the cured acrylic adhesive layer substantially existing between the respective layers.
It was 5 μm. FIG. 7 shows the laminated state of each layer. Next, the obtained laminate was disposed on a liquid crystal display device having a backlight system shown in FIG.
The measurement was performed on the viewing angle dependency of the color. Table 1 shows the results.

Embodiment 2 FIG. The following nematic liquid crystalline polyester C and optically active polyester D were synthesized, and three compositions having different composition ratios were prepared. 1 for each composition
A tetrachloroethane solution containing 5% by weight is coated on a rubbed polyimide film by a spinner,
A heat treatment was performed at 200 ° C. for 10 minutes and then at 180 ° C. for 10 minutes, and a cholesteric liquid crystal film 4 having a thickness of 5 μm was obtained.
5 and 6 were obtained. The birefringence (Δn) at 590 nm of the film was 0.38.

[0103]

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[0104]

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(1) Film 4 composition ratio (weight ratio) A / B = 78.8 / 21.2 selective reflection region 598 nm to 752 nm center wavelength 675 nm (2) Film 5 composition ratio (weight ratio) A / B = 73 0.8 / 26.2 Selective reflection region 483 nm to 607 nm Center wavelength 545 nm (3) Film 6 composition ratio (weight ratio) A / B = 67.5 / 32.5 Selective reflection region 390 nm to 490 nm Center wavelength 440 nm

Using the obtained films 4, 5 and 6, according to substantially the same manner as in Example 1, triacetyl cellulose (supporting substrate) / film 6 / film 5 / film 4 / polyethylene-ethylvinyl alcohol film (1/4 wavelength plate) ) Was obtained. In addition, the thickness of the obtained laminated body is 15 including the cured acrylic adhesive layer substantially present in each layer.
It was 5 nm. Also, triacetyl cellulose (supporting substrate) / film 6 / film 5 / film 4
The selective reflection wavelength region of the cholesteric liquid crystal laminate of
It was 390 nm to 752 nm. FIG. 3 shows the laminated state of each layer. Then, the obtained laminate is arranged on a liquid crystal display device having a backlight system shown in FIG. 5 (FIG. 6).
Then, the luminance improvement rate and the viewing angle dependency of the color were measured. Table 1 shows the results.

Embodiment 3 FIG. The following nematic liquid crystalline polyester E and optically active polyester F were synthesized, and three compositions having different composition ratios were prepared. 1 for each composition
An N-methylpyrrolidone solution containing a concentration of 5% by weight is applied on a rubbed polyphenylene sulfide film by a spinner, at 210 ° C. for 10 minutes, and then at 180 ° C.
C. for 10 minutes to obtain cholesteric liquid crystal films 7, 8 and 9 having a thickness of 5 .mu.m. The birefringence (Δn) at 590 nm of the film was 0.40.

[0108]

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[0109]

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(1) Film 7 composition ratio (weight ratio) A / B = 79.6 / 20.4 selective reflection region 597 nm to 747 nm center wavelength 672 nm (2) Film 8 composition ratio (weight ratio) A / B = 74 9.9 / 25.1 selective reflection region 484 nm to 606 nm center wavelength 545 nm (3) Film 9 composition ratio (weight ratio) A / B = 69.0 / 31.0 selective reflection region 391 nm to 489 nm center wavelength 440 nm

Using the obtained films 7, 8 and 9, according to Example 1, triacetyl cellulose (supporting substrate) / film 9 / film 8 / film 7 / polyethylene-ethylvinyl alcohol film (1/4 wavelength plate) ) Was obtained. In addition, the thickness of the obtained laminated body is 15 including the cured acrylic adhesive layer substantially present in each layer.
It was 5 nm. Also, triacetyl cellulose (supporting substrate) / film 9 / film 8 / film 7
Of the cholesteric liquid crystal layered product of Example 3 is 3
It was 91 nm to 747 nm.

The film comprising the three cholesteric liquid crystalline polymer layers produced on the triacetyl cellulose film in this manner has a thickness of 155 μm including the cured acrylic resin adhesive layer and the 波長 wavelength plate. there were. FIG.
The laminated state of each layer is shown in FIG. Next, the obtained laminate is
The liquid crystal display device having the backlight system shown in FIG. 5 was arranged (FIG. 6), and the luminance improvement rate and the viewing angle dependency of the color were measured. Table 1 shows the results.

[0113]

[Table 1]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a production process of a cholesteric liquid crystal laminate of the present invention.

FIG. 2 is an explanatory diagram showing a laminated state of the laminated body of Example 1.

FIG. 3 is an explanatory diagram showing a laminated state of a laminated body of Example 2.

FIG. 4 is an explanatory view showing a laminated state of a laminated body according to a third embodiment.

FIG. 5 is an explanatory diagram of a backlight system.

FIG. 6 is an explanatory diagram of a liquid crystal display element.

[Description of Signs] In FIG. 1: 1 Oriented substrate 2 Cholesteric oriented film 1 3, 5, 8, 11 Adhesive 4, 9, 12 Removable substrate 6 Translucent support substrate 7 Cholesteric oriented film 2 10 Cholesteric oriented film 3 In FIG. 2: 13 adhesive 14 cholesteric alignment film 1 center wavelength 68
0 nm 15 Adhesive 16 Cholesteric alignment film 2 Center wavelength 55
0 nm 17 Adhesive 18 Cholesteric alignment film 3 Center wavelength 44
5 nm 19 adhesive 20 translucent support substrate In FIG. 3: 21 adhesive 22 cholesteric alignment film 4 center wavelength 67
5 nm 23 adhesive 24 cholesteric alignment film 5 center wavelength 54
5 nm 25 adhesive 26 cholesteric alignment film 6 center wavelength 44
0 nm 27 adhesive 28 translucent support substrate In FIG. 4: 29 adhesive 30 cholesteric alignment film 7 center wavelength 67
2 nm 31 adhesive 32 cholesteric alignment film 8 center wavelength 54
5 nm 33 adhesive 34 cholesteric alignment film 9 center wavelength 44
5 nm: 1 prism sheet 2 light diffusion film 3 light guide plate 4 light reflection film 5 lamp In FIG. 6: 6 polarizing plate 7 cell 8 polarizing plate 9 1/4 wavelength plate 10 cholesteric Liquid crystal laminate 11 Backlight system

Continued on the front page (51) Int.Cl. ⁶ Identification code FI G02B 1/08 G02B 1/08 5/30 5/30 G02F 1/13 500 G02F 1/13 500

Claims (2)

[Claims] 1. A cholesteric liquid crystalline polyester composition formed from at least two layers of cholesteric alignment films having different helical pitches, wherein at least one layer of the cholesteric liquid crystalline polyester contains 50 to 99.5% by weight of the following liquid crystalline polyester. A cholesteric liquid crystal laminate characterized by being a cholesteric alignment film formed from: [Liquid-Crystalline Polyester] It has the following structural units (A), (B) and (C) as essential structural units, and optionally has at least one structure selected from structural units (D), (E) and (F) Liquid crystalline polyester having units. Embedded image [Where R represents H, F, Cl, Br or an alkyl group or an alkoxyl group having 1 to 5 carbon atoms, and R ′ represents H,
F, Cl, Br or an alkyl group having 1 to 5 carbon atoms, and n represents 1 or 2] 20 to 80 mol% Represents one or more structural units selected from the group consisting of:
0 to 40 mol% 10 to 40 mol% Represents one or more structural units selected from the group consisting of:
-10 mol% Represents one or more structural units selected from the group consisting of:
~ 20 mol% At least one structural unit selected from the group consisting of
R ″ represents a C _{1 to} C ₂₀ linear or side chain alkyl group, and n represents 1 or 2.] 0 to 30 mol% 2. A liquid crystal display device comprising at least a light source / a cholesteric liquid crystal layer / a quarter wavelength plate / a lower polarizer / a driving liquid crystal cell / an upper polarizer, wherein the cholesteric liquid crystal layer is provided. A liquid crystal display device characterized by being a cholesteric liquid crystal laminate of the above.