Retarder and circular polarizer

• US 20040109114A1
• Filed: 08/06/2003
• Published: 06/10/2004
• Est. Priority Date: 08/07/2002
• Status: Abandoned Application

• Current Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Ito, Tadashi, Takeuchi, Hiroshi
• Application Number:
  US10/634,906
• Publication Number:
  US 20040109114A1
• Time in Patent Office: Days
• US Class Current: 349/117
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133541 Circular polarisers
• CPC Class Codes: G02F 2203/02 reflective

Abstract

A retarder comprising a substrate having a longitudinal direction and a first and second optically anisotropic layers respectively formed of a composition comprising a rod-like liquid-crystalline compound, in which the rod-like molecules are aligned homogeneously. The first layer substantially generates a phase difference of π at 550 nm, and the second layer substantially generates a phase difference of π/2 at 550 nm. An in-plane slow axis of the first layer and the longitudinal direction cross substantially at +30 degrees, an in-plane slow axis of the second layer and the longitudinal direction cross substantially at −30 degrees, and the slow axis of the second layer and the slow axis of the first layer cross substantially at 60 degrees. A circular polarizer comprising the retarder and a linear polarizer film having a transparent axis inclined at 45 degrees relative to the longitudinal direction is also disclosed.

Claims

1. A retarder comprising:

a substrate having a longitudinal direction,

a first optically anisotropic layer formed of a composition comprising a rod-like liquid-crystalline compound, in which the rod-like molecules are aligned homogeneously, and substantially generating a phase difference of π

at 550 nm, and

a second optically anisotropic layer formed of a composition comprising a rod-like liquid-crystalline compound, in which the rod-like molecules are aligned homogeneously, and substantially generating a phase difference of π

/2 at 550 nm;

wherein an in-plane slow axis of the first optically anisotropic layer and the longitudinal direction of the substrate cross substantially at +30 degrees, an in-plane slow axis of the second optically anisotropic layer and the longitudinal direction of the substrate cross substantially at −

30 degrees, and the in-plane slow axis of the second optically anisotropic layer and the in-plane slow axis of the first optically anisotropic layer cross substantially at 60 degrees.

2. The retarder of claim 1, wherein a rubbing axis of an alignment layer for predetermining an orientation angle of the rod-like molecules in the first optically anisotropic layer and the longitudinal direction of the substrate cross substantially at +30 degrees, and a rubbing axis of an alignment layer for predetermining an orientation angle of the rod-like molecules in the second optically anisotropic layer and the longitudinal direction of the substrate cross substantially at −

30 degrees.

3. The retader of claim 1, wherein at least one of the first and second optically anisotropic layers is formed of a composition comprising a rod-like liquid-crystalline compound denoted by Formula (I) bellow:

Q¹—

L¹—

Cy¹—

L²—

(Cy²—

L³)_n—

Cy³—

L⁴—

Q²  

 

Formula (I)

where Q¹ and Q²respectively denote a polymerizable group;

L¹ and L⁴ respectively denote a divalent linking group, L² and L³ respectively denote a single bond or divalent linking group;

Cy¹, Cy², and Cy³ respectively denote a divalent cyclic group; and

n is 0, 1 or 2.

4. The retader of claim 1, wherein at least one of the first and second optically anisotropic layers is formed of a composition comprising a compound denoted by Formula (V) bellow:

(Hb—

L⁵²—

)_nB⁵¹  

 

Formula (V)

where Hb represents a C6-40 aliphatic group, or oligosiloxanoxy group having a C6-40 aliphatic group;

L⁵² is a single bond or divalent linking group;

B⁵¹ is an n-valent group showing an excluded volume effect and comprising at least three rings and n is an integer from 2 to 12.

5. The retader of claim 4, wherein B⁵¹ is an n-valent group denoted by Formula (V-a);

(−

Cy⁵¹—

L⁵³—

)_n Cy⁵²  

 

Formula (V-a)

where Cy⁵¹ is a divalent cyclic group;

L⁵³ is a divalent linking group selected from the group consisting of a single bond, -alkylene-, -alkenylene-, -alkynylene-, —

O—

, —

S—

, —

CO—

, —

NR—

, —

SO₂— and

any combinations thereof;

Cy⁵² is an n-valent cyclic group; and

n is an integer from 2 to 12.

6. A process for preparing a retarder comprising:

(i) a step of preparing a layer on or above a surface of a substrate having a longitudinal direction and rubbing a surface of the layer in a direction at +30 degrees relative to the longitudinal direction of the substrate, to prepare a first alignment layer capable of aligning rod-like liquid-crystalline molecules in a direction parallel to a rubbing axis,

(ii) a step of applying a composition comprising a rod-like liquid-crystalline compound to the rubbed surface of the first alignment layer and aligning rod-like molecules homogenously in a direction parallel to the rubbing axis of the first alignment layer, to prepare a first optically anisotropic layer generating substantially a phase difference of π

at 550 nm,

(iii-1) a step of preparing a layer on or above the surface of the substrate and rubbing a surface of the layer in a direction at −

30 degrees relative to the longitudinal direction of the substrate, namely, in a direction crossing the rubbing axis of the first alignment layer at 60 degrees, to prepare a second alignment layer capable of aligning rod-like liquid-crystalline molecules in a direction parallel to a rubbing axis, or

(iii-2) a step of preparing a layer on or above a rear surface of the substrate and rubbing a surface of the layer in a direction at +30 degrees relative to the longitudinal direction of the substrate, namely, in a direction crossing the rubbing axis of the first alignment layer at 60 degrees, to prepare a second alignment layer capable of aligning rod-like liquid-crystalline molecules in a direction parallel to a rubbing axis, and

(iv) a step of applying a composition comprising a rod-like liquid-crystalline compound to the rubbed surface of the second alignment layer and aligning rod-like molecules homogenously in a direction parallel to the rubbing axis of the second alignment layer, to prepare a second optically anisotropic layer generating substantially a phase difference of π

/2 at 550 nm.

7. The process of claim 6, wherein at least one of the rod-like liquid-crystalline compounds used in the first and second optically anisotropic layers is denoted by Formula (I) bellow:

Q¹—

L¹—

Cy¹—

L²—

(Cy²—

L³)_n—

Cy³—

L⁴—

Q²  

 

Formula (I)

where Q¹ and Q² respectively denote a polymerizable group;

L¹ and L⁴ respectively denote a divalent linking group, L² and L³ respectively denote a single bond or divalent linking group;

Cy¹, Cy², and Cy³ respectively denote a divalent cyclic group; and

n is 0, 1 or 2.

8. The process of claim 6, wherein at least one of the compositions for the first and second optically anisotropic layers comprises a compound denoted by Formula (V) bellow:

(Hb—

L⁵²—

)_nB⁵¹  

 

Formula (V)

where Hb represents a C6-40 aliphatic group, or oligosiloxanoxy group having a C6-40 aliphatic group;

L⁵² is a single bond or divalent linking group;

B⁵¹ is an n-valent group showing an excluded volume effect and comprising at least three rings and n is an integer from 2 to 12.

9. The process of claim 6, wherein B⁵¹ is an n-valent group denoted by Formula (V-a);

(—

Cy⁵¹—

L⁵³—

)_n Cy⁵²  

 

Formula (V-a)

where Cy⁵¹ is a divalent cyclic group;

L⁵³ is a divalent linking group selected from the group consisting of a single bond, -alkylene-, -alkenylene-, -alkynylene-, —

O—

, —

S—

, —

CO—

, —

NR—

, —

SO₂— and

any combinations thereof;

Cy⁵² is an n-valent cyclic group; and

n is an integer from 2 to 12.

10. A circular polarizer comprising:

a linear polarizer film having a transparent axis substantially inclined at +45 degrees or −

45 degrees relative to a longitudinal direction thereof,

a substrate having a longitudinal direction,

a first optically anisotropic layer formed of a composition comprising a rod-like liquid-crystalline compound, in which the rod-like molecules are aligned homogeneously, and substantially generating a phase difference of π

at 550 nm, and

a second optically anisotropic layer formed of a composition comprising a rod-like liquid-crystalline compound, in which the rod-like molecules are aligned homogeneously, and substantially generating a phase difference of π

/2 at 550 nm;

wherein an in-plane slow axis of the first optically anisotropic layer and the longitudinal direction of the substrate cross substantially at +30 degrees, an in-plane slow axis of the second optically anisotropic layer and the longitudinal direction of the substrate cross substantially at −

30 degrees, and the in-plane slow axis of the second optically anisotropic layer and the in-plane slow axis of the first optically anisotropic layer cross substantially at 60 degrees.

11. The circular polarizer of claim 10, wherein a rubbing axis of an alignment layer for predetermining an orientation angle of the rod-like molecules in the first optically anisotropic layer and the longitudinal direction of the substrate cross substantially at +30 degrees, and a rubbing axis of an alignment layer for predetermining an orientation angle of the rod-like molecules in the second optically anisotropic layer and the longitudinal direction of the substrate cross substantially at −

30 degrees.

12. The circular polarizer of claim 10, wherein at least one of the first and second optically anisotropic layers is formed of a composition comprising a rod-like liquid-crystalline compound denoted by Formula (I) bellow:

Q¹—

L¹—

Cy¹—

L²—

(Cy²—

L³)_n—

Cy³—

L⁴—

Q²  

 

Formula (I)

where Q¹ and Q² respectively denote a polymerizable group;

L¹ and L⁴ respectively denote a divalent linking group, L² and L³ respectively denote a single bond or divalent linking group;

Cy¹, Cy², and Cy³ respectively denote a divalent cyclic group; and

n is 0, 1 or 2.

13. The circular polarizer of claim 10, wherein at least one of the first and second optically anisotropic layers is formed of a composition comprising a compound denoted by Formula (V) bellow:

(Hb—

L⁵²—

)_nB⁵¹  

 

Formula (V)

where Hb represents a C6-40 aliphatic group, or oligosiloxanoxy group having a C6-40 aliphatic group;

L⁵² is a single bond or divalent linking group;

B⁵¹ is an n-valent group showing an excluded volume effect and comprising at least three rings and n is an integer from 2 to 12.

14. The circular polarizer of claim 13, wherein B⁵¹ is an n-valent group denoted by Formula (V-a);

(—

Cy⁵¹—

L⁵³—

)_n Cy⁵²  

 

Formula (V-a)

where Cy⁵¹ is a divalent cyclic group;

L⁵³ is a divalent linking group selected from the group consisting of a single bond, -alkylene-, -alkenylene-, -alkynylene-, —

O—

, —

S—

, —

CO—

, —

NR—

, —

SO₂— and

any combinations thereof;

Cy⁵² is an n-valent cyclic group; and

n is an integer from 2 to 12.

15. A process for preparing a circular polarizer comprising:

(i) a step of preparing a layer on or above a surface of a substrate having a longitudinal direction and rubbing a surface of the layer in a direction at +30 degrees relative to the longitudinal direction of the substrate, to prepare a first alignment layer capable of aligning rod-like liquid-crystalline molecules in a direction parallel to a rubbing axis,

(ii) a step of applying a composition comprising a rod-like liquid-crystalline compound to the rubbed surface of the first alignment layer and aligning rod-like molecules homogenously in a direction parallel to the rubbing axis of the first alignment layer, to prepare a first optically anisotropic layer generating substantially a phase difference of π

at 550 nm,

(iii-1) a step of preparing a layer on or above the surface of the substrate and rubbing a surface of the layer in a direction at −

30 degrees relative to the longitudinal direction of the substrate, namely, in a direction crossing the rubbing axis of the first alignment layer at 60 degrees, to prepare a second alignment layer capable of aligning rod-like liquid-crystalline molecules in a direction parallel to a rubbing axis, or

(iii-2) a step of preparing a layer on or above a rear surface of the substrate and rubbing a surface of the layer in a direction at +30 degrees relative to the longitudinal direction of the substrate, namely, in a direction crossing the rubbing axis of the first alignment layer at 60 degrees, to prepare a second alignment layer capable of aligning rod-like liquid-crystalline molecules in a direction parallel to a rubbing axis,

(iv) a step of applying a composition comprising a rod-like liquid-crystalline compound to the rubbed surface of the second alignment layer and aligning rod-like molecules homogenously in a direction parallel to the rubbing axis of the second alignment layer, to prepare a second optically anisotropic layer generating substantially a phase difference of π

/2 at 550 nm, and

(v) a step of laminating a linear polarizer film, having a transparent axis substantially inclined at +45 degrees or −

45 degrees relative to a longitudinal direction thereof, on or above the surface or the rear surface of the substrate, so that the longitudinal directions of the linear polarizer film and of the substrate are identical.

16. The process of claim 15, wherein the first and second optically anisotropic layers are prepared on or above the surface of the substrate and the linear polarizer film is laminated on or above the surface of the substrate.

17. The process of claim 15, wherein the first and second optically anisotropic layers are prepared on or above the surface of the substrate and the linear polarizer film is laminated on or above the rear surface of the substrate.

18. The process of claim 15, wherein at least one of the rod-like liquid-crystalline compounds used in the first and second optically anisotropic layers is denoted by Formula (I) bellow:

Q¹—

L¹—

Cy¹—

L²—

(Cy²—

L³)_n—

Cy³—

L⁴—

Q²  

 

Formula (I)

where Q¹ and Q² respectively denote a polymerizable group;

L¹ and L⁴ respectively denote a divalent linking group, L² and L³ respectively denote a single bond or divalent linking group;

Cy¹, Cy², and Cy³ respectively denote a divalent cyclic group; and

n is 0, 1 or 2.

19. The process of claim 15, wherein at least one of the composition used for the first and second optically anisotropic layers comprises a compound denoted by Formula (V) bellow:

(Hb—

L⁵²—

)_nB⁵¹  

 

Formula (V)

where Hb represents a C6-40 aliphatic group, or oligosiloxanoxy group having a C6-40 aliphatic group;

L⁵² is a single bond or divalent linking group;

B⁵¹ is an n-valent group showing an excluded volume effect and comprising at least three rings and n is an integer from 2 to 12.

20. The process of claim 19, wherein B⁵¹ is an n-valent group denoted by Formula (V-a);

(—

Cy⁵¹—

L⁵³—

)_n Cy⁵²  

 

Formula (V-a)

where Cy⁵¹ is a divalent cyclic group;

L⁵³ is a divalent linking group selected from the group consisting of a single bond, -alkylene-, -alkenylene-, -alkynylene-, —

O—

, —

S—

, —

CO—

, —

NR—

, —

SO₂— and

any combinations thereof;

Cy⁵² is an n-valent cyclic group; and

n is an integer from 2 to 12.